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RS_DrainageReportTIR_DEA_170825_v1
KING COUNTY REGIONAL AFIS LAB REPLACEMENT 900 Oaksdale Ave SW Renton, WA 98057 STORMWATER TIR Prepared for: King County 500 5th Ave Seattle, WA 98104 (206) 357-5600 Prepared by: David Evans and Associates, Inc. 14432 SE Eastgate Way, Suite 400 Bellevue, WA 98007 (425) 519-6500 BUFF 0000-0011 Prepared: August 2017 KING COUNTY REGIONAL AFIS LAB REPLACEMENT 900 Oaksdale Ave SW Renton, WA 98057 STORMWATER TIR Prepared for: King County 500 5th Ave Seattle, WA 98104 (206) 357-5600 Prepared by: David Evans and Associates, Inc. 14432 SE Eastgate Way, Suite 400 Bellevue, WA 98007 (425) 519-6500 BUFF 0000-0011 Prepared: August 2017 KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE i TABLE OF CONTENTS 1 PROJECT OVERVIEW ................................................................................................. 1 1.1 Drainage Basins, Sub-basins and Site Characteristics ...................................... 1 1.1.1 Drainage Basins .................................................................................... 1 1.1.2 Site Characteristics ................................................................................ 1 1.2 Soils ................................................................................................................... 1 2 CONDITIONS AND REQUIREMENTS SUMMARY ......................................................... 2 2.1 Drainage Review Requirements ........................................................................ 2 2.2 Core Requirements ............................................................................................ 5 2.2.1 Core Requirement #1: ........................................................................... 5 2.2.2 Core Requirement #2: ........................................................................... 5 2.2.3 Core Requirement #3: ........................................................................... 5 2.2.4 Core Requirement #4: ........................................................................... 5 2.2.5 Core Requirement #5: ........................................................................... 5 2.2.6 Core Requirement #6: ........................................................................... 5 2.2.7 Core Requirement #7: ........................................................................... 6 2.2.8 Core Requirement #8: ........................................................................... 6 2.2.9 Core Requirement #9: ........................................................................... 6 2.3 Special Requirements ........................................................................................ 6 2.3.1 Special Requirement #1: ....................................................................... 6 2.3.2 Special Requirement #2: ....................................................................... 6 2.3.3 Special Requirement #3: ....................................................................... 6 2.3.4 Special Requirement #4: ....................................................................... 6 2.3.5 SPECIAL REQUIREMENT #5: ........................................................... 6 2.3.6 SPECIAL REQUIREMENT #6: ........................................................... 7 3 OFFSITE ANALYSIS .................................................................................................... 8 3.1 Task 1: Study Area Definition .......................................................................... 8 3.2 Task 3: Field Inspection .................................................................................... 8 3.3 Task 4: Drainage System Description and Problems Description .................... 8 4 FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID) AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ............................................................................. 9 4.1 Flow Control ..................................................................................................... 9 4.1.1 Part A: Existing Site Hydrology ........................................................... 9 4.1.2 Part B: Developed Site Hydrology ........................................................ 9 4.1.3 Part C: Performance Standards ............................................................. 9 4.1.4 Part D: Flow Control System .............................................................. 10 4.2 LOW IMPACT DEVELOPMENT: ................................................................ 10 4.3 WATER QUALITY: ....................................................................................... 11 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN ...................................................... 12 6 SPECIAL REPORTS AND STUDIES ............................................................................. 13 KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE ii 7 OTHER PERMITS ...................................................................................................... 14 8 CONSTRUCTION STORMWATER POLLUTION PREVENTION ANALYSIS AND DESIGN15 8.1 Part A: ESC Measures: ................................................................................... 15 8.2 Part B: SWPPS Measures: .............................................................................. 17 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT .. 18 9.1 City of Renton Bond Quantity Worksheet ...................................................... 18 9.2 Flow Control and Water Quality Facility Summary Sheet and Sketch .......... 18 10 OPERATIONS AND MAINTENANCE MANUAL ........................................................... 19 List of Figures Figure 1: TIR Worksheet Figure 2: Site Location Map Figure 3: Drainage Basin Map Figure 4: Existing Discharge Point Figure 5: NRCS Web Soil Survey Figure 6: Flow Control Application Map KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 1 1 PROJECT OVERVIEW King County is proposing to construct new facilities for the relocation of the County’s Automated Fingerprint Identification System (AFIS) processing laboratory at 900 Oaksdale Avenue SW. The project is located on the east side of the Oaksdale Ave SW, south of SW 7th Street, and will occupy 15,000 square feet of the renovated area inside the King County Black River Building. The project includes a 3,000 square foot addition to the east side of the existing building, which will eliminate approximately 25 of the approximately 317 parking spaces on site. The project also includes grading of the associated parking lot in order to accommodate the addition. There is no proposed change to the site access from the public street. See Figure 1 for the TIR Worksheet and Figure 2 for the Site Location Map. 1.1 Drainage Basins, Sub-basins and Site Characteristics 1.1.1 Drainage Basins The project site is located in the Black River Basin. See Figure 3, Drainage Basin Map. 1.1.2 Site Characteristics Figure 4, Existing Discharge Point, illustrates the location of the discharge point from the site to the city storm system. The proposed storm system consists of a system of catch basins (CB) in the parking lot that discharge to an existing CB to the north of the existing building. Figure 4 illustrates the length of travel from the proposed storm system in the redevelopment area to the existing CB. 1.2 Soils Soil information at the project is Woodinville Silt loam (Wo). The soil is classified as a Hydrologic Group C/D soil. See Figure 5 NRCS Web soil survey. According to the generalized soil profile from the Geotech (see geotechnical report from S&EE dated: 03-07-2017), the site consists of the following: Fill soil for a depth of 5 feet approximately Silt and Clay soil for a depth of 20 feet approximately Sand, Silty Sand and Gravel for a depth of 45 feet approximately The water table is at depth of 5.2 feet from ground approximately. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 2 2 CONDITIONS AND REQUIREMENTS SUMMARY The stormwater design in this project is designed according to the 2017 City of Renton Surface Water Design Manual. 2.1 Drainage Review Requirements The proposed redevelopment of the project site will result in greater than 2,000 square feet of new plus replaced impervious surface area. Full Drainage Review is required for this project in accordance with Figure 1.1.2.A of 2017 City of Renton Surface Water Design Manual, shown on the following pages. Also per Table 1.1.2.A of 2017 City of Renton Surface Water Design Manual, all nine core requirements (see Section 2.2) and six special requirements (see Section 2.3) are applicable to the Full Drainage Review and will be addressed in this TIR. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 3 KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 4 KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 5 2.2 Core Requirements 2.2.1 Core Requirement #1: Discharge at Natural Location: The proposed design will not cause significant adverse impacts to downstream waters. The proposed conveyance system will connect to the existing drai nage system, which discharges to the Black River. 2.2.2 Core Requirement #2: Offsite Analysis: An Offsite Analysis was performed and is described in Section 3.0. 2.2.3 Core Requirement #3: Flow Control: Flow control is required for this project. The project is located in the Peak Rate Flow Control Standard area (See Figure 6, Flow Control Application Map from City of Renton Manual). The project adds more than 5000 SF of new plus replaced impervious surface, which does not meet the basic exemption. However, a flow control facility will not be required for this project. See Section 4.1 for the Flow Control Analysis. 2.2.4 Core Requirement #4: Conveyance System: The proposed conveyance system has been designed as per the 2017 COR Surface Water Design Manual. See Section 5.0 for more detail. 2.2.5 Core Requirement #5: Erosion and Sedimentation Control (EC): A Construction Stormwater Pollution Prevention (CSWPP) Plan will be provided as part of the design drawings for the site improvements. This plan will provide erosion and sediment control information, locations where Best Management Practices (BMPs) shall be implemented, and requirements that the contractor must follow throughout construction. BMPs that will be implemented during construction are dust control, temporary and permanent seeding, storm drain inlet protection, and all clearing limits. The CSWPP Plan, which includes Temporary Erosion and Sediment Control (TES C) measures and Stormwater Pollution Prevention and Spill Control (SWPPS) measures, will become part of the contract documents for construction of the project. Additional erosion control may be applied as needed if directed by the design engineer or by the City of Renton. At the completion of the project, exposed soils will be seeded or mulched. See Section 8.0 for a detailed description of the CSWPP Analysis and Design. 2.2.6 Core Requirement #6: Maintenance and Operations: The property owner will perform all necessary maintenance of the on-site conveyance systems. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 6 2.2.7 Core Requirement #7: Financial Guarantees and Liability: The City of Renton will receive Financial Guarantees and Liability per permit requirements. 2.2.8 Core Requirement #8: Water Quality: Water Quality treatment will be provided in accordance to the requirements of the 2017 City of Renton Surface Water Design Manual. See Section 4.4 for the analysis and design of the proposed Water Quality Facilities. 2.2.9 Core Requirement #9: Flow Control BMPs: Flow Control BMPs were evaluated for feasibility in accordance with the 2017 Renton Manual. See Section 4.3 for more details. 2.3 Special Requirements 2.3.1 Special Requirement #1: Other Adopted Area-Specific Requirements Not applicable. 2.3.2 Special Requirement #2: Flood Hazard Area Delineation This project is not within flood hazard areas. 2.3.3 Special Requirement #3: Flood Protection Facilities No flood protection facilities are required. 2.3.4 Special Requirement #4: Source Control During the construction phase of the project, source controls measures will be implemented in accordance with the SWPP Plan. BMPs that will be employed are temporary and permanent seeding, catch basin inserts, clearing limits and mulch. 2.3.5 SPECIAL REQUIREMENT #5: Oil Control Not applicable. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 7 2.3.6 SPECIAL REQUIREMENT #6: Aquifer Protection Area Not applicable. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 8 3 OFFSITE ANALYSIS Per Core Requirement #2, all proposed redevelopments must conduct an offsite analysis to assess the potential offsite drainage and water quality impacts associated with development of the project site. The intent of this section is to identify the conditions and existing problems of the downstream system leaving the site and to demonstrate that the proposed project will not create any new drainage problems. 3.1 Task 1: Study Area Definition The existing commercial building on the project site and the parking areas to the south and east will remain. The proposed project will include a 3000 square foot addition to the east side of the existing building, which will eliminate 25 of the approximately 317 existing parking spaces on site. The total amount of impervious area will not change. The Basin Area Summary (see Table 1 in Section 4.1) shows that the existing impervious surfaces and the proposed impervious surfaces have similar runoff-generating characteristics. The proposed redevelopment does not change the rate, volume, duration, or location of discharges to and from the project site. Per Core Requirement #8, the project triggers the water quality requirement (See Section 4.3). Per Core Requirement #2, projects that trigger Core Requirement #8 must perform offsite analysis sufficient to identify and address “Downstream Water Quality Problems Requiring Special Attention”. 3.2 Task 3: Field Inspection The stormwater from the redeveloped area within the clearing limits discharges into the City storm system at the northwest corner of the site, which discharges into the Black River. See Figure 4 Existing Discharge Point. This downstream analysis was completed based on a site visit conducted on July 20th, 2017, at approximately 10:30 am. The conditions during the site visit were cloudy and 71° F. This analysis follows the proposed storm system in the redeveloped area up to ¼ mile downstream of the existing catch basin (CB A) into which the proposed redevelopment area discharges, with no drainage problems observed. See Appendix A for the downstream analysis map, photos of the downstream system and Field Notes. For the quarter mile downstream of CB A into which the proposed storm system discharges, the stormwater is collected via CB A and conveyed in storm drains and manholes to the Black River to the north of the project site. No onsite flooding or ponding was observed in the downstream analysis. 3.3 Task 4: Drainage System Description and Problems Description No downstream problems were observed that this project will aggravate or create. See Figure 8 King County Downstream Drainage Complaint Map. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 9 4 FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID) AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.1 Flow Control Per Core Requirement #3, flow control is required for this project. The project is located in the Peak Rate Flow Control Standard area (See Appendix A for the Flow Control Application Map from City of Renton Manual). New impervious, new pervious surface area and existing impervious surface areas were calculated to check if the project site meets the flow control facility requirement exemptions according to the City of Renton Manual. The peak flow rates for the existing and proposed site conditions were calculated using Western Washington Hydrology Model (WWHM) (See Appendix B for Hydrologic Analysis). Table 2 on the following page provides the calculation results 4.1.1 Part A: Existing Site Hydrology Presently, the project site is developed with a commercial building, parking lots around the building, landscaping and concrete paths. The existing stormwater runoff from the site is collected in a system of catch basins throughout the parking lot. The discharge from the catch basins is conveyed through a system of storm drains to the city storm system at the northwest corner of the site. See Exhibit B-1 in Appendix B for the existing site areas within the limits of disturbance; referred to as the redevelopment area. 4.1.2 Part B: Developed Site Hydrology The redevelopment consists of adding a 3000 square foot addition to the east side of the existing building and associated grading of the existing parking lot surrounding the addition. See Exhibit B-2 in Appendix B for the proposed site areas within the redevelopment area. Table 1 provides a summary of the site areas within the limits of disturbance. Table 1. BASIN AREA SUMMARY: BASIN ID PERVIOUS AREA (acres) IMPERVIOUS AREA (acres) TOTAL AREA (acres) % IMPERVIOUS Existing Basin 0.1 0.28 0.38 74% Proposed Basin 0.1 0.28 0.38 74% 4.1.3 Part C: Performance Standards4 The proposed redevelopment does not change the amount of impervious surface area within the limits of disturbance and, as shown in WWHM model summary, the peak discharge rates do not change. See Table 2 on the next page for the WWHM model summary. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 10 Table 2. WWHM MODEL SUMMARY BASIN ID 2-YEAR STORM (CFS) 10-YEAR STORM (CFS) 25-YEAR STORM (CFS) 100-YEAR STORM (CFS) Existing Basin 0.1 0.17 0.2 0.24 Proposed Basin 0.1 0.17 0.2 0.24 4.1.4 Part D: Flow Control System Per 2017 City of Renton Surface Water Design Manual Core Requirement #3, all proposed projects are must provide on-site flow control facilities or flow control BMPs or both to mitigate the impacts of storm and surface water run-off generated by new impervious surface, new pervious surface and replaced impervious surface targeted for flow mitigation. Exemptions from Core Requirement # 3: Per 2017 City of Renton Surface Water Design Manual, Peak Rate Flow Control Standard Area exceptions, the flow control facility requirement will be waived for any threshold discharge area in which the target surfaces subject to this requirement will generate no more than a 0.15- cubic feet per second (cfs) increase (when modeled using 15 minute time steps) in the existing site conditions 100-year peak flow (modeled using same time step unit (e.g., 15-minute) used to calculate the developed flow. This project meets the exemption. Flow Control Facility is not Required. 4.2 LOW IMPACT DEVELOPMENT: 1. Full Dispersion: The site was evaluated for full dispersion. Full Dispersion is not feasible because dispersion requires substantial amounts of undisturbed native vegetation on-site. This site is in an urban location and site conditions do not make dispersion feasible as there is not adequate space for the required 100 feet vegetated flow path. 2. Full Infiltration: Infiltration investigation is not required where the existing soils is comprised of fill materials or silt/clay soils. Since the majority of the site consists of an existing building and an associated parking lot, and fill soil for an approximate depth of 5 feet, Full Infiltration Systems will not be feasible for the site. (See Geotechnical Report and Infiltration Addendum from S&EE in Appendix E) 3. Bioretention: The existing site is developed as a parking lot and there is not sufficient space within the redevelopment area for bioretention facilities. 4. Limited Infiltration: Infeasible for the same reasons listed under Full Infiltration. 5. Permeable Pavement: The existing site conditions include an existing building surrounded by parking lots (paved/PGIS). Permeable Pavement is not feasible where replacing existing pollution generating impervious surfaces. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 11 4.3 WATER QUALITY: Water Quality is required for this project. The project adds more than 5000 square feet (SF) of new plus replaced impervious surface, which does not meet the basic exemption per Core Requirement #8. The project site land use is commercial, which requires Enhanced Basic Water Quality treatment per Core Requirement #8. Option 5- Proprietary Facility was chosen from the Enhanced Basic Water treatment facility options per Chapter 6 of the 2017 City of Renton Surface Water Design manual. This project will employ a Filterra system. Filterra units are approved by the State of Washington Department of Ecology (WSDOE) for enhanced treatment. Filterra units have been designated by WSDOE as facilities that meet the requirements of enhanced stormwater treatment and oil control. There will be one Filterra unit of size 6’x4’ placed in the landscape island to the north of the redevelopment area, which can treat 0.219 acres o impervious. See Table 3 for the new and replaced PGIS area summary. See Table 4 for the summary of the PGIS areas treated by the Filterra unit. See Appendix D for Exhibit D-1: New and Replaced PGIS Area and Exhibit D-2: PGIS Area treated by Filterra. Table 3. NEW AND REPLACED PGIS AREA SUMMARY New PGIS Area (acres) Replaced PGIS Area (acres) TOTAL PGIS Area (acres) 0.02 0.17 0.19 Table 4. SUMMARY OF THE PGIS AREA TREATED BY THE FILTERRA New/Replace PGIS Area (acres) Equivalent Existing PGIS Area (acres) TOTAL Treated PGIS Area (acres) 0.11 0.12 0.23 The total PGIS area treated by the Filterra unit is greater than the new plus replaced PGIS area added to the project site due to the proposed redevelopments. Therefore, a single Filterra unit of size 6’x4’ is sufficient to provide Enhanced Basic Water Quality treatment for the redeveloped area of the project site. This project proposes to upsize the Filterra unit to a 6’x6’ to allow for a shallower unit. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 12 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN Runoff from the redevelopment area is collected by a system of catch basins and storm drains in the parking lot, which discharges to the existing catch basin located to the north of the existing building. Conveyance was calculated using rational method for the area draining to Filterra A. See Appendix C for Rational Method Calculations. Using the Rational Method, the 100-year flow rate at Filerra A was calculated to be 1.03 cfs. The storm pipe leaving Filterra A is a 10” PVC pipe sloped at 0.5%. Bentley Flow Master was used to calculate the full flow capacity for this existing storm pipe, based on a Manning’s N-value of 0.014 for ductile iron. The full flow capacity is 1.42 cfs. See Appendix C for Full Flow Capacity Results using Bentley Flow Master. The 100-year flow rate for the area draining to Filterra A is less than the full flow capacity of the 10” pipe. Therefore, the proposed storm drain has the capacity to convey discharge from Filterra A to the existing system. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 13 6 SPECIAL REPORTS AND STUDIES See Appendix E for the Geotechnical Engineering Report from S&EE dated: 03-07-2017. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 14 7 OTHER PERMITS Not Applicable KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 15 8 CONSTRUCTION STORMWATER POLLUTION PREVENTION ANALYSIS AND DESIGN CSWPP measures include ESC measures and SWPPS measures. 8.1 Part A: ESC Measures: 1. Clearing Limits Prior to any site clearing or grading, areas to remain undisturbed during project construction shall be delineated. The clearing and grading limits are indicated in the TESC Plan. 2. Cover Measures Temporary Cover using Mulch (according to Appendix D, D.2.1.2.2 of 2017 City of Renton Surface Water Design Manual) will be installed if an area is to remain unworked for more than seven days during the dry season (May 1 to September 30) or for more than two consecutive working days during the wet season (October 1 to April 30). If the exposed area is to remain unworked for more than 30 days, Temporary and Permanent Seeding (according to Appendix D, D.2.1.2.6 of 2017 City of Renton Surface Water Design Manual) will be used. 3. Perimeter Protection Silt Fence (according to Appendix D, D.2.1.3.1 of 2017 City of Renton Surface Water Design Manual) will be used to filter sediment from sheetwash and will be located downslope of all the disturbed areas. It will be installed prior to any upslope grading or clearing. The location of the Silt Fence is indicated in the TESC Plan. 4. Traffic Area Stabilization The proposed redevelopment will use the existing paved area as a paved construction access. No additional BMPs are needed. 5. Sediment Retention As the contributing drainage area is less than an acre, Catch Basin Inserts (according to Appendix D, D.2.1.5.3 of 2017 City of Renton Surface Water Design Manual) will be installed within 500 feet of construction area in order to prevent the sediments form entering the storm drainage systems. They will be installed prior to any clearing and grading. 6. Surface Water Collection As the contributing drainage area is small enough to be treated with Perimeter protection and Sediment retention, Silt Fence and Catch Basin Inserts will be installed prior to any clearing and grading, as shown on the TESC Plan. 7. Dewatering Control Dewatering of trench and foundation will be done via vactor trucks as needed. 8. Dust Control Dust Control will not be required as the redevelopment involves replacing the existing paved area with the proposed building. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 16 9. Flow Control Surface water from disturbed areas will be routed through the existing flow control facility. 10. Control Pollutants Similar to SWPPS Measures. 11. Protect Existing and Proposed Stormwater Facilities and On-site BMPs Protection measures will be installed and maintained so as to prevent adverse impacts to existing stormwater facilities and on-site BMPs and areas of proposed stormwater facilities and on-site BMPs for the project. Adverse impacts can prompt the requirement to restore or replace affected stormwater facilities and on-site BMPs. a. Protect all stormwater facilities and on-site BMPs and proposed stormwater facility and on-site BMP footprints from sedimentation through installation and maintenance of erosion and sediment control BMPs on portions of the site that drain into the BMPs/facilities. b. Stormwater facilities and on-site BMPs will be restored to their fully functioning condition if they accumulate sediment during construction. Restoring the stormwater facilities and on-site BMPs will include, at a minimum, removal of sediment and any sediment-laden bioretention soils, and replacing the removed soils with soils meeting the design specification. Replacement with a new fully functioning stormwater facility and/or on-site BMP may be required if restoration to the fully functioning condition cannot be accomplished. c. Prevent compacting Bioretention BMPs/facilities by excluding construction equipment and foot traffic. Protect completed lawn and landscaped areas from compaction due to construction equipment. d. Control erosion and avoid introducing sediment from surrounding land uses onto permeable pavement BMPs. Do not allow muddy construction equipment on the base material or pavement. Do not allow sediment-laden runoff onto permeable pavements. e. Permeable pavement BMPs fouled with sediments or no longer passing an initial infiltration text will be cleaned using procedures from Appendix A of 2017 City of Renton SWDM or the manufacturer’s procedures. f. Keep all heavy equipment off existing soils under stormwater facilities and on-site BMPs that have been excavated to final grade to retain the infiltration rate of the soils. 12. Maintain Protective BMPs Protection measures will be maintained to ensure continued performance of their intended function, to prevent adverse impacts to the existing stormwater facilities and on-site BMPs and areas of proposed BMPs/facilities, and protect other disturbed areas of the project. Protection measures will be monitored per Section D.2.4.4 of 2017 City of Renton SWDM at a minimum. a. Maintain and repair all temporary and permanent erosion and sediment control BMPs as needed to ensure continued performance of their intended function in accordance with BMP specifications. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 17 b. Remove all temporary erosion and sediment control BMPs prior to final construction approval or within 30 days after achieving final site stabilization or after the temporary BMPs are no longer needed. c. Provide protection to all stormwater facilities and on-site BMPs installed for the permanent control of stormwater from sediment and compaction. All stormwater facilities and on-site BMPs that are to remain in place following completion of construction will be examined and placed in full operating conditions. If sediment enters the stormwater facilities and/or on-site BMPs during construction, it shall be removed and the stormwater facility and on-site BMP will be returned to the conditions specified in the construction documents or as required for full stormwater facility and on-site BMP replacement. d. Remove or stabilize trapped sediment on site. Permanently stabilize disturbed soil resulting from removal of erosion and sediment control BMPs or vegetation. 13. Manage the Project The project will be effectively managed by coordinating the timing of site development relative to the ESC concerns and timely inspection, maintenance and update of protective measures. A qualified CSWPP Supervisor will be assigned to be the primary contact for ESC and SWPPP issues. In addition, project management will incorporate the following; a. Phase development projects to the maximum degree practicable and take into account seasonal work limits. b. Inspection and monitoring – Inspect, maintain, and repair all BMPs as needed to ensure continued performance of their intended function. Conduct site inspections and monitoring in accordance with the Construction Stormwater General Permit and City requirements. c. Maintaining an updated construction SWPPP – Maintain, update, and implement the SWPPP in accordance with the Construction Stormwater General Permit and City requirements. 8.2 Part B: SWPPS Measures: The following SWPPS measures were considered for application to the project: a) Follow effective pollutant handling and disposal procedures. b) Provide cover and containment for materials, fuel and other pollutants c) Manage Project site to maximize pollutant control and minimize pollutant sources. d) Protect from spills and drips of petroleum products and other pollutants e) Avoid over application or untimely application of chemicals and fertilizers f) Prevent or treat contamination of stormwater runoff by pH modifying sources KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 18 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 9.1 City of Renton Bond Quantity Worksheet To be included with final report. 9.2 Flow Control and Water Quality Facility Summary Sheet and Sketch To be included with final report. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN PAGE 19 10 OPERATIONS AND MAINTENANCE MANUAL All drainage facilities must be maintained by the property owner as specified in the Appendix A, “Maintenance Requirements for Stormwater Facilities and On-site BMPs”, and as further prescribed in Chapter 6 for water quality facilities in City of Renton Surface Water Design Manual. A copy of the Operation and Maintenance Manual submitted as part of the permit application for flow control and water quality treatment facilities used will be retained on site. A log of maintenance activity indicating when cleaning occurred and where waste was disposed of will also be kept by the owner and be available for inspection by the City. KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN FIGURES 1. FIGURE 1: TIR WORKSHEET 2. FIGURE 2: SITE LOCATION MAP 3. FIGURE 3: DRAINAGE BASIN MAP 4. FIGURE 4: EXISTING DISCHARGE POINT 5. FIGURE 5: NRCS WEB SOIL SURVEY 6. FIGURE 6: FLOW CONTROL APPLICATION MAP FIGURE 1: TIR WORKSHEET KING COUNTY ANGELA CHUNG DAVID EVANS AND ASSOCIATES 425-519-6504 AFIS LAB REPLACEMENT 900 OAKSDALE AVE SW RENTON, WA 98057 CIVIL CONSTRUCTION PERMIT FIGURE 1: TIR WORKSHEET BLACK RIVER DRAINAGE BASIN SPRING BROOK CREEK FIGURE 1: TIR WORKSHEET WOODINVILLE SILT LOAM LID IS NOT FEASIBLE THERE IS NO ADEQUATE SPACE FOR DISPERSION, INFILTRATION AND BIORETENTION SYSTEMS ON SITE. PERMEABLE PAVEMENT IS NOT FEASIBLE WHILE REPLACING EXISTING PGIS. 3000 SQFFT ADDITION AND PARKING LOT MODIFICATION FULL DRAINAGE REVIEW - ALL 8 CORE REQUIREMENTS APPLY ONE 07/19/2017 EXCEPTION #1 UNDER PEAK FLOW RATE STANDARD AREAS TBD FILL MATERIALS 0 - 5% 0 - 5% SEE GEOTECH REPORT SEE GEOTECH REPORT FIGURE 1: TIR WORKSHEET COMMERCIAL FIGURE 1: TIR WORKSHEET FILTERRA VAULT FIGURE 1: TIR WORKSHEET NTS FIGURE 2: SITE LOCATION MAP PROJECT SITE BN Inc4th R a i n i e r Lind3rd Cedar River 140thPetr o v i t s k yI-405TalbotParkG rady I-5SR 167108th148thInterurban68thBenson84thLogan95th 144thDuvall78th 16th WellsAndoverOakesdale27th SR 515Coal Creek128th 72nd43rd MercerWest Valley8th May Valley Carr 116th 79th 76thPuget6th 164thRe n t o n I ssa q u a h 134th KirklandFairwo o d Rento n M a p l e ValleyMonroe Southcenter132nd 80th 204th 41st East Valley34th 89th Langston 5th 200thUnionWilliamsB e a c o n 154thHoquiamMa p l e V a l l e y57th9th 30th Forest JonesSeward ParkNewcastle Aberdeen184thBangor 88th 1 6 9 t h SR 900194th CornellHarringtonHardieValleyPelly5 6 t h 58th183rd121st 161st62nd168th149th64th Parkside96th63rdGarden186th Strander 87th19th Mi l l Sunset 176th59thPedestrian156th1 2th 21st 70th 175thLincoln125th135t h Leo 61st31st 155th9 2 n d Di x o n 118th24th81st Re n t o n 133rd 2nd 166th15th Lakemont160th 1 0th 14th Avon Island CrestTukwilaMaule Newcas t l e G o l f C lub 1 7 1 s tEdmonds39th 141st Martin L King Jr Taft 29th Blaine192nd 180th FieldTobin La k e r i d g e Si dney 114th 208th 177th196t h174th106th53rd38th93rd32nd 8 3rd Lake Youngs T r ai lShattuck 142nd 82nd 136thCrestwoodAccess112th Lic o r i c e 143rd23rd Soos C reek Wo o d s i d eBronsonHolly 131stNorfolk 138th 104th52ndIn d e x 159th55thPerimeter 105th199th 17 8 th 65th 6 6t h 71st Airport BurnettRoyal Hills123rd126th OlympiaMon s t e r 75 th HouserWoodley190thIsland 7th 28th 167th35th Rosario85th 1st 33rd 91st IndustryFir Macadam60thSunnycre s t AnacortesLynnwoodMinkler Rustic103rd98thLake173rdAccess R d w y LyonsFrager181st22nd 1 3 0 t h 145thRiverside158th111thSperryTaylo r 102nd 40th Pasco151st198th 179thDavisB e a c o n C o a l M i n e 201st Baker Ryan Nile110thGree n River 69th124thOthello MapleAuburn188th 170th137thWa b a s h Avalon 129thAW e s t L a k e D e s irePi e r c e54th Klickitat 193rd Lake Youngs Service 73rd Rail road 13th 195thMorris139th109th36th122ndPrivateBoeing 117th120th157th47th Todd 25th Myrtle F e r n d a l e MainFletcher Juniper L u t h e r 113th20th 209th163rd77thLake WashingtonPowellCedar146th 1 5 0 t h 182nd172ndThomasHillside Pilgrim High17thWate rs 99thHazelwood42nd OlympicEast Lake DesireSheltonKenyon 206th Triland 100th VashonStevens97th187th OrcasOakOl d P e t r o v i t s k y 119th 147thRolling HillsL a k e Y o u n g sRussell6th pl 11th Hazel Winds or 45th 165thWallace 202nd 48th 152nd37th JeffersonPine26th 127th Victoria 115th67th 191st Ca m a s 185th 94thL a u r e l GlenwoodJericho107thRose Eden 90th Costco Willow Brighton NachesCapri203rd 18th Upland ChristensenSunwoodCeda r R i d g eHouser Way BypassMonte rey Kent BoeingRipleyRenton TC86th Eagle Ridge44th Ilwaco212thKennewick50thSeneca Cou n t y Ro a d 6 6 M e a d o w GrantLongacres153rd L im a Arr ow sm i t h DaytonQuinceyMidland GemMountain View46th 7 4 t h 101st Segale Park B189th WhitmanPrentice 162ndF o un t ai n Center Point207th Warsaw Treck ElmaQueenP a r k A c c e s s Shore Renton Dist CtChelanLewis 855th Oaksdale197th Gazelle Augusta 136 Talbot CrestKitsapUnnamedBoeing RentonNelsonGene Coul on Park49t h Ridgecrest Victo r Park ViewRedmondMosesTacomaH o ly o k e Rox bury Smither sNels BerglundEvergreen La ke Vi ew R a ym o n d Riverview Park BremertonGrahamSouthcent e r M a ll Whitwo rt h Eastwood Cooper Berkshire AptWestwood Du n c a n Kentridge HS Corporate 95th 140th 120th 150th1st 119th3rd 139th 77th 71st 184th 18t h 1 4 4 t h Lincoln1 8 1st118th145thVashonAccess143rd139th65th 18 2n d 114th61st116th 148th64th11th Kirkland10th 147thHoquiam70th105th121st I-584th61stAccess142ndP r i v a t e 172nd137th173rd140th 134th112th 166th124th8th Morris86thPrivateCamas124th 74th 105th7 4t h 142nd 192nd 1 6 7 t h 146th12 6 t h 155th 162ndAc c e s sWilliams 184th 3rd 8th 178thMo n t ere y81st 208th 7 4 t h 184th182nd 166thDayton 193rd127th 177thCamas129th 155th59th131st 130th 54th 88th 4t h 69 t h 18th 1st Private 152nd170th 5th 76th A ccess102nd70th77th92nd 126th 161st105th128th17 5 t h 187th 112thAc cess 115th 102nd 162nd57th57th9th 170th79thQueen6th83rd 193rd 154 t h PrivateRedmond35th 116th169th103rd154thMeadow23rd130th181stPierce133rd121st 105th144th86th 10th 22nd 67th 141st140th71st3rd 173rd 116th 199th 113th 184th199th 137th71stAnacortes 104thHarrington1st132nd 2nd 151st139thPriv ate 81st58th206th Glenwood80th114th147th177th Burnett117thP e d e s t r i a n Private Minkler 104th140th7th 110th2nd 135th 186 t h 94thPrivate165th Access73rd61st Shattuck143rd135th 18 0th 101st68th152nd 175th147thP e d e stria n 196th Access4th WellsMain9th 100th 98thPrivat e 138th 168th 4th 124th1 7 1st 106th23r d 10th 77th141st 37th 65th 170th Private146th7th 138th209th 128th119th4th 113th184th I- 5 173rd 202nd PrivatePrivate75th 127thGr e e n R i v e r 123rd 161st143rd 128th18th 3rd72nd Pasco83rd64th157t hPrivateBurnett130th 136th 1st Private160th165th130th92nd 165th 16 8 t h 121stLake Young s T r a i l151st 165thP r i v a t e 179th135th118th145th 198thI-5164th121stPrivate175th 3rd 8th Pelly78thHouser26th 178thIndexJon e s150thPrivate 117th 141st70th185th21st 106th 136th 113th111th149th 169th120th84th176th 191st 5th 158thPrivate 169th126th 143rd 109th170th134th 5th120th I-5 192ndBlaine 3rd 200th 160th200th 134th 78th69th5thLind12th 202nd 206th Private 62nd17th 92nd 124th132ndRaymond151st103rd 66t h 146th70th 184 th 156th1st 1 50th 87th 3rd 177th102ndA c c e s s Priva te157t h Private 8th 32ndGr e e n R i v e r 171st181st 125th174th57th14 1st Pri v a t eDayton112th 189th 133r d134th 175 th 21st 71st Private72nd160th3rd 119th 77th27th119th 204th 1 2 6 t h 3 rd A cces s 118th141s t 6th 4th 23rd 123rdLind190th 4t h Access 87 t h S R 51583rd1st 198th 164th 7th 7th 143rd7 5 t h 18thSR 515Access 135th150th130th52nd68thPri v a t e 6th 119th Cedar6th 129thStevens143rd9th 29th 86th Jones99th 202nd 146thJefferson2nd 144th Index1 57th 1 7 2 n d 2nd 120th78th 160th Private124th 16th 180th122nd 70thPrivate 76th 185th Kent Boeing Morris5th 141 s t 169th16 1 s t119th 21st AccessAccess3 6th 111th4th 77th Unnamed143rd20th 66th149th56th191 st Private AccessPr i vate 43rd 160thPierce156th129th Interurban179th 169th173rd 1st 1 5th 124th67th 156th118th121stElma71st114th 24th 90th121st131st 74 th 68th 28th 32nd 154th180th 130th 181st 185th 156thPrivate71st 157th1 7 0 t h 98thPriva t e 142nd204th 165 t h114th 17th Private105th4th 1 34th 182nd 120th Jones126th21st Pedestrian181st188th 18 5th 20t h Powell183rd178th Jericho136th190th Parkside163rdAccess 2nd 143rd 167th 188th 20th56th 91st 176th 164th172nd17 4 t h 136th 171st66th 11th129thAberdeen Access100th172nd 116th 155th190th 55th S u n s e t 64th132nd166th 135th125 th 56th184th66th 131st13th Private 152nd204th 149th152nd59th80thAccess122nd1 2 4 t h 204th 18 4 t h113th113th 27th67th 127th199th 148th 23rd 147th152nd105th10th 163rd6 th 27th 2nd 202nd 5th 162ndAccess 4th 72nd 164th 168th83rd 133rd2 0 t h 1 48th 138th59th118th4th 127th Ped e s t r i a n 139th 4th57th 143rd138th190th114th21st 122nd 170th I n t e r u r b a n 8th 173rd 180thPr i v ate 66th124th 115th1 6 th 19th81st26th Camas65th134t h192ndAndover 161st 39th Access 177th65th180th88th E dm o n d s Private 28th 84th110th106th122nd4th123rd118th Elma2 7 t h 168th148thPrivate 160th27th 172nd 12 0 t h 1st 7th 85th186th 16 t h 160thPrivate 1 2 6 t h 1 89th 116th Maple122nd208th 196th54th 141st165th123rd21st Pri v a t e 166th62nd 76th 6th 172nd 178th85th6 7 t h 6th 187th Access 25th P rivate 103rd196thPrivate 10th A c ces s Hazel 174th 140th 27th 31st 124th 146thBenson180th86t h Private 158th 184th 128th133rd194th IndexLyons6th 168th132nd149th 110th80th 148th190th 112th Access Williams178th 66th 126th74th189th 106th66th96th136th164th78t h 145th 196t hPrivate171st 145t h Acc e s s 190th 75th143rd78th 127thHigh144th Private165t h 188th 29th 8th80th 174th72nd 2nd 37th56th 111th164th68thPark133rd150th23rd Private 77th 1 2 6 t h 184th 1 3 3 r d 117th 10th Access 148th184thLake9th 192nd 120thRyan Access 164th132nd 85th 1 2 2 n d120th Olympia5th 125th Smithers36th 2nd ThomasMonterey175th 72nd152ndMill1 7 1 s t 65th 144thLa n g s t o n 87th200th 117th 131st160th 67t h 5th 37th 66th 131st 13th Blaine43rd 167th Acce ssAccess May Val ley56th 82ndPrivate 142nd 1 2 0 t h 1 s t 20th 194t h 4th PrivateAccess30th 16th 172nd 137th 7th 182nd Private145th 190th 92nd85th76th 131st 190th 125th7th 199th80th135th 78thHazelwood Davis82nd164th 179t h 4th 76th 126thDayton120th 118th149th 166th154th172nd68th69th4 0 t h 146th115th82nd184th116th75th123rd5th 91 st Private3rd AccessIndexLake96th 159th 196th 156th136th 159thPrivate132nd158th76th32nd 109th81st 117th9 8th 180th 25th 160th2ndMill 128th110 t h 80th110th 162nd142ndPrivate56th24th 172nd158th140th 167th Access 193rd Chelan 203rdAccess 163rd 1st Pedes t r i an162nd 169th82nd 158thHouser186th 57 t h 201st 65th 196th 7th Access114th204th 22nd Access10th Priv ate RentonPark1 8 t h57th85th10th84th 23rd55th 158thShattuck160thGrant5th Jones120th4th 9th 143rd98th113th77th6th 132nd66 t h 61st124th201s tAccess 132nd Access A ccess 108thPrivate 166th 184th I -405 198th 2 n d 89th158th76th54th81st126th155th 136th64th A c c e s s 116th19th 58th160th 76th 160thAccess166th157thTacomaJonesAccess 3rd 108th Maple21st 7th 126th167th 6th 10th Private5th 8th 7 1 s t 26th Private 194th 144thPrivate 129th Private8 thGarden 20th Access128th62nd82nd 185th 6th 12th 143rd 114th CedarPrivate71st116th62nd3rd 128th59th7th A c c e s s AccessPrivate120th 139th 92nd174thPrivate96th14th Cedar172nd199 t h56th138th66th 164th170thSunset 130th7th 168th 9th 10th 182nd15 7 t h Access 118th 3rd 176th 96th182nd 25th 138thAccess 100th 18 7 t h 24th 16th 149th 123rd 159th May Cre ek Coal Creek Un n a m e d Madsen CreekSpringbrook CreekCoal Cr e e k T r i b u t a ry UnnamedU nnamed Coal CreekUnnamedUnnamedUnnamed UnnamedUnnamedUnnamedUnnamedKing County Kent Tukwila Newcastle Seattle Bellevue King County Mercer Island King County King County SeaTac King County King County King County King County Kent Renton City Limits Potential Annexation Area Basins Black River Duamish Lake Washington East Lake Washington West Lower Cedar River May Creek Soos Creek ´ Surface Water Utility Comprehensive Plan Printed 10/16/2009 Basin Locations 0 10.5 Miles PROJECT SITE FIGURE 3: DRAINAGE BASIN MAP 4,514 376 City of Renton Print map Template This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. None 6/27/2017 Legend 2560 128 THIS MAP IS NOT TO BE USED FOR NAVIGATION Feet Notes 256 WGS_1984_Web_Mercator_Auxiliary_Sphere Information Technology - GIS RentonMapSupport@Rentonwa.gov City and County Boundary Other City of Renton Addresses Parcels Renton Fire Hydrant Hydrant Other System Water Gravity Pipe Water Main Water Service Areas Lift Station Clean Outs Manholes Casings Pressurized Mains Renton Private Gravity Mains Renton Private KC Pressurized Mains KC Gravity Mains Network Structures Inlet Manhole Utility Vault FIGURE 4: EXISTING DISCHARGE POINT DOWNSTREAM DISCHARGE POINT TO THE CITY STORM SYSTEM PROJECT SITE Hydrologic Soil Group—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/22/2017 Page 1 of 4525777052577905257810525783052578505257870525789052579105257790525781052578305257850525787052578905257910557660557680557700557720557740557760557780557800557820557840557860 557660 557680 557700 557720 557740 557760 557780 557800 557820 557840 557860 47° 28' 19'' N 122° 14' 5'' W47° 28' 19'' N122° 13' 55'' W47° 28' 14'' N 122° 14' 5'' W47° 28' 14'' N 122° 13' 55'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 45 90 180 270 Feet 0 10 20 40 60 Meters Map Scale: 1:992 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. FIGURE 5: NRCS WEB SOIL SURVEY MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 12, Sep 8, 2016 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 31, 2013—Oct 6, 2013 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/22/2017 Page 2 of 4 FIGURE 5: NRCS WEB SOIL SURVEY Hydrologic Soil GroupHydrologic Soil Group— Summary by Map Unit — King County Area, Washington (WA633)Map unit symbol Map unit name Rating Acres in AOI Percent of AOIUrUrban land 0.1 1.1% Wo Woodinville silt loam C/D 4.8 98.9% Totals for Area of Interest 4.8 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Hydrologic Soil Group—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/22/2017 Page 3 of 4 FIGURE 5: NRCS WEB SOIL SURVEY Component Percent Cutoff: None SpecifiedTie-break Rule: HigherHydrologic Soil Group—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/22/2017 Page 4 of 4 FIGURE 5: NRCS WEB SOIL SURVEY FIGURE 6: FLOW CONTROL APPLICATION MAP PROJECT SITE KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN Appendix A – OFFSITE ANALYSIS 1. DOWNSTREAM ANALYSIS MAP 2. PHOTOS 3. FIELD NOTES CB ACB B CB C CB D CB E SDMH A SDMH B SDMH C SDMH D SDMH E SDMH F SDMH G SDMH H SDMH I SDMH K DOWNSTREAM ANALYSIS MAP OUTFALL IN THE BLACK RIVER PROJECT SITE CB A CB B CB E SDMH ACB E SDMH B SDMH D SDMH E SDMH H SDMH KTO OUTFALL KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN Appendix B – FLOW CONTROL 1. WWHM HYDROLOGIC ANALYSIS 2. EXISTING LAND COVER EXHIBIT 3. PROPOSED LAND COVER EXHIBIT WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: AFIS LAB Site Name: AFIS LAB Site Address: 900 OAKSDALE AVE SW City : RENTON Report Date: 8/25/2017 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2017/04/14 Version : 4.2.13 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .1 Pervious Total 0.1 Impervious Land Use acre SIDEWALKS FLAT 0.01 PARKING FLAT 0.27 Impervious Total 0.28 Basin Total 0.38 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .1 Pervious Total 0.1 Impervious Land Use acre ROOF TOPS FLAT 0.07 SIDEWALKS FLAT 0.04 PARKING FLAT 0.17 Impervious Total 0.28 Basin Total 0.38 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.1 Total Impervious Area:0.28 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.1 Total Impervious Area:0.28 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.113141 5 year 0.14527 10 year 0.167376 25 year 0.196336 50 year 0.218695 100 year 0.241753 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.113141 5 year 0.14527 10 year 0.167376 25 year 0.196336 50 year 0.218695 100 year 0.241753 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.153 0.153 1950 0.152 0.152 1951 0.095 0.095 1952 0.078 0.078 1953 0.084 0.084 1954 0.092 0.092 1955 0.103 0.103 1956 0.102 0.102 1957 0.119 0.119 1958 0.092 0.092 1959 0.090 0.090 1960 0.098 0.098 1961 0.101 0.101 1962 0.084 0.084 1963 0.098 0.098 1964 0.092 0.092 1965 0.124 0.124 1966 0.079 0.079 1967 0.138 0.138 1968 0.157 0.157 1969 0.113 0.113 1970 0.106 0.106 1971 0.126 0.126 1972 0.138 0.138 1973 0.074 0.074 1974 0.117 0.117 1975 0.125 0.125 1976 0.091 0.091 1977 0.091 0.091 1978 0.113 0.113 1979 0.154 0.154 1980 0.156 0.156 1981 0.117 0.117 1982 0.170 0.170 1983 0.132 0.132 1984 0.085 0.085 1985 0.118 0.118 1986 0.099 0.099 1987 0.152 0.152 1988 0.090 0.090 1989 0.113 0.113 1990 0.228 0.228 1991 0.175 0.175 1992 0.085 0.085 1993 0.071 0.071 1994 0.075 0.075 1995 0.103 0.103 1996 0.117 0.117 1997 0.112 0.112 1998 0.107 0.107 1999 0.232 0.232 2000 0.113 0.113 2001 0.118 0.118 2002 0.150 0.150 2003 0.117 0.117 2004 0.215 0.215 2005 0.099 0.099 2006 0.089 0.089 2007 0.203 0.203 2008 0.172 0.172 2009 0.138 0.138 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.2319 0.2319 2 0.2278 0.2278 3 0.2154 0.2154 4 0.2030 0.2030 5 0.1755 0.1755 6 0.1723 0.1723 7 0.1698 0.1698 8 0.1570 0.1570 9 0.1564 0.1564 10 0.1539 0.1539 11 0.1528 0.1528 12 0.1521 0.1521 13 0.1517 0.1517 14 0.1503 0.1503 15 0.1385 0.1385 16 0.1383 0.1383 17 0.1378 0.1378 18 0.1316 0.1316 19 0.1261 0.1261 20 0.1247 0.1247 21 0.1241 0.1241 22 0.1194 0.1194 23 0.1179 0.1179 24 0.1175 0.1175 25 0.1173 0.1173 26 0.1173 0.1173 27 0.1171 0.1171 28 0.1168 0.1168 29 0.1130 0.1130 30 0.1128 0.1128 31 0.1128 0.1128 32 0.1125 0.1125 33 0.1119 0.1119 34 0.1069 0.1069 35 0.1057 0.1057 36 0.1034 0.1034 37 0.1030 0.1030 38 0.1018 0.1018 39 0.1009 0.1009 40 0.0991 0.0991 41 0.0988 0.0988 42 0.0984 0.0984 43 0.0976 0.0976 44 0.0951 0.0951 45 0.0922 0.0922 46 0.0922 0.0922 47 0.0916 0.0916 48 0.0910 0.0910 49 0.0906 0.0906 50 0.0905 0.0905 51 0.0903 0.0903 52 0.0887 0.0887 53 0.0855 0.0855 54 0.0847 0.0847 55 0.0842 0.0842 56 0.0839 0.0839 57 0.0792 0.0792 58 0.0779 0.0779 59 0.0754 0.0754 60 0.0742 0.0742 61 0.0714 0.0714 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0566 1695 1695 100 Pass 0.0582 1551 1551 100 Pass 0.0598 1390 1390 100 Pass 0.0615 1253 1253 100 Pass 0.0631 1120 1120 100 Pass 0.0648 1026 1026 100 Pass 0.0664 944 944 100 Pass 0.0680 866 866 100 Pass 0.0697 778 778 100 Pass 0.0713 717 717 100 Pass 0.0729 658 658 100 Pass 0.0746 611 611 100 Pass 0.0762 562 562 100 Pass 0.0779 525 525 100 Pass 0.0795 491 491 100 Pass 0.0811 447 447 100 Pass 0.0828 410 410 100 Pass 0.0844 380 380 100 Pass 0.0860 361 361 100 Pass 0.0877 338 338 100 Pass 0.0893 318 318 100 Pass 0.0910 289 289 100 Pass 0.0926 270 270 100 Pass 0.0942 251 251 100 Pass 0.0959 236 236 100 Pass 0.0975 221 221 100 Pass 0.0991 200 200 100 Pass 0.1008 194 194 100 Pass 0.1024 182 182 100 Pass 0.1041 167 167 100 Pass 0.1057 157 157 100 Pass 0.1073 147 147 100 Pass 0.1090 137 137 100 Pass 0.1106 131 131 100 Pass 0.1122 122 122 100 Pass 0.1139 113 113 100 Pass 0.1155 108 108 100 Pass 0.1172 101 101 100 Pass 0.1188 93 93 100 Pass 0.1204 88 88 100 Pass 0.1221 82 82 100 Pass 0.1237 81 81 100 Pass 0.1254 77 77 100 Pass 0.1270 76 76 100 Pass 0.1286 74 74 100 Pass 0.1303 67 67 100 Pass 0.1319 66 66 100 Pass 0.1335 62 62 100 Pass 0.1352 57 57 100 Pass 0.1368 55 55 100 Pass 0.1385 52 52 100 Pass 0.1401 48 48 100 Pass 0.1417 46 46 100 Pass 0.1434 43 43 100 Pass 0.1450 41 41 100 Pass 0.1466 40 40 100 Pass 0.1483 37 37 100 Pass 0.1499 34 34 100 Pass 0.1516 31 31 100 Pass 0.1532 27 27 100 Pass 0.1548 26 26 100 Pass 0.1565 24 24 100 Pass 0.1581 21 21 100 Pass 0.1597 20 20 100 Pass 0.1614 19 19 100 Pass 0.1630 17 17 100 Pass 0.1647 16 16 100 Pass 0.1663 15 15 100 Pass 0.1679 14 14 100 Pass 0.1696 13 13 100 Pass 0.1712 12 12 100 Pass 0.1728 9 9 100 Pass 0.1745 9 9 100 Pass 0.1761 8 8 100 Pass 0.1778 8 8 100 Pass 0.1794 8 8 100 Pass 0.1810 8 8 100 Pass 0.1827 8 8 100 Pass 0.1843 8 8 100 Pass 0.1859 8 8 100 Pass 0.1876 8 8 100 Pass 0.1892 8 8 100 Pass 0.1909 7 7 100 Pass 0.1925 7 7 100 Pass 0.1941 7 7 100 Pass 0.1958 7 7 100 Pass 0.1974 7 7 100 Pass 0.1990 7 7 100 Pass 0.2007 7 7 100 Pass 0.2023 7 7 100 Pass 0.2040 5 5 100 Pass 0.2056 5 5 100 Pass 0.2072 4 4 100 Pass 0.2089 4 4 100 Pass 0.2105 4 4 100 Pass 0.2121 4 4 100 Pass 0.2138 3 3 100 Pass 0.2154 3 3 100 Pass 0.2171 2 2 100 Pass 0.2187 2 2 100 Pass _____________________________________________________ ___________________________________________________________________ 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. ___________________________________________________________________ LID Report LID Technique Used for Total Volumn Volumn Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volumn Volumn Volumn Water Quality Treatment Facility (ac-ft.) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Total Volume Infiltrated 0.00 0.00 0.00 0.00 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2017; All Rights Reserved. 58 58 KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN Appendix C - CONVEYANCE SYSTEM ANALYSIS 1. RATIONAL METHOD CALCULATIONS 2. BENTLEY FLOW MASTER ANALYSIS Project Name: AFIS LAB REPLACEMENT Project Number: BUFF0011 Location Bellevue WA Date: 6/28/2017 By: SGR Calculation for:EXISTING + PROPOSED AREAS Flowrates: 2 Yr 0.35 cfs 10 Yr 0.71 cfs 100 Yr 1.03 cfs Tc 6.3 Minutes Area 0.360 Acres C 0.90 Impervious surfaces Area draining to detention vault: 0.000 Ac @ C=0.25 (landscape) 0.360 Ac @ C=0.9 (Impervious Surface) P R a R b R I R 2 Yr 2 1.58 0.58 1.09 10 Yr 2.9 2.44 0.64 2.18 100 Yr 3.9 2.61 0.63 3.19 Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.013 Channel Slope 0.01000 ft/ft Normal Depth 0.67 ft Diameter 0.67 ft Results Discharge 1.22 ft³/s Flow Area 0.35 ft² Wetted Perimeter 2.10 ft Hydraulic Radius 0.17 ft Top Width 0.00 ft Critical Depth 0.52 ft Percent Full 100.0 % Critical Slope 0.01098 ft/ft Velocity 3.47 ft/s Velocity Head 0.19 ft Specific Energy 0.86 ft Froude Number 0.00 Maximum Discharge 1.32 ft³/s Discharge Full 1.22 ft³/s Slope Full 0.01000 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise 100.00 % Downstream Velocity Infinity ft/s 7/24/2017 8:59:17 AM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of1Page 8" PVC PIPE AT 1% SLOPE GVF Output Data Upstream Velocity Infinity ft/s Normal Depth 0.67 ft Critical Depth 0.52 ft Channel Slope 0.01000 ft/ft Critical Slope 0.01098 ft/ft 7/24/2017 8:59:17 AM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of2Page 8" PVC PIPE AT 1% SLOPE KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN Appendix D - WATER QUALITY 1. EXHIBIT D-1: NEW AND REPLACED PGIS AREA 2. EXHIBIT D-2: PGIS AREA TREATED BY FILTERRA 58 58 KING COUNTY REGIONAL AFIS LAB REPLACEMENT AUGUST 2017 STORMWATER SITE PLAN Appendix E - OTHER REPORTS 1. GEOTECHNICAL REPORT 2. GEOTECHNICAL REPORT INFILTRATION ADDENDUM Job No. 1701 S&EE S&EE GEOTECHNICAL REPORT KING COUNTY REGIONAL AFIS LAB 900 OAKESDALE AVE. SW, RENTON, WA S&EE JOB NO. 1701 MARCH 7, 2017 1701rpt S&EE TABLE OF CONTENTS Section Page 1.0 INTRODUCTION ................................................................................................................................................. 1 2.0 SCOPE OF WORK ............................................................................................................................................... 1 3.0 SITE CONDITIONS ............................................................................................................................................. 2 3.1 SITE GEOLOGY ................................................................................................................................................ 2 3.2 SURFACE AND SUBSURFACE CONDITIONS ............................................................................................... 3 4.0 LABORATORY TESTING ................................................................................................................................. 3 5.0 ENGINEERING EVALUATIONS AND RECOMMENDATIONS ................................................................. 4 5.1 SEISMIC CONSIDERATIONS .......................................................................................................................... 4 5.1.1 LIQUEFACTION .......................................................................................................................................... 4 5.1.2 SITE CLASS ................................................................................................................................................. 4 5.2 FOUNDATION SUPPORT ................................................................................................................................ 5 5.3 UNDERGROUND UTILITY CONSTRUCTION .............................................................................................. 7 5.3.1 TEMPORARY SLOPE AND SHORING ....................................................................................................... 7 5.3.2 SUBGRADE PREPARATION ..................................................................................................................... 7 5.3.3 DEWATERING ............................................................................................................................................ 8 5.3.4 BUOYANCY RESISTANCE ......................................................................................................................... 8 5.4 LATERAL EARTH PRESSURES ON UNDERGROUND WALLS ................................................................. 9 5.5 SITE PREPARATION AND STRUCTURAL FILL ........................................................................................ 10 5.6 SLAB-ON-GRADE .......................................................................................................................................... 11 5.7 PAVEMENT DESIGN RECOMMENDATIONS ............................................................................................ 11 5.8 ADDITIONAL SERVICES .............................................................................................................................. 12 6.0 CLOSURE ............................................................................................................................................................. 12 FIGURE 1: SITE LOCATION MAP FIGURE 2: SITE & EXPLORATION PLAN FIGURE 3: LIQUEFACTION MAP FIGURE 4: GENERALIZED SOIL PROFILE FIGURE 5: RESULTS OF LIQUEFACTION ANALYSES FIGURE 6: SOIL PROPERTIES USED IN PILE ANALYSES FIGURE 7: RESULTS OF LATERALLY LOADED PILE APPENDIX A: FIELD EXPLORATION, LOG, AND SOIL CLASSIFICATION CHART APPENDIX B: LABORATORY TEST RESULTS 1701rpt S&EE 1 REPORT OF GEOTECHNICAL INVESTIGATION KING COUNTY REGIONAL AFIS LAB For Buffalo Design 1.0 INTRODUCTION We present in this report the results of our geotechnical investigation for the proposed King County Regional AFIS (Automated Fingerprint Identification System) Lab located at 900 Oakesdale Ave. SW, Renton, Washington. The project site is located in the northeastern portion of an office park. A Site Location Map is shown in Figure 1 and a Site & Exploration Plan is shown in Figure 2, both are included at the end this report. We understand that the project will involve a building addition measuring 44 feet by 66 feet for vehicle processing laboratory. This new space will be connected to the existing building with 18 feet long by 16 feet wide corridor. The new structure will be single story and 23 feet in height. The entrance to the corridor will be through an opening of an existing window in the existing building exterior wall. We understand from the project structural engineer that the column and wall loads will be 30 kips and 1.1 kips/feet, respectively. Floor load will be 250 pounds per square feet. The site is relatively flat. As such, cut and fill will be minimal. New underground utilities will include storm and sewer lines. 2.0 SCOPE OF WORK The purpose of our investigation is to provide geotechnical parameters and recommendations for design and construction. Specifically, the scopes of our services have included the followings: 1. Review of available geotechnical data in our file. 2. Exploration of the subsurface conditions at the site by the drilling of 2 soil test borings. 3. Obtain representative soil samples and transport to our sub-contracted soil laboratory for testing. 4. Recommendations regarding foundation supports of the proposed building. 5. Recommendation regarding slab support. 1701rpt 2 S&EE 6. Performance of liquefaction analyses and recommendations regarding seismic design. 7. Recommendations regarding passive, active and at-rest earth pressures and coefficient of friction for the resistance of lateral loads. 8. Recommendations regarding site preparation, suitability of onsite soils for use as fill, types of suitable imported fill, fill placement techniques, and compaction criteria. 9. Recommendations regarding angles of temporary and permanent slopes. 10. Recommendations regarding underground utility construction; recommendation regarding excavation shoring and construction dewatering, if necessary. 11. Recommendations regarding flexible and rigid pavement designs. We will provide subgrade CBR value for flexible pavement and subgrade reaction modulus for rigid pavement designs. 12. Preparation of a geotechnical report containing a site plan, a description of subsurface conditions, and our findings and recommendations. 3.0 SITE CONDITIONS 3.1 SITE GEOLOGY Published geologic information indicates that the site is underlain by alluvium (Qaw). These soils are chiefly sand, silt, and clay deposited by the White and Green Rivers before the diversion of the White River to the south in 1906. The upper parts of these alluvial are mostly clayey silt and fine sand with thickness ranges from 30 to 40 feet near Tukwila. The lower parts are mostly medium and coarse sand that are more than 75 feet in thickness. (Geologic map of the Renton Quadrangle, King County, Washington by D.R. Mullineaux, 1965, USGS) Seismic Hazards The project site is under the threat of the movement of Seattle Fault. This fault is a collective term for a series of four or more east-west-trending, south-dipping fault strands underlying the Seattle area. This thrust fault zone is approximately 2 to 4 miles wide (north-south) and extends from the Kitsap Peninsula near Bremerton on the west to the Sammamish Plateau east of Lake Sammamish on the east. The four fault strands have been interpolated from over-water geophysical surveys (Johnson, et al., 1701rpt 3 S&EE 1999) and, consequently, the exact locations on land have yet to be determined or verified. Recent geologic evidence suggests that movement on this fault zone occurred about 1,100 years ago, and the earthquake it produced was on the order of a magnitude 7. A liquefaction map (Figure 3: Preliminary Liquefaction Susceptibility Map of the Renton Quadrangle, Washington by Stephen Palmer) indicates that the project area has high liquefaction susceptibility. 3.2 SURFACE AND SUBSURFACE CONDITIONS The proposed AFIS lab is located in a parking area behind (at the northeastern corner of) the existing building. The area is relatively flat. Underground utilities in the area include stormdrain and gas lines. According to the as-built foundation plan (11-9-90), the existing 3-story building is supported on 16-inch diameter augercast piles having 55 and 75 tons capacities. On September February 2, 2017, we explored the subsurface condition at the site by the drilling of 2 soil test borings. The locations of these borings are shown on Figures 2 - Site & Exploration Plan. The boring logs are included in Appendix A of this report. A generalized soil profile is shown in Figure 4. The boring data show that the subsurface conditions at the site include fill over native soils. The fill is about 5 to 6 feet in thickness and includes loose to medium dense, sand, silty sand and silt. The native soils below the fill include 15.5 feet of very soft and very loose, silt, clay and silty sand. We believe these soils represent the upper part of the alluvium indicated in the geologic map. The soils under this upper alluvium include medium dense to very dense sand and gravel. We believe these soils represent the lower alluvium. Both borings ended in this unit. Groundwater was encountered at a depth of 6 feet 8 inches at the time of drilling. Based on our experience with the subsurface conditions in the site vicinity, we believe that the depth of groundwater is affected by precipitation. We expect that the groundwater may fluctuate between about 6 to 10 feet below ground surface. 4.0 LABORATORY TESTING The soil sample at the depth of 11.5 feet from Boring B-2 was transported to our sub-contracted laboratory, Materials Testing & Consulting, for consolidation testing of the silty/clayey soil. The soil properties were used in the evaluation of consolidation (long-term) settlement. The test results are included in Appendix B. 1701rpt 4 S&EE 5.0 ENGINEERING EVALUATIONS AND RECOMMENDATIONS 5.1 SEISMIC CONSIDERATIONS 5.1.1 LIQUEFACTION As mentioned previously, the project site is under the threat of earthquakes from Seattle fault. Based on US Geologic Survey, the intensity or Peak Ground Acceleration (PGA) from this crustal event will be about 0.6g. Liquefaction is the primary geotechnical impacts from such earthquakes. Liquefaction is a condition when vibration or shaking of the ground results in the excess pore pressures in saturated soils and subsequent loss of strength. Liquefaction can result in ground settlement. In general, soils that are susceptible to liquefaction include saturated, loose to medium dense sands and soft to medium stiff, low- plasticity silt. The evaluation of liquefaction potential is complex and is dependent on many parameters including soil’s grain size, density, and level of ground acceleration and duration of vibration. We performed liquefaction analyses for the project site using a computer program, Lique-Pro. The results are shown in Figure 5. As indicated in the figure, liquefaction will occur in the loose/soft zone from groundwater table to a depth of 21.5 feet, and a pocket of medium dense soil at about 40 feet. Ground settlement of about 2.5 inches may occur. This settlement will result mostly from the loose/soft soils in the upper 21.5 feet, and very slightly from the medium dense soils below 21.5 feet. 5.1.2 SITE CLASS The geotechnical-related parameters for seismic design are evaluated as described in Section 1613.3 of the 2015 IBC Code. From USGS website and using a site latitude of 47.47 degrees and a longitude of -122.23 degrees, the spectral response values for Site Class B (rock) are: SS = 1.450 g (short period, or 0.2 second spectral response) S1 = 0.542 g (long period, or 1.0 second spectral response) The Site Class is selected using the definitions in Chapter 20 of ASCE 7-10 considering the average properties of soils in the upper 100 feet of the soil profile at the site. Using the boring data, we determined that the subsoils correspond to Site Class E (“Soft Clay Soil”) in Table 20.3-1 (ASCE 7-10). The site coefficient values, obtained from Section 1613.3.3 of the 2015 IBC, are used to adjust the 1701rpt 5 S&EE mapped spectral response acceleration values to get the adjusted spectral response acceleration values for the site. The recommended Site Coefficient values for Site Class E are: Fa = 0.9 (short period, or 0.2 second spectral response) Fv = 2.4 (1.0 second spectral response) The most recent USGS Earthquake Hazards Map (U.S. Geologic Survey web site, 2008 data) has indicated that a horizontal peak acceleration (PGA) of 0.6 g is appropriate for a 4,275-year return period event, i.e. an event having a 2 percent chance of being exceeded in 50 years. 5.2 FOUNDATION SUPPORT Due to the risk of liquefaction, we recommend that the proposed building be supported by concrete augercast piles. We recommend that the pile be 16-inch in diameter with the pile tip embedded at a depth of 35 feet below the ground surface. The minimum pile spacing should be 5 feet on center. Pile Capacities: The pile will develop a total downward capacity of 88 kips. This capacity is obtained with the reduced soil strengths under the liquefaction condition, and includes an allowable working load of 70 kips and a downdrag force of 18 kips after liquefaction. The allowable upward capacity is 20 kips. These capacities include a safety factor of about 1.5 and 2.0 under the static and seismic conditions, respectively. Figure 6 shows the soil parameters used in the evaluations. Response to Lateral Load: Figure 7 shows that the top of pile deflection will be about ½ inch when subjected to a lateral load of 10 kips. The evaluation assumes a free head connection. The figure also shows that the point of reflection is located at about 14.5 feet below the top of pile. We recommend a point of fixity of 18 feet for design. Additional Lateral Resistance: Additional resistance to lateral loads will be provided by passive soil pressure against pile caps and grade beams. Assuming that structural fill is used for the backfill, an equivalent fluid density of 200 pounds per cubic foot (pcf) may be used for design. The criteria for the structural fill are presented in Section 5.5 of this report. Pile Settlements: Pile settlement will result from elastic compression of the piles and the supporting soils. The settlement is estimated to be about 1/2 inches, and will occur rapidly, essentially as the loads are applied. 1701rpt 6 S&EE Pile Installation: Cement grout must be pumped continuously during withdrawal of the auger, the rate of which should not exceed about 5 to 8 feet per minute. Also, at least 10 feet of grout head must be maintained during the entire withdrawal. We anticipate that the grout volume discharged from the pump to be about 1.2 to 1.5 times the theoretical volume of the drilled hole. The grout volume is usually obtained by counting the number of pump strokes. The grout pressure at the pump should be maintained in the range of 150 to 350 psi, depending on the length of the feeder hose used. The drilling contractor should provide pressure gages and stroke counters at the pump prior to drilling. Quality Control: The piling contractor must implement the following quality control measures. 1. Prior to pile installation, the contractor should provide historical data regarding the volume of grout output per stroke of their pump. If this is not available, the contractor should calibrate the grout pump by filling a 55-gallon drum. This calibration should be performed a minimum of two times and approved by our onsite inspector. 2. Prior to casting, the operator should lift auger 6 to 12 inches at start of grout pumping to facilitate tip plug removal, then return to previously established tip elevation before withdrawal. An initial grout head of 10 feet should be developed before start of auger withdrawal and maintained during extraction. 3. Volume of placed grout should be at least 120 percent of theoretical volume of the hole. 4. If grout pumping is interrupted during placement, the auger should be lowered a minimum of 5 feet before resuming withdrawal. 5. All debris fall into grout column must be removed before the installation of rebar cage. 6. The rebar cage should be equipped with centralizers and the cage should be plumb before inserting into the drilled-hole. Single cable hooked on one side of the cage, or any other mean resulting in tilting of the cage is not allowed. The cage should sink to the design depth by its own weight. Pushing the cage down by machine is not allowed. If grout de-hydration or any other reason preventing smooth cage installation, the hole should be re-drilled and re-grouted. 7. For adjacent piles that are less than 5 feet clear space, the minimum waiting period for installation should be 12 hours. 1701rpt 7 S&EE 8. Pile installation should be monitored by an inspector from our office. Our inspector will evaluate the adequacy of the construction methods and procedures. Any problems which might arise, or deviations from the specifications, will be considered during our evaluations and approval of each pile installed. 5.3 UNDERGROUND UTILITY CONSTRUCTION 5.3.1 TEMPORARY SLOPE AND SHORING Temporary cuts less than 6 feet in depth and above groundwater table can be sloped at 1H:1V, and shoring is likely required for cuts over 6 feet depth and below groundwater table. A variety of shoring methods has been used for the similar soils, including trench boxes, steel sheets, timber lagging, and steel sheetpile. We recommend the following soil parameters for any shoring method that requires structural designs. ¥ Soil’s total unit weight: 125 pcf (pounds per cubic feet) ¥ Soil’s buoyant unit weight: 60 pcf ¥ Active soil pressure: 45 pcf, equivalent fluid density, above groundwater table ¥ Active soil pressure: 21 pcf, equivalent fluid density, below groundwater table ¥ Passive soil pressure: 200 pcf, equivalent fluid density, above groundwater table (include 1.5 safety factor) ¥ Passive soil pressure: 125 pcf, equivalent fluid density, below groundwater table (include 1.5 safety factor) Please note that hydrostatic pressures should be included at both the active and passive sides of the shoring, and the pressure will depend on the type of dewatering method. A 2-foot over-excavation depth at the passive side should be considered in the design. 5.3.2 SUBGRADE PREPARATION All loose soil cuttings should be removed from the subgrade prior to the placement of bedding materials. Wet and loose subgrades may be encountered. The contractor should make efforts to minimize subgrade disturbance, especially during the last foot of excavation. Subgrade disturbance in wet and loose soil may be inevitable, and stabilization is necessary in order to avoid re-compression of the disturbed soils. Depending on the degrees of disturbance, the stabilization may require a layer of quarry spalls (4 to 6 inches size crushed rock). Based on our experience with the site soils, when compacted by the bucket of an excavator, a 12 to 18 inches thick layer of spalls would sink into the loose and soft subgrade, interlock 1701rpt 8 S&EE and eventually form a stable subbase. A chocker stone such as 1-1/4” clean crushed rock should be installed over the quarry spalls. This stone should be 4 to 6 inches in thickness and be compacted to a firm and non-yielding condition using a vibratory plated compactor that weighs at least 1,000 pounds. In the event that soft silty soils above groundwater table are encountered at subgrade, the subgrade should be over-excavated for a minimum of 6 inches. A non-woven geotextile having a minimum grab tensile strength of 200 pounds should be installed at the bottom of the over-excavation and the over-excavation be backfilled with 1-1/4” minus crushed rock. The geotextile should be installed flat with all wrinkles removed and have 12 inches overlap. The rock should be compacted to a firm a non-yielding condition using the same compactor. 5.3.3 DEWATERING Dewatering will be required for excavations deeper than the groundwater table. Based on our experience with the similar subsoils, we believe that for excavation shallower than about 6 feet, dewatering can be successful using local sumps. The contractor should install sumps at locations and spacing that are best fitted for the situation. To facilitate drainage, the sump holes should be at least 2 feet below the excavation subgrade. Also, the granular backfill around the sump should make hydraulic connection with the crushed rock and quarry spalls placed for subgrade stabilization. For excavation deeper than 6 feet, our experience has shown that wellpoints at 5 to 8 feet spacing would provide adequate dewatering, depending on the size of excavation and drawdown requirement. The contractor may need to retain a dewatering specialist for a detailed dewatering design. 5.3.4 BUOYANCY RESISTANCE The subsoils below groundwater table will liquefy during strong earthquakes. As such, buoyancy force should be considered in the design. If the self-weight of the structure and equipment is insufficient to resist the buoyancy force, an extended base can be considered for additional resistance. In this case, the additional resistance can be calculated using the weight of the soil above groundwater table and above the extended base. A soil’s unit weight of 125 pounds per cubic feet (pcf) can be used for this purpose. Sidewall friction should be ignored. 1701rpt 9 S&EE 5.4 LATERAL EARTH PRESSURES ON UNDERGROUND WALLS Lateral earth pressures on permanent retaining walls, underground vaults or utility trenches/pits, and resistance to lateral loads may be estimated using the recommended soil parameters presented in the following table. Equivalent Fluid Unit Weight (PCF) Coefficient of Friction at Base Active At-rest Passive Structural fill 45 60 200 0.4 Note: Hydrostatic pressures are not included in the above lateral earth pressures. The at-rest case applies to unyielding walls, and would be appropriate for walls that are structurally restrained from lateral deflection such as basement walls, utility trenches or pits. The active case applies to walls that are permitted to rotate or translate away from the retained soil by approximately 0.002H to 0.004H, where H is the height of the wall. The passive earth pressure and coefficient of friction include a safety factor of 1.5. SURCHARGE INDUCED LATERAL LOADS Additional lateral earth pressures will result from surcharge loads from floor slabs or pavements for parking that are located immediately adjacent to the walls. The surcharge-induced lateral earth pressures are uniform over the depth of the wall. Surcharge-induced lateral pressures for the "active" case may be calculated by multiplying the applied vertical pressure (in psf) by the active earth pressure coefficient (Ka). The value of Ka may be taken as 0.33. The surcharge-induced lateral pressures for the "at-rest" case are similarly calculated using an at-rest earth pressure coefficient (Ko) of 0.5. 1701rpt 10 S&EE 5.5 SITE PREPARATION AND STRUCTURAL FILL We recommend that areas of proposed building and pavement be stripped of asphalt. All existing underground utilities should also be removed. After stripping and excavation, subgrades of slabs, pavement, or areas to receive new fill should be thoroughly proof-rolled using heavy construction equipment. If the subgrade is wet and proof rolling is not feasible, the area should be probed using a steel bar so as to avoid disturbance and rutting of the subgrade soils. Areas which are found to be loose or soft, or which contain organic soils should be over-excavated. It is our experience that very soft subgrade can be stabilized with 2- foot of over-excavation and backfill with structural fill over a layer of geotextile. A geotechnical engineer/site inspector from our office should observe the proof-rolling and/or perform probing to assist in evaluating the over-excavation and backfill requirements. After stripping, over-excavation and excavation to the design grade, the top 12 inches of the subgrade soil should be moisture-conditioned to +/-2% from it optimum moisture content and then re-compacted to a firm and non-yielding condition or at least 95% of their maximum dry density as determined using ASTM D-1557 test procedures (Modified Proctor test). Structural fill should be used for all fill or backfill. The Structural fill materials should meet both the material and compaction requirements presented below. Material Requirements: Structural fill should be free of organic and frozen material and should consist of hard durable particles, such as sand, gravel, or quarry-processed stone. The onsite granular fill soils above the depth of 5 feet are suitable on a select basis. The native soils below are silty in nature and should not be used. Suitable imported structural fill materials include silty sand, sand, mixture of sand and gravel, recycled concrete, and crushed rock. All structural fill materials should be approved by a site inspector from our office prior to use. Placement and Compaction Requirements: Structural fill should be moisture-conditioned to +/- 2% from optimum prior to placement. The material should then be placed in loose horizontal lifts not exceeding a thickness of 6 to 12 inches, depending on the material type and compaction equipment. Structural fill should be compacted to a firm and non-yielding condition, or at least 95% of the maximum dry density as determined using the ASTM D-1557 test procedures. 1701rpt 11 S&EE 5.6 SLAB-ON-GRADE We recommend that the lab-on-grade be designed using a subgrade reaction modulus of 150 pounds per cubic inches (pci), and the subgrade be prepared in according to recommendations presented above. In order to minimize differential settlement, we recommend that the slab be underlain by 12 inches thick base course over a layer of geotextile. The base course should be 1-1/4” minus crushed rock, placed in two lifts and each lift compacted to a firm and non-yielding condition using a vibratory plate compactor that weighs at least 1,000 pounds. The compactor must make 4 passes (back and forth is one pass) in one direction, then 4 passes in a perpendicular direction. The geotextile should be woven with a minimum 200 pounds grab tensile strength of 200 pounds. The geotextile should be installed flat with all wrinkles removed and have 12 inches overlap. 5.7 PAVEMENT DESIGN RECOMMENDATIONS Pavement subgrade should be prepared according to procedures stated in Section 5.5. We recommend that asphalt pavements be designed with a California Bearing Ratio of 12, and rigid pavements be designed with a subgrade reaction modulus of 100 pci (pounds per cubic inch). The pavements should also be designed for frost protection consisting of at least 15 inches of pavement, base course, and/or granular subbase between the subgrade soils and the top of the pavement. The base course and granular subbase should be non-frost-susceptible and contain no more than 5 percent fines (material finer than a No. 200 U.S. standard sieve). Base course under pavements should consist of well-graded crushed rock. conforming to WSDOT specifications for Crushed Surfacing, Specification 9-03.9(3). Both the subbase and base course layers should be compacted to a firm and non-yielding condition or at least 95 percent of the maximum dry density, as determined by the modified Proctor compaction test (ASTM D 1557). A typical standard-duty (lightweight) pavement section that we have used on similar projects consists of 2.5 inches of Class B asphalt, 4 inches of base course, and 4 inches of subbase. A heavy-duty pavement section could consist of 4.5 inches of Class B asphalt, 6 inches of base course, and 6 inches of subbase. A concrete pavement section could consist of 6 inches of reinforced concrete over 4 inches of base course. Sidewalks could consist of 4 inches of Portland cement concrete over 4 inches of base course. We recommend that these typical sections be considered for planning purposes and that project-specific pavement design analyses be performed. These analyses will require traffic load data such as vehicle axle loads and daily vehicle trips. 1701rpt 12 S&EE 5.8 ADDITIONAL SERVICES We recommend the following our additional services during the construction of the project. 1. Monitor site preparation. We will observe proof-rolling and provide recommendations regarding local over-excavation to remove soft, wet or organic soil; observe and approve compaction of subgrade soils. 2. Observe and approve structural fill materials and base course; observe and approve fill placement and compaction; assist contractor in achieving required compaction. 3. Monitor underground utility construction. We will observe excavation and recommend re-use of onsite soil for backfill; observe excavation subgrade and provide recommendations regarding subgrade stabilization; observe dewatering and provide recommendations when necessary; observe any potential adverse impacts on nearby structures and provide recommendations regarding mitigation; observe backfill placement and assist contractor in achieving required compaction. 4. Monitor augercast pile installation. We will observe and approve contractor’s equipment; monitor and approve each pile installed. 5. Review contractors’ submittals and RFI’s. 6. Attend construction progress meetings. 7. Prepare and distribute field reports. 8. Other geotechnical issues deemed necessary. 6.0 CLOSURE The recommendations presented in this report are provided for design purposes and are based on soil conditions disclosed by the available geotechnical boring data. Subsurface information presented herein does not constitute a direct or implied warranty that the soil conditions between exploration locations can be directly interpolated or extrapolated or that subsurface conditions and soil variations different from those disclosed by the explorations will not be revealed. The recommendations outlined in this report are based on the assumption that the development plan is consistent with the description provided in this report. If the development plan is changed or subsurface conditions different from those disclosed by the exploration are observed during construction, we should be advised at once so that we can review these conditions, and if necessary, reconsider our design recommendations. 3/3/2017 900 Oakesdale Ave SW - Google Maps https://www.google.com/maps/place/900+Oakesdale+Ave+SW,+Renton,+WA+98057/@47.4698424,-122.1884064,11.97z/data=!4m5!3m4!1s0x549042cb6cbe1215:0x144adf08666e7253!8m2!3d47.4715883!4d-122.2337654 1/2 Map data ©2017 Google 1 mi 900 Oakesdale Ave SW Figure 1 Site Location Map buffalodesign architecture | interiors1520 fourth ave suite 400 seattle wa 98101 206 467 6306 | buffalodesign.com11/30/20161" =30'-0"oaksdale ave sw0 10 20 4080160 ftremove planter & (4)trees for relocated firelaneexisting parking: 354 spacesprovided parking: 324 spacessecure yardsecure parkingfence & gate(5) secure parking spacesschematic designking county regional AFIS - site planBoring B-2Boring B-1Figure 2 - Site & Exploration PlanProposed AFIS LabExisting BuildingConnecting Corridor Figure 4 (Airport)SITE Figure 3 (Liquefaction Zone)Figure 4 Figure 5 Figure 6 Figure 7 Job No. 1701 S&EE APPENDIX A FIELD EXPLORATION, LOG, AND SOIL CLASSIFICATION CHART One soil test borings, B-1 and B-2, were performed for the project. The boring locations are shown in Figure 2. The borings were advanced using a hollow-stem auger. Soil samples were taken during the drilling of soil test borings in general accordance with ASTM D-1586, "Standard Method for Penetration Test and Split-Barrel Sampling of Soils" (1.4” I.D. sampler). The penetration test involves driving the samplers 18 inches into the ground at the bottom of the borehole with a 140 pounds hammer dropping 30 inches. The numbers of blows needed for the samplers to penetrate each 6 inches are recorded and are presented on the boring logs. The sum of the number of blows required for the second and third 6 inches of penetration is termed "standard penetration resistance" or the "N-value". In cases where 50 blows are insufficient to advance it through a 6 inches interval the penetration after 50 blows is recorded. The blow count provides an indication of the density of the subsoil, and it is used in many empirical geotechnical engineering formulae. The following table provides a general correlation of blow count with density and consistency. DENSITY (GRANULAR SOILS) CONSISTENCY (FINE-GRAINED SOILS) N-value < 4 very loose N-value < 2 very soft 5-10 loose 3-4 soft 11-30 medium dense 5-8 medium stiff 31-50 dense 9-15 stiff >50 very dense 16-30 very stiff >30 hard A chart showing the Unified Soil Classification System is included at the end of this appendix One Shelby-tube sample was retrieved from depths of 11.5 to 14 feet at Boring B-2. The sample was transported to our soil laboratory for consolidation test. The test results are included in Appendix B. After drilling, the boreholes were backfilled with bentonite chips, and the surfaces were patched with cold- mix asphalt. APPENDIX B LABORATORY TEST RESULTS Project:1701 Date Received:February 2, 2017 Project #:17T-009 Sampled By:Client Client:Soil & Environmental Engineering Date Tested:February 13, 2017 Source:Sample 1, 11.5 ft Tested By:H Benny Sample #:T17-0258 Comments: Reviewed by: Visit our website: www.mtc-inc.net Materials Testing & Consulting, Inc. Geotechnical Engineering • Special Inspection • Materials Testing • Environmental Consulting Corporate Office ~ 777 Chrysler Drive • Burlington, WA 98233 • Phone (360) 755-1990 • Fax (360) 755-1980 Regional offices in Olympia, Bellingham, and Silverdale All results apply only to actual locations and materials tested. As a mutual protection to clients, the public and ourselves, all reports are submitted as the confidential property of clients, and authorization for publication of statements, conclusions or extracts from or regarding our reports is reserved pending our written approval. Consolidation testing was performed on a GeoTac, Inc. automated consolidation test system. Preliminary data reduction is performed by the proprietary software that runs the test. Additional data reduction is performed by MTC personnel using this data. 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 10 100 1000 10000 100000 Strain - % Stress, psf Vertical Strain versus Stress Project:1701 Date Received: Project #:17T-009 Sampled By:Client Client:Soil & Environmental Engineering Date Tested:13-Feb-17 Source:Sample 1, 11.5 ft Tested By:H Benny Sample #:T17-0258 Comments: Reviewed by: Corporate Office ~ 777 Chrysler Drive • Burlington, WA 98233 • Phone (360) 755-1990 • Fax (360) 755-1980 Regional offices in Olympia, Bellingham, and Silverdale Visit our website: www.mtc-inc.net Materials Testing & Consulting, Inc. Geotechnical Engineering • Special Inspection • Materials Testing • Environmental Consulting All results apply only to actual locations and materials tested. As a mutual protection to clients, the public and ourselves, all reports are submitted as the confidential property of clients, and authorization for publication of statements, conclusions or extracts from or regarding our reports is reserved pending our written approval. Consolidation testing was performed on a GeoTac, Inc. automated consolidation test system. Preliminary data reduction is performed by the proprietary software that runs the test. Additional data reduction is performed by MTC personnel using this data. February 2, 2017 0.90 1.00 1.10 1.20 1.30 1.40 1.50 10 100 1000 10000 100000Void Ratio Stress, psf Project:1701 Date Received: Project #:17T-009 Sampled By:Client Client:Soil & Environmental Engineering Date Tested: Source:Sample 1, 11.5 ft Tested By:H Benny Sample #:T17-0258 125 0.66 1.42 3.42 0.12 250 1.64 1.38 1.00 0.39 500 2.24 1.36 1.08 0.36 1000 3.25 1.33 0.16 2.37 2000 4.83 1.29 0.61 0.60 4000 6.92 1.23 0.64 0.56 8000 9.51 1.16 0.09 3.75 16000 13.01 1.07 0.11 2.87 32000 16.90 0.96 0.10 2.83 8000 16.39 0.98 2000 15.61 1.00 500 14.76 1.02 125 14.19 1.04 Initial Final Moisture Content, %48.1 39.4 Wet Density, pcf 101.3 113.1 Dry Density, pcf 68.4 81.2 Comments: Reviewed by: Materials Testing & Consulting, Inc. Geotechnical Engineering • Special Inspection • Materials Testing • Environmental Consulting Corporate Office ~ 777 Chrysler Drive • Burlington, WA 98233 • Phone (360) 755-1990 • Fax (360) 755-1980 Regional offices in Olympia, Bellingham, and Silverdale Visit our website: www.mtc-inc.net Load, psf Strain Void Ratio t50, min Cv, ft2/day Test Summary February 2, 2017 February 13, 2017 All results apply only to actual locations and materials tested. As a mutual protection to clients, the public and ourselves, all reports are submitted as the confidential property of clients, and authorization for publication of statements, conclusions or extracts from or regarding our reports is reserved pending our written approval. Consolidation testing was performed on a GeoTac, Inc. automated consolidation test system. Preliminary data reduction is performed by the proprietary software that runs the test. Additional data reduction is performed by MTC personnel using this data.