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TECHNICAL INFORMATION REPORT FOR Parking Lot Upgrades at 600 SW 10th Street Renton, WA 98057 February 20, 2025 PREPARED FOR: TESLA 600 SW 10TH STREET RENTON, WA, 98057 PREPARED BY: KIMLEY-HORN 1201 3RD AVENUE, SUITE 2800 SEATTLE, WA 98101 OFFICE: (206) 607-2600 KHA PROJECT #: 194612001 ÓKimley-Horn and Associates, Inc., 2025 2/20/2025 Surface Water Enginering jfarah 05/05/2025 DEVELOPMENT ENGINEERING yqi 05/13/2025 (This sheet was intentionally left blank) Disclosure Statement: This document, together with the concepts and designs presented herein, as an instrument of service, is intended only for the specific purpose and client for which it was prepared. Reuse of and improper reliance on this document without written authorization and adaptation by Kimley-Horn and Associates, Inc. shall be without liability to Kimley-Horn and Associates, Inc. 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page i Table of Contents TECHNICAL INFORMATION REPORT WORKSHEET .............................................................................. iv SECTION A – PROJECT OVERVIEW ......................................................................................................... 1 A.1 SITE LOCATION ......................................................................................................................... 1 A.2 EXISTING SITE CONDITIONS ................................................................................................... 1 A.3 EXISTING ON-SITE STORMWATER SYSTEMS ....................................................................... 1 A.4 ADJACENT PROPERTIES .......................................................................................................... 1 A.5 PROJECT IMPACT ON ADJACENT AREAS .............................................................................. 1 A.6 PROPOSED SITE CONDITIONS ................................................................................................ 1 SECTION B – CORE REQUIREMENTS ...................................................................................................... 2 B.1 APPLICABLE CORE REQUIREMENTS ............................................................................................. 2 TABLE 1 – LAND DISTURBING ACTIVITY .......................................................................................... 2 CR#1: Discharge at the Natural Location .............................................................................................. 2 CR#2: Offsite Analysis ........................................................................................................................... 2 CR#3: Flow Control Facilities ................................................................................................................ 3 CR#4: Conveyance System ................................................................................................................... 3 CR#5: Construction Stormwater Pollution Prevention (CSWPP) .......................................................... 3 CR#6: Maintenance and Operations ..................................................................................................... 3 CR#7: Financial Guarantees and Liability ............................................................................................. 3 CR#8: Water Quality Facilities ............................................................................................................... 3 CR#9: On-Site BMPs ............................................................................................................................. 4 B.2 APPLICABLE SPECIAL REQUIREMENTS ........................................................................................ 4 SR#1: Other Adopted Area-Specific Requirements .............................................................................. 4 SR#2: Flood Hazard Area Delineation ................................................................................................... 4 SR#3: Flood Protection Facilities ........................................................................................................... 4 SR#4: Source Controls .......................................................................................................................... 4 SR#5: Oil Control ................................................................................................................................... 4 SR#6: Aquifer Protection Area ............................................................................................................... 4 SECTION C – PRELIMINARY SOILS EVALUATION .................................................................................. 5 SECTION D – OFFSITE ANALYSIS (CR#2) ................................................................................................ 5 Figure 1: Catch basin #1 along north side of SW 10th Street at the upstream end of the downstream storm system .......................................................................................................................................... 5 Figure 2: Catch basin #2 along south side of SW 10th Street at the upstream end of the downstream storm system .......................................................................................................................................... 6 Figure 3: Catch basin #3 along south side of SW 10th Street ............................................................... 7 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page ii Figure 4: Catch basin #4 along south side of SW 10th Street ............................................................... 7 Figure 5: Catch basin #5 along the curb at the NE corner of the intersection of SW 10th Street and Powell Avenue SW ................................................................................................................................ 8 Figure 6: Catch basin #6 along the curb at the SE corner of the intersection of SW 10th Street and Powell Avenue SW ................................................................................................................................ 8 Figure 7: Catch basin #7 along the west side of Powell Ave SW near the intersection of Powell Avenue SW and SW 10th Street ........................................................................................................... 9 Figure 8: Catch basin #8 along the west side of Powell Ave SW near the intersection of Powell Avenue SW and SW 10th Street ........................................................................................................... 9 Figure 9: Pipe daylight into ditch #1, with headwall slightly visible behind fallen tree ......................... 10 Figure 10: Ditch #1 as seen from the west looking east ...................................................................... 10 Figure 11: Culvert #1 daylight from the east looking west ................................................................... 11 Figure 12: Culvert #1 daylight from the west looking east ................................................................... 11 Figure 13: Ditch #2 from the east looking west ................................................................................... 11 Figure 14: Culvert #2 daylight from the east looking west, with headwall partially visible behind brush ............................................................................................................................................................. 12 SECTION E – FLOW CONTROL FACILITIES (CR#3) ............................................................................... 12 Figure 15 – Predeveloped and mitigated flow rates ............................................................................ 13 SECTION F – CONVEYANCE SYSTEM (CR#4) ....................................................................................... 13 SECTION G – WATER QUALITY FACILITIES (CR#8) .............................................................................. 14 Figure 16 – Water quality flow rate ...................................................................................................... 14 SECTION H – ON-SITE BMPS (CR#9) ...................................................................................................... 15 SECTION I – OTHER PERMITS ................................................................................................................ 16 SECTION J – OPERATIONS AND MAINTENANCE MANUAL (CR#6) ..................................................... 17 SECTION M – APPENDICES ..................................................................................................................... 18 APPENDIX A: MAPS ............................................................................................................................... 18 1. VICINITY MAP ........................................................................................................................... 18 2. FLOOD INSURANCE RATE MAP ............................................................................................. 19 3. PRE-DEVELOPMENT DRAINAGE AREA MAP ....................................................................... 20 4. POST-DEVELOPMENT DRAINAGE AREA MAP ..................................................................... 21 5. PROPOSED DRAINAGE PLAN ................................................................................................ 22 6. AQUIFER PROTECTION AREA MAP ...................................................................................... 23 7. DOWNSTREAM ANALYSIS STUDY AREA MAP ..................................................................... 24 APPENDIX B: CALCULATIONS ............................................................................................................. 25 1. FLOW CONTROL CALCULATIONS ......................................................................................... 25 2. CONVEYANCE SYSTEM CALCULATIONS ............................................................................. 26 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page iii 3. TEMPORARY EROSION AND SEDIMENT CONTROL CALCULATIONS .............................. 27 APPENDIX C: ADDITIONAL PLANS AND REPORTS ........................................................................... 28 1. GEOTECHNICAL ENGINEERING REPORT (FOR REFERENCE ONLY) ............................... 28 2. NRCS WEB SOIL SURVEY ...................................................................................................... 29 3. SWPPP ...................................................................................................................................... 30 APPENDIX D: OPERATIONS AND MAINTENANCE MANUAL ............................................................. 31 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page iv TECHNICAL INFORMATION REPORT WORKSHEET 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 1 SECTION A – PROJECT OVERVIEW A.1 SITE LOCATION The 10.01-acre site is located along SW 10th Street between Lind Ave SW and Thomas Ave SW, in the City of Renton, King County, Washington. The legal description of the site is as follows: Lot 5 of Earlington Industrial Park No. 1, according to plat recorded in Volume 83 of plats, page 10, in King County, Washington and the parcel number is 214600-0050. The site is also located in Flood Insurance Rate Map (FIRM) Map Number 53033C0976G, Panel 0976G. The site is not within the 100- or 500-year floodplain – see Appendix A for a map of floodplains around the site. A.2 EXISTING SITE CONDITIONS The site contains an existing warehouse of approximately 115,000 square feet. The site is bounded by SW 10th Street to the south, railroad easements to the west and east with existing industrial developments on the other side of both easements, and existing industrial developments to the north. Seneca Avenue SW splits the parcels adjacent to the site to the north and runs south to a dead end with a turnaround area approximately at the site’s north property line. The existing site is relatively flat, with a drop across the site of approximately 3 feet from the NE to SW corner. The portion of the site proposed to be improved contains some existing asphalt pavement in the SW corner, with the remainder of this area containing mostly hard-packed landscape. The existing site is approximately 39% impervious. Refer to Appendix A for a Pre-Development Drainage Area Map that includes additional information, including the 2-, 5-,10-, 25-, 50-, and 100- year predeveloped flows. A.3 EXISTING ON-SITE STORMWATER SYSTEMS There are existing drainage structures on-site that convey stormwater runoff to the public storm main in SW 10th Street. It can be assumed that all stormwater runoff is collected by these existing structures and carried off-site. Building roof downspouts are tight-lined and connected to existing structures. Refer to the Pre-Development Drainage Area Map in Appendix A for additional information. A.4 ADJACENT PROPERTIES The site is generally at the same elevation as the adjacent properties, and therefore does not convey any by-pass flow to the adjacent properties or street right-of-way. The general drainage patterns and directions will be maintained in the proposed post-development condition. Refer to the Drainage Area Maps in Appendix A for additional information. A.5 PROJECT IMPACT ON ADJACENT AREAS The stormwater design intent of the project is to produce minimal impact on the adjacent properties and public drainage system. The project will capture and manage on-site stormwater runoff as is feasible within the threshold discharge area and will ensure no runoff enters adjacent sites. Areas of the site that currently sheet flow to the street right-of-way are outside of the threshold discharge area and will continue to do so at similar rates of flow. See Section D for an Offsite Analysis of the downstream drainage infrastructure. A.6 PROPOSED SITE CONDITIONS The project will construct a parking lot around an existing industrial building on-site that is to remain, with associated landscaping and utility improvements. Site stormwater runoff will be captured on-site by new catch basins, conveyed to a corrugated metal pipe (CMP) detention system and Contech Filterra system 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 2 for treatment, then to the public storm main in SW 10th Street. The proposed project will disturb approximately 4.62 acres. The developed site is approximately 84% impervious. See Table 1 – Land Disturbing Activity below for additional information. Refer to Appendix A for a Post-Development Drainage Area Map that includes additional information, including the 2-, 5-, 10-, 25-, 50-, and 100- year developed flows. One curb ramp and minor sidewalk improvements are proposed to be installed south of the existing building, disturbance of the base course is not anticipated to the south of the existing building, and the pavement material will be replaced in-kind. SECTION B – CORE REQUIREMENTS B.1 APPLICABLE CORE REQUIREMENTS As the site has an existing impervious surface coverage of more than 35%, the proposed project is considered a redevelopment project. The project will create more than 2,000 square feet of hard surfaces and will disturb more than 7,000 square feet of land, and therefore the project is subject to Full Drainage Review per the 2022 City of Renton Surface Water Design Manual (SWDM) and must apply Core Requirements (CRs) #1 through #9 and Special Requirements (SRs) #1 through #6. See below for list of the Core and Special Requirements, the applicability of each to the project, and where additional information regarding compliance to each Core and Special Requirement may be found in this report. See Table 1 below for summary of Land Disturbing Activity for the project. TABLE 1 – LAND DISTURBING ACTIVITY EXISTING IMPERVIOUS SURFACE 1.79 AC NEW IMPERVIOUS SURFACE 3.90 AC TOTAL LAND DISTURBANCE 4.62 AC UNDISTURBED AREA 0.00 AC CR#1: Discharge at the Natural Location The project is required to adhere to CR#1, which states that, “All storm water runoff and surface water from a project must be discharged at the natural location so as not to be diverted onto or away from downstream properties. The manner in which stormwater runoff and surface water are discharged from the project site must not create a significant adverse impact to downhill properties or drainage facilities.” The existing site drainage patterns will be altered slightly to collect stormwater runoff in the post- developed condition. New on-site drainage structures will be installed to collect stormwater and convey it to the same public storm main in SW 10th Street as existing. No adverse impacts to downstream drainage facilities are anticipated – refer to Section D for an Offsite Analysis of the drainage facilities downstream of the site. CR#2: Offsite Analysis All proposed projects must adhere to CR#2, which states that “projects must submit an offsite analysis report that assesses potential offsite drainage and water quality impacts associated with development of the project site, and that proposes appropriate mitigation of those impacts.” The initial permit submittal includes a Level 1 downstream analysis as described in section 1.2.2.1 of the SWDM. The Level 1 downstream analysis is a qualitative survey of the downstream system, and involves defining and mapping the downstream study area, reviewing all available information on the study area, field inspecting the study area, and describing the drainage system and any existing/predicted drainage 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 3 and water quality problems. Refer to Section D of this report for additional information on how this project meets CR#2. CR#3: Flow Control Facilities As the project proposes more than 5,000 square feet of new plus replaced impervious surface, the project is required to adhere to CR#3, which states that, “All proposed projects, including redevelopment projects, must provide on-site flow control facilities to mitigate the impacts of storm and surface water runoff.” The flow control performance criteria are dependent on the results of the downstream analysis per Section 1.2.3.1 of the SWDM. Refer to Section E of this report for additional information on how this project meets CR#3. A pump system is proposed downstream of detention and the proposed flow control structure. This pump system has been sized to discharge stormwater at the same mitigated discharge rates as those from the flow control structure – see Section F for additional information on the pump system and Appendix B for pump sizing calculations. CR#4: Conveyance System The project is required to adhere to CR#4, which states that, “All engineered conveyance system elements for proposed projects must be analyzed, designed, and constructed to provide a minimum level of protection against overtopping, flooding, erosion, and structural failure.” For new systems, conveyance requirements are outlined in Section 1.2.4.1 of the SWDM. Refer to Section F of this report for additional information on how this project meets CR#4. CR#5: Construction Stormwater Pollution Prevention (CSWPP) The project shall comply with CR#5. Temporary erosion control plans will be developed for this project site complying with City of Renton and Washington State Department of Ecology requirements. As the site disturbance is greater than one acre in size, a Stormwater Pollution Prevention Plan (SWPPP) has been developed and included with this Final Stormwater Report. See Appendix C for the SWPPP. CR#6: Maintenance and Operations The project is required to adhere to CR#6, which states, “maintenance and operation of all drainage facilities is the responsibility of the applicant or property owner, except those facilities for which the City assumes maintenance and operation,” For industrial sites, maintenance and operation of flow control and water quality treatment facilities, including on-site BMPs, are the responsibility of the property owner. An Operations and Maintenance Manual has been prepared and provided with the Final Stormwater Report as part of the permit application for flow control and water quality facilities. See Appendix D of this report for the Operations and Maintenance Manual. CR#7: Financial Guarantees and Liability The project is required to adhere to CR#7, which states, “In accordance with Renton Municipal Code (RMC) 4-6-030, Community and Economic Development (CED) shall require all persons constructing any surface water facilities (including flow control/water quality facilities, conveyance systems, erosion control, and road drainage), to post with the City of Renton a bond, assignment of funds or certified check.” Provisions for the project to meet CR#7 shall be provided prior to final permit issuance. CR#8: Water Quality Facilities As a redevelopment project that proposes more than 5,000 square feet of new and replaced impervious surface, the project is required to adhere to CR#8, which states, “All proposed projects, including redevelopment projects, must provide water quality (WQ) facilities to treat the runoff from those new and 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 4 replaced pollution-generating impervious surfaces and new pollution-generating pervious surfaces targeted for treatment.” The project proposes to use a Contech Filterra System to treat stormwater runoff. Refer to Section G of this report for additional information on how this project meets CR#8. CR#9: On-Site BMPs The project proposes more than 2,000 square feet of new and replaced impervious surface and therefore must meet CR#9, which states that “All proposed projects, including redevelopment projects, must provide on-site BMPs to mitigate the impacts of storm and surface water runoff generated by new impervious surface, new pervious surface, existing impervious surfaces, and replaced impervious surface targeted for mitigation.” The project will apply on-site BMPs to supplement the flow mitigation provided by on-site flow control facilities. This project will apply BMPs to the maximum extent feasible using lists specific to the project location, size, and impervious coverage in compliance with Section 1.2.9.2.2 of the SWDM, Large Lot BMP Requirements. Refer to Section H of this report for additional information on how this project meets CR#9. B.2 APPLICABLE SPECIAL REQUIREMENTS SR#1: Other Adopted Area-Specific Requirements Copies of all adopted basin plans, Salmon Conservation Plans (SCPs), Hazard Mitigation Plans, and Lake Management Plans have been obtained from the City of Renton and reviewed for compliance in this report. SR#2: Flood Hazard Area Delineation The proposed project is not within or adjacent to a flood hazard area, so SR#2 is not applicable to the project. See Appendix A for the project site Flood Map. SR#3: Flood Protection Facilities The proposed project is not within or adjacent to a flood hazard area, so SR#2 is not applicable to the project. See Appendix A for the project site Flood Map. SR#4: Source Controls The project is required to adhere to SR#4, which states that, “When applicable per the Stormwater Pollution Prevention Manual, structural source control measures, such as car wash pads or dumpster area roofing, shall be applied to the entire site containing the proposed project, not just the project site.” The proposed project is for continued warehousing services, and therefore will have no known sources of pollution that will require treatment beyond the treatment required by CR#8. SR#5: Oil Control The project is required to adhere to SR#5, which states that, “Projects proposing to develop or redevelop a high-use site must provide oil controls in addition to any other water quality controls required by this manual.” This project is not a high use site, so SR#5 is not applicable. SR#6: Aquifer Protection Area The project site is not within an Aquifer Protection Area (APA), so SR#6 is not applicable to the project. Refer to Appendix A for the APA Map. 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 5 SECTION C – PRELIMINARY SOILS EVALUATION A Geotechnical Engineering Report, prepared by PanGeo, Inc., dated June 10, 2021 has been included with this report. Generally, the soils on site consist of a surficial layer of topsoil above two to four feet of fill soil overlying silt and clay. Refer to Appendix C for the report. SECTION D – OFFSITE ANALYSIS (CR#2) A Level 1 downstream analysis has been completed for the proposed project and has determined no existing drainage issues exist within the study area downstream of the site, and no predicted drainage or water quality issues will arise as part of the proposed project. Per the Section 1.2.2.1 of the SWDM, “the downstream analysis must consider the existing conveyance system(s) for a minimum flow path distance downstream of one-quarter mile and beyond that, as needed, to reach a point where the project site area constitutes less than 15% of the tributary area.” The distance from the project point of discharge to the public main in SW 10th Street to where the downstream system discharges to the receiving waterbody (Black River) is approximately 1,800 linear feet, or 0.35 miles, at which point the project site area constitutes less than 15% of the tributary area. This is the extent of the project downstream analysis – refer to Appendix A for a Downstream Analysis Study Area Map. Using the available City of Renton (COR) Maps and GIS Data, it was determined that there are no known drainage issues currently on file with COR or King County within the Downstream Analysis Study Area. A field inspection of the study area was also completed, and the condition of the existing drainage structures within the study area downstream of the project site are documented below. Refer to Appendix A for a Downstream Analysis Study Area Map for locations of structures documented below. Figure 1: Catch basin #1 along north side of SW 10th Street at the upstream end of the downstream storm system 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 6 Figure 2: Catch basin #2 along south side of SW 10th Street at the upstream end of the downstream storm system 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 7 Figure 3: Catch basin #3 along south side of SW 10th Street Figure 4: Catch basin #4 along south side of SW 10th Street 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 8 Figure 5: Catch basin #5 along the curb at the NE corner of the intersection of SW 10th Street and Powell Avenue SW Figure 6: Catch basin #6 along the curb at the SE corner of the intersection of SW 10th Street and Powell Avenue SW 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 9 Figure 7: Catch basin #7 along the west side of Powell Ave SW near the intersection of Powell Avenue SW and SW 10th Street Figure 8: Catch basin #8 along the west side of Powell Ave SW near the intersection of Powell Avenue SW and SW 10th Street 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 10 Figure 9: Pipe daylight into ditch #1, with headwall slightly visible behind fallen tree Figure 10: Ditch #1 as seen from the west looking east 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 11 Figure 11: Culvert #1 daylight from the east looking west Figure 12: Culvert #1 daylight from the west looking east Figure 13: Ditch #2 from the east looking west 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 12 Figure 14: Culvert #2 daylight from the east looking west, with headwall partially visible behind brush SECTION E – FLOW CONTROL FACILITIES (CR#3) Per Chapter 3, Hydrologic Analysis and Design, of the SWDM, WWHM2012 is an approved model for stormwater runoff and water quality design in the City of Renton. WWHM2012 was used to model a detention vault that meets the Peak Rate Flow Control Standard. A vault of approximately 24,000 cubic feet was selected as the appropriate size for a flow control facility. Refer to Appendix B for an WWHM2012 report containing preliminary calculations of the detention vault. Reference Section 15-A, City of Renton (COR) Flow Control Application Map, of the SWDM was used to determine that the project site is in a Peak Rate Flow Control Standard area – refer to Appendix A for a copy of the Flow Control Applications Map. The offsite analysis referenced in Section D of this report identified no issues downstream of the project site, so per Table 1.2.3.A of the SWDM, project flow control facilities must meet the Peak Rate Flow Control Standard, which matches the 2-, 10-, and 100- year peaks in the pre-developed and post-developed conditions within the threshold discharge area. The northern half of the existing building roof, which previously released unmitigated runoff to the parking lot, is now designed to drain to the proposed detention system to prevent any stormwater backup or ponding issues, and the detention system has been sized accordingly. Refer to Appendix A for Pre- and Post- Developed Drainage Area maps and a preliminary drainage plan. 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 13 Figure 15 – Predeveloped and mitigated flow rates SECTION F – CONVEYANCE SYSTEM (CR#4) Pump systems may be used to convey water from one location or elevation to another within the project site provided they meet the design criteria specified for such systems in Section 4.2.3 and will be privately owned and maintained. Pump systems discharging flows from the project site that would not have discharged by gravity flow under existing site conditions will require an approved adjustment to Core Requirement #1 (see Section 1.4, “Adjustment Process“). These pump systems will be considered only when there is no other physical gravity alternative and they are necessary to prevent creation or aggravation of a flooding or erosion problem as specified in Section 1.2.2. A pump system is proposed downstream of detention and the proposed flow control structure. This pump system has been sized to discharge stormwater at the same mitigated discharge rates as those from the flow control structure. The proposed pump system for the site meets the following requirements in section 4.2.3.1 of the SWDM: The pump system must be privately owned and maintained. The pump system will be privately owned and maintained. The pump system shall be used to convey water from one location or elevation to another within the site. The pump station’s inlet and outlet are both within the site. The pump system must have a dual pump (alternating) equipped with an external alarm system. The system is currently designed as a duplex system and alarm elevations will be set when a manufacturer has been selected. The pump system shall not be used to circumvent any other City drainage requirements, and construction and operation of the pump system shall not violate any other City requirements. The pump system shall follow all City drainage requirements and will not be used to circumvent any other requirements. Construction and operation of the pump system will follow all City requirements. 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 14 The gravity-flow components of the drainage system to and from the pump system must be designed so that pump failure does not result in flooding of a building or emergency access, or overflow to a location other than the natural discharge point for the site. In the event of a pump failure, overflow will happen to the natural discharge point for the site. The pump system shall have either installed emergency backup power or the ability for portable backup power generator in the event of a loss of primary power. If portable backup emergency power is provided, the appliance must include a description of how the backup power will be brought to the site during an emergency within an emergency response plan. In the event of a power outage, a building maintenance employee will connect the pump system to the backup power generator and turn the system on. Building maintenance employee will ensure proper operation of the pump system during emergency situations. The applicant must provide an emergency response plan that details how backup power will be activated during an emergency and include method for delivering to the site and energizing portable backup power. The emergency response plan must also describe response for pump failures including repair and replacement of damaged pumps/motors and generators. An emergency response plan will be submitted detailing the backup power plan as well as pump failure response. Per Section 1.2.4.1 of the SWDM, new stormwater pipe systems shall be designed to convey and contain the 25-year peak flow for the developed condition. Stormwater conveyance system sizing calculations were completed using Autodesk StormCAD, and calculations are included in Appendix B. SECTION G – WATER QUALITY FACILITIES (CR#8) As the project proposes new plus replaced pollution generating impervious surface (PGIS) in excess of 5,000 square feet, the project will be required to provide enhanced basic water quality treatment. On-site soils are not suitable for infiltration or treatment under CR#8. Therefore, a Contech Filterra System is proposed to be located downstream of on-site flow control facilities to treat the runoff generated on-site. The Contech Filterra system has attained a General Use Level Designation for Enhanced Treatment for the Washington Department of Ecology and therefore is suitable to satisfy CR#8. Per the Section 6.2.1 of the SWDM, for treatment installed downstream of detention, the water quality design flow rate is the full 2-year release rate from the detention facility. The proposed Filterra configuration can treat 324 in/hr through a media surface area of 9’x11.5’, which equates to approximately 0.776 cfs, enough to treat the full 2-year release rate. Refer to Figure 15 below for the full 2-year release rate as determined using WWHM2012. See Appendix B for WWHM2012 calculations for water quality and flow control. Figure 16 – Water quality flow rate 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 15 SECTION H – ON-SITE BMPS (CR#9) As the proposed project site is larger than 22,000 square feet, per Section 1.2.9.2.2 of the SWDM the project must apply on-site BMPs as specified in the requirements of that section and outlined below: Full Dispersion Per Section C.2.1.1 of Appendix C of the SWDM, “the total area of impervious surface being fully dispersed must be no more than 15% of the total area of native vegetated surface being preserved by a recorded tract, easement, or covenant on the site.” As the site improvements will consist primarily of impervious surface for parking that will need to be collected a managed on-site, there will not be enough native vegetation available, and full dispersion is not feasible. Full Infiltration Per Section C.2.2.2 of Appendix C of the SWDM, for full infiltration to be feasible and applicable to manage stormwater runoff from target surfaces, “existing soils must be coarse sands or cobbles or medium sands and cannot be comprised of fill materials where the infiltration device will be located.” Per an initial subsurface investigation completed by PanGeo, the site soils consist of fill overlying silt and clay, with a design infiltration rate of between 0.14 and 0.25 inches per hour. Therefore, full infiltration is not feasible. The geotechnical report prepared by PanGeo, Inc., and dated June 10, 2021 is available in Appendix C of this report. Limited Infiltration Per Section C.2.3.2 of Appendix C of the SWDM, “the minimum design requirements for limited infiltration are the same as those for full infiltration, except infiltration depressions are excluded and existing soils in the location of the infiltration device may be fine sands, loamy sands, sandy loams, or loams.” For the project, limited infiltration is not feasible given the existing soil conditions. Basic Dispersion Per Section C.2.4 of Appendix C of the SWDM, “basic dispersion is considered infeasible and not required for projects that cannot meet the minimum design requirements” list in Section C.2.4. The project proposes mostly new impervious surface and cannot meet the minimum vegetated flow path requirements for Basic Dispersion BMPs. Therefore, Basic Dispersion is not feasible. Farmland Dispersion This BMP does not apply to the City of Renton per Section C.2.5 of the SWDM. Bioretention Per Section C.2.6 of Appendix C of the SWDM, bioretention is infeasible “where the only area available for siting would threaten the safety or reliability of pre-existing underground utilities, pre-existing underground storage tanks, pre-existing structures, or pre-existing road or parking lot surfaces.” For the proposed parking, due to the flat nature of the site and the location of the existing storm drain tie-in on- site, the project will be unable to direct stormwater to the areas available for siting bioretention. Therefore, bioretention is not feasible. 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 16 Permeable Pavement Per Section C.2.7 of Appendix C of the SWDM, permeable pavement is infeasible “- this is contingent on Geotech report Rainwater Harvesting Per Section C.2.8 of Appendix C of the SWDM, “rainwater harvesting means the collection and storage of roof runoff for domestic or irrigation uses.” As there are no proposed modifications to the existing building and no proposed new structures as part of the project, rainwater harvesting is not applicable. Reduced Impervious Surface Credit The Reduced Impervious Surface Credit is not applicable to the project. Native Growth Retention Credit The Native Growth Retention Credit is not applicable to the project. Perforated Pipe Connection As the site soils are not conducive to infiltration, Perforated Pipe Connections that allow for infiltration of stormwater runoff are not applicable to the project. See Appendix C of this report for project geotechnical report. Rain Gardens Per Section C.2.12 of Appendix C of the SWDM, infeasibility criteria for rain gardens are the same as for bioretention. Therefore, rain gardens are not feasible. Soil Amendment Native soil retention and reuse will be used on-site to the maximum extent feasible. Tree Retention Credit Existing trees on-site will be protected and retained to the maximum extent feasible. There are no existing trees within the project limits of disturbance that are proposed to be removed. Vegetated Roofs As the project proposes to protect the existing building and make no building modifications, and does not propose any new structures, vegetated roof would not be feasible for the project. SECTION I – OTHER PERMITS 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 17 Construction of this project and its stormwater facilities will require the following additional permits: Construction Stormwater General Permit – Washington Department of Ecology (DOE) Status: Initial submittal to DOE complete SECTION J – OPERATIONS AND MAINTENANCE MANUAL (CR#6) An Operations and Maintenance Manual that addresses the maintenance and operation of all on-site drainage facilities has been prepared for the project and is included in Appendix D of this report. 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report February 20, 2025 Page 18 SECTION M – APPENDICES APPENDIX A: MAPS 1. VICINITY MAP FOUND MON. IN CASE,2' BRASS DISC W/ SCRIBED"X",0.7' BELOW GRADE AT ROADINTERSECTION OF SW 10THSTREET & LIND AVENUE SWFOUND MON. IN CASECONC. W/ BRASS TAG,0.5' BELOW GRADE AT ROADINTERSECTION OF SW 10TH STREETAND THOMAS AVENUE SWFOUND MON. IN CASE3" BRASS DISC, 0.4'BELOW GRADE W/NO PUNCHFOUND MON. IN CASE3" X 3" CONC MON. IN CASEW/ HOLE @ SOUTH END OFSENECA AVENUE SW, 0.5'BELOW GRADE RECORD MON.1/2" REBAR & CAPMARKED "CNI LS 18898"13 1824 19RECORDMON. IN CASEW/ COVERRECORDMON. IN CASE W/ BRASS NAIL INCONCRETE W/ PUNCH ATINTERSECTION OF SW 7TH ST. &LIND AVE. SWR=47.8'R=47.5'SURVEYED SITELOT 5PARCEL 214600-0050WAREHOUSETHOMAS AVENUE SWLIND AVENUE SWSW 10TH STREETSW 7TH STREET15.00'15.00'PARCEL214600-0030LOT 1PARCEL 214600-0041LOT 2PARCEL 214600-0040PARCEL214600-0010PARCEL 214600-0020 (SPUR TRACK)PARCEL 214600-0020 (SPUR TRACK)FOUNDREBAR & CAP"LS 38992"PUBLIC UTILITIESEASEMENTAFN 8511010604WATER MAINEASEMENTAFN 8410040587TELECOMMUNICATIONSFACILITY EASEMENTAFN 2000091300171515.0'15.0'15.0'15.0'21.4'31.2'600 SW 10TH STREETRENTON, WA 98057RYERSONLAND USE PERMITFORPROJECT RESOURCE LIST:NEIGHBORHOOD DETAIL MAPOWNEREV 600 LLC600 SW 10TH STREETRENTON, WA 98057CONTACT: MICHAEL STELLINOTEL: 786-528-5938EMAIL: mjs@Elionpartners.comENGINEERKIMLEY-HORN AND ASSOCIATES, INC.1000 2ND AVE, SUITE 3900SEATTLE, WA 98104TEL: (206) 607-2600CONTACT: SKY McCLAVEPROJECT MANAGERTEL: (206) 705-9767EMAIL: SKY.McCLAVE@KIMLEY-HORN.COMAERIAL OBTAINED FROM NEAR MAPSSITE ANALYSISAPPROXIMATE ACREAGE10.01±AC436,044±SFEXISTING ZONINGIM, INDUSTRIAL MEDIUMPROPOSED ZONINGIM, INDUSTRIAL MEDIUMEXISTING BUILDING AREA±114,531 SFFRONT SETBACK(SOUTH)BLDG: 15 FTPARKING: 15 FTSIDE SETBACK(EAST)BLDG: 0 FTPARKING: 0 FTSIDE SETBACK(WEST)BLDG: 0 FTPARKING: 0 FTREAR SETBACK(NORTH)BLDG: 0 FTPARKING: 0 FTPERCENTAGE OF LOT COVERAGE87AREA OF WORK (SF)167,489EXISTING LANDSCAPE AREA (SF)112,485PROPOSED LANDSCAPE AREA(SF)21,815EXISTING PARKING AREA (SF)55,656PROPOSED PARKING AREA (SF)146,183REQUIRED PARKING77 STALLS @ 1 STALL PER 1,500 SFPROVIDED PARKING196 STALLSPARKING STALL SIZE15 X 36.5 FTBICYCLE SPACESREQUIRED: 8PROVIDED: 8ADA PARKING SPACES (PROVIDEDPER ASSOCIATE PARKINGREQUIREMENTS)REQUIRED: 6PROVIDED: 6SHEET INDEXC0-00COVERSHEETPARKING LOT UPGRADESCONTROL DIAGRAMSW 10TH STSW GRADY WAYSENECA AVE WAY LIND AVE SW THOMAS AVE SW SW 12TH ST 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 19 2. FLOOD INSURANCE RATE MAP February 20, 2025 Site Location 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 20 3. PRE-DEVELOPMENT DRAINAGE AREA MAP February 20, 2025 DD W W S FOUND MON. IN CASE3" X 3" CONC MON. IN CASEW/ HOLE @ SOUTH END OFSENECA AVENUE SW, 0.5'BELOW GRADE 30' D-8826D-8827 T-8625 T-8621 P-8596 P-8604 P-8600 P-8620 D-8279 T-8608 T-8612 D-8357 D-8356 D-8355 D-8358 D-8190 D-8191 D-8207 D-8208 S-8591 W-8403 W-8404 W-8406 W-8405 W-8595 W-8593 W-8592 W-8590 W-8589 (6) POWER PAINT (3) POWER PAINT(2) COMM. FIBER PAINT(2) COMM. FIBER PAINTWAREHOUSE WAREHOUSE FOUND REBAR & CAP "LS 38992" DRAINAGE AREA = 5.83 AC 600 SW 10TH STREETPREPARED FOREV 600 LLCPRELIMINARY - NOT FOR CONSTRUCTIONNORTH PRE-DEVELOPMENTDRAINAGE AREA MAPA-1 LEGEND DRAINAGE DIVIDE DESIGN POINT PRE-DEVELOPED SITE HYDROLOGY PRE-DEVELOPED LANDUSE TOTALS: TOTAL PERVIOUS AREA: 2.83 TOTAL IMPERVIOUS AREA: 3.00 PERCENT IMPERVIOUS: ~51% FLOW FREQUENCY RETURN PERIODS AT DP: RETURN PERIOD:FLOW (CFS): 2 YEAR 1.3326 5 YEAR 1.7683 10 YEAR 2.0757 25 YEAR 2.4865 50 YEAR 2.8093 100 YEAR 3.1467 © 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 21 4. POST-DEVELOPMENT DRAINAGE AREA MAP February 20, 2025 D WCCOM PA CT COMPAC T COM PA CT COMPAC TWCNOPARKINGNOPARKINGNOPARKINGNOPARK ING NOPARK ING NOPARK ING NOPARKING NO PARKINGWCWCWCWCWCWCWCWCWC WCWCWCWCWCBFP W W LOT 5PARCEL 214600-0050EARLINGTON INDUSTRIAL PARK NO. 1 PARCEL 192305-9030 PARCEL 192305-9062 PARCEL 192305-9061 PARCEL 214600-0010 PARCEL214600-0020 30'30' 30' 40 ' D-8826D-8827 T-8625 T-8621 P-8596P-8604 P-8600 P-8620 D-8279 T-8608 T-8612 D-8357 D-8356 D-8355 D-8358 D-8190 D-8191 D-8207 D-8208 W-8403 W-8404 W-8406 W-8405 W-8595 W-8593 W-8592 (6) POWER PAINT (3) POWER PAINT(2) COMM. FIBER PAINTWAREHOUSE WAREHOUSE FOUND REBAR & CAP "LS 38992"LOT 5PARCEL 214600-0050EARLINGTON INDUSTRIAL PARK NO. 1 DRAINAGE AREA = 5.83 AC PRELIMINARY - NOT FOR CONSTRUCTIONPOST-DEVELOPMENTDRAINAGE AREA MAPA-2 NORTH 600 SW 10TH STREETPREPARED FOREV 600 LLCLEGEND DRAINAGE DIVIDE DESIGN POINT DEVELOPED SITE HYDROLOGY DEVELOPED LANDUSE TOTALS: TOTAL PERVIOUS AREA: 0.72 TOTAL IMPERVIOUS AREA: 5.11 PERCENT IMPERVIOUS: ~88% FLOW FREQUENCY RETURN PERIODS AT DP: RETURN PERIOD: FLOW (CFS): 2 YEAR 5 YEAR 10 YEAR 25 YEAR 50 YEAR 100 YEAR ©0.6862 0.9423 1.1436 1.4372 1.6865 1.9642 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 22 5. PROPOSED DRAINAGE PLAN February 20, 2025 D WCCOMPACTCOMPACTCOMPACTCOMPACTWCNOPARKINGNOPARKINGNOPARKINGNOPARKINGNOPARKINGNOPARKINGNOPARKINGNO PARKINGWCWCWCWCWCWCWCWCWC WCWCWCWCWCBFP IN COMPLIANCE WITH CITY OF RENTON STANDARDS 28 600 SW 10TH PARKING LOT 600 SW 10TH PARKING LOTPR23-000169LUA24-000157C24004706600 SW 10TH PARKING LOTTED-40-432702/21/2025 -4327 NORTH GRADING & STORM DRAIN PLAN 6 C-103 LEGEND PROPERTY LINE SW 10TH S T R E E T SENECA AVE SWC-103RIDGE LINE STORM DRAIN PIPE CATCH BASIN TYPE 1P CATCH BASIN TYPE 2 MANHOLE (REFER TO PLAN FOR TYPE) ACCESS HATCH (SEE SHEET C-507) CURB INLET PARKING LIGHTS SPOT ELEVATION ABBREVIATIONS EP EDGE OF PAVEMENT TC TOP OF CURB BC BACK OF CURB FL FLOW LINE LP LOW POINT HP HIGH POINT ME MATCH EXISTING CB CATCH BASIN LF LINEAR FEET CMP CORRUGATED METAL PIPE VALVE 1"=5' 1 BOX DETAIL C-103 06R 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 23 6. AQUIFER PROTECTION AREA MAP February 20, 2025 Esri, HERE, Garmin, (c) OpenStreetMap contributors, and the GIS usercommunity Zone 1 Zone 1 Modified Zone 2 Renton Water District ³ Data Sources: City of Renton, King County, ESRI 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. Coordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 FeetProjection: Lambert Conformal ConicDatum: North American 1983 HARN Date: 05/15/2020 0 0.5 10.25 Miles Site Location 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 24 7. DOWNSTREAM ANALYSIS STUDY AREA MAP February 20, 2025 4,514752 600 SW 10th St 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. THIS MAP IS NOT TO BE USED FOR NAVIGATIONWGS_1984_Web_Mercator_Auxiliary_Sphere Notes Downstream Analysis Study Area Map 06/08/2021 Legend 512 0 256 512 Feet Information Technology - GIS RentonMapSupport@Rentonwa.gov Network Structures Access Riser Inlet Manhole Utility Vault Clean Out Unknown Control Structure Pump Station Discharge Point Water Quality Detention Facilities Pond Tank Vault Bioswale Wetland Other Surface Water Main Culvert Open Drains Facility Outline Private Network Structures Access Riser Inlet Manhole Clean Out Utility Vault Unknown Private Control Structure Private Pump Station Private Discharge Point Private Water Quality Private Detention Facilities Tank, No Stormwater Wetland, No; Natural Wetland, No Filter Strip, No Infiltration Trench, No Vault, No Pond, No; Pond, Unknown Bioswale, No Stormtech Chamber, No Other, No Private Pipe Private Culvert Private Open Drains Private Facility Outline Fence Stormwater Ponds Facility Transfer Inactive Structure Inactive Pipe Inactive Water Quality Inactive Detention Facilities Drainage Complaints Known Drainage Issues Renton CB#1 CB#2 CB#3 CB#4 CB#5 CB#6 CB#7 CB#8 Ditch #1 Ditch #2 Culvert #1 Culvert #2 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 25 APPENDIX B: CALCULATIONS 1. FLOW CONTROL CALCULATIONS February 20, 2025 WWHM2012 PROJECT REPORT Tesla Renton_Storage Provided 2/12/2025 11:39:05 AM Page 2 General Model Information WWHM2012 Project Name:Tesla Renton_Storage Provided Site Name: Site Address: City: Report Date:2/12/2025 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2024/06/28 Version:4.3.1 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Tesla Renton_Storage Provided 2/12/2025 11:39:05 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 2.83 Pervious Total 2.83 Impervious Land Use acre PARKING FLAT 3 Impervious Total 3 Basin Total 5.83 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Tesla Renton_Storage Provided 2/12/2025 11:39:06 AM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.72 Pervious Total 0.72 Impervious Land Use acre PARKING FLAT 5.11 Impervious Total 5.11 Basin Total 5.83 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Contech CMP SSD Contech CMP SSD Tesla Renton_Storage Provided 2/12/2025 11:39:06 AM Page 5 Routing Elements Predeveloped Routing Tesla Renton_Storage Provided 2/12/2025 11:39:06 AM Page 6 Mitigated Routing Contech CMP SSD Depth:6 ft. Discharge Structure: 1 Riser Height:5 ft. Riser Diameter:18 in. Notch Type:Rectangular Notch Width:0.100 ft. Notch Height:2.250 ft. Orifice 1 Diameter:3.859 in.Elevation:0 ft. Element Outlets: Outlet 1 Outlet 2 Outlet Flows To: SSD Table Hydraulic Table Stage Area Volume Outlet (feet) (ac.) (ac-ft.) Struct NotUsed NotUsed NotUsed NotUsed 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.067 0.025 0.001 0.104 0.000 0.000 0.000 0.000 0.133 0.035 0.003 0.148 0.000 0.000 0.000 0.000 0.200 0.042 0.006 0.181 0.000 0.000 0.000 0.000 0.267 0.048 0.009 0.209 0.000 0.000 0.000 0.000 0.333 0.054 0.012 0.233 0.000 0.000 0.000 0.000 0.400 0.059 0.016 0.256 0.000 0.000 0.000 0.000 0.467 0.063 0.020 0.276 0.000 0.000 0.000 0.000 0.533 0.067 0.024 0.295 0.000 0.000 0.000 0.000 0.600 0.070 0.029 0.313 0.000 0.000 0.000 0.000 0.667 0.074 0.034 0.330 0.000 0.000 0.000 0.000 0.733 0.077 0.039 0.346 0.000 0.000 0.000 0.000 0.800 0.080 0.044 0.361 0.000 0.000 0.000 0.000 0.867 0.083 0.049 0.376 0.000 0.000 0.000 0.000 0.933 0.085 0.055 0.390 0.000 0.000 0.000 0.000 1.000 0.087 0.061 0.404 0.000 0.000 0.000 0.000 1.067 0.090 0.066 0.417 0.000 0.000 0.000 0.000 1.133 0.092 0.073 0.430 0.000 0.000 0.000 0.000 1.200 0.094 0.079 0.443 0.000 0.000 0.000 0.000 1.267 0.096 0.085 0.455 0.000 0.000 0.000 0.000 1.333 0.098 0.092 0.467 0.000 0.000 0.000 0.000 1.400 0.099 0.098 0.478 0.000 0.000 0.000 0.000 1.467 0.101 0.105 0.489 0.000 0.000 0.000 0.000 1.533 0.102 0.112 0.500 0.000 0.000 0.000 0.000 1.600 0.104 0.118 0.511 0.000 0.000 0.000 0.000 1.667 0.105 0.125 0.522 0.000 0.000 0.000 0.000 1.733 0.106 0.132 0.532 0.000 0.000 0.000 0.000 1.800 0.108 0.140 0.542 0.000 0.000 0.000 0.000 1.867 0.109 0.147 0.552 0.000 0.000 0.000 0.000 1.933 0.110 0.154 0.562 0.000 0.000 0.000 0.000 2.000 0.111 0.161 0.572 0.000 0.000 0.000 0.000 2.067 0.112 0.169 0.581 0.000 0.000 0.000 0.000 2.133 0.112 0.176 0.590 0.000 0.000 0.000 0.000 2.200 0.113 0.184 0.599 0.000 0.000 0.000 0.000 2.267 0.114 0.191 0.608 0.000 0.000 0.000 0.000 2.333 0.114 0.199 0.617 0.000 0.000 0.000 0.000 2.400 0.115 0.207 0.626 0.000 0.000 0.000 0.000 Tesla Renton_Storage Provided 2/12/2025 11:39:06 AM Page 7 2.467 0.115 0.214 0.635 0.000 0.000 0.000 0.000 2.533 0.116 0.222 0.643 0.000 0.000 0.000 0.000 2.600 0.116 0.230 0.652 0.000 0.000 0.000 0.000 2.667 0.117 0.237 0.660 0.000 0.000 0.000 0.000 2.733 0.117 0.245 0.668 0.000 0.000 0.000 0.000 2.800 0.117 0.253 0.680 0.000 0.000 0.000 0.000 2.867 0.117 0.261 0.697 0.000 0.000 0.000 0.000 2.933 0.117 0.269 0.717 0.000 0.000 0.000 0.000 3.000 0.117 0.277 0.739 0.000 0.000 0.000 0.000 3.067 0.117 0.284 0.763 0.000 0.000 0.000 0.000 3.133 0.117 0.292 0.788 0.000 0.000 0.000 0.000 3.200 0.117 0.300 0.814 0.000 0.000 0.000 0.000 3.267 0.117 0.308 0.841 0.000 0.000 0.000 0.000 3.333 0.117 0.316 0.869 0.000 0.000 0.000 0.000 3.400 0.116 0.323 0.897 0.000 0.000 0.000 0.000 3.467 0.116 0.331 0.926 0.000 0.000 0.000 0.000 3.533 0.115 0.339 0.954 0.000 0.000 0.000 0.000 3.600 0.115 0.346 0.983 0.000 0.000 0.000 0.000 3.667 0.114 0.354 1.013 0.000 0.000 0.000 0.000 3.733 0.114 0.362 1.042 0.000 0.000 0.000 0.000 3.800 0.113 0.369 1.074 0.000 0.000 0.000 0.000 3.867 0.112 0.377 1.109 0.000 0.000 0.000 0.000 3.933 0.112 0.384 1.144 0.000 0.000 0.000 0.000 4.000 0.111 0.392 1.181 0.000 0.000 0.000 0.000 4.067 0.110 0.399 1.217 0.000 0.000 0.000 0.000 4.133 0.109 0.406 1.255 0.000 0.000 0.000 0.000 4.200 0.108 0.413 1.422 0.000 0.000 0.000 0.000 4.267 0.106 0.421 1.470 0.000 0.000 0.000 0.000 4.333 0.105 0.428 1.519 0.000 0.000 0.000 0.000 4.400 0.104 0.435 1.569 0.000 0.000 0.000 0.000 4.467 0.102 0.442 1.620 0.000 0.000 0.000 0.000 4.533 0.101 0.448 1.671 0.000 0.000 0.000 0.000 4.600 0.099 0.455 1.723 0.000 0.000 0.000 0.000 4.667 0.098 0.462 1.776 0.000 0.000 0.000 0.000 4.733 0.096 0.468 1.830 0.000 0.000 0.000 0.000 4.800 0.094 0.474 1.884 0.000 0.000 0.000 0.000 4.867 0.092 0.480 1.940 0.000 0.000 0.000 0.000 4.933 0.090 0.487 1.996 0.000 0.000 0.000 0.000 5.000 0.087 0.492 2.052 0.000 0.000 0.000 0.000 5.067 0.085 0.498 2.332 0.000 0.000 0.000 0.000 5.133 0.083 0.504 2.836 0.000 0.000 0.000 0.000 5.200 0.080 0.509 3.475 0.000 0.000 0.000 0.000 5.267 0.077 0.514 4.200 0.000 0.000 0.000 0.000 5.333 0.074 0.519 4.965 0.000 0.000 0.000 0.000 5.400 0.070 0.524 5.720 0.000 0.000 0.000 0.000 5.467 0.067 0.529 6.420 0.000 0.000 0.000 0.000 5.533 0.063 0.533 7.024 0.000 0.000 0.000 0.000 5.600 0.059 0.537 7.506 0.000 0.000 0.000 0.000 5.667 0.054 0.541 7.865 0.000 0.000 0.000 0.000 5.733 0.048 0.544 8.130 0.000 0.000 0.000 0.000 5.800 0.042 0.547 8.460 0.000 0.000 0.000 0.000 5.867 0.035 0.550 8.725 0.000 0.000 0.000 0.000 5.933 0.025 0.552 8.979 0.000 0.000 0.000 0.000 6.000 0.000 0.553 9.225 0.000 0.000 0.000 0.000 Tesla Renton_Storage Provided 2/12/2025 11:39:06 AM Page 8 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:2.83 Total Impervious Area:3 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.72 Total Impervious Area:5.11 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 1.332605 5 year 1.768263 10 year 2.075691 25 year 2.486527 50 year 2.809293 100 year 3.146741 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.686159 5 year 0.94232 10 year 1.143635 25 year 1.437181 50 year 1.686531 100 year 1.964163 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 1.892 0.720 1950 1.752 0.648 1951 1.173 0.820 1952 0.855 0.559 1953 0.925 0.567 1954 1.083 0.555 1955 1.184 0.866 1956 1.177 0.634 1957 1.448 0.796 1958 1.050 0.639 Tesla Renton_Storage Provided 2/12/2025 11:45:00 AM Page 9 1959 0.971 0.575 1960 1.225 0.802 1961 1.203 0.562 1962 0.936 0.515 1963 1.166 0.509 1964 1.070 0.589 1965 1.520 0.567 1966 0.911 0.562 1967 1.767 0.764 1968 1.834 0.607 1969 1.378 0.631 1970 1.242 0.603 1971 1.484 0.583 1972 1.765 0.890 1973 0.801 0.589 1974 1.412 0.530 1975 1.471 0.841 1976 1.090 0.565 1977 1.033 0.545 1978 1.282 0.714 1979 1.681 0.568 1980 2.028 0.683 1981 1.358 0.629 1982 2.105 1.074 1983 1.474 0.697 1984 0.998 0.560 1985 1.369 0.632 1986 1.184 1.008 1987 1.685 1.001 1988 0.968 0.544 1989 1.211 0.501 1990 3.102 1.789 1991 2.293 1.360 1992 0.990 0.616 1993 0.804 0.518 1994 0.808 0.487 1995 1.187 0.614 1996 1.469 0.971 1997 1.370 0.993 1998 1.202 0.576 1999 2.834 0.842 2000 1.337 0.675 2001 1.296 0.550 2002 1.875 0.977 2003 1.458 0.562 2004 2.609 2.499 2005 1.204 0.875 2006 1.101 0.616 2007 2.790 1.720 2008 2.249 1.759 2009 1.486 0.857 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 3.1022 2.4988 2 2.8344 1.7885 3 2.7904 1.7589 Tesla Renton_Storage Provided 2/12/2025 11:45:00 AM Page 10 4 2.6092 1.7204 5 2.2929 1.3597 6 2.2494 1.0739 7 2.1047 1.0082 8 2.0278 1.0012 9 1.8920 0.9927 10 1.8748 0.9765 11 1.8342 0.9712 12 1.7672 0.8901 13 1.7648 0.8748 14 1.7518 0.8663 15 1.6855 0.8572 16 1.6809 0.8421 17 1.5203 0.8410 18 1.4862 0.8199 19 1.4836 0.8015 20 1.4737 0.7959 21 1.4708 0.7636 22 1.4690 0.7202 23 1.4578 0.7137 24 1.4476 0.6966 25 1.4117 0.6833 26 1.3785 0.6752 27 1.3699 0.6478 28 1.3689 0.6394 29 1.3584 0.6337 30 1.3373 0.6319 31 1.2964 0.6306 32 1.2819 0.6286 33 1.2418 0.6162 34 1.2253 0.6158 35 1.2107 0.6136 36 1.2035 0.6070 37 1.2034 0.6027 38 1.2024 0.5893 39 1.1870 0.5886 40 1.1841 0.5835 41 1.1837 0.5761 42 1.1771 0.5747 43 1.1733 0.5676 44 1.1655 0.5671 45 1.1015 0.5671 46 1.0898 0.5654 47 1.0826 0.5625 48 1.0699 0.5623 49 1.0502 0.5618 50 1.0329 0.5595 51 0.9983 0.5593 52 0.9896 0.5546 53 0.9708 0.5495 54 0.9680 0.5453 55 0.9363 0.5440 56 0.9245 0.5297 57 0.9110 0.5178 58 0.8545 0.5146 59 0.8077 0.5092 60 0.8037 0.5011 61 0.8008 0.4870 Tesla Renton_Storage Provided 2/12/2025 11:45:00 AM Page 11 Tesla Renton_Storage Provided 2/12/2025 11:45:00 AM Page 12 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.6663 1572 985 62 Pass 0.6879 1411 800 56 Pass 0.7096 1257 696 55 Pass 0.7312 1132 630 55 Pass 0.7529 1025 548 53 Pass 0.7745 914 483 52 Pass 0.7962 825 440 53 Pass 0.8178 747 396 53 Pass 0.8395 682 366 53 Pass 0.8611 625 332 53 Pass 0.8828 575 306 53 Pass 0.9044 522 278 53 Pass 0.9261 483 233 48 Pass 0.9477 447 203 45 Pass 0.9694 406 185 45 Pass 0.9910 377 163 43 Pass 1.0126 353 152 43 Pass 1.0343 330 142 43 Pass 1.0559 312 134 42 Pass 1.0776 289 126 43 Pass 1.0992 266 121 45 Pass 1.1209 252 117 46 Pass 1.1425 229 110 48 Pass 1.1642 214 105 49 Pass 1.1858 198 100 50 Pass 1.2075 181 95 52 Pass 1.2291 163 92 56 Pass 1.2508 156 89 57 Pass 1.2724 146 87 59 Pass 1.2940 136 84 61 Pass 1.3157 130 80 61 Pass 1.3373 123 79 64 Pass 1.3590 115 77 66 Pass 1.3806 107 72 67 Pass 1.4023 105 70 66 Pass 1.4239 101 70 69 Pass 1.4456 98 69 70 Pass 1.4672 89 66 74 Pass 1.4889 79 66 83 Pass 1.5105 78 60 76 Pass 1.5322 73 57 78 Pass 1.5538 71 53 74 Pass 1.5754 68 49 72 Pass 1.5971 64 45 70 Pass 1.6187 62 42 67 Pass 1.6404 59 39 66 Pass 1.6620 56 34 60 Pass 1.6837 53 33 62 Pass 1.7053 50 26 52 Pass 1.7270 47 20 42 Pass 1.7486 45 20 44 Pass 1.7703 40 17 42 Pass 1.7919 39 14 35 Pass Tesla Renton_Storage Provided 2/12/2025 11:45:01 AM Page 13 1.8136 34 12 35 Pass 1.8352 32 11 34 Pass 1.8569 32 11 34 Pass 1.8785 29 11 37 Pass 1.9001 28 10 35 Pass 1.9218 26 9 34 Pass 1.9434 24 8 33 Pass 1.9651 23 7 30 Pass 1.9867 23 6 26 Pass 2.0084 22 5 22 Pass 2.0300 20 5 25 Pass 2.0517 19 5 26 Pass 2.0733 18 5 27 Pass 2.0950 17 4 23 Pass 2.1166 15 4 26 Pass 2.1383 15 4 26 Pass 2.1599 15 4 26 Pass 2.1815 14 4 28 Pass 2.2032 14 3 21 Pass 2.2248 11 3 27 Pass 2.2465 11 3 27 Pass 2.2681 10 3 30 Pass 2.2898 9 3 33 Pass 2.3114 8 3 37 Pass 2.3331 7 3 42 Pass 2.3547 7 2 28 Pass 2.3764 7 2 28 Pass 2.3980 7 2 28 Pass 2.4197 7 2 28 Pass 2.4413 7 1 14 Pass 2.4630 7 1 14 Pass 2.4846 6 1 16 Pass 2.5062 5 0 0 Pass 2.5279 5 0 0 Pass 2.5495 5 0 0 Pass 2.5712 5 0 0 Pass 2.5928 5 0 0 Pass 2.6145 3 0 0 Pass 2.6361 3 0 0 Pass 2.6578 3 0 0 Pass 2.6794 3 0 0 Pass 2.7011 3 0 0 Pass 2.7227 3 0 0 Pass 2.7444 3 0 0 Pass 2.7660 3 0 0 Pass 2.7876 3 0 0 Pass 2.8093 2 0 0 Pass Tesla Renton_Storage Provided 2/12/2025 11:45:01 AM Page 14 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.3704 acre-feet On-line facility target flow:0.2534 cfs. Adjusted for 15 min:0.2534 cfs. Off-line facility target flow:0.1624 cfs. Adjusted for 15 min:0.1624 cfs. Tesla Renton_Storage Provided 2/12/2025 11:45:01 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. Tesla Renton_Storage Provided 2/12/2025 11:45:03 AM Page 16 Appendix Predeveloped Schematic Tesla Renton_Storage Provided 2/12/2025 11:45:53 AM Page 17 Mitigated Schematic Tesla Renton_Storage Provided 2/12/2025 11:46:31 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 Tesla Renton_Storage Provided.wdm MESSU 25 PreTesla Renton_Storage Provided.MES 27 PreTesla Renton_Storage Provided.L61 28 PreTesla Renton_Storage Provided.L62 30 POCTesla Renton_Storage Provided1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 11 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 *** 16 C, Lawn, Flat 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 *** 16 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 ********* 16 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO Tesla Renton_Storage Provided 2/12/2025 11:46:32 AM Page 19 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 16 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 16 0 4.5 0.03 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 16 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 16 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 16 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 *** 11 PARKING/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 11 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 11 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 *** 11 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 11 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 11 0 0 Tesla Renton_Storage Provided 2/12/2025 11:46:32 AM Page 20 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 11 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 16 2.83 COPY 501 12 PERLND 16 2.83 COPY 501 13 IMPLND 11 3 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 Tesla Renton_Storage Provided 2/12/2025 11:46:32 AM Page 21 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 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 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 Tesla Renton_Storage Provided 2/12/2025 11:46:32 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 Tesla Renton_Storage Provided.wdm MESSU 25 MitTesla Renton_Storage Provided.MES 27 MitTesla Renton_Storage Provided.L61 28 MitTesla Renton_Storage Provided.L62 30 POCTesla Renton_Storage Provided1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 11 RCHRES 1 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Contech CMP SSD 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 *** 16 C, Lawn, Flat 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 *** 16 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 ********* Tesla Renton_Storage Provided 2/12/2025 11:46:33 AM Page 23 16 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 16 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 16 0 4.5 0.03 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 16 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 16 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 16 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 *** 11 PARKING/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 11 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 11 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 *** 11 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 11 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** Tesla Renton_Storage Provided 2/12/2025 11:46:33 AM Page 24 # - # ***PETMAX PETMIN 11 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 11 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 16 0.72 RCHRES 1 2 PERLND 16 0.72 RCHRES 1 3 IMPLND 11 5.11 RCHRES 1 5 ******Routing****** PERLND 16 0.72 COPY 1 12 IMPLND 11 5.11 COPY 1 15 PERLND 16 0.72 COPY 1 13 RCHRES 1 1 COPY 501 16 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 *** 1 Contech CMP SSD 1 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 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 * * * * * * * * * * * * * * *** 1 0 1 0 0 4 0 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** Tesla Renton_Storage Provided 2/12/2025 11:46:33 AM Page 25 1 1 0.01 0.0 0.0 0.5 0.0 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 <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 91 4 Depth Area Volume Outflow1 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (ft/sec) (Minutes)*** 0.000000 0.000000 0.000000 0.000000 0.066667 0.024603 0.001096 0.104343 0.133333 0.034598 0.003089 0.147563 0.200000 0.042132 0.005656 0.180727 0.266667 0.048369 0.008678 0.208686 0.333333 0.053763 0.012087 0.233318 0.400000 0.058547 0.015833 0.255587 0.466667 0.062861 0.019883 0.276065 0.533333 0.066795 0.024206 0.295126 0.600000 0.070413 0.028782 0.313029 0.666667 0.073762 0.033589 0.329961 0.733333 0.076878 0.038611 0.346066 0.800000 0.079786 0.043835 0.361454 0.866667 0.082510 0.049245 0.376214 0.933333 0.085067 0.054832 0.390415 1.000000 0.087472 0.060584 0.404118 1.066667 0.089736 0.066492 0.417371 1.133333 0.091871 0.072546 0.430216 1.200000 0.093884 0.078739 0.442689 1.266667 0.095785 0.085062 0.454820 1.333333 0.097579 0.091508 0.466635 1.400000 0.099272 0.098070 0.478159 1.466667 0.100869 0.104742 0.489411 1.533333 0.102374 0.111517 0.500411 1.600000 0.103793 0.118390 0.511173 1.666667 0.105128 0.125354 0.521714 1.733333 0.106382 0.132405 0.532046 1.800000 0.107558 0.139537 0.542181 1.866667 0.108659 0.146744 0.552130 1.933333 0.109687 0.154023 0.561903 2.000000 0.110644 0.161368 0.571509 2.066667 0.111531 0.168774 0.580956 2.133333 0.112352 0.176237 0.590252 2.200000 0.113106 0.183753 0.599404 2.266667 0.113795 0.191316 0.608418 2.333333 0.114421 0.198924 0.617301 2.400000 0.114984 0.206571 0.626057 2.466667 0.115486 0.214254 0.634693 2.533333 0.115927 0.221968 0.643212 2.600000 0.116308 0.229709 0.651621 2.666667 0.116629 0.237474 0.659922 2.733333 0.116891 0.245259 0.668120 2.800000 0.117094 0.253058 0.679905 2.866667 0.117239 0.260870 0.697182 2.933333 0.117326 0.268689 0.717314 3.000000 0.117355 0.276512 0.739497 3.066667 0.117326 0.284335 0.763270 3.133333 0.117239 0.292154 0.788312 3.200000 0.117094 0.299966 0.814384 3.266667 0.116891 0.307766 0.841290 3.333333 0.116629 0.315550 0.868867 3.400000 0.116308 0.323315 0.896979 Tesla Renton_Storage Provided 2/12/2025 11:46:33 AM Page 26 3.466667 0.115927 0.331056 0.925501 3.533333 0.115486 0.338770 0.954326 3.600000 0.114984 0.346453 0.983356 3.666667 0.114421 0.354100 1.012502 3.733333 0.113795 0.361708 1.041680 3.800000 0.113106 0.369271 1.074399 3.866667 0.112352 0.376787 1.109006 3.933333 0.111531 0.384250 1.144394 4.000000 0.110644 0.391656 1.180541 4.066667 0.109687 0.399001 1.217427 4.133333 0.108659 0.406280 1.255032 4.200000 0.107558 0.413487 1.422483 4.266667 0.106382 0.420619 1.470483 4.333333 0.105128 0.427670 1.519353 4.400000 0.103793 0.434634 1.569075 4.466667 0.102374 0.441507 1.619633 4.533333 0.100869 0.448282 1.671008 4.600000 0.099272 0.454954 1.723186 4.666667 0.097579 0.461516 1.776154 4.733333 0.095785 0.467963 1.829896 4.800000 0.093884 0.474285 1.884400 4.866667 0.091871 0.480478 1.939655 4.933333 0.089736 0.486532 1.995646 5.000000 0.087472 0.492440 2.052366 5.066667 0.085067 0.498192 2.332068 5.133333 0.082510 0.503779 2.835797 5.200000 0.079786 0.509190 3.474725 5.266667 0.076878 0.514413 4.199977 5.333333 0.073762 0.519435 4.964516 5.400000 0.070413 0.524243 5.720017 5.466667 0.066795 0.528818 6.419625 5.533333 0.062861 0.533142 7.023533 5.600000 0.058547 0.537191 7.506269 5.666667 0.053763 0.540937 7.865220 5.733333 0.048369 0.544346 8.130354 5.800000 0.042132 0.547368 8.460484 5.866667 0.034598 0.549935 8.724883 5.933333 0.024603 0.551928 8.979469 6.000000 0.000000 0.553024 9.225281 END FTABLE 1 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*** RCHRES 1 HYDR RO 1 1 1 WDM 1004 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1005 STAG ENGL REPL 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 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL Tesla Renton_Storage Provided 2/12/2025 11:46:33 AM Page 27 END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 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 MASS-LINK 16 RCHRES ROFLOW COPY INPUT MEAN END MASS-LINK 16 END MASS-LINK END RUN Tesla Renton_Storage Provided 2/12/2025 11:46:34 AM Page 28 Predeveloped HSPF Message File Tesla Renton_Storage Provided 2/12/2025 11:46:34 AM Page 29 Mitigated HSPF Message File Tesla Renton_Storage Provided 2/12/2025 11:46:35 AM Page 30 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. 2005-2025; 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 Date:2/12/205 Project Name:Tesla Renton City / County:Renton / King State:Washington Designed By:CLH Company:Kimley-Horn =Adjustable Input Cells Telephone: Out-to-out length (ft): 137.0 Backfill Porosity (%): 0% System Diameter (in): 72 Out-to-out width (ft):51.0 Depth Above Pipe (in):0.0 Pipe Spacing (in):36 Number of Manifolds (ea):2.0 Depth Below Pipe (in):0.0 Incremental Analysis (in):2 Number of Barrels (ea):6.0 Width At Ends (ft):0.0 System Invert (Elevation):0 Width At Sides (ft):0.0 Depth (ft) Elevation (ft) Incremental Storage (cf) Cumulative Storage (cf) Incremental Storage (cf) Cumulative Storage (cf) Incremental Storage (cf) Cumulative Storage (cf) Percent Open Storage (%) Ave. Surface Area (sf) 0.00 0.00 0.0 0.0 0.0 0.0 0.0 0.0 0.0% 0.0 0.17 0.16 187.7 187.7 0.0 0.0 187.7 187.7 100.0% 1,680.2 0.33 0.33 338.8 526.5 0.0 0.0 338.8 526.5 100.0% 2,341.9 0.50 0.50 432.3 958.8 0.0 0.0 432.3 958.8 100.0% 2,825.8 0.67 0.66 504.3 1,463.1 0.0 0.0 504.3 1,463.1 100.0% 3,213.1 0.83 0.83 563.2 2,026.3 0.0 0.0 563.2 2,026.3 100.0% 3,535.8 1.00 1.00 612.8 2,639.1 0.0 0.0 612.8 2,639.1 100.0% 3,810.3 1.17 1.16 655.2 3,294.3 0.0 0.0 655.2 3,294.3 100.0% 4,046.4 1.33 1.33 691.8 3,986.1 0.0 0.0 691.8 3,986.1 100.0% 4,250.5 1.50 1.50 723.5 4,709.6 0.0 0.0 723.5 4,709.6 100.0% 4,427.1 1.67 1.66 750.9 5,460.4 0.0 0.0 750.9 5,460.4 100.0% 4,579.4 1.83 1.83 774.4 6,234.8 0.0 0.0 774.4 6,234.8 100.0% 4,709.6 2.00 2.00 794.4 7,029.2 0.0 0.0 794.4 7,029.2 100.0% 4,819.6 2.17 2.16 811.1 7,840.3 0.0 0.0 811.1 7,840.3 100.0% 4,910.8 2.33 2.33 824.8 8,665.1 0.0 0.0 824.8 8,665.1 100.0% 4,984.2 2.50 2.50 835.6 9,500.7 0.0 0.0 835.6 9,500.7 100.0% 5,040.5 2.67 2.66 843.6 10,344.4 0.0 0.0 843.6 10,344.4 100.0% 5,080.3 2.83 2.83 848.9 11,193.3 0.0 0.0 848.9 11,193.3 100.0% 5,104.1 3.00 3.00 851.6 12,044.9 0.0 0.0 851.6 12,044.9 100.0% 5,112.0 3.17 3.16 851.6 12,896.4 0.0 0.0 851.6 12,896.4 100.0% 5,104.1 3.33 3.33 848.9 13,745.4 0.0 0.0 848.9 13,745.4 100.0% 5,080.3 3.50 3.50 843.6 14,589.0 0.0 0.0 843.6 14,589.0 100.0% 5,040.5 3.67 3.66 835.6 15,424.6 0.0 0.0 835.6 15,424.6 100.0% 4,984.2 3.83 3.83 824.8 16,249.4 0.0 0.0 824.8 16,249.4 100.0% 4,910.8 4.00 4.00 811.1 17,060.6 0.0 0.0 811.1 17,060.6 100.0% 4,819.6 4.17 4.16 794.4 17,854.9 0.0 0.0 794.4 17,854.9 100.0% 4,709.6 4.33 4.33 774.4 18,629.3 0.0 0.0 774.4 18,629.3 100.0% 4,579.4 4.50 4.50 750.9 19,380.2 0.0 0.0 750.9 19,380.2 100.0% 4,427.1 4.67 4.66 723.5 20,103.7 0.0 0.0 723.5 20,103.7 100.0% 4,250.5 4.83 4.83 691.8 20,795.5 0.0 0.0 691.8 20,795.5 100.0% 4,046.4 5.00 5.00 655.2 21,450.7 0.0 0.0 655.2 21,450.7 100.0% 3,810.3 5.17 5.16 612.8 22,063.4 0.0 0.0 612.8 22,063.4 100.0% 3,535.8 5.33 5.33 563.2 22,626.6 0.0 0.0 563.2 22,626.6 100.0% 3,213.1 5.50 5.50 504.3 23,130.9 0.0 0.0 504.3 23,130.9 100.0% 2,825.8 5.67 5.66 432.3 23,563.2 0.0 0.0 432.3 23,563.2 100.0% 2,341.9 5.83 5.83 338.8 23,902.0 0.0 0.0 338.8 23,902.0 100.0% 1,680.2 6.00 6.00 187.7 24,089.7 0.0 0.0 187.7 24,089.7 100.0% 0.0 Pipe Stone Total SystemSystem Storage Volume Estimation Miscellaneous Contech Engineered Solutions, LLC is pleased to offer the following estimate of storage volume for the above named project. The results are submitted as an estimate only, without liability on the part of Contech Engineered Solutions, LLC for accuracy or suitability to any particular applicaton and are subject to verification of the Engineer of Record. This tool is only applicable for rectangular shaped systems. CMP: Underground Detention System Storage Volume Estimation Summary of Inputs Pipe & Analysis InformationSystem Information Backfill Information These results are submitted to you as a guideline only, without liability on the part of CONTECH Engineered Solutions, LLC for accuracy or suitability to any particular application, and are subject to your verification. 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 26 2. CONVEYANCE SYSTEM CALCULATIONS February 20, 2025 5DWCWCWCWCWCWCWCWCWCWCWCWCWCWCWCWCCB: 01AREA: 0.83CB: 02AREA: 0.68 ACCB: 03AREA: 0.40 ACCB: 04AREA: 0.71 ACCB: 08AREA: 0.54 ACCB: 07AREA: 0.50 ACCB: 06AREA: 0.39 ACCB: 05AREA: 0.58 ACCB: 10AREA: 0.03 ACAREA: 0.30 ACAREA: 0.32 ACAREA: 0.30 ACAREA: 0.15 ACAREA: 0.15 ACLEGENDTRIBUTARY AREAEXISTING PROPERTY LINESTORM MAINEXISTING CONTOURPROPOSED CONTOURSTORM CATCH BASINSTORM MANHOLENORTHPRELIMINARY - NOT FOR CONSTRUCTION POST-DEVELOPMENT DRAINAGE AREA MAP 600 SW 10TH STREET PREPARED FOR EV 600 LLC ©A-3 5.00 10.00 15.00 20.00 25.00 -0+50 0+00 0+50 1+00 1+50 2+00 Station (ft)Elevation(ft)19 (oPIPE-STRM)Rim: 21.97 ft Invert: 19.07 ft 15 (oPIPE-STRM) Rim: 22.42 ft Invert: 13.44 ft 51 (oPIPE-STRM) Rim: 22.50 ft Invert: 19.17 ft 14 (oPIPE-STRM) Rim: 23.11 ft Invert: 13.29 ft 52 (oPIPE-STRM) Rim: 23.21 ft Invert: 9.98 ft 78 (oPIPE-STRM) Invert: 10.04 ft 13 (oPIPE-STRM) Invert: 13.24 ft 16 (oPIPE-STRM) Invert: 13.44 ft O-1 Rim: 23.00 ft Invert: 18.00 ft Page 1 of 376 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 9/19/2024 StormCAD [10.04.00.158] Bentley Systems, Inc. Haestad Methods Solution CenterRenton TESLA-01.stsw 25 - YEAR STORM Profile Report Engineering Profile - POND (2025-02-12_Renton TESLA-01.stsw) 10.00 15.00 20.00 25.00 -0+50 0+00 0+50 1+00 1+50 2+00 Station (ft)Elevation(ft)MH-01 (oPIPE-STRM) Rim: 21.86 ft Invert: 15.60 ft MH-03 (oPIPE-STRM) Rim: 23.11 ft Invert: 13.29 ft MW-1 (oPIPE-STRM) Rim: 23.00 ft Invert: 13.24 ft V-1 (oPIPE-STRM) Rim: 23.00 ft Invert: 15.58 ft DET PIPE MH-02 (oPIPE-STRM) Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 2/12/2025 StormCAD [10.04.00.158]Bentley Systems, Inc. Haestad Methods Solution Center2025-02-12_Renton TESLA-01.stsw 25 - YEAR STORM Profile Report Engineering Profile - MAIN (2025-02-12_Renton TESLA-01.stsw) 15.00 20.00 25.00 -0+50 0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50 4+00 4+50 5+00 5+50 Station (ft)Elevation(ft)MH-01 (oPIPE-STRM) Rim: 21.86 ft Invert: 15.60 ft CB-11 (oPIPE-STRM)Rim: 21.97 ftInvert: 16.67 ft CB-12 (oPIPE-STRM)Rim: 22.12 ft Invert: 15.64 ft CB-09 (oPIPE-STRM)Rim: 22.33 ft Invert: 18.31 ft CB-10 (oPIPE-STRM)Rim: 22.36 ftInvert: 17.24 ft V-1 (oPIPE-STRM)Rim: 23.00 ft Invert: 15.58 ft Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 2/12/2025 StormCAD [10.04.00.158]Bentley Systems, Inc. Haestad Methods Solution Center2025-02-12_Renton TESLA-01.stsw 25 - YEAR STORM Profile Report Engineering Profile - ROOF LEADERS (2025-02-12_Renton TESLA-01.stsw) 15.00 20.00 25.00 -0+50 0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50 4+00 4+50 5+00 5+50 6+00 Station (ft)Elevation(ft)CB-13 (oPIPE-STRM)Rim: 21.55 ftInvert: 15.92 ftCB-15 (oPIPE-STRM)Rim: 21.68 ftInvert: 17.01 ft MH-01 (oPIPE-STRM)Rim: 21.86 ftInvert: 15.60 ft CB-17 (oPIPE-STRM)Rim: 21.95 ft Invert: 18.50 ft CB-14 (oPIPE-STRM)Rim: 21.98 ftInvert: 16.31 ft CB-16 (oPIPE-STRM)Rim: 22.04 ftInvert: 17.79 ft Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 2/12/2025 StormCAD [10.04.00.158]Bentley Systems, Inc. Haestad Methods Solution Center2025-02-12_Renton TESLA-01.stsw 25 - YEAR STORM Conduit FlexTable: 25-Year Storm Flow / Capacity (Design) (%) Hydraulic Grade Line (In) (ft) Hydraulic Grade Line (Out) (ft) Elevation Ground (Stop) (ft) Elevation Ground (Start) (ft) Velocity (ft/s) Flow (cfs) Slope (Calculated) (ft/ft) Diameter (in) Stop NodeStart Node 38.719.4318.520.0021.972.660.600.00510.0OUTFALLMH-05 (oPIPE-STRM) 26.613.8213.7723.0023.113.551.970.00518.0MW-1 (oPIPE- STRM) MH-03 (oPIPE- STRM) 26.613.9713.8223.1122.423.551.970.00518.0MH-03 (oPIPE-STRM)MH-02 (oPIPE-STRM) 83.719.2218.8221.9722.363.506.190.00518.0CB-11 (oPIPE- STRM) CB-10 (oPIPE- STRM) 48.719.4419.2222.3622.334.163.600.00518.0CB-10 (oPIPE- STRM) CB-09 (oPIPE- STRM) 57.119.3119.2222.3621.631.831.440.00512.0CB-10 (oPIPE-STRM)CB-07 (oPIPE-STRM) 45.919.2719.2222.3621.331.471.150.00512.0CB-10 (oPIPE- STRM) CB-03 (oPIPE- STRM) 61.719.5419.4422.3321.633.371.550.00512.0CB-09 (oPIPE-STRM)CB-08 (oPIPE-STRM) 81.519.5819.4422.3321.192.602.040.00512.0CB-09 (oPIPE- STRM) CB-04 (oPIPE- STRM) 83.318.4718.4521.8622.124.2413.330.00524.0MH-01 (oPIPE- STRM) CB-12 (oPIPE- STRM) 48.918.5918.4722.1221.112.131.670.00912.0CB-12 (oPIPE-STRM)CB-05 (oPIPE-STRM) 94.918.8818.4722.1220.153.042.390.00512.0CB-12 (oPIPE- STRM) CB-01 (oPIPE- STRM) 58.218.8218.4722.1221.972.959.270.00524.0CB-12 (oPIPE-STRM)CB-11 (oPIPE-STRM) 28.618.7918.7521.6822.043.632.120.00518.0CB-15 (oPIPE- STRM) CB-16 (oPIPE- STRM) 43.518.9618.7922.0421.953.101.100.00512.0CB-16 (oPIPE- STRM) CB-17 (oPIPE- STRM) 129.619.7918.7922.0423.005.241.030.0206.0CB-16 (oPIPE-STRM)RL-3 (oPIPE-STRM) 49.418.6218.5221.5521.982.083.670.00518.0CB-13 (oPIPE- STRM) CB-14 (oPIPE- STRM) 42.518.7518.6221.9821.681.783.150.00518.0CB-14 (oPIPE-STRM)CB-15 (oPIPE-STRM) 64.818.8318.6221.9823.002.620.510.0206.0CB-14 (oPIPE- STRM) RL-1 (oPIPE- STRM) 44.818.8718.8221.9721.071.431.120.00512.0CB-11 (oPIPE- STRM) CB-06 (oPIPE- STRM) 78.119.1018.8221.9720.512.491.960.00512.0CB-11 (oPIPE-STRM)CB-02 (oPIPE-STRM) 64.720.2219.3621.9723.004.300.510.0206.0MH-05 (oPIPE- STRM) RL-5 (oPIPE- STRM) 138.220.1318.9821.9523.005.591.100.0206.0CB-17 (oPIPE-STRM)RL-4 (oPIPE-STRM) 56.218.4518.4423.0021.863.4617.000.00530.0V-1 (oPIPE- STRM) MH-01 (oPIPE- STRM) 49.418.5218.4521.8621.552.083.670.00518.0MH-01 (oPIPE- STRM) CB-13 (oPIPE- STRM) 129.619.5818.7521.6823.005.241.030.0206.0CB-15 (oPIPE-STRM)RL-2 (oPIPE-STRM) Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 2/12/2025 StormCAD [10.04.00.158]Bentley Systems, Inc. Haestad Methods Solution Center2025-02-12_Renton TESLA-01.stsw 5.00 10.00 15.00 20.00 25.00 -0+50 0+00 0+50 1+00 1+50 2+00 Station (ft)Elevation(ft)19 (oPIPE-STRM)Rim: 21.97 ft Invert: 19.07 ft 15 (oPIPE-STRM) Rim: 22.42 ft Invert: 13.44 ft 51 (oPIPE-STRM) Rim: 22.50 ft Invert: 19.17 ft 14 (oPIPE-STRM) Rim: 23.11 ft Invert: 13.29 ft 52 (oPIPE-STRM) Rim: 23.21 ft Invert: 9.98 ft 78 (oPIPE-STRM) Invert: 10.04 ft 13 (oPIPE-STRM) Invert: 13.24 ft 16 (oPIPE-STRM) Invert: 13.44 ft O-1 Rim: 23.00 ft Invert: 18.00 ft Page 1 of 376 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 9/19/2024 StormCAD [10.04.00.158] Bentley Systems, Inc. Haestad Methods Solution CenterRenton TESLA-01.stsw 100 - YEAR STORM Profile Report Engineering Profile - POND (2025-02-12_Renton TESLA-01.stsw) 10.00 15.00 20.00 25.00 -0+50 0+00 0+50 1+00 1+50 2+00 Station (ft)Elevation(ft)MH-01 (oPIPE-STRM) Rim: 21.86 ft Invert: 15.60 ft MH-03 (oPIPE-STRM) Rim: 23.11 ft Invert: 13.29 ft MW-1 (oPIPE-STRM) Rim: 23.00 ft Invert: 13.24 ft V-1 (oPIPE-STRM) Rim: 23.00 ft Invert: 15.58 ft DET PIPE MH-02 (oPIPE-STRM) Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 2/12/2025 StormCAD [10.04.00.158]Bentley Systems, Inc. Haestad Methods Solution Center2025-02-12_Renton TESLA-01.stsw 100 - YEAR STORM Profile Report Engineering Profile - MAIN (2025-02-12_Renton TESLA-01.stsw) 15.00 20.00 25.00 -0+50 0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50 4+00 4+50 5+00 5+50 Station (ft)Elevation(ft)MH-01 (oPIPE-STRM) Rim: 21.86 ft Invert: 15.60 ft CB-11 (oPIPE-STRM)Rim: 21.97 ftInvert: 16.67 ft CB-12 (oPIPE-STRM)Rim: 22.12 ft Invert: 15.64 ft CB-09 (oPIPE-STRM)Rim: 22.33 ft Invert: 18.31 ft CB-10 (oPIPE-STRM)Rim: 22.36 ftInvert: 17.24 ft V-1 (oPIPE-STRM)Rim: 23.00 ft Invert: 15.58 ft Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 2/12/2025 StormCAD [10.04.00.158]Bentley Systems, Inc. Haestad Methods Solution Center2025-02-12_Renton TESLA-01.stsw 100 - YEAR STORM Profile Report Engineering Profile - ROOF LEADERS (2025-02-12_Renton TESLA-01.stsw) 15.00 20.00 25.00 -0+50 0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50 4+00 4+50 5+00 5+50 6+00 Station (ft)Elevation(ft)CB-13 (oPIPE-STRM)Rim: 21.55 ftInvert: 15.92 ftCB-15 (oPIPE-STRM)Rim: 21.68 ftInvert: 17.01 ft MH-01 (oPIPE-STRM)Rim: 21.86 ftInvert: 15.60 ft CB-17 (oPIPE-STRM)Rim: 21.95 ft Invert: 18.50 ft CB-14 (oPIPE-STRM)Rim: 21.98 ftInvert: 16.31 ft CB-16 (oPIPE-STRM)Rim: 22.04 ftInvert: 17.79 ft Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 2/12/2025 StormCAD [10.04.00.158]Bentley Systems, Inc. Haestad Methods Solution Center2025-02-12_Renton TESLA-01.stsw 100 - YEAR STORM Conduit FlexTable: 100-Year Storm Flow / Capacity (Design) (%) Hydraulic Grade Line (In) (ft) Hydraulic Grade Line (Out) (ft) Elevation Ground (Stop) (ft) Elevation Ground (Start) (ft) Velocity (ft/s) Flow (cfs) Slope (Calculated) (ft/ft) Diameter (in) Stop NodeStart Node 44.419.4618.550.0021.972.760.690.00510.0OUTFALLMH-05 (oPIPE-STRM) 26.613.8213.7723.0023.113.551.970.00518.0MW-1 (oPIPE- STRM) MH-03 (oPIPE- STRM) 26.613.9713.8223.1122.423.551.970.00518.0MH-03 (oPIPE-STRM)MH-02 (oPIPE-STRM) 96.119.4718.9421.9722.364.027.100.00518.0CB-11 (oPIPE- STRM) CB-10 (oPIPE- STRM) 55.819.8019.4722.3622.334.304.130.00518.0CB-10 (oPIPE- STRM) CB-09 (oPIPE- STRM) 65.519.5919.4722.3621.632.101.650.00512.0CB-10 (oPIPE-STRM)CB-07 (oPIPE-STRM) 52.719.5319.4722.3621.331.681.320.00512.0CB-10 (oPIPE- STRM) CB-03 (oPIPE- STRM) 70.819.9419.8022.3321.632.271.780.00512.0CB-09 (oPIPE-STRM)CB-08 (oPIPE-STRM) 93.519.9919.8022.3321.192.992.340.00512.0CB-09 (oPIPE- STRM) CB-04 (oPIPE- STRM) 95.618.4918.4521.8622.124.8715.290.00524.0MH-01 (oPIPE- STRM) CB-12 (oPIPE- STRM) 56.118.6318.4922.1221.112.441.920.00912.0CB-12 (oPIPE-STRM)CB-05 (oPIPE-STRM) 108.819.0218.4922.1220.153.492.740.00512.0CB-12 (oPIPE- STRM) CB-01 (oPIPE- STRM) 66.818.9418.4922.1221.973.3810.630.00524.0CB-12 (oPIPE-STRM)CB-11 (oPIPE-STRM) 32.818.9118.8421.6822.043.762.440.00518.0CB-15 (oPIPE- STRM) CB-16 (oPIPE- STRM) 49.919.0618.9122.0421.953.211.260.00512.0CB-16 (oPIPE- STRM) CB-17 (oPIPE- STRM) 148.620.2218.9122.0423.006.011.180.0206.0CB-16 (oPIPE-STRM)RL-3 (oPIPE-STRM) 56.618.6818.5521.5521.982.384.210.00518.0CB-13 (oPIPE- STRM) CB-14 (oPIPE- STRM) 48.718.8418.6821.9821.682.053.620.00518.0CB-14 (oPIPE-STRM)CB-15 (oPIPE-STRM) 74.318.9518.6821.9823.003.000.590.0206.0CB-14 (oPIPE- STRM) RL-1 (oPIPE- STRM) 51.419.0118.9421.9721.071.641.290.00512.0CB-11 (oPIPE- STRM) CB-06 (oPIPE- STRM) 89.519.3018.9421.9720.512.862.250.00512.0CB-11 (oPIPE-STRM)CB-02 (oPIPE-STRM) 74.220.2419.3921.9723.004.430.590.0206.0MH-05 (oPIPE- STRM) RL-5 (oPIPE- STRM) 158.620.5619.0621.9523.006.411.260.0206.0CB-17 (oPIPE-STRM)RL-4 (oPIPE-STRM) 64.518.4518.4423.0021.863.9719.500.00530.0V-1 (oPIPE- STRM) MH-01 (oPIPE- STRM) 56.618.5518.4521.8621.552.384.210.00518.0MH-01 (oPIPE- STRM) CB-13 (oPIPE- STRM) 148.619.9518.8421.6823.006.011.180.0206.0CB-15 (oPIPE-STRM)RL-2 (oPIPE-STRM) Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203-755-1666 2/12/2025 StormCAD [10.04.00.158]Bentley Systems, Inc. Haestad Methods Solution Center2025-02-12_Renton TESLA-01.stsw STORM MAIN NORTH SCALE: 1" = 40' H 1" = 4' V 6 8 12 16 20 24 28 32 36 40 6 8 12 16 20 24 28 32 36 40 ROOF LEADER TIE IN SCALE: 1" = 40' H 1" = 4' V 12 16 20 24 28 32 12 16 20 24 28 32 IN COMPLIANCE WITH CITY OF RENTON STANDARDS 28 600 SW 10TH PARKING LOT 600 SW 10TH PARKING LOTPR23-000169LUA24-000157C24004706600 SW 10TH PARKING LOTTED-40-432702/21/2025 -4327 STORM DRAIN PROFILES C-103.1 7 07R CATCH BASIN 8 SCALE: 1" = 40' H 1" = 4' V 14 16 20 24 28 32 14 16 20 24 28 32 CATCH BASIN 1 SCALE: 1" = 40' H 1" = 4' V 14 16 20 24 28 32 14 16 20 24 28 32 CATCH BASIN 2 SCALE: 1" = 40' H 1" = 4' V 14 16 20 24 28 32 14 16 20 24 28 32 CATCH BASIN 3 SCALE: 1" = 40' H 1" = 4' V 14 16 20 24 28 32 14 16 20 24 28 32 CATCH BASIN 4 SCALE: 1" = 40' H 1" = 4' V 14 16 20 24 28 32 14 16 20 24 28 32 CATCH BASIN 5 SCALE: 1" = 40' H 1" = 4' V 14 16 20 24 28 32 14 16 20 24 28 32 CATCH BASIN 6 SCALE: 1" = 40' H 1" = 4' V 14 16 20 24 28 32 14 16 20 24 28 32 CATCH BASIN 7 SCALE: 1" = 40' H 1" = 4' V 14 16 20 24 28 32 14 16 20 24 28 32 IN COMPLIANCE WITH CITY OF RENTON STANDARDS 28 600 SW 10TH PARKING LOT 600 SW 10TH PARKING LOTPR23-000169LUA24-000157C24004706600 SW 10TH PARKING LOTTED-40-432702/21/2025 -4327 STORM DRAIN PROFILES C-103.2 8 08R 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 27 3. TEMPORARY EROSION AND SEDIMENT CONTROL CALCULATIONS February 20, 2025 Renton Parking Improvements TESC Design Phase 1 Sediment Trap Q=CIA, I=Pi P= 2in (Map 3.2.1A) I=.543(2) i=a2(Tc)^-b2 I=1.087in/hr a=1.58 b=0.58 Q=.0(1.087)(2.35) Q=2.3cfs Phase 2 Sediment Trap Q=CIA, C=.09 I=1.087 (same as Phase 1) A=2.091AC Q=2.05 cfs Tc= T1+T2+....Tt, Tt=L/60v; V=Kr sqrt(5o) KR=20 (Table 3.2.1.C) S=1% L=380 V=20sqrt(.01) = 2 Tt=380/60(2) = 3.167 6.3<Tc<100 = TC = 6.3 i=1.58(6.3)^-.58 i= 0.543 min Sediment Trap Sizing D.2.1.5 Phase 1: SA = 2Q/.00096 Q=2.3 SA = 4782 Phase 2: Q=2.05 SA= 4255 Assumed 3:1 sizing Phase 1 : Phase 2: 40' 120' 37' 115' Code Source: 2022 Renton Surface Water Design Manual 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 28 APPENDIX C: ADDITIONAL PLANS AND REPORTS 1. GEOTECHNICAL ENGINEERING REPORT (FOR REFERENCE ONLY) February 20, 2025 Geotechnical & Earthquake Engineering Consultants DRAFT GEOTECHNICAL REPORT AND INFILTRATION TEST RESULTS PROPOSED TRUCK PARKING 600 Southwest 10th Street Renton, Washington PROJECT NO. 21-220June 2021 Prepared for:Elion Partners ________________________________________________ 3213 Eastlake Avenue E, Ste B Seattle, WA 98102 Tel (206) 262-0370 Fax (206) 262-0374 Geotechnical & Earthquake Engineering Consultants June 10, 2021 Project No. 21-220 Mr. Michael Stellino Elion Partners 3323 Northeast 163rd Street, Suite 600 Miami, Florida 33160 Subject: Draft Geotechnical Report and Infiltration Test Results Proposed Truck Parking 600 Southwest 10th Street, Lakewood, Washington Dear Mr. Stellino: Attached please find our draft geotechnical report for the proposed truck parking at 600 Southwest 10th Street in Renton, Washington, Washington. In preparing the attached report, we performed a reconnaissance of the site, observed and logged the excavation of eight test pits, conducted two infiltration tests, and performed our engineering analyses. This report is being provided as a draft pending the results of our laboratory testing. Our final report will be issued the week of June 14 after the laboratory testing is completed, and after we have received review comments from the design team. In summary, based on the results of our study, it is our opinion the proposed truck parking improvements may be constructed as planned. The near surface conditions in the project area consist of fill comprised of poorly graded sand with silt overlying native medium stiff to stiff silt. The fill should provide suitable support for the planned pavement improvements. We conducted two infiltration tests to evaluate the feasibility of infiltrating stormwater at the site. Based on the results of our tests, the site soils have limited infiltration capacity and the suitability of infiltration would be subject to engineering feasibility. We appreciate the opportunity to be of service. Please call if you have any questions. Sincerely, DRAFT Scott D. Dinkelman, LEG Principal Engineering Geologist 21-220 600 SW 10th Avenue i PanGEO, Inc. TABLE OF CONTENTS ..................................................................................................................................................... 1 1.0 INTRODUCTION................................................................................................................... 1 2.0 SITE AND PROJECT DESCRIPTION ............................................................................... 1 3.0 SUBSURFACE EXPLORATIONS ....................................................................................... 3 3.1 TEST PIT EXCAVATIONS ......................................................................................................... 3 3.2 LABORATORY TESTING .......................................................................................................... 3 3.2.1 Moisture Content and Grain Size Distribution Analysis ............................................... 3 3.2.2 Cation Exchange Capacity and Organic Content ......................................................... 4 4.0 SUBSURFACE CONDITIONS ............................................................................................. 4 4.1 SITE GEOLOGY ....................................................................................................................... 4 4.2 SOIL CONDITIONS................................................................................................................... 5 4.3 GROUNDWATER CONDITIONS ................................................................................................. 5 5.0 INFILTRATION TESTING AND RECOMMENDATIONS ............................................ 6 5.1 TEST METHOD ........................................................................................................................ 6 5.2 CORRECTION FACTORS .......................................................................................................... 7 5.3 LONG TERM INFILTRATION RATE FOR DESIGN ....................................................................... 7 5.4 CATION EXCHANGE CAPACITY TEST RESULTS ...................................................................... 8 5.5 ORGANIC CONTENT TEST RESULTS ........................................................................................ 9 5.6 CONSTRUCTION CONSIDERATIONS ......................................................................................... 9 6.0 PAVEMENT DESIGN ......................................................................................................... 10 6.1 DESIGN PARAMETERS .......................................................................................................... 10 6.2 PAVEMENT DESIGN .............................................................................................................. 11 6.2.1 Asphalt Pavement Sections .......................................................................................... 11 6.1.3 Portland Cement Concrete Pavements ........................................................................ 12 6.1.4 Subgrade Preparation .................................................................................................. 12 6.1.5 Construction of Cement Treated Base (CTB) .............................................................. 13 6.1.6 Placement of HMA ....................................................................................................... 14 6.1.7 Pavement Surface Drainage ........................................................................................ 14 6.1.8 Maintenance ................................................................................................................. 14 7.0 EARTHWORK CONSIDERATIONS ................................................................................ 14 7.1 TEMPORARY EXCAVATIONS ................................................................................................. 14 7.2 UNDERGROUND UTILITIES ................................................................................................... 15 7.2.1 Pipe Support and Bedding ........................................................................................... 15 7.2.2 Trench Backfill ............................................................................................................. 15 7.4 STRUCTURAL FILL AND COMPACTION .................................................................................. 16 Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Street, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue ii PanGEO, Inc. 7.5 MATERIAL REUSE ................................................................................................................ 16 7.6 PERMANENT CUT AND FILL SLOPES ..................................................................................... 17 7.7 WET WEATHER CONSTRUCTION .......................................................................................... 17 7.8 EROSION CONSIDERATIONS .................................................................................................. 17 8.0 LIMITATIONS ..................................................................................................................... 18 9.0 LIST OF REFERENCES ..................................................................................................... 20 Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Street, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue iii PanGEO, Inc. LIST OF ATTACHMENTS Figure 1 Vicinity Map Figure 2 Site and Exploration Plan Appendix A Summary Test Pit Logs Figure A-1 Terms and Symbols for Boring and Test Pit Logs Figure A-2 Log of Test Pit TP-1 (Infiltration Test) Figure A-3 Log of Test Pit TP-2 (Infiltration Test) Figure A-4 Log of Test Pit TP-3 Figure A-5 Log of Test Pit TP-4 Figure A-6 Log of Test Pit TP-5 Figure A-7 Log of Test Pit TP-6 Figure A-7 Log of Test Pit TP-7 Figure A-8 Log of Test Pit TP-8 Appendix B Geotechnical Laboratory Test Results Figure B-1 Grain Size Distribution (Results Pending) Appendix C Analytical Laboratory Test Results Cation Exchange Capacity and Organic Matter Test Results (Results Pending) 21-220 600 SW 10th Avenue PanGEO, Inc. 1 DRAFT GEOTECHNICAL REPORT AND INFILTRATION ASSESSMENT PROPOSED TRUCK PARKING 600 SOUTHWEST 10TH AVENUE RENTON, WASHINGTON _______________________________________________________________________ 1.0 INTRODUCTION PanGEO has completed a geotechnical study and infiltration assessment for the proposed truck parking at 600 Southwest 10th Avenue in Renton, Washington. Our scope of services included conducting a site reconnaissance, excavating eight test pits, conducting two Small Pilot Infiltration Tests, and developing the conclusions and recommendations presented in this report. This report is being provided in draft form for the preliminary use of the design team, pending the results of our laboratory testing. We will provide a final version of this report when the laboratory testing is completed. However, we do not anticipate the test results to affect the recommendations contained herein. 2.0 SITE AND PROJECT DESCRIPTION The subject site is located at 600 Southwest 10th Avenue in Renton, Washington and is approximately as shown on Figure 1, Vicinity Map. The project site is an approximately rectangular-shaped area on the north side of the existing warehouse building at 600 Southwest 10th Avenue and comprises about 4½ acres. The project area is surrounded to the north, south, east, and west by one-story warehouse buildings. The attached Figure 2, Site and Exploration Plan shows the layout of the site. Plate 1 on the next page provides an aerial view of the site while Plate 2 on the next page provides a ground level view of the site at the time of this study. The site is currently vacant of structures and is flat, with less than five feet of elevation change across the length of the site. The north half of the site is vegetated with a thin covering of grass, while the south portion of the site is surfaced with asphalt and gravel and is being used for outdoor storage. The perimeter of the site is vegetated with alder trees. We understand it is planned to develop the site for use as truck parking with spaces for 140 WB- 40 semi-trucks with trailers along with associated driving and turning lanes. At the time of this study, it had not been determined how many trucks would use the facility on a daily basis. For pavement design purposes, we have assumed 100 truck trips per day. We understand it is planned Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 2 PanGEO, Inc. to use both concrete and asphalt pavements. The planned improvements will also include the installation of underground utilities. Surface water from the impervious surfaces will be directed to an infiltration trench below the central portion of the site. Plate 1: Aerial view of the site looking toward the north. The warehouse at 600 Southwest 10th Street is in the lower portion of the photo. The project area is outlined in yellow. Plate 2: Ground level view of the site. View is looking from west to east. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 3 PanGEO, Inc. 3.0 SUBSURFACE EXPLORATIONS 3.1 TEST PIT EXCAVATIONS Eight test pits (TP-1 through TP-8) were excavated at the site on May 27, 2021. The test pits were excavated using a CAT 305E excavator. The approximate locations of our test pits were identified in the field relative to site features and are shown on Figure 2, Site and Exploration Plan. A geologist from PanGEO was present throughout the infiltration test program to observe the excavation, assist in sampling, and to document the soil samples obtained from the excavation and perform the tests. The relative in-situ density of cohesionless soils, or the relative consistency of fine-grained soils, was estimated from the excavating action of the excavator, probing the sidewalls of the test pits with a ½-inch diameter T-handle probe, and the stability of the test pit sidewalls. Where soil contacts were gradual or undulating, the average depth of the contact was recorded in the log. Test Pits TP-1 and TP-2 were used for infiltration testing purposes. The infiltration testing process consisted of initially excavating to about four feet below grade for testing. After the infiltration tests were completed the test pits were excavated to a maximum depth of about ten feet below grade. Details of our infiltration testing and discussion of the test results are included in Section 5 of this report. The soils were logged in general accordance with ASTM D-2487 Standard Practice for Classification of Soils for Engineering Purposes and the system summarized on Figure A-1, Terms and Symbols for Boring and Test Pit Logs. The summary test pit logs are included in Appendix A. 3.2 LABORATORY TESTING Representative soil samples have been submitted for laboratory testing, to verify or modify the field soil classification and to evaluate the general physical properties and engineering characteristics of the soil encountered. The test results are pending, and will be included in our final report. 3.2.1 Moisture Content and Grain Size Distribution Analysis Moisture content tests and grain-size distribution analysis were performed on six soil samples collected from the test pits. The tests were conducted in general accordance with ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 4 PanGEO, Inc. Rock by Mass and ASTM D-6913 Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis. A summary of our test results is included in Appendix B of this report. 3.2.2 Cation Exchange Capacity and Organic Content Four samples were submitted to Kuo Testing Labs for cation exchange capacity (CEC) testing in accordance with EPA Laboratory Method 9081. The CEC is a calculated value that estimates of the soil’s ability to attract, retain, and exchange cation elements. It is reported in millequivalents per 100 grams of soil (meq/100g). The results of the CEC tests are discussed in Section 5.4 of this report and are provided in Appendix C. 3.2.3 Organics Content Testing Four samples were also submitted to Kuo Testing Labs to determine the percent organics content. The testing was performed in general accordance with the ASTM D-2974 Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils. Section 5.5 of this report discusses the organics test results. 4.0 SUBSURFACE CONDITIONS 4.1 SITE GEOLOGY Based on review of the Geologic Map of the Renton Quadrangle, King County, Washington (Mullineaux, 1965) the geologic units in the vicinity of the site consist of Quaternary Alluvium deposited by the Cedar River (Qac) and Quaternary Alluvium deposited by the White River (Qaw). Quaternary Alluvium deposited by the Cedar River consists of sand and gravel deposited with thin interbeds of silt, clay and peat and occurs along the edges of the Duwamish Valley. Quaternary Alluvium deposited by the White River consists of clay, silt, and sand that locally contains peat and gravel. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 5 PanGEO, Inc. 4.2 SOIL CONDITIONS For a detailed description of the subsurface conditions encountered at each exploration location, please refer to our test pit logs provided in Appendix A. The stratigraphic contacts indicated on the logs represent the approximate depth to boundaries between soil units. Actual transitions between soil units may be more gradual or occur at different elevations. The descriptions of groundwater conditions and depths are likewise approximate. The following is a generalized description of the soils encountered in the test pits. Topsoil – A surficial layer of topsoil and sod was encountered at our test pit locations. The topsoil was about six inches thick and consisted of dark brown sand with silt and organics. Fill – Below the topsoil, we encountered fill. The fill ranged from two to four feet thick and consisted of poorly graded fine to medium sand with silt and a trace of gravel. Based on the extent of the fill encountered at our exploration locations, it is likely the pavement subgrade soils will consist of fill. Quaternary Alluvium (Qaw) – Directly below the fill, we encountered medium stiff to stiff gray silt with a trace to some sand. Based on the relatively fined grained nature of this soil, we classified this soil as Quaternary Alluvium deposited by the White River. This soil was encountered to the maximum exploration depth of 10 feet below grade. Our test pits were backfilled after completion of our logging and testing. The backfill was not compacted. We recommend the backfill in the test pits be overexcavated during clearing and grading and backfilled with properly-compacted structural fill. Our subsurface descriptions are based on the conditions encountered at the time of our exploration. Soil conditions between our exploration locations may vary from those encountered. The nature and extent of variations between our exploratory locations may not become evident until construction. If variations do appear, PanGEO should be requested to reevaluate the recommendations in this report and to modify or verify them in writing prior to proceeding with earthwork and construction. 4.3 GROUNDWATER CONDITIONS Light groundwater seepage was encountered at 8 to 8½ feet below grade in all of our test pits except Test Pits TP-4, TP-5, and TP-7 located along the north side of the site. With the planned Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 6 PanGEO, Inc. improvements to be constructed at or near existing site grade, we do not anticipate that groundwater seepage will result in construction related issues. However, groundwater could be encountered in utility trenches, especially deep utilities, if planned. It should also be noted that groundwater elevations may vary depending on the season, local subsurface conditions, and other factors. Groundwater levels are normally highest during the winter and early spring (typically October through May). The planned infiltration systems will need to be set at least five feet above the wet season high groundwater elevation. We installed shallow two-inch diameter standpipe piezometers in Test Pits TP-4, TP-6, and TP-7 to allow for monitoring of groundwater levels during the wet season to allow for establishing the wet season high groundwater elevation. 5.0 INFILTRATION TESTING AND RECOMMENDATIONS Two infiltration tests were conducted in TP-1 and TP-2 at the locations indicated on the attached Figure 2. The test method and the results are discussed below. 5.1 TEST METHOD The field infiltration tests were conducted in general accordance with the procedure for Small Pilot Infiltration Test (PIT) as outlined in the King County Surface Water Design Manual (KCSWDM) (King County, 2016). In general, the test consisted of the following procedure: • A test pit was excavated to the approximate design bottom of the proposed infiltration facilities with a minimum bottom area of 12 square feet. • The test pit was pre-soaked by maintaining a water level of at least 12 inches above the bottom of the pit. • After the pre-soak period, an electronic flow meter was used to monitor the amount of water needed to maintain a constant head of 12 inches for at least one hour and until at least a constant volume of water per time unit was achieved. • At the end of the constant head test, we measured the falling head infiltration rate by shutting off the water flow and recorded the drop in water level over regular time intervals for one hour or until all of the water was completely infiltrated. The field infiltration rate was calculated based on the final measured volume per time unit, and the surface area of the holes. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 7 PanGEO, Inc. 5.2 CORRECTION FACTORS The KCSWDM requires the infiltration rates measured in the field be reduced by applying correction factors to account for uncertainties in the test method used, depth to the water table or impervious strata, the geometry of the infiltration facility, and degree of influent control to prevent siltation and bio-buildup. We used the simplified method outlined in the King County Surface Water Design Manual (KCSWDM, 2016) to estimate the maximum design infiltration rate. The simplified method equation is provided below: Idesign = Imeasured x Ftesting x Fgeometry x Fplugging (KCSWDM Eq 5-11) where, Fgeometry = 4 D/W + 0.05 (KCSWDM Eq 5-12) (where D = the depth from the bottom of the proposed facility to the maximum wet-season water table or nearest impervious layer, whichever is less, and W = width of the facility, a value between 0.25 and 1.0 should be used) The following values were used to reduce the field infiltration rate and provide a long-term design infiltration rate: Ftesting = 0.5 for large-scale testing Fgeometry = 1.0 (D=4 feet*, W=4 feet) Fplugging = 0.7 (loams and sandy loams) *To determine Fgeometry, we estimated D to be 4 feet based on an assumed infiltration system depth of four feet and used a groundwater elevation of eight feet below grade. 5.3 LONG TERM INFILTRATION RATE FOR DESIGN Table 1, below, details the infiltration data collected during the tests and the long-term design rates calculated for each tested location. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 8 PanGEO, Inc. TABLE 1: Small Pilot Infiltration Test Data Corrected for Long Term Design Rate Test Location (depth) Pre-Soak Duration (hours) Test Stage Test Duration Field Measured Rate (in/hour) Correction Factors Long Term Design Rate (in/hour) Ftesting Fgeometry Fplugging TP-1 (4 feet) 6 Constant Head 1 hour 0.7 0.5 1 0.7 0.25 TP-2 (4 feet) 6 Constant Head 1 hour 0.4 0.5 1 0.7 0.14 Infiltration provided in Table 2 are relatively low and the soils may not be feasible to use for infiltration. The KCSWDM does not specify a minimum infiltration rate for infiltration system design except a requirement that any ponding be drawn down with 24 hours. The infiltration system feasibility should be determined by the civil engineer. 5.4 CATION EXCHANGE CAPACITY TEST RESULTS The KCSWDM specifies that soils used for treatment and infiltration should have a CEC of greater than or equal to 5 milliequivalents per 100 grams of dry soil (meq/100g). CEC testing was performed on two representative samples from our test pits. Table 2, below, provides a summary of the CEC test results. TABLE 2: Cation Exchange Capacity Test Results Location Soil Sample Depth (feet) CEC (meq/100g) TP-1 4 PENDING TP-2 4 PENDING The results of the analytical testing are provided in Appendix C. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 9 PanGEO, Inc. 5.5 ORGANIC CONTENT TEST RESULTS Two representative samples collected from our infiltration test pits were submitted to determine the percent of organic material in the soils at our infiltration test locations. The testing procedure was performed in general accordance with the ASTM D2974-13 Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils. Table 5, below, provides a summary of the organic material test results. TABLE 3: Organic Matter of Organic Soils Test Results Location Soil Sample Depth (feet) Organic Content (%) PIT-1 4 PENDING PIT-2 4 PENDING A summary of the analytical testing is provided in Appendix C. 5.6 CONSTRUCTION CONSIDERATIONS Infiltration facilities are post-construction facilities which are designed to improve the quality and manage the volume of stormwater runoff by encouraging natural infiltration on-site. In order to protect the infiltration receptor soils from becoming clogged with sediment and/or becoming compacted during construction, we recommend the following measures be implemented during construction: • The infiltration facilities should be constructed as late in the schedule as feasible and should not be constructed until after the upstream areas are stabilized. • Heavy equipment traffic on prepared subgrades should be limited, especially during wet weather. • If fine grained sediment is deposited or tracked onto the infiltration system subgrade, it should be removed using an excavator with a grade plate, a small dozer or a vacuum truck. • The subgrade should be scarified prior to placing fill to prevent sealing of the receptor soils. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 10 PanGEO, Inc. • Structural fill and aggregate base materials should be end-dumped at the edge of the fill area and the material pushed out over the subgrade. • Grading of the infiltration galleries should be accomplished using low-impact earth- moving equipment to prevent compaction of the underlying soils. Wide tracked vehicles such as excavator, small dozers and bobcats are suggested. • The infiltration system subgrade soils should be reviewed after excavation to verify the soils encountered are as anticipated. • The infiltration system should not be brought on-line until after earthwork is completed and the site is permanently stabilized with vegetation and hardscaping. 6.0 PAVEMENT DESIGN 6.1 DESIGN PARAMETERS Our pavement analysis was performed using the 1993 AASHTO pavement design methodology. Our analysis included evaluating hot mix asphalt (HMA) and Portland Cement Concrete (PCC) pavement sections. For the HMA pavement section, it is our opinion that the HMA may be used in conjunction with crushed surfacing base course (i.e., 1 ¼ inch minus crushed rock), or cement treated base. The principal benefit of CTB is the use of on-site soils and the reduction and possible elimination of the need for crushed rock base for pavement. We understand traffic will consist of 40-WB semi-trucks with trailers. The number of daily truck trips was not available at the time this study was prepared. Therefore, for our design we assumed 100 trucks per day. The parameters summarized in Table 4 on the next page were used in our design. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 11 PanGEO, Inc. TABLE 4: Pavement Design Parameters Parameter Value HMA PCC Pavement Design life 20 years 20 years Reliability 85% 85% Overall Standard Deviation 0.45 0.45 Initial Serviceability 4.2 4.2 Terminal Serviceability 2.5 2.5 Design Serviceability Loss (∆PSI) 1.7 1.7 Drainage Coefficient 1.0 1.0 Layer Coefficients: Hot Mix Asphalt Crushed Surfacing Base/Top Course Cement Treated Base 0.44 0.14 0.14 0.11 0.11 Design Resilient Modulus for Subgrade 15,000 psi 15,000 psi Average Annual Daily Traffic 100 100 Percent Heavy Trucks 100 100 ESAL 1,145,000 1,145,000 The performance of the pavement designs provided below and using the design period assumed in our analysis would depend on a number of factors, including the actual traffic loading conditions and performance of regular maintenance. The recommended pavement sections will need to be revised if the anticipated truck traffic varies from our assumptions. 6.2 PAVEMENT DESIGN 6.2.1 Asphalt Pavement Sections We recommend the following minimum pavement sections be used in new asphalt paved areas: Light Traffic Areas – truck parking areas and passenger vehicle areas: • Three inches of Class ½ inch Hot Mix Asphalt (HMA) over six inches crushed surfacing top/base course (CSTC/CSBC); or Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 12 PanGEO, Inc. • Three inches of Class ½ inch HMA over 12 inches cement treated base (see detailed discussion on cement treated base in Section 6.5.1) Heavy Traffic Areas – drive aisles subjected to truck traffic: • Four inches of Class ½ inch Hot Mix Asphalt (HMA) over six inches crushed surfacing top/base course (CSTC/CSBC); or • Four inches of Class ½ inch HMA over 12 inches cement treated base The asphalt binder should consist of pavement grade (PG) PG64-22. 6.1.3 Portland Cement Concrete Pavements • Eight inches of Portland cement concrete (plain butt jointed) over six inches of crushed surfacing base course; or • Eight inches of Portland cement concrete (plain butt jointed) over 12 inches of cement treated base. The design is based on using concrete that will achieve a minimum 28-day compressive strength (f’c) of 4,000 psi. The transverse joints in the pavement should be spaced 15 feet apart or less and should be in accordance with WSDOT Standard Specifications for Road, Bridge and Municipal Construction (WSDOT, 2021). 6.1.4 Subgrade Preparation Based on the conditions encountered in our test pits, the pavement subgrade will consist of existing fill comprised of poorly graded sand with silt and a trace of gravel. Site preparation for new pavement areas should begin with removal of the existing topsoil, vegetation, roots, debris, deleterious material, and unsuitable soil from the area of the proposed improvements and excavating to the design subgrade elevation, where applicable. Following the stripping operation and excavations necessary to achieve construction subgrade elevations, the ground surface where structural fill, or pavements are to be placed should be observed by PanGEO. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 13 PanGEO, Inc. The test pits for this study were backfilled with the site soils after completion of our logging and testing. The backfill was not compacted to the requirements of structural fill. The test pit locations should be identified during grading and the fill overexcavated and backfilled with properly- compacted structural fill. Proofrolling should be performed to identify soft or unstable areas. Soft or yielding areas identified during proofrolling should be moisture conditioned as needed and re-compacted in place. If the soft areas are still yielding after re-compaction, they should be overexcavated and replaced with structural fill to a depth that will provide a stable pavement base. The optional use of a geotextile subgrade stabilization fabric, such as Mirafi 600X, or an equivalent product placed directly on the overexcavated surface may help to bridge excessively unstable areas. The need for geotextile can be determined during construction, based on the actual conditions encountered, but should be included in the construction budget. Overexcavated areas should be backfilled with WSDOT 9-03.9(3) Crushed Surfacing Base Course, or WSDOT 9-03.14 (1) Gravel Borrow (WSDOT, 2021) compacted to the requirements of structural fill. The subgrade preparation should be observed by PanGEO during construction, to verify the adequacy of the prepared subgrade. 6.1.5 Construction of Cement Treated Base (CTB) If cement treated base pavement option is used, the cement treatment should be performed using Portland concrete cement. The cement should be applied at a rate of at least 10 pounds of cement per square foot of area to be treated to a depth of 12 inches. The cement treatment operation should be performed in general accordance with the following recommendations: • For every square foot of treated area, mix minimum 10 pounds of cement into the upper 12 inches of the subgrade soils. A road reclaimer/stabilizer, or similar piece of equipment, should be used to thoroughly mix the cement into the soil to the recommended treatment depth. • The treated subgrade should then be graded and compacted using a smooth-drum vibratory roller to at least 95 percent maximum dry density in accordance with ASTM D 1557, Modified Proctor. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 14 PanGEO, Inc. • Heavy truck traffic should be kept off the treated area for at least 3 days after treatment to allow the cement treated soils to cure; passenger vehicles may use the CTB treated surface two hours after its completion. 6.1.6 Placement of HMA Placement of HMA should be in accordance with Section 5-04 of the WSDOT Standard Specifications for Road and Bridge Construction (WSDOT, 2021). 6.1.7 Pavement Surface Drainage The pavement surface should be sloped to provide drainage of surface water to the storm drain system. Wherever possible, the grades around the perimeter of the parking log should be sloped so surface water will drain away from the pavement. Water that ponds on or adjacent to pavement surfaces could penetrate or seep under the pavement, saturate the subgrade and contribute to premature pavement deterioration. 6.1.8 Maintenance Cracking in asphalt pavement is typical and should be expected over the life of the pavement. These require routine maintenance to prevent accelerated deterioration. Accordingly, it is highly recommended to establish a maintenance program where the cracks are routinely filled as they appear beginning at about the second year of life. It is also recommended that surface fog seal coats be considered beginning at about year five and every five years after. This will help preserve the pavements, extending the pavement service life. It should be anticipated that a functional overlay will be required at between 20 and 30 years. 7.0 EARTHWORK CONSIDERATIONS 7.1 TEMPORARY EXCAVATIONS Temporary excavations should be made in accordance with Part N of WAC (Washington Administrative Code) 296-155. The contractor is responsible for maintaining safe excavation slopes and/or shoring. It is contractor’s responsibility to maintain safe working conditions, including temporary excavation stability and, if needed, dewatering. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 15 PanGEO, Inc. Based on the encountered fill and fine grained soils underlying the project area, temporary excavations should be inclined no steeper and 1½H:1V (Horizontal:Vertical). Temporary excavations should be evaluated in the field during construction based on actual observed soil conditions. If seepage is encountered, temporary excavation slope inclinations may need to be reduced. During wet weather, the cut slopes may need to be flattened to reduce potential erosion or should be covered with plastic sheeting. 7.2 UNDERGROUND UTILITIES Underground utilities planned as part of the road improvements can be installed using conventional excavation methods. Excavations in excess of 4 feet in depth should be sloped in accordance with the recommendations in Section 8.2 of this study. 7.2.1 Pipe Support and Bedding Utility installation should be conducted in accordance with the 2021 WSDOT Standard Specifications or other applicable specifications for placement and compaction of pipe bedding and backfill. In general, pipe bedding should be placed in loose lifts not exceeding 6 inches in thickness and compacted to a firm and unyielding condition. Bedding materials and thicknesses provided should be suitable for the utility system and materials installed, and in accordance with any applicable manufacturers' recommendations. Pipe bedding materials should be placed on relatively undisturbed native soil. Based on our field explorations, we anticipate relatively coarse-grained soils comprised of poorly graded gravel with cobbles. Some overexcavation and removal of cobbles should be anticipated at the pipe invert elevation to maintain a uniform grade for the utility installation. Where overexcavation is needed, additional pipe bedding should be placed to restore the grade. 7.2.2 Trench Backfill Utility trench backfill is a primary concern in reducing the potential for settlement along utility alignments, particularly in pavement areas. It is important that each section of utility line be adequately supported in the bedding material. The material should be hand tamped to ensure support is provided around the pipe haunches. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 16 PanGEO, Inc. Fill should be carefully placed and hand tamped to about 12 inches above the crown of the pipe before heavy compaction equipment is brought into use. The trench backfill should be placed in 8- to 12-inch-thick loose lifts and compacted to at least 95 percent maximum dry density, per ASTM D1557 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort. In order to reduce the potential for damaging the utilities, heavy compaction equipment should not be permitted to operate directly over utilities until a minimum of two feet of backfill has been placed. 7.4 STRUCTURAL FILL AND COMPACTION Structural fill should be properly moisture conditioned, placed in loose, horizontal lifts less than 8 inches in thickness, and compacted to at least 95 percent maximum density, determined using ASTM D 1557 (Modified Proctor). The procedure to achieve proper density of a compacted fill depends on the size and type of compacting equipment, the number of passes, thickness of the lifts being compacted, and certain soil properties. If the excavation is constricted and limits the use of heavy equipment, smaller equipment can be used, but the lift thickness will need to be reduced to achieve the required relative compaction. Generally, loosely compacted soils are a result of poor construction technique or improper moisture content. Soils with high fines contents are particularly susceptible to becoming too wet and coarse-grained materials easily become too dry, for proper compaction. Silty or clayey soils with a moisture content too high for adequate compaction should be dried as necessary, or moisture conditioned by mixing with drier materials, or other methods. 7.5 MATERIAL REUSE The existing fill may be used as structural fill, provided earthwork is conducted during dry weather and the fill is free of topsoil and organics. If it is planned to use the existing fill as structural fill the excavated soil should be stockpiled and protected with plastic sheeting to prevent it from becoming saturated by precipitation or runoff. The native silt underlying the site will not be suitable for reuse as structural fill due to the high percent of fines and relatively high natural moisture content. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 17 PanGEO, Inc. 7.6 PERMANENT CUT AND FILL SLOPES Based on the anticipated soil that will be exposed in the planned excavation, we recommend permanent cut and fill slopes be constructed no steeper than 2H:1V (Horizontal:Vertical). Cut slopes should be observed by a qualified professional during excavation to verify that conditions are as anticipated. Supplementary recommendations can then be developed, if needed, to improve stability, including flattening of slopes or installation of surface or subsurface drains. Permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and improve stability of the surficial layer of soil. 7.7 WET WEATHER CONSTRUCTION General recommendations relative to earthwork performed in wet weather or in wet conditions are presented below. The following procedures are best management practices recommended for use in wet weather construction: • Earthwork should be performed in small areas to minimize subgrade exposure to wet weather. Excavation or the removal of unsuitable soil should be followed promptly by the placement and compaction of clean structural fill. The size and type of construction equipment used may have to be limited to prevent soil disturbance. • During wet weather, the allowable fines content of the structural fill should be reduced to no more than 5 percent by weight based on the portion passing the 0.75-inch sieve. The fines should be non-plastic. • The ground surface within the construction area should be graded to promote run-off of surface water and to prevent the ponding of water. • Bales of straw and/or geotextile silt fences should be installed at strategic locations around the site to control erosion and the movement of soil. • Excavation slopes and soils stockpiled on site should be covered with plastic sheeting. 7.8 EROSION CONSIDERATIONS Surface water runoff can be controlled during construction by careful grading practices. Typically, this includes the construction of shallow, upgrade perimeter ditches or low earthen berms in Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 18 PanGEO, Inc. conjunction with silt fences to collect runoff and prevent water from entering excavations or to prevent runoff from the construction area leaving the immediate work site. Temporary erosion control may require the use of hay bales on the downhill side of the project to prevent water from leaving the site and potential storm water detention to trap sand and silt before the water is discharged to a suitable outlet. All collected water should be directed under control to a positive and permanent discharge system. Permanent control of surface water should be incorporated in the final grading design. Adequate surface gradients and drainage systems should be incorporated into the design such that surface runoff is collected and directed away from the reservoir structure to a suitable outlet. Potential issues associated with erosion may also be reduced by establishing vegetation within disturbed areas immediately following grading operations. 8.0 LIMITATIONS We have prepared this report for Elion Partners and the project design team. Recommendations contained in this report are based on a site reconnaissance, a subsurface exploration program, review of pertinent subsurface information, and our understanding of the project. The study was performed using a mutually agreed-upon scope of work. Variations in soil conditions may exist between the locations of the explorations and the actual conditions underlying the site. The nature and extent of soil variations may not be evident until construction occurs. If any soil conditions are encountered at the site that are different from those described in this report, we should be notified immediately to review the applicability of our recommendations. Additionally, we should also be notified to review the applicability of our recommendations if there are any changes in the project scope. The scope of our work does not include services related to construction safety precautions. Our recommendations are not intended to direct the contractors’ methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. Additionally, the scope of our work specifically excludes the assessment of environmental characteristics, particularly those involving hazardous substances. Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 19 PanGEO, Inc. This report has been prepared for planning and design purposes for specific application to the proposed project in accordance with the generally accepted standards of local practice at the time this report was written. No warranty, express or implied, is made. This report may be used only by the client and for the purposes stated, within a reasonable time from its issuance. Land use, site conditions (both off and on-site), or other factors including advances in our understanding of applied science, may change over time and could materially affect our findings. Therefore, this report should not be relied upon after 24 months from its issuance. PanGEO should be notified if the project is delayed by more than 24 months from the date of this report so that we may review the applicability of our conclusions considering the time lapse. It is the client’s responsibility to see that all parties to this project, including the designer, contractor, subcontractors, etc., are made aware of this report in its entirety. The use of information contained in this report for bidding purposes should be done at the contractor’s option and risk. Any party other than the client who wishes to use this report shall notify PanGEO of such intended use and for permission to copy this report. Based on the intended use of the report, PanGEO may require that additional work be performed and that an updated report be reissued. Noncompliance with any of these requirements will release PanGEO from any liability resulting from the use this report. We appreciate the opportunity to be of service. Sincerely, DRAFT DRAFT Scott D. Dinkelman, LEG Siew L. Tan, P. E. Principal Engineering Geologist Principal Geotechnical Engineer SDinkelman@pangeoinc.com STan@pangeoinc.com Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 20 PanGEO, Inc. 9.0 LIST OF REFERENCES Mullineaux, D.R., 1965, Geologic Map of the Renton Quadrangle, King County, Washington: U.S. Geological Survey, Geologic Quadrangle Map GQ-405, scale 1:24000. King County, 2016, King County Surface Water Design Manual, Department of Natural Resources and Parks. WSDOT, 2021, Standard Specifications for Road, Bridge and Municipal Construction, M 41-10. VICINITY MAP 21-220 1 Reference: ArcGIS Online Terrain Map Not to Scale PROJECT SITE Proposed Truck Parking 600 Southwest 10th Avenue Renton, WA Project No.Figure No. SITE AND EXPLORATION PLAN 21-220 213-011_Fig 2 Site & Exploration Plan.grf 6/10/21 JCRLEGEND: Approx. Scale (feet) Project Boundary 0 200 400 NORTH SOUTHW E S T 1 0 T H S T R E E T Existing Structures SENECA AVE TP-1 (2') TP-2 (2')TP-3 (4') TP-4 (2') TP-5 (2.5')TP-7 (2.5') TP-6 (2') TP-8 (2') TP-1 Approximate Test Pit Location, PanGEO, Inc., May 2021 (Approximate Fill Thickness in Feet) - Infiltration tests were conducted in TP-1 and TP-2 - Ellipse around symbol indicates shallow standpipe piezometer location Proposed Truck Parking 600 Southwest 10th Avenue Renton, WA Proposed Infiltration System APPENDIX A SUMMARY TEST PIT LOGS MOISTURE CONTENT 2-inch OD Split Spoon, SPT (140-lb. hammer, 30" drop) 3.25-inch OD Spilt Spoon (300-lb hammer, 30" drop) Non-standard penetration test (see boring log for details) Thin wall (Shelby) tube Grab Rock core Vane Shear Dusty, dry to the touch Damp but no visible water Visible free water Terms and Symbols for Boring and Test Pit Logs Density SILT / CLAY GRAVEL (<5% fines) GRAVEL (>12% fines) SAND (<5% fines) SAND (>12% fines) Liquid Limit < 50 Liquid Limit > 50 Breaks along defined planes Fracture planes that are polished or glossy Angular soil lumps that resist breakdown Soil that is broken and mixed Less than one per foot More than one per foot Angle between bedding plane and a planenormaltocoreaxis Very Loose Loose Med. Dense Dense Very Dense SPT N-values Approx. Undrained Shear Strength (psf) <4 4 to 10 10 to 30 30 to 50 >50 <2 2 to 4 4 to 8 8 to 15 15 to 30 >30 SPT N-values Units of material distinguished by color and/orcomposition frommaterial unitsabove andbelow Layers of soil typically 0.05 to 1mm thick, max. 1 cm Layer of soil that pinches out laterally Alternating layers of differing soil material Erratic, discontinuous deposit of limited extent Soil with uniform color and composition throughout Approx. Relative Density (%) Gravel Layered: Laminated: Lens: Interlayered: Pocket: Homogeneous: Highly Organic Soils #4 to #10 sieve (4.5 to 2.0 mm) #10 to #40 sieve (2.0 to 0.42 mm) #40 to #200 sieve (0.42 to 0.074 mm) 0.074 to 0.002 mm <0.002 mm UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP DESCRIPTIONS Notes: MONITORING WELL <15 15 - 35 35 - 65 65 - 85 85 - 100 GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT TEST SYMBOLS 50%or more passing #200 sieve Groundwater Level at time of drilling (ATD)Static Groundwater Level Cement / Concrete Seal Bentonite grout / seal Silica sand backfill Slotted tip Slough <250 250 - 500 500 - 1000 1000 - 2000 2000 - 4000 >4000 RELATIVE DENSITY / CONSISTENCY Fissured: Slickensided: Blocky: Disrupted: Scattered: Numerous: BCN: COMPONENT DEFINITIONS Dry Moist Wet 1. Soil exploration logs contain material descriptions based on visual observation and field tests using a systemmodified from the Uniform Soil Classification System (USCS). Where necessary laboratory tests have beenconducted (as noted in the "Other Tests" column), unit descriptions may include a classification. Please refer to thediscussions in the report text for a more complete description of the subsurface conditions. 2. The graphic symbols given above are not inclusive of all symbols that may appear on the borehole logs.Other symbols may be used where field observations indicated mixed soil constituents or dual constituent materials. COMPONENT SIZE / SIEVE RANGE COMPONENT SIZE / SIEVE RANGE SYMBOLS Sample/In Situ test types and intervals Silt and Clay Consistency SAND / GRAVEL Very Soft Soft Med. Stiff Stiff Very Stiff Hard Phone: 206.262.0370 Bottom of BoringBoulder: Cobbles: Gravel Coarse Gravel: Fine Gravel: Sand Coarse Sand: Medium Sand: Fine Sand: Silt Clay > 12 inches 3 to 12 inches 3 to 3/4 inches 3/4 inches to #4 sieve Atterberg Limit Test Compaction Tests Consolidation Dry Density Direct Shear Fines Content Grain Size Permeability Pocket Penetrometer R-value Specific Gravity Torvane Triaxial Compression Unconfined Compression Sand 50% or more of the coarsefraction passing the #4 sieve.Use dual symbols (eg. SP-SM)for 5% to 12% fines. for In Situ and Laboratory Testslisted in "Other Tests" column. 50% or more of the coarsefraction retained on the #4sieve. Use dual symbols (eg.GP-GM) for 5% to 12% fines. DESCRIPTIONS OF SOIL STRUCTURES Well-graded GRAVEL Poorly-graded GRAVEL Silty GRAVEL Clayey GRAVEL Well-graded SAND Poorly-graded SAND Silty SAND Clayey SAND SILT Lean CLAY Organic SILT or CLAY Elastic SILT Fat CLAY Organic SILT or CLAY PEAT ATT Comp Con DD DS %F GS Perm PP R SG TV TXC UCC LOG KEY 09-118 LOG.GPJ PANGEO.GDT 11/12/13Figure A-1 Test Pit TP-1 (Infiltration Test) Location: 47.471510, -122.225836 (WGS84) Approximate ground surface elevation: 23 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil) ½ – 2 Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2 – 10 Medium stiff to stiff, gray to brown, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to wet (Alluvium) Image of soils encountered at approximately 4 feet (testing depth). After testing, the test pit was excavated to approximately 10 feet below the existing ground surface. Light groundwater seepage was encountered at approximately 8 feet at the time of exploration. Figure A-2 Test Pit TP-2 (Infiltration Test) Location: 47.471547, -122.226891 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2 Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2 – 10 Medium stiff to stiff, gray, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to wet (Alluvium) Image of soils encountered at approximately 4 feet (testing depth). After testing, the test pit was excavated to approximately 10 feet below the existing ground surface. Light groundwater seepage was encountered at approximately 8 feet at the time of exploration. Figure A-3 Test Pit TP-3 Location: 47.471558, -122.227340 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 4 Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 4 – 10 Medium stiff to stiff, gray, SILT, trace to some sand, trace clay, trace organic material (wood), minor iron-oxide staining; moist to wet (Alluvium) - Wood debris encountered between approximately 6 and 8 feet. Image of soils encountered approximately 10 feet below the existing ground surface. Light groundwater seepage was encountered at approximately 8 feet at the time of exploration. Figure A-4 Test Pit TP-4 Location: 47.471783, -122.227372 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2 Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2 – 10 Medium stiff to stiff, gray, clayey SILT to silty CLAY, trace to some sand, minor iron-oxide staining; moist to very moist (Alluvium) Image of soils encountered approximately 10 feet below the existing ground surface. Groundwater was not encountered at the time of exploration. However, an increase in moisture was noted below approximately 8 feet. Figure A-5 Test Pit TP-5 Location: 47.471793, -122.226299 (WGS84) Approximate ground surface elevation: 23 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2½ Topsoil over loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2½– 10 Medium stiff to stiff, brown to gray, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to very moist (Alluvium) Image of soils encountered approximately 10 feet below the existing ground surface. Groundwater was not encountered at the time of exploration. Figure A-6 Test Pit TP-6 Location: 47.471551, -122.226204 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2 Topsoil over loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2 – 10 Medium stiff to stiff, gray, SILT, trace to some sand, trace to some clay, minor iron-oxide staining; moist to wet (Alluvium) - Transitions to SAND with silt and clay at approximately 6 feet. Image of soils encountered approximately 10 feet below the existing ground surface. Light groundwater seepage was observed at approximately 8½ feet at the time of exploration. Figure A-7 Test Pit TP-7 Location: 47.471761, -122.224953 (WGS84) Approximate ground surface elevation: 24 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2½ Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2½ – 10 Medium stiff to stiff, brown to gray, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to very moist (Alluvium) Image of soils encountered approximately 10 feet below the existing ground surface. Groundwater was not encountered at the time of exploration. Figure A-8 Test Pit TP-8 Location: 47.471200, -122.225226 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2½ Loose to medium dense, brown, gravelly fine to medium SAND with silt, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2½ – 10 Medium stiff to stiff, gray, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to wet (Alluvium) - Sand lens (1½-feet) observed at approximately 8 feet Image of soils encountered approximately 10 feet below the existing ground surface. Light groundwater seepage encountered at approximately 8 feet at the time of exploration. Test Pit Explorations: Test pits were excavated on May 27, 2021 using a CAT 305.5E2 rubber tracked excavator. Test Pits Logged by: Christian Venturino Figure A-9 APPENDIX B GEOTECHNICAL LABORATORY TEST RESULTS (RESULTS PENDING) APPENDIX C ANALYTICAL LABORATORY TEST RESULTS (RESULTS PENDING) 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 29 2. NRCS WEB SOIL SURVEY February 20, 2025 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map 52576205257680525774052578005257860525792052579805257620525768052577405257800525786052579205257980558060 558120 558180 558240 558300 558360 558420 558480 558540 558600 558060 558120 558180 558240 558300 558360 558420 558480 558540 558600 47° 28' 21'' N 122° 13' 47'' W47° 28' 21'' N122° 13' 19'' W47° 28' 9'' N 122° 13' 47'' W47° 28' 9'' N 122° 13' 19'' 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: 1:2,670 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation 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 16, Jun 4, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 6, 2020—Jul 20, 2020 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. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI Ur Urban land 33.7 100.0% Totals for Area of Interest 33.7 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 11 An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 King County Area, Washington Ur—Urban land Map Unit Composition Urban land:100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Urban Land Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8 Hydric soil rating: No Custom Soil Resource Report 13 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 14 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 15 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 30 3. SWPPP February 20, 2025 Construction Stormwater General Permit (CSWGP) Stormwater Pollution Prevention Plan (SWPPP) for 600 SW 10th Renton Parking Prepared for: Department of Ecology State of Washington Permittee / Owner Developer Operator / Contractor TBD TBD TBD 600 SW 10th Street Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD TBD TBD SWPPP Prepared By Name Organization Contact Phone Number Jack Royse Kimley-Horn and Associates, Inc. 206-756-0960 SWPPP Preparation Date April / 05 / 2022 Project Construction Dates Activity / Phase Start Date End Date TBD TBD TBD List of Acronyms and Abbreviations Acronym / Abbreviation Explanation 303(d) Section of the Clean Water Act pertaining to Impaired Waterbodies BFO Bellingham Field Office of the Department of Ecology BMP(s) Best Management Practice(s) CESCL Certified Erosion and Sediment Control Lead CO2 Carbon Dioxide CRO Central Regional Office of the Department of Ecology CSWGP Construction Stormwater General Permit CWA Clean Water Act DMR Discharge Monitoring Report DO Dissolved Oxygen Ecology Washington State Department of Ecology EPA United States Environmental Protection Agency ERO Eastern Regional Office of the Department of Ecology ERTS Environmental Report Tracking System ESC Erosion and Sediment Control GULD General Use Level Designation NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Units NWRO Northwest Regional Office of the Department of Ecology pH Power of Hydrogen RCW Revised Code of Washington SPCC Spill Prevention, Control, and Countermeasure su Standard Units SWMMEW Stormwater Management Manual for Eastern Washington SWMMWW Stormwater Management Manual for Western Washington SWPPP Stormwater Pollution Prevention Plan TESC Temporary Erosion and Sediment Control SWRO Southwest Regional Office of the Department of Ecology TMDL Total Maximum Daily Load VFO Vancouver Field Office of the Department of Ecology WAC Washington Administrative Code WSDOT Washington Department of Transportation WWHM Western Washington Hydrology Model Project Information (1.0) Project/Site Name: 600 SW 10th Street – Parking Lot Improvements Street/Location: 600 SW 10th Street City: Renton State: WA Zip code: 98057 Subdivision: Receiving waterbody: Black River Existing Conditions (1.1) Total acreage 4.38 Disturbed acreage: 3.84 Existing structures: 115,000 SF warehouse Landscape topography: The existing site is relatively flat, with a drop across the site of approximately 3 feet from the NE to SW corner. Drainage patterns: There are existing drainage structures on-site that convey stormwater runoff to the public storm main in SW 10th Street. Existing Vegetation: Grass and a few trees North and East of the existing parking lot. Critical Areas: N/A List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: N/A Table 1 includes a list of suspected and/or known contaminants associated with the construction activity. Table 1 – Summary of Site Pollutant Constituents Constituent (Pollutant) Location Depth Concentration N/A N/A N/A N/A Proposed Construction Activities (1.2) Description of site development (example: subdivision): The project will construct a parking lot around an existing industrial building on-site that is to remain, with associated landscaping and utility improvements. Description of construction activities (example: site preparation, demolition, excavation): Demolishing activities include removal of asphalt and minor clearing and grubbing. Onsite improvements include asphalt pavement, concrete curbing, landscaping, stormwatrer management BMPs, drainage structures, and striping. Description of site drainage including flow from and onto adjacent properties. Must be consistent with Site Map in Appendix A: Site stormwater runoff will be captured on-site by new drainage infrastructure and conveyed to the public storm main in SW 10th Street. Description of final stabilization (example: extent of revegetation, paving, landscaping): The majority of the disturbed land will be converted to parking lot, with limited landscaping around the edges. Contaminated Site Information: Proposed activities regarding contaminated soils or groundwater (example: on-site treatment system, authorized sanitary sewer discharge): The site does not contain any known contaminated soils or groundwater. Construction Stormwater Best Management Practices (BMPs) (2.0) The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e. hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. The 13 Elements (2.1) Element 1: Preserve Vegetation / Mark Clearing Limits (2.1.1) List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Element 2: Establish Construction Access (2.1.2) List and describe BMPs: Stabilized Construction Entrance Installation Schedules: TBD Inspection and Maintenance plan: TBD Responsible Staff: TBD Two stabilized construction entrances will be installed — One on the Southeast side of the site, just East of Sediment Trap 1, and the other on the North side, accessible via the cul de sac to the North. These will be utilized to mitigate tracking from vehicles exiting the site. Element 3: Control Flow Rates (2.1.3) Will you construct stormwater retention and/or detention facilities? Yes Will you use permanent infiltration ponds or other low impact development (example: rain gardens, bio-retention, porous pavement) to control flow during construction? No List and describe BMPs: Sediment Trap Installation Schedules: TBD Inspection and Maintenance plan: TBD Responsible Staff: TBD Two sediment traps will be constructed onsite, as shown on Sheet C-102, Demolition & Temporary Erosion & Sediment Control Plan in the Construction Documents. The two constructed Sediment Traps on either side of the site will be used to aid in the settling of suspended sediments from concentrated flows. Element 4: Install Sediment Controls (2.1.4) List and describe BMPs: Storm Drain Inlet Protection Installation Schedules: TBD Inspection and Maintenance plan: TBD Responsible Staff: TBD Storm drain inlet protections will be placed over inlets directly impacted by construction activities. The inlet protection will catch the sediment before it can travel downstream into local stormwater systems and ultimately into Black River. These BMPs will be observed throughout construction to avoid malfunctions and be cleaned as necessary. List and describe BMPs: Silt Fence Installation Schedules: TBD Inspection and Maintenance plan: TBD Responsible Staff: TBD Silt fence will be installed as shown on Sheet C-102, Demolition & Temporary Erosion & Sediment Control Plan in the Construction Documents. The silt fence will reduce the transport of coarse sediment from the site by providing a geotextile barrier that reduces velocities of sheet flow or shallow overland flow. List and describe BMPs: Sediment Trap Installation Schedules: TBD Inspection and Maintenance plan: TBD Responsible Staff: TBD Two sediment traps will be constructed onsite, as shown on Sheet C-102, Demolition & Temporary Erosion & Sediment Control Plan in the Construction Documents. The two constructed Sediment Traps on either side of the site will be used to aid in the settling of suspended sediments from concentrated flows. List and describe BMPs: Filter Sock Installation Schedules: TBD Inspection and Maintenance plan: TBD Responsible Staff: TBD A 25 ft segment of filter sock will be installed to capture runoff from the Stabilized Construction Entrance from flowing Southerly along the building, bypassing the inlet protection. Filter socks are intended to provide sediment control prior to a discharge or to slow the velocity of flows on a slope. Element 5: Stabilize Soils (2.1.5) West of the Cascade Mountains Crest Season Dates Number of Days Soils Can be Left Exposed During the Dry Season May 1 – September 30 7 days During the Wet Season October 1 – April 30 2 days Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Anticipated project dates: Start date: TBD End date: TBD Will you construct during the wet season? Yes No List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Element 6: Protect Slopes (2.1.6) Will steep slopes be present at the site during construction? No List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Element 7: Protect Drain Inlets (2.1.7) List and describe BMPs: Storm Drain Inlet Protection Installation Schedules: TBD Inspection and Maintenance plan: TBD Responsible Staff: TBD Storm drain inlet protections will be placed over inlets directly impacted by construction activities. The inlet protection will catch the sediment before it can travel downstream into local stormwater systems and ultimately into Black River. These BMPs will be observed throughout construction to avoid malfunctions and be cleaned as necessary. Element 8: Stabilize Channels and Outlets (2.1.8) Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all conveyance systems. List and describe BMPs: Interceptor Swales Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Interceptor Swales will be constructed throughout the site with locations shown on Sheet C-102, Demolition & Temporary Erosion & Sediment Control Plan in the Construction Documents. The temporary interceptor swales will be used to intercept runoff and/or groundwater from drainage areas on slopes and direct it to the two onsite sediment traps. Element 9: Control Pollutants (2.1.9) The following pollutants are anticipated to be present on-site: Table 2 – Pollutants Pollutant (and source, if applicable) N/A List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? No List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Will wheel wash or tire bath system BMPs be used during construction? No List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Will pH-modifying sources be present on-site? Table 3 – pH-Modifying Sources X None Bulk cement Cement kiln dust Fly ash Other cementitious materials New concrete washing or curing waters Waste streams generated from concrete grinding and sawing Exposed aggregate processes Dewatering concrete vaults Concrete pumping and mixer washout waters Recycled concrete Other (i.e. calcium lignosulfate) [please describe] List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches, streets, or streams. Excess concrete must not be dumped on-site, except in designated concrete washout areas with appropriate BMPs installed. Element 10: Control Dewatering (2.1.10) Temporary interceptor swales will be constructed throughout the site, which will discharge into the two sediment traps. There is no contaminated water present. Table 4 – Dewatering BMPs Infiltration Transport off-site in a vehicle (vacuum truck for legal disposal) Ecology-approved on-site chemical treatment or other suitable treatment technologies Sanitary or combined sewer discharge with local sewer district approval (last resort) Use of sedimentation bag with discharge to ditch or swale (small volumes of localized dewatering) Element 11: Maintain BMPs (2.1.11) All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained and repaired as needed to ensure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMP specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW). Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to once every calendar month. All temporary ESC BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal of either BMPs or vegetation shall be permanently stabilized. Additionally, protection must be provided for all BMPs installed for the permanent control of stormwater from sediment and compaction. BMPs that are to remain in place following completion of construction shall be examined and restored to full operating condition. If sediment enters these BMPs during construction, the sediment shall be removed and the facility shall be returned to conditions specified in the construction documents. Element 12: Manage the Project (2.1.12) The project will be managed based on the following principles: • Projects will be phased to the maximum extent practicable and seasonal work limitations will be taken into account. • Inspection and monitoring: o Inspection, maintenance and repair of all BMPs will occur as needed to ensure performance of their intended function. o Site inspections and monitoring will be conducted in accordance with Special Condition S4 of the CSWGP. Sampling locations are indicated on the Site Map. Sampling station(s) are located in accordance with applicable requirements of the CSWGP. • Maintain an updated SWPPP. o The SWPPP will be updated, maintained, and implemented in accordance with Special Conditions S3, S4, and S9 of the CSWGP. As site work progresses the SWPPP will be modified routinely to reflect changing site conditions. The SWPPP will be reviewed monthly to ensure the content is current. Table 5 – Management X Design the project to fit the existing topography, soils, and drainage patterns Emphasize erosion control rather than sediment control Minimize the extent and duration of the area exposed Keep runoff velocities low X Retain sediment on-site X Thoroughly monitor site and maintain all ESC measures Schedule major earthwork during the dry season Other (please describe) Table 6 – BMP Implementation Schedule Phase of Construction Project Stormwater BMPs Date Wet/Dry Season Before construction begins Storm Drain Inlet Protection TBD TBD Before construction begins Silt Fence TBD TBD After demolition Sediment Traps TBD TBD After demolition Interceptor Swales TBD TBD Before construction begins Stabilized Construction Entrance TBD TBD Before construction begins Filter Sock TBD TBD Element 13: Protect Low Impact Development (LID) BMPs (2.1.13) LID BMPs have not been designed for this site. Protecting and cleaning LID BMPs is not applicable. Pollution Prevention Team (3.0) Table 7 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) Resident Engineer Emergency Ecology Contact Emergency Permittee/ Owner Contact Non-Emergency Owner Contact Monitoring Personnel Ecology Regional Office Monitoring and Sampling Requirements (4.0) Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements • Site inspections • Stormwater sampling data File a blank form under Appendix D. The site log book must be maintained on-site within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See CSWGP Special Condition S8 and Section 5 of this template. Complete the following paragraph for sites that discharge to impaired waterbodies for fine sediment, turbidity, phosphorus, or pH: Site Inspection (4.1) Site inspections will be conducted at least once every calendar week and within 24 hours following any discharge from the site. For sites that are temporarily stabilized and inactive, the required frequency is reduced to once per calendar month. The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with the applicable requirements of the CSWGP. Stormwater Quality Sampling (4.2) Turbidity Sampling (4.2.1) Requirements include calibrated turbidity meter or transparency tube to sample site discharges for compliance with the CSWGP. Sampling will be conducted at all discharge points at least once per calendar week. Method for sampling turbidity: Table 8 – Turbidity Sampling Method Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size) X Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size) The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency less than 33 centimeters. If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to or greater than 6 cm, the following steps will be conducted: 1. Review the SWPPP for compliance with Special Condition S9. Make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. 3. Document BMP implementation and maintenance in the site log book. If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following steps will be conducted: 1. Telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) within 24 hours. https://www.ecology.wa.gov/About-us/Get-involved/Report-an-environmental-issue • Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, Yakima): (509) 575-2490 • Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 • Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 • Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period 3. Document BMP implementation and maintenance in the site log book. 4. Continue to sample discharges daily until one of the following is true: • Turbidity is 25 NTU (or lower). • Transparency is 33 cm (or greater). • Compliance with the water quality limit for turbidity is achieved. o 1 - 5 NTU over background turbidity, if background is less than 50 NTU o 1% - 10% over background turbidity, if background is 50 NTU or greater • The discharge stops or is eliminated. pH Sampling (4.2.2) pH monitoring is required for “Significant concrete work” (i.e. greater than 1000 cubic yards poured concrete or recycled concrete over the life of the project).The use of engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD] or fly ash) also requires pH monitoring. For significant concrete work, pH sampling will start the first day concrete is poured and continue until it is cured, typically three (3) weeks after the last pour. For engineered soils and recycled concrete, pH sampling begins when engineered soils or recycled concrete are first exposed to precipitation and continues until the area is fully stabilized. If the measured pH is 8.5 or greater, the following measures will be taken: 1. Prevent high pH water from entering storm sewer systems or surface water. 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate technology such as carbon dioxide (CO2) sparging (liquid or dry ice). 3. Written approval will be obtained from Ecology prior to the use of chemical treatment other than CO2 sparging or dry ice. Method for sampling pH: Table 8 – pH Sampling Method pH meter pH test kit Wide range pH indicator paper Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies (5.0) 303(d) Listed Waterbodies (5.1) Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? No List the impairment(s): N/A TMDL Waterbodies (5.2) Waste Load Allocation for CWSGP discharges: N/A List and describe BMPs: N/A Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water Body form is included in Appendix F. Reporting and Record Keeping (6.0) Record Keeping (6.1) Site Log Book (6.1.1) A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements • Site inspections • Sample logs Records Retention (6.1.2) Records will be retained during the life of the project and for a minimum of three (3) years following the termination of permit coverage in accordance with Special Condition S5.C of the CSWGP. Permit documentation to be retained on-site: • CSWGP • Permit Coverage Letter • SWPPP • Site Log Book Permit documentation will be provided within 14 days of receipt of a written request from Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP. Updating the SWPPP (6.1.3) The SWPPP will be modified if: • Found ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. • There is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine additional or modified BMPs are necessary for compliance. An updated timeline for BMP implementation will be prepared. Reporting (6.2) Discharge Monitoring Reports (6.2.1) Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given monitoring period the DMR will be submitted as required, reporting “No Discharge”. The DMR due date is fifteen (15) days following the end of each calendar month. DMRs will be reported online through Ecology’s WQWebDMR System. https://www.ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Water-quality- permits-guidance/WQWebPortal-guidance Notification of Noncompliance (6.2.2) If any of the terms and conditions of the permit is not met, and the resulting noncompliance may cause a threat to human health or the environment, the following actions will be taken: 1. Ecology will be notified within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number (Regional office numbers listed below). 2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or correct the noncompliance. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6 cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as required by Special Condition S5.A of the CSWGP. • Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, or Yakima County • Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman County • Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County • Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum Include the following information: 1. Your name and / Phone number 2. Permit number 3. City / County of project 4. Sample results 5. Date / Time of call 6. Date / Time of sample 7. Project name In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water. Appendix/Glossary A. Site Map 5 D LODLODLODLODLODLODLODLODLODLOD LOD LOD LOD LOD LOD LOD LOD LOD LODLOD LOD LOD LOD LOD LOD LODLODLODLODLODLOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LODLODLOD LOD LOD LOD LOD LOD LOD LOD LOD LODLODLODLODLODLODLODLODLODLODLODLODLODLOD LOD LODLOD LOD LOD LOD LOD LOD LOD LOD PHASE 2 PHASE 1 20.0'46.0'80.0'70.0'30.0'20.0'100.0'40.0'15.0'25.5' 5.0'1.5'5.0' 1.0'15.0'1.0' 20.0' 1.0'30.0'41.0' 46.7'5.0' 26.0' 45.5'3.0'40.0' 20.0' IN COMPLIANCE WITH CITY OF RENTON STANDARDS 28 600 SW 10TH PARKING LOT 600 SW 10TH PARKING LOTPR23-000169LUA24-000157C24004706600 SW 10TH PARKING LOTTED-40-432702/21/2025 -4327 LEGEND LOD LOD PROPERTY LINE LIMITS OF DISTURBANCE SILT FENCE FILTER SOCK TEMPORARY INTERCEPTOR SWALE INLET PROTECTION FULL DEPTH ASPHALT REMOVAL STABILIZED CONSTRUCTION ENTRANCE DEMOLITION NOTES REMOVE EXISTING CONCRETE PAD ADJUST EXISTING FIRE HYDRANT TO GRADE AND REMOVE EXISTING BOLLARDS AND ASSOCIATED FOOTINGS. TYP. PROTECT EXISTING ROOF LEADERS PROTECT EXISTING CHANLINK FENCING PROTECT EXISTING RAILS REMOVE EXISTING CHAINLINK FENCE & GATES & ASSOCIATED FOOTINGS, AS REQUIRED. SEE SHEET C3.0 FOR NEW LOCATION. CONTRACTOR TO REMOVE EXISTING CATCH BASIN AND ABANDON EXISTING STORM DRAIN PIPES WITH FLOWABLE FILL AFTER THE EROSION CONTROL DEVICES ARE REMOVED DIP CULVERT AS NEEDED UNDER CONSTRUCTION ENTRANCE WET SANDBLAST EXISTING STRIPING. LIGHT POLE TO BE RELOCATED. SEE SHEET C-102 FOR NEW LOCATION. EXISTING DOOR TO BE REMOVED. SEE ARCHITECTURAL PLANS. SAWCUT, REMOVE & DISPOSE EXISTING CONCRETE CURB. REMOVE & DISPOSE EXISTING RAIL ROAD INCLUDING ASSOCIATED MATERIALS SUCH AS: RAILS, RAILROAD TILES, AGGEREGATE BERM, ETC WITHIN LIMITS AS INDICATED AS COORDINATED WITH BNSF. PROTECT EXISTING DRAIN INLET. REMOVE & DISPOSE EXISTING BOLLARD. REMOVE & DISPOSE EXISTING MONUMENT SIGN AND ASSOCIATED FOOTING.. PROTECT EXISTING GAS METER. PROTECT EXISTING TRANSFORMER. PROTECT EXISTING ELECTRIC METER. PROTECT EXISTING FDC. PROTECT EXISTING WATER VALVE. JOIN TO EXISTING CURB. SAWCUT AND REMOVE 1' OF EXISTING A.C. PAVEMENT FROM PROPOSED CURB SECTION TO THE TOP OF THE BASE LAYER. PROTECT IN PLACE EXISTING PIV. REMOVE & DISPOSE EXISTING UNDERGROUND WATER VAULT, INCLUDING BACKFLOW PREVENTER AND WATER METER. REMOVE AND DISPOSE EXISTING TREE, INCLUDING TREE ROOT AND STUMP. PROTECT EX. 1.5" IRRIGATION METER AND DCVA. DRAINAGE DIVIDE GENERAL NOTES 1.CONTRACTOR TO MAINTAIN ACCESS TO THE CENTER BAY DOORS AT ALL TIMES TO THE MAXIMUM EXTENTS POSSIBLE. TEMPORARY BUILDING ACCESS MUST BE FROM SENECA AVENUE. 2.RELOCATION AND RECONNECTION OF THE LIQUID PROPANE TANK MAY BE REQUIRED TO ENSURE CONTINUED USE AFTER PAVEMENT CONSTRUCTION HAS BEEN COMPLETED. IF TANK IS NO LONGER NEEDED, THEN THE TANK SHALL BE TURNED OVER TO THE OWNER. 3.CONTRACTOR SHALL STAY CLEAR OF EXISTING RAILROAD RAILS AND CARE MUST BE TAKEN TO ENSURE UNDERMINING OF RAILS DOES NOT OCCUR. 4.CONTRACT SHALL NOT REMOVE OR RELOCATE ANY FENCING AROUND THE EXISTING COMMUNICATION TOWER. COORDINATION WITH EXISTING PROVIDER MAY BE REQUIRED. 5.PRIOR TO COMMENCEMENT OF DEMOLITION AND GROUND DISTURBANCE, THE LIMITS OF DISTURBANCE MUST BE CLEARLY MARKED. 6.ROOF LEADERS AND UNDERGROUND STORM PIPES APPEAR TO CONNECT TO A TIGHT-LINE THAT RUNS WEST TO EXISTING CATCH BASIN. CONTRACTOR TO CONFIRM THIS ASSUMPTION WITH POTHOLES PRIOR TO REMOVAL OF THIS EXISTING CATCH BASINS. IF THIS ALIGNMENT DIFFERS, THEN CONTRACTOR MUST CONTACT ENGINEER TO PROVIDE AN ALTERNATIVE STORM DRAIN DESIGN TO ENSURE ROOF RUNOFF IS MAINTAINED TO EXISTING OUTFALL. 7.INSTALL EROSION AND SEDIMENT CONTROL BMPS ACCORDING TO THE CONSTRUCTION SCHEDULE AND PHASING ON SHEET C-002. SEDIMENT TRAP 1: -DRAINAGE AREA = 2.35 AC -Q2 = 2.30 CFS -SURFACE AREA REQUIRED = 4,782 SF -SURFACE AREA PROVIDED = 4,800 SF -VOLUME PROVIDED = 16,800 CF -MINIMUM DIMENSIONS TOP OF WET STORAGE = 120' X 40' SEDIMENT TRAPS 1 AND 2 SUMMARY SEDIMENT TRAP 2: -DRAINAGE AREA = 2.09 -Q2 = 2.05 CFS -SURFACE AREA REQUIRED = 4,255 SF -SURFACE AREA PROVIDED = 4,292 SF -VOLUME PROVIDED = 15,022 CF -MINIMUM DIMENSIONS TOP OF WET STORAGE = 116' X 37' DRAINAGE PATTERN LANDSCAPE REMOVAL CONCRETE REMOVAL MILL EXISTING ASPHALT NORTH 4 DEMOLITION & TEMPORARY EROSION & SEDIMENT CONTROL PLAN C-101 ASPHALT LAYER REMOVAL ONLY, EXISTING BASE/SUBGRADE TO REMAIN. EXISTING WATER LINE TO BE REMOVED. 04R D WCCOMPACTCOMPACTCOMPACTCOMPACTWCNOPARKINGNOPARKINGNOPARKINGNOPARKINGNOPARKINGNOPARKINGNOPARKINGNO PARKINGWCWCWCWCWCWCWCWCWC WCWCWCWCWCBFP IN COMPLIANCE WITH CITY OF RENTON STANDARDS 28 600 SW 10TH PARKING LOT 600 SW 10TH PARKING LOTPR23-000169LUA24-000157C24004706600 SW 10TH PARKING LOTTED-40-432702/21/2025 -4327 NORTH GRADING & STORM DRAIN PLAN 6 C-103 LEGEND PROPERTY LINE SW 10TH S T R E E T SENECA AVE SWC-103RIDGE LINE STORM DRAIN PIPE CATCH BASIN TYPE 1P CATCH BASIN TYPE 2 MANHOLE (REFER TO PLAN FOR TYPE) ACCESS HATCH (SEE SHEET C-507) CURB INLET PARKING LIGHTS SPOT ELEVATION ABBREVIATIONS EP EDGE OF PAVEMENT TC TOP OF CURB BC BACK OF CURB FL FLOW LINE LP LOW POINT HP HIGH POINT ME MATCH EXISTING CB CATCH BASIN LF LINEAR FEET CMP CORRUGATED METAL PIPE VALVE 1"=5' 1 BOX DETAIL C-103 06R B. BMP Detail C. Correspondence D. Site Inspection Form Create your own or download Ecology’s template: https://www.ecology.wa.gov/Regulations-Permits/Permits-certifications/Stormwater- general-permits/Construction-stormwater-permit E. Construction Stormwater General Permit (CSWGP) Download CSWGP: https://www.ecology.wa.gov/Regulations-Permits/Permits- certifications/Stormwater-general-permits/Construction-stormwater-permit F. 303(d) List Waterbodies / TMDL Waterbodies Information N/A G. Contaminated Site Information N/A H. Engineering Calculations N/A 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Final Stormwater Report Page 31 APPENDIX D: OPERATIONS AND MAINTENANCE MANUAL February 20, 2025 CITY OF RENTON SURFACE WATER DESIGN MANUAL 2022 City of Renton Surface Water Design Manual 6/22/2022 A-1 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS This appendix contains the maintenance requirements for the following typical stormwater flow control and water quality facilities and on-site BMPs (ctrl/click the title to follow the link): No. 1 – Detention Ponds No. 2 – Infiltration Facilities No. 3 – Detention Tanks and Vaults No. 4 – Control Structure/Flow Restrictor No. 5 – Catch Basins and Manholes No. 6 – Conveyance Pipes and Ditches No. 7 – Debris Barriers (e.g., trash racks) No. 8 – Energy Dissipaters No. 9 – Fencing No. 10 – Gates/Bollards/Access Barriers No. 11 – Grounds (landscaping) No. 12 – Access Roads No. 13 – Basic Bioswale (grass) No. 14 – Wet Bioswale No. 15 – Filter Strip No. 16 – Wetpond No. 17 – Wetvault No. 18 – Stormwater Wetland No. 19 – Sand Filter Pond No. 20 – Sand Filter Vault No. 21 – Proprietary Facility Cartridge Filter Systems No. 22 – Baffle Oil/Water Separator No. 23 – Coalescing Plate Oil/Water Separator APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-2 No. 24 – Catch Basin Insert (not allowed in the city for oil control) No. 25 – Drywell BMP No. 26 – Gravel Filled Infiltration Trench BMP No. 27 – Gravel Filled Dispersion Trench BMP No. 28 – Native Vegetated Surface/Native Vegetated Landscape BMP No. 29 – Perforated Pipe Connections BMP No. 30 – Permeable Pavement BMP No. 31 – Bioretention BMP No. 32 – RainWater Harvesting BMP No. 33 – Rock Pad BMP No. 34 – Sheet Flow BMP No. 35 – Splash Block BMP No. 36 – Vegetated Roof BMP No. 37 – Rain Garden BMP No. 38 – Soil Amendment BMP No. 39 – Retained Trees No. 40 – Filterra System No. 41 – Compost Amended Vegetated Filter Strip (CAVFS) No. 42 – Media Filter Drain (MFD) No. 43 – Compost-Amended Biofiltration Swale APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-3 NO. 1 – DETENTION PONDS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Storage Area Sediment accumulation Accumulated sediment that exceeds 10% of the designed pond depth. Sediment cleaned out to designed pond shape and depth; pond reseeded if necessary to control erosion. Liner damaged (If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Emergency Overflow/Spillway Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. Rock missing Only one layer of rock exists above native soil in area five square feet or larger or any exposure of native soil on the spillway. Spillway restored to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-4 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Infiltration Pond, Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Infiltration Pond, Tank, Vault, Trench, or Small Basin Storage Area Sediment accumulation If two inches or more sediment is present or a percolation test indicates facility is working at or less than 90% of design. Facility infiltrates as designed. Liner damaged (If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Infiltration Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Infiltration Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-5 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Infiltration Pond, Tank, Vault, Trench, or Small Basin Filter Bags Plugged filter bag (if applicable) Filter bag more than 1/2 full. Replace filter bag or redesign system. Infiltration Pond, Tank, Vault, Trench, or Small Basin Pre- settling Ponds and Vaults Sediment accumulation 6" or more of sediment has accumulated. Pre-settling occurs as designed Infiltration Pond, Rock Filter Plugged rock filter High water level on upstream side of filter remains for extended period of time or little or no water flows through filter during heavy rain storms. Rock filter replaced evaluate need for filter and remove if not necessary. Infiltration Pond Emergency Overflow Spillway Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-6 NO. 3 – DETENTION TANKS AND VAULTS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Tank or Vault Storage Area Trash and debris Any trash and debris accumulated in vault or tank (includes floatables and non- floatables). No trash or debris in vault. Sediment accumulation Accumulated sediment depth exceeds 10% of the diameter of the storage area for ½ length of storage vault or any point depth exceeds 15% of diameter. Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than ½ length of tank. All sediment removed from storage area. Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipes Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-7 NO. 3 – DETENTION TANKS AND VAULTS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Access Manhole (cont.) Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-8 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the structure opening or is blocking capacity of the structure by more than 10%. No Trash or debris blocking or potentially blocking entrance to structure. Trash or debris in the structure 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 structure. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the structure to the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Sump of structure contains no sediment. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering structure through cracks, or maintenance person judges that structure is unsound. Structure is sealed and structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering structure through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Structure has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder rungs missing or unsafe Ladder is unsafe due to missing rungs, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. FROP-T Section Damaged FROP-T T section is not securely attached to structure wall and outlet pipe structure should support at least 1,000 lbs of up or down pressure. T section securely attached to wall and outlet pipe. Structure is not in upright position (allow up to 10% from plumb). Structure in correct position. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-9 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED FROP-T Section (cont.) Damaged FROP-T (cont.) Connections to outlet pipe are not watertight or show signs of deteriorated grout. Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. Any holes—other than designed holes—in the structure. Structure has no holes other than designed holes. Cleanout Gate Damaged or missing cleanout gate Cleanout gate is missing. Replace cleanout gate. Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one maintenance person. Gate moves up and down easily and is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing orifice plate Control device is not working properly due to missing, out of place, or bent orifice plate. Plate is in place and works as designed. Obstructions to orifice plate Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Overflow Pipe Obstructions to overflow pipe Any trash or debris blocking (or having the potential of blocking) the overflow pipe. Pipe is free of all obstructions and works as designed. Deformed or damaged lip of overflow pipe Lip of overflow pipe is bent or deformed. Overflow pipe does not allow overflow at an elevation lower than design Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates (If applicable) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. Damaged or missing grate Grate missing or broken member(s) of the grate. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-10 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-11 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipe (cont.) Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates (Catch Basins) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. Damaged or missing grate Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-12 NO. 6 – CONVEYANCE PIPES AND DITCHES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/root growth in pipe Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged pipes Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive vegetation growth Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-13 NO. 7 – DEBRIS BARRIERS (E.G., TRASH RACKS) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED. Site Trash and debris Trash or debris plugging more than 20% of the area of the barrier. Barrier clear to receive capacity flow. Sediment accumulation Sediment accumulation of greater than 20% of the area of the barrier Barrier clear to receive capacity flow. Structure Cracked, broken, or loose pipe or structure Structure which bars attached to is damaged – pipe is loose or cracked or concrete structure is cracked, broken, or loose. Structure barrier attached to is sound. Bars Incorrect bar spacing Bar spacing exceeds 6 inches. Bars have at most 6 inches spacing. Damaged or missing bars Bars are bent out of shape more than 3 inches. Bars in place with no bends more than ¾ inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars are loose and rust is causing 50% deterioration to any part of barrier. Repair or replace barrier to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-14 NO. 8 – ENERGY DISSIPATERS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED. Site Trash and debris Trash and/or debris accumulation. Dissipater clear of trash and/or debris. 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. Rock Pad Missing or moved rock Only one layer of rock exists above native soil in area five square feet or larger or any exposure of native soil. Rock pad prevents erosion. Dispersion Trench Pipe plugged with sediment Accumulated sediment that exceeds 20% of the design depth. Pipe cleaned/flushed so that it matches design. Not discharging water properly Visual evidence of water discharging at concentrated points along trench (normal condition is a “sheet flow” of water along trench). Water discharges from feature by sheet flow. Perforations plugged Over 1/4 of perforations in pipe are plugged with debris or sediment. Perforations freely discharge flow. Water flows out top of “distributor” catch basin. Water flows out of distributor catch basin during any storm less than the design storm. No flow discharges from distributor catch basin. Receiving area over- saturated Water in receiving area is causing or has potential of causing landslide problems. No danger of landslides. Gabions Damaged mesh Mesh of gabion broken, twisted or deformed so structure is weakened or rock may fall out. Mesh is intact, no rock missing. Corroded mesh Gabion mesh shows corrosion through more than ¼ of its gage. All gabion mesh capable of containing rock and retaining designed form. Collapsed or deformed baskets Gabion basket shape deformed due to any cause. All gabion baskets intact, structure stands as designed. Missing rock Any rock missing that could cause gabion to loose structural integrity. No rock missing. Manhole/Chamber Worn or damaged post, baffles or side of chamber Structure dissipating flow deteriorates to ½ or original size or any concentrated worn spot exceeding one square foot which would make structure unsound. Structure is in no danger of failing. Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch or any evidence of soil entering the structure through cracks, or maintenance inspection personnel determines that the structure is not structurally sound. Manhole/chamber is sealed and structurally sound. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No soil or water enters and no water discharges at the joint of inlet/outlet pipes. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-15 NO. 9 – FENCING MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Erosion or holes under fence Erosion or holes more than 4 inches high and 12-18 inches wide permitting access through an opening under a fence. No access under the fence. Wood Posts, Boards and Cross Members Missing or damaged parts Missing or broken boards, post out of plumb by more than 6 inches or cross members broken No gaps on fence due to missing or broken boards, post plumb to within 1½ inches, cross members sound. Weakened by rotting or insects Any part showing structural deterioration due to rotting or insect damage All parts of fence are structurally sound. Damaged or failed post foundation Concrete or metal attachments deteriorated or unable to support posts. Post foundation capable of supporting posts even in strong wind. Metal Posts, Rails and Fabric Damaged parts Post out of plumb more than 6 inches. Post plumb to within 1½ inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence (including post, top rails, and fabric) more than 1 foot out of design alignment. Fence is aligned and meets design standards. Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or protective coating Part or parts that have a rusting or scaling condition that has affected structural adequacy. Structurally adequate posts or parts with a uniform protective coating. Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-16 NO. 10 – GATES/BOLLARDS/ACCESS BARRIERS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Chain Link Fencing Gate Damaged or missing members Missing gate. Gates in place. Broken or missing hinges such that gate cannot be easily opened and closed by a maintenance person. Hinges intact and lubed. Gate is working freely. Gate is out of plumb more than 6 inches and more than 1 foot out of design alignment. Gate is aligned and vertical. Missing stretcher bar, stretcher bands, and ties. Stretcher bar, bands, and ties in place. Locking mechanism does not lock gate Locking device missing, non-functioning or does not link to all parts. Locking mechanism prevents opening of gate. Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. Bar Gate Damaged or missing cross bar Cross bar does not swing open or closed, is missing or is bent to where it does not prevent vehicle access. Cross bar swings fully open and closed and prevents vehicle access. Locking mechanism does not lock gate Locking device missing, non-functioning or does not link to all parts. Locking mechanism prevents opening of gate. Support post damaged Support post does not hold cross bar up. Cross bar held up preventing vehicle access into facility. Bollards Damaged or missing bollards Bollard broken, missing, does not fit into support hole or hinge broken or missing. No access for motorized vehicles to get into facility. Bollards do not lock Locking assembly or lock missing or cannot be attached to lock bollard in place. No access for motorized vehicles to get into facility. Boulders Dislodged boulders Boulders not located to prevent motorized vehicle access. No access for motorized vehicles to get into facility. Evidence of vehicles circumventing boulders Motorized vehicles going around or between boulders. No access for motorized vehicles to get into facility. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-17 NO. 11 – GROUNDS (LANDSCAPING) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Trees and Shrubs Hazard tree identified Any tree or limb of a tree identified as having a potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. No hazard trees in facility. Damaged tree or shrub identified Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-18 NO. 12 – ACCESS ROADS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site 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 drivable by maintenance vehicles. Debris which could damage vehicle tires or prohibit use of road. Roadway drivable by maintenance vehicles. 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. Blocked roadway 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. At least 12-foot of width on access road. Road Surface Erosion, settlement, potholes, soft spots, ruts Any surface defect which hinders or prevents maintenance access. Road drivable by maintenance vehicles. Vegetation on road surface Trees or other vegetation prevent access to facility by maintenance vehicles. Maintenance vehicles can access facility. Shoulders and Ditches Erosion Erosion within 1 foot of the roadway more than 8 inches wide and 6 inches deep. Shoulder free of erosion and matching the surrounding road. Weeds and brush Weeds and brush exceed 18 inches in height or hinder maintenance access. Weeds and brush cut to 2 inches in height or cleared in such a way as to allow maintenance access. Modular Grid Pavement 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. Damaged or missing blocks/grids Access surface compacted because of broken on missing modular block. Access road surface restored so road infiltrates. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-19 NO. 13 – BASIC BIOSWALE (GRASS) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and/or debris accumulated on the bioswale site. No trash or debris on the bioswale site. 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. Swale Section Sediment accumulation Sediment depth exceeds 2 inches in 10% of the swale treatment area. No sediment deposits in grass treatment area of the bioswale. Sediment inhibits grass growth over 10% of swale length. Grass growth not inhibited by sediment. Sediment inhibits even spreading of flow. Flow spreads evenly through swale Erosion/scouring Eroded or scoured swale bottom due to channelization or high flows. No eroded or scoured areas in bioswale. Cause of erosion or scour addressed. Poor vegetation coverage Grass is sparse or bare or eroded patches occur in more than 10% of the swale bottom. Swale has no bare spots and grass is thick and healthy. Excessive vegetation growth Grass excessively tall (greater than 10 inches), grass is thin or nuisance weeds and other vegetation have taken over. Grass is between 3 and 4 inches tall, thick and healthy. No nuisance vegetation present. Excessive shade Grass growth is poor because sunlight does not reach swale. Healthy grass growth or swale converted to a wet bioswale. Constant baseflow Continuous flow through the swale, even when it has been dry for weeks or an eroded, muddy channel has formed in the swale bottom. Baseflow removed from swale by a low- flow pea-gravel drain or bypassed around the swale. Standing water Water pools in the swale between storms or does not drain freely. Swale freely drains and there is no standing water in swale between storms. Channelization Flow concentrates and erodes channel through swale. No flow channels in swale. Flow Spreader Concentrated flow Flow from spreader not uniformly distributed across entire swale width. Flows are spread evenly over entire swale width. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-20 NO. 14 – WET BIOSWALE MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and/or debris accumulated at the site. No trash or debris at the site. 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. Swale Section Sediment accumulation Sediment depth exceeds 2 inches in 10% of the swale treatment area. No sediment deposits in treatment area. Erosion/scouring Eroded or scoured swale bottom due to channelization or high flows. No eroded or scoured areas in bioswale. Cause of erosion or scour addressed. Water not retained in swale during wet season Water not retained to a depth of about 4 inches during the wet season. Water depth of 4 inches throughout swale for most of wet season. Poor vegetation coverage and/or nuisance vegetation present Vegetation sparse, does not provide adequate filtration or crowded out by very dense clumps of cattail or nuisance vegetation. Wetland vegetation fully covers bottom of swale and no cattails or nuisance vegetation present. Insufficient water to maintain vegetation growth Wetland vegetation dies due to lack of water. Wetland vegetation remains healthy (may require converting to grass lined bioswale) Flow Spreader Concentrated flow Flow from spreader not uniformly distributed across entire swale width. Flows are spread evenly over entire swale width. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-21 NO. 15 – FILTER STRIP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris accumulated on the filter strip site. Filter strip site free of any trash or debris 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. Grass Strip Sediment accumulation Sediment accumulation on grass exceeds 2 inches depth. No sediment deposits in treatment area. Erosion/scouring Eroded or scoured swale bottom due to channelization or high flows. No eroded or scoured areas in bioswale. Cause of erosion or scour addressed. Excessive vegetation growth Grass excessively tall (greater than 10 inches), grass is thin or nuisance weeds and other vegetation have taken over. Grass is between 3 and 4 inches tall, thick and healthy. No nuisance vegetation present. Poor vegetation coverage and/or nuisance vegetation present Grass has died out, become excessively tall (greater than 10 inches) or nuisance vegetation is taking over. Grass is healthy, less than 9 inches high and no nuisance vegetation present. Flow Spreader Concentrated flow Flow from spreader not uniformly distributed across entire swale width. Flows are spread evenly over entire swale width. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-22 NO. 16 – WETPOND MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris accumulated on the wetpond site. Wetpond site free of any trash or debris. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Side Slopes of Dam, Berm, internal berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm or embankment integrity, are not interfering with access or maintenance or leaves do not cause a plugging problem they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Top or Side Slopes of Dam, Berm, internal berm or Embankment Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Irregular surface on internal berm Top of berm not uniform and level. Top of berm graded to design elevation. Pond Areas Sediment accumulation (except first wetpool cell) Accumulated sediment that exceeds 10% of the designed pond depth. Sediment cleaned out to designed pond shape and depth. Sediment accumulation (first wetpool cell) Sediment accumulations in pond bottom that exceeds the depth of sediment storage (1 foot) plus 6 inches. Sediment storage contains no sediment. Liner damaged (If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Low water level (all wetpool cells) Cell level(s) drops more than 12 inches in any 7-day period. Cell level(s) drops less than 12 inches in any 7-day period. Algae mats (first wetpool cell) Algae mats develop over more than 10% of the water surface should be removed. Algae mats removed (usually in the late summer before Fall rains, especially in Sensitive Lake Protection Areas.) APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-23 NO. 16 – WETPOND MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Pond Areas (cont.) Sparse or dying design planting and poor vegetation survival Sparse or dying design planting, or when design plantings are not thriving across 80% or more of the design vegetated areas within the pond; invasive vegetation (e.g., cattails) Design plantings and vegetation are thriving and appropriately spaced across 80% or more of the design vegetated areas within the pond; invasives removed including root clumps Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won’t seal Valve does not seal completely. Valve completely seals closed. Emergency Overflow Spillway Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-24 NO. 17 – WETVAULT MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from facility site. Treatment Area Trash and debris Any trash and debris accumulated in vault (includes floatables and non-floatables). No trash or debris in vault. Sediment accumulation Sediment accumulation in vault bottom exceeds the depth of the sediment zone plus 6 inches. No sediment in vault. 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. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks, vault does not retain water or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. Baffles damaged Baffles corroding, cracking, warping and/or showing signs of failure or baffle cannot be removed. Repair or replace baffles or walls to specifications. Ventilation area blocked/plugged Ventilation area blocked or plugged. No reduction of ventilation area exists. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won’t seal Valve does not seal completely. Valve completely seals closed. Access Manhole Access cover/lid damaged or difficult to open Access cover/lid cannot be easily opened by one person. Corrosion/deformation of cover/lid. Access cover/lid can be opened by one person. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Access doors/plate has gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-25 NO. 18 – STORMWATER WETLAND MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from facility site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth or grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Side Slopes of Dam, Berm, Internal Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Top or Side Slopes of Dam, Berm, Internal Berm or Embankment Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Irregular surface on internal berm Top of berm not uniform and level. Top of berm graded flat to design elevation. Pond Areas Sediment accumulation (first cell/forebay) Sediment accumulations in pond bottom that exceeds the depth of sediment storage (1 foot) plus 6 inches. Sediment storage contains no sediment. Sediment accumulation (wetland cell) Accumulated sediment that exceeds 10% of the designed pond depth. Sediment cleaned out to designed pond shape and depth. Liner damaged (If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Low water level (first cell/forebay) Cell level drops more than 12 inches in any 7-day period. Cell level drops no more than 12 inches in any 7-day period. Low water level (wetland cell) Cell does not retain water for at least 10 months of the year or wetland plants are not surviving. Water retained at least 10 months of the year or wetland plants are surviving. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-26 NO. 18 – STORMWATER WETLAND MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Pond Areas (cont.) Algae mats (first cell/forebay) Algae mats develop over more than 10% of the water surface should be removed. Algae mats removed (usually in the late summer before Fall rains, especially in Sensitive Lake Protection Areas.) Vegetation Vegetation dead, dying, or overgrown (cattails) or not meeting original planting specifications across more than 20% of the entire design vegetated area within the pond. Plants in wetland cell surviving across 80% or more of the entire design vegetated area within the pond and not interfering with wetland function. Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won’t seal Valve does not seal completely. Valve completely seals closed. Emergency Overflow Spillway Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of outflow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-27 NO. 19 – SAND FILTER POND MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from facility site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover (not in the treatment area) Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Pre-Treatment (if applicable) Sediment accumulation Sediment accumulations in pond bottom that exceeds the depth of sediment storage (1 foot) plus 6 inches. Sediment storage contains no sediment. Liner damaged (If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Low water level Cell empty, doesn't hold water. Water retained in first cell for most of the year. Algae mats Algae mats develop over more than 10% of the water surface should be removed. Algae mats removed (usually in the late summer before Fall rains, especially in Sensitive Lake Protection Areas.) Pond Area Sediment accumulation Sediment or crust depth exceeds ½-inch over 10 % of surface area of sand filter. No sediment or crust deposit on sand filter that would impede permeability of the filter section. Excessive grass growth (if applicable) Grass becomes excessively tall (greater than 6 inches) or when nuisance weeds and other vegetation start to take over or thatch build up occurs. Mow vegetation and/or remove nuisance vegetation. Side Slopes of Pond Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-28 NO. 19 – SAND FILTER POND MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Sand Filter Media Plugged media Drawdown of water through the sand filter media, takes longer than 24 hours, and/or flow through the overflow pipes occurs frequently. A sieve analysis of >4% -100 or >2% -200 requires replacing sand filter media. Sand filter media surface is aerated or the surface is scraped and replaced, and drawdown rate is normal. Prolonged flows Sand is saturated for prolonged periods of time (several weeks) and does not dry out between storms due to continuous base flow or prolonged flows from detention facilities. Excess flows bypassed or confined to small portion of filter media surface. Short circuiting Flows become concentrated over one section of the sand filter rather than dispersed or drawdown rate of pool exceeds 12 inches per hour. Flow and percolation of water through the sand filter is uniform and dispersed across the entire filter area and drawdown rate is normal. Insufficient media thickness Sand thickness is less than 18 inches. Rebuild sand thickness to a minimum of 18 inches. Underdrains and Clean-Outs Sediment and debris Underdrains or clean-outs partially plugged or filled with sediment and/or debris. Junction box/cleanout wyes not watertight. Underdrains and clean-outs free of sediment and debris and are watertight. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Rock Pad Missing rock or out of place Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil. Rock pad restored to design standards. Flow Spreader Concentrated flow Flow from spreader not uniformly distributed across sand filter. Flows spread evenly over sand filter. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-29 NO. 20 – SAND FILTER VAULT MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from facility site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Pre-Treatment Chamber Sediment accumulation Sediment accumulation exceeds the depth of the sediment zone plus 6 inches. Sediment storage contains no sediment. Sand Filter Media Sediment accumulation Sediment depth exceeds ½-inch on sand filter media. Sand filter freely drains at normal rate. Trash and debris Trash and debris accumulated in vault (floatables and non-floatables). No trash or debris in vault. Plugged media Drawdown of water through the sand filter media, takes longer than 24 hours, and/or flow through the overflow pipes occurs frequently. A sieve analysis of >4% -100 or >2% -200 requires replacing sand filter media. Sand filter media drawdown rate is normal. Short circuiting Seepage or flow occurs along the vault walls and corners. Sand eroding near inflow area. Cleanout wyes are not watertight. Sand filter media section re-laid and compacted along perimeter of vault to form a semi-seal. Erosion protection added to dissipate force of incoming flow and curtail erosion. Vault Structure Damaged to walls, frame, bottom and/or top slab. Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault replaced or repaired to provide complete sealing of the structure. Ventilation area blocked/plugged Ventilation area blocked or plugged. No reduction of ventilation area exists. Underdrains and Cleanouts Sediment and debris Underdrains or clean-outs partially plugged, filled with sediment and/or debris or not watertight. Underdrains and clean-outs free of sediment and debris and sealed. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-30 NO. 20 – SAND FILTER VAULT MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large Access Doors/Plate Damaged or difficult to open access doors/plate Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-31 NO. 21 – PROPRIETARY FACILITY CARTRIDGE FILTER SYSTEMS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED In addition to the specific maintenance criteria provided below, all manufacturers’ requirements shall be followed. Facility Documentation Update facility inspection record after each inspection. Maintenance records are up to date. Provide certification of replaced filter media. Filter media is certified to meet manufacturer specifications. Site Trash and debris Any trash or debris which impairs the function of the facility. Trash and debris removed from facility. Contaminants and pollution Any evidence of contaminants or pollution such as oils, 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. Life cycle Once per year. Facility is re-inspected and any needed maintenance performed. Vault Treatment Area Sediment on vault floor Varies – Refer to manufacturer’s requirements. Vault is free of sediment. Sediment on top of cartridges Varies – Refer to manufacturer’s requirements. Vault is free of sediment. Multiple scum lines above top of cartridges Thick or multiple scum lines above top of cartridges. Probably due to plugged canisters or underdrain manifold. Cause of plugging corrected, canisters replaced if necessary. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch and any evidence of soil particles entering the structure through the cracks, or qualified inspection personnel determines the vault is not structurally sound. Vault replaced or repaired to design specifications. Baffles damaged Baffles corroding, cracking warping, and/or showing signs of failure as determined by maintenance/inspection person. Repair or replace baffles to specification. Filter Media Standing water in vault Varies – Refer to manufacturer’s requirements. No standing water in vault 24 hours after a rain event. Short circuiting Flows do not properly enter filter cartridges. Flows go through filter media. Underdrains and Clean-Outs Sediment and debris Underdrains or clean-outs partially plugged or filled with sediment and/or debris. Underdrains and clean-outs free of sediment and debris. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-32 NO. 21 – PROPRIETARY FACILITY CARTRIDGE FILTER SYSTEMS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large Access Doors/Plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat and cover access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-33 NO. 22 – BAFFLE OIL/WATER SEPARATOR MAINTENANCE COMPONENT DEFECT CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash or debris which impairs the function of the facility. Trash and debris removed from facility. Contaminants and pollution Floating oil in excess of 1 inch in first chamber, any oil in other chambers or other contaminants of any type in any chamber. No contaminants present other than a surface oil film. Vault Treatment Area Sediment accumulation Sediment accumulates exceeds 6 inches in the vault. No sediment in the vault. Discharge water not clear Inspection of discharge water shows obvious signs of poor water quality- effluent discharge from vault shows thick visible sheen. Effluent discharge is clear. Trash or debris accumulation Any trash and debris accumulation in vault (floatables and non-floatables). Vault is clear of trash and debris. Oil accumulation Oil accumulations that exceed 1 inch, at the surface of the water in the oil/water separator chamber. No visible oil depth on water. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch or 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. Baffles damaged Baffles corroding, cracking, warping and/or showing signs of failure as determined by maintenance inspection personnel. Repair or replace baffles to specifications. Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won’t seal Valve does not seal completely. Valve completely seals closed. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-34 NO. 22 – BAFFLE OIL/WATER SEPARATOR MAINTENANCE COMPONENT DEFECT CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Large Access Doors/Plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat and cover access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or cover/lid. Lifting rings sufficient to lift or remove cover/lid. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-35 NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR MAINTENANCE COMPONENT DEFECT CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash or debris which impairs the function of the facility. Trash and debris removed from facility. Contaminants and pollution Floating oil in excess of 1 inch in first chamber, any oil in other chambers or other contaminants of any type in any chamber. No contaminants present other than a surface oil film. Vault Treatment Area Sediment accumulation in the forebay Sediment accumulation of 6 inches or greater in the forebay. No sediment in the forebay. Discharge water not clear Inspection of discharge water shows obvious signs of poor water quality – effluent discharge from vault shows thick visible sheen. Repair function of plates so effluent is clear. Trash or debris accumulation Trash and debris accumulation in vault (floatables and non-floatables). Trash and debris removed from vault. Oil accumulation Oil accumulation that exceeds 1 inch at the water surface in the in the coalescing plate chamber. No visible oil depth on water and coalescing plates clear of oil. Coalescing Plates Damaged Plate media broken, deformed, cracked and/or showing signs of failure. Replace that portion of media pack or entire plate pack depending on severity of failure. Sediment accumulation Any sediment accumulation which interferes with the operation of the coalescing plates. No sediment accumulation interfering with the coalescing plates. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-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. Baffles damaged Baffles corroding, cracking, warping and/or showing signs of failure as determined by maintenance/inspection person. Repair or replace baffles to specifications. Ventilation Pipes Plugged ventilation pipes Any obstruction to the ventilation pipes. Ventilation pipes are clear. Shutoff Valve Damaged or inoperable shutoff valve Shutoff valve cannot be opened or closed. Shutoff valve operates normally. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-36 NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR MAINTENANCE COMPONENT DEFECT CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Access Manhole (cont.) Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat and cover access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-37 NO. 24 – CATCH BASIN INSERT (NOT ALLOWED IN THE CITY FOR OIL CONTROL) APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-38 NO. 25 – DRYWELL BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Plugging, obstructions Any cause limiting flow into drywell. Drywell able to receive full flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the drywell is evident. No trash or debris that could get into the drywell can be found. Pipes Plugged inlet The entrance to the pipe is restricted due to sediment, trash, or debris. The entrance to the pipe is not restricted. Vegetation/root growth in pipes Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Plugged pipe Sediment or other material prevents free flow of water through the pipe. Water flows freely through pipes. Broken pipe or joint leaks Damage to the pipe or pipe joints allowing water to seep out. Pipe does not allow water to exit other than at the outlet. Structure Basin leaks Holes or breaks in the basin allow water to leave the basin at locations other than per design. Basin is sealed and allows water to exit only where designed. Filter Media Plugged filter media Filter media plugged. Flow through filter media is normal. NO. 26 – GRAVEL FILLED INFILTRATION TRENCH BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow to infiltration trench. Infiltration trench able to receive full flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the infiltration trench is evident. No trash or debris that could get into the infiltration trench can be found. Pipes Plugged inlet The entrance to the pipe is restricted due to sediment, trash, or debris. The entrance to the pipe is not restricted. Vegetation/root growth in pipes Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Plugged pipes Sediment or other material prevents free flow of water through the pipe. Water flows freely through pipes. Broken pipe or joint leaks Damage to the pipe or pipe joints allowing water to seep out. Pipe does not allow water to exit other than at the outlet to the trench. Structure Flow not reaching trench Flows are not getting into the trench as designed. Water enters and exits trench as designed. Cleanout/inspection access does not allow cleaning or inspection of trench The cleanout/inspection access is not available. Cleanout/inspection access is available. Filter Media Plugged filter media Filter media plugged. Flow through filter media is normal. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-39 NO. 27 – GRAVEL FILLED DISPERSION TRENCH BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow to dispersion trench or preventing spreader function. Dispersion trench able to receive full flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the dispersion trench is evident. No trash or debris that could get into the dispersion trench can be found. Pipes Plugged inlet The entrance to the pipe is restricted due to sediment, trash, or debris. The entrance to the pipe is not restricted. Vegetation/root growth in pipes Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Plugged pipe Sediment or other material prevents free flow of water through the pipe. Water flows freely through pipes. Broken pipe or joint leaks. Damage to the pipe or pipe joints allowing water to seep out. Pipe does not allow water to exit other than at the outlet to the trench. Broken or missing cleanout caps Cleanout caps are broken, missing, or buried. Cleanout caps are accessible and intact. Structure Flow not reaching trench Flows are not getting into the trench as designed. Water enters and exits trench as designed. Perforated pipe plugged Flow not able to enter or properly exit from perforated pipe. Water freely enters and exits perforated pipe. Flow not spreading evenly at outlet of trench Outlet flows channelizing or not spreading evenly from trench. Sheet flow occurs at the outlet of the trench. Cleanout/inspection access does not allow cleaning or inspection of perforated pipe The cleanout/inspection access is not available. Cleanout/inspection access is available. Filter Media Plugged filter media Filter media plugged. Flow through filter media is normal. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-40 NO. 28 – NATIVE VEGETATED SURFACE/NATIVE VEGETATED LANDSCAPE BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on the native vegetated surface/native vegetated landscape site. Native vegetated surface site free of any trash or debris. Vegetation Insufficient vegetation Less than two species each of native trees, shrubs, and groundcover occur in the design area. A minimum of two species each of native trees, shrubs, and groundcover is established and healthy. Poor vegetation coverage Less than 90% if the required vegetated area has healthy growth. A minimum of 90% of the required vegetated area has healthy growth. Undesirable vegetation present Weeds, blackberry, and other undesirable plants are invading more than 10% of vegetated area. Less than 10% undesirable vegetation occurs in the required native vegetated surface area. Vegetated Area Soil compaction Soil in the native vegetation area compacted. Less than 8% of native vegetation area is compacted. Insufficient vegetation Less than 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. A minimum of 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. Excess slope Slope of native vegetation area greater than 15%. Slope of native growth area does not exceed 15%. NO. 29 – PERFORATED PIPE CONNECTIONS BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow into perforated pipe system or outfall of BMP is plugged or otherwise nonfunctioning. Outfall of BMP is receiving designed flows from perforated pipe connection. Inflow Inflow impeded Inflow into the perforated pipe is partially or fully blocked or altered to prevent flow from getting into the pipe. Inflow to the perforated pipe is unimpeded. Pipe Trench Area Surface compacted Ground surface over the perforated pipe trench is compacted or covered with impermeable material. Ground surface over the perforated pipe is not compacted and free of any impervious cover. Outflow Outflow impeded Outflow from the perforated pipe into the public drainage system is blocked. Outflow to the public drainage system is unimpeded. Outfall Area Erosion or landslides Existence of the perforated pipe is causing or exasperating erosion or landslides. Perforated pipe system is sealed off and an alternative BMP is implemented. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-41 NO. 30 – PERMEABLE PAVEMENT BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Surface cleaning/ vegetation control Media surface vacuumed or pressure washed annually, vegetation controlled to design maximum. Weed growth suggesting sediment accumulation. No dirt, sediment, or debris clogging porous media, or vegetation limiting infiltration. Porous Concrete, Porous Asphaltic Concrete, and Permeable Pavers Trash and debris Trash and debris on the pavement interfering with infiltration; leaf drop in fall season. No trash or debris interfering with infiltration. Sediment accumulation Sediment accumulation on the pavement interfering with infiltration; runoff from adjacent areas depositing sediment/debris on pavement. Pavement infiltrates as designed; adjacent areas stabilized. Insufficient infiltration rate Pavement does not infiltrate at a rate of 10 inches per hour. Pavement infiltrates at a rate greater than 10 inches per hour. Excessive ponding Standing water for a long period of time on the surface of the pavement. Standing water infiltrates at the desired rate. Broken or cracked pavement Pavement is broken or cracked. No broken pavement or cracks on the surface of the pavement. Settlement Uneven pavement surface indicating settlement of the subsurface layer. Pavement surface is uniformly level. Moss growth Moss growing on pavement interfering with infiltration. No moss interferes with infiltration. Inflow restricted Inflow to the pavement is diverted, restricted, or depositing sediment and debris on the pavement. Inflow to pavement is unobstructed and not bringing sediment or debris to the pavement. Underdrain not freely flowing Underdrain is not flowing when pavement has been infiltrating water. Underdrain flows freely when water is present. Overflow not controlling excess water Overflow not controlling excess water to desired location; native soil is exposed or other signs of erosion damage are present. Overflow permits excess water to leave the site at the desired location; Overflow is stabilized and appropriately armored. Permeable Pavers Broken or missing pavers Broken or missing paving blocks on surface of pavement. No missing or broken paving blocks interfering with infiltration. Uneven surface Uneven surface due to settlement or scour of fill in the interstices of the paving blocks. Pavement surface is uniformly level. Compaction Poor infiltration due to soil compaction between paving blocks. No soil compaction in the interstices of the paver blocks limiting infiltration. Poor vegetation growth (if applicable) Grass in the interstices of the paving blocks is dead. Healthy grass is growing in the interstices of the paver blocks. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-42 NO. 31 – BIORETENTION BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Vegetation Vegetation to be watered and pruned as needed and mulch applied to a minimum of 2 inches to maintain healthy growth. Healthy vegetation growth with full coverage as designed. Bioretention Area Trash and debris Trash and debris in the bioretention area; leaf drop in the fall season. No trash or debris In the bioretention area. Sediment accumulation Sediment accumulation in the bioretention area interfering with infiltration. Water in the bioretention infiltrates as designed. Excessive ponding Standing water in the bioretention area for more than two days. Standing water infiltrates at the desired rate. Inflow restricted Inflow not getting into bioretention; debris/sediment blockage at inlet features; native soil is exposed or other signs of erosion damage is present. Unobstructed and properly routed inflow into bioretention area; inlet is stabilized and appropriately armored. Overflow not controlling excess water Overflow water not controlled by outlet features; native soil is exposed or other signs of erosion damage is present. Outlet features control overflow; overflow is stabilized and appropriately armored. Underdrain not freely flowing Underdrain is not flowing when bioretention area has been infiltrating water. Underdrain flows freely when water is present. Vegetation Poor vegetation coverage Plants not thriving across at least 80% of the entire design vegetated area within the BMP; overly dense vegetation requiring pruning. Healthy water tolerant plants in bioretention area, plants thriving across at least 80% of the entire design vegetated area within the facility. Insufficient vegetation Plants not water tolerant species. Plants are water tolerant. Weeds present Weeds growing in bioretention area. No weeds in bioretention area. Watering not occurring Planting schedule requires frequent watering (approx. weekly Year 1, bimonthly Years 2 and 3) for new facilities, and as needed for established plantings or dry periods Plants are established and thriving Pest control Signs of pests, such as wilting or chewed leaves or bark, spotting or other indicators; extended ponding period encouraging mosquitoes Plant community is pest-free when following an approved Integrated Pest Management plan; bioretention functioning normally and ponding controlled as needed for pest control Containment Berm and Earthen Slopes Erosion Erosion occurring at earthen slopes or containment berm side slope. Erosion on the containment berm and side slopes has been repaired and the cause of the erosion corrected. Voids created by nuisance animals (e.g., rodents) or tree roots Voids affecting berm integrity or creating leaky pond condition Voids have been repaired; facility is free of nuisance animals following an approved Integrated Pest Management plan. Settlement Any part of the containment berm top has less than 6 inches of freeboard from the maximum pond level to the top of the berm. A minimum of 6 inches freeboard from the maximum pond level to the top of the berm. Amended Soil Poor soil nutrients Soil not providing plant nutrients. Soil providing plant nutrients. Bare spots Bare spots on soil in bioretention area. No bare spots, bioretention area covered with vegetation or mulch mixed into the underlying soil. Compaction Poor infiltration due to soil compaction in the bioretention area. No soil compaction in the bioretention area. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-43 NO. 32 – RAINWATER HARVESTING BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Insufficient storage volume No rain water in storage unit at the beginning of the rain season. Maximum storage available at the beginning of the rain season (Oct. 1). Collection Area Trash and debris Trash of debris on collection area may plug filter system Collection area clear of trash and debris. Filter Restricted or plugged filter Filter is partially or fully plugged preventing water from getting in to the storage unit. Filter is allowing collection water into storage unit. NO. 33 – ROCK PAD BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on rock pad site. Rock pad site free of any trash or debris. Rock Pad Area Insufficient rock pad size Rock pad is not 2 feet by 3 feet by 6 inches thick or as designed. Rock pad is 2 feet by 3 feet by 6 inches thick or as designed. Vegetation growth Vegetation is seen growing in or through rock pad. No vegetation within rock pad area. Rock Exposed soil Soil can be seen through the rock pad. Full thickness of the rock pad is in place, no soil visible through rock pad. NO. 34 – SHEET FLOW BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on the sheet flow site. Sheet flow site free of any trash or debris. Sheet flow area Erosion Soil erosion occurring in sheet flow zone. Soil erosion is not occurring and rills and channels have been repaired. Concentrated flow Sheet flow is not occurring in the sheet flow zone. Sheet flow area is regraded to provide sheet flow. NO. 35 – SPLASH BLOCK BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on the splash block. Splash block site free of any trash or debris. Splash Block Dislodged splash block Splash block moved from outlet of downspout. Splash block correctly positioned to catch discharge from downspout. Channeling Water coming off the splash block causing erosion. No erosion occurs from the splash block. Downspout water misdirected Water coming from the downspout is not discharging to the dispersal area. Water is discharging normally to the dispersal area. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-44 NO. 36 – VEGETATED ROOF BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Vegetation Vegetation to be watered and pruned as needed to maintain healthy growth. Healthy vegetation growth with full coverage as designed. Site Trash and debris Trash and debris has accumulated on the vegetated roof. Vegetated roof free of any trash or debris. Waterproof Membrane Leaking waterproof membrane Waterproof membrane breached. Waterproof membrane has no tears or holes allowing water through it. Drainage Layer Drainage pathway plugged/obstructed Drainage layer flow plugged or obstructed. Drainage layer passing water with no obstruction. Drainage Overflow obstructed Drainage of overflow is obstructed. Overflow has no obstruction. Growth Media Compaction Soil in the growth media area compacted. No part of the growth media is compacted. Erosion Growth media washed out. Growth media is not being washed away. Insufficient nutrients Plants are not thriving. Growth media has proper nutrients to support plant growth. Vegetation Insufficient vegetation Vegetation species not succulents, grass, herbs, and/or wildflowers adapted to harsh conditions. Correct species of vegetation is used. Poor vegetation coverage Healthy vegetation covers less than 90% of vegetation area. Healthy vegetation covers more than 90% of vegetation area. Undesirable vegetation Weeds and other undesirable plants are invading more than 10% of vegetated area. No undesirable vegetation occurs in the vegetated area. No herbicides or pesticides used to control undesirable vegetation. Poor vegetation growth Special vegetation not thriving. Special vegetation is kept healthy and inspected on frequent schedule. Border Zone Access restricted Border zone limited by vegetation overgrowth or other means. Border zone is kept open so vegetated area is accessible. Gravel Stop Overflow uncontained Gravel stop does not contain overflow or divert it to a designed outlet. Overflow water is only exits from the designed outlet. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-45 NO. 37 – RAIN GARDEN BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Facility – General Requirements Mosquitoes Standing water remains for more than 3 days after the end of a storm Rain garden drains freely. Standing water in rain garden does not persist for more than 3 days after a storm event. Cause of the standing water addressed (see “Ponded water”). Trash and debris Trash and debris present No trash or debris present Earthen Side Slopes and Berms Erosion Persistent soil erosion on slopes No eroded or scoured areas. Cause of erosion or scour addressed. Rockery Sidewalls Unstable rockery Rockery side walls are insecure Stable rockery sidewalls (may require consultation with licensed engineer, particularly for walls 4 feet or greater in height) Rain Garden Bottom Area Sediment accumulation Visible sediment deposition in the rain garden that reduces drawdown time of water in the rain garden No sediment accumulation in rain garden. Source of sediment addressed. Debris accumulation Accumulated leaves in facility No leaves clogging outlet structure or impeding water flow. Mulch Lack of mulch Bare spots (without mulch cover) are present or mulch depth less than 2 inches Facility has a minimum 2- to 3-inch layer of an appropriate type of mulch. Mulch kept away from woody stems. Splash Block Inlet Water not properly directed to rain garden Water is being directed towards building structure Blocks are reconfigured to direct water to rain garden and away from structure. Pipe Inlet/Outlet Erosion Rock or cobble removed or missing and concentrated flows contacting soil No eroded or scoured areas. Cause of erosion or scour addressed. Cover of rock or cobbles protects the ground where concentrated water flows into the rain garden. Accumulated debris Accumulated leaves, sediment, debris or vegetation at curb cuts, inlet or outlet pipe Blockage cleared Damaged pipe Pipe is damaged Pipe repaired/replaced Clogged pipe Pipe is clogged Pipe clear of roots and debris Blocked access Maintain access for inspections Vegetation cleared or transplanted within 1 foot of inlets and outlets Ponded Water Ponded water Excessive ponding water: Ponded water remains in the rain garden more than 48 hours after the end of a storm Rain garden drains freely. Standing water in rain garden does not persist for more than 48 hours after a storm event. Leaf litter/debris/sediment removed. Overflow Blocked overflow Capacity reduced by sediment or debris No sediment or debris in overflow. Vegetation Blocked site distances and sidewalks Vegetation inhibits sight distances and sidewalks Sidewalks and sight distances along roadways and sidewalks are kept clear. Blocked pipes Vegetation is crowding inlets and outlets Inlets and outlets in rain garden clear of vegetation. Unhealthy vegetation Yellowing: possible Nitrogen (N) deficiency Poor growth: possible Phosphorous (P) deficiency Poor flowering, spotting or curled leaves, or weak roots or stems: possible Potassium (K) deficiency Plants are healthy and appropriate for site conditions. Weeds Presence of weeds Weeds removed (manual methods preferred) and mulch applied. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-46 NO. 37 – RAIN GARDEN BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Summer Watering (years 1–3) Plant establishment Tree, shrubs and groundcovers in first 3 years of establishment period Plants are watered during plant establishment period (years 1–3). Summer Watering (after establishment) Drought conditions Vegetation requires supplemental water Plants are watered during drought conditions or more often if necessary during post-establishment period (after 2 years). APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-47 NO. 38 – SOIL AMENDMENT BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Soil Media Unhealthy vegetation Vegetation not fully covering ground surface or vegetation health is poor. Yellowing: possible Nitrogen (N) deficiency. Poor growth: possible Phosphorous (P) deficiency. Poor flowering, spotting or curled leaves, or weak roots or stems: possible Potassium (K) deficiency. Plants are healthy and appropriate for site conditions Inadequate soil nutrients and structure In the fall, return leaf fall and shredded woody materials from the landscape to the site when possible Soil providing plant nutrients and structure Excessive vegetation growth Grass becomes excessively tall (greater than 10 inches); nuisance weeds and other vegetation start to take over. Healthy turf- “grasscycle” (mulch-mow or leave the clippings) to build turf health Weeds Preventive maintenance Avoid use of pesticides (bug and weed killers), like “weed & feed,” which damage the soil Fertilizer needed Where fertilization is needed (mainly turf and annual flower beds), a moderate fertilization program should be used which relies on compost, natural fertilizers or slow-release synthetic balanced fertilizers Integrated Pest Management (IPM) protocols for fertilization followed Bare spots Bare spots on soil No bare spots, area covered with vegetation or mulch mixed into the underlying soil. Compaction Poor infiltration due to soil compaction To remediate compaction, aerate soil, till to at least 8-inch depth, or further amend soil with compost and re-till If areas are turf, aerate compacted areas and top dress them with 1/4 to 1/2 inch of compost to renovate them If drainage is still slow, consider investigating alternative causes (e.g., high wet season groundwater levels, low permeability soils) Also consider site use and protection from compacting activities No soil compaction Poor infiltration Soils become waterlogged, do not appear to be infiltrating. Facility infiltrating properly Erosion/Scouring Erosion Areas of potential erosion are visible Causes of erosion (e.g., concentrate flow entering area, channelization of runoff) identified and damaged area stabilized (regrade, rock, vegetation, erosion control matting).For deep channels or cuts (over 3 inches in ponding depth), temporary erosion control measures in place until permanent repairs can be made Grass/Vegetation Unhealthy vegetation Less than 75% of planted vegetation is healthy with a generally good appearance. Healthy vegetation. Unhealthy plants removed/replaced. Appropriate vegetation planted in terms of exposure, soil and soil moisture. Noxious Weeds Noxious weeds Listed noxious vegetation is present (refer to current County noxious weed list). No noxious weeds present. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-48 NO. 39 – RETAINED TREES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Tree Dead or declining Dead, damaged, or declining Tree replaced per planting plan or acceptable substitute NO. 40 – FILTERRA SYSTEM MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED In addition to the specific maintenance criteria provided below, all manufacturer’s requirements shall be followed. 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. “Ponding” of water on mulch cover “Ponding” in unit could be indicative of clogging due to excessive fine sediment accumulation or spill of petroleum oils Stormwater should drain freely and evenly through mulch cover 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 Vegetation 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 Media/mulch too dry Irrigation is required Plants absent Plants absent Appropriate plants are present Excessive plant growth Excessive plant growth inhibits facility function or becomes a hazard for pedestrian and vehicular circulation and safety Pruning and/or thinning vegetation maintains proper plant density. Appropriate plants are present. 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 MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-49 NO. 41 – COMPOST AMENDED VEGETATED FILTER STRIP (CAVFS) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED General Sediment accumulation on grass Sediment depth exceeds 2 inches. Remove sediment deposits. Relevel so slope is even and flows pass evenly through strip. Excessive vegetation growth Grass becomes excessively tall (greater than 10 inches); nuisance weeds and other vegetation start to take over. Mow grass and control nuisance vegetation so that flow is not impeded. Grass should be mowed to a height of 6 inches. Trash and debris Trash and debris have accumulated on the vegetated filter strip. Remove trash and debris from filter. Erosion/scouring Areas have eroded or scoured due to flow channelization or high flows. For ruts or bare areas less than 12 inches wide, repair the damaged area by filling with a 50/50 mixture of crushed gravel and compost. The grass will creep in over the rock in time. If bare areas are large, generally greater than 12 inches wide, the vegetated filter strip should be regraded and reseeded. For smaller bare areas, overseed when bare spots are evident. Flow spreader uneven or clogged Flow spreader is uneven or clogged so that flows are not uniformly distributed over entire filter width. Level the spreader and clean so that flows are spread evenly over entire filter width APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-50 NO. 42 – MEDIA FILTER DRAIN (MFD) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED General Sediment accumulation on grass filter strip Sediment depth exceeds 2 inches or creates uneven grading that interferes with sheet flow. Remove sediment deposits on grass treatment area of the embankment. When finished, embankment should be level from side to side and drain freely toward the toe of the embankment slope. There should be no areas of standing water once inflow has ceased. No-vegetation zone/flow spreader is uneven or clogged Flow spreader is uneven or clogged so that flows are not uniformly distributed over entire embankment width. Level the spreader and clean to spread flows evenly over entire embankment width. Poor vegetation coverage Grass is sparse or bare, or eroded patches are observed in more than 10% of the grass strip surface area. Determine why grass growth is poor and correct the offending condition. Reseed into loosened, fertile soil or compost; or, replant with plugs of grass from the upper slope. Excessive vegetation growth Grass becomes excessively tall (greater than 10 inches); nuisance weeds and other vegetation start to take over. Mow vegetation or remove nuisance vegetation to not impede flow. Mow grass to a height of 6 inches. Media filter drain mix needs replacement Water is seen on the surface of the media filter drain mix long after the storms have ceased. Typically, the 6-month, 24-hour precipitation event should drain within 48 hours. More common storms should drain within 24 hours. Maintenance also needed on a 10-year cycle and during a preservation project. Excavate and replace all of the media filter drain mix contained within the media filter drain. Excessive shading Grass growth is poor because sunlight does not reach embankment. If possible, trim back overhanging limbs and remove brushy vegetation on adjacent slopes. Trash and debris Trash and debris have accumulated on embankment. Remove trash and debris from embankment. Flooding of media filter drain When media filter drain is inundated by flood water Evaluate media filter drain material for acceptable infiltration rate and replace if media filter drain does not meet long-term infiltration rate standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-51 NO. 43 – COMPOST-AMENDED BIOFILTRATION SWALE MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and/or debris accumulated on the bioswale site. No trash or debris on the bioswale site. 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. Swale Section Sediment accumulation Sediment depth exceeds 2 inches in 10% of the swale treatment area. No sediment deposits in grass treatment area of the bioswale. Sediment inhibits grass growth over 10% of swale length. Grass growth not inhibited by sediment. Sediment inhibits even spreading of flow. Flow spreads evenly through swale Erosion/scouring Eroded or scoured swale bottom due to channelization or high flows. No eroded or scoured areas in bioswale. Cause of erosion or scour addressed. Poor vegetation coverage Grass is sparse or bare or eroded patches occur in more than 10% of the swale bottom. Swale has no bare spots and grass is thick and healthy. Excessive vegetation growth Grass excessively tall (greater than 10 inches), grass is thin or nuisance weeds and other vegetation have taken over. Grass is between 3 and 4 inches tall, thick and healthy. No nuisance vegetation present. Excessive shade Grass growth is poor because sunlight does not reach swale. Healthy grass growth or swale converted to a wet bioswale. Constant baseflow Continuous flow through the swale, even when it has been dry for weeks or an eroded, muddy channel has formed in the swale bottom. Baseflow removed from swale by a low- flow pea-gravel drain or bypassed around the swale. Standing water Water pools in the swale between storms or does not drain freely. Swale freely drains and there is no standing water in swale between storms. Channelization Flow concentrates and erodes channel through swale. No flow channels in swale. Insufficient compost depth Depth of compost is less than 3 inches. Compost depth is 3 inches. Flow Spreader Concentrated flow Flow from spreader not uniformly distributed across entire swale width. Flows are spread evenly over entire swale width. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe.