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255 S. King Street, Suite 800, Seattle, WA 98104 | 206.426.2600 | JACOBSONENGINEERS.COM TECHNICAL INFORMATION REPORT RSD Transportation Center Expansion 420, 444, & 450 Park Ave N Renton, WA 98057 May 21, 2025 PREPARED FOR: Renton School District 7812 South 124th Street Seattle, WA 98178 PREPARED BY: Jacobson Consulting Engineers Sascha Eastman 206.426.2600 sascha@jacobsonengineers.com DEVELOPMENT ENGINEERING HBray 06/12/2025 Surface Water Enginering jfarah 06/12/2025 i Technical Information Report for Renton School District Transportation Expansion JCE Project No. C220041-0132 May 21, 2025 TABLE OF CONTENTS 1. PROJECT OVERVIEW ................................................................................................................................ 3 GENERAL DESCRIPTION .............................................................................................................................. 3 EXISTING CONDITIONS ................................................................................................................................. 3 PROPOSED DRAINAGE SYSTEM ................................................................................................................. 3 2. CONDITIONS AND REQUIREMENTS SUMMARY ......................................................................................... 5 CORE REQUIREMENT #1: DISCHARGE AT THE NATURAL LOCATION .................................................. 5 CORE REQUIREMENT #2: OFFSITE ANALYSIS ......................................................................................... 5 CORE REQUIREMENT #3: FLOW CONTROL FACILITIES.......................................................................... 5 CORE REQUIREMENT #4: CONVEYANCE SYSTEM .................................................................................. 6 CORE REQUIREMENT #5: CONSTRUCTION STORMWATER POLLUTION PREVENTION ................... 6 CORE REQUIREMENT #6: MAINTENANCE AND OPERATIONS ............................................................... 6 CORE REQUIREMENT #7: FINANCIAL GUARANTEES AND LIABILITY.................................................... 6 CORE REQUIREMENT #8: WATER QUALITY FACILITIES ......................................................................... 7 CORE REQUIREMENT #9: ON-SITE BMPS .................................................................................................. 7 SPECIAL REQUIREMENT #1: OTHER ADOPTED AREA-SPECIFIC REQUIREMENTS ........................... 8 SPECIAL REQUIREMENT #2: FLOOD HAZARD AREA DELINEATION ..................................................... 8 SPECIAL REQUIREMENT #3: FLOOD PROTECTION FACILITIES ............................................................ 8 SPECIAL REQUIREMENT #4: SOURCE CONTROLS .................................................................................. 8 SPECIAL REQUIREMENT #5: OIL CONTROL .............................................................................................. 8 SPECIAL REQUIREMENT #6: AQUIFER PROTECTION AREA .................................................................. 9 3. OFFSITE ANALYSIS ................................................................................................................................ 10 FIELD INSPECTION ......................................................................................................................................10 DRAINAGE SYSTEM PROBLEM DESCRIPTIONS .....................................................................................10 UPSTREAM ANALYSIS .................................................................................................................................10 DOWNSTREAM ANALYSIS ..........................................................................................................................10 MITIGATION OF EXISTING OR POTENTIAL PROBLEMS .........................................................................10 4. FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID), AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ......................................................................................................................................................... 11 FLOW CONTROL SYSTEM (PART D) .........................................................................................................11 WATER QUALITY SYSTEM (PART E) .........................................................................................................11 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN ...................................................................................... 13 6. SPECIAL REPORTS AND SUMMARY ........................................................................................................ 15 7. CSWPP ANALYSIS AND DESIGN ............................................................................................................. 16 STANDARD REQUIREMENTS .....................................................................................................................16 RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION ii 8. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ..................................... 17 BOND QUANTITIES WORKSHEET..............................................................................................................17 FLOW CONTROL AND WATER QUALITY FACILITY SUMMARY SHEET AND SKETCH .......................17 DECLARATION OF COVENANT FOR PRIVEATELY MAINTAINED FLOW CONTROL AND WATER QUALITY FACILITIES ....................................................................................................................................17 9. OPERATIONS AND MAINTENANCE MANUAL ....................................................................................... 18 10. FIGURES ......................................................................................................................................... 19 11. APPENDICES ................................................................................................................................... 20 APPENDIX A – BOND QUANTITY WORKSHEET .............................................................................. 20 APPENDIX B – STORMWATER CALCULATIONS ............................................................................. 20 APPENDIX C – STORMWATER POLLUTION PREVENTION PLAN (SWPPP) ...................................... 20 APPENDIX D – FACILITY SUMMARY SHEET, DECLARATION OF COVENANT .................................. 20 RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 3 1. PROJECT OVERVIEW GENERAL DESCRIPTION The following Drainage Report provides the design narrative and discussion for the Renton School District Transportation Expansion project. The stormwater design for the project was based on the requirements outlined in the 2022 City of Renton Water Design Manual (RSWDM). The Renton School District Transportation facility is within the City of Renton jurisdictional limits at 420, 444, & 450 Park Ave N, Renton, WA 98057 (parcel numbers 7224000676, 7224000675, 7564600105). The site is bounded by N 5th St to the north, Garden Ave N to the east, N 4th St to the south, and Park Ave N to the west. See Figure 2 – Vicinity Map. The proposed improvements are primarily located on parcels 7224000676 and 7224000675, and consist of a new paved parking lot with sidewalks, landscaping, and public amenity space at the northwest corner of the site. Additionally, some right-of-way improvements are proposed to remove existing driveways to the parcels and replace them with new concrete sidewalks. EXISTING CONDITIONS The Renton School District Transportation facility is a fully developed site that contains an existing administration building, vehicle maintenance facility, and multiple parking lots for buses, fleet vehicles, staff, and visitors. The existing administration building and vehicle maintenance facility are located in the southwest portion of the site, while the rest of the site is primarily paved parking lots, drive aisles, and pockets of landscaping. The portion of the site to be redeveloped with this project consists of two asphalt parking lots and landscaping. The topography of the existing site is generally flat, sloping gently from south to north at approximately 1 – 2% slope. Stormwater in the existing conditions is collected in a series of catch basins and routed north to the storm system in N 5th Street, following the topography of the site. Geotechnical investigation on site has found site soils to consist of a surface layer of topsoil underlain by existing fill soils, and Holocene Alluvium deposits from the Cedar River. No groundwater was encountered in the most recent geotechnical testing, but was encountered approximately 10 feet below the surface in explorations for the construction of the transportation center in 2007. The project geotechnical engineer anticipates that perched groundwater may be encountered, but proposed improvements and utilities are not deep enough to be impacted by regional groundwater. See project geotechnical report and Figure 9 – Soils Map. Table 1 below summarizes the land cover characteristics of the existing current Disturbed Site Area, see Figure 3 – Existing Conditions TABLE 1 – PROJECT DISTURBED AREA EXISTING SITE CONDITIONS Land Cover Area (AC) Impervious Area 0.278 Landscape Area 0.210 Total Project Area 0.488 % Impervious of Project Area 56.9% PROPOSED DRAINAGE SYSTEM The proposed improvements consist of a new paved parking lot with sidewalks, landscaping, and public amenity space at the northwest corner of the site. New catch basins will be installed to collect surface runoff and route through water quality treatment prior to discharging to the existing storm main in N 5th Street. This project is required to comply with the Peak Rate Flow Control standard, however this project does not increase flows by more RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 4 than 0.15 CFS using a 15-minute timestep therefore flow control is not required for this project. Table 2 below summarizes the land cover characteristics of the proposed project disturbed areas. See Figure 4 – Proposed Conditions and Figure 5 - New + Replaced Impervious Areas. TABLE 2 – DEVELOPED PROJECT SITE CONDITIONS AREA BREAKDOWN Land Cover Area (AC) Impervious Area 0.368 Landscape Area 0.120 Total Project (Disturbed) Area 0.488 % Impervious of Project Area 75.4% RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 5 2. CONDITIONS AND REQUIREMENTS SUMMARY The proposed Renton School District Transportation facility project will result in more than 7,000 square feet of land disturbing activity with the various pavement improvements and will require Full Drainage Review by the City of Renton as directed in Section 1.1.1 of the 2022 Renton Surface Water Design Manual (RSWDM). See Figure 6 – Project Minimum Requirements Flow Chart for how the level of drainage review was determined for this project. This section of the report will address the (9) nine required minimum requirements and (6) six special requirements for Full Drainage Review as set forth by Section 1.1.2.4 of the 2022 RSWDM. CORE REQUIREMENT #1: DISCHARGE AT THE NATURAL LOCATION All storm water runoff and surface water from a project must be discharged at the natural location so as not to be diverted onto or away from downstream properties. The manner in which stormwater runoff and surface water are discharged from the project site must not create a significant adverse impact to downhill properties or drainage facilities (see "Discharge Requirements" below). Drainage facilities as described above means a constructed or engineered feature that collects, conveys, stores, treats, or otherwise manages surface water or stormwater runoff. “Drainage facility” includes, but is not limited to, a constructed or engineered stream, lake, wetland, or closed depression, or a pipe, channel, ditch, gutter, flow control facility, flow control BMP, water quality facility, erosion and sediment control facility, and any other structure and appurtenance that provides for drainage. Note: Projects that do not discharge all project site runoff at the natural location will require an approved adjustment of this requirement (see Section 1.4). CED may waive this adjustment, however, for projects in which only a small portion of the project site does not discharge runoff at the natural location and the runoff from that portion is unconcentrated and poses no significant adverse impact to downstream properties. Runoff from the site currently sheet flows and is collected in catch basins according to the survey and record drawings for the site. The proposed development will not alter existing drainage patterns, and runoff from the site will continue to drain to the existing 24” storm main in N 5th Street as it currently does today. CORE REQUIREMENT #2: OFFSITE ANALYSIS All proposed projects must submit an offsite analysis report that assesses potential offsite drainage and water quality impacts associated with development of the project site, and that proposes appropriate mitigation of those impacts. The initial permit submittal shall include, at minimum, a Level 1 downstream analysis as described in Section 1.2.2.1 of the RSWDM. If impacts are identified, the proposed projects shall meet any applicable problem-specific requirements specified in Section 1.2.2.2 for mitigation of impacts to drainage problems and Section 1.2.2.3 for mitigation of impacts to water quality problems. The project is NOT exempt from performing an Offsite Level 1 Downstream Analysis as the project adds more than 2,000 square feet of new impervious surface, even though the project will create less than 3/4 acres of new pervious surface, AND does not construct or modify a drainage pipe/ditch that is 12 inches or more in size/depth or that receives runoff from a drainage pipe/ditch that is 12 inches or more in size/depth, AND does not contain or lie adjacent to a landslide, steep slope, or erosion hazard area as defined in RMC 4-3-050. Additionally, there are no known Drainage Complaints downstream or adjacent to project property that are related to the Renton School District Transportation facility according to the City of Renton GIS and King County iMap. A Level 1 Downstream Analysis has been performed for this project. See Downstream Analysis in Section 3 Off-Site Analysis of this report and Figure 7 – Offsite Analysis. CORE REQUIREMENT #3: FLOW CONTROL FACILITIES All proposed projects, including redevelopment projects, must provide onsite flow control facilities to mitigate the impacts of storm and surface water runoff generated by new impervious surface, new pervious surface, and replaced impervious surface targeted for flow mitigation as specified in the following sections. Flow control facilities must be provided and designed to perform as specified by the RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 6 area-specific flow control facility requirement in Section 1.2.3.1 of the RSWDM and in accordance with the applicable flow control facility implementation requirements in Section 1.2.3.2. This project is required to comply with the Peak Rate Flow Control standard, however this project does not increase flows by more than 0.15 CFS using a 15-minute timestep therefore flow control is not required for this project. See Appendix B for MGS Flood calculations. CORE REQUIREMENT #4: CONVEYANCE SYSTEM All engineered conveyance system elements for proposed projects must be analyzed, designed, and constructed to provide a minimum level of protection against overtopping, flooding, erosion, and structural failure as specified in the following groups of requirements: • "Conveyance Requirements for New Systems," Section 1.2.4.1 • "Conveyance Requirements for Existing Systems," Section 1.2.4.2 • "Conveyance System Implementation Requirements," Section 1.2.4.3 This project is NOT exempt from considering Conveyance Requirements for New Systems as there are new pipe system additions from the proposed improvements. All new conveyance systems will be designed to meet requirements. CORE REQUIREMENT #5: CONSTRUCTION STORMWATER POLLUTION PREVENTION All proposed projects that will clear, grade, or otherwise disturb the site must provide erosion and sediment controls to prevent, to the maximum extent practicable, the transport of sediment from the project site to downstream drainage facilities, water resources, and adjacent properties. All proposed projects that will conduct construction activities onsite or offsite must provide stormwater pollution prevention and spill controls to prevent, reduce, or eliminate the discharge of pollutants to onsite or adjacent stormwater systems or watercourses. To prevent sediment transport and pollutant discharges as well as other impacts related to land-disturbing and construction activities, Erosion and Sediment Control (ESC) measures and Stormwater Pollution Prevention and Spill Control (SWPPS) measures that are appropriate to the project site must be applied through a comprehensive Construction Stormwater Pollution Prevention (CSWPP) plan as described in Sections 1.2.5.1 and 1.2.5.3 and shall perform as described in Section 1.2.5.2. In addition, these measures, both temporary and permanent, shall be implemented consistent with the requirements in Section 1.2.5.3 that apply to the proposed project. A SWPPP has been prepared for this project and is included in Appendix C of this report. A concept ESC plan with requirements for the Contractor to provide and implement a design for a system to treat construction runoff to no more than 25 NTU’s over baseline is included with the submittal. A baseline will be established at the start of construction and the contractor will be required to maintain levels no greater than 25 NTU’s above this level. See Appendix C for the project SWPPP. CORE REQUIREMENT #6: MAINTENANCE AND OPERATIONS Maintenance and operation of all drainage facilities is the responsibility of the applicant or property owner, except those facilities for which the City assumes maintenance and operation as described below and in RMC 4-6-030.M. Drainage facilities must be maintained and operated in accordance with the maintenance standards in Appendix A of this manual, or other maintenance standards as approved by the City. An operation and maintenance manual is included in Section 10 of this drainage report and will be provided to the School District for all stormwater BMPs proposed for this project that are maintained by the School District. CORE REQUIREMENT #7: FINANCIAL GUARANTEES AND LIABILITY In accordance with RMC 4-6-030, CED shall require all persons constructing any surface water facilities (including flow control/water quality facilities, conveyance systems, erosion control, and road drainage), to post with the City of Renton a bond, assignment of funds or certified check. RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 7 The applicant must also maintain liability insurance as described in this Core Requirement #7. The owner of the proposed project, Renton School District (RSD), is a public agency and is not subject to bonding requirements. The School District will provide a Public Agency Agreement to the City of Renton in lieu of bonding. CORE REQUIREMENT #8: WATER QUALITY FACILITIES All proposed projects, including redevelopment projects, must provide water quality (WQ) facilities to treat the runoff from those new and replaced pollution-generating impervious surfaces and new pollution-generating pervious surfaces targeted for treatment as specified in the following sections. These facilities shall be selected from a menu of water quality facility options specified by the area-specific facility requirements in Section 1.2.8.1 and implemented according to the applicable WQ implementation requirements in Section 1.2.8.2. This project proposes more than 5,000 SF of pollution generating surfaces, therefore enhanced basic water quality treatment is required for this project. Water quality treatment will be provided by a Filterra water quality treatment facility. Presettling directly upstream of the Filterra will be provided by a Contech CDS Separator. See Appendix B for MGS Flood calculations and GULD approval documentation for both facilities. CORE REQUIREMENT #9: ON-SITE BMPS All proposed projects, including redevelopment projects, must provide on-site flow control BMPs to mitigate the impacts of storm and surface water runoff generated by new impervious surface, new pervious surface, existing impervious surfaces, and replaced impervious surface targeted for mitigation as specified in the following sections. On-site BMPs must be selected and applied according to the basic requirements, procedures, and provisions detailed in this section and the design specifications for each BMP in Appendix C, Section C.2. In accordance with the RSWDM, Flow Control BMPs must be evaluated and implemented to the maximum extent feasible. Per section 1.2.9.2, this project site is over 22,000 SF and is subject to evaluating the Large Lot BMP Requirements as detailed in section 1.2.9.2.2 and described below: 1. Full Dispersion – The project site does not contain enough native vegetated surface to fully disperse all impervious surfaces proposed with this project, therefore it is not feasible to implement Full Dispersion for this project. 2. Full Roof Infiltration – No new roof surfaces are proposed with this project, therefore Full Roof Infiltration is not feasible. 3. Full Infiltration –This project is within Zones 1 and 2 of the City’s Aquifer Protection Area which prohibits infiltration BMPs, and geotechnical evaluation shows that infiltration is not feasible due to uncontrolled existing fill soils, therefore Full Infiltration is not feasible for this project. 4. Limited Infiltration – This project is within Zones 1 and 2 of the City’s Aquifer Protection Area which prohibits infiltration BMPs, and geotechnical evaluation shows that infiltration is not feasible due to uncontrolled existing fill soils, therefore Limited Infiltration is not feasible for this project. 5. Bioretention – This project is within Zones 1 and 2 of the City’s Aquifer Protection Area which prohibits infiltration BMPs, and geotechnical evaluation shows that infiltration is not feasible due to uncontrolled existing fill soils, therefore Bioretention is not feasible for this project. 6. Permeable Pavement –This project is within Zones 1 and 2 of the City’s Aquifer Protection Area which prohibits infiltration BMPs, and geotechnical evaluation shows that infiltration is not feasible due to uncontrolled existing fill soils, therefore Permeable Pavement is not feasible for this project. 7. Basic Dispersion – The minimum required flow path and maximum slope requirements cannot be met on this project therefore Basic Dispersion is not feasible. 8. Reduced Impervious Surface Credit – The proposed site improvements propose more than 4,000 SF of impervious surface and therefore the Restricted Footprint credit is not feasible for this site. No driveways are proposed with this project therefore the Wheel Strip Driveway credit is not feasible for this site. There are no proposed buildings with this project, therefore the Minimum Disturbance Foundation credit is RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 8 infeasible for this project. No open grid decks are proposed with this project therefore the Open Grid Decking credit is not feasible for this project. 9. Native Growth Retention Credit – This site does not contain any native vegetation, therefore the Native Growth Retention Credit is not feasible for this site. 10. Perforated Pipe Connection – No new buildings or downspouts are proposed with this project, therefore Perforated Pipe Connections are infeasible for this project. SPECIAL REQUIREMENT #1: OTHER ADOPTED AREA-SPECIFIC REQUIREMENTS The RSWDM is one of several adopted regulations in in the City of Renton that apply requirements for controlling drainage on an area-specific basis. Other adopted area-specific regulations with requirements that have a direct bearing on the drainage design of a proposed project are found in Section 1.3.1 of the RSWDM. To the best of our knowledge, there are no adopted area-specific requirements in the area of the proposed project site development that would impact the current Renton Surface Water Design Manual (RSWDM) requirements for this project. Therefore, the project will adhere to the requirements set forth in the 2022 RSWDM. SPECIAL REQUIREMENT #2: FLOOD HAZARD AREA DELINEATION Flood hazard areas are composed of the 100-year floodplain, zero-rise flood fringe, zero-rise floodway, FEMA floodway. If a proposed project contains or is adjacent to a flood hazard area as determined by CED, this special requirement requires the project to determine those components that are applicable and delineate them on the project’s site improvement plans and recorded maps. To the best of our knowledge in reviewing both only FEMA Flood Insurance Rate Maps and the King County iMap, the proposed project site area is not located within a 100-year floodplain. SPECIAL REQUIREMENT #3: FLOOD PROTECTION FACILITIES Flood protection facilities, such as levees and revetments, require a high level of confidence in their structural integrity and performance. Proper analysis, design, and construction is necessary to protect against the potentially catastrophic consequences if such facilities should fail. To the best of our knowledge in reviewing both FEMA Flood Insurance Rate Maps and the King County iMap, the proposed project site area is not located within a 100-year floodplain and not located adjacent to any rivers, streams, creeks, or other water bodies, and does not have any existing flood protection facilities installed on the existing property, nor are any new flood protection facilities proposed to be installed or warranted for this project. SPECIAL REQUIREMENT #4: SOURCE CONTROLS If a proposed project requires a commercial building or commercial site development permit then water quality source controls applicable to the proposed project shall be applied as described below in accordance with the King County Stormwater Pollution Prevention Manual and King County Code 9.12. No structural improvements are proposed that will require source controls. SPECIAL REQUIREMENT #5: OIL CONTROL Projects proposing to develop or redevelop a high-use site must provide oil controls in addition to any other water quality controls required by this manual. Such sites typically generate high concentrations of oil due to high traffic turnover, on-site vehicle or heavy or stationary equipment use, some business operations, e.g., automotive recycling, or the frequent transfer of liquid petroleum or coal derivative products. The project is not considered a high-use site and therefore will not require oil controls to be installed. RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 9 SPECIAL REQUIREMENT #6: AQUIFER PROTECTION AREA Aquifer Protection Area(s) (APA) are identified in the RMC 4-3-050. If a proposed project is located within the APA, this special requirement requires the project to determine those components that are applicable and delineate them on the project’s site improvements plans. APA zones are depicted in the Wellhead Protection Area Zones layer of COR Maps (<https://maps.rentonwa.gov/Html5viewer/Index.html?viewer=cormaps>). The subject project is located within Aquifer Protection Area Zones 1 and 2 according to the online City of Renton COR Maps (see Figure 11 – Aquafer Protection Zones), therefore open facilities, open conveyance systems, and on- site BMPs that rely on infiltration are prohibited. RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 10 3. OFFSITE ANALYSIS FIELD INSPECTION A Site visit has been made on February 16, 2022 to gather information about the existing characteristics, including, but not limited to, review of the parking lots and drainage facilities. Please refer to Downstream Analysis below for more information. DRAINAGE SYSTEM PROBLEM DESCRIPTIONS There are no known drainage concerns or any existing drainage problems per review of the site with the Renton School District, the King County iMap, and City of Renton COR Maps ‘Drainage Complaints’ Layer. As such, no drainage problems are anticipated to be present in the redevelopment or exacerbate any existing problems. UPSTREAM ANALYSIS The existing Renton School District Transportation facility is bound by North 5th Street to the north, Garden Ave N to the east, North 4th Street to the south, and Park Avenue N to the west. To the best of our knowledge, the surrounding streets are fully developed with curb, gutter, and catch basins that collect stormwater. Therefore, no offsite flows are anticipated for this project. DOWNSTREAM ANALYSIS According to the project survey and the City of Renton COR GIS database, stormwater runoff from the existing transportation facility currently is collected on the north side of the site along North 5th Street in a 18-inch corrugated metal pipe that connects to a 24-inch corrugated metal pipe and runs west along North 5th Street. Then the pipe goes north along Burnett Avenue North until it reaches North 6th Street and heads west discharging into Cedar River that ultimately drains to Lake Washington. See Figure 7 – Offsite Analysis. MITIGATION OF EXISTING OR POTENTIAL PROBLEMS The site is not within or near any FEMA flood zones, no existing problems are known, and no potential problems are expected as a result of the proposed development. RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 11 4. FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID), AND WATER QUALITY FACILITY ANALYSIS AND DESIGN EXISTING SITE HYDROLOGY (PART A) Geotechnical investigation on site has found site soils to consist of a surface layer of topsoil underlain by existing fill soils, and Holocene Alluvium deposits from the Cedar River. See project geotechnical report and Figure 9 – Soils Map. The topography of the existing site is generally flat, sloping gently from south to north at approximately 1-2% slope. See Table 1 in Section 1 of this report and Figure 3 – Existing Conditions for a summary of the existing land cover characteristics for the project site. DEVELOPED SITE HYDROLOGY (PART B) The proposed improvements consist of a new paved parking lot with sidewalks, landscaping, and public amenity space at the northwest corner of the site. New catch basins will be installed to collect surface runoff and route through water quality treatment prior to discharging to the existing 24” storm main in N 5th Street. Table 2 in Section 1 of this report summarizes the land cover characteristics of the proposed project site redevelopment disturbed area (See Figure 4 – Proposed Conditions and Figure 5 – New + Replaced Impervious Areas). PERFORMANCE STANDARDS (PART C) Flow control conforming to Core Requirement #3 meeting the Peak Rate Flow Control standard is required for this project. Specifically, flow durations for the developed site must match flow durations for the existing site conditions between ½ the two-year and the 50-year storm events. In accordance with the RSWDM, MGS Flood Version 4, an approved continuous-modeling software, is used to model the existing and proposed site drainage basins. The target surfaces for this project do not increase flows by more than 0.15 CFS using a 15-minute timestep, therefore flow control is not required for this project. Table 3 below summarizes the land cover characteristics of the existing and proposed target surfaces. See Figure 4 – Proposed Conditions and Figure 5 - New + Replaced Impervious Areas and Appendix B of this report for MGS Flood modeling results. TABLE 3 – TARGET SURFACES BASINS AREA (AC) 100-YR FLOW (CFS) EXISTING BASIN Flat Parking 0.278 0.401 Flat Lawn 0.210 PROPOSED BASIN Flat Parking 0.368 0.466 Flat Lawn 0.120 0.488 AC 0.065 CFS Increase FLOW CONTROL SYSTEM (PART D) This project is exempt from providing flow control as described above, therefore no flow control systems will be installed with this project. WATER QUALITY SYSTEM (PART E) This project proposes more than 5,000 SF of pollution generating surfaces, therefore Enhanced Basic water quality treatment is required for this project. Water quality treatment will be provided by a Filterra water quality treatment facility. Presettling will be provided by a Contech CDS Separator upstream of the Filterra. Contech Filterra units RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 12 have GULD approval for metals (Enhanced Basic treatment), and Contech CDS Separators have GULD approval for presettling/pretreatment and are both on the list of approved proprietary products accepted by the City of Renton. See Appendix B for GULD approval letters. An area swap will be utilized in order to provide water quality treatment to all new PGIS surfaces. In the proposed conditions 3,835 SF of new PGIS and non-pollution generating sidewalks will bypass the proposed storm system and sheet flow to the existing storm system on site. In order to not overwhelm the existing water quality systems with this additional flow from new paved surfaces, 3,848 SF of existing PGIS will be collected and routed to the proposed CDS Separator and Filterra water quality treatment unit. See Figure 10 – Water Quality Area Swap and Appendix B for MGS Flood calculations. RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 13 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN PIPE SYSTEMS: 1. New pipe systems shall be designed with sufficient capacity to convey and contain (at minimum) the 25- year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. - New pipe systems are designed to convey and contain the 25-year peak flow rate. 2. Pipe system structures may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a severe flooding problem or severe erosion problem as described in Core Requirement #2, Section 1.2.2 (p. 1-27). Any overflow occurring onsite for runoff events up to and including the 100-year event must discharge at the natural location for the project site. In residential subdivisions, this overflow must be contained within an onsite drainage easement, tract, covenant, or public right-of-way. - Pipe systems are designed so that the 100-year runoff event does not create or aggravate a severe flooding or erosion problem. 3. The upstream end of a pipe system that receives runoff from an open drainage feature (pond, ditch, etc.) shall be analyzed and sized as a culvert as described below. - The upstream end of the proposed pipe system does not receive runoff from an open drainage feature. CULVERTS: 1. New culverts shall be designed with sufficient capacity to meet the headwater requirements in Section 4.3.1 and convey (at minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. - No culverts are proposed with this project. 2. New culverts must also convey as much of the 100-year peak flow as is necessary to preclude creating or aggravating a severe flooding problem or severe erosion problem as described in Core Requirement #2, Section 1.2.2 (p. 1-27). Any overflow occurring onsite for runoff events up to and including the 100-year event must discharge at the natural location for the project site. In residential subdivisions, this overflow must be contained within an onsite drainage easement, tract, covenant or public right-of-way. - No culverts are proposed with this project. 3. New culverts proposed in streams with salmonids shall be designed to provide for fish passage as detailed in Section 4.3.2. Note: The County’s critical areas regulations (KCC 21A.24) or the state Department of Fish and Wildlife may require a bridge to facilitate fish passage. - No culverts are proposed with this project. DITCHES/CHANNELS: 1. New ditches/channels shall be designed with sufficient capacity to convey and contain, at minimum, the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. - No new ditches or channels are proposed with this project. 2. New ditches/channels must also convey as much of the 100-year peak flow as is necessary to preclude creating or aggravating a severe flooding problem or severe erosion problem as described in Core Requirement #2, Section 1.2.2 (p. 1-27). Any overflow occurring onsite for runoff events up to and including the 100-year event must discharge at the natural location for the project site. In residential subdivisions, this overflow must be contained within an onsite drainage easement, tract, covenant, or public right-of-way. - No new ditches or channels are proposed with this project. TIGHTLINE SYSTEMS TRAVERSING STEEP SLOPES: 1. New tightline conveyance systems traversing slopes that are steeper than 15% and greater than 20 feet in height, or are within a steep slope hazard area as defined in KCC 21A.06, shall be designed with sufficient capacity to convey and contain (at minimum) the 100-year peak flow, assuming full build-out RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 14 conditions for all tributary areas, both onsite and offsite. Tightline systems shall be designed as detailed in Section 4.2.2. - No tightline conveyance systems that traverse a steep slope are proposed with this project. BRIDGES: 1. New bridges shall be designed to accommodate the 100-year peak flow as specified in Section 4.3.3 and in accordance with the floodplain development standards in KCC 21A.24. - No bridges are proposed with this project. RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 15 6. SPECIAL REPORTS AND SUMMARY Please refer to the Geotechnical Engineering Report – by Associated Earth Sciences, dated April 10, 2025 Kirkland | Tacoma | Mount Vernon 425-827-7701 | www.aesgeo.com April 10, 2025 Project No. 20240196E001 Renton School District No. 403 7812 South 124th Street Seattle, Washington 98178 Attention: Andrew Hollenback Subject: Limited Geotechnical Engineering Study Renton School District Transportation Facility New Parking Lot 420 Park Avenue North Renton, Washington References: Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report, New Transportation Center, 1220 North 4th Street, Renton, Washington, AESI Project No. 20070040, March 20, 2007 Geologic Map of the Renton Quadrangle, King County, Washington, Mullineaux, D.R., 1965 Dear Andrew Hollenback: As requested, Associated Earth Sciences, Inc. (AESI) has completed a site reconnaissance, subsurface exploration, and limited geotechnical engineering study for the proposed new parking lot at the Renton School District Transportation Facility. We are familiar with the site having completed the site exploration and geotechnical design report (AESI, March 20, 2007) as well as providing observation and testing services during construction of the existing transportation facility in 2007. This study was completed in general accordance with our scope of work and cost proposal dated August 13, 2024. We were authorized to proceed by means of District Purchase Order #2012300302. This limited study was completed in accordance with local standards of practice in the field of geotechnical engineering at the time it was completed. No other warranty, express or implied, is made. Renton School District Transportation Facility Limited Geotechnical New Parking Lot Engineering Study April 10, 2025 ASSOCIATED EARTH SCIENCES, INC. FGR/ld – 20240196E001-004 Page 2 SITE AND PROJECT DESCRIPTION The proposed project will include converting the currently undeveloped northwest corner of the overall transportation facility property located at 420 Park Avenue North in Renton, Washington, as shown on the “Vicinity Map” (Figure 1), to a new parking lot measuring some 105 feet east-west by 200 feet north-south. This portion of the property previously had two buildings constructed which were demolished by 2020. The topography across the property is flat with total grade change north to south of just a few feet. Based on our review of conceptual site plans dated April 5, 2024, provided by Jacobson Consulting, we understand that the new parking lot will be close to existing grades, paved in asphalt with planters and landscaping providing separation from parking rows and the city right-of-way. The parking lot will also be provided with on-site lighting. SUBSURFACE EXPLORATIONS AND CONDITIONS Our field study included excavating two exploration pits on September 13, 2024. The various types of sediments, as well as depths where characteristics of the sediments changed, are indicated on the exploration logs presented in Appendix A. Our exploration locations were approximately determined on the property by measuring from known site features. The site and approximate locations of the subsurface explorations referenced in this study are presented on the “Site and Exploration Plan” (Figure 2). The conclusions and recommendations presented in this letter-report are based, in part, on the exploration pits completed for this study. The number, locations, and depths of the explorations were completed within site and budgetary constraints. Because of the nature of the exploratory work below ground, extrapolation of subsurface conditions between explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this letter-report and make appropriate changes. Previous Explorations AESI completed a geotechnical study in 2007 during the design phase of the existing transportation center. The 2007 study included six exploration borings which generally agree with the geologic findings of the current study. Copies of the 2007 exploration logs are included in Appendix A, along with logs of exploration pits recently completed for the current project Renton School District Transportation Facility Limited Geotechnical New Parking Lot Engineering Study April 10, 2025 ASSOCIATED EARTH SCIENCES, INC. FGR/ld – 20240196E001-004 Page 3 proposed. Generally, the 2007 study found fill within the surface 3 feet, underlain by soft/loose, recent, Quaternary Holocene alluvium deposits. We reviewed field reports from the construction phase of the current transportation center which indicated that parking area improvements consisted of a 12-inch-deep overexcavation, placement of Mirafi 500X, and replacement with 2-inch clean crushed rock. Visual on-site reconnaissance indicates that the near-surface remedial improvements were effective in providing structural support of the paved parking areas. We observed no concerning settlement or cracking, and the paved surface appeared to be performing well. New Exploration Pits For the current study, two new exploration pits were completed by Northwest Excavating, an independent firm working under subcontract to AESI, at the locations shown on Figure 2. The pits were completed using a 2.5-foot-wide, toothed bucket on a E50, tracked Bobcat Excavator. The pits permitted direct, visual observation of subsurface conditions. During excavation, samples were generally collected upon observation of a lithology change with depth. The excavation process was continuously observed and logged by a geologist from our firm. After logging the exposed soils, pits were backfilled with the excavated soil and lightly tamped with the excavator bucket. The various types of materials and sediments encountered in the explorations, as well as the depths where characteristics of these materials changed, are indicated on the exploration logs included in Appendix A. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field. Disturbed soil samples were selected from the pits, placed in moisture-tight containers, and transported to AESI’s laboratory for further visual classification and testing, as necessary. The exploration logs in Appendix A are based on the field observations and inspection of the samples. SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from our field explorations accomplished for this study, visual reconnaissance of the site, and review of selected applicable geologic literature. Published Geologic and Soils Map Review of the regional geologic map, titled “Geologic Map of the Renton Quadrangle, King County, Washington,” U.S. Geological Survey, Geologic Quadrangle Map GQ-405, scale 1:24,000, prepared by D.R. Mullineaux (1965) indicates that the subject property is underlain by Renton School District Transportation Facility Limited Geotechnical New Parking Lot Engineering Study April 10, 2025 ASSOCIATED EARTH SCIENCES, INC. FGR/ld – 20240196E001-004 Page 4 widespread artificial fill with Quaternary alluvium deposited by the ancestral Cedar River mapped nearby. Review of the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Web Soil Survey indicates that the soils in the vicinity of the site consist predominately of Urban Land. The regional mapping is consistent with our subsurface observations. Stratigraphy As shown on the field logs, our explorations in the area of the planned parking lot generally encountered native, Holocene alluvium at shallow depths, overlain by about 1 to 3 feet of fill and topsoil. The following section presents more detailed subsurface information organized from the youngest (shallowest) to the oldest (deepest) sediment types. Copies of our exploration logs are included in Appendix A. Sod and Topsoil Both exploration pits in the current project area encountered up to 10 inches of sod and topsoil; the sod and topsoil are not suitable for structural support and should be stripped from structural areas. Fill Existing fill was encountered in both explorations; EP-1 was mixed with topsoil to a dept of about 10 inches and in EP-2 there was up to about 2 feet of variable fill under the topsoil, where the new parking lot will be constructed. Existing fill generally consisted of moist, gray, fine to coarse sandy, fine to coarse gravel with some plastic and brick debris. Excavation through fill was difficult for the contractor’s equipment and appeared firm. Fill in EP-2 extended to approximately a depth of about 3 feet below the ground surface. Existing fill is also expected to be found around buried utilities and structures, in areas of past grading, and beneath landscape improvements. Where existing fill is found to be firm and unyielding during a proof-roll with a fully loaded, tandem-axle dump truck, it may be suitable for structural support of the paved parking area. We recommend remedial preparation of surfaces where fill is not encountered to be consistent with preparation in areas where fill is encountered. Excavated existing fill may be suitable for reuse in structural fill applications provided it is free of excessive organic material and other deleterious material, at proper moisture content, and is allowed by project plans and specifications. Renton School District Transportation Facility Limited Geotechnical New Parking Lot Engineering Study April 10, 2025 ASSOCIATED EARTH SCIENCES, INC. FGR/ld – 20240196E001-004 Page 5 Holocene Alluvium Sediments encountered below the fill and topsoil generally consisted of interbedded clean sand, silty sand, and silt with some woody debris present. We interpret these sediments to be representative of Cedar River alluvium. The alluvium extends past the depth of our deepest exploration pit of 11 feet below current ground surface. This concurs with the 2007 study which indicates a maximum boring depth of 95 feet below surface elevation. In general, the alluvium is very loose/soft to medium dense at depths shallower than 75 feet, as indicated by the 2007 study. Remedial action is recommended in planned paved areas to mitigate compressive settlement within the loose/soft soil. In general, the Holocene alluvium where moisture content is within the compactable range is considered suitable for reuse as structural fill. It should be noted that where soils are above their optimum moisture content for compaction, their reuse as structural fill during all but the driest times of the year will be difficult. However, it should be noted that the existing alluvial soil was observed to have a high silt content and is considered moisture-sensitive. Hydrology No groundwater was encountered during our current phase of exploration to depths of approximately 11 feet below the ground surface, or approximately elevation 25 feet (surface elevation 36). Groundwater is expected to be present at depth within the Holocene alluvium as an unconfined local aquifer. Shallow perched water may be present within the alternating silt and sand interbeds. During our previous study (2007, referenced above), groundwater was encountered at approximately 10 feet below the surface, or approximately elevation 25 (surface elevation 35). To our knowledge, the project specified no deep cuts that might encounter the regional groundwater aquifer. It should be noted that fluctuations in the level of the groundwater may occur due to the time of the year, variations in rainfall, and adjacent river levels. No utilities are anticipated to be installed at depths where the anticipated groundwater table might be encountered. Renton School District Transportation Facility Limited Geotechnical New Parking Lot Engineering Study April 10, 2025 ASSOCIATED EARTH SCIENCES, INC. FGR/ld – 20240196E001-004 Page 6 CONCLUSIONS AND RECOMMENDATIONS Our explorations completed in the location of the proposed new parking lot encountered loose/soft Holocene alluvium underlying 1 to 3 feet of existing fill which contains up to 10 inches of topsoil. Similar conditions were reported in AESI’s “Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report” dated in 2007. Recommendations in the referenced letter-report included near-surface remedial improvements for preparation of paved parking areas. Given that the adjacent parking areas with similarly described subsurface conditions performed well with the completion of near-surface remedial improvements, it is our opinion that the site is suitable for the proposed parking lot development, provided that recommendations contained herein are properly followed. Subgrade Preparation Recommendations The finished parking lot subgrade should receive similar near-surface stabilization improvements as performed in the adjacent transportation center parking lot. Generally, the adjacent parking lot consists of a minimum of 12 inches of aggregate (crushed rock) over geotextile reinforcement fabric (Mirafi 500X equivalent or structurally better) on the stripped surface. Site preparation of the planned paved parking area should include removal of all grass, topsoil, and any other deleterious surface materials and the remaining roots grubbed to a depth that will allow at least 12 inches of imported base material under the pavement section. Overexcavation to accommodate the specified thickness of aggregate may be necessary, depending on design elevations. Any loose existing fill soils below this elevation should be recompacted to a firm and unyielding condition prior to the placement of subsequent base stabilization. Once the subgrade elevation is achieved, we recommend performing a proof-roll with a fully loaded, tandem-axle dump truck on the exposed excavated surface prior to placing geotextile fabric. This will allow the opportunity for visual performance verification of the exposed subgrade, and if needed, less invasive access to remedy any concerns that may arise. We recommend allowing budgetary flexibility should we identify any necessity for additional near-surface improvements. AESI recommends that an engineering stabilization geotextile reinforcement such as Mirafi 500X (or approved equivalent) be placed over the stripped subgrade. The geotextile should be overlain with a minimum of 12 inches of 2-inch clean crushed rock or clean crushed recycled concrete. The fabric acts as a separation barrier between relatively fine-grained surficial materials on the site and the load-distributor aggregate. As a separator, it reduces the loss of costly aggregate Renton School District Transportation Facility Limited Geotechnical New Parking Lot Engineering Study April 10, 2025 ASSOCIATED EARTH SCIENCES, INC. FGR/ld – 20240196E001-004 Page 7 material into the subgrade and prevents the upward pumping of contaminating silt into the aggregate. The high tensile strength and low modulus of elongation of the fabric also act to reduce localized stress by redistributing the traffic loads over a wider area of subgrade. In addition, the recommended method of installation (proof-rolling) identifies weak areas, which can be improved prior to paving. After placement of stabilization fabric and aggregate, if needed, additional structural fill may be placed to attain desired grades. Structural fill placed below parking areas should consist of a granular imported material such as crushed base course or clean chip rock which are free of organics and other deleterious materials, placed in maximum 8-inch loose lifts. Each lift should be compacted to 95 percent of the modified Proctor maximum density using ASTM D-1557 as the standard. In the case of utility trench filling, the backfill should be placed and compacted in accordance with applicable codes and standards. The contractor should note that any proposed fill soils must be evaluated by AESI prior to their use in fills. This would require that we have a sample of the material 72 hours in advance to perform a Proctor test and determine its field compaction standard. Pavement Recommendations The majority of the new parking lot will accommodate light vehicle loads from passenger vehicles. In these light traffic load areas, we recommend a pavement section consisting of 3 inches of hot-mix asphalt (HMA) underlain by 4 inches of crushed surfacing top course meeting the specification of Washington State Department of Transportation (WSDOT) Standard Specification 9-03.9(3) Crushed Surfacing Top Course (CSTC). The eastern edge of the parking lot is proposed for a heavy-duty section. In these areas we recommend a minimum of 4 inches of HMA over 4 inches of CSTC. The crushed rock will provide improved and consistent drainage. The CSTC must be compacted to 95 percent of the maximum density, as determined by ASTM D-1557. All paving materials should meet gradation criteria contained in the current WSDOT Standard Specifications. Infiltration Feasibility In our opinion, shallow infiltration at the project site is considered to be not feasible. The two primary requirements for infiltration feasibility are permeability and separation from groundwater or perching layers. The on-site explorations generally encountered approximately 1 to 3 feet of existing fill overlying generally fine-grained alluvium. Existing fill soils are not suitable for use as an infiltration receptor due to its high variability and uncontrolled placement. The upper portion of the native alluvial sediments encountered below the existing fill consisted Renton School District Transportation Facility Limited Geotechnical New Parking Lot Engineering Study April 10, 2025 ASSOCIATED EARTH SCIENCES, INC. FGR/ld – 20240196E001-004 Page 8 of interbedded silty fine sand and silt with low permeability and therefore are not suitable for use as an infiltration receptor. CLOSURE We are available to provide geotechnical engineering and monitoring services during construction if required. The integrity of the paved parking areas depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. We have enjoyed working with you on this study and are confident these recommendations will aid in the successful completion of your project. If you should have any questions or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ Forest Gheen-Regouski Matthew A. Miller, P.E. Natural Resource Scientist Principal Engineer Attachments: Figure 1: Vicinity Map Figure 2: Site and Exploration Plan Appendix A: Exploration Logs G:\ G I S _ P r o j e c t s \ 2 0 2 4 \ 2 4 0 1 9 6 R e n t o n S D T r a n s p o r a t i o n S i t e \ _ a p r x \ 2 0 2 4 0 1 9 6 E 0 0 1 F 1 V M _ R e n t o n S D T r a n s p o r a t i o n . a p r x | 2 0 2 4 0 1 9 6 E 0 0 1 F 1 V M _ R e n t o n S D T r a n s p o r t a t i o n | 2 0 2 4 - 1 0 - 0 1 | m t r o p COUNTY LOCALE LOCATION PROJECT NO.DATE FIGURE 19/2420240196E001 RENTON SD TRANSPORATION SITE PARKING EXPANSION RENTON, WASHINGTON VICINITY MAP ESRI, USGS, NATIONAL GEOGRAPHIC,DELORME, NATURALVUE, I-CUBED, GEBCO:ARCGIS ONLINE BASEMAP. WADOT STATEROUTES 24K (12/20). KING CO: PARCELS,ROADS (8/24). NOTE: LOCATION AND DISTANCES SHOWNARE APPROXIMATE. BLACK AND WHITEREPRODUCTION OF THIS COLOR ORIGINALMAY REDUCE ITS EFFECTIVENESS AND LEADTO INCORRECT INTERPRETATION. KinJ CoXnt\ WE L L S A L Y N PE L L Y A V E N PE L L Y A L Y N GA R D E N A V E N N 5TH ST PA R K A V E N 405 16 900 169 /DNH WDVKLQJWRQ KING C O U N T Y KING COUNTY RENTON SEATTLE 0 2,000 FEET m SITE LOCATION AND DISTANCESSHOWN ARE APPROXIMATE. BLACK AND WHITE REPRODUCTION OFTHIS COLOR ORIGINAL MAY REDUCEITS EFFECTIVENESS AND LEAD TOINCORRECT INTERPRETATION.G:\ G I S _ P r o j e c t s \ 2 0 2 4 \ 2 4 0 1 9 6 R e n t o n S D T r a n s p o r a t i o n S i t e \ _ a p r x \ 2 0 2 4 0 1 9 6 E 0 0 1 F 2 E S _ R e n t o n S D T r a n s p o r a t i o n . a p r x | 2 0 2 4 0 1 9 6 E 0 0 1 F 2 E S _ R e n t o n S D T r a n s p o r t a t i o n | 2 0 2 4 - 1 0 - 0 3 | m t r o p PROJECT NO.DATE FIGURE ± 210/2420240196E001 RENTON SD TRANSPORATION SITE PARKING EXPANSION RENTON, WASHINGTON EXISTING SITE AND EXPLORATION PLAN DATA SOURCES/REFERENCES:KING COUNTY: PARCELS, ROADS (8/24). EAGLEVIEW TECHNOLOGIES,INC.: AERIAL IMAGERY (2023). WA DNR LIDAR:KING_COUNTY_WEST_2021, ACQUIRED 4/21, 1.5' CELL SIZE.CONTOURS DERIVED FROM LIDAR. 0 100 FEET GA R D E N A V E N PA R K AVE N N 4TH ST N 5TH ST EP124 EP224 EB10EB20 EB30 EB40 EB50EB0 4 42 38 34 3 32 44 40 3 3 2 4 4 4 3 3 32 3 3 3 3 3 34 LEGEND SITE EXPLORAION TYPE-YEAR EXPLORATION BORING EXPLORATION PIT CONTOUR 10 FT CONTOUR 2 FT PARCEL APPENDIX A Exploration Logs Classifications of soils in this report are based on visual field and/or laboratory observations, which include density/consistency, moisture condition, grain size, and plasticity estimates and should not be construed to imply field or laboratory testing unless presented herein. Visual-manual and/or laboratory classification methods of ASTM D-2487 and D-2488 were used as an identification guide for the Unified Soil Classification System. OH PT CH OL MH CL ML SM SC GW SP GC SW GM GP Well-graded gravel and gravel with sand, little to no fines Poorly-graded gravel and gravel with sand, little to no fines Clayey gravel and clayey gravel with sand Silty gravel and silty gravel with sand Well-graded sand and sand with gravel, little to no fines Poorly-graded sand and sand with gravel, little to no fines Clayey sand and clayey sand with gravel Organic clay or silt of low plasticity Organic clay or silt of medium to high plasticity Peat, muck and other highly organic soils Silty sand and silty sand with gravel Silt, sandy silt, gravelly silt, silt with sand or gravel Clay of low to medium plasticity; silty, sandy, or gravelly clay, lean clay Elastic silt, clayey silt, silt with micaceous or diatomaceous fine sand or silt Clay of high plasticity, sandy or gravelly clay, fat clay with sand or gravel (1 ) Hi g h l y Or g a n i c So i l s Fin e - G r a i n e d S o i l s - 5 0 % o r M o r e P a s s e s N o . 2 0 0 S i e v e (1 ) Co a r s e - G r a i n e d S o i l s - M o r e t h a n 5 0 % R e t a i n e d o n N o . 2 0 0 S i e v e Gr a v e l s - M o r e t h a n 5 0 % o f C o a r s e F r a c t i o n Re t a i n e d o n N o . 4 S i e v e 12 % F i n e s 5% F i n e s Sa n d s - 5 0 % o r M o r e o f C o a r s e F r a c t i o n Pa s s e s N o . 4 S i e v e Si l t s a n d C l a y s Li q u i d L i m i t L e s s t h a n 5 0 Sil t s a n d C l a y s Li q u i d L i m i t 5 0 o r M o r e (1 ) (1 ) 12 % F i n e s 5% F i n e s (2 ) (2 ) (2 ) (2 ) Terms Describing Relative Density and Consistency Estimated Percentage Moisture Content Percentage by Weight <5 5 to <12 12 to <30 30 to <50 Component Definitions Component Trace Some Modifier (silty, sandy, gravelly) Very modifier (silty, sandy, gravelly) Size Range and Sieve Number Larger than 12" Descriptive Term Smaller than No. 200 (0.075 mm) 3" to 12" Coarse- Grained Soils Fine- Grained Soils Density Very Loose Loose Medium Dense Dense Very Dense SPT blows/foot 0 to 4 4 to 10 10 to 30 30 to 50 >50 (3) 0 to 2 2 to 4 4 to 8 8 to 15 15 to 30 >30 Consistency Very Soft Soft Medium Stiff Stiff Very Stiff Hard SPT blows/foot(3) Test Symbols No. 4 (4.75 mm) to No. 200 (0.075 mm) Boulders Silt and Clay Gravel Coarse Gravel Fine Gravel Cobbles Sand Coarse Sand Medium Sand Fine Sand Dry - Absence of moisture, dusty, dry to the touch Slightly Moist - Perceptible moisture Moist - Damp but no visible water Very Moist - Water visible but not free draining Wet - Visible free water, usually from below water table G = Grain Size M = Moisture Content A = Atterberg Limits C = Chemical DD = Dry Density K = Permeability No. 4 (4.75 mm) to No. 10 (2.00 mm) No. 10 (2.00 mm) to No. 40 (0.425 mm) No. 40 (0.425 mm) to No. 200 (0.075 mm) 3" to No. 4 (4.75 mm) 3" to 3/4" 3/4" to No. 4 (4.75 mm) Symbols Sampler Type and Description Blows/6" or portion of 6"15 10 20 California Sampler Ring Sampler Continuous Sampling Grab Sample Portion not recovered Split-Spoon Sampler (SPT) Cement grout surface seal Bentonite seal Filter pack with blank casing section Screened casing or Hydrotip with filter pack End cap ATD At time of drilling Static water level (date) (1) Percentage by dry weight(2) Combined USCS symbols used for fines between 5% and 12%(3) (SPT) Standard Penetration Test (ASTM D-1586)(4) In General Accordance with Standard Practice for Description and Identification of Soils (ASTM D-2488) Groundwater depth i n c o r p o r a t e d e a r t h s c i e n c e s a s s o c i a t e d EXPLORATION LOG KEY FIGURE:A1Blo c k s \ d w g \ l o g _ k e y 2 0 2 2 . d w g L A Y O U T : L a y o u t 5 - 2 0 2 2 L o g d r a f t 0 2.5 5 7.5 10 12.5 15 17.5 20 Topsoil / Fill - 10 inches Moist, dark brown, silty, gravelly, fine to medium SAND; angular gravel (SM). Holocene Alluvium Moist, light brown, silty, fine SAND (SM). Very moist, gray with orange mottling, fine sandy, SILT; micaceous (ML). Becomes less orange mottling. Very moist, dark gray, fine to coarse SAND; some organic wood (2 to 4 inches thick); interbeds of gray, silt (SP). Occasional orange, fine sand. No seepage. No caving. Associated Earth Sciences, Inc. Exploration Pit EP-1 Renton SD Transportation Site Parking Expansion Renton, WA Date:9/13/2024 Logged By:FGR 20240196E001 Total Depth (ft):11 Approved By:JHS De p t h ( f t ) Description US C S 20 2 4 0 1 9 6 E 0 0 1 10 / 4 / 2 0 2 4 Elev.: »36 ft NAVD88 Sheet: 1 of 1 0 2.5 5 7.5 10 12.5 15 17.5 20 Topsoil - 6 inches Fill Slightly moist, gray, silty, fine to coarse sandy, fine to coarse GRAVEL; some plastic; brick debris (SM). Holocene Alluvium Very moist, orangish brown and gray, SILT; some interbed (2 to 3 inches thick) of orange, fine sand (ML). Moist, brown, fine SAND, some silt; discontinuous; interdeposits of gray, silt; bed (1 to 3 inches thick) (SP). Becomes gray. Very moist, gray, SILT; beds (0.5 to 2 inches thick) of gray, fine sand, and orange, fine to medium sand (ML). No seepage. No caving. Associated Earth Sciences, Inc. Exploration Pit EP-2 Renton SD Transportation Site Parking Expansion Renton, WA Date:9/13/2024 Logged By:FGR 20240196E001 Total Depth (ft):11 Approved By:JHS De p t h ( f t ) Description US C S 20 2 4 0 1 9 6 E 0 0 1 10 / 4 / 2 0 2 4 Elev.: »36 ft NAVD88 Sheet: 1 of 1 RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 16 7. CSWPP ANALYSIS AND DESIGN This section lists the requirements that were met when designing the TESC Plan for this site. STANDARD REQUIREMENTS Erosion/Sedimentation Plan shall include the following: 1. Clearing Limits – Construction limits are delineated or noted on the project erosion control plans and shall be physically laid out on the project site. 2. Cover Measures – Contractor will use plastic sheeting, hydroseeding, and mulching to protect soils from erosion. Gravel borrow or “hog fuel” may be used in areas of excessively moist soils that will support building or traffic loads, if necessary. 3. Perimeter Protection – Temporary construction fencing will be used to delineate and protect the project clearing limits and provide a secure site. Straw wattles will be used to prevent sediment-laden water from discharging from the site. 4. Traffic Area Stabilization – The existing drive aisles and parking lots will be utilized for construction access, staging, and laydown as needed. The contractor shall coordinate with the Renton School District prior to starting construction. Additional gravel borrow or “hog fuel” may be used in areas of excessively moist soils that will support traffic loads, if necessary. 5. Sediment Retention – Filter fabric protection will also be installed in all new area drain structures and remain until the site is stabilized. 6. Surface Water Collection – Interceptor swales will be used in the appropriate areas of the site to collect stormwater runoff, if necessary. 7. Dewatering Control – Dewatering is not necessary for this site; therefore, no dewatering control measures are implemented. 8. Dust Control – Dry soils will be appropriately sprinkled with water to limit airborne dust during dry weather. 9. Flow Control – Discharge will be restricted and will therefore serve as a flow control measure. 10. Control Pollutants – BMPs shall be implemented to prevent or treat contamination of stormwater runoff by pH modifying sources. Carbon dioxide sparging, using dry ice or a gas diffuser as a source of CO2 will be used as needed to adjust the pH level and prevent discharge of water with elevated pH levels to the City’s Storm System. In addition, dust control will be implemented as needed to prevent fugitive dust during the treatment process. In addition, all waste materials from the site will be removed in a manner that does not cause contamination of stormwater. 11. Protect Existing and Proposed Flow Control BMPs – The native vegetation will be protected with silt fencing and perimeter construction fencing. 12. Maintain BMPs – BMPs for the project will be monitored for effectiveness on a regular basis to ensure they are repaired and replaced as necessary. 13. Manage the Project – The project will be phased to take weather and seasonal work limits into account. The BMPs will be inspected, maintained, and repaired as needed to ensure their intended performance. RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 17 8. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT BOND QUANTITIES WORKSHEET A bond quantities worksheet is included in Appendix A. FLOW CONTROL AND WATER QUALITY FACILITY SUMMARY SHEET AND SKETCH A Facility Summary Sheet has been completed and is included in Appendix D. DECLARATION OF COVENANT FOR PRIVEATELY MAINTAINED FLOW CONTROL AND WATER QUALITY FACILITIES A draft Declaration of Covenant is included in Appendix D for City review and will be recorded prior to permit issuance. RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 18 9. OPERATIONS AND MAINTENANCE MANUAL As stated in the Renton Surface Water Design Manual (RSWDM), the owner will maintain all privately owned facilities. Sections of the RSWDM outlining the operations and maintenance of these facilities have been included in this section along with maintenance manuals from proposed proprietary products. A COPY OF THE OPERATION AND MAINTENANCE MANUAL SHALL BE RETAINED ON SITE OR WITHIN REASONABLE ACCESS TO THE SITE AND SHALL BE TRANSFERRED WITH THE PROPERTY TO ANY NEW OWNER OPERATIONS AND MAINTENANCE MANUAL for RSD Transportation Expansion PARTY RESPONSIBLE FOR MAINTENANCE AND OPERATIONS: Renton School District CITY OF RENTON SURFACE WATER DESIGN MANUAL 2022 City of Renton Surface Water Design Manual 6/22/2022 A-1 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS This appendix contains the maintenance requirements for the following typical stormwater flow control and water quality facilities and on-site BMPs (ctrl/click the title to follow the link): No. 1 – Detention Ponds No. 2 – Infiltration Facilities No. 3 – Detention Tanks and Vaults No. 4 – Control Structure/Flow Restrictor No. 5 – Catch Basins and Manholes No. 6 – Conveyance Pipes and Ditches No. 7 – Debris Barriers (e.g., trash racks) No. 8 – Energy Dissipaters No. 9 – Fencing No. 10 – Gates/Bollards/Access Barriers No. 11 – Grounds (landscaping) No. 12 – Access Roads No. 13 – Basic Bioswale (grass) No. 14 – Wet Bioswale No. 15 – Filter Strip No. 16 – Wetpond No. 17 – Wetvault No. 18 – Stormwater Wetland No. 19 – Sand Filter Pond No. 20 – Sand Filter Vault No. 21 – Proprietary Facility Cartridge Filter Systems No. 22 – Baffle Oil/Water Separator No. 23 – Coalescing Plate Oil/Water Separator APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-2 No. 24 – Catch Basin Insert (not allowed in the city for oil control) No. 25 – Drywell BMP No. 26 – Gravel Filled Infiltration Trench BMP No. 27 – Gravel Filled Dispersion Trench BMP No. 28 – Native Vegetated Surface/Native Vegetated Landscape BMP No. 29 – Perforated Pipe Connections BMP No. 30 – Permeable Pavement BMP No. 31 – Bioretention BMP No. 32 – RainWater Harvesting BMP No. 33 – Rock Pad BMP No. 34 – Sheet Flow BMP No. 35 – Splash Block BMP No. 36 – Vegetated Roof BMP No. 37 – Rain Garden BMP No. 38 – Soil Amendment BMP No. 39 – Retained Trees No. 40 – Filterra System No. 41 – Compost Amended Vegetated Filter Strip (CAVFS) No. 42 – Media Filter Drain (MFD) No. 43 – Compost-Amended Biofiltration Swale APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-10 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-11 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipe (cont.) Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates (Catch Basins) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. Damaged or missing grate Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-12 NO. 6 – CONVEYANCE PIPES AND DITCHES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/root growth in pipe Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged pipes Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive vegetation growth Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-15 NO. 9 – FENCING MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Erosion or holes under fence Erosion or holes more than 4 inches high and 12-18 inches wide permitting access through an opening under a fence. No access under the fence. Wood Posts, Boards and Cross Members Missing or damaged parts Missing or broken boards, post out of plumb by more than 6 inches or cross members broken No gaps on fence due to missing or broken boards, post plumb to within 1½ inches, cross members sound. Weakened by rotting or insects Any part showing structural deterioration due to rotting or insect damage All parts of fence are structurally sound. Damaged or failed post foundation Concrete or metal attachments deteriorated or unable to support posts. Post foundation capable of supporting posts even in strong wind. Metal Posts, Rails and Fabric Damaged parts Post out of plumb more than 6 inches. Post plumb to within 1½ inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence (including post, top rails, and fabric) more than 1 foot out of design alignment. Fence is aligned and meets design standards. Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or protective coating Part or parts that have a rusting or scaling condition that has affected structural adequacy. Structurally adequate posts or parts with a uniform protective coating. Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-16 NO. 10 – GATES/BOLLARDS/ACCESS BARRIERS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Chain Link Fencing Gate Damaged or missing members Missing gate. Gates in place. Broken or missing hinges such that gate cannot be easily opened and closed by a maintenance person. Hinges intact and lubed. Gate is working freely. Gate is out of plumb more than 6 inches and more than 1 foot out of design alignment. Gate is aligned and vertical. Missing stretcher bar, stretcher bands, and ties. Stretcher bar, bands, and ties in place. Locking mechanism does not lock gate Locking device missing, non-functioning or does not link to all parts. Locking mechanism prevents opening of gate. Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. Bar Gate Damaged or missing cross bar Cross bar does not swing open or closed, is missing or is bent to where it does not prevent vehicle access. Cross bar swings fully open and closed and prevents vehicle access. Locking mechanism does not lock gate Locking device missing, non-functioning or does not link to all parts. Locking mechanism prevents opening of gate. Support post damaged Support post does not hold cross bar up. Cross bar held up preventing vehicle access into facility. Bollards Damaged or missing bollards Bollard broken, missing, does not fit into support hole or hinge broken or missing. No access for motorized vehicles to get into facility. Bollards do not lock Locking assembly or lock missing or cannot be attached to lock bollard in place. No access for motorized vehicles to get into facility. Boulders Dislodged boulders Boulders not located to prevent motorized vehicle access. No access for motorized vehicles to get into facility. Evidence of vehicles circumventing boulders Motorized vehicles going around or between boulders. No access for motorized vehicles to get into facility. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-17 NO. 11 – GROUNDS (LANDSCAPING) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Trees and Shrubs Hazard tree identified Any tree or limb of a tree identified as having a potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. No hazard trees in facility. Damaged tree or shrub identified Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-47 NO. 38 – SOIL AMENDMENT BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Soil Media Unhealthy vegetation Vegetation not fully covering ground surface or vegetation health is poor. Yellowing: possible Nitrogen (N) deficiency. Poor growth: possible Phosphorous (P) deficiency. Poor flowering, spotting or curled leaves, or weak roots or stems: possible Potassium (K) deficiency. Plants are healthy and appropriate for site conditions Inadequate soil nutrients and structure In the fall, return leaf fall and shredded woody materials from the landscape to the site when possible Soil providing plant nutrients and structure Excessive vegetation growth Grass becomes excessively tall (greater than 10 inches); nuisance weeds and other vegetation start to take over. Healthy turf- “grasscycle” (mulch-mow or leave the clippings) to build turf health Weeds Preventive maintenance Avoid use of pesticides (bug and weed killers), like “weed & feed,” which damage the soil Fertilizer needed Where fertilization is needed (mainly turf and annual flower beds), a moderate fertilization program should be used which relies on compost, natural fertilizers or slow-release synthetic balanced fertilizers Integrated Pest Management (IPM) protocols for fertilization followed Bare spots Bare spots on soil No bare spots, area covered with vegetation or mulch mixed into the underlying soil. Compaction Poor infiltration due to soil compaction To remediate compaction, aerate soil, till to at least 8-inch depth, or further amend soil with compost and re-till If areas are turf, aerate compacted areas and top dress them with 1/4 to 1/2 inch of compost to renovate them If drainage is still slow, consider investigating alternative causes (e.g., high wet season groundwater levels, low permeability soils) Also consider site use and protection from compacting activities No soil compaction Poor infiltration Soils become waterlogged, do not appear to be infiltrating. Facility infiltrating properly Erosion/Scouring Erosion Areas of potential erosion are visible Causes of erosion (e.g., concentrate flow entering area, channelization of runoff) identified and damaged area stabilized (regrade, rock, vegetation, erosion control matting).For deep channels or cuts (over 3 inches in ponding depth), temporary erosion control measures in place until permanent repairs can be made Grass/Vegetation Unhealthy vegetation Less than 75% of planted vegetation is healthy with a generally good appearance. Healthy vegetation. Unhealthy plants removed/replaced. Appropriate vegetation planted in terms of exposure, soil and soil moisture. Noxious Weeds Noxious weeds Listed noxious vegetation is present (refer to current County noxious weed list). No noxious weeds present. ® Filterra® Maintenance Steps Contech has created a network of Certified Maintenance Providers (CCMP’s) to provide maintenance on Filterra systems. To find a CCMP in your area please visit www.conteches.com/maintenance 1. Inspection of Filterra and surrounding area 2. Removal of tree grate and erosion control stones 3. Removal of debris, trash and mulch 4. Mulch replacement 5. Clean area around Filterra 6. Complete paperwork and record plant height and width © 2015 Contech Engineered Solutions LLC ENGINEERED SOLUTIONS Filterra Vault Owner’s Manual (Precast Vault Configurations) ® Bioretention Systems ENGINEERED SOLUTIONS This Owner’s Manual applies to all precast Filterra Configurations, including Filterra Bioscape Vault and Filterra HC. www.ContechES.com/filterra | 800-338-1122 3 Table of Contents Introduction ................................................................................4 Activation Overview .....................................................................4 Filterra Plant Selection Overview ...................................................6 Warranty Overview ......................................................................6 Routine Maintenance Guidelines...................................................6 Maintenance Visit Procedure .........................................................9 Plant Care ................................................................................11 Appendix 1 – Activation Package ................................................12 Appendix 2 – Filterra Tree Grate Opening Expansion Procedure..... 19 ® Bioretention Systems ENGINEERED SOLUTIONS www.ContechES.com/filterra | 800-338-11224 Introduction Thank you for your purchase of the Filterra® Bioretention System. Filterra is a specially engineered stormwater treatment system incorporating high performance biofiltration media to remove pollutants from stormwater runoff. The system’s biota (vegetation and soil microorganisms) then further breakdown and absorb captured pollutants. All components of the system work together to provide a sustainable long-term solution for treating stormwater runoff. The Filterra system has been delivered to you with protection in place to resist intrusion of construction related sediment which can contaminate the biofiltration media and result in inadequate system performance. These protection devices are intended as a best practice and cannot fully prevent contamination. It is the purchaser’s responsibility to provide adequate measures to prevent construction related runoff from entering the Filterra system. Included with your purchase is Activation of the Filterra system by the manufacturer as well as a 1-year warranty from delivery of the system and a final site assessment of unit condition (mulch replacement, debris removal, and pruning of vegetation) scheduled between 6 and 12 months after activation, upon request. Design and Installation Each project presents different scopes for the use of Filterra systems. Information and help may be provided to the design engineer during the planning process. Correct Filterra box sizing (by rainfall region) is essential to predict pollutant removal rates for a given area. The engineer shall submit calculations for approval by the local jurisdiction. The contractor is responsible for the correct installation of Filterra units as shown in approved plans. A comprehensive installation manual is available at www.ContechES.com. Activation Overview Activation of the Filterra system is a procedure completed by the manufacturer to place the system into working condition. This involves the following items: • Removal of construction runoff protection devices. • Planting of the system’s vegetation (provided by the purchaser). • Placement of pretreatment mulch layer using mulch acceptable for use in Filterra systems. Activation MUST be provided by the manufacturer to ensure proper site conditions are met for Activation, proper installation of the vegetation, and use of pretreatment mulch acceptable for use in Filterra systems. More information is available in the Filterra Activation Package. www.ContechES.com/filterra | 800-338-1122 5 Minimum Requirements The minimum requirements for Filterra Activation are as follows: 1. The purchaser must have procured vegetation meeting the requirements outlined in the Filterra Activation Package. 2. The site landscaping must be fully stabilized, i.e. full landscaping installed and some grass cover (not just straw and seed) is required to reduce sediment transport. Construction debris and materials should be removed from surrounding area. 3. Final paving must be completed. Final paving ensures that paving materials will not enter and contaminate the Filterra system during the paving process, and that the plant will receive runoff from the drainage area, assisting with plant survival for the Filterra system. 4. Filterra throat opening should be at least 4” in order to ensure adequate capacity for inflow and debris. The Filterra Activation Package is available on the Contech website (www.ContechES.com/filterra) and ensures that the proper conditions are met for Contech to perform the Activation service. Vegetation meeting Contech’s requirements must be provided at time of Activation. If the site does not meet the conditions required for Activation, or acceptable vegetation is not provided by the purchaser at time of Activation, a charge of $1,500 will be invoiced to the purchaser. www.ContechES.com/filterra | 800-338-11226 Filterra Plant Selection Overview A Plant List is available on the Contech website highlighting recommended plants for Filterra systems in your area. Keep in mind that plants are subject to availability due to seasonality and required minimum size for the Filterra system. Plants installed in the Filterra system are container plants (max 15 gallon) from nursery stock and will be immature in height and spread at Activation. It is the responsibility of the owner to provide adequate irrigation when necessary to the plant of the Filterra system. More information is available in the Filterra Activation Package. Warranty Overview Refer to the Contech Engineered Solutions LLC Stormwater Treatment System LIMITED WARRANTY for further information. The following conditions may void the Filterra system’s warranty and waive the manufacturer provided Activation and Final Site Assessment services: • Unauthorized activation or performance of any of the items listed in the activation overview • Any tampering, modifications or damage to the Filterra system or runoff protection devices • Removal of any Filterra system components • Failure to prevent construction related runoff from entering the Filterra system • Failure to properly store and protect any Filterra components (including media and underdrain stone) that may be shipped separately from the vault Final Site Assessment With proper routine maintenance, the biofiltration media within the Filterra system should last as long as traditional bioretention media. A final site assessment is included by the manufacturer, upon request, on all Filterra systems between 6 and 12 months after activation. This includes a final assessment of unit condition, debris removal, mulch replacement, and pruning of vegetation. More information is provided in the Operations and Maintenance Guidelines. Some Filterra systems also contain pretreatment or outlet bays. Depending on site pollutant loading, these bays may require periodic removal of debris, however this is not included in the final site assessment, and would likely not be required within the first year of operation. These services, as well as routine maintenance outside of the included first year, can be provided by certified maintenance providers listed on the Contech website. Training can also be provided to other stormwater maintenance or landscape providers. www.ContechES.com/filterra | 800-338-1122 7 Why Maintain? All stormwater treatment systems require maintenance for effective operation. This necessity is often incorporated in your property’s permitting process as a legally binding BMP maintenance agreement. Other reasons to maintain are: • Avoiding legal challenges from your jurisdiction’s maintenance enforcement program. • Prolonging the expected lifespan of your Filterra media. • Avoiding more costly media replacement. • Helping reduce pollutant loads leaving your property. Simple maintenance of the Filterra is required to continue effective pollutant removal from stormwater runoff before discharge into downstream waters. This procedure will also extend the longevity of the living biofilter system. The unit will recycle and accumulate pollutants within the biomass, but is also subjected to other materials entering the inlet. This may include trash, silt and leaves etc. which will be contained above the mulch layer. Too much silt may inhibit the Filterra’s flow rate, which is the reason for site stabilization before activation. Regular replacement of the mulch stops accumulation of such sediment. When to Maintain? Maintenance visits are scheduled seasonally; the spring visit aims to clean up after winter loads including salts and sands while the fall visit helps the system by removing excessive leaf litter. It has been found that in regions which receive between 30-50 inches of annual rainfall, (2) two visits are generally required; in regions with less rainfall often only (1) one visit per annum is sufficient. Varying land uses can affect maintenance frequency. Contributing drainage areas which are subject to new development wherein the recommended erosion and sediment control measures have not been implemented may require additional maintenance visits. Some sites may be subjected to extreme sediment or trash loads, requiring more frequent maintenance visits. This is the reason for detailed notes of maintenance actions per unit, helping the Supplier and Owner predict future maintenance frequencies, reflecting individual site conditions. Owners must promptly notify the maintenance provider of any damage to the plant(s), which constitute(s) an integral part of the bioretention technology. www.ContechES.com/filterra | 800-338-11228 Exclusion of Services Clean up due to major contamination such as oils, chemicals, toxic spills, etc. will result in additional costs and are not included as part of the final site assessment. Should a major contamination event occur the Owner must block off the outlet pipe of the Filterra (where the cleaned runoff drains to, such as drop inlet) and block off the throat of the Filterra. The Supplier should be informed immediately. Maintenance Visit Summary Each maintenance visit consists of the following simple tasks (detailed instructions below). 1. Inspection of Filterra and surrounding area 2. Removal of tree grate and erosion control stones 3. Removal of debris, trash and mulch 4. Mulch replacement 5. Plant health evaluation and pruning or replacement as necessary 6. Clean area around Filterra 7. Complete paperwork Maintenance Tools, Safety Equipment and Supplies Ideal tools include: camera, bucket, shovel, broom, pruners, hoe/rake, and tape measure. Appropriate Personal Protective Equipment (PPE) should be used in accordance with local or company procedures. This may include impervious gloves where the type of trash is unknown, high visibility clothing and barricades when working in close proximity to traffic and also safety hats and shoes. A T-Bar or crowbar should be used for moving the tree grates (up to 170 lbs ea.). Most visits require minor trash removal and a full replacement of mulch. See below for actual number of bagged mulch that is required in each media bay size. Mulch should be a double shredded, hardwood variety. Some visits may require additional Filterra engineered soil media available from the Supplier. Box Length Box Width Filter Surface Area (ft²)Volume at 3” (ft³)# of 2 ft³ Mulch Bags 4 4 16 4 2 6 4 24 6 3 8 4 32 8 4 6 6 36 9 5 8 6 48 12 6 10 6 60 15 8 12 6 72 18 9 13 7 91 23 12 Other sizes not listed - 1 bag per 8 ft2 of media. www.ContechES.com/filterra | 800-338-1122 9 1. Inspection of Filterra and surrounding area • Record individual unit before maintenance with photograph (numbered). Record on Maintenance Report (see example in this document) the following: 2. Removal of tree grate and erosion control stones • Remove cast iron grates for access into Filterra box. • Dig out silt (if any) and mulch and remove trash & foreign items. 3. Removal of debris, trash and mulch • After removal of mulch and debris, measure distance from the top of the Filterra engineered media soil to the top of the top slab. Compare the measured distance to the distance shown on the approved Contract Drawings for the system. Add Filterra media (not top soil or other) to bring media up as needed to distance indicated on drawings. Record on Maintenance Report the following: Standing Water yes | no Damage to Box Structure yes | no Damage to Grate yes | no Is Bypass Clear yes | no If yes answered to any of these observations, record with close-up photograph (numbered). Record on Maintenance Report the following: Silt/Clay yes | no Cups/ Bags yes | no Leaves yes | no Buckets Removed ________ Record on Maintenance Report the following: Distance to Top of Top Slab (inches) ________ Inches of Media Added ________ Maintenance Visit Procedure Keep sufficient documentation of maintenance actions to predict location specific maintenance frequencies and needs. An example Maintenance Report is included in this manual. www.ContechES.com/filterra | 800-338-112210 4. Mulch replacement • Add double shredded mulch evenly across the entire unit to a depth of 3”. • Refer to Filterra Mulch Specifications for information on acceptable sources. • Ensure correct repositioning of erosion control stones by the Filterra inlet to allow for entry of trash during a storm event. • Replace Filterra grates correctly using appropriate lifting or moving tools, taking care not to damage the plant. 5. Plant health evaluation and pruning or replacement as necessary • Examine the plant’s health and replace if necessary. • Prune as necessary to encourage growth in the correct directions 6. Clean area around Filterra • Clean area around unit and remove all refuse to be disposed of appropriately. 7. Complete paperwork • Deliver Maintenance Report. • Some jurisdictions may require submission of maintenance reports in accordance with approvals. It is the responsibility of the Owner to comply with local regulations. Record on Maintenance Report the following: Height above Grate _____________________(ft) Width at Widest Point _____________________(ft) Health healthy | unhealthy Damage to Plant yes | no Plant Replaced yes | no www.ContechES.com/filterra | 800-338-1122 11 Plant Care for Filterra® Systems After Activation, the Contractor is responsible for proper care of the vegetation until the site is handed over to the Owner. After that, it is the Site Owner’s responsibility to care for the vegetation. Contech recommends the following care for the plants: 1. To prevent transplant shock (especially if planting takes place in the hot season), it may be necessary to prune some of the foliage to compensate for reduced root uptake capacity. This is accomplished by pruning away some of the smaller secondary branches or a main scaffold branch if there are too many. Too much foliage relative to the root ball can dehydrate and damage the plant. 2. Plant staking may be required. 3. With all trees/shrubs, remove dead, diseased, crossed/ rubbing, sharply crotched branches or branches growing excessively long or in wrong direction compared to majority of branches. 4. Contech recommends irrigation of the Filterra® Vegetation. The following guidance will help to ensure the vegetation is properly irrigated. Irrigation Recommendations: • Each Filterra® system must receive adequate irrigation to ensure survival of the living system during periods of drier weather. • Irrigation sources include rainfall runoff from downspouts and/or gutter flow, applied water through the tree grate or in some cases from an irrigation system with emitters installed during construction. • At Activation: Apply about one (cool climates) to two (warm climates) gallons of water per inch of trunk diameter over the root ball. • During Establishment: In common with all plants, each Filterra® plant will require more frequent watering during the establishment period. One inch of applied water per week for the first three months is recommended for cooler climates (2 to 3 inches for warmer climates). If the system is receiving rainfall runoff from the drainage area, then irrigation may not be needed. Inspection of the soil moisture content can be evaluated by gently brushing aside the mulch layer and feeling the soil. Be sure to replace the mulch when the assessment is complete. Irrigate as needed**. • Established Plants: Established plants have fully developed root systems and can access the entire water column in the media. Therefore irrigation is less frequent but requires more applied water when performed. For a mature system assume 3.5 inches of available water within the media matrix. Irrigation demand can be estimated as 1” of irrigation demand per week. Therefore if dry periods exceed 3 weeks, irrigation may be required. ** Five gallons per square yard approximates 1 inch of water. Therefore for a 6’ x 6 foot Filterra® approximately 20-60 gallons of applied water is needed. To ensure even distribution of water it needs to be evenly sprinkled over the entire surface of the filter bed, with special attention to make sure the root ball is completely wetted. NOTE: if needed, measure the time it takes to fill a five gallon bucket to estimate the applied water flow rate. Then calculate the time needed to irrigate the Filterra®, For example is the flow rate of the sprinkler is 5 gallons/minute then it would take 12 minutes to irrigate a 6’x6’ filter. Plant Replacement: In some cases, plants will require replacement. Please follow the procedures below to ensure a properly functioning Filterra® system. 1. Remove the existing plant, and leave as much of the Filterra® media in place as possible. 2. Select a replacement per the Filterra® Activation Package. 3. Prior to removing the plant from the container, ensure the soil moisture is sufficient to maintain the integrity of the root ball. If needed, pre-wet the container plant. 4. Cut away any roots which are growing out of the container drain holes. 5. Plant(s) should be carefully removed from the pot by gently pounding on the sides of the container with the fist to loosen root ball. Then carefully slide out. Do not lift plant(s) by trunk as this can break roots and cause soil to fall off. Extract the root ball in a horizontal position and support it to prevent it from breaking apart. Alternatively, the pot can be cut away to minimize root ball disturbance. 6. Excavate a hole with a diameter 4” greater than the root ball, gently place the plant(s). 7. Plant the tree/shrub/grass with the top of the root ball 1” above surrounding media to allow for settling. 8. All plants should have the main stem centered in the tree grate (where applicable) upon completion of installation. 9. Reinstall or add mulch to a depth of 3” per Contech’s mulch specifications for Filterra® systems. www.ContechES.com/filterra | 800-338-112212 Maintenance Checklist Filterra Inspection & Maintenance Log Filterra System Size/Model: _____________________________Location: ____________________________________________ Drainage System Failure Problem Conditions to Check Condition that Should Exist Actions Inlet Excessive sediment or trash accumulation. Accumulated sediments or trash impair free flow of water into Filterra. Inlet should be free of obstructions allowing free distributed flow of water into Filterra. Sediments and/or trash should be removed. Mulch Cover Trash and floatable debris accumulation.Excessive trash and/or debris accumulation.Minimal trash or other debris on mulch cover. Trash and debris should be removed and mulch cover raked level. Ensure bark nugget mulch is not used. Mulch Cover “Ponding” of water on mulch cover. “Ponding” in unit could be indicative of clogging due to excessive fine sediment accumulation or spill of petroleum oils. Stormwater should drain freely and evenly through mulch cover. Recommend contact manufacturer and replace mulch as a minimum. Vegetation Plants not growing or in poor condition. Soil/mulch too wet, evidence of spill. Incorrect plant selection. Pest infestation. Vandalism to plants. Plants should be healthy and pest free.Contact manufacturer for advice. Vegetation Plant growth excessive. Plants should be appropriate to the species and location of Filterra. Trim/prune plants in accordance with typical landscaping and safety needs. Structure Structure has visible cracks. Cracks wider than 1/2 inch or evidence of soil particles entering the structure through the cracks. Vault should be repaired. Maintenance is ideally to be performed twice annually. Date Mulch & Debris Removed Depth of Mulch Added Mulch Brand Height of Vegetation Above Grate Vegetation Species Issues with System Comments 1/1/17 5 – 5 gal Buckets 3”Lowe’s Premium Brown Mulch 4’Galaxy Magnolia - Standing water in downstream structure - Removed blockage in downstream structure www.ContechES.com/filterra | 800-338-1122 13 Filterra Activation Package | Page 1 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® The Filterra system will be (or has been) delivered to you with protection in place to resist intrusion of construction related sediment which can contaminate the biofiltration media and result in inadequate system performance. These protection devices are intended as a best practice and cannot fully prevent contamination. It is the purchaser’s responsibility to provide adequate measures to prevent construction related runoff from entering the Filterra system. Included with your purchase is Activation of the Filterra system by the manufacturer as well as a 1-year warranty from delivery of the system and a Final Site Assessment (assessment of unit condition, mulch replacement, debris removal, and pruning of vegetation) scheduled between 6 months and 1 year after Activation, upon request. Activation of the Filterra system is a procedure completed by the manufacturer to place the system into working condition. This involves the following items: • Removal of construction runoff protection devices • Planting of the system’s vegetation (provided by the purchaser) • Placement of pretreatment mulch layer using mulch acceptable for use in Filterra systems. Activation MUST be provided by the manufacturer to ensure proper site conditions are met for Activation, proper installation of the vegetation, and use of pretreatment mulch acceptable for use in Filterra systems. The purchaser should request Activation from Contech after the site is stabilized, but prior to turning over the site to the owner. Please allow 1-2 weeks to schedule Activation. The purchaser must ensure that the site is acceptable for Filterra Activation. A checklist (included as page 3 of this document must be completed and submitted to the Contech Activation Coordinator. The minimum 4 requirements for Filterra Activation are as follows: 1. The purchaser must have sourced vegetation meeting the requirements outlined in “Plant Selection for Filterra Systems” starting on page 4 of this document. FILTERRA® VAULT ACTIVATION PACKAGE ENGINEERED SOLUTIONS Appendix 1 – Filterra® Vault Activation Package www.ContechES.com/filterra | 800-338-112214 Filterra Activation Package | Page 2 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® 2. The site landscaping must be fully stabilized, i.e. full landscaping installed and some grass cover (not just straw and seed) is required to reduce sediment transport. Construction debris and materials should be removed from surrounding area. 3. Final paving must be completed. Final paving ensures that paving materials will not enter and contaminate the Filterra system during the paving process, and that the plant will receive runoff from the drainage area, assisting with plant survival for the Filterra system. 4. Where curb inlets are included as part of the Filterra system, Filterra throat opening should be at least 4” clear in order to ensure adequate capacity for inflow and debris. www.ContechES.com/filterra | 800-338-1122 15 Filterra Activation Package | Page 3 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Filterra® Vault Activation Checklist Project Name: ________________________________________Company: ______________________________________________ Site Contact Name: _______________________________________Site Contact Phone/Email: ____________________________ Site Owner/End User Name: _________________________Site Owner/End User Phone/Email: ____________________________ Preferred Activation Date: ___________________________________(provide 2 weeks minimum from date this form is submitted) Site Designation Top Opening Type Final Pavement Complete Landscaping Complete / Grass Emerging Construction materials / Piles / Debris Removed Throat Opening Measures 4” Min. Height (where applicable) Vegetation Sourced by Contractor Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. Attach additional sheets as necessary. Signature Date ENGINEERED SOLUTIONS www.ContechES.com/filterra | 800-338-112216 Filterra Activation Package | Page 4 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Planting Selection for Filterra® Vault Systems All Filterra systems require vegetation for proper long-term performance. As indicated in the Activation Package, the Contractor is responsible for sourcing the proper vegetation prior to Activation. Contech or a Contech representative will install the vegetation during the Activation process. Contractors should identify the Top Opening style for each Filterra requiring Activation on the Activation Checklist. Contech offers three types, which are detailed on page 5 of this document: • Vault with Tree Grate • Vault with Full Grate • Bioscape / Open Planter Contractors must ensure the vegetation meets the following 4 requirements: 1. Select plant(s) as specified in the engineering plans and specifications AND that are listed on Contech’s Configuration Specific Plant Lists**. 2. All plants MUST be container-grown in nursery containers no larger than 15 gallons. Crated and/or Ball/Burlap plants are NOT permitted. 3. For Vaults with Tree Grates, plant height must be 4’ Minimum, from soil surface to top of plant. 4. Provide plant quantities per the following guidance: • Vault with Tree Grate – 1 per Tree Grate • Vault with Full Grate – 4-5 Small or Extra Small Grasses per Full Grate • Bioscape – Quantities should be selected based on plant palette options found starting on page 6 of this document. If Contech or Contech’s representative shows up for Activation and any of the 4 requirements above are not met, Activation cannot be performed and the Contractor will be billed a $1,500 Unprepared Site fee*. Some additional vegetation recommendations for the best possible Activation and Installation are as follows: • Select plant(s) with full root development but not to the point where root bound. • For Filterra systems with a Tree Grate, select plants with taller trunks. Lower branches can be pruned away provided there are sufficient branches above the grate for tree or shrub development. • For Filterra systems with a Tree Grate, plant(s) should have a single trunk at installation. • Plant species shall not have a mature height greater than 30 feet. ** In some cases, Contech may consider alternate plant species as approved by the Product Manager. Please list the plant name in the space below and submit this sheet to your Contech Activation Coordinator. If the plant species is approved, either the Product Manager or the Activation Coordinator will sign the form and return to you for inclusion with your Activation Checklist. Requested Plant Species: ___________________________________________Approved: _______________________________ Date: ____________________________________ www.ContechES.com/filterra | 800-338-1122 17 Filterra Activation Package | Page 5 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Figure 1a. Filterra with Tree Grate Drawing Figure 2a. Filterra with Full Grate Drawing Figure 3a. Filterra Bioscape Vault Drawing Figure 1b. Filterra with Tree Grate Photo (not yet planted) Figure 2b. Filterra with Full Grate Photo Figure 3b. Filterra Bioscape Vault Photo Filterra® Top Opening Examples Filterra® Vault with Tree Grate Filterra® Vault with Full Grate Filterra® Bioscape Vault www.ContechES.com/filterra | 800-338-112218 Filterra Activation Package | Page 6 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Filterra® Bioscape Vault Plant Palettes KEY: (refer to plant lists for species sizing) 4x4 Media Bay A. 3 A.5 A. 6 A. 6 A. 9 A. 12 A. 15 A. 20 B. 6 C. 3 D. 2 B. 1 B.2 B. 2 B. 2 B. 3 B. 3 B. 4 C. 1 C.1 C. 1 D. 1 D. 1 D. 1 D. 1 D. 1 C. 1 C. 2 C. 2 C. 2 4x6/6x4 Media Bay 4x8/8x4 & 4.5x7.83/7.83x4.5 Media Bay 6x6 Media Bay 6x8/8x6 Media Bay 6x10/10x6 & 8x8 Media Bay 6x12/12x6 Media Bay 7x13/13x7/12x8 & 14x8 Media Bay A. EXTRA SMALL GRASS • Up to 2’ mature spread • 1-2 gallon typical (1 gal. minimum) B. SMALL GRASS/SHRUB • 2’-4’ mature spread • 1-7 gallon typical C. MEDIUM SHRUB • 4’-6’ mature spread • 1-7 gallon typical D. LARGE SHRUB OR EXTRA LARGE SHRUB OR TREE • 6’ mature spread and greater, 30’ max. mature height • Up to 15 gallon maximum NOTE: For larger vaults and in-ground Filterra Bioscape systems, palettes can be scaled (i.e. Qty 6 of the 22x8 Palette can be used for a 1056 sf Filterra Bioscape). MIX & MATCH SUBSTITUTION OPTIONS: 1 Large Shrub or Extra Large Shrub or Tree • 2 Medium Shrubs • 4 Small Grass/SHrubs • 12 Extra Small Grasses 1 Medium Shrub • 2 Small Grass/Shrubs • 6 Extra Small Grasses 1 Small Grass/Shrub • 3 Extra Small Grasses www.ContechES.com/filterra | 800-338-1122 19 Filterra Activation Package | Page 7 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® A. 24 A. 28 A. 32 A. 36 B. 8 B. 8 B. 10 B. 10 C. 4 C. 4 C. 5 C. 5 D. 2 D. 2 D. 3 D. 3 16x8 & 15x9 Media Bay 18x8 Media Bay 20x8 Media Bay 22x8 Media Bay Appendix 2 – Filterra® Tree Grate Opening Expansion Procedure The standard grates used on all Filterra configurations that employ Tree Grates are fabricated with a 6” opening that is designed with a breakaway section that can be removed, allowing the grate opening to be expanded to 12” as the tree matures and the trunk widens. The following tools are required to expand the opening: • Mini sledgehammer (3 lb. or greater) • Safety Glasses / Goggles The following guidelines should be followed to properly expand the tree opening from 6” to 12”: 1. Remove the grate from the Filterra frame, place it flat on a hard surface, and support the grate by stepping on the edge or using other weighted items such as a few mulch bags if this is being done during a Filterra maintenance event. Put on safety glasses/goggles. Align the mini sledgehammer as shown in the figure to the left. The head of the sledgehammer should be aimed just inside the wide cast iron bar between the larger grate section and the breakaway section. 2. Repeatedly hit the grate at this spot with the mini sledgehammer. 3. After several hits, the breakaway section should snap cleanly off of the larger grate section. Reinstall the grate into the Filterra grate frame. Recycle or dispose of the breakaway section per local guidelines. 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___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS CDS Guide Operation, Design, Performance and Maintenance ENGINEERED SOLUTIONS 2 CDS® Using patented continuous deflective separation technology, the CDS system screens, separates and traps debris, sediment, and oil and grease from stormwater runoff. The indirect screening capability of the system allows for 100% removal of floatables and neutrally buoyant material without blinding. Flow and screening controls physically separate captured solids, and minimize the re-suspension and release of previously trapped pollutants. Inline units can treat up to 6 cfs, and internally bypass flows in excess of 50 cfs (1416 L/s). Available precast or cast-in- place, offline units can treat flows from 1 to 300 cfs (28.3 to 8495 L/s). The pollutant removal capacity of the CDS system has been proven in lab and field testing. Operation Overview Stormwater enters the diversion chamber where the diversion weir guides the flow into the unit’s separation chamber and pollutants are removed from the flow. All flows up to the system’s treatment design capacity enter the separation chamber and are treated. Swirl concentration and screen deflection force floatables and solids to the center of the separation chamber where 100% of floatables and neutrally buoyant debris larger than the screen apertures are trapped. Stormwater then moves through the separation screen, under the oil baffle and exits the system. The separation screen remains clog free due to continuous deflection. During the flow events exceeding the treatment design capacity, the diversion weir bypasses excessive flows around the separation chamber, so captured pollutants are retained in the separation cylinder. Design Basics There are three primary methods of sizing a CDS system. The Water Quality Flow Rate Method determines which model size provides the desired removal efficiency at a given flow rate for a defined particle size. The Rational Rainfall Method™ or the and Probabilistic Method is used when a specific removal efficiency of the net annual sediment load is required. Typically in the Unites States, CDS systems are designed to achieve an 80% annual solids load reduction based on lab generated performance curves for a gradation with an average particle size (d50) of 125 microns (μm). For some regulatory environments, CDS systems can also be designed to achieve an 80% annual solids load reduction based on an average particle size (d50) of 75 microns (μm) or 50 microns (μm). Water Quality Flow Rate Method In some cases, regulations require that a specific treatment rate, often referred to as the water quality design flow (WQQ), be treated. This WQQ represents the peak flow rate from either an event with a specific recurrence interval, e.g. the six-month storm, or a water quality depth, e.g. 1/2-inch (13 mm) of rainfall. The CDS is designed to treat all flows up to the WQQ. At influent rates higher than the WQQ, the diversion weir will direct most flow exceeding the WQQ around the separation chamber. This allows removal efficiency to remain relatively constant in the separation chamber and eliminates the risk of washout during bypass flows regardless of influent flow rates. Treatment flow rates are defined as the rate at which the CDS will remove a specific gradation of sediment at a specific removal efficiency. Therefore the treatment flow rate is variable, based on the gradation and removal efficiency specified by the design engineer. Rational Rainfall Method™ Differences in local climate, topography and scale make every site hydraulically unique. It is important to take these factors into consideration when estimating the long-term performance of any stormwater treatment system. The Rational Rainfall Method combines site-specific information with laboratory generated performance data, and local historical precipitation records to estimate removal efficiencies as accurately as possible. Short duration rain gauge records from across the United States and Canada were analyzed to determine the percent of the total annual rainfall that fell at a range of intensities. US stations’ depths were totaled every 15 minutes, or hourly, and recorded in 0.01-inch increments. Depths were recorded hourly with 1-mm resolution at Canadian stations. One trend was consistent at all sites; the vast majority of precipitation fell at low intensities and high intensity storms contributed relatively little to the total annual depth. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Rainfall Method. Since most sites are relatively small and highly impervious, the Rational Rainfall Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS system are GRATE INLET(CAST IRON HOOD FORCURB INLET OPENING) CREST OF BYPASS WEIR(ONE EACH SIDE) INLET(MULTIPLE PIPES POSSIBLE) OIL BAFFLE SUMP STORAGESEPARATION SLAB TREATMENT SCREEN OUTLET INLET FLUME SEPARATION CYLINDER CLEAN OUT(REQUIRED) DEFLECTION PAN, 3 SIDED(GRATE INLET DESIGN) 3 determined. Performance efficiency curve determined from full scale laboratory tests on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Probabilistic Rational Method The Probabilistic Rational Method is a sizing program Contech developed to estimate a net annual sediment load reduction for a particular CDS model based on site size, site runoff coefficient, regional rainfall intensity distribution, and anticipated pollutant characteristics. The Probabilistic Method is an extension of the Rational Method used to estimate peak discharge rates generated by storm events of varying statistical return frequencies (e.g. 2-year storm event). Under the Rational Method, an adjustment factor is used to adjust the runoff coefficient estimated for the 10-year event, correlating a known hydrologic parameter with the target storm event. The rainfall intensities vary depending on the return frequency of the storm event under consideration. In general, these two frequency dependent parameters (rainfall intensity and runoff coefficient) increase as the return frequency increases while the drainage area remains constant. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Method. Since most sites are relatively small and highly impervious, the Rational Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS are determined. Performance efficiency curve on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Treatment Flow Rate The inlet throat area is sized to ensure that the WQQ passes through the separation chamber at a water surface elevation equal to the crest of the diversion weir. The diversion weir bypasses excessive flows around the separation chamber, thus preventing re-suspension or re-entrainment of previously captured particles. Hydraulic Capacity The hydraulic capacity of a CDS system is determined by the length and height of the diversion weir and by the maximum allowable head in the system. Typical configurations allow hydraulic capacities of up to ten times the treatment flow rate. The crest of the diversion weir may be lowered and the inlet throat may be widened to increase the capacity of the system at a given water surface elevation. The unit is designed to meet project specific hydraulic requirements. Performance Full-Scale Laboratory Test Results A full-scale CDS system (Model CDS2020-5B) was tested at the facility of University of Florida, Gainesville, FL. This CDS unit was evaluated under controlled laboratory conditions of influent flow rate and addition of sediment. Two different gradations of silica sand material (UF Sediment & OK-110) were used in the CDS performance evaluation. The particle size distributions (PSDs) of the test materials were analyzed using standard method “Gradation ASTM D-422 “Standard Test Method for Particle-Size Analysis of Soils” by a certified laboratory. UF Sediment is a mixture of three different products produced by the U.S. Silica Company: “Sil-Co-Sil 106”, “#1 DRY” and “20/40 Oil Frac”. Particle size distribution analysis shows that the UF Sediment has a very fine gradation (d50 = 20 to 30 μm) covering a wide size range (Coefficient of Uniformity, C averaged at 10.6). In comparison with the hypothetical TSS gradation specified in the NJDEP (New Jersey Department of Environmental Protection) and NJCAT (New Jersey Corporation for Advanced Technology) protocol for lab testing, the UF Sediment covers a similar range of particle size but with a finer d50 (d50 for NJDEP is approximately 50 μm) (NJDEP, 2003). The OK-110 silica sand is a commercial product of U.S. Silica Sand. The particle size distribution analysis of this material, also included in Figure 1, shows that 99.9% of the OK-110 sand is finer than 250 microns, with a mean particle size (d50) of 106 microns. The PSDs for the test material are shown in Figure 1. Figure 1. Particle size distributions Tests were conducted to quantify the performance of a specific CDS unit (1.1 cfs (31.3-L/s) design capacity) at various flow rates, ranging from 1% up to 125% of the treatment design capacity of the unit, using the 2400 micron screen. All tests were conducted with controlled influent concentrations of approximately 200 mg/L. Effluent samples were taken at equal time intervals across the entire duration of each test run. These samples were then processed with a Dekaport Cone sample splitter to obtain representative sub-samples for Suspended Sediment Concentration (SSC) testing using ASTM D3977-97 “Standard Test Methods for Determining Sediment Concentration in Water Samples”, and particle size distribution analysis. Results and Modeling Based on the data from the University of Florida, a performance model was developed for the CDS system. A regression analysis was used to develop a fitting curve representative of the scattered data points at various design flow rates. This model, which demonstrated good agreement with the laboratory data, can then be used to predict CDS system performance with respect 4 to SSC removal for any particle size gradation, assuming the particles are inorganic sandy-silt. Figure 2 shows CDS predictive performance for two typical particle size gradations (NJCAT gradation and OK-110 sand) as a function of operating rate. Figure 2. CDS stormwater treatment predictive performance for various particle gradations as a function of operating rate. Many regulatory jurisdictions set a performance standard for hydrodynamic devices by stating that the devices shall be capable of achieving an 80% removal efficiency for particles having a mean particle size (d50) of 125 microns (e.g. Washington State Department of Ecology — WASDOE - 2008). The model can be used to calculate the expected performance of such a PSD (shown in Figure 3). The model indicates (Figure 4) that the CDS system with 2400 micron screen achieves approximately 80% removal at the design (100%) flow rate, for this particle size distribution (d50 = 125 μm). Figure 3. WASDOE PSD Figure 4. Modeled performance for WASDOE PSD. Maintenance The CDS system should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit. For example, unstable soils or heavy winter sanding will cause the grit chamber to fill more quickly but regular sweeping of paved surfaces will slow accumulation. Inspection Inspection is the key to effective maintenance and is easily performed. Pollutant transport and deposition may vary from year to year and regular inspections will help ensure that the system is cleaned out at the appropriate time. At a minimum, inspections should be performed twice per year (e.g. spring and fall) however more frequent inspections may be necessary in climates where winter sanding operations may lead to rapid accumulations, or in equipment washdown areas. Installations should also be inspected more frequently where excessive amounts of trash are expected. The visual inspection should ascertain that the system components are in working order and that there are no blockages or obstructions in the inlet and separation screen. The inspection should also quantify the accumulation of hydrocarbons, trash, and sediment in the system. Measuring pollutant accumulation can be done with a calibrated dipstick, tape measure or other measuring instrument. If absorbent material is used for enhanced removal of hydrocarbons, the level of discoloration of the sorbent material should also be identified 5 during inspection. It is useful and often required as part of an operating permit to keep a record of each inspection. A simple form for doing so is provided. Access to the CDS unit is typically achieved through two manhole access covers. One opening allows for inspection and cleanout of the separation chamber (cylinder and screen) and isolated sump. The other allows for inspection and cleanout of sediment captured and retained outside the screen. For deep units, a single manhole access point would allows both sump cleanout and access outside the screen. The CDS system should be cleaned when the level of sediment has reached 75% of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accumulated. If absorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100% of the sump capacity is exceeded however it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimating the level of sediment in the chamber, the measuring device must be lowered to the top of the sediment pile carefully. Particles at the top of the pile typically offer less resistance to the end of the rod than consolidated particles toward the bottom of the pile. Once this measurement is recorded, it should be compared to the as-built drawing for the unit to determine weather the height of the sediment pile off the bottom of the sump floor exceeds 75% of the total height of isolated sump. Cleaning Cleaning of a CDS systems should be done during dry weather conditions when no flow is entering the system. The use of a vacuum truck is generally the most effective and convenient method of removing pollutants from the system. Simply remove the manhole covers and insert the vacuum hose into the sump. The system should be completely drained down and the sump fully evacuated of sediment. The area outside the screen should also be cleaned out if pollutant build-up exists in this area. In installations where the risk of petroleum spills is small, liquid contaminants may not accumulate as quickly as sediment. However, the system should be cleaned out immediately in the event of an oil or gasoline spill. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use absorbent pads since they are usually less expensive to dispose than the oil/water emulsion that may be created by vacuuming the oily layer. Trash and debris can be netted out to separate it from the other pollutants. The screen should be cleaned to ensure it is free of trash and debris. Manhole covers should be securely seated following cleaning activities to prevent leakage of runoff into the system from above and also to ensure that proper safety precautions have been followed. Confined space entry procedures need to be followed if physical access is required. Disposal of all material removed from the CDS system should be done in accordance with local regulations. In many jurisdictions, disposal of the sediments may be handled in the same manner as the disposal of sediments removed from catch basins or deep sump manholes. Check your local regulations for specific requirements on disposal. 6 Note: To avoid underestimating the volume of sediment in the chamber, carefully lower the measuring device to the top of the sediment pile. Finer silty particles at the top of the pile may be more difficult to feel with a measuring stick. These finer particles typically offer less resistance to the end of the rod than larger particles toward the bottom of the pile. CDS Model Diameter Distance from Water Surface to Top of Sediment Pile Sediment Storage Capacity ft m ft m y3 m3 CDS1515 3 0.9 3.0 0.9 0.5 0.4 CDS2015 4 1.2 3.0 0.9 0.9 0.7 CDS2015 5 1.5 3.0 0.9 1.3 1.0 CDS2020 5 1.5 3.5 1.1 1.3 1.0 CDS2025 5 1.5 4.0 1.2 1.3 1.0 CDS3020 6 1.8 4.0 1.2 2.1 1.6 CDS3025 6 1.8 4.0 1.2 2.1 1.6 CDS3030 6 1.8 4.6 1.4 2.1 1.6 CDS3035 6 1.8 5.0 1.5 2.1 1.6 CDS4030 8 2.4 4.6 1.4 5.6 4.3 CDS4040 8 2.4 5.7 1.7 5.6 4.3 CDS4045 8 2.4 6.2 1.9 5.6 4.3 CDS5640 10 3.0 6.3 1.9 8.7 6.7 CDS5653 10 3.0 7.7 2.3 8.7 6.7 CDS5668 10 3.0 9.3 2.8 8.7 6.7 CDS5678 10 3.0 10.3 3.1 8.7 6.7 Table 1: CDS Maintenance Indicators and Sediment Storage Capacities 7 CDS Inspection & Maintenance Log CDS Model: Location: Water Floatable Describe Maintenance Date depth to Layer Maintenance Personnel Comments sediment1 Thickness2 Performed —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— 1. The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than the values listed in table 1 the system should be cleaned out. Note: to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. 2. For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. SUPPORT • Drawings and specifications are available at www.ContechES.com. • Site-specific design support is available from our engineers. ©2017 Contech Engineered Solutions LLC, a QUIKRETE Company Contech Engineered Solutions provides site solutions for the civil engineering industry. Contech’s portfolio includes bridges, drainage, sanitary sewer, earth stabilization and stormwater treatment products. For information on other Contech division offerings, visit www.ContechES.com or call 800.338.1122 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. The product(s) described may be protected by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6,027,639; 6,350,374; 6,406,218; 6,641,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296,692; 7,297,266; related foreign patents or other patents pending. 800-338-1122 www.ContechES.com cds_manual 3/17 PDF ENGINEERED SOLUTIONS RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 19 10. FIGURES FIGURE 1 – TIR WORKSHEET FIGURE 2 – VICINITY MAP FIGURE 3 – EXISTING CONDITIONS FIGURE 4 – PROPOSED CONDITIONS FIGURE 5 – NEW AND REPLACED IMPERVIOUS AREAS FIGURE 6 – PROJECT MINIMUM REQUIREMENTS FLOW CHART FIGURE 7 – OFFSITE DRAINAGE FIGURE 8 – 100 YEAR FLOODPLAIN FIGURE 9 – SOILS MAP FIGURE 10 – WATER QUALITY AREA SWAP FIGURE 11 – AQUIFER PROTECTION ZONES CITY OF RENTON SURFACE WATER DESIGN MANUAL 2022 City of Renton Surface Water Design Manual 6/22/2022 8-A-1 REFERENCE 8-A TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner _____________________________ Phone ___________________________________ Address __________________________________ _________________________________________ Project Engineer ___________________________ Company _________________________________ Phone ___________________________________ Project Name __________________________ CED Permit # ________________________ Location Township ________________ Range __________________ Section _________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Land Use (e.g., Subdivision / Short Subd.) Building (e.g., M/F / Commercial / SFR) Grading Right-of-Way Use Other _______________________ DFW HPA COE 404 DOE Dam Safety FEMA Floodplain COE Wetlands Other ________ Shoreline Management Structural Rockery/Vault/_____ ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review (check one): Date (include revision dates): Date of Final: Full Targeted Simplified Large Project Directed __________________ __________________ __________________ Plan Type (check one): Date (include revision dates): Date of Final: Full Modified Simplified __________________ __________________ __________________ FIGURE 1: TIR WORKSHEET Renton School District (206) 482-5253 7812 South 124th Street Seattle, WA 98178 Sascha Eastman Jacobson Consulting Engineers (206) 426-2600 Renton School District Transportation Expansion 410 Park Ave N Renton, WA 98057 23N 5E 08 N/A 10/30/2024 5/21/2025 10/30/2024 5/21/2025 C25001104 4/14/2025 4/14/2025 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-2 Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Blanket Description: (include conditions in TIR Section 2) ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ Approved Adjustment No. ______________________ Date of Approval: _______________________ Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ Re: SWDM Adjustment No. ________________ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: ____________________________________________________________________ Special District Overlays: ______________________________________________________________ Drainage Basin: _____________________________________________________________________ Stormwater Requirements: _____________________________________________________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/Stream ________________________ Lake ______________________________ Wetlands ____________________________ Closed Depression ____________________ Floodplain ___________________________ Other _______________________________ _______________________________ Steep Slope __________________________ Erosion Hazard _______________________ Landslide Hazard ______________________ Coal Mine Hazard ______________________ Seismic Hazard _______________________ Habitat Protection ______________________ _____________________________________ FIGURE 1: TIR WORKSHEET N/A N/A N/A Cedar River N/A N/A N/A N/A Zones 1 & 2 Aquifer Protection Area REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2022 City of Renton Surface Water Design Manual 6/22/2022 Ref 8-A-3 Part 10 SOILS Soil Type ______________________ ______________________ ______________________ ______________________ Slopes ________________________ ________________________ ________________________ ________________________ Erosion Potential _________________________ _________________________ _________________________ _________________________ High Groundwater Table (within 5 feet) Other ________________________________ Sole Source Aquifer Seeps/Springs Additional Sheets Attached Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core 2 – Offsite Analysis_________________ Sensitive/Critical Areas__________________ SEPA________________________________ LID Infeasibility________________________ Other________________________________ _____________________________________ LIMITATION / SITE CONSTRAINT _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Core Requirements (all 9 apply): Discharge at Natural Location Number of Natural Discharge Locations: Offsite Analysis Level: 1 / 2 / 3 dated:__________________ Flow Control (include facility summary sheet) Standard: _______________________________ or Exemption Number: ____________ Conveyance System Spill containment located at: _____________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: _____________________ Contact Phone: _________________________ After Hours Phone: _________________________ Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Holocene Alluvium 0% - 5%Moderate N/A Cedar River Drainage Basin FIGURE 1: TIR WORKSHEET 1 N/A TBD TBD TBD #1: < 0.15 cfs flow increase 2/16/2022 Peak Rate Standard REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-4 Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Water Quality (include facility summary sheet) Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. _______________________ On-site BMPs Describe: Special Requirements (as applicable): Area Specific Drainage Requirements Type: SDO / MDP / BP / Shared Fac. / None Name: ________________________ Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): _______________ Datum: Flood Protection Facilities Describe: Source Control (commercial / industrial land use) Describe land use: Describe any structural controls: Oil Control High-Use Site: Yes / No Treatment BMP: _________________________________ Maintenance Agreement: Yes / No with whom? _____________________________________ Other Drainage Structures Describe: FIGURE 1: TIR WORKSHEET N/A N/A N/A Contech CDS Separator REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2022 City of Renton Surface Water Design Manual 6/22/2022 Ref 8-A-5 Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION Clearing Limits Cover Measures Perimeter Protection Traffic Area Stabilization Sediment Retention Surface Water Collection Dewatering Control Dust Control Flow Control Control Pollutants Protect Existing and Proposed BMPs/Facilities Maintain Protective BMPs / Manage Project MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize exposed surfaces Remove and restore Temporary ESC Facilities Clean and remove all silt and debris, ensure operation of Permanent BMPs/Facilities, restore operation of BMPs/Facilities as necessary Flag limits of sensitive areas and open space preservation areas Other _______________________ Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Description Water Quality Description On-site BMPs Description Detention Infiltration Regional Facility Shared Facility Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Vegetated Flowpath Wetpool Filtration Oil Control Spill Control Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Full Dispersion Full Infiltration Limited Infiltration Rain Gardens Bioretention Permeable Pavement Basic Dispersion Soil Amendment Perforated Pipe Connection Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ FIGURE 1: TIR WORKSHEET N/A N/A Filterra N/A N/A CDS Separator REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-6 Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Covenant Tract Other ____________________________ Cast in Place Vault Retaining Wall Rockery > 4′ High Structural on Steep Slope Other _______________________________ Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. ____________________________________________________________________________________ Signed/Date FIGURE 1: TIR WORKSHEET N/A N/A 5/21/2025 255 S. King Street, Suite 800, Seattle, WA 98104 | 206.399.6233 | JACOBSONENGINEERS.COM206.426.2600 FIGURE 2: VICINITY MAPSCALE: NTS Project Site Project Site FIGURE 3: EXISTING CONDITIONS SCALE 1" = 40' 0 20 40 80 Pa r k A v e N o r t h d Quantity Unit e 0.278 ac 0.210 ac Legend Description Quantity Unit Impervious Surface 0.278 ac Landscape 0.210 ac SCALE 1" = 40' 0 20 40 80 FIGURE 4: PROPOSED CONDITIONS Pa r k A v e N o r t h X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Legend Description Quantity Unit Impervious Surface 0.368 ac Landscape 0.120 ac FIGURE 5: NEW AND REPLACED IMPERVIOUS AREAS SCALE 1" = 40' 0 20 40 80 Pa r k A v e N o r t h X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Legend Description Quantity Unit New Impervious 0.151 ac Replaced Impervious 0.218 ac FIGURE 6: PROJECT MINIMUM REQUIREMENTS FLOWCHART FIGURE 7: OFFSITE ANALYSIS PROJECT SITE 1/4 MILE DOWNSTREAM DISCHARGES TO CEDAR RIVER FIGURE 8: 100 YR FLOODPLAIN PROJECT SITE FEMA FLOOD MAP 53033C0977G FIGURE 9: SOILS MAP 9 Custom Soil Resource Report Soil Map 52 5 9 8 6 0 52 5 9 8 7 0 52 5 9 8 8 0 52 5 9 8 9 0 52 5 9 9 0 0 52 5 9 9 1 0 52 5 9 9 2 0 525 9 9 3 0 52 5 9 9 4 0 525 9 9 5 0 52 5 9 9 6 0 525 9 8 6 0 52 5 9 8 7 0 525 9 8 8 0 52 5 9 8 9 0 525 9 9 0 0 52 5 9 9 1 0 525 9 9 2 0 52 5 9 9 3 0 525 9 9 4 0 52 5 9 9 5 0 525 9 9 6 0 560080 560090 560100 560110 560120 560130 560140 560150 560160 560080 560090 560100 560110 560120 560130 560140 560150 560160 47° 29' 25'' N 12 2 ° 1 2 ' 8 ' ' W 47° 29' 25'' N 12 2 ° 1 2 ' 4 ' ' W 47° 29' 21'' N 12 2 ° 1 2 ' 8 ' ' W 47° 29' 21'' N 12 2 ° 1 2 ' 4 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS840 25 50 100 150 Feet0 5 10 20 30 MetersMap Scale: 1:532 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 19, Aug 29, 2023 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 31, 2022—Aug 8, 2022 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI Ur Urban land 0.9 100.0% Totals for Area of Interest 0.9 100.0% SCALE 1" = 40' 0 20 40 80 FIGURE 10: WATER QUALITY AREA SWAP Pa r k A v e N o r t h X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Legend Description Quantity Unit Area Swap 3,848 sf Bypass 3,835 sf Landscape 1,442 sf Paving 11,491 sf FIGURE 11: AQUIFER PROTECTION ZONES PROJECT SITE RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 20 11. APPENDICES APPENDIX A – BOND QUANTITY WORKSHEET APPENDIX B – STORMWATER CALCULATIONS APPENDIX C – STORMWATER POLLUTION PREVENTION PLAN (SWPPP) APPENDIX D – FACILITY SUMMARY SHEET, DECLARATION OF COVENANT RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 21 APPENDIX A BOND QUANTITY WORKSHEET BOND QUANTITY WORKSHEET INSTRUCTIONS 1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200 This worksheet is intended to be a "working" copy of the bond quantity worksheet, which will be used throughout all phases of the project, from initial submittal to project close-out approval. Submit this workbook, in its entirety, as follows: •(1) electronic copy (.xlsx format) and (1) hard copy of the entire workbook for civil construction permit submittal. Hard copies are to be included as part of the Technical Information Report (TIR). •(1) electronic copy (.xlsx format) and (1) hard copy of the entire workbook for final close-out submittal. The following forms are to be completed by the engineer/developer/applicant as applicable to the project: Section I: Project Information •This section includes all pertinent information for the project •This section must be completed in its entirety •Information from this section auto-populates to all other relevant areas of the workbook Section II: Bond Quantities Worksheets •Section II contains a separate spreadsheet TAB for each of the following specialties: •Section II.a EROSION CONTROL (Stabilization/Erosion Sediment Control (ESC)) •Section II.b TRANSPORTATION (Street and Site Improvements) •Section II.c DRAINAGE (Drainage and Stormwater Facilities): •Section II.d WATER - ONLY APPLICABLE IF WATER SERVICE IS PROVIDED BY CITY OF RENTON •Section II.e SANITARY SEWER - ONLY APPLICABLE IF SEWER SERVICE IS PROVIDED BY CITY OF RENTON •Complete the 'Quantity' columns for each of the appropriate section(s). Include existing Right-of-Way (ROW), Future Public Improvements and Private Improvements. •Note: Private improvements, with the exception of stormwater facilities, are not included in the bond amount calculation, but must be entered on the form. Stormwater facilities (public and private) are required to be included in the bond amount. •The 'Quantity Remaining' column is only to be used when a project is under construction. The City allows one (1) bond reduction during the life of the project with the exception of the maintenance period reduction. •Excel will auto-calculate and auto-populate the relevant fields and subtotals throughout the document. Only the 'Quantity' columns should need completing. •Additional items not included in the lists can be added under the "write-in" sections. Provide a complete description, cost estimate and unit of measure for each write-in item. •All unit prices include labor, equipment, materials, overhead, profit, and taxes. The Bond Worksheet form will auto-calculate and auto-populate from the information provided in Section I and Section II. Section III. Bond Worksheet •This section calculates the required Permit Bond for construction permit issuance as well as the required Maintenance Bond for project close-out submittals to release the permit bond on a project. Page 1 of 16 Ref 8-H Bond Quantity Worksheet INSTRUCTIONS Version: 4/1/2024 Printed 5/13/2025 SITE IMPROVEMENT BOND QUANTITY WORKSHEET PROJECT INFORMATION 1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200 Date Prepared: 5/21/2024 Project Phase 1 FOR APPROVAL Prepared by:Engineer Stamp Required (all cost estimates must have original wet stamp and signature)Name:Alan Jacobson PE Registration No:43667 Firm Name:Jacobson Consulting Engineers Firm Address:255 S King St, Suite 800, Seattle, WA 98104 Phone No.206.426.2600 Email Address:alan@jacobsonengineers.com Project Location and Description Project Owner Information Project Name: RSD Transportation Expansion Project Owner:Andrew Hollenback c/o Renton School District CED Plan # (LUA):LUA24-000376 Phone:425.204.4437 CED Permit # (C):C25001104 Address: 7812 S 124th St Site Address:420 Park Ave N, Renton, WA 98057 Seattle, WA 98178 Street Intersection:Park Ave N and N 4th Street Addt'l Project Owner: Parcel #(s):7224000676, 7224000675, 7564600105 Phone: Abbreviated Legal Description: RENTON FARM PLAT LOT A OF RENTON LLA LUA-11-016-LLA REC #20110616900016 SD LLA BEING LOTS 10 THRU 13 BLK 8 OF SD PLAT (7224000676), RENTON FARM PLAT LOT B OF RENTON LLA LUA-11-016- LLA REC #20110616900016 SD LLA BEING LOTS 10 THRU 13 BLK 8 OF SD PLAT (7224000675), SARTORISVILLE ADD TGW LOTS 1 THRU 9 BLK 8 OF PLAT OF RENTON FORM PLAT LESS RDS (7564600105) Address: Clearing and Grading Utility Providers Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No:NO Water Service Provided by:CITY OF RENTON If Yes, Provide Forest Practice Permit #:N/A Sewer Service Provided by: CITY OF RENTON Estimated Civil Construction Permit - Construction Costs2 As outlined in City Ordinance No. 4345, 50% of the plan review and inspection fees are to be paid at Permit Submittal. The balance is due at Permit Issuance. Significant changes or additional review cycles (beyond 3 cycles) during the review process may result in adjustments to the final review fees. Water A $- Wastewater (Sanitary Sewer)B $- Stormwater (Drainage)C $49,628.38 Roadway (Erosion Control + Transportation)D $217,018.95 Total Estimated Construction Costs E A + B + C + D $266,647.33 Page 2 of 16 Ref 8-H Bond Quantity Worksheet SECTION I PROJECT INFORMATION Version 4/1/2024 Printed 5/13/2025 1 Select the current project status/phase from the following options: For Approval - Preliminary Data Enclosed, pending approval from the City; For Construction - Estimated Data Enclosed, Plans have been approved for contruction by the City; Project Closeout - Final Costs and Quantities Enclosed for Project Close-out Submittal 2 All prices include labor, equipment, materials, overhead, profit, and taxes. City of Renton Sales Tax is:10.3% Page 3 of 16 Ref 8-H Bond Quantity Worksheet SECTION I PROJECT INFORMATION Version 4/1/2024 Printed 5/13/2025 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR EROSION & SEDIMENT CONTROL CED Permit #:C25001104 Description No. Unit (A) Reference #Price Unit Quantity Cost Backfill & compaction-embankment ESC-1 $7.50 CY Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 $90.00 Each Catch Basin Protection ESC-3 $145.00 Each 8 1,160.00 Crushed surfacing 1 1/4" minus ESC-4 WSDOT 9-03.9(3)$110.00 CY Ditching ESC-5 $10.50 CY Excavation-bulk ESC-6 $2.30 CY Fence, silt ESC-7 SWDM 5.4.3.1 $5.00 LF 90 450.00 Fence, Temporary (NGPE)ESC-8 $1.75 LF Geotextile Fabric ESC-9 $3.00 SY 240 720.00 Hay Bale Silt Trap ESC-10 $0.60 Each Hydroseeding ESC-11 SWDM 5.4.2.4 $0.90 SY Interceptor Swale / Dike ESC-12 $1.15 LF 434 499.10 Jute Mesh ESC-13 SWDM 5.4.2.2 $4.00 SY Level Spreader ESC-14 $2.00 LF Mulch, by hand, straw, 3" deep ESC-15 SWDM 5.4.2.1 $2.90 SY Mulch, by machine, straw, 2" deep ESC-16 SWDM 5.4.2.1 $2.30 SY Piping, temporary, CPP, 6"ESC-17 $13.75 LF Piping, temporary, CPP, 8"ESC-18 $16.00 LF Piping, temporary, CPP, 12"ESC-19 $20.50 LF Plastic covering, 6mm thick, sandbagged ESC-20 SWDM 5.4.2.3 $4.60 SY Rip Rap, machine placed; slopes ESC-21 WSDOT 9-13.1(2)$51.00 CY Rock Construction Entrance, 50'x15'x1'ESC-22 SWDM 5.4.4.1 $2,050.00 Each Rock Construction Entrance, 100'x15'x1'ESC-23 SWDM 5.4.4.1 $3,675.00 Each 1 3,675.00 Sediment pond riser assembly ESC-24 SWDM 5.4.5.2 $2,525.00 Each Sediment trap, 5' high berm ESC-25 SWDM 5.4.5.1 $22.00 LF 26 572.00 Sed. trap, 5' high, riprapped spillway berm section ESC-26 SWDM 5.4.5.1 $80.00 LF Seeding, by hand ESC-27 SWDM 5.4.2.4 $1.15 SY Sodding, 1" deep, level ground ESC-28 SWDM 5.4.2.5 $9.20 SY Sodding, 1" deep, sloped ground ESC-29 SWDM 5.4.2.5 $11.50 SY TESC Supervisor ESC-30 $125.00 HR 80 10,000.00 Water truck, dust control ESC-31 SWDM 5.4.7 $160.00 HR WRITE-IN-ITEMS Unit Reference #Price Unit Quantity Cost Straw Wattles SWDM D.2.1.2.5 $4.00 LF 650 2,600.00 EROSION/SEDIMENT SUBTOTAL:19,676.10 SALES TAX @ 10.3%2,026.64 EROSION/SEDIMENT TOTAL:21,702.74 (A) Page 4 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.a EROSION_CONTROL Version: 4/01/2024 Printed 5/13/2025 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost GENERAL ITEMS Backfill & Compaction- embankment GI-1 $7.00 CY Backfill & Compaction- trench GI-2 $10.25 CY Clear/Remove Brush, by hand (SY)GI-3 $1.15 SY Bollards - fixed GI-4 $275.00 Each Bollards - removable GI-5 $520.00 Each Clearing/Grubbing/Tree Removal GI-6 $11,475.00 Acre Excavation - bulk GI-7 $2.30 CY 45 103.50 Excavation - Trench GI-8 $5.75 CY Fencing, cedar, 6' high GI-9 $23.00 LF Fencing, chain link, 4'GI-10 $44.00 LF Fencing, chain link, vinyl coated, 6' high GI-11 $23.00 LF 431 9,913.00 Fencing, chain link, gate, vinyl coated, 20' GI-12 $1,600.00 Each 2 3,200.00 Fill & compact - common barrow GI-13 $28.75 CY 375 10,781.25 Fill & compact - gravel base GI-14 $31.00 CY Fill & compact - screened topsoil GI-15 $44.75 CY Gabion, 12" deep, stone filled mesh GI-16 $74.50 SY Gabion, 18" deep, stone filled mesh GI-17 $103.25 SY Gabion, 36" deep, stone filled mesh GI-18 $172.00 SY Grading, fine, by hand GI-19 $2.90 SY 305 884.50 Grading, fine, with grader GI-20 $2.30 SY 1520 3,496.00 Monuments, 3' Long GI-21 $1,025.00 Each Sensitive Areas Sign GI-22 $8.00 Each Sodding, 1" deep, sloped ground GI-23 $9.25 SY Surveying, line & grade GI-24 $975.00 Day Surveying, lot location/lines GI-25 $2,050.00 Acre Topsoil Type A (imported)GI-26 $32.75 CY Traffic control crew ( 2 flaggers )GI-27 $137.75 HR Trail, 4" chipped wood GI-28 $9.15 SY Trail, 4" crushed cinder GI-29 $10.25 SY Trail, 4" top course GI-30 $13.75 SY Conduit, 2"GI-31 $5.75 LF Wall, retaining, concrete GI-32 $63.00 SF Wall, rockery GI-33 $17.25 SF SUBTOTAL THIS PAGE:28,378.25 (B)(C)(D)(E) Page 5 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Version: 4/1/2024 Printed 5/13/2025 ROAD IMPROVEMENT/PAVEMENT/SURFACING AC Grinding, 4' wide machine < 1000sy RI-1 $34.50 SY AC Grinding, 4' wide machine 1000-2000sy RI-2 $18.25 SY AC Grinding, 4' wide machine > 2000sy RI-3 $11.50 SY AC Removal/Disposal RI-4 $40.00 SY 20 800.00 1340 53,600.00 Barricade, Type III ( Permanent )RI-5 $64.25 LF Guard Rail RI-6 $34.50 LF Curb & Gutter, rolled RI-7 $19.50 LF Curb & Gutter, vertical RI-8 $14.25 LF 90 1,282.50 700 9,975.00 Curb and Gutter, demolition and disposal RI-9 $20.50 LF 90 1,845.00 525 10,762.50 Curb, extruded asphalt RI-10 $6.25 LF Curb, extruded concrete RI-11 $8.00 LF Sawcut, asphalt, 3" depth RI-12 $3.00 LF 102 306.00 260 780.00 Sawcut, concrete, per 1" depth RI-13 $5.00 LF 30 150.00 Sealant, asphalt RI-14 $2.25 LF 102 229.50 260 585.00 Shoulder, gravel, 4" thick RI-15 $17.25 SY Sidewalk, 4" thick RI-16 $43.50 SY 70 3,045.00 215 9,352.50 Sidewalk, 4" thick, demolition and disposal RI-17 $37.00 SY 70 2,590.00 Sidewalk, 5" thick RI-18 $47.00 SY Sidewalk, 5" thick, demolition and disposal RI-19 $46.00 SY Sign, Handicap RI-20 $97.00 Each 1 97.00 Striping, per stall RI-21 $8.00 Each 45 360.00 Striping, thermoplastic, ( for crosswalk )RI-22 $3.50 SF Striping, 4" reflectorized line RI-23 $0.55 LF Additional 2.5" Crushed Surfacing RI-24 $4.15 SY HMA 1/2" Overlay 1.5" RI-25 $16.00 SY HMA 1/2" Overlay 2"RI-26 $20.75 SY HMA Road, 2", 4" rock, First 2500 SY RI-27 $32.25 SY HMA Road, 2", 4" rock, Qty. over 2500SY RI-28 $24.00 SY HMA Road, 4", 6" rock, First 2500 SY RI-29 $51.75 SY 20 1,035.00 HMA Road, 4", 6" rock, Qty. over 2500 SY RI-30 $42.50 SY HMA Road, 4", 4.5" ATB RI-31 $43.50 SY Gravel Road, 4" rock, First 2500 SY RI-32 $17.25 SY Gravel Road, 4" rock, Qty. over 2500 SY RI-33 $11.50 SY Thickened Edge RI-34 $10.00 LF SUBTOTAL THIS PAGE:11,283.00 85,512.00 (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Page 6 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Version: 4/1/2024 Printed 5/13/2025 PARKING LOT SURFACING No. 2" AC, 2" top course rock & 4" borrow PL-1 $24.00 SY 2" AC, 1.5" top course & 2.5" base course PL-2 $32.00 SY 1622 51,904.00 4" select borrow PL-3 $5.75 SY 1.5" top course rock & 2.5" base course PL-4 $16.00 SY SUBTOTAL PARKING LOT SURFACING:51,904.00 (B)(C)(D)(E) LANDSCAPING & VEGETATION No. Street Trees LA-1 Median Landscaping LA-2 Right-of-Way Landscaping LA-3 Wetland Landscaping LA-4 SUBTOTAL LANDSCAPING & VEGETATION: (B)(C)(D)(E) TRAFFIC & LIGHTING No. Signs TR-1 Street Light System ( # of Poles)TR-2 Traffic Signal TR-3 Traffic Signal Modification TR-4 SUBTOTAL TRAFFIC & LIGHTING: (B)(C)(D)(E) WRITE-IN-ITEMS SUBTOTAL WRITE-IN ITEMS: STREET AND SITE IMPROVEMENTS SUBTOTAL:11,283.00 165,794.25 SALES TAX @ 10.3%1,162.15 17,076.81 STREET AND SITE IMPROVEMENTS TOTAL:12,445.15 182,871.06 (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Page 7 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Version: 4/1/2024 Printed 5/13/2025 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost DRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.) Access Road, R/D D-1 $30.00 SY * (CBs include frame and lid) Beehive D-2 $103.00 Each Through-curb Inlet Framework D-3 $460.00 Each CB Type I D-4 $1,725.00 Each 4 6,900.00 CB Type IL D-5 $2,000.00 Each CB Type II, 48" diameter D-6 $3,500.00 Each for additional depth over 4' D-7 $550.00 FT CB Type II, 54" diameter D-8 $4,075.00 Each for additional depth over 4'D-9 $570.00 FT CB Type II, 60" diameter D-10 $4,225.00 Each for additional depth over 4'D-11 $690.00 FT CB Type II, 72" diameter D-12 $6,900.00 Each for additional depth over 4'D-13 $975.00 FT CB Type II, 96" diameter D-14 $16,000.00 Each for additional depth over 4'D-15 $1,050.00 FT Trash Rack, 12"D-16 $400.00 Each Trash Rack, 15"D-17 $470.00 Each Trash Rack, 18"D-18 $550.00 Each Trash Rack, 21"D-19 $630.00 Each Cleanout, PVC, 4"D-20 $170.00 Each Cleanout, PVC, 6"D-21 $195.00 Each Cleanout, PVC, 8"D-22 $230.00 Each Culvert, PVC, 4" D-23 $11.50 LF Culvert, PVC, 6" D-24 $15.00 LF Culvert, PVC, 8" D-25 $17.00 LF 182 3,094.00 Culvert, PVC, 12" D-26 $26.00 LF Culvert, PVC, 15" D-27 $40.00 LF Culvert, PVC, 18" D-28 $47.00 LF Culvert, PVC, 24"D-29 $65.00 LF Culvert, PVC, 30" D-30 $90.00 LF Culvert, PVC, 36" D-31 $150.00 LF Culvert, CMP, 8"D-32 $22.00 LF Culvert, CMP, 12"D-33 $33.00 LF SUBTOTAL THIS PAGE:9,994.00 (B)(C)(D)(E) Page 8 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 5/13/2025 DRAINAGE (Continued) Culvert, CMP, 15"D-34 $40.00 LF Culvert, CMP, 18"D-35 $47.00 LF Culvert, CMP, 24"D-36 $64.00 LF Culvert, CMP, 30"D-37 $90.00 LF Culvert, CMP, 36"D-38 $150.00 LF Culvert, CMP, 48"D-39 $218.00 LF Culvert, CMP, 60"D-40 $310.00 LF Culvert, CMP, 72"D-41 $400.00 LF Culvert, Concrete, 8"D-42 $48.00 LF Culvert, Concrete, 12"D-43 $55.00 LF Culvert, Concrete, 15"D-44 $89.00 LF Culvert, Concrete, 18"D-45 $100.00 LF Culvert, Concrete, 24"D-46 $120.00 LF Culvert, Concrete, 30"D-47 $145.00 LF Culvert, Concrete, 36"D-48 $175.00 LF Culvert, Concrete, 42"D-49 $200.00 LF Culvert, Concrete, 48"D-50 $235.00 LF Culvert, CPE Triple Wall, 6" D-51 $16.00 LF Culvert, CPE Triple Wall, 8" D-52 $18.00 LF Culvert, CPE Triple Wall, 12" D-53 $27.00 LF Culvert, CPE Triple Wall, 15" D-54 $40.00 LF Culvert, CPE Triple Wall, 18" D-55 $47.00 LF Culvert, CPE Triple Wall, 24"D-56 $64.00 LF Culvert, CPE Triple Wall, 30" D-57 $90.00 LF Culvert, CPE Triple Wall, 36" D-58 $149.00 LF Culvert, LCPE, 6"D-59 $69.00 LF Culvert, LCPE, 8"D-60 $83.00 LF Culvert, LCPE, 12"D-61 $96.00 LF Culvert, LCPE, 15"D-62 $110.00 LF Culvert, LCPE, 18"D-63 $124.00 LF Culvert, LCPE, 24"D-64 $138.00 LF Culvert, LCPE, 30"D-65 $151.00 LF Culvert, LCPE, 36"D-66 $165.00 LF Culvert, LCPE, 48"D-67 $179.00 LF Culvert, LCPE, 54"D-68 $193.00 LF SUBTOTAL THIS PAGE: (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Page 9 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 5/13/2025 DRAINAGE (Continued) Culvert, LCPE, 60"D-69 $206.00 LF Culvert, LCPE, 72"D-70 $220.00 LF Culvert, HDPE, 6"D-71 $48.00 LF Culvert, HDPE, 8"D-72 $60.00 LF Culvert, HDPE, 12"D-73 $85.00 LF Culvert, HDPE, 15"D-74 $122.00 LF Culvert, HDPE, 18"D-75 $158.00 LF Culvert, HDPE, 24"D-76 $254.00 LF Culvert, HDPE, 30"D-77 $317.00 LF Culvert, HDPE, 36"D-78 $380.00 LF Culvert, HDPE, 48"D-79 $443.00 LF Culvert, HDPE, 54"D-80 $506.00 LF Culvert, HDPE, 60"D-81 $570.00 LF Culvert, HDPE, 72"D-82 $632.00 LF Pipe, Polypropylene, 6"D-83 $96.00 LF Pipe, Polypropylene, 8"D-84 $100.00 LF Pipe, Polypropylene, 12"D-85 $100.00 LF Pipe, Polypropylene, 15"D-86 $103.00 LF Pipe, Polypropylene, 18"D-87 $106.00 LF Pipe, Polypropylene, 24"D-88 $119.00 LF Pipe, Polypropylene, 30"D-89 $136.00 LF Pipe, Polypropylene, 36"D-90 $185.00 LF Pipe, Polypropylene, 48"D-91 $260.00 LF Pipe, Polypropylene, 54"D-92 $381.00 LF Pipe, Polypropylene, 60"D-93 $504.00 LF Pipe, Polypropylene, 72"D-94 $625.00 LF Culvert, DI, 6"D-95 $70.00 LF Culvert, DI, 8"D-96 $101.00 LF Culvert, DI, 12"D-97 $121.00 LF Culvert, DI, 15"D-98 $148.00 LF Culvert, DI, 18"D-99 $175.00 LF Culvert, DI, 24"D-100 $200.00 LF Culvert, DI, 30"D-101 $227.00 LF Culvert, DI, 36"D-102 $252.00 LF Culvert, DI, 48"D-103 $279.00 LF Culvert, DI, 54"D-104 $305.00 LF Culvert, DI, 60"D-105 $331.00 LF Culvert, DI, 72"D-106 $357.00 LF SUBTOTAL THIS PAGE: SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Page 10 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 5/13/2025 (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Page 11 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 5/13/2025 Specialty Drainage Items Ditching SD-1 $10.90 CY Flow Dispersal Trench (1,436 base+)SD-3 $32.00 LF French Drain (3' depth)SD-4 $30.00 LF Geotextile, laid in trench, polypropylene SD-5 $3.40 SY Mid-tank Access Riser, 48" dia, 6' deep SD-6 $2,300.00 Each Pond Overflow Spillway SD-7 $18.25 SY Restrictor/Oil Separator, 12"SD-8 $1,320.00 Each Restrictor/Oil Separator, 15"SD-9 $1,550.00 Each Restrictor/Oil Separator, 18"SD-10 $1,950.00 Each Riprap, placed SD-11 $48.20 CY Tank End Reducer (36" diameter)SD-12 $1,375.00 Each Infiltration pond testing SD-13 $143.00 HR Permeable Pavement SD-14 Permeable Concrete Sidewalk SD-15 Culvert, Box __ ft x __ ft SD-16 SUBTOTAL SPECIALTY DRAINAGE ITEMS: (B)(C)(D)(E) STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch) Detention Pond SF-1 Each Detention Tank SF-2 Each Detention Vault SF-3 Each Infiltration Pond SF-4 Each Infiltration Tank SF-5 Each Infiltration Vault SF-6 Each Infiltration Trenches SF-7 Each Basic Biofiltration Swale SF-8 Each Wet Biofiltration Swale SF-9 Each Wetpond SF-10 Each Wetvault SF-11 Each Sand Filter SF-12 Each Sand Filter Vault SF-13 Each Linear Sand Filter SF-14 Each Proprietary Facility SF-15 Each Bioretention Facility SF-16 Each SUBTOTAL STORMWATER FACILITIES: (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Page 12 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 5/13/2025 WRITE-IN-ITEMS (INCLUDE ON-SITE BMPs) Filterra Vault, 4x4 WI-1 $22,500.00 Each 1 22,500.00 Contech CDS Solids Separator WI-2 $12,500.00 Each 1 12,500.00 WI-3 WI-4 WI-5 WI-6 WI-7 WI-8 WI-9 WI-10 WI-11 WI-12 WI-13 WI-14 WI-15 SUBTOTAL WRITE-IN ITEMS:35,000.00 DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:44,994.00 SALES TAX @ 10.3%4,634.38 DRAINAGE AND STORMWATER FACILITIES TOTAL:49,628.38 (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Page 13 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 5/13/2025 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR WATER CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Connection to Existing Watermain W-1 $3,400.00 Each Ductile Iron Watermain, CL 52, 4 Inch Diameter W-2 $58.00 LF Ductile Iron Watermain, CL 52, 6 Inch Diameter W-3 $65.00 LF Ductile Iron Watermain, CL 52, 8 Inch Diameter W-4 $75.00 LF Ductile Iron Watermain, CL 52, 10 Inch Diameter W-5 $80.00 LF Ductile Iron Watermain, CL 52, 12 Inch Diameter W-6 $145.00 LF Gate Valve, 4 inch Diameter W-7 $1,225.00 Each Gate Valve, 6 inch Diameter W-8 $1,350.00 Each Gate Valve, 8 Inch Diameter W-9 $1,550.00 Each Gate Valve, 10 Inch Diameter W-10 $2,100.00 Each Gate Valve, 12 Inch Diameter W-11 $2,500.00 Each Fire Hydrant Assembly W-12 $5,000.00 Each Permanent Blow-Off Assembly W-13 $1,950.00 Each Air-Vac Assembly, 2-Inch Diameter W-14 $3,050.00 Each Air-Vac Assembly, 1-Inch Diameter W-15 $1,725.00 Each Compound Meter Assembly 3-inch Diameter W-16 $9,200.00 Each Compound Meter Assembly 4-inch Diameter W-17 $10,500.00 Each Compound Meter Assembly 6-inch Diameter W-18 $11,500.00 Each Pressure Reducing Valve Station 8-inch to 10-inch W-19 $23,000.00 Each WATER SUBTOTAL: SALES TAX @ 10.3% WATER TOTAL: (B)(C)(D)(E) Page 14 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.d WATER Version: 4/1/2024 Printed 5/13/2025 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR SANITARY SEWER CED Permit #:C25001104 Existing Future Public Private Quantity Remaining (Bond Reduction)Right-of-Way Improvements Improvements (B)(C)(D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Clean Outs SS-1 $1,150.00 Each Grease Interceptor, 500 gallon SS-2 $9,200.00 Each Grease Interceptor, 1000 gallon SS-3 $11,500.00 Each Grease Interceptor, 1500 gallon SS-4 $17,200.00 Each Side Sewer Pipe, PVC. 4 Inch Diameter SS-5 $92.00 LF Side Sewer Pipe, PVC. 6 Inch Diameter SS-6 $110.00 LF Sewer Pipe, PVC, 8 inch Diameter SS-7 $120.00 LF Sewer Pipe, PVC, 12 Inch Diameter SS-8 $144.00 LF Sewer Pipe, DI, 8 inch Diameter SS-9 $130.00 LF Sewer Pipe, DI, 12 Inch Diameter SS-10 $150.00 LF Manhole, 48 Inch Diameter SS-11 $6,900.00 Each Manhole, 54 Inch Diameter SS-13 $6,800.00 Each Manhole, 60 Inch Diameter SS-15 $7,600.00 Each Manhole, 72 Inch Diameter SS-17 $10,600.00 Each Manhole, 96 Inch Diameter SS-19 $16,000.00 Each Pipe, C-900, 12 Inch Diameter SS-21 $205.00 LF Outside Drop SS-24 $1,700.00 LS Inside Drop SS-25 $1,150.00 LS Sewer Pipe, PVC, ____ Inch Diameter SS-26 Lift Station (Entire System)SS-27 LS SANITARY SEWER SUBTOTAL: SALES TAX @ 10.3% SANITARY SEWER TOTAL: (B)(C)(D)(E) Page 15 of 16 Ref 8-H Bond Quantity Worksheet SECTION II.e SANITARY SEWER Version: 4/1/2024 Printed 5/13/2025 SITE IMPROVEMENT BOND QUANTITY WORKSHEET BOND CALCULATIONS 1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200 Date:5/21/2024 Prepared by:Project Information Name:Alan Jacobson Project Name: RSD Transportation Expansion PE Registration No:43667 CED Plan # (LUA):LUA24-000376 Firm Name:Jacobson Consulting Engineers CED Permit # (C):C25001104 Firm Address:255 S King St, Suite 800, Seattle, WA 98104 Site Address:420 Park Ave N, Renton, WA 98057 Phone No.206.426.2600 Parcel #(s):7224000676, 7224000675, 7564600105 Email Address:alan@jacobsonengineers.com Project Phase: FOR APPROVAL CONSTRUCTION BOND AMOUNT */** (prior to permit issuance) MAINTENANCE BOND */** (after final acceptance of construction) Site Restoration/Erosion Sediment Control Subtotal (a)$21,702.74 Existing Right-of-Way Improvements Subtotal (b)$12,445.15 (b)$12,445.15 Future Public Improvements Subtotal (c)$- Stormwater & Drainage Facilities (Public & Private) Subtotal (d)$49,628.38 (d)$49,628.38 Bond Reduction: Existing Right-of-Way Improvements (Quantity Remaining)2 (e)$- Bond Reduction: Stormwater & Drainage Facilities (Quantity Remaining)2 (f)$- Site Restoration P (a) x 100%$21,702.74 Existing Right-of-Way and Storm Drainage Improvements R ((b x 150%) + (d x 100%))$68,296.11 Maintenance Bond EST1 ((b) + (c) + (d)) x 20%$12,414.71 Bond Reduction2 S (e) x 150% + (f) x 100%$- Construction Permit Bond Amount 3 T (P +R - S) $89,998.84 Minimum Bond Amount is $10,000.00 1 Estimate Only - May involve multiple and variable components, which will be established on an individual basis by Development Engineering. 2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% will cover all remaining items to be constructed. 3 Required Bond Amounts are subject to review and modification by Development Engineering. * Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton. ** Note: All prices include labor, equipment, materials, overhead, profit, and taxes. Page 16 of 16 Ref 8-H Bond Quantity Worksheet SECTION III. BOND WORKSHEET Version: 4/1/2024 Printed 5/13/2025 RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 22 APPENDIX B STORMWATER CALCULATIONS ————————————————————————————————— MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.64 Program License Number: 201910001 Project Simulation Performed on: 04/14/2025 9:26 AM Report Generation Date: 04/14/2025 10:01 AM ————————————————————————————————— Input File Name: RSDTE_100YR.fld Project Name: RSD Transportation Expansion Analysis Title: 100-yr storm comparison Ex vs Dev Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Full Period of Record Available used for Routing Climatic Region Number: 14 Precipitation Station : 96003605 Puget East 36 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961036 Puget East 36 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : Ecology Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.488 0.488 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.488 0.488 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Predeveloped ---------- -------Area (Acres) -------- C, Lawn, Flat 0.210 PARKING/FLAT 0.278 FLOW CONTROL EXCEPTION CALCULATIONS ---------------------------------------------- Subbasin Total 0.488 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Post Developed ---------- -------Area (Acres) -------- C, Lawn, Flat 0.120 PARKING/FLAT 0.368 ---------------------------------------------- Subbasin Total 0.488 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: Outflow Link Type: Copy Downstream Link: None **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 1 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Predeveloped 24.194 _____________________________________ Total: 24.194 FLOW CONTROL EXCEPTION CALCULATIONS Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Post Developed 13.825 Link: Outflow 0.000 _____________________________________ Total: 13.825 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.153 ac-ft/year, Post Developed: 0.088 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ********** Link: Outflow ********** 2-Year Discharge Rate : 0.148 cfs 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91% Exceedance): 0.05 cfs Off-line Design Discharge Rate (91% Exceedance): 0.03 cfs Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 163.72 Inflow Volume Including PPT-Evap (ac-ft): 163.72 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 163.72 Secondary Outflow To Downstream System (ac-ft): 0.00 Volume Lost to ET (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered+ET)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Subbasin: Predeveloped Scenario Postdeveloped Compliance Link: Outflow *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- FLOW CONTROL EXCEPTION CALCULATIONS 2-Year 0.119 2-Year 0.148 5-Year 0.159 5-Year 0.193 10-Year 0.186 10-Year 0.233 25-Year 0.248 25-Year 0.293 50-Year 0.334 50-Year 0.380 100-Year 0.401 100-Year 0.466 200-Year 0.423 200-Year 0.501 500-Year 0.452 500-Year 0.547 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals FLOW CONTROL EXCEPTION CALCULATIONS FLOW INCREASE 0.065 CFS 0.065 CFS < 0.15 CFS ————————————————————————————————— MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.64 Program License Number: 201910001 Project Simulation Performed on: 04/14/2025 9:17 AM Report Generation Date: 04/14/2025 9:17 AM ————————————————————————————————— Input File Name: RSDTE_WQ.fld Project Name: RSD Transportation Expansion Analysis Title: Water Quality Sizing Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Full Period of Record Available used for Routing Climatic Region Number: 14 Precipitation Station : 96003605 Puget East 36 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961036 Puget East 36 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : Ecology Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.385 0.385 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.385 0.385 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Predeveloped ---------- -------Area (Acres) -------- C, Lawn, Flat 0.385 ---------------------------------------------- WATER QUALITY SIZING Subbasin Total 0.385 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Post Developed ---------- -------Area (Acres) -------- C, Lawn, Flat 0.033 PARKING/FLAT 0.352 ---------------------------------------------- Subbasin Total 0.385 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: Outflow Link Type: Copy Downstream Link: None **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 1 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Predeveloped 44.355 _____________________________________ Total: 44.355 Total Post Developed Recharge During Simulation WATER QUALITY SIZING Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Post Developed 3.802 Link: Outflow 0.000 _____________________________________ Total: 3.802 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.281 ac-ft/year, Post Developed: 0.024 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ********** Link: Outflow ********** 2-Year Discharge Rate : 0.135 cfs 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91% Exceedance): 0.05 cfs Off-line Design Discharge Rate (91% Exceedance): 0.03 cfs Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 143.72 Inflow Volume Including PPT-Evap (ac-ft): 143.72 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 143.72 Secondary Outflow To Downstream System (ac-ft): 0.00 Volume Lost to ET (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered+ET)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Subbasin: Predeveloped Scenario Postdeveloped Compliance Link: Outflow *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 2.409E-02 2-Year 0.135 WATER QUALITY SIZING WATER QUALITY DESIGN FLOW RATE 5-Year 4.526E-02 5-Year 0.173 10-Year 6.934E-02 10-Year 0.217 25-Year 0.100 25-Year 0.261 50-Year 0.160 50-Year 0.331 100-Year 0.162 100-Year 0.412 200-Year 0.170 200-Year 0.448 500-Year 0.180 500-Year 0.496 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals WATER QUALITY SIZING 1 July 2024 GENERAL USE LEVEL DESIGNATION FOR BASIC (TSS), METALS, PHOSPHORUS & OIL TREATMENT For CONTECH Engineered Solutions Filterra® Ecology’s Decision: Based on the Contech Engineered Solution’s (Contech) submissions for the Filterra® system, Ecology hereby issues the following use level designation: 1. A General Use Level Designation for Basic, Metals, Phosphorus, and Oil Treatment for the Filterra system constructed with a minimum media thickness of 21 inches (1.75 feet), at the following water quality design hydraulic loading rates: Treatment Infiltration Rate (in/hr) for use in Sizing Basic 324 Phosphorus 324 Oils 50 Metals 324 2. The Filterra is not appropriate for oil spill-control purposes. 3. Ecology approves Filterra systems for treatment at the hydraulic loading rates listed above, and sized based on the water quality design flow rate for an off-line system. Calculate the water quality design flow rates using the following procedures: • Western Washington: for treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using the latest version of the Western Washington Hydrology Model or other Ecology-approved continuous runoff model and as described in section III-2.6 of the 2024 Stormwater Management Manual for Western Washington (SWMMWW) • Eastern Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using one of the three methods described in Chapter 6.5.1 of the 2024 Stormwater Management Manual for Eastern Washington (SWMMEW) or local manual. • Entire State: For treatment installed downstream of detention, the water quality design flow rate is the full 2-year release rate of the detention facility. 4. This General Use Level Designation has no expiration date, but Ecology may revoke or amend the designation, and is subject to the conditions specified below. 2 Ecology’s Conditions of Use: Filterra systems shall comply with these conditions shall comply with the following conditions: 1. Design, assemble, install, operate, and maintain the Filterra systems in accordance with applicable Contech Filterra manuals and this Ecology Decision. 2. The minimum size filter surface-area for use in Washington is determined by using the design water quality flow rate (as determined in this Ecology Decision, Item 3, above) and the Infiltration Rate from the table above (use the lowest applicable Infiltration Rate depending on the level of treatment required). Calculate the required area by dividing the water quality design flow rate (cu-ft/sec) by the Infiltration Rate (converted to ft/sec) to obtain required surface area (sq-ft) of the Filterra unit. 3. Each site plan must undergo Contech Filterra review before Ecology can approve the unit for site installation. This will ensure that design parameters including site grading and slope are appropriate for use of a Filterra unit. 4. Filterra media shall conform to the specifications submitted to and approved by Ecology and shall be sourced from Contech with no substitutions. 5. Contech tested the Filterra with and without plants. The GULD applies to the Filterra whether plants are included in the final product or not. 6. Maintenance: The required maintenance interval for stormwater treatment devices is often dependent upon the degree of pollutant loading from a particular drainage basin. Therefore, Ecology does not endorse or recommend a “one size fits all” maintenance cycle for a particular model/size of manufactured treatment device. • Contech designs Filterra systems for a target maintenance interval of 6 months in the Pacific Northwest. Maintenance includes removing and replacing the mulch layer above the media along with accumulated sediment, trash, and captured organic materials therein, evaluating plant health, and pruning the plant if deemed necessary. • Owners/operators must inspect the Filterra system for a minimum of twelve months from the start of post-construction operation to determine site-specific inspection/maintenance schedules and requirements. Owners/operators must conduct inspections monthly during the wet season, and every other month during the dry season (According to the SWMMWW, the wet season in western Washington is October 1 to April 30. According to the SWMMEW, the wet season in eastern Washington is October 1 to June 30). After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections. 7. Conduct maintenance following manufacturer’s guidelines. Follow maintenance procedures given in the most recent version of the Filterra Operation and Maintenance Manual. 8. Filterra systems come in standard sizes. 9. Install the Filterra in such a manner that flows exceeding the maximum operating rate are conveyed around the mulch and media and will not resuspend captured sediment. 3 10. Discharges from the Filterra units shall not cause or contribute to water quality standards violations in receiving waters. Approved Alternate Configurations Filterra Internal Bypass - Pipe (FTIB-P) 1. The Filterra® Internal Bypass – Pipe allows for piped-in flow from area drains, grated inlets, trench drains, and/or roof drains. Design capture flows and peak flows enter the structure through an internal slotted pipe. Filterra® inverted the slotted pipe to allow design flows to drop through to a series of splash plates that then disperse the design flows over the top surface of the Filterra® planter area. Higher flows continue to bypass the slotted pipe and convey out the structure. 2. To select a FTIB-P unit, the designer must determine the size of the standard unit using the sizing guidance described above. Filterra Internal Bypass – Curb (FTIB-C) 1. The Filterra® Internal Bypass –Curb model (FTIB-C) incorporates a curb inlet, biofiltration treatment chamber, and internal high flow bypass in one single structure. Filterra® designed the FTIB-C model for use in a “Sag” or “Sump” condition and will accept flows from both directions along a gutter line. An internal flume tray weir component directs treatment flows entering the unit through the curb inlet to the biofiltration treatment chamber. Flows in excess of the water quality treatment flow rise above the flume tray weir and discharge through a standpipe orifice; providing bypass of untreated peak flows. Americast manufactures the FTIB-C model in a variety of sizes and configurations and you may use the unit on a continuous grade when a single structure providing both treatment and high flow bypass is preferred. The FTIB-C model can also incorporate a separate junction box chamber to allow larger diameter discharge pipe connections to the structure. 2. To select a FTIB-C unit, the designer must determine the size of the standard unit using the sizing guidance described above. Filterra® Shallow 1. The Filterra Shallow provides additional flexibility for design engineers and designers in situations where various elevation constraints prevent application of a standard Filterra configuration. Engineers can design this system up to six inches shallower than any of the previous Filterra unit configurations noted above. 2. Ecology requires that the Filterra Shallow provide a media contact time equivalent to that of the standard unit. This means that with a smaller depth of media, the surface area must increase. 3. To select a Filterra Shallow System unit, the designer must first identify the size of the standard unit using the modeling guidance described above. 4 4. Once the size of the standard Filterra unit is established using the sizing technique described above, use information from the following table to select the appropriate size Filterra Shallow System unit. Shallow Unit Basic, Metals, Phosphorus, and Oil Treatment Sizing Standard Depth Equivalent Shallow Depth 4x4 4x6 or 6x4 4x6 or 6x4 6x6 4x8 or 8x4 6x8 or 8x6 6x6 6x10 or 10x6 6x8 or 8x6 6x12 or 12x6 6x10 or 10x6 13x7 Notes: 1. Shallow Depth Boxes are less than the standard depth of 3.5 feet but no less than 3.0 feet deep (TC to INV). Applicant: Contech Engineered Solutions, LLC. Applicant’s Address: 12901 SE 97th Ave, Suite 400 Clackamas, OR 97015 Application Documents: State of Washington Department of Ecology Application for Conditional Use Designation, Americast (September 2006) Quality Assurance Project Plan Filterra® Bioretention Filtration System Performance Monitoring, Americast (April 2008) Quality Assurance Project Plan Addendum Filterra® Bioretention Filtration System Performance Monitoring, Americast (June 2008) Draft Technical Evaluation Report Filterra® Bioretention Filtration System Performance Monitoring, Americast (August 2009) Final Technical Evaluation Report Filterra® Bioretention Filtration System Performance Monitoring, Americast (December 2009) Technical Evaluation Report Appendices Filterra® Bioretention Filtration System Performance Monitoring, Americast, (August 2009) Memorandum to Department of Ecology Dated October 9, 2009 from Americast, Inc. and Herrera Environmental Consultants Quality Assurance Project Plan Filterra® Bioretention System Phosphorus treatment and Supplemental Basic and Enhanced Treatment Performance Monitoring, Americast (November 2011) Filterra® letter August 24, 2012 regarding sizing for the Filterra® Shallow System. University of Virginia Engineering Department Memo by Joanna Crowe Curran, Ph. D dated March 16, 2013 concerning capacity analysis of Filterra® internal weir inlet tray. Terraphase Engineering letter to Jodi Mills, P.E. dated April 2, 2013 regarding Terraflume Hydraulic Test, Filterra® Bioretention System and attachments. 5 Technical Evaluation Report, Filterra® System Phosphorus Treatment and Supplemental Basic Treatment Performance Monitoring. March 27th, 2014. State of Washington Department of Ecology Application for Conditional Use Level Designation, Contech Engineered Solutions (May 2015) Quality Assurance Project Plan Filterra® Bioretention System, Contech Engineered Solutions (May 2015) Filterra Bioretention System Armco Avenue General Use Level Designation Technical Evaluation Report, Contech Engineered Solutions (August 2019) NJCAT Technology Verification, Filterra Bioretention System, Contech Engineered Solutions (October 2020) Basic Treatment PULD Application for Contech Enhanced Filtration System, Contech Engineered Solutions (November 2020) Contech Enhanced Filtration System, Application for Certification, Contech Engineered Solutions (November 2020) Quality Assurance Project Plan Contech Enhanced Filtration System (CEFS) Technology Performance Evaluation, Prepared by Contech Engineered Solutions (September 2021) Addendum to the Quality Assurance Project Plan – Contech Enhanced Filtration System, Prepared by Contech Engineered Solutions (August 2021) Contech Enhanced Filtration System Armco Avenue General Use Level Designation Technical Evaluation Report, Prepared by Contech Engineered Solutions (May 2024) Applicant’s Use Level Request: General Level Use Designation as a Basic, Metals, Phosphorus, and Oil Treatment device in accordance with Ecology’s Stormwater Management Manual for Western Washington. Applicant’s Performance Claims: Based on field testing, the Filterra is able to meet TAPE performance goals for TSS, dissolved metals, and total phosphorus at an infiltration rate of 324 in/hr, and is able to meet TAPE performance goals for oil at an infiltration rate of 50 in/hr. Ecology’s Recommendations: Ecology finds that Contech has shown Ecology, through laboratory and field testing, that the Filterra is capable of attaining Ecology’s Basic, Metals, Phosphorus, and Oil treatment goals. Findings of Fact: Field Testing 2021-2023 1. Contech completed field testing of a 4 ft. x 3 ft. unvegetated Filterra unit (referred to as a Contech Enhanced Filtration System [CEFS] during testing) in Hillsboro, Oregon between June 2021 and April 2023. Throughout the monitoring period a total of 35 individual storm events were sampled. 6 2. The CEFS utilized the same media formulation and dimensional layout as a Filterra unit but did not include plants. 3. Contech evaluated the system for basic, metals, and phosphorus treatment against a hydraulic loading rate of 3.36 gpm/sf (324 in/hr). 4. Herrera Environmental Consultants conducted a third-party review of the data and TER to ensure the monitoring complied with the QAPP and met the requirements of the TAPE guidance document. 5. Particle size distribution analysis showed 39% of the influent particulate finer than 62.5 microns (µm) for the samples collected during the 35-event period. The similarity of influent and effluent PSD prompted a review of the influence of laboratory procedure on the results. Upon recommendation of Herrera Environmental Consultants, a secondary laboratory was consulted which provided TAPE PSD analysis on multiple previous TAPE testing campaigns, including the Ship Canal test site. Six supplemental events were sampled for PSD between 1/4/24 and 2/16/24. Results from the second laboratory showed 77% of influent particulate finer than 62.5 microns (µm). 6. Of the 35 sampled events, 21 met requirements for TSS analysis. Influent TSS concentrations ranged from 20 mg/L to 269 mg/L, with a mean concentration of 57 mg/L. For samples with an influent concentration between 20 and 100 mg/L (n=17) the upper 95 percent confidence limit of the mean TSS effluent concentration was 17.5 mg/L. For samples with an influent concentration greater than 100 mg/L (n=4) the lower 95 percent confidence limit of the mean TSS reduction was 83.5%. Influent concentrations greater than 200 mg/L (the upper end of the TAPE influent concentration range) were capped at 200 mg/L before calculating the pollutant removal efficiency. 7. Of the 35 sampled events, 27 met requirements for dissolved copper analysis. Influent dissolved copper concentrations ranged from 7.3 µg/L to 46.0 µg/L, with a mean concentration of 18.1 µg/L. The lower 95 percent confidence limit of the mean dissolved copper reduction was 39.8%. Influent concentrations greater than 20 µg/L (the upper end of the TAPE influent concentration range) were capped at 20 µg/L before calculating the pollutant removal efficiency. 8. Of the 35 sampled events, 28 met requirements for dissolved zinc analysis. Influent dissolved zinc concentrations ranged from 33.9 µg/L to 178.0 µg/L, with a mean concentration of 74.4 µg/L. The lower 95 percent confidence limit of the mean dissolved zinc reduction was 62.4%. 9. Of the 35 sampled events, 16 met requirements for the total phosphorus analysis. Influent total phosphorus concentrations ranged from 0.101 mg/L to 0.571 mg/L with a mean concentration of 0.298 mg/L. The lower 95 percent confidence limit of the mean total phosphorus reduction was 64.4%. 10. Maintenance was conducted 3 times during the 23-month study period with frequency ranging from every 4 to 9 months. Maintenance performed consisted of replacing the mulch layer. Field Testing 2015-2019 1. Contech completed field testing of a 4 ft. x 4 ft. Filterra unit at one site in Hillsboro, Oregon from September 2015 to July 2019. Throughout the monitoring period a total of 24 individual storm events were sampled, of which 23 qualified for TAPE sampling criteria. 7 2. Contech encountered several unanticipated events and challenges that prevented them from collecting continuous flow and rainfall data. An analysis of the flow data from the sampled events, including both the qualifying and non-qualifying events, demonstrated the system treated over 99% of the influent flows. Peak flows during these events ranged from 25% to 250% of the design flow rate of 29 gallons per minute. 3. Of the 23 TAPE qualified sample events, 13 met requirements for TSS analysis. Influent concentrations ranged from 20.8 mg/L to 83 mg/L, with a mean concentration of 46.3 mg/L. The UCL95 mean effluent concentration was 15.9 mg/L, meeting the 20 mg/L performance goal for Basic Treatment. 4. All 23 TAPE qualified sample events met requirements for dissolved zinc analysis. Influent concentrations range from 0.0384 mg/L to 0.2680 mg/L, with a mean concentration of 0.0807 mg/L. The LCL 95 mean percent removal was 62.9%, meeting the 60% performance goal for Metals Treatment. 5. Thirteen of the 23 TAPE qualified sample events met requirements for dissolved copper analysis. Influent concentrations ranged from 0.00543 mg/L to 0.01660 mg/L, with a mean concentration of 0.0103 mg/L. The LCL 95 mean percent removal was 41.2%, meeting the 30% performance goal for Metals Treatment. 6. Total zinc concentrations were analyzed for all 24 sample events. Influent EMCs for total zinc ranged from 0.048 mg/L to 5.290 mg/L with a median of 0.162 mg/L. Corresponding effluent EMCs for total zinc ranged from 0.015 mg/L to 0.067 mg/L with a median of 0.029 mg/L. Total event loadings for the study for total zinc were 316.85 g at the influent and 12.92 g at the effluent sampling location, resulting in a summation of loads removal efficiency of 95.9%. 7. Total copper concentrations were analyzed for all 24 sample events. Influent EMCs for total copper ranged from 0.003 mg/L to 35.600 mg/L with a median value of 0.043 mg/L. Corresponding effluent EMCs for total copper ranged from 0.002 mg/L to 0.015 mg/L with a median of 0.004 mg/L. Total event loadings for total copper for the study were 1,810.06 g at the influent and 1.90 g at the effluent sampling location, resulting in a summation of loads removal efficiency of 99.9%. Field Testing 2013 1. Filterra completed field-testing of a 6.5 ft x 4 ft. unit at one site in Bellingham, Washington. Continuous flow and rainfall data collected from January 1, 2013 through July 23, 2013 indicated that 59 storm events occurred. Water quality data was obtained from 22 storm events. Not all the sampled storms produced information that met TAPE criteria for storm and/or water quality data. 2. The system treated 98.9% of the total 8-month runoff volume during the testing period. Consequently, the system achieved the goal of treating 91% of the volume from the site. Stormwater runoff bypassed Filterra treatment during four of the 59 storm events. 3. Of the 22 sampled events, 18 qualified for TSS analysis (influent TSS concentrations ranged from 25 to 138 mg/L). The data were segregated into sample pairs with influent concentration greater than and less than 100 mg/L. The UCL95 mean effluent 8 concentration for the data with influent less than 100 mg/L was 5.2 mg/L, below the 20- mg/L threshold. Although the TAPE guidelines do not require an evaluation of TSS removal efficiency for influent concentrations below 100 mg/L, the mean TSS removal for these samples was 90.1%. Average removal of influent TSS concentrations greater than 100 mg/L (three events) was 85%. In addition, the system consistently exhibited TSS removal greater than 80% at flow rates equivalent to a 100 in/hr infiltration rate and was observed at 150 in/hr. 4. Ten of the 22 sampled events qualified for TP analysis. Americast augmented the dataset using two sample pairs from previous monitoring at the site. Influent TP concentrations ranged from 0.11 to 0.52 mg/L. The mean TP removal for these twelve events was 72.6%. The LCL95 mean percent removal was 66.0, well above the TAPE requirement of 50%. Treatment above 50% was evident at 100 in/hr infiltration rate and as high as 150 in/hr. Consequently, the Filterra test system met the TAPE Phosphorus Treatment goal at 100 in/hr. Influent ortho-P concentrations ranged from 0.005 to 0.012 mg/L; effluent ortho-P concentrations ranged from 0.005 to 0.013 mg/L. The reporting limit/resolution for the ortho-P test method is 0.01 mg/L, therefore the influent and effluent ortho-P concentrations were both at and near non-detect concentrations. Field Testing 2008-2009 1. Filterra completed field-testing at two sites at the Port of Tacoma. Continuous flow and rainfall data collected during the 2008-2009 monitoring period indicated that 89 storm events occurred. The monitoring obtained water quality data from 27 storm events. Not all the sampled storms produced information that met TAPE criteria for storm and/or water quality data. 2. During the testing at the Port of Tacoma, 98.96 to 99.89% of the annual influent runoff volume passed through the POT1 and POT2 test systems respectively. Stormwater runoff bypassed the POT1 test system during nine storm events and bypassed the POT2 test system during one storm event. Bypass volumes ranged from 0.13% to 15.3% of the influent storm volume. Both test systems achieved the 91% water quality treatment-goal over the 1-year monitoring period. 3. Consultants observed infiltration rates as high as 133 in/hr during the various storms. Filterra did not provide any paired data that identified percent removal of TSS, metals, oil, or phosphorus at an instantaneous observed flow rate. 4. The maximum storm average hydraulic loading rate associated with water quality data is <40 in/hr, with the majority of flow rates < 25 in/hr. The average instantaneous hydraulic loading rate ranged from 8.6 to 53 in/hr. 5. The field data showed a removal rate greater than 80% for TSS with an influent concentration greater than 20 mg/L at an average instantaneous hydraulic loading rate up to 53 in/hr (average influent concentration of 28.8 mg/L, average effluent concentration of 4.3 mg/L). 6. The field data showed a removal rate generally greater than 54% for dissolved zinc at an average instantaneous hydraulic loading rate up to 60 in/hr and an average influent concentration of 0.266 mg/L (average effluent concentration of 0.115 mg/L). 9 7. The field data showed a removal rate generally greater than 40% for dissolved copper at an average instantaneous hydraulic loading rate up to 35 in/hr and an average influent concentration of 0.0070 mg/L (average effluent concentration of 0.0036 mg/L). 8. The field data showed an average removal rate of 93% for total petroleum hydrocarbon (TPH) at an average instantaneous hydraulic loading rate up to 53 in/hr and an average influent concentration of 52 mg/L (average effluent concentration of 2.3 mg/L). The data also shows achievement of less than 15 mg/L TPH for grab samples. Filterra provided limited visible sheen data due to access limitations at the outlet monitoring location. 9. The field data showed low percentage removals of total phosphorus at all storm flows at an average influent concentration of 0.189 mg/L (average effluent concentration of 0.171 mg/L). We may relate the relatively poor treatment performance of the Filterra system at this location to influent characteristics for total phosphorus that are unique to the Port of Tacoma site. It appears that the Filterra system will not meet the 50% removal performance goal when the majority of phosphorus in the runoff is expected to be in the dissolved form. Laboratory Testing 1. Contech conducted testing of a 4 ft. x 4 ft. unit in July 2020 at Contech’s laboratory in Ashland, Virginia. The unit included the Filterra® HC media blend without the use of any vegetation that is standard in Filterra installations. • The laboratory testing was performed in accordance with the New Jersey Department of Environmental Protection (NJDEP) Laboratory Protocol to Assess Total Suspended Solids Removal by a Filtration Manufactured Treatment Device. Since Contech did the testing, A. Morton Thomas and Associates, inc. performed independent third-party observation. • The testing evaluated a full-scale 4 ft. x 4 ft. unit at a hydraulic loading rate of 3.12 gpm/sq. ft (300 in/hr). The test sediment used with compliant with the NJDEP particle size distribution requirements, with a d50 particle size of 69 µm. • Contech evaluated TSS removal efficiency over 15 events. The influent concentration ranged from 182 mg/L to 211 mg/L with a mean concentration of 200.7 mg/L and a mean removal efficiency of 86%. • Contech evaluated sediment mass loading capacity over an additional 21 events as a continuation of the removal efficiency testing. During the sediment mass loading capacity evaluation Contech increased the target influent concentration to 400 mg/L. The cumulative removal efficiency over the 36 events was 82% and the cumulative mass captured was 110 kg. 2. Filterra performed laboratory testing on a scaled down version of the Filterra unit. The lab data showed an average removal from 83-91% for TSS with influents ranging from 21 to 320 mg/L, 82-84% for total copper with influents ranging from 0.94 to 2.3 mg/L, and 50-61% for orthophosphate with influents ranging from 2.46 to 14.37 mg/L. • Filterra conducted permeability tests on the soil media. • Lab scale testing using Sil-Co-Sil 106 showed removals ranging from 70.1% to 95.5% with a median removal of 90.7%, for influent concentrations ranging from 8.3 to 260 mg/L. Filterra ran these laboratory tests at an infiltration rate of 50 in/hr. 10 • Supplemental lab testing conducted in September 2009 using Sil-Co-Sil 106 showed an average removal of 90.6%. These laboratory tests were run at infiltration rates ranging from 25 to 150 in/hr for influent concentrations ranging from 41.6 to 252.5 mg/L. Regression analysis results indicate that the Filterra system’s TSS removal performance is independent of influent concentration in the concentration rage evaluated at hydraulic loading rates of up to 150 in/hr. Other Filterra Related Issues to be Addressed by the Company: 1. Conduct hydraulic testing to obtain additional information about the maintenance longevity and requirements. Complete testing by May 30, 2027. Technology Description: https://www.conteches.com/stormwater-management/biofiltration- solutions/filterra/ Contact Information: Applicant: Jeremiah Lehman Contech Engineered Solutions, LLC. 12901 SE 97th Ave, Suite 400 Clackamas, OR 97015 (503) 258-3136 jlehman@conteches.com Applicant’s Website: http://www.conteches.com Ecology web link: http://www.ecy.wa.gov/programs/wq/stormwater/newtech/index.html Ecology: Douglas C. Howie, P.E. Department of Ecology Water Quality Program (360) 870-0983 douglas.howie@ecy.wa.gov Date Revision December 2009 GULD for Basic, Enhanced, and Oil granted, CULD for Phosphorus September 2011 Extended CULD for Phosphorus Treatment September 2012 Revised design storm discussion, added Shallow System. January 2013 Revised format to match Ecology standards, changed Filterra contact information February 2013 Added FTIB-P system March 2013 Added FTIB-C system April 2013 Modified requirements for identifying appropriate size of unit June 2013 Modified description of FTIB-C alternate configuration 11 March 2014 GULD awarded for Phosphorus Treatment. GULD updated for a higher flow-rate for Basic Treatment. June 2014 Revised sizing calculation methods March 2015 Revised Contact Information June 2015 CULD for Basic and Enhanced at 100 in/hr infiltration rate September 2019 GULD for Basic and Enhanced at 175 in/hr infiltration rate February 2020 Revised sizing language to note sizing based on off-line calculations June 2020 Added Phosphorus to Filterra Shallow sizing table January 2024 Revised Dissolved Metals (Enhanced) to Metals July 2024 GULD for Basic, Enhanced, and Phosphorus at 324 in/hr infiltration rate for vegetated and unvegetated Filterra systems. Updated Contech address August 2018 GENERAL USE LEVEL DESIGNATION FOR PRETREATMENT (TSS) For CONTECH Engineered Solutions CDS® System Ecology’s Decision: Based on the CONTECH Engineered Solutions (CONTECH) application submissions for the CDS® System, Ecology hereby issues the following use designations for the CDS storm water treatment system: 1. General Use Level Designation (GULD) for pretreatment use, as defined in Ecology’s 2011 Technical Guidance Manual for Evaluating Emerging Stormwater Treatment Technologies Technology Assessment Protocol – Ecology (TAPE) Table 2, (a) ahead of infiltration treatment, or (b) to protect and extend the maintenance cycle of a basic, enhanced, or phosphorus treatment device (e.g., sand or media filter). This GULD applies to 2,400 micron screen CDS® units sized per the table below. 2. The following table shows flowrates associated with various CDS models: CDS Model Water Quality Flow cfs L/s Pr e c a s t * * In l i n e o r O f f l i n e CDS 2015-4 0.7 19.8 CDS 2015-5 0.7 19.8 CDS 2020-5 1.1 31.2 CDS2025-5 1.6 45.3 CDS3020-6 2 56.6 CDS3030-6 3 85.0 CDS3035-6 3.8 106.2 CDS4030-8 4.5 127.4 CDS4040-8 6 169.9 CDS4045-8 7.5 212.4 CDS5640-10 9 254.9 CDS5653-10 14 396.5 CDS5668-10 19 538.1 CDS5678-10 25 7.08 Of f l i n e On l y CDS3030-V 3 85 Pr e c as t * * CDS4030-7 4.5 127.4 CDS4040-7 6 169.9 CDS4045-7 7.5 212.4 CDS5640-8 9 254.9 CDS5653-8 14 396.5 CDS5668-8 19 538.1 CDS5678-8 25 708 CDS5042 9 254.9 CDS5050 11 311.5 CDS7070 26 736.3 CDS10060 30 849.6 CDS10080 50 1416 CDS100100 64 1812.5 Cast In Place CDS150134-22 148 4191.4 CDS200164-26 270 7646.6 CDS240160-32 300 8496.2 *Specially Designed CDS Units may be approved by Ecology on a on a site-by-site basis. **Contact Contech for updated model numbers if PMIU, PMSU, PSW, PSWC are specified. 3. The water quality design flow rates are calculated using the following procedures: Western Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using the latest version of the Western Washington Hydrology Model or other Ecology- approved continuous runoff model. Eastern Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using one of the three methods described in Chapter 2.2.5 of the Stormwater Management Manual for Eastern Washington (SWMMEW) or local manual. Entire State: For treatment installed downstream of detention, the water quality design flow rate is the full 2-year release rate of the detention facility. 4. The pretreatment GULD has no expiration date; however, Ecology may amend or revoke the designation. 5. All designations are subject to the conditions specified below. 6. Properly designed and operated CDS systems may also have applicability in other situations (example: low-head situations such as bridges or ferry docks), for TSS where, on a case-by-case basis, it is found to be infeasible or impracticable to use any other approved practice. Jurisdictions covered under the Phase I or II municipal stormwater permits should use variance/exception procedures and criteria as required by their NPDES permit. 7. Ecology finds that the CDS, sized according to the table above, could also provide water quality benefits in retrofit situations. Ecology’s Conditions of Use: CDS systems shall comply with these conditions: 1. Design, assemble, install, operate, and maintain CDS Systems in accordance with Contech’s applicable manuals and documents and the Ecology decision and conditions specified herein. Ecology recommends use of the inspection and maintenance schedule included as Attachment 1. 2. Maintenance: The required inspection/maintenance interval for stormwater treatment devices is often dependent upon the efficiency of the device and the degree of pollutant loading from a particular drainage basin. Therefore, Ecology does not endorse or recommend a “one size fits all” maintenance cycle for a particular model/size of manufactured treatment device. Owners/operators must inspect the CDS™ System for a minimum of twelve months from the start of post-construction operation to determine site-specific maintenance schedules and requirements. You must conduct inspections monthly during the wet season, and every other month during the dry season. (According to SWMMWW, the wet season for western Washington is October 1 to April 30. According to SWMMEW, the wet season in eastern Washington is October 1 to June 30). After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections. Conduct inspections by qualified personnel, follow manufacturer’s guidelines, and use methods capable of determining either a decrease in treated effluent flow rate and/or a decrease in pollutant removal ability. 3. Discharges from the CDS System shall not cause or contribute to water quality standards violations in receiving waters. Applicant: Contech Engineered Solutions Applicant’s Address: 11835 NE Glen Widing Drive Portland, OR 97220 Application Documents: Contech Stormwater Solutions Application to: Washington State Department of Ecology Water Quality Program for General Use Level Designation – Pretreatment Applications and Conditional Use Level Designation – Oil Treatment of the Continuous Deflective Separation (CDS™) Technology (June 2007) Strynchuk, Royal, and England, The Use of a CDS Unit for Sediment Control in Brevard County. Walker, Allison, Wong, and Wootton, Removal of Suspended Solids and Associated Pollutants by a CDS Gross Pollutant Trap, Cooperative Research Centre for Catchment Hydrology, Report 99/2, February 1999 Allison, Walker, Chiew, O’Neill, McMahon, From Roads to Rivers Gross Pollutant Removal from Urban Waterways, Cooperative Research Centre for Catchment Hydrology, Report 98/6, May 1998 Applicant’s Use Level Request: General use level designation as a pretreatment device and conditional use level designation as an oil and grease device in accordance with Ecology’s Stormwater Management Manual for Western Washington. Applicant’s Performance Claims: Based on laboratory trials, the CDS™ System will achieve 50% removal of total suspended solids with d50 of 50-μm and 80% removal of total suspended solids with d50 of 125-μm at 100% design flowrate with typical influent concentration of 200-mg/L. Ecology’s Recommendation: Ecology finds that: The CDS™ system, sized per the table above, should provide, at a minimum, equivalent performance to a presettling basin as defined in the most recent Stormwater Management Manual for Western Washington, Volume V, Chapter 6. Findings of Fact: 1. Laboratory testing was completed on a CDS 2020 unit equipped with 2400-m screen using OK-110 sand (d50 of 106-μm) at flowrates ranging from 100 to 125% of the design flowrate (1.1 cfs) with a target influent of 200 mg/L. Laboratory results for the OK-110 sand showed removal rates from about 65% to 99% removal with 80% removal occurring near 70% of the design flowrate. 2. Laboratory testing was completed on a CDS 2020 unit equipped with 2400-m screen using “UF” sediment (d50 of 20 to 30-μm) at flowrates ranging from 100 to 125% of the design flowrate (1.1 cfs) with a target influent of 200 mg/L. Laboratory results for the “UF” sediment showed removal rates from about 42% to 94% removal with 80% removal occurring at 5% of the design flowrate. 3. Laboratory testing was completed on a CDS 2020 unit equipped with 4700-m screen using OK-110 sand (d50 of 106-μm) at flowrates ranging from 100 to 125% of the design flowrate (1.1 cfs) with a target influent of 200 mg/L. Laboratory results for the OK-110 sand showed removal rates from about 45% to 99% removal with an average removal of 83.1%. 4. Laboratory testing was completed on a CDS 2020 unit equipped with 4700-m screen using “UF” sediment (d50 of 20 to 30-μm) at flowrates ranging from 100 to 125% of the design flowrate (1.1 cfs) with a target influent of 200 mg/L. Laboratory results for the “UF” sediment showed removal rates from about 39% to 88% removal with an average removal of 56.1%. 5. Contech completed laboratory testing on a CDS2020 unit using motor oil at flowrates ranging from 25% to 75% of the design flowrate (1.1 cfs) with influents ranging from 7 to 47 mg/L. Laboratory results showed removal rates from 27% to 92% removal. A spill test was also run at 10% of the design flowrate with an influent of 82,000 mg/L with an average percent capture of 94.5% 6. Independent parties in California, Florida, and Australia completed various field studies. Field studies showed the potential for the unit to remove oils and grease and total suspended solids, and capture 100% gross solids greater than the aperture size of the screen under treatment flow rate. 7. CDS Technology has been widely accepted with over 6,200 installations in the United States and Canada. There are over 1,380 installations in Washington and Oregon. Technology Description: Engineers can download a technology description from the company’s website. www.conteches.com Recommended Research and Development: Ecology encourages Contech to pursue continuous improvements to the CDS system. To that end, Ecology makes the following recommendations: 1. Conduct testing to quantify the flowrate at which resuspension occurs. 2. Conduct testing on various sized CDS units to verify the sizing technique is appropriate. 3. Test the system under normal operating conditions, pollutants partially filling the swirl concentrator. Results obtained for “clean” systems may not be representative of typical performance. Contact Information: Applicant Contact: Jeremiah Lehman Contech Engineered Solutions (503) 258-3136 jlehman@conteches.com Applicant website: http://www.conteches.com/ Ecology web link: http://www.ecy.wa.gov/programs/wq/stormwater/newtech/index.html Ecology: Douglas C. Howie. P.E. Department of Ecology Water Quality Program (360) 407-6444 douglas.howie@ecy.wa.gov Revision History Date Revision July 2008 Original use-level-designation document February 2010 Reinstate Contech’s Oil Control PULD August 2012 Revised design storm criteria, revised oil control QAPP, TER, and Expiration dates December 2012 Revised Contech Engineered Solutions Contact Information; Added QAPP for Oil Treatment May 2013 Revised model numbers in Attachment 1 April 2014 Revised Due dates for QAPP and TER and changed Expiration date August 2014 Revised Due dates for QAPP and TER and changed Expiration date July 2016 Updated Oil Control PULD to a CULD based on preliminary field monitoring results November 2016 Revised Contech Contact person August 2018 Removed CULD for Oil from document Attachment 1 CDS Stormwater Treatment Unit Checklist Frequency Drainage System Feature Problem Conditions to Check For Recommended Action Date Inspected* J F M A M J J A S O N D M & S Inlet Chamber Accumulation of trash, debris and sediment Trash blocking inlet throat opening & sediment accumulation exceeds 2 inches Remove trash, debris, and sediments. Inlet throat opening should not be blocked by any materials. A Screen Blockage/Damage Biological growth on the surface of the screen; broken screen or loose screen Powerwash screen to clean the surface and Contact CSS for screen repair (broken or loose) M Separation Chamber Trash and floatable debris accumulation Excessive trash and floatable debris accumulation on the surface in separation chamber Remove trash or other floatable debris in separation chamber to minimum level A Oil Baffle** Damaged Baffles corroding, cracking, warping, and/or showing signs of failure as determined by maintenance/inspection person. Baffles repaired or replaced to design specifications. M & S Oil sorbent** Consumed Change of color in sorbents (fresh sorbents typically appears to be white or light yellow) Remove spent oil sorbent and replace with new sorbent M Sediment Depth in the Sump Sediment accumulation Sediment accumulation exceeds 75-85% sump depth (varies depending on the Model, see attached Table) Sediment in sump should be removed using vactor truck. M Sediment Depth behind the screen Sediment accumulation Sediment accumulation exceeds 2 inches behind the screen Sediment behind the screen should be removed using vactor truck. Frequency Drainage System Feature Problem Conditions to Check For Recommended Action Date Inspected* J F M A M J J A S O N D M Access Cover (MH, Grate, cleanout) Access cover Damaged/ Not working One maintenance person cannot remove lid after applying 80 pounds of lift, corrosion of deformation of cover. Cover repaired to proper working specifications or replaced. A Inlet and Outlet Piping Damaged Piping/Leaking Any part of the pipes are crushed or damaged due to corrosion and/or settlement. Pipe repaired or replaced. A Concrete Structure Concrete structure (MH or diversion vault) has cracks in wall, bottom, and damage to frame and/or top slab. Cracks wider than ½ inch or evidence of soil particles entering the structure through the cracks, or maintenance/inspection personnel determine that the structure is not structurally sound. Structure repaired so that no cracks exist wider than 0.25 inch at the joint of inlet/outlet pipe. A Access Ladder Ladder rungs unsafe Maintenance person judges that ladder is unsafe due to missing rungs, misalignment, rust, or cracks. Ladder must be fixed or secured immediately. Ladder meets design standards and allows maintenance persons safe access. *Note dates when maintenance was performed and type of maintenance performed in notes section below. **May not be present on all units. (M) Monthly from November through April. (A) Once in late summer (preferable September) (S) After any major storm (use 1-inch in 24 hours as a guideline). If you are unsure whether a problem exists, please contact a Professional Engineer. Notes: Maintenance of CDS stormwater treatment unit typically does not require confined space entry. Visual inspections should be performed above ground. If entry is required, it should be performed by qualified personnel. Refer to CDS Unit Operation & Maintenance Guideline for maintenance details. Typically the CDS unit needs to be inspected before and after the rainfall seasons (November to April), after any major storms (>1-inch within 24 hour) and in the event of chemical spills. Contact Contech Engineered Solutions (CSS) (800-548-4667) if there is any damage to the internal components of CDS Unit. CDS Maintenance Indicators and Sediment Storage Capacities CDS Model Diameter Distance from Water Surface to Top of Sediment Pile Sediment Storage Capacity ft m ft m yd3 m3 CDS2015 5 1.5 3.0 0.9 1.3 1.0 CDS2020 5 1.5 3.5 1.1 1.3 1.0 CDS2025 5 1.5 4.0 1.2 1.3 1.0 CDS3020 6 1.8 4.0 1.2 2.1 1.6 CDS3030 6 1.8 4.6 1.4 2.1 1.6 CDS3035 6 1.8 5.0 1.5 2.1 1.6 CDS4030 8 2.4 4.6 1.4 5.6 4.3 CDS4040 8 2.4 5.7 1.7 5.6 4.3 CDS4045 8 2.4 6.2 1.9 5.6 4.3 ————————————————————————————————— MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.59 Program License Number: 201910001 Project Simulation Performed on: 08/29/2024 2:56 PM Report Generation Date: 08/29/2024 2:56 PM ————————————————————————————————— Input File Name: 2024-08-29 RSD Transportation Expansion TESC Sizing.fld Project Name: RSD Transportation Expansion Analysis Title: TESC Sizing Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Full Period of Record Available used for Routing Climatic Region Number: 16 Precipitation Station : 96004405 Puget East 44 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961044 Puget East 44 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : Ecology Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.470 0.470 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.470 0.470 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- C, Forest, Flat 0.470 ---------------------------------------------- TESC - SEDIMENTATION TANK SIZING CALCULATIONS Subbasin Total 0.470 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- SIDEWALKS/FLAT 0.470 ---------------------------------------------- Subbasin Total 0.470 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 0 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 89.444 _____________________________________ Total: 89.444 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 0.000 _____________________________________ Total: 0.000 Total Predevelopment Recharge is Greater than Post Developed TESC - SEDIMENTATION TANK SIZING CALCULATIONS Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.566 ac-ft/year, Post Developed: 0.000 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 ***********Compliance Point Results ************* Scenario Predeveloped Compliance Subbasin: Subbasin 1 Scenario Postdeveloped Compliance Subbasin: Subbasin 1 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 1.183E-02 2-Year 0.193 5-Year 1.865E-02 5-Year 0.249 10-Year 2.319E-02 10-Year 0.293 25-Year 3.195E-02 25-Year 0.367 50-Year 3.509E-02 50-Year 0.440 100-Year 3.803E-02 100-Year 0.547 200-Year 5.630E-02 200-Year 0.583 500-Year 8.085E-02 500-Year 0.629 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals TESC - SEDIMENTATION TANK SIZING CALCULATIONS Proposed Runoff Conditions for TESC - Entire Site Total Site:Area (ac) Pervious Area 0.000 Impervious Area 0.470 Total Area 0.470 Stormshed Data Type Reduced Time Step 15-min MGS - Flood 2-Yr developed flow 0.193 cfs MGS - Flood 10-Yr developed flow 0.293 cfs MGS - Flood 25-Yr developed flow 0.367 cfs MGS - Flood 100-Yr developed flow 0.547 cfs Vr=S.A. x 3.5'Vr = Minimum Required Storage Volume S.A. = Minimum allowable top surface area of pond S.A. = (2Q2)/Vsed Q = design peak flow rate Vsed = 0.00096 Settling Velocity (0.00096 ft/sec) Q=0.193 cfs INPUT (note that this is the 10-yr design peak flow rate in cfs) S.A. = 402 sf Vr=1407 cf Volume Required 10,527 gal 1 sediment storage tanks are required. * the volume is based a minimum pond depth of 3.5' - this depth does not include the minimum sediment storage volume or freeboard Assume 18,900 gallons per sediment storage tank, then Temporary Sediment Trap Sizing: Storage Volume per Section D.2.1.5, ESC Measures: Selection of the Design Storm of the 2021 King County Surface Water Design Manual - Appendix D: 255 S. King Street, Suite 800, Seattle, WA 98104 | 206.426.2600 | JACOBSONENGINEERS.COM RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 23 APPENDIX C STORMWATER POLLUTION PREVENTION PLAN (SWPPP) Construction Stormwater General Permit (CSWGP) Stormwater Pollution Prevention Plan (SWPPP) for RSD Transportation Expansion Prepared for: Renton School District Capital Planning & Construction Permittee / Owner Developer Operator / Contractor Renton School District Renton School District TBD 420 Park Ave N, Renton, WA 98057 Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD TBD TBD SWPPP Prepared By Name Organization Contact Phone Number Sascha Eastman Jacobson Consulting Engineers Office: (206) 426-2600 SWPPP Preparation Date 10/18/2024 Project Construction Dates Activity / Phase Start Date End Date Sitework and Building Construction June 1, 2025 September 30, 2025 Page | 1 Table of Contents 1. Project Information .......................................................................................................................... 4 1.1 Existing Conditions ......................................................................................................................... 4 1.2 Proposed Construction Activities .................................................................................................... 5 2. Construction Stormwater Best Management Practices (BMPs) .................................................... 6 2.1 The 13 Elements ............................................................................................................................. 6 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits ........................................................... 6 2.1.2 Element 2: Establish Construction Access ............................................................................... 7 2.1.3 Element 3: Control Flow Rates ................................................................................................. 8 2.1.4 Element 4: Install Sediment Controls ........................................................................................9 2.1.5 Element 5: Stabilize Soils ........................................................................................................10 2.1.6 Element 6: Protect Slopes........................................................................................................11 2.1.7 Element 7: Protect Drain Inlets ................................................................................................12 2.1.8 Element 8: Stabilize Channels and Outlets .............................................................................13 2.1.9 Element 9: Control Pollutants ..................................................................................................14 2.1.10 Element 10: Control Dewatering .............................................................................................17 2.1.11 Element 11: Maintain BMPs ....................................................................................................18 2.1.12 Element 12: Manage the Project .............................................................................................19 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs ....................................................22 3. Pollution Prevention Team .............................................................................................................23 4. Monitoring and Sampling Requirements ........................................................................................24 4.1 Site Inspection ...............................................................................................................................24 4.2 Stormwater Quality Sampling ........................................................................................................24 4.2.1 Turbidity Sampling ..................................................................................................................24 4.2.2 pH Sampling ...........................................................................................................................27 5. Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies ....................................28 5.1 303(d) Listed Waterbodies .............................................................................................................28 5.2 TMDL Waterbodies .......................................................................................................................28 6. Reporting and Record Keeping ......................................................................................................29 6.1 Record Keeping .............................................................................................................................29 6.1.1 Site Log Book ..........................................................................................................................29 6.1.2 Records Retention ..................................................................................................................29 6.1.3 Updating the SWPPP ..............................................................................................................29 6.2 Reporting .......................................................................................................................................30 6.2.1 Discharge Monitoring Reports .................................................................................................30 6.2.2 Notification of Noncompliance .................................................................................................30 Page | 2 List of Tables Table 1 – Summary of Site Pollutant Constituents ....................................................................... 5 Table 2 – Pollutants .....................................................................................................................14 Table 3 – pH-Modifying Sources .................................................................................................15 Table 4 – Dewatering BMPs ........................................................................................................17 Table 5 – Management ................................................................................................................19 Table 6 – BMP Implementation Schedule ....................................................................................20 Table 7 – Team Information .........................................................................................................23 Table 8 – Turbidity Sampling Method ..........................................................................................24 Table 9 – pH Sampling Method ...................................................................................................27 List of Appendices A. Site Map B. BMP Details C. Correspondence (N/A) D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) (N/A) F. 303(d) List Waterbodies / TMDL Waterbodies Information (N/A) G. Contaminated Site Information (N/A) H. Engineering Calculations Page | 3 List of Acronyms and Abbreviations Acronym / Abbreviation Explanation 303(d) Section of the Clean Water Act pertaining to Impaired Waterbodies BFO Bellingham Field Office of the Department of Ecology BMP(s) Best Management Practice(s) CESCL Certified Erosion and Sediment Control Lead CO2 Carbon Dioxide CRO Central Regional Office of the Department of Ecology CSWGP Construction Stormwater General Permit CWA Clean Water Act DMR Discharge Monitoring Report DO Dissolved Oxygen Ecology Washington State Department of Ecology EPA United States Environmental Protection Agency ERO Eastern Regional Office of the Department of Ecology ERTS Environmental Report Tracking System ESC Erosion and Sediment Control GULD General Use Level Designation NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Units NWRO Northwest Regional Office of the Department of Ecology pH Power of Hydrogen RCW Revised Code of Washington SPCC Spill Prevention, Control, and Countermeasure su Standard Units SWMMEW Stormwater Management Manual for Eastern Washington SWMMWW Stormwater Management Manual for Western Washington SWPPP Stormwater Pollution Prevention Plan TESC Temporary Erosion and Sediment Control SWRO Southwest Regional Office of the Department of Ecology TMDL Total Maximum Daily Load VFO Vancouver Field Office of the Department of Ecology WAC Washington Administrative Code WSDOT Washington Department of Transportation WWHM Western Washington Hydrology Model Page | 4 1 Project Information Project/Site Name: Renton Schol District Transportation Street/Location: 420 Park Ave N City: Renton State: WA Zip code: 98057 Subdivision: N/A Receiving waterbody: Puget Sound 1.1 Existing Conditions The project for the Renton School District Transportation is located at 420 Park Ave N, Renton, WA, 98057 on the property of the Renton School District. The area within the district’s property boundary includes three parcels. Parcel 1 (7564600105) which is 4.76 acres, parcel 2 (7224000675) which is 0.28 acres, and parcel 3 (7224000676) which is 0.17 acres. The parcels are completely developed and combined and are roughly rectangular. The property consists of the Renton School District Transportation Administration building, paved employee parking, paved bus parking, and adjacent landscaping surrounding the parking areas. The property slopes mildly to the north with approximately 3 feet of elevation change across the entire site. Total acreage: 5.21-acre Disturbed acreage: 0.48-acre Landscape topography: In general, the site topography of the Renton School District Transportation property is mild, and slopes to the north with an elevation change of approximately 3 vertical feet. Drainage patterns: Stormwater from the project site flows northwest except for a small portion that drains at the southwest corner. From the site to the north, water is taken offsite and enters the municipal system on N 5th Street. From 5th Street, it connects to Burnett Avenue N and then onto 6th Street N. The stormwater then connects to an outfall into the Cedar River which eventually drains into Lake Washington. Existing Vegetation: The entire site is developed, and the only vegetation exists in small, landscaped areas along the paved parking areas. Critical Areas: There are no critical areas in the vicinity of the proposed project work. List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: The project discharges to the Cedar River with no known TMDL and is not 303(d) listed. Page | 5 Table 1 below includes a list of suspected and/or known contaminants associated with the construction activity. Table 1 – Summary of Site Pollutant Constituents Constituent (Pollutant) Location Depth Concentration Oil and Grease Parking Lot Surface Typical concentration from parking lots Total Suspended Solids Buildings and Parking Lots Surface N/A pH Newly installed concrete areas Surface N/A 1.2 Proposed Construction Activities Description of site development: The proposed project consists of removing existing driveways, redeveloping and expanding the northwest parking lot Description of construction activities (example: site preparation, demolition, excavation): The project will consist of site preparation, demolition, paving, stormwater and electrical utility installation, and various landscaping elements. Description of site drainage including flow from and onto adjacent properties. Must be consistent with Site Map in Appendix A: Stormwater from the project site flows northwest except for a small portion that drains at the southwest corner. From the site to the north, water is taken offsite and enters the municipal system on N 5th Street. From 5th Street, it connects to Burnett Avenue N and then onto 6th Street N. The stormwater then connects to an outfall into the Cedar River which eventually drains into Lake Washington. Description of final stabilization (example: extent of revegetation, paving, landscaping): At final stabilization, the project will include a redeveloped parking lot expansion with asphalt and concrete pavements and landscaping, consisting of groundcover/shrub, trees, and grass. Contaminated Site Information: Proposed activities regarding contaminated soils or groundwater (example: on-site treatment system, authorized sanitary sewer discharge) - There are no contaminated soil or groundwater conditions known at the project site and therefore no proposed activities for the cleanup of existing contamination. Page | 6 2 Construction Stormwater Best Management Practices (BMPs) The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e. hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. 2.1 The 13 Elements 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied for this project include: List and describe BMPs: · Preserving Natural Vegetation (BMP C101) · High-Visibility Fence (BMP C103) Installation Schedules: BMPs will be installed at the beginning of construction and be inspected and maintained throughout construction. Page | 7 2.1.2 Element 2: Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on-site. The specific BMPs related to establishing construction access that will be used on this project include: List and describe BMPs: · N/A; the contractor shall utilize existing paved asphalt and concrete areas adjacent to the proposed project site for construction access, laydown, and staging. Installation Schedules: BMPs will be installed at the beginning of construction and be inspected and maintained throughout construction. Page | 8 2.1.3 Element 3: Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The specific BMPs for flow control that shall be used on this project include: Will you construct stormwater retention and/or detention facilities? No Will you use permanent infiltration ponds or other low-impact development (example: rain gardens, bio-retention, porous pavement) to control flow during construction? No List and describe BMPs: · The project will install Straw Wattles and Catch Basin Filter Socks to slow down and control any construction stormwater from entering the existing downstream storm system: o Interceptor Dike and Swale (BMP C200) o Storm Drain Inlet Protection (BMP C220) o Silt Fence (BMP C233) o Straw Wattles (BMP C235) o Sediment Trap (BMP C240) o Temporary Water Storage Tanks for Sedimentation Installation Schedules: BMPs will be installed at the beginning of construction and be inspected and maintained throughout construction until the site is fully stabilized and permanent flow control facilities are functioning. Page | 9 2.1.4 Element 4: Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or before being discharged to an infiltration facility. Specific BMPs to be used for controlling sediment on this project include: List and describe BMPs: · Inlet Protection (BMP C220) · Silt Fence (BMP C233) · Straw Wattles (BMP C235) · Sediment Trap (BMP C240) · Temporary Water Storage Tanks for Sedimentation Installation Schedules: BMPs will be installed at the beginning of construction and be inspected and maintained throughout construction. Page | 10 2.1.5 Element 5: Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project are listed below: List and describe BMPs: · Temporary and Permanent Seeding (BMP C120) · Mulching (BMP C121) · Plastic Covering (BMP C123) West of the Cascade Mountains Crest Season Dates Number of Days Soils Can be Left Exposed During the Dry Season May 1 – September 30 7 days During the Wet Season October 1 – April 30 2 days Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Will you construct during the wet season? NO; project is not anticipating performing construction past October. Installation Schedules: BMPs will be installed at the beginning of construction and be inspected and maintained throughout construction until the site is fully stabilized. Page | 11 2.1.6 Element 6: Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner that minimizes erosion during construction. Will steep slopes be present at the site during construction? No List and describe BMPs: · N/A; No steep slopes will be present at the site during construction, therefore no slope protection BMPs are necessary. Installation Schedules: BMPs will be installed at the beginning of construction and be inspected and maintained throughout construction until the site is fully stabilized. Page | 12 2.1.7 Element 7: Protect Drain Inlets All storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. However, the first priority is to keep all access roads clean of sediment and keep street wash water separate from entering storm drains until treatment can be provided. Storm Drain Inlet Protection (BMP C220) will be implemented for all drainage inlets and culverts that could potentially be impacted by sediment-laden runoff on and near the project site. All inlets will be inspected weekly at a minimum and daily during storm events. Inlet protection devices will be cleaned or replaced when sediment has reached 1/3 capacity or as specified by the product manufacturer. List and describe BMPs: · Interceptor Dike and Swale (BMP C200) · Inlet Protection (BMP C220) · Silt Fence (BMP C233) · Straw Wattles (BMP C235) · Sediment Trap (BMP C240) · Temporary Water Storage Tanks for Sedimentation Installation Schedules: BMPs will be installed at the beginning of construction and be inspected and maintained throughout construction until the site is fully stabilized and permanent flow control facilities are functioning. Page | 13 2.1.8 Element 8: Stabilize Channels and Outlets Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural discharge point, efforts will be taken to prevent downstream erosion. Temporary settlement tanks will be provided on-site to attenuate flows and remove sediment before discharging to the existing storm system. Hydrologic analysis has been performed and found in Appendix H. Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all conveyance systems. List and describe BMPs: · Interceptor Dike and Swale (BMP C200) · Sediment Trap (BMP C240) · Temporary Water Storage Tanks for Sedimentation Installation Schedules: BMPs will be installed at the beginning of construction and be inspected and maintained throughout construction until the site is fully stabilized and permanent flow control facilities are functioning. Page | 14 2.1.9 Element 9: Control Pollutants The following pollutants are anticipated to be present on-site: Table 2 – Pollutants Pollutant (and source, if applicable) Vehicles and construction equipment Demolition Concrete and grout All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well-organized, and free of debris. Vehicles, construction equipment, and/or petroleum product storage/dispensing: · All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. · On-site fueling tanks and petroleum product storage containers shall include secondary containment. · Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. · In order to perform emergency repairs on-site, temporary plastic will be placed beneath and, if raining, over the vehicle. · Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Demolition: · Dust released from demolished sidewalks, buildings, or structures will be controlled using Dust Control measures (BMP C140). · Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet Protection (BMP C220 as described above for Element 7). · Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering the waters of the State by implementing Sawcutting and Surfacing Pollution Prevention measures (BMP C152). Page | 15 Concrete and grout: · Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C151) List and describe BMPs: · Materials on Hand (BMP C150) · Concrete Handling (BMP C151) · Sawcutting and Surfacing Pollution Prevention (BMP C152) · Material Delivery, Storage, and Containment (BMP C153) · Concrete Washout Area (BMP C154) Installation Schedules: BMPs will be implemented at the beginning of construction and be inspected and maintained throughout construction until the site is fully stabilized. Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? No Will wheel wash or tire bath system BMPs be used during construction? No; the contractor shall utilize existing paved asphalt and concrete areas adjacent to the proposed project site for construction access, laydown, and staging Will pH-modifying sources be present on-site? YES Table 3 – pH-Modifying Sources None X Bulk cement Cement kiln dust Fly ash X Other cementitious materials X New concrete washing or curing waters X Waste streams generated from concrete grinding and sawing Exposed aggregate processes Dewatering concrete vaults Concrete pumping and mixer washout waters Recycled concrete Other (i.e. calcium lignosulfate) [please describe] Page | 16 List and describe BMPs: · Materials on Hand (BMP C150) · Concrete Handling (BMP C151) · Sawcutting and Surfacing Pollution Prevention (BMP C152) · Material Delivery, Storage and Containment (BMP C153) · Concrete Washout Area (BMP C154) · Treating and Disposing of High pH Water (BMP C252) Installation Schedules: BMP’s will be implemented at the beginning of construction and be inspected and maintained throughout construction as required. Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches, streets, or streams. Excess concrete must not be dumped on-site, except in designated concrete washout areas with appropriate BMPs installed. Page | 17 2.1.10 Element 10: Control Dewatering This project does not propose dewatering and therefore will not be implementing any dewatering BMPs associated with Element 10. Table 4 – Dewatering BMPs Infiltration Transport off-site in a vehicle (vacuum truck for legal disposal) Ecology-approved on-site chemical treatment or other suitable treatment technologies Sanitary or combined sewer discharge with local sewer district approval (last resort) Use of sedimentation bag with discharge to ditch or swale (small volumes of localized dewatering) List and describe BMPs: N/A Page | 18 2.1.11 Element 11: Maintain BMPs All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained and repaired as needed to ensure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMP specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW). Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to once every calendar month. All temporary ESC BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal of either BMPs or vegetation shall be permanently stabilized. Additionally, protection must be provided for all BMPs installed for the permanent control of stormwater from sediment and compaction. BMPs that are to remain in place following completion of construction shall be examined and restored to full operating condition. If sediment enters these BMPs during construction, the sediment shall be removed and the facility shall be returned to conditions specified in the construction documents. Page | 19 2.1.12 Element 12: Manage the Project The project will be managed based on the following principles: · Projects will be phased to the maximum extent practicable and seasonal work limitations will be taken into account. · Inspection and monitoring: o Inspection, maintenance, and repair of all BMPs will occur as needed to ensure the performance of their intended function. o Site inspections and monitoring will be conducted in accordance with City of Renton Standards. Sampling locations are indicated on the Site Map, included in Appendix A. · Maintain an updated SWPPP. o The SWPPP will be updated, maintained, and implemented in accordance with h City of Renton Standards and project specifications. As site work progresses the SWPPP will be modified routinely to reflect changing site conditions. The SWPPP will be reviewed monthly to ensure the content is current. Table 5 – Management X Design the project to fit the existing topography, soils, and drainage patterns X Emphasize erosion control rather than sediment control X Minimize the extent and duration of the area exposed X Keep runoff velocities low X Retain sediment on-site X Thoroughly monitor the site and maintain all ESC measures X Schedule major earthwork during the dry season Other (please describe) Page | 20 Table 6 – BMP Implementation Schedule Phase of Construction Project Stormwater BMPs Date Wet/Dry Season [Insert construction activity] [Insert BMP] [MM/DD/YYYY] [Insert Season] Page | 21 Phase of Construction Project Stormwater BMPs Date Wet/Dry Season [Insert construction activity] [Insert BMP] [MM/DD/YYYY] [Insert Season] Page | 22 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs The project will be implementing BMP T5.13 for Post-Construction Soil Quality and Depth. To comply with the requirements of this BMP, the duff layer and native topsoil’s will be stockpiled and retained on site during grading activities to be reapplied for use in post-construction soils prior to planting. Existing vegetation or landscaped areas will be protected during construction (BMP C101, C103, and C233). Topsoil’s will be imported as needed to meet BMP T5.13 requirements. Soil quality and depth will be established at the end of construction to prevent compaction from heavy machinery. Page | 23 3 Pollution Prevention Team Table 7 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD Resident Engineer TBD Emergency Ecology Contact TBD Emergency Permittee/ Owner Contact TBD Non-Emergency Owner Contact TBD Monitoring Personnel TBD Ecology Regional Office Northwest Regional Office 425-649-7098 Page | 24 4 Monitoring and Sampling Requirements Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: · A record of the implementation of the SWPPP and other permit requirements · Site inspections · Stormwater sampling data Please find a blank form under to be completed in Appendix D. The site logbook must be maintained on-site within reasonable access to the site and be made available upon request to the City of Renton. Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. Complete the following paragraph for sites that discharge to impaired waterbodies for fine sediment, turbidity, phosphorus, or pH: 4.1 Site Inspection Site inspections will be conducted at least once every calendar week and within 24 hours following any discharge from the site. For sites that are temporarily stabilized and inactive, the required frequency is reduced to once per calendar month. The discharge point(s) are indicated on the Site Map included in Appendix A. 4.2 Stormwater Quality Sampling 4.2.1 Turbidity Sampling Requirements include a calibrated turbidity meter or transparency tube to sample site discharges for compliance with the City of Renton Standards. Sampling will be conducted at all discharge points at least once per calendar week. Page | 25 Method for sampling turbidity: Table 8 – Turbidity Sampling Method X Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size) Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size) The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency of less than 33 centimeters. If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to or greater than 6 cm, the following steps will be conducted: 1. Review the SWPPP for compliance with Special Condition S9. Make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. 3. Document BMP implementation and maintenance in the site log book. If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following steps will be conducted: 1. Telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) within 24 hours. https://www.ecology.wa.gov/About-us/Get-involved/Report-an-environmental-issue · Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, Yakima): (509) 575-2490 · Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 · Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 · Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period 3. Document BMP implementation and maintenance in the site log book. Page | 26 4. Continue to sample discharges daily until one of the following is true: · Turbidity is 25 NTU (or lower). · Transparency is 33 cm (or greater). · Compliance with the water quality limit for turbidity is achieved. o 1 - 5 NTU over background turbidity, if background is less than 50 NTU o 1% - 10% over background turbidity, if background is 50 NTU or greater · The discharge stops or is eliminated. Page | 27 4.2.2 pH Sampling pH monitoring is required for “Significant concrete work” (i.e. greater than 1000 cubic yards of poured concrete or recycled concrete over the life of the project). The use of engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD] or fly ash) also requires pH monitoring. For significant concrete work, pH sampling will start the first day the concrete is poured and continue until it is cured, typically three (3) weeks after the last pour. For engineered soils and recycled concrete, pH sampling begins when engineered soils or recycled concrete are first exposed to precipitation and continues until the area is fully stabilized. If the measured pH is 8.5 or greater, the following measures will be taken: 1. Prevent high pH water from entering storm sewer systems or surface water. 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate technology such as carbon dioxide (CO2) sparging (liquid or dry ice). 3. Written approval will be obtained from Ecology or City of Renton prior to the use of chemical treatment other than CO2 sparging or dry ice. Method for sampling pH: Table 9 – pH Sampling Method X pH meter pH test kit Wide range pH indicator paper Page | 28 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies 5.1 303(d) Listed Waterbodies Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? NO List the impairment(s): N/A List and describe BMPs: N/A 5.2 TMDL Waterbodies Waste Load Allocation for CWSGP discharges: This project site discharges to the Goat Trail Ravine Basin. The proposed development is not proposing any pollution generating surfaces and is therefore not required provide water quality treatment and does not discharge to a TMDL Waterbody. Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. N/A; project site disturbance is less than 1.0 acres, therefore a CSWGP is not required for this project. Page | 29 6 Reporting and Record Keeping 6.1 Record Keeping 6.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: · A record of the implementation of the SWPPP and other permit requirements · Site inspections · Sample logs 6.1.2 Records Retention Records will be retained during the life of the project and for a minimum of three (3) years following the termination of permit coverage in accordance with Special Condition S5.C of the CSWGP. Permit documentation to be retained on-site: · CSWGP; N/A project site disturbance is less than 1.0 acres. · Permit Coverage Letter; N/A project site disturbance is less than 1.0 acres. · SWPPP · Site Log Book Permit documentation will be provided within 14 days of receipt of a written request from Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP. 6.1.3 Updating the SWPPP The SWPPP will be modified if: · Found ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. · There is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine additional or modified BMPs are necessary for compliance. An updated timeline for BMP implementation will be prepared. Page | 30 6.2 Reporting 6.2.1 Discharge Monitoring Reports Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given monitoring period the DMR will be submitted as required, reporting “No Discharge”. The DMR due date is fifteen (15) days following the end of each calendar month. DMRs will be reported online through Ecology’s WQWebDMR System. N/A project site disturbance is less than 1.0 acres. 6.2.2 Notification of Noncompliance If any of the terms and conditions of the permit is not met, and the resulting noncompliance may cause a threat to human health or the environment, the following actions will be taken: 1. Ecology will be notified within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number (Regional office numbers listed below). 2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or correct the noncompliance. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6 cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as required by Special Condition S5.A of the CSWGP. · Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, or Yakima County · Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman County · Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County · Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum Page | 31 Include the following information: 1. Your name and / Phone number 2. Permit number 3. City / County of project 4. Sample results 5. Date / Time of call 6. Date / Time of sample 7. Project name In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water. Page | 32 Appendix/Glossary A. Site Map B. BMP Plans and Details C. Correspondence - N/A D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information – N/A G. Contaminated Site Information - N/A H. Engineering Calculations Page | 33 Appendix A – Site Map Vicinity Map Temporary Erosion and Sediment Control (TESC) Plans & Details 255 S. King Street, Suite 800, Seattle, WA 98104 | 206.399.6233 | JACOBSONENGINEERS.COM206.426.2600 VICINITY MAPSCALE: NTS Project Site Project Site NOTE - PLANS HAVE BEEN SCALED TO 11X17 NOTE - PLANS HAVE BEEN SCALED TO 11X17 NOTE - PLANS HAVE BEEN SCALED TO 11X17 Page | 34 Appendix B – BMP Details Preserving Natural Vegetation (BMP C101) High Visibility Fence (BMP C103) Temporary and Permanent Seeding (BMP C120) Mulching (BMP C121) Plastic Covering (BMP C123) Dust Control (BMP C140) Materials on Hand (BMP C150) Concrete Handling (BMP C151) Sawcutting and Surfacing Pollution Prevention (BMP C152) Material Delivery, Storage and Containment (BMP C153) Concrete Washout Area (BMP C154) Certified Erosion and Sediment Control Lead (BMP C160) Scheduling (BMP C162) Interceptor Dike and Swale (BMP C200) Storm Drain Inlet Protection (BMP C220) Silt Fence (BMP C233) Wattles (BMP C235) Sediment Trap (BMP C240) Construction Stormwater Chemical Treatment (BMP C250) Construction Stormwater Filtration (BMP C251) Treating and Disposing of High pH Water (BMP C252) BMP C101: Preserving Natural Vegetation Purpose The purpose of preserving natural vegetation is to reduce erosion wherever practicable. Limiting site disturbance is the single most effective method for reducing erosion. For example, conifers can hold up to about 50 percent of all rain that falls during a storm. Up to 20-30 percent of this rain may never reach the ground but is taken up by the tree or evaporates. Another benefit is that the rain held in the tree can be released slowly to the ground after the storm. Conditions of Use Natural vegetation should be preserved on steep slopes, near perennial and intermittent water- courses or swales, and on building sites in wooded areas. l As required by local governments. l Phase construction to preserve natural vegetation on the project site for as long as possible during the construction period. Design and Installation Specifications Natural vegetation can be preserved in natural clumps or as individual trees, shrubs and vines. The preservation of individual plants is more difficult because heavy equipment is generally used to remove unwanted vegetation. The points to remember when attempting to save individual plants are: l Is the plant worth saving? Consider the location, species, size, age, vigor, and the work involved. Local governments may also have ordinances to save natural vegetation and trees. l Fence or clearly mark areas around trees that are to be saved. It is preferable to keep ground disturbance away from the trees at least as far out as the dripline. Plants need protection from three kinds of injuries: l Construction Equipment - This injury can be above or below the ground level. Damage results from scarring, cutting of roots, and compaction of the soil. Placing a fenced buffer zone around plants to be saved prior to construction can prevent construction equipment injuries. l Grade Changes - Changing the natural ground level will alter grades, which affects the plant's ability to obtain the necessary air, water, and minerals. Minor fills usually do not cause prob- lems although sensitivity between species does vary and should be checked. Trees can typ- ically tolerate fill of 6 inches or less. For shrubs and other plants, the fill should be less. When there are major changes in grade, it may become necessary to supply air to the roots of plants. This can be done by placing a layer of gravel and a tile system over the roots before the fill is made. The tile system should be laid out on the original grade leading from a dry well 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 271 around the tree trunk. The system should then be covered with small stones to allow air to cir- culate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest per- centage of the plant roots are in the upper 12 inches of the soil and cuts of only 2-3 inches can cause serious injury. To protect the roots it may be necessary to terrace the immediate area around the plants to be saved. If roots are exposed, construction of retaining walls may be needed to keep the soil in place. Plants can also be preserved by leaving them on an undis- turbed, gently sloping mound. To increase the chances for survival, it is best to limit grade changes and other soil disturbances to areas outside the dripline of the plant. l Excavations - Protect trees and other plants when excavating for drainfields, power, water, and sewer lines. Where possible, the trenches should be routed around trees and large shrubs. When this is not possible, it is best to tunnel under them. This can be done with hand tools or with power augers. If it is not possible to route the trench around plants to be saved, then the following should be observed: o Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends with a wood dressing like asphalt base paint if roots will be exposed for more than 24-hours. o Backfill the trench as soon as possible. o Tunnel beneath root systems as close to the center of the main trunk to preserve most of the important feeder roots. Some problems that can be encountered with a few specific trees are: l Maple, Dogwood, Red alder, Western hemlock, Western red cedar, and Douglas fir do not readily adjust to changes in environment and special care should be taken to protect these trees. l The windthrow hazard of Pacific silver fir and madrona is high, while that of Western hemlock is moderate. The danger of windthrow increases where dense stands have been thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep) have a low windthrow hazard. l Cottonwoods, maples, and willows have water-seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions that other trees would not. l Thinning operations in pure or mixed stands of Grand fir, Pacific silver fir, Noble fir, Sitka spruce, Western red cedar, Western hemlock, Pacific dogwood, and Red alder can cause ser- ious disease problems. Disease can become established through damaged limbs, trunks, roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect attack. Maintenance Standards Inspect flagged and/or fenced areas regularly to make sure flagging or fencing has not been removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 272 If tree roots have been exposed or injured, “prune” cleanly with an appropriate pruning saw or lop- pers directly above the damaged roots and recover with native soils. Treatment of sap flowing trees (fir, hemlock, pine, soft maples) is not advised as sap forms a natural healing barrier. BMP C102: Buffer Zones Purpose Creation of an undisturbed area or strip of natural vegetation or an established suitable planting that will provide a living filter to reduce soil erosion and stormwater runoff velocities. Conditions of Use Buffer zones are used along streams, wetlands and other bodies of water that need protection from erosion and sedimentation. Contractors can use vegetative buffer zone BMPs to protect natural swales and they can incorporate them into the natural landscaping of an area. Do not use critical-areas buffer zones as sediment treatment areas. These areas shall remain com- pletely undisturbed. The local permitting authority may expand the buffer widths temporarily to allow the use of the expanded area for removal of sediment. The types of buffer zones can change the level of protection required as shown below: Designated Critical Area Buffers - buffers that protect Critical Areas, as defined by the Washington State Growth Management Act, and are established and managed by the local permitting authority. These should not be disturbed and must protected with sediment control BMPs to prevent impacts. The local permitting authority may expand the buffer widths temporarily to allow the use of the expan- ded area for removal of sediment. Vegetative Buffer Zones - areas that may be identified in undisturbed vegetation areas or managed vegetation areas that are outside any Designated Critical Area Buffer. They may be utilized to provide an additional sediment control area and/or reduce runoff velocities. If being used for pre- servation of natural vegetation, they should be arranged in clumps or strips. They can be used to pro- tect natural swales and incorporated into the natural landscaping area. Design and Installation Specifications l Preserving natural vegetation or plantings in clumps, blocks, or strips is generally the easiest and most successful method. l Leave all unstable steep slopes in natural vegetation. l Mark clearing limits and keep all equipment and construction debris out of the natural areas and buffer zones. Steel construction fencing is the most effective method to protect sensitive areas and buffers. Alternatively, wire-backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective. l Keep all excavations outside the dripline of trees and shrubs. l Do not push debris or extra soil into the buffer zone area because it will cause damage by 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 273 N/A burying and smothering vegetation. l Vegetative buffer zones for streams, lakes or other waterways shall be established by the local permitting authority or other state or federal permits or approvals. Maintenance Standards Inspect the area frequently to make sure flagging remains in place and the area remains undis- turbed. Replace all damaged flagging immediately. Remove all materials located in the buffer area that may impede the ability of the vegetation to act as a filter. BMP C103: High-Visibility Fence Purpose High-visibility fencing is intended to: l Restrict clearing to approved limits. l Prevent disturbance of sensitive areas, their buffers, and other areas required to be left undis- turbed. l Limit construction traffic to designated construction entrances, exits, or internal roads. l Protect areas where marking with survey tape may not provide adequate protection. Conditions of Use To establish clearing limits plastic, fabric, or metal fence may be used: l At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. l As necessary to control vehicle access to and on the site. Design and Installation Specifications High-visibility plastic fence shall be composed of a high-density polyethylene material and shall be at least four feet in height. Posts for the fencing shall be steel or wood and placed every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color shall be high-visibility orange. The fence tensile strength shall be 360 lbs/ft using the ASTM D4595 testing method. If appropriate install fabric silt fence in accordance with BMP C233: Silt Fence to act as high-visibility fence. Silt fence shall be at least 3 feet high and must be highly visible to meet the requirements of this BMP. Metal fences shall be designed and installed according to the manufacturer's specifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 274 Crushed rock, gravel base, etc., shall be added as required to maintain a stable driving surface and to stabilize any areas that have eroded. Following construction, these areas shall be restored to pre-construction condition or better to pre- vent future erosion. Perform street cleaning at the end of each day or more often if necessary. BMP C120: Temporary and Permanent Seeding Purpose Seeding reduces erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducing erosion. Conditions of Use Use seeding throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. The optimum seeding windows for western Washington are April 1 through June 30 and September 1 through October 1. Between July 1 and August 30 seeding requires irrigation until 75 percent grass cover is established. Between October 1 and March 30 seeding requires a cover of mulch or an erosion control blanket until 75 percent grass cover is established. Review all disturbed areas in late August to early September and complete all seeding by the end of September. Otherwise, vegetation will not establish itself enough to provide more than average pro- tection. Mulch is required at all times for seeding because it protects seeds from heat, moisture loss, and transport due to runoff. Mulch can be applied on top of the seed or simultaneously by hydroseeding. See BMP C121: Mulching for specifications. Seed and mulch all disturbed areas not otherwise vegetated at final site stabilization. Final sta- bilization means the completion of all soil disturbing activities at the site and the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (such as pavement, riprap, gabions, or geotextiles) which will prevent erosion. See BMP T5.13: Post-Construction Soil Quality and Depth. Design and Installation Specifications General l Install channels intended for vegetation before starting major earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated channels that will have high flows, install erosion control blankets over the top of hydroseed. Before allowing water to flow in vegetated channels, establish 75 percent vegetation cover. If vegetated channels cannot be established by seed 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 284 before water flow; install sod in the channel bottom — over top of hydromulch and erosion con- trol blankets. l Confirm the installation of all required surface water control measures to prevent seed from washing away. l Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 per- cent tackifier. See BMP C121: Mulching for specifications. l Areas that will have seeding only and not landscaping may need compost or meal-based mulch included in the hydroseed in order to establish vegetation. Re-install native topsoil on the disturbed soil surface before application. See BMP T5.13: Post-Construction Soil Quality and Depth. l When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends up in contact with the soil surface. This reduces the ability to establish a good stand of grass quickly. To overcome this, consider increasing seed quantities by up to 50 percent. l Enhance vegetation establishment by dividing the hydromulch operation into two phases: o Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift. o Phase 2- Install the rest of the mulch and tackifier over the first lift. Or, enhance vegetation by: o Installing the mulch, seed, fertilizer, and tackifier in one lift. o Spread or blow straw over the top of the hydromulch at a rate of 800-1000 pounds per acre. o Hold straw in place with a standard tackifier. Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost may be offset by the reduced need for: o Irrigation. o Reapplication of mulch. o Repair of failed slope surfaces. This technique works with standard hydromulch (1,500 pounds per acre minimum) and Bon- ded Fiber Matrix/ Mechanically Bonded Fiber Matrix (BFM/MBFMs) (3,000 pounds per acre minimum). l Seed may be installed by hand if: o Temporary and covered by straw, mulch, or topsoil. o Permanent in small areas (usually less than 1 acre) and covered with mulch, topsoil, or erosion blankets. l The seed mixes listed in Table II-3.4: Temporary and Permanent Seed Mixes include 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 285 recommended mixes for both temporary and permanent seeding. l Apply these mixes, with the exception of the wet area seed mix, at a rate of 120 pounds per acre. This rate can be reduced if soil amendments or slow-release fertilizers are used. Apply the wet area seed mix at a rate of 60 pounds per acre. l Consult the local suppliers or the local conservation district for their recommendations. The appropriate mix depends on a variety of factors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used, depending on the soil type and hydrology of the area. Common Name Latin Name % Weight % Purity % Germination Temporary Erosion Control Seed Mix A standard mix for areas requiring a temporary vegetative cover. Chewings or annual blue grass Festuca rubra var. commutata or Poa anna 40 98 90 Perennial rye Lolium perenne 50 98 90 Redtop or colonial bentgrass Agrostis alba or Agrostis tenuis 5 92 85 White dutch clover Trifolium repens 5 98 90 Landscaping Seed Mix A recommended mix for landscaping seed. Perennial rye blend Lolium perenne 70 98 90 Chewings and red fescue blend Festuca rubra var. commutata or Fes- tuca rubra 30 98 90 Low-Growing Turf Seed Mix A turf seed mix for dry situations where there is no need for watering. This mix requires very little main- tenance. Dwarf tall fescue (several varieties) Festuca arundin- acea var. 45 98 90 Dwarf perennial rye (Barclay) Lolium perenne var. barclay 30 98 90 Red fescue Festuca rubra 20 98 90 Colonial bentgrass Agrostis tenuis 5 98 90 Bioswale Seed Mix A seed mix for bioswales and other intermittently wet areas. Tall or meadow fes-Festuca arundin-75-80 98 90 Table II-3.4: Temporary and Permanent Seed Mixes 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 286 Common Name Latin Name % Weight % Purity % Germination cue acea or Festuca elatior Seaside/Creeping bentgrass Agrostis palustris 10-15 92 85 Redtop bentgrass Agrostis alba or Agrostis gigantea 5-10 90 80 Wet Area Seed Mix A low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wet- lands. Consult Hydraulic Permit Authority (HPA) for seed mixes if applicable. Tall or meadow fes- cue Festuca arundin- acea or Festuca elatior 60-70 98 90 Seaside/Creeping bentgrass Agrostis palustris 10-15 98 85 Meadow foxtail Alepocurus praten- sis 10-15 90 80 Alsike clover Trifolium hybridum 1-6 98 90 Redtop bentgrass Agrostis alba 1-6 92 85 Meadow Seed Mix A recommended meadow seed mix for infrequently maintained areas or non-maintained areas where col- onization by native plants is desirable. Likely applications include rural road and utility right-of-way. Seed- ing should take place in September or very early October in order to obtain adequate establishment prior to the winter months. Consider the appropriateness of clover, a fairly invasive species, in the mix. Amending the soil can reduce the need for clover. Redtop or Oregon bentgrass Agrostis alba or Agrostis ore- gonensis 20 92 85 Red fescue Festuca rubra 70 98 90 White dutch clover Trifolium repens 10 98 90 Table II-3.4: Temporary and Permanent Seed Mixes (continued) Roughening and Rototilling l The seedbed should be firm and rough. Roughen all soil no matter what the slope. Track walk slopes before seeding if engineering purposes require compaction. Backblading or smoothing of slopes greater than 4H:1V is not allowed if they are to be seeded. l Restoration-based landscape practices require deeper incorporation than that provided by a simple single-pass rototilling treatment. Wherever practical, initially rip the subgrade to improve long-term permeability, infiltration, and water inflow qualities. At a minimum, 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 287 permanent areas shall use soil amendments to achieve organic matter and permeability per- formance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches complete the rototilling process in multiple lifts, or prepare the engineered soil system per specifications and place to achieve the specified depth. Fertilizers l Conducting soil tests to determine the exact type and quantity of fertilizer is recommended. This will prevent the over-application of fertilizer. l Organic matter is the most appropriate form of fertilizer because it provides nutrients (includ- ing nitrogen, phosphorus, and potassium) in the least water-soluble form. l In general, use 10-4-6 N-P-K (nitrogen-phosphorus-potassium) fertilizer at a rate of 90 pounds per acre. Always use slow-release fertilizers because they are more efficient and have fewer environmental impacts. Do not add fertilizer to the hydromulch machine, or agit- ate, more than 20 minutes before use. Too much agitation destroys the slow-release coating. l There are numerous products available that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If 100 percent cottonseed meal is used as the mulch in hydroseed, chemical fertilizer may not be necessary. Cottonseed meal provides a good source of long-term, slow-release, available nitrogen. Bonded Fiber Matrix and Mechanically Bonded Fiber Matrix l On steep slopes use Bonded Fiber Matrix (BFM) or Mechanically Bonded Fiber Matrix (MBFM) products. Apply BFM/MBFM products at a minimum rate of 3,000 pounds per acre with approximately 10 percent tackifier. Achieve a minimum of 95 percent soil coverage during application. Numerous products are available commercially. Most products require 24-36 hours to cure before rainfall and cannot be installed on wet or saturated soils. Generally, products come in 40-50 pound bags and include all necessary ingredients except for seed and fertilizer. l Install products per manufacturer's instructions. l BFMs and MBFMs provide good alternatives to blankets in most areas requiring vegetation establishment. Advantages over blankets include: o BFM and MBFMs do not require surface preparation. o Helicopters can assist in installing BFM and MBFMs in remote areas. o On slopes steeper than 2.5H:1V, blanket installers may require ropes and harnesses for safety. o Installing BFM and MBFMs can save at least $1,000 per acre compared to blankets. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 288 Maintenance Standards Reseed any seeded areas that fail to establish at least 75 percent cover (100 percent cover for areas that receive sheet or concentrated flows). If reseeding is ineffective, use an alternate method such as sodding, mulching, nets, or blankets. l Reseed and protect by mulch any areas that experience erosion after achieving adequate cover. Reseed and protect by mulch any eroded area. l Supply seeded areas with adequate moisture, but do not water to the extent that it causes run- off. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology’s website at: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies BMP C121: Mulching Purpose Mulching soils provides immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and moderating soil temperatures. There are a variety of mulches that can be used. This section discusses only the most common types of mulch. Conditions of Use As a temporary cover measure, mulch should be used: l For less than 30 days on disturbed areas that require cover. l At all times for seeded areas, especially during the wet season and during the hot summer months. l During the wet season on slopes steeper than 3H:1V with more than 10 feet of vertical relief. Mulch may be applied at any time of the year and must be refreshed periodically. For seeded areas, mulch may be made up of 100 percent: l cottonseed meal; l fibers made of wood, recycled cellulose, hemp, or kenaf; 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 289 l compost; l or blends of these. Tackifier shall be plant-based, such as guar or alpha plantago, or chemical-based such as poly- acrylamide or polymers. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. Recycled cellulose may contain polychlorinated biphenyl (PCBs). Ecology recommends that products should be evaluated for PCBs prior to use. Refer to BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection for conditions of use. PAM shall not be directly applied to water or allowed to enter a water body. Any mulch or tackifier product used shall be installed per the manufacturer’s instructions. Design and Installation Specifications For mulch materials, application rates, and specifications, see Table II-3.6: Mulch Standards and Guidelines. Consult with the local supplier or the local conservation district for their recom- mendations. Increase the application rate until the ground is 95% covered (i.e. not visible under the mulch layer). Note: Thickness may be increased for disturbed areas in or near sensitive areas or other areas highly susceptible to erosion. Where the option of “Compost” is selected, it should be a coarse compost that meets the size grad- ations listed in Table II-3.5: Size Gradations of Compost as Mulch Material when tested in accord- ance with Test Method 02.02-B found in Test Methods for the Examination of Composting and Compost (Thompson, 2001). Sieve Size Percent Passing 3"100% 1"90% - 100% 3/4"70% - 100% 1/4"40% - 100% Table II-3.5: Size Gradations of Compost as Mulch Material Mulch used within the ordinary high-water mark of surface waters should be selected to minimize potential flotation of organic matter. Composted organic materials have higher specific gravities (densities) than straw, wood, or chipped material. Consult the Hydraulic Permit Authority (HPA) for mulch mixes if applicable. Maintenance Standards The thickness of the mulch cover must be maintained. Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remulched. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 290 Mulch Mater- ial Guideline Description Straw Quality Standards Air-dried; free from undesirable seed and coarse material. Application Rates 2"-3" thick; 5 bales per 1,000 sf or 2-3 tons per acre Remarks Cost-effective protection when applied with adequate thickness. Hand- application generally requires greater thickness than blown straw. The thickness of straw may be reduced by half when used in conjunction with seeding. In windy areas straw must be held in place by crimping, using a tackifier, or covering with netting. Blown straw always has to be held in place with a tackifier as even light winds will blow it away. Straw, however, has several deficiencies that should be considered when selecting mulch materials. It often introduces and/or encourages the propagation of weed species and it has no significant long-term benefits It should also not be used within the ordinary high-water elevation of surface waters (due to flot- ation). Hydromulch Quality Standards No growth inhibiting factors. Application Rates Approx. 35-45 lbs per 1,000 sf or 1,500 - 2,000 lbs per acre Remarks Shall be applied with hydromulcher. Shall not be used without seed and tackifier unless the application rate is at least doubled. Fibers longer than about 3/4 - 1 inch clog hydromulch equipment. Fibers should be kept to less than 3/4 inch. Compost Quality Standards No visible water or dust during handling. Must be produced per WAC 173- 350, Solid Waste Handling Standards, but may have up to 35% biosolids. Application Rates 2" thick min.; approx. 100 tons per acre (approx. 750 lbs per cubic yard) Remarks More effective control can be obtained by increasing thickness to 3". Excel- lent mulch for protecting final grades until landscaping because it can be dir- ectly seeded or tilled into soil as an amendment. Compost used for mulch has a coarser size gradation than compost used for BMP C125: Topsoiling / Composting or BMP T5.13: Post-Construction Soil Quality and Depth. It is more stable and practical to use in wet areas and during rainy weather conditions. Do not use near wetlands or near phosphorous impaired water bodies. Chipped Site Veget- ation Quality Standards Gradations from fines to 6 inches in length for texture, variation, and inter- locking properties. Include a mix of various sizes so that the average size is between 2- and 4- inches. Application Rates 2" thick min.; Table II-3.6: Mulch Standards and Guidelines 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 291 Mulch Mater- ial Guideline Description Remarks This is a cost-effective way to dispose of debris from clearing and grub- bing, and it eliminates the problems associated with burning. Generally, it should not be used on slopes above approx. 10% because of its tendency to be transported by runoff. It is not recommended within 200 feet of sur- face waters. If permanent seeding or planting is expected shortly after mulch, the decomposition of the chipped vegetation may tie up nutrients important to grass establishment. Note: thick application of this material over existing grass, herbaceous spe- cies, and some groundcovers could smother and kill vegetation. Wood- Based Mulch Quality Standards No visible water or dust during handling. Must be purchased from a supplier with a Solid Waste Handling Permit or one exempt from solid waste reg- ulations. Application Rates 2" thick min.; approx. 100 tons per acre (approx. 750 lbs. per cubic yard) Remarks This material is often called "wood straw" or "hog fuel". The use of mulch ultimately improves the organic matter in the soil. Special caution is advised regarding the source and composition of wood-based mulches. Its preparation typically does not provide any weed seed control, so evidence of residual vegetation in its composition or known inclusion of weed plants or seeds should be monitored and prevented (or minimized). Wood Strand Mulch Quality Standards A blend of loose, long, thin wood pieces derived from native conifer or deciduous trees with high length-to-width ratio. Application Rates 2" thick min. Remarks Cost-effective protection when applied with adequate thickness. A min- imum of 95-percent of the wood strand shall have lengths between 2 and 10-inches, with a width and thickness between 1/16 and 1/2-inches. The mulch shall not contain resin, tannin, or other compounds in quantities that would be detrimental to plant life. Sawdust or wood shavings shall not be used as mulch. [Specification 9-14.4(4) from the Standard Specifications for Road, Bridge, and Municipal Construction (WSDOT, 2016) Table II-3.6: Mulch Standards and Guidelines (continued) BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 292 BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Use Plastic covering may be used on disturbed areas that require cover measures for less than 30 days, except as stated below. l Plastic is particularly useful for protecting cut and fill slopes and stockpiles. However, the rel- atively rapid breakdown of most polyethylene sheeting makes it unsuitable for applications greater than six months. l Due to rapid runoff caused by plastic covering, do not use this method upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. l Plastic sheeting may result in increased runoff volumes and velocities, requiring additional on- site measures to counteract the increases. Creating a trough with wattles or other material can convey clean water away from these areas. l To prevent undercutting, trench and backfill rolled plastic covering products. l Although the plastic material is inexpensive to purchase, the cost of installation, maintenance, removal, and disposal add to the total costs of this BMP. l Whenever plastic is used to protect slopes, install water collection measures at the base of the slope. These measures include plastic-covered berms, channels, and pipes used to convey clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a plastic covered slope with dirty runoff from a project. l Other uses for plastic include: o Temporary ditch liner. o Pond liner in temporary sediment pond. o Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored. o Emergency slope protection during heavy rains. o Temporary drainpipe (“elephant trunk”) used to direct water. Design and Installation Specifications l Plastic slope cover must be installed as follows: 1. Run plastic up and down the slope, not across the slope. 2. Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 298 3. Provide a minimum of 8-inch overlap at the seams. 4. On long or wide slopes, or slopes subject to wind, tape all seams. 5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath. 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and tie them together with twine to hold them in place. 7. Inspect plastic for rips, tears, and open seams regularly and repair immediately. This prevents high velocity runoff from contacting bare soil, which causes extreme erosion. 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. l Plastic sheeting shall have a minimum thickness of 0.06 millimeters. l If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. Maintenance Standards l Torn sheets must be replaced and open seams repaired. l Completely remove and replace the plastic if it begins to deteriorate due to ultraviolet radi- ation. l Completely remove plastic when no longer needed. l Dispose of old tires used to weight down plastic sheeting appropriately. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology’s website at: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies BMP C124: Sodding Purpose The purpose of sodding is to establish turf for immediate erosion protection and to stabilize drainage paths where concentrated overland flow will occur. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 299 BMP C140: Dust Control Purpose Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, drainage ways, and surface waters. Conditions of Use Use dust control in areas (including roadways) subject to surface and air movement of dust where on-site or off-site impacts to roadways, drainage ways, or surface waters are likely. Design and Installation Specifications l Vegetate or mulch areas that will not receive vehicle traffic. In areas where planting, mulching, or paving is impractical, apply gravel or landscaping rock. l Limit dust generation by clearing only those areas where immediate activity will take place, leaving the remaining area(s) in the original condition. Maintain the original ground cover as long as practical. l Construct natural or artificial windbreaks or windscreens. These may be designed as enclos- ures for small dust sources. l Sprinkle the site with water until the surface is wet. Repeat as needed. To prevent carryout of mud onto the street, refer to BMP C105: Stabilized Construction Access and BMP C106: Wheel Wash. l Irrigation water can be used for dust control. Irrigation systems should be installed as a first step on sites where dust control is a concern. l Spray exposed soil areas with a dust palliative, following the manufacturer’s instructions and cautions regarding handling and application. Used oil is prohibited from use as a dust sup- pressant. Local governments may approve other dust palliatives such as calcium chloride or PAM. l PAM (BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection) added to water at a rate of 0.5 pounds per 1,000 gallons of water per acre and applied from a water truck is more effect- ive than water alone. This is due to increased infiltration of water into the soil and reduced evaporation. In addition, small soil particles are bonded together and are not as easily trans- ported by wind. Adding PAM may reduce the quantity of water needed for dust control. Note that the application rate specified here applies to this BMP, and is not the same application rate that is specified in BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection, but the downstream protections still apply. Refer to BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection for conditions of use. PAM shall not be directly applied to water or allowed to enter a water body. l Contact your local Air Pollution Control Authority for guidance and training on other dust con- trol measures. Compliance with the local Air Pollution Control Authority constitutes 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 313 compliance with this BMP. l Use vacuum street sweepers. l Remove mud and other dirt promptly so it does not dry and then turn into dust. l Techniques that can be used for unpaved roads and lots include: o Lower speed limits. High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. o Upgrade the road surface strength by improving particle size, shape, and mineral types that make up the surface and base materials. o Add surface gravel to reduce the source of dust emission. Limit the amount of fine particles (those smaller than .075 mm) to 10 to 20 percent. o Use geotextile fabrics to increase the strength of new roads or roads undergoing recon- struction. o Encourage the use of alternate, paved routes, if available. o Apply chemical dust suppressants using the admix method, blending the product with the top few inches of surface material. Suppressants may also be applied as surface treatments. o Limit dust-causing work on windy days. o Pave unpaved permanent roads and other trafficked areas. Maintenance Standards Respray area as necessary to keep dust to a minimum. BMP C150: Materials on Hand Purpose Keep quantities of erosion prevention and sediment control materials on the project site at all times to be used for regular maintenance and emergency situations such as unexpected heavy rains. Hav- ing these materials on-site reduces the time needed to replace existing or implement new BMPs when inspections indicate that existing BMPs are not meeting the Construction SWPPP require- ments. In addition, contractors can save money by buying some materials in bulk and storing them at their office or yard. Conditions of Use l Construction projects of any size or type can benefit from having materials on hand. A small commercial development project could have a roll of plastic and some gravel available for immediate protection of bare soil and temporary berm construction. A large earthwork project, such as highway construction, might have several tons of straw, several rolls of plastic, flexible 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 314 pipe, sandbags, geotextile fabric and steel “T” posts. l Materials should be stockpiled and readily available before any site clearing, grubbing, or earthwork begins. A large contractor or project proponent could keep a stockpile of materials that are available for use on several projects. l If storage space at the project site is at a premium, the contractor could maintain the materials at their office or yard. The office or yard must be less than an hour from the project site. Design and Installation Specifications Depending on project type, size, complexity, and length, materials and quantities will vary. A good minimum list of items that will cover numerous situations includes: l Clear Plastic, 6 mil l Drainpipe, 6 or 8 inch diameter l Sandbags, filled l Straw Bales for mulching l Quarry Spalls l Washed Gravel l Geotextile Fabric l Catch Basin Inserts l Steel "T" Posts l Silt fence material l Straw Wattles Maintenance Standards l All materials with the exception of the quarry spalls, steel “T” posts, and gravel should be kept covered and out of both sun and rain. l Re-stock materials as needed. BMP C151: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. Concrete spillage or concrete dis- charge to waters of the State is prohibited. Use this BMP to minimize and eliminate concrete, con- crete process water, and concrete slurry from entering waters of the State. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 315 Conditions of Use Any time concrete is used, utilize these management practices. Concrete construction project com- ponents include, but are not limited to: l Curbs l Sidewalks l Roads l Bridges l Foundations l Floors l Runways Disposal options for concrete, in order of preference are: 1. Off-site disposal 2. Concrete wash-out areas (see BMP C154: Concrete Washout Area) 3. De minimus washout to formed areas awaiting concrete Design and Installation Specifications l Wash concrete truck drums at an approved off-site location or in designated concrete washout areas only. Do not wash out concrete trucks onto the ground (including formed areas awaiting concrete), or into storm drains, open ditches, streets, or streams. Refer to BMP C154: Concrete Washout Area for information on concrete washout areas. o Return unused concrete remaining in the truck and pump to the originating batch plant for recycling. Do not dump excess concrete on site, except in designated concrete washout areas as allowed in BMP C154: Concrete Washout Area. l Wash small concrete handling equipment (e.g. hand tools, screeds, shovels, rakes, floats, trowels, and wheelbarrows) into designated concrete washout areas or into formed areas awaiting concrete pour. l At no time shall concrete be washed off into the footprint of an area where an infiltration fea- ture will be installed. l Wash equipment difficult to move, such as concrete paving machines, in areas that do not dir- ectly drain to natural or constructed stormwater conveyance or potential infiltration areas. l Do not allow washwater from areas, such as concrete aggregate driveways, to drain directly (without detention or treatment) to natural or constructed stormwater conveyances. l Contain washwater and leftover product in a lined container when no designated concrete washout areas (or formed areas, allowed as described above) are available. Dispose of con- tained concrete and concrete washwater (process water) properly. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 316 l Always use forms or solid barriers for concrete pours, such as pilings, within 15-feet of surface waters. l Refer to BMP C252: Treating and Disposing of High pH Water for pH adjustment require- ments. l Refer to the Construction Stormwater General Permit (CSWGP) for pH monitoring require- ments if the project involves one of the following activities: o Significant concrete work (as defined in the CSWGP). o The use of soils amended with (but not limited to) Portland cement-treated base, cement kiln dust or fly ash. o Discharging stormwater to segments of water bodies on the 303(d) list (Category 5) for high pH. Maintenance Standards Check containers for holes in the liner daily during concrete pours and repair the same day. BMP C152: Sawcutting and Surfacing Pollution Prevention Purpose Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting), both of which can violate the water quality standards in the receiving water. Concrete spillage or concrete discharge to waters of the State is prohibited. Use this BMP to minimize and eliminate process water and slurry created through sawcutting or surfacing from enter- ing waters of the State. Conditions of Use Utilize these management practices anytime sawcutting or surfacing operations take place. Saw- cutting and surfacing operations include, but are not limited to: l Sawing l Coring l Grinding l Roughening l Hydro-demolition l Bridge and road surfacing 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 317 Design and Installation Specifications l Vacuum slurry and cuttings during cutting and surfacing operations. l Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight. l Slurry and cuttings shall not drain to any natural or constructed drainage conveyance includ- ing stormwater systems. This may require temporarily blocking catch basins. l Dispose of collected slurry and cuttings in a manner that does not violate ground water or sur- face water quality standards. l Do not allow process water generated during hydro-demolition, surface roughening or similar operations to drain to any natural or constructed drainage conveyance including stormwater systems. Dispose of process water in a manner that does not violate ground water or surface water quality standards. l Handle and dispose of cleaning waste material and demolition debris in a manner that does not cause contamination of water. Dispose of sweeping material from a pick-up sweeper at an appropriate disposal site. Maintenance Standards Continually monitor operations to determine whether slurry, cuttings, or process water could enter waters of the state. If inspections show that a violation of water quality standards could occur, stop operations and immediately implement preventive measures such as berms, barriers, secondary containment, and/or vacuum trucks. BMP C153: Material Delivery, Storage, and Containment Purpose Prevent, reduce, or eliminate the discharge of pollutants to the stormwater system or watercourses from material delivery and storage. Minimize the storage of hazardous materials on-site, store mater- ials in a designated area, and install secondary containment. Conditions of Use Use at construction sites with delivery and storage of the following materials: l Petroleum products such as fuel, oil and grease l Soil stabilizers and binders (e.g., Polyacrylamide) l Fertilizers, pesticides and herbicides l Detergents l Asphalt and concrete compounds 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 318 l Hazardous chemicals such as acids, lime, adhesives, paints, solvents, and curing compounds l Any other material that may be detrimental if released to the environment Design and Installation Specifications l The temporary storage area should be located away from vehicular traffic, near the con- struction entrance(s), and away from waterways or storm drains. l Safety Data Sheets (SDS) should be supplied for all materials stored. Chemicals should be kept in their original labeled containers. l Hazardous material storage on-site should be minimized. l Hazardous materials should be handled as infrequently as possible. l During the wet weather season (Oct 1 – April 30), consider storing materials in a covered area. l Materials should be stored in secondary containments, such as an earthen dike, horse trough, or even a children’s wading pool for non-reactive materials such as detergents, oil, grease, and paints. Small amounts of material may be secondarily contained in “bus boy” trays or con- crete mixing trays. l Do not store chemicals, drums, or bagged materials directly on the ground. Place these items on a pallet and, when possible, within secondary containment. l If drums must be kept uncovered, store them at a slight angle to reduce ponding of rainwater on the lids to reduce corrosion. Domed plastic covers are inexpensive and snap to the top of drums, preventing water from collecting. l Liquids, petroleum products, and substances listed in 40 CFR Parts 110, 117, or 302 shall be stored in approved containers and drums and shall not be overfilled. Containers and drums shall be stored in temporary secondary containment facilities. l Temporary secondary containment facilities shall provide for a spill containment volume able to contain 10% of the total enclosed container volume of all containers, or 110% of the capa- city of the largest container within its boundary, whichever is greater. l Secondary containment facilities shall be impervious to the materials stored therein for a min- imum contact time of 72 hours. l Sufficient separation should be provided between stored containers to allow for spill cleanup and emergency response access. l During the wet weather season (Oct 1 – April 30), each secondary containment facility shall be covered during non-working days, prior to and during rain events. l Keep material storage areas clean, organized and equipped with an ample supply of appro- priate spill clean-up material (spill kit). l The spill kit should include, at a minimum: 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 319 o 1-Water Resistant Nylon Bag o 3-Oil Absorbent Socks 3”x 4’ o 2-Oil Absorbent Socks 3”x 10’ o 12-Oil Absorbent Pads 17”x19” o 1-Pair Splash Resistant Goggles o 3-Pair Nitrile Gloves o 10-Disposable Bags with Ties o Instructions Maintenance Standards l Secondary containment facilities shall be maintained free of accumulated rainwater and spills. In the event of spills or leaks, accumulated rainwater and spills shall be collected and placed into drums. These liquids shall be handled as hazardous waste unless testing determines them to be non-hazardous. l Re-stock spill kit materials as needed. BMP C154: Concrete Washout Area Purpose Prevent or reduce the discharge of pollutants from concrete waste to stormwater by conducting washout off-site, or performing on-site washout in a designated area. Conditions of Use Concrete washout areas are implemented on construction projects where: l Concrete is used as a construction material l It is not possible to dispose of all concrete wastewater and washout off-site (ready mix plant, etc.). l Concrete truck drums are washed on-site. Note that auxiliary concrete truck components (e.g. chutes and hoses) and small concrete handling equipment (e.g. hand tools, screeds, shovels, rakes, floats, trowels, and wheel- barrows) may be washed into formed areas awaiting concrete pour. At no time shall concrete be washed off into the footprint of an area where an infiltration feature will be installed. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 320 Design and Installation Specifications Implementation l Perform washout of concrete truck drums at an approved off-site location or in designated con- crete washout areas only. l Do not wash out concrete onto non-formed areas, or into storm drains, open ditches, streets, or streams. l Wash equipment difficult to move, such as concrete paving machines, in areas that do not dir- ectly drain to natural or constructed stormwater conveyance or potential infiltration areas. l Do not allow excess concrete to be dumped on-site, except in designated concrete washout areas as allowed above. l Concrete washout areas may be prefabricated concrete washout containers, or self-installed structures (above-grade or below-grade). l Prefabricated containers are most resistant to damage and protect against spills and leaks. Companies may offer delivery service and provide regular maintenance and disposal of solid and liquid waste. l If self-installed concrete washout areas are used, below-grade structures are preferred over above-grade structures because they are less prone to spills and leaks. l Self-installed above-grade structures should only be used if excavation is not practical. l Concrete washout areas shall be constructed and maintained in sufficient quantity and size to contain all liquid and concrete waste generated by washout operations. Education l Discuss the concrete management techniques described in this BMP with the ready-mix con- crete supplier before any deliveries are made. l Educate employees and subcontractors on the concrete waste management techniques described in this BMP. l Arrange for the contractor’s superintendent or Certified Erosion and Sediment Control Lead (CESCL) to oversee and enforce concrete waste management procedures. l A sign should be installed adjacent to each concrete washout area to inform concrete equip- ment operators to utilize the proper facilities. Contracts Incorporate requirements for concrete waste management into concrete supplier and subcontractor agreements. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 321 Location and Placement l Locate concrete washout areas at least 50 feet from sensitive areas such as storm drains, open ditches, water bodies, or wetlands. l Allow convenient access to the concrete washout area for concrete trucks, preferably near the area where the concrete is being poured. l If trucks need to leave a paved area to access the concrete washout area, prevent track-out with a pad of rock or quarry spalls (see BMP C105: Stabilized Construction Access). These areas should be far enough away from other construction traffic to reduce the likelihood of acci- dental damage and spills. l The number of concrete washout areas you install should depend on the expected demand for storage capacity. l On large sites with extensive concrete work, concrete washout areas should be placed in mul- tiple locations for ease of use by concrete truck drivers. Concrete Truck Washout Procedures l Washout of concrete truck drums shall be performed in designated concrete washout areas only. l Concrete washout from concrete pumper bins can be washed into concrete pumper trucks and discharged into designated concrete washout areas or properly disposed of off-site. Concrete Washout Area Installation l Concrete washout areas should be constructed as shown in the figures below, with a recom- mended minimum length and minimum width of 10 ft, but with sufficient quantity and volume to contain all liquid and concrete waste generated by washout operations. l Plastic lining material should be a minimum of 10 mil polyethylene sheeting and should be free of holes, tears, or other defects that compromise the impermeability of the material. l Lath and flagging should be commercial type. l Liner seams shall be installed in accordance with manufacturers’ recommendations. l Soil base shall be prepared free of rocks or other debris that may cause tears or holes in the plastic lining material. Maintenance Standards Inspection and Maintenance l Inspect and verify that concrete washout areas are in place prior to the commencement of con- crete work. l Once concrete wastes are washed into the designated washout area and allowed to harden, 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 322 the concrete should be broken up, removed, and disposed of per applicable solid waste reg- ulations. Dispose of hardened concrete on a regular basis. l During periods of concrete work, inspect the concrete washout areas daily to verify continued performance. o Check overall condition and performance. o Check remaining capacity (% full). o If using self-installed concrete washout areas, verify plastic liners are intact and side- walls are not damaged. o If using prefabricated containers, check for leaks. l Maintain the concrete washout areas to provide adequate holding capacity with a minimum freeboard of 12 inches. l Concrete washout areas must be cleaned, or new concrete washout areas must be con- structed and ready for use once the concrete washout area is 75% full. l If the concrete washout area is nearing capacity, vacuum and dispose of the waste material in an approved manner. l Do not discharge liquid or slurry to waterways, storm drains or directly onto ground. l Do not discharge to the sanitary sewer without local approval. l Place a secure, non-collapsing, non-water collecting cover over the concrete washout area prior to predicted wet weather to prevent accumulation and overflow of pre- cipitation. l Remove and dispose of hardened concrete and return the structure to a functional con- dition. Concrete may be reused on-site or hauled away for disposal or recycling. l When you remove materials from a self-installed concrete washout area, build a new struc- ture; or, if the previous structure is still intact, inspect for signs of weakening or damage, and make any necessary repairs. Re-line the structure with new plastic after each cleaning. Removal of Concrete Washout Areas l When concrete washout areas are no longer required for the work, the hardened concrete, slurries and liquids shall be removed and properly disposed of. l Materials used to construct concrete washout areas shall be removed from the site of the work and disposed of or recycled. l Holes, depressions or other ground disturbance caused by the removal of the concrete washout areas shall be backfilled, repaired, and stabilized to prevent erosion. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 323 Figure II-3.7: Concrete Washout Area with Wood Planks 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 324 3m Minimum -e- -e-Lath and flagging on 3 sides Sandbag0□ CD □ '>TI SandbagBermc> 10 mil plastic lining□Varies A iAf 'Xo-o-1 m •x Q —I Berm 10 CD CD Section A-A6 10 mil plastic liningPlan Notes: 1.Actual layout determined in the field. A concrete washout sign shall be installed within 10 m of the temporary concrete washout facility. Type "Below Grade ii 2. 3m Minimum JSL JHL T8T Wood frame securely fastened around entire perimeter with two stakes B BtI■s-a ■s-a Varies 10 mil plastic lining S 3 E VStake (typ.) M Section B-Bw 10 mil plastic lining Two-stacked 2x12 rough wood frame Plan Type "Above Grade" with Wood Planks NOT TO SCALE Concrete Washout Area with Wood Planks Revised June 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Figure II-3.8: Concrete Washout Area with Straw Bales 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 325 Straw bale 10 mil plastic lining Binding wire Staples (2 per bale)Native material (optional) Wood or metal stakes (2 per bale) Plywood 1200 mm x 610 mm painted white Wood post (89 mm x 89 mm x 2.4 m)Lag screws (12.5 mm)Section B-B Black letters 150 mm heightILCONCRETE WASHOUT' U915 mm f 915 mm T3m Minimum Concrete Washout Sign Detail (or equivalent)Stake (typ)A B Bt1 i 50 mm 3.05 mm dia. steel wire Varies 200 mm f Staple Detail 10 mil plastic lining Notes:Straw bale (typ)1. Actual layout determined in the field. The concrete washout sign shall be installed within 10 m of the temporary concrete washout facility. Plan 2. Type "Above Grade" with Straw Bales NOT TO SCALE Concrete Washout Area with Straw Bales Revised June 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Figure II-3.9: Prefabricated Concrete Washout Container w/Ramp 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 326 ■•-0 \riy l-j X - NOT TO SCALE Prefabricated Concrete Washout Container w/Ramp Revised June 2016DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyright.htmMor copyright notice including permissions, limitation of liability, and disclaimer.State of Washington BMP C160: Certified Erosion and Sediment Control Lead Purpose The project proponent designates at least one person as the responsible representative in charge of erosion and sediment control (ESC), and water quality protection. The designated person shall be responsible for ensuring compliance with all local, state, and federal erosion and sediment control and water quality requirements. Construction sites one acre or larger that discharge to waters of the State must designate a Certified Erosion and Sediment Control Lead (CESCL) as the responsible representative. Conditions of Use A CESCL shall be made available on projects one acre or larger that discharge stormwater to sur- face waters of the state. Sites less than one acre may have a person without CESCL certification conduct inspections. The CESCL shall: l Have a current certificate proving attendance in an erosion and sediment control training course that meets the minimum ESC training and certification requirements established by Ecology. Ecology has provided the minimum requirements for CESCL course training, as well as a list of ESC training and certification providers at: https://ecology.wa.gov/Regulations-Permits/Permits-certifications/Certified-erosion-sed- iment-control OR l Be a Certified Professional in Erosion and Sediment Control (CPESC). For additional inform- ation go to: http://www.envirocertintl.org/cpesc/ Specifications l CESCL certification shall remain valid for three years. l The CESCL shall have authority to act on behalf of the contractor or project proponent and shall be available, or on-call, 24 hours per day throughout the period of construction. l The Construction SWPPP shall include the name, telephone number, fax number, and address of the designated CESCL. See II-2 Construction Stormwater Pollution Prevention Plans (Construction SWPPPs). l A CESCL may provide inspection and compliance services for multiple construction projects in the same geographic region, but must be on site whenever earthwork activities are 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 327 occurring that could generate release of turbid water. l Duties and responsibilities of the CESCL shall include, but are not limited to the following: o Maintaining a permit file on site at all times which includes the Construction SWPPP and any associated permits and plans. o Directing BMP installation, inspection, maintenance, modification, and removal. o Updating all project drawings and the Construction SWPPP with changes made. o Completing any sampling requirements including reporting results using electronic Dis- charge Monitoring Reports (WebDMR). o Facilitate, participate in, and take corrective actions resulting from inspections per- formed by outside agencies or the owner. o Keeping daily logs, and inspection reports. Inspection reports should include: n Inspection date/time. n Weather information; general conditions during inspection and approximate amount of precipitation since the last inspection. n Visual monitoring results, including a description of discharged stormwater. The presence of suspended sediment, turbid water, discoloration, and oil sheen shall be noted, as applicable. n Any water quality monitoring performed during inspection. n General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. n A summary or list of all BMPs implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted: 1. Locations of BMPs inspected. 2. Locations of BMPs that need maintenance. 3. Locations of BMPs that failed to operate as designed or intended. 4. Locations of where additional or different BMPs are required. BMP C162: Scheduling Purpose Sequencing a construction project reduces the amount and duration of soil exposed to erosion by wind, rain, runoff, and vehicle tracking. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 328 Conditions of Use The construction sequence schedule is an orderly listing of all major land-disturbing activities together with the necessary erosion and sedimentation control measures planned for the project. This type of schedule guides the contractor on work to be done before other work is started so that serious erosion and sedimentation problems can be avoided. Following a specified work schedule that coordinates the timing of land-disturbing activities and the installation of control measures is perhaps the most cost-effective way of controlling erosion during construction. The removal of ground cover leaves a site vulnerable to erosion. Construction sequen- cing that limits land clearing, provides timely installation of erosion and sedimentation controls, and restores protective cover quickly can significantly reduce the erosion potential of a site. Design Considerations l Minimize construction during rainy periods. l Schedule projects to disturb only small portions of the site at any one time. Complete grading as soon as possible. Immediately stabilize the disturbed portion before grading the next por- tion. Practice staged seeding in order to revegetate cut and fill slopes as the work progresses. II-3.3 Construction Runoff BMPs BMP C200: Interceptor Dike and Swale Purpose Provide a dike of compacted soil or a swale at the top or base of a disturbed slope or along the peri- meter of a disturbed construction area to convey stormwater. Use the dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment-laden runoff from leaving the con- struction site. Conditions of Use Use an interceptor dike or swale where runoff from an exposed site or disturbed slope must be con- veyed to an erosion control BMP which can safely convey the stormwater. l Locate upslope of a construction site to prevent runoff from entering the disturbed area. l When placed horizontally across a disturbed slope, it reduces the amount and velocity of run- off flowing down the slope. l Locate downslope to collect runoff from a disturbed area and direct it to a sediment BMP (e.g. BMP C240: Sediment Trap or BMP C241: Sediment Pond (Temporary)). 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 329 Conditions of Use The construction sequence schedule is an orderly listing of all major land-disturbing activities together with the necessary erosion and sedimentation control measures planned for the project. This type of schedule guides the contractor on work to be done before other work is started so that serious erosion and sedimentation problems can be avoided. Following a specified work schedule that coordinates the timing of land-disturbing activities and the installation of control measures is perhaps the most cost-effective way of controlling erosion during construction. The removal of ground cover leaves a site vulnerable to erosion. Construction sequen- cing that limits land clearing, provides timely installation of erosion and sedimentation controls, and restores protective cover quickly can significantly reduce the erosion potential of a site. Design Considerations l Minimize construction during rainy periods. l Schedule projects to disturb only small portions of the site at any one time. Complete grading as soon as possible. Immediately stabilize the disturbed portion before grading the next por- tion. Practice staged seeding in order to revegetate cut and fill slopes as the work progresses. II-3.3 Construction Runoff BMPs BMP C200: Interceptor Dike and Swale Purpose Provide a dike of compacted soil or a swale at the top or base of a disturbed slope or along the peri- meter of a disturbed construction area to convey stormwater. Use the dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment-laden runoff from leaving the con- struction site. Conditions of Use Use an interceptor dike or swale where runoff from an exposed site or disturbed slope must be con- veyed to an erosion control BMP which can safely convey the stormwater. l Locate upslope of a construction site to prevent runoff from entering the disturbed area. l When placed horizontally across a disturbed slope, it reduces the amount and velocity of run- off flowing down the slope. l Locate downslope to collect runoff from a disturbed area and direct it to a sediment BMP (e.g. BMP C240: Sediment Trap or BMP C241: Sediment Pond (Temporary)). 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 329 Design and Installation Specifications l Dike and/or swale and channel must be stabilized with temporary or permanent vegetation or other channel protection during construction. l Steep grades require channel protection and check dams. l Review construction for areas where overtopping may occur. l Can be used at the top of new fill before vegetation is established. l May be used as a permanent diversion channel to carry the runoff. l Contributing area for an individual dike or swale should be one acre or less. l Design the dike and/or swale to contain flows calculated by one of the following methods: o Single Event Hydrograph Method: The peak volumetric flow rate calculated using a 10- minute time step from a Type 1A, 10-year, 24-hour frequency storm for the worst-case land cover condition. OR o Continuous Simulation Method: The 10-year peak flow rate, as determined by an approved continuous runoff model with a 15-minute time step for the worst-case land cover condition. Worst-case land cover conditions (i.e., producing the most runoff) should be used for analysis (in most cases, this would be the land cover conditions just prior to final landscaping). Interceptor Dikes Interceptor dikes shall meet the following criteria: l Top Width: 2 feet minimum. l Height: 1.5 feet minimum on berm. l Side Slope: 2H:1V or flatter. l Grade: Depends on topography, however, dike system minimum is 0.5%, and maximum is 1%. l Compaction: Minimum of 90 percent ASTM D698 standard proctor. l Stabilization: Depends on velocity and reach. Inspect regularly to ensure stability. l Ground Slopes <5%: Seed and mulch applied within 5 days of dike construction (see BMP C121: Mulching). l Ground Slopes 5 - 40%: Dependent on runoff velocities and dike materials. Stabilization should be done immediately using either sod or riprap, or other measures to avoid erosion. l The upslope side of the dike shall provide positive drainage to the dike outlet. No erosion shall 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 330 occur at the outlet. Provide energy dissipation measures as necessary. Sediment-laden runoff must be released through a sediment trapping facility. l Minimize construction traffic over temporary dikes. Use temporary cross culverts for channel crossing. l See Table II-3.8: Horizontal Spacing of Interceptor Dikes Along Ground Slope for recom- mended horizontal spacing between dikes. Average Slope Slope Percent Flowpath Length 20H:1V or less 3-5%300 feet (10 to 20)H:1V 5-10%200 feet (4 to 10)H:1V 10-25%100 feet (2 to 4)H:1V 25-50%50 feet Table II-3.8: Horizontal Spacing of Interceptor Dikes Along Ground Slope Interceptor Swales Interceptor swales shall meet the following criteria: l Bottom Width: 2 feet minimum; the cross-section bottom shall be level. l Depth: 1-foot minimum. l Side Slope: 2H:1V or flatter. l Grade: Maximum 5 percent, with positive drainage to a suitable outlet (such as BMP C241: Sediment Pond (Temporary)). l Stabilization: Seed as per BMP C120: Temporary and Permanent Seeding, or BMP C202: Riprap Channel Lining, 12 inches thick riprap pressed into the bank and extending at least 8 inches vertical from the bottom. Maintenance Standards l Inspect diversion dikes and interceptor swales once a week and after every rainfall. Imme- diately remove sediment from the flow area. l Damage caused by construction traffic or other activity must be repaired before the end of each working day. l Check outlets and make timely repairs as needed to avoid gully formation. When the area below the temporary diversion dike is permanently stabilized, remove the dike and fill and sta- bilize the channel to blend with the natural surface. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 331 thickness is 2 feet. o For outlets at the base of steep slope pipes (pipe slope greater than 10 percent), use an engineered energy dissipator. o Filter fabric or erosion control blankets should always be used under riprap to prevent scour and channel erosion. See BMP C122: Nets and Blankets. l Bank stabilization, bioengineering, and habitat features may be required for disturbed areas. This work may require a Hydraulic Project Approval (HPA) from the Washington State Depart- ment of Fish and Wildlife. See I-2.11 Hydraulic Project Approvals. Maintenance Standards l Inspect and repair as needed. l Add rock as needed to maintain the intended function. l Clean energy dissipator if sediment builds up. BMP C220: Inlet Protection Purpose Inlet protection prevents coarse sediment from entering drainage systems prior to permanent sta- bilization of the disturbed area. Conditions of Use Use inlet protection at inlets that are operational before permanent stabilization of the disturbed areas that contribute runoff to the inlet. Provide protection for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless those inlets are preceded by a sediment trapping BMP. Also consider inlet protection for lawn and yard drains on new home construction. These small and numerous drains coupled with lack of gutters can add significant amounts of sediment into the roof drain system. If possible, delay installing lawn and yard drains until just before landscaping, or cap these drains to prevent sediment from entering the system until completion of landscaping. Provide 18-inches of sod around each finished lawn and yard drain. Table II-3.10: Storm Drain Inlet Protection lists several options for inlet protection. All of the methods for inlet protection tend to plug and require a high frequency of maintenance. Limit contributing drain- age areas for an individual inlet to one acre or less. If possible, provide emergency overflows with additional end-of-pipe treatment where stormwater ponding would cause a hazard. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 356 Type of Inlet Pro- tection Emergency Overflow Applicable for Paved/ Earthen Sur- faces Conditions of Use Drop Inlet Protection Excavated drop inlet protection Yes, temporary flooding may occur Earthen Applicable for heavy flows. Easy to maintain. Large area requirement: 30'x30'/acre Block and gravel drop inlet pro- tection Yes Paved or Earthen Applicable for heavy concentrated flows. Will not pond. Gravel and wire drop inlet pro- tection No Paved or Earthen Applicable for heavy concentrated flows. Will pond. Can withstand traffic. Catch basin filters Yes Paved or Earthen Frequent maintenance required. Curb Inlet Protection Curb inlet pro- tection with wooden weir Small capacity overflow Paved Used for sturdy, more compact install- ation. Block and gravel curb inlet pro- tection Yes Paved Sturdy, but limited filtration. Culvert Inlet Protection Culvert inlet sed- iment trap N/A N/A 18 month expected life. Table II-3.10: Storm Drain Inlet Protection Design and Installation Specifications Excavated Drop Inlet Protection Excavated drop inlet protection consists of an excavated impoundment around the storm drain inlet. Sediment settles out of the stormwater prior to entering the storm drain. Design and installation spe- cifications for excavated drop inlet protection include: l Provide a depth of 1-2 ft as measured from the crest of the inlet structure. l Slope sides of excavation should be no steeper than 2H:1V. l Minimum volume of excavation is 35 cubic yards. l Shape the excavation to fit the site, with the longest dimension oriented toward the longest inflow area. l Install provisions for draining to prevent standing water. l Clear the area of all debris. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 357 l Grade the approach to the inlet uniformly. l Drill weep holes into the side of the inlet. l Protect weep holes with screen wire and washed aggregate. l Seal weep holes when removing structure and stabilizing area. l Build a temporary dike, if necessary, to the down slope side of the structure to prevent bypass flow. Block and Gravel Filter A block and gravel filter is a barrier formed around the inlet with standard concrete blocks and gravel. See Figure II-3.17: Block and Gravel Filter. Design and installation specifications for block gravel fil- ters include: l Provide a height of 1 to 2 feet above the inlet. l Recess the first row of blocks 2-inches into the ground for stability. l Support subsequent courses by placing a pressure treated wood 2x4 through the block open- ing. l Do not use mortar. l Lay some blocks in the bottom row on their side to allow for dewatering the pool. l Place hardware cloth or comparable wire mesh with ½-inch openings over all block openings. l Place gravel to just below the top of blocks on slopes of 2H:1V or flatter. l An alternative design is a gravel berm surrounding the inlet, as follows: o Provide a slope of 3H:1V on the upstream side of the berm. o Provide a slope of 2H:1V on the downstream side of the berm. o Provide a 1-foot wide level stone area between the gravel berm and the inlet. o Use stones 3 inches in diameter or larger on the upstream slope of the berm. o Use gravel ½- to ¾-inch at a minimum thickness of 1-foot on the downstream slope of the berm. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 358 Figure II-3.17: Block and Gravel Filter 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 359 A Drain grate r>Aft> QS, SSL ogjfe Q. ~ _ ?rygioSOso^cy.;Concrete block Sfei A* o• o>cr> °i?o ^•Pa- ■sPc^I? 4 STTO <&', Gravel backfill■osVf\ A-°i ° _?o “■'frvSPP^ •§?° to. gdp> §0-^<S> q® v«r.^4y A Plan View Concrete block Wire screen or filter fabric Overflow water Gravel backfill Ponding height |5»S Water'^n iplllpfls^Drop inlet Section A-A Notes: 1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas, (less than 5%) 2. Excavate a basin of sufficient size adjacent to the drop inlet. 3. The top of the structure (ponding height) must be well below the ground elevation downslope to prevent runoff from bypassing the inlet. A temporary dike may be necessary on the downslope side of the structure. NOT TO SCALE Block and Gravel Filter Revised June 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Gravel and Wire Mesh Filter Gravel and wire mesh filters are gravel barriers placed over the top of the inlet. This method does not provide an overflow. Design and installation specifications for gravel and wire mesh filters include: l Use a hardware cloth or comparable wire mesh with ½-inch openings. o Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot bey- ond each side of the inlet structure. o Overlap the strips if more than one strip of mesh is necessary. l Place coarse aggregate over the wire mesh. o Provide at least a 12-inch depth of aggregate over the entire inlet opening and extend at least 18-inches on all sides. Catch Basin Filters Catch basin filters are designed by manufacturers for construction sites. The limited sediment stor- age capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. To reduce maintenance requirements, combine a catch basin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights-of-way. Design and install- ation specifications for catch basin filters include: l Provides 5 cubic feet of storage. l Requires dewatering provisions. l Provides a high-flow bypass that will not clog under normal use at a construction site. l Insert the catch basin filter in the catch basin just below the grating. Curb Inlet Protection with Wooden Weir Curb inlet protection with wooden weir is an option that consists of a barrier formed around a curb inlet with a wooden frame and gravel. Design and installation specifications for curb inlet protection with wooden weirs include: l Use wire mesh with ½-inch openings. l Use extra strength filter cloth. l Construct a frame. l Attach the wire and filter fabric to the frame. l Pile coarse washed aggregate against the wire and fabric. l Place weight on the frame anchors. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 360 Block and Gravel Curb Inlet Protection Block and gravel curb inlet protection is a barrier formed around a curb inlet with concrete blocks and gravel. See Figure II-3.18: Block and Gravel Curb Inlet Protection. Design and installation spe- cifications for block and gravel curb inlet protection include: l Use wire mesh with ½-inch openings. l Place two concrete blocks on their sides abutting the curb at either side of the inlet opening. These are spacer blocks. l Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. l Place blocks on their sides across the front of the inlet and abutting the spacer blocks. l Place wire mesh over the outside vertical face. l Pile coarse aggregate against the wire to the top of the barrier. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 361 Figure II-3.18: Block and Gravel Curb Inlet Protection 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 362 A Catch basin Back of sidewalk 2x4 Wood stud Curb inletBack of curb Concrete block pt < 1'[ ]o a & Wire screen or filter fabric 3c§ i?$C5 3Ko..om,o jOjsQi 0»Wm JS SS A Concrete block% inch (20 mm) Drain gravel Plan View Ponding height % inch (20 mm) Drain gravel Overflow w I□Curb inlet Wire screen or filter fabric r2x4 Wood stud (100x50 Timber stud)/iCatch basin Concrete block Section A-A Notes: 1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shall allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately.NOT TO SCALE Block and Gravel Curb Inlet Protection Revised June 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Curb and Gutter Sediment Barrier Curb and gutter sediment barrier is a sandbag or rock berm (riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure II-3.19: Curb and Gutter Barrier. Design and installation specifications for curb and gutter sediment barrier include: l Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. l Construct a horseshoe shaped sedimentation trap on the upstream side of the berm. Size the trap to sediment trap standards for protecting a culvert inlet. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 363 Figure II-3.19: Curb and Gutter Barrier 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 364 Back of sidewalk Burlap sacks to overlap onto curb Back of curb Curb inletRunoff SpillwayRunoff Catch basin Plan View Gravel filled sandbags stacked tightly Notes: 1. Place curb type sediment barriers on gently sloping street segments, where water can pond and allow sediment to separate from runoff. 2. Sandbags of either burlap or woven 'geotextile' fabric, are filled with gravel, layered and packed tightly. 3. Leave a one sandbag gap in the top row to provide a spillway for overflow. 4. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately.NOT TO SCALE Curb and Gutter Barrier Revised June 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Maintenance Standards l Inspect all forms of inlet protection frequently, especially after storm events. Clean and replace clogged catch basin filters. For rock and gravel filters, pull away the rocks from the inlet and clean or replace. An alternative approach would be to use the clogged rock as fill and put fresh rock around the inlet. l Do not wash sediment into storm drains while cleaning. Spread all excavated material evenly over the surrounding land area or stockpile and stabilize as appropriate. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology’s website at: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies BMP C231: Brush Barrier Purpose The purpose of brush barriers is to reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use l Brush barriers may be used downslope of disturbed areas that are less than one-quarter acre. l Brush barriers are not intended to treat concentrated flows, nor are they intended to treat sub- stantial amounts of overland flow. Any concentrated flows must be directed to a sediment trap- ping BMP. The only circumstance in which overland flow can be treated solely by a brush barrier, rather than by a sediment trapping BMP, is when the area draining to the barrier is small. l Brush barriers should only be installed on contours. Design and Installation Specifications l Height: 2 feet (minimum) to 5 feet (maximum). l Width: 5 feet at base (minimum) to 15 feet (maximum). l Filter fabric (geotextile) may be anchored over the brush berm to enhance the filtration ability of the barrier. Ten-ounce burlap is an adequate alternative to filter fabric. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 365 N/A BMP C233: Silt Fence Purpose Silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use Silt fence may be used downslope of all disturbed areas. l Silt fence shall prevent sediment carried by runoff from going beneath, through, or over the top of the silt fence, but shall allow the water to pass through the fence. l Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Convey any concentrated flows through the drainage system to a sediment trapping BMP. l Do not construct silt fences in streams or use in V-shaped ditches. Silt fences do not provide an adequate method of silt control for anything deeper than sheet or overland flow. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 370 Figure II-3.22: Silt Fence 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 371 Joints in geotextile fabric shall be spliced at posts. Use staples, wire rings or equivalent to attach fabric to posts 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used x x X VX' XX>0<A xoi Rx Xxx>-X>:X XXXX’1 I EEj-X X I I: ;■;<>'_ >' *X xvwy !>x x ■,x' _n------ i ii i 6' max IMinimum 4''x4'' trench I II Post spacing may be increased to 8' if wire backing is used 2"x2" wood posts, steel fence posts, or equivalent 2''x2" by 14 Ga. wire or equivalent, if standard strength fabric used Geotextile fabric 2' min 7 Backfill trench with native soil or %" - 1.5" washed gravel r 'ToplE -T.\\ Minimum 4''x4'' trench . V 2"x2" wood posts, steel fence posts, or equivalent NOT TO SCALE Silt Fence Revised July 2017 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Design and Installation Specifications l Use in combination with other construction stormwater BMPs. l Maximum slope steepness (perpendicular to the silt fence line) 1H:1V. l Maximum sheet or overland flow path length to the silt fence of 100 feet. l Do not allow flows greater than 0.5 cfs. l Use geotextile fabric that meets the following standards. All geotextile properties listed below are minimum average roll values (i.e., the test result for any sampled roll in a lot shall meet or exceed the values shown in Table II-3.11: Geotextile Fabric Standards for Silt Fence): Geotextile Property Minimum Average Roll Value Polymeric Mesh AOS (ASTM D4751) 0.60 mm maximum for slit film woven (#30 sieve). 0.30 mm maximum for all other geotextile types (#50 sieve). 0.15 mm minimum for all fabric types (#100 sieve). Water Permittivity (ASTM D4491) 0.02 sec-1 minimum Grab Tensile Strength (ASTM D4632) 180 lbs. Minimum for extra strength fabric. 100 lbs minimum for standard strength fabric. Grab Tensile Strength (ASTM D4632) 30% maximum Ultraviolet Resistance (ASTM D4355) 70% minimum Table II-3.11: Geotextile Fabric Standards for Silt Fence l Support standard strength geotextiles with wire mesh, chicken wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the geotextile. Silt fence materials are available that have synthetic mesh backing attached. l Silt fence material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable construction life at a temperature range of 0°F to 120°F. l One-hundred percent biodegradable silt fence is available that is strong, long lasting, and can be left in place after the project is completed, if permitted by the local jurisdiction. l Refer to Figure II-3.22: Silt Fence for standard silt fence details. Include the following Stand- ard Notes for silt fence on construction plans and specifications: 1. The Contractor shall install and maintain temporary silt fences at the locations shown in the Plans. 2. Construct silt fences in areas of clearing, grading, or drainage prior to starting those activities. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 372 3. The silt fence shall have a 2-feet min. and a 2½-feet max. height above the original ground surface. 4. The geotextile fabric shall be sewn together at the point of manufacture to form fabric lengths as required. Locate all sewn seams at support posts. Alternatively, two sections of silt fence can be overlapped, provided that the overlap is long enough and that the adjacent silt fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. 5. Attach the geotextile fabric on the up-slope side of the posts and secure with staples, wire, or in accordance with the manufacturer's recommendations. Attach the geotextile fabric to the posts in a manner that reduces the potential for tearing. 6. Support the geotextile fabric with wire or plastic mesh, dependent on the properties of the geotextile selected for use. If wire or plastic mesh is used, fasten the mesh securely to the up-slope side of the posts with the geotextile fabric up-slope of the mesh. 7. Mesh support, if used, shall consist of steel wire with a maximum mesh spacing of 2- inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to the same level of ultraviolet radiation as the geotextile fabric it supports. 8. Bury the bottom of the geotextile fabric 4-inches min. below the ground surface. Backfill and tamp soil in place over the buried portion of the geotextile fabric, so that no flow can pass beneath the silt fence and scouring cannot occur. When wire or polymeric back-up support mesh is used, the wire or polymeric mesh shall extend into the ground 3-inches min. 9. Drive or place the silt fence posts into the ground 18-inches min. A 12–inch min. depth is allowed if topsoil or other soft subgrade soil is not present and 18-inches cannot be reached. Increase fence post min. depths by 6 inches if the fence is located on slopes of 3H:1V or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to pre- vent overturning of the fence due to sediment loading. 10. Use wood, steel or equivalent posts. The spacing of the support posts shall be a max- imum of 6-feet. Posts shall consist of either: l Wood with minimum dimensions of 2 inches by 2 inches by 3 feet. Wood shall be free of defects such as knots, splits, or gouges. l No. 6 steel rebar or larger. l ASTM A 120 steel pipe with a minimum diameter of 1-inch. l U, T, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. l Other steel posts having equivalent strength and bending resistance to the post sizes listed above. 11. Locate silt fences on contour as much as possible, except at the ends of the fence, 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 373 where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. 12. If the fence must cross contours, with the exception of the ends of the fence, place check dams perpendicular to the back of the fence to minimize concentrated flow and erosion. The slope of the fence line where contours must be crossed shall not be steeper than 3H:1V. l Check dams shall be approximately 1-foot deep at the back of the fence. Check dams shall be continued perpendicular to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. l Check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. Check dams shall be located every 10 feet along the fence where the fence must cross contours. l Refer to Figure II-3.23: Silt Fence Installation by Slicing Method for slicing method details. The following are specifications for silt fence installation using the slicing method: 1. The base of both end posts must be at least 2- to 4-inches above the top of the geo- textile fabric on the middle posts for ditch checks to drain properly. Use a hand level or string level, if necessary, to mark base points before installation. 2. Install posts 3- to 4-feet apart in critical retention areas and 6- to 7-feet apart in standard applications. 3. Install posts 24-inches deep on the downstream side of the silt fence, and as close as possible to the geotextile fabric, enabling posts to support the geotextile fabric from upstream water pressure. 4. Install posts with the nipples facing away from the geotextile fabric. 5. Attach the geotextile fabric to each post with three ties, all spaced within the top 8- inches of the fabric. Attach each tie diagonally 45 degrees through the fabric, with each puncture at least 1-inch vertically apart. Each tie should be positioned to hang on a post nipple when tightening to prevent sagging. 6. Wrap approximately 6-inches of the geotextile fabric around the end posts and secure with 3 ties. 7. No more than 24-inches of a 36-inch geotextile fabric is allowed above ground level. 8. Compact the soil immediately next to the geotextile fabric with the front wheel of the tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the upstream side first and then each side twice for a total of four trips. Check and correct the silt fence installation for any deviation before compaction. Use a flat-bladed shovel to tuck the fabric deeper into the ground if necessary. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 374 Figure II-3.23: Silt Fence Installation by Slicing Method 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 375 Ponding height max. 24" \v 3: 3:POST SPACING: 7 max. on open runs 4' max. on pooling areasAttach fabric to upstream side of post Top of Fabric I'////A E'////// Belt * FLOW POST DEPTH: As much below ground as fabric above ground top 8" Drive over each side of silt fence 2 to 4 times with device exerting 60 p.s.i. or greater i Diagonal attachment doubles strength100% compaction100% compaction r33n TT~ J]=I iLE inWo Q.ILEt Attachment Details: • Gather fabric at posts, if needed. • Utilize three ties per post, all within top 8" of fabric. • Position each tie diagonally, puncturing holes vertically a minimum of 1" apart. • Hang each tie on a post nipple and tighten securely. Use cable ties (50 lbs) or soft wire. oQ. Q.31HM1I meii=iii=iii i=in No more than 24" of a 36" fabric is allowed above ground Roll of silt fenceOperation Post installed after compaction Fabric above groundPIo Silt Fence ifJC il==U 200 - jj=ji 300mmIrmssrSlicing blade (18 mm width) Horizontal chisel point (76 mm width) Completed Installation Vibratory plow is not acceptable because of horizontal compaction NOT TO SCALE Silt Fence Installation by Slicing Method Revised June 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Maintenance Standards l Repair any damage immediately. l Intercept and convey all evident concentrated flows uphill of the silt fence to a sediment trap- ping BMP. l Check the uphill side of the silt fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence and remove the trapped sediment. l Remove sediment deposits when the deposit reaches approximately one-third the height of the silt fence, or install a second silt fence. l Replace geotextile fabric that has deteriorated due to ultraviolet breakdown. BMP C234: Vegetated Strip Purpose Vegetated strips reduce the transport of coarse sediment from a construction site by providing a physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use l Vegetated strips may be used downslope of all disturbed areas. l Vegetated strips are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to BMP C241: Sediment Pond (Temporary) or other sediment trapping BMP. The only circumstance in which overland flow can be treated solely by a vegetated strip, rather than by a sediment trapping BMP, is when the following criteria are met (see Table II- 3.12: Contributing Drainage Area for Vegetated Strips): Average Contributing Area Slope Average Contributing Area Per- cent Slope Max Contributing area Flowpath Length 1.5H : 1V or flatter 67% or flatter 100 feet 2H : 1V or flatter 50% or flatter 115 feet 4H : 1V or flatter 25% or flatter 150 feet 6H : 1V or flatter 16.7% or flatter 200 feet 10H : 1V or flatter 10% or flatter 250 feet Table II-3.12: Contributing Drainage Area for Vegetated Strips 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 376 Design and Installation Specifications l The vegetated strip shall consist of a continuous strip of dense vegetation with topsoil for a min- imum of a 25-foot length along the flowpath. Grass-covered, landscaped areas are generally not adequate because the volume of sediment overwhelms the grass. Ideally, vegetated strips shall consist of undisturbed native growth with a well-developed soil that allows for infiltration of runoff. l The slope within the vegetated strip shall not exceed 4H:1V. l The uphill boundary of the vegetated strip shall be delineated with clearing limits. Maintenance Standards l Any areas damaged by erosion or construction activity shall be seeded immediately and pro- tected by mulch. l If more than 5 feet of the original vegetated strip width has had vegetation removed or is being eroded, sod must be installed. l If there are indications that concentrated flows are traveling across the vegetated strip, storm- water runoff controls must be installed to reduce the flows entering the vegetated strip, or addi- tional perimeter protection must be installed. BMP C235: Wattles Purpose Wattles are temporary erosion and sediment control barriers consisting of straw, compost, or other material that is wrapped in netting made of natural plant fiber or similar encasing material. They reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sed- iment. Conditions of Use l Wattles shall consist of cylinders of plant material such as weed-free straw, coir, wood chips, excelsior, or wood fiber or shavings encased within netting made of natural plant fibers unaltered by synthetic materials. l Use wattles: o In disturbed areas that require immediate erosion protection. o On exposed soils during the period of short construction delays, or over winter months. o On slopes requiring stabilization until permanent vegetation can be established. l The material used dictates the effectiveness period of the wattle. Generally, wattles are effect- ive for one to two seasons. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 377 l Prevent rilling beneath wattles by entrenching and overlapping wattles to prevent water from passing between them. Design Criteria l See Figure II-3.24: Wattles for typical construction details. l Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length. l Install wattles perpendicular to the flow direction and parallel to the slope contour. l Place wattles in shallow trenches, staked along the contour of disturbed or newly constructed slopes. Dig narrow trenches across the slope (on contour) to a depth of 3- to 5-inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas with high rainfall, the trenches should be dug to a depth of 5- to 7- inches, or 1/2 to 2/3 of the thickness of the wattle. l Start building trenches and installing wattles from the base of the slope and work up. Spread excavated material evenly along the uphill slope and compact it using hand tamping or other methods. l Construct trenches at intervals of 10- to 25-feet depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches. l Install the wattles snugly into the trenches and overlap the ends of adjacent wattles 12 inches behind one another. l Install stakes at each end of the wattle, and at 4-foot centers along entire length of wattle. l If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. l Wooden stakes should be approximately 0.75 x 0.75 x 24 inches min. Willow cuttings or 3/8- inch rebar can also be used for stakes. l Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake pro- truding above the wattle. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 378 Figure II-3.24: Wattles 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 379 3' -4' (1,2 m) jjlSi\fc Viz Overlap adjacent rolls 12" behind one another / /■y \Straw rolls must be placed along slope contours /// \/ \ v-C »S \J/10' - 25' (3-8m)d ■■■ Spacing depends on soil type and slope steepness y. Sediment, organic matter, and native seeds are captured behind the rolls.*3 3"-5" (75-125mm) N\ 8"-10" Dia. (200-250mm)A///-<A.//A Live Stake // // // 1"x1" Stake £/ (25 x 25mm)/ \/ V NOTE:l 1. Straw roll installation requires the placement and secure staking of the roll in a trench, 3" - 5" (75-125mm) deep, dug on contour. Runoff must not be allowed to run under or around roll. A NOT TO SCALE Wattles Revised December 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Maintenance Standards l Wattles may require maintenance to ensure they are in contact with soil and thoroughly entrenched, especially after significant rainfall on steep sandy soils. l Inspect the slope after significant storms and repair any areas where wattles are not tightly abutted or water has scoured beneath the wattles. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology’s website at: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies BMP C236: Vegetative Filtration Purpose Vegetative filtration as a BMP is used in conjunction with detention storage in the form of portable tanks or BMP C241: Sediment Pond (Temporary), BMP C206: Level Spreader, and a pumping sys- tem with surface intake. Vegetative filtration improves turbidity levels of stormwater discharges by fil- tering runoff through existing vegetation where undisturbed forest floor duff layer or established lawn with thatch layer are present. Vegetative filtration can also be used to infiltrate dewatering waste from foundations, vaults, and trenches as long as runoff does not occur. Conditions of Use l For every five acres of disturbed soil use one acre of grass field, farm pasture, or wooded area. Reduce or increase this area depending on project size, ground water table height, and other site conditions. l Wetlands shall not be used for vegetative filtration. l Do not use this BMP in areas with a high ground water table, or in areas that will have a high seasonal ground water table during the use of this BMP. l This BMP may be less effective on soils that prevent the infiltration of the water, such as hard till. l Using other effective source control measures throughout a construction site will prevent the generation of additional highly turbid water and may reduce the time period or area need for this BMP. l Stop distributing water into the vegetated filtration area if standing water or erosion results. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 380 Maintenance Standards l Monitor the spray field on a daily basis to ensure that over saturation of any portion of the field doesn’t occur at any time. The presence of standing puddles of water or creation of con- centrated flows visually signify that over saturation of the field has occurred. l Monitor the vegetated spray field all the way down to the nearest surface water, or farthest spray area, to ensure that the water has not caused overland or concentrated flows, and has not created erosion around the spray nozzle(s). l Do not exceed water quality standards for turbidity. l Ecology recommends that a separate inspection log be developed, maintained and kept with the existing site logbook to aid the operator conducting inspections. This separate “Field Filtra- tion Logbook” can also aid in demonstrating compliance with permit conditions. l Inspect the spray nozzles daily, at a minimum, for leaks and plugging from sediment particles. l If erosion, concentrated flows, or over saturation of the field occurs, rotate the use of branches or spray heads or move the branches to a new field location. l Check all branches and the manifold for unintended leaks. BMP C240: Sediment Trap Purpose A sediment trap is a small temporary ponding area with a gravel outlet used to collect and store sed- iment from sites during construction. Sediment traps, along with other perimeter controls, shall be installed before any land disturbance takes place in the drainage area. Conditions of Use l Sediment traps are intended for use on sites where the tributary drainage area is less than 3 acres, with no unusual drainage features, and a projected build-out time of six months or less. The sediment trap is a temporary measure (with a design life of approximately 6 months) and shall be maintained until the tributary area is permanently protected against erosion by veget- ation and/or structures. l Sediment traps are only effective in removing sediment down to about the medium silt size fraction. Runoff with sediment of finer grades (fine silt and clay) will pass through untreated, emphasizing the need to control erosion to the maximum extent first. l Projects that are constructing permanent Flow Control BMPs, or Runoff Treatment BMPs that use ponding for treatment, may use the rough-graded or final-graded permanent BMP footprint for the temporary sediment trap. When permanent BMP footprints are used as tem- porary sediment traps, the surface area requirement of the sediment trap must be met. If the surface area requirement of the sediment trap is larger than the surface area of the per- manent BMP, then the sediment trap shall be enlarged beyond the permanent BMP footprint to comply with the surface area requirement. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 383 l A floating pond skimmer may be used for the sediment trap outlet if approved by the Local Per- mitting Authority. l Sediment traps may not be feasible on utility projects due to the limited work space or the short-term nature of the work. Portable tanks may be used in place of sediment traps for utility projects. Design and Installation Specifications l See Figure II-3.26: Cross Section of Sediment Trap and Figure II-3.27: Sediment Trap Outlet for details. l To determine the sediment trap geometry, first calculate the design surface area (SA) of the trap, measured at the invert of the weir. Use the following equation: SA = FS(Q2/Vs) where Q2 = o Option 1 - Single Event Hydrograph Method: Q2 = Peak volumetric flow rate calculated using a 10-minute time step from a Type 1A, 2-year, 24-hour frequency storm for the developed condition. The 10-year peak volu- metric flow rate shall be used if the project size, expected timing and duration of con- struction, or downstream conditions warrant a higher level of protection. o Option 2 - For construction sites that are less than 1 acre, the Rational Method may be used to determine Q2. Vs = The settling velocity of the soil particle of interest. The 0.02 mm (medium silt) particle with an assumed density of 2.65 g/cm3 has been selected as the particle of interest and has a set- tling velocity (Vs) of 0.00096 ft/sec. FS = A safety factor of 2 to account for non-ideal settling. Therefore, the equation for computing sediment trap surface area becomes: SA = 2 x Q2/0.00096 or 2080 square feet per cfs of inflow l Sediment trap depth shall be 3.5 feet minimum from the bottom of the trap to the top of the overflow weir. l To aid in determining sediment depth, all sediment traps shall have a staff gauge with a prom- inent mark 1-foot above the bottom of the trap. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 384 l Design the discharge from the sediment trap by using the guidance for discharge from tem- porary sediment ponds in BMP C241: Sediment Pond (Temporary). Maintenance Standards l Sediment shall be removed from the trap when it reaches 1-foot in depth. l Any damage to the trap embankments or slopes shall be repaired. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 385 Figure II-3.26: Cross Section of Sediment Trap 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 386 Surface area determined at top of weir 4' Min.i1' Min.Overflow1iV Min. T I T11' Min.u 3.5' - 5'&1.5' Min.i Flat Bottom I %" -1.5" Washed gravel Geotextile Discharge to stabilized conveyance, outlet, or level spreader Note: Trap may be formed by berm or by partial or complete excavation.2" - 4" Rock Rip Rap NOT TO SCALE Cross Section of Sediment Trap Revised June 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Figure II-3.27: Sediment Trap Outlet 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 387 6' Min. HiSiSiS V Min. depth overflow spillway I I T* -\in Min. T depth 2" - 4" rock Min. 1'depth %" -1-5" washed gravelNative soil or compacted backfill Geotextile NOT TO SCALE Sediment Trap Outlet Revised June 2016 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyhght.html for copyright notice including permissions, limitation of liability, and disclaimer.State of Washington Maintenance Standards l Remove sediment from the pond when it reaches 1 foot in depth. l Repair any damage to the pond embankments or slopes. BMP C250: Construction Stormwater Chemical Treatment Purpose This BMP applies when using chemicals to treat turbidity in stormwater by either batch or flow- through chemical treatment. Turbidity is difficult to control once fine particles are suspended in stormwater runoff from a con- struction site. BMP C241: Sediment Pond (Temporary) is effective at removing larger particulate matter by gravity settling, but is ineffective at removing smaller particulates such as clay and fine silt. Traditional Construction Stormwater BMPs may not be adequate to ensure compliance with the water quality standards for turbidity in the receiving water. Chemical treatment can reliably provide exceptional reductions of turbidity and associated pol- lutants. Chemical treatment may be required to meet turbidity stormwater discharge requirements, especially when construction proceeds through the wet season. Conditions of Use Formal written approval from Ecology is required for the use of chemical treatment, regardless of site size. See https://fortress.wa.gov/ecy/publications/SummaryPages/ecy070258.html for a copy of the Request for Chemical Treatment form. The Local Permitting Authority may also require review and approval. When authorized, the chemical treatment systems must be included in the Con- struction Stormwater Pollution Prevention Plan (SWPPP). Chemically treated stormwater discharged from construction sites must be nontoxic to aquatic organ- isms. The Chemical Technology Assessment Protocol - Ecology (CTAPE) must be used to evaluate chemicals proposed for stormwater treatment. Only chemicals approved by Ecology under the CTAPE may be used for stormwater treatment. The approved chemicals, their allowable application techniques (batch treatment or flow-through treatment), allowable application rates, and conditions of use can be found at the Department of Ecology Emerging Technologies website: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-permittee- guidance-resources/Emerging-stormwater-treatment-technologies Background on Chemical Treatment Systems Coagulation and flocculation have been used for over a century to treat water. The use of coagu- lation and flocculation to treat stormwater is a very recent application. Experience with the treatment of water and wastewater has resulted in a basic understanding of the process, in particular factors 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 396 that affect performance. This experience can provide insights as to how to most effectively design and operate similar systems in the treatment of stormwater. Fine particles suspended in water give it a milky appearance, measured as turbidity. Their small size, often much less than 1 µm in diameter, give them a very large surface area relative to their volume. These fine particles typically carry a negative surface charge. Largely because of these two factors (small size and negative charge), these particles tend to stay in suspension for extended periods of time. Thus, removal is not practical by gravity settling. These are called stable suspensions. Chem- icals like polymers, as well as inorganic chemicals such as alum, speed the settling process. The added chemical destabilizes the suspension and causes the smaller particles to flocculate. The pro- cess consists of three primary steps: coagulation, flocculation, and settling or clarification. Ecology requires a fourth step, filtration, on all stormwater chemical treatment systems to reduce floc dis- charge and to provide monitoring prior to discharge. General Design and Installation Specifications l Chemicals approved for use in Washington State are listed on Ecology's TAPE website, http://www.ecy.wa.gov/programs/wq/stormwater/newtech/technologies.html, under the "Con- struction" tab. l Care must be taken in the design of the withdrawal system to minimize outflow velocities and to prevent floc discharge. Stormwater that has been chemically treated must be filtered through BMP C251: Construction Stormwater Filtration for filtration and monitoring prior to dis- charge. l System discharge rates must take into account downstream conveyance integrity. l The following equipment should be located on site in a lockable shed: o The chemical injector. o Secondary containment for acid, caustic, buffering compound, and treatment chemical. o Emergency shower and eyewash. o Monitoring equipment which consists of a pH meter and a turbidimeter. l There are two types of systems for applying the chemical treatment process to stormwater: the batch chemical treatment system and the flow-through chemical treatment system. See below for further details for both types of systems. Batch Chemical Treatment Systems A batch chemical treatment system consists of four steps: coagulation, flocculation, clarification, and polishing and monitoring via filtration. Step 1: Coagulation Coagulation is the process by which negative charges on the fine particles are disrupted. By dis- rupting the negative charges, the fine particles are able to flocculate. Chemical addition is one method of destabilizing the suspension, and polymers are one class of chemicals that are generally effective. Chemicals that are used for this purpose are called coagulants. Coagulation is complete 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 397 when the suspension is destabilized by the neutralization of the negative charges. Coagulants per- form best when they are thoroughly and evenly dispersed under relatively intense mixing. This rapid mixing involves adding the coagulant in a manner that promotes rapid dispersion, followed by a short time period for destabilization of the particle suspension. The particles are still very small and are not readily separated by clarification until flocculation occurs. Step 2: Flocculation Flocculation is the process by which fine particles that have been destabilized bind together to form larger particles that settle rapidly. Flocculation begins naturally following coagulation, but is enhanced by gentle mixing of the destabilized suspension. Gentle mixing helps to bring particles in contact with one another such that they bind and continually grow to form "flocs." As the size of the flocs increase, they become heavier and settle. Step 3: Clarification The final step is the settling of the particles, or clarification. Particle density, size and shape are important during settling. Dense, compact flocs settle more readily than less dense, fluffy flocs. Because of this, flocculation to form dense, compact flocs is particularly important during chemical treatment. Water temperature is important during settling. Both the density and viscosity of water are affected by temperature; these in turn affect settling. Cold temperatures increase viscosity and dens- ity, thus slowing down the rate at which the particles settle. The conditions under which clarification is achieved can affect performance. Currents can affect set- tling. Currents can be produced by wind, by differences between the temperature of the incoming water and the water in the clarifier, and by flow conditions near the inlets and outlets. Quiescent water, such as that which occurs during batch clarification, provides a good environment for settling. One source of currents in batch chemical treatment systems is movement of the water leaving the clarifier unit. Because flocs are relatively small and light, the velocity of the water must be as low as possible. Settled flocs can be resuspended and removed by fairly modest currents. Step 4: Filtration After clarification, Ecology requires stormwater that has been chemically treated to be filtered and monitored prior to discharge. The sand filtration system continually monitors the stormwater effluent for turbidity and pH. If the discharge water is ever out of an acceptable range for turbidity or pH, the water is returned to the untreated stormwater pond where it will begin the treatment process again. Design and Installation of Batch Chemical Treatment Systems A batch chemical treatment system consists of a stormwater collection system (either a temporary diversion or the permanent site drainage system), an untreated stormwater storage pond, pumps, a chemical feed system, treatment cells, a filtering and monitoring system, and interconnecting piping. The batch treatment system uses a storage pond for untreated stormwater, followed by a minimum of two lined treatment cells. Multiple treatment cells allow for clarification of chemically treated water in one cell, while other cells are being filled or emptied. Treatment cells may be ponds or tanks. Ponds with constructed earthen embankments greater than six feet high or which impound more than 10 acre-feet are subject to the Washington Dam Safety Regulations (Chapter 173-175 WAC). 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 398 See BMP D.1: Detention Ponds for more information regarding dam safety considerations for ponds. Stormwater is collected at interception point(s) on the site and is diverted by gravity or by pumping to an untreated stormwater storage pond or other untreated stormwater holding area. The stormwater is stored until treatment occurs. It is important that the storage pond is large enough to provide adequate storage. The first step in the treatment sequence is to check the pH of the stormwater in the untreated storm- water storage pond. The pH is adjusted by the application of carbon dioxide or a base until the storm- water in the untreated storage pond is within the desired pH range, 6.5 to 8.5. When used, carbon dioxide is added immediately downstream of the transfer pump. Typically sodium bicarbonate (bak- ing soda) is used as a base, although other bases may be used. When needed, base is added dir- ectly to the untreated stormwater storage pond. The stormwater is recirculated with the treatment pump to provide mixing in the storage pond. Initial pH adjustments should be based on daily bench tests. Further pH adjustments can be made at any point in the process. See BMP C252: Treating and Disposing of High pH Water for more information on pH adjustments as a part of chemical treat- ment. Once the stormwater is within the desired pH range (which is dependant on the coagulant being used), the stormwater is pumped from the untreated stormwater storage pond to a lined treatment cell as a coagulant is added. The coagulant is added upstream of the pump to facilitate rapid mixing. The water is kept in the lined treatment cell for clarification. In a batch mode process, clarification typ- ically takes from 30 minutes to several hours. Prior to discharge, samples are withdrawn for analysis of pH, coagulant concentration, and turbidity. If these levels are acceptable, the treated water is with- drawn, filtered, and discharged. Several configurations have been developed to withdraw treated water from the treatment cell. The original configuration is a device that withdraws the treated water from just beneath the water sur- face using a float with adjustable struts that prevent the float from settling on the cell bottom. This reduces the possibility of picking up floc from the bottom of the cell. The struts are usually set at a min- imum clearance of about 12 inches; that is, the float will come within 12 inches of the bottom of the cell. Other systems have used vertical guides or cables which constrain the float, allowing it to drift up and down with the water level. More recent designs have an H-shaped array of pipes, set on the hori- zontal.This scheme provides for withdrawal from four points rather than one. This configuration reduces the likelihood of sucking settled solids from the bottom. It also reduces the tendency for a vor- tex to form. Inlet diffusers, a long floating or fixed pipe with many small holes in it, are also an option. Safety is a primary concern. Design should consider the hazards associated with operations, such as sampling. Facilities should be designed to reduce slip hazards and drowning. Tanks and ponds should have life rings, ladders, or steps extending from the bottom to the top. Sizing Batch Chemical Treatment Systems Chemical treatment systems must be designed to control the velocity and peak volumetric flow rate that is discharged from the system and consequently the project site. See Element 3: Control Flow Rates for further details on this requirement. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 399 The total volume of the untreated stormwater storage pond and treatment cells must be large enough to treat stormwater that is produced during multiple day storm events. It is recommended that at a minimum the untreated stormwater storage pond be sized to hold 1.5 times the volume of runoff generated from the site during the 10-year, 24-hour storm event. Bypass should be provided around the chemical treatment system to accommodate extreme storm events. Runoff volume shall be calculated using the methods presented in III-2.3 Single Event Hydrograph Method. Worst-case land cover conditions (i.e., producing the most runoff) should be used for analyses (in most cases, this would be the land cover conditions just prior to final landscaping). Primary settling should be encouraged in the untreated stormwater storage pond. A forebay with access for maintenance may be beneficial. There are two opposing considerations in sizing the treatment cells. A larger cell is able to treat a lar- ger volume of water each time a batch is processed. However, the larger the cell, the longer the time required to empty the cell. A larger cell may also be less effective at flocculation and therefore require a longer settling time. The simplest approach to sizing the treatment cell is to multiply the allowable discharge flow rate (as determined by the guidance in Element 3: Control Flow Rates) times the desired drawdown time. A 4-hour drawdown time allows one batch per cell per 8-hour work period, given 1 hour of flocculation followed by two hours of settling. See BMP C251: Construction Stormwater Filtration for details on sizing the filtration system at the end of the batch chemical treatment system. If the chemical treatment system design does not allow you to discharge at the rates as required by Element 3: Control Flow Rates, and if the site has a permanent Flow Control BMP that will serve the planned development, the discharge from the chemical treatment system may be directed to the per- manent Flow Control BMP to comply with Element 3: Control Flow Rates. In this case, all discharge (including water passing through the treatment system and stormwater bypassing the treatment sys- tem) will be directed into the permanent Flow Control BMP. If site constraints make locating the untreated stormwater storage pond difficult, the permanent Flow Control BMP may be divided to serve as the untreated stormwater storage pond and the post-treatment temporary flow control pond. A berm or barrier must be used in this case so the untreated water does not mix with the treated water. Both untreated stormwater storage requirements, and adequate post-treatment flow control must be achieved. The designer must document in the Construction SWPPP how the per- manent Flow Control BMP is able to attenuate the discharge from the site to meet the requirements of Element 3: Control Flow Rates. If the design of the permanent Flow Control BMP was modified for temporary construction flow control purposes, the construction of the permanent Flow Control BMP must be finalized, as designed for its permanent function, at project completion. Flow-Through Chemical Treatment Systems Background on Flow-Through Chemical Treatment Systems A flow-through chemical treatment system adds a sand filtration component to the batch chemical treatment system's treatment train following flocculation. The coagulant is added to the stormwater upstream of the sand filter so that the coagulation and flocculation step occur immediately prior to the filter. The advantage of a flow-through chemical treatment system is the time saved by immediately filtering the water, as opposed to waiting for the clarification process necessary in a batch chemical 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 400 treatment system. See BMP C251: Construction Stormwater Filtration for more information on fil- tration. Design and Installation of Flow-Through Chemical Treatment Systems At a minimum, a flow-through chemical treatment system consists of a stormwater collection system (either a temporary diversion or the permanent site drainage system), an untreated stormwater stor- age pond, and a chemically enhanced sand filtration system. As with a batch treatment system, stormwater is collected at interception point(s) on the site and is diverted by gravity or by pumping to an untreated stormwater storage pond or other untreated storm- water holding area. The stormwater is stored until treatment occurs. It is important that the holding pond be large enough to provide adequate storage. Stormwater is then pumped from the untreated stormwater storage pond to the chemically enhanced sand filtration system where a coagulant is added. Adjustments to pH may be necessary before coagulant addition. The sand filtration system continually monitors the stormwater effluent for turbidity and pH. If the discharge water is ever out of an acceptable range for turbidity or pH, the water is returned to the untreated stormwater pond where it will begin the treatment process again. Sizing Flow-Through Chemical Treatment Systems Refer to BMP C251: Construction Stormwater Filtration for sizing requirements of flow-through chemical treatment systems. Factors Affecting the Chemical Treatment Process Coagulants Cationic polymers can be used as coagulants to destabilize negatively charged turbidity particles present in natural waters, wastewater and stormwater. Polymers are large organic molecules that are made up of subunits linked together in a chain-like structure. Attached to these chain-like struc- tures are other groups that carry positive or negative charges, or have no charge. Polymers that carry groups with positive charges are called cationic, those with negative charges are called anionic, and those with no charge (neutral) are called nonionic. In practice, the only way to determ- ine whether a polymer is effective for a specific application is to perform preliminary or on-site test- ing. Aluminum sulfate (alum) can also be used as a coagulant, as this chemical becomes positively charged when dispersed in water. Polymers are available as powders, concentrated liquids, and emulsions (which appear as milky liquids). The latter are petroleum based, which are not allowed for construction stormwater treat- ment. Polymer effectiveness can degrade with time and also from other influences. Thus, man- ufacturers' recommendations for storage should be followed. Manufacturer’s recommendations usually do not provide assurance of water quality protection or safety to aquatic organisms. Con- sideration of water quality protection is necessary in the selection and use of all polymers. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 401 Application Application of coagulants at the appropriate concentration or dosage rate for optimum turbidity removal is important for management of chemical cost, for effective performance, and to avoid aquatic toxicity. The optimum dose in a given application depends on several site-specific features. Turbidity of untreated water can be important with turbidities greater than 5,000 NTU. The surface charge of particles to be removed is also important. Environmental factors that can influence dosage rate are water temperature, pH, and the presence of constituents that consume or otherwise affect coagulant effectiveness. Laboratory experiments indicate that mixing previously settled sediment (floc sludge) with the untreated stormwater significantly improves clarification, therefore reducing the effective dosage rate. Preparation of working solutions and thorough dispersal of coagulants in water to be treated is also important to establish the appropriate dosage rate. For a given water sample, there is generally an optimum dosage rate that yields the lowest residual turbidity after settling. When dosage rates below this optimum value (underdosing) are applied, there is an insufficient quantity of coagulant to react with, and therefore destabilize, all of the turbidity present. The result is residual turbidity (after flocculation and settling) that is higher than with the optimum dose. Overdosing, application of dosage rates greater than the optimum value, can also negatively impact performance. Like underdosing, the result of overdosing is higher residual turbidity than that with the optimum dose. Mixing The G-value, or just "G", is often used as a measure of the mixing intensity applied during coagu- lation and flocculation. The symbol G stands for “velocity gradient”, which is related in part to the degree of turbulence generated during mixing. High G-values mean high turbulence, and vice versa. High G-values provide the best conditions for coagulant addition. With high G's, turbulence is high and coagulants are rapidly dispersed to their appropriate concentrations for effective destabilization of particle suspensions. Low G-values provide the best conditions for flocculation. Here, the goal is to promote formation of dense, compact flocs that will settle readily. Low G's provide low turbulence to promote particle col- lisions so that flocs can form. Low G's generate sufficient turbulence such that collisions are effective in floc formation, but do not break up flocs that have already formed. pH Adjustment The pH must be in the proper range for the coagulants to be effective, which is typically 6.5 to 8.5. As polymers tend to lower the pH, it is important that the stormwater have sufficient buffering capacity. Buffering capacity is a function of alkalinity. Without sufficient alkalinity, the application of the polymer may lower the pH to below 6.5. A pH below 6.5 not only reduces the effectiveness of the polymer as a coagulant, but it may also create a toxic condition for aquatic organisms. Stormwater may not be discharged without readjustment of the pH to above 6.5. The target pH should be within 0.2 stand- ard units of the receiving water's pH. Experience gained at several projects in the City of Redmond has shown that the alkalinity needs to be at least 50 mg/L to prevent a drop in pH to below 6.5 when the polymer is added. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 402 Maintenance Standards Monitoring At a minimum, the following monitoring shall be conducted. Test results shall be recorded on a daily log kept on site. Additional testing may be required by the NPDES permit based on site conditions. l Operational Monitoring o Total volume treated and discharged. o Flow must be continuously monitored and recorded at not greater than 15-minute inter- vals. o Type and amount of chemical used for pH adjustment. o Type and amount of coagulant used for treatment. o Settling time. l Compliance Monitoring o Influent and effluent pH, flocculent chemical concentration, and turbidity must be con- tinuously monitored and recorded at not greater than 15-minute intervals. o pH and turbidity of the receiving water. l Biomonitoring o Treated stormwater must be non-toxic to aquatic organisms. Treated stormwater must be tested for aquatic toxicity or residual chemicals. Frequency of biomonitoring will be determined by Ecology. o Residual chemical tests must be approved by Ecology prior to their use. o If testing treated stormwater for aquatic toxicity, you must test for acute (lethal) toxicity. Bioassays shall be conducted by a laboratory accredited by Ecology, unless otherwise approved by Ecology. Acute toxicity tests shall be conducted per the CTAPE protocol and Appendix G of Whole Effluent Toxicity Testing Guidance and Test Review Criteria (Marshall, 2016). Discharge Compliance Prior to discharge, treated stormwater must be sampled and tested for compliance with pH, floc- culent chemical concentration, and turbidity limits. These limits may be established by the Con- struction Stormwater General Permit or a site-specific discharge permit. Sampling and testing for other pollutants may also be necessary at some sites. pH must be within the range of 6.5 to 8.5 stand- ard units and not cause a change in the pH of the receiving water by more than 0.2 standard units. Treated stormwater samples and measurements shall be taken from the discharge pipe or another location representative of the nature of the treated stormwater discharge. Samples used for determ- ining compliance with the water quality standards in the receiving water shall not be taken from the 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 403 treatment pond prior to decanting. Compliance with the water quality standards is determined in the receiving water. Operator Training Each project site using chemical treatment must have a trained operator who is certified for oper- ation of an Enhanced Chemical Treatment system. The operator must be trained and certified by an organization approved by Ecology. Organizations approved for operator training are found at the fol- lowing website: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-permittee- guidance-resources/Contaminated-water-on-construction-sites Sediment Removal and Disposal l Sediment shall be removed from the untreated stormwater storage pond and treatment cells as necessary. Typically, sediment removal is required at least once during a wet season and at the decommissioning of the chemical treatment system. Sediment remaining in the cells between batches may enhance the settling process and reduce the required chemical dosage. l Sediment that is known to be non-toxic may be incorporated into the site away from drain- ages. BMP C251: Construction Stormwater Filtration Purpose Filtration removes sediment from runoff originating from disturbed areas of the site. Conditions of Use Traditional Construction Stormwater BMPs used to control soil erosion and sediment loss from con- struction sites may not be adequate to ensure compliance with the water quality standard for tur- bidity in the receiving water. Filtration may be used in conjunction with gravity settling to remove sediment as small as fine silt (0.5 µm). The reduction in turbidity will be dependent on the particle size distribution of the sediment in the stormwater. In some circumstances, sedimentation and fil- tration may achieve compliance with the water quality standard for turbidity. The use of construction stormwater filtration does not require approval from Ecology as long as treat- ment chemicals are not used. Filtration in conjunction with BMP C250: Construction Stormwater Chemical Treatment requires testing under the Chemical Technology Assessment Protocol – Eco- logy (CTAPE) before it can be initiated. Approval from Ecology must be obtained at each site where chemical use is proposed prior to use. See https://- fortress.wa.gov/ecy/publications/SummaryPages/ecy070258.html for a copy of the Request for Chemical Treatment form. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 404 Design and Installation Specifications Two types of filtration systems may be applied to construction stormwater treatment: rapid and slow. Rapid filtration systems are the typical system used for water and wastewater treatment. They can achieve relatively high hydraulic flow rates, on the order of 2 to 20 gpm/sf, because they have auto- matic backwash systems to remove accumulated solids. Slow filtration systems have very low hydraulic rates, on the order of 0.02 gpm/sf, because they do not have backwash systems. Slow filtration systems have generally been used as post construction BMPs to treat stormwater (see V-6 Filtration BMPs). Slow filtration is mechanically simple in com- parison to rapid filtration, but requires a much larger filter area. Filter Types and Efficiencies Sand media filters are available with automatic backwashing features that can filter to 50 µm particle size. Screen or bag filters can filter down to 5 µm. Fiber wound filters can remove particles down to 0.5 µm. Filters should be sequenced from the largest to the smallest pore opening. Sediment removal efficiency will be related to particle size distribution in the stormwater. Treatment Process and Description Stormwater is collected at interception point(s) on the site and diverted to an untreated stormwater sediment pond or tank for removal of large sediment, and storage of the stormwater before it is treated by the filtration system. In a rapid filtration system, the untreated stormwater is pumped from the pond or tank through the filtration media. Slow filtration systems are designed using gravity to convey water from the pond or tank to and through the filtration media. Sizing Filtration treatment systems must be designed to control the velocity and peak volumetric flow rate that is discharged from the system and consequently the project site. See Element 3: Control Flow Rates for further details on this requirement. The untreated stormwater storage pond or tank should be sized to hold 1.5 times the volume of run- off generated from the site during the 10-year, 24-hour storm event, minus the filtration treatment system flowrate for an 8-hour period. For a chitosan-enhanced sand filtration system, the filtration treatment system flowrate should be sized using a hydraulic loading rate between 6-8 gpm/ft2. Other hydraulic loading rates may be more appropriate for other systems. Bypass should be provided around the filtration treatment system to accommodate extreme storm events. Runoff volume shall be calculated using the methods presented in III-2.3 Single Event Hydrograph Method. Worst-case land cover conditions (i.e., producing the most runoff) should be used for analyses (in most cases, this would be the land cover conditions just prior to final landscaping). If the filtration treatment system design does not allow you to discharge at the rates as required by Element 3: Control Flow Rates, and if the site has a permanent Flow Control BMP that will serve the planned development, the discharge from the filtration treatment system may be directed to the per- manent Flow Control BMP to comply with Element 3: Control Flow Rates. In this case, all discharge (including water passing through the treatment system and stormwater bypassing the treatment 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 405 system) will be directed into the permanent Flow Control BMP. If site constraints make locating the untreated stormwater storage pond difficult, the permanent Flow Control BMP may be divided to serve as the untreated stormwater storage pond and the post-treatment temporary flow control pond. A berm or barrier must be used in this case so the untreated water does not mix with the treated water. Both untreated stormwater storage requirements, and adequate post-treatment flow control must be achieved. The designer must document in the Construction SWPPP how the per- manent Flow Control BMP is able to attenuate the discharge from the site to meet the requirements of Element 3: Control Flow Rates. If the design of the permanent Flow Control BMP was modified for temporary construction flow control purposes, the construction of the permanent Flow Control BMP must be finalized, as designed for its permanent function, at project completion. Maintenance Standards l Rapid sand filters typically have automatic backwash systems that are triggered by a pre-set pressure drop across the filter. If the backwash water volume is not large or substantially more turbid than the untreated stormwater stored in the holding pond or tank, backwash return to the untreated stormwater pond or tank may be appropriate. However, other means of treat- ment and disposal may be necessary. l Screen, bag, and fiber filters must be cleaned and/or replaced when they become clogged. l Sediment shall be removed from the storage and/or treatment ponds as necessary. Typically, sediment removal is required once or twice during a wet season and at the decommissioning of the ponds. l Disposal of filtration equipment must comply with applicable local, state, and federal reg- ulations. BMP C252: Treating and Disposing of High pH Water Purpose When pH levels in stormwater rise above 8.5, it is necessary to lower the pH levels to the acceptable range of 6.5 to 8.5 prior to discharge to surface or ground water. A pH level range of 6.5 to 8.5 is typ- ical for most natural watercourses, and this neutral pH range is required for the survival of aquatic organisms. Should the pH rise or drop out of this range, fish and other aquatic organisms may become stressed and may die. Conditions of Use l The water quality standard for pH in Washington State is in the range of 6.5 to 8.5. Storm- water with pH levels exceeding water quality standards may be either neutralized on site or disposed of to a sanitary sewer or concrete batch plant with pH neutralization capabilities. l Neutralized stormwater may be discharged to surface waters under the Construction Storm- water General permit. l Neutralized process water such as concrete truck wash-out, hydro-demolition, or saw-cutting slurry must be managed to prevent discharge to surface waters. Any stormwater 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 406 contaminated during concrete work is considered process wastewater and must not be dis- charged to waters of the State or stormwater collection systems. l The process used for neutralizing and/or disposing of high pH stormwater from the site must be documented in the Construction Stormwater Pollution Prevention Plan. Causes of High pH High pH at construction sites is most commonly caused by the contact of stormwater with poured or recycled concrete, cement, mortars, and other Portland cement or lime containing construction materials. (See BMP C151: Concrete Handling for more information on concrete handling pro- cedures). The principal caustic agent in cement is calcium hydroxide (free lime). Calcium hardness can contribute to high pH values and cause toxicity that is associated with high pH conditions. A high level of calcium hardness in waters of the state is not allowed. Ground water stand- ard for calcium and other dissolved solids in Washington State is less than 500 mg/l. Treating High pH Stormwater by Carbon Dioxide Sparging Advantages of Carbon Dioxide Sparging l Rapidly neutralizes high pH water. l Cost effective and safer to handle than acid compounds. l CO2 is self-buffering. It is difficult to overdose and create harmfully low pH levels. l Material is readily available. The Chemical Process of Carbon Dioxide Sparging When carbon dioxide (CO2) is added to water (H2O), carbonic acid (H2CO3) is formed which can further dissociate into a proton (H+) and a bicarbonate anion (HCO3-) as shown below: CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3- The free proton is a weak acid that can lower the pH. Water temperature has an effect on the reac- tion as well. The colder the water temperature is, the slower the reaction occurs. The warmer the water temperature is, the quicker the reaction occurs. Most construction applications in Washington State have water temperatures in the 50°F or higher range so the reaction is almost simultaneous. The Treatment Process of Carbon Dioxide Sparging High pH water may be treated using continuous treatment, continuous discharge systems. These manufactured systems continuously monitor influent and effluent pH to ensure that pH values are within an acceptable range before being discharged. All systems must have fail safe automatic shut off switches in the event that pH is not within the acceptable discharge range. Only trained operators may operate manufactured systems. System manufacturers often provide trained operators or train- ing on their devices. The following procedure may be used when not using a continuous discharge system: 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 407 1. Prior to treatment, the appropriate jurisdiction should be notified in accordance with the reg- ulations set by the jurisdiction. 2. Every effort should be made to isolate the potential high pH water in order to treat it separately from other stormwater on-site. 3. Water should be stored in an acceptable storage facility, detention pond, or containment cell prior to pH treatment. 4. Transfer water to be treated for pH to the pH treatment structure. Ensure that the pH treat- ment structure size is sufficient to hold the amount of water that is to be treated. Do not fill the pH treatment structure completely, allow at least 2 feet of freeboard. 5. The operator samples the water within the pH treatment structure for pH and notes the clarity of the water. As a rule of thumb, less CO2 is necessary for clearer water. The results of the samples and water clarity observations should be recorded. 6. In the pH treatment structure, add CO2 until the pH falls into the range of 6.9-7.1. Adjusting pH to within 0.2 pH units of receiving water (background pH) is recommended. It is unlikely that pH can be adjusted to within 0.2 pH units using dry ice. Compressed carbon dioxide gas should be introduced to the water using a carbon dioxide diffuser located near the bottom of the pH treatment structure, this will allow carbon dioxide to bubble up through the water and diffuse more evenly. 7. Slowly discharge the water, making sure water does not get stirred up in the process. Release about 80% of the water from the pH treatment structure leaving any sludge behind. If turbidity remains above the maximum allowable, consider adding filtration to the treatment train. See BMP C251: Construction Stormwater Filtration. 8. Discharge treated water through a pond or drainage system. 9. Excess sludge needs to be disposed of properly as concrete waste. If several batches of water are undergoing pH treatment, sludge can be left in the treatment structure for the next batch treatment. Dispose of sludge when it fills 50% of the treatment structure volume. 10. Disposal must comply with applicable local, state, and federal regulations. Treating High pH Stormwater by Food Grade Vinegar Food grade vinegar that meets FDA standards may be used to neutralize high pH water. Food grade vinegar is only 4% to 18% acetic acid with the remainder being water. Food grade vinegar may be used if dosed just enough to lower pH sufficiently. Use a treatment process as described above for CO2 sparging, but add food grade vinegar instead of CO2. This treatment option for high pH stormwater does not apply to anything but food grade vinegar. Acetic acid does not equal vinegar. Any other product or waste containing acetic acid must go through the evaluation process in Appendix G of Whole Effluent Toxicity Testing Guidance and Test Review Criteria (Marshall, 2016). 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 408 Disposal of High pH Stormwater Sanitary Sewer Disposal Local sewer authority approval is required prior to disposal via the sanitary sewer. Concrete Batch Plant Disposal l Only permitted facilities may accept high pH water. l Contact the facility to ensure they can accept the high pH water. Maintenance Standards Safety and materials handling: l All equipment should be handled in accordance with OSHA rules and regulations. l Follow manufacturer guidelines for materials handling. Each operator should provide: l A diagram of the monitoring and treatment equipment. l A description of the pumping rates and capacity the treatment equipment is capable of treat- ing. Each operator should keep a written record of the following: l Client name and phone number. l Date of treatment. l Weather conditions. l Project name and location. l Volume of water treated. l pH of untreated water. l Amount of CO2 or food grade vinegar needed to adjust water to a pH range of 6.9-7.1. l pH of treated water. l Discharge point location and description. A copy of this record should be given to the client/contractor who should retain the record for three years. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 409 Page | 35 Appendix D – Site Inspection Form Construction Stormwater Site Inspection Form Page 1 Project Name Permit # Inspection Date Time Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre Print Name: Approximate rainfall amount since the last inspection (in inches): Approximate rainfall amount in the last 24 hours (in inches): Current Weather Clear Cloudy Mist Rain Wind Fog A. Type of inspection: Weekly Post Storm Event Other B. Phase of Active Construction (check all that apply): Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads Concrete pours Vertical Construction/buildings Utilities Offsite improvements Site temporary stabilized Final stabilization C. Questions: 1. Were all areas of construction and discharge points inspected? Yes No 2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No 3. Was a water quality sample taken during inspection? (refer to permit conditions S4 & S5) Yes No 4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No 5. If yes to #4 was it reported to Ecology? Yes No 6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken, and when. *If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33 cm or greater. Sampling Results: Date: Parameter Method (circle one) Result Other/Note NTU cm pH Turbidity tube, meter, laboratory pH Paper, kit, meter Construction Stormwater Site Inspection Form Page 2 D. Check the observed status of all items. Provide “Action Required “details and dates. Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 1 Clearing Limits Before beginning land disturbing activities are all clearing limits, natural resource areas (streams, wetlands, buffers, trees) protected with barriers or similar BMPs? (high visibility recommended) 2 Construction Access Construction access is stabilized with quarry spalls or equivalent BMP to prevent sediment from being tracked onto roads? Sediment tracked onto the road way was cleaned thoroughly at the end of the day or more frequent as necessary. 3 Control Flow Rates Are flow control measures installed to control stormwater volumes and velocity during construction and do they protect downstream properties and waterways from erosion? If permanent infiltration ponds are used for flow control during construction, are they protected from siltation? 4 Sediment Controls All perimeter sediment controls (e.g. silt fence, wattles, compost socks, berms, etc.) installed, and maintained in accordance with the Stormwater Pollution Prevention Plan (SWPPP). Sediment control BMPs (sediment ponds, traps, filters etc.) have been constructed and functional as the first step of grading. Stormwater runoff from disturbed areas is directed to sediment removal BMP. 5 Stabilize Soils Have exposed un-worked soils been stabilized with effective BMP to prevent erosion and sediment deposition? Construction Stormwater Site Inspection Form Page 3 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 5 Stabilize Soils Cont. Are stockpiles stabilized from erosion, protected with sediment trapping measures and located away from drain inlet, waterways, and drainage channels? Have soils been stabilized at the end of the shift, before a holiday or weekend if needed based on the weather forecast? 6 Protect Slopes Has stormwater and ground water been diverted away from slopes and disturbed areas with interceptor dikes, pipes and or swales? Is off-site storm water managed separately from stormwater generated on the site? Is excavated material placed on uphill side of trenches consistent with safety and space considerations? Have check dams been placed at regular intervals within constructed channels that are cut down a slope? 7 Drain Inlets Storm drain inlets made operable during construction are protected. Are existing storm drains within the influence of the project protected? 8 Stabilize Channel and Outlets Have all on-site conveyance channels been designed, constructed and stabilized to prevent erosion from expected peak flows? Is stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream conveyance systems? 9 Control Pollutants Are waste materials and demolition debris handled and disposed of to prevent contamination of stormwater? Has cover been provided for all chemicals, liquid products, petroleum products, and other material? Has secondary containment been provided capable of containing 110% of the volume? Were contaminated surfaces cleaned immediately after a spill incident? Were BMPs used to prevent contamination of stormwater by a pH modifying sources? Construction Stormwater Site Inspection Form Page 4 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 9 Cont. Wheel wash wastewater is handled and disposed of properly. 10 Control Dewatering Concrete washout in designated areas. No washout or excess concrete on the ground. Dewatering has been done to an approved source and in compliance with the SWPPP. Were there any clean non turbid dewatering discharges? 11 Maintain BMP Are all temporary and permanent erosion and sediment control BMPs maintained to perform as intended? 12 Manage the Project Has the project been phased to the maximum degree practicable? Has regular inspection, monitoring and maintenance been performed as required by the permit? Has the SWPPP been updated, implemented and records maintained? 13 Protect LID Is all Bioretention and Rain Garden Facilities protected from sedimentation with appropriate BMPs? Is the Bioretention and Rain Garden protected against over compaction of construction equipment and foot traffic to retain its infiltration capabilities? Permeable pavements are clean and free of sediment and sediment laden- water runoff. Muddy construction equipment has not been on the base material or pavement. Have soiled permeable pavements been cleaned of sediments and pass infiltration test as required by stormwater manual methodology? Heavy equipment has been kept off existing soils under LID facilities to retain infiltration rate. E. Check all areas that have been inspected. All in place BMPs All disturbed soils All concrete wash out area All material storage areas All discharge locations All equipment storage areas All construction entrances/exits Construction Stormwater Site Inspection Form Page 5 F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number; be specific on location and work needed. Document, initial, and date when the corrective action has been completed and inspected. Element # Description and Location Action Required Completion Date Initials Attach additional page if needed Sign the following certification: “I certify that this report is true, accurate, and complete, to the best of my knowledge and belief” Inspected by: (print) (Signature) Date: Title/Qualification of Inspector: Page | 36 Appendix H – Engineering Calculations Proposed Runoff Conditions for TESC - Entire Site Total Site:Area (ac) Pervious Area 0.000 Impervious Area 0.470 Total Area 0.470 Stormshed Data Type Reduced Time Step 15-min MGS - Flood 2-Yr developed flow 0.193 cfs MGS - Flood 10-Yr developed flow 0.293 cfs MGS - Flood 25-Yr developed flow 0.367 cfs MGS - Flood 100-Yr developed flow 0.547 cfs Vr=S.A. x 3.5'Vr = Minimum Required Storage Volume S.A. = Minimum allowable top surface area of pond S.A. = (2Q2)/Vsed Q = design peak flow rate Vsed = 0.00096 Settling Velocity (0.00096 ft/sec) Q=0.193 cfs INPUT (note that this is the 10-yr design peak flow rate in cfs) S.A. = 402 sf Vr=1407 cf Volume Required 10,527 gal 1 sediment storage tanks are required. * the volume is based a minimum pond depth of 3.5' - this depth does not include the minimum sediment storage volume or freeboard Assume 18,900 gallons per sediment storage tank, then Temporary Sediment Trap Sizing: Storage Volume per Section D.2.1.5, ESC Measures: Selection of the Design Storm of the 2021 King County Surface Water Design Manual - Appendix D: 255 S. King Street, Suite 800, Seattle, WA 98104 | 206.426.2600 | JACOBSONENGINEERS.COM ————————————————————————————————— MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.59 Program License Number: 201910001 Project Simulation Performed on: 08/29/2024 2:56 PM Report Generation Date: 08/29/2024 2:56 PM ————————————————————————————————— Input File Name: 2024-08-29 RSD Transportation Expansion TESC Sizing.fld Project Name: RSD Transportation Expansion Analysis Title: TESC Sizing Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Full Period of Record Available used for Routing Climatic Region Number: 16 Precipitation Station : 96004405 Puget East 44 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961044 Puget East 44 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : Ecology Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.470 0.470 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.470 0.470 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- C, Forest, Flat 0.470 ---------------------------------------------- TESC - SEDIMENTATION TANK SIZING CALCULATIONS Subbasin Total 0.470 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- SIDEWALKS/FLAT 0.470 ---------------------------------------------- Subbasin Total 0.470 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 0 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 89.444 _____________________________________ Total: 89.444 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 0.000 _____________________________________ Total: 0.000 Total Predevelopment Recharge is Greater than Post Developed TESC - SEDIMENTATION TANK SIZING CALCULATIONS Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.566 ac-ft/year, Post Developed: 0.000 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 ***********Compliance Point Results ************* Scenario Predeveloped Compliance Subbasin: Subbasin 1 Scenario Postdeveloped Compliance Subbasin: Subbasin 1 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 1.183E-02 2-Year 0.193 5-Year 1.865E-02 5-Year 0.249 10-Year 2.319E-02 10-Year 0.293 25-Year 3.195E-02 25-Year 0.367 50-Year 3.509E-02 50-Year 0.440 100-Year 3.803E-02 100-Year 0.547 200-Year 5.630E-02 200-Year 0.583 500-Year 8.085E-02 500-Year 0.629 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals TESC - SEDIMENTATION TANK SIZING CALCULATIONS RENTON SCHOOL DISTRICT TRANSPORTATION EXPANSION 24 APPENDIX D FACILITY SUMMARY SHEET DECLARATION OF COVENANT STORMWATER FACILITY SUMMARY SHEET ( provide one Stormwater Facility Summary Sheet per Natural Discharge Location) Major Basin Name __ Immediate Basin Name GENERAL FACILITY INFORMATION: Detention Infiltration Water Quality Flow Control Type # of Type # of Type #of Performance Std Pond s Ponds Ponds □ Basic Vaults Tanks Vaults □ Conservation Tanks renches Tanks □ Flood Problem DPER Permit No. Date NPDES Permit No. Parcel No. Retired Parcel No. Project includes Landscape Management Plan? yes □ (include copy with TIR as Appendix) no □ Declarations of Covenant Recording No. Leachable Metals Impervious Surface Limit Flow Control BMPs Clearing Limit Drainage Facility Landscape Management Plan If no flow control facility, check one: □ Project qualifies for KCSWDM Exemption (KCSWDM 1.2.3): □ Basic Exemption □ Impervious Surface Exemption for Transportation Redevelopment projects □ Cost Exemption for Parcel Redevelopment projects □ Direct Discharge Exemption □ Other___________________ □ Project qualifies for 0.1 cfs Exception per KCSWDM 1.2.3 □ No flow control required per approved KCSWDM Adjustment No.________________ □ Flow control provided in regional/shared facility per approved approved KCSWDM Adjustment No.________________ Shared Facility Name/Locati nn____________________ □ No flow control required (other, provide justification): TREATMENT SUMMARY FOR TOTAL IMPERVIOUS SURFACES (Applies to Commercial parcels only)Area % of Total Total Acreage (ac) Total Impervious Acreage (ac) Total impervious surface served by flow control facility(ies) (sq ft) Impervious surface served by flow control facility(ies) designed 1990 or later (sq ft) Impervious surface served by pervious surface absorption (sq ft) Impervious surface served by approved water quality facility(ies) (sq ft) PROVIDE FACILITY DETAILS AND FACILITY SKETCH FOR EACH FACILITY ON REVERSE. USE ADDITIONAL SHEETS AS NEEDED FOR ADDITIONAL FACILITIES 2021 KING COUNTY SURFACE WATER DESIGN MANUAL, REFERENCE D 7/23/2021 Page 1 RSD Transportation Expansion 420 Park Ave N, Renton, WA 98057 East Lake Washington - Renton Cedar River / Lake Washington N/A N/A 1 7224000676, 7224000675, 7564600105 0 0 0.488 0.368 75.4 0 0 0 0 15,339 95.7 N/A STORMWATER FACILITY PRELIMINARY SUMMARY SHEET TBD STORMWATER FACILITY SUMMARY SHEET DPER Permit No. ( provide one Stormwater Facility Summary Sheet per Natural Discharge Location) Project Name Project Location Downstream Drainage Basins: Major Basin Nam__________ Immediate Basin Nam______ FLOW CONTROL FACILITY: Basin: Facility Name/Number___________________________________□ New Facility □ Existing FacilityFacility Location UIC? □ yes □ no UIC Site ID: Live Storage □ cu.ft. Volume □ ac.ft. Live Storage Depth (ft) Volume Factor of Safety ______ Project Impervious Acres Served % of Total Project Impervious Acres Served No. of Lots Served Control Structure location:_ Type of Control Structure: □ Riser in vault □ Riser in Type II CB □ Weir in Type II CB No. of Orifices/Restrictions Size of Orifice/Restriction (in.) (numbered starting with lowest orifice): (inches in decimal format) N o . 1 No.2 No.3 No.4 Dam Safety Regulations (WA State Dept of Ecology): Re servoir Volume above natural grade □ cu.ft. □ ac.ft. Depth of Reservoir above natural grade (ft) WATER QUALITY FACILITIES Indicate no. of water quality facilities/BMPs for each type: _____Flow dispersion _____Filter strip _____Biofiltration swale □ regular, □ wet or □ continuous inflow _____Wetvault □ combined w/detention _____Wetpond □ basic □ large □ combined w/detention _____Pre-settling pond Design Information Water Quality design flow (cfs) Water Quality treated volume (sandfilter) (cu.ft.) Water Quality storage volume (wetpool) (cu.ft.) □ Landscape management plan □ Farm management plan High flow bypass structure (e.g., flow-splitter catch basin) Oil/water separator □ baffle □ coalescing plate _torm filter Stormwater wetland Sand filter □ basic □ large Sand bed depth Catch basin inserts (Manufacturer: ) □ regular □ linear □ vault (inches)__urce controls • Is facility lined? □ yes □ no If so, what marker is used above liner?What type of liner is used? Facility Summary Sheet Sketch: All detention, infiltration and water quality facilities must include a detailed sketch (11"x17" reduced size plan sheets preferred). 2021 KING COUNTY SURFACE WATER DESIGN MANUAL, REFERENCE D 7/23/2021 Page 2 RSD Transportation Expansion 420 Park Ave N, Renton, WA 98057 East Lake Washington - Renton Cedar River / Lake Washington N/A 1 STORMWATER FACILITY PRELIMINARY SUMMARY SHEET FILTERRA N/A 0.03 1 CONTECH CDS Pa r k A v e N o r t h North 5th Street Ga r d e n A v e N o r t h X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X SD SD SD SD SD SD SD E E E E E E E E E E E E CO M CO M CO M CO M CO M CO M CO M CO M CO M CO M CO M CO M CR E E E E E E E E E E E E E E EE E E E E E E E E EEEEEEEEEE E CA =ONING PARCEL PROPOSED PAR.ING LOT E;PANSION E;ISTING PAR.ING LOT DRIVEWA< CUR% CUT GATED E;ISTING SECURIT< GATE NO PU%LIC ACCESS %E<OND THIS POINT APPRO;IMATE PROPERT< LINE TO %E SURVE<ED E;ISTING STA)) AND )LEET VEHICLE PAR.ING LOT E;ISTING %US PAR.ING LOT IL =ONING PARCEL IL =ONING PARCEL IL =ONING PARCEL NEW LIGHT POLE PER ELEC L PLANS CA =ONING PARCEL SD A C% T<PE P PRIVATE RIM IE OUT NE SEE DETAIL T<P SD A C% T<PE P PRIVATE RIM IE IN SW IE IN E IE OUT N SD A C% T<PE P PRIVATE RIM IE OUT W SD A C% T<PE II PRIVATE CONTECH CDSC RIM IE IN W IE OUT E SEE DETAIL SD A )ILTERRA PRIVATE RIM IE IN W IE OUT NE SEE DETAIL L) SD # PRIVATE L ) SD # PR I V A T E L ) SD # P R I V A T E L) SD # PRIVATE L) SD # PRIVATE CONNECT TO E; CATCH %ASIN IE PRIVATE UTILIT< ;ING TOP SS %OT C% C C E;ISTING VISITOR PAR.ING LOT EV CHARGING STATION POWER POC PER ELEC L PLANS EV READ< CHARGING STATIONS PER ELEC L PLANS EV IN)RASTRUCTURE TO %E PROVIDED )OR )UTURE EV CHARGING STATIONS PER ELEC L PLANS T<P UON UTILIT< ;ING NEW SD IE TOP SS INSTALL ETHA)OAM PAD )OR PIPE CLEARANCE LESS THAN SEE DETAIL C E; LIGHT POLE E; LIGHT POLE ACCESSI%LE EV READ< CHARGING STATION PER ELEC L PLANS C SD A C% T<PE I PRIVATE RIM IE IN S IE OUT E L) SD # PRIVATE 43667 NSTATE OF WASHIN GTON REGISTERE D PROF ESSIONAL EN GINEER O S B O CAJA.DLAREJ CITY OF RENTON IN COMPLIANCE WITH CITY OF RENTON STANDARDS TE D - 4 0 - 4 3 4 3 C2 5 0 0 1 1 0 4 LU A 2 4 - 0 0 0 3 7 6 PR 2 4 - 0 0 0 0 7 9 g. 8-1-1 Call before you D or 1-800-424-5555 UNDERGROUND SERVICE (USA) R SCALE 1"=20' RSD TRANSPORTATION EXPANSION STORM DRAINAGE AND UTILITY PLAN SE 1/4 SECTION 08, T. 23 N., R. 5 E., W.M. LEGENDLEGEND NOTE: FOR CATCH BASINS TO BE ADJUSTED (RAISED) TO FINISH GRADE WHERE INDICATED ON PLANS, SHIMS ARE NOT ALLOWED PER CITY OF RENTON; CONTRACTOR SHALL USE CONCRETE COLLARS R-434309 FOR TYPICAL TRENCH AND BACKFILL FOR STORM PIPING, SEE DETAIL 7/C410. FOR CITY OF RENTON SURFACE WATER STANDARD PLAN NOTES, SEE SHEET C001 NOTE: DETENTION NOT REQUIRED BECAUSE STORMWATER IS COLLECTED ON-SITE THEN CONNECTED TO EXISTING PIPED CONVEYANCE SYSTEM IN N 5TH ST. STORMWATER IS THEN CONVEYED WEST ALONG N 5TH ST TO BURNETT AVE N, THEN NORTH TO N 6TH ST, THEN WEST ALONG N 6TH ST UNTIL STORMWATER OUTFALLS INTO THE CEDAR RIVER, WHICH FLOWS NORTH AND DRAINS INTO LAKE WASHINGTON. PROPERT< LINE STORM DRAINAGE PIPE SD )H)DCPIVVALVE WATER VAULTMETER )H )DC PIV WV WATER LINE W C% T<PE C% T<PE AREA DRAINSDCO LANDSCAPE AREAS SHALL HAVE SOILS AMENDED, SEE DETAIL 7/C411. NOTE: SEE ELECTRICAL PLANS FOR ELECTRIC VEHICLE (EV) PARKING SPACES AND CHARGING STATIONS VAULTS, CONDUITS, INFRASTRUCTURE, AND POWER REQUIREMENTS, INCLUDING POWER POINT OF CONNECTION. SEE SHEET C420 FOR STORM DRAINAGE PROFILES WATER QUALITY FACILITY NOTE: THIS SHEET HAS BEEN RESIZED TO BE 11X17 AND IS NOT TO SCALE PRESETTLING FACILITY Page 1 of ___ Return Address: City Clerk’s Office City of Renton 1055 S Grady Way Renton, WA 98057 DECLARATION OF COVENANT FOR INSPECTION AND MAINTENANCE OF DRAINAGE FACILITIES AND ON-SITE BMPS Grantor: Grantee: City of Renton, a Washington municipal corporation Legal Description: Assessor's Tax Parcel ID#: IN CONSIDERATION of the approved City of Renton (check one of the following) Residential Building Permit Commercial Building Permit Clearing and Grading Permit Civil Construction or Utility Permit for Permit(s)_____________________ (Construction/Building/Utility Permit #) relating to the real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby covenants (covenant) with the City of Renton (“City of Renton” or “City”), a municipal corporation of the state of Washington, that he/she (they) will observe, consent to, and abide by the conditions and obligations set forth and described in Paragraphs 1 through 9 below with regard to the Property, and hereby grants (grant) an easement as described in Paragraphs 2 and 3. Grantor(s) hereby grants (grant), covenants (covenant), and agrees (agree) as follows: 1.The Grantor(s) or his/her (their) successors in interest and assigns ("Owners ") shall at their own cost, operate, maintain, and keep in good repair, the Property's drainage facilities constructed as required in the approved construction plans and specifications __________________ (Project Plan #) on file with the City of Renton and submitted to the City of Renton for the review and approval of permit(s) _____________________________ (Construction/Building/Utility Permit #). The Property's drainage facilities are shown and/or listed on Exhibit A – Site Plan. The Property’s drainage facilities shall be maintained in compliance with the operation and maintenance schedule included and attached herein as Exhibit B – Operations and Maintenance. Drainage facilities include pipes, channels, flow control facilities, water quality facilities, on-site best management practices (BMPs) and other engineered structures designed to manage and/or Page 2 of ___ treat stormwater on the Property. On-site BMPs include dispersion and infiltration devices, bioretention, permeable pavements, rainwater harvesting systems, tree retention credit, reduced impervious surface footprint, vegetated roofs and other measures designed to mimic pre-developed hydrology and minimize stormwater runoff on the Property. 2.City of Renton shall have the right to ingress and egress over those portions of the Property necessary to perform inspections of the stormwater facilities and BMPs and conduct maintenance activities specified in this Declaration of Covenant and in accordance with the Renton Municipal Code. City of Renton shall provide at least thirty (30) days written notice to the Owners that entry on the Property is planned for the inspection of drainage facilities. After the thirty (30) days, the Owners shall allow the City of Renton to enter for the sole purpose of inspecting drainage facilities. In lieu of inspection by the City, the Owners may elect to engage a licensed civil engineer registered in the state of Washington who has expertise in drainage to inspect the drainage facilities and provide a written report describing their condition. If the engineer option is chosen, the Owners shall provide written notice to the City of Renton within fifteen (15) otice of inspection. Within thirty (30) days of giving this report to the City of Renton. If the report is not provided in a timely manner as specified above, the City of Renton may inspect the drainage facilities without further notice. 3.If City of Renton determines accordance with Paragraph 2, that maintenance, repair, restoration, and/or mitigation work is required to be done to any of the drainage facilities, City of Renton shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work (Work ) required pursuant to the Renton Municipal Code. The City shall also set a reasonable deadline for the Owners to complete th the Work. After the deadline has passed, the Owners shall allow the City access to re-inspect the Work. If the Work is not completed within the time frame set by the City, the City may initiate an enforcement action and/or perform the Work and hereby is given access to the Property for such purposes. intention to perform such Work. This Work will not commence until at least seven (7) days after such notice is mailed. If, within the sole discretion of the City, there exists an imminent or present danger, the seven (7) day notice period will be waived and Work will begin immediately. 4.The Owners shall assume all responsibility for the cost of any Work, or any measures taken by the City to address conditions as described in Paragraph 3. Such responsibility shall include reimbursement to the City within thirty (30) days of the receipt of the invoice for any such Work performed. Overdue payments will require payment of interest at the maximum legal rate allowed by RCW 19.52.020 (currently twelve percent (12%)). If the City initiates legal action to enforce this agreement, the prevailing party in such action is entitled to recover reasonable 5.The Owners are required to obtain written approval from City of Renton prior to filling, piping, cutting, or removing vegetation (except in routine landscape maintenance) in open vegetated stormwater facilities (such as swales, channels, ditches, ponds, etc.), or performing any alterations or modifications to the drainage facilities referenced in this Declaration of Covenant. Page 3 of ___ 6.Any notice or consent required to be given or otherwise provided for by the provisions of this Agreement shall be effective upon personal delivery, or three (3) days after mailing by Certified Mail, return receipt requested. 7.With regard to the matters addressed herein, this agreement constitutes the entire agreement between the parties, and supersedes all prior discussions, negotiations, and all agreements whatsoever whether oral or written. 8.This Declaration of Covenant is intended to protect the value and desirability and promote efficient and effective management of surface water drainage of the real property described above, and shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This Declaration of Covenant shall run with the land and be binding upon Grantor(s), and Grantor's(s') successors in interest, and assigns. 9.This Declaration of Covenant may be terminated by execution of a written agreement by the Owners and the City that is recorded by King County in its real property records. IN WITNESS WHEREOF, this Declaration of Covenant for the Inspection and Maintenance of Drainage Facilities is executed this _____ day of ____________________, 20_____. GRANTOR, owner of the Property GRANTOR, owner of the Property STATE OF WASHINGTON ) COUNTY OF KING )ss. On this day personally appeared before me: , to me known to be the individual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this _____ day of ___________________, 20_____. Printed name Notary Public in and for the State of Washington, residing at My appointment expires Damien Pattenaude Superintendent Renton School District No. 403 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X SD SD SD SD SD SD SD 39 FILTERRA WATER QUALITY TREATMENT UNIT EXHIBIT A - SITE PLAN Page 5 of 4 N 5TH ST PA R K A V E N AMENDED SOIL AT ALL NEW AND REPLACED LANDSCAPE AREAS CDS SEPARATOR EXHIBIT B - OPERATIONS AND MAINTENANCE 39Page 5 of ® Filterra® Maintenance Steps Contech has created a network of Certified Maintenance Providers (CCMP’s) to provide maintenance on Filterra systems. To find a CCMP in your area please visit www.conteches.com/maintenance 1. Inspection of Filterra and surrounding area 2. Removal of tree grate and erosion control stones 3. Removal of debris, trash and mulch 4. Mulch replacement 5. Clean area around Filterra 6. Complete paperwork and record plant height and width © 2015 Contech Engineered Solutions LLC ENGINEERED SOLUTIONS 39Page 5 of 6 ® Filterra® Maintenance Steps Contech has created a network of Certified Maintenance Providers (CCMP’s) to provide maintenance on Filterra systems. To find a CCMP in your area please visit www.conteches.com/maintenance 1. Inspection of Filterra and surrounding area 2. Removal of tree grate and erosion control stones 3. Removal of debris, trash and mulch 4. Mulch replacement 5. Clean area around Filterra 6. Complete paperwork and record plant height and width © 2015 Contech Engineered Solutions LLC ENGINEERED SOLUTIONS MAINTENANCE INSTRUCTIONS FOR FILTERRA VAULT Filterra Vault Owner’s Manual (Precast Vault Configurations) ® Bioretention Systems ENGINEERED SOLUTIONS This Owner’s Manual applies to all precast Filterra Configurations, including Filterra Bioscape Vault and Filterra HC. 39Page 5 of 7 Filterra Vault Owner’s Manual (Precast Vault Configurations) ® Bioretention Systems ENGINEERED SOLUTIONS This Owner’s Manual applies to all precast Filterra Configurations, including Filterra Bioscape Vault and Filterra HC.This Owner's Manual Applies to all precast Filterra Configurations, including Filterra Bioscape Vault and Filterra HC. 39Page 5 of 8 www.ContechES.com/filterra | 800-338-1122 3 Table of Contents Introduction ................................................................................4 Activation Overview .....................................................................4 Filterra Plant Selection Overview ...................................................6 Warranty Overview ......................................................................6 Routine Maintenance Guidelines...................................................6 Maintenance Visit Procedure .........................................................9 Plant Care ................................................................................11 Appendix 1 – Activation Package ................................................12 Appendix 2 – Filterra Tree Grate Opening Expansion Procedure..... 19 ® Bioretention Systems ENGINEERED SOLUTIONS 39Page 5 of 9 www.ContechES.com/filterra | 800-338-1122 3 Table of Contents Introduction ................................................................................4 Activation Overview .....................................................................4 Filterra Plant Selection Overview ...................................................6 Warranty Overview ......................................................................6 Routine Maintenance Guidelines...................................................6 Maintenance Visit Procedure .........................................................9 Plant Care ................................................................................11 Appendix 1 – Activation Package ................................................12 Appendix 2 – Filterra Tree Grate Opening Expansion Procedure..... 19 ® Bioretention Systems ENGINEERED SOLUTIONS www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-11224 Introduction Thank you for your purchase of the Filterra® Bioretention System. Filterra is a specially engineered stormwater treatment system incorporating high performance biofiltration media to remove pollutants from stormwater runoff. The system’s biota (vegetation and soil microorganisms) then further breakdown and absorb captured pollutants. All components of the system work together to provide a sustainable long-term solution for treating stormwater runoff. The Filterra system has been delivered to you with protection in place to resist intrusion of construction related sediment which can contaminate the biofiltration media and result in inadequate system performance. These protection devices are intended as a best practice and cannot fully prevent contamination. It is the purchaser’s responsibility to provide adequate measures to prevent construction related runoff from entering the Filterra system. Included with your purchase is Activation of the Filterra system by the manufacturer as well as a 1-year warranty from delivery of the system and a final site assessment of unit condition (mulch replacement, debris removal, and pruning of vegetation) scheduled between 6 and 12 months after activation, upon request. Design and Installation Each project presents different scopes for the use of Filterra systems. Information and help may be provided to the design engineer during the planning process. Correct Filterra box sizing (by rainfall region) is essential to predict pollutant removal rates for a given area. The engineer shall submit calculations for approval by the local jurisdiction. The contractor is responsible for the correct installation of Filterra units as shown in approved plans. A comprehensive installation manual is available at www.ContechES.com. Activation Overview Activation of the Filterra system is a procedure completed by the manufacturer to place the system into working condition. This involves the following items: • Removal of construction runoff protection devices. • Planting of the system’s vegetation (provided by the purchaser). • Placement of pretreatment mulch layer using mulch acceptable for use in Filterra systems. Activation MUST be provided by the manufacturer to ensure proper site conditions are met for Activation, proper installation of the vegetation, and use of pretreatment mulch acceptable for use in Filterra systems. More information is available in the Filterra Activation Package. 39Page 5 of 10 of www.ContechES.com/filterra | 800-338-11224 Introduction Thank you for your purchase of the Filterra® Bioretention System. Filterra is a specially engineered stormwater treatment system incorporating high performance biofiltration media to remove pollutants from stormwater runoff. The system’s biota (vegetation and soil microorganisms) then further breakdown and absorb captured pollutants. All components of the system work together to provide a sustainable long-term solution for treating stormwater runoff. The Filterra system has been delivered to you with protection in place to resist intrusion of construction related sediment which can contaminate the biofiltration media and result in inadequate system performance. These protection devices are intended as a best practice and cannot fully prevent contamination. It is the purchaser’s responsibility to provide adequate measures to prevent construction related runoff from entering the Filterra system. Included with your purchase is Activation of the Filterra system by the manufacturer as well as a 1-year warranty from delivery of the system and a final site assessment of unit condition (mulch replacement, debris removal, and pruning of vegetation) scheduled between 6 and 12 months after activation, upon request. Design and Installation Each project presents different scopes for the use of Filterra systems. Information and help may be provided to the design engineer during the planning process. Correct Filterra box sizing (by rainfall region) is essential to predict pollutant removal rates for a given area. The engineer shall submit calculations for approval by the local jurisdiction. The contractor is responsible for the correct installation of Filterra units as shown in approved plans. A comprehensive installation manual is available at www.ContechES.com. Activation Overview Activation of the Filterra system is a procedure completed by the manufacturer to place the system into working condition. This involves the following items: • Removal of construction runoff protection devices. • Planting of the system’s vegetation (provided by the purchaser). • Placement of pretreatment mulch layer using mulch acceptable for use in Filterra systems. Activation MUST be provided by the manufacturer to ensure proper site conditions are met for Activation, proper installation of the vegetation, and use of pretreatment mulch acceptable for use in Filterra systems. More information is available in the Filterra Activation Package. www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-1122 5 Minimum Requirements The minimum requirements for Filterra Activation are as follows: 1. The purchaser must have procured vegetation meeting the requirements outlined in the Filterra Activation Package. 2. The site landscaping must be fully stabilized, i.e. full landscaping installed and some grass cover (not just straw and seed) is required to reduce sediment transport. Construction debris and materials should be removed from surrounding area. 3. Final paving must be completed. Final paving ensures that paving materials will not enter and contaminate the Filterra system during the paving process, and that the plant will receive runoff from the drainage area, assisting with plant survival for the Filterra system. 4. Filterra throat opening should be at least 4” in order to ensure adequate capacity for inflow and debris. The Filterra Activation Package is available on the Contech website (www.ContechES.com/filterra) and ensures that the proper conditions are met for Contech to perform the Activation service. Vegetation meeting Contech’s requirements must be provided at time of Activation. If the site does not meet the conditions required for Activation, or acceptable vegetation is not provided by the purchaser at time of Activation, a charge of $1,500 will be invoiced to the purchaser. 39Page 5 of 11 of www.ContechES.com/filterra | 800-338-1122 5 Minimum Requirements The minimum requirements for Filterra Activation are as follows: 1. The purchaser must have procured vegetation meeting the requirements outlined in the Filterra Activation Package. 2. The site landscaping must be fully stabilized, i.e. full landscaping installed and some grass cover (not just straw and seed) is required to reduce sediment transport. Construction debris and materials should be removed from surrounding area. 3. Final paving must be completed. Final paving ensures that paving materials will not enter and contaminate the Filterra system during the paving process, and that the plant will receive runoff from the drainage area, assisting with plant survival for the Filterra system. 4. Filterra throat opening should be at least 4” in order to ensure adequate capacity for inflow and debris. The Filterra Activation Package is available on the Contech website (www.ContechES.com/filterra) and ensures that the proper conditions are met for Contech to perform the Activation service. Vegetation meeting Contech’s requirements must be provided at time of Activation. If the site does not meet the conditions required for Activation, or acceptable vegetation is not provided by the purchaser at time of Activation, a charge of $1,500 will be invoiced to the purchaser. www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-11226 Filterra Plant Selection Overview A Plant List is available on the Contech website highlighting recommended plants for Filterra systems in your area. Keep in mind that plants are subject to availability due to seasonality and required minimum size for the Filterra system. Plants installed in the Filterra system are container plants (max 15 gallon) from nursery stock and will be immature in height and spread at Activation. It is the responsibility of the owner to provide adequate irrigation when necessary to the plant of the Filterra system. More information is available in the Filterra Activation Package. Warranty Overview Refer to the Contech Engineered Solutions LLC Stormwater Treatment System LIMITED WARRANTY for further information. The following conditions may void the Filterra system’s warranty and waive the manufacturer provided Activation and Final Site Assessment services: • Unauthorized activation or performance of any of the items listed in the activation overview • Any tampering, modifications or damage to the Filterra system or runoff protection devices • Removal of any Filterra system components • Failure to prevent construction related runoff from entering the Filterra system • Failure to properly store and protect any Filterra components (including media and underdrain stone) that may be shipped separately from the vault Final Site Assessment With proper routine maintenance, the biofiltration media within the Filterra system should last as long as traditional bioretention media. A final site assessment is included by the manufacturer, upon request, on all Filterra systems between 6 and 12 months after activation. This includes a final assessment of unit condition, debris removal, mulch replacement, and pruning of vegetation. More information is provided in the Operations and Maintenance Guidelines. Some Filterra systems also contain pretreatment or outlet bays. Depending on site pollutant loading, these bays may require periodic removal of debris, however this is not included in the final site assessment, and would likely not be required within the first year of operation. These services, as well as routine maintenance outside of the included first year, can be provided by certified maintenance providers listed on the Contech website. Training can also be provided to other stormwater maintenance or landscape providers. 39Page 5 of 12 of www.ContechES.com/filterra | 800-338-11226 Filterra Plant Selection Overview A Plant List is available on the Contech website highlighting recommended plants for Filterra systems in your area. Keep in mind that plants are subject to availability due to seasonality and required minimum size for the Filterra system. Plants installed in the Filterra system are container plants (max 15 gallon) from nursery stock and will be immature in height and spread at Activation. It is the responsibility of the owner to provide adequate irrigation when necessary to the plant of the Filterra system. More information is available in the Filterra Activation Package. Warranty Overview Refer to the Contech Engineered Solutions LLC Stormwater Treatment System LIMITED WARRANTY for further information. The following conditions may void the Filterra system’s warranty and waive the manufacturer provided Activation and Final Site Assessment services: • Unauthorized activation or performance of any of the items listed in the activation overview • Any tampering, modifications or damage to the Filterra system or runoff protection devices • Removal of any Filterra system components • Failure to prevent construction related runoff from entering the Filterra system • Failure to properly store and protect any Filterra components (including media and underdrain stone) that may be shipped separately from the vault Final Site Assessment With proper routine maintenance, the biofiltration media within the Filterra system should last as long as traditional bioretention media. A final site assessment is included by the manufacturer, upon request, on all Filterra systems between 6 and 12 months after activation. This includes a final assessment of unit condition, debris removal, mulch replacement, and pruning of vegetation. More information is provided in the Operations and Maintenance Guidelines. Some Filterra systems also contain pretreatment or outlet bays. Depending on site pollutant loading, these bays may require periodic removal of debris, however this is not included in the final site assessment, and would likely not be required within the first year of operation. These services, as well as routine maintenance outside of the included first year, can be provided by certified maintenance providers listed on the Contech website. Training can also be provided to other stormwater maintenance or landscape providers. www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-1122 7 Why Maintain? All stormwater treatment systems require maintenance for effective operation. This necessity is often incorporated in your property’s permitting process as a legally binding BMP maintenance agreement. Other reasons to maintain are: • Avoiding legal challenges from your jurisdiction’s maintenance enforcement program. • Prolonging the expected lifespan of your Filterra media. • Avoiding more costly media replacement. • Helping reduce pollutant loads leaving your property. Simple maintenance of the Filterra is required to continue effective pollutant removal from stormwater runoff before discharge into downstream waters. This procedure will also extend the longevity of the living biofilter system. The unit will recycle and accumulate pollutants within the biomass, but is also subjected to other materials entering the inlet. This may include trash, silt and leaves etc. which will be contained above the mulch layer. Too much silt may inhibit the Filterra’s flow rate, which is the reason for site stabilization before activation. Regular replacement of the mulch stops accumulation of such sediment. When to Maintain? Maintenance visits are scheduled seasonally; the spring visit aims to clean up after winter loads including salts and sands while the fall visit helps the system by removing excessive leaf litter. It has been found that in regions which receive between 30-50 inches of annual rainfall, (2) two visits are generally required; in regions with less rainfall often only (1) one visit per annum is sufficient. Varying land uses can affect maintenance frequency. Contributing drainage areas which are subject to new development wherein the recommended erosion and sediment control measures have not been implemented may require additional maintenance visits. Some sites may be subjected to extreme sediment or trash loads, requiring more frequent maintenance visits. This is the reason for detailed notes of maintenance actions per unit, helping the Supplier and Owner predict future maintenance frequencies, reflecting individual site conditions. Owners must promptly notify the maintenance provider of any damage to the plant(s), which constitute(s) an integral part of the bioretention technology. www.ContechES.com/filterra | 800-338-1122 7 Why Maintain? All stormwater treatment systems require maintenance for effective operation. This necessity is often incorporated in your property’s permitting process as a legally binding BMP maintenance agreement. Other reasons to maintain are: • Avoiding legal challenges from your jurisdiction’s maintenance enforcement program. • Prolonging the expected lifespan of your Filterra media. • Avoiding more costly media replacement. • Helping reduce pollutant loads leaving your property. Simple maintenance of the Filterra is required to continue effective pollutant removal from stormwater runoff before discharge into downstream waters. This procedure will also extend the longevity of the living biofilter system. The unit will recycle and accumulate pollutants within the biomass, but is also subjected to other materials entering the inlet. This may include trash, silt and leaves etc. which will be contained above the mulch layer. Too much silt may inhibit the Filterra’s flow rate, which is the reason for site stabilization before activation. Regular replacement of the mulch stops accumulation of such sediment. When to Maintain? Maintenance visits are scheduled seasonally; the spring visit aims to clean up after winter loads including salts and sands while the fall visit helps the system by removing excessive leaf litter. It has been found that in regions which receive between 30-50 inches of annual rainfall, (2) two visits are generally required; in regions with less rainfall often only (1) one visit per annum is sufficient. Varying land uses can affect maintenance frequency. Contributing drainage areas which are subject to new development wherein the recommended erosion and sediment control measures have not been implemented may require additional maintenance visits. Some sites may be subjected to extreme sediment or trash loads, requiring more frequent maintenance visits. This is the reason for detailed notes of maintenance actions per unit, helping the Supplier and Owner predict future maintenance frequencies, reflecting individual site conditions. Owners must promptly notify the maintenance provider of any damage to the plant(s), which constitute(s) an integral part of the bioretention technology. www.ContechES.com/filterra | 800-338-1122 Page 5 of 13 of 39 www.ContechES.com/filterra | 800-338-11228 Exclusion of Services Clean up due to major contamination such as oils, chemicals, toxic spills, etc. will result in additional costs and are not included as part of the final site assessment. Should a major contamination event occur the Owner must block off the outlet pipe of the Filterra (where the cleaned runoff drains to, such as drop inlet) and block off the throat of the Filterra. The Supplier should be informed immediately. Maintenance Visit Summary Each maintenance visit consists of the following simple tasks (detailed instructions below). 1. Inspection of Filterra and surrounding area 2. Removal of tree grate and erosion control stones 3. Removal of debris, trash and mulch 4. Mulch replacement 5. Plant health evaluation and pruning or replacement as necessary 6. Clean area around Filterra 7. Complete paperwork Maintenance Tools, Safety Equipment and Supplies Ideal tools include: camera, bucket, shovel, broom, pruners, hoe/rake, and tape measure. Appropriate Personal Protective Equipment (PPE) should be used in accordance with local or company procedures. This may include impervious gloves where the type of trash is unknown, high visibility clothing and barricades when working in close proximity to traffic and also safety hats and shoes. A T-Bar or crowbar should be used for moving the tree grates (up to 170 lbs ea.). Most visits require minor trash removal and a full replacement of mulch. See below for actual number of bagged mulch that is required in each media bay size. Mulch should be a double shredded, hardwood variety. Some visits may require additional Filterra engineered soil media available from the Supplier. Box Length Box Width Filter Surface Area (ft²)Volume at 3” (ft³)# of 2 ft³ Mulch Bags 4 4 16 4 2 6 4 24 6 3 8 4 32 8 4 6 6 36 9 5 8 6 48 12 6 10 6 60 15 8 12 6 72 18 9 13 7 91 23 12 Other sizes not listed - 1 bag per 8 ft2 of media. Page 5 of www.ContechES.com/filterra | 800-338-11228 Exclusion of Services Clean up due to major contamination such as oils, chemicals, toxic spills, etc. will result in additional costs and are not included as part of the final site assessment. Should a major contamination event occur the Owner must block off the outlet pipe of the Filterra (where the cleaned runoff drains to, such as drop inlet) and block off the throat of the Filterra. The Supplier should be informed immediately. Maintenance Visit Summary Each maintenance visit consists of the following simple tasks (detailed instructions below). 1. Inspection of Filterra and surrounding area 2. Removal of tree grate and erosion control stones 3. Removal of debris, trash and mulch 4. Mulch replacement 5. Plant health evaluation and pruning or replacement as necessary 6. Clean area around Filterra 7. Complete paperwork Maintenance Tools, Safety Equipment and Supplies Ideal tools include: camera, bucket, shovel, broom, pruners, hoe/rake, and tape measure. Appropriate Personal Protective Equipment (PPE) should be used in accordance with local or company procedures. This may include impervious gloves where the type of trash is unknown, high visibility clothing and barricades when working in close proximity to traffic and also safety hats and shoes. A T-Bar or crowbar should be used for moving the tree grates (up to 170 lbs ea.). Most visits require minor trash removal and a full replacement of mulch. See below for actual number of bagged mulch that is required in each media bay size. Mulch should be a double shredded, hardwood variety. Some visits may require additional Filterra engineered soil media available from the Supplier. Box Length Box Width Filter Surface Area (ft²)Volume at 3” (ft³)# of 2 ft³ Mulch Bags 4 4 16 4 2 6 4 24 6 3 8 4 32 8 4 6 6 36 9 5 8 6 48 12 6 10 6 60 15 8 12 6 72 18 9 13 7 91 23 12 Other sizes not listed - 1 bag per 8 ft2 of media. 14 of 39 www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-1122 9 1. Inspection of Filterra and surrounding area • Record individual unit before maintenance with photograph (numbered). Record on Maintenance Report (see example in this document) the following: 2. Removal of tree grate and erosion control stones • Remove cast iron grates for access into Filterra box. • Dig out silt (if any) and mulch and remove trash & foreign items. 3. Removal of debris, trash and mulch • After removal of mulch and debris, measure distance from the top of the Filterra engineered media soil to the top of the top slab. Compare the measured distance to the distance shown on the approved Contract Drawings for the system. Add Filterra media (not top soil or other) to bring media up as needed to distance indicated on drawings. Record on Maintenance Report the following: Standing Water yes | no Damage to Box Structure yes | no Damage to Grate yes | no Is Bypass Clear yes | no If yes answered to any of these observations, record with close-up photograph (numbered). Record on Maintenance Report the following: Silt/Clay yes | no Cups/ Bags yes | no Leaves yes | no Buckets Removed ________ Record on Maintenance Report the following: Distance to Top of Top Slab (inches) ________ Inches of Media Added ________ Maintenance Visit Procedure Keep sufficient documentation of maintenance actions to predict location specific maintenance frequencies and needs. An example Maintenance Report is included in this manual. Page 5 of 15 of 39 www.ContechES.com/filterra | 800-338-1122 9 1. Inspection of Filterra and surrounding area • Record individual unit before maintenance with photograph (numbered). Record on Maintenance Report (see example in this document) the following: 2. Removal of tree grate and erosion control stones • Remove cast iron grates for access into Filterra box. • Dig out silt (if any) and mulch and remove trash & foreign items. 3. Removal of debris, trash and mulch • After removal of mulch and debris, measure distance from the top of the Filterra engineered media soil to the top of the top slab. Compare the measured distance to the distance shown on the approved Contract Drawings for the system. Add Filterra media (not top soil or other) to bring media up as needed to distance indicated on drawings. Record on Maintenance Report the following: Standing Water yes | no Damage to Box Structure yes | no Damage to Grate yes | no Is Bypass Clear yes | no If yes answered to any of these observations, record with close-up photograph (numbered). Record on Maintenance Report the following: Silt/Clay yes | no Cups/ Bags yes | no Leaves yes | no Buckets Removed ________ Record on Maintenance Report the following: Distance to Top of Top Slab (inches) ________ Inches of Media Added ________ Maintenance Visit Procedure Keep sufficient documentation of maintenance actions to predict location specific maintenance frequencies and needs. An example Maintenance Report is included in this manual. www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-112210 4. Mulch replacement • Add double shredded mulch evenly across the entire unit to a depth of 3”. • Refer to Filterra Mulch Specifications for information on acceptable sources. • Ensure correct repositioning of erosion control stones by the Filterra inlet to allow for entry of trash during a storm event. • Replace Filterra grates correctly using appropriate lifting or moving tools, taking care not to damage the plant. 5. Plant health evaluation and pruning or replacement as necessary • Examine the plant’s health and replace if necessary. • Prune as necessary to encourage growth in the correct directions 6. Clean area around Filterra • Clean area around unit and remove all refuse to be disposed of appropriately. 7. Complete paperwork • Deliver Maintenance Report. • Some jurisdictions may require submission of maintenance reports in accordance with approvals. It is the responsibility of the Owner to comply with local regulations. Record on Maintenance Report the following: Height above Grate _____________________(ft) Width at Widest Point _____________________(ft) Health healthy | unhealthy Damage to Plant yes | no Plant Replaced yes | no Page 5 of 16 of 39 www.ContechES.com/filterra | 800-338-112210 4. Mulch replacement • Add double shredded mulch evenly across the entire unit to a depth of 3”. • Refer to Filterra Mulch Specifications for information on acceptable sources. • Ensure correct repositioning of erosion control stones by the Filterra inlet to allow for entry of trash during a storm event. • Replace Filterra grates correctly using appropriate lifting or moving tools, taking care not to damage the plant. 5. Plant health evaluation and pruning or replacement as necessary • Examine the plant’s health and replace if necessary. • Prune as necessary to encourage growth in the correct directions 6. Clean area around Filterra • Clean area around unit and remove all refuse to be disposed of appropriately. 7. Complete paperwork • Deliver Maintenance Report. • Some jurisdictions may require submission of maintenance reports in accordance with approvals. It is the responsibility of the Owner to comply with local regulations. Record on Maintenance Report the following: Height above Grate _____________________(ft) Width at Widest Point _____________________(ft) Health healthy | unhealthy Damage to Plant yes | no Plant Replaced yes | no www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-1122 11 Plant Care for Filterra® Systems After Activation, the Contractor is responsible for proper care of the vegetation until the site is handed over to the Owner. After that, it is the Site Owner’s responsibility to care for the vegetation. Contech recommends the following care for the plants: 1. To prevent transplant shock (especially if planting takes place in the hot season), it may be necessary to prune some of the foliage to compensate for reduced root uptake capacity. This is accomplished by pruning away some of the smaller secondary branches or a main scaffold branch if there are too many. Too much foliage relative to the root ball can dehydrate and damage the plant. 2. Plant staking may be required. 3. With all trees/shrubs, remove dead, diseased, crossed/ rubbing, sharply crotched branches or branches growing excessively long or in wrong direction compared to majority of branches. 4. Contech recommends irrigation of the Filterra® Vegetation. The following guidance will help to ensure the vegetation is properly irrigated. Irrigation Recommendations: • Each Filterra® system must receive adequate irrigation to ensure survival of the living system during periods of drier weather. • Irrigation sources include rainfall runoff from downspouts and/or gutter flow, applied water through the tree grate or in some cases from an irrigation system with emitters installed during construction. • At Activation: Apply about one (cool climates) to two (warm climates) gallons of water per inch of trunk diameter over the root ball. • During Establishment: In common with all plants, each Filterra® plant will require more frequent watering during the establishment period. One inch of applied water per week for the first three months is recommended for cooler climates (2 to 3 inches for warmer climates). If the system is receiving rainfall runoff from the drainage area, then irrigation may not be needed. Inspection of the soil moisture content can be evaluated by gently brushing aside the mulch layer and feeling the soil. Be sure to replace the mulch when the assessment is complete. Irrigate as needed**. • Established Plants: Established plants have fully developed root systems and can access the entire water column in the media. Therefore irrigation is less frequent but requires more applied water when performed. For a mature system assume 3.5 inches of available water within the media matrix. Irrigation demand can be estimated as 1” of irrigation demand per week. Therefore if dry periods exceed 3 weeks, irrigation may be required. ** Five gallons per square yard approximates 1 inch of water. Therefore for a 6’ x 6 foot Filterra® approximately 20-60 gallons of applied water is needed. To ensure even distribution of water it needs to be evenly sprinkled over the entire surface of the filter bed, with special attention to make sure the root ball is completely wetted. NOTE: if needed, measure the time it takes to fill a five gallon bucket to estimate the applied water flow rate. Then calculate the time needed to irrigate the Filterra®, For example is the flow rate of the sprinkler is 5 gallons/minute then it would take 12 minutes to irrigate a 6’x6’ filter. Plant Replacement: In some cases, plants will require replacement. Please follow the procedures below to ensure a properly functioning Filterra® system. 1. Remove the existing plant, and leave as much of the Filterra® media in place as possible. 2. Select a replacement per the Filterra® Activation Package. 3. Prior to removing the plant from the container, ensure the soil moisture is sufficient to maintain the integrity of the root ball. If needed, pre-wet the container plant. 4. Cut away any roots which are growing out of the container drain holes. 5. Plant(s) should be carefully removed from the pot by gently pounding on the sides of the container with the fist to loosen root ball. Then carefully slide out. Do not lift plant(s) by trunk as this can break roots and cause soil to fall off. Extract the root ball in a horizontal position and support it to prevent it from breaking apart. Alternatively, the pot can be cut away to minimize root ball disturbance. 6. Excavate a hole with a diameter 4” greater than the root ball, gently place the plant(s). 7. Plant the tree/shrub/grass with the top of the root ball 1” above surrounding media to allow for settling. 8. All plants should have the main stem centered in the tree grate (where applicable) upon completion of installation. 9. Reinstall or add mulch to a depth of 3” per Contech’s mulch specifications for Filterra® systems. Page 5 of 17 of 39 www.ContechES.com/filterra | 800-338-1122 11 Plant Care for Filterra® Systems After Activation, the Contractor is responsible for proper care of the vegetation until the site is handed over to the Owner. After that, it is the Site Owner’s responsibility to care for the vegetation. Contech recommends the following care for the plants: 1. To prevent transplant shock (especially if planting takes place in the hot season), it may be necessary to prune some of the foliage to compensate for reduced root uptake capacity. This is accomplished by pruning away some of the smaller secondary branches or a main scaffold branch if there are too many. Too much foliage relative to the root ball can dehydrate and damage the plant. 2. Plant staking may be required. 3. With all trees/shrubs, remove dead, diseased, crossed/ rubbing, sharply crotched branches or branches growing excessively long or in wrong direction compared to majority of branches. 4. Contech recommends irrigation of the Filterra® Vegetation. The following guidance will help to ensure the vegetation is properly irrigated. Irrigation Recommendations: • Each Filterra® system must receive adequate irrigation to ensure survival of the living system during periods of drier weather. • Irrigation sources include rainfall runoff from downspouts and/or gutter flow, applied water through the tree grate or in some cases from an irrigation system with emitters installed during construction. • At Activation: Apply about one (cool climates) to two (warm climates) gallons of water per inch of trunk diameter over the root ball. • During Establishment: In common with all plants, each Filterra® plant will require more frequent watering during the establishment period. One inch of applied water per week for the first three months is recommended for cooler climates (2 to 3 inches for warmer climates). If the system is receiving rainfall runoff from the drainage area, then irrigation may not be needed. Inspection of the soil moisture content can be evaluated by gently brushing aside the mulch layer and feeling the soil. Be sure to replace the mulch when the assessment is complete. Irrigate as needed**. • Established Plants: Established plants have fully developed root systems and can access the entire water column in the media. Therefore irrigation is less frequent but requires more applied water when performed. For a mature system assume 3.5 inches of available water within the media matrix. Irrigation demand can be estimated as 1” of irrigation demand per week. Therefore if dry periods exceed 3 weeks, irrigation may be required. ** Five gallons per square yard approximates 1 inch of water. Therefore for a 6’ x 6 foot Filterra® approximately 20-60 gallons of applied water is needed. To ensure even distribution of water it needs to be evenly sprinkled over the entire surface of the filter bed, with special attention to make sure the root ball is completely wetted. NOTE: if needed, measure the time it takes to fill a five gallon bucket to estimate the applied water flow rate. Then calculate the time needed to irrigate the Filterra®, For example is the flow rate of the sprinkler is 5 gallons/minute then it would take 12 minutes to irrigate a 6’x6’ filter. Plant Replacement: In some cases, plants will require replacement. Please follow the procedures below to ensure a properly functioning Filterra® system. 1. Remove the existing plant, and leave as much of the Filterra® media in place as possible. 2. Select a replacement per the Filterra® Activation Package. 3. Prior to removing the plant from the container, ensure the soil moisture is sufficient to maintain the integrity of the root ball. If needed, pre-wet the container plant. 4. Cut away any roots which are growing out of the container drain holes. 5. Plant(s) should be carefully removed from the pot by gently pounding on the sides of the container with the fist to loosen root ball. Then carefully slide out. Do not lift plant(s) by trunk as this can break roots and cause soil to fall off. Extract the root ball in a horizontal position and support it to prevent it from breaking apart. Alternatively, the pot can be cut away to minimize root ball disturbance. 6. Excavate a hole with a diameter 4” greater than the root ball, gently place the plant(s). 7. Plant the tree/shrub/grass with the top of the root ball 1” above surrounding media to allow for settling. 8. All plants should have the main stem centered in the tree grate (where applicable) upon completion of installation. 9. Reinstall or add mulch to a depth of 3” per Contech’s mulch specifications for Filterra® systems. www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-112212 Maintenance Checklist Filterra Inspection & Maintenance Log Filterra System Size/Model: _____________________________Location: ____________________________________________ Drainage System Failure Problem Conditions to Check Condition that Should Exist Actions Inlet Excessive sediment or trash accumulation. Accumulated sediments or trash impair free flow of water into Filterra. Inlet should be free of obstructions allowing free distributed flow of water into Filterra. Sediments and/or trash should be removed. Mulch Cover Trash and floatable debris accumulation.Excessive trash and/or debris accumulation.Minimal trash or other debris on mulch cover. Trash and debris should be removed and mulch cover raked level. Ensure bark nugget mulch is not used. Mulch Cover “Ponding” of water on mulch cover. “Ponding” in unit could be indicative of clogging due to excessive fine sediment accumulation or spill of petroleum oils. Stormwater should drain freely and evenly through mulch cover. Recommend contact manufacturer and replace mulch as a minimum. Vegetation Plants not growing or in poor condition. Soil/mulch too wet, evidence of spill. Incorrect plant selection. Pest infestation. Vandalism to plants. Plants should be healthy and pest free.Contact manufacturer for advice. Vegetation Plant growth excessive. Plants should be appropriate to the species and location of Filterra. Trim/prune plants in accordance with typical landscaping and safety needs. Structure Structure has visible cracks. Cracks wider than 1/2 inch or evidence of soil particles entering the structure through the cracks. Vault should be repaired. Maintenance is ideally to be performed twice annually. Date Mulch & Debris Removed Depth of Mulch Added Mulch Brand Height of Vegetation Above Grate Vegetation Species Issues with System Comments 1/1/17 5 – 5 gal Buckets 3”Lowe’s Premium Brown Mulch 4’Galaxy Magnolia - Standing water in downstream structure - Removed blockage in downstream structure Page 5 of 18 of 39 www.ContechES.com/filterra | 800-338-112212 Maintenance Checklist Filterra Inspection & Maintenance Log Filterra System Size/Model: _____________________________Location: ____________________________________________ Drainage System Failure Problem Conditions to Check Condition that Should Exist Actions Inlet Excessive sediment or trash accumulation. Accumulated sediments or trash impair free flow of water into Filterra. Inlet should be free of obstructions allowing free distributed flow of water into Filterra. Sediments and/or trash should be removed. Mulch Cover Trash and floatable debris accumulation.Excessive trash and/or debris accumulation.Minimal trash or other debris on mulch cover. Trash and debris should be removed and mulch cover raked level. Ensure bark nugget mulch is not used. Mulch Cover “Ponding” of water on mulch cover. “Ponding” in unit could be indicative of clogging due to excessive fine sediment accumulation or spill of petroleum oils. Stormwater should drain freely and evenly through mulch cover. Recommend contact manufacturer and replace mulch as a minimum. Vegetation Plants not growing or in poor condition. Soil/mulch too wet, evidence of spill. Incorrect plant selection. Pest infestation. Vandalism to plants. Plants should be healthy and pest free.Contact manufacturer for advice. Vegetation Plant growth excessive. Plants should be appropriate to the species and location of Filterra. Trim/prune plants in accordance with typical landscaping and safety needs. Structure Structure has visible cracks. Cracks wider than 1/2 inch or evidence of soil particles entering the structure through the cracks. Vault should be repaired. Maintenance is ideally to be performed twice annually. Date Mulch & Debris Removed Depth of Mulch Added Mulch Brand Height of Vegetation Above Grate Vegetation Species Issues with System Comments 1/1/17 5 – 5 gal Buckets 3”Lowe’s Premium Brown Mulch 4’Galaxy Magnolia - Standing water in downstream structure - Removed blockage in downstream structure www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-1122 13 Filterra Activation Package | Page 1 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® The Filterra system will be (or has been) delivered to you with protection in place to resist intrusion of construction related sediment which can contaminate the biofiltration media and result in inadequate system performance. These protection devices are intended as a best practice and cannot fully prevent contamination. It is the purchaser’s responsibility to provide adequate measures to prevent construction related runoff from entering the Filterra system. Included with your purchase is Activation of the Filterra system by the manufacturer as well as a 1-year warranty from delivery of the system and a Final Site Assessment (assessment of unit condition, mulch replacement, debris removal, and pruning of vegetation) scheduled between 6 months and 1 year after Activation, upon request. Activation of the Filterra system is a procedure completed by the manufacturer to place the system into working condition. This involves the following items: • Removal of construction runoff protection devices • Planting of the system’s vegetation (provided by the purchaser) • Placement of pretreatment mulch layer using mulch acceptable for use in Filterra systems. Activation MUST be provided by the manufacturer to ensure proper site conditions are met for Activation, proper installation of the vegetation, and use of pretreatment mulch acceptable for use in Filterra systems. The purchaser should request Activation from Contech after the site is stabilized, but prior to turning over the site to the owner. Please allow 1-2 weeks to schedule Activation. The purchaser must ensure that the site is acceptable for Filterra Activation. A checklist (included as page 3 of this document must be completed and submitted to the Contech Activation Coordinator. The minimum 4 requirements for Filterra Activation are as follows: 1. The purchaser must have sourced vegetation meeting the requirements outlined in “Plant Selection for Filterra Systems” starting on page 4 of this document. FILTERRA® VAULT ACTIVATION PACKAGE ENGINEERED SOLUTIONS Appendix 1 – Filterra® Vault Activation Package Page 5 of 19 of 39 www.ContechES.com/filterra | 800-338-1122 13 Filterra Activation Package | Page 1 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® The Filterra system will be (or has been) delivered to you with protection in place to resist intrusion of construction related sediment which can contaminate the biofiltration media and result in inadequate system performance. These protection devices are intended as a best practice and cannot fully prevent contamination. It is the purchaser’s responsibility to provide adequate measures to prevent construction related runoff from entering the Filterra system. Included with your purchase is Activation of the Filterra system by the manufacturer as well as a 1-year warranty from delivery of the system and a Final Site Assessment (assessment of unit condition, mulch replacement, debris removal, and pruning of vegetation) scheduled between 6 months and 1 year after Activation, upon request. Activation of the Filterra system is a procedure completed by the manufacturer to place the system into working condition. This involves the following items: • Removal of construction runoff protection devices • Planting of the system’s vegetation (provided by the purchaser) • Placement of pretreatment mulch layer using mulch acceptable for use in Filterra systems. Activation MUST be provided by the manufacturer to ensure proper site conditions are met for Activation, proper installation of the vegetation, and use of pretreatment mulch acceptable for use in Filterra systems. The purchaser should request Activation from Contech after the site is stabilized, but prior to turning over the site to the owner. Please allow 1-2 weeks to schedule Activation. The purchaser must ensure that the site is acceptable for Filterra Activation. A checklist (included as page 3 of this document must be completed and submitted to the Contech Activation Coordinator. The minimum 4 requirements for Filterra Activation are as follows: 1. The purchaser must have sourced vegetation meeting the requirements outlined in “Plant Selection for Filterra Systems” starting on page 4 of this document. FILTERRA® VAULT ACTIVATION PACKAGE ENGINEERED SOLUTIONS Appendix 1 – Filterra® Vault Activation Package www.ContechES.com/filterra | 800-338-1122 www.ContechES.com/filterra | 800-338-112214 Filterra Activation Package | Page 2 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® 2. The site landscaping must be fully stabilized, i.e. full landscaping installed and some grass cover (not just straw and seed) is required to reduce sediment transport. Construction debris and materials should be removed from surrounding area. 3. Final paving must be completed. Final paving ensures that paving materials will not enter and contaminate the Filterra system during the paving process, and that the plant will receive runoff from the drainage area, assisting with plant survival for the Filterra system. 4. Where curb inlets are included as part of the Filterra system, Filterra throat opening should be at least 4” clear in order to ensure adequate capacity for inflow and debris. Page 5 of 20 of 39 www.ContechES.com/filterra | 800-338-112214 Filterra Activation Package | Page 2 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® 2. The site landscaping must be fully stabilized, i.e. full landscaping installed and some grass cover (not just straw and seed) is required to reduce sediment transport. Construction debris and materials should be removed from surrounding area. 3. Final paving must be completed. Final paving ensures that paving materials will not enter and contaminate the Filterra system during the paving process, and that the plant will receive runoff from the drainage area, assisting with plant survival for the Filterra system. 4. Where curb inlets are included as part of the Filterra system, Filterra throat opening should be at least 4” clear in order to ensure adequate capacity for inflow and debris. www.ContechES.com/filterra | 800-338-1122 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. Filterra Activation Package | Page 2 ® www.ContechES.com/filterra | 800-338-1122 15 Filterra Activation Package | Page 3 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Filterra® Vault Activation Checklist Project Name: ________________________________________Company: ______________________________________________ Site Contact Name: _______________________________________Site Contact Phone/Email: ____________________________ Site Owner/End User Name: _________________________Site Owner/End User Phone/Email: ____________________________ Preferred Activation Date: ___________________________________(provide 2 weeks minimum from date this form is submitted) Site Designation Top Opening Type Final Pavement Complete Landscaping Complete / Grass Emerging Construction materials / Piles / Debris Removed Throat Opening Measures 4” Min. Height (where applicable) Vegetation Sourced by Contractor Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. Attach additional sheets as necessary. Signature Date ENGINEERED SOLUTIONS Page 5 of 21 of 39 Filterra Activation Package | Page 3 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Filterra® Vault Activation Checklist Project Name: ________________________________________Company: ______________________________________________ Site Contact Name: _______________________________________Site Contact Phone/Email: ____________________________ Site Owner/End User Name: _________________________Site Owner/End User Phone/Email: ____________________________ Preferred Activation Date: ___________________________________(provide 2 weeks minimum from date this form is submitted) Site Designation Top Opening Type Final Pavement Complete Landscaping Complete / Grass Emerging Construction materials / Piles / Debris Removed Throat Opening Measures 4” Min. Height (where applicable) Vegetation Sourced by Contractor Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided Tree Grate Full Grate (No tree opening) Bioscape Vault (Open Planter) Verified Verified Verified Verified Species on FT Plant List Container Grown (15 gal. max) 4’ Tall Min. (Tree grate units only) ____ Qty provided NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. Attach additional sheets as necessary. Signature Date ENGINEERED SOLUTIONS * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. www.ContechES.com/filterra | 800-338-1122 vations will void the system war Filterra Activation Package | Page 3 ® www.ContechES.com/filterra | 800-338-112216 Filterra Activation Package | Page 4 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Planting Selection for Filterra® Vault Systems All Filterra systems require vegetation for proper long-term performance. As indicated in the Activation Package, the Contractor is responsible for sourcing the proper vegetation prior to Activation. Contech or a Contech representative will install the vegetation during the Activation process. Contractors should identify the Top Opening style for each Filterra requiring Activation on the Activation Checklist. Contech offers three types, which are detailed on page 5 of this document: • Vault with Tree Grate • Vault with Full Grate • Bioscape / Open Planter Contractors must ensure the vegetation meets the following 4 requirements: 1. Select plant(s) as specified in the engineering plans and specifications AND that are listed on Contech’s Configuration Specific Plant Lists**. 2. All plants MUST be container-grown in nursery containers no larger than 15 gallons. Crated and/or Ball/Burlap plants are NOT permitted. 3. For Vaults with Tree Grates, plant height must be 4’ Minimum, from soil surface to top of plant. 4. Provide plant quantities per the following guidance: • Vault with Tree Grate – 1 per Tree Grate • Vault with Full Grate – 4-5 Small or Extra Small Grasses per Full Grate • Bioscape – Quantities should be selected based on plant palette options found starting on page 6 of this document. If Contech or Contech’s representative shows up for Activation and any of the 4 requirements above are not met, Activation cannot be performed and the Contractor will be billed a $1,500 Unprepared Site fee*. Some additional vegetation recommendations for the best possible Activation and Installation are as follows: • Select plant(s) with full root development but not to the point where root bound. • For Filterra systems with a Tree Grate, select plants with taller trunks. Lower branches can be pruned away provided there are sufficient branches above the grate for tree or shrub development. • For Filterra systems with a Tree Grate, plant(s) should have a single trunk at installation. • Plant species shall not have a mature height greater than 30 feet. ** In some cases, Contech may consider alternate plant species as approved by the Product Manager. Please list the plant name in the space below and submit this sheet to your Contech Activation Coordinator. If the plant species is approved, either the Product Manager or the Activation Coordinator will sign the form and return to you for inclusion with your Activation Checklist. Requested Plant Species: ___________________________________________Approved: _______________________________ Date: ____________________________________ Page 5 of 22 of 39 www.ContechES.com/filterra | 800-338-1122 Filterra Activation Package | Page 4 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Planting Selection for Filterra® Vault Systems All Filterra systems require vegetation for proper long-term performance. As indicated in the Activation Package, the Contractor is responsible for sourcing the proper vegetation prior to Activation. Contech or a Contech representative will install the vegetation during the Activation process. Contractors should identify the Top Opening style for each Filterra requiring Activation on the Activation Checklist. Contech offers three types, which are detailed on page 5 of this document: • Vault with Tree Grate • Vault with Full Grate • Bioscape / Open Planter Contractors must ensure the vegetation meets the following 4 requirements: 1. Select plant(s) as specified in the engineering plans and specifications AND that are listed on Contech’s Configuration Specific Plant Lists**. 2. All plants MUST be container-grown in nursery containers no larger than 15 gallons. Crated and/or Ball/Burlap plants are NOT permitted. 3. For Vaults with Tree Grates, plant height must be 4’ Minimum, from soil surface to top of plant. 4. Provide plant quantities per the following guidance: • Vault with Tree Grate – 1 per Tree Grate • Vault with Full Grate – 4-5 Small or Extra Small Grasses per Full Grate • Bioscape – Quantities should be selected based on plant palette options found starting on page 6 of this document. If Contech or Contech’s representative shows up for Activation and any of the 4 requirements above are not met, Activation cannot be performed and the Contractor will be billed a $1,500 Unprepared Site fee*. Some additional vegetation recommendations for the best possible Activation and Installation are as follows: • Select plant(s) with full root development but not to the point where root bound. • For Filterra systems with a Tree Grate, select plants with taller trunks. Lower branches can be pruned away provided there are sufficient branches above the grate for tree or shrub development. • For Filterra systems with a Tree Grate, plant(s) should have a single trunk at installation. • Plant species shall not have a mature height greater than 30 feet. ** In some cases, Contech may consider alternate plant species as approved by the Product Manager. Please list the plant name in the space below and submit this sheet to your Contech Activation Coordinator. If the plant species is approved, either the Product Manager or the Activation Coordinator will sign the form and return to you for inclusion with your Activation Checklist. Requested Plant Species: ___________________________________________Approved: _______________________________ Date: ____________________________________ * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ________________________ Filterra Activation Package | Page 4 ® www.ContechES.com/filterra | 800-338-1122 17 Filterra Activation Package | Page 5 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Figure 1a. Filterra with Tree Grate Drawing Figure 2a. Filterra with Full Grate Drawing Figure 3a. Filterra Bioscape Vault Drawing Figure 1b. Filterra with Tree Grate Photo (not yet planted) Figure 2b. Filterra with Full Grate Photo Figure 3b. Filterra Bioscape Vault Photo Filterra® Top Opening Examples Filterra® Vault with Tree Grate Filterra® Vault with Full Grate Filterra® Bioscape Vault Page 5 of 23 of 39 www.ContechES.com/filterra | 800-338-1122 Filterra Activation Package | Page 5 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Figure 1a. Filterra with Tree Grate Drawing Figure 2a. Filterra with Full Grate Drawing Figure 3a. Filterra Bioscape Vault Drawing Figure 1b. Filterra with Tree Grate Photo (not yet planted) Figure 2b. Filterra with Full Grate Photo Figure 3b. Filterra Bioscape Vault Photo Filterra® Top Opening Examples Filterra® Vault with Tree Grate Filterra® Vault with Full Grate Filterra® Bioscape Vault * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. Filterra Activation Package | Page 5 ® www.ContechES.com/filterra | 800-338-112218 Filterra Activation Package | Page 6 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® Filterra® Bioscape Vault Plant Palettes KEY: (refer to plant lists for species sizing) 4x4 Media Bay A. 3 A.5 A. 6 A. 6 A. 9 A. 12 A. 15 A. 20 B. 6 C. 3 D. 2 B. 1 B.2 B. 2 B. 2 B. 3 B. 3 B. 4 C. 1 C.1 C. 1 D. 1 D. 1 D. 1 D. 1 D. 1 C. 1 C. 2 C. 2 C. 2 4x6/6x4 Media Bay 4x8/8x4 & 4.5x7.83/7.83x4.5 Media Bay 6x6 Media Bay 6x8/8x6 Media Bay 6x10/10x6 & 8x8 Media Bay 6x12/12x6 Media Bay 7x13/13x7/12x8 & 14x8 Media Bay A. EXTRA SMALL GRASS • Up to 2’ mature spread • 1-2 gallon typical (1 gal. minimum) B. SMALL GRASS/SHRUB • 2’-4’ mature spread • 1-7 gallon typical C. MEDIUM SHRUB • 4’-6’ mature spread • 1-7 gallon typical D. LARGE SHRUB OR EXTRA LARGE SHRUB OR TREE • 6’ mature spread and greater, 30’ max. mature height • Up to 15 gallon maximum NOTE: For larger vaults and in-ground Filterra Bioscape systems, palettes can be scaled (i.e. Qty 6 of the 22x8 Palette can be used for a 1056 sf Filterra Bioscape). MIX & MATCH SUBSTITUTION OPTIONS: 1 Large Shrub or Extra Large Shrub or Tree • 2 Medium Shrubs • 4 Small Grass/SHrubs • 12 Extra Small Grasses 1 Medium Shrub • 2 Small Grass/Shrubs • 6 Extra Small Grasses 1 Small Grass/Shrub • 3 Extra Small Grasses Page 5 of 24 of 39 www.ContechES.com/filterra | 800-338-1122 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. www.ContechES.com/filterra | 800-338-1122 19 Filterra Activation Package | Page 7 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. ® A. 24 A. 28 A. 32 A. 36 B. 8 B. 8 B. 10 B. 10 C. 4 C. 4 C. 5 C. 5 D. 2 D. 2 D. 3 D. 3 16x8 & 15x9 Media Bay 18x8 Media Bay 20x8 Media Bay 22x8 Media Bay Page 5 of 25 of 39 www.ContechES.com/filterra | 800-338-1122 * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation AND/OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection. Appendix 2 – Filterra® Tree Grate Opening Expansion Procedure The standard grates used on all Filterra configurations that employ Tree Grates are fabricated with a 6” opening that is designed with a breakaway section that can be removed, allowing the grate opening to be expanded to 12” as the tree matures and the trunk widens. The following tools are required to expand the opening: • Mini sledgehammer (3 lb. or greater) • Safety Glasses / Goggles The following guidelines should be followed to properly expand the tree opening from 6” to 12”: 1. Remove the grate from the Filterra frame, place it flat on a hard surface, and support the grate by stepping on the edge or using other weighted items such as a few mulch bags if this is being done during a Filterra maintenance event. Put on safety glasses/goggles. Align the mini sledgehammer as shown in the figure to the left. The head of the sledgehammer should be aimed just inside the wide cast iron bar between the larger grate section and the breakaway section. 2. Repeatedly hit the grate at this spot with the mini sledgehammer. 3. After several hits, the breakaway section should snap cleanly off of the larger grate section. Reinstall the grate into the Filterra grate frame. Recycle or dispose of the breakaway section per local guidelines. Page 5 of www.ContechES.com/filterra | 800-338-1122 Appendix 2 – Filterra® Tree Grate Opening Expansion Procedure The standard grates used on all Filterra configurations that employ Tree Grates are fabricated with a 6” opening that is designed with a breakaway section that can be removed, allowing the grate opening to be expanded to 12” as the tree matures and the trunk widens. The following tools are required to expand the opening: • Mini sledgehammer (3 lb. or greater) • Safety Glasses / Goggles The following guidelines should be followed to properly expand the tree opening from 6” to 12”: 1. Remove the grate from the Filterra frame, place it flat on a hard surface, and support the grate by stepping on the edge or using other weighted items such as a few mulch bags if this is being done during a Filterra maintenance event. Put on safety glasses/goggles. Align the mini sledgehammer as shown in the figure to the left. The head of the sledgehammer should be aimed just inside the wide cast iron bar between the larger grate section and the breakaway section. 2. Repeatedly hit the grate at this spot with the mini sledgehammer. 3. After several hits, the breakaway section should snap cleanly off of the larger grate section. Reinstall the grate into the Filterra grate frame. Recycle or dispose of the breakaway section per local guidelines. 26 of 39 Notes ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ 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___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ 39Page 5 of 28 of Page 5 of www.ContechES.com/filterra | 800-338-1122 28 of 39 Notes ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ 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___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ 39Page 5 of 28 of Page 5 of www.ContechES.com/filterra | 800-338-1122 29 of 39 Notes ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ 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___________________________________________________________________________________________________________ PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS 39Page 5 of 28 of Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. CDS Guide Operation, Design, Performance and Maintenance ENGINEERED SOLUTIONS 39Page 5 of 28 of Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. 39Page 5 of 28 of Page 5 of 31 of 39 CDS Guide Operation, Design, Performance and Maintenance ENGINEERED SOLUTIONS 2 CDS® Using patented continuous deflective separation technology, the CDS system screens, separates and traps debris, sediment, and oil and grease from stormwater runoff. The indirect screening capability of the system allows for 100% removal of floatables and neutrally buoyant material without blinding. Flow and screening controls physically separate captured solids, and minimize the re-suspension and release of previously trapped pollutants. Inline units can treat up to 6 cfs, and internally bypass flows in excess of 50 cfs (1416 L/s). Available precast or cast-in- place, offline units can treat flows from 1 to 300 cfs (28.3 to 8495 L/s). The pollutant removal capacity of the CDS system has been proven in lab and field testing. Operation Overview Stormwater enters the diversion chamber where the diversion weir guides the flow into the unit’s separation chamber and pollutants are removed from the flow. All flows up to the system’s treatment design capacity enter the separation chamber and are treated. Swirl concentration and screen deflection force floatables and solids to the center of the separation chamber where 100% of floatables and neutrally buoyant debris larger than the screen apertures are trapped. Stormwater then moves through the separation screen, under the oil baffle and exits the system. The separation screen remains clog free due to continuous deflection. During the flow events exceeding the treatment design capacity, the diversion weir bypasses excessive flows around the separation chamber, so captured pollutants are retained in the separation cylinder. Design Basics There are three primary methods of sizing a CDS system. The Water Quality Flow Rate Method determines which model size provides the desired removal efficiency at a given flow rate for a defined particle size. The Rational Rainfall Method™ or the and Probabilistic Method is used when a specific removal efficiency of the net annual sediment load is required. Typically in the Unites States, CDS systems are designed to achieve an 80% annual solids load reduction based on lab generated performance curves for a gradation with an average particle size (d50) of 125 microns (μm). For some regulatory environments, CDS systems can also be designed to achieve an 80% annual solids load reduction based on an average particle size (d50) of 75 microns (μm) or 50 microns (μm). Water Quality Flow Rate Method In some cases, regulations require that a specific treatment rate, often referred to as the water quality design flow (WQQ), be treated. This WQQ represents the peak flow rate from either an event with a specific recurrence interval, e.g. the six-month storm, or a water quality depth, e.g. 1/2-inch (13 mm) of rainfall. The CDS is designed to treat all flows up to the WQQ. At influent rates higher than the WQQ, the diversion weir will direct most flow exceeding the WQQ around the separation chamber. This allows removal efficiency to remain relatively constant in the separation chamber and eliminates the risk of washout during bypass flows regardless of influent flow rates. Treatment flow rates are defined as the rate at which the CDS will remove a specific gradation of sediment at a specific removal efficiency. Therefore the treatment flow rate is variable, based on the gradation and removal efficiency specified by the design engineer. Rational Rainfall Method™ Differences in local climate, topography and scale make every site hydraulically unique. It is important to take these factors into consideration when estimating the long-term performance of any stormwater treatment system. The Rational Rainfall Method combines site-specific information with laboratory generated performance data, and local historical precipitation records to estimate removal efficiencies as accurately as possible. Short duration rain gauge records from across the United States and Canada were analyzed to determine the percent of the total annual rainfall that fell at a range of intensities. US stations’ depths were totaled every 15 minutes, or hourly, and recorded in 0.01-inch increments. Depths were recorded hourly with 1-mm resolution at Canadian stations. One trend was consistent at all sites; the vast majority of precipitation fell at low intensities and high intensity storms contributed relatively little to the total annual depth. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Rainfall Method. Since most sites are relatively small and highly impervious, the Rational Rainfall Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS system are GRATE INLET(CAST IRON HOOD FORCURB INLET OPENING) CREST OF BYPASS WEIR(ONE EACH SIDE) INLET(MULTIPLE PIPES POSSIBLE) OIL BAFFLE SUMP STORAGESEPARATION SLAB TREATMENT SCREEN OUTLET INLET FLUME SEPARATION CYLINDER CLEAN OUT(REQUIRED) DEFLECTION PAN, 3 SIDED(GRATE INLET DESIGN) 39Page 5 of 28 of Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. 39Page 5 of 28 of Page 5 of 32 of 39 2 CDS® Using patented continuous deflective separation technology, the CDS system screens, separates and traps debris, sediment, and oil and grease from stormwater runoff. The indirect screening capability of the system allows for 100% removal of floatables and neutrally buoyant material without blinding. Flow and screening controls physically separate captured solids, and minimize the re-suspension and release of previously trapped pollutants. Inline units can treat up to 6 cfs, and internally bypass flows in excess of 50 cfs (1416 L/s). Available precast or cast-in- place, offline units can treat flows from 1 to 300 cfs (28.3 to 8495 L/s). The pollutant removal capacity of the CDS system has been proven in lab and field testing. Operation Overview Stormwater enters the diversion chamber where the diversion weir guides the flow into the unit’s separation chamber and pollutants are removed from the flow. All flows up to the system’s treatment design capacity enter the separation chamber and are treated. Swirl concentration and screen deflection force floatables and solids to the center of the separation chamber where 100% of floatables and neutrally buoyant debris larger than the screen apertures are trapped. Stormwater then moves through the separation screen, under the oil baffle and exits the system. The separation screen remains clog free due to continuous deflection. During the flow events exceeding the treatment design capacity, the diversion weir bypasses excessive flows around the separation chamber, so captured pollutants are retained in the separation cylinder. Design Basics There are three primary methods of sizing a CDS system. The Water Quality Flow Rate Method determines which model size provides the desired removal efficiency at a given flow rate for a defined particle size. The Rational Rainfall Method™ or the and Probabilistic Method is used when a specific removal efficiency of the net annual sediment load is required. Typically in the Unites States, CDS systems are designed to achieve an 80% annual solids load reduction based on lab generated performance curves for a gradation with an average particle size (d50) of 125 microns (μm). For some regulatory environments, CDS systems can also be designed to achieve an 80% annual solids load reduction based on an average particle size (d50) of 75 microns (μm) or 50 microns (μm). Water Quality Flow Rate Method In some cases, regulations require that a specific treatment rate, often referred to as the water quality design flow (WQQ), be treated. This WQQ represents the peak flow rate from either an event with a specific recurrence interval, e.g. the six-month storm, or a water quality depth, e.g. 1/2-inch (13 mm) of rainfall. The CDS is designed to treat all flows up to the WQQ. At influent rates higher than the WQQ, the diversion weir will direct most flow exceeding the WQQ around the separation chamber. This allows removal efficiency to remain relatively constant in the separation chamber and eliminates the risk of washout during bypass flows regardless of influent flow rates. Treatment flow rates are defined as the rate at which the CDS will remove a specific gradation of sediment at a specific removal efficiency. Therefore the treatment flow rate is variable, based on the gradation and removal efficiency specified by the design engineer. Rational Rainfall Method™ Differences in local climate, topography and scale make every site hydraulically unique. It is important to take these factors into consideration when estimating the long-term performance of any stormwater treatment system. The Rational Rainfall Method combines site-specific information with laboratory generated performance data, and local historical precipitation records to estimate removal efficiencies as accurately as possible. Short duration rain gauge records from across the United States and Canada were analyzed to determine the percent of the total annual rainfall that fell at a range of intensities. US stations’ depths were totaled every 15 minutes, or hourly, and recorded in 0.01-inch increments. Depths were recorded hourly with 1-mm resolution at Canadian stations. One trend was consistent at all sites; the vast majority of precipitation fell at low intensities and high intensity storms contributed relatively little to the total annual depth. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Rainfall Method. Since most sites are relatively small and highly impervious, the Rational Rainfall Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS system are GRATE INLET(CAST IRON HOOD FORCURB INLET OPENING) CREST OF BYPASS WEIR(ONE EACH SIDE) INLET(MULTIPLE PIPES POSSIBLE) OIL BAFFLE SUMP STORAGESEPARATION SLAB TREATMENT SCREEN OUTLET INLET FLUME SEPARATION CYLINDER CLEAN OUT(REQUIRED) DEFLECTION PAN, 3 SIDED(GRATE INLET DESIGN) 3 determined. Performance efficiency curve determined from full scale laboratory tests on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Probabilistic Rational Method The Probabilistic Rational Method is a sizing program Contech developed to estimate a net annual sediment load reduction for a particular CDS model based on site size, site runoff coefficient, regional rainfall intensity distribution, and anticipated pollutant characteristics. The Probabilistic Method is an extension of the Rational Method used to estimate peak discharge rates generated by storm events of varying statistical return frequencies (e.g. 2-year storm event). Under the Rational Method, an adjustment factor is used to adjust the runoff coefficient estimated for the 10-year event, correlating a known hydrologic parameter with the target storm event. The rainfall intensities vary depending on the return frequency of the storm event under consideration. In general, these two frequency dependent parameters (rainfall intensity and runoff coefficient) increase as the return frequency increases while the drainage area remains constant. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Method. Since most sites are relatively small and highly impervious, the Rational Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS are determined. Performance efficiency curve on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Treatment Flow Rate The inlet throat area is sized to ensure that the WQQ passes through the separation chamber at a water surface elevation equal to the crest of the diversion weir. The diversion weir bypasses excessive flows around the separation chamber, thus preventing re-suspension or re-entrainment of previously captured particles. Hydraulic Capacity The hydraulic capacity of a CDS system is determined by the length and height of the diversion weir and by the maximum allowable head in the system. Typical configurations allow hydraulic capacities of up to ten times the treatment flow rate. The crest of the diversion weir may be lowered and the inlet throat may be widened to increase the capacity of the system at a given water surface elevation. The unit is designed to meet project specific hydraulic requirements. Performance Full-Scale Laboratory Test Results A full-scale CDS system (Model CDS2020-5B) was tested at the facility of University of Florida, Gainesville, FL. This CDS unit was evaluated under controlled laboratory conditions of influent flow rate and addition of sediment. Two different gradations of silica sand material (UF Sediment & OK-110) were used in the CDS performance evaluation. The particle size distributions (PSDs) of the test materials were analyzed using standard method “Gradation ASTM D-422 “Standard Test Method for Particle-Size Analysis of Soils” by a certified laboratory. UF Sediment is a mixture of three different products produced by the U.S. Silica Company: “Sil-Co-Sil 106”, “#1 DRY” and “20/40 Oil Frac”. Particle size distribution analysis shows that the UF Sediment has a very fine gradation (d50 = 20 to 30 μm) covering a wide size range (Coefficient of Uniformity, C averaged at 10.6). In comparison with the hypothetical TSS gradation specified in the NJDEP (New Jersey Department of Environmental Protection) and NJCAT (New Jersey Corporation for Advanced Technology) protocol for lab testing, the UF Sediment covers a similar range of particle size but with a finer d50 (d50 for NJDEP is approximately 50 μm) (NJDEP, 2003). The OK-110 silica sand is a commercial product of U.S. Silica Sand. The particle size distribution analysis of this material, also included in Figure 1, shows that 99.9% of the OK-110 sand is finer than 250 microns, with a mean particle size (d50) of 106 microns. The PSDs for the test material are shown in Figure 1. Figure 1. Particle size distributions Tests were conducted to quantify the performance of a specific CDS unit (1.1 cfs (31.3-L/s) design capacity) at various flow rates, ranging from 1% up to 125% of the treatment design capacity of the unit, using the 2400 micron screen. All tests were conducted with controlled influent concentrations of approximately 200 mg/L. Effluent samples were taken at equal time intervals across the entire duration of each test run. These samples were then processed with a Dekaport Cone sample splitter to obtain representative sub-samples for Suspended Sediment Concentration (SSC) testing using ASTM D3977-97 “Standard Test Methods for Determining Sediment Concentration in Water Samples”, and particle size distribution analysis. Results and Modeling Based on the data from the University of Florida, a performance model was developed for the CDS system. A regression analysis was used to develop a fitting curve representative of the scattered data points at various design flow rates. This model, which demonstrated good agreement with the laboratory data, can then be used to predict CDS system performance with respect Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. 39Page 5 of 28 of Page 5 of 33 of 39 3 determined. Performance efficiency curve determined from full scale laboratory tests on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Probabilistic Rational Method The Probabilistic Rational Method is a sizing program Contech developed to estimate a net annual sediment load reduction for a particular CDS model based on site size, site runoff coefficient, regional rainfall intensity distribution, and anticipated pollutant characteristics. The Probabilistic Method is an extension of the Rational Method used to estimate peak discharge rates generated by storm events of varying statistical return frequencies (e.g. 2-year storm event). Under the Rational Method, an adjustment factor is used to adjust the runoff coefficient estimated for the 10-year event, correlating a known hydrologic parameter with the target storm event. The rainfall intensities vary depending on the return frequency of the storm event under consideration. In general, these two frequency dependent parameters (rainfall intensity and runoff coefficient) increase as the return frequency increases while the drainage area remains constant. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Method. Since most sites are relatively small and highly impervious, the Rational Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS are determined. Performance efficiency curve on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Treatment Flow Rate The inlet throat area is sized to ensure that the WQQ passes through the separation chamber at a water surface elevation equal to the crest of the diversion weir. The diversion weir bypasses excessive flows around the separation chamber, thus preventing re-suspension or re-entrainment of previously captured particles. Hydraulic Capacity The hydraulic capacity of a CDS system is determined by the length and height of the diversion weir and by the maximum allowable head in the system. Typical configurations allow hydraulic capacities of up to ten times the treatment flow rate. The crest of the diversion weir may be lowered and the inlet throat may be widened to increase the capacity of the system at a given water surface elevation. The unit is designed to meet project specific hydraulic requirements. Performance Full-Scale Laboratory Test Results A full-scale CDS system (Model CDS2020-5B) was tested at the facility of University of Florida, Gainesville, FL. This CDS unit was evaluated under controlled laboratory conditions of influent flow rate and addition of sediment. Two different gradations of silica sand material (UF Sediment & OK-110) were used in the CDS performance evaluation. The particle size distributions (PSDs) of the test materials were analyzed using standard method “Gradation ASTM D-422 “Standard Test Method for Particle-Size Analysis of Soils” by a certified laboratory. UF Sediment is a mixture of three different products produced by the U.S. Silica Company: “Sil-Co-Sil 106”, “#1 DRY” and “20/40 Oil Frac”. Particle size distribution analysis shows that the UF Sediment has a very fine gradation (d50 = 20 to 30 μm) covering a wide size range (Coefficient of Uniformity, C averaged at 10.6). In comparison with the hypothetical TSS gradation specified in the NJDEP (New Jersey Department of Environmental Protection) and NJCAT (New Jersey Corporation for Advanced Technology) protocol for lab testing, the UF Sediment covers a similar range of particle size but with a finer d50 (d50 for NJDEP is approximately 50 μm) (NJDEP, 2003). The OK-110 silica sand is a commercial product of U.S. Silica Sand. The particle size distribution analysis of this material, also included in Figure 1, shows that 99.9% of the OK-110 sand is finer than 250 microns, with a mean particle size (d50) of 106 microns. The PSDs for the test material are shown in Figure 1. Figure 1. Particle size distributions Tests were conducted to quantify the performance of a specific CDS unit (1.1 cfs (31.3-L/s) design capacity) at various flow rates, ranging from 1% up to 125% of the treatment design capacity of the unit, using the 2400 micron screen. All tests were conducted with controlled influent concentrations of approximately 200 mg/L. Effluent samples were taken at equal time intervals across the entire duration of each test run. These samples were then processed with a Dekaport Cone sample splitter to obtain representative sub-samples for Suspended Sediment Concentration (SSC) testing using ASTM D3977-97 “Standard Test Methods for Determining Sediment Concentration in Water Samples”, and particle size distribution analysis. Results and Modeling Based on the data from the University of Florida, a performance model was developed for the CDS system. A regression analysis was used to develop a fitting curve representative of the scattered data points at various design flow rates. This model, which demonstrated good agreement with the laboratory data, can then be used to predict CDS system performance with respect 4 to SSC removal for any particle size gradation, assuming the particles are inorganic sandy-silt. Figure 2 shows CDS predictive performance for two typical particle size gradations (NJCAT gradation and OK-110 sand) as a function of operating rate. Figure 2. CDS stormwater treatment predictive performance for various particle gradations as a function of operating rate. Many regulatory jurisdictions set a performance standard for hydrodynamic devices by stating that the devices shall be capable of achieving an 80% removal efficiency for particles having a mean particle size (d50) of 125 microns (e.g. Washington State Department of Ecology — WASDOE - 2008). The model can be used to calculate the expected performance of such a PSD (shown in Figure 3). The model indicates (Figure 4) that the CDS system with 2400 micron screen achieves approximately 80% removal at the design (100%) flow rate, for this particle size distribution (d50 = 125 μm). Figure 3. WASDOE PSD Figure 4. Modeled performance for WASDOE PSD. Maintenance The CDS system should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit. For example, unstable soils or heavy winter sanding will cause the grit chamber to fill more quickly but regular sweeping of paved surfaces will slow accumulation. Inspection Inspection is the key to effective maintenance and is easily performed. Pollutant transport and deposition may vary from year to year and regular inspections will help ensure that the system is cleaned out at the appropriate time. At a minimum, inspections should be performed twice per year (e.g. spring and fall) however more frequent inspections may be necessary in climates where winter sanding operations may lead to rapid accumulations, or in equipment washdown areas. Installations should also be inspected more frequently where excessive amounts of trash are expected. The visual inspection should ascertain that the system components are in working order and that there are no blockages or obstructions in the inlet and separation screen. The inspection should also quantify the accumulation of hydrocarbons, trash, and sediment in the system. Measuring pollutant accumulation can be done with a calibrated dipstick, tape measure or other measuring instrument. If absorbent material is used for enhanced removal of hydrocarbons, the level of discoloration of the sorbent material should also be identified Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. 39Page 5 of 28 of Page 5 of 34 of 39 4 to SSC removal for any particle size gradation, assuming the particles are inorganic sandy-silt. Figure 2 shows CDS predictive performance for two typical particle size gradations (NJCAT gradation and OK-110 sand) as a function of operating rate. Figure 2. CDS stormwater treatment predictive performance for various particle gradations as a function of operating rate. Many regulatory jurisdictions set a performance standard for hydrodynamic devices by stating that the devices shall be capable of achieving an 80% removal efficiency for particles having a mean particle size (d50) of 125 microns (e.g. Washington State Department of Ecology — WASDOE - 2008). The model can be used to calculate the expected performance of such a PSD (shown in Figure 3). The model indicates (Figure 4) that the CDS system with 2400 micron screen achieves approximately 80% removal at the design (100%) flow rate, for this particle size distribution (d50 = 125 μm). Figure 3. WASDOE PSD Figure 4. Modeled performance for WASDOE PSD. Maintenance The CDS system should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit. For example, unstable soils or heavy winter sanding will cause the grit chamber to fill more quickly but regular sweeping of paved surfaces will slow accumulation. Inspection Inspection is the key to effective maintenance and is easily performed. Pollutant transport and deposition may vary from year to year and regular inspections will help ensure that the system is cleaned out at the appropriate time. At a minimum, inspections should be performed twice per year (e.g. spring and fall) however more frequent inspections may be necessary in climates where winter sanding operations may lead to rapid accumulations, or in equipment washdown areas. Installations should also be inspected more frequently where excessive amounts of trash are expected. The visual inspection should ascertain that the system components are in working order and that there are no blockages or obstructions in the inlet and separation screen. The inspection should also quantify the accumulation of hydrocarbons, trash, and sediment in the system. Measuring pollutant accumulation can be done with a calibrated dipstick, tape measure or other measuring instrument. If absorbent material is used for enhanced removal of hydrocarbons, the level of discoloration of the sorbent material should also be identified 5 during inspection. It is useful and often required as part of an operating permit to keep a record of each inspection. A simple form for doing so is provided. Access to the CDS unit is typically achieved through two manhole access covers. One opening allows for inspection and cleanout of the separation chamber (cylinder and screen) and isolated sump. The other allows for inspection and cleanout of sediment captured and retained outside the screen. For deep units, a single manhole access point would allows both sump cleanout and access outside the screen. The CDS system should be cleaned when the level of sediment has reached 75% of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accumulated. If absorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100% of the sump capacity is exceeded however it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimating the level of sediment in the chamber, the measuring device must be lowered to the top of the sediment pile carefully. Particles at the top of the pile typically offer less resistance to the end of the rod than consolidated particles toward the bottom of the pile. Once this measurement is recorded, it should be compared to the as-built drawing for the unit to determine weather the height of the sediment pile off the bottom of the sump floor exceeds 75% of the total height of isolated sump. Cleaning Cleaning of a CDS systems should be done during dry weather conditions when no flow is entering the system. The use of a vacuum truck is generally the most effective and convenient method of removing pollutants from the system. Simply remove the manhole covers and insert the vacuum hose into the sump. The system should be completely drained down and the sump fully evacuated of sediment. The area outside the screen should also be cleaned out if pollutant build-up exists in this area. In installations where the risk of petroleum spills is small, liquid contaminants may not accumulate as quickly as sediment. However, the system should be cleaned out immediately in the event of an oil or gasoline spill. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use absorbent pads since they are usually less expensive to dispose than the oil/water emulsion that may be created by vacuuming the oily layer. Trash and debris can be netted out to separate it from the other pollutants. The screen should be cleaned to ensure it is free of trash and debris. Manhole covers should be securely seated following cleaning activities to prevent leakage of runoff into the system from above and also to ensure that proper safety precautions have been followed. Confined space entry procedures need to be followed if physical access is required. Disposal of all material removed from the CDS system should be done in accordance with local regulations. In many jurisdictions, disposal of the sediments may be handled in the same manner as the disposal of sediments removed from catch basins or deep sump manholes. Check your local regulations for specific requirements on disposal. Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. 39Page 5 of 28 of Page 5 of 35 of 39 5 during inspection. It is useful and often required as part of an operating permit to keep a record of each inspection. A simple form for doing so is provided. Access to the CDS unit is typically achieved through two manhole access covers. One opening allows for inspection and cleanout of the separation chamber (cylinder and screen) and isolated sump. The other allows for inspection and cleanout of sediment captured and retained outside the screen. For deep units, a single manhole access point would allows both sump cleanout and access outside the screen. The CDS system should be cleaned when the level of sediment has reached 75% of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accumulated. If absorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100% of the sump capacity is exceeded however it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimating the level of sediment in the chamber, the measuring device must be lowered to the top of the sediment pile carefully. Particles at the top of the pile typically offer less resistance to the end of the rod than consolidated particles toward the bottom of the pile. Once this measurement is recorded, it should be compared to the as-built drawing for the unit to determine weather the height of the sediment pile off the bottom of the sump floor exceeds 75% of the total height of isolated sump. Cleaning Cleaning of a CDS systems should be done during dry weather conditions when no flow is entering the system. The use of a vacuum truck is generally the most effective and convenient method of removing pollutants from the system. Simply remove the manhole covers and insert the vacuum hose into the sump. The system should be completely drained down and the sump fully evacuated of sediment. The area outside the screen should also be cleaned out if pollutant build-up exists in this area. In installations where the risk of petroleum spills is small, liquid contaminants may not accumulate as quickly as sediment. However, the system should be cleaned out immediately in the event of an oil or gasoline spill. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use absorbent pads since they are usually less expensive to dispose than the oil/water emulsion that may be created by vacuuming the oily layer. Trash and debris can be netted out to separate it from the other pollutants. The screen should be cleaned to ensure it is free of trash and debris. Manhole covers should be securely seated following cleaning activities to prevent leakage of runoff into the system from above and also to ensure that proper safety precautions have been followed. Confined space entry procedures need to be followed if physical access is required. Disposal of all material removed from the CDS system should be done in accordance with local regulations. In many jurisdictions, disposal of the sediments may be handled in the same manner as the disposal of sediments removed from catch basins or deep sump manholes. Check your local regulations for specific requirements on disposal. 6 Note: To avoid underestimating the volume of sediment in the chamber, carefully lower the measuring device to the top of the sediment pile. Finer silty particles at the top of the pile may be more difficult to feel with a measuring stick. These finer particles typically offer less resistance to the end of the rod than larger particles toward the bottom of the pile. CDS Model Diameter Distance from Water Surface to Top of Sediment Pile Sediment Storage Capacity ft m ft m y3 m3 CDS1515 3 0.9 3.0 0.9 0.5 0.4 CDS2015 4 1.2 3.0 0.9 0.9 0.7 CDS2015 5 1.5 3.0 0.9 1.3 1.0 CDS2020 5 1.5 3.5 1.1 1.3 1.0 CDS2025 5 1.5 4.0 1.2 1.3 1.0 CDS3020 6 1.8 4.0 1.2 2.1 1.6 CDS3025 6 1.8 4.0 1.2 2.1 1.6 CDS3030 6 1.8 4.6 1.4 2.1 1.6 CDS3035 6 1.8 5.0 1.5 2.1 1.6 CDS4030 8 2.4 4.6 1.4 5.6 4.3 CDS4040 8 2.4 5.7 1.7 5.6 4.3 CDS4045 8 2.4 6.2 1.9 5.6 4.3 CDS5640 10 3.0 6.3 1.9 8.7 6.7 CDS5653 10 3.0 7.7 2.3 8.7 6.7 CDS5668 10 3.0 9.3 2.8 8.7 6.7 CDS5678 10 3.0 10.3 3.1 8.7 6.7 Table 1: CDS Maintenance Indicators and Sediment Storage Capacities Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. 39Page 5 of 28 of Page 5 of 36 of 39 6 Note: To avoid underestimating the volume of sediment in the chamber, carefully lower the measuring device to the top of the sediment pile. Finer silty particles at the top of the pile may be more difficult to feel with a measuring stick. These finer particles typically offer less resistance to the end of the rod than larger particles toward the bottom of the pile. CDS Model Diameter Distance from Water Surface to Top of Sediment Pile Sediment Storage Capacity ft m ft m y3 m3 CDS1515 3 0.9 3.0 0.9 0.5 0.4 CDS2015 4 1.2 3.0 0.9 0.9 0.7 CDS2015 5 1.5 3.0 0.9 1.3 1.0 CDS2020 5 1.5 3.5 1.1 1.3 1.0 CDS2025 5 1.5 4.0 1.2 1.3 1.0 CDS3020 6 1.8 4.0 1.2 2.1 1.6 CDS3025 6 1.8 4.0 1.2 2.1 1.6 CDS3030 6 1.8 4.6 1.4 2.1 1.6 CDS3035 6 1.8 5.0 1.5 2.1 1.6 CDS4030 8 2.4 4.6 1.4 5.6 4.3 CDS4040 8 2.4 5.7 1.7 5.6 4.3 CDS4045 8 2.4 6.2 1.9 5.6 4.3 CDS5640 10 3.0 6.3 1.9 8.7 6.7 CDS5653 10 3.0 7.7 2.3 8.7 6.7 CDS5668 10 3.0 9.3 2.8 8.7 6.7 CDS5678 10 3.0 10.3 3.1 8.7 6.7 Table 1: CDS Maintenance Indicators and Sediment Storage Capacities 7 CDS Inspection & Maintenance Log CDS Model: Location: Water Floatable Describe Maintenance Date depth to Layer Maintenance Personnel Comments sediment1 Thickness2 Performed —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— 1. The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than the values listed in table 1 the system should be cleaned out. Note: to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. 2. For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. 39Page 5 of 28 of Page 5 of 37 of 39 7 CDS Inspection & Maintenance Log CDS Model: Location: Water Floatable Describe Maintenance Date depth to Layer Maintenance Personnel Comments sediment1 Thickness2 Performed —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— 1. The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than the values listed in table 1 the system should be cleaned out. Note: to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. 2. For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. 1. The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than the values listed in table 1 the system should be cleaned out. Note: to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. 2. For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. SUPPORT • Drawings and specifications are available at www.ContechES.com. • Site-specific design support is available from our engineers. ©2017 Contech Engineered Solutions LLC, a QUIKRETE Company Contech Engineered Solutions provides site solutions for the civil engineering industry. Contech’s portfolio includes bridges, drainage, sanitary sewer, earth stabilization and stormwater treatment products. For information on other Contech division offerings, visit www.ContechES.com or call 800.338.1122 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. The product(s) described may be protected by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6,027,639; 6,350,374; 6,406,218; 6,641,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296,692; 7,297,266; related foreign patents or other patents pending. 800-338-1122 www.ContechES.com cds_manual 3/17 PDF ENGINEERED SOLUTIONS Page 5 of 30 of 39 PDF 1/23 © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com | 800-338-1122 www.ContechES.com ALL RIGHTS RESERVED. PRINTED IN THE USA. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ® Bioretention Systems ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. © 2023 Contech Engineered Solutions LLC, a QUIKRETE Company ALL RIGHTS RESERVED. PRINTED IN THE USA. 39Page 5 of 28 of Page 5 of 38 of 39 SUPPORT • Drawings and specifications are available at www.ContechES.com. • Site-specific design support is available from our engineers. ©2017 Contech Engineered Solutions LLC, a QUIKRETE Company Contech Engineered Solutions provides site solutions for the civil engineering industry. Contech’s portfolio includes bridges, drainage, sanitary sewer, earth stabilization and stormwater treatment products. For information on other Contech division offerings, visit www.ContechES.com or call 800.338.1122 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. The product(s) described may be protected by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6,027,639; 6,350,374; 6,406,218; 6,641,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296,692; 7,297,266; related foreign patents or other patents pending. 800-338-1122 www.ContechES.com cds_manual 3/17 PDF ENGINEERED SOLUTIONS ©2017 Contech Engineered Solutions LLC, a QUIKRETE Company Contech Engineered Solutions provides site solutions for the civil engineering industry. Contech’s portfolio includes bridges, drainage, sanitary sewer, earth stabilization and stormwater treatment products. For information on other Contech division offerings, visit www.ContechES.com or call 800.338.1122 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. The product(s) described may be protected by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6,027,639; 6,350,374; 6,406,218; 6,641,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296,692; 7,297,266; related foreign patents or other patents pending. EXHIBIT C – LEGAL DESCRIPTION 39Page 5 of 39 of PARCEL: 722400-0675 LOT B OF CITY OF RENTON LOT LINE ADJUSTMENT NO. LUA-11-016-LLA RECORDED JUNE 6, 2011 UNDER RECORDING NO. 20110616900016, RECORDS OF KING COUNTY, WASHINGTON. PARCEL: 722400-0676 LOT A OF CITY OF RENTON LOT LINE ADJUSTMENT NO. LUA-11-016-LLA RECORDED JUNE 6, 2011 UNDER RECORDING NO. 20110616900016, RECORDS OF KING COUNTY, WASHINGTON. PARCEL: 759460-0105 LOTS 1-9, BLOCK 8, RENTON FARM PLAT ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 10 OF PLATS, PAGE 97, IN KING COUNTY, WASHINGTON; EXCEPT THOSE PORTIONS OF LOTS 1 THROUGH 5 AS CONDEMNED IN KING COUNTY SUPERIOR COURT CASE NO. 94-2-03644-1 FOR STREET PURPOSES. TOGETHER WITH LOTS 1 THROUGH 12, BLOCK 2, SARTORISVILLE, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 8 OF PLATS, PAGE 7, IN KING COUNTY, WASHINGTON; EXCEPT THE WEST 20 FEET THEREOF.