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RS_TIR_250826_v1
Western Washington Division Eastern Washington Division 165 NE Juniper St., Ste 201, Issaquah, WA 98027 407 Swiftwater Blvd, Cle Elum, WA 98922 Phone: (425) 392-0250 Fax: (425) 391-3055 Phone: (509) 674-7433 Fax: (509) 674-7419 www.EncompassES.net PRELIMINARY TECHNICAL INFORMATION REPORT For Meadow Ave Short Plat 3804 Meadow Avenue N Renton, WA 98056 January 29, 2021 Revised March 7, 2022 Revised August 12, 2025 Prepared by: Ian Dahl Encompass Engineering Job No. 20591 Prepared For: Huy Nguyen 15400 SE 155th Place, Unit 99 Renton, WA 98058 Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | i Table of Contents List of Figures ................................................................................................................................... i I. PROJECT OVERVIEW ................................................................................................................ 1 II. CONDITIONS AND REQUIREMENTS SUMMARY ...................................................................... 8 III. DOWNSTREAM ANALYSIS ..................................................................................................... 12 IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ........................... 16 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN ..................................................................... 20 VII. OTHER PERMITS ..................................................................................................................... 20 VIII. CSWPP ANALYSIS AND DESIGN .............................................................................................. 20 IX. BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION of COVENANT .................. 20 X. OPERATION AND MAINTENANCE MANUAL .......................................................................... 20 List of Figures Figure 1 – TIR Worksheet Figure 2 – Vicinity Map Figure 3 – Soils Map and Legend Figure 4 – Existing Conditions Map Figure 5 – Developed Conditions Map Figure 6 – Drainage Review Flow Chart Figure 7 – Downstream Map Appendix A Geotechnical Engineering Study by Earth Solutions NW dated March 12, 2020 Geotechnical Review Letter by Earth Solutions NW dated March 7, 2022 Appendix B WWHM Output Appendix C Arborist Report/Tree Plan by Layton Tree Consulting, LLC dated February 12, 2020 Appendix D CSWWP Analysis And Design Appendix E Bond Quantities, Facility Summaries And Declaration Of Covenant Appendix F Operation And Maintenance Manual Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 1 I. PROJECT OVERVIEW Project: Meadow Ave Short Plat Site Address: 3804 Meadow Avenue N, Renton, WA 98056 (See Vicinity Map) Tax Parcel #: 334270-0570 Zoning District: R-6, Single Family Residential Site Area: 25,536 SF (0.59 Acres) Site Location: The site is in the City of Renton within the NW quarter of Section 32, Township 24 North, Range 5 East, W.M, King County, Washington. The site is located on the northeast corner of the intersection of Meadow Ave N and N 38th St. Figure 2: Vicinity Map Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 2 Pre-developed Site Conditions The project site is located in the City of Renton on a 25,536 SF (0.59 Acres) lot that is zoned R-6 (single- family residential). The site is accessed from Meadow Ave N, north of the intersection of N 38th St and Meadow Ave N. The site is bordered to the north and south by single family residences, to the east by I- 405, and to the west by Meadow Ave N right-of way (ROW). The site is currently developed with a single-family residence accessed from Meadow Ave N via two gravel driveways on the western side of the site. The site slopes gently to the northwest at approximately 2%. The property is located within the May Creek drainage basin. Stormwater runoff currently leaves the site at a single natural discharge location at the northwest corner, creating one Threshold Discharge Area for the site. The majority of the site gently slopes at approximately 2%, allowing stormwater to sheet flow northwest into Meadow Ave. A cleared area on the adjacent parcel 334270-0630 is tributary to the site. This off-site area sheet flows to the north over approximately 10-15% slopes onto the existing gravel driveway located in the southern portion of the site. See full downstream analysis in Section III of this Technical Information Report (TIR). An Existing Conditions Map is included as Figure 4 at the end of this Section. Critical Areas According to the City of Renton online mapping system, there is a High Erosion Hazard Area in the northeast corner of the project site. There are no required buffers or building setbacks associated with the erosion hazard area. No other critical areas have been identified on the project site. Soils Per the US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS) Web Soil Survey (WSS) information, the majority of the project site is underlain with Indianola loamy sand, 5 to 15 percent slopes with a small portion of the site in the northeast corner underlain with Norma sandy loam (See Figure 3 on the following page). Soil explorations detailed in the Geotechnical Engineering Study by Earth Solutions NW dated March 12, 2020 (Appendix A) encountered primarily medium dense silty sand and poorly graded sand. These findings are consistent with geologic and soil mapping resources. An in- situ infiltration test was performed and a design infiltration rate of 5 inches per hour was determined by the Geotech, which is suitable for stormwater infiltration. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 3 Figure 3: Soil Map and Legend Developed Site Conditions The project proposes the development of three (3) single-family lots within the 25,536 SF (0.59 Acres) parcel, as well as a 7.5-foot right-of-way dedication with frontage improvements. Lot 1 is 8,230 SF (0.19 AC) and is located in the north portion of the site. Lot 2 is 8,043 SF (0.18 Acres) and is located in the central portion of the site. Lot 3 is 7,868 SF (0.18 AC) and is located in the southern portion of the site. All three (3) lots will have driveway access off of Meadow Ave N. Frontage improvements will include the addition of a 5-foot sidewalk, 8-foot planter strip, as well as curb and gutter along the edge of asphalt roadway. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 4 The total disturbed area for this project, including the construction of frontage improvements, is 27,320 SF (0.627 AC). The parcel is zoned R-6, which allows for a maximum building coverage of 40% and a maximum impervious surface coverage of 55%. The maximum allowable building/impervious surface for each lot is discussed below: · Lot 1: The maximum allowable building coverage for Lot 1 is 8,230 SF*0.4 = 3,292 SF, and the maximum impervious surface coverage is 8,230 SF*0.55 = 4,527 SF. The final site layout of Lot 1 has not been determined at this stage; therefore, this report assumes that the future impervious surfaces required to construct the residence on Lot 1 will use the maximum coverages stated above. · Lot 2: The maximum allowable building coverage for Lot 2 is 8,043 SF*0.4 = 3,217 SF, and the maximum impervious surface coverage is 8,043 SF*0.55 = 4,424 SF. The final site layout of Lot 2 has not been determined at this stage; therefore, this report assumes that the future impervious surfaces required to construct the residence on Lot 2 will use the maximum coverages stated above. · Lot 3: The maximum allowable building coverage for Lot 2 is 7,868 SF*0.4 = 3,147 SF, and the maximum impervious surface coverage is 7,868 SF*0.55 = 4,327 SF. The final site layout of Lot 3 has not been determined at this stage; therefore, this report assumes that the future impervious surfaces required to construct the residence on Lot 3 will use the maximum coverages stated above. Stormwater runoff from the proposed development of Lots 1-3 will be managed as follows: · Lot 1: Stormwater BMP’s satisfying Core Requirement #9 will be used to the maximum extent feasible to mitigate new runoff created by the proposed single-family residence and other impervious surfaces on-site. A 30’x9’ gravel filled full infiltration trench is proposed on Lot 1 to the west of the proposed structure to mitigate stormwater from impervious areas. An emergency overflow to the public storm system from the infiltration trench will be provided. This report assumes that the maximum impervious surface per zoning (4,527 SF) will be conveyed to this infiltration trench. · Lot 2: Stormwater BMP’s satisfying Core Requirement #9 will be used to the maximum extent feasible to mitigate new runoff created by the proposed single-family residence and other impervious surfaces on-site. A 30’x9’ gravel filled full infiltration trench is proposed on Lot 2 to the west of the proposed structure to mitigate stormwater from impervious areas. An emergency overflow to the public storm system from the infiltration trench will be provided. This report assumes that the maximum impervious surface per zoning (4,424 SF) will be conveyed to this infiltration trench. · Lot 3: Stormwater BMP’s satisfying Core Requirement #9 will be used to the maximum extent feasible to mitigate new runoff created by the proposed single-family residence and other impervious surfaces on-site. A 30’x9’ gravel filled full infiltration trench is proposed on Lot 3 Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 5 to the west of the proposed structure to mitigate stormwater from impervious areas. An emergency overflow to the public storm system from the infiltration trench will be provided. This report assumes that the maximum impervious surface per zoning (4,327 SF) will be conveyed to this infiltration trench. Please refer to Core Requirement # 9 in Section II and Section IV of this TIR for additional discussion on stormwater BMPs. A Developed Conditions Map is provided as Figure 5 at this end of this Section. N 38TH STREET MEADOW AVENUE NEastern Washington Division 6ZiItZater %OvG ▪ &Oe EOXP W$ ▪ 3hone Western Washington Division 1E -XniSer 6treet 6Xite ▪ ,ssaTXah W$ ▪ 3hone ncompass ENGINEERING & SURVEYING E Know what'sCall below. before you dig. R NORTHEXISTING CONDITIONS AREAS PREDEVELOPED MODELED AREA FIGURE 4 - EXISTING CONDITIONS MAP Eastern Washington Division 6ZiItZater %OvG ▪ &Oe EOXP W$ ▪ 3hone Western Washington Division 1E -XniSer 6treet 6Xite ▪ ,ssaTXah W$ ▪ 3hone ncompassENGINEERING & SURVEYINGEKnow what'sCallbelow.before you dig.RNORTHDEVELOPED CONDITIONS AREAS MITIGATED MODELED AREASFIGURE 5 - DEVELOPED CONDITIONS MAP Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 8 II. CONDITIONS AND REQUIREMENTS SUMMARY The 2017 City of Renton Surface Water Design Manual (RSWDM) was utilized to determine and address all core and special requirements. Based on the criteria specified in Figure 1.1.2.A of the RSWDM, the project falls under Full Drainage Review. Per Section 1.1.2.4 of the RSWDM, the project must meet all nine (9) core and all six (6) special requirements. See Figure 6 below for more information on how the type of drainage review was determined. Figure 6: Drainage Review Flow Chart Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 9 Core Requirements Core Requirement #1: Discharge at the Natural Location The proposed development runoff will follow existing drainage patterns toward the Meadow Ave N storm system or will be fully infiltrated on-site. Refer to the Level 1 Downstream Analysis in Section III of this TIR for a complete description of the existing drainage paths. Core Requirement #2: Downstream Analysis A Level 1 Downstream analysis has been completed for the site and no existing or potential drainage problems have been identified. This analysis is included in Section III of this TIR. Core Requirement #3: Flow Control Facilities Based on the City of Renton’s flow control application map, the project site is located within the Peak Rate Flow Control Standard (Existing Site Conditions). Flow control facilities are required to match the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10- and 100-year return periods. The proposed stormwater BMPs result in a 0.2289 CFS decrease in the 100-year flow using 15- minutes time steps. This is below the allowable threshold of a 0.15 CFS maximum increase per Section 1.2.3.1.B of the RSWDM; therefore, the project meets flow control exemption 2. No formal flow control facilities are proposed at this time; however, flow control BMPs will be implemented as described in Core Requirement #9. Please refer to Section IV of this TIR for additional discussion. Core Requirement #4: Conveyance System Conveyance in compliance with the requirements detailed in Section 1.2.4.1 of the City of Renton 2017 SWDM will be provided with final engineering. Core Requirement #5: Construction Stormwater Pollution Prevention The limits of construction for the project are less than 1 acre. A temporary erosion and sediment control (TESC) plan providing details on best management practices (BMPs) to be implemented during construction is included in the engineering plan set. A Construction Stormwater Pollution Prevention Plan (CSWPPP) will be provided with final engineering. Please refer to Section VIII of this TIR for additional discussion. Core Requirement #6: Maintenance and Operations An Operation and Maintenance Manual will be provided with final engineering. Core Requirement #7: Financial Guarantees and Liability The owner will arrange for any financial guarantees and liabilities required by the permit. Core Requirement #8: Water Quality Facilities In accordance with Section 1.2.8.1.A of the RSWDM, Basic Water Quality Treatment is not required for this project as new plus replaced pollution generating impervious surfaces (PGIS) does not exceed 5,000 SF. The development results in 768 SF of concrete driveway within the ROW dedication area, 485 of pavement replacement within the existing ROW, and 3,700 SF of on- site driveway is estimated for the future build-out of Lots 1-3. These quantities total to 4,953 SF Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 10 of PGIS that will be created or replaced as a result of this project; therefore, the project meets surface area exemption 1. Core Requirement #9: Flow Control BMPs Per section 1.2.9.3.1 of the RSWDM, this project is classified as a small subdivision; therefore, it is subject to the Small Road Improvement and Urban Road Improvement Project BMP Requirements detailed in Section 1.2.9.3.2 in the RSWDM. Although implementation of individual lot BMPs is not required until building permit application, BMPs have been considered for the future improvements on Lots 1-3 based on Section 1.2.9.2 of the RSWDM. See Section IV of this TIR for further discussion and flow control analysis. Impervious Surface BMPs Full Dispersion: Infeasible for Lots 1-3. · Lots 1-3: The space required for a 100-foot native vegetated flowpath segment is not available on these sites. Full Infiltration: Feasible for Lots 1-3. · Lots 1-3: Soil explorations detailed in the Geotechnical Engineering Study by Earth Solutions NW dated March 12, 2020 (Appendix A) encountered primarily medium dense silty sand and poorly graded sand. An in-situ infiltration test was performed and a design infiltration rate of 5 inches per hour was determined which is suitable for stormwater infiltration. Per section C.2.2.3 of the RSWDM, 30 liner feet of 2’ wide trench per 1,000 SF of tributary impervious surface can be used to design full infiltration trenches in coarse sands. A 30’x2’ trench has an infiltration area of 60 SF; therefore, 60 SF of infiltration area is required per 1,000 SF of tributary impervious surface. For Lots 1-3, three infiltration trenches of 30’x9’ are proposed which provides an infiltration area of 270 SF each. A 30’x9’ trench has the ability to mitigate up to (270 SF/60 SF)x1,000 SF= 4500 SF of tributary impervious surface. This allows each trench to mitigate the entire maximum impervious surface coverage for each lot. As an additional safety measure, an emergency overflow to the public storm system from the infiltration trenches will be provided. As all target impervious surfaces on the project site have been mitigated with flow control BMPs, no further BMPs have been considered. Pervious Surface BMPs Soil Amendment: Feasible for Lots 1-3 · Lots 1-3: All disturbed, pervious areas of the project will meet soil amendment requirements as detailed in Section C.2.13 of the RSWDM. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 11 Special Requirements Special Requirement #1: Other Adopted Area-Specific Requirements Critical Drainage Area – N/A Master Drainage Plan – N/A Basin Plan – N/A Lake management Plan – N/A Shared Facility Drainage Plan – N/A Special Requirement #2: Flood Hazard Area Delineation The limits of this project do not lie within a delineated FEMA 100-year floodplain. Special Requirement #3: Flood Protection Facilities This project does not rely on or propose to modify/construct a new flood protection facility. Special Requirement #4: Source controls The project is a single-family residential development; therefore, this requirement is not applicable. Special Requirement #5: Oil Control This project is not considered high-use in need of oil control. Special Requirement #6: Aquifer Protection Area The site is not located within an Aquifer Protection Area Zone per the City of Renton Groundwater Protection Area Map Reference 15-B. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 12 III. DOWNSTREAM ANALYSIS A Level 1 Downstream analysis has been conducted per the requirements in Section 1.2.2.1 of the RSWDM. Please see Tasks 1 through 4 below for a summary of the results. Task 1: Define and Map the Study Area The area of analysis extends from the site discharge points along Meadow Ave N and the eastern limit of the site along the I-405 barrier wall to approximately a quarter-mile downstream where the two discharge areas converge. A Downstream Map is provided in Figure 7 below. Figure 7: Downstream Map Task 2: Review All Available Information on the Study Area Per King county resources, there have been no significant drainage complaints within a quarter-mile downstream of the site. Task 3: Field Inspect the Study Area A field inspection was performed by Encompass Engineering & Surveying on January 26, 2021. Please refer to Task 4 for a detailed description of the downstream drainage system and analysis. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 13 Task 4: Describe the Drainage System Stormwater runoff currently leaves the site at a single natural discharge location at the northwest corner creating one Threshold Discharge Area for the site. The majority of the site gently slopes at approximately 2%, allowing stormwater to sheet flow northwest into Meadow Ave. A cleared area on the adjacent parcel 334270-0630 is tributary to the site. This off-site area and sheet flows to the north over approximately 10-15% slopes onto the existing gravel driveway in the southern portion of the site. Runoff in the southeast portion of the site sheet flows on gravel driveway and grass towards a low point along the I-405 wall on the eastern side of the site (A). From here, stormwater is assumed to infiltrate directly into the soil as no outlet exists. This observation is consistent with type A/B outwash soils found and detailed in the Geotechnical Engineering Study by Earth Solutions NW dated March 12, 2020 (Appendix A). Runoff from the southwestern portion of the site sheets flows towards Meadow Ave N where it enters the City of Renton (COR) storm system in a Type 1 CB (B) on the edge of asphalt. Runoff from the northern portion of the site sheet flows to the north and west, eventually entering Meadow Ave N and entering a Type 1 CB (C) just northwest of the site at the edge of asphalt. The southern of these two Type 1 CBs (B) outlets to the NW through a 10” DI storm pipe into a Type 2 CB approximately 12 feet away (D). From here, stormwater flows to the north through an 18” Poly storm pipe (E) into another Type 2 CB (F). This Type 2 CB collects stormwater from the Type 1 CB (C) just northwest of the site via an 8” DI storm pipe. Stormwater continues north on Meadow Ave N through a series of Type 2 CBs and 18” Poly storm pipe. It turns to the west when it reaches the intersection of Meadow Ave N and N 40th St, and runs westward on N 40th St downhill towards lake Washington. Stormwater continues through a series of Type 2 CBs and 18” poly pipe, through the intersection of N 40th St and Park Ave N, to the intersection of N 40th St and Wells Ave N. The Type 2 CB in this location (G) is where the analysis was completed, just over ¼ mile downstream of the site. Please refer to Figure 7 on the previous page, for the approximate location of identified drainage features. If conveyance system nuisance, severe erosion, severe flooding, or wetland hydrology problems are identified downstream of the site under Core Requirement #2, additional impact analysis and/or mitigation may be required. As discussed in Task 2, there have been no recent significant drainage complaints within a quarter-mile downstream of the site. As no existing drainage or conveyance issues have been recently identified, further impact analysis and mitigation of the downstream stormwater system is not required. Please refer to the conveyance analysis in Section V of this TIR for additional discussion and evaluation of the on-site conveyance system capacity. Photographs from the site visit are included on the pages that follow. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 14 Element A- Low point on eastern side of site by I-405 Wall Element B- Type 1 CB on Meadow Ave N collecting runoff from southern site frontage and yard Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 15 Element C- Type 1 CB on Meadow Ave N collecting water from the northern site frontage and yard Element G- Type 2 CB on N 40th St Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 16 IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN Part A: Existing Site Hydrology The 25,536 SF (0.59 AC) site is currently developed with a single-family residence accessed from Meadow Ave N via two gravel driveways on the west side of the site. The property is located within the May Creek drainage basin. Stormwater runoff currently leaves the site at a single natural discharge location at the northwest corner creating one Threshold Discharge Area for the site. The majority of the site gently slopes at approximately 2%, allowing stormwater to sheet flow northwest into Meadow Ave. A cleared area on the adjacent parcel 334270-0630 is tributary to the site. This off-site area and sheet flows to the north over approximately 10-15% slopes onto the existing gravel driveway in the southern portion of the site. See full downstream analysis in Section III of this Technical Information Report (TIR). Soil explorations detailed in the Geotechnical Engineering Study by Earth Solutions NW dated March 12, 2020 (Appendix A) encountered primarily medium dense silty sand and poorly graded sand. An in-situ infiltration test was performed and a design infiltration rate of 5 inches per hour was determined by the Geotech, which is suitable for stormwater infiltration. WWHM 2012 was used to model the existing condition within the 27,320 SF (0.627 AC) limits of disturbance using existing surfaces found on site including rooftop, driveway, lawn and walkways. See the summary of existing and developed analyses on the following pages, as well as the existing conditions map provided as Figure 4 for more details. Part B: Developed Site Hydrology The project proposes the development of three (3) single-family lots within the 25,536 SF (0.59 Acres) parcel, as well as a 7.5-foot right-of-way dedication with frontage improvements. Lot 1 is 8,230 SF (0.19 AC) and is located in the north portion of the site. Lot 2 is 8,043SF (0.18 Acres) and is located in the central portion of the site. Lot 3 is 7,868 SF (0.18 AC) and is located in the southern portion of the site. All three (3) lots will have driveway access off of Meadow Ave N. Frontage improvements will include the addition of a 5-foot sidewalk, 8-foot planter strip, as well as curb and gutter along the edge of asphalt roadway. Stormwater runoff from the proposed development of Lots 1-3 will be managed as follows: · Lot 1: Stormwater BMP’s satisfying Core Requirement #9 will be used to the maximum extent feasible to mitigate new runoff created by the proposed single-family residence and other impervious surfaces on-site. A 30’x9’ gravel filled full infiltration trench is proposed on Lot 1 to the west of the proposed structure to mitigate stormwater from impervious areas. This report assumes that the maximum impervious surface per zoning (4,527 SF) will be conveyed to this infiltration trench. Additionally, an emergency overflow to the public storm system from the infiltration trench will be provided. · Lot 2: Stormwater BMP’s satisfying Core Requirement #9 will be used to the maximum extent feasible to mitigate new runoff created by the proposed single-family residence and other impervious surfaces on-site. A 30’x9’ gravel filled full infiltration trench is proposed on Lot 2 to the west of the proposed structure to mitigate stormwater from impervious areas. This report assumes that the maximum impervious surface per zoning (4,424 SF) will be conveyed to this infiltration trench. Additionally, an emergency overflow to the public storm system from the infiltration trench will be provided. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 17 · Lot 3: Stormwater BMP’s satisfying Core Requirement #9 will be used to the maximum extent feasible to mitigate new runoff created by the proposed single-family residence and other impervious surfaces on-site. A 30’x9’ gravel filled full infiltration trench is proposed on Lot 3 to the west of the proposed structure to mitigate stormwater from impervious areas. This report assumes that the maximum impervious surface per zoning (4,327 SF) will be conveyed to this infiltration trench. Additionally, an emergency overflow to the public storm system from the infiltration trench will be provided. WWHM 2012 was used to model the proposed condition as follows: · Lot 1: The modeled limits of disturbance for Lot 1 is 8,230 SF. The maximum impervious surface per R-6 zoning of 4,527 SF was assumed, with the entirety of this area being conveyed to the full infiltration trench. Per Table 1.2.9.A in the RSWDM, the area going to full infiltration can be subtracted from the model. The remaining 3,703 SF of pervious surface on Lot 1 will meet soil amendment requirement as detailed in Section C.2.13 of the RSWDM; therefore, it has been modeled as 100% pasture with flat slopes in type A/B soils. · Lot 2: The modeled limits of disturbance for Lot 2 is 8,043 SF. The maximum impervious surface per R-6 zoning of 4,424 SF was assumed, with the entirety of this area being conveyed to the full infiltration trench. Per Table 1.2.9.A in the RSWDM, the area going to full infiltration can be subtracted from the model. The remaining 3,619 SF of pervious surface on Lot 1 will meet soil amendment requirement as detailed in Section C.2.13 of the RSWDM; therefore, it has been modeled as 100% pasture with flat slopes in type A/B soils. · Lot 3: The modeled limits of disturbance for Lot 3 is 7,868 SF. The maximum impervious surface per R-6 zoning of 4,327 SF was assumed, with the entirety of this area being conveyed to the full infiltration trench. Per Table 1.2.9.A in the RSWDM, the area going to full infiltration can be subtracted from the model. The remaining 3,541 SF of pervious surface on Lot 1 will meet soil amendment requirement as detailed in Section C.2.13 of the RSWDM; therefore, it has been modeled as 100% pasture with flat slopes in type A/B soils. · ROW Dedication & Road Widening: The modeled limits of disturbance for the ROW dedication area and road widening is 2,995 SF. This will include 838 SF of sidewalk, 768 SF of driveway entrance as well as 485 SF of asphalt road repair. The remaining 904 SF of pervious surface will meet soil amendment requirement as detailed in Section C.2.13 of the RSWDM; therefore, it has been modeled as 100% pasture with moderate slopes in type C soils. Please refer to Core Requirement #9 in Section II of the TIR for additional discussion. A Developed Conditions Map is provided as Figure 5. A summary of the existing and developed analyses is provided in the table on the following page. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 18 On-site + Off-Site Existing Proposed Condition Measured Modeled Measured Modeled Lawn, Mod: 14,050 SF (0.322 AC) 14,050 SF (0.322 AC) 11,850 (0.272 AC) Pasture, Mod: 11,850 (0.272 AC) Roof, Flat: 1,995 SF (0.046 AC) 1,995 SF (0.046 AC) 9,729 SF (0.223 AC) Driveway, Flat: 10,122 SF (0.232 AC) 10,122 SF (0.232 AC) 4,418 SF (0.101 AC) 768 SF (0.018 AC) Sidewalk, Flat: 719 (0.017 AC) 719 (0.017 AC) 838 SF (0.019 AC) 838 SF (0.019 AC) Road, Flat: 434 SF (0.010 AC) 434 SF (0.010 AC) 485 SF (0.011 AC) 485 SF (0.011 AC) Total Area: 27,320 SF (0.627 AC) 27,320 SF (0.627 AC) 27,320 SF (0.627 AC) 13,941 SF (0.320 AC) Part C: Performance Standards Based on the City of Renton’s flow control map, the project site is located within the Peak Rate Flow Control Standard (Existing Site Conditions). Flow control facilities are required to match the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10- and 100-year return periods. However, as determined in Part D on the following page, the site meets flow control exemption 2 per Section 1.2.3.1.B of the RSWDM, and flow control facilities are not required. Per section 1.2.9.3.1 of the RSWDM, this project is classified as a small subdivision; therefore, it is subject to the Small Road Improvement and Urban Road Improvement Project BMP Requirements detailed in Section 1.2.9.3.2 in the RSWDM. The site falls within a Basic Water Quality treatment area in accordance with Section 1.2.8.1.A of the RSWDM, however new plus replaced impervious pollution generating areas within the project site is under 5,000 SF. Therefore, water quality treatment is not required. Part D: Flow Control System As shown in the table below, the proposed stormwater BMPs result in a 0.2289 CFS decrease in the 100- year flow using 15-minutes time steps. This is below the allowable threshold of a 0.15 CFS maximum increase per Section 1.2.3.1.B of the RSWDM; therefore, the project meets flow control exemption 2. No formal flow control facilities are proposed at this time; however, flow control BMPs will be implemented as described in Core Requirement #9 in Section II of this TIR. Please refer to Appendix B for a copy of the full WWHM data output. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 19 Part E: Water Quality System In accordance with Section 1.2.8.1.A of the RSWDM, Basic Water Quality Treatment is not required for this project as new plus replaced pollution generating impervious surfaces (PGIS) does not exceed 5,000 SF. The development results in 768 SF of concrete driveway within the ROW dedication area, 485 SF of pavement replacement within the existing ROW, and 3,700 SF of on-site driveway is estimated for the future build-out of Lots 1-3. These quantities total to 4,953 SF of PGIS that will be created or replaced as a result of this project; therefore, the project meets surface area exemption 1. Meadow Ave Short Plat Preliminary Technical Information Report 8/12/2025 P a g e | 20 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN This project is using infiltration using the BMP prescriptive method. Rainwater infiltrates and the pipes are provided for emergency overflow. Therefore, this project does not warrant conveyance analysis. VI. SPECIAL REPORTS AND STUDIES · Geotechnical Engineering Study by Earth Solutions NW dated March 12, 2020 · Arborist Report/Tree Plan by Layton Tree Consulting, LLC dated February 12, 2020 VII. OTHER PERMITS · Civil Construction Permit · Final Short Plat · Building Permits · Right-of-Way Use Permit VIII. CSWPP ANALYSIS AND DESIGN See Appendix D. IX. BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION of COVENANT See Appendix E X. OPERATION AND MAINTENANCE MANUAL See Appendix F Appendix A Geotechnical Engineering Study by Earth Solutions NW dated March 12, 2020 EarthSolutionsNWLLC EarthSolutionsNWLLC 15365 N.E. 90th Street, Suite 100 Redmond, WA98052 (425) 449-4704 Fax (425) 449-4711 www.earthsolutionsnw.com Geotechnical Engineering Construction Observation/Testing Environmental Services GEOTECHNICAL ENGINEERING STUDY PROPOSED SHORT PLAT 3804 MEADOW AVENUE NORTH RENTON, WASHINGTON ES-7126 PREPARED FOR MR. HUY NGUYEN March 12, 2020 _________________________ Brian C. Snow, G.I.T. Staff Geologist _________________________ Keven D. Hoffmann, P.E. Senior Project Manager GEOTECHNICAL ENGINEERING STUDY PROPOSED SHORT PLAT 3804 MEADOW AVENUE NORTH RENTON, WASHINGTON ES-7126 Earth Solutions NW, LLC 15365 Northeast 90th Street, Suite 100 Redmond, Washington 98052 Phone: 425-449-4704 | Fax: 425-449-4711 www.earthsolutionsnw.com 03/16/2020 Geotechnical-Engineering Report Important Information about This Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help. The Geoprofessional Business Association (GBA) has prepared this advisory to help you – assumedly a client representative – interpret and apply this geotechnical-engineering report as effectively as possible. In that way, you can benefit from a lowered exposure to problems associated with subsurface conditions at project sites and development of them that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed herein, contact your GBA-member geotechnical engineer. Active engagement in GBA exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Understand the Geotechnical-Engineering Services Provided for this ReportGeotechnical-engineering services typically include the planning, collection, interpretation, and analysis of exploratory data from widely spaced borings and/or test pits. Field data are combined with results from laboratory tests of soil and rock samples obtained from field exploration (if applicable), observations made during site reconnaissance, and historical information to form one or more models of the expected subsurface conditions beneath the site. Local geology and alterations of the site surface and subsurface by previous and proposed construction are also important considerations. Geotechnical engineers apply their engineering training, experience, and judgment to adapt the requirements of the prospective project to the subsurface model(s). Estimates are made of the subsurface conditions that will likely be exposed during construction as well as the expected performance of foundations and other structures being planned and/or affected by construction activities. The culmination of these geotechnical-engineering services is typically a geotechnical-engineering report providing the data obtained, a discussion of the subsurface model(s), the engineering and geologic engineering assessments and analyses made, and the recommendations developed to satisfy the given requirements of the project. These reports may be titled investigations, explorations, studies, assessments, or evaluations. Regardless of the title used, the geotechnical-engineering report is an engineering interpretation of the subsurface conditions within the context of the project and does not represent a close examination, systematic inquiry, or thorough investigation of all site and subsurface conditions. Geotechnical-Engineering Services are Performed for Specific Purposes, Persons, and Projects, and At Specific TimesGeotechnical engineers structure their services to meet the specific needs, goals, and risk management preferences of their clients. A geotechnical-engineering study conducted for a given civil engineer will not likely meet the needs of a civil-works constructor or even a different civil engineer. Because each geotechnical-engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. Likewise, geotechnical-engineering services are performed for a specific project and purpose. For example, it is unlikely that a geotechnical- engineering study for a refrigerated warehouse will be the same as one prepared for a parking garage; and a few borings drilled during a preliminary study to evaluate site feasibility will not be adequate to develop geotechnical design recommendations for the project. Do not rely on this report if your geotechnical engineer prepared it: • for a different client; • for a different project or purpose; • for a different site (that may or may not include all or a portion of the original site); or • before important events occurred at the site or adjacent to it; e.g., man-made events like construction or environmental remediation, or natural events like floods, droughts, earthquakes, or groundwater fluctuations. Note, too, the reliability of a geotechnical-engineering report can be affected by the passage of time, because of factors like changed subsurface conditions; new or modified codes, standards, or regulations; or new techniques or tools. If you are the least bit uncertain about the continued reliability of this report, contact your geotechnical engineer before applying the recommendations in it. A minor amount of additional testing or analysis after the passage of time – if any is required at all – could prevent major problems. Read this Report in Full Costly problems have occurred because those relying on a geotechnical- engineering report did not read the report in its entirety. Do not rely on an executive summary. Do not read selective elements only. Read and refer to the report in full. You Need to Inform Your Geotechnical Engineer About Change Your geotechnical engineer considered unique, project-specific factors when developing the scope of study behind this report and developing the confirmation-dependent recommendations the report conveys. Typical changes that could erode the reliability of this report include those that affect: • the site’s size or shape; • the elevation, configuration, location, orientation, function or weight of the proposed structure and the desired performance criteria; • the composition of the design team; or • project ownership. As a general rule, always inform your geotechnical engineer of project or site changes – even minor ones – and request an assessment of their impact. The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered. Most of the “Findings” Related in This Report Are Professional Opinions Before construction begins, geotechnical engineers explore a site’s subsurface using various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing is performed. The data derived from that sampling and testing were reviewed by your geotechnical engineer, who then applied professional judgement to form opinions about subsurface conditions throughout the site. Actual sitewide-subsurface conditions may differ – maybe significantly – from those indicated in this report. Confront that risk by retaining your geotechnical engineer to serve on the design team through project completion to obtain informed guidance quickly, whenever needed. This Report’s Recommendations Are Confirmation-Dependent The recommendations included in this report – including any options or alternatives – are confirmation-dependent. In other words, they are not final, because the geotechnical engineer who developed them relied heavily on judgement and opinion to do so. Your geotechnical engineer can finalize the recommendations only after observing actual subsurface conditions exposed during construction. If through observation your geotechnical engineer confirms that the conditions assumed to exist actually do exist, the recommendations can be relied upon, assuming no other changes have occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation-dependent recommendations if you fail to retain that engineer to perform construction observation. This Report Could Be Misinterpreted Other design professionals’ misinterpretation of geotechnical- engineering reports has resulted in costly problems. Confront that risk by having your geotechnical engineer serve as a continuing member of the design team, to: • confer with other design-team members; • help develop specifications; • review pertinent elements of other design professionals’ plans and specifications; and • be available whenever geotechnical-engineering guidance is needed. You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction-phase observations. Give Constructors a Complete Report and GuidanceSome owners and design professionals mistakenly believe they can shift unanticipated-subsurface-conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note conspicuously that you’ve included the material for information purposes only. To avoid misunderstanding, you may also want to note that “informational purposes” means constructors have no right to rely on the interpretations, opinions, conclusions, or recommendations in the report. Be certain that constructors know they may learn about specific project requirements, including options selected from the report, only from the design drawings and specifications. Remind constructors that they may perform their own studies if they want to, and be sure to allow enough time to permit them to do so. Only then might you be in a position to give constructors the information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Conducting prebid and preconstruction conferences can also be valuable in this respect. Read Responsibility Provisions Closely Some client representatives, design professionals, and constructors do not realize that geotechnical engineering is far less exact than other engineering disciplines. This happens in part because soil and rock on project sites are typically heterogeneous and not manufactured materials with well-defined engineering properties like steel and concrete. That lack of understanding has nurtured unrealistic expectations that have resulted in disappointments, delays, cost overruns, claims, and disputes. To confront that risk, geotechnical engineers commonly include explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The personnel, equipment, and techniques used to perform an environmental study – e.g., a “phase-one” or “phase-two” environmental site assessment – differ significantly from those used to perform a geotechnical-engineering study. For that reason, a geotechnical-engineering report does not usually provide environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not obtained your own environmental information about the project site, ask your geotechnical consultant for a recommendation on how to find environmental risk-management guidance. Obtain Professional Assistance to Deal with Moisture Infiltration and Mold While your geotechnical engineer may have addressed groundwater, water infiltration, or similar issues in this report, the engineer’s services were not designed, conducted, or intended to prevent migration of moisture – including water vapor – from the soil through building slabs and walls and into the building interior, where it can cause mold growth and material-performance deficiencies. Accordingly, proper implementation of the geotechnical engineer’s recommendations will not of itself be sufficient to prevent moisture infiltration. Confront the risk of moisture infiltration by including building-envelope or mold specialists on the design team. Geotechnical engineers are not building-envelope or mold specialists. Copyright 2019 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent or intentional (fraudulent) misrepresentation. Telephone: 301/565-2733 e-mail: info@geoprofessional.org www.geoprofessional.org March 12, 2020 ES-7126 Mr. Huy Nguyen 15400 Southeast 155th Place, Unit 99 Renton, Washington 98058 Dear Mr. Nguyen: Earth Solutions NW, LLC (ESNW), is pleased to present this geotechnical report for the subject site. While specific site plans were not available at the time of this report, we presume the site will be developed into a short plat, comprised of several two- to three-story residential structures and related infrastructure improvements. Based on the results of our study, construction of a short plat is feasible from a geotechnical standpoint. Based on the conditions observed during the fieldwork, the subject site is underlain primarily by medium dense recessional outwash deposits. The proposed structures can be supported on conventional spread and continuous foundations bearing on undisturbed competent native soil, recompacted native soil, or new structural fill. We anticipate competent native soil suitable for support of foundations will be encountered beginning at depths of about two to four feet below existing grades across the site. This report provides geotechnical analyses and recommendations for the proposed short plat. The opportunity to be of service to you is appreciated. If you have any questions regarding the content of this geotechnical engineering study, please call. Sincerely, EARTH SOLUTIONS NW, LLC Brian C. Snow, G.I.T. Staff Geologist 15365 N.E. 90th Street, Suite 100 • Redmond, WA 98052 •(425) 449-4704 • FAX (425) 449-4711 Earth Solutions NW LLC Geotechnical Engineering, Construction Observation/Testing and Environmental Services Earth Solutions NW, LLC Table of Contents ES-7126 PAGE INTRODUCTION ................................................................................. 1 General..................................................................................... 1 Project Description ................................................................. 2 SITE CONDITIONS ............................................................................. 2 Surface ..................................................................................... 2 Subsurface .............................................................................. 2 Topsoil and Fill ............................................................. 2 Native Soil ..................................................................... 3 Geologic Setting ........................................................... 3 Groundwater ................................................................. 3 GEOLOGICALLY HAZARDOUS AREAS EVALUATION .................. 3 Erosion Hazard ........................................................................ 4 Landslide Hazard .................................................................... 4 Regulated Slopes .................................................................... 5 Seismic Hazard ....................................................................... 5 Analysis of Proposal .............................................................. 6 DISCUSSION AND RECOMMENDATIONS ....................................... 6 General..................................................................................... 6 Site Preparation and Earthwork ............................................. 6 Temporary Erosion Control ......................................... 6 In-Situ and Imported Soil ............................................. 6 Structural Fill ................................................................ 7 Subgrade Preparation .................................................. 7 Excavations and Slopes .............................................. 7 Foundations ............................................................................ 8 Seismic Design ....................................................................... 9 Slab-on-Grade Floors ............................................................. 9 Retaining Walls ....................................................................... 9 Drainage................................................................................... 10 Infiltration Evaluation ................................................... 10 Utility Support and Trench Backfill ....................................... 11 LIMITATIONS ...................................................................................... 11 Additional Services ................................................................. 11 Earth Solutions NW, LLC Table of Contents Continued ES-7126 GRAPHICS Plate 1 Vicinity Map Plate 2 Test Pit Location Plan Plate 3 Retaining Wall Drainage Detail Plate 4 Footing Drain Detail APPENDICES Appendix A Subsurface Exploration Test Pit Logs Appendix B Laboratory Test Results Earth Solutions NW, LLC GEOTECHNICAL ENGINEERING STUDY PROPOSED SHORT PLAT 3804 MEADOW AVENUE NORTH RENTON, WASHINGTON ES-7126 INTRODUCTION General This geotechnical engineering study (study) was prepared for the proposed short plat to be constructed on the east side of Meadow Avenue North, nearest the intersection with North 38th Street, in the Kennydale neighborhood of Renton, Washington. To complete the scope of services, we performed the following: Subsurface exploration to characterize the soil and groundwater conditions; In-situ infiltration testing; Laboratory testing of representative soil samples collected on site; Review of on-site geologically hazardous areas; Engineering analyses and recommendations for the proposed short plat, and; Preparation of this report. The following documents and resources were reviewed as part of our report preparation: Preliminary Geologic Map of Seattle and Vicinity, Washington, compiled by H.H. Waldron et al., dated 1961; Web Soil Survey (WSS) online resource, maintained by the Natural Resources Conservation Service (NRCS) under the United States Department of Agriculture (USDA); Soil Survey of Snoqualmie Pass Area, Parts of King and Pierce Counties, Washington, prepared by the United States Department of Agriculture Soil Conservation Service, dated 1990; Soil Survey of King County Area, Washington, prepared by the United States Department of Agriculture Soil Conservation Service, dated 1973; Liquefaction Susceptibility Map 11-5, prepared by the King County Flood Control District, dated May 2010; Renton Municipal Code (RMC); City of Renton Critical Areas Map: Online “COR Maps”, and; City of Renton Surface Water Design Manual. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 2 Earth Solutions NW, LLC Project Description We understand the proposed project will likely consist of constructing a three-lot short plat and associated improvements. At the time this report was prepared, neither site plans nor building load values were available for review. However, we anticipate the proposed residential structures will be two to three stories and constructed using relatively lightly loaded wood framing supported atop conventional foundation systems. Based on our experience with similar developments, we estimate wall loads of about 1 to 2 kips per linear foot and slab-on-grade loading of 150 pounds per square foot (psf) will be incorporated into final designs. Grade cuts and fills to establish individual-lot subgrade and finish grade elevations are expected to be less than five feet. Stormwater management will presumably use infiltration to the extent feasible. If the above design assumptions are incorrect or change, ESNW should be contacted to review the recommendations provided in this report. ESNW should review the final designs to verify the geotechnical recommendations provided in this report have been incorporated into the plans. SITE CONDITIONS Surface The subject site is located northeast of the intersection between North 38th Street and Meadow Avenue North, in Renton, Washington. The approximate location of the property is illustrated on Plate 1 (Vicinity Map). The site is comprised of one tax parcel (King County Parcel No. 334270- 0570), totaling about 0.59 acres. The site is currently developed with a single-family residence and a detached shed structure. The existing topography is relatively level, with less than two feet of elevation change across the site. To the east of the sound barrier wall, grades descend sharply to the Interstate 405 corridor. Subsurface An ESNW representative observed, logged, and sampled five test pits on February 17, 2020. The test pits were excavated at accessible locations within the property, using a mini-trackhoe and operator retained by our firm. The approximate locations of the test pits are depicted on Plate 2 (Test Pit Location Plan). Please refer to the test pit logs provided in Appendix A for a more detailed description of subsurface conditions. Representative soil samples collected at the test pit locations were analyzed in general accordance with Unified Soil Classification System (USCS) and USDA methods and procedures. Topsoil and Fill Topsoil was generally encountered within the upper 6 to 42 inches of existing grades where test pits were excavated. In some instances, relic topsoil horizons were observed beneath fill soil. The topsoil was characterized by a dark brown color, the presence of fine organic material, and small root intrusions. Root zones extended between about four to five feet below the existing ground surface (bgs). Mr. Huy Nguyen ES-7126 March 12, 2020 Page 3 Earth Solutions NW, LLC Fill was observed at test pit locations TP-1, TP-2, TP-3, and TP-4, extending to a maximum depth of about five feet bgs. The fill soil generally consisted of tan silty sand with minor interbedded topsoil. In TP-4, rebar, plastic bags, and wood debris was observed. Native Soil Underlying the topsoil and fill, the native soil consisted primarily of medium dense silty sand and poorly graded sand with variable silt and gravel content (USCS: SM, SP, and SP-SM). The native deposits were primarily observed in a wet condition at the time of our exploration, and weak iron oxide staining was noted at several locations. The maximum exploration depth was roughly nine feet bgs. Geologic Setting Geologic mapping of the area indicates the site is underlain by younger gravel (Qyg) and younger sand (Qys) as part of the Vashon recessional outwash series. Recessional outwash was deposited by glacial meltwater and is readily comprised of silt, clay, sand, and gravel. The referenced WSS resource identifies Indianola loamy sand (Map Unit Symbol: InC) across the majority of the site, with Norma sandy loam (Map Unit Symbol: No) mapped along the eastern edge. The Indianola loamy sands were formed in eskers, kames, and terraces, and the Norma sandy loams were formed in flood plains. Based on our field observations, the native soil on site is generally consistent with the geologic and soil mapping resources outlined in this section. Groundwater During the subsurface exploration, perched groundwater seepage was encountered at test pit locations TP-3 and TP-4 at eight-and-one-half and five-and-one-half feet bgs, respectively. Groundwater seepage may be encountered within site excavations depending on the time of year and extent of grading activities. Seepage rates and elevations fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater flow rates are higher during the winter, spring, and early summer months. GEOLOGICALLY HAZARDOUS AREAS EVALUATION To evaluate geologically hazardous areas, we reviewed Chapter 4-3 of the City of Renton (City) Municipal Code (RMC). The RMC provides designation and definition criteria for identifying specific geologically hazardous areas and developing appropriate site development plans which will not adversely impact the site or surrounding properties. According to the referenced City Critical Areas Map, erosion hazards, landslide hazards, and regulated slopes are all mapped within 50 feet of the subject site. The mapped hazards are largely associated with the hillslope east of the subject site (outside of the property boundaries) and bordering Interstate 405. Additionally, a seismic hazard area is mapped within 500 feet of the subject site. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 4 Earth Solutions NW, LLC Erosion Hazard According to RMC 4-3-050G5c, erosion hazard areas can be defined as: i. Low Erosion Hazard (EL): Areas with soils characterized by the NRCS as having slight or moderate erosion potential and a slope less than 15 percent. ii. High Erosion Hazard (EH): Areas with soils characterized by the NRCS as having severe or very severe erosion potential and a slope greater than 15 percent. The referenced City Critical Areas Map designates a high erosion hazard on the eastern slope of the site (bordering Interstate 405). The site soils are predominantly mapped as Indianola loamy sand (Map Unit Symbol: InC), with Norma sandy loam (Map Unit Symbol: No) along the eastern edge. The USDA SCS 1973 King County Soils Survey classifies the erosion hazard of Indianola soils as slight to moderate. The USDA SCS 1990 Snoqualmie Pass Area Soil Survey states there is no hazard of erosion associated with Norma soils. In our opinion, given that the site topography is relatively level, the site soils within the proposed development areas generally exhibit low erosivity potential in a typical construction setting. Best Management Practices (BMPs), in general accordance with City surface water and stormwater regulations, should be used for site design and development. At a minimum, silt fencing should be placed along the entire development envelope, and soil stockpiles should be covered when not in use. If construction occurs during periods of wet weather, methods to control surface water runoff will likely be necessary. Construction entrances should be surfaced with quarry spalls to minimize off-site tracking of silt and soil generated during site construction. Landslide Hazard Per RMC 4-3-050G5b, landslide hazard areas can be defined as: i. Low Landslide Hazard (LL): Areas with slopes less than 15 percent. ii. Medium Landslide Hazard (LM): Areas with slopes between 15 percent and 40 percent, underlain by soils that consist largely of sand, gravel, or glacial till. iii. High Landslide Hazards (LH): Areas with slopes greater than 40 percent and areas with slopes between 15 percent and 40 percent underlain by soils consisting largely of silt and clay. iv. Very High Landslide Hazards (LV): Areas of known mapped or identified landslide deposits. The referenced City Critical Areas Map designates a landslide hazard on the eastern slope bordering Interstate 405. In our opinion, given that the slope is largely vegetated with blackberries, trees, and other shrubs; has a slope of about 31 percent; and is outside of the proposed development area, the landslide hazard may be characterized as low to medium. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 5 Earth Solutions NW, LLC Regulated Slopes According to RMC 4-3-050G5a, steep slopes may be categorized into two types: i. Sensitive Slopes: A hillside, or portion thereof (excluding engineering retaining walls), characterized by: a. An average slope of 25 percent to less than 40 percent, as identified in the City Steep Slope Atlas or in a method approved by the City, or; b. An average slope of 40 percent or greater, with a vertical rise of less than 15 feet, as identified in the City Steep Slope Atlas or in a method approved by the City; c. Abutting an average slope of 25 percent to 40 percent, as identified in the City Steep Slope Atlas or in a method approved by the City. ii. Protected Slopes: A hillside, or portion thereof, characterized by an average slope of 40 percent or greater grade and having a minimum vertical rise of 15 feet, as identified in the City Steep Slope Atlas or in a method approved by the City. The referenced City Critical Areas Map designates portions of the eastern slope both as sensitive and protected slopes. Because the eastern slope is located outside of and well away from the anticipated grading and construction activities, it is our opinion that the designations of sensitive and/or protected slopes on site should not impact the proposed short plat from a geotechnical standpoint. Seismic Hazard Per RMC 4-3-050G5d, seismic hazard areas can be defined as: i. Low Seismic Hazard (SL): Areas underlain by dense soils or bedrock. These soils generally have site classifications of A through D, as defined in the 2012 International Building Code (2012 IBC). ii. High Seismic Hazard (SH): Areas underlain by soft or loose, saturated soils. These soils generally have site classifications E or F, as defined in the 2012 IBC. The referenced City Critical Areas Map designates a seismic hazard area approximately 260 feet to the east of the subject site. Based on the conditions observed during our subsurface exploration and the lack of an established, shallow groundwater table, it is our opinion that the seismic hazard on site is low. The referenced Liquefaction Susceptibility Map identifies low potential for liquefaction at the subject site. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 6 Earth Solutions NW, LLC Analysis of Proposal ESNW should be contacted to review both the preliminary and final project plans to further evaluate the proposed construction and any potential impacts to geologically hazardous areas. If more significant grading activities or larger-than-anticipated residential structures are proposed, ESNW should reevaluate the potential impacts to the adjacent hazard areas. DISCUSSION AND RECOMMENDATIONS General Based on the results of our investigation, construction of the proposed short plat is feasible from a geotechnical standpoint. The primary geotechnical considerations associated with the proposed development include site preparation and earthwork, suitability of on-site soil as structural fill, subgrade preparation, temporary excavations, building foundations, retaining walls, drainage, and infiltration feasibility. Site Preparation and Earthwork Site preparation activities should consist of installing temporary erosion control measures and performing site stripping within the designated clearing limits. Subsequent earthwork activities may involve infrastructure and utility installations. Temporary Erosion Control Erosion control measures should conform to the standards and requirements of the Washington State Department of Ecology, King County, and City, where applicable. Please refer to the Erosion Hazard section of this report for a more detailed discussion on recommended temporary erosion and sediment control measures during construction. In-Situ and Imported Soil The majority of the soils encountered during our subsurface exploration have a moderate to high sensitivity to moisture and were generally in a wet condition at the time of exploration. The soils anticipated to be exposed at this site will degrade if exposed to wet weather and construction traffic. Compaction of the soils to the levels necessary for use as structural fill may be difficult or impossible during wet weather conditions. Soils encountered during site excavations that are excessively over the optimum moisture content will likely require aeration or treatment prior to placement and compaction. Conversely, soils that are substantially below the optimum moisture content will require moisture conditioning through the addition of water prior to use as structural fill. An ESNW representative should determine the suitability of in-situ soils for use as structural fill at the time of construction. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 7 Earth Solutions NW, LLC Imported soil intended for use as structural fill should be evaluated by ESNW during construction. The imported soil must be workable to the optimum moisture content, as determined by the Modified Proctor Method (ASTM D1557), at the time of placement and compaction. During wet weather conditions, imported soil intended for use as structural fill should consist of a well-graded, granular soil with a fines content of 5 percent or less (where the fines content is defined as the percent passing the Number 200 sieve, based on the minus three-quarter-inch fraction). Structural Fill Structural fill is defined as compacted soil placed in foundation, slab-on-grade, roadway, permanent slope, retaining wall, and utility trench backfill areas. Structural fill placed and compacted during site grading activities should meet the following specifications and guidelines: Structural fill material Granular soil* Moisture content At or slightly above optimum** Relative compaction (minimum) 95 percent (Modified Proctor) Loose lift thickness (maximum) 12 inches * The existing soil may not be suitable for use as structural fill unless the soil is at (or slightly above) the optimum moisture content at the time of placement and compaction ** Soil shall not be placed dry of optimum and should be evaluated by ESNW during construction With respect to underground utility installations and backfill, local jurisdictions may dictate the soil type(s) and compaction requirements. Areas of otherwise unsuitable material and debris should be removed from structural areas and replaced with structural fill. Subgrade Preparation Following site stripping, ESNW should observe the subgrade to confirm soil conditions are as anticipated and to provide supplementary recommendations for subgrade preparation as necessary. In general, foundation subgrade surfaces should be compacted in situ to a minimum depth of one foot below the design subgrade elevation. Uniform compaction of the foundation and slab subgrade areas will establish a relatively consistent subgrade condition below the foundation and slab elements. Supplementary recommendations for subgrade improvement may be provided at the time of construction and would likely include further mechanical compaction or overexcavation and replacement with suitable structural fill. Excavations and Slopes Excavation activities on site are likely to expose loose to medium dense native soil beginning at depths of approximately two to four feet bgs. Based on the soil conditions observed at the subsurface exploration locations, the following maximum allowable temporary slope inclinations may be used. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 8 Earth Solutions NW, LLC The applicable Federal Occupation Safety and Health Administration and Washington Industrial Safety and Health Act soil classifications are also provided: Areas exposing groundwater seepage 1.5H:1V (Type C) Loose soil; fill 1.5H:1V (Type C) Medium dense to dense native soil 1H:1V (Type B) Permanent slopes should be planted with vegetation to both enhance stability and minimize erosion and should maintain a gradient of 2H:1V or flatter. The presence of perched groundwater may cause localized sloughing of temporary slopes. An ESNW representative should observe temporary and permanent slopes to confirm the slope inclinations are suitable for the exposed soil conditions and to provide additional excavation and slope recommendations as necessary. If the recommended temporary slope inclinations cannot be achieved, temporary shoring may be necessary to support excavations. Foundations The proposed residential structures can be supported on conventional spread and continuous footings bearing on undisturbed competent native soil, compacted native soil, or new structural fill. We anticipate competent native soil suitable for support of foundations will be encountered at a depth of about two to four feet below existing grades. Where loose or unsuitable soil conditions are encountered at foundation subgrade elevations, compaction of the soils to the specifications of structural fill or overexcavation and replacement with suitable structural fill will likely be necessary. Provided the structure will be supported as described above, the following parameters may be used for design of the new foundations: Allowable soil bearing capacity 2,500 psf Passive earth pressure 300 pcf Coefficient of friction 0.40 A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind and seismic loading conditions. The passive earth pressure and coefficient of friction values include a safety factor of 1.5. With structural loading as expected, total settlement in the range of one inch is anticipated, with differential settlement of about one-half inch. The majority of the settlement should occur during construction when dead loads are applied. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 9 Earth Solutions NW, LLC Seismic Design The 2015 IBC recognizes the American Society of Civil Engineers (ASCE) for seismic site class definitions. In accordance with Table 20.3-1 of the ASCE Minimum Design Loads for Buildings and Other Structures Manual, Site Class D should be used for design. Please refer to the Seismic Hazard section of this report for an opinion of the site-specific seismic hazard. Slab-on-Grade Floors Slab-on-grade floors should be supported on a firm and unyielding subgrade consisting of competent native soil or at least 12 inches of new structural fill. Unstable or yielding areas of the subgrade should be recompacted or overexcavated and replaced with suitable structural fill prior to slab construction. A capillary break consisting of a minimum of four inches of free-draining crushed rock or gravel should be placed below the slab. The free-draining material should have a fines content of 5 percent or less defined as the percent passing the number 200 sieve, based on the minus three- quarters-inch fraction. In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should be considered. If used, the vapor barrier should consist of a material specifically designed to function as a vapor barrier and should be installed in accordance with the manufacturer’s specifications. Retaining Walls Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The following parameters may be used for retaining wall design: Active earth pressure (unrestrained condition) 35 pcf At-rest earth pressure (restrained condition) 55 pcf Traffic surcharge (passenger vehicles) 70 psf (rectangular distribution) Passive earth pressure 300 pcf Coefficient of friction 0.40 Seismic surcharge 6H psf* * Where H equals the retained height (in feet) The passive earth pressure and coefficient of friction values include a safety factor of 1.5. Additional surcharge loading from adjacent foundations, sloped backfill, or other loads should be included in the retaining wall design. Drainage should be provided behind retaining walls such that hydrostatic pressures do not develop. If drainage is not provided, hydrostatic pressures should be included in the wall design. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 10 Earth Solutions NW, LLC Retaining walls should be backfilled with free-draining material that extends along the height of the wall and a distance of at least 18 inches behind the wall. The upper 12 inches of the wall backfill may consist of a less permeable soil, if desired. A perforated drainpipe should be placed along the base of the wall and connected to an approved discharge location. A typical retaining wall drainage detail is provided on Plate 3. If drainage is not provided, hydrostatic pressures should be included in the wall design. Drainage Discrete zones of perched groundwater seepage should be anticipated in site excavations depending on the time of year grading operations take place. Temporary measures to control surface water runoff and groundwater during construction would likely involve interceptor trenches, interceptor swales, and sumps. ESNW should be consulted during preliminary grading to both identify areas of seepage and provide recommendations to reduce the potential for seepage-related instability. Finish grades must be designed to direct surface drain water away from structures and slopes. Water must not be allowed to pond adjacent to structures or slopes. In our opinion, foundation drains should be installed along building perimeter footings. A typical foundation drain detail is provided on Plate 4. Infiltration Evaluation In accordance with the 2017 City of Renton Surface Water Design Manual (2017 RSWDM), a small-scale Pilot Infiltration Test (PIT) was completed at test pit location TP-2. The PIT was completed by excavating a roughly three-foot by four-foot (infiltration surface) test pit to a depth of about three and one-half feet bgs and following the prescribed PIT procedure as outlined in the 2017 RSWDM. Based on the results of the PIT, the following design parameters are recommended: Measured infiltration rate 10 inches per hour (iph) Total correction factor 0.5 Design infiltration rate 5 iph The correction factor of 0.5 was selected based on the guidelines provided in the 2017 RSWDM. In our opinion, a correction factor of 0.5 is suitable for the observed conditions at the testing location. At this time, the design infiltration rate of 5 iph is applicable only at the location of TP-2 and only at the infiltration test depth. ESNW should be contacted to review stormwater management plans if infiltration is used for design. Supplementary recommendations and/or testing may be necessary depending on the size, depth, and siting of infiltration facilities. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 11 Earth Solutions NW, LLC Utility Support and Trench Backfill The soils observed at the subsurface exploration locations are generally suitable for support of utilities. Use of the native soil as structural backfill in the utility trench excavations will depend on the in-situ moisture content at the time of placement and compaction. If native soil is placed below the optimum moisture content, settlement will likely occur once wet weather impacts the trenches. Native soil will be difficult or impossible to use as utility trench backfill during wet weather conditions. Moisture conditioning or treatment of the soils may be necessary at some locations prior to use as structural fill. Utility trench backfill should be placed and compacted to the specifications of structural fill provided in this report or to the applicable requirements of the presiding jurisdiction. LIMITATIONS This study has been prepared for the exclusive use of Mr. Huy Nguyen and his representatives. The recommendations and conclusions provided in the geotechnical engineering study are professional opinions consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. A warranty is not expressed or implied. Variations in the soil and groundwater conditions observed at the test locations may exist and may not become evident until construction. ESNW should reevaluate the conclusions provided in this geotechnical engineering study if variations are encountered. Additional Services ESNW should have an opportunity to review the final design with respect to the geotechnical recommendations provided in this report. ESNW should also be retained to provided testing and consultation services during construction. Drwn. MRS Checked BCS Date Mar. 2020 Date 03/13/2020 Proj. No. 7126 Plate 1 Earth Solutions NWLLC Geotechnical Engineering,Construction EarthSolutionsNWLLC EarthSolutionsNWLLC Observation/Testing and Environmental Services Vicinity Map Meadow Avenue Short Plat Renton, Washington Reference: King County, Washington OpenStreetMap.org NORTH NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. SITE Newcastle Renton Drwn. MRS Checked BCS Date Mar. 2020 Date 03/13/2020 Proj. No. 7126 Plate 2 Earth Solutions NWLLC Geotechnical Engineering,Construction EarthSolutionsNWLLC EarthSolutionsNWLLC Observation/Testing and Environmental Services Test Pit Location Plan Meadow Avenue Short Plat Renton, Washington NORTH 0 30 60 120 Scale in Feet 1"=60' NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. NOTE: The graphics shown on this plate are not intended for design purposes or precise scale measurements, but only to illustrate the approximate test locations relative to the approximate locations of existing and / or proposed site features. The information illustrated is largely based on data provided by the client at the time of our study. ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. LEGEND Approximate Location of ESNW Test Pit, Proj. No. ES-7126, Feb. 2020 Subject Site Existing Building Proposed Lot Letter A B C Sound Barrier Wall TP-1 TP-2 TP-3 TP-4 TP-5 TP-1 130 130MEADOW AVENUE N.SR-405A N. 38TH STREET Drwn. MRS Checked BCS Date Mar. 2020 Date 03/13/2020 Proj. No. 7126 Plate 3 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutionsNWLLC Geotechnical Engineering,Construction Observation/Testing and Environmental Services Retaining Wall Drainage Detail Meadow Avenue Short Plat Renton, Washington NOTES: Free-draining Backfill should consist of soil having less than 5 percent fines. Percent passing No. 4 sieve should be 25 to 75 percent. Sheet Drain may be feasible in lieu of Free-draining Backfill, per ESNW recommendations. Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1-inch Drain Rock. LEGEND: Free-draining Structural Backfill 1-inch Drain Rock 18" Min. Structural Fill Perforated Rigid Drain Pipe (Surround in Drain Rock) SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Drwn. MRS Checked BCS Date Mar. 2020 Date 03/13/2020 Proj. No. 7126 Plate 4 Earth Solutions NWLLC Geotechnical Engineering,Construction Observation/Testing and Environmental Services EarthSolutionsNWLLC EarthSolutionsNWLLC Footing Drain Detail Meadow Avenue Short Plat Renton, Washington Slope Perforated Rigid Drain Pipe (Surround in Drain Rock) 18" Min. NOTES: Do NOT tie roof downspouts to Footing Drain. Surface Seal to consist of 12" of less permeable, suitable soil. Slope away from building. LEGEND: Surface Seal: native soil or other low-permeability material. 1-inch Drain Rock SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Earth Solutions NW, LLC Appendix A Subsurface Exploration Test Pit Logs ES-7126 Subsurface conditions on site were explored on February 17, 2020, by excavating five test pits using a mini-trackhoe and operator retained by our firm. The approximate locations of the test pits are illustrated on Plate 2 of this study. The test pit logs are provided in this Appendix. The test pits were advanced to a maximum depth of about nine feet bgs. The final logs represent the interpretations of the field logs and the results of laboratory analyses. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. GRAVEL AND GRAVELLYSOILS CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES WELL-GRADED SANDS, GRAVELLYSANDS, LITTLE OR NO FINES POORLY-GRADED SANDS,GRAVELLY SAND, LITTLE OR NO FINES SILTY SANDS, SAND - SILTMIXTURES CLAYEY SANDS, SAND - CLAYMIXTURES INORGANIC SILTS AND VERY FINESANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEYSILTS WITH SLIGHT PLASTICITY INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS ORGANIC SILTS AND ORGANICSILTY CLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND ORSILTY SOILS INORGANIC CLAYS OF HIGHPLASTICITY SILTSANDCLAYS MORE THAN 50% OF MATERIAL ISLARGER THANNO. 200 SIEVE SIZE MORE THAN 50%OF MATERIAL IS SMALLER THANNO. 200 SIEVESIZE MORE THAN 50%OF COARSEFRACTION PASSING ON NO.4 SIEVE MORE THAN 50%OF COARSEFRACTION RETAINED ON NO.4 SIEVE SOIL CLASSIFICATION CHART (APPRECIABLEAMOUNT OF FINES) (APPRECIABLE AMOUNT OF FINES) (LITTLE OR NO FINES) FINEGRAINEDSOILS SAND AND SANDY SOILS SILTS AND CLAYS ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS PEAT, HUMUS, SWAMP SOILS WITHHIGH ORGANIC CONTENTS LETTERGRAPH SYMBOLSMAJOR DIVISIONS COARSE GRAINEDSOILS TYPICAL DESCRIPTIONS WELL-GRADED GRAVELS, GRAVEL -SAND MIXTURES, LITTLE OR NO FINES POORLY-GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLEOR NO FINES SILTY GRAVELS, GRAVEL - SAND - SILT MIXTURES CLEANGRAVELS GRAVELS WITH FINES CLEAN SANDS (LITTLE OR NO FINES) SANDS WITH FINES LIQUID LIMITLESS THAN 50 LIQUID LIMITGREATER THAN 50 HIGHLY ORGANIC SOILS DUAL SYMBOLS are used to indicate borderline soil classifications. The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Earth Solutions NW LLC 127.5 126.5 123.0 122.0 MC = 16.20% MC = 18.40% MC = 2.90% Fines = 1.40% MC = 21.90% SM TPSL SP SM Brown silty SAND, medium dense, moist (Fill) Relic TOPSOIL Horizon Tan poorly graded SAND with gravel, medium dense, moist [USDA Classification: very gravelly coarse SAND] Tan silty SAND, medium dense, moist Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during excavation. No caving observed. 2.5 3.5 7.0 8.0 NOTES Surface Conditions: gravel GROUND ELEVATION 130 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-1 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 128.5 127.5 127.0 125.0 120.5 MC = 11.00% MC = 20.50%Fines = 33.20% MC = 27.70% Fines = 8.20% MC = 19.20% MC = 14.70%Fines = 5.10% TPSL SM TPSL SM SP-SM Dark brown TOPSOIL, root intrusions to 5' (Fill) Tan silty SAND, medium dense, moist (Fill) Relic TOPSOIL Horizon Tan silty SAND, medium dense, moist -slight caving to BOH -infiltration test, [USDA Classification: slightly gravelly very fine sandy LOAM] Gray poorly graded SAND with silt, medium dense, wet [USDA Classification: slightly gravelly SAND] -weak iron oxide staining to 8' -becomes poorly graded sand with gravel [USDA Classification: gravelly coarse SAND] Test pit terminated at 8.5 feet below existing grade. No groundwater encountered duringexcavation. Caving observed from 3.0 feet to BOH. 0.5 1.5 2.0 4.0 8.5 NOTES Depth of Topsoil & Sod 6": grass GROUND ELEVATION 129 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-2 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 129.5 127.0 126.0 121.5 MC = 15.20% MC = 11.40% Fines = 15.20% MC = 22.90% MC = 23.10% TPSL SM TPSL SM Dark brown TOPSOIL (Fill) Brown silty SAND, medium dense, moist (Fill) Relic TOPSOIL Horizon -charcoal fragments Tan silty SAND, medium dense, moist -weak iron oxide staining -at 4' [USDA Classification: slightly gravelly loamy SAND] -becomes gray, light groundwater seepage at 8.5' Test pit terminated at 8.5 feet below existing grade. Groundwater seepage encountered at8.5 feet during excavation. No caving observed. 0.5 3.0 4.0 8.5 NOTES Depth of Topsoil & Sod 6": grass GROUND ELEVATION 130 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-3 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 125.5 121.0 MC = 22.60% MC = 24.30% MC = 18.40% SM SM Tan silty SAND, medium dense, moist (Fill) -becomes brown -interbedded dark brown TOPSOIL in fill -rebar, plastic bags, and wood debris Gray silty SAND, medium dense, moist -weak iron oxide staining -light groundwater seepage Test pit terminated at 9.0 below existing grade. Groundwater seepage encountered at 5.5feet during excavation. Caving observed from 1.5 to 5.0 feet. 4.5 9.0 NOTES Surface Conditions: gravel GROUND ELEVATION 130 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-4 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 125.5 124.5 120.0 MC = 10.90% MC = 6.60% Fines = 7.80% MC = 45.40% TPSL SM SP- SM Dark brown TOPSOIL -root intrusions to 4' Tan silty SAND, medium dense, moist Gray poorly graded SAND with silt, medium dense, moist [USDA Classification: gravelly SAND] -8" tan silty sand lens -becomes wet Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during excavation. No caving observed. 2.5 3.5 8.0 NOTES Depth of Topsoil & Sod 30": grass GROUND ELEVATION 128 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-5 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG Earth Solutions NW, LLC Appendix B Laboratory Test Results ES-7126 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 0.0010.010.1110100 3 D100 140 Specimen Identification 1 fine 6 HYDROMETER304 1.4 33.2 8.2 5.1 15.2 101/2 COBBLES Specimen Identification 4 coarse 20 401.5 8 14 USDA: Tan Very Gravelly Coarse Sand. USCS: SP with Gravel. USDA: Tan Slightly Gravelly Very Fine Sandy Loam. USCS: SM. USDA: Gray Slightly Gravelly Sand. USCS: SP-SM. USDA: Gray Gravelly Coarse Sand. USCS: SP-SM with Gravel. USDA: Tan Slightly Gravelly Loamy Sand. USCS: SM. 6 60 PERCENT FINER BY WEIGHTD10 0.526 0.174 0.399 0.111 7.406 0.137 0.259 1.314 0.253 GRAIN SIZE DISTRIBUTION 100 36.98 3.06 8.55 LL TP-01 TP-02 TP-02 TP-02 TP-03 0.2 0.085 0.154 3/4U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS GRAVEL SAND 37.5 9.5 9.5 19 9.5 %Silt 0.19 1.38 0.79 TP-01 TP-02 TP-02 TP-02 TP-03 2 2003 Cc CuClassification %Clay 16 PID60 D30 coarse SILT OR CLAYfinemedium GRAIN SIZE IN MILLIMETERS 3/8 50 5.0ft. 3.5ft. 5.0ft. 8.5ft. 4.0ft. 5.00ft. 3.50ft. 5.00ft. 8.50ft. 4.00ft. PL PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GRAIN SIZE USDA ES-7126 MEADOW AVENUE SHORT PLAT.GPJ GINT US LAB.GDT 3/10/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 0.0010.010.1110100 3 D100 140 Specimen Identification 1 fine 6 HYDROMETER304 7.8 101/2 COBBLES Specimen Identification 4 coarse 20 401.5 8 14 USDA: Gray Gravelly Sand. USCS: SP-SM. 6 60 PERCENT FINER BY WEIGHTD10 0.2650.664 GRAIN SIZE DISTRIBUTION 100 7.71 LL TP-05 0.086 3/4U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS GRAVEL SAND 19 %Silt 1.23 TP-05 2 2003 Cc CuClassification %Clay 16 PID60 D30 coarse SILT OR CLAYfinemedium GRAIN SIZE IN MILLIMETERS 3/8 50 4.0ft. 4.00ft. PL PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GRAIN SIZE USDA ES-7126 MEADOW AVENUE SHORT PLAT.GPJ GINT US LAB.GDT 3/10/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 Earth Solutions NW, LLC Report Distribution ES-7126 EMAIL ONLY Mr. Huy Nguyen 15400 Southeast 155th Place, Unit 99 Renton, Washington 98058 Appendix B WWHM Output WWHM2012 PROJECT REPORT 20591 WWHM 1/27/2021 6:46:41 PM Page 2 General Model Information Project Name:20591 WWHM Site Name: Site Address: City: Report Date:1/27/2021 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2019/09/13 Version:4.2.17 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year 20591 WWHM 1/27/2021 6:46:41 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 0.322 Pervious Total 0.322 Impervious Land Use acre ROADS FLAT 0.01 ROOF TOPS FLAT 0.046 DRIVEWAYS FLAT 0.232 SIDEWALKS FLAT 0.017 Impervious Total 0.305 Basin Total 0.627 Element Flows To: Surface Interflow Groundwater 20591 WWHM 1/27/2021 6:46:41 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Pasture, Flat 0.272 Pervious Total 0.272 Impervious Land Use acre ROADS FLAT 0.011 DRIVEWAYS FLAT 0.018 SIDEWALKS FLAT 0.019 Impervious Total 0.048 Basin Total 0.32 Element Flows To: Surface Interflow Groundwater 20591 WWHM 1/27/2021 6:46:41 PM Page 5 Routing Elements Predeveloped Routing 20591 WWHM 1/27/2021 6:46:41 PM Page 6 Mitigated Routing 20591 WWHM 1/27/2021 6:46:41 PM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.322 Total Impervious Area:0.305 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.272 Total Impervious Area:0.048 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.117712 5 year 0.152554 10 year 0.177699 25 year 0.211909 50 year 0.239222 100 year 0.268153 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.018418 5 year 0.023514 10 year 0.027077 25 year 0.031804 50 year 0.035494 100 year 0.039335 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.152 0.024 1950 0.163 0.026 1951 0.104 0.016 1952 0.084 0.013 1953 0.090 0.014 1954 0.098 0.015 1955 0.107 0.017 1956 0.106 0.017 1957 0.120 0.019 1958 0.097 0.015 20591 WWHM 1/27/2021 6:47:13 PM Page 8 1959 0.099 0.016 1960 0.097 0.015 1961 0.102 0.016 1962 0.089 0.014 1963 0.101 0.016 1964 0.097 0.015 1965 0.126 0.019 1966 0.083 0.013 1967 0.149 0.022 1968 0.162 0.025 1969 0.112 0.018 1970 0.108 0.017 1971 0.129 0.020 1972 0.154 0.021 1973 0.081 0.013 1974 0.118 0.019 1975 0.136 0.021 1976 0.092 0.014 1977 0.099 0.016 1978 0.121 0.019 1979 0.166 0.026 1980 0.149 0.024 1981 0.122 0.019 1982 0.171 0.027 1983 0.139 0.022 1984 0.088 0.014 1985 0.121 0.019 1986 0.105 0.017 1987 0.162 0.026 1988 0.099 0.015 1989 0.123 0.019 1990 0.272 0.033 1991 0.183 0.026 1992 0.087 0.014 1993 0.075 0.012 1994 0.082 0.013 1995 0.108 0.017 1996 0.131 0.022 1997 0.119 0.018 1998 0.113 0.018 1999 0.231 0.036 2000 0.115 0.018 2001 0.126 0.020 2002 0.147 0.023 2003 0.116 0.018 2004 0.216 0.034 2005 0.099 0.016 2006 0.094 0.014 2007 0.261 0.041 2008 0.176 0.026 2009 0.150 0.024 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.2721 0.0411 2 0.2607 0.0363 3 0.2310 0.0340 20591 WWHM 1/27/2021 6:47:14 PM Page 9 4 0.2161 0.0329 5 0.1825 0.0270 6 0.1764 0.0263 7 0.1714 0.0261 8 0.1656 0.0256 9 0.1628 0.0256 10 0.1621 0.0256 11 0.1616 0.0254 12 0.1538 0.0237 13 0.1521 0.0237 14 0.1503 0.0235 15 0.1495 0.0232 16 0.1486 0.0224 17 0.1473 0.0220 18 0.1395 0.0219 19 0.1358 0.0214 20 0.1312 0.0212 21 0.1292 0.0203 22 0.1263 0.0201 23 0.1258 0.0195 24 0.1230 0.0194 25 0.1215 0.0193 26 0.1212 0.0191 27 0.1210 0.0190 28 0.1198 0.0188 29 0.1191 0.0186 30 0.1179 0.0181 31 0.1164 0.0180 32 0.1154 0.0178 33 0.1129 0.0177 34 0.1123 0.0177 35 0.1084 0.0171 36 0.1078 0.0170 37 0.1072 0.0169 38 0.1056 0.0167 39 0.1051 0.0166 40 0.1036 0.0163 41 0.1023 0.0157 42 0.1008 0.0157 43 0.0990 0.0157 44 0.0989 0.0156 45 0.0986 0.0155 46 0.0985 0.0155 47 0.0981 0.0154 48 0.0972 0.0152 49 0.0971 0.0152 50 0.0966 0.0149 51 0.0945 0.0144 52 0.0920 0.0143 53 0.0904 0.0142 54 0.0891 0.0138 55 0.0882 0.0138 56 0.0871 0.0137 57 0.0839 0.0132 58 0.0827 0.0130 59 0.0823 0.0129 60 0.0808 0.0129 61 0.0755 0.0120 20591 WWHM 1/27/2021 6:47:14 PM Page 10 20591 WWHM 1/27/2021 6:47:14 PM Page 11 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0589 1755 0 0 Pass 0.0607 1576 0 0 Pass 0.0625 1417 0 0 Pass 0.0643 1265 0 0 Pass 0.0661 1140 0 0 Pass 0.0680 1026 0 0 Pass 0.0698 927 0 0 Pass 0.0716 862 0 0 Pass 0.0734 777 0 0 Pass 0.0753 712 0 0 Pass 0.0771 641 0 0 Pass 0.0789 587 0 0 Pass 0.0807 548 0 0 Pass 0.0825 500 0 0 Pass 0.0844 458 0 0 Pass 0.0862 432 0 0 Pass 0.0880 402 0 0 Pass 0.0898 370 0 0 Pass 0.0916 346 0 0 Pass 0.0935 319 0 0 Pass 0.0953 296 0 0 Pass 0.0971 270 0 0 Pass 0.0989 250 0 0 Pass 0.1008 226 0 0 Pass 0.1026 214 0 0 Pass 0.1044 197 0 0 Pass 0.1062 186 0 0 Pass 0.1080 169 0 0 Pass 0.1099 157 0 0 Pass 0.1117 148 0 0 Pass 0.1135 138 0 0 Pass 0.1153 132 0 0 Pass 0.1172 122 0 0 Pass 0.1190 118 0 0 Pass 0.1208 110 0 0 Pass 0.1226 101 0 0 Pass 0.1244 97 0 0 Pass 0.1263 91 0 0 Pass 0.1281 84 0 0 Pass 0.1299 77 0 0 Pass 0.1317 74 0 0 Pass 0.1336 70 0 0 Pass 0.1354 67 0 0 Pass 0.1372 63 0 0 Pass 0.1390 62 0 0 Pass 0.1408 60 0 0 Pass 0.1427 58 0 0 Pass 0.1445 54 0 0 Pass 0.1463 48 0 0 Pass 0.1481 43 0 0 Pass 0.1499 39 0 0 Pass 0.1518 36 0 0 Pass 0.1536 33 0 0 Pass 20591 WWHM 1/27/2021 6:47:14 PM Page 12 0.1554 29 0 0 Pass 0.1572 26 0 0 Pass 0.1591 25 0 0 Pass 0.1609 23 0 0 Pass 0.1627 21 0 0 Pass 0.1645 18 0 0 Pass 0.1663 17 0 0 Pass 0.1682 17 0 0 Pass 0.1700 17 0 0 Pass 0.1718 15 0 0 Pass 0.1736 15 0 0 Pass 0.1755 15 0 0 Pass 0.1773 14 0 0 Pass 0.1791 14 0 0 Pass 0.1809 13 0 0 Pass 0.1827 12 0 0 Pass 0.1846 11 0 0 Pass 0.1864 10 0 0 Pass 0.1882 10 0 0 Pass 0.1900 10 0 0 Pass 0.1919 10 0 0 Pass 0.1937 9 0 0 Pass 0.1955 9 0 0 Pass 0.1973 9 0 0 Pass 0.1991 8 0 0 Pass 0.2010 8 0 0 Pass 0.2028 7 0 0 Pass 0.2046 7 0 0 Pass 0.2064 6 0 0 Pass 0.2083 6 0 0 Pass 0.2101 6 0 0 Pass 0.2119 5 0 0 Pass 0.2137 5 0 0 Pass 0.2155 4 0 0 Pass 0.2174 3 0 0 Pass 0.2192 3 0 0 Pass 0.2210 3 0 0 Pass 0.2228 3 0 0 Pass 0.2246 3 0 0 Pass 0.2265 3 0 0 Pass 0.2283 3 0 0 Pass 0.2301 3 0 0 Pass 0.2319 2 0 0 Pass 0.2338 2 0 0 Pass 0.2356 2 0 0 Pass 0.2374 2 0 0 Pass 0.2392 2 0 0 Pass 20591 WWHM 1/27/2021 6:47:14 PM Page 13 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0 acre-feet On-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Off-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. 20591 WWHM 1/27/2021 6:47:14 PM Page 14 LID Report 20591 WWHM 1/27/2021 6:47:36 PM 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. 20591 WWHM 1/27/2021 6:47:36 PM Page 16 Appendix Predeveloped Schematic 20591 WWHM 1/27/2021 6:47:38 PM Page 17 Mitigated Schematic 20591 WWHM 1/27/2021 6:47:39 PM 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 20591 WWHM.wdm MESSU 25 Pre20591 WWHM.MES 27 Pre20591 WWHM.L61 28 Pre20591 WWHM.L62 30 POC20591 WWHM1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 7 IMPLND 1 IMPLND 4 IMPLND 5 IMPLND 8 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 *** 7 A/B, 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 *** 7 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR 20591 WWHM 1/27/2021 6:47:39 PM Page 19 # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 7 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 *** 7 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 7 0 5 0.8 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 7 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 7 0.1 0.5 0.25 0 0.7 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 7 0 0 0 0 3 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 ROADS/FLAT 1 1 1 27 0 4 ROOF TOPS/FLAT 1 1 1 27 0 5 DRIVEWAYS/FLAT 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 4 0 0 1 0 0 0 5 0 0 1 0 0 0 8 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 0 1 9 4 0 0 4 0 0 0 1 9 5 0 0 4 0 0 0 1 9 8 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 20591 WWHM 1/27/2021 6:47:39 PM Page 20 4 0 0 0 0 0 5 0 0 0 0 0 8 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 4 400 0.01 0.1 0.1 5 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 4 0 0 5 0 0 8 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 4 0 0 5 0 0 8 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 7 0.322 COPY 501 12 PERLND 7 0.322 COPY 501 13 IMPLND 1 0.01 COPY 501 15 IMPLND 4 0.046 COPY 501 15 IMPLND 5 0.232 COPY 501 15 IMPLND 8 0.017 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 *** 20591 WWHM 1/27/2021 6:47:39 PM Page 21 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP 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 20591 WWHM 1/27/2021 6:47:39 PM 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 20591 WWHM.wdm MESSU 25 Mit20591 WWHM.MES 27 Mit20591 WWHM.L61 28 Mit20591 WWHM.L62 30 POC20591 WWHM1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 4 IMPLND 1 IMPLND 5 IMPLND 8 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 *** 4 A/B, Pasture, 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 *** 4 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 ********* 20591 WWHM 1/27/2021 6:47:39 PM Page 23 4 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 *** 4 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 4 0 5 1.5 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 4 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 4 0.15 0.5 0.3 0 0.7 0.4 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 4 0 0 0 0 3 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 ROADS/FLAT 1 1 1 27 0 5 DRIVEWAYS/FLAT 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 5 0 0 1 0 0 0 8 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 0 1 9 5 0 0 4 0 0 0 1 9 8 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 5 0 0 0 0 0 8 0 0 0 0 0 END IWAT-PARM1 20591 WWHM 1/27/2021 6:47:39 PM Page 24 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 5 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 5 0 0 8 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 5 0 0 8 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 4 0.272 COPY 501 12 PERLND 4 0.272 COPY 501 13 IMPLND 1 0.011 COPY 501 15 IMPLND 5 0.018 COPY 501 15 IMPLND 8 0.019 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 *** 20591 WWHM 1/27/2021 6:47:39 PM Page 25 # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 END MASS-LINK END RUN 20591 WWHM 1/27/2021 6:47:39 PM Page 26 Predeveloped HSPF Message File 20591 WWHM 1/27/2021 6:47:39 PM Page 27 Mitigated HSPF Message File 20591 WWHM 1/27/2021 6:47:39 PM Page 28 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. 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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 Appendix C Arborist Report/Tree Plan by Layton Tree Consulting, LLC dated February 12, 2020 LAYTON TREE CONSULTING, LLC It’s all about trees…… PO BOX 572, SNOHOMISH, WA 98291-0572 * 425-220-5711 * bob@laytontreeconsulting.com ARBORIST REPORT/TREE PLAN 3804 Meadow Avenue N Renton, WA Report Prepared by: Bob Layton Registered Consulting Arborist #670 Certified Arborist #PN-2714A February 12, 2020 Updated August 6, 2025 Arborist Report – 3804 Meadow Ave N Page 2 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 Table of Contents Assignment.................................................................................................................................................... 3 Description .................................................................................................................................................... 3 Methodology ................................................................................................................................................. 3 Judging Condition...................................................................................................................................... 3 Judging Retention Suitability .................................................................................................................... 4 Observations ................................................................................................................................................. 4 Discussion/Recommendations ...................................................................................................................... 5 Tree Protection Guidelines ........................................................................................................................... 5 Tree Protection Measures ............................................................................................................................ 5 Tree Density-Tree Replacement ................................................................................................................... 6 Arborist Disclosure Statement ...................................................................................................................... 7 Attachments Photos, pages 8 - 11 Tree Summary Table Tree Plan Map City of Renton – Approved Tree List Arborist Report – 3804 Meadow Ave N Page 3 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 Assignment Layton Tree Consulting, LLC was contacted by Huy Nguyen, and was asked to compile an Arborist Report for one parcel in Renton. The subject property is located at 3804 Meadow Avenue N (Parcel 334270- 0570). The purpose of the report is to satisfy City requirements associated with tree retention regulations and the proposed development of the property. My assignment is to prepare a written report on present tree conditions, which is to be submitted to the City with the development application materials. This report covers all of the criteria set forth under the City of Renton’s tree regulations, Municipal Code Section 4-4-130 - Tree Retention and Land Clearing Regulations. Date of Field Examination: February 11, 2020 Description Two significant trees were identified on the property. A numbered aluminum tag was attached to the lower trunk of the subject trees. These tag numbers correspond with the numbers on the attached Tree Summary Table and attached Tree Plan Map. There are no significant neighboring tree issues associated with this property. Methodology Each tree in this report was visited. Tree diameters were measured by tape. The tree heights were measured using a Spiegel Relaskop. Each tree was visually examined for defects and vigor. The tree assessment procedure involves the examination of many factors: The crown or canopy of the tree is examined for current vigor/health by examining the foliage for appropriate color and density, the vegetative buds for color and size, and the branches for structural form and annual shoot growth; and the overall presence of limb dieback and/or any disease issues. The trunk or main stem of the tree is inspected for decay, which includes cavities, wounds, fruiting bodies of decay (conks or mushrooms), seams, insect pests, bleeding or exudation of sap, callus development, broken or dead tops, structural defects and unnatural leans. Structural defects can include but are not limited to excessive or unnatural leans, crooks, forks with V-shaped crotches, multiple attachments. The root collar and exposed surface roots are inspected for the presence of decay, insect damage, as well as if they have been injured or wounded, undermined or exposed, or the original grade has been altered. Judging Condition The three condition categories are described as follows: Good – free of significant structural defects, no disease concerns, minor pest issues, no significant root issues, good structure/form with uniform crown or canopy, foliage of normal color and density, average or normal vigor, will be wind firm if isolated or left as part of a grouping or grove of trees, suitable for its location Arborist Report – 3804 Meadow Ave N Page 4 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 Fair – minor to moderate structural defects not expected to contribute to a failure in near future, no disease concerns, moderate pest issues, no significant root issues, asymmetric or unbalanced crown or canopy, average or normal vigor, foliage of normal color, moderate foliage density, will be wind firm if left as part of a grouping or grove of trees, cannot be isolated, suitable for its location Poor – major structural defects expected to cause fail in near future, disease or significant pest concerns, decline due to old age, significant root issues, asymmetric or unbalanced crown or canopy, sparse or abnormally small foliage, poor vigor, not suitable for its location The attached tree conditions map indicates the ‘condition rating’ of the subject trees found at the site. The attached Tree Summary Table provides specific information on tree sizes and drip-line measurements. Judging Retention Suitability Not all trees necessarily warrant retention. The three retention suitability categories as described in ANSI A300 Part 5 (Standard Practices for the Management of Trees During Site Planning, Site Development and Construction) are as follows: Good – trees are in good health condition and structural stability and have the potential for longevity at the site Fair – trees are in fair health condition and/or have structural defects that can be mitigated with treatment. These trees may require more intense management and monitoring, and may have shorter life-spans than those in the “good” category. Poor – trees are in poor health condition and have significant defects in structure that cannot be mitigated with treatment. These trees can be expected to decline regardless of management. The species or individual tree may possess characteristics that are incompatible or undesirable in landscape settings or be unsuited for the intended use of the site. Observations The subject trees are described as follows: Tree #1 is a mature English walnut, located in the northeast portion of the property. It is completely covered with or consumed by English ivy. The ivy has encroached into the top of the tree. An inspection of the root crown, trunk and branch/stem attachments is not possible. See pictures below. The majority of tree crown extends south. Vigor appears fairly good. Overall condition is rated as ‘fair-poor’ due to the ivy encroachment. Tree #2 is a semi-mature to mature Douglas fir. The top has broken out in the past. Vigor is good. The lower trunk is sound with no outward indicators of any internal decay issues. Condition is rated as fair to good. Neighboring Trees No issues. Arborist Report – 3804 Meadow Ave N Page 5 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 Discussion/Recommendations Tree locations are shown on the attached map. The driplines of both trees have also been delineated. Both trees will be retained through the short plat process. Position a tree protection barrier as shown on the attached tree plan map. Move the stormwater utility outside of the tree protection fence for Tree #1 (walnut). The English ivy vines have been cut from the base of the walnut tree years ago. Based on Google Streets imagery dated October 2022 and July 2025, the ivy has been completely removed from the tree. See pictures below. Tree #1 needs to be pruned to prevent a large future limb failure. The tree has a noteworthy lean and major asymmetric or unbalanced canopy to the south. Reduce the canopy area/dripline on the south side to roughly 20-feet to more uniformly shape the canopy. Use a professional tree service to conduct this work. The existing concrete and other hardscapes within the tree protection area for Tree #2 shall be removed by hand-labor only, prior to the demolition of the existing structure. Concrete shall be broken up with a manual jackhammer and pieces shall be removed by hand labor only. Thoroughly irrigate the newly exposed ground and cover with a +/- 6-inch layer of coarse wood/bark-chip mulch or hog fuel. Tree Protection Guidelines Tree protection fencing shall be positioned around retained trees prior to site demolition or bringing any heavy equipment onto the site. This will help to define clearing limits and protect soils and surface roots. Existing grades within the tree protection fenced area shall not be altered. Any roots from protected trees damaged during site work outside of the tree protection areas shall be pruned clean at sound tissue prior to backfilling or finishing areas. Sound tissue is where the root is undamaged and the bark is completely intact with the root. This will help roots to seal off potential decay and allow them to sprout new growth. Any disturbed areas near protected trees shall be watered weekly during the dry season of June through September. This will help to create a favorable environment for new root growth and reduce the overall stress associated with root loss and disturbance. Equipment shall be kept outside of tree protection areas at all times. All finish landscape work inside the tree protection area shall be completed using hand-labor only. Maintain the existing grades within the protection areas. Finish the landscape within the driplines of retained or protected trees by simply removing any unwanted vegetation by cutting and hand-pulling, and adding a +/- 4-inch layer of organic mulch. Keep irrigation trenches, large plantings or other improvements outside of the tree protection areas. Tree Protection Measures The following guidelines are recommended to ensure that the designated space set aside for the retained trees is protected and construction impacts are kept to a minimum. Arborist Report – 3804 Meadow Ave N Page 6 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 • Tree protection fencing shall be erected per prior to moving any heavy equipment on site. Doing this will set clearing limits and avoid compaction of soils within root zones of retained trees. • Excavation limits shall be laid out in paint on the ground to avoid over excavating. • Any city-authorized excavation within the driplines of retained trees shall be monitored by the project arborist so necessary precautions can be taken to decrease impacts to tree parts. • To establish subgrade for foundations, curbs and pavement sections near the trees, soil should be removed parallel to the roots (away from tree trunks) and not at 90-degree angles to avoid breaking and tearing roots that lead back to the trunk within the dripline. Any roots damaged during these excavations shall be exposed to sound tissue and cut cleanly with a saw. • Areas excavated within the driplines of retained trees shall be thoroughly irrigated weekly during dry periods. • Preparations for final landscaping shall be accomplished by hand within the driplines of retained trees. Large equipment shall be kept outside of the tree protection zones at all times. Tree Density-Tree Replacement For detached single-family development, a minimum of 2 significant trees per every 5,000 sq. ft. of lot area is required. Replacement tree requirements will be determined at the individual building lot approval stage. Replacement trees shall be at least 2-inch caliper for deciduous species and 6-feet in height for evergreen species. The City’s approved tree list is attached. Replacement tree species shall be chosen from this list. Arborist Report – 3804 Meadow Ave N Page 7 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 Arborist Disclosure Statement Arborists are tree specialists who use their education, knowledge, training and experience to examine and assess trees, recommend measures to enhance the beauty and health of trees, and attempt to reduce the risks associated with living near trees. Clients may choose to accept or disregard the recommendations of the arborist, or to seek additional advice. Arborists cannot detect every condition that could possibly lead to the structural failure of a tree. Trees are living organisms that grow, respond to their environment, mature, decline and sometimes fail in ways we do not fully understand. Conditions are often hidden within trees and below ground. Arborists cannot guarantee that a tree will be healthy and/or safe under all circumstances, or for a specified period of time. Likewise, remedial treatments, like any medicine, cannot be guaranteed. Treatment, pruning and removal of trees may involve considerations beyond the scope of the arborist’s services such as property boundaries, property ownership, site lines, disputes between neighbors, and other issues. Arborists cannot take such considerations into account unless complete and accurate information is disclosed to the arborist. An arborist should then be expected to reasonably rely upon the completeness and accuracy of the information provided. Trees can be managed, but they cannot be controlled. To live near trees is to accept some degree of risk. The only way to eliminate all risk associated with trees is to eliminate all trees. Arborist Report – 3804 Meadow Ave N Page 8 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 Photo Documentation Google Streets Imagery dated July 2025, ivy no longer exists in tree Google Streets Imagery dated October 2022, ivy has been cut from lower trunk Arborist Report – 3804 Meadow Ave N Page 9 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 Tree #1 – was consumed by ivy growth in 2020 Tree #1 – massive ivy growth into tree canopy (2020) Arborist Report – 3804 Meadow Ave N Page 10 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 North property line, Tree #1 on right Northwest corner of property Arborist Report – 3804 Meadow Ave N Page 11 Layton Tree Consulting LLC February 12, 2020 Updated August 6, 2025 Tree #2, back or east side of property Tree #1, looking west from back of property Layton Tree Consulting LLC For:Huy Nguyen Site:3804 Meadow Ave N - Renton Tree Summary Table Date: Tree/DBH Height Retention Tag #Species (inches)(feet)Condition Suitability Comments Proposal N S E W 1 English walnut 28 58 16 36 20 22 Fair Fair asymmetric canopy to south, needs pruning Retain 2 Douglas fir 37 106 16 17 16 17 Fair-Good Fair old broken top, sound Retain OFF-SITE TREES No issues Dripline measurements from face of trunk Dripline (feet) 2/11/2020 APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 1 In the City of Renton there is an overabundance of maple and cherry species. According to the most recent street tree inventory, maples currently comprise 35% and cherry 24% of all species. To reduce a catastrophic loss of species, experts agree that 10% or less of any species or cultivar exist within a street tree population. Because of this, planting maple or cherry trees within the right-of-way is discouraged. SMALL TREES: 30 feet in height or less Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Acer buergeranum / Trident Maple 20 20 yellow orange and red Adaptable to urban environments. Decidiuous: prefers moist, well-drained soils: tolerates infertile sites. Drought tolerant. Acer campestre / Hedge Maple 30 30 yellow Deciduous; prefers moist, rich soils; slow growing tree tolerant of air pollution and soil compaction; yellow fall color; cultivars available including Queen Elizabeth maple (‘Evelyn’) with dark green, glossy foliage. Acer circinatum / Vine Maple 20-25 10 orange and red Deciduous; prefers moist, well-drained soils; tolerates seasonal saturation and varying soil types; drought tolerant once established; bushy shrub or small tree; most often multi-trunked and does well in small groups; white flowers April- June. Acer ginnala 'Flame' / Amur Maple 20 20 red Deciduous; prefers moist, well-drained soils, but is tolerant of drought; is often multi-trunked, but can be pruned to a single stem; rounded form; fragrant, yellowish-white flowers in spring; cultivars are available such as ‘Flame’ and ‘Embers’ with differing fall colors. Select or prune for single stem; can be multi- trunked. Acer grandidentatum 'Schmidt' / Rocky Mt. Glow Maple 25+ 15 intense Acer griseum / Paperback Maple 25 20 scarlet Deciduous; prefers moist, well-drained soils, but is moderately drought tolerant; bronze peeling bark provides year-round visual interest; often multitrunked, but can be trained to a single stem; slow growing; disease and pest resistant. Smooth, peeling, cinnamon colored bark. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 2 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Acer palmatum / Japanese Maple 20 24 yellow, orange, red Prefers moist, well-drained soils; deciduous; slow to moderate growth rate; multi-trunked with spreading branches; intolerant of inundation but moderately drought resistant; vibrant fall colors; many cultivars available including ‘Emperor I’, ‘Katsura’, and ‘Osakazuki’. Hundreds of varied cultivars. Can be slow growing. Acer saccharum 'Apollo' 25 10 yellow, orange Prefers well drained soils, but grows in varying soils; hearty. Acer platanoides 'Globosum' / Globe Norway Maple 20 18 yellow Moist soils preferred, but tolerates drought and seasonal inundation; tolerant of urban pollution; dense, compact, round form; slow-growing deciduous tree with brilliant fall color; shallow root system may make mowing under the tree slightly difficult; good selection for locations under power lines; another cultivar well suited for such a location is A. platanoides ‘Almira,’ reaching only 20-25 ft. Rounded top, and compact growth. Acer truncatum / Purpleblow maple 20-25 20-25 Prefers moist, well-drained soil, but drought tolerant; very cold hardy deciduous tree; moderate growth rate; yellow flowers in spring; an additional maple cultivar of interest is 'Pacific sunset'. Acer truncatum x A. platanoides 'Warren's Red' / Pacific Sunset 30 25 yellow- orange/ red Acer Triflorum - Roughbark maple 25-30 20-25 apricot, gold Deciduous; prefers moist soils, but somewhat drought tolerant once established; rough, knobby trunk provides interest in winter; disease and pest resistant; non- aggressive roots do not damage sidewalks or driveways. Amelanchier grandiflora 'Princess Diana' 20 15 bright red Good for limited space. Amelanchier x grandiflora 'Autumn Brilliance' Serviceberry 20 15 red or yellow Moist to dry, well-drained soils; small tree; drought tolerant; white clustered flowers in spring; also try 'Princess Diana' for bright red fall color and the slightly taller 'Robin Hill' (20-30 feet). Reliable bloom. Amelanchier laevis ' lustre' / Luster Serviceberry 25 25 red or yellow Moist to dry, well-drained soils; small tree; drought tolerant; white clustered flowers in spring. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 3 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Arbutus 'Marina' 25 15 evergreen Good substitute for Pacific Madrone. May exceed 25' height under some site conditions. Carpinus caroliniana / American hornbeam 20-30 20-20 Deciduous; prefers moist, rich soils; grows near saturated areas but is only weakly tolerant of saturation; blooms March-May; slow growing; deep coarse laterally spreading roots; medium life span; also consider Carpinus japonica (Japanese hornbeam). Cercis canadensis / Eastern Redbud 25 30 yellow Deciduous; prefers moist, rich soils; tolerant of shade; somewhat drought resistant, but not in full sun; purple-lavender flowers; medium longevity; often multi-trunked; shallow, fibrous roots become deeper on drier sites; fairly short- lived; blooms March-May. Blooms before leaves are out. Cornus kousa 'Chinensis' / Chinese Kousa Dogwood 20 20 reddish to scarlet Prefers moist soils; tolerant of varying soil types; moderate growth rate; deciduous; white flowers in June and large red fruits that resemble a raspberry in September; red to maroon fall color; more disease resistant than other dogwoods; many additional cultivars available. Most resistant to disease of the dogwoods. Crataegus crus-galli 'Inermis' / Thornless Cockspur Hawthorn 25 30 orange to scarlet Red persistent fruit. Crataegus x lavalii / Lavalle Hawthorne 28 20 bronze, coppery red Deciduous; prefers moist, well-drained soil, but tolerant of varying soil types; white flowers in spring; fruit can be a bit messy. Thorns on younger trees. Crataegus phaenopyrum / Washington Hawthorn 25 20 scarlet Thorny. Fraxinus pennsylvanica 'Johnson' / Leprechaun Ash 18 16 yellow Prefers moist, well-drained soils; deciduous: slow to moderate growth rate; tolerant of inundation but moderately drought resistant. A miniature in every way. Magnolia x loebneri 20 20 yellow Several cultivars. Magnolia grandiflora 'Little Gem' 15 10 evergreen Useful where larger varieties are inappropriate. Magnolia grandiflora 'Victoria' 25 20 evergreen APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 4 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Malus spp. / Flowering crabapple 15-25 6-15 Selection should be based on disease resistance to apple scab and fireblight. Tolerant of prolonged soil saturation; short lived; tolerant of drought and seasonally saturated soils; deciduous; white or faintly pink flowers in spring; numerous Malus species and cultivars provide a variety of foliage and flower colors, forms and fruit. Malus 'Adirondack' 18 8 yellow Red fruit. Excellent scab resistance. Malus 'Red Barron' 18 8 yellow Good for narrow spaces. Red berries. Malus 'Golden Raindrops' 18 13 yellow Abundant yellow fruit. Malus 'Tschonoskii' 28 14 scarlet Sparse green fruit, pyramidal. Parrotia persica / Persian Parrotia 30 20 yellow- orange red Moist to dry soils; drought tolerant when established, deciduous tree with moderate growth rate; brilliant fall color; often multi-trunked, but can be trained to have just one; tolerates urban pollution and soil compaction; surface roots do not generally cause problems; virtually disease and pest-free. Pranus 'Frankthrees' / Mt. St. Helens Plum 20 20 Purple foliage. Prunus 'Newport' / Newport Plum 20 20 reddish to scarlet Purple red foliage. Prunus cerasifera 'Krauter Vesuvius' / Flowering Plum 30 15 Upright growth, darkest foliage of the plums. Prunus cerasifera 'Thundercloud' / Plum 20 20 Dark purple foliage. Prunus x hillieri 'Spire' 30 10 orange red Prunus 'Snowgoose' / Snow Goose Cherry 20 20 Upright when young, spreading when older. Prunus serrulata 'Amanogawa' / Flowering Cherry 20 6 bronze Particularly useful for very narrow planting strips. Prunus serrulata 'Shirofugen' / Japanese flowering cherry 25 25 Deciduous flowering tree; moist, well-drained soils; double pink to white blooms in spring; vigorous grower; additional desirable choices include P. serrulata ‘Snowgoose’, ‘Kwanzan’, and ‘Shirotae’. Prunus x yedoensis 'Akebono' / Flowering Cherry 25 25 yellow APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 5 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Quercus Ilex / Holly Oak 20 20 Prefers moist soils, but grows in varying soils; hearty, slow-growing evergreen tree; light pink flowers May-June; pruning will keep tree small for a hedge, without pruning may grow considerably larger – not appropriate under utility lines; tolerates salt water spray. Prune to keep small, leave it alone to grow large. Styrax japonica / Japanese Snowbell 25 25 yellow Plentiful, green 1/2 inch seeds. Styrax obassia / Fragrant Snowbell 30 25 Prefers moist, well-drained soil but tolerates wide variations; fragrant with flowers; twisting bark. Try other Styrax species. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 6 MEDIUM TREES: 30 to 50 feet in height Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Acer campestre 'Evelyn' / Queen Elizabeth Maple 35 30 yellow More upright branching than the species. Acer platanoides 'Columnar' / Columnar Norway maple 40 15 yellow Deciduous; adapts to varying soils; upright or columnar in form making this cultivar a better choice for narrow locations; tolerant of drought and seasonal inundation; tolerates urban pollution and displays brilliant fall color; shallow rooting necessitates locating at least 4-6 feet from sidewalks and driveways to prevent heaving of pavement. Good close to buildings. Acer truncatum x A. platanoides 'Klethsform' / Norwegian Sunset 35 25 yellow- orange/ red Acer rubrum 'Bowhall' / Bowhall Maple 40 15 yellow orange Acer rubrum 'Karpick' / Karpick Maple 35-40 20 yellow to orange May work under very high powerlines with arborist's approval. Acer rubrum 'Scarsen' / Scarlet Sentinel Maple 40 20 yellow orange Acer rubrum / Red Maple 35-50 15-40 Deciduous tree known for fall color; prefer wet or moist soils; fast growing with roots that may heave sidewalks or interfere with mowing; many cultivars of varying heights available including: A. rubrum, 'Armstrong', 'Bowhall', 'Karpick', 'Scarsen', and 'Red Sunset'. Betula jacquemontii / Jacquemontii Birch 40 30 yellow White bark makes for good winter interest. Carpinus betulus 'Fastigiati' / Pyramidal European Hornbeam 35 25 yellow Fagus sylvatica 'Dawyck Purple' / Dawyck Purple Beech 40 12 Purple foliage. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 7 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Fraxinus americana 'Autumn Applause' / Ash 40 25 purple Deciduous; prefers moist, well-drained soils; dense, wide spreading canopy; long-lived; purple fall color; moderate growth rate; also try F. Americana 'Junginger'. Fraxinus oxycarpa 'Raywood' / Raywood Ash 35 25 reddish purple Pyrus calleryana 'Aristocrat' / Pear 40 45 red Pyrus calleryana 'Chanticleer' / Flowring Pear 40 15 Deciduous tree that grows well in a variety of soil types; orange to reddish fall color; white flowers in spring; additional cultivars of interest include P. calleryana 'Redspire' and 'Aristocrat'. Pyrus calleryana 'Redspire' / Pear 40 45 red Pyrus calleryana 'Autumn Blaze' / Pear 30 25 scarlet Vigorous. Ginko biloba 'Autumn Gold' / Maidenhair tree 45 35 yellow Moist soils; deciduous ornamental tree; fast growing and long-lived; tolerant of urban pollution, summer drought and winter inundation; showy fall color; grows in soils of varying quality; provides dense canopy; additional cultivars available. Ginko biloba 'Princeton Sentry' 40 15 yellow Very narrow growth. Gleditsia triacanthos inermis 'Shademaster' / Shademaster Thornless Honeylocust 45 35 yellow Deciduous; prefers moist, rich soils, but will grow in varying soil types; a thornless cultivar tolerant of drought and seasonal inundation; adapts to urban pollution and displays vigorous growth; deciduous tree with showy yellow fall color; additional cultivars available such as ‘Imperial,’ which grows 30-35 feet, ‘Moraine,’ and ‘Rubylace’. Do not confuse with 'Sunburst'. Koelreuteria paniculata / Goldenrain Tree 20-35 10-30 yellow Deciduous; prefers moist well-drained soils, but is tolerant of poor soils; medium rate of growth and longevity; tolerant of periods of drought and seasonal inundation; tolerates urban pollution; provides a dense, wide-spreading canopy. Midsummer blooming. Oxydendron arboreum / Sourwood 35 12 reddish purple Consistent and brilliant fall color. Prunus sargentii 'Columnarus' 35 15 orange to orange red The cherry with the best fall color. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 8 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Quercus 'Crimschmidt' / Crimson Spire Oak 45 15 Hard to find. Robinia x ambigua 'Idahoensis' / Pink Idaho Locust 35 25 yellow Fragrant flowers. Tilia americana 'Redmond' 35 20 yellow Pyramidal, needs water. Tilia cordata 'Chancole' / Chancelor Linden 35 20 yellow Pyramidal. Tilia cordata 'De Groot' / Linden 30-50 20 yellow Compact, suckers less than other Lindens. Tilia cordata 'Greenspire' / Greenspire Linden 40 30 yellowish Symmetrical pyramidal form. Tilia cordata 'Littleleaf' / Littleleaf Linden 30-50 30 Deciduous; prefers moist, well-drained soils, but tolerant of a variety of soil types; tolerant of wind and urban pollution; fast growing and long-lived; tolerates summer drought and seasonal inundation; provides a dense canopy; C. cordata is the hardiest Linden; many forms available including, T. cordata ‘Chancellor’, ‘Corzam’, and ’Greenspire’. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 9 LARGE TREES: 50 feet in height or taller Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Acer freemanli / Autumn Blaze Maple 50 40 orange Abies grandis / Grand Fir 100 40 Evergreen; tolerant of fluctuating water tables and floods; medium rate of growth; root structure depends on site conditions – shallow in moist areas, deep taproot in drier conditions. Acer nigrum 'Green Colunm' / Green Column Maple 50 20 yellow to orange Good close to buildings. Acer platanoides 'Emerald Queen' 50 40 yellow Deciduous; fast growing with an erect, spreading form; prefers moist soils, but is tolerant of summer drought and seasonal inundation; tolerates urban pollution; avoid locating near structures due to shallow, vigorous rooting; additional cultivars available including A. platanoids ‘Parkway’. Acer pseudoplatanus / Sycamore maple 40-60 25-40 Deciduous; prefers moist, well-drained soils but is adaptable to may soil types; tolerates summer drought and seasonal inundation; tolerant of urban pollution with a moderate growth rate; sturdy, resistant to wind and salt spray; a number of cultivars are available including: A. pseudoplatanus ‘Atropurpureum,’ ‘ Brilliantissimum,’ ‘Cox’ (Lustre), and ‘Puget Pink’. Acer saccharum 'Bonfire' 50 40 bright orange red Fastest growing sugar maple. Acer saccharum 'Commemoration' 50 35 orange to orange- red Resistant to leaf tatter. Acer saccharum 'Green Mountain' 45 35 red to orange Acer saccharum / Sugar maple 60-75 35 yellow, orange Deciduous; prefers moderately moist, well-drained soils; long-lived and tolerant of urban pollutants; slow to medium growth rate; needs large planting area; a variety of cultivars available including Acer saccharum ‘Legacy’. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 10 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Calocedrus decurrens / Incense cedar 75-90 10-20 Evergreen; tolerant of poor soils; drought tolerant after established; tolerant of wind and urban conditions; narrow growth habit makes this a good choice for smaller spaces and ideal for screening, fragrant tree; slow growing and long- lived. Carpinus betulus / European Hornbeam 40-60 30-40 Deciduous tree: tolerant of urban pollution and poor soils; cultivars available and suggested include 'Fasigiata' (30-40 ft height) and 'Franz Fontaine' (30-35 ft height). Cedrus deodara / Deodar cedar 40-60 20-40 Evergreen; prefers moist, well-drained soils, but drought tolerant when established; fairly fast growing and long lived; dense, wide spreading canopy; attractive cultivars available. Cercidiphyllum japonicum / Katsura Tree 40-60 20-40 apricot, orange Deciduous; requires moist soil and does not do well on hot dry sites. Leaves are heart-shaped. Cercidiphyllum japonicum / Katsura Tree 40 40 yellow to orange Fagus sylvatica / Green Beech 50 40 bronze Silvery-grey bark. Fraxinus american 'Autumn Purple' / Autumn Purple White Ash 60-80 50-70 to a dark purple Deciduous; prefers moist well-drained soils but tolerates a range of soil types; Also try 'Rosehill'. Fraxinus latifolia / Oregon Ash 40-80 30 Deciduous; saturated, ponded or moist soils; flood tolerant; small green-white flowers; tolerant of poor soils. Fraxinus pennsylvanica / Green Ash 50 40 Deciduous; prefers moist soils; fast growth rate; salt, seasonal drought and urban pollution; numerous cultivars including'Patmore' (50-60 ft. height), 'Summit' (to 45 ft. height), and 'Urbanite' (to 50 ft. height). Fraxinus pennsylvanica 'Patmore' / Patmore Ash 45 35 yellow Extremely hardy, may be seedless. Fraxinus pennsylvanica 'Urbanite' / Ash 50 40 deep bronze Gleditsia triacanthos inermis 'Skyline' / Skyline Thornless Honeylocust 60-70 40 yellow Deciduous; prefers moist soils, but will grow in poor soils; tolerant of drought, seasonal inundation, and urban pollution; occasionally fruit pods can create litter during winter months; thornless. Do not confuse with 'Sunburst'. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 11 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Gymnocladus dioicus espresso / Espresso Kentucky Coffeetree 50 35 yellow Deciduous; drought and variable soil tolerant; seedless. Liquidamber styraci fleia / American sweetgum 60-75 40 Deciduous; prefers moist well-drained soils but tolerant of poor soils; drought tolerant after established; avoid major roadways and restricted sites. Many cultivars available. Liriodendron tulipifera / Tulip Tree 60-80 30-60 yellow Deciduous; prefers moist, deep, well-drained soils, but tolerates poor soils; fast growing; needs large growing area, lower growing cultivars available such as 'Columnar'. Fast-growing tree. Metasequoia glyptostoboides / Dawn redwood 70-100 25 Deciduous; prefers moist, deep, well-drained soils, but tolerates compacted and poor soils; long-lived, fast growing conifer; tolerant of seasonal inundation and drought; can grow in standing water; needles turn russet in the fall; needs large growing area; lower growing cultivars available such as M. glyptostroboides ‘Gold Rush’ and ‘Sheridan Spire’. Nothofagus antartica / Southern Beech 50 35 none Rugged twisted branching and petite foliage. Nyssa sylvatica / Tupelo 70+ 20 apricot to bright red Handsomely chunky bark. Picca omorika / Serbian spruce 50-60 20-25 Slow growing; tolerant of varying soils and urban pollution; moderately drought tolerant once established; elegant evergreen spruce, good for narrow locations; lower growing cultivars available. Pseudotsuga menziesii / Douglas fir 75-120 40 Evergreen conifer; moist to dry soils; long-lived with a medium to fast rate of growth; tolerant of summer drought, winter inundation, and poor soils; withstands wind and urban pollution; provides a nice canopy, but potential height will restrict placement. Quercus coccinea / Scarlet oak 50-60 45 brilliant scarlet to red Deciduous; grows in a variety of soil types; long-lived with a moderate growth rate; tolerant of summer drought and urban pollution; does not tolerate saturated soils or shade. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 12 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Quercus macrocarpa / Burr oak 70-80 30-40 Prefers moist soils, but is adaptable to varying soils; slow growing and long-lived; rugged looking deciduous tree; tolerant of seasonal drought and inundation; tolerates urban pollution and city conditions; provides a wide-spreading, dense canopy. Quercus phellos / Willow oak 60-70 50 Deciduous; prefers moist, well-drained soils, but grows in a wide range of soils types; long-lived tree with moderate growth rate and fibrous root system; tolerant of seasonal drought and inundation, as well as urban pollution; provides a wide-spreading, dense canopy; small delicate leaves. Quercus palustris 'Crownright' 80 40 More upright form of Pin Oak. Quercus robar / English oak 40-60+ 40 Prefers well-drained soil; slow to moderate growth rate; long-lived deciduous tree; tolerant of seasonal drought and inundation; tolerates urban pollution, poor soils and constrained root space; susceptible to powdery mildew; many varieties and cultivars available including: ‘Concordia,’ ‘Fastigiata,’ ‘Foliis Variegatis, and ’Westminster Globe.’ Quercus rubra / Northern red oak 60-75 50 Prefers moist, well-drained soils, but drought tolerant when established; tolerates seasonal inundation, urban pollution and salt spray; moderate rate of growth and longevity; provides a dense, wide-spreading canopy; susceptible to oak wilt fungus. Quercus shumardii / Shumard's oak to 70 50 Prefers moist, well-drained soils; deciduous, long-lived tree; tolerant of seasonal drought and inundation, urban pollution and poor soils. Taxodium distichum / Bald cypress to 75 40 Deciduous conifer; wet, mucky soils; tolerant of summer drought and seasonal flooding; will grow in poor soils; slow growing; long-lived with a wide-spreading canopy; roots do not appear to lift sidewalks as readily as other species; prune lower branches for sight-lines; cultivars include T. distichum ‘Shawnee Brave’. Thuja plicata / Western red cedar 200+ 60 Moist to swampy soils; evergreen tree tolerant of seasonal flooding and saturated soils; a good tree for screening; long-lived; cultivars ‘Pumilio’ and ‘Cuprea’ are shorter versions, ‘Aurea’ and ‘Atrovirens’ have distinctive foliage. Tilia americana x euchlora 'Redmond' / Redmond Linden 50 35 yellow Prefers moist, rich soils, but tolerant of a variety of soils; tolerant of seasonal drought and inundation, urban pollution and poor soils; deciduous tree resistant; also try 'Sentry' and 'Boulevard'. APPROVED TREE LIST – Small, Medium, and Large H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\treeslist_march2010.doc P. 13 Botanical name / Common Name Mature Height in Feet Mature Spread in Feet Fall Color Comments Tilia plalyphyllos / Bigleaf linden 60-80 60 Prefers moist, well-drained soils, but grows in a variety of soil types; deciduous tree with medium growth rate; long-lived; tolerant of seasonal drought and inundation; tolerates urban pollutants; provides a wide-spreading, dense canopy; yellowish-white flowers attract bees. Tilia tomentosa / Silver Linden 40-75 25-45 Deciduous; prefers moist, well-drained soils, but drought tolerant when established; urban tolerant. Cultivars include 'sterlay' and 'Green Mountain'. Ulmus ssp. / Elm hybrids 50-60 35-50 yellow Deciduous; prefers moist, well-drained soils, but drought tolerant; rapid grower; a hybrid elm resistant to Dutch elm disease; suggested hybrids include ‘Accolade’, ‘Homestead’ and ‘Pioneer’. Ulmus 'Homestead' / Homestead Elm 60 35 yellow Ulmus parvifolia / Lace Bark Elm 50 40 Deciduous; prefers moist, well drained soils but tolerant of soil types and hot dry conditions. Flaking bark of orange, gray, green and brown color. Several cultivars including 'Allee' and 'Bosque'. Ulmus 'Pioneer' / Pioneer Elm 60 50 yellow Resistant to Dutch elm disease. Umbellularia californica / Oregon myrtle 40-75+ to 50 Prefers moist, well-drained soils; slow growing evergreen tree with aromatic leaves; tolerates seasonal drought and inundation; tolerant of urban pollution; provides a wide spreading, dense canopy; resistant to pests and disease; good for tall hedges or, when trunks are thinned, as a street tree; requires summer watering until established. Appendix D CSWPPP Analysis And Design P a g e | 1 Construction Stormwater General Permit (CSWGP) Stormwater Pollution Prevention Plan (SWPPP) for Meadow Ave Short Plat Prepared for: Department of Ecology Northwest Regional Office Permittee / Owner Developer Operator / Contractor The Cuong Nguyen / Thi Yen Van Pham N/A TBD 15400 SE 155th Pl Unit 99 Renton, WA 98058 3625 Meadow Avenue North Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD TBD TBD SWPPP Prepared By Name Organization Contact Phone Number Clint Wise Encompass Engineering & Survey (425) 392-0250 SWPPP Preparation Date June 5, 2025 Project Construction Dates Activity / Phase Start Date End Date General Construction TBD TBD P a g e | 2 Table of Contents 1 Project Information ...............................................................................................................5 1.1 Existing Conditions .......................................................................................................5 1.2 Proposed Construction Activities ...................................................................................6 2 Construction Stormwater Best Management Practices (BMPs) ............................................7 2.1 The 13 Elements ...........................................................................................................7 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits .......................................... 7 2.1.2 Element 2: Establish Construction Access ............................................................. 8 2.1.3 Element 3: Control Flow Rates ............................................................................... 9 2.1.4 Element 4: Install Sediment Controls ................................................................... 10 2.1.5 Element 5: Stabilize Soils ..................................................................................... 11 2.1.6 Element 6: Protect Slopes ....................................................................................12 2.1.7 Element 7: Protect Drain Inlets............................................................................. 13 2.1.8 Element 8: Stabilize Channels and Outlets .......................................................... 14 2.1.9 Element 9: Control Pollutants ............................................................................... 15 2.1.10 Element 10: Control Dewatering........................................................................... 19 2.1.11 Element 11: Maintain BMPs ................................................................................. 20 2.1.12 Element 12: Manage the Project .......................................................................... 21 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs .................................. 22 3 Pollution Prevention Team ................................................................................................. 23 4 Monitoring and Sampling Requirements............................................................................. 24 4.1 Site Inspection ............................................................................................................ 24 4.2 Stormwater Quality Sampling ......................................................................................24 4.2.1 Turbidity Sampling ............................................................................................... 24 4.2.2 pH Sampling ........................................................................................................ 26 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies ......................... 27 5.1 303(d) Listed Waterbodies .......................................................................................... 27 5.2 TMDL Waterbodies ..................................................................................................... 27 6 Reporting and Record Keeping ..........................................................................................28 6.1 Record Keeping .......................................................................................................... 28 6.1.1 Site Log Book....................................................................................................... 28 6.1.2 Records Retention ............................................................................................... 28 6.1.3 Updating the SWPPP ........................................................................................... 28 6.2 Reporting .................................................................................................................... 29 6.2.1 Discharge Monitoring Reports .............................................................................. 29 6.2.2 Notification of Noncompliance .............................................................................. 29 P a g e | 3 List of Tables Table 1 – Summary of Site Pollutant Constituents .......................................................................5 Table 2 – Pollutants ................................................................................................................. 15 Table 3 – pH-Modifying Sources ...............................................................................................17 Table 4 – Dewatering BMPs ......................................................................................................19 Table 5 – Management .............................................................................................................21 Table 7 – Team Information ..................................................................................................... 23 Table 8 – Turbidity Sampling Method ....................................................................................... 24 Table 9 – pH Sampling Method ................................................................................................ 26 List of Appendices Appendix/Glossary A. Site Map B. BMP Detail C. Correspondence D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies/TMDL Waterbodies Information G. Contaminated Site Information H. Engineering Calculations P a g e | 4 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 P a g e | 5 1 Project Information Project/Site Name: Meadow Ave Short Plat Street/Location: 3804 Meadow Avenue North City: Renton State: WA Zip code: 98007 Receiving waterbody: Lake Washington 1.1 Existing Conditions Total acreage (including support activities such as off-site equipment staging yards, material storage areas, and borrow areas). Total Acreage 0.59 AC (Parcel) Disturbed Acreage: 0.52 AC Existing Structures: Existing single-family residence, gravel/asphalt driveway, miscellaneous hardscape. Topography: Majority of site slopes moderately to the northwest. Drainage Patterns: Predominantly sheet flows to the northwest towards Meadow Ave N. Existing Vegetation: The parcel consists of two trees and residential landscaping and lawn. List of known impairments for 303(d) or Total Maximum Daily Load (TMDL) for the receiving waterbody: None noted at this time. Critical Areas: None noted at this time. Table 1 includes a list of suspected and/or known contaminants associated with the construction activity. See Appendix G for contaminant location map and contaminant location. None noted at this time. Table 1 – Summary of Site Pollutant Constituents Constituent (Pollutant) Location (Remediation Area) Depth Concentration (mg/kg) N/A N/A N/A N/A P a g e | 6 1.2 Proposed Construction Activities Description of site development (example: subdivision, single-famiy, cottages): Subdivision. Description of construction activities (example: site preparation, demolition, excavation): This project proposes the subdivision of an existing parcel and constructing access and utilities for the respective lots. Construction activities will include site preparation, TESC installation, excavation for utilities, foundations, grading, utility installation, asphalt paving, permeable pavement construction, and landscaping. Description of site drainage including flow from and onto adjacent properties. Must be consistent with Site Map in Appendix A: The site has no existing structures. In the existing condition, runoff from the site is generated from one drainage basin sheet flows northwest down sloping terrain over onsite lawn towards Meadow Ave N. In the developed condition, impervious site area will utilize infiltration to control runoff. An overflow will be provided for infiltration facilities, where the outfall to the overflow will closely match the site existing discharge location towards Meadows Ave N. Description of final stabilization (example: extent of revegetation, paving, landscaping): In final conditions the developed site will be fully stabilized with paving of access and seeding of exposed dirt disturbed during construction within clearing limits. Permanent storm drainage infrastructure will collect and treat the majority of onsite surface runoff through infiltration devices to closely match the site existing discharge location. Contaminated Site Information: Proposed activities regarding contaminated soil or groundwater (example: on-site treatment system, authorized sanitary sewer discharge): None noted at this time. P a g e | 7 2 Construction Stormwater Best Management Practices (BMPs) Alternate City approved BMPs shall be utilized in the event the BMP(s) listed below are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NEDES Permit (Appendix E). To avoid potential erosion and sediment control issues that may cause violation(s) of the NPDES Construction Stormwater permit, the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of alternative BMPs after the first sign that existing BMPs are ineffective or failing. 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. Please refer to the TESC plan included in Appendix A and BMP details included in Appendix B. 2.1 The 13 Elements 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. The BMPs relevant to marking the clearing limits that will be applied for this project include: Applicable BMPs: • City of Renton Standard Plan - 212.00: Stake and Wire Fence • City of Renton Standard Plan – 214.00: Silt Fence Installation Schedules: Start of project and replaced as needed and at start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspection to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. P a g e | 8 2.1.2 Element 2: Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads. Construction vehicle access and exit shall be limited to one route, if possible. Wheel washing, street sweeping, and street cleaning may be necessary if stabilized construction access is not effective. All wash wastewater shall be controlled on site and cannot be discharged into waters of the State. If sediment is tracked off site, roads shall be cleaned thoroughly at the end of each day, or more frequently during wet weather. Sediment shall be removed from roads by shoveling or pickup sweeping and shall be transported to a controlled sediment disposal area. Applicable BMPs: • City of Renton Standard Plan – 215.10: Stabilized Construction Entrance Installation Schedules: Start of project and replaced as needed and at start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspection to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. P a g e | 9 2.1.3 Element 3: Control Flow Rates To protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. In general, discharge rates of stormwater from the site will be controlled where increases in impervious areas or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems) Will you construct stormwater retention and/or detention facilities? ☐Yes ☒ No Will you use permanent infiltration ponds or other low impact development (example: rain gardens, bio-retention, porous pavement) to control flow during construction? ☐Yes ☒No Silt fence will act as a barrier between the runoff generated onsite and properties and waterways downstream of the project site. Due to the small area of disturbance, silt fencing should be sufficient for controlling flow rates on the site. List and describe BMPs: City of Renton Standard Plan – 214.00: Silt Fence Installation Schedules: Start of project and as required. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in on-site BMPs and anticipate potential problems and remedies. More frequent inspections during periods of heavy rain. Responsible Staff: identified Certified Erosion and Sediment Control Lead in Section 3 of the SWPPP. P a g e | 10 2.1.4 Element 4: Install Sediment Controls All stormwater runoff from disturbed areas shall pass through appropriate sediment removal BMPs before leaving the construction site. BMPs will be constructed as one of the first steps of grading and will be functional before other land disturbing activities take place. Additionally, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers to minimize tracking of sediments on vehicle tires away from the site and to minimize wash off sediments from adjacent streets in runoff. List and describe BMPs: • City of Renton Standard Plan – 214.00: Silt Fence Installation Schedules: Start of project and as required. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in on-site BMPs and anticipate potential problems and remedies. More frequent inspections during periods of heavy rain. Responsible Staff: identified Certified Erosion and Sediment Control Lead in Section 3 of the SWPPP. P a g e | 11 2.1.5 Element 5: Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. Earthwork quantities: 750 CY. 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 Anticipated project dates: Start date: TBD End date: TBD Will you construct during the wet season? Yes No Applicable BMPs: Element 5: Stabilize Soils: • Section C.3.2 of the 2022 COR SWDM: Mulching • Section C.3.3 of the 2022 COR SWDM: Nets and Blankets • Section C.3.4 of the 2022 COR SWDM: Plastic Covering • Section C.3.10 of the 2022 COR SWDM: Seeding • Section D.2.1.8 of the 2022 COR SWDM: Dust Control • Early application of gravel base on areas to be paved Installation Schedules: Start of project and replaced as needed and at start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. P a g e | 12 2.1.6 Element 6: Protect Slopes Will steep slopes be present at the site during construction? ☐Yes ☒ No Cut and fill slopes within the site will be designed, constructed, and protected in a manner that minimizes erosion. The BMPs to be used to protect slopes for this project are listed below. Applicable BMPs: • Section C.3.2 of the 2022 COR SWDM: Mulching • Section C.3.3 of the 2022 COR SWDM: Nets and Blankets • Section C.3.10 of the 2022 COR SWDM: Seeding Installation Schedules: Start of project and replaced as needed and at start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. P a g e | 13 2.1.7 Element 7: Protect Drain Inlets All storm drain inlets and culverts operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. The priority, however, shall be to keep all access roads clean of sediment and keep street wash water from entering storm drains until treatment can be provided. Inlet protection shall be implemented for all drainage inlets and culverts that could potentially be impacted by sediment-laden runoff on and near the project site. The following inlet protection measures will be applied on this project: Applicable BMPs: • City of Renton Standard Plan – 216.30: Catch Basin Insert Installation Schedules: Start of project and replaced as needed and at start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. P a g e | 14 2.1.8 Element 8: Stabilize Channels and Outlets Where site runoff is to be conveyed in channels or discharged to a stream or some other natural drainage point, efforts will be taken to prevent downstream erosion. Applicable BMPs: N/A Installation Schedules: Start of project and replaced as needed and at start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. 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. P a g e | 15 2.1.9 Element 9: Control Pollutants The following pollutants are anticipated to be present on-site: Table 2 – Pollutants Pollutant (List pollutants and source, if applicable) Concrete Diesel Fuel Asphalt Building, insulation, and roofing materials All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well-organized, and free of debris. BMPs to be implemented to control specific sources of pollutants are discussed below. Chemical storage: ▪ Any chemicals stored in the construction areas will conform to the appropriate source control BMPs listed in the COR SWDM. All chemicals shall have cover, containment, and protection provided on site, per Section D.2.2.4 of the 2022 COR SWDM for Material Delivery, Storage and Containment. ▪ Application of agricultural chemicals, including fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers’ recommendations for application procedures and rates shall be followed. Excavation and tunneling spoils dewatering waste: ▪ Dewatering BMPs and BMPs specific to the excavation and tunneling (including handling of contaminated soils) are discussed under Element 10. Demolition: ▪ Dust released from demolished sidewalks, buildings, or structures will be controlled using Dust Control measures (Section D.2.1.8 of the 2022 COR SWDM). ▪ Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet Protection (City of Renton Standard Plan – 216.30: Catch Basin Insert, as described above for Element 7). ▪ Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering the waters of the State by implementing Sawcutting P a g e | 16 and Surfacing Pollution Prevention measures (Section D.2.2.3 of the 2022 COR SWDM). Concrete and grout: ▪ Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (Section D.2.2.1 of the 2022 COR SWDM). Concrete wash out areas shall not be allowed on bare dirt or allowed to drain to bare dirt or the storm system. Sanitary wastewater: ▪ Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Solid Waste: ▪ Solid waste will be stored in secure, clearly marked containers. Other: ▪ Other BMPs will be administered as necessary to address any additional pollutant sources on site. Installation Schedules: Start of project and replaced as needed and as start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? Yes No Vehicles, construction equipment, and/or petroleum product storage/dispensing: ▪ All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. ▪ On-site fueling tanks and petroleum product storage containers shall include secondary containment. ▪ Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. ▪ To perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. P a g e | 17 ▪ Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Applicable BMPs: • Material Delivery, Storage and Containment (Section D.2.2.4 of the 2022 COR SWDM) Fuel onsite will be comprised of fuel tanks in operating equipment ranging between 50-100 gallons of off-road diesel fuel. The BMPs listed below as well as procedures described above should be followed with refueling equipment. Spill kits should be kept on hand and accessible during refueling activities. Installation Schedules: Start of project and replaced as needed and at start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. Will wheel wash or tire bath system BMPs be used during construction? Yes No Will pH-modifying sources be present on-site? Yes No Table 3 – pH-Modifying Sources 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 Recycled concrete stockpiles Other (i.e., calcium lignosulfate) [please describe:] Applicable BMPs: ▪ Monitoring should be performed to ensure concrete placement does not result in excessively high pH in stormwater runoff. pH testing should be performed on a weekly basis, from the start of concrete work until pH drops below 8.5 su. P a g e | 18 Concrete and grout: ▪ Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (Section D.2.2.1 of the 2022 COR SWDM). Concrete wash out areas shall not be allowed on bare dirt or allowed to drain to bare dirt or the storm system. Installation Schedules: Start of project and replaced as needed and at start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. Adjust pH of stormwater if outside the range of 6.5 to 8.5 su. Obtain written approval from Ecology before using chemical treatment except for CO2 or dry ice to modify pH. Will uncontaminated water from water-only based shaft drilling for construction of building, road, and bridge foundations be infiltrated provided the wastewater is managed in a way that prohibits discharge to surface waters? Yes No 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. P a g e | 19 2.1.10 Element 10: Control Dewatering All dewatering water from open cut excavation, tunneling, foundation work, trench, or underground vaults shall be discharged into a controlled conveyance system prior to discharge to a sediment trap or sediment pond. Channels will be stabilized, per Element #8. Clean, non-turbid dewatering water will not be routed through stormwater sediment ponds and will not be discharged to systems tributary to the receiving waters of the State in a manner that does no cause erosion, flooding, or a violation of State water quality standards in the receiving water. Highly turbid dewatering water from soils known or suspected to be contaminated, or from use of construction equipment, will require additional monitoring and treatment as required for the specific pollutants based on the receiving waters into which the discharge is occurring. Such monitoring is the responsibility of the contractor. Dewatering of soils known to be free of contamination will trigger BMPs to trap sediment and reduce turbidity. Other BMPs to be used for sediment trapping and turbidity reduction include the following. 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) Installation Schedules: Start of project and replaced as needed and as start of wet season. Inspection and Maintenance plan: Responsible staff to make weekly site walks and inspections to identify deficiencies in onsite BMPs and anticipate potential problems and remedies. Responsible Staff: Identified Certified Erosion and Sediment Control Lead in Section 3 of this SWPPP. P a g e | 20 2.1.11 Element 11: Maintain BMPs All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained and repaired as needed to ensure the continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each BMP specification (see 2022 City of Renton Surface Water Design Manual, Appendix D). 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 sediments 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. P a g e | 21 2.1.12 Element 12: Manage the Project The project will be managed based on the following principles: • Projects will be phased to the maximum extent practicable and seasonal work limitations will be considered. • 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 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 Design the project to fit the existing topography, soils, and drainage patterns Emphasize erosion control rather than sediment control Minimize the extent and duration of the area exposed Keep runoff velocities low Retain sediment on-site Thoroughly monitor site and maintain all ESC measures Schedule major earthwork during the dry season Other (please describe) P a g e | 22 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs During construction, inlet protection for catch basins shall be installed and maintained in accordance with City of Renton Standard Plan – 216.30: Catch Basin Insert. Pipes should be protected during installation using temporary plugs to prevent excess groundwater from entering the trench. Clean gravel shall be installed into the dispersion trench and protected until the surrounding ground is stabilized with seeding or mulch. Native vegetated flow paths downstream of the dispersion trenches should be clearly delineated and protected from disturbance. Most of the site area will have native vegetation or landscaping coverage. These areas shall be protected from heavy construction equipment to the maximum extent feasible in order to prevent compaction of the underlying soils. P a g e | 23 3 Pollution Prevention Team Table 7 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD TBD Resident Engineer TBD TBD Emergency Ecology Contact Tracie Walters 425-649-4484 Emergency Permittee/ Owner Contact Huy Nguyen 206-334-2245 Non-Emergency Owner Contact Huy Nguyen 206-334-2245 Monitoring Personnel TBD TBD Ecology Regional Office Northwest Region (425) 649-7000 P a g e | 24 4 Monitoring and Sampling Requirements Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements • Site inspections • Stormwater sampling data See form in 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. 4.1 Site Inspection Site inspections will be conducted at least once every calendar week and within 24 hours following any discharge from the site. For sites that are temporarily stabilized and inactive, the required frequency is reduced to once per calendar month. The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with the applicable requirements of the CSWGP. 4.2 Stormwater Quality Sampling 4.2.1 Turbidity Sampling 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) 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. 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. P a g e | 25 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. Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, Yakima): (509) 575-2490 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/CRO_nerts_online.html Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/ERO_nerts_online.html Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/NWRO_nerts_online.html Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/SWRO_nerts_online.html 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. P a g e | 26 4.2.2 pH Sampling pH monitoring is required for “Significant concrete work” (i.e., greater than 1000 cubic yards poured concrete over the life of the project). The use of recycled concrete or 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 9 – pH Sampling Method pH meter pH test kit Wide range pH indicator paper To be determined P a g e | 27 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies 5.1 303(d) Listed Waterbodies Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? Yes No List the impairment(s): None noted at this time. 5.2 TMDL Waterbodies Waste Load Allocation for CWSGP discharges: N/A List and describe BMPs: N/A The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water Body form is included in Appendix F. Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. P a g e | 28 6 Reporting and Record Keeping 6.1 Record Keeping 6.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements • Site inspections • Sample logs 6.1.2 Records Retention Records will be retained during the life of the project and for a minimum of three (3) years following the termination of permit coverage in accordance with Special Condition S5.C of the CSWGP. Permit documentation to be retained on-site: • CSWGP • 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. 6.1.3 Updating the SWPPP The SWPPP will be modified if: • Found ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. • There is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine additional or modified BMPs are necessary for compliance. An updated timeline for BMP implementation will be prepared. P a g e | 29 6.2 Reporting 6.2.1 Discharge Monitoring Reports Cumulative soil disturbance is less than (1) acre; therefore, Discharge Monitoring Reports (DMRs) are not required. 6.2.2 Notification of Noncompliance If any of the terms and conditions of the permit is not met, and the resulting noncompliance may cause a threat to human health or the environment, the following actions will be taken: 1. Ecology will be notified within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number (Regional office numbers listed below). 2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or correct the noncompliance. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Specific information to be included in the noncompliance report is found in Special Condition S5.F.3 of the CSWGP. 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 P a g e | 30 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. P a g e | 31 Appendix/Glossary A. Site Map P a g e | 32 B. BMP Detail 1.CONDITIONS OF USE 1.1.TO ESTABLISH CLEARING LIMITS, STAKE AND WIRE FENCE MAY BE USED: 1.1.1.AT THE BOUNDARY OF CRITICAL AREAS, THEIR BUFFERS AND OTHER AREAS REQUIRED TO BE LEFT UNCLEARED. 1.1.2.AS NECESSARY TO CONTROL VEHICLE ACCESS TO AND ON THE SITE. 2.MAINTENANCE AND REQUIREMENTS 2.1.IF THE FENCE IS DAMAGED OR VISIBILITY REDUCED, IT SHALL BE REPAIRED OR REPLACED IMMEDIATELY AND VISIBILITY RESTORED. 2.2.DISTURBANCE OF A CRITICAL AREA, CRITICAL BUFFER AREA, NATIVE GROWTH RETENTION AREA, OR OTHER AREA REQUIRED TO BE LEFT UNDISTURBED SHALL BE REPORTED TO THE CITY OF RENTON FOR RESOLUTION. 2.3.THE CITY MAY REQUIRE MORE SUBSTANTIAL FENCING IF THE FENCE DOES NOT PREVENT ENCROACHMENT INTO THOSE AREAS THAT ARE NOT TO BE DISTURBED. NOTES SURVEYFLAGGINGBAILINGWIRE DO NOT NAIL OR STAPLE WIRE TO TREES METAL FENCE POST (TYP.)3' MIN. 10' - 20' 12" MIN. STAKE AND WIRE FENCE STD. PLAN - 212.00 PUBLIC WORKS DEPARTMENT APPROVED: DATEGreggZimmerman Public Works Administrator UNLESS OTHERWISE NOTED, DRAWING IS NOT TO SCALE (NTS) DocuSign Envelope ID: 6EECF5B6-602A-4E4A-B436-A317AA638878 9/28/2018 | 9:45 AM PDT 1.CONDITIONS OF USE 1.1.SILT FENCE MAY BE USED DOWNSLOPE OF ALL DISTURBED AREAS. 1.2.SILT FENCE IS NOT INTENDED TO TREAT CONCENTRATED FLOWS, NOR IS IT INTENDED TO TREAT SUBSTANTIAL AMOUNTS OF OVERLAND FLOW. ANY CONCENTRATED FLOW MUST BE CONVEYED THROUGH THE DRAINAGE SYSTEM TO A SEDIMENT TRAP OR POND. 2.DESIGN AND INSTALLATION SPECIFICATIONS 2.1.THE GEOTEXTILE USED MUST MEET THE STANDARD LISTED BELLOW. A COPY OF THE MANUFACTURER'S FABRIC SPECIFICATIONS MUST BE AVAILABLE ON SITE. 2.2.STANDARD STRENGTH FABRIC REQUIRES WIRE BACKING TO INCREASE THE STRENGTH OF THE FENCE. WIRE BACKING OR CLOSER POST SPACING MAY BE REQUIRED FOR EXTRA STRENGTH FABRIC IF FIELD PERFORMANCE WARRANTS A STRONGER FENCE. 2.3.WHERE THE FENCE IS INSTALLED, THE SLOPE SHALL NOT BE STEEPER THAN 2H:1V 2.4.IF A TYPICAL SILT FENCE IS USED, THE STANDARD 4"X4" TRENCH MAY BE REDUCED AS LONG AS THE BOTTOM 8 INCHES OF THE SILT FENCE FABRIC IS WELL BURIED AND SECURE IN A TRENCH THAT STABILIZES THE FENCE AND DOES NOT ALLOW WATER TO BYPASS OR UNDERMINE THE SILT FENCE. 2.5.FILTER FABRIC FENCES SHALL BE INSTALLED ALONG CONTOURS WHENEVER POSSIBLE. 3.MAINTENANCE STANDARDS 3.1.ANY DAMAGE SHALL BE REPAIRED IMMEDIATELY. 3.2.IF CONCENTRATED FLOWS ARE EVIDENT UPHILL OF THE FENCE, THEY MUST BE INTERCEPTED AND CONVEYED TO A SEDIMENT TRAP OR POND. 3.3.IT IS IMPORTANT TO CHECK THE UPHILL SIDE OF THE FENCE FOR SIGNS OF THE FENCE CLOGGING AND ACTING AS A BARRIER TO FLOW AND THEN CAUSING CHANNELIZATION OF FLOWS PARALLEL TO THE FENCE. IF THIS OCCURS, REPLACE THE FENCE OR REMOVE THE TRAPPED SEDIMENT. 3.4.SEDIMENT MUST BE REMOVED WHEN SEDIMENT IS 6 INCHES HIGH. 3.5.IF THE FILTER FABRIC (GEOTEXTILE) HAS DETERIORATED DUE TO ULTRAVIOLET BREAKDOWN, IT SHALL BE REPLACED. NOTES: JOINTS IN FILTER FABRIC SHALL BE SPLICED AT POSTS. USE STAPLES, WIRE RINGS, OR EQUIVALENT TO ATTACH FABRIC TO POSTS 2"x2" 14 GAUGE WIRE, OR EQUIVALENT, IF STANDARD STRENGTH FABRIC USED FILTER FABRIC 2' MIN. 12" MIN. 4"x4" MIN. TRENCH BACKFILL TRENCH WITH NATIVE SOIL OR 3/4" TO 1-1/2" WASHED GRAVEL 2"x4" WOOD POSTS, STEEL FENCE POSTS, OR EQUIVALENT (TYP.) 6' MAX. POST SPACING MAY BE INCREASED TO 8' IF WIRE BACKING IS USED AOS (ASTM D4751)30-100 SIEVE SIZE (0.60-0.15mm) FOR SILT FILM 50-100 SIEVE SIZE (0.30-0.15mm) FOR OTHER FABRICS WATER PERMITTIVITY (ASTM D4491)0.02 SEC-1MINIMUM GRAB TENSILE STRENGTH (ASTM D4632)180 LBS. MIN. FOR EXTRA STRENGTH FABRIC 100 LBS. MIN. FOR STANDARD STRENGTH FABRIC GRAB TENSILE ELONGATION (ASTM D4632)30% MAX. (WOVEN) ULTRAVIOLET RESISTANCE (ASTM D4355)70% MIN. SILT FENCE STD. PLAN - 214.00 PUBLIC WORKS DEPARTMENT APPROVED: DATEGreggZimmerman Public Works Administrator UNLESS OTHERWISE NOTED, DRAWING IS NOT TO SCALE (NTS) DocuSign Envelope ID: 6EECF5B6-602A-4E4A-B436-A317AA638878 9/28/2018 | 9:45 AM PDT EXIST ING R OA D 1.CONDITION OF USE 1.1.CONSTRUCTION ENTRANCE SHALL BE STABILIZED WHEREVER TRAFFIC WILL BE LEAVING A CONSTRUCTION SITE AND TRAVELING ON PAVED ROADS OR OTHER PAVED AREAS WITHIN 1,000 FEET OF THE SITE. 1.2.FOR RESIDENTIAL CONSTRUCTION PROVIDE STABILIZED CONSTRUCTION ENTRANCES FOR EACH RESIDENCE IN ADDITION TO THE MAIN SUBDIVISION ENTRANCE. STABILIZED SURFACES SHALL BE OF SUFFICIENT LENGTH/WIDTH TO PROVIDE VEHICLE ACCESS/PARKING, BASED ON LOT SIZE/CONFIGURATION. 2.DESIGN AND INSTALLATION SPECIFICATIONS 2.1.A SEPARATION GEOTEXTILE SHALL BE PLACED UNDER THE SPALLS TO PREVENT FINE SEDIMENT FROM PUMPING UP INTO THE ROCK PAD. THE GEOTEXTILE SHALL MEET THE FOLLOWING STANDARDS: 2.2.DO NOT USE CRUSHED CONCRETE, CEMENT, OR CALCIUM CHLORIDE FOR CONSTRUCTION ENTRANCE STABILIZATION BECAUSE THESE PRODUCTS RAISE pH LEVELS IN STORMWATER AND CONCRETE DISCHARGE TO SURFACE WATERS OF THE STATE IS PROHIBITED. 2.3.HOG FUEL (WOOD BASED MULCH) MAY BE SUBSTITUTED FOR OR COMBINED WITH QUARRY SPALLS IN AREAS THAT WILL NOT BE USED FOR PERMANENT ROADS. HOG FUEL IS NOT RECOMMENDED FOR ENTRANCE STABILIZATION IN URBAN AREAS. THE INSPECTOR MAY AT ANY TIME REQUIRE THE USE OF QUARRY SPALLS IF THE HOG FUEL IS NOT PREVENTING SEDIMENT FROM BEING TRACKED ONTO PAVEMENT OR IF THE HOG FUEL IS BEING CARRIED ONTO PAVEMENT. 2.4.FENCING SHALL BE INSTALLED AS NECESSARY TO RESTRICT TRAFFIC TO THE CONSTRUCTION ENTRANCE. 2.5.WHENEVER POSSIBLE, THE ENTRANCE SHALL BE CONSTRUCTED ON A FIRM, COMPACTED SUBGRADE. THIS CAN SUBSTANTIALLY INCREASE THE EFFECTIVENESS OF THE PAD AND REDUCE THE NEED FOR MAINTENANCE. 3.MAINTENANCE STANDARDS 3.1.QUARRY SPALLS SHALL BE ADDED IF THE PAD IS NO LONGER IN ACCORDANCE WITH THE SPECIFICATIONS. 3.2.IF THE ENTRANCE IS NOT PREVENTING SEDIMENT FROM BEING TRACKED ONTO PAVEMENT, THEN ALTERNATIVE MEASURES TO KEEP THE STREETS FREE OF SEDIMENT SHALL BE USED. THIS MAY INCLUDE STREET SWEEPING, AN INCREASE IN THE DIMENSIONS OF THE ENTRANCE, OR THE INSTALLATION OF A WHEEL WASH. IF WASHING IS USED, IT SHALL BE DONE ON AN AREA COVERED WITH CRUSHED ROCK, AND WASH WATER SHALL DRAIN TO A SEDIMENT TRAP OR POND. 3.3.ANY SEDIMENT THAT IS TRACKED ONTO PAVEMENT SHALL BE REMOVED IMMEDIATELY BY SWEEPING. THE SEDIMENT COLLECTED BY SWEEPING SHALL BE REMOVED OR STABILIZED ON SITE. THE PAVEMENT SHALL NOT BE CLEANED BY WASHING DOWN THE STREET, EXCEPT WHEN SWEEPING IS INEFFECTIVE AND THERE IS A THREAT TO PUBLIC SAFETY. IF IT IS NECESSARY TO WASH THE STREETS, A SMALL SUMP MUST BE CONSTRUCTED. THE SEDIMENT WOULD THEN BE WASHED INTO THE SUMP WHERE IT CAN BE CONTROLLED AND DISCHARGED APPROPRIATELY. WASH WATER MUST BE PUMPED BACK ONTO THE SITE AND CANNOT DISCHARGE TO SYSTEMS TRIBUTARY TO SURFACE WATERS. 3.4.ANY QUARRY SPALLS THAT ARE LOOSENED FROM THE PAD AND END UP ON THE ROADWAY SHALL BE REMOVED IMMEDIATELY. 3.5.IF VEHICLES ARE ENTERING OR EXITING THE SITES AT POINTS OTHER THAN THE CONSTRUCTION ENTRANCE(S), FENCING SHALL BE INSTALLED TO CONTROL TRAFFIC. NOTES: CONSTRUCTION ENTRANCE NOTES: 1.DRIVEWAYS SHALL BE PAVED TO THE EDGE OF THE RIGHT-OF-WAY PRIOR TO INSTALLATION OF THE CONSTRUCTION ENTRANCE TO AVOID DAMAGING OF THE ROADWAY. 2.IT IS RECOMMENDED THAT THE ENTRANCE BE CROWNED SO THAT RUNOFF DRAINS OFF THE PAD INSTALL DRIVEWAY CULVERT IF THERE IS A ROADSIDE DITCH PRESENT, AS PER CITY ROAD STANDARDS GEOTEXTILE 4"-8" QUARRY SPALLS 12" MIN. THICKNESS 15' MIN. PROVIDE FULL WIDTH OF INGRESS/EGRESS AREA 100' MIN. GRAB TENSILE STRENGTH (ASTM D4632)200 LBS. MIN. GRAB TENSILE ELONGATION (ASTM D4632)30% MAX. (WOVEN) CBR PUNCTURE STRENGTH (ASTM D6241)495 LBS. MIN. AOS (ASTM D4751)20-45 (U.S. STANDARD SIEVE SIZE) R = 25' MIN. STABILIZED CONSTRUCTION ENTRANCE STD. PLAN - 215.10 PUBLIC WORKS DEPARTMENT APPROVED: DATEGreggZimmerman Public Works Administrator UNLESS OTHERWISE NOTED, DRAWING IS NOT TO SCALE (NTS) DocuSign Envelope ID: 6EECF5B6-602A-4E4A-B436-A317AA638878 9/28/2018 | 9:45 AM PDT NOTES: SECTION VIEW ISOMETRIC VIEW DRAINAGE GRATE TRIM GRATE FRAME FILTERED WATER SEDIMENT AND DEBRIS OVERFLOW BYPASS BELOW INLET GRATE DEVICE DRAINAGE GRATE RECTANGULAR GRATE SHOWN)RETRIEVAL SYSTEM (TYP.) OVERFLOW BYPASS (TYP.) BELOW INLET GRATE DEVICE 1.PROTECTION SHALL BE PROVIDED FOR ALL STORM DRAIN INLETS DOWNSLOPE AND WITHIN 500 FEET OF A DISTURBED OR CONSTRUCTION AREA, UNLESS THE RUNOFF THAT ENTERS THE CATCH BASIN WILL BE CONVEYED TO A SEDIMENT POND OR TRAP. 2.INLET PROTECTION SHALL BE USED TO PROTECT THE DRAINAGE SYSTEM. 3.THE CONTRIBUTING DRAINAGE AREA MUST NOT BE LARGER THAN ONE ACRE. 4.SIZE THE BELOW INLET GRATE DEVICE (BIGD) FOR THE STORMWATER STRUCTURE IT WILL SERVICE. 5.THE BIGD SHALL HAVE A BUILT-IN HIGH-FLOW RELIEF SYSTEM (OVERFLOW BYPASS). 6.THE RETRIEVAL SYSTEM MUST ALLOW REMOVAL OF THE BIGD WITHOUT SPILLING THE COLLECTED MATERIAL. 7.PERFORM MAINTENANCE IN ACCORDANCE WITH STANDARD SPECIFICATION 8-01.3(15). 8.ANY SEDIMENT IN THE CATCH BASIN INSERT SHALL BE REMOVED WHEN THE SEDIMENT HAS FILLED ONE-THIRD OF THE AVAILABLE STORAGE. THE FILTER MEDIA FOR THE INSERT SHALL BE CLEANED OR REPLACED AT LEAST MONTHLY. 5" MAX. CATCH BASIN INSERT STD. PLAN - 216.30 PUBLIC WORKS DEPARTMENT APPROVED: DATEGreggZimmerman Public Works Administrator UNLESS OTHERWISE NOTED, DRAWING IS NOT TO SCALE (NTS) DocuSign Envelope ID: 6EECF5B6-602A-4E4A-B436-A317AA638878 9/28/2018 | 9:45 AM PDT SECTION C.3 CONSTRUCTION STORMWATER POLLUTION PREVENTION (CSWPP) MEASURES 6/22/2022 2022 City of Renton Surface Water Design Manual C-112 FIGURE C.3.1.A SCHEMATIC REPRESENTATION OF A STABILIZED CONSTRUCTION ENTRANCE C.3.2 MULCHING Purpose The purpose of mulching soils is to provide immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and moderating soil temperatures. There is an enormous variety of mulches that may be used. Only the most common types are discussed in this section. Conditions of Use As a temporary cover measure, mulch should be used: 1. On disturbed areas that require cover measures for less than 30 days 2. As a cover for seed during the wet season and during the hot summer months 3. During the wet season on slopes steeper than 3H:1V with more than 10 feet of vertical relief. Design and Installation Specifications For mulch materials, application rates, and specifications, see Table C.3.2.A. Note: Thicknesses may be increased for disturbed areas in or near critical areas or other areas highly susceptible to erosion. Maintenance Standards 1. The thickness of the mulch cover must be maintained. 2. Any areas that experience erosion shall be re-mulched and/or protected with a net or blanket. If the erosion problem is drainage related, then the drainage problem shall be assessed and alternate drainage such as interceptor swales may be needed to fix the problem and the eroded area re-mulched. PER KING COUNTY ROAD DESIGN AND CONSTRUCTION STANDARDS (KCRDCS), DRIVEWAYS SHALL BE PAVED TO EDGE OF R-O-W PRIOR TO INSTALLATION OF THE CONSTRUCTION ENTRANCE TO AVOID DAMAGING OF THE ROADWAY. IT IS RECOMMENDED THAT THE ENTRANCE BE CROWNED SO THAT RUNOFF DRAINS OFF THE PAD. 12" MIN. THICKNESS PROVIDE FULL WIDTH OF INGRESS/EGRESS AREA IF A ROADSIDE DITCH IS PRESENT, INSTALL DRIVEWAY CULVERT PER KCRDCS GEOTEXTILE 4"- 8" QUARRY SPALLS R=25' MIN. 100' MIN. E X IS T IN G R O A D 1 5 ' M IN .NOTES: C.3.2 MULCHING 2022 City of Renton Surface Water Design Manual 6/22/2022 C-113 TABLE C.3.2.A MULCH STANDARDS AND GUIDELINES Mulch Material Quality Standards Application Rates Remarks Straw Air-dried; free from undesirable seed and coarse material 2″–3″ thick; 2–3 bales per 1000 sf or 2–3 tons per acre Cost-effective protection when applied with adequate thickness. Hand-application generally requires greater thickness than blown straw. Straw should be crimped to avoid wind blow. The thickness of straw may be reduced by half when used in conjunction with seeding. Wood Fiber Cellulose No growth inhibiting factors Approx. 25–30 lbs per 1,000 sf or 1,000–1,500 lbs per acre Shall be applied with hydromulcher. Shall not be used without seed and tackifier unless the application rate is at least doubled. Some wood fiber with very long fibers can be effective at lower application rates and without seed or tackifier. Compost No visible water or dust during handling. Must be purchased from supplier with Solid Waste Handling Permit. 2″ thick min.; approx. 100 tons per acre (approx. 800 lbs per cubic yard) More effective control can be obtained by increasing thickness to 3″. Excellent mulch for protecting final grades until landscaping because it can be directly seeded or tilled into soil as an amendment. Hydraulic Matrices (Bonded Fiber Matrix [BFM]) This mulch category includes hydraulic slurries composed of wood fiber, paper fiber or a combination of the two held together by a binding system. The BFM shall be a mixture of long wood fibers and various bonding agents. Apply at rates from 3,000 lbs per acre to 4,000 lbs per acre and based on manufacturers recommendations The BFM shall not be applied immediately before, during or immediately after rainfall so that the matrix will have an opportunity to dry for 24 hours after installation. Application rates beyond 2,500 pounds may interfere with germination and are not usually recommended for turf establishment. BFM is generally a matrix where all fiber and binders are in one bag, rather than having to mix components from various manufacturers to create a matrix. BFMs can be installed via helicopter in remote areas. They are approximately $1,000 per acre cheaper to install. Chipped Site Vegetation Average size shall be several inches. 2″ minimum thickness This is a cost-effective way to dispose of debris from clearing and grubbing, and it eliminates the problems associated with burning. Generally, it should not be used on slopes above approx. 10% because of its tendency to be transported by runoff. It is not recommended within 200 feet of surface waters. If seeding is expected shortly after mulch, the decomposition of the chipped vegetation may tie up nutrients important to grass establishment. SECTION C.3 CONSTRUCTION STORMWATER POLLUTION PREVENTION (CSWPP) MEASURES 6/22/2022 2022 City of Renton Surface Water Design Manual C-114 C.3.3 NETS AND BLANKETS Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets are strands of material woven into an open, but high-tensile strength net (for example, jute matting). Blankets are strands of material that are not tightly woven, but instead form a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets, but cover the ground more completely. Coir (coconut fiber) fabric comes as both nets and blankets. Conditions of Use Erosion control nets and blankets should be used: 1. For permanent stabilization of slopes 2H:1V or greater and with more than 10 feet of vertical relief. 2. In conjunction with seed for final stabilization of a slope, not for temporary cover. However, they may be used for temporary applications as long as the product is not damaged by repeated handling. In fact, this method of slope protection is superior to plastic sheeting, which generates high-velocity runoff. 3. For drainage ditches and swales (highly recommended). The application of appropriate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due to their open, porous structure. Synthetic nets and blankets may be used to permanently stabilize channels and may provide a cost-effective, environmentally preferable alternative to riprap. Design and Installation Specifications 1. See Figure C.3.3.A and Figure C.3.3.B for typical orientation and installation of nettings and blankets. Note: Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. 2. With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the design engineer thoroughly consults the manufacturer’s information and that a site visit takes place in order to ensure that the product specified is appropriate. 3. Jute matting must be used in conjunction with mulch. Excelsior, woven straw blankets, and coir (coconut fiber) blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. Other types of products will have to be evaluated individually. In general, most nets (e.g., jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. 4. Purely synthetic blankets are allowed but shall only be used for long-term stabilization of waterways. The organic blankets authorized above are better for slope protection and short-term waterway protection because they retain moisture and provide organic matter to the soil, substantially improving the speed and success of re-vegetation. Maintenance Standards 1. Good contact with the ground must be maintained, and there must not be erosion beneath the net or blanket. 2. Any areas of the net or blanket that are damaged or not in close contact with the ground shall be repaired and stapled. C.3.3 NETS AND BLANKETS 2022 City of Renton Surface Water Design Manual 6/22/2022 C-115 3. If erosion occurs due to poorly controlled drainage, the problem shall be fixed and the eroded area protected. FIGURE C.3.3.A WATERWAY INSTALLATION OF NETS AND BLANKETS FIGURE C.3.3.B SLOPE INSTALLATION OF NETS AND BLANKETS DO NOT STRETCH BLANKETS/MATTINGS TIGHT - ALLOW THE ROLLS TO MOLD TO ANY IRREGULARITIES. SLOPE SURFACE SHALL BE SMOOTH BEFORE PLACEMENT FOR PROPER SOIL CONTACT. ANCHOR, STAPLE, AND INSTALL CHECK SLOTS AS PER MANUFACTURER'S RECOMMENDATIONS. AVOID JOINING MATERIAL IN THE CENTER OF THE DITCH. LIME, FERTILIZE AND SEED BEFORE INSTALLATION. MIN.4" OVERLAP' MIN.6" OVERLAP SLOPE SURFACE SHALL BE SMOOTH BEFORE PLACEMENT FOR PROPER SOIL CONTACT STAPLING PATTERN AS PER MANUFACTURER'S RECOMMENDATION MIN. 2" OVERLAP LIME, FERTILIZE AND SEED BEFORE INSTALLATION. PLANTING OF SHRUBS, TREES, ETC. SHOULD OCCUR AFTER INSTALLATION DO NOT STRETCH BLANKETS/MATTINGS TIGHT - ALLOW THE ROLLS TO MOLD TO ANY IRREGULARITIES FOR SLOPES LESS THAN 3H:1V, ROLLS MAY BE PLACED IN HORIZONTAL STRIPS BRING MATERIAL DOWN TO A LEVEL AREA, TURN THE END UNDER 4" AND STAPLE AT 12" INTERVALS ANCHOR IN 6"x6" MIN. TRENCH AND STAPLE AT 12" INTERVALS STAPLE OVERLAPS MAX. 5' SPACING IF THERE IS A BERM AT THE TOP OF SLOPE, ANCHOR UPSLOPE OF THE BERM MIN. 6" OVERLAP SECTION C.3 CONSTRUCTION STORMWATER POLLUTION PREVENTION (CSWPP) MEASURES 6/22/2022 2022 City of Renton Surface Water Design Manual C-116 C.3.4 PLASTIC COVERING Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Use 1. Plastic covering may be used on disturbed areas that require cover measures for less than 30 days. 2. Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term applications. 3. Clear plastic sheeting may be used over newly-seeded areas to create a greenhouse effect and encourage grass growth. Clear plastic should not be used for this purpose during the summer months because the resulting high temperatures can kill the grass. 4. Due to rapid runoff caused by plastic sheeting, this method shall not be used upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. Note: There have been many problems with plastic, usually attributable to poor installation and maintenance. However, the material itself can cause problems, even when correctly installed and maintained, because it generates high-velocity runoff and breaks down quickly due to ultraviolet radiation. In addition, if the plastic is not completely removed, it can clog drainage system inlets and outlets. It is highly recommended that alternatives to plastic sheeting be used whenever possible and that its use be limited. Design and Installation Specifications 1. See Figure C.3.4.A for details. 2. Plastic sheeting shall have a minimum thickness of 0.06 millimeters. 3. If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. FIGURE C.3.4.A PLASTIC COVERING TIRES, SANDBAGS, OR EQUIVALENT MAY BE USED TO WEIGHT PLASTIC SEAMS BETWEEN SHEETS MUST OVERLAP A MINIMUM OF 12" AND BE WEIGHTED OR TAPED TOE IN SHEETING IN MINIMUM 4"X4" TRENCH PROVIDE ENERGY DISSIPATION AT TOE WHEN NEEDED 10' MAX. 10' MAX. C.3.6 SILT FENCE 2022 City of Renton Surface Water Design Manual 6/22/2022 C-117 Maintenance Standards for Plastic Covering 1. Torn sheets must be replaced and open seams repaired. 2. If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and replaced. 3. When the plastic is no longer needed, it shall be completely removed. C.3.5 MARK CLEARING LIMITS/MINIMIZE CLEARING Purpose Minimizing clearing is the most effective method of erosion control. Undisturbed vegetation intercepts and slows rainwater. Plant roots hold soil in place, and dead vegetation on the ground acts as a mulch. Marking clearing limits around existing or proposed on-site BMP areas helps protect their infiltrative soil characteristics from construction activity. Applications Clearing limits shall be marked and clearing minimized on any site where significant areas of undisturbed vegetation will be retained or where existing or proposed BMP/facility areas require protection from construction activities. Design Specifications 1. Minimizing clearing should be incorporated into the site design. Clearing limits must be marked on the Small Site CSWPP plan. 2. On the ground, clearing limits must be clearly marked with brightly colored tape or plastic or metal safety fencing. If tape is used, it should be supported by vegetation or stakes, and should be about 3 to 6 feet high and highly visible. BMP/facility areas to be protected should be marked with brightly colored silt fence to add sedimentation protection. Equipment operators should be informed of areas of vegetation that are to be left undisturbed and BMP/facility areas that are to be protected. 3. The duff layer, native top soil, and natural vegetation shall be retained in an undisturbed state to the maximum extent practicable. If it is not practicable to retain the duff layer in place, it should be stockpiled on-site, covered to prevent erosion, and replaced immediately upon completion of the ground disturbing activities. Maintenance Fencing shall be inspected regularly and repaired or replaced as needed. C.3.6 SILT FENCE Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use 1. Silt fence may be used downslope of all disturbed areas. 2. Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment trap or pond. Design and Installation Specifications 1. See Figure C.3.6.A and Figure C.3.6.B for details. SECTION C.3 CONSTRUCTION STORMWATER POLLUTION PREVENTION (CSWPP) MEASURES 6/22/2022 2022 City of Renton Surface Water Design Manual C-118 2. The geotextile used must meet the standards listed below. A copy of the manufacturer’s fabric specifications must be available onsite. AOS (ASTM D4751) 30–100 sieve size (0.60–0.15 mm) for slit film 50–100 sieve size (0.30–0.15 mm) for other fabrics Water Permittivity (ASTM D4491) 0.02 sec-1 minimum Grab Tensile Strength (ASTM D4632) (see Specification Note 3) 180 lbs. min. for extra strength fabric 100 lbs. min. for standard strength fabric Grab Tensile Elongation (ASTM D4632) 30% max. (woven) Ultraviolet Resistance (ASTM D4355) 70% min. 3. Standard strength fabric requires wire backing to increase the strength of the fence. Wire backing or closer post spacing may be required for extra strength fabric if field performance warrants a stronger fence. 4. Where the fence is installed, the slope shall be no steeper than 2H:1V. 5. If a typical silt fence (per Figure C.3.6.A) is used, the standard 4 x 4 trench may be reduced as long as the bottom 8 inches of the silt fence fabric is well buried and secured in a trench that stabilizes the fence and does not allow water to bypass or undermine the silt fence. Maintenance Standards 1. Any damage shall be repaired immediately. 2. If concentrated flows are evident uphill of the fence, they must be intercepted and conveyed to a sediment trap or pond. 3. It is important to check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. 4. Sediment must be removed when the sediment is 6 inches high. 5. If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, it shall be replaced. C.3.6 SILT FENCE 2022 City of Renton Surface Water Design Manual 6/22/2022 C-119 FIGURE C.3.6.A SILT FENCE FIGURE C.3.6.B SILT FENCE INSTALLATION AND MAINTENANCE 2"X2" BY 14 Ga. WIRE OR EQUIVALENT, IF STANDARD STRENGTH FABRIC USED NOTE: FILTER FABRIC FENCES SHALL BE INSTALLED ALONG CONTOURS WHENEVER POSSIBLE JOINTS IN FILTER FABRIC SHALL BE SPLICED AT POSTS. USE STAPLES, WIRE RINGS OR EQUIVALENT TO ATTACH FABRIC TO POSTS. FILTER FABRIC BACKFILL TRENCH WITH NATIVE SOIL OR 3/4" TO 1-1/2" WASHED GRAVEL MINIMUM 4"x4" TRENCH 2"x4" WOOD POSTS, STEEL FENCE POSTS, REBAR, OR EQUIVALENT POST SPACING MAY BE INCREASED TO 8' IF WIRE BACKING IS USED 6' MAX.2' MIN.12" MIN. C.3.9 STORM DRAIN INLET PROTECTION 2022 City of Renton Surface Water Design Manual 6/22/2022 C-121 C.3.9 STORM DRAIN INLET PROTECTION Purpose Storm drain inlets are protected to prevent coarse sediment from entering storm drainage systems. Temporary devices around storm drains assist in improving the quality of water discharged to inlets or catch basins by ponding sediment-laden water. These devices are effective only for relatively small drainage areas. Conditions of Use 1. Protection shall be provided for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless the runoff that enters the catch basin will be conveyed to a sediment pond or trap. 2. Inlet protection may be used anywhere at the applicant’s discretion to protect the drainage system. This will, however, require more maintenance, and it is highly likely that the drainage system will still require some cleaning. 3. The contributing drainage area must not be larger than one acre. Design and Installation Specifications 1. There are many options for protecting storm drain inlets. Two commonly used options are filter fabric protection and catch basin inserts. Filter fabric protection (see Figure C.3.9.A) is filter fabric (geotextile) placed over the grate. This method is generally very ineffective and requires intense maintenance efforts. Therefore, filter fabric protection is not allowed in the City of Renton. Catch basin inserts (see Figure C.3.9.B) are manufactured devices that nest inside a catch basin. This method also requires a high frequency of maintenance to be effective. Trapping sediment in the catch basins is unlikely to improve the water quality of runoff if it is treated in a pond or trap because the coarse particles that are trapped at the catch basin settle out very quickly in the pond or trap. Catch basin protection normally only improves water quality where there is SECTION C.3 CONSTRUCTION STORMWATER POLLUTION PREVENTION (CSWPP) MEASURES 6/22/2022 2022 City of Renton Surface Water Design Manual C-122 no treatment facility downstream. In these circumstances, catch basin protection is an important last line of defense. It is not, however, a substitute for preventing erosion. 2. It is sometimes possible to construct a small sump around the catch basin before final surfacing of the road. This is allowed because it can be a very effective method of sediment control. 3. Block and gravel filters, gravel and wire mesh filter barriers, and bag barriers filled with various filtering media placed around catch basins can be effective when the drainage area is 1 acre or less and flows do not exceed 0.5 cfs. It is necessary to allow for overtopping to prevent flooding. Many manufacturers have various inlet protection filters that are very effective in keeping sediment-laden water from entering the storm drainage system. The following are examples of a few common methods. a) Block and gravel filters (Figure C.3.9.C) are a barrier formed around an inlet with standard concrete block and gravel, installed as follows: Height is 1 to 2 feet above the inlet. Recess the first row of blocks 2 inches into the ground for stability. Support subsequent rows by placing a 2 x 4 through the concrete block opening. Do not use mortar. Lay some blocks in the bottom row on their side for dewatering the pooled water. Place cloth or mesh with ½ inch openings over all block openings. Place gravel below the top of blocks on slopes of 2:1 or flatter. An alternate design is a gravel donut. b) Gravel and wire mesh filters consist of a gravel barrier placed over the top of an inlet. This structure generally does not provide overflow. Install as follows: Cloth or comparable wire mesh with ½ inch openings is placed over inlet. Coarse aggregate covers the cloth or mesh. Height/depth of gravel should be 1 foot or more, 18 inches wider than inlet on all sides. c) Curb inlet protection with a wooden weir is a barrier formed around an inlet with a wooden frame and gravel, installed as follows: Construct a frame and attach wire mesh (½ inch openings) and filter fabric to the frame. Pile coarse washed aggregate against the wire/fabric. Place weight on frame anchors. d) Curb and gutter sediment barriers (Figure C.3.9.D) consist of sandbags or rock berms (riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape, installed as follows: Bags of either burlap or woven geotextile fabric, filled with a variety of media such as gravel, wood chips, compost or sand stacked tightly allows water to pond and allows sediment to separate from runoff. Leave a “one bag gap” in the top row of the barrier to provide a spillway for overflow. Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 x 3 and at least 2 feet from the inlet. Construct a horseshoe shaped sedimentation trap on the outside of the berm to sediment trap standards for protecting a culvert inlet. 4. Excavated drop inlet sediment traps are appropriate where relatively heavy flows are expected and overflow capability is needed. If emergency overflow is provided, additional end-of-pipe treatment may be required. Excavated drop inlets consist of an excavated impoundment area around a storm drain. Sediment settles out of the stormwater prior to enter the drain. Install according to the following specifications: C.3.9 STORM DRAIN INLET PROTECTION 2022 City of Renton Surface Water Design Manual 6/22/2022 C-123 a) The impoundment area should have a depth of 1 to 2 feet measured from the crest of the inlet structure. b) Side slopes of the excavated area must be no steeper than 2:1. c) Minimum volume of the excavated area should be 35 cubic yards. d) Install provisions for draining the area to prevent standing water problems. e) Keep the area clear of debris. f) Weep holes may be drilled into the side of the inlet. g) Protect weep holes with wire mesh and washed aggregate. h) Weep holes must be sealed when removing and stabilizing excavated area. i) A temporary dike may be necessary on the down slope side of the structure to prevent bypass flow. Maintenance Standards 1. Any accumulated sediment on or around inlet protection shall be removed immediately. Sediment shall not be removed with water, and all sediment must be disposed of as fill on site or hauled off site. 2. Any sediment in the catch basin insert shall be removed when the sediment has filled one-third of the available storage. The filter media for the insert shall be cleaned or replaced at least monthly. 3. Regular maintenance is critical for all forms of catch basin/inlet protection. Unlike many forms of protection that fail gradually, catch basin protection will fail suddenly and completely if not maintained properly. SECTION C.3 CONSTRUCTION STORMWATER POLLUTION PREVENTION (CSWPP) MEASURES 6/22/2022 2022 City of Renton Surface Water Design Manual C-124 FIGURE C.3.9.A FILTER FABRIC PROTECTION (NOT ALLOWED) FIGURE C.3.9.B CATCH BASIN INSERT CATCH BASIN NOTE: ONLY TO BE USED WHERE PONDING OF WATER ABOVE THE CATCH BASIN WILL NOT CAUSE TRAFFIC PROBLEMS AND WHERE OVERFLOW WILL NOT RESULT IN EROSION OF SLOPES. GRATESTANDARD STRENGTH FILTER FABRIC NOTE: THIS DETAIL IS ONLY SCHEMATIC. ANY INSERT IS ALLOWED THAT HAS:A MIN. 0.5 C.F. OF STORAGE,THE MEANS TO DEWATER THE STORED SEDIMENT,AN OVERFLOW, ANDCAN BE EASILY MAINTAINED. OVERFLOW GRATECATCH BASIN POROUS BOTTOM SOLID WALLS FILTER MEDIA FOR DEWATERING C.3.10 SEEDING 2022 City of Renton Surface Water Design Manual 6/22/2022 C-127 C.3.10 SEEDING Purpose Seeding is intended to reduce erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducing erosion. Conditions of Use 1. Seeding shall be used throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. 2. At the City’s discretion, seeding without mulch during the dry season is allowed even though it will take more than seven days to develop an effective cover. Mulch is, however, recommended at all times because it protects seeds from heat, moisture loss, and transport due to runoff. 3. Prior to the beginning of the wet season, all disturbed areas shall be reviewed to identify which ones can be seeded in preparation for the winter rains. Disturbed areas shall be seeded within one week of the beginning of the wet season. A sketch map of those areas to be seeded and those areas to remain uncovered shall be submitted to the CED inspector. The CED inspector may require seeding of additional areas in order to protect surface waters, adjacent properties, or drainage facilities. 4. At final site stabilization, all disturbed areas not otherwise vegetated or stabilized shall be seeded and mulched. Design and Installation Specifications 1. The best time to seed is fall (late September to October) or in spring (mid-March to June). Irrigation is required during the first summer following installation if seeding occurs in spring or summer or during prolonged dry times of year. Areas may also be seeded during the winter months, but it may take additional spring seeding applications to develop a dense groundcover due to cold temperatures. The application and maintenance of mulch is critical for winter seeding. 2. To prevent seed from being washed away, confirm that all required surface water control measures have been installed. 3. The seedbed should not be compacted because soils that are well compacted will not vegetate as quickly or thoroughly. 4. In general, 10-20-20 N-P-K (nitrogen-phosphorus-potassium) fertilizer may be used at a rate of 90 pounds per acre. Slow-release fertilizers are preferred because they are more efficient and have fewer environmental impacts. It is recommended that areas being seeded for final landscaping conduct soil tests to determine the exact type and quantity of fertilizer needed. This will prevent the over- application of fertilizer. Disturbed areas within 200 feet of water bodies and wetlands must use slow- release low-phosphorus fertilizer (typical proportions 3-1-2 N-P-K). 5. The following requirements apply to mulching: a) Mulch is always required for seeding slopes greater than 3H:1V (see Section D.4.2.1). b) If seeding during the wet season, mulch is required. c) The use of mulch may be required during the dry season at the City’s discretion if grass growth is expected to be slow, the soils are highly erodible due to soil type or gradient, there is a water body close to the disturbed area, or significant precipitation is anticipated before the grass will provide effective cover. d) Mulch may be applied on top of the seed or simultaneously by hydroseeding. 6. Hydroseeding is allowed as long as tackifier is included. Hydroseeding with wood fiber mulch is adequate during the dry season. During the wet season, the application rate shall be doubled because the mulch and tackifier used in hydroseeding break down fairly rapidly. SECTION C.3 CONSTRUCTION STORMWATER POLLUTION PREVENTION (CSWPP) MEASURES 6/22/2022 2022 City of Renton Surface Water Design Manual C-128 7. Areas to be permanently landscaped shall use soil amendments. Good quality topsoil shall be tilled into the top six inches to reduce the need for fertilizer and improve the overall soil quality. Most native soils will require the addition of four inches of well-rotted compost to be tilled into the soil to provide a good quality topsoil. Compost used should meet specifications in Reference Section 11-C. 8. The seed mixes listed below in Table C.3.10.A and Table C.3.10.B include recommended mixes for both temporary and permanent seeding. These mixes, with the exception of the wetland mix, shall be applied at a rate of 80 to 100 seeds per square foot. Wet sites should apply 120 to 150 seeds per square foot. Local suppliers should be consulted for information on current Pure Live Seed (PLS) rates and species specific seeds per pound in order to determine seed mix PLS pounds of seed per acre. The appropriate mix depends on a variety of factors, including exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the City may be used. TABLE C.3.10.A EROSION CONTROL SEED MIX Common Name/Latin Name % Species Composition Desired Seeds per Square Foot PLS pounds/Acre Spike bentgrass Agrostis exarata 6 9 0.1 California brome/Bromus carinatus 15 23 9.8 Tufted hairgrass/Deschampsia cespitosa 15 23 0.4 Blue wildrye/Elymus glaucus 18 27 10.7 California oatgrass/Danthonia californica 18 27 5.6 Native red fescue/Festuca rubra var. rubra 18 27 2.4 Meadow barley/Hordeum brachyantherum 10 15 7.7 TABLE C.3.10.B LANDSCAPING SEED MIX Common Name/Latin Name % Species Composition Desired Seeds per Square Foot PLS pounds/Acre Sideoats grama/Bouteloua curtipendula 20 30 6.8 California oatgrass/Danthonia californica 20 30 6.2 Native red fescue/Festuca rubra var. rubra 30 45 3.9 Prairie junegrass/Koeleria macrantha 30 45 0.8 Maintenance Standards for Seeding 1. Any seeded areas that fail to establish at least 80 percent cover within one month shall be reseeded. If reseeding is ineffective, an alternate method, such as sodding or nets/blankets, shall be used. If winter weather prevents adequate seed establishment and growth, this time limit may be relaxed at the discretion of the City when critical areas would otherwise be protected. 2. After adequate cover is achieved, any areas that experience erosion shall be re-seeded and protected by mulch. If the erosion problem is drainage related, the problem shall be fixed and the eroded area re- seeded and protected by mulch. 3. Seeded areas shall be supplied with adequate moisture, but not watered to the extent that it causes runoff. D.2.1 ESC MEASURES 2022 City of Renton Surface Water Design Manual 6/22/2022 D-67 D.2.1.8 DUST CONTROL Preventative measures to minimize the wind transport of soil shall be taken when a traffic hazard may be created or when sediment transported by wind is likely to be deposited in water resources or adjacent properties. Purpose: To prevent wind transport of dust from exposed soil surfaces onto roadways, drainage ways, and surface waters. When to Install: Dust control shall be implemented when exposed soils are dry to the point that wind transport is possible and roadways, drainage ways, or surface waters are likely to be impacted. Dust control measures may consist of chemical, structural, or mechanical methods. Measures to Install: Water is the most common dust control (or palliative) used in the area. When using water for dust control, the exposed soils shall be sprayed until wet, but runoff shall not be generated by spraying. Calcium chloride, Magnesium chloride, Lignin derivatives, Tree Resin Emulsions, and Synthetic Polymer Emulsions may also be used for dust control. Exposed areas shall be re-sprayed as needed. Oil shall not be used for dust control. The following table lists many common dust control measures. Some of the measures are not recommended for use in the City and must have prior approval prior to use from the CED inspector assigned to specific projects. TABLE D.2.1.8.A DUST CONTROL MEASURES Method Considerations Site Preparation Recommended Application Rate Water -Most commonly used practice -Evaporates quickly -Lasts less than 1 day For all liquid agents: -Blade a small surface -Crown or slope surface to avoid ponding -Compact soils if needed -Uniformly pre-wet at 0.03 – 0.3 gal/sq yd -Apply solution under pressure. Overlap solution 6 – 12 inches -Allow treated area to cure 0 – 4 hours -Compact area after curing -Apply second treatment before first treatment becomes ineffective 0.125 gal/sq yd every 20 to 30 minutes Salts Calcium Chloride (CaCl) -Restricts evaporation -Lasts 6–12 months -Can be corrosive -Less effective in low humidity -Can build up in soils and leach by rain Apply 38% solution at 1.21L/m2 (0.27 gal/yd2) or as loose dry granules per manufacturer SECTION D.2 GENERAL CSWPP REQUIREMENTS 6/22/2022 2022 City of Renton Surface Water Design Manual D-68 TABLE D.2.1.8.A DUST CONTROL MEASURES Method Considerations Site Preparation Recommended Application Rate Magnesium Chloride (MgCl) -Restricts evaporation -Works at higher temperatures and lower humidity than CaCl -May be more costly than CaCl Apply 26 – 32% solution at 2.3 L/m2 (0.5 gal/yd2) Sodium Chloride (NaCl) -Effective over smaller range of conditions -Less expensive -Can be corrosive -Less effective in low humidity Per Manufacturer Silicates -Generally expensive -Available in small quantities -Require Second application Surfactants -High evaporation rates -Effective for short time periods -Must apply frequently Copolymers -Forms semi-permeable transparent crust -Resists ultraviolet radiation and moisture induced breakdown -Last 1 to 2 years 750 – 940 L/ha (80 – 100 gal/ac) Petroleum Products -Used oil is prohibited as a dust control method -Bind soil particles -May hinder foliage growth -Environmental and aesthetic concerns -Higher cost Use 57 – 63% resins as base. Apply at 750 – 940 L/ha (80–100 gal/ac) Lignin Sulfonate -Paper industry waste product -Acts as dispersing agent -Best in dry climates -Can be slippery -Will decrease Dissolved Oxygen in waterways therefore cannot be used adjacent to surface water systems Loosen surface 25–50 mm (1–2 inches) Need 4–8% fines Vegetable Oils -Coat grains of soils, so limited binding ability -May become brittle -Limited availability Per Manufacturer Spray on Adhesives -Available as organic or synthetic -Effective on dry, hard soils -Forms a crust -Can last 3 to 4 years Per Manufacturer ’ SECTION D.2 GENERAL CSWPP REQUIREMENTS 6/22/2022 2022 City of Renton Surface Water Design Manual D-78 D.2.2.3 SAWCUTTING AND SURFACING POLLUTION PREVENTION Purpose Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting), both of which can violate the water quality standards in the receiving water. Concrete spillage or concrete discharge to surface waters of the State is prohibited. Use this BMP to minimize and eliminate process water and slurry created through sawcutting or surfacing from entering waters of the State. Conditions of Use Utilize these management practices anytime sawcutting or surfacing operations take place. Sawcutting and surfacing operations include, but are not limited to, sawing, coring, grinding, roughening, hydro- demolition, bridge and road surfacing Design and Installation Specifications 1. Vacuum slurry and cuttings during cutting and surfacing operations. 2. Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight. 3. Slurry and cuttings shall not drain to any natural or constructed drainage conveyance including stormwater systems. This may require temporarily blocking catch basins. 4. Dispose of collected slurry and cuttings in a manner that does not violate ground water or surface water quality standards. 5. Do not allow process water generated during hydro-demolition, surface roughening or similar operations to drain to any natural or constructed drainage conveyance including stormwater systems. Dispose process water in a manner that does not violate ground water or surface water quality standards. 6. Handle and dispose cleaning waste material and demolition debris in a manner that does not cause contamination of water. Dispose of sweeping material from a pick-up sweeper at an appropriate disposal site. Maintenance Standards Continually monitor operations to determine whether slurry, cuttings, or process water could enter waters of the state. If inspections show that a violation of water quality standards could occur, stop operations and immediately implement preventive measures such as berms, barriers, secondary containment, and vacuum trucks. D.2.2.4 MATERIAL DELIVERY, STORAGE, AND CONTAINMENT Purpose Prevent, reduce, or eliminate the discharge of pollutants to the stormwater system or watercourses from material delivery and storage. Minimize the storage of hazardous materials onsite, store materials in a designated area, and install secondary containment. Conditions of Use These procedures are suitable for use at all construction sites with delivery and storage of the following materials: Petroleum products such as fuel, oil and grease Soil stabilizers and binders (e.g., Polyacrylamide) Fertilizers, pesticides and herbicides Detergents Asphalt and concrete compounds D.2.2 SWPPS MEASURES 2022 City of Renton Surface Water Design Manual 6/22/2022 D-79 Hazardous chemicals such as acids, lime, adhesives, paints, solvents and curing compounds Any other material that may be detrimental if released to the environment Design and Installation Specifications The following steps should be taken to minimize risk: 1. Temporary storage area should be located away from vehicular traffic, near the construction entrance(s), and away from waterways or storm drains. 2. Material Safety Data Sheets (MSDS) should be supplied for all materials stored. Chemicals should be kept in their original labeled containers. 3. Hazardous material storage onsite should be minimized. 4. Hazardous materials should be handled as infrequently as possible. 5. During the wet weather season (October 1 – April 30), consider storing materials in a covered area. 6. Materials should be stored in secondary containments, such as earthen dike, horse trough, or even a children’s wading pool for non-reactive materials such as detergents, oil, grease, and paints. Small amounts of material may be secondarily contained in “bus boy” trays or concrete mixing trays. 7. Do not store chemicals, drums, or bagged materials directly on the ground. Place these items on a pallet and, when possible, and within secondary containment. 8. If drums must be kept uncovered, store them at a slight angle to reduce ponding of rainwater on the lids to reduce corrosion. Domed plastic covers are inexpensive and snap to the top of drums, preventing water from collecting. Material Storage Areas and Secondary Containment Practices: 1. Liquids, petroleum products, and substances listed in 40 CFR Parts 110, 117, or 302 shall be stored in approved containers and drums and shall not be overfilled. Containers and drums shall be stored in temporary secondary containment facilities. 2. Temporary secondary containment facilities shall provide for a spill containment volume able to contain 10% of the total enclosed container volume of all containers, or 110% of the capacity of the largest container within its boundary, whichever is greater. 3. Secondary containment facilities shall be impervious to the materials stored therein for a minimum contact time of 72 hours. 4. Secondary containment facilities shall be maintained free of accumulated rainwater and spills. In the event of spills or leaks, accumulated rainwater and spills shall be collected and placed into drums. These liquids shall be handled as hazardous waste unless testing determines them to be non- hazardous. 5. Sufficient separation should be provided between stored containers to allow for spill cleanup and emergency response access. 6. During the wet weather season (October 1 – April 30), each secondary containment facility shall be covered during non-working days, prior to and during rain events. 7. Keep material storage areas clean, organized and equipped with an ample supply of appropriate spill clean-up material (spill kit). 8. The spill kit should include, at a minimum: 1-Water Resistant Nylon Bag 3-Oil Absorbent Socks 3″ x 4′ 2-Oil Absorbent Socks 3″ x 10′ 12-Oil Absorbent Pads 17″ x 19″ SECTION D.2 GENERAL CSWPP REQUIREMENTS 6/22/2022 2022 City of Renton Surface Water Design Manual D-80 1-Pair Splash Resistant Goggles 3-Pair Nitrile Gloves 10-Disposable Bags with Ties Instructions μ C. Correspondence P a g e | 33 P a g e | 34 D. Site Inspection Form Construction Stormwater Site Inspection Form Page 1 Project Name Permit # Inspection Date Time Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre Print Name: Approximate rainfall amount since the last inspection (in inches): Approximate rainfall amount in the last 24 hours (in inches): Current Weather Clear Cloudy Mist Rain Wind Fog A. Type of inspection: Weekly Post Storm Event Other B. Phase of Active Construction (check all that apply): Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads Concrete pours Vertical Construction/buildings Utilities Offsite improvements Site temporary stabilized Final stabilization C. Questions: 1. Were all areas of construction and discharge points inspected? Yes No 2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No 3. Was a water quality sample taken during inspection? (refer to permit conditions S4 & S5) Yes No 4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No 5. If yes to #4 was it reported to Ecology? Yes No 6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken, and when. *If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33 cm or greater. Sampling Results: Date: Parameter Method (circle one) Result Other/Note NTU cm pH Turbidity tube, meter, laboratory pH Paper, kit, meter Construction Stormwater Site Inspection Form Page 2 D. Check the observed status of all items. Provide “Action Required “details and dates. Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 1 Clearing Limits Before beginning land disturbing activities are all clearing limits, natural resource areas (streams, wetlands, buffers, trees) protected with barriers or similar BMPs? (high visibility recommended) 2 Construction Access Construction access is stabilized with quarry spalls or equivalent BMP to prevent sediment from being tracked onto roads? Sediment tracked onto the road way was cleaned thoroughly at the end of the day or more frequent as necessary. 3 Control Flow Rates Are flow control measures installed to control stormwater volumes and velocity during construction and do they protect downstream properties and waterways from erosion? If permanent infiltration ponds are used for flow control during construction, are they protected from siltation? 4 Sediment Controls All perimeter sediment controls (e.g. silt fence, wattles, compost socks, berms, etc.) installed, and maintained in accordance with the Stormwater Pollution Prevention Plan (SWPPP). Sediment control BMPs (sediment ponds, traps, filters etc.) have been constructed and functional as the first step of grading. Stormwater runoff from disturbed areas is directed to sediment removal BMP. 5 Stabilize Soils Have exposed un‐worked soils been stabilized with effective BMP to prevent erosion and sediment deposition? Construction Stormwater Site Inspection Form Page 3 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 5 Stabilize Soils Cont. Are stockpiles stabilized from erosion, protected with sediment trapping measures and located away from drain inlet, waterways, and drainage channels? Have soils been stabilized at the end of the shift, before a holiday or weekend if needed based on the weather forecast? 6 Protect Slopes Has stormwater and ground water been diverted away from slopes and disturbed areas with interceptor dikes, pipes and or swales? Is off‐site storm water managed separately from stormwater generated on the site? Is excavated material placed on uphill side of trenches consistent with safety and space considerations? Have check dams been placed at regular intervals within constructed channels that are cut down a slope? 7 Drain Inlets Storm drain inlets made operable during construction are protected. Are existing storm drains within the influence of the project protected? 8 Stabilize Channel and Outlets Have all on‐site conveyance channels been designed, constructed and stabilized to prevent erosion from expected peak flows? Is stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream conveyance systems? 9 Control Pollutants Are waste materials and demolition debris handled and disposed of to prevent contamination of stormwater? Has cover been provided for all chemicals, liquid products, petroleum products, and other material? Has secondary containment been provided capable of containing 110% of the volume? Were contaminated surfaces cleaned immediately after a spill incident? Were BMPs used to prevent contamination of stormwater by a pH modifying sources? Construction Stormwater Site Inspection Form Page 4 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 9 Cont. Wheel wash wastewater is handled and disposed of properly. 10 Control Dewatering Concrete washout in designated areas. No washout or excess concrete on the ground. Dewatering has been done to an approved source and in compliance with the SWPPP. Were there any clean non turbid dewatering discharges? 11 Maintain BMP Are all temporary and permanent erosion and sediment control BMPs maintained to perform as intended? 12 Manage the Project Has the project been phased to the maximum degree practicable? Has regular inspection, monitoring and maintenance been performed as required by the permit? Has the SWPPP been updated, implemented and records maintained? E. Check all areas that have been inspected. All in place BMPs All disturbed soils All concrete wash out area All material storage areas All discharge locations All equipment storage areas All construction entrances/exits F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number; be specific on location and work needed. Document, initial, and date when the corrective action has been completed and inspected. Element # Description and Location Action Required Completion Date Initials Attach additional page if needed Sign the following certification: “I certify that this report is true, accurate, and complete, to the best of my knowledge and belief” Inspected by: (print) (Signature) Date: Title/Qualification of Inspector: P a g e | 35 E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information N/A P a g e | 36 P a g e | 37 G. Contaminated Site Information N/A P a g e | 38 H. Engineering Calculations N/A Appendix E Bond Quantities, Facility Summaries And Declaration Of Covenant 1055 South Grady Way – 6 th Floor | Renton, WA 98057 (425) 430-7200 • • Section I: Project Information • • • Section II: Bond Quantities Worksheets • •Section II.a EROSION CONTROL (Stabilization/Erosion Sediment Control (ESC)) •Section II.b TRANSPORTATION (Street and Site Improvements) •Section II.c DRAINAGE (Drainage and Stormwater Facilities): •Section II.d WATER - ONLY APPLICABLE IF WATER SERVICE IS PROVIDED BY CITY OF RENTON •Section II.e SANITARY SEWER - ONLY APPLICABLE IF SEWER SERVICE IS PROVIDED BY CITY OF RENTON • • • • • • Section III. Bond Worksheet • This section calculates the required Permit Bond for construction permit issuance as well as the required Maintenance Bond for project close-out submittals to release the permit bond on a project. All unit prices include labor, equipment, materials, overhead, profit, and taxes. Complete the 'Quantity' columns for each of the appropriate section(s). Include existing Right-of-Way (ROW), Future Public Improvements and Private Improvements. The 'Quantity Remaining' column is only to be used when a project is under construction. The City allows one (1) bond reduction during the life of the project with the exception of the maintenance period reduction. Excel will auto-calculate and auto-populate the relevant fields and subtotals throughout the document. Only the 'Quantity' columns should need completing. Additional items not included in the lists can be added under the "write-in" sections. Provide a complete description, cost estimate and unit of measure for each write-in item. Note: Private improvements, with the exception of stormwater facilities, are not included in the bond amount calculation, but must be entered on the form. Stormwater facilities (public and private) are required to be included in the bond amount. BOND QUANTITY WORKSHEET INSTRUCTIONS This worksheet is intended to be a "working" copy of the bond quantity worksheet, which will be used throughout all phases of the project, from initial submittal to project close-out approval. Submit this workbook, in its entirety, as follows: The following forms are to be completed by the engineer/developer/applicant as applicable to the project: The Bond Worksheet form will auto-calculate and auto-populate from the information provided in Section I and Section II. This section includes all pertinent information for the project Section II contains a separate spreadsheet TAB for each of the following specialties: (1) electronic copy (.xlsx format) and (1) hard copy of the entire workbook for civil construction permit submittal. Hard copies are to be included as part of the Technical Information Report (TIR). (1) electronic copy (.xlsx format) and (1) hard copy of the entire workbook for final close-out submittal. This section must be completed in its entirety Information from this section auto-populates to all other relevant areas of the workbook Page 1 of 15 Ref 8-H Bond Quantity Worksheet INSTRUCTIONS Version: 4/1/2024 Printed 8/12/2025 1055 South Grady Way – 6 th Floor | Renton, WA 98057 (425) 430-7200 Date Prepared: Name: PE Registration No: Firm Name: Firm Address: Phone No. Email Address: Project Name: Project Owner: CED Plan # (LUA):Phone: CED Permit # (C):Address: Site Address: Street Intersection:Addt'l Project Owner: Parcel #(s):Phone: Address: Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No:NO Water Service Provided by: If Yes, Provide Forest Practice Permit #:Sewer Service Provided by: SITE IMPROVEMENT BOND QUANTITY WORKSHEET PROJECT INFORMATION CITY OF RENTON CITY OF RENTON Engineer Stamp Required (all cost estimates must have original wet stamp and signature) Clearing and Grading Utility Providers N/A Project Location and Description Project Owner Information Meadow Ave Short Plat RENTON, WA 98058 334270-0570 HUY NGUYEN LUA21-000084, SHPL-A (206) 334-2245 Prepared by: FOR APPROVALProject Phase 1 CostaP@encompasses.net Costa Philippides 38375 Encompass Engineering & Surveying 165 NE Juniper Street, Suite 201, Issaquah, WA 98027 (425) 392-0250 15400 SE 155TH PLACE, UNIT 99PR21-000093 10,919.70$ Abbreviated Legal Description: TRACTS 112 & 113, HILLMANS LAKE WASHINGTON GARDEN OF EDEN ADDN TO SEATTLE NO. 2 Total Estimated Construction Costs E A + B + C + D 73,998.89$ Estimated Civil Construction Permit - Construction Costs2 Stormwater (Drainage)C 33,591.87$ As outlined in City Ordinance No. 4345, 50% of the plan review and inspection fees are to be paid at Permit Submittal. The balance is due at Permit Issuance. Significant changes or additional review cycles (beyond 3 cycles) during the review process may result in adjustments to the final review fees. Roadway (Erosion Control + Transportation)D 1,691.73$ Water A 27,795.60$ Wastewater (Sanitary Sewer)B Page 2 of 15 Ref 8-H Bond Quantity Worksheet SECTION I PROJECT INFORMATION Version 4/1/2024 Printed 8/12/2025 10.3%2 All prices include labor, equipment, materials, overhead, profit, and taxes. City of Renton Sales Tax is: 1 Select the current project status/phase from the following options: For Approval - Preliminary Data Enclosed, pending approval from the City; For Construction - Estimated Data Enclosed, Plans have been approved for contruction by the City; Project Closeout - Final Costs and Quantities Enclosed for Project Close-out Submittal Page 3 of 15 Ref 8-H Bond Quantity Worksheet SECTION I PROJECT INFORMATION Version 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Unit Reference #Price Unit Quantity Cost Backfill & compaction-embankment ESC-1 7.50$ CY Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 90.00$ Each Catch Basin Protection ESC-3 145.00$ Each 5 725.00 Crushed surfacing 1 1/4" minus ESC-4 WSDOT 9-03.9(3)110.00$ CY Ditching ESC-5 10.50$ CY Excavation-bulk ESC-6 2.30$ CY Fence, silt ESC-7 SWDM 5.4.3.1 5.00$ LF Fence, Temporary (NGPE)ESC-8 1.75$ LF 140 245.00 Geotextile Fabric ESC-9 3.00$ SY Hay Bale Silt Trap ESC-10 0.60$ Each Hydroseeding ESC-11 SWDM 5.4.2.4 0.90$ SY Interceptor Swale / Dike ESC-12 1.15$ LF Jute Mesh ESC-13 SWDM 5.4.2.2 4.00$ SY Level Spreader ESC-14 2.00$ LF Mulch, by hand, straw, 3" deep ESC-15 SWDM 5.4.2.1 2.90$ SY Mulch, by machine, straw, 2" deep ESC-16 SWDM 5.4.2.1 2.30$ SY Piping, temporary, CPP, 6"ESC-17 13.75$ LF Piping, temporary, CPP, 8"ESC-18 16.00$ LF Piping, temporary, CPP, 12"ESC-19 20.50$ LF Plastic covering, 6mm thick, sandbagged ESC-20 SWDM 5.4.2.3 4.60$ SY Rip Rap, machine placed; slopes ESC-21 WSDOT 9-13.1(2)51.00$ CY Rock Construction Entrance, 50'x15'x1'ESC-22 SWDM 5.4.4.1 2,050.00$ Each Rock Construction Entrance, 100'x15'x1'ESC-23 SWDM 5.4.4.1 3,675.00$ Each Sediment pond riser assembly ESC-24 SWDM 5.4.5.2 2,525.00$ Each Sediment trap, 5' high berm ESC-25 SWDM 5.4.5.1 22.00$ LF Sed. trap, 5' high, riprapped spillway berm section ESC-26 SWDM 5.4.5.1 80.00$ LF Seeding, by hand ESC-27 SWDM 5.4.2.4 1.15$ SY Sodding, 1" deep, level ground ESC-28 SWDM 5.4.2.5 9.20$ SY Sodding, 1" deep, sloped ground ESC-29 SWDM 5.4.2.5 11.50$ SY TESC Supervisor ESC-30 125.00$ HR Water truck, dust control ESC-31 SWDM 5.4.7 160.00$ HR Unit Reference #Price Unit Quantity Cost EROSION/SEDIMENT SUBTOTAL:970.00 SALES TAX @ 10.3%99.91 EROSION/SEDIMENT TOTAL:1,069.91 (A) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR EROSION & SEDIMENT CONTROL Description No. (A) WRITE-IN-ITEMS Page 4 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.a EROSION_CONTROL Version: 4/01/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost GENERAL ITEMS Backfill & Compaction- embankment GI-1 7.00$ CY Backfill & Compaction- trench GI-2 10.25$ CY 55 563.75 Clear/Remove Brush, by hand (SY)GI-3 1.15$ SY Bollards - fixed GI-4 275.00$ Each Bollards - removable GI-5 520.00$ Each Clearing/Grubbing/Tree Removal GI-6 11,475.00$ Acre Excavation - bulk GI-7 2.30$ CY Excavation - Trench GI-8 5.75$ CY Fencing, cedar, 6' high GI-9 23.00$ LF Fencing, chain link, 4'GI-10 44.00$ LF Fencing, chain link, vinyl coated, 6' high GI-11 23.00$ LF Fencing, chain link, gate, vinyl coated, 20' GI-12 1,600.00$ Each Fill & compact - common barrow GI-13 28.75$ CY Fill & compact - gravel base GI-14 31.00$ CY Fill & compact - screened topsoil GI-15 44.75$ CY Gabion, 12" deep, stone filled mesh GI-16 74.50$ SY Gabion, 18" deep, stone filled mesh GI-17 103.25$ SY Gabion, 36" deep, stone filled mesh GI-18 172.00$ SY Grading, fine, by hand GI-19 2.90$ SY Grading, fine, with grader GI-20 2.30$ SY Monuments, 3' Long GI-21 1,025.00$ Each Sensitive Areas Sign GI-22 8.00$ Each Sodding, 1" deep, sloped ground GI-23 9.25$ SY Surveying, line & grade GI-24 975.00$ Day Surveying, lot location/lines GI-25 2,050.00$ Acre Topsoil Type A (imported)GI-26 32.75$ CY Traffic control crew ( 2 flaggers )GI-27 137.75$ HR Trail, 4" chipped wood GI-28 9.15$ SY Trail, 4" crushed cinder GI-29 10.25$ SY Trail, 4" top course GI-30 13.75$ SY Conduit, 2"GI-31 5.75$ LF Wall, retaining, concrete GI-32 63.00$ SF Wall, rockery GI-33 17.25$ SF SUBTOTAL THIS PAGE:563.75 (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) Page 5 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) ROAD IMPROVEMENT/PAVEMENT/SURFACING AC Grinding, 4' wide machine < 1000sy RI-1 34.50$ SY AC Grinding, 4' wide machine 1000-2000sy RI-2 18.25$ SY AC Grinding, 4' wide machine > 2000sy RI-3 11.50$ SY AC Removal/Disposal RI-4 40.00$ SY Barricade, Type III ( Permanent )RI-5 64.25$ LF Guard Rail RI-6 34.50$ LF Curb & Gutter, rolled RI-7 19.50$ LF Curb & Gutter, vertical RI-8 14.25$ LF Curb and Gutter, demolition and disposal RI-9 20.50$ LF Curb, extruded asphalt RI-10 6.25$ LF Curb, extruded concrete RI-11 8.00$ LF Sawcut, asphalt, 3" depth RI-12 3.00$ LF Sawcut, concrete, per 1" depth RI-13 5.00$ LF Sealant, asphalt RI-14 2.25$ LF Shoulder, gravel, 4" thick RI-15 17.25$ SY Sidewalk, 4" thick RI-16 43.50$ SY Sidewalk, 4" thick, demolition and disposal RI-17 37.00$ SY Sidewalk, 5" thick RI-18 47.00$ SY Sidewalk, 5" thick, demolition and disposal RI-19 46.00$ SY Sign, Handicap RI-20 97.00$ Each Striping, per stall RI-21 8.00$ Each Striping, thermoplastic, ( for crosswalk )RI-22 3.50$ SF Striping, 4" reflectorized line RI-23 0.55$ LF Additional 2.5" Crushed Surfacing RI-24 4.15$ SY HMA 1/2" Overlay 1.5" RI-25 16.00$ SY HMA 1/2" Overlay 2"RI-26 20.75$ SY HMA Road, 2", 4" rock, First 2500 SY RI-27 32.25$ SY HMA Road, 2", 4" rock, Qty. over 2500SY RI-28 24.00$ SY HMA Road, 4", 6" rock, First 2500 SY RI-29 51.75$ SY HMA Road, 4", 6" rock, Qty. over 2500 SY RI-30 42.50$ SY HMA Road, 4", 4.5" ATB RI-31 43.50$ SY Gravel Road, 4" rock, First 2500 SY RI-32 17.25$ SY Gravel Road, 4" rock, Qty. over 2500 SY RI-33 11.50$ SY Thickened Edge RI-34 10.00$ LF SUBTOTAL THIS PAGE: (B)(C)(D)(E) Page 6 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) PARKING LOT SURFACING No. 2" AC, 2" top course rock & 4" borrow PL-1 24.00$ SY 2" AC, 1.5" top course & 2.5" base course PL-2 32.00$ SY 4" select borrow PL-3 5.75$ SY 1.5" top course rock & 2.5" base course PL-4 16.00$ SY SUBTOTAL PARKING LOT SURFACING: (B)(C)(D)(E) LANDSCAPING & VEGETATION No. Street Trees LA-1 Median Landscaping LA-2 Right-of-Way Landscaping LA-3 Wetland Landscaping LA-4 SUBTOTAL LANDSCAPING & VEGETATION: (B)(C)(D)(E) TRAFFIC & LIGHTING No. Signs TR-1 Street Light System ( # of Poles)TR-2 Traffic Signal TR-3 Traffic Signal Modification TR-4 SUBTOTAL TRAFFIC & LIGHTING: (B)(C)(D)(E) WRITE-IN-ITEMS SUBTOTAL WRITE-IN ITEMS: STREET AND SITE IMPROVEMENTS SUBTOTAL:563.75 SALES TAX @ 10.3%58.07 STREET AND SITE IMPROVEMENTS TOTAL:621.82 (B)(C)(D)(E) Page 7 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost DRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.) Access Road, R/D D-1 30.00$ SY * (CBs include frame and lid) Beehive D-2 103.00$ Each Through-curb Inlet Framework D-3 460.00$ Each CB Type I D-4 1,725.00$ Each 2 3,450.00 CB Type IL D-5 2,000.00$ Each CB Type II, 48" diameter D-6 3,500.00$ Each for additional depth over 4' D-7 550.00$ FT CB Type II, 54" diameter D-8 4,075.00$ Each for additional depth over 4'D-9 570.00$ FT CB Type II, 60" diameter D-10 4,225.00$ Each for additional depth over 4'D-11 690.00$ FT CB Type II, 72" diameter D-12 6,900.00$ Each for additional depth over 4'D-13 975.00$ FT CB Type II, 96" diameter D-14 16,000.00$ Each for additional depth over 4'D-15 1,050.00$ FT Trash Rack, 12"D-16 400.00$ Each Trash Rack, 15"D-17 470.00$ Each Trash Rack, 18"D-18 550.00$ Each Trash Rack, 21"D-19 630.00$ Each Cleanout, PVC, 4"D-20 170.00$ Each Cleanout, PVC, 6"D-21 195.00$ Each 3 585.00 Cleanout, PVC, 8"D-22 230.00$ Each Culvert, PVC, 4" D-23 11.50$ LF Culvert, PVC, 6" D-24 15.00$ LF Culvert, PVC, 8" D-25 17.00$ LF Culvert, PVC, 12" D-26 26.00$ LF Culvert, PVC, 15" D-27 40.00$ LF Culvert, PVC, 18" D-28 47.00$ LF Culvert, PVC, 24"D-29 65.00$ LF Culvert, PVC, 30" D-30 90.00$ LF Culvert, PVC, 36" D-31 150.00$ LF Culvert, CMP, 8"D-32 22.00$ LF Culvert, CMP, 12"D-33 33.00$ LF SUBTOTAL THIS PAGE:4,035.00 (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Quantity Remaining (Bond Reduction) (B)(C) Page 8 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Quantity Remaining (Bond Reduction) (B)(C) DRAINAGE (Continued) Culvert, CMP, 15"D-34 40.00$ LF Culvert, CMP, 18"D-35 47.00$ LF Culvert, CMP, 24"D-36 64.00$ LF Culvert, CMP, 30"D-37 90.00$ LF Culvert, CMP, 36"D-38 150.00$ LF Culvert, CMP, 48"D-39 218.00$ LF Culvert, CMP, 60"D-40 310.00$ LF Culvert, CMP, 72"D-41 400.00$ LF Culvert, Concrete, 8"D-42 48.00$ LF Culvert, Concrete, 12"D-43 55.00$ LF Culvert, Concrete, 15"D-44 89.00$ LF Culvert, Concrete, 18"D-45 100.00$ LF Culvert, Concrete, 24"D-46 120.00$ LF Culvert, Concrete, 30"D-47 145.00$ LF Culvert, Concrete, 36"D-48 175.00$ LF Culvert, Concrete, 42"D-49 200.00$ LF Culvert, Concrete, 48"D-50 235.00$ LF Culvert, CPE Triple Wall, 6" D-51 16.00$ LF Culvert, CPE Triple Wall, 8" D-52 18.00$ LF Culvert, CPE Triple Wall, 12" D-53 27.00$ LF Culvert, CPE Triple Wall, 15" D-54 40.00$ LF Culvert, CPE Triple Wall, 18" D-55 47.00$ LF Culvert, CPE Triple Wall, 24" D-56 64.00$ LF Culvert, CPE Triple Wall, 30" D-57 90.00$ LF Culvert, CPE Triple Wall, 36" D-58 149.00$ LF Culvert, LCPE, 6"D-59 69.00$ LF Culvert, LCPE, 8"D-60 83.00$ LF Culvert, LCPE, 12"D-61 96.00$ LF Culvert, LCPE, 15"D-62 110.00$ LF Culvert, LCPE, 18"D-63 124.00$ LF Culvert, LCPE, 24"D-64 138.00$ LF Culvert, LCPE, 30"D-65 151.00$ LF Culvert, LCPE, 36"D-66 165.00$ LF Culvert, LCPE, 48"D-67 179.00$ LF Culvert, LCPE, 54"D-68 193.00$ LF SUBTOTAL THIS PAGE: (B)(C)(D)(E) Page 9 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Quantity Remaining (Bond Reduction) (B)(C) DRAINAGE (Continued) Culvert, LCPE, 60"D-69 206.00$ LF Culvert, LCPE, 72"D-70 220.00$ LF Culvert, HDPE, 6"D-71 48.00$ LF Culvert, HDPE, 8"D-72 60.00$ LF Culvert, HDPE, 12"D-73 85.00$ LF Culvert, HDPE, 15"D-74 122.00$ LF Culvert, HDPE, 18"D-75 158.00$ LF Culvert, HDPE, 24"D-76 254.00$ LF Culvert, HDPE, 30"D-77 317.00$ LF Culvert, HDPE, 36"D-78 380.00$ LF Culvert, HDPE, 48"D-79 443.00$ LF Culvert, HDPE, 54"D-80 506.00$ LF Culvert, HDPE, 60"D-81 570.00$ LF Culvert, HDPE, 72"D-82 632.00$ LF Pipe, Polypropylene, 6"D-83 96.00$ LF 170 16,320.00 Pipe, Polypropylene, 8"D-84 100.00$ LF Pipe, Polypropylene, 12"D-85 100.00$ LF 20 2,000.00 Pipe, Polypropylene, 15"D-86 103.00$ LF Pipe, Polypropylene, 18"D-87 106.00$ LF Pipe, Polypropylene, 24"D-88 119.00$ LF Pipe, Polypropylene, 30"D-89 136.00$ LF Pipe, Polypropylene, 36"D-90 185.00$ LF Pipe, Polypropylene, 48"D-91 260.00$ LF Pipe, Polypropylene, 54"D-92 381.00$ LF Pipe, Polypropylene, 60"D-93 504.00$ LF Pipe, Polypropylene, 72"D-94 625.00$ LF Culvert, DI, 6"D-95 70.00$ LF Culvert, DI, 8"D-96 101.00$ LF Culvert, DI, 12"D-97 121.00$ LF Culvert, DI, 15"D-98 148.00$ LF Culvert, DI, 18"D-99 175.00$ LF Culvert, DI, 24"D-100 200.00$ LF Culvert, DI, 30"D-101 227.00$ LF Culvert, DI, 36"D-102 252.00$ LF Culvert, DI, 48"D-103 279.00$ LF Culvert, DI, 54"D-104 305.00$ LF Culvert, DI, 60"D-105 331.00$ LF Culvert, DI, 72"D-106 357.00$ LF SUBTOTAL THIS PAGE:18,320.00 (B)(C)(D)(E) Page 10 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Quantity Remaining (Bond Reduction) (B)(C) Specialty Drainage Items Ditching SD-1 10.90$ CY Flow Dispersal Trench (1,436 base+)SD-3 32.00$ LF French Drain (3' depth)SD-4 30.00$ LF Geotextile, laid in trench, polypropylene SD-5 3.40$ SY Mid-tank Access Riser, 48" dia, 6' deep SD-6 2,300.00$ Each Pond Overflow Spillway SD-7 18.25$ SY Restrictor/Oil Separator, 12"SD-8 1,320.00$ Each Restrictor/Oil Separator, 15"SD-9 1,550.00$ Each Restrictor/Oil Separator, 18"SD-10 1,950.00$ Each Riprap, placed SD-11 48.20$ CY Tank End Reducer (36" diameter)SD-12 1,375.00$ Each Infiltration pond testing SD-13 143.00$ HR Permeable Pavement SD-14 Permeable Concrete Sidewalk SD-15 Culvert, Box __ ft x __ ft SD-16 SUBTOTAL SPECIALTY DRAINAGE ITEMS: (B)(C)(D)(E) STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch) Detention Pond SF-1 Each Detention Tank SF-2 Each Detention Vault SF-3 Each Infiltration Pond SF-4 Each Infiltration Tank SF-5 Each Infiltration Vault SF-6 Each Infiltration Trenches SF-7 2,700.00$ Each 3 8,100.00 Basic Biofiltration Swale SF-8 Each Wet Biofiltration Swale SF-9 Each Wetpond SF-10 Each Wetvault SF-11 Each Sand Filter SF-12 Each Sand Filter Vault SF-13 Each Linear Sand Filter SF-14 Each Proprietary Facility SF-15 Each Bioretention Facility SF-16 Each SUBTOTAL STORMWATER FACILITIES:8,100.00 (B)(C)(D)(E) Page 11 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Quantity Remaining (Bond Reduction) (B)(C) WRITE-IN-ITEMS (INCLUDE ON-SITE BMPs) WI-1 WI-2 WI-3 WI-4 WI-5 WI-6 WI-7 WI-8 WI-9 WI-10 WI-11 WI-12 WI-13 WI-14 WI-15 SUBTOTAL WRITE-IN ITEMS: DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:30,455.00 SALES TAX @ 10.3%3,136.87 DRAINAGE AND STORMWATER FACILITIES TOTAL:33,591.87 (B) (C) (D) (E) Page 12 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Connection to Existing Watermain W-1 3,400.00$ Each 2 6,800.00 Ductile Iron Watermain, CL 52, 4 Inch Diameter W-2 58.00$ LF Ductile Iron Watermain, CL 52, 6 Inch Diameter W-3 65.00$ LF Ductile Iron Watermain, CL 52, 8 Inch Diameter W-4 75.00$ LF Ductile Iron Watermain, CL 52, 10 Inch Diameter W-5 80.00$ LF Ductile Iron Watermain, CL 52, 12 Inch Diameter W-6 145.00$ LF Gate Valve, 4 inch Diameter W-7 1,225.00$ Each Gate Valve, 6 inch Diameter W-8 1,350.00$ Each Gate Valve, 8 Inch Diameter W-9 1,550.00$ Each Gate Valve, 10 Inch Diameter W-10 2,100.00$ Each Gate Valve, 12 Inch Diameter W-11 2,500.00$ Each Fire Hydrant Assembly W-12 5,000.00$ Each Permanent Blow-Off Assembly W-13 1,950.00$ Each Air-Vac Assembly, 2-Inch Diameter W-14 3,050.00$ Each Air-Vac Assembly, 1-Inch Diameter W-15 1,725.00$ Each Compound Meter Assembly 3-inch Diameter W-16 9,200.00$ Each 2 18,400.00 Compound Meter Assembly 4-inch Diameter W-17 10,500.00$ Each Compound Meter Assembly 6-inch Diameter W-18 11,500.00$ Each Pressure Reducing Valve Station 8-inch to 10-inch W-19 23,000.00$ Each WATER SUBTOTAL:25,200.00 SALES TAX @ 10.3%2,595.60 WATER TOTAL:27,795.60 (B) (C) (D) (E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR WATER Quantity Remaining (Bond Reduction) (B)(C) Page 13 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.d WATER Version: 4/1/2024 Printed 8/12/2025 CED Permit #:PR21-000093 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Clean Outs SS-1 1,150.00$ Each Grease Interceptor, 500 gallon SS-2 9,200.00$ Each Grease Interceptor, 1000 gallon SS-3 11,500.00$ Each Grease Interceptor, 1500 gallon SS-4 17,200.00$ Each Side Sewer Pipe, PVC. 4 Inch Diameter SS-5 92.00$ LF Side Sewer Pipe, PVC. 6 Inch Diameter SS-6 110.00$ LF 90 9,900.00 Sewer Pipe, PVC, 8 inch Diameter SS-7 120.00$ LF Sewer Pipe, PVC, 12 Inch Diameter SS-8 144.00$ LF Sewer Pipe, DI, 8 inch Diameter SS-9 130.00$ LF Sewer Pipe, DI, 12 Inch Diameter SS-10 150.00$ LF Manhole, 48 Inch Diameter SS-11 6,900.00$ Each Manhole, 54 Inch Diameter SS-13 6,800.00$ Each Manhole, 60 Inch Diameter SS-15 7,600.00$ Each Manhole, 72 Inch Diameter SS-17 10,600.00$ Each Manhole, 96 Inch Diameter SS-19 16,000.00$ Each Pipe, C-900, 12 Inch Diameter SS-21 205.00$ LF Outside Drop SS-24 1,700.00$ LS Inside Drop SS-25 1,150.00$ LS Sewer Pipe, PVC, ____ Inch Diameter SS-26 Lift Station (Entire System)SS-27 LS SANITARY SEWER SUBTOTAL:9,900.00 SALES TAX @ 10.3%1,019.70 SANITARY SEWER TOTAL:10,919.70 (B) (C) (D) (E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR SANITARY SEWER Quantity Remaining (Bond Reduction) (B)(C) Page 14 of 15 Ref 8-H Bond Quantity Worksheet SECTION II.e SANITARY SEWER Version: 4/1/2024 Printed 8/12/2025 1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200 Date: Name:Project Name: PE Registration No:CED Plan # (LUA): Firm Name:CED Permit # (C): Firm Address:Site Address: Phone No.Parcel #(s): Email Address:Project Phase: Site Restoration/Erosion Sediment Control Subtotal (a) Existing Right-of-Way Improvements Subtotal (b)(b)39,337.12$ Future Public Improvements Subtotal (c)-$ Stormwater & Drainage Facilities (Public & Private) Subtotal (d)(d)33,591.87$ (e) (f) Site Restoration Existing Right-of-Way and Storm Drainage Improvements Maintenance Bond 14,585.80$ Bond Reduction 2 Construction Permit Bond Amount 3 Minimum Bond Amount is $10,000.00 1 Estimate Only - May involve multiple and variable components, which will be established on an individual basis by Development Engineering. 2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% will cover all remaining items to be constructed. 3 Required Bond Amounts are subject to review and modification by Development Engineering. * Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton. ** Note: All prices include labor, equipment, materials, overhead, profit, and taxes. (425) 392-0250 CostaP@encompasses.net Meadow Ave Short Plat LUA21-000084, SHPL-A 334270-0570 FOR APPROVAL PR21-000093 165 NE Juniper Street, Suite 201, Issaquah, WA 98027 93,667.45$ P (a) x 100% SITE IMPROVEMENT BOND QUANTITY WORKSHEET BOND CALCULATIONS Costa Philippides 38375 Encompass Engineering & Surveying R ((b x 150%) + (d x 100%)) S (e) x 150% + (f) x 100% Bond Reduction: Existing Right-of-Way Improvements (Quantity Remaining)2 Bond Reduction: Stormwater & Drainage Facilities (Quantity Remaining)2 T (P +R - S) Prepared by:Project Information CONSTRUCTION BOND AMOUNT */** (prior to permit issuance) EST1 ((b) + (c) + (d)) x 20% -$ MAINTENANCE BOND */** (after final acceptance of construction) 1,069.91$ 39,337.12$ 92,597.54$ 1,069.91$ -$ 33,591.87$ -$ Page 15 of 15 Ref 8-H Bond Quantity Worksheet SECTION III. BOND WORKSHEET Version: 4/1/2024 Printed 8/12/2025 12" 12" YARD DRAIN OR CATCH BASIN WITH SOLID LID 2' MIN. SECTION A PLAN ELEVATION HOUSE HOUSE 5' MIN.10' MIN.SEE NOTE 2 ROOF DOWNSPOUT WITH OVERFLOW WYE AND SPLASH BLOCK 6" DIA. MIN. PVC, SDR 35 PER ASTM D3034 6" MIN. FINE MESH SCREEN, SS304 10x10 OR SIMILAR 6" DIA. MIN. PERFORATED PVC, SDR 35 PER ASTM D3034 NON-WOVEN GEOTEXTILE FOR SEPARATION ON TOP AND SIDES OF TRENCH PER WSDOT SPECIFICATIONS SECTION 9-33.2(1) TABLE 3 COMPACTED BACKFILL 6" DIA. MIN. PERFORATED PVC, SDR 35 PER ASTM D3034 6" MIN. 6" MIN. 12" MIN. APERFORATED PIPE TO BE LEVEL 3/4" TO 1-1/2" WASHED DRAIN ROCK OR GRAVEL BACKFILL FOR DRYWELLS PER WSDOT STD SPECIFICATION SECTION 9-03.12(5) 12" MIN. ABOVE SEASONAL HIGH GROUNDWATER OR HYDRAULICALLY RESTRICTIVE LAYER FLEXIBLE GASKETED CAP PER ASTM D5926 NOTES: 1.15' MINIMUM SETBACK FROM INFILTRATION TRENCH TO BUILDINGS WITH CRAWL SPACES, BASEMENTS, OR ELEVATIONS BELOW THE OVERFLOW POINT. 2.REQUIRED TRENCH LENGTH VARIES DEPENDING ON SOIL TYPE, UP TO 100' MAX. WHEN LOCATED IN COARSE SANDS OR COBBLES, INFILTRATION TRENCHES MUST BE AT LEAST 20' IN LENGTH PER 1,000 SQUARE FEET OF IMPERVIOUS SURFACE SERVED. WHEN LOCATED IN MEDIUM SANDS, INFILTRATION TRENCHES MUST BE AT LEAST 30' IN LENGTH PER 1,000 SQUARE FEET OF IMPERVIOUS SURFACE SERVED. 3.SEE CONSTRUCTION PLANS FOR SPECIFIC PROJECT REQUIREMENTS. 6" MIN. CLEANOUT PER STD. PLAN 226.00 24" MIN. SINGLE FAMILY ROOF DOWNSPOUT INFILTRATION TRENCH STD. PLAN - 225.20 PUBLIC WORKS DEPARTMENT APPROVED: DATEMartinPastucha Public Works Administrator UNLESSOTHERWISE NOTED, DRAWINGISNOTTOSCALE (NTS) DocuSign Envelope ID: 3B1B34D3-7E0A-476C-ADB3-4329FFE0C108 8/13/2020 | 8:48 AM PDT Page 1 of ___ Return Address: City Clerk’s Office City of Renton 1055 S Grady Way Renton, WA 98057 DECLARATION OF COVENANT FOR INSPECTION AND MAINTENANCE OF DRAINAGE FACILITIES AND ON-SITE BMPS Grantor: Grantee: City of Renton, a Washington municipal corporation Legal Description: Assessor's Tax Parcel ID#: IN CONSIDERATION of the approved City of Renton (check one of the following) Residential Building Permit Commercial Building Permit Clearing and Grading Permit Civil Construction or Utility Permit for Permit(s)_____________________ (Construction/Building/Utility Permit #) relating to the real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby covenants (covenant) with the City of Renton (“City of Renton” or “City”), a municipal corporation of the state of Washington, that he/she (they) will observe, consent to, and abide by the conditions and obligations set forth and described in Paragraphs 1 through 9 below with regard to the Property, and hereby grants (grant) an easement as described in Paragraphs 2 and 3. Grantor(s) hereby grants (grant), covenants (covenant), and agrees (agree) as follows: 1.The Grantor(s) or his/her (their) successors in interest and assigns ("Owners ") shall at their own cost, operate, maintain, and keep in good repair, the Property's drainage facilities constructed as required in the approved construction plans and specifications __________________ (Project Plan #) on file with the City of Renton and submitted to the City of Renton for the review and approval of permit(s) _____________________________ (Construction/Building/Utility Permit #). The Property's drainage facilities are shown and/or listed on Exhibit A – Site Plan. The Property’s drainage facilities shall be maintained in compliance with the operation and maintenance schedule included and attached herein as Exhibit B – Operations and Maintenance. Drainage facilities include pipes, channels, flow control facilities, water quality facilities, on-site best management practices (BMPs) and other engineered structures designed to manage and/or Page 2 of ___ treat stormwater on the Property. On-site BMPs include dispersion and infiltration devices, bioretention, permeable pavements, rainwater harvesting systems, tree retention credit, reduced impervious surface footprint, vegetated roofs and other measures designed to mimic pre-developed hydrology and minimize stormwater runoff on the Property. 2.City of Renton shall have the right to ingress and egress over those portions of the Property necessary to perform inspections of the stormwater facilities and BMPs and conduct maintenance activities specified in this Declaration of Covenant and in accordance with the Renton Municipal Code. City of Renton shall provide at least thirty (30) days’ written notice to the Owners that entry on the Property is planned for the inspection of drainage facilities. After the thirty (30) days, the Owners shall allow the City of Renton to enter for the sole purpose of inspecting drainage facilities. In lieu of inspection by the City, the Owners may elect to engage a licensed civil engineer registered in the state of Washington who has expertise in drainage to inspect the drainage facilities and provide a written report describing their condition. If the engineer option is chosen, the Owners shall provide written notice to the City of Renton within fifteen (15) days of receiving the City’s notice of inspection. Within thirty (30) days of giving this notice, the Owners, or engineer on behalf of the Owners, shall provide the engineer’s report to the City of Renton. If the report is not provided in a timely manner as specified above, the City of Renton may inspect the drainage facilities without further notice. 3.If City of Renton determines from its inspection, or from an engineer’s report provided in accordance with Paragraph 2, that maintenance, repair, restoration, and/or mitigation work is required to be done to any of the drainage facilities, City of Renton shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work (“Work”) required pursuant to the Renton Municipal Code. The City shall also set a reasonable deadline for the Owners to complete the Work, or to provide an engineer’s report that verifies completion of the Work. After the deadline has passed, the Owners shall allow the City access to re-inspect the drainage facilities unless an engineer’s report has been provided verifying completion of the Work. If the Work is not completed within the time frame set by the City, the City may initiate an enforcement action and/or perform the Work and hereby is given access to the Property for such purposes. Written notice will be sent to the Owners stating the City’s intention to perform such Work. This Work will not commence until at least seven (7) days after such notice is mailed. If, within the sole discretion of the City, there exists an imminent or present danger, the seven (7) day notice period will be waived and Work will begin immediately. 4.The Owners shall assume all responsibility for the cost of any Work, or any measures taken by the City to address conditions as described in Paragraph 3. Such responsibility shall include reimbursement to the City within thirty (30) days of the receipt of the invoice for any such Work performed. Overdue payments will require payment of interest at the maximum legal rate allowed by RCW 19.52.020 (currently twelve percent (12%)). If the City initiates legal action to enforce this agreement, the prevailing party in such action is entitled to recover reasonable litigation costs and attorney’s fees. 5.The Owners are required to obtain written approval from City of Renton prior to filling, piping, cutting, or removing vegetation (except in routine landscape maintenance) in open vegetated stormwater facilities (such as swales, channels, ditches, ponds, etc.), or performing any alterations or modifications to the drainage facilities referenced in this Declaration of Covenant. Page 3 of ___ 6.Any notice or consent required to be given or otherwise provided for by the provisions of this Agreement shall be effective upon personal delivery, or three (3) days after mailing by Certified Mail, return receipt requested. 7.With regard to the matters addressed herein, this agreement constitutes the entire agreement between the parties, and supersedes all prior discussions, negotiations, and all agreements whatsoever whether oral or written. 8.This Declaration of Covenant is intended to protect the value and desirability and promote efficient and effective management of surface water drainage of the real property described above, and shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This Declaration of Covenant shall run with the land and be binding upon Grantor(s), and Grantor's(s') successors in interest, and assigns. 9.This Declaration of Covenant may be terminated by execution of a written agreement by the Owners and the City that is recorded by King County in its real property records. IN WITNESS WHEREOF, this Declaration of Covenant for the Inspection and Maintenance of Drainage Facilities is executed this _____ day of ____________________, 20_____. GRANTOR, owner of the Property GRANTOR, owner of the Property STATE OF WASHINGTON ) COUNTY OF KING )ss. On this day personally appeared before me: , to me known to be the individual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this _____ day of ___________________, 20_____. Printed name Notary Public in and for the State of Washington, residing at My appointment expires N 38TH STREET(RESIDENTIAL COLLECTOR)MEADOW AVENUE N(RESIDENTIAL COLLECTOR) I-405Eastern Washington Division407 Swiftwater Blvd. ▪ Cle Elum, WA 98922 ▪ Phone: (509) 674-7433Western Washington Division165 NE Juniper Street, Suite 201 ▪ Issaquah, WA 98027 ▪ Phone: (425) 392-0250ncompassENGINEERING & SURVEYINGEKnow what'sCallbelow.before you dig.RLEGAL DESCRIPTION:BENCH MARK :BASIS OF BEARINGS :HORIZONTAL DATUM :PROJECT TEAM:SITE DATA:VICINITY MAPNORTHCONTRACTOR RESPONSIBILITY:DISCREPANCIES:EXISTING UTILITY NOTE:UTILITY DISTRICT INFORMATION:PERVIOUS SURFACE SUMMARY:ON-OFF SITE IMPERIOUS /SHEET INDEXNO.NAME1COVER SHEET2TOPOGRAPHIC SURVEY3TESC PLAN4TESC DETAILS5PRELIMINARY UTILITY PLAN6ROAD & GRADING PLAN7STREET DETAILS8STORM DETAILS I9STORM DETAILS II10SEWER DETAILS11WATER DETAILS 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 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 F Operation And Maintenance Manual MAINTENANCE INSTRUCTIONS FOR FULL INFILTRATION Your property contains an on-site BMP (best management practice) called “full infiltration,” which was installed to mitigate the stormwater quantity and quality impacts of some or all of the impervious surfaces on your property. Full infiltration is a method of soaking runoff from impervious area (such as paved areas and roofs) into the ground. If properly installed and maintained per Appendix A of the City of Renton’s Surface Water Design Manual, full infiltration can manage runoff so that a majority of precipitation events are absorbed. Infiltration devices, such as gravel filled trenches, drywells, and ground surface depressions, facilitate this process by putting runoff in direct contact with the soil and holding the runoff long enough to soak most of it into the ground. To be successful, the soil condition around the infiltration device must be reliably able to soak water into the ground for a reasonable number of years. Infiltration Devices The infiltration devices used on your property include the following as indicated on the site plan (CHECK THE BOX(ES) THAT APPLY): gravel filled trenches, drywells, ground surface depressions. MAINTENANCE RESTRICTIONS The size, placement, and composition of these devices as depicted by the site plan and design details must be maintained and may not be changed without written approval from the City of Renton or through a future development permit from the City of Renton. INSPECTION FREQUENCY AND MAINTENANCE GUIDELINES • Infiltration devices must be inspected annually and after major storm events to identify and repair any physical defects. • Maintenance and operation of the system should focus on ensuring the system’s viability by preventing sediment-laden flows from entering the device. Excessive sedimentation will result in a plugged or non-functioning facility. • If the infiltration device has a catch basin, sediment accumulation must be removed on a yearly basis or more frequently if necessary. • Prolonged ponding around or atop a device may indicate a plugged facility. If the device becomes plugged, it must be replaced. • Keeping the areas that drain to infiltration devices well swept and clean will enhance the longevity of these devices. • For roofs, frequent cleaning of gutters will reduce sediment loads to these devices. RECORDING REQUIREMENT These full infiltration on-site BMP maintenance and operation instructions must be recorded as an attachment to the required declaration of covenant and grant of easement per Requirement 3 of Section C.1.3.4 of the City of Renton Surface Water Design Manual. The intent of these instructions is to explain to future property owners, the purpose of the BMP and how it must be maintained and operated. These instructions are intended to be a minimum; the City of Renton may require additional instructions based on site-specific conditions. See the City of Renton’s Surface Water Design Manual website for additional information and updates. TYPICAL FULL INFILTRATION APPLICATIONS 6"24"12"24"WASHED ROCK 1 12"- 34"LEVELINFILTRATION TRENCHSECTION ANTSPLAN VIEWNTSSECTION VIEWNTSVARIESAA6"6"4" RIGID OR 6"FLEXIBLEPERFORATEDPIPECB SUMP w/SOLID LIDROOF DRAIN4" RIGID OR 6" FLEXIBLEPERFORATED PIPEOVERFLOWSPLASH BLOCKROOF DRAINCB SUMP w/SOLID LID12"FINE MESHSCREENSETBACKFROMBUILDING5' MIN.1' MIN.1' MIN.FILTER FABRICCOMPACTED BACKFILL4" RIGID OR 6" FLEXIBLEPERFORATED PIPE112" - 34" WASHED ROCKMIN. 1' ABOVE SEASONALHIGH GROUNDWATERTABLE, SEE SECTION C.2.2.2TRENCH SETBACK FROMBUILDING AS REQUIRED,15' MIN. TYPICAL FULL INFILTRATION APPLICATIONS DRIVEWAYX-SECTIONNTSX-SECTIONNTS2' MIN.FILTER STRIPSEE SECTIONS6.3.4 & 6.3.518" MIN.6" MIN.3/4" TO 1-1/2"WASHED DRAINROCKGRASSOVERFLOWNOTE:SEE C.2.2.3 FORTRENCH LENGTHS,TRENCH SPACING ANDSITE LIMITATIONSGRASS2' MIN.18" MIN.6" MIN.3/4" TO 1-1/2"WASHED DRAINROCKOVERFLOW15' MIN. ASREQUIRED,SEE C.2.2.3FROM ROOFNOTE:SEE C.2.2.3 FORTRENCH LENGTHS,TRENCH SPACING ANDSITE LIMITATIONSMIN. 1' ABOVESEASONAL HIGHGROUNDWATERTABLE, SEESECTION C.2.2.2MIN. 1' ABOVESEASONAL HIGHGROUNDWATERTABLE, SEESECTION C.2.2.2 TYPICAL FULL INFILTRATION APPLICATIONS FLOWHOUSEFLOW48 INCH DIAMETERHOLE FILLED WITH1 12" - 3" WASHEDDRAIN ROCKPLAN VIEWNTSSECTIONNTSMARK CENTER OF HOLEWITH 1" CAPPED PVCOR OTHER MEANSFLUSH WITH SURFACEROOF DOWNSPOUTOVERFLOWSPLASH BLOCKTOPSOILFINE MESH SCREENMIN. 4" DIA.PVC PIPESIDES OF HOLELINED WITHFILTER FABRICCATCH BASIN(YARD DRAIN)15' MIN. AS REQUIRED, SEE SECTION C.2.2.3VARIES1' MIN.MIN. 1' ABOVE SEASONALHIGH GROUNDWATER TABLE,SEE SECTION C.2.2.2HOUSEROOFDOWNSPOUTROOFDOWNSPOUTCATCH BASIN(YARD DRAIN)48 INCH DIAMETERHOLE FILLED WITH1 12" - 3" WASHEDDRAIN ROCK5' MIN. SETBACKFROM BUILDING