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RS_Approved_SECO_Park_Avenue_Full_TIR_F_200107_v1
ENGINEERING REPORT Technical Information Report Southport Park Avenue Extension Renton, WA September 2019 PREPARED BY: COUGHLIN PORTER LUNDEEN 801 Second Avenue, Suite 900 Seattle, WA 98104 P 206.343.0460 CONTACT / Tim Brockway, PE, LEED AP BD+C IN COMPLIANCE WITH CITY OF RENTON STANDARDS DEVELOPMENT ENGINEERING bbannwarth 10/04/2019 SURFACE WATER UTILITY jfarah 10/10/2019 TABLE OF CONTENTS I. PROJECT OVERVIEW .................................................................................................................................... 1 General Description .......................................................................................................................................... 1 Existing Conditions ........................................................................................................................................... 1 Proposed Drainage System .............................................................................................................................. 1 II. CONDITIONS AND REQUIREMENTS ............................................................................................................ 3 Special Requirements:...................................................................................................................................... 3 Project Specific Requirements:......................................................................................................................... 4 III. OFF-SITE ANALYSIS ..................................................................................................................................... 5 Task 1 – Study Area Definition and Maps ........................................................................................................ 5 Task 2 - Resource Review ................................................................................................................................ 5 Task 3 - Field Inspection ................................................................................................................................... 5 Task 4 - Drainage System Description and Problem Descriptions ................................................................... 5 Upstream Analysis ........................................................................................................................................ 5 Downstream Analysis .................................................................................................................................... 6 Task 5 – Mitigation of Existing or Potential Problems....................................................................................... 6 IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ....................................... 7 Existing Site Hydrology (Part A) ....................................................................................................................... 7 Developed Site Hydrology (Part B) ................................................................................................................... 7 Performance Standards and Onsite BMP’s (Parts C and D) ............................................................................ 8 Water Quality System (Part E) ........................................................................................................................ 10 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN .................................................................................. 11 Standard Requirements (based on KCSWDM and SAO): .............................................................................. 11 On-site Conveyance ....................................................................................................................................... 11 Existing Conditions: ..................................................................................................................................... 11 Developed Storm System Description: ....................................................................................................... 11 VI. SPECIAL REPORTS AND STUDIES ........................................................................................................... 13 VII. OTHER PERMITS ....................................................................................................................................... 14 VIII. CSWPPP ANALYSIS AND DESIGN .......................................................................................................... 15 Standard Requirements .................................................................................................................................. 15 ESC Analysis and Design (part A) .................................................................................................................. 16 SWPPP Plan Design (Part B) ......................................................................................................................... 16 IX. BOND QUANTITY, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ............................... 18 X. OPERATION AND MAINTENANCE MANUAL ............................................................................................ 19 Standard Maintenance........................................................................................................................................ Appendix A – Figures .......................................................................................................................................... Figure 1 TIR Worksheet .................................................................................................................................. Figure 2 Site Lcoation Map ............................................................................................................................. Figure 3 USDA Soil Survey Map ..................................................................................................................... Figure 4 Sensitive Areas Map ......................................................................................................................... Figure 5 Existing Southport Conditions ........................................................................................................... Figure 6A Proposed Catchment Areas ........................................................................................................... Figure 6B Proposed Subbasin Areas .............................................................................................................. Figure 6C drainage Basin Map ....................................................................................................................... Figure 7A Proposed Southport Conditions ...................................................................................................... Figure 7B Proposed Additional Impervious Area Map .................................................................................... Figure 8 StormFilter Sizing .............................................................................................................................. Figure 9 Flow Control Application Map ........................................................................................................... Figure 10 FEMA Firm Map .............................................................................................................................. Figure 11 Aquifer Protection Map ................................................................................................................... Figure 12 Offsite Analysis ............................................................................................................................... Appendix B– Engineering Calculations ............................................................................................................. Southport Park Avenue Conveyance Analysis) .............................................................................................. Backwater Analysis ......................................................................................................................................... StormFilter Sizing ............................................................................................................................................ 1 I. PROJECT OVERVIEW GENERAL DESCRIPTION The following Technical Information Report (TIR) provides the technical information and design analysis required for developing the Drainage and Temporary Erosion and Sedimentation Control Plan (TESC) for the Southport Park Avenue Extension Project. The stormwater design for the project was based on the requirements set forth in the 2017 Renton Surface Water Design Manual (RSWDM) (See Figure 1 – Technical Information Report Worksheet). The Southport Park Avenue Extension Project is located within the City of Renton, situated north of the existing intersection of Park Avenue and 757th Avenue. The proposed temporary road will extend north of existing Park Avenue and will tie into the existing ground level parking garage tunnel on the Southport office site. (See Figure 2 – Site Location Map). The site is in the NW ¼ of the NW ¼ of Section 8, Township 23 North, Range 5 East, Willamette Meridian. Overall, the proposed roadway addition will include new paving, channelization, signage, and the installation of storm conveyance infrastructure that will connect to an existing storm system on site. The existing site consists of 1.56 acres of gravel and asphalt, all impervious area. The proposed conditions will consist of 0.59 acres of asphalt and concrete sidewalk and 0.97 acres of hydroseed pervious area. The site discharges to the existing Southport property to the north, into a storm conveyance system known as the “PSE Bypass” storm system, as named in the Southport Hotel project. The existing PSE Bypass drainage system already accounts for the northern 0.31 acres of the proposed roadway. This project will add 0.28 acres of impervious surface to the existing PSE Bypass drainage system. Runoff from the site will be captured by catch basins and treated in a Contech Solutions StormFilter catch basin prior to connection into the existing PSE drainage system. Soils for the area were mapped using the King County Soil Survey maps (See Figure 3 – USDA Soil Survey Map), and a Geotechnical exploration has been performed for the public portion of the Park Avenue extension to address slope and soil characteristics. EXISTING CONDITIONS The existing site consists of asphalt and gravel. Storm runoff currently drains south-southwest to north- northeast. There is a total elevation change of approximately 3 feet across the site, from 25 feet in the southwestern region to 22 feet in the northern region of the project limits. See Table 1 for site surface cover information. The BNSF rail at the south end of the site sits at an elevation of approximately 28 feet. PROPOSED DRAINAGE SYSTEM The proposed site consists of asphalt roadway paving, concrete sidewalk placement, and a Contech Solutions StormFilter catch basin. See Table 2 for site surface cover information. According to Table 1.1.2.A of the 2017 Renton Surface Water Design Manual (RSWDM), this project meets the criteria for a Full Drainage Review, including water quality requirements. Per the 2017 RSWDM, since 100% of the runoff will directly discharge to major receiving water body (Lake Washington) Basic Water Quality measures apply. 2 The proposed drainage improvements are confined within the limits of disturbance for the road, along the east side of the adjacent Boeing property line, north of the existing 757th Avenue, and approximately 13ft west of the existing PSE owned building on site. The project site lies within the City’s Existing Peak Flow Control basin. This project is therefore not required to provide flow control for the replaced impervious area, provided the existing downstream system has sufficient capacity to safely convey the added flows. The proposed roadway includes 0.59 acres of impervious area. The existing PSE Bypass drainage system already takes 0.31 acres of the proposed roadway site area into account for conveyance capacity. The remaining 0.28 acres of impervious area will be routed to the existing PSE Bypass system via catch basins and a water quality catch basin. Based on City of Renton GIS data and available survey data, this 0.29 acres of impervious area runoff is being redirected from the existing Boeing drainage system located west of the site to the existing PSE Bypass drainage system. Both systems ultimately drain to Lake Washington. See Southport Park Avenue Conveyance Analysis calculations, which indicate that the existing PSE system has enough capacity to accommodate the additional flows generated by the portion of the proposed roadway that the PSE system does not already account for. Storm runoff will be conveyed by gutter flow to this series of catch basins and will then discharge to the new Contech StormFilter system (See Figure 6A – Proposed Catchment Area and Figure 6B – Proposed Subbasin Area). After being treated, all runoff from the capture area and will be discharged into the existing PSE Bypass storm conveyance system and ultimately discharged into Lake Washington. The existing PSE site drainage system is proposed to be rerouted such that the storm main will run just east of the proposed SECO storm system running along the Park Avenue private extension. The proposed PSE site reconfiguration will continue to connect to the same existing PSE catch basin just north of the proposed road, and runoff will continue to run through the same downstream system and ultimately discharge to Lake Washington. According to the most recent survey, a portion of the runoff from of the project site drains to the adjacent Boeing property to the west of the PSE property. This runoff will continue to discharge to Boeing. See Figure 6A – Proposed Catchment Area for an indication of proposed stormwater routing to remove storm pipe conflicts with the proposed roadway extension. All conveyance on site will be designed according to Chapter 4 of the 2017 Renton Surface Water Design Manual (RSWDM). 3 II. CONDITIONS AND REQUIREMENTS This section will address the requirements set forth by the Core and Special Requirements listed in Chapter 1 of the City of Renton Surface Water Design Manual. City of Renton Surface Water Design Manual Core Requirements: 1. Discharge at the Natural Location (1.2.1): This project proposes to redirect 0.28 acres of runoff from what used to flow to the existing Boeing drainage system located west of the project site to the existing PSE drainage system. Both areas tie into Lake Washington within a quarter mile of the site. 2. Off-site Analysis (1.2.2): Refer to Sections III and IV. A Level 1 downstream analysis has been performed, as this project will discharge to Lake Washington. 3. Flow Control (1.2.3.1): Refer to Section IV. The project is located in a Peak Flow Control Area. Flow control has not been provided for the proposed improvements, due to no increase in flow during the 100-year event. The pre-development condition 100-year peak flow is 1.21 cfs, and the mitigated 100- year peak flow rate is 0.83 cfs. 4. Conveyance System (1.2.4): Refer to Section V. Closed pipe systems, treatment catch basin and extension connections have been provided for stormwater conveyance. 5. Erosion and Sedimentation Control (1.2.5): Refer to Section VIII and the demolition/TESC provided as part of this submittal. The project will construct a series of sediment controls to address the specific conditions at the site. 6. Maintenance and Operations (1.2.6): Refer to Section X. The proposed storm drainage system will be privately owned, operated and maintained by SECO Development. 7. Financial Guarantees and Liability (1.2.7): The owner and contractor will obtain all necessary permits and bonds prior to the beginning of construction. 8. Water Quality (1.2.8): Refer to Section IV. Water quality treatment for runoff from target pollution generating surfaces will be provided by a Contech StormFilter system. See Section IV for more information. 9. Onsite BMP (1.2.9): Refer to Section IV. Onsite BMP’s have been assessed to the maximum extent possible. See Section IV for more information. SPECIAL REQUIREMENTS: Special Requirement #1. Other Adopted Area-Specific Requirements Section 1.3.1 • Critical Drainage Areas (CDAs): Not Applicable • Master Drainage Plans (MDPs): There are no known master drainage plans covering this project site. • Basin Plans (BPs): The project is located within the South Lake Washington – Renton drainage basin. • Lake Management Plans (LMPs): Not Applicable • Shared Facility Drainage Plans (SFDPs): Not Applicable Special Requirement #2. Flood Hazard Area Delineation, Section 1.3.2: See Figure for 100-yr flood zone. The site is within Zone X therefore no 100-yr flood plains have been delineated on the plans. 4 Special Requirement #3. Flood Protection Facilities, Section 1.3.3: Not Applicable Special Requirement #4. Source Controls, Section 1.3.4: See attached Activity Worksheet and Required BMP’s. Special Requirement #5. Oil Control, Section 6.1.5. Traffic counts in this section of roadway do not trigger this requirement due to an anticipated WSDOT Average Daily Two-Way Traffic tabulation of 8,000 trips. No oil control is required. However, the water quality StormFilter system will be a “proprietary facility” as categorized under the High-Use menu (Section 6.1.5) and will remove targeted pollutants. Special Requirement #6. Aquifer Protection Area. Section 1.3.6: See attached Aquifer Protection Map under Appendix A. The site is not located in an Aquifer Protection Zone. Not applicable. PROJECT SPECIFIC REQUIREMENTS: There are no applicable project specific instructions. 5 III. OFF-SITE ANALYSIS TASK 1 – STUDY AREA DEFINITION AND MAPS The Renton drainage basin map was used to verify that the site was fully in the Lake Washington South drainage basin (See Figure 6C – Drainage Basin Map). TASK 2 - RESOURCE REVIEW a) Adopted Basin Plans Lake Washington South drainage basin b) Floodplain/floodway (FEMA) Maps Site is not in the floodplain (See Figure 10) c) Off-site Analysis Reports None d) Sensitive Areas Folio No Sensitive Areas. See Figure 4 and Figure 11 e) Drainage Complaints and Studies No Drainage Complaints. See Figure 4. f) Road Drainage Problems No Current Road Drainage Problems. g) King County Soils Survey: See Figure 3 – USDA Soil Map h) Wetland Inventory Maps: No Wetlands. See Figure 4 i) Migrating Rivers Study Not Applicable. j) DOE’s Section 303d List of Polluted Waters See Section VIII, Part B of this report for Category 5 listings. k) KC Designated Water Quality Problems Not Applicable. l) City of Renton Critical Maps: See Figure 4 and Figure 11. Project is in a seismic area. TASK 3 - FIELD INSPECTION Coughlin Porter Lundeen conducted site visits in preparing the project plans. Please refer to Task 4, Downstream Analysis below for more information. TASK 4 - DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS Runoff from the site will be conveyed through new and existing storm elements that discharge to Lake Washington. The proposed road is designed to direct flows from the Park Avenue curb system to the catch basin system, located on the east side of the road, which collect and treat the runoff before discharging into the existing PSE Bypass system. See Appendix A, Figure 12 – Offsite Analysis Map. Upstream Analysis Upstream of the proposed stormwater conveyance system is a limited segment of the public portion of the Park Avenue extension. This segment of road will be included in the treatment volume for the conveyance 6 design. Runoff will be conveyed to the most upstream catch basin on site through curb flow. See Figure 6A – Proposed Catchmetn Area, for reference. Downstream Analysis As delineated in red on Figure 12 – Offsite Analysis Map, the downstream analysis begins immediately after the furthest downstream proposed pipe ties into the existing PSE Bypass system consisting of man-made catch basins. Runoff generated on the project site discharges through a system of catch basins into an underground drainage tunnel, and ultimately into Lake Washington. The distance from the PSE catch basin this project proposes to tie into to Lake Washington is approximately 750 feet, see Figure 12 for downstream conveyance route. No known drainage problems have been reported with this conveyance system. The Park Avenue Extension project will add 0.28 acres of impervious area runoff to the existing PSE system. This addition of impervious area can be accommodated by the existing PSE drainage system, see Southport Park Avenue Extension Conveyance Analysis calculations. The additional basin area increases the impervious area of the drainage basin (PSE #2a) from 1.26 acres to 1.54 acres, as indicated in the calculations. City of Renton requires an elevation difference of 0.5 feet between the energy grade line and the RIM elevation for the 25-year storm, and the added basin area still allows the system to meet this requirement. TASK 5 – MITIGATION OF EXISTING OR POTENTIAL PROBLE MS The proposed project will not increase the impervious area, as the existing site is fully asphalt-covered, thus the project is not required to provide flow control facilities. The additional 0.28 acres of impervious area to the existing PSE drainage system must work to assure no increased velocities are experienced in the downstream system. Stormwater improvements include proposed treatment of 22,652 SF of pollution-generating impervious surface associated with the roadway. In order to provide treatment for the project prior to the connection with PSE, A Contech StormFilter 4-cartridge treatment system has been proposed. The StormFilter will capture runoff from 0.52 acres of impervious area. The treatment catch basin is designed to capture offline flows of less than 1 cfs, and the project is designed with a water quality offline flow of 0.0543 cfs. Therefore, this StormFilter is designed to safely accommodate the proposed flows. See Figure 8 – StormFilter Sizing. The pipe system itself has been designed with 12-inch ductile iron pipes, allowing for abundant pipe capacity to the system. See Conveyance Calculations, located in Appendix B: Engineering Calculations, which indicate that the system will convey 1.49 cfs of runoff flow in a 100-year storm, and the system can accommodate 2.34 cfs. The pipe that will connect to the existing PSE catch basin will be 18-inch to accommodate the proposed roadway flows as well as the existing PSE pipes that flow into the catch basin prior to connection. 7 IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN EXISTING SITE HYDROLOGY (PART A) The disturbed area of 1.56 acres consists of existing asphalt and gravel beyond paved areas. The site slopes generally south-southwest to north-northeast with about a 3-foot elevation change throughout. The site area conditions are illustrated in Figure 7A and 7B and summarized in Table 1 below. TABLE 1 - EXISTING SITE CONDITIONS AREA BREAKDOWN DESCRIPTION AREA (SQUARE FEET) AREA (ACRES) TOTAL PERVIOUS 0.0 0.0 TOTAL IMPERVIOUS 68,054 1.56 TOTAL DISTURBED AREA 68,054 1.56 DEVELOPED SITE HYDROLOGY (PART B) The developed site hydrology will not increase the amount of impervious area on site, as the existing site is already completely impervious. The addition of roadway and drainage modifications will result in similar site hydrology as it exists currently, before flowing into the proposed water quality treatment facility and then into the existing PSE conveyance system. Flow from the roadway being constructed will be captured and treated before being discharged to the existing PSE system. The system will have 0.28 acres of impervious area runoff added to it, as the existing system only accounts for 0.31 acres of the 0.59-acre roadway and sidewalk. See Figure 7A and 7B – Proposed Conditions, for reference. Sheet flow runoff from the upstream southern- most proposed catch basin will be directed to the catch basin via gutter flow and will then make its way to the StormFilter treatment catch basin once it has been captured into the system. 8 TABLE 2 - DEVELOPED SITE CONDITIONS AREA BREAKDOWN DESCRIPTION AREA (SQUARE FEET) AREA (ACRES) TOTAL PERVIOUS 0.0 0.0 NEW IMPERVIOUS (NEW PGIS) REPLACED IMPERVIOUS (REPLACED PGIS) EXISTING IMPERVIOUS (NPGIS TO REMAIN) 0 22,540 45,514 0 0.52 1.04 TOTAL DISTURBED AREA 68,054 1.56 PERFORMANCE STANDARDS (PARTS C) According to Section 1.2.3.1 (See Figure 9 - Flow Control Application Map) of the 2017 Renton Surface Water Design Manual (RSWDM), this project is located within the Peak Flow Control area. Although this project lies within a flow control basin, the project improvements are allowed to discharge directly to Lake Washington without detention. Given that the project development satisfies all of the Direct Discharge Exemption criteria (discussed below), flow control will not be required. Direct Discharge Exemption Criteria: A) The project site discharges to Lake Washington. B) The conveyance system between the project site and the major receiving water (Lake Washington) will extend to the ordinary high-water mark and will be comprised of manmade conveyance elements (pipes) and will be within a private drainage easement. C) The conveyance system will have adequate capacity to convey the 25-year peak flow (per Core Requirement #4, Conveyance System) for the entire contributing drainage area. D) The conveyance system will be adequately stabilized to prevent erosion E) The direct discharge proposal will not divert flows from or increase flows to an existing wetland or stream sufficient to cause a significant adverse impact. To mitigate the impacts of storm and surface water runoff generated by new impervious surface onsite BMP’s were proposed. Per Section 1.2.9 of the 2017 Renton Surface Water Design Manual (RSWDM) for implementation of BMPs, an evaluation of the BMPs was done. These catch basins serve impervious area only within the proposed Park Avenue extension roadway as shown per Figure 6A: Proposed Catchment Area and Figure 6B: Proposed Subbasin Area. SECO Development will assume maintenance of the Stormfilter and catch basins as they comply with the drainage facility financial guarantee and liability requirements. 9 ON-SITE BEST MANAGEMENT PRACTICES (ON-SITE BMPS) PA RT D Onsite BMP’s have been assessed for this project to mitigate the impacts of storm and surface water runoff generated by new impervious surfaces, existing impervious surfaces, and replaced impervious surface targeted for mitigation. Due to direct discharge to Lake Washington, the LID performance standard does not need to be met and bioretention, permeable pavement, and full dispersion are not required to be considered. However, all other BMP’s have been assessed to the maximum extent possible per section 1.2.9 of the 2017 Renton Surface Water Design Manual (RSWDM). See assessment below. On-site BMPs Assessment SECTION REFERENCE BMP DESCRIPTION ACTION Section C.2.2 Full Infiltration Full Infiltration is infeasible because the groundwater level is relatively high in this area, estimated to be 5 feet below ground surface per the Geotechnical Analysis. Section C.2.3 Limited Infiltration Limited Infiltration is infeasible because the groundwater level is relatively high in this area, estimated to be 5 feet below ground surface per the Geotechnical Analysis. Section C.2.4 Basic Dispersion Basic Dispersion is infeasible because there is not sufficient length to install a dispersion trench, and there are no locations where a “vegetated flowpath segment” of at least 25- feet can be created. Section C.2.13 Soil Amendment Soil Amendment is feasible and has been proposed for the site. Section C.2. Perforated Pipe Perforated Pipe has been deemed infeasible for the project because there are no buildings proposed for the project, as perforated pipe is typically used for draining roof area. 10 WATER QUALITY SYSTEM (PART E) Section 1.2.8.1(A) of the 2017 Renton Surface Water Design Manual (RSWDM) outlines the specific land uses within Basic Water Quality Treatment areas which are subject to providing Enhanced Basic Water Quality treatment. The project discharges to Lake Washington, a Basic Treatment Receiving Water, making it subject to Basic Water Quality treatment for all new and replaced pollution generating impervious surfaces (PGIS). This will be provided by the four-cartridge Contech StormFilter system, which has a General Use Level Designation from the Washington Department of Ecology for basic treatment and was deemed suitable for this application. The water quality catch basin will be installed with the proposed road on the north end, just prior to tie-in to the existing PSE catch basin in order to treat runoff prior to tie-in. TABLE 3. WATER QUALITY TREATMENT AREA SUMMARY NEW PGIS (REQ. TREATMENT AREA) PROPOSED TREATMENT AREA (SEE FIG 4) % DIFFERENCE 22,540 SF (0.52 AC) 22,540 SF (0.52 AC) 0% According to capacity calculations provided by Contech Solutions LLC, the StormFilter catch basin can accommodate all the flows this proposed roadway will generate in a 100-year storm. The StormFilter will capture runoff from 0.52 acres of impervious area. The treatment catch basin is designed to capture offline flows of less than 1 cfs, and the project is designed with a water quality offline flow of 0.0543 cfs. Therefore, this StormFilter is designed to safely accommodate the proposed flows. See Figure 8 – StormFilter Sizing. 11 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN This section discusses the criteria that will be used to analyze and design the proposed storm conveyance system. STANDARD REQUIREMENTS (BASED ON 2017 RSWDM AND SAO): 1. Facilities must convey the 100-year flow without overtopping the crown of the roadway, flooding buildings, and if sheet flow occurs it must pass through a drainage easement. All stormwater conveyance will be designed such that the 100-year flow is conveyed without overtopping the drive aisle or flooding any nearby buildings. 2. New pipe systems and culverts must convey the 25-year flow with at least 0.5 feet of freeboard. (1.2.4.1). The new pipe system discharging from the StormFilter will be designed to convey the 25-year flow. See Conveyance Calculations under Appendix B. These new 12” pipes will meet the conveyance requirement per Section 1.2.4.1. of the 2017 RSWDM. 3. Bridges must convey the 100-year flow and provide a minimum of two feet, varying up to six feet, of clearance based on 25% of the mean channel width. (1.2.4-2)(4.3.5-6). This project does not propose a bridge. 4. Drainage ditches must convey the 25-year flow with 0.5 feet of freeboard and the 100-year flow without overtopping. (1.2.4-2). This project does not propose open channel drainage ditches. 5. Floodplain Crossings must not increase the base flood elevation by more than 0.01 feet [41(83.C)] and shall not reduce the flood storage volume [37(82.A)]. Piers shall not be constructed in the FEMA floodway. [41(83.F.1)]. No work is being proposed within the base flood elevation or within the FEMA floodway. 6. Stream Crossings shall require a bridge for class 1 streams that does not disturb or banks. For type 2 and type 3 streams, open bottom culverts or other method may be used that will not harm the stream or inhibit fish passage. [60(95.B)]. The project does not propose a stream crossing. 7. Discharge at natural location is required and must produce no significant impacts to the downstream property (1.2.1-1). The project will discharge to the existing PSE storm system and to Lake Washington, ultimately. ON-SITE CONVEYANCE Existing Conditions: Generally, stormwater runoff flows south to north by sheet flow to four existing PSE catch basins on site. This runoff is taken offsite to the north through the Southport site to Lake Washington. Developed Storm System Description: The project will add roughly 22,540 SF of new PGIS associated with the proposed roadway. The northern portion of this site is already accounted for as being conveyed into the existing PSE drainage system. This 12 project proposes to add 12,640 SF to the existing system, once treated. Storm runoff will be conveyed by gutter flow to the four new catch basins and will then be conveyed into the Contech StormFilter catch basin (See Figure 6A – Proposed Catchment Area and Figure 6B – Proposed Subbasin Area). After being treated, all runoff from the capture area and unaffected existing impervious area that currently drains elsewhere will be conveyed through pipe to the PSE Bypass system and ultimately to Lake Washington. The conveyance and backwater calculations are provided as part of Appendix B: Engineering Calculations. The proposed drainage system will connect to the existing system that was constructed with the Southport Hotel project. The PSE drainage basin that this project will connect to is called PSE #2. Basins PSE #3 and PSE #4 are existing basins that were designed with the Hotel project, and they drain to Basin PSE #2. The new basins are CB#1 through CB#6, and their naming conventions match the naming conventions shown in the drainage plan submitted with this report, for ease of understanding. The graphic shown on the first page of these conveyance calculations indicates that 0.22 acres of the project were already incorporated as part of the conveyance analysis for the Southport Hotel project. The Park Avenue extension project proposes to add 0.29 acres of impervious surface to the conveyance system, so these calculations serve to prove that the existing system has the capacity to handle this additional runoff. 13 VI. SPECIAL REPORTS AND STUDIES Geotechnical Engineering Report, Park Avenue Extension Prepared by Hart Crowser, Inc. (dated July 31, 2019) Geotechnical Engineering Design Study Southport Park Avenue Extension Renton, Washington Prepared for SECO Development July 31, 2019 19014-11 19014-11 July 31, 2019 Contents INTRODUCTION 1 PURPOSE, SCOPE, AND THE USE OF THIS REPORT 1 SUBSURFACE CONDITIONS 2 GEOTECHNICAL ENGINEERING DESIGN AND RECOMMENDATIONS 3 Pavement and Sidewalk Design Recommendations 3 Additional Subsurface Investigations 4 Anticipated Settlement 4 Luminaire, Sign, and Fencing Foundations 5 CONSTRUCTION RECOMMENDATIONS 5 Utilities 6 Compaction Equipment 6 Structural Fill 7 Temporary Excavations 7 Excavation Groundwater Control 8 Site Drainage and Erosion Control 8 RECOMMENDATIONS FOR CONTINUING GEOTECHNICAL SERVICES9 TABLES Table 1 – Estimated CBR of Subgrade Soils 2 Table 2 – Allowable Lateral Bearing Capacities 5 FIGURES Figure 1 – Site and Exploration Plan APPENDIX A Explorations and Laboratory Testing by Others 19014-11 July 31, 2019 Geotechnical Engineering Design Study Southport Park Avenue Extension Renton, Washington INTRODUCTION This report presents our design recommendations for a flexible asphalt pavement section for a new temporary road to the Southport offices. We also provide fence and signage foundation recommendation and considerations for new and existing utilities. It is our understanding that the new private road will extend the existing Park Avenue through the west side of the existing Puget Sound Energy (PSE) property and access the office buildings from the southwest corner of the site. This road will be considered a temporary road while development of a future building progresses. See Figure 1 for project location and site plan. Our understanding of the project comes from discussions with SECO Development and the 60 percent plan set from CPL, dated May 25, 2019. We understand the road will connect to a public extension of Park Avenue at the property line. The road will cross the BNSF railway tracks and require placing a significant amount of fill around the tracks just south of the property line. It is our understanding that the City of Renton’s embankment design around the BNSF railroad mitigates settlement of the railroad tracks, limiting settlement to approximately 0.25 inch. The City’s consultant calculated a baseline of 2 inches of settlement if the embankment were completed with traditional structural fill. PURPOSE, SCOPE, AND THE USE OF THIS REPORT The purpose of our work was to assess subsurface information and provide geotechnical engineering recommendations for the design of the Park Avenue extension project and associated infrastructure at Southport. Our scope of work for this project included: Corresponding with the design team; Reviewing recent geotechnical explorations; Performing two Dynamic Cone Penetrometer (DCP) tests; Providing geotechnical engineering recommendations; and Writing this report. We prepared this report for the exclusive use of SECO Development and their design consultants for specific application to the Southport Park Avenue extension project and site location. This report was prepared in accordance with our contract, dated May 31, 2019. Within the constraints of schedule and budget, we completed the work according to generally accepted geotechnical practices in the same or similar localities, related to the nature of the work accomplished, at the time the services were accomplished. We make no other warranty, express or implied. 2 | Southport Park Avenue Extension 19014-11 July 31, 2019 SUBSURFACE CONDITIONS The Southport site is known to have settlement concerns when placing new fill. We have discussed this with the project team and noted that the roadway section may be subject to settlement caused by the placement of the road and any utility backfill. It is our understanding that up to a couple inches of post- construction settlement is acceptable to SECO and that the road should be designed to account for the traffic loading, with the knowledge that future pavement overlays may be needed if the road has excessive settlement caused by the compression of the native soils beneath the new embankment, pavement, and storm drain utility line. The proposed project area is currently a fenced, gravel yard for PSE. We performed two DCP tests within the proposed new roadway boundaries to evaluate the existing subgrade on site (HC19-DCP1 and HC19- DCP2). See Figure 1 for locations. Refusal was encountered with the DCP between 0.5 and 2.5 inches below existing ground surface. A rock hammer and shovel were used to dig at the DCP test locations and confirm that very dense, dry, sandy gravel and cobble fill existed to at least 12 inches below existing grade. Logs from the two new DCP tests are not included in this report because refusal conditions were encountered immediately. A soil boring was drilled near the south side of the project site in February 2019 for the City of Renton project related to the Park Avenue extension. Boring BH-4 shows that loose silty sands or soft sandy silt may exist beneath the existing fill encountered in the DCP tests. There is no information in the boring suggesting the samples were taken in the upper 2 feet of BH-4. We are relying upon BH-4 for subsurface information deeper than the observed and assumed gravel depths. The explorations and laboratory testing completed by the City of Renton’s consultant are included in Appendix A. To assess the existing subgrade at the site for pavement design, the California Bearing Ratio (CBR) of soils can be estimated from the measured DCP penetration index (DCPI) or Standard Penetration Test (SPT) blow counts. Table 1, below, presents the estimated CBR of subgrade materials encountered in both DCPs and in BH-4. CBR is expressed as a percentage, so values over 100 are not realistic, but do indicate a very dense material with high bearing capacity. For soils with an estimated CBR of greater than 100, a value of 100 was used in our analysis. Table 1 – Estimated CBR of Subgrade Soils Exploration ID Subgrade Material Average DCPI or N-value Estimated CBR (%) HC19-DCP1 poorly-graded gravel (fill) 0.02a 2100 HC19-DCP2 poorly-graded gravel (fill) 0.02a 1000 BH-4 silty sand to sandy silt 3b 3 to 5 Notes: a. DCPI in inches per blow. b. N-value from SPT in blows per foot. Southport Park Avenue Extension | 3 19014-11 July 31, 2019 GEOTECHNICAL ENGINEERING DESIGN AND RECOMMENDATIONS We have developed our recommendations based on our current understanding of the project and the subsurface conditions encountered by our explorations. If the nature or location of the development is different than we have assumed, we should be notified so we can change or confirm our recommendations. Pavement and Sidewalk Design Recommendations It is our opinion that the existing gravel fill will provide suitable subbase for the new asphalt pavement section, provided at least 12 inches of the material remains in place below the new pavement section. The soft underlying soils encountered in BH-4, however, may require a larger section, if encountered. In general, we recommend the pavement section consist of 6 inches of asphalt concrete over 6 inches of crushed surfacing base course (CSBC) over a firm subbase (subgrade). We recommend the following subbase materials for the varying conditions on site: Option A. In areas where at least 12 inches of the existing gravel fill material will remain in place below the new pavement section, we recommend using the existing fill as the subbase and placing CSBC directly on the surface. If the surface of the fill is disturbed by construction activities, limited compaction effort may be necessary. Option B. In areas where less than 12 inches of the existing gravel fill material will remain in place, we recommend overexcavating and backfilling with a subbase of at least 12 inches of structural fill compacted to at least 95 percent relative density and underlain with TenCate Mirafi RS280i Geosynthetic fabric. The geosynthetic recommended in Option B is intended to act as a separator and provide subgrade reinforcement, reducing the likelihood of observable differential settlement occurring. If the pavement section is being placed on at least 24 inches of newly placed and compacted fill, such as when the pavement is over utility backfill or embankment fill, no geosynthetic is needed. In this case, backfill within 24 inches of the pavement should be compacted to 95 percent relative density. Sidewalks should have the same 12 inches of subbase (subgrade) thickness beneath their design section. The CSBC should conform to Section 9-03.9(3) base course of the Washington State Department of Transportation (WSDOT) Standard Specifications and the structural fill should be in accordance with recommendations in the following sections of this report. This pavement section was based on a design life of 5 to 10 years and an estimated lifetime load of about 650,000 equivalent single axle load (ESALs). ESALs were calculated using an anticipated average daily two- way traffic total of 8,000 vehicles, with 2 percent growth, and 5 percent truck traffic. 4 | Southport Park Avenue Extension 19014-11 July 31, 2019 We analyzed the pavement using the design methods outlined in AASHTO Guide of Pavement Structures 1993 and implemented in the WSDOT approved software PaveExpress. The traffic loading results in a required structural number of 2.2. The pavement section described above should provide a structural number of at least 3.5, resulting in a relatively conservative design, even for a traditional 15-year design life. It is not advisable to attempt to further reduce the pavement section due to constructability concerns of lifts less than 6 inches. This pavement section is sufficient for a 15-year design life, based on the near surface subgrade conditions observed, and the traffic loading provided to us by TENW. Additionally, this pavement section is the standard WSDOT Hot Mix Asphalt (HMA) pavement section for design period traffic loading anticipated over the next 15 years if the road transitions from a temporary (5 year) design life to a traditional use case. Additional Subsurface Investigations During our investigation, we were only able to confirm the existence of the gravel fill to a depth of 12 inches below existing grade. To better identify areas where thin fill or soft subgrade may be exposed, and to potentially reduce the amount of overexcavation required, the contractor should verify the extent and depth of the existing gravel fill by potholing several locations along the planned road prior to the start of construction where new backfill is not anticipated for utilities. Anticipated Settlement According to the 60 percent plan set, up to 9 feet of fill will be placed on site as an approach embankment for Park Avenue to cross the existing railroad. Boring BH-4 indicated that soft, compressible soils exist on site, which will be subjected to consolidation settlement due to loading from the new embankment. Our analysis indicates the proposed embankment could experience up to 2 inches of total settlement on the north end (approximately 1.5 feet of new fill) and 6 to 11 inches of total settlement on the south end near the rail road (approximately 9 feet of new fill). The magnitude of total settlement may be reduced in areas where poor subgrade is overexcavated and replaced with compacted structural fill as described in our recommendations for the roadway pavement section. Consolidation settlement is both time- and stress-dependent. Areas of thicker fill placement will likely continue to settle over the lifetime of the road, whereas thinner areas of fill may cease to show any observable settlement earlier than the planned lifespan. Maintenance and asphalt overlays should be expected on the south side of the embankment for the planned 5- to 10-year lifespan of the road. Settlement Mitigation We understand the developer intends to preload the approach embankment prior to placing the final surfacing. In other words, the approach embankment will be rough graded for a period of time to allow the majority of settlement to occur, at which point in time the final grading will occur. Our understanding is that no utilities will be placed beneath the fill, therefore the risk of settlement is limited to structures installed on or in the embankment. Based on Boring BH-4, and correlations with the information collected with the boring, we anticipate that allowing the embankment fill to settle for a period of approximately Southport Park Avenue Extension | 5 19014-11 July 31, 2019 two to four weeks should result in less than 2 inches of post-construction settlement from primary consolidation. Given the high uncertainty in these calculations, we recommend monitoring the settlement of the embankment with near surface settlement points during construction to better refine the magnitude of long-term settlement and determine when the final grading should occur. This will require support from the contractor to install and survey the settlement monitoring points. This estimate of settlement does not account for secondary settlement, which should occur over a relatively wide area and gradually over a long period of time, but is generally a small portion of the total settlement observed in silts. Based on BH-4, the soft silt layer that is the source of the majority of the calculated settlement is up to approximately 7 feet below ground surface. Based on the 60 percent plan set, the trenching for the utilities will likely excavate most, if not all, of the soft silt from beneath the proposed utility line. By removing the soft silt, the potential for settlement is reduced, which should result in significantly less than 2 inches of settlement of the storm line. Luminaire, Sign, and Fencing Foundations Lightly loaded foundation elements, such as those for the luminaires, fence, and gate posts planned on site, can be designed using allowable lateral bearing pressures recommended in the WSDOT Geotechnical Design Manual (GDM). The allowable lateral bearing pressures for soils anticipated on site are listed below in Table 2. For foundations in multiple soil types, use a weighted average of the allowable bearing pressures. Table 2 – Allowable Lateral Bearing Capacities Soil Type Allowable Lateral Bearing Pressure (pounds per square foot) Soft native subgrade 800 Existing gravel fill 4500 New Fill (pipe zone backfill or structural fill)a 4500 Notes: a. Assumed compacted in place to 95 percent relative density. The allowable pressures listed above only apply to relatively flat ground conditions. For foundation elements of diameter “B” placed in or within 1B of a slope steeper than 3H:1V, additional depth of foundation is required. For 2H:1V or flatter slopes, add 0.5B to the depth of the foundation. For 1.5H:1V or flatter slopes, add 1B to the depth. Interpolation may be used between these values. According to the WSDOT GDM, these additional depth requirements do not apply to luminaire foundations. CONSTRUCTION RECOMMENDATIONS We have developed our recommendations for construction based on our current understanding of the project and the subsurface conditions encountered by our explorations. If the nature or location of the 6 | Southport Park Avenue Extension 19014-11 July 31, 2019 development is different than we have assumed, we should be notified so we can change or confirm our recommendations. Utilities Compressible soils may exist deeper than the typical depth of buried utilities; therefore, utilities placed under areas of raised grade may settle along with the new fill. In areas where the grade will be raised above the current ground surface, we recommend installing utilities after placing the backfill to reduce the amount of utility settlement. Utility connections should be as flexible as possible, and utility grades and slopes should be adjusted, as appropriate, to adapt to the expected settlement. For shallow utilities, we anticipate that open-cut trenches and/or trench boxes could be used for utility trench excavations. Our understanding is that a storm drain will likely be installed to a depth of approximately 2 to 4 feet below existing grade. This depth will likely remove much of the soft silt that was observed in BH-4, but will likely require placement of a separation fabric as described below. Our recommendations for bedding and trench backfill materials are presented below. The minimum percent compaction recommended below is a percentage of the modified Proctor maximum dry density, as determined by the ASTM D1557 test procedure. At least 4 inches of bedding is recommended for all utility pipes. We recommend that bedding materials consist of well-graded sand and gravel with less than 3 percent material passing the U.S. No. 200 mesh sieve (based on the minus 3/4-inch fraction). Bedding material should be compacted using care not to damage the utility pipes. The recommended bedding backfill materials can be used as backfill around the pipe utilities (pipe zone backfill). Pipe zone backfill should extend to at least the top of the pipe. For bedding material beneath catch basins and manholes, we recommend at least 6 inches of imported structural fill (or acceptable on-site material) that consists of well-graded sand and gravel with less than 3 percent passing the U.S. No. 200 mesh sieve (based on the minus 3/4-inch fraction). The bedding material should be compacted to at least 90 percent. If the bottom of the excavation is in soft silt, which existing explorations indicate is possible, a separation fabric should be used to line the pipe trench and keep the clean bedding and backfill from becoming contaminated with fine-grained soil. Compaction Equipment Generally, we recommend using hand-operated compaction equipment within 12 inches of any pipe, catch basin, or similar structure to reduce the risk of damage. In cases with more than 12 inches distance from pipes and structures, it is common to use a vibratory plate compactor attached to a backhoe, or even a self-propelled roller. The contractor should be responsible for selecting appropriate compaction equipment and adjusting the lift thickness and moisture content of the backfill as needed for adequate compaction and to avoid Southport Park Avenue Extension | 7 19014-11 July 31, 2019 damage to the pipe. In general, heavy mechanical compaction equipment should not be allowed over the pipe until the backfill is at least 2 feet above the top of the pipe. All utilities and utility-related construction, including soil gradation, should conform to City of Renton Standard Plans and Specifications. Structural Fill Soils placed beneath structures, around utilities, or below paved areas should be considered structural fill. In these fill areas, we recommend the following: Structural fill should only be placed on a dense and non-yielding subgrade. For imported soil to be used as structural fill, we recommend using a clean, well-graded sand or sand and gravel with less than 5 percent by weight passing the U.S. No. 200 mesh sieve (based on the minus 3/4-inch fraction) for grading in wet conditions. Compaction of material containing more than about 5 percent fine material may be difficult if the material is wet or becomes wet. During dry grading conditions, the fines content may be increased provided the soil is compacted near its optimum moisture content. Place and compact all structural fill in lifts with a loose thickness no greater than 10 inches. If small, hand-operated compaction equipment is used to compact structural fill, fill lifts should not exceed 6 inches in loose thickness. Control the moisture content of the fill to within 2 percent of the optimum moisture. Optimum moisture is the moisture content corresponding to the maximum modified Proctor dry density. Below all structures, the compaction requirement should be at least 95 percent. The minimum percent compaction recommended herein is a percentage of the modified Proctor maximum dry density, as determined by the ASTM D1557 test procedure. If wet subgrade areas are encountered during foundation or pavement section preparation, clean material with a gravel content (material coarser than a U.S. No. 4 sieve) of at least 30 to 35 percent may be necessary. The compacted densities of each lift should be verified by a Hart Crowser representative. Before fill control can begin, the compaction characteristics must be determined from representative samples of the structural and drainage fill. Samples should be obtained as soon as possible. A study of compaction characteristics should include determination of optimum and natural moisture contents, maximum dry density, and gradation of these soils. Temporary Excavations For planning purposes, we recommend that temporary unsupported open-cut slopes be designed in accordance with current Washington Industrial Safety and Health Act (WISHA) rules and regulations for a 8 | Southport Park Avenue Extension 19014-11 July 31, 2019 Type C soil. Note that unshored cuts deeper than 4 feet will need to be sloped; cuts shallower than 4 feet do not require sloping. The contractor should be made responsible for the stability of all temporary excavation, ground settlement and associated damage to nearby structures, and worker safety. Excavations deeper than approximately 5 feet below the existing ground surface could encounter groundwater. We anticipate that the majority of the excavations could be completed with conventional earthwork equipment. In addition, excavations must conform to federal, state, and local safety regulations. Excavation Groundwater Control Groundwater is anticipated at approximately 5 feet below the existing ground surface and may seep into excavations. However, it will likely flow slowly enough to be controllable using conventional means. In general, shallow excavations do not require a detailed dewatering plan if the depth of the cut is less than about 7 feet below existing grade. Reasonably dry conditions should be able to be maintained by pumping from one or two sumps located within each excavation. The excavation side walls should be protected from sloughing by using steel sheets or similar protection. Site Drainage and Erosion Control Final grades should be sloped to carry surface water runoff away from project features and prevent ponding. New surface water drainage should not be tied into the subdrain system and should not discharge onto the site. In general, the on-site soils are not suitable for stormwater infiltration. We understand no infiltration is planned for this project. We recommend the following for excavation or earthwork in wet conditions to minimize erosion and sediment transport: Earthwork and excavation work areas should be limited to minimize subgrade exposure to excessive moisture via infiltration. Excavation of unsuitable or disturbed subgrade should be immediately followed by placement and compaction of structural fill. Limit the fines content of structural fill to less than 5 percent by weight, as described in the previous sections. The ground surface within the construction area should be maintained at a slope to prevent ponding on site. Cuts, fills, stock piles, and any other soils on site should not be left uncompacted or unprotected and exposed to infiltration. Straw waddles or bales and/or geotextile silt fences should be installed in any necessary locations along the perimeter of the site to prevent the migration of soils. Southport Park Avenue Extension | 9 19014-11 July 31, 2019 RECOMMENDATIONS FOR CONTINUING GEOTECHNICAL SERVICES Before construction begins, we recommend that we review the final design plans to satisfy City requirements and that the geotechnical engineering recommendations have been properly interpreted and implemented in the design. During construction, we recommend that we be retained to review contractor submittals, provide geotechnical engineering support as needed, and observe the following activities: Additional subsurface explorations (i.e. potholing), if any; Preparation of pavement and utility subgrade; Placement and density testing of structural fill at the site, if any; Backfilling of utility trenches; and Other special inspection items as required by Seattle Department of Construction and Inspections (SDCI). The purpose of our observations is to verify compliance with design concepts and recommendations, and to allow design changes or evaluation of appropriate construction methods in the event that subsurface conditions differ from those anticipated prior to the start of construction. \\seafs\Projects\Notebooks\1901411_Southport_Park_Ave_Extension\Deliverables\Reports\1901411_Southport Park Ave Report_FINAL\Southport Park Avenue Extension_Final.docx Document Path: L:\Notebooks\1901411_Southport_Park_Ave_Extension\GIS\MGIS\1901411-AA (SPlan).mxd Date: 6/7/2019 User Name: evinfairchild!! !! !! HC19-DCP1 HC19-DCP2 BH-4 N Note: Feature locations are approximate. 0 80 16040 Feet Southport Park Ave Extension Renton, Washington Site and Exploration Plan 19014-11 6/19 Figure1 Source: Aerial photograph provided by Hexagon Imagery Program Data. Legend !!DCP Te st Location (H art C ro wser 2019) !!Boring (H WA GeoSciences 201 9) Project Boun dary Propo se d Asphalt Pavem ent 19014-11 July 31, 2019 APPENDIX A Explorations and Laboratory Testing by Others AL GS GS GS GS HYD GS GS GS S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 Soft, rust-mottled olive-gray, very sandy SILT, moist. Low plasticity. (ALLUVIUM) Becomes dark yellow-brown. Non-plastic. Very loose, rust-mottled, yellow-brown, very silty SAND, wet. Grades to dark gray. Becomes loose, dark gray. Becomes slightly gravelly. Becomes medium dense. Very loose, dark gray, slightly gravelly, slightly silty SAND, wet. Piece of decomposed wood in tip of sampler. Driller reports encountering decomposed wood from 20 feet to 23 feet. Medium dense, dark gray, silty SAND, wet. Driller reports drilling action at 27 feet. Medium dense dark gray, very gravelly, slightly silty SAND, wet. Driller reports drilling action ends at 32 feet. 1-1-2 1-2-2 1-1-1 2-3-5 2-3-4 2-2-2 7-6-5 1-1-1 6-4-4 12-9-9 ML SM SP SM SM SP SM SM BORING-DSM 2017-147-21.GPJ 2/22/19 FIGURE:PROJECT NO.:2017-147-21 RENTON, WASHINGTON PARK AVENUE N EXTENSIONDEPTH(feet)0 5 10 15 20 25 30 35 25 20 15 10 5 0 -5ELEVATION (feet)BH-4 PAGE: 1 of 2(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid LimitSYMBOL010203040 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%) NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations. (140 lb. weight, 30" drop) Blows per foot A-5 Standard Penetration Test DATE COMPLETED: 1/4/2019 DRILLING COMPANY: Geologic Drill Partners, Inc. DRILLING METHOD: Diedrich D-120 Truck Rig, 4.25" ID HSA LOCATION: See Figure 2 DATE STARTED: 1/4/2019 SAMPLING METHOD: SPT w/ Autohammer LOGGED BY: Z. Ngoma SURFACE ELEVATION: 27.0 feet GS HYD AL GS GS HYD GS HYD GS S-11 S-12 S-13 S-14 S-15 S-15 Medium dense, dark gray, silty SAND, wet. Very soft, olive-brown, organic SILT, moist. High plasticity. Drove Shelby Tube at 50 feet and it was advanced 13 inches. Medium Dense, gray, silty SAND, moist. Driller reports gravelly drilling action at 51 feet. Becomes dark gray. Minor organics. Very stiff, dark olive-brown, sandy organic SILT, moist. High plasticity. Borehole terminated 61.5 feet below ground surface (bgs). Ground water seepage encountered at approximately 5 feet bgs during drilling. Borehole completed as a 2-inch PVC well (DOE # BKC 472). 8-10-12 0-0-0 1-1-1 13-11-13 11-10-14 OH SM OH BORING-DSM 2017-147-21.GPJ 2/22/19 FIGURE:PROJECT NO.:2017-147-21 RENTON, WASHINGTON PARK AVENUE N EXTENSIONDEPTH(feet)35 40 45 50 55 60 65 70 -10 -15 -20 -25 -30 -35 -40ELEVATION(feet)BH-4 PAGE: 2 of 2(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid LimitSYMBOL010203040 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%) NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations. (140 lb. weight, 30" drop) Blows per foot A-5 Standard Penetration Test DATE COMPLETED: 1/4/2019 DRILLING COMPANY: Geologic Drill Partners, Inc. DRILLING METHOD: Diedrich D-120 Truck Rig, 4.25" ID HSA LOCATION: See Figure 2 DATE STARTED: 1/4/2019 SAMPLING METHOD: SPT w/ Autohammer LOGGED BY: Z. Ngoma >>128 SURFACE ELEVATION: 27.0 feet 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-11b S-2 S-3 30.5 - 31.5 5.0 - 6.5 7.5 - 9.0 #10 80.0 39.0 62.8 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND B-12 Coarse #60#40#20 Fine Coarse SYMBOL Gravel % 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 0.7 1.6 Sand % (SM) Dark gray, silty SAND (ML) Dark yellowish-brown, sandy SILT (SM) Very dark grayish-brown, silty SAND Fines % 0.00050.005 CLAY BH-3 BH-4 BH-4 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 29 42 42 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D6913 19.3 59.4 37.2 2017-147-21PROJECT NO.: HWAGRSZ 2017-147-21.GPJ 01/28/19 FIGURE: PARK AVENUE N EXTENSION RENTON, WASHINGTON 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-4 S-6 S-8 10.0 - 11.5 15.0 - 16.5 20.0 - 21.5 #10 75.6 68.5 78.8 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND B-13 Coarse #60#40#20 Fine Coarse SYMBOL Gravel % 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 7.6 9.6 Sand % (SM) Dark gray, silty SAND (SM) Dark gray, silty SAND (SP-SM) Dark gray, poorly graded SAND with silt Fines % 0.00050.005 CLAY BH-4 BH-4 BH-4 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 35 30 36 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D6913 24.4 24.0 11.7 2017-147-21PROJECT NO.: HWAGRSZ 2017-147-21.GPJ 01/28/19 FIGURE: PARK AVENUE N EXTENSION RENTON, WASHINGTON 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-9 S-10 S-11 25.0 - 26.5 30.0 - 31.5 35.0 - 36.5 #10 72.7 52.2 73.3 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND B-14 Coarse #60#40#20 Fine Coarse SYMBOL Gravel % 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 1.1 41.9 5.0 Sand % (SM) Dark gray, silty SAND (SP-SM) Dark gray, poorly graded SAND with silt and gravel (SM) Dark gray, silty SAND Fines % 0.00050.005 CLAY BH-4 BH-4 BH-4 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 30 15 29 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D6913 26.2 6.0 21.7 2017-147-21PROJECT NO.: HWAGRSZ 2017-147-21.GPJ 01/28/19 FIGURE: PARK AVENUE N EXTENSION RENTON, WASHINGTON 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-13 S-14 S-15 45.0 - 46.5 50.0 - 51.1 55.0 - 56.5 #10 11.4 86.9 81.1 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND B-15 Coarse #60#40#20 Fine Coarse SYMBOL Gravel % 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 3.3 Sand % (OH) Olive-brown, organic SILT (SM) Gray, silty SAND (SM) Dark gray, silty SAND Fines % 0.00050.005 CLAY BH-4 BH-4 BH-4 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 78 22 27 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D6913 88.6 13.1 15.6 2017-147-21PROJECT NO.: HWAGRSZ 2017-147-21.GPJ 01/28/19 FIGURE: PARK AVENUE N EXTENSION RENTON, WASHINGTON 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-15 S-1 S-3 60.0 - 61.5 0.0 - 1.5 5.0 - 6.5 #10 22.6 64.1 59.3 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND B-16 Coarse #60#40#20 Fine Coarse SYMBOL Gravel % 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 1.7 17.6 14.6 Sand % (OH) Very dark grayish-brown, organic SILT (SM) Olive-brown, silty SAND with gravel (SM) Dark grayish-brown, silty SAND Fines % 0.00050.005 CLAY BH-4 BH-5 BH-5 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 84 11 12 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D6913 75.7 18.3 26.0 2017-147-21PROJECT NO.: HWAGRSZ 2017-147-21.GPJ 01/28/19 FIGURE: PARK AVENUE N EXTENSION RENTON, WASHINGTON 0 10 20 30 40 50 60 0 20 40 60 80 100 % MC LL CL-ML MH SAMPLEPLASTICITY INDEX (PI)SYMBOL PL PI S-4 S-3 S-9 S-1 10.0 - 11.5 7.5 - 9.0 25.0 - 26.5 2.5 - 4.0 27 26 23 29 42 40 45 45 LIQUID LIMIT, PLASTIC LIMIT AND PLASTICITY INDEX OF SOILS METHOD ASTM D4318 CL (ML) Olive-brown, SILT (ML) Olive-gray, SILT (ML) Dark gray, SILT (ML) Grayish-brown, SILT B-21 14 8 4 9 CH CLASSIFICATION % Fines LIQUID LIMIT (LL) BH-1 BH-2 BH-2 BH-4 ML 41 34 27 38 DEPTH (ft) 2017-147-21PROJECT NO.: HWAATTB 2017-147-21.GPJ 01/28/19 FIGURE: PARK AVENUE N EXTENSION RENTON, WASHINGTON 0 50 100 150 200 250 0 40 80 120 160 200 240 280 320 360 DEPTH (ft) 17.5 - 18.3 40.0 - 41.5 (OH) Brown, organic SILT (OH) Olive-brown, organic SILT 163 87 BH-1 BH-4 S-6a S-12 CH MH B-22 LIQUID LIMIT (LL)PLASTICITY INDEX (PI)SYMBOL SAMPLE LIQUID LIMIT, PLASTIC LIMIT AND PLASTICITY INDEX OF SOILS METHOD ASTM D4318 CLASSIFICATION % MC LL PL PI % Fines 217 134 54 47 165 128 CL-ML ML CL 2017-147-21PROJECT NO.: HWAATTB7 2017-147-21.GPJ 01/28/19 FIGURE: PARK AVENUE N EXTENSION RENTON, WASHINGTON 14 VII. OTHER PERMITS This project will require a City of Renton Civil Construction permit, City of Renton Land Use permit, and NPDES permit. 15 VIII. CSWPPP ANALYSIS AND DESIGN This section lists the requirements that will be used when designing the TESC plan for this site. A copy of the Draft CSWPPP has been included at this time. STANDARD REQUIREMENTS Erosion/Sedimentation Plan shall include the following: 1. Clearing Limits a. Clearing limits are noted on plans and will be implemented prior to any offsite impacts or damage due to construction. 2. Cover Measures a. During construction, temporary cover BMPs will be implemented to prevent erosion. The project will meet wet season cover requirements. 3. Perimeter Protection a. Silt Fence will be implemented around construction limits to preserve undisturbed areas. 4. Traffic Area Stabilization a. The Contractor, per the plans, shall implement necessary BMP measures to ensure sediment does not leave the site onto streets or adjacent properties. 5. Sediment Retention a. Inlet protection will be implemented to prevent sediment from entering the existing drainage system. 6. Surface Water Collection a. Existing stormwater catch basins on-site that are proposed to remain will continue to operate during construction to collect runoff. 7. Dewatering Control a. Dewatering needs shall be monitored throughout construction. 8. Dust Control a. Dust control BMPs will be implemented throughout construction. 9. Flow Control a. Flow control is not required for the project as there will be no increase in impervious surface coverage. 10. Control Pollutants a. BMPs shall be implemented to prevent or treat contamination of stormwater runoff by pH modifying sources. In addition, all waste materials from the site will be removed in a manner that does not cause contamination of water. 11. Protect Existing and Proposed Stormwater facilities and On-Site BMPs a. Inlet protection BMPs will be implemented on the site for existing and proposed catch basins affected by construction. 12. Maintain Protective BMPs 16 a. BMPs listed in the SWPPP shall be maintained as needed through the project. As portions of the project get completed, portions of the established BMPs shall be adjusted to other areas of the project site until their completion. 13. Manage the Project a. Proposed erosion and sediment control measures will be implemented throughout construction. ESC PLAN ANALYSIS AND DESIGN (PART A) 1. The Standard Requirements above indicate the overall ESC Plan approach and justify these methods based on circumstances specific to the Southport Park Avenue extension project. 2. The proposed Contech StormFilter catch basin is the primary ESC and water quality treatment facility that was analyzed for appropriateness to the project and sizing. Refer to Appendix B: Engineering Calculations for the StormFilter catch basin sizing calculations. 3. The project site is currently flat with complete impervious surface coverage, giving it a low chance of erosion risk. Once construction is complete, the road will be graded at a 2.0% slope, and the surface off the road will grade down at a 3H:1V slope, which is consistent with City of Renton requirements. This grading design will prevent on-site erosion. 4. Please refer to the SWPPP provided with this report for a full list of BMPs recommended for construction. The special reports do not provide further BMP recommendation than what is discussed in the SWPPP. 5. All techniques and products proposed for this project meet standards set in the Erosion and Sediment Control Standards in Appendix D of the City of Renton Stormwater Design Manual. SWPPS PLAN DESIGN (PART B) The CSWPPP that has been included with this report identifies all activities that could contribute pollutants to surface and storm water during construction. The receiving water body for this project, Lake Washington, has 25 Category 5 listings: · Sediment – Assessment Unit ID: 47122F2D0_SW and 47122F2D0_SE · Chlordane – Assessment Unit ID: 47122G2D5, 47122F2B6, 47122F2B3 · Dieldrin - Assessment Unit ID: 47122F2B3, 47122F2D5, 47122F2B6 · Bacteria - Assessment Unit ID: 47122G2D7, 47122G2H0, 47122F2A0 · 4,4’-DDE – Assessment Unit ID: 47122H2B3, 47122F2B6, 47122G2D5 · 4,4’-DDD – Assessment Unit ID: 47122G2D5 · Total Phosphorus – Assessment Unit ID: 47122H2E6 · Total Chlordane – Assessment Unti ID: 47122G2D5 · Polychlorinated Biphenyls (PCBs) – Assessment Unit ID: 47122G2D5, 47122H2B6, 47122F2B3, 47122H2E6 · Mercury – Assessment Unit ID: 47122G2D5 · 2,3,7,8-TCDD (Dioxin) – Assessment Unit ID: 47122G2D5, 47122H2B6, 47122F2B3 The proposed water quality Contech StormFilter catch basin has been designed to treat water prior to discharge into the existing PSE Bypass drainage system through Southport property and ultimately to Lake 17 Washington. This StormFilter catch basin has a General Use Level Designation (GULD), making it acceptable to treat water for this site to meet the required Basic treatment. 18 IX. BOND QUANTITY, FACILITY SUMMARIES, AND DECLARATION OF COVENANT A Bond Quantity Worksheet is included with this report. Planning Division |1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200Date Prepared: Name:PE Registration No:Firm Name:Firm Address:Phone No.Email Address:Project Name: Project Owner:CED Plan # (LUA):Phone:CED Permit # (U):Address: Site Address:Street Intersection:Addt'l Project Owner:Parcel #(s):Phone:Address: Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No:NOWater Service Provided by:If Yes, Provide Forest Practice Permit #:Sewer Service Provided by: Abbreviated Legal Description:LOT A OF CITY OF RENTON LOT LINE ADJUSTMENT NO LUA 98-176-LLA RECORDING NO 9902019014 BEING A PORTION OF GOV LOT 1 IN NW 1/4 OF SECTION 08-23-05 & PORTION LAKE WASH SHORELAND LY NLY & WLY OF BURLINGTON NORTHERN RAILROAD CO R/W TCO 17-1681Site Address1083 Lake Washington Blvd N, Suite 50Street Intersection########425-282-58339/5/2019Prepared by:FOR APPROVALProject Phase 1timb@cplinc.comTim Brockway33708Coughlin Porter Lundeen801 2nd Ave, Suite 900, Seattle, WA 98104206-343-0460SITE IMPROVEMENT BOND QUANTITY WORKSHEETPROJECT INFORMATIONCITY OF RENTONCITY OF RENTON1 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 SubmittalEngineer Stamp Required (all cost estimates must have original wet stamp and signature)Clearing and GradingUtility ProvidersN/AProject Location and DescriptionProject Owner InformationSouthport Park Avenue ExtensionRenton, WA, 98056082305-9178SECO Development##-######Page 2 of 14Ref 8-H Bond Quantity WorksheetSECTION I PROJECT INFORMATIONUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########UnitReference #PriceUnitQuantity CostBackfill & compaction-embankmentESC-16.50$ CY577537,537.50Check dams, 4" minus rockESC-2SWDM 5.4.6.380.00$ Each Catch Basin ProtectionESC-335.50$ Each7248.50Crushed surfacing 1 1/4" minusESC-4WSDOT 9-03.9(3)95.00$ CY DitchingESC-59.00$ CY Excavation-bulkESC-62.00$ CY4.59.00Fence, siltESC-7SWDM 5.4.3.11.50$ LF475712.50Fence, Temporary (NGPE)ESC-81.50$ LF Geotextile FabricESC-92.50$ SY Hay Bale Silt TrapESC-100.50$ Each HydroseedingESC-11SWDM 5.4.2.40.80$ SY Interceptor Swale / DikeESC-121.00$ LF Jute MeshESC-13SWDM 5.4.2.23.50$ SY Level SpreaderESC-141.75$ LF Mulch, by hand, straw, 3" deepESC-15SWDM 5.4.2.12.50$ SY Mulch, by machine, straw, 2" deepESC-16SWDM 5.4.2.12.00$ SY Piping, temporary, CPP, 6"ESC-1712.00$ LF Piping, temporary, CPP, 8"ESC-1814.00$ LF Piping, temporary, CPP, 12"ESC-1918.00$ LF Plastic covering, 6mm thick, sandbaggedESC-20SWDM 5.4.2.34.00$ SY3301,320.00Rip Rap, machine placed; slopesESC-21WSDOT 9-13.1(2)45.00$ CY Rock Construction Entrance, 50'x15'x1'ESC-22SWDM 5.4.4.11,800.00$ Each Rock Construction Entrance, 100'x15'x1'ESC-23SWDM 5.4.4.13,200.00$ Each Sediment pond riser assemblyESC-24SWDM 5.4.5.22,200.00$ Each Sediment trap, 5' high berm ESC-25SWDM 5.4.5.119.00$ LF Sed. trap, 5' high, riprapped spillway berm section ESC-26SWDM 5.4.5.170.00$ LF Seeding, by handESC-27SWDM 5.4.2.41.00$ SY Sodding, 1" deep, level groundESC-28SWDM 5.4.2.58.00$ SY Sodding, 1" deep, sloped groundESC-29SWDM 5.4.2.510.00$ SY TESC SupervisorESC-30110.00$ HR606,600.00Water truck, dust controlESC-31SWDM 5.4.7140.00$ HR UnitReference #PriceUnitQuantity Cost EROSION/SEDIMENT SUBTOTAL:46,427.50SALES TAX @ 10%4,642.75EROSION/SEDIMENT TOTAL:51,070.25(A)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR EROSION & SEDIMENT CONTROLDescription No.(A)WRITE-IN-ITEMS Page 3 of 14Ref 8-H Bond Quantity WorksheetSECTION II.a EROSION_CONTROLUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostGENERAL ITEMS Backfill & Compaction- embankmentGI-16.00$ CYBackfill & Compaction- trenchGI-29.00$ CYClear/Remove Brush, by hand (SY)GI-31.00$ SYBollards - fixedGI-4240.74$ EachBollards - removableGI-5452.34$ EachClearing/Grubbing/Tree RemovalGI-610,000.00$ AcreExcavation - bulkGI-72.00$ CYExcavation - TrenchGI-85.00$ CYFencing, cedar, 6' highGI-920.00$ LFFencing, chain link, 4'GI-1038.31$ LFFencing, chain link, vinyl coated, 6' highGI-1120.00$ LF80016,000.00Fencing, chain link, gate, vinyl coated, 20' GI-121,400.00$ Each11,400.00Fill & compact - common barrowGI-1325.00$ CY4208105,200.00Fill & compact - gravel baseGI-1427.00$ CYFill & compact - screened topsoilGI-1539.00$ CYGabion, 12" deep, stone filled mesh GI-1665.00$ SYGabion, 18" deep, stone filled mesh GI-1790.00$ SYGabion, 36" deep, stone filled meshGI-18150.00$ SYGrading, fine, by handGI-192.50$ SYGrading, fine, with graderGI-202.00$ SY23004,600.00Monuments, 3' LongGI-21250.00$ EachSensitive Areas SignGI-227.00$ EachSodding, 1" deep, sloped groundGI-238.00$ SYSurveying, line & gradeGI-24850.00$ DaySurveying, lot location/linesGI-251,800.00$ AcreTopsoil Type A (imported)GI-2628.50$ CYTraffic control crew ( 2 flaggers )GI-27120.00$ HRTrail, 4" chipped woodGI-288.00$ SYTrail, 4" crushed cinderGI-299.00$ SYTrail, 4" top courseGI-3012.00$ SYConduit, 2"GI-315.00$ LFWall, retaining, concreteGI-3255.00$ SFWall, rockeryGI-3315.00$ SFSUBTOTAL THIS PAGE:127,200.00(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)Page 4 of 14Ref 8-H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)ROAD IMPROVEMENT/PAVEMENT/SURFACINGAC Grinding, 4' wide machine < 1000syRI-130.00$ SYAC Grinding, 4' wide machine 1000-2000syRI-216.00$ SYAC Grinding, 4' wide machine > 2000syRI-310.00$ SYAC Removal/DisposalRI-435.00$ SY82929,015.00Barricade, Type III ( Permanent )RI-556.00$ LFGuard RailRI-630.00$ LFCurb & Gutter, rolledRI-717.00$ LFCurb & Gutter, verticalRI-812.50$ LF150018,750.00Curb and Gutter, demolition and disposalRI-918.00$ LFCurb, extruded asphaltRI-105.50$ LFCurb, extruded concreteRI-117.00$ LFSawcut, asphalt, 3" depthRI-121.85$ LF130240.50Sawcut, concrete, per 1" depthRI-133.00$ LFSealant, asphaltRI-142.00$ LFShoulder, gravel, 4" thickRI-1515.00$ SYSidewalk, 4" thickRI-1638.00$ SY45017,100.00Sidewalk, 4" thick, demolition and disposalRI-1732.00$ SYSidewalk, 5" thickRI-1841.00$ SYSidewalk, 5" thick, demolition and disposalRI-1940.00$ SYSign, Handicap RI-2085.00$ EachStriping, per stallRI-217.00$ EachStriping, thermoplastic, ( for crosswalk )RI-223.00$ SF175525.00Striping, 4" reflectorized lineRI-230.50$ LF1500750.00Additional 2.5" Crushed SurfacingRI-243.60$ SYHMA 1/2" Overlay 1.5" RI-2514.00$ SYHMA 1/2" Overlay 2"RI-2618.00$ SY230041,400.00HMA Road, 2", 4" rock, First 2500 SYRI-2728.00$ SYHMA Road, 2", 4" rock, Qty. over 2500SYRI-2821.00$ SYHMA Road, 4", 6" rock, First 2500 SYRI-2945.00$ SY2300103,500.00HMA Road, 4", 6" rock, Qty. over 2500 SYRI-3037.00$ SYHMA Road, 4", 4.5" ATBRI-3138.00$ SYGravel Road, 4" rock, First 2500 SYRI-3215.00$ SYGravel Road, 4" rock, Qty. over 2500 SYRI-3310.00$ SYThickened EdgeRI-348.60$ LFSUBTOTAL THIS PAGE:211,280.50(B)(C)(D)(E)Page 5 of 14Ref 8-H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)PARKING LOT SURFACINGNo.2" AC, 2" top course rock & 4" borrowPL-121.00$ SY2" AC, 1.5" top course & 2.5" base coursePL-228.00$ SY4" select borrowPL-35.00$ SY1.5" top course rock & 2.5" base coursePL-414.00$ SYSUBTOTAL PARKING LOT SURFACING:(B)(C)(D)(E)LANDSCAPING & VEGETATIONNo.Street TreesLA-1Median LandscapingLA-2Right-of-Way LandscapingLA-3Wetland LandscapingLA-4SUBTOTAL LANDSCAPING & VEGETATION:(B)(C)(D)(E)TRAFFIC & LIGHTINGNo.SignsTR-11,500.00$ LS11,500.00Street Light System ( # of Poles)TR-295,000.00$ LS195,000.00Traffic SignalTR-3Traffic Signal ModificationTR-4SUBTOTAL TRAFFIC & LIGHTING:96,500.00(B)(C)(D)(E)WRITE-IN-ITEMSSUBTOTAL WRITE-IN ITEMS:STREET AND SITE IMPROVEMENTS SUBTOTAL:434,980.50SALES TAX @ 10%43,498.05STREET AND SITE IMPROVEMENTS TOTAL:478,478.55(B)(C)(D)(E)Page 6 of 14Ref 8-H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostDRAINAGE (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/DD-126.00$ SY* (CBs include frame and lid)BeehiveD-290.00$ EachThrough-curb Inlet FrameworkD-3400.00$ EachCB Type ID-41,500.00$ Each710,500.00CB Type ILD-51,750.00$ Each11,750.00CB Type II, 48" diameterD-62,300.00$ Each for additional depth over 4' D-7480.00$ FTCB Type II, 54" diameterD-82,500.00$ Each for additional depth over 4'D-9495.00$ FTCB Type II, 60" diameterD-102,800.00$ Each for additional depth over 4'D-11600.00$ FTCB Type II, 72" diameterD-126,000.00$ Each for additional depth over 4'D-13850.00$ FTCB Type II, 96" diameterD-1414,000.00$ Each for additional depth over 4'D-15925.00$ FTTrash Rack, 12"D-16350.00$ EachTrash Rack, 15"D-17410.00$ EachTrash Rack, 18"D-18480.00$ EachTrash Rack, 21"D-19550.00$ EachCleanout, PVC, 4"D-20150.00$ EachCleanout, PVC, 6"D-21170.00$ EachCleanout, PVC, 8"D-22200.00$ EachCulvert, PVC, 4" D-2310.00$ LFCulvert, PVC, 6" D-2413.00$ LFCulvert, PVC, 8" D-2515.00$ LFCulvert, PVC, 12" D-2623.00$ LFCulvert, PVC, 15" D-2735.00$ LFCulvert, PVC, 18" D-2841.00$ LFCulvert, PVC, 24"D-2956.00$ LFCulvert, PVC, 30" D-3078.00$ LFCulvert, PVC, 36" D-31130.00$ LFCulvert, CMP, 8"D-3219.00$ LFCulvert, CMP, 12"D-3329.00$ LFSUBTOTAL THIS PAGE:12,250.00(B)(C)(D)(E)Quantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESPage 7 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESDRAINAGE (Continued)Culvert, CMP, 15"D-3435.00$ LFCulvert, CMP, 18"D-3541.00$ LFCulvert, CMP, 24"D-3656.00$ LFCulvert, CMP, 30"D-3778.00$ LFCulvert, CMP, 36"D-38130.00$ LFCulvert, CMP, 48"D-39190.00$ LFCulvert, CMP, 60"D-40270.00$ LFCulvert, CMP, 72"D-41350.00$ LFCulvert, Concrete, 8"D-4242.00$ LFCulvert, Concrete, 12"D-4348.00$ LFCulvert, Concrete, 15"D-4478.00$ LFCulvert, Concrete, 18"D-4548.00$ LFCulvert, Concrete, 24"D-4678.00$ LFCulvert, Concrete, 30"D-47125.00$ LFCulvert, Concrete, 36"D-48150.00$ LFCulvert, Concrete, 42"D-49175.00$ LFCulvert, Concrete, 48"D-50205.00$ LFCulvert, CPE Triple Wall, 6" D-5114.00$ LFCulvert, CPE Triple Wall, 8" D-5216.00$ LFCulvert, CPE Triple Wall, 12" D-5324.00$ LFCulvert, CPE Triple Wall, 15" D-5435.00$ LFCulvert, CPE Triple Wall, 18" D-5541.00$ LFCulvert, CPE Triple Wall, 24" D-5656.00$ LFCulvert, CPE Triple Wall, 30" D-5778.00$ LFCulvert, CPE Triple Wall, 36" D-58130.00$ LFCulvert, LCPE, 6"D-5960.00$ LFCulvert, LCPE, 8"D-6072.00$ LFCulvert, LCPE, 12"D-6184.00$ LFCulvert, LCPE, 15"D-6296.00$ LFCulvert, LCPE, 18"D-63108.00$ LFCulvert, LCPE, 24"D-64120.00$ LFCulvert, LCPE, 30"D-65132.00$ LFCulvert, LCPE, 36"D-66144.00$ LFCulvert, LCPE, 48"D-67156.00$ LFCulvert, LCPE, 54"D-68168.00$ LFSUBTOTAL THIS PAGE:(B)(C)(D)(E)Page 8 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESDRAINAGE (Continued)Culvert, LCPE, 60"D-69180.00$ LFCulvert, LCPE, 72"D-70192.00$ LFCulvert, HDPE, 6"D-7142.00$ LFCulvert, HDPE, 8"D-7242.00$ LFCulvert, HDPE, 12"D-7374.00$ LFCulvert, HDPE, 15"D-74106.00$ LFCulvert, HDPE, 18"D-75138.00$ LFCulvert, HDPE, 24"D-76221.00$ LFCulvert, HDPE, 30"D-77276.00$ LFCulvert, HDPE, 36"D-78331.00$ LFCulvert, HDPE, 48"D-79386.00$ LFCulvert, HDPE, 54"D-80441.00$ LFCulvert, HDPE, 60"D-81496.00$ LFCulvert, HDPE, 72"D-82551.00$ LFPipe, Polypropylene, 6"D-8384.00$ LFPipe, Polypropylene, 8"D-8489.00$ LFPipe, Polypropylene, 12"D-8595.00$ LFPipe, Polypropylene, 15"D-86100.00$ LFPipe, Polypropylene, 18"D-87106.00$ LFPipe, Polypropylene, 24"D-88111.00$ LFPipe, Polypropylene, 30"D-89119.00$ LFPipe, Polypropylene, 36"D-90154.00$ LFPipe, Polypropylene, 48"D-91226.00$ LFPipe, Polypropylene, 54"D-92332.00$ LFPipe, Polypropylene, 60"D-93439.00$ LFPipe, Polypropylene, 72"D-94545.00$ LFCulvert, DI, 6"D-9561.00$ LFCulvert, DI, 8"D-9684.00$ LF25821,672.00Culvert, DI, 12"D-97106.00$ LF34836,888.00Culvert, DI, 15"D-98129.00$ LFCulvert, DI, 18"D-99152.00$ LF152,280.00Culvert, DI, 24"D-100175.00$ LFCulvert, DI, 30"D-101198.00$ LFCulvert, DI, 36"D-102220.00$ LFCulvert, DI, 48"D-103243.00$ LFCulvert, DI, 54"D-104266.00$ LFCulvert, DI, 60"D-105289.00$ LFCulvert, DI, 72"D-106311.00$ LFSUBTOTAL THIS PAGE:60,840.00(B)(C)(D)(E)Page 9 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESSpecialty Drainage ItemsDitching SD-19.50$ CYFlow Dispersal Trench (1,436 base+)SD-328.00$ LF French Drain (3' depth)SD-426.00$ LFGeotextile, laid in trench, polypropyleneSD-53.00$ SYMid-tank Access Riser, 48" dia, 6' deepSD-62,000.00$ EachPond Overflow SpillwaySD-716.00$ SYRestrictor/Oil Separator, 12"SD-81,150.00$ EachRestrictor/Oil Separator, 15"SD-91,350.00$ EachRestrictor/Oil Separator, 18"SD-101,700.00$ EachRiprap, placedSD-1142.00$ CYTank End Reducer (36" diameter)SD-121,200.00$ EachInfiltration pond testingSD-13125.00$ HRPermeable PavementSD-14Permeable Concrete SidewalkSD-15Culvert, Box __ ft x __ ftSD-16SUBTOTAL SPECIALTY DRAINAGE ITEMS:(B)(C)(D)(E)STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch)Detention PondSF-1Each Detention TankSF-2Each Detention VaultSF-3Each Infiltration PondSF-4Each Infiltration TankSF-5Each Infiltration VaultSF-6Each Infiltration TrenchesSF-7Each Basic Biofiltration SwaleSF-8Each Wet Biofiltration SwaleSF-9Each WetpondSF-10Each WetvaultSF-11Each Sand FilterSF-12Each Sand Filter VaultSF-13Each Linear Sand FilterSF-14Each Proprietary FacilitySF-1519,800.00$ Each 119,800.00Bioretention FacilitySF-16Each SUBTOTAL STORMWATER FACILITIES:19,800.00(B)(C)(D)(E)Page 10 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESWRITE-IN-ITEMS (INCLUDE ON-SITE BMPs)WI-1WI-2WI-3WI-4WI-5WI-6WI-7WI-8WI-9WI-10WI-11WI-12WI-13WI-14WI-15SUBTOTAL WRITE-IN ITEMS:DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:92,890.00SALES TAX @ 10%9,289.00DRAINAGE AND STORMWATER FACILITIES TOTAL:102,179.00(B) (C) (D) (E)Page 11 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostConnection to Existing WatermainW-12,000.00$ EachDuctile Iron Watermain, CL 52, 4 Inch DiameterW-250.00$ LFDuctile Iron Watermain, CL 52, 6 Inch DiameterW-356.00$ LFDuctile Iron Watermain, CL 52, 8 Inch DiameterW-460.00$ LFDuctile Iron Watermain, CL 52, 10 Inch DiameterW-570.00$ LFDuctile Iron Watermain, CL 52, 12 Inch DiameterW-680.00$ LFGate Valve, 4 inch DiameterW-7500.00$ EachGate Valve, 6 inch DiameterW-8700.00$ EachGate Valve, 8 Inch DiameterW-9800.00$ EachGate Valve, 10 Inch DiameterW-101,000.00$ EachGate Valve, 12 Inch DiameterW-111,200.00$ EachFire Hydrant AssemblyW-124,000.00$ EachPermanent Blow-Off AssemblyW-131,800.00$ EachAir-Vac Assembly, 2-Inch DiameterW-142,000.00$ EachAir-Vac Assembly, 1-Inch DiameterW-151,500.00$ EachCompound Meter Assembly 3-inch DiameterW-168,000.00$ EachCompound Meter Assembly 4-inch DiameterW-179,000.00$ EachCompound Meter Assembly 6-inch DiameterW-1810,000.00$ EachPressure Reducing Valve Station 8-inch to 10-inchW-1920,000.00$ EachWATER SUBTOTAL:SALES TAX @ 10%WATER TOTAL:(B) (C) (D) (E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR WATERQuantity Remaining (Bond Reduction) (B)(C)Page 12 of 14Ref 8-H Bond Quantity WorksheetSECTION II.d WATERUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 CED Permit #:########ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostClean OutsSS-11,000.00$ EachGrease Interceptor, 500 gallonSS-28,000.00$ EachGrease Interceptor, 1000 gallonSS-310,000.00$ EachGrease Interceptor, 1500 gallonSS-415,000.00$ EachSide Sewer Pipe, PVC. 4 Inch DiameterSS-580.00$ LFSide Sewer Pipe, PVC. 6 Inch DiameterSS-695.00$ LFSewer Pipe, PVC, 8 inch DiameterSS-7105.00$ LFSewer Pipe, PVC, 12 Inch DiameterSS-8120.00$ LFSewer Pipe, DI, 8 inch DiameterSS-9115.00$ LFSewer Pipe, DI, 12 Inch DiameterSS-10130.00$ LFManhole, 48 Inch DiameterSS-116,000.00$ EachManhole, 54 Inch DiameterSS-136,500.00$ EachManhole, 60 Inch DiameterSS-157,500.00$ EachManhole, 72 Inch DiameterSS-178,500.00$ EachManhole, 96 Inch DiameterSS-1914,000.00$ EachPipe, C-900, 12 Inch DiameterSS-21180.00$ LFOutside DropSS-241,500.00$ LSInside DropSS-251,000.00$ LSSewer Pipe, PVC, ____ Inch DiameterSS-26Lift Station (Entire System)SS-27LSSANITARY SEWER SUBTOTAL:SALES TAX @ 10%SANITARY SEWER TOTAL:(B) (C) (D) (E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR SANITARY SEWERQuantity Remaining (Bond Reduction) (B)(C)Page 13 of 14Ref 8-H Bond Quantity WorksheetSECTION II.e SANITARY SEWERUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 Planning Division |1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200Date:Name:Project Name: PE Registration No:CED Plan # (LUA):Firm Name:CED Permit # (U):Firm Address:Site Address:Phone No.Parcel #(s):Email Address:Project Phase: Site Restoration/Erosion Sediment Control Subtotal (a)Existing Right-of-Way Improvements Subtotal (b)(b)-$ Future Public Improvements Subtotal(c)-$ Stormwater & Drainage Facilities (Public & Private) Subtotal(d)(d)102,179.00$ (e)(f)Site RestorationCivil Construction PermitMaintenance Bond20,435.80$ Bond Reduction2Construction Permit Bond Amount 3Minimum Bond Amount is $10,000.001 Estimate Only - May involve multiple and variable components, which will be established on an individual basis by Development Engineering.2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% willcover all remaining items to be constructed. 3 Required Bond Amounts are subject to review and modification by Development Engineering.* Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton.** Note: All prices include labor, equipment, materials, overhead and profit. EST1((b) + (c) + (d)) x 20%-$ MAINTENANCE BOND */**(after final acceptance of construction)51,070.25$ -$ 102,179.00$ 51,070.25$ -$ 102,179.00$ -$ 153,249.25$ P (a) x 100%SITE IMPROVEMENT BOND QUANTITY WORKSHEET BOND CALCULATIONS9/5/2019Tim Brockway33708Coughlin Porter LundeenR((b x 150%) + (d x 100%))S(e) x 150% + (f) x 100%Bond Reduction: Existing Right-of-Way Improvements (Quantity Remaining)2Bond Reduction: Stormwater & Drainage Facilities (Quantity Remaining)2T(P +R - S)Prepared by:Project InformationCONSTRUCTION BOND AMOUNT */**(prior to permit issuance)206-343-0460timb@cplinc.comSouthport Park Avenue Extension##-######Site Address082305-9178FOR APPROVAL########801 2nd Ave, Suite 900, Seattle, WA 98104Page 14 of 14Ref 8-H Bond Quantity WorksheetSECTION III. BOND WORKSHEETUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 9/5/2019 19 X. OPERATION AND MAINTENANCE MANUAL STANDARD MAINTENANCE All facilities are to be maintained by SECO Development after a 2-year maintenance warranty. Sections of the 2017 Renton Surface Water Design Manual (RSWDM) under this section outline the Maintenance Requirements for stormwater facilities and on-site BMPs have been included in this section on the following pages for use by the City in the maintenance of the designed facilities. 20 MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES AT SOUTHPORT NO. 5 - CATCH BASINS Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is performed General Trash & Debris (Includes Sediment) Trash or debris of more than 1/2 cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the basin by more than 10% No Trash or debris located immediately in front of catch basin opening. Trash or debris (in the 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. Trash or debris in any inlet or outlet pipe blocking more than 1/3 of its height. Inlet and outlet pipes free of trash or debris. 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 the 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. Structure Damage to Frame and/or Top Slab Corner of frame extends more than 3/4 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 1/4 inch (intent is to make sure all material is running into basin). Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than 3/4 inch of the frame from the top slab. Frame is sitting flush on top slab. 21 Maintenance Components Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed. Cracks in Basin Walls/ Bottom Cracks wider than 1/2 inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that structure is unsound. Basin replaced or repaired to design standards. Cracks wider than 1/2 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. Sediment/ Misalignment Basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Fire Hazard Presence of chemicals such as natural gas, oil and gasoline. No flammable chemicals present. Vegetation Vegetation growing across and blocking more than 10% of the basin opening. No vegetation blocking opening to basin. Vegetation growing in inlet/outlet pipe joints that is more than six inches tall and less than six inches apart. No vegetation or root growth present. Pollution Nonflammable chemicals of more than 1/2 cubic foot per three feet of basin length. No pollution present other than surface film. Catch Basin Cover Cover Not in Place Cover is missing or only partially in place. Any open catch basin requires maintenance. Catch basin cover is closed Locking Mechanism Not Working Mechanism cannot be opened by on maintenance person with proper tools. Bolts into frame have less than 1/2 inch of thread. Mechanism opens with proper tools. Cover Difficult to Remove One maintenance person cannot remove lid after applying 80 lbs. of lift; intent is keep cover from sealing off access to maintenance. Cover can be removed by one maintenance person. Ladder Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. Metal Grates (If Applicable) Grate with opening wider than 7/8 inch. Grate opening meets design standards. 22 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 missing or broken member(s) of the grate. Grate is in place and meets design standards. 23 NO. 9 - FENCING Maintenance Components Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed General Missing or Broken Parts Any defect in the fence that permits easy entry to a facility. Parts in place to provide adequate security. Erosion Erosion more than 4 inches high and 12-18 inches wide permitting an opening under a fence. No opening under the fence that exceeds 4 inches in height. Wire Fences Damaged Parts Post out of plumb more than 6 inches. Post plumb to within 1- 1/2 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) 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. Extension arm missing, broken, or bent out of shape more than 1 1/2 inches. Extension arm in place with no bends larger than 3/4 inch. 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. 24 NO. 6 - CONVEYANCE SYSTEMS (PIPES & DITCHES) Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Pipes Sediment & Debris Accumulated sediment that exceeds 20% of the diameter of the pipe. Pipe cleaned of all sediment and debris. Vegetation Vegetation that reduces free movement of water through pipes. All vegetation removed so water flows freely through pipes. Damaged Protective coating is damaged; rust is causing more than 50% deterioration to any part of pipe. Pipe repaired or replaced. Any dent that decreases the cross section area of pipe by more than 20%. Pipe repaired or replaced. Open Ditches Trash & Debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment Accumulated sediment that exceeds 20 % of the design depth. Ditch cleaned/ flushed of all sediment and debris so that it matches design. Vegetation Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion Damage to Slopes See “Rain gardens” Standard No. 1 See “Rain gardens” Standard No. 1 Rock Lining Out of Place or Missing (If Applicable). Maintenance person can see native soil beneath the rock lining. Replace rocks to design standards. Catch Basins See “Catch Basins: Standard No. 4 See “Catch Basins” Standard No. 4 Debris Barriers (e.g., Trash Rack) See “Debris Barriers” Standard No.5 See “Debris Barriers” Standard No. 5 25 NO. 11 - GROUNDS (LANDSCAPING) Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed General Weeds (Nonpoisonous) Weeds growing in more than 20% of the landscaped area (trees and shrubs only). Weeds present in less than 5% of the landscaped area. Safety Hazard Any presence of poison ivy or other poisonous vegetation. No poisonous vegetation present in landscaped area. Trash or Litter Paper, cans, bottles, totaling more than 1 cubic foot within a landscaped area (trees and shrubs only) of 1,000 square feet. Area clear of litter. Trees and Shrubs Damaged 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. Tree or shrub in place 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; remove any dead or diseased trees. 26 NO. 12 - ACCESS ROADS/ EASEMENTS Maintenance Component Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed General Trash and Debris Trash and debris exceeds 1 cubic foot per 1,000 square feet i.e., trash and debris would fill up one standards size garbage can. Roadway free of debris which could damage tires. Blocked Roadway Debris which could damage vehicle tires (glass or metal). Roadway free of debris which could damage tires. Any obstruction which reduces clearance above road surface to less than 14 feet. Roadway overhead clear to 14 feet high. Any obstruction restricting the access to a 10 to 12 foot width for a distance of more than 12 feet or any point restricting access to less than a 10 foot width. Obstruction removed to allow at least a 12 foot access. Road Surface Settlement, Potholes, Mush Spots, Ruts When any surface defect exceeds 6 inches in depth and 6 square feet in area. In general, any surface defect which hinders or prevents maintenance access. Road surface uniformly smooth with no evidence of settlement, potholes, mush spots, or ruts. Vegetation in Road Surface Weeds growing in the road surface that are more than 6 inches tall and less than 6 inches tall and less than 6 inches apart within a 400-square foot area. Road surface free of weeds taller than 2 inches. 27 NO. 12- WATER QUALITY FACILITIES A.) Cartridge Filter Catch Basin 28 Maintenance Component Defect or Problem Condition When Maintenance is Needed Recommended Maintenance to Correct Problem Facility – General Requirements Life cycle Once per year, except mulch and trash removal twice per year. Facility is re-inspected and any needed maintenance performed 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 Excessive sediment or trash accumulation Accumulated sediments or trash impair free flow of water into system inlet should be free of obstructions allowing free distributed flow of water into system Mulch Cover Trash and floatable debris accumulation Excessive trash and/or debris accumulation Minimal trash or other debris on mulch cover. Mulch cover raked level. Proprietary Filter Media/ Vegetation Substrate “Ponding” of water on mulch cover after mulch cover has been maintained Excessive fine sediment passes the mulch cover and clogs the filter media/vegetative substrate Stormwater should drain freely and evenly through mulch cover. Replace substrate and vegetation when needed Plants not growing or in poor condition Soil/mulch too wet, evidence of spill, incorrect plant selection, pest infestation, and/or vandalism to plants Plants should be healthy and pest free Damaged Pipes Any part of the pipes that are crushed, damaged due to corrosion and/ or settlement. Pipe repaired and/ or replaced. Access Cover Damaged/ Not Working Cover cannot be opened, one person cannot open the cover, corrosion/ deformation of cover. Cover repaired to proper working specifications or replaced. Vault Structure Includes Cracks in Wall, Bottom, Damage to Frame and/ or Top Slab Cracks wider than 1/2-inch and any evidence of soil particles entering the structure through the cracks, or maintenance/ inspection personnel determines that the vault is not structurally sound. Vault replaced or repaired to design specifications. Structure Structure has visible cracks Cracks wider than ½ inch Evidence of soil particles entering the structure through the cracks Structure is sealed and structurally sound Appendix A – Figures Figures Figure 1 Technical Information Report Worksheet Figure 2 Site Location Map Figure 3 USGS Soil Map Figure 4 Sensitive Areas Map Figure 5 Existing Southport Conditions Figure 6A Proposed Catchment Area Figure 6B Proposed Subbasin Area Figure 6C Drainage Basin Map Figure 7A Proposed Southport Conditions Figure 7B proposed Additional Impervious Area Map Figure 8 StormFilter Sizing Figure 9 Flow Control Application Map Figure 10 FEMA Map Figure 11 Aquifer Protection Map Figure 12 Offsite Analysis CITY OF RENTON SURFACE WATER DESIGN MANUAL 2017 City of Renton Surface Water Design Manual 12/12/2016 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 SECO Development (425) 282-5833 1083 Lake Washington Blvd, Suite 50 Renton, WA 98056 Tim Brockway, P.E. Coughlin Porter Lundeen (206) 343-0460 Southport Park Avenue Extension 23N 5E 8 North of existing Park Avenue (extension of City Park Avenue extension) 5/20/2019 5/20/2019 8/1/2019 8/1/2019 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 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 Lake Washington South Drainage Basin Flow control not required. No increase in impervious area. Basic WQ required. REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2017 City of Renton Surface Water Design Manual 12/12/2016 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 8 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: ____________ On-site BMPs: _______________________________ Conveyance System Spill containment located at: _____________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: _____________________ Contact Phone: _________________________ After Hours Phone: _________________________ Figure 1 - TIR Worksheet loose sandy silt Southport Park Avenue Extension Site 1 (existing PSE pipe) N/A TBD TBD TBD 1.2.3.1A REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-4 Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality (include facility summary sheet) Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. _______________________ 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 Contech StormFilter WQ catch basin utilized prior to tie in with existing PSE storm system Temporary road infrastructure, drainage modifications Contech StormFilter Catch Basin, COR catch basins Catch basins and Contech StormFilter Catch Basin designed to pass 100-yr storm peak safely REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2017 City of Renton Surface Water Design Manual 12/12/2016 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 Type/Description Water Quality Type/Description Detention Infiltration Regional Facility Shared Facility On-site BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ Vegetated Flowpath Wetpool Filtration Oil Control Spill Control On-site BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ ________________ 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 _______________________________ Figure 1 - TIR Worksheet Contech StormFilter Outflow to Lake Washington REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-6 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 Figure 2 - Site Location Project Site Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/15/2019 Page 1 of 352609305260990526105052611105261170526123052612905260930526099052610505261110526117052612305261290559660559720559780559840559900559960560020560080560140560200 559660 559720 559780 559840 559900 559960 560020 560080 560140 560200 47° 30' 8'' N 122° 12' 28'' W47° 30' 8'' N122° 12' 1'' W47° 29' 56'' N 122° 12' 28'' W47° 29' 56'' N 122° 12' 1'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 100 200 400 600 Feet 0 35 70 140 210 Meters Map Scale: 1:2,630 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. Figure 3 - USDA Soil Survey Map 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 Service Web 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 14, Sep 10, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 31, 2013—Oct 6, 2013 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. Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/15/2019 Page 2 of 3 Figure 3 - USDA Soil Survey Map Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI Ur Urban land 24.9 100.0% Totals for Area of Interest 24.9 100.0% Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/15/2019 Page 3 of 3 Figure 3 - USDA Soil Survey Map 36,112 3,009 City of Renton Sensitive Areas Map This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. 5/16/2019 Legend 2,04601,023 THIS MAP IS NOT TO BE USED FOR NAVIGATION Feet Notes 2,046 WGS_1984_Web_Mercator_Auxiliary_Sphere Information Technology - GIS RentonMapSupport@Rentonwa.gov Erosion Hazard - High Special Flood Hazard Areas (100 year flood) Landslide Very High High Moderate Unclassified Wetlands Seismic Hazard Areas Faults Streets Parks Waterbodies Designated Neighborhoods Map Extent2010 Map Project Site Figure 4 - Sensitive Areas Map Figure 5 - Existing Southport Conditions Notes: 1These sub-basin areas are based on existing PSE site conditions. Scale: 1" = 200' Lake Washington 1.26 ac 1.32 ac 1.36 ac PSE#4 PSE#3 PSE#2 PSE#1 Existing Drainage Tunnel PSE#2a PSE Property Line Project Site PARCEL A8 + 0 0 9 + 0 0 10+ 0 0 11+00 12+00 13+0014+0015+00 15+50 2530 23 2426 27 28 29 3 1 32 25 30 24 26272829 3132 25232426272825302426272829 3132252223242523 24 2223 22 22222 2 23 22 22 0 20 40 80 SCALE 1"=40' Figure 6A - Proposed Catchment Areas C18 August 2019 Southport Park Avenue Extension Portion of proposed roadway stormwater has already been evaluated with previous Southport Office project, Permit #SW18001113 Connection to Existing PSE Drainage System Contech Solutions StormFilter Water Quality 4-Cartridge Catch Basin Proposed PSE Drainage Reconfiguration, area captured by proposed reconfiguration, discharges to original discharge point and ultimately to Lake Washington (9.295 SF) (0.21 AC) Connection to Existing PSE Drainage System (from PSE reconfiguaration, connecting at same invert elevation as previous, IE=18.88) Area captured by existing catch basin to remain, discharges west to Boeing property as it currently does. (9,960 SF) (0.23 AC) Area to be conveyed to existing PSE drainage system (22,540 SF) (0.52 AC) Area currently discharges west to Boeing Property, will continue to do so in proposed condition (21,950 SF) (0.50 AC) PARCEL A8 + 0 0 9 + 0 0 10+ 0 0 11+00 12+00 13+0014+0015+00 15+50 2530 23 2426 27 28 29 3 1 32 25 30 24 26272829 3132 25232426272825302426272829 3132252223242523 24 2223 22 22 2 2 2 2 23 22 22 0 20 40 80 SCALE 1"=40' Figure 6B - Proposed Subbasin Area Map C180194-03 August 2019 Southport Park Avenue Extension BASIN CB#6 11,063 SF (0.25 AC) BASIN CB#5 1,577 SF (0.04 AC) BASIN CB#4 3,089 SF (0.07 AC) BASIN CB#3 3,105 SF (0.07 AC) BASIN CB#2 3,220 SF (0.07 AC) BASIN CB#1 486 SF (0.01 AC) 72,224 6,019 City of Renton Drainage Basin Map This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. 5/15/2019 Legend 4,09302,046 THIS MAP IS NOT TO BE USED FOR NAVIGATION Feet Notes 4,093 WGS_1984_Web_Mercator_Auxiliary_Sphere Information Technology - GIS RentonMapSupport@Rentonwa.gov City and County Boundary Drainage Sub Basins <all other values> Black River Boren Creek Cabbage Creek Cedar Grove Cedar Main Urban China Creek Country Creek Duamish East Fork May Creek Garrison Creek Ginger Creek Greenes Creek Gypsy Honey Creek Jenkins Creek Main Lake Kathleen Lake Washington - East Lake Washington - West Johns Creek Lake Washington South Little Soos Creek Long Marsh Creek Lower May Creek Project Site Figure 6C - Drainage Basin Map Figure 7A - Proposed Southport Conditions~~PSE #1 PSE #2 PSE #3 PSE #4 Existing Drainage Tunnel Lake Washington PSE Property Line Basin Area (0.29 ac) added to PSE#2. New Total PSE#2 impervious area = 1.55 ac See Southport Park Avenue Extension Conveyance Analysis (Appendix B) for calculations. 1.26 ac 1.32 ac 1.36 ac PARCEL A0 20 40 80 SCALE 1"=40' Added basin area to be added to existing PSE drainage system (12,640 SF) (0.29 AC) Legend Existing storm drainage system already accounted for in existing PSE system (9,900 SF) (0.22 AC) Figure 7B - Additional Impervious Area Map C180194-03 August 2019 Southport Park Avenue Extension Upstream segment of public portion of Park Avenue extension, draining on to project site Portion of proposed roadway stormwater has already been evaluated with previous Southport Office project, Permit #SW18001113 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.97 Pervious Total 0.97 Impervious Land Use acre ROADS FLAT 0.59 Impervious Total 0.59 Basin Total 1.56 Element Flows To: Surface Interflow Groundwater Figure 8 - StormFilter Sizing Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.1058 acre-feet On-line facility target flow:0.0984 cfs. Adjusted for 15 min:0.0984 cfs. Off-line facility target flow:0.0543 cfs. Adjusted for 15 min:0.0543 cfs. LakeDesire ShadyLake (MudLake) PantherLake LakeYoungs LakeWashington Bl a c kRi ver Gr eenRiv e r C edarRi verUV900 UV167 UV515 UV169 UV900 UV169 UV167BN IncBN IncBBNNIInnccSSEERReennttoonn II ssss aa qquuaahh RR dd RReennttoonnMMaappllee VVaalllleeyyRRdd MMaapplleeVVaalllleeyyHHwwyy 110088tthhAAvveeSSEESSWW SSuunnsseettBBllvvdd RRaaiinnii eerrAAvveeNNNE 3rd StNE 3rd St SW 43rd StSW 43rd St SS EE CCaarrrrRR dd NE 4th StNE 4th St SSEE RReennttoonn MMaappllee VVaalllleeyy RRddLLooggaannAAvveeNN SR 515SR 515PPaarrkkAAvveeNNOOaakkeessddaalleeAAvveeSSWWSSuunnsseettBBllvvddNN EE DDuuvvaallllAAvveeNNEEI-405 FWYI-405 FWY II--440055FFWWYYSR 167SR 167114400tthh WWaayySS EENNEE 2277tthh SStt 115566tthhAAvveeSSEEUUnniioonnAAvveeNNEE111166tthhAAvveeSSEESW 7th StSW 7th St N 8th StN 8th St PP uuggeettDDrrSSEE RR ee nnttoonnAAvvee SS SSWW 2277tthh SStt BBeennssoonnRRddSSWWiilllliiaammssAAvveeSSMMoonnrrooeeAAvveeNNEESE 128th StSE 128th St II nntt eerr uurr bbaannAAvveeSS HHooqquuiiaammAAvveeNNEE8844tthhAAvveeSSSSEEPPeett rr oovvii tt sskkyyRRddEEVVaalllleeyyHHwwyySE 192nd StSE 192nd St SE 60th StSE 60th St TTaallbboottRRddSSRRee nn tt oo nn AAvveeSS116644tthhAAvveeSSEESE 208th StSE 208th St SE 72nd StSE 72nd St RRaaiinniieerr AAvvee SS 111166tthhAAvveeSSEES 128th StS 128th St NNeewwccaassttllee WWaayy SS 221122tthh SStt SS 118800tthh SStt CCooaall CCrreeeekkPPkkwwyySSEESW 41st StSW 41st St 114400tthhAAvveeSSEE112288tthhAAvveeSSEE6688tthhAAvveeSSSSEE 116688tthh SStt NE 12th StNE 12th St BBee aa ccoonn AA vv ee SS FFoorreesstt DDrr SSEE SSEE 116644tthh SStt 114488tthhAAvveeSSEESSEE MMaayy VVaalllleeyy RRdd SS EE JJ oo nn ee ss RR dd SSEE 22 00 44 tthh WW aayySW 34th StSW 34th St SE 144th StSE 144th St 114488tthhAAvveeSSEE115544tthhPPllSSEELL aa kk ee WWaa sshhii nnggtt oonnBBll vvddNNEEddmmoonnddssAAvveeNNEEAAbbeerrddeeeennAAvveeNNEEEEMM eerrcceerrWWaayyWWeessttVVaalllleeyyHHwwyyEast Valley RdEast Valley Rd,§-405 ,§-405 ,§-405 µ0 1 2Miles Flow Control Application Map Reference 15-A Date: 01/09/2014 Flow Control Standards Peak Rate Flow Control Standard (Existing Site Conditions) Flow Control Duration Standard (Existing Site Conditions) Flow Control Duration Standard (Forested Conditions) Flood Problem Flow Unincorporated King County Flow Control Standards Renton City Limits Potential Annexation Area Figure 9 - Flow Control Application Map Project Site Figure 10 - FEMA Flood Insurance Rate Map (FIRM) Southport Park Avenue Extension Site (Approximate) k k k k k k k k k k k k k k k k k k k k k k k k k k k kk k k k k k k k k k k k k k k k k k k k HoquiamAveNEE Valley Hwy84thAveSNEParkD r SW 7th St SE 128th St SE 192nd StLind Ave SWMainAveSS 132nd St Factory PlN Talbot Rd SN 3rd St RainierAveS 164thAveSETukwila Pk w y SPuget Dr NE 4th St S 3rd St S 1 2 9 thS t68thAveSSWSunsetBlvd SW 16th St 116thAveSEN 4th St I n t e r u r b a n Av e S WilliamsAveNBronsonW a y N NE7thSt 124thAveSES 7th St SERenton IssaquahRd Rai ni er AveNNewcastle Way CoalCr e e k PkwySESW 41st St T a y l o r P l NW NESunsetBlvdWellsAveNUnionAveNENE 3rd St Ha r die A v eSWS180th St Maple V a l l e y H w y 140thAveSES G radyWayS 2 1 s tSt BensonRdSRe nt o n AveS87thAveS128thAveSE148thAveSESW 43rd St SEC arrR d SE 168th St Beaco n A v e S 68thAveSLoganAveN108thAveSEForestDr SE S2ndSt 141 s tAve S ERainierAveS 156thAveSES E 183rd StBenson D r S S 124th StS 43rd St Airport Way S W G radyW a y S E J o n e s RdSunsetBlvdN Puget Dr SESE 204th Way SW 34th StMo n s ter RdSW SE 142nd Pl WestValleyHwySSEMay ValleyRd SunsetBlvdNS C a r r RdHouserWayNNewcastle GolfClubRd S 133rd St WilliamsAveSWellsAveSEMercerWay154thPlSEDuvallAveNELoganAveSMonroeAveNESunsetBlvdNEEdmondsAveNEStevens AveNWRai ni er AveSTalbotRdSOakesdaleAveSWTaylorAveNW164thAveSERainierAveSWestVal leyHwyWestValleyHwyParkAveN108thAveSE6 6 t h Av e SWMercerWayWMercer W ay Lakemont BlvdSE132ndAve SELakeWashingtonBlvdNE140thWaySE East Valley Rd68thAveS³City of RentonSensitive Areas 0 0.5 10.25 Miles Information Technology - GISmapsupport@rentonwa.govPrinted on: 11/12/2014 Data Sources: City of Renton, King County This document is a graphic representation, not guaranteedto survey accuracy, and is based on the best informationavailable as of the date shown. This map is intended forCity display purposes only. Renton City Limits k Education Fire Station K Valley Medical Center Aquifer Protection Zone 1 Zone 1 Modified Zone 2 Coordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 FeetProjection: Lambert Conformal ConicDatum: North American 1983 HARN Figure 11 - Aquifer Protection Map Project Site 9,028 752 Figure 11 - Offsite Analysis Map This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. None 5/20/2019 Legend 5120256 THIS MAP IS NOT TO BE USED FOR NAVIGATION Feet Notes 512 WGS_1984_Web_Mercator_Auxiliary_Sphere Information Technology - GIS RentonMapSupport@Rentonwa.gov City and County Boundary Parcels Water Gravity Pipes Water Mains Mains - Other System Water Service Areas Lift Stations Pressurized Mains Renton Private Gravity Mains Renton Private Wastewater Service Areas KC Pressurized Mains KC Gravity Mains Pump Stations Discharge Points Stormwater Mains Culverts Open Drains Facility Outlines Private Pump Stations Private Discharge Points Private Pipes Private Culverts EXISTING PSE DRAINAGE SYSTEM ROUTE Project Site CONNECTION TO EXISTING PSE DRAINAGE SYSTEM Figure 12 -Offsite Analysis Map Appendix B – Engineering Calculations SOUTHPORT PARK AVENUE EXTNSION CONVEYANCE ANALYSIS BACKWATER ANALYSIS STORMFILTER SIZING (WWHM) Southport Park Avenue Extension Conveyance Analysis Sub- Total Composite Impervious Area Grass Basin Area1 C Value Area Area (Acres)(Sq. Ft.), C=0.90 (Sq. Ft.), C=0.22 PSE#42 1.36 0.90 59241 0 PSE#32 1.32 0.90 57499 0 0.00 0.00 CB #6 0.25 0.90 11063 0 CB #5 0.04 0.90 1577 0 CB #4 0.07 0.90 3089 0 CB #3 0.07 0.90 3105 0 CB #2 0.07 0.90 3220 0 CB #1 0.01 0.90 486 0 PSE#2 1.04 0.90 45303 0 PSE#1 0.00 0.00 0 0 Tunnel 0.00 0.00 0 0 Totals 4.24 184583 0 Notes: 1These sub-basin areas are based on existing PSE site conditions. 2 Unchanged 3 Sub-Basin area changed to account for additional 0.29 acres of impervious area runoff added to the existing PSE drainage system Catch Basin Sub-basin Areas Original Calculations dated September 30, 2014. Modified May 20, 2019 and revised August 1, 2019 to account for addition of 0.29 acres of impervious area addded to PSE #2 (PSE #2 original impervious area = 1.26 ac) Southport Park Avenue Extension Conveyance Analysis 8/2/2019~~PSE #1 PSE #2 PSE #3 PSE #4 Existing Drainage Tunnel Lake Washington PSE Property Line Basin Area (0.29 ac) added to PSE#2. New Total PSE#2 impervious area = 1.55 ac See Southport Park Avenue Extension Conveyance Analysis (Appendix B) for calculations. 1.26 ac 1.32 ac 1.36 ac See Figure 5 - Existing Southport Conditions and Figure 7A - Proposed Southport Conditions 10-Year ConveyanceSub Area C C*A Sum Tc I Q(R) Pipe Typ. Slope Q(F) V V L Tt d/DBasinC*A (c.f.s.)(pipe (pipe (atFromToNumber(acres)(min.)(in.)(Manning's "n")(ft./ft.)full)full)Q(R))(ft.)(min.)(%)(%)PSE#4PSE#3PSE#41.360.901.221.226.32.122.59150.0140.50%4.253.463.181991.063.00%61.0%PSE#3PSE#2PSE#31.320.901.192.417.31.954.71150.0140.50%4.253.465.181720.669.50%110.9%CB #6CB #5CB #60.250.900.230.236.32.120.48120.0140.50%2.352.991.87380.336.50%20.6%CB #5CB #4CB #50.040.900.030.266.62.060.54120.0140.50%2.352.991.971000.838.00%22.9%CB #4CB #3CB #40.070.900.060.327.51.930.63120.0140.50%2.352.992.07940.841.00%26.7%CB #3CB #2CB #30.070.900.060.398.21.840.71120.0140.50%2.352.992.21830.643.00%30.4%CB #2CB #1CB #20.070.900.070.468.91.770.81120.0140.50%2.352.992.35330.245.00%34.3%CB #1 PSE#2 CB #1 0.01 0.90 0.01 0.47 9.1 1.74 0.81 18 0.014 0.50% 6.92 3.92 2.00 15 0.1 28.00% 11.7%PSE#2PSE#1PSE#20.000.000.002.889.11.745.02180.0140.30%5.363.033.834151.869.50%93.6%PSE#1TunnelPSE#10.000.000.002.8810.91.584.56180.01431.40%54.8031.0114.84140.023.00%8.3%Project:Southport Park Avenue ExtensionR=10 yrCalcs by:AEHJob No: C180194-03Location:Renton, WADate:8/2/2019 LocationNotesFRQQThese flows are used for the 10-yr backwater analysisSouthport Park Avenue ExtensionConveyance Analysis - 10 Year8/2/2019 10-Year BackwaterBackwater Analysis TableMannings Coefficient0.014Storm Event Return Period 10PSE Stormwater Reroute Q L Pipe TYP Outlet Inlet Barrel Barrel Velocity Excel Critical TW Friction HGL Entry Entry Exit Outlet Headwater Inlet Approach Bend Bend Junc Loss Junction Headwater Rim Elev. O.K.? Submerged Submerged Downstream Upstream (cfs) (FT) Diam (in). n Elev Elev Area Velocity Head Check Depth Elev Loss Elev Coef Loss Loss ControlDepth Control Head Coefficient Loss Coefficient Loss ElevationDifferenceCheckPSE#3 PSE#4 2.59 199 15 0.014 19.00 19.99 1.227 2.113 0.069 1.00 0.65 20.76 0.369 21.24 0.50 0.03 0.0721.340.57 20.70 -0.07 0.00 0.00 0.00 0.00 21.27 23.50 2.23 yes unsubmerged 1.890PSE#2 PSE#3 4.71 172 15 0.014 18.14 19.00 1.227 3.840 0.229 1.00 0.88 19.59 1.052 20.65 0.50 0.11 0.2320.990.84 20.05 -0.23 0.00 0.00 0.00 0.00 20.76 23.00 2.24 yes unsubmerged 3.435CB #5 CB #6 0.48 38 12 0.014 20.13 20.32 0.785 0.617 0.006 1.00 0.29 21.08 0.008 21.32 0.50 0.00 0.0121.330.30 20.62 -0.01 -3.70 -0.02 -5.00 -0.03 21.27 23.69 2.42 yesunsubmerged 0.617CB #4 CB #5 0.54 100 12 0.014 19.63 20.13 0.785 0.685 0.007 1.00 0.30 20.74 0.026 21.13 0.50 0.00 0.0121.140.32 20.45 -0.01 -2.70 -0.02 -4.00 -0.03 21.08 23.23 2.15 yesunsubmerged 0.685CB #3 CB #4 0.63 94 12 0.014 19.16 19.63 0.785 0.800 0.010 1.00 0.33 20.75 0.034 20.78 0.50 0.00 0.0120.800.35 19.98 -0.01 -1.70 -0.02 -3.00 -0.03 20.74 22.73 1.99 yesunsubmerged 0.800CB #2 CB #3 0.71 83 12 0.014 18.74 19.16 0.785 0.910 0.013 1.00 0.35 20.74 0.038 20.78 0.50 0.01 0.0120.790.37 19.53 -0.01 -0.70 -0.01 -2.00 -0.03 20.75 22.24 1.49 yesunsubmerged 0.910CB #1 CB #2 0.81 33 12 0.014 18.58 18.74 0.785 1.026 0.016 1.00 0.38 19.60 0.019 19.74 0.50 0.01 0.0219.760.40 19.14 -0.02 0.30 0.00 -1.00 -0.02 19.74 21.79 2.05 yes unsubmerged 1.026PSE#2 CB #1 0.81 15 18 0.014 18.00 18.08 1.767 0.459 0.003 1.00 0.34 19.59 0.001 19.60 0.50 0.00 0.0019.600.23 18.43 0.00 1.30 0.00 0.00 0.00 19.60 22.00 2.40 yes unsubmerged 0.375PSE#1 PSE#2 5.02 415 18 0.014 16.90 18.14 1.767 2.839 0.125 1.00 0.86 18.48 1.088 19.64 0.50 0.03 0.0519.720.64 19.11 -0.13 0.00 0.00 0.00 0.00 19.59 22.25 2.66 yes unsubmerged 2.318Tunnel PSE#1 4.56 14 18 0.014 12.50 16.90 1.767 2.579 0.103 1.00 0.82 18.40 0.030 18.43 0.50 0.05 0.1018.590.76 18.04 -0.10 0.00 0.00 0.00 0.00 18.48 21.78 3.30 yes unsubmerged 2.106Southport Park Avenue ExtensionLocationThe elevation of the rim.The difference between the water elevation and the rim should be greater than 1.0 feet for the 10-year storm event.Southport HotelBackwater Analysis - 10-Year8/2/2019 25-Year ConveyanceSub Area C C*A Sum Tc I Q(R) Pipe Typ. Slope Q(F) V V L Tt d/DBasinC*A (c.f.s.)(pipe (pipe (atFromToNumber(acres)(min.)(in.)(Manning's "n")(ft./ft.)full)full)Q(R))(ft.)(min.)(%)(%)PSE#4PSE#3PSE#41.360.901.221.226.32.553.13150.0140.50%4.253.463.441991.069.50%73.6%PSE#3PSE#2PSE#31.320.901.192.417.32.375.71150.0140.50%4.253.466.271720.569.50%134.3%CB #6CB #5CB #60.250.900.230.236.32.550.58120.0140.50%2.352.992.02380.339.50%24.9%CB #5CB #4CB #50.040.900.030.266.62.490.65120.0140.50%2.352.992.111000.841.50%27.7%CB #4CB #3CB #40.070.900.060.327.42.340.76120.0140.50%2.352.992.29940.744.00%32.4%CB #3CB #2CB #30.070.900.060.398.12.230.87120.0140.50%2.352.992.36830.647.50%37.0%CB #2CB #1CB #20.070.900.070.468.72.150.98120.0140.50%2.352.992.43330.251.00%41.7%CB #1 PSE#2 CB #1 0.01 0.90 0.01 0.47 8.9 2.12 0.99 18 0.014 0.50% 6.92 3.92 2.22 15 0.1 30.00% 14.3%PSE#2PSE#1PSE#20.000.000.002.888.92.126.10180.0140.30%5.363.034.664151.569.50%113.9%PSE#1TunnelPSE#10.000.000.002.8810.41.955.62180.0140.30%5.363.034.28140.169.50%104.8% LocationNotesFRQQFRQQSouthport HotelConveyance Analysis - 25 Year8/2/2019 25-Year BackwaterBackwater Analysis TableMannings Coefficient0.014Storm Event Return Period 25PSE Stormwater Reroute Q L Pipe TYP Outlet Inlet Barrel Barrel Velocity Excel Critical TW Friction HGL Entry Entry Exit Outlet Headwater Inlet Approach Bend Bend Junc Loss Junction Headwater Rim Elev. O.K.? Submerged Submerged DownstreamUpstream(cfs)(FT)Diam (in).nElevElevAreaVelocityHeadCheckDepthElevLossElevCoefLossLossControlDepthControlHeadCoefficientLossCoefficientLossElevationDifferenceCheckPSE#3 PSE#4 3.13 199 15 0.014 19.00 19.99 1.227 2.548 0.101 1.00 0.71 21.74 0.536 22.28 0.50 0.05 0.1022.430.64 20.79 -0.10 0.00 0.00 0.00 0.00 22.33 23.50 1.17 yes unsubmerged 2.279PSE#2 PSE#3 5.71 172 15 0.014 18.14 19.00 1.227 4.650 0.336 1.00 0.97 20.03 1.542 21.57 0.50 0.17 0.3422.081.23 20.54 -0.34 0.00 0.00 0.00 0.00 21.74 23.00 1.26 yes submerged 4.159CB #5 CB #6 0.58 38 12 0.014 20.13 20.32 0.785 0.744 0.009 1.00 0.32 21.06 0.012 21.32 0.50 0.00 0.0121.330.33 20.65 -0.01 -3.70 -0.03 -5.00 -0.04 21.25 23.69 2.44 yesunsubmerged 0.744CB #4 CB #5 0.65 100 12 0.014 19.63 20.13 0.785 0.828 0.011 1.00 0.34 21.07 0.038 21.13 0.50 0.01 0.0121.150.35 20.48 -0.01 -2.70 -0.03 -4.00 -0.04 21.06 23.23 2.17 yesunsubmerged 0.828CB #3 CB #4 0.76 94 12 0.014 19.16 19.63 0.785 0.969 0.015 1.00 0.36 21.08 0.049 21.13 0.50 0.01 0.0121.150.38 20.01 -0.01 -1.70 -0.02 -3.00 -0.04 21.07 22.73 1.66 yesunsubmerged 0.969CB #2 CB #3 0.87 83 12 0.014 18.74 19.16 0.785 1.106 0.019 1.00 0.39 21.06 0.057 21.12 0.50 0.01 0.0221.150.41 19.57 -0.02 -0.70 -0.01 -2.00 -0.04 21.08 22.24 1.16 yesunsubmerged 1.106CB #1 CB #2 0.98 33 12 0.014 18.58 18.74 0.785 1.248 0.024 1.00 0.42 20.04 0.029 20.07 0.50 0.01 0.0220.110.44 19.18 -0.02 0.30 0.01 -1.00 -0.02 20.06 21.79 1.73 yes unsubmerged 1.248PSE#2 CB #1 0.99 15 18 0.014 18.00 18.08 1.767 0.559 0.005 1.00 0.37 20.03 0.002 20.03 0.50 0.00 0.0020.040.26 18.47 0.00 1.30 0.01 0.00 0.00 20.04 22.00 1.96 yes unsubmerged 0.456PSE#1 PSE#2 6.10 415 18 0.014 16.90 18.14 1.767 3.454 0.185 1.00 0.95 18.52 1.611 20.14 0.50 0.03 0.0520.220.73 19.24 -0.19 0.00 0.00 0.00 0.00 20.03 22.25 2.22 yes unsubmerged 2.820Tunnel PSE#1 5.62 14 18 0.014 12.50 16.90 1.767 3.178 0.157 1.00 0.91 18.40 0.046 18.45 0.50 0.08 0.1618.680.85 18.17 -0.16 0.00 0.00 0.00 0.00 18.52 21.78 3.26 yes unsubmerged 2.595Southport Park Avenue ExtensionLocationThe elevation of the rim.The difference between the water elevation and the rim should be greater than 0.5 feet for the 25-year storm event.The elevation of the rim.The difference between the water elevation and the rim should be greater than 1.0 feet for the 25-year storm event.Southport HotelBackwater Analysis - 25-Year8/2/2019 WWHM2012 PROJECT REPORT 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:06:50 AM Page 2 General Model Information Project Name:2019-05-09 WWHM for Storm Filter CB Site Name: Site Address: City: Report Date:5/20/2019 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.00 Version Date:2016/02/25 Version:4.2.12 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:06:50 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 1.56 Impervious Total 1.56 Basin Total 1.56 Element Flows To: Surface Interflow Groundwater 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:06:50 AM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.97 Pervious Total 0.97 Impervious Land Use acre ROADS FLAT 0.59 Impervious Total 0.59 Basin Total 1.56 Element Flows To: Surface Interflow Groundwater 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:06:50 AM Page 5 Routing Elements Predeveloped Routing 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:06:50 AM Page 6 Mitigated Routing 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:06:50 AM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:1.56 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.97 Total Impervious Area:0.59 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.594773 5 year 0.751267 10 year 0.857595 25 year 0.995517 50 year 1.101078 100 year 1.209204 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.304594 5 year 0.423886 10 year 0.511194 25 year 0.631278 50 year 0.728029 100 year 0.831202 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.770 0.471 1950 0.832 0.444 1951 0.481 0.281 1952 0.428 0.182 1953 0.462 0.189 1954 0.484 0.248 1955 0.548 0.267 1956 0.540 0.260 1957 0.612 0.344 1958 0.494 0.230 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:19 AM Page 8 1959 0.504 0.191 1960 0.494 0.293 1961 0.523 0.273 1962 0.456 0.197 1963 0.506 0.275 1964 0.496 0.238 1965 0.631 0.360 1966 0.422 0.198 1967 0.727 0.440 1968 0.826 0.424 1969 0.574 0.325 1970 0.554 0.285 1971 0.661 0.345 1972 0.682 0.431 1973 0.413 0.173 1974 0.603 0.341 1975 0.695 0.354 1976 0.467 0.256 1977 0.506 0.238 1978 0.619 0.287 1979 0.847 0.344 1980 0.760 0.514 1981 0.622 0.303 1982 0.876 0.513 1983 0.713 0.313 1984 0.450 0.222 1985 0.620 0.305 1986 0.537 0.279 1987 0.829 0.351 1988 0.503 0.190 1989 0.629 0.238 1990 1.060 0.803 1991 0.847 0.582 1992 0.446 0.221 1993 0.386 0.171 1994 0.420 0.159 1995 0.551 0.264 1996 0.586 0.386 1997 0.570 0.328 1998 0.577 0.260 1999 1.181 0.695 2000 0.588 0.312 2001 0.646 0.269 2002 0.754 0.448 2003 0.585 0.368 2004 1.105 0.629 2005 0.505 0.279 2006 0.446 0.263 2007 1.033 0.730 2008 0.832 0.565 2009 0.769 0.351 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 1.1811 0.8025 2 1.1050 0.7298 3 1.0599 0.6948 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:19 AM Page 9 4 1.0328 0.6291 5 0.8764 0.5823 6 0.8469 0.5650 7 0.8467 0.5139 8 0.8324 0.5126 9 0.8319 0.4707 10 0.8293 0.4476 11 0.8261 0.4438 12 0.7703 0.4398 13 0.7688 0.4306 14 0.7598 0.4241 15 0.7535 0.3858 16 0.7266 0.3681 17 0.7133 0.3600 18 0.6945 0.3541 19 0.6822 0.3510 20 0.6609 0.3506 21 0.6459 0.3449 22 0.6306 0.3437 23 0.6292 0.3436 24 0.6215 0.3409 25 0.6201 0.3278 26 0.6187 0.3250 27 0.6121 0.3128 28 0.6028 0.3123 29 0.5879 0.3050 30 0.5865 0.3035 31 0.5855 0.2935 32 0.5773 0.2867 33 0.5743 0.2853 34 0.5695 0.2809 35 0.5541 0.2794 36 0.5512 0.2790 37 0.5484 0.2746 38 0.5396 0.2733 39 0.5375 0.2689 40 0.5230 0.2665 41 0.5062 0.2638 42 0.5058 0.2634 43 0.5050 0.2602 44 0.5038 0.2598 45 0.5031 0.2565 46 0.4964 0.2483 47 0.4944 0.2382 48 0.4940 0.2381 49 0.4837 0.2376 50 0.4812 0.2299 51 0.4670 0.2221 52 0.4622 0.2211 53 0.4557 0.1982 54 0.4500 0.1970 55 0.4461 0.1913 56 0.4456 0.1905 57 0.4280 0.1889 58 0.4216 0.1821 59 0.4199 0.1729 60 0.4131 0.1710 61 0.3860 0.1589 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:19 AM Page 10 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:19 AM Page 11 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.2974 1809 134 7 Pass 0.3055 1648 121 7 Pass 0.3136 1481 110 7 Pass 0.3217 1357 106 7 Pass 0.3299 1235 99 8 Pass 0.3380 1119 92 8 Pass 0.3461 1003 87 8 Pass 0.3542 922 80 8 Pass 0.3623 854 75 8 Pass 0.3704 796 66 8 Pass 0.3786 728 57 7 Pass 0.3867 670 53 7 Pass 0.3948 612 48 7 Pass 0.4029 576 48 8 Pass 0.4110 532 46 8 Pass 0.4192 489 41 8 Pass 0.4273 451 40 8 Pass 0.4354 420 35 8 Pass 0.4435 391 33 8 Pass 0.4516 366 31 8 Pass 0.4597 340 28 8 Pass 0.4679 319 27 8 Pass 0.4760 297 24 8 Pass 0.4841 271 21 7 Pass 0.4922 256 20 7 Pass 0.5003 239 19 7 Pass 0.5085 222 19 8 Pass 0.5166 209 17 8 Pass 0.5247 196 17 8 Pass 0.5328 181 16 8 Pass 0.5409 171 14 8 Pass 0.5490 161 13 8 Pass 0.5572 148 13 8 Pass 0.5653 139 12 8 Pass 0.5734 135 11 8 Pass 0.5815 122 9 7 Pass 0.5896 113 7 6 Pass 0.5978 108 7 6 Pass 0.6059 105 6 5 Pass 0.6140 100 5 5 Pass 0.6221 92 4 4 Pass 0.6302 87 3 3 Pass 0.6383 84 3 3 Pass 0.6465 73 3 4 Pass 0.6546 71 3 4 Pass 0.6627 66 3 4 Pass 0.6708 64 3 4 Pass 0.6789 63 3 4 Pass 0.6871 58 3 5 Pass 0.6952 54 2 3 Pass 0.7033 54 2 3 Pass 0.7114 52 2 3 Pass 0.7195 50 2 4 Pass 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:19 AM Page 12 0.7276 46 2 4 Pass 0.7358 45 1 2 Pass 0.7439 42 1 2 Pass 0.7520 38 1 2 Pass 0.7601 33 1 3 Pass 0.7682 32 1 3 Pass 0.7764 29 1 3 Pass 0.7845 28 1 3 Pass 0.7926 25 1 4 Pass 0.8007 22 1 4 Pass 0.8088 21 0 0 Pass 0.8169 20 0 0 Pass 0.8251 17 0 0 Pass 0.8332 13 0 0 Pass 0.8413 12 0 0 Pass 0.8494 9 0 0 Pass 0.8575 9 0 0 Pass 0.8657 9 0 0 Pass 0.8738 9 0 0 Pass 0.8819 8 0 0 Pass 0.8900 8 0 0 Pass 0.8981 8 0 0 Pass 0.9062 8 0 0 Pass 0.9144 8 0 0 Pass 0.9225 8 0 0 Pass 0.9306 8 0 0 Pass 0.9387 7 0 0 Pass 0.9468 7 0 0 Pass 0.9550 7 0 0 Pass 0.9631 7 0 0 Pass 0.9712 7 0 0 Pass 0.9793 7 0 0 Pass 0.9874 6 0 0 Pass 0.9955 6 0 0 Pass 1.0037 6 0 0 Pass 1.0118 6 0 0 Pass 1.0199 6 0 0 Pass 1.0280 6 0 0 Pass 1.0361 5 0 0 Pass 1.0443 5 0 0 Pass 1.0524 4 0 0 Pass 1.0605 3 0 0 Pass 1.0686 3 0 0 Pass 1.0767 2 0 0 Pass 1.0848 2 0 0 Pass 1.0930 2 0 0 Pass 1.1011 2 0 0 Pass 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:19 AM Page 13 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.1058 acre-feet On-line facility target flow:0.0984 cfs. Adjusted for 15 min:0.0984 cfs. Off-line facility target flow:0.0543 cfs. Adjusted for 15 min:0.0543 cfs. 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:19 AM Page 14 LID Report 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:25 AM Page 15 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:25 AM Page 16 Appendix Predeveloped Schematic 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:25 AM Page 17 Mitigated Schematic 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 18 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 2019-05-09 WWHM for Storm Filter CB.wdm MESSU 25 Pre2019-05-09 WWHM for Storm Filter CB.MES 27 Pre2019-05-09 WWHM for Storm Filter CB.L61 28 Pre2019-05-09 WWHM for Storm Filter CB.L62 30 POC2019-05-09 WWHM for Storm Filter CB1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 IMPLND 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 19 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 ROADS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 END IWAT-STATE1 END IMPLND 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 20 SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** IMPLND 1 1.56 COPY 501 15 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 21 END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 END MASS-LINK END RUN 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 22 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 2019-05-09 WWHM for Storm Filter CB.wdm MESSU 25 Mit2019-05-09 WWHM for Storm Filter CB.MES 27 Mit2019-05-09 WWHM for Storm Filter CB.L61 28 Mit2019-05-09 WWHM for Storm Filter CB.L62 30 POC2019-05-09 WWHM for Storm Filter CB1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 17 IMPLND 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 17 C, Lawn, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 17 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 17 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 23 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 17 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 17 0 4.5 0.03 400 0.1 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 17 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 17 0.1 0.25 0.25 6 0.5 0.25 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 17 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 ROADS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 24 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 17 0.97 COPY 501 12 PERLND 17 0.97 COPY 501 13 IMPLND 1 0.59 COPY 501 15 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 25 END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 END MASS-LINK END RUN 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 26 Predeveloped HSPF Message File 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 27 Mitigated HSPF Message File 2019-05-09 WWHM for Storm Filter CB 5/20/2019 10:07:26 AM Page 28 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com n i Stormwater Pollution Prevention Plan For Southport Park Avenue Extension: Prepared For Northwest Regional Office 3190 - 160th Avenue SE Bellevue, WA 98008-5452 425-649-7000 Owner Developer Operator/Contractor SECO Development, Inc. SECO Development, Inc. TBD 1083 Lake Washington Boulevard North, #50 1083 Lake Washington Boulevard North, #50 TBD Renton, Washington 98056 Renton, Washington 98056 TBD Project Site Location Renton, Washington Certified Erosion and Sediment Control Lead TBD SWPPP Prepared By Coughlin Porter Lundeen 801 Second Ave Suite# 900 Seattle, WA 98104 (206) 343-0460 Ashton Huff, Civil Engineer SWPPP Preparation Date 5/17/2019 Approximate Project Construction Dates 08-01-2019 to 01-01-2020 n ii Contents 1.0 Introduction ...............................................................................................................................1 2.0 Site Description ........................................................................................................................3 2.1 Existing Conditions ...........................................................................................................3 2.2 Proposed Construction Activities ......................................................................................3 3.0 Construction Stormwater BMPs ...............................................................................................5 3.1 The 12 BMP Elements .......................................................................................................5 3.1.1 Element #1 – Mark Clearing Limits ...................................................................5 3.1.2 Element #2 – Establish Construction Access .....................................................5 3.1.3 Element #3 – Control Flow Rates .......................................................................6 3.1.4 Element #4 – Install Sediment Controls .............................................................6 3.1.5 Element #5 – Stabilize Soils ...............................................................................7 3.1.6 Element #6 – Protect Slopes ...............................................................................8 3.1.7 Element #7 – Protect Drain Inlets .......................................................................8 3.1.8 Element #8 – Stabilize Channels and Outlets .....................................................9 3.1.9 Element #9 – Control Pollutants .........................................................................9 3.1.10 Element #10 – Control Dewatering .................................................................11 3.1.11 Element #11 – Maintain BMPs .......................................................................11 3.1.12 Element #12 – Manage the Project ..................................................................11 5.0 Pollution Prevention Team ......................................................................................................17 5.1 Roles and Responsibilities ...............................................................................................17 5.2 Team Members ................................................................................................................17 6.0 Site Inspections and Monitoring .............................................................................................19 6.1 Site Inspection .................................................................................................................19 6.1.1 Site Inspection Frequency ................................................................................19 6.1.2 Site Inspection Documentation .........................................................................19 6.2 Stormwater Quality Monitoring ......................................................................................20 6.2.2 pH Sampling .....................................................................................................20 7.0 Reporting and Recordkeeping ................................................................................................23 7.1 Recordkeeping .................................................................................................................23 7.1.1 Site Log Book ...................................................................................................23 7.1.2 Records Retention.............................................................................................23 7.1.3 Access to Plans and Records ............................................................................23 7.1.4 Updating the SWPPP ........................................................................................23 7.2 Reporting .........................................................................................................................24 7.2.1 Discharge Monitoring Reports .........................................................................24 7.2.2 Notification of Noncompliance ........................................................................24 7.2.3 Permit Application and Changes ......................................................................24 n iii Appendix A – Site Plans .........................................................................................................25 Appendix B – Construction BMPs .........................................................................................26 Appendix C – Alternative BMPs ............................................................................................27 Appendix D – General Permit ................................................................................................29 Appendix E – Site Inspection Forms (and Site Log) ..............................................................30 Appendix F – Engineering Calculations .................................................................................39 Appendix A Site plans Appendix B Construction BMPs Appendix C Alternative Construction BMP list Appendix D General Permit Appendix E Site Log and Inspection Forms Appendix F Engineering Calculations Stormwater Pollution Prevention Plan 1 1.0 Introduction This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES stormwater permit requirements for the Southport Park Avenue Extension construction project in Renton, Washington. The site is situated at the southern tip of Lake Washington to the west of the Gene Coulon Memorial Beach Park. The site is in the NW ¼ of the NW ¼ of Section 8, Township 23 North, Range 5 East, Willamette Meridian. The site will occupy parcels 082305917807 and 082305919100, with an area of 439,578-SF. The existing site consists of 1.56 acres of entirely impervious area. Overall, the proposed project will include roadway paving, concrete sidewalk, catch basins, and a Contech Solutions StormFilter catch basin for water quality purposes. The proposed conditions will consist of approximately 1.56 acres of impervious area. Construction activities will include demolition, excavation, grading, and relocation of onsite utilities. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, inspection/monitoring activities, and recordkeeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to: 1. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee’s outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology website. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit and Stormwater Management Manual for Western Washington (SWMMWW 2005). The report is divided into seven main sections with several appendices that include stormwater related reference materials. The topics presented in the each of the main sections are: Section 1 – INTRODUCTION. This section provides a summary description of the project, and the organization of the SWPPP document. Stormwater Pollution Prevention Plan 2 Section 2 – SITE DESCRIPTION. This section provides a detailed description of the existing site conditions, proposed construction activities, and calculated stormwater flow rates for existing conditions and post– construction conditions. Section 3 – CONSTRUCTION BMPs. This section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP. Section 4 – CONSTRUCTION PHASING AND BMP IMPLEMENTATION. This section provides a description of the timing of the BMP implementation in relation to the project schedule. Section 5 – POLLUTION PREVENTION TEAM. This section identifies the appropriate contact names (emergency and non-emergency), monitoring personnel, and the onsite temporary erosion and sedimentation control inspector Section 6 – INSPECTION AND MONITORING. This section provides a description of the inspection and monitoring requirements such as the parameters of concern to be monitored, sample locations, sample frequencies, and sampling methods for all stormwater discharge locations from the site. Section 7 – RECORDKEEPING. This section describes the requirements for documentation of the BMP implementation, site inspections, monitoring results, and changes to the implementation of certain BMPs due to site factors experienced during construction. Supporting documentation and standard forms are provided in the following Appendices: Appendix A – Site plans Appendix B – Construction BMPs Appendix C – Alternative Construction BMP list Appendix D – General Permit Appendix E – Site Log and Inspection Forms Appendix F – Engineering Calculations Stormwater Pollution Prevention Plan 3 2.0 Site Description 2.1 Existing Conditions The existing site consists of asphalt and gravel. The site was previously home to the Shuffleton Steam Plant, which was built in the 1930’s and demolished in 2001. The site is situated at the southern tip of Lake Washington to the west of the Gene Coulon Memorial Beach Park. The site is in the NW ¼ of the NW ¼ of Section 8, Township 23 North, Range 5 East, Willamette Meridian. The site will occupy parcels 082305917807 and 082305919100, with an area of 439,578-SF. The area of disturbance is 1.56 acres in size and includes a roadway portion, concrete sidewalk, and grassed area. The topography of the site and surrounding properties gently slopes to the northwest with approximately three feet of elevation change. Per the geotechnical report provided for the public Park Avenue extension project, soil depth and thickness vary throughout the site. Generally, the site is loose to medium silty sand. Groundwater lies as high as four feet below existing grade in some areas. Runoff from the site generally sheet flows to the north side of the site, into the existing PSE storm system, ultimately discharging directly to Lake Washington. Based on city of Renton GIS data and available survey information, the southwest portion of the site, located southwest of the proposed road and just north of existing 757th Avenue, currently drains west to the adjacent Boeing property and then to Lake Washington. There are no critical areas on the site such as high erosion risk areas, wetlands, streams, or steep slopes (potential landslide area). The project site is, however, a seismic hazard area, according to City of Renton map data. 2.2 Proposed Construction Activities Overall, the project will include additional roadway paving, concrete sidewalk, catch basins, a Contech Solutions StormFilter catch basin, and light poles. Construction activities will include site preparation, TESC installation, demolition of the existing asphalt on site, concrete sidewalk construction, site-wide grading, asphalt paving, and seeding of unpaved areas. The schedule and phasing of BMPs during construction is provided in Section 4.0. Stormwater runoff volumes were calculated using the computer software WWHM2012. Basic Water Quality Treatment will be provided by the Contech Solutions StormFilter catch basin. The peak flows are based on the developed conditions after construction. Stormwater Pollution Prevention Plan 5 3.0 Construction Stormwater BMPs 3.1 The 12 BMP Elements 3.1.1 Element #1 – 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: · High Visibility Plastic or Metal Fence (BMP C103) Alternate BMPs for marking clearing limits are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 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: · Stabilized Construction Entrance (BMP C105) · Wheel Wash (BMP C106) · Construction Road/Parking Area Stabilization (BMP C107) Alternate construction access BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the Stormwater Pollution Prevention Plan 6 alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.3 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: No BMPs to be implemented. Alternate flow control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, the project must comply with Minimum Requirement 7 (Ecology 2005). In general, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). 3.1.4 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 prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: · Detention Pond Or Vault · Storm Drain Inlet Protection (BMP C220) Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the Stormwater Pollution Prevention Plan 7 alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in runoff. Whenever possible, sediment laden water shall be discharged into onsite, relatively level, vegetated areas (BMP C240 paragraph 5, page 4-102). In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention ponds) can be used during the construction phase. When permanent stormwater BMPs will be used to control sediment discharge during construction, the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated sediment shall be removed after construction is complete and the permanent stormwater BMP will be restabilized with vegetation per applicable design requirements. The following BMPs will be implemented as end-of-pipe sediment controls as required to meet permitted turbidity limits in the site discharge(s). Prior to the implementation of these technologies, sediment sources and erosion control and soil stabilization BMP efforts will be maximized to reduce the need for end-of-pipe sedimentation controls. Temporary Sediment Pond (BMP C241) Construction Stormwater Filtration (BMP C251) Construction Stormwater Chemical Treatment (BMP C 250) (implemented only with prior written approval from Ecology). 3.1.5 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 include: · Temporary and Permanent Seeding (BMP C120) Alternate soil stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate Stormwater Pollution Prevention Plan 8 during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain exposed and unworked for more than 7 days during the dry season (May 1 to September 30) and 2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. 3.1.6 Element #6 – Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner than minimizes erosion. The following specific BMPs will be used to protect slopes for this project: · Temporary and Permanent Seeding (BMP C120) Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 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. The following inlet protection measures will be applied on this project: Stormwater Pollution Prevention Plan 9 Drop Inlet Protection · Catch Basin Filters If the BMP options listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D), or if no BMPs are listed above but deemed necessary during construction, the Certified Erosion and Sediment Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix C. 3.1.8 Element #8 – Stabilize Channels and Outlets Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: No BMPs to be implemented Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, all temporary on-site conveyance channels shall be designed, constructed, and stabilized to prevent erosion from the expected peak 10 minute velocity of flow from a Type 1A, 10-year, 24-hour recurrence interval storm for the developed condition. Alternatively, the 10-year, 1-hour peak flow rate indicated by an approved continuous runoff simulation model, increased by a factor of 1.6, shall be used. Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent streambanks, slopes, and downstream reaches shall be provided at the outlets of all conveyance systems. 3.1.9 Element #9 – Control Pollutants 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. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. Stormwater Pollution Prevention Plan 10 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). 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). Sanitary wastewater: Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Stormwater Pollution Prevention Plan 11 Wheel wash or tire bath wastewater shall be discharged to a separate on- site treatment system or to the sanitary sewer as part of Wheel Wash implementation (BMP C106). Solid Waste: Solid waste will be stored in secure, clearly marked containers. The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal regulations of the Clean Water Act (CWA). 3.1.10 Element #10 – Control Dewatering Dewatering will not occur with this project. 3.1.11 Element #11 – Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMPs specifications (attached). Visual monitoring of the BMPs 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 will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 3.1.12 Element #12 – Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: Design the project to fit the existing topography, soils, and drainage patterns. Emphasize erosion control rather than sediment control. Minimize the extent and duration of the area exposed. Keep runoff velocities low. Retain sediment on site. Stormwater Pollution Prevention Plan 12 Thoroughly monitor site and maintain all ESC measures. Schedule major earthwork during the dry season. In addition, project management will incorporate the key components listed below: As this project site is located west of the Cascade Mountain Crest, the project will be managed according to the following key project components: Phasing of Construction The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the maximum extent possible, the transport of sediment from the site during construction. Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C 162). Seasonal Work Limitations From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt-laden runoff will be prevented from leaving the site through a combination of the following: Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and Limitations on activities and the extent of disturbed areas; and Proposed erosion and sediment control measures. Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. The following activities are exempt from the seasonal clearing and grading limitations: Routine maintenance and necessary repair of erosion and sediment control BMPs; Stormwater Pollution Prevention Plan 13 Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. Inspection and Monitoring All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: Assess the site conditions and construction activities that could impact the quality of stormwater, and Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all times. Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP This SWPPP shall be retained on-site or within reasonable access to the site. The SWPPP shall be modified whenever there is a change in the 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. Stormwater Pollution Prevention Plan 14 The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. Alternate dewatering control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. Stormwater Pollution Prevention Plan 15 4.0 Construction Phasing and BMP Implementation The BMP implementation schedule will be driven by the construction schedule. The following provides a sequential list of the proposed construction schedule milestones and the corresponding BMP implementation schedule. The list contains key milestones such as wet season construction. The BMP implementation schedule listed below is keyed to proposed phases of the construction project and reflects differences in BMP installations and inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such, the dry season is considered to be from May 1 to September 30 and the wet season is considered to be from October 1 to April 30. Estimate of Construction start date: TBD Estimate of Construction finish date: TBD Mobilize equipment on site: TBD Mobilize and store all ESC and soil stabilization products (store materials on hand BMP C150): TBD Install ESC measures: TBD Install stabilized construction entrance: TBD Begin clearing and grubbing: TBD Soil stabilization on excavated sideslopes (in idle, no work areas as shown on ESC plans) TBD Temporary erosion control measures (hydroseeding) TBD Site inspections reduced to monthly: TBD Begin concrete pour and implement BMP C151: TBD Excavate and install new utilities and services (Phase 1): TBD Begin building construction: TBD Complete Phase 1 utility construction TBD Stormwater Pollution Prevention Plan 16 Begin implementing soil stabilization and sediment control BMPs throughout the site in preparation for wet season: TBD Wet Season starts: 10 / 01 / 2019 Site inspections and monitoring conducted weekly and for applicable rain events as detailed in Section 6 of this SWPPP: TBD Implement Element #12 BMPs and manage site to minimize soil disturbance during the wet season TBD No site work such as grading or excavation planned: Dry Season starts: 05 / 01 / 2020 Site grading begins: TBD Excavate and install new utilities and services (Phase 2): TBD Site grading ends: TBD Permanent erosion control measures (hydroseeding): TBD Stormwater Pollution Prevention Plan 17 5.0 Pollution Prevention Team 5.1 Roles and Responsibilities The pollution prevention team consists of personnel responsible for implementation of the SWPPP, including the following: Certified Erosion and Sediment Control Lead (CESCL) – primary contractor contact, responsible for site inspections (BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ESC measures. Resident Engineer – For projects with engineered structures only (sediment ponds/traps, sand filters, etc.): site representative for the owner that is the project's supervising engineer responsible for inspections and issuing instructions and drawings to the contractor's site supervisor or representative Emergency Ecology Contact – individual to be contacted at Ecology in case of emergency. Emergency Owner Contact – individual that is the site owner or representative of the site owner to be contacted in the case of an emergency. Non-Emergency Ecology Contact – individual that is the site owner or representative of the site owner than can be contacted if required. Monitoring Personnel – personnel responsible for conducting water quality monitoring; for most sites this person is also the Certified Erosion and Sediment Control Lead. 5.2 Team Members Names and contact information for those identified as members of the pollution prevention team are provided in the following table. Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD TBD Resident Engineer Tim Brockway, P.E. (206) 343-0460 Emergency Ecology Contact TBD TBD Emergency Owner Contact TBD TBD Stormwater Pollution Prevention Plan 18 Non-Emergency Ecology Contact TBD TBD Monitoring Personnel TBD TBD Stormwater Pollution Prevention Plan 19 6.0 Site Inspections and Monitoring Monitoring includes visual inspection, monitoring for water quality parameters of concern, and documentation of the inspection and monitoring 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; and, Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site log book if desired, or the forms may be separated and included in a separate site log book. However, if separated, the site log book but must be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.1 Site Inspection All BMPs will be inspected, maintained, and repaired as needed to assure continued performance of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead (CESCL) per BMP C160. The name and contact information for the CESCL is provided in Section 5 of this SWPPP. Site inspection will occur in all areas disturbed b y construction activities and at all stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be documented in the site log book or forms provided in this document. All new BMPs or design changes will be documented in the SWPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspections will be conducted at least once a week and within 24 hours following any discharge from the site. For sites with temporary stabilization measures, the site inspection frequency can be reduced to once every month. 6.1.2 Site Inspection Documentation The site inspector will record each site inspection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document, but Stormwater Pollution Prevention Plan 20 will be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.2 Stormwater Quality Monitoring Monitoring requirements for the proposed project will include either turbidity or water transparency sampling to monitor site discharges for water quality compliance with the 2005 Construction Stormwater General Permit (Appendix D). Sampling will be conducted at all discharge points at least once per calendar week. Turbidity or transparency monitoring will follow the analytical methodologies described in Section S4 of the 2005 Construction Stormwater General Permit (Appendix D). The key benchmark turbidity value is 25 nephelometric turbidity units (NTU) for the downstream receiving water body. If the 25 NTU benchmark is exceeded in any sample collected from CB5, the following steps will be conducted: 1. Ensure all BMPs specified in this SWPPP are installed and functioning as intended. 2. Assess whether additional BMPs should be implemented, and document modified BMPs in the SWPPP as necessary. 3. Sample discharge daily until the discharge is 25 NTU or lower. If the turbidity exceeds 250 NTU at any time, the following steps will be conducted: 1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of this SWPPP for contact information). 2. Continue sampling daily until the discharge is 25 NTU or lower Initiate additional treatment BMPs such as off-site treatment, infiltration, filtration and chemical treatment within 24 hours, and implement those additional treatment BMPs as soon as possible, but within a minimum of 7 days. 3. Describe inspection results and remedial actions taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.2 pH Sampling Stormwater runoff will be monitored for pH starting on the first day of any activity that includes more than 40 yards of poured or recycled concrete, or after the application of “Engineered Soils” such as, Portland cement treated base, cement kiln dust, or fly ash. This does not include fertilizers. For concrete work, pH monitoring will start the first day concrete is poured and Stormwater Pollution Prevention Plan 21 continue until 3 weeks after the last pour. For engineered soils, the pH monitoring period begins when engineered soils are first exposed to precipitation and continue until the area is fully stabilized. Stormwater samples will be collected weekly from all points of discharge from the site and measured for pH using a calibrated pH meter, pH test kit, or wide range pH indicator paper. If the measured pH is 8.5 or greater, the following steps will be conducted: 1. Prevent the high pH water from entering storm drains or surface water. 2. Adjust or neutralize the high pH water if necessary using appropriate technology such as CO2 sparging (liquid or dry ice). 3. Contact Ecology if chemical treatment other than CO2 sparging is planned. Stormwater Pollution Prevention Plan 23 7.0 Reporting and Recordkeeping 7.1 Recordkeeping 7.1.1 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; and, Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. 7.1.2 Records Retention Records of all monitoring information (site log book, inspection reports/checklists, etc.), this Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit requirements will be retained during the life of the construction project and for a minimum of three years following the termination of permit coverage in accordance with permit condition S5.C. 7.1.3 Access to Plans and Records The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be retained on site or within reasonable access to the site and will be made immediately available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written request for the SWPPP from Ecology. Any other information requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with permit condition S5.G. 7.1.4 Updating the SWPPP In accordance with Conditions S3, S4.B, and S9.B.3 of the General Permit, this SWPPP will be modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site or there has been a change in design, construction, operation, or maintenance at the site that has a significant effect on the discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP will be modified within seven days of determination based on inspection(s) that additional or modified BMPs are necessary to correct problems identified, and an updated timeline for BMP implementation will be prepared. Stormwater Pollution Prevention Plan 24 7.2 Reporting 7.2.1 Discharge Monitoring Reports If cumulative soil disturbance is 5 acres or larger: Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. Of there was no discharge during a given monitoring period, the Permittee shall submit the form as required, with the words “No discharge” entered in the place of monitoring results. The DMR due date is 15 days following the end of each month. 7.2.2 Notification of Noncompliance If any of the terms and conditions of the permit are not met, and it causes a threat to human health or the environment, the following steps will be taken in accordance with permit section S5.F: 1. Ecology will be immediately notified of the failure to comply. 2. Immediate action will be taken to control the noncompliance issue and to correct the problem. 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. 7.2.3 Permit Application and Changes In accordance with permit condition S2.A, a complete application form will be submitted to Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General Permit. Stormwater Pollution Prevention Plan 25 Appendix A – Site Plans Stormwater Pollution Prevention Plan 26 Appendix B – Construction BMPs 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 watercourses 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 gen- erally 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 veget- ation 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 usu- ally do not cause problems although sensitivity between species does vary and should be checked.Trees can typically tolerate fill of 6 inches or less.For shrubs 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 266 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.A tile system protects a tree from a raised grade.The tile system should be laid out on the original grade leading from a dry well around the tree trunk.The system should then be covered with small stones to allow air to circulate over the root area. Lowering the natural ground level can seriously damage trees and shrubs.The highest percentage 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 neces- sary 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 undisturbed,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 pre- serve 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, 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 267 Sitka spruce,Western red cedar,Western hemlock,Pacific dogwood,and Red alder can cause serious 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. l If tree roots have been exposed or injured,“prune”cleanly with an appropriate prun- ing saw or loppers 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 runoff velocities. Conditions of Use Natural buffer zones are used along streams,wetlands and other bodies of water that need protection from erosion and sedimentation.Vegetative buffer zones can be used to protect natural swales and can be incorporated into the natural landscaping of an area. Critical-areas buffer zones should not be used as sediment treatment areas.These areas shall remain completely undisturbed.The local permitting authority may expand the buffer widths temporarily to allow the use of the expanded area for removal of sed- iment. 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 nat- ural areas and buffer zones.Steel construction fencing is the most effective method in protecting 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 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 268 damage from burying and smothering. 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 undisturbed.Replace all damaged flagging immediately. BMP C103:High Visibility Fence Purpose Fencing is intended to: 1.Restrict clearing to approved limits. 2.Prevent disturbance of sensitive areas,their buffers,and other areas required to be left undisturbed. 3.Limit construction traffic to designated construction entrances,exits,or internal roads. 4.Protect areas where marking with survey tape may not provide adequate pro- tection. 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 sag- ging 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 (p.367)to act as high visibility fence.Silt fence shall be at least 3 feet high and must be highly vis- ible to meet the requirements of this BMP. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 269 Metal fences shall be designed and installed according to the manufacturer's spe- cifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. Maintenance Standards If the fence has been damaged or visibility reduced,it shall be repaired or replaced immediately and visibility restored. BMP C105:Stabilized Construction Entrance /Exit Purpose Stabilized Construction entrances are established to reduce the amount of sediment transported onto paved roads by vehicles or equipment.This is done by constructing a stabilized pad of quarry spalls at entrances and exits for construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be entering or leaving a construction site if paved roads or other paved areas are within 1,000 feet of the site. For residential construction provide stabilized construction entrances for each residence, rather than only at the main subdivision entrance.Stabilized surfaces shall be of suf- ficient length/width to provide vehicle access/parking,based on lot size/configuration. On large commercial,highway,and road projects,the designer should include enough extra materials in the contract to allow for additional stabilized entrances not shown in the initial Construction SWPPP.It is difficult to determine exactly where access to these projects will take place;additional materials will enable the contractor to install them where needed. Design and Installation Specifications See Figure II-4.1.1 Stabilized Construction Entrance (p.273)for details.Note:the 100’ minimum length of the entrance shall be reduced to the maximum practicable size when the size or configuration of the site does not allow the full length (100’). Construct stabilized construction entrances with a 12-inch thick pad of 4-inch to 8-inch quarry spalls,a 4-inch course of asphalt treated base (ATB),or use existing pavement. Do not use crushed concrete,cement,or calcium chloride for construction entrance sta- bilization because these products raise pH levels in stormwater and concrete discharge to surface waters of the State is prohibited. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 270 A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad.The geotextile shall meet the following standards: Grab Tensile Strength (ASTM D4751)200 psi min. Grab Tensile Elongation (ASTM D4632)30%max. Mullen Burst Strength (ASTM D3786-80a)400 psi min. AOS (ASTM D4751)20-45 (U.S.standard sieve size) l Consider early installation of the first lift of asphalt in areas that will paved;this can be used as a stabilized entrance.Also consider the installation of excess concrete as a stabilized entrance.During large concrete pours,excess concrete is often available for this purpose. l Fencing (see BMP C103:High Visibility Fence (p.269))shall be installed as neces- sary to restrict traffic to the construction entrance. l Whenever possible,the entrance shall be constructed on a firm,compacted sub- grade.This can substantially increase the effectiveness of the pad and reduce the need for maintenance. l Construction entrances should avoid crossing existing sidewalks and back of walk drains if at all possible.If a construction entrance must cross a sidewalk or back of walk drain,the full length of the sidewalk and back of walk drain must be covered and protected from sediment leaving the site. Maintenance Standards Quarry spalls shall be added if the pad is no longer in accordance with the spe- cifications. l If the entrance is not preventing sediment from being tracked onto pavement,then alternative measures to keep the streets free of sediment shall be used.This may include replacement/cleaning of the existing quarry spalls,street sweeping,an increase in the dimensions of the entrance,or the installation of a wheel wash. l Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping.The sediment collected by sweeping shall be removed or sta- bilized on site.The pavement shall not be cleaned by washing down the street, except when high efficiency sweeping is ineffective and there is a threat to public safety.If it is necessary to wash the streets,the construction of a small sump to con- tain the wash water shall be considered.The sediment would then be washed into the sump where it can be controlled. l Perform street sweeping by hand or with a high efficiency sweeper.Do not use a non-high efficiency mechanical sweeper because this creates dust and throws soils into storm systems or conveyance ditches. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 271 l Any quarry spalls that are loosened from the pad,which end up on the roadway shall be removed immediately. l If vehicles are entering or exiting the site at points other than the construction entrance(s),fencing (see BMP C103)shall be installed to control traffic. l Upon project completion and site stabilization,all construction accesses intended as permanent access for maintenance shall be permanently stabilized. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 272 Figure II-4.1.1 Stabilized Construction Entrance D E P A R T M E N T O F E C O L O G Y S t a t e o f W a s h i n g t o n Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure II-4.1.1 Stabilized Construction Entrance Revised June 2015 NOT TO SCALE Existin g R o a d Notes: 1.Driveway shall meet the requirements of the permitting agency. 2.It is recommended that the entrance be crowned so that runoff drains off the pad. Install driveway culvert if there is a roadside ditch present 4" - 8" quarry spalls Geotextile 12" minimum thickness 15' min. 100' min. Provide full width of ingress/egress area 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 273 Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C105:Stab- ilized Construction Entrance /Exit.The products did not pass through the Technology Assessment Protocol –Ecology (TAPE)process.Local jurisdictions may choose not to accept this product approved as equivalent,or may require additional testing prior to con- sideration for local use.The products are available for review on Ecology’s website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html BMP C106:Wheel Wash Purpose Wheel washes reduce the amount of sediment transported onto paved roads by motor vehicles. Conditions of Use When a stabilized construction entrance (see BMP C105:Stabilized Construction Entrance /Exit (p.270))is not preventing sediment from being tracked onto pavement. l Wheel washing is generally an effective BMP when installed with careful attention to topography.For example,a wheel wash can be detrimental if installed at the top of a slope abutting a right-of-way where the water from the dripping truck can run unimpeded into the street. l Pressure washing combined with an adequately sized and surfaced pad with dir- ect drainage to a large 10-foot x 10-foot sump can be very effective. l Discharge wheel wash or tire bath wastewater to a separate on-site treatment sys- tem that prevents discharge to surface water,such as closed-loop recirculation or upland land application,or to the sanitary sewer with local sewer district approval. l Wheel wash or tire bath wastewater should not include wastewater from concrete washout areas. Design and Installation Specifications Suggested details are shown in Figure II-4.1.2 Wheel Wash (p.276).The Local Per- mitting Authority may allow other designs.A minimum of 6 inches of asphalt treated base (ATB)over crushed base material or 8 inches over a good subgrade is recommended to pave the wheel wash. Use a low clearance truck to test the wheel wash before paving.Either a belly dump or lowboy will work well to test clearance. Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck tongues with water. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 274 Midpoint spray nozzles are only needed in extremely muddy conditions. Wheel wash systems should be designed with a small grade change,6-to 12-inches for a 10-foot-wide pond,to allow sediment to flow to the low side of pond to help prevent re- suspension of sediment.A drainpipe with a 2-to 3-foot riser should be installed on the low side of the pond to allow for easy cleaning and refilling.Polymers may be used to promote coagulation and flocculation in a closed-loop system.Polyacrylamide (PAM) added to the wheel wash water at a rate of 0.25 -0.5 pounds per 1,000 gallons of water increases effectiveness and reduces cleanup time.If PAM is already being used for dust or erosion control and is being applied by a water truck,the same truck can be used to change the wash water. Maintenance Standards The wheel wash should start out the day with fresh water. The wash water should be changed a minimum of once per day.On large earthwork jobs where more than 10-20 trucks per hour are expected,the wash water will need to be changed more often. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 275 Figure II-4.1.2 Wheel Wash D E P A R T M E N T O F E C O L O G Y S t a t e o f W a s h i n g t o n Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure II-4.1.2 Wheel Wash Revised June 2015 NOT TO SCALE Notes: 1.Build 8' x 8' sump to accomodate cleaning by trackhoe. 6" sewer pipe with butterfly valves 8' x 8' sump with 5' of catch 3" trash pump with floats on suction hose 2" schedule 40 1 12 " schedule 40 for sprayers midpoint spray nozzles, if needed 15' ATB apron to protect ground from splashing water 6" sleeve under road 6" ATB construction entrance Asphalt curb on the low road side to direct water back to pond Ball valves 2% slope 5:1 slope 1:1 slope 5:1 slope 2% slope A A Plan View 15'15'20'15'50' Curb 6" sleeve Elevation View Locate invert of top pipe 1' above bottom of wheel wash 8' x 8' sump 5' Drain pipe 12' 3' 18' Water level 1:1 slope Section A-A 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 276 BMP C107:Construction Road/Parking Area Stabilization Purpose Stabilizing subdivision roads,parking areas,and other on-site vehicle transportation routes immediately after grading reduces erosion caused by construction traffic or runoff. Conditions of Use Roads or parking areas shall be stabilized wherever they are constructed,whether per- manent or temporary,for use by construction traffic. l High Visibility Fencing (see BMP C103:High Visibility Fence (p.269))shall be installed,if necessary,to limit the access of vehicles to only those roads and park- ing areas that are stabilized. Design and Installation Specifications l On areas that will receive asphalt as part of the project,install the first lift as soon as possible. l A 6-inch depth of 2-to 4-inch crushed rock,gravel base,or crushed surfacing base course shall be applied immediately after grading or utility installation.A 4-inch course of asphalt treated base (ATB)may also be used,or the road/parking area may be paved.It may also be possible to use cement or calcium chloride for soil stabilization.If cement or cement kiln dust is used for roadbase stabilization,pH monitoring and BMPs (BMP C252:High pH Neutralization Using CO2 (p.409)and BMP C253:pH Control for High pH Water (p.412))are necessary to evaluate and minimize the effects on stormwater.If the area will not be used for permanent roads,parking areas,or structures,a 6-inch depth of hog fuel may also be used, but this is likely to require more maintenance.Whenever possible,construction roads and parking areas shall be placed on a firm,compacted subgrade. l Temporary road gradients shall not exceed 15 percent.Roadways shall be care- fully graded to drain.Drainage ditches shall be provided on each side of the road- way in the case of a crowned section,or on one side in the case of a super- elevated section.Drainage ditches shall be directed to a sediment control BMP. l Rather than relying on ditches,it may also be possible to grade the road so that run- off sheet-flows into a heavily vegetated area with a well-developed topsoil.Land- scaped areas are not adequate.If this area has at least 50 feet of vegetation that water can flow through,then it is generally preferable to use the vegetation to treat runoff,rather than a sediment pond or trap.The 50 feet shall not include wetlands or their buffers.If runoff is allowed to sheetflow through adjacent vegetated areas,it is vital to design the roadways and parking areas so that no concentrated runoff is created. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 277 l Storm drain inlets shall be protected to prevent sediment-laden water entering the storm drain system (see BMP C220:Storm Drain Inlet Protection (p.357)). Maintenance Standards Inspect stabilized areas regularly,especially after large storm events. 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 bet- ter to prevent 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 with straw 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 protection. l Mulch is required at all times for seeding because it protects seeds from heat,mois- ture loss,and transport due to runoff.Mulch can be applied on top of the seed or simultaneously by hydroseeding.See BMP C121:Mulching (p.284)for spe- cifications. l Seed and mulch,all disturbed areas not otherwise vegetated at final site sta- bilization.Final stabilization means the completion of all soil disturbing activities at the site and the establishment of a permanent vegetative cover,or equivalent per- 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 278 manent stabilization measures (such as pavement,riprap,gabions,or geotextiles) which will prevent erosion. Design and Installation Specifications Seed retention/detention ponds as required. 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 hydroseed.Before allowing water to flow in vegetated channels,establish 75 percent vegetation cover.If vegetated channels cannot be estab- lished by seed before water flow;install sod in the channel bottom—over hydromulch and erosion control 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 percent tackifier.See BMP C121:Mulching (p.284)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. l When installing seed via hydroseeding operations,only about 1/3 of the seed actu- ally 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: 1.Phase 1-Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift. 2.Phase 2-Install the rest of the mulch and tackifier over the first lift. Or,enhance vegetation by: 1.Installing the mulch,seed,fertilizer,and tackifier in one lift. 2.Spread or blow straw over the top of the hydromulch at a rate of 800-1000 pounds per acre. 3.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: 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 279 l Irrigation. l Reapplication of mulch. l Repair of failed slope surfaces. This technique works with standard hydromulch (1,500 pounds per acre minimum) and BFM/MBFMs (3,000 pounds per acre minimum). l Seed may be installed by hand if: l Temporary and covered by straw,mulch,or topsoil. l Permanent in small areas (usually less than 1 acre)and covered with mulch, topsoil,or erosion blankets. l The seed mixes listed in the tables below include recommended mixes for both temporary and permanent seeding. l Apply these mixes,with the exception of the wetland mix,at a rate of 120 pounds per acre.This rate can be reduced if soil amendments or slow- release fertilizers are used. l Consult the local suppliers or the local conservation district for their recom- mendations because the appropriate mix depends on a variety of factors, including location,exposure,soil type,slope,and expected foot traffic.Altern- ative seed mixes approved by the local authority may be used. l Other mixes may be appropriate,depending on the soil type and hydrology of the area. l Table II-4.1.2 Temporary Erosion Control Seed Mix (p.280)lists the standard mix for areas requiring a temporary vegetative cover. %Weight %Purity %Germination 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 Table II-4.1.2 Temporary Erosion Control Seed Mix l Table II-4.1.3 Landscaping Seed Mix (p.281)lists a recommended mix for land- scaping seed. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 280 %Weight %Purity %Germination Perennial rye blend Lolium perenne 70 98 90 Chewings and red fescue blend Festuca rubra var.commutata or Festuca rubra 30 98 90 Table II-4.1.3 Landscaping Seed Mix l Table II-4.1.4 Low-Growing Turf Seed Mix (p.281)lists a turf seed mix for dry situ- ations where there is no need for watering.This mix requires very little main- tenance. %Weight %Purity %Germination Dwarf tall fescue (several varieties) Festuca arundinacea 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 Table II-4.1.4 Low-Growing Turf Seed Mix l Table II-4.1.5 Bioswale Seed Mix*(p.281)lists a mix for bioswales and other inter- mittently wet areas. %Weight %Purity %Germination Tall or meadow fescue Festuca arundinacea or Festuca ela- tior 75-80 98 90 Seaside/Creeping bentgrass Agrostis palustris 10-15 92 85 Redtop bentgrass Agrostis alba or Agrostis gigantea 5-10 90 80 *Modified Briargreen,Inc.Hydroseeding Guide Wetlands Seed Mix Table II-4.1.5 Bioswale Seed Mix* l Table II-4.1.6 Wet Area Seed Mix*(p.282)lists a low-growing,relatively non-invas- ive seed mix appropriate for very wet areas that are not regulated wetlands.Apply 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 281 this mixture at a rate of 60 pounds per acre.Consult Hydraulic Permit Authority (HPA)for seed mixes if applicable. %Weight %Purity %Germination Tall or meadow fescue Festuca arundinacea or Festuca ela- tior 60-70 98 90 Seaside/Creeping bentgrass Agrostis palustris 10-15 98 85 Meadow foxtail Alepocurus pratensis 10-15 90 80 Alsike clover Trifolium hybridum 1-6 98 90 Redtop bentgrass Agrostis alba 1-6 92 85 *Modified Briargreen,Inc.Hydroseeding Guide Wetlands Seed Mix Table II-4.1.6 Wet Area Seed Mix* l Table II-4.1.7 Meadow Seed Mix (p.282)lists a recommended meadow seed mix for infrequently maintained areas or non-maintained areas where colonization by native plants is desirable.Likely applications include rural road and utility right-of- way.Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter months.Consider the appro- priateness of clover,a fairly invasive species,in the mix.Amending the soil can reduce the need for clover. %Weight %Purity %Germination Redtop or Oregon bentgrass Agrostis alba or Agrostis oregonensis 20 92 85 Red fescue Festuca rubra 70 98 90 White dutch clover Trifolium repens 10 98 90 Table II-4.1.7 Meadow Seed Mix l 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 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 282 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 prac- tical,initially rip the subgrade to improve long-term permeability,infiltration, and water inflow qualities.At a minimum,permanent areas shall use soil amendments to achieve organic matter and permeability performance 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. l 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 (including 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 fer- tilizer to the hydromulch machine,or agitate,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 fer- tilizers.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. l 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 of mulch with approximately 10 percent tackifier. Achieve a minimum of 95 percent soil coverage during application.Numer- ous products are available commercially.Installed products per man- ufacturer’s instructions.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. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 283 l BFMs and MBFMs provide good alternatives to blankets in most areas requir- ing vegetation establishment.Advantages over blankets include: l BFM and MBFMs do not require surface preparation. l Helicopters can assist in installing BFM and MBFMs in remote areas. l On slopes steeper than 2.5H:1V,blanket installers may require ropes and harnesses for safety. l Installing BFM and MBFMs can save at least $1,000 per acre com- pared to blankets. Maintenance Standards Reseed any seeded areas that fail to establish at least 80 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,or nets/blankets.If winter weather pre- vents adequate grass growth,this time limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. 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 runoff. Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C120:Tem- porary and Permanent Seeding.The products did not pass through the Technology Assessment Protocol –Ecology (TAPE)process.Local jurisdictions may choose not to accept this product approved as equivalent,or may require additional testing prior to con- sideration for local use.The products are available for review on Ecology’s website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html. BMP C121:Mulching Purpose Mulching soils provides immediate temporary protection from erosion.Mulch also enhances plant establishment by conserving moisture,holding fertilizer,seed,and top- soil in place,and moderating soil temperatures.There is an enormous 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: 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 284 BMP C123:Plastic Covering Purpose Plastic covering provides immediate,short-term erosion protection to slopes and dis- turbed 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.Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term (greater than six months)applications. 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 While plastic is inexpensive to purchase,the added cost of installation,main- tenance,removal,and disposal make this an expensive material,up to $1.50-2.00 per square yard. 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 covey 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: 1.Temporary ditch liner. 2.Pond liner in temporary sediment pond. 3.Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored. 4.Emergency slope protection during heavy rains. 5.Temporary drainpipe (“elephant trunk”)used to direct water. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 294 Design and Installation Specifications l Plastic slope cover must be installed as follows: 1.Run plastic up and down slope,not across slope. 2.Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet. 3.Minimum of 8-inch overlap at 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 imme- diately.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 pro- tection shall be installed at the toe of the slope in order to reduce the velocity of run- off. 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 ultra- violet radiation. l Completely remove plastic when no longer needed. l Dispose of old tires used to weight down plastic sheeting appropriately. Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C123:Plastic Covering.The products did not pass through the Technology Assessment Protocol – Ecology (TAPE)process.Local jurisdictions may choose not to accept this product approved as equivalent,or may require additional testing prior to consideration for local use.The products are available for review on Ecology’s website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 295 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 l In areas (including roadways)subject to surface and air movement of dust where on-site and 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 plant- ing,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 ori- ginal ground cover as long as practical. l Construct natural or artificial windbreaks or windscreens.These may be designed as enclosures for small dust sources. l Sprinkle the site with water until surface is wet.Repeat as needed.To prevent carryout of mud onto street,refer to BMP C105:Stabilized Construction Entrance / Exit (p.270). 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 pro- hibited from use as a dust suppressant.Local governments may approve other dust palliatives such as calcium chloride or PAM. l PAM (BMP C126:Polyacrylamide (PAM)for Soil Erosion Protection (p.300)) added to water at a rate of 0.5 lbs.per 1,000 gallons of water per acre and applied from a water truck is more effective than water alone.This is due to increased infilt- ration of water into the soil and reduced evaporation.In addition,small soil particles are bonded together and are not as easily transported by wind.Adding PAM may actually reduce the quantity of water needed for dust control.Use of PAM could be a cost-effective dust control method. Techniques that can be used for unpaved roads and lots include: 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 310 l Lower speed limits.High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. l Upgrade the road surface strength by improving particle size,shape,and mineral types that make up the surface and base materials. l 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. l Use geotextile fabrics to increase the strength of new roads or roads undergoing reconstruction. l Encourage the use of alternate,paved routes,if available. l Restrict use of paved roadways by tracked vehicles and heavy trucks to prevent damage to road surface and base. l 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. l Pave unpaved permanent roads and other trafficked areas. l Use vacuum street sweepers. l Remove mud and other dirt promptly so it does not dry and then turn into dust. l Limit dust-causing work on windy days. l Contact your local Air Pollution Control Authority for guidance and training on other dust control measures.Compliance with the local Air Pollution Control Authority constitutes compliance with this BMP. 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 unex- pected heavy summer rains.Having these materials on-site reduces the time needed to implement BMPs when inspections indicate that existing BMPs are not meeting the Con- struction SWPPP requirements.In addition,contractors can save money by buying some materials in bulk and storing them at their office or yard. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 311 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 pipe,sandbags,geotextile fab- ric and steel “T”posts. l Materials are stockpiled and readily available before any site clearing,grubbing,or earthwork begins.A large contractor or developer could keep a stockpile of mater- ials 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: Material Clear Plastic,6 mil Drainpipe,6 or 8 inch diameter Sandbags,filled Straw Bales for mulching, Quarry Spalls Washed Gravel Geotextile Fabric Catch Basin Inserts Steel "T" Posts Silt fence material 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 used as needed. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 312 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 discharge to surface waters of the State is prohibited.Use this BMP to minimize and eliminate concrete,concrete process water,and concrete slurry from entering waters of the state. Conditions of Use Any time concrete is used,utilize these management practices.Concrete construction projects include,but are not limited to,the following: l Curbs l Sidewalks l Roads l Bridges l Foundations l Floors l Runways Design and Installation Specifications l Assure that washout of concrete trucks,chutes,pumps,and internals is performed at an approved off-site location or in designated concrete washout areas.Do not wash out concrete trucks onto the ground,or into storm drains,open ditches, streets,or streams.Refer to BMP C154:Concrete Washout Area (p.317)for inform- ation on concrete washout areas. l 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 con- crete washout areas. l Wash off hand tools including,but not limited to,screeds,shovels,rakes,floats, and trowels into formed areas only. l Wash equipment difficult to move,such as concrete pavers in areas that do not dir- ectly drain to natural or constructed stormwater conveyances. l Do not allow washdown from areas,such as concrete aggregate driveways,to drain directly to natural or constructed stormwater conveyances. l Contain washwater and leftover product in a lined container when no formed areas 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 313 are available.Dispose of contained concrete in a manner that does not violate ground water or surface water quality standards. l Always use forms or solid barriers for concrete pours,such as pilings,within 15- feet of surface waters. l Refer to BMP C252:High pH Neutralization Using CO2 (p.409)and BMP C253: pH Control for High pH Water (p.412)for pH adjustment requirements. l Refer to the Construction Stormwater General Permit for pH monitoring require- ments if the project involves one of the following activities: l Significant concrete work (greater than 1,000 cubic yards poured concrete or recycled concrete used over the life of a project). l The use of engineered soils amended with (but not limited to)Portland cement-treated base,cement kiln dust or fly ash. l Discharging stormwater to segments of water bodies on the 303(d)list (Cat- egory 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 surface waters of the State is prohibited.Use this BMP to minimize and eliminate process water and slurry created through sawcutting or surfacing from entering waters of the State. Conditions of Use Utilize these management practices anytime sawcutting or surfacing operations take place.Sawcutting and surfacing operations include,but are not limited to,the following: l Sawing l Coring l Grinding l Roughening 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 314 l Hydro-demolition l Bridge and road surfacing 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 con- veyance including 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 surface water quality standards. l Do not allow process water generated during hydro-demolition,surface rough- ening or similar operations to drain to any natural or constructed drainage con- veyance including stormwater systems.Dispose process water in a manner that does not violate ground water or surface water quality standards. l Handle and dispose 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 stand- ards could occur,stop operations and immediately implement preventive measures such as berms,barriers,secondary containment,and 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 materials in a designated area,and install secondary con- tainment. Conditions of Use These procedures are suitable for use at all construction sites with delivery and storage of the following materials: 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 315 1.If the discharge velocity at the outlet is less than 5 fps (pipe slope less than 1 percent),use 2-inch to 8-inch riprap.Minimum thickness is 1-foot. 2.For 5 to 10 fps discharge velocity at the outlet (pipe slope less than 3 per- cent),use 24-inch to 48-inch riprap.Minimum thickness is 2 feet. 3.For outlets at the base of steep slope pipes (pipe slope greater than 10 per- cent),an engineered energy dissipater shall be used. l Filter fabric or erosion control blankets should always be used under riprap to pre- vent scour and channel erosion. l New pipe outfalls can provide an opportunity for low-cost fish habitat improve- ments.For example,an alcove of low-velocity water can be created by con- structing the pipe outfall and associated energy dissipater back from the stream edge and digging a channel,over-widened to the upstream side,from the outfall. Overwintering juvenile and migrating adult salmonids may use the alcove as shel- ter during high flows.Bank stabilization,bioengineering,and habitat features may be required for disturbed areas.This work may require a HPA.See Volume V (p.765)for more information on outfall system design. Maintenance Standards l Inspect and repair as needed. l Add rock as needed to maintain the intended function. l Clean energy dissipater if sediment builds up. BMP C220:Storm Drain Inlet Protection Purpose Storm drain inlet protection prevents coarse sediment from entering drainage systems prior to permanent stabilization of the disturbed area. Conditions of Use Use storm drain inlet protection at inlets that are operational before permanent sta- bilization of the disturbed drainage area.Provide protection for all storm drain inlets downslope and within 500 feet of a disturbed or construction area,unless conveying run- off entering catch basins to a sediment pond or trap. Also consider inlet protection for lawn and yard drains on new home construction.These small and numerous drains coupled with lack of gutters in new home construction 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 pre- 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 357 vent sediment from entering the system until completion of landscaping.Provide 18- inches of sod around each finished lawn and yard drain. Table II-4.2.2 Storm Drain Inlet Protection (p.358)lists several options for inlet protection. All of the methods for storm drain inlet protection tend to plug and require a high fre- quency of maintenance.Limit drainage areas to one acre or less.Possibly provide emer- gency overflows with additional end-of-pipe treatment where stormwater ponding would cause a hazard. Type of Inlet Protection Emergency Overflow Applicable for Paved/Earthen Surfaces Conditions of Use Drop Inlet Protection Excavated drop inlet protection Yes,tem- porary flood- ing will occur Earthen Applicable for heavy flows.Easy to maintain.Large area Require- ment:30'x30'/acre Block and gravel drop inlet protection Yes Paved or Earthen Applicable for heavy concentrated flows.Will not pond. Gravel and wire drop inlet pro- tection No Applicable for heavy concentrated flows.Will pond.Can withstand traffic. Catch basin fil- ters 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 installation. Block and gravel curb inlet protection Yes Paved Sturdy,but limited filtration. Culvert Inlet Protection Culvert inlet Sed- iment trap 18 month expected life. Table II-4.2.2 Storm Drain Inlet Protection Design and Installation Specifications Excavated Drop Inlet Protection -An excavated impoundment around the storm drain. Sediment settles out of the stormwater prior to entering the storm drain. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 358 l Provide a depth of 1-2 ft as measured from the crest of the inlet structure. l Slope sides of excavation no steeper than 2H:1V. l Minimum volume of excavation 35 cubic yards. l Shape basin to fit site with longest dimension oriented toward the longest inflow area. l Install provisions for draining to prevent standing water problems. l Clear the area of all debris. 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 pre- vent bypass flow. Block and Gravel Filter -A barrier formed around the storm drain inlet with standard con- crete blocks and gravel.See Figure II-4.2.8 Block and Gravel Filter (p.360). l Provide a height of 1 to 2 feet above inlet. l Recess the first row 2-inches into the ground for stability. l Support subsequent courses by placing a 2x4 through the block opening. l Do not use mortar. l Lay some blocks in the bottom row on their side for dewatering the pool. l Place hardware cloth or comparable wire mesh with ½-inch openings over all block openings. l Place gravel just below the top of blocks on slopes of 2H:1V or flatter. l An alternative design is a gravel donut. l Provide an inlet slope of 3H:1V. l Provide an outlet slope of 2H:1V. l Provide a1-foot wide level stone area between the structure and the inlet. l Use inlet slope stones 3 inches in diameter or larger. l Use gravel ½-to ¾-inch at a minimum thickness of 1-foot for the outlet slope. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 359 Figure II-4.2.8 Block and Gravel Filter D E P A R T M E N T O F E C O L O G Y S t a t e o f W a s h i n g t o n Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure II-4.2.8 Block and Gravel Filter Revised August 2015 NOT TO SCALE Plan View A A Section A-A Drain grate Concrete block Gravel backfill Less than5% slope Gravel backfill Concrete block Water Overflow water Drop inlet Ponding height Wire screen or filter fabric 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. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 360 Gravel and Wire Mesh Filter -A gravel barrier placed over the top of the inlet.This struc- ture does not provide an overflow. l Use a hardware cloth or comparable wire mesh with ½-inch openings. l Use coarse aggregate. l Provide a height 1-foot or more,18-inches wider than inlet on all sides. l Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot beyond each side of the inlet structure. l Overlap the strips if more than one strip of mesh is necessary. l Place coarse aggregate over the wire mesh. l Provide at least a 12-inch depth of gravel over the entire inlet opening and extend at least 18-inches on all sides. Catchbasin Filters –Use inserts designed by manufacturers for construction sites.The limited sediment storage capacity increases the amount of inspection and maintenance required,which may be daily for heavy sediment loads.To reduce maintenance require- ments combine a catchbasin 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. 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 catchbasin filter in the catchbasin just below the grating. Curb Inlet Protection with Wooden Weir –Barrier formed around a curb inlet with a wooden frame and gravel. 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 wire/fabric. l Place weight on frame anchors. Block and Gravel Curb Inlet Protection –Barrier formed around a curb inlet with concrete blocks and gravel.See Figure II-4.2.9 Block and Gravel Curb Inlet Protection (p.363). 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 361 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. Curb and Gutter Sediment Barrier –Sandbag or rock berm (riprap and aggregate)3 feet high and 3 feet wide in a horseshoe shape.See Figure II-4.2.10 Curb and Gutter Barrier (p.364). 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 outside of the berm sized to sediment trap standards for protecting a culvert inlet. Maintenance Standards l Inspect catch basin filters frequently,especially after storm events.Clean and replace clogged inserts.For systems with clogged stone filters:pull away the stones from the inlet and clean or replace.An alternative approach would be to use the clogged stone as fill and put fresh stone 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 appro- priate. Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C220:Storm Drain Inlet Protection.The products did not pass through the Technology Assessment Protocol –Ecology (TAPE)process.Local jurisdictions may choose not to accept this product approved as equivalent,or may require additional testing prior to consideration for local use.The products are available for review on Ecology’s website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 362 Figure II-4.2.9 Block and Gravel Curb Inlet Protection D E P A R T M E N T O F E C O L O G Y S t a t e o f W a s h i n g t o n Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure II-4.2.9 Block and Gravel Curb Inlet Protection Revised August 2015 NOT TO SCALE Plan View A A 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. Back of sidewalk Catch basin Back of curb Curb inlet Concrete block 2x4 Wood stud Concrete block34 inch (20 mm) Drain gravel Wire screen or filter fabric 3 4 inch (20 mm) Drain gravel Wire screen or filter fabric Ponding height Overflow 2x4 Wood stud (100x50 Timber stud) Concrete block Curb inlet Catch basin 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 363 Figure II-4.2.10 Curb and Gutter Barrier D E P A R T M E N T O F E C O L O G Y S t a t e o f W a s h i n g t o n Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure II-4.2.10 Curb and Gutter Barrier Revised September 2015 NOT TO SCALE Plan View Back of sidewalk Runoff Runoff Spillway Burlap sacks to overlap onto curb Gravel filled sandbags stacked tightly Curb inlet Catch basin Back of curb 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. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 364 BMP C232:Gravel Filter Berm Purpose A gravel filter berm is constructed on rights-of-way or traffic areas within a construction site to retain sediment by using a filter berm of gravel or crushed rock. Conditions of Use Where a temporary measure is needed to retain sediment from rights-of-way or in traffic areas on construction sites. Design and Installation Specifications l Berm material shall be ¾to 3 inches in size,washed well-grade gravel or crushed rock with less than 5 percent fines. l Spacing of berms: o Every 300 feet on slopes less than 5 percent o Every 200 feet on slopes between 5 percent and 10 percent o Every 100 feet on slopes greater than 10 percent l Berm dimensions: o 1 foot high with 3H:1V side slopes o 8 linear feet per 1 cfs runoff based on the 10-year,24-hour design storm Maintenance Standards l Regular inspection is required.Sediment shall be removed and filter material replaced as needed. BMP C233:Silt Fence Purpose Use of a 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.See Figure II-4.2.12 Silt Fence (p.369)for details on silt fence con- struction. Conditions of Use Silt fence may be used downslope of all disturbed areas. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 367 l Silt fence shall prevent soil carried by runoff water 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 sub- stantial amounts of overland flow.Convey any concentrated flows through the drainage system to a sediment pond. 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. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 368 Figure II-4.2.12 Silt Fence D E P A R T M E N T O F E C O L O G Y S t a t e o f W a s h i n g t o n Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure II-4.2.12 Silt Fence Revised October 2014 NOT TO SCALE Joints in filter fabric shall be spliced at posts. Use staples, wire rings or equivalent to attach fabric to posts 6' max Post spacing may be increased to 8' if wire backing is used 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used Minimum 4"x4" trench 2"x2" wood posts, steel fence posts, or equivalent 12" min 2' min 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used Filter fabric Minimum 4"x4" trench 2"x2" wood posts, steel fence posts, or equivalent Backfill trench with native soil or 3 4" - 1.5" washed gravel 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 369 Design and Installation Specifications l Use in combination with sediment basins or other BMPs. l Maximum slope steepness (normal (perpendicular)to fence line)1H:1V. l Maximum sheet or overland flow path length to the fence of 100 feet. l Do not allow flows greater than 0.5 cfs. l The geotextile used shall meet the following standards.All geotextile properties lis- ted 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-4.2.3 Geotextile Stand- ards (p.370)): 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-4.2.3 Geotextile Standards l Support standard strength fabrics with wire mesh,chicken wire,2-inch x 2-inch wire,safety fence,or jute mesh to increase the strength of the fabric.Silt fence materials are available that have synthetic mesh backing attached. l Filter fabric 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 last- ing,and can be left in place after the project is completed,if permitted by local reg- ulations. l Refer to Figure II-4.2.12 Silt Fence (p.369)for standard silt fence details.Include the following standard Notes for silt fence on construction plans and specifications: 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 370 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. 3.The silt fence shall have a 2-feet min.and a 2½-feet max.height above the original ground surface. 4.The filter fabric shall be sewn together at the point of manufacture to form fil- ter fabric lengths as required.Locate all sewn seams at support posts.Altern- atively,two sections of silt fence can be overlapped,provided the Contractor can demonstrate,to the satisfaction of the Engineer,that the overlap is long enough and that the adjacent fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. 5.Attach the filter fabric on the up-slope side of the posts and secure with staples,wire,or in accordance with the manufacturer's recommendations. Attach the filter fabric to the posts in a manner that reduces the potential for tearing. 6.Support the filter 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 filter fabric up-slope of the mesh. 7.Mesh support,if used,shall consist of steel wire with a maximum mesh spa- cing 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 ultra- violet radiation as the filter fabric it supports. 8.Bury the bottom of the filter fabric 4-inches min.below the ground surface. Backfill and tamp soil in place over the buried portion of the filter fabric,so that no flow can pass beneath the 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 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 prevent overturning of the fence due to sediment loading. 10.Use wood,steel or equivalent posts.The spacing of the support posts shall 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 371 be a maximum of 6-feet.Posts shall consist of either: l Wood with dimensions of 2-inches by 2-inches wide min.and a 3-feet min.length.Wood posts 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,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 gravel 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 Gravel check dams shall be approximately 1-foot deep at the back of the fence.Gravel 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 Gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls,or shoulder ballast.Gravel check dams shall be located every 10 feet along the fence where the fence must cross con- tours. l Refer to Figure II-4.2.13 Silt Fence Installation by Slicing Method (p.374)for slicing method details.Silt fence installation using the slicing method specifications: 1.The base of both end posts must be at least 2-to 4-inches above the top of the filter 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 install - ation. 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 filter fabric,enabling posts to support the filter fabric from upstream water pressure. 4.Install posts with the nipples facing away from the filter fabric. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 372 5.Attach the filter fabric to each post with three ties,all spaced within the top 8- inches of the filter fabric.Attach each tie diagonally 45 degrees through the fil- ter 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 fabric around the end posts and secure with 3 ties. 7.No more than 24-inches of a 36-inch filter fabric is allowed above ground level. Compact the soil immediately next to the filter 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 fabric deeper into the ground if necessary. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 373 Figure II-4.2.13 Silt Fence Installation by Slicing Method D E P A R T M E N T O F E C O L O G Y S t a t e o f W a s h i n g t o n Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure II-4.2.13 Silt Fence Installation by Slicing Method Revised November 2015 NOT TO SCALE Completed Installation Silt Fence Post installed after compaction Vibratory plow is not acceptable because of horizontal compaction Slicing blade (18 mm width) Horizontal chisel point (76 mm width) Fabric above ground 200 - 300mm Roll of silt fenceOperation No more than 24" of a 36" fabric is allowed above groundSteel support post100% compaction 100% compaction FLOW Drive over each side of silt fence 2 to 4 times with device exerting 60 p.s.i. or greater Attach fabric to upstream side of post Ponding height max. 24" POST SPACING: 7' max. on open runs 4' max. on pooling areas POST DEPTH: As much below ground as fabric above ground Top of Fabric Belt top 8" Diagonal attachment doubles strength Attachment Details: x Gather fabric at posts, if needed. x Utilize three ties per post, all within top 8" of fabric. x Position each tie diagonally, puncturing holes vertically a minimum of 1" apart. x Hang each tie on a post nipple and tighten securely. Use cable ties (50 lbs) or soft wire. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 374 Maintenance Standards l Repair any damage immediately. l Intercept and convey all evident concentrated flows uphill of the silt fence to a sed- iment pond. l Check the uphill side of the 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 or 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 filter 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 temporary 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 con- veyed through the drainage system to a sediment pond.The only circumstance in which overland flow can be treated solely by a strip,rather than by a sediment pond,is when the following criteria are met (see Table II-4.2.4 Contributing Drain- age Area for Vegetated Strips (p.375)): Average Contributing Area Slope Average Contributing Area Percent 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-4.2.4 Contributing Drainage Area for Vegetated Strips 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 375 Design and Installation Specifications l The vegetated strip shall consist of a minimum of a 25-foot flowpath length con- tinuous strip of dense vegetation with topsoil.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 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 imme- diately and protected 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 buffer,sur- face water controls must be installed to reduce the flows entering the buffer,or addi- tional perimeter protection must be installed. BMP C235:Wattles Purpose Wattles are temporary erosion and sediment control barriers consisting of straw,com- post,or other material that is wrapped in biodegradable tubular plastic or similar encas- ing material.They reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sediment.Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length.Wattles are placed in shallow trenches and staked along the contour of disturbed or newly constructed slopes.See Figure II-4.2.14 Wattles (p.378)for typical construction details.WSDOT Standard Plan I-30.30-00 also provides information on Wattles (http://www.wsdot.wa.gov/Design/Standards/Plans.htm#SectionI) Conditions of Use l Use wattles: l In disturbed areas that require immediate erosion protection. l On exposed soils during the period of short construction delays,or over winter months. l On slopes requiring stabilization until permanent vegetation can be estab- lished. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 376 l The material used dictates the effectiveness period of the wattle.Generally, Wattles are typically effective for one to two seasons. l Prevent rilling beneath wattles by properly entrenching and abutting wattles together to prevent water from passing between them. Design Criteria l Install wattles perpendicular to the flow direction and parallel to the slope contour. l Narrow trenches should be dug 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 compacted 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 abut tightly end to end.Do not over- lap the ends. 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 3/4 x 3/4 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 protruding above the wattle. Maintenance Standards l Wattles may require maintenance to ensure they are in contact with soil and thor- oughly entrenched,especially after significant rainfall on steep sandy soils. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 377 Figure II-4.2.14 Wattles D E P A R T M E N T O F E C O L O G Y S t a t e o f W a s h i n g t o n Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Figure II-4.2.14 Wattles Revised November 2015 NOT TO SCALE 3' - 4' (1.2m) Adjacent rolls shall tightly abut Straw rolls must be placed along slope contours Spacing depends on soil type and slope steepness 10' - 25' (3-8m) Sediment, organic matter, and native seeds are captured behind the rolls. Live Stake 1" x 1" Stake (25 x 25mm) 3" - 5" (75-125mm) 8" - 10" Dia. (200-250mm) NOTE: 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. 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 378 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 Equivalent Ecology has approved products as able to meet the requirements of BMP C235:Wattles. The products did not pass through the Technology Assessment Protocol –Ecology (TAPE)process.Local jurisdictions may choose not to accept this product approved as equivalent,or may require additional testing prior to consideration for local use.The products are available for review on Ecology’s website at http://www.ecy.wa.gov- /programs/wq/stormwater/newtech/equivalent.html BMP C236:Vegetative Filtration Purpose Vegetative Filtration may be used in conjunction with BMP C241:Temporary Sediment Pond (p.388),BMP C206:Level Spreader (p.348)and a pumping system with surface intake to improve turbidity levels of stormwater discharges by filtering 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 acre 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 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 area if standing water or erosion results. Design Criteria l Find land adjacent to the project that has a vegetated field,preferably a farm field, or wooded area. l If the project site does not contain enough vegetated field area consider obtaining 2014 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 379 Stormwater Pollution Prevention Plan 27 Appendix C – Alternative BMPs The following includes a list of possible alternative BMPs for each of the 12 elements not described in the main SWPPP text. This list can be referenced in the event a BMP for a specific element is not functioning as designed and an alternative BMP needs to be implemented. Element #1 - Mark Clearing Limits Element #2 - Establish Construction Access Element #3 - Control Flow Rates Element #4 - Install Sediment Controls Straw Bale Barrier (BMP C230) Straw Wattles (BMP C235) Storm Drain Inlet Protection (BMP C220) Advanced BMPs: Element #5 - Stabilize Soils Preserving Natural Vegetation (BMP C101) Element #6 - Protect Slopes Element #8 - Stabilize Channels and Outlets Channel Lining (BMP C202) Straw Wattles (BMP C235) Interceptor Dike and Swale (BMP C200) Element #10 - Control Dewatering Check Dams (BMP C207) Outlet Protection (BMP C209) Additional Advanced BMPs to Control Dewatering: Stormwater Pollution Prevention Plan 29 Appendix D – General Permit Stormwater Pollution Prevention Plan 30 Appendix E – Site Inspection Forms (and Site Log) The results of each inspection shall be summarized in an inspection report or checklist that is entered into or attached to the site log book. It is suggested that the inspection report or checklist be included in this appendix to keep monitoring and inspection information in one document, but this is optional. However, it is mandatory that this SWPPP and the site inspection forms be kept onsite at all times during construction, and that inspections be performed and documented as outlined below. At a minimum, each inspection report or checklist shall include: a. Inspection date/times b. Weather information: general conditions during inspection, approximate amount of precipitation since the last inspection, and approximate amount of precipitation within the last 24 hours. c. A summary or list of all BMPs that have been implemented, including observations of all erosion/sediment control structures or practices. d. The following shall be noted: i. locations of BMPs inspected, ii. locations of BMPs that need maintenance, iii. the reason maintenance is needed, iv. locations of BMPs that failed to operate as designed or intended, and v. locations where additional or different BMPs are needed, and the reason(s) why e. A description of stormwater discharged from the site. The presence of suspended sediment, turbid water, discoloration, and/or oil sheen shall be noted, as applicable. f. A description of any water quality monitoring performed during inspection, and the results of that monitoring. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. h. A statement that, in the judgment of the person conducting the site inspection, the site is either in compliance or out of compliance with the terms and conditions of the SWPPP and the NPDES permit. If the site inspection indicates that the site is out of compliance, the inspection report shall include a summary of the Stormwater Pollution Prevention Plan 31 remedial actions required to bring the site back into compliance, as well as a schedule of implementation. i. Name, title, and signature of person conducting the site inspection; and the following statement: “I certify under penalty of law that this report is true, accurate, and complete, to the best of my knowledge and belief”. When the site inspection indicates that the site is not in compliance with any terms and conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment, the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S5.F of the permit. Stormwater Pollution Prevention Plan 32 Site Inspection Form General Information Project Name: Inspector Name: Title: CESCL # : Date: Time: Inspection Type: □ After a rain event □ Weekly □ Turbidity/transparency benchmark exceedance □ Other Weather Precipitation Since last inspection In last 24 hours Description of General Site Conditions: Inspection of BMPs Element 1: Mark Clearing Limits BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 2: Establish Construction Access BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Stormwater Pollution Prevention Plan 33 Element 3: Control Flow Rates BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 4: Install Sediment Controls BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Stormwater Pollution Prevention Plan 34 Element 5: Stabilize Soils BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 6: Protect Slopes BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Stormwater Pollution Prevention Plan 35 Element 7: Protect Drain Inlets BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 8: Stabilize Channels and Outlets BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Stormwater Pollution Prevention Plan 36 Element 9: Control Pollutants BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 10: Control Dewatering BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Stormwater Pollution Prevention Plan 37 Stormwater Discharges From the Site Observed? Problem/Corrective Action Y N Location Turbidity Discoloration Sheen Location Turbidity Discoloration Sheen Stormwater Pollution Prevention Plan 38 Water Quality Monitoring Was any water quality monitoring conducted? □ Yes □ No If water quality monitoring was conducted, record results here: If water quality monitoring indicated turbidity 250 NTU or greater; or transparency 6 cm or less, was Ecology notified by phone within 24 hrs? □ Yes □ No If Ecology was notified, indicate the date, time, contact name and phone number below: Date: Time: Contact Name: Phone #: General Comments and Notes Include BMP repairs, maintenance, or installations made as a result of the inspection. Were Photos Taken? □ Yes □ No If photos taken, describe photos below: