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Home My WebLink AboutAPPROVED_117 Wells_TIR-241010©2024 D. R. STRONG Consulting Engineers Inc. BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington TECHNICAL INFORMATION REPORT For BASSANO MULTI-FAMLIY 117 Wells Ave S, Renton, Washington 08-23-24 ____________________________________________________________________________ DRS Project No. 20070 Renton File No. PR20-000331 Owner/Applicant Joe Bernasconi Windermere Real Estate PO Box 1343 Renton, WA 98056 Report Prepared by D. R. STRONG Consulting Engineers, Inc. 620 7th Avenue Kirkland, WA 98033 (425) 827-3063 Report Issue Date August 23, 2024 DEVELOPMENT ENGINEERING Michael Sippo 10/07/2024 Surface Water Enginering JFarah 10/07/2024 ©2024 D. R. STRONG Consulting Engineers Inc. BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington TECHNICAL INFORMATION REPORT BASSANO MULTI-FAMLIY TABLE OF CONTENTS SECTION I ...................................................................................................................... 1 Project Overview ......................................................................................................... 1 Predeveloped Site Conditions ..................................................................................... 1 Developed Site Conditions .......................................................................................... 1 SECTION II ................................................................................................................... 12 Conditions and Requirements Summary ................................................................... 12 Conditions of Approval............................................................................................... 15 SECTION III .................................................................................................................. 16 Off-Site Analysis ........................................................................................................ 16 Task 1: Define and Map Study Area ...................................................................... 17 Task 2: Resource Review ...................................................................................... 18 Task 3: Field Inspection ......................................................................................... 27 Task 4: Drainage System Description and Problem Descriptions .......................... 28 Task 5: Mitigation of Existing or Potential Problems .............................................. 29 SECTION IV .................................................................................................................. 34 Flow Control Analysis and Water Quality Design ...................................................... 34 Developed Site Hydrology ...................................................................................... 34 Performance Standards ............................................................................................. 36 Water Quality Treatment System ............................................................................... 37 SECTION V ................................................................................................................... 38 Conveyance System Analysis and Design ................................................................ 38 Rational Method ........................................................................................................ 39 SECTION VI .................................................................................................................. 40 Special Reports and Studies ..................................................................................... 40 SECTION VII ................................................................................................................. 41 Other Permits, Variances and Adjustments ............................................................... 41 SECTION VIII ................................................................................................................ 42 CSWPPP Analysis and Design (Part A) .................................................................... 42 SWPPP Plan Design (Part B) .................................................................................... 42 SECTION IX .................................................................................................................. 44 Bond Quantities, Facility Summaries, and Declaration of Covenant .......................... 44 SECTION X ................................................................................................................... 45 Operations and Maintenance Manual ........................................................................ 45 ©2024 D. R. STRONG Consulting Engineers Inc. BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDICES ............................................................................................................... 46 Appendix “A” Legal Description ................................................................................. 47 Appendix “B” Bond Quantity Worksheet .................................................................... 48 Appendix “C” Geotechnical Report ............................................................................ 49 List of Figures Figure 1 TIR Worksheet .................................................................................................. 3 Figure 2 Vicinity Map ....................................................................................................... 8 Figure 3 Drainage Basins, Subbasins, and Site Characteristics ..................................... 9 Figure 4 Soils ................................................................................................................ 10 Figure 5 City of Renton Topography Map ..................................................................... 19 Figure 6 City of Renton Coal Mine Hazard Areas Map.................................................. 20 Figure 7 City of Renton Flood Hazards Map ................................................................. 21 Figure 8 City of Renton Streams and Wetlands Map .................................................... 22 Figure 9 City of Renton Landslide Hazards Map ........................................................... 23 Figure 10 City of Renton Seismic Hazard Areas Map ................................................... 24 Figure 11 FEMA Map .................................................................................................... 25 Figure 12 King County iMap Drainage Complaints Map................................................ 26 Figure 13 Offsite Analysis Downstream Map ................................................................ 30 Figure 14 Offsite Analysis Downstream Table .............................................................. 31 Figure 15 Developed Area Map .................................................................................... 35 ©2024 D. R. STRONG Consulting Engineers Inc. Page 1 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION I PROJECT OVERVIEW The Project is the proposed development of the existing parcel with six multi-family units per the City of Renton (City) development process. The Project is located at 117 Wells Avenue South, Renton, Washington (Site) also known as Tax Parcel Numbers 000720- 0168 and 723150-2025. The Project will meet the drainage requirements of the 2017 King County Surface Water Design Manual (Manual), as adopted by the City. PREDEVELOPED SITE CONDITIONS The total existing Site area is approximately 6,005 s.f. (0.138 acres). The total Project area is 6,695 s.f. (0.154 acres) and includes the sidewalk area within Wells Avenue ROW to be reconstructed as a part of the new driveway cut. The current site is vacant and does not have any existing structures. A gravel parking area and small areas of lawn are the only thing present on the Site. The Site is relatively flat with a shallow grade from east to west maintaining one Threshold Discharge Area (TDA). Runoff generated from the TDA gradually sheet flows from the west to the east toward Wells Avenue S. It reaches the conveyance system in Wells Avenue S and is conveyed in a northerly direction before entering the Cedar River. DEVELOPED SITE CONDITIONS The applicant is seeking approval to develop 0.138 acres with six multi-family units (Project), All existing improvements located on the Site will be demolished or removed during Project construction. The Project is required to meet the City’s Peak Rate Flow Control Standard (Existing Conditions) and Basic Water Quality treatment. The proposed impervious surfaces consist of the roof area for the six multi-family units and small portion of uncoveded concrete patio/driveway area. The total new and replaced impervious surfaces for the Project will be 5,793 s.f. 636 s.f. of this impervious area will be replaced sidewalk within the Wells Avenue right of way. The remaining impervious area will be on-site and any non-impervious Project area will be pervious lawn. The Site is within a half mile of the 100-year flood plain for the Cedar River downstream of the Taylor Creek confluence, meaning the Project qualifies for the direct discharge exemption from providing a formal flow control facility. It is also exempt from providing a formal water quality treatment facility as only 1,901 s.f. of the proposed impervious surface is considered PGIS. This is below the 5,000 s.f. threshold for the surface area exemption from water quality mitigation, per the Manual. Per Section 1.2.9.2.1 Small Lot BMP Requirements of the Manual, projects are required to mitigate for impervious surfaces by use of Flow Control Best Management Practices (BMPs), to the maximum extent feasible. This requires all lots under 11,000 s.f. to apply flow control BMPs to mitigate impervious areas equal to 10% of the total lot area. 10% of the impervious area for this Site is 600 s.f., so flow control BMPS will be used to mitigate runoff from 600 s.f. of roof area if feasilble (See Section IV). ©2024 D. R. STRONG Consulting Engineers Inc. Page 2 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington The soil investigation summarized by the project getotechnical engineer was conducted to a depth of 31.5 feet. The report indicates the presence of overbank and channel alluvium deposits. The geotechnical engineer recommends that the on-site soils should not be used for the purposes of infiltrating stormwatwer and that alternative means of stromwater management should be used for this Project. ©2024 D. R. STRONG Consulting Engineers Inc. Page 3 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 1 TIR WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner: Joseph Bernasconi Phone: (253) 740-2119 Address: PO Box 1343 Renton, WA 98055 Project Engineer: Yoshio L. Piediscalzi, P.E. Company: D. R. STRONG Consulting Engineers Inc. Phone: (425) 827-3063 Project Name: Bassano Multi-Family City Permit#: PRE19-000224 Location: Township: 23 North Range: 5 West Section: 17 Site Address: 117 Wells Avenue S Renton, WA 98057 Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Landuse Services Subdivision / Short Subdivision / UPD Building Services: M/F / Commercial / SFR Clearing and Grading Right-of-Way Other: Civil Construction Permit DFW HPA Shoreline Mngmt COE 404 Structural DOE Dam Safety Rockery/Vault FEMA Floodplain ESA Section 7 COE Wetlands Other: Part 5 PLAN AND REPORT INFORMATION Technical Information Report Type of Drainage Review Full / Targeted / (circle): Large Site Date (include revision August 23, 2024 dates): Date of Final: Site Improvement Plan (Engr. Plans) Type (circle one): Full / Modified / : Small Site Date (include revision August 23, 2024 dates): Date of Final: Part 6 ADJUSTMENT APPROVALS Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket Description: (include conditions in TIR Section 2) _____________________________________________________________________________________ _____________________________________________________________________________________ ____________________________________________________________________________________ Date of Approval: ©2024 D. R. STRONG Consulting Engineers Inc. Page 4 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: TBD Completion Date Describe: Monitor discharge location during construction. Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: City of Renton Special District Overlays: Urban Design District A Drainage Basin: Cedar River / Lake Washington and Lower Cedar River Stormwater Requirements: Flow Control Duration Standard – Peak Flow Control Standard (Existing Conditions) and Basic WQ treatment Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/ Stream Lake Wetlands Closed Depression Floodplain Other: Zone 1 Aquifer Protection Area Steep Slope Erosion Hazard Landslide Hazard Coal Mine Hazard Seismic Hazard Habitat Protection City’s Peak Rate Flow Control Standard (Existing Conditions). Part 10 SOILS Soil Type Ur Slopes 0-8% Erosion Potential Low to Moderate High Groundwater Table Sole Source Aquifer other Seeps/Springs Additional Sheets Attached ©2024 D. R. STRONG Consulting Engineers Inc. Page 5 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core Requirement #2 – Offsite Analysis Special Requirement #6 – Aquifer Protection Additional Sheet Attached LIMITATION / SITE CONSTRAINT Infiltration is not allowed in zone 1 aquifer protection zone Part 12 TIR SUMMARY SHEET Threshold Discharge Area: Site comprised of one TDA (name or description) Core Requirements (all 8 apply) Discharge of Natural Location Yes Number of Natural Discharge Locations: 1 Offsite Analysis Level: 1 / 2 / 3 dated: 11/10/20 Flow Control Level: 1 / 2 / 3 or Exemption Number Basic (incl. facility summary sheet Small Site BMPS: Conveyance System Spill containment located at: CB 1 Erosion and Sediment Control ESC Site Supervisor: T/B/D Contact Phone: T/B/D After Hours Phone: T/B/D Maintenance and Operation Responsibility: Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Provided: Yes / No Liability Water Quality Type: Basic / Sens Lake / Enhanced Basic / Bog (include facility summary sheet) or exemption No. Landscape Management Plan: Yes / No Special Requirements (as applicable) Area Specific Drainage Type: CDA / SDO / MDP / BP / LMP / Shared / None Requirements Name: Floodplain/Floodway Delineation Type: Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: N/A Source Control Describe Landuse: Underground parking requires oil/water separation as source control Describe any structural controls: Oil Control High-use Site: Yes / No Treatment BMP: ©2024 D. R. STRONG Consulting Engineers Inc. Page 6 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington Maintenance Agreement: Yes / No with whom? Other Drainage Structures Describe: Runoff will be collected and conveyed to the existing conveyance system in Wells Avenue S. Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION Clearing Limits Cover Measures Perimeter Protection Traffic Area Stabilization Sediment Retention Surface Water Collection Dewatering Control Dust control Flow Control MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize Exposed Surfaces Remove and Restore Temporary ESC Facilities Clean and Remove All Silt and Debris, Ensure Operations of Permanent Facilities Flag Limits of SAO and open space Preservation areas Other Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch Flow Control Type/Description Water Quality Type/Description Detention Infiltration Regional Facility Shared Facility Flow Control BMPs Other Biofiltration Wetpool Media Filtration Oil Control Spill Control Flow Control BMPs Other Spill Control at CB1 ©2024 D. R. STRONG Consulting Engineers Inc. Page 7 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Covenant Tract Other: Cast in Place Vault Retaining Wall Rockery > 4’ High Structural on Steep Slope Other: Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. 08-23-24 Signed/Date ©2024 D. R. STRONG Consulting Engineers Inc. Page 8 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 2 VICINITY MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 9 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS ©2024 D. R. STRONG Consulting Engineers Inc. Page 10 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 4 SOILS ©2024 D. R. STRONG Consulting Engineers Inc. Page 11 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington King County Area, Washington UR – Urban Land Map Unit Composition • Urban land: 100 percent • Estimates are based on observations, descriptions, and transects of the map unit. Description of Urban Land Interpretive groups • Land capability classification (irrigated): None specified • Land capability classification (nonirrigated): 8 • Hydric soil rating: No ©2024 D. R. STRONG Consulting Engineers Inc. Page 12 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION II CONDITIONS AND REQUIREMENTS SUMMARY The Project must comply with the following Core and Special Requirements: • C.R. #1 – Discharge at the Natural Location: Existing drainage discharges the Site at one location, maintaining one TDA. The topography indicates that all stormwater runoff leaves the Site as sheet flow across the east property line. It enters the curb and gutter along the west side of Wells Avenue before flowing north and entering a type 1 CB approximately 30’ north of the property line. • C.R. #2 – Offsite Analysis: Analysis is included in Section III. The Analysis describes the Site’s runoff patterns in detail. • C.R. #3 – Flow Control Facilities: The Project is required to meet the City’s Peak Rate Flow Control Standard (Existing Conditions). The Site is required to “match the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10-, and 100-year return periods,” (City of Renton 2017 Surface Water Design Manual Amendment, Sec. 1.2.3.1). However, the Site is within a half mile of the 100- year flood plain for the Cedar River downstream of the Taylor Creek confluence, meaning the Project qualifies for the direct discharge exemption from providing a formal flow control facility. • C.R. #4 – Conveyance System: New pipe systems are required to be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. Pipe system structures may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a “severe flooding problem” or “severe erosion problem” as defined in C.R. #2. Any overflow occurring onsite for runoff events up to and including the 100-year event must discharge at the natural location for the project site. In residential subdivisions, such overflow must be contained within an onsite drainage easement, tract, covenant or public right-of-way. This analysis has been included in Section V of this report. • C.R. #5 – Construction Stormwater Pollution Prevention: The Project will provide the thirteen minimum ESC measures. A temporary erosion and sedimentation control plan will be prepared at the time construction plan preparation. • C.R. #6 – Maintenance and Operations: Maintenance of the proposed storm drainage facilities will be the responsibility of the City. An Operation and Maintenance Manual will be included in Section X. • C.R. #7 – Financial Guarantees and Liability: Prior to commencing construction, the Applicant must post a drainage facilities restoration and site stabilization financial guarantee. For any constructed or modified drainage facilities to be maintained and operated by the City, the Applicant must: 1) Post a drainage defect and maintenance financial guarantee for a period of two years, and 2) Maintain the drainage facilities ©2024 D. R. STRONG Consulting Engineers Inc. Page 13 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington during the two-year period following posting of the drainage defect and maintenance financial guarantee. • C.R. #8 – Water Quality Facilities: The Project is required to provide basic water quality treatment. However, the Project is only proposing 1,901 s.f. of PGIS for the concrete driveway. This is below the 5,000 s.f. threshold for formal water quality control in the Manual. This means that the Project is not required to provide a formal flow control facility. • C.R. #9 – On-Site BMPs: The Project is required to provide on-site BMPs to mitigate the impacts of storm and surface water runoff. Small lot BMPs were determined by the BMP requirements outlined in Section 1.2.9.2.1 of the CORSWDM. As required by the CORSWDM, small lot BMP requirements were analyzed in the order of preference listed in section 1.2.9.2.1. 1. Full Dispersion: There is an insufficient amount of native growth in order to utilize full dispersion. The lack of required undisturbed area and flowpath lengths means that full dispersion is infeasible for this Lot. 2. Full Infiltration: Per the geotechnical report, the existing soil on the Site is fine graded soils with high levels of silt to deaths of approximately eight feet. This means that infiltration applications are infeasible. The full geotechnical report is included with this application. 3. Limited Infiltration: Per the geotechnical report, the existing soil on the Site is fine graded soils with high levels of silt to deaths of approximately eight feet. This means that infiltration applications are infeasible. The full geotechnical report is included with this application. 4. Rain Gardens: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. The full geotechnical report has been included in conjunction with the preliminary application. 5. Bioretention: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. 6. Permeable Pavement: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. 7. Basic Dispersion: Due to the amount of impervious surface proposed for this Project, there is no pervious area available for a flowpath that will meet the requirements of the manual for basic dispersion. 8. Soil Amendment: Soil amendment will be provided for all landscaped areas. Per the CORSWDM, a perforated stub out connection is required for a project that proposes the connection of roof downspouts to the local drainage system. However, a perforated pipe connection cannot be provided for this Project because the Site is within Zone 1 APA which does not allow for infiltration and due to the amount of impervious area being added to the Site which eliminates any feasible location for a perforated stub out. • S.R. #1 – Other Adopted Area-Specific Requirements: Not applicable for this Project. • S.R. #2 – Floodplain/Floodway Delineation: Not applicable for this Project. • S.R. #3 – Flood Protection Facilities: Not applicable for this Project. ©2024 D. R. STRONG Consulting Engineers Inc. Page 14 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington • S.R. #4 – Source Control: Source control required at CB 1. • S.R. #5 – Oil Control: Not applicable for this Project. S.R. #6 – Aquifer Protection Area: The Site is located within the Aquifer Protection Zone 1. No infiltration is proposed as a part of this Project, and therefore the Project does not need to meet the requirements in the Manual for zone 1. ©2024 D. R. STRONG Consulting Engineers Inc. Page 15 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington CONDITIONS OF APPROVAL RenFour Multi-Family PR20-000331 TBD ©2024 D. R. STRONG Consulting Engineers Inc. Page 16 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION III OFF-SITE ANALYSIS A Level One Downstream Analysis was prepared by D.R. Strong Consulting Engineers and is included in this Section. ©2024 D. R. STRONG Consulting Engineers Inc. Page 17 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington LEVEL ONE DOWNSTREAM ANALYSIS TASK 1: DEFINE AND MAP STUDY AREA This Offsite Analysis was prepared in accordance with Core Requirement #2, Section 1.2.2 of the 2017 King County Surface Water Design Manual and City Amendments as adopted by the City of Renton (Manual). The Site is located at 117 Wells Ave S, Renton, Washington. The Project is the development of one parcel with six townhouse units. See Figures 1, 2, 3, and 5 for maps of the study area. ©2024 D. R. STRONG Consulting Engineers Inc. Page 18 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington TASK 2: RESOURCE REVIEW • Adopted Basin Plans: King County Department of Permitting and Environmental Review (DPER) and Department of Natural Resources and Parks (DNRP) Lower Cedar River Basin Plan Summary • Finalized Drainage Studies: No available applicable drainage studies at this time. • Basin Reconnaissance Summary Reports: Cedar River Current and Future Conditions Report (April 1993). • Comprehensive Plans: Renton’s Comprehensive Plan, adopted on June 22, 2015, effective July 1, 2015. • Floodplain/Floodway (FEMA) Map: No floodplains exist on site, See Figure 10. • Other Offsite Analysis Reports: N/A • Sensitive Areas Map Folios: See Figures 6-9. • DNRP Drainage Complaints and Studies: Per King County Water and Land Resources Division, there were no complaints within the downstream paths, within approximately one mile from the Site within the last 10 years. See Figure 11. • USDA King County Soils Survey: See Figure 4 • Wetlands Inventory: Vol. 2 East (1990) – No wetlands identified along the downstream paths in the KC Wetlands Inventory. The City of Renton Mapping Applications indicates there are also no wetlands along the downstream path. See Figure 8. • Migrating River Studies: The Site is not located near the channel migration zones of Cedar River, Tolt River, Raging River, Snoqualmie River, or Green River. • King County Designated Water Quality Problems: Per the Washington State Water Quality Assessment 303(d)/305(b) Integrated Report current as of 2012, the reach of the Cedar River will outlet to has three category 5 listings, one category 2 listing, and three category 5 listings. ©2024 D. R. STRONG Consulting Engineers Inc. Page 19 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 5 CITY OF RENTON TOPOGRAPHY MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 20 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 6 CITY OF RENTON COAL MINE HAZARD AREAS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 21 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 7 CITY OF RENTON FLOOD HAZARDS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 22 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 8 CITY OF RENTON STREAMS AND WETLANDS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 23 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 9 CITY OF RENTON LANDSLIDE HAZARDS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 24 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 10 CITY OF RENTON SEISMIC HAZARD AREAS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 25 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 11 FEMA MAP Site (Approximate) ©2024 D. R. STRONG Consulting Engineers Inc. Page 26 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 12 KING COUNTY IMAP DRAINAGE COMPLAINTS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 27 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington TASK 3: FIELD INSPECTION UPSTREAM TRIBUTARY AREA Upon evaluation of the upstream area through examining COR topographic map (see Figure 5) and by conducting field reconnaissance on November 9, 2020, the upstream tributary area for the Site is considered negligible. The area generally slopes from the southeast property corner to the northwest property corner. Runoff from the property to the south appears to follow the same flowpath direction as the on-site runoff. Runoff from the right of way (Wells Ave S) to the east and the property to the north heads in a northerly direction away from the Site. GENERAL ONSITE AND OFFSITE DRAINAGE DESCRIPTIONS The Site consists of one Natural Discharge Area (NDA 1) with one Natural Discharge Location (NDL 1) and contained within one Threshold Discharge Area (TDA 1). Runoff from the Site leaves at the northwest property corner and sheet flows along the fence line of the adjacent property to the north before reaching the conveyance system in Williams Ave S. The runoff continues north via the existing conveyance system before outfalling to the Cedar River and continuing northwest before entering Lake Washington roughly 1 ½ miles from the Site. Runoff from the frontage was also considered and is contained within one NDA. The runoff leaves along the eastern property line and sheet flows along the driveway to the curb line where it starts heading north. It eventually enters the conveyance system in Wells Ave S that conveys the runoff northwest to Cedar River where it outlets and continues its path to Lake Washington. The downstream path of the runoff from the frontage NDA meets up with the downstream path from the on-site NDA within a ¼ mile of leaving the Site meaning that the Project is made up of a single Threshold Discharge Area. ©2024 D. R. STRONG Consulting Engineers Inc. Page 28 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington TASK 4: DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS DRAINAGE SYSTEM DESCRIPTION The downstream analysis is further illustrated and detailed in the Downstream Map Figure 12 and Downstream Table Figure 13. The drainage area is located within the Lower Cedar River. The drainage area was evaluated by reviewing available resources described in Task 2, and by conducting a field reconnaissance on November 9, 2020 under rainy conditions. ON-SITE DOWNSTREAM PATH Runoff leaves the Site as sheet flow across the western property line. Runoff continues west as sheet flow over the adjacent parcel to the west of the Site before reaching the curb and gutter along the east side of Williams Ave S. It briefly flows north as curb and gutter flow before entering a Type 2 CB on the east side of Williams Ave S. It is conveyed north through a series of pipes and Type 2-CBs before outfalling to the Cedar River and then entering Lake Washington roughly a mile from the outfall. FRONTAGE DOWNSTREAM PATH Runoff from the Site frontage sheet flows to the east before reaching the curb and gutter along the west side of Wells Ave S. From there it flows north as curb and gutter flow before reaching a Type 1-CB on the west side of Wells Ave S. The runoff is piped east to a Type 2-CB followed by conveyance north through two more Type 2-CBs before runoff is then discharged into Cedar River and continues northwesterly to Lake Washington. ©2024 D. R. STRONG Consulting Engineers Inc. Page 29 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington TASK 5: MITIGATION OF EXISTING OR POTENTIAL PROBLEMS A review of the King County Water and Land Resource Division – Drainage Services Section Documented Drainage Complaints revealed no drainage complaints within one mile of the downstream flow paths within the past ten years. The Project is required to meet the City’s Peak Rate Flow Control Standard (Existing Conditions) and Basic Water Quality treatment, per the Manual. During construction, standard sediment and erosion control methods will be utilized. This will include the use of a stabilized construction entrance, perimeter silt fencing, and other necessary measures to minimize soil erosion during construction. ©2024 D. R. STRONG Consulting Engineers Inc. Page 30 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 13 OFFSITE ANALYSIS DOWNSTREAM MAP Site A1 C1 F1 E1 H F G I A B1 D1 G1 B C D E ©2024 D. R. STRONG Consulting Engineers Inc. Page 31 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 14 OFFSITE ANALYSIS DOWNSTREAM TABLE EXISTING DOWNSTREAM PATH Symbol Drainage Component Type, Name, and Size Drainage Component Description Slope Distance From site Discharge Existing Problems Potential Problems Observations of field inspector resource reviewer, or resident See map Type: sheet flow, swale, Stream, channel, pipe, Pond; Size: diameter Surface area drainage basin, vegetation, cover, depth, type of sensitive area, volume % 1/4 mile = 1,320 feet Constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion Tributary area, likelihood of problem, overflow pathways, potential impacts. A Natural discharge area Runoff exits at the NDA as sheet flow over the western property line of the Site 0’ None Observed None Anticipated No flow observed A-B Westerly Sheet Flow Runoff sheet flows across adjacent parcel to the west None Observed None Anticipated No flow observed B Curb and Gutter Runoff enters curb and gutter on east side of Williams Ave S 125’ None Observed None Anticipated No flow observed B-C Northerly Curb and Gutter Flow Runoff sheet flows along flow line of city curb None Observed None Observed No flow observed C Type 1-CB Located on the east side of Williams Ave S ±135’ None Observed None Anticipated No flow observed C-D Westerly pipe flow 6” concrete pipe None Observed None Anticipated No flow observed D Type 2-CB Located on the east side of Williams Ave S ±141’ None Observed None Anticipated No flow observed D-E Northerly pipe flow 8” concrete pipe None Observed None Anticipated No flow observed E Type 2-CB Located on the east side of Williams Ave S ±292’ None Observed None Anticipated No flow observed E-F Northerly pipe flow 8” concrete pipe None Observed None Anticipated No flow observed F Type 2-CB Located on the east side of Williams Ave S ±443’ None Observed None Anticipated No flow observed F-G Northerly pipe flow 8” concrete pipe None Observed None Anticipated No flow observed ©2024 D. R. STRONG Consulting Engineers Inc. Page 32 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FRONTAGE DOWNSTREAM PATH G Type 2-CB Located on the east side of Williams Ave S ±801’ None Observed None Anticipated No flow observed G-H Northwesterly pipe flow 8” concrete pipe None Observed None Anticipated No flow observed H Type 2-CB Located on the east side of Williams Ave S ±852’ None Observed None Anticipated No flow observed H-I Northerly pipe flow 12” concrete pipe None Observed None Anticipated No flow observed I Outfall to Cedar River COR Facility ID No. OUT-0335 ±942’ None Observed None Anticipated No flow observed Symbol Drainage Component Type, Name, and Size Drainage Component Description Slope Distance From site Discharge Existing Problems Potential Problems Observations of field inspector resource reviewer, or resident See map Type: sheet flow, swale, Stream, channel, pipe, Pond; Size: diameter Surface area drainage basin, vegetation, cover, depth, type of sensitive area, volume % 1/4 mile = 1,320 feet Constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion Tributary area, likelihood of problem, overflow pathways, potential impacts. A1 Natural discharge area Runoff exits at the NDA as sheet flow on the eastern property line of the Site 0’ None Observed None Anticipated No flow observed A1-B1 Easterly Sheet Flow Runoff sheet flows down driveway along frontage None Observed None Anticipated No flow observed B1 Curb and Gutter Runoff enters curb and gutter on west side of Wells Ave S 15’ None Observed None Anticipated No flow observed B1-C1 Northerly Curb and Gutter Flow Runoff sheet flows along flow line of city curb None Observed None Anticipated No flow observed C1 Type-1 CB Located on the west side of Wells Ave S ±69’ None Observed None Observed No flow observed C1-D1 Easterly Pipe Flow 8” concrete pipe None Observed None Anticipated No flow observed D1 Type-2 CB Located on the east side of Wells Ave S ±103’ None Observed None Anticipated No flow observed D1-E1 Northerly Pipe Flow 12” concrete pipe None Observed None Anticipated No flow observed ©2024 D. R. STRONG Consulting Engineers Inc. Page 33 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington E1 Type-2 CB Located on the east side of Wells Ave S ±396’ None Observed None Anticipated No flow observed E1-F1 Northerly Pipe Flow 12” concrete pipe None Observed None Anticipated No flow observed F1 Type-2 CB Located on the east side of Wells Ave S ±513’ None Observed None Anticipated No flow observed F1-G1 Northeasterly Pipe Flow 12” concrete pipe None Observed None Anticipated No flow observed G1 Outfall to Cedar River COR Facility ID No. OUT-0319 ±559’ None Observed None Anticipated No flow observed G1-I Northwesterly Open Channel Flow Open channel flow in Cedar River before reaching outfall location from on-site NDA None Observed None Anticipated No flow observed I Outfall to Cedar River COR Facility ID No. OUT-0335 ±1,052’ None Observed None Anticipated No flow observed ©2024 D. R. STRONG Consulting Engineers Inc. Page 34 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION IV FLOW CONTROL ANALYSIS AND WATER QUALITY DESIGN DEVELOPED SITE HYDROLOGY Per the geotechnical report, soils present on-site is holocene alluvium which is considered an outwash soil. The total new and replaced impervious surface area for the Project is 5,793 s.f. 636 s.f. of that impervious area is replaced sidewalk area along the Wells Avenue frontage for the construction of the new driveway cut. The remianing Project impervious area is all new surfaces being added on-site. Of the 5,157 s.f. of impervious surface being added to the Site, 4,903 s.f. is roof area. The remaining of the on-site impervious area consists of 198 s.f. of uncovered driveway/sidewalk area and 56 s.f. of uncovered patio area. The uncovered and covered driveway area totals 1,901 s.f. which makes up all of the proposed PGIS for the Project. The remainder of the Site will be lawn area. The developed map below illustrates the area breakdown for the Project. ©2024 D. R. STRONG Consulting Engineers Inc. Page 35 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 15 DEVELOPED AREA MAP ©2024 D. R. STRONG Consulting Engineers Inc. Page 36 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington PERFORMANCE STANDARDS The Project is required to meet the City’s Peak Rate Flow Control Standard (Existing Conditions). The Site is required to “match the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10-, and 100-year return periods,” (City of Renton 2017 Surface Water Design Manual Amendment, Sec. 1.2.3.1). However, the Site is within a half mile of the 100-year flood plain for the Cedar River downstream of the Taylor Creek confluence, meaning the Project qualifies for the direct discharge exemption from providing a formal flow control facility. Per Section 1.2.9.2.1 Small Lot BMP Requirements of the Manual, projects are required to mitigate for impervious surfaces by use of Flow Control Best Management Practices (BMPs), to the maximum extent feasible. This requires all lots under 11,000 s.f. to apply flow control BMPs to mitigate impervious areas equal to 10% of the total lot area. 10% of the impervious area for this Site is 600 s.f., so flow control BMPS will be used to mitigate runoff from 600 s.f. of roof area if feasilble. Small lot BMPs were determined by the BMP requirements outlined in Section 1.2.9.2.1 of the CORSWDM. As required by the CORSWDM, small lot BMP requirements were analyzed in the order of preference listed in section 1.2.9.2.1. 1. Full Dispersion: There is an insufficient amount of native growth in order to utilize full dispersion. The lack of required undisturbed area and flowpath lengths means that full dispersion is infeasible for this Lot. 2. Full Infiltration: Per the geotechnical report, the existing soil on the Site is fine graded soils with high levels of silt to deaths of approximately eight feet. This means that infiltration applications are infeasible. The full geotechnical report is included with this application. 3. Limited Infiltration: Per the geotechnical report, the existing soil on the Site is fine graded soils with high levels of silt to deaths of approximately eight feet. This means that infiltration applications are infeasible. The full geotechnical report is included with this application. 4. Rain Gardens: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. The full geotechnical report has been included in conjunction with the preliminary application. 5. Bioretention: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. 6. Permeable Pavement: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. 7. Basic Dispersion: Due to the amount of impervious surface proposed for this Project, there is no pervious area available for a flowpath that will meet the requirements of the manual for basic dispersion. 8. Soil Amendment: Soil amendment will be provided for all landscaped areas. Per the CORSWDM, a perforated stub out connection is required for a project that proposes the connection of roof downspouts to the local drainage system. However, a perforated pipe connection cannot be provided for this Project because the Site is within Zone 1 APA which does not allow for infiltration and due to the amount of impervious area being added to the Site which eliminates any feasible location for a perforated stub out. ©2024 D. R. STRONG Consulting Engineers Inc. Page 37 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington WATER QUALITY TREATMENT SYSTEM The Project is required to adhere to the City of Renton’s basic water quality treatment criteria. However, the Project is only proposing 1,901 s.f. of PGIS for the concrete driveway. This is below the 5,000 s.f. threshold for formal water quality control in the Manual. This means that the Project is not required to provide a formal flow control facility. ©2024 D. R. STRONG Consulting Engineers Inc. Page 38 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION V CONVEYANCE SYSTEM ANALYSIS AND DESIGN Per Core Requirement #4 of the CORSWDM, the conveyance system must be analyzed and designed for the existing tributary and developed onsite runoff. Pipe systems shall be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow with a minimum of 6 inches of freeboard between the design water surface and structure grate. Pipe system structures may overtop for runoff events that exceed the 25-year design capacity provided the overflow from a 100-year runoff event does not create or aggravate a “severe flooding problem” or “severe erosion problem” as defined in C.R. #2. The Rational Method is used to calculate the 100-year peak flow for the Site. A conveyance system consisting of pipes and catch basins has been designed for the Project. Onsite runoff from all target surfaces is collected by the on-site catch basin or roof drains and conveyed to the existing conveyance system in Wells Avenue S. Pipes are 12” diameter PVC material with a minimum slope of 1.13%. Per the rational method (below), the 100-year flow for the Site under proposed conditions is approximately 0.36 cfs. Manning’s equation was used to estimate the capacity of the most limiting pipe in the conveyance system, which is a 12 PVC pipe at 1.13%. This pipe, and therefore the conveyance system, is capable of conveying 4.49 cfs. This conveyance system is adequately sized to handle the 100-year peak flow. ©2024 D. R. STRONG Consulting Engineers Inc. Page 39 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington RATIONAL METHOD Table 3.2.1.B Coefficients for the Rational Method "iR" Equation 100 year 50 year 25 year 10 year 5 year 2 year aR 2.61 2.75 2.66 2.44 2.33 1.58 bR 0.63 0.65 0.65 0.64 0.63 0.58 Table 3.2.1.A Runoff Coefficients Land Cover C Dense Forest 0.10 Light Forest 0.15 Pasture 0.20 Lawns 0.25 Playgrounds 0.30 Gravel Areas 0.80 Pavement & Roofs 0.90 Open Water 1.00 ©2024 D. R. STRONG Consulting Engineers Inc. Page 40 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION VI SPECIAL REPORTS AND STUDIES The following report and studies have been provided with this submittal. Geotechnical Engineering Study: Associated Earth Sciences, Inc. – August 13, 2020 ©2024 D. R. STRONG Consulting Engineers Inc. Page 41 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION VII OTHER PERMITS, VARIANCES AND ADJUSTMENTS None at this time. ©2024 D. R. STRONG Consulting Engineers Inc. Page 42 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION VIII CSWPPP ANALYSIS AND DESIGN (PART A) The Erosion and Sedimentation Control Design will meet the seven minimum King County requirements: 1. Areas to remain undisturbed shall be delineated with a high visibility plastic fence prior to any site clearing or grading. 2. Site disturbed areas shall be covered with mulch and seeded, as appropriate, for temporary or permanent measures. 3. Perimeter protection shall consist of a silt fence down slope of any disturbed areas or stockpiles. 4. The existing concrete driveway at the point of ingress/egress to the Site will be used as the stabilized construction entrance. 5. Perimeter silt fences downslope will provide sediment retention for the Site. 6. Surface water from disturbed areas will sheet flow to the silt fences. 7. Dust control shall be provided by spraying exposed soils with water until wet. This is required when exposed soils are dry to the point that wind transport is possible which would affect roadways, drainage ways, surface waters, or neighboring residences. SWPPP PLAN DESIGN (PART B) Construction activities that could contribute pollutants to surface and storm water include the following, with applicable BMP’s listed for each item: 1. Storage and use of chemicals: Utilize source control, and soil erosion and sedimentation control practices, such as using only recommended amounts of chemical materials applied in the proper manner; neutralizing concrete wash water, and disposing of excess concrete material only in areas prepared for concrete placement, or return to batch plant; disposing of wash-up waters from water-based paints in sanitary sewer; disposing of wastes from oil-based paints, solvents, thinners, and mineral spirits only through a licensed waste management firm, or treatment, storage, and disposal (TSD) facility. 2. Material delivery and storage: Locate temporary storage areas away from vehicular traffic, near the construction entrance, and away from storm drains. Material Safety Data Sheets (MSDS) should be supplied for all materials stored, and chemicals kept in their original labeled containers. Maintenance, fueling, and repair of heavy equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident. Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other potentially hazardous materials. 3. Building demolition: Protect stormwater drainage system from sediment-laden runoff and loose particles. To the extent possible, use dikes, berms, or other ©2024 D. R. STRONG Consulting Engineers Inc. Page 43 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington methods to protect overland discharge paths from runoff. Street gutter, sidewalks, driveways, and other paved surfaces in the immediate area of demolition must be swept daily to collect and properly dispose of loose debris and garbage. Spray the minimum amount of water to help control windblown fine particles such as concrete, dust, and paint chips. Avoid excessive spraying so that runoff from the site does not occur, yet dust control is achieved. Oils must never be used for dust control. 4. Sawcutting: Slurry and cuttings shall be vacuumed during the activity to prevent migration offsite and must not remain on permanent concrete or asphalt paving overnight. Collected slurry and cuttings shall be disposed of in a manner that does not violate ground water or surface water quality standards. ©2024 D. R. STRONG Consulting Engineers Inc. Page 44 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION IX BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 1. Bond Quantity Worksheet is included as Appendix B of this report. ©2024 D. R. STRONG Consulting Engineers Inc. Page 45 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION X OPERATIONS AND MAINTENANCE MANUAL The maintenance of the private catch basin on-site will be the responsibility of the owners. Maintenance guidelines set forth in the 2017 CORSWDM have been included in this Section. ©2024 D. R. STRONG Consulting Engineers Inc. Page 46 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDICES ©2024 D. R. STRONG Consulting Engineers Inc. Page 47 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDIX “A” LEGAL DESCRIPTION THE LAND REFERRED TO HEREIN BELOW IS SITUATED IN THE COUNTY OF KING, STATE OF WA, AND IS DESCRIBED AS FOLLOWS: THAT PORTION OF BLOCK 23, TOWN OF RENTON, ACCORDING TO THE PLAT RECORDED IN VOLUME 1 OF PLATS, PAGE 135, IN KING COUNTY, WASHINGTON; AND AN UNPLATTED TRACT ADJOINING, LYING BETWEEN THE WEST LINE OF LOT 15 AND THE EAST LINE OF SAID BLOCK 23 AND THE PRODUCTION OF SAID LINE BETWEEN LINES PARALLEL WITH AND RESPECTIVELY 250 FEET AND 300 FEET NORTH OF THE SOUTH LINE OF SAID BLOCK 23; (BEING KNOWN AS LOT 15 OF THE UNRECORDED SUPPLEMENTAL PLAT OF BLOCK 23 OF THE TOWN OF RENTON). 723150202502 AND 000720016807 VACANT LAND RENTON, WASHINGTON 98057 ©2024 D. R. STRONG Consulting Engineers Inc. Page 48 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDIX “B” BOND QUANTITY WORKSHEET ©2024 D. R. STRONG Consulting Engineers Inc. Page 49 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDIX “C” GEOTECHNICAL REPORT ©2024 D. R. STRONG Consulting Engineers Inc. Page 8 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 2 VICINITY MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 9 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS 0GRAPHIC SCALE10'20'40'1 INCH = 20 FT. ©2024 D. R. STRONG Consulting Engineers Inc. Page 10 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 4 SOILS ©2024 D. R. STRONG Consulting Engineers Inc. Page 11 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington King County Area, Washington UR – Urban Land Map Unit Composition • Urban land: 100 percent • Estimates are based on observations, descriptions, and transects of the map unit. Description of Urban Land Interpretive groups • Land capability classification (irrigated): None specified • Land capability classification (nonirrigated): 8 • Hydric soil rating: No ©2024 D. R. STRONG Consulting Engineers Inc. Page 12 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION II CONDITIONS AND REQUIREMENTS SUMMARY The Project must comply with the following Core and Special Requirements: • C.R. #1 – Discharge at the Natural Location: Existing drainage discharges the Site at one location, maintaining one TDA. The topography indicates that all stormwater runoff leaves the Site as sheet flow across the east property line. It enters the curb and gutter along the west side of Wells Avenue before flowing north and entering a type 1 CB approximately 30’ north of the property line. • C.R. #2 – Offsite Analysis: Analysis is included in Section III. The Analysis describes the Site’s runoff patterns in detail. • C.R. #3 – Flow Control Facilities: The Project is required to meet the City’s Peak Rate Flow Control Standard (Existing Conditions). The Site is required to “match the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10-, and 100-year return periods,” (City of Renton 2017 Surface Water Design Manual Amendment, Sec. 1.2.3.1). However, the Site is within a half mile of the 100- year flood plain for the Cedar River downstream of the Taylor Creek confluence, meaning the Project qualifies for the direct discharge exemption from providing a formal flow control facility. • C.R. #4 – Conveyance System: New pipe systems are required to be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. Pipe system structures may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a “severe flooding problem” or “severe erosion problem” as defined in C.R. #2. Any overflow occurring onsite for runoff events up to and including the 100-year event must discharge at the natural location for the project site. In residential subdivisions, such overflow must be contained within an onsite drainage easement, tract, covenant or public right-of-way. This analysis has been included in Section V of this report. • C.R. #5 – Construction Stormwater Pollution Prevention: The Project will provide the thirteen minimum ESC measures. A temporary erosion and sedimentation control plan will be prepared at the time construction plan preparation. • C.R. #6 – Maintenance and Operations: Maintenance of the proposed storm drainage facilities will be the responsibility of the City. An Operation and Maintenance Manual will be included in Section X. • C.R. #7 – Financial Guarantees and Liability: Prior to commencing construction, the Applicant must post a drainage facilities restoration and site stabilization financial guarantee. For any constructed or modified drainage facilities to be maintained and operated by the City, the Applicant must: 1) Post a drainage defect and maintenance financial guarantee for a period of two years, and 2) Maintain the drainage facilities ©2024 D. R. STRONG Consulting Engineers Inc. Page 13 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington during the two-year period following posting of the drainage defect and maintenance financial guarantee. • C.R. #8 – Water Quality Facilities: The Project is required to provide basic water quality treatment. However, the Project is only proposing 1,901 s.f. of PGIS for the concrete driveway. This is below the 5,000 s.f. threshold for formal water quality control in the Manual. This means that the Project is not required to provide a formal flow control facility. • C.R. #9 – On-Site BMPs: The Project is required to provide on-site BMPs to mitigate the impacts of storm and surface water runoff. Small lot BMPs were determined by the BMP requirements outlined in Section 1.2.9.2.1 of the CORSWDM. As required by the CORSWDM, small lot BMP requirements were analyzed in the order of preference listed in section 1.2.9.2.1. 1. Full Dispersion: There is an insufficient amount of native growth in order to utilize full dispersion. The lack of required undisturbed area and flowpath lengths means that full dispersion is infeasible for this Lot. 2. Full Infiltration: Per the geotechnical report, the existing soil on the Site is fine graded soils with high levels of silt to deaths of approximately eight feet. This means that infiltration applications are infeasible. The full geotechnical report is included with this application. 3. Limited Infiltration: Per the geotechnical report, the existing soil on the Site is fine graded soils with high levels of silt to deaths of approximately eight feet. This means that infiltration applications are infeasible. The full geotechnical report is included with this application. 4. Rain Gardens: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. The full geotechnical report has been included in conjunction with the preliminary application. 5. Bioretention: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. 6. Permeable Pavement: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. 7. Basic Dispersion: Due to the amount of impervious surface proposed for this Project, there is no pervious area available for a flowpath that will meet the requirements of the manual for basic dispersion. 8. Soil Amendment: Soil amendment will be provided for all landscaped areas. Per the CORSWDM, a perforated stub out connection is required for a project that proposes the connection of roof downspouts to the local drainage system. However, a perforated pipe connection cannot be provided for this Project because the Site is within Zone 1 APA which does not allow for infiltration and due to the amount of impervious area being added to the Site which eliminates any feasible location for a perforated stub out. • S.R. #1 – Other Adopted Area-Specific Requirements: Not applicable for this Project. • S.R. #2 – Floodplain/Floodway Delineation: Not applicable for this Project. • S.R. #3 – Flood Protection Facilities: Not applicable for this Project. ©2024 D. R. STRONG Consulting Engineers Inc. Page 14 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington • S.R. #4 – Source Control: Source control required at CB 1. • S.R. #5 – Oil Control: Not applicable for this Project. S.R. #6 – Aquifer Protection Area: The Site is located within the Aquifer Protection Zone 1. No infiltration is proposed as a part of this Project, and therefore the Project does not need to meet the requirements in the Manual for zone 1. ©2024 D. R. STRONG Consulting Engineers Inc. Page 15 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington CONDITIONS OF APPROVAL RenFour Multi-Family PR20-000331 TBD ©2024 D. R. STRONG Consulting Engineers Inc. Page 16 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION III OFF-SITE ANALYSIS A Level One Downstream Analysis was prepared by D.R. Strong Consulting Engineers and is included in this Section. ©2024 D. R. STRONG Consulting Engineers Inc. Page 17 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington LEVEL ONE DOWNSTREAM ANALYSIS TASK 1: DEFINE AND MAP STUDY AREA This Offsite Analysis was prepared in accordance with Core Requirement #2, Section 1.2.2 of the 2017 King County Surface Water Design Manual and City Amendments as adopted by the City of Renton (Manual). The Site is located at 117 Wells Ave S, Renton, Washington. The Project is the development of one parcel with six townhouse units. See Figures 1, 2, 3, and 5 for maps of the study area. ©2024 D. R. STRONG Consulting Engineers Inc. Page 18 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington TASK 2: RESOURCE REVIEW • Adopted Basin Plans: King County Department of Permitting and Environmental Review (DPER) and Department of Natural Resources and Parks (DNRP) Lower Cedar River Basin Plan Summary • Finalized Drainage Studies: No available applicable drainage studies at this time. • Basin Reconnaissance Summary Reports: Cedar River Current and Future Conditions Report (April 1993). • Comprehensive Plans: Renton’s Comprehensive Plan, adopted on June 22, 2015, effective July 1, 2015. • Floodplain/Floodway (FEMA) Map: No floodplains exist on site, See Figure 10. • Other Offsite Analysis Reports: N/A • Sensitive Areas Map Folios: See Figures 6-9. • DNRP Drainage Complaints and Studies: Per King County Water and Land Resources Division, there were no complaints within the downstream paths, within approximately one mile from the Site within the last 10 years. See Figure 11. • USDA King County Soils Survey: See Figure 4 • Wetlands Inventory: Vol. 2 East (1990) – No wetlands identified along the downstream paths in the KC Wetlands Inventory. The City of Renton Mapping Applications indicates there are also no wetlands along the downstream path. See Figure 8. • Migrating River Studies: The Site is not located near the channel migration zones of Cedar River, Tolt River, Raging River, Snoqualmie River, or Green River. • King County Designated Water Quality Problems: Per the Washington State Water Quality Assessment 303(d)/305(b) Integrated Report current as of 2012, the reach of the Cedar River will outlet to has three category 5 listings, one category 2 listing, and three category 5 listings. ©2024 D. R. STRONG Consulting Engineers Inc. Page 19 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 5 CITY OF RENTON TOPOGRAPHY MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 20 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 6 CITY OF RENTON COAL MINE HAZARD AREAS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 21 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 7 CITY OF RENTON FLOOD HAZARDS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 22 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 8 CITY OF RENTON STREAMS AND WETLANDS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 23 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 9 CITY OF RENTON LANDSLIDE HAZARDS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 24 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 10 CITY OF RENTON SEISMIC HAZARD AREAS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 25 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 11 FEMA MAP Site (Approximate) ©2024 D. R. STRONG Consulting Engineers Inc. Page 26 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 12 KING COUNTY IMAP DRAINAGE COMPLAINTS MAP Site ©2024 D. R. STRONG Consulting Engineers Inc. Page 27 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington TASK 3: FIELD INSPECTION UPSTREAM TRIBUTARY AREA Upon evaluation of the upstream area through examining COR topographic map (see Figure 5) and by conducting field reconnaissance on November 9, 2020, the upstream tributary area for the Site is considered negligible. The area generally slopes from the southeast property corner to the northwest property corner. Runoff from the property to the south appears to follow the same flowpath direction as the on-site runoff. Runoff from the right of way (Wells Ave S) to the east and the property to the north heads in a northerly direction away from the Site. GENERAL ONSITE AND OFFSITE DRAINAGE DESCRIPTIONS The Site consists of one Natural Discharge Area (NDA 1) with one Natural Discharge Location (NDL 1) and contained within one Threshold Discharge Area (TDA 1). Runoff from the Site leaves at the northwest property corner and sheet flows along the fence line of the adjacent property to the north before reaching the conveyance system in Williams Ave S. The runoff continues north via the existing conveyance system before outfalling to the Cedar River and continuing northwest before entering Lake Washington roughly 1 ½ miles from the Site. Runoff from the frontage was also considered and is contained within one NDA. The runoff leaves along the eastern property line and sheet flows along the driveway to the curb line where it starts heading north. It eventually enters the conveyance system in Wells Ave S that conveys the runoff northwest to Cedar River where it outlets and continues its path to Lake Washington. The downstream path of the runoff from the frontage NDA meets up with the downstream path from the on-site NDA within a ¼ mile of leaving the Site meaning that the Project is made up of a single Threshold Discharge Area. ©2024 D. R. STRONG Consulting Engineers Inc. Page 28 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington TASK 4: DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS DRAINAGE SYSTEM DESCRIPTION The downstream analysis is further illustrated and detailed in the Downstream Map Figure 12 and Downstream Table Figure 13. The drainage area is located within the Lower Cedar River. The drainage area was evaluated by reviewing available resources described in Task 2, and by conducting a field reconnaissance on November 9, 2020 under rainy conditions. ON-SITE DOWNSTREAM PATH Runoff leaves the Site as sheet flow across the western property line. Runoff continues west as sheet flow over the adjacent parcel to the west of the Site before reaching the curb and gutter along the east side of Williams Ave S. It briefly flows north as curb and gutter flow before entering a Type 2 CB on the east side of Williams Ave S. It is conveyed north through a series of pipes and Type 2-CBs before outfalling to the Cedar River and then entering Lake Washington roughly a mile from the outfall. FRONTAGE DOWNSTREAM PATH Runoff from the Site frontage sheet flows to the east before reaching the curb and gutter along the west side of Wells Ave S. From there it flows north as curb and gutter flow before reaching a Type 1-CB on the west side of Wells Ave S. The runoff is piped east to a Type 2-CB followed by conveyance north through two more Type 2-CBs before runoff is then discharged into Cedar River and continues northwesterly to Lake Washington. ©2024 D. R. STRONG Consulting Engineers Inc. Page 29 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington TASK 5: MITIGATION OF EXISTING OR POTENTIAL PROBLEMS A review of the King County Water and Land Resource Division – Drainage Services Section Documented Drainage Complaints revealed no drainage complaints within one mile of the downstream flow paths within the past ten years. The Project is required to meet the City’s Peak Rate Flow Control Standard (Existing Conditions) and Basic Water Quality treatment, per the Manual. During construction, standard sediment and erosion control methods will be utilized. This will include the use of a stabilized construction entrance, perimeter silt fencing, and other necessary measures to minimize soil erosion during construction. ©2024 D. R. STRONG Consulting Engineers Inc. Page 30 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 13 OFFSITE ANALYSIS DOWNSTREAM MAP Site A1 C1 F1 E1 H F G I A B1 D1 G1 B C D E ©2024 D. R. STRONG Consulting Engineers Inc. Page 31 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FIGURE 14 OFFSITE ANALYSIS DOWNSTREAM TABLE EXISTING DOWNSTREAM PATH Symbol Drainage Component Type, Name, and Size Drainage Component Description Slope Distance From site Discharge Existing Problems Potential Problems Observations of field inspector resource reviewer, or resident See map Type: sheet flow, swale, Stream, channel, pipe, Pond; Size: diameter Surface area drainage basin, vegetation, cover, depth, type of sensitive area, volume % 1/4 mile = 1,320 feet Constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion Tributary area, likelihood of problem, overflow pathways, potential impacts. A Natural discharge area Runoff exits at the NDA as sheet flow over the western property line of the Site 0’ None Observed None Anticipated No flow observed A-B Westerly Sheet Flow Runoff sheet flows across adjacent parcel to the west None Observed None Anticipated No flow observed B Curb and Gutter Runoff enters curb and gutter on east side of Williams Ave S 125’ None Observed None Anticipated No flow observed B-C Northerly Curb and Gutter Flow Runoff sheet flows along flow line of city curb None Observed None Observed No flow observed C Type 1-CB Located on the east side of Williams Ave S ±135’ None Observed None Anticipated No flow observed C-D Westerly pipe flow 6” concrete pipe None Observed None Anticipated No flow observed D Type 2-CB Located on the east side of Williams Ave S ±141’ None Observed None Anticipated No flow observed D-E Northerly pipe flow 8” concrete pipe None Observed None Anticipated No flow observed E Type 2-CB Located on the east side of Williams Ave S ±292’ None Observed None Anticipated No flow observed E-F Northerly pipe flow 8” concrete pipe None Observed None Anticipated No flow observed F Type 2-CB Located on the east side of Williams Ave S ±443’ None Observed None Anticipated No flow observed F-G Northerly pipe flow 8” concrete pipe None Observed None Anticipated No flow observed ©2024 D. R. STRONG Consulting Engineers Inc. Page 32 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington FRONTAGE DOWNSTREAM PATH G Type 2-CB Located on the east side of Williams Ave S ±801’ None Observed None Anticipated No flow observed G-H Northwesterly pipe flow 8” concrete pipe None Observed None Anticipated No flow observed H Type 2-CB Located on the east side of Williams Ave S ±852’ None Observed None Anticipated No flow observed H-I Northerly pipe flow 12” concrete pipe None Observed None Anticipated No flow observed I Outfall to Cedar River COR Facility ID No. OUT-0335 ±942’ None Observed None Anticipated No flow observed Symbol Drainage Component Type, Name, and Size Drainage Component Description Slope Distance From site Discharge Existing Problems Potential Problems Observations of field inspector resource reviewer, or resident See map Type: sheet flow, swale, Stream, channel, pipe, Pond; Size: diameter Surface area drainage basin, vegetation, cover, depth, type of sensitive area, volume % 1/4 mile = 1,320 feet Constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion Tributary area, likelihood of problem, overflow pathways, potential impacts. A1 Natural discharge area Runoff exits at the NDA as sheet flow on the eastern property line of the Site 0’ None Observed None Anticipated No flow observed A1-B1 Easterly Sheet Flow Runoff sheet flows down driveway along frontage None Observed None Anticipated No flow observed B1 Curb and Gutter Runoff enters curb and gutter on west side of Wells Ave S 15’ None Observed None Anticipated No flow observed B1-C1 Northerly Curb and Gutter Flow Runoff sheet flows along flow line of city curb None Observed None Anticipated No flow observed C1 Type-1 CB Located on the west side of Wells Ave S ±69’ None Observed None Observed No flow observed C1-D1 Easterly Pipe Flow 8” concrete pipe None Observed None Anticipated No flow observed D1 Type-2 CB Located on the east side of Wells Ave S ±103’ None Observed None Anticipated No flow observed D1-E1 Northerly Pipe Flow 12” concrete pipe None Observed None Anticipated No flow observed ©2024 D. R. STRONG Consulting Engineers Inc. Page 33 BASSANO MULTI-FAMLIY Level One Downstream Analysis Renton, Washington E1 Type-2 CB Located on the east side of Wells Ave S ±396’ None Observed None Anticipated No flow observed E1-F1 Northerly Pipe Flow 12” concrete pipe None Observed None Anticipated No flow observed F1 Type-2 CB Located on the east side of Wells Ave S ±513’ None Observed None Anticipated No flow observed F1-G1 Northeasterly Pipe Flow 12” concrete pipe None Observed None Anticipated No flow observed G1 Outfall to Cedar River COR Facility ID No. OUT-0319 ±559’ None Observed None Anticipated No flow observed G1-I Northwesterly Open Channel Flow Open channel flow in Cedar River before reaching outfall location from on-site NDA None Observed None Anticipated No flow observed I Outfall to Cedar River COR Facility ID No. OUT-0335 ±1,052’ None Observed None Anticipated No flow observed ©2024 D. R. STRONG Consulting Engineers Inc. Page 34 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION IV FLOW CONTROL ANALYSIS AND WATER QUALITY DESIGN DEVELOPED SITE HYDROLOGY Per the geotechnical report, soils present on-site is holocene alluvium which is considered an outwash soil. The total new and replaced impervious surface area for the Project is 5,793 s.f. 636 s.f. of that impervious area is replaced sidewalk area along the Wells Avenue frontage for the construction of the new driveway cut. The remianing Project impervious area is all new surfaces being added on-site. Of the 5,157 s.f. of impervious surface being added to the Site, 4,903 s.f. is roof area. The remaining of the on-site impervious area consists of 198 s.f. of uncovered driveway/sidewalk area and 56 s.f. of uncovered patio area. The uncovered and covered driveway area totals 1,901 s.f. which makes up all of the proposed PGIS for the Project. The remainder of the Site will be lawn area. The developed map below illustrates the area breakdown for the Project. ©2024 D. R. STRONG Consulting Engineers Inc. Page 35 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington FIGURE 15 DEVELOPED AREA MAP 0GRAPHIC SCALE10'20'40'1 INCH = 20 FT. ©2024 D. R. STRONG Consulting Engineers Inc. Page 36 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington PERFORMANCE STANDARDS The Project is required to meet the City’s Peak Rate Flow Control Standard (Existing Conditions). The Site is required to “match the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10-, and 100-year return periods,” (City of Renton 2017 Surface Water Design Manual Amendment, Sec. 1.2.3.1). However, the Site is within a half mile of the 100-year flood plain for the Cedar River downstream of the Taylor Creek confluence, meaning the Project qualifies for the direct discharge exemption from providing a formal flow control facility. Per Section 1.2.9.2.1 Small Lot BMP Requirements of the Manual, projects are required to mitigate for impervious surfaces by use of Flow Control Best Management Practices (BMPs), to the maximum extent feasible. This requires all lots under 11,000 s.f. to apply flow control BMPs to mitigate impervious areas equal to 10% of the total lot area. 10% of the impervious area for this Site is 600 s.f., so flow control BMPS will be used to mitigate runoff from 600 s.f. of roof area if feasilble. Small lot BMPs were determined by the BMP requirements outlined in Section 1.2.9.2.1 of the CORSWDM. As required by the CORSWDM, small lot BMP requirements were analyzed in the order of preference listed in section 1.2.9.2.1. 1. Full Dispersion: There is an insufficient amount of native growth in order to utilize full dispersion. The lack of required undisturbed area and flowpath lengths means that full dispersion is infeasible for this Lot. 2. Full Infiltration: Per the geotechnical report, the existing soil on the Site is fine graded soils with high levels of silt to deaths of approximately eight feet. This means that infiltration applications are infeasible. The full geotechnical report is included with this application. 3. Limited Infiltration: Per the geotechnical report, the existing soil on the Site is fine graded soils with high levels of silt to deaths of approximately eight feet. This means that infiltration applications are infeasible. The full geotechnical report is included with this application. 4. Rain Gardens: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. The full geotechnical report has been included in conjunction with the preliminary application. 5. Bioretention: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. 6. Permeable Pavement: Per the geotechnical report, the existing soil on the Site makes any form of infiltration infeasible. 7. Basic Dispersion: Due to the amount of impervious surface proposed for this Project, there is no pervious area available for a flowpath that will meet the requirements of the manual for basic dispersion. 8. Soil Amendment: Soil amendment will be provided for all landscaped areas. Per the CORSWDM, a perforated stub out connection is required for a project that proposes the connection of roof downspouts to the local drainage system. However, a perforated pipe connection cannot be provided for this Project because the Site is within Zone 1 APA which does not allow for infiltration and due to the amount of impervious area being added to the Site which eliminates any feasible location for a perforated stub out. ©2024 D. R. STRONG Consulting Engineers Inc. Page 37 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington WATER QUALITY TREATMENT SYSTEM The Project is required to adhere to the City of Renton’s basic water quality treatment criteria. However, the Project is only proposing 1,901 s.f. of PGIS for the concrete driveway. This is below the 5,000 s.f. threshold for formal water quality control in the Manual. This means that the Project is not required to provide a formal flow control facility. ©2024 D. R. STRONG Consulting Engineers Inc. Page 38 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION V CONVEYANCE SYSTEM ANALYSIS AND DESIGN Per Core Requirement #4 of the CORSWDM, the conveyance system must be analyzed and designed for the existing tributary and developed onsite runoff. Pipe systems shall be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow with a minimum of 6 inches of freeboard between the design water surface and structure grate. Pipe system structures may overtop for runoff events that exceed the 25-year design capacity provided the overflow from a 100-year runoff event does not create or aggravate a “severe flooding problem” or “severe erosion problem” as defined in C.R. #2. The Rational Method is used to calculate the 100-year peak flow for the Site. A conveyance system consisting of pipes and catch basins has been designed for the Project. Onsite runoff from all target surfaces is collected by the on-site catch basin or roof drains and conveyed to the existing conveyance system in Wells Avenue S. Pipes are 12” diameter PVC material with a minimum slope of 1.13%. Per the rational method (below), the 100-year flow for the Site under proposed conditions is approximately 0.36 cfs. Manning’s equation was used to estimate the capacity of the most limiting pipe in the conveyance system, which is a 12 PVC pipe at 1.13%. This pipe, and therefore the conveyance system, is capable of conveying 4.49 cfs. This conveyance system is adequately sized to handle the 100-year peak flow. ©2024 D. R. STRONG Consulting Engineers Inc. Page 39 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington RATIONAL METHOD Table 3.2.1.B Coefficients for the Rational Method "iR" Equation 100 year 50 year 25 year 10 year 5 year 2 year aR 2.61 2.75 2.66 2.44 2.33 1.58 bR 0.63 0.65 0.65 0.64 0.63 0.58 Table 3.2.1.A Runoff Coefficients Land Cover C Dense Forest 0.10 Light Forest 0.15 Pasture 0.20 Lawns 0.25 Playgrounds 0.30 Gravel Areas 0.80 Pavement & Roofs 0.90 Open Water 1.00 ©2024 D. R. STRONG Consulting Engineers Inc. Page 40 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION VI SPECIAL REPORTS AND STUDIES The following report and studies have been provided with this submittal. Geotechnical Engineering Study: Associated Earth Sciences, Inc. – August 13, 2020 ©2024 D. R. STRONG Consulting Engineers Inc. Page 41 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION VII OTHER PERMITS, VARIANCES AND ADJUSTMENTS None at this time. ©2024 D. R. STRONG Consulting Engineers Inc. Page 42 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION VIII CSWPPP ANALYSIS AND DESIGN (PART A) The Erosion and Sedimentation Control Design will meet the seven minimum King County requirements: 1. Areas to remain undisturbed shall be delineated with a high visibility plastic fence prior to any site clearing or grading. 2. Site disturbed areas shall be covered with mulch and seeded, as appropriate, for temporary or permanent measures. 3. Perimeter protection shall consist of a silt fence down slope of any disturbed areas or stockpiles. 4. The existing concrete driveway at the point of ingress/egress to the Site will be used as the stabilized construction entrance. 5. Perimeter silt fences downslope will provide sediment retention for the Site. 6. Surface water from disturbed areas will sheet flow to the silt fences. 7. Dust control shall be provided by spraying exposed soils with water until wet. This is required when exposed soils are dry to the point that wind transport is possible which would affect roadways, drainage ways, surface waters, or neighboring residences. SWPPP PLAN DESIGN (PART B) Construction activities that could contribute pollutants to surface and storm water include the following, with applicable BMP’s listed for each item: 1. Storage and use of chemicals: Utilize source control, and soil erosion and sedimentation control practices, such as using only recommended amounts of chemical materials applied in the proper manner; neutralizing concrete wash water, and disposing of excess concrete material only in areas prepared for concrete placement, or return to batch plant; disposing of wash-up waters from water-based paints in sanitary sewer; disposing of wastes from oil-based paints, solvents, thinners, and mineral spirits only through a licensed waste management firm, or treatment, storage, and disposal (TSD) facility. 2. Material delivery and storage: Locate temporary storage areas away from vehicular traffic, near the construction entrance, and away from storm drains. Material Safety Data Sheets (MSDS) should be supplied for all materials stored, and chemicals kept in their original labeled containers. Maintenance, fueling, and repair of heavy equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident. Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other potentially hazardous materials. 3. Building demolition: Protect stormwater drainage system from sediment-laden runoff and loose particles. To the extent possible, use dikes, berms, or other ©2024 D. R. STRONG Consulting Engineers Inc. Page 43 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington methods to protect overland discharge paths from runoff. Street gutter, sidewalks, driveways, and other paved surfaces in the immediate area of demolition must be swept daily to collect and properly dispose of loose debris and garbage. Spray the minimum amount of water to help control windblown fine particles such as concrete, dust, and paint chips. Avoid excessive spraying so that runoff from the site does not occur, yet dust control is achieved. Oils must never be used for dust control. 4. Sawcutting: Slurry and cuttings shall be vacuumed during the activity to prevent migration offsite and must not remain on permanent concrete or asphalt paving overnight. Collected slurry and cuttings shall be disposed of in a manner that does not violate ground water or surface water quality standards. ©2024 D. R. STRONG Consulting Engineers Inc. Page 44 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION IX BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 1. Bond Quantity Worksheet is included as Appendix B of this report. ©2024 D. R. STRONG Consulting Engineers Inc. Page 45 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington SECTION X OPERATIONS AND MAINTENANCE MANUAL The maintenance of the private catch basin on-site will be the responsibility of the owners. Maintenance guidelines set forth in the 2017 CORSWDM have been included in this Section. ©2024 D. R. STRONG Consulting Engineers Inc. Page 46 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDICES ©2024 D. R. STRONG Consulting Engineers Inc. Page 47 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDIX “A” LEGAL DESCRIPTION THE LAND REFERRED TO HEREIN BELOW IS SITUATED IN THE COUNTY OF KING, STATE OF WA, AND IS DESCRIBED AS FOLLOWS: THAT PORTION OF BLOCK 23, TOWN OF RENTON, ACCORDING TO THE PLAT RECORDED IN VOLUME 1 OF PLATS, PAGE 135, IN KING COUNTY, WASHINGTON; AND AN UNPLATTED TRACT ADJOINING, LYING BETWEEN THE WEST LINE OF LOT 15 AND THE EAST LINE OF SAID BLOCK 23 AND THE PRODUCTION OF SAID LINE BETWEEN LINES PARALLEL WITH AND RESPECTIVELY 250 FEET AND 300 FEET NORTH OF THE SOUTH LINE OF SAID BLOCK 23; (BEING KNOWN AS LOT 15 OF THE UNRECORDED SUPPLEMENTAL PLAT OF BLOCK 23 OF THE TOWN OF RENTON). 723150202502 AND 000720016807 VACANT LAND RENTON, WASHINGTON 98057 ©2024 D. R. STRONG Consulting Engineers Inc. Page 48 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDIX “B” BOND QUANTITY WORKSHEET Planning Division |1055 South Grady Way – 6 th Floor | Renton, WA 98057 (425) 430-7200 Date Prepared: Name: PE Registration No: Firm Name: Firm Address: Phone No. Email Address: Project Name: Project Owner: CED Plan # (LUA): Phone: CED Permit # (U):Address: Site Address: Street Intersection: Addt'l Project Owner: Parcel #(s): Phone: Address: Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No:NO Water Service Provided by: If Yes, Provide Forest Practice Permit #:Sewer Service Provided by: Abbreviated Legal Description: 117 Wells Avenue S. Renton, WA 98057 13985 NE 3rd Street Just north of S. 2nd St. and Wells Ave. S. (425) 442-4850 05.09.24 Prepared by: FOR APPROVALProject Phase 1 yoshio.piediscalzi@drstrong.com Yoshio L. Piediscalzi 53232 DR Strong Consulting Engineers 620 7th Avenue, Kirkland, WA 98033 (425) 827-3063 SITE IMPROVEMENT BOND QUANTITY WORKSHEET PROJECT INFORMATION CITY OF RENTON CITY OF RENTON 1 Select the current project status/phase from the following options: For Approval - Preliminary Data Enclosed, pending approval from the City; For Construction - Estimated Data Enclosed, Plans have been approved for contruction by the City; Project Closeout - Final Costs and Quantities Enclosed for Project Close-out Submittal Engineer Stamp Required (all cost estimates must have original wet stamp and signature) Clearing and Grading Utility Providers N/A Project Location and Description Project Owner Information Bassano Multi-Family Bellevue, WA 98005 723150-2025 bConnect, LLC PRE19-000196 Page 2 of 14 Ref 8-H Bond Quantity Worksheet SECTION I PROJECT INFORMATION Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Unit Reference #Price Unit Quantity CostBackfill & compaction-embankment ESC-1 6.50$ CY Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 80.00$ Each Catch Basin Protection ESC-3 35.50$ Each 5 177.50Crushed surfacing 1 1/4" minus ESC-4 WSDOT 9-03.9(3)95.00$ CY Ditching ESC-5 9.00$ CY Excavation-bulk ESC-6 2.00$ CY Fence, silt ESC-7 SWDM 5.4.3.1 1.50$ LF 189 283.50 Fence, Temporary (NGPE)ESC-8 1.50$ LF Geotextile Fabric ESC-9 2.50$ SY Hay Bale Silt Trap ESC-10 0.50$ Each Hydroseeding ESC-11 SWDM 5.4.2.4 0.80$ SY 93 74.40 Interceptor Swale / Dike ESC-12 1.00$ LF Jute Mesh ESC-13 SWDM 5.4.2.2 3.50$ SY Level Spreader ESC-14 1.75$ LF Mulch, by hand, straw, 3" deep ESC-15 SWDM 5.4.2.1 2.50$ SY Mulch, by machine, straw, 2" deep ESC-16 SWDM 5.4.2.1 2.00$ SY Piping, temporary, CPP, 6"ESC-17 12.00$ LF Piping, temporary, CPP, 8"ESC-18 14.00$ LF Piping, temporary, CPP, 12"ESC-19 18.00$ LF Plastic covering, 6mm thick, sandbagged ESC-20 SWDM 5.4.2.3 4.00$ SY Rip Rap, machine placed; slopes ESC-21 WSDOT 9-13.1(2)45.00$ CY Rock Construction Entrance, 50'x15'x1'ESC-22 SWDM 5.4.4.1 1,800.00$ Each Rock Construction Entrance, 100'x15'x1'ESC-23 SWDM 5.4.4.1 3,200.00$ Each Sediment pond riser assembly ESC-24 SWDM 5.4.5.2 2,200.00$ Each Sediment trap, 5' high berm ESC-25 SWDM 5.4.5.1 19.00$ LF Sed. trap, 5' high, riprapped spillway berm section ESC-26 SWDM 5.4.5.1 70.00$ LF Seeding, by hand ESC-27 SWDM 5.4.2.4 1.00$ SY Sodding, 1" deep, level ground ESC-28 SWDM 5.4.2.5 8.00$ SY Sodding, 1" deep, sloped ground ESC-29 SWDM 5.4.2.5 10.00$ SY TESC Supervisor ESC-30 110.00$ HR 60 6,600.00Water truck, dust control ESC-31 SWDM 5.4.7 140.00$ HR 12 1,680.00 Unit Reference #Price Unit Quantity Cost EROSION/SEDIMENT SUBTOTAL:8,815.40 SALES TAX @ 10%881.54 EROSION/SEDIMENT TOTAL:9,696.94 (A) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR EROSION & SEDIMENT CONTROL Description No. (A) WRITE-IN-ITEMS Page 3 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.a EROSION_CONTROL Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public Private Right-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.CostGENERAL ITEMS Backfill & Compaction- embankment GI-1 6.00$ CY Backfill & Compaction- trench GI-2 9.00$ CY 897 8,073.00 Clear/Remove Brush, by hand (SY)GI-3 1.00$ SY Bollards - fixed GI-4 240.74$ Each Bollards - removable GI-5 452.34$ Each Clearing/Grubbing/Tree Removal GI-6 10,000.00$ Acre Excavation - bulk GI-7 2.00$ CY Excavation - Trench GI-8 5.00$ CY 897 4,485.00 Fencing, cedar, 6' high GI-9 20.00$ LF Fencing, chain link, 4'GI-10 38.31$ LF Fencing, chain link, vinyl coated, 6' high GI-11 20.00$ LF Fencing, chain link, gate, vinyl coated, 20' GI-12 1,400.00$ Each Fill & compact - common barrow GI-13 25.00$ CY 897 22,425.00 Fill & compact - gravel base GI-14 27.00$ CY Fill & compact - screened topsoil GI-15 39.00$ CY Gabion, 12" deep, stone filled mesh GI-16 65.00$ SY Gabion, 18" deep, stone filled mesh GI-17 90.00$ SY Gabion, 36" deep, stone filled mesh GI-18 150.00$ SY Grading, fine, by hand GI-19 2.50$ SY Grading, fine, with grader GI-20 2.00$ SY Monuments, 3' Long GI-21 250.00$ Each Sensitive Areas Sign GI-22 7.00$ Each Sodding, 1" deep, sloped ground GI-23 8.00$ SY Surveying, line & grade GI-24 850.00$ Day Surveying, lot location/lines GI-25 1,800.00$ Acre Topsoil Type A (imported)GI-26 28.50$ CY Traffic control crew ( 2 flaggers )GI-27 120.00$ HR 16 1,920.00 Trail, 4" chipped wood GI-28 8.00$ SY Trail, 4" crushed cinder GI-29 9.00$ SY Trail, 4" top course GI-30 12.00$ SY Conduit, 2"GI-31 5.00$ LF Wall, retaining, concrete GI-32 55.00$ SF Wall, rockery GI-33 15.00$ SF SUBTOTAL THIS PAGE:14,478.00 22,425.00 (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) Page 4 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public Private Right-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) ROAD IMPROVEMENT/PAVEMENT/SURFACINGAC Grinding, 4' wide machine < 1000sy RI-1 30.00$ SY AC Grinding, 4' wide machine 1000-2000sy RI-2 16.00$ SY AC Grinding, 4' wide machine > 2000sy RI-3 10.00$ SY 790 7,900.00 AC Removal/Disposal RI-4 35.00$ SY 790 27,650.00 Barricade, Type III ( Permanent )RI-5 56.00$ LF Guard Rail RI-6 30.00$ LF Curb & Gutter, rolled RI-7 17.00$ LF Curb & Gutter, vertical RI-8 12.50$ LF 69 862.50 Curb and Gutter, demolition and disposal RI-9 18.00$ LF 69 1,242.00 Curb, extruded asphalt RI-10 5.50$ LF Curb, extruded concrete RI-11 7.00$ LF Sawcut, asphalt, 3" depth RI-12 1.85$ LF 579 1,071.15 Sawcut, concrete, per 1" depth RI-13 3.00$ LF Sealant, asphalt RI-14 2.00$ LF 579 1,158.00 Shoulder, gravel, 4" thick RI-15 15.00$ SY Sidewalk, 4" thick RI-16 38.00$ SY 56 2,128.00 Sidewalk, 4" thick, demolition and disposal RI-17 32.00$ SY 56 1,792.00 Sidewalk, 5" thick RI-18 41.00$ SY Sidewalk, 5" thick, demolition and disposal RI-19 40.00$ SY Sign, Handicap RI-20 85.00$ Each Striping, per stall RI-21 7.00$ Each Striping, thermoplastic, ( for crosswalk )RI-22 3.00$ SF Striping, 4" reflectorized line RI-23 0.50$ LF Additional 2.5" Crushed Surfacing RI-24 3.60$ SY HMA 1/2" Overlay 1.5" RI-25 14.00$ SY HMA 1/2" Overlay 2"RI-26 18.00$ SY 790 14,220.00 HMA Road, 2", 4" rock, First 2500 SY RI-27 28.00$ SY HMA Road, 2", 4" rock, Qty. over 2500SY RI-28 21.00$ SY HMA Road, 4", 6" rock, First 2500 SY RI-29 45.00$ SY HMA Road, 4", 6" rock, Qty. over 2500 SY RI-30 37.00$ SY HMA Road, 4", 4.5" ATB RI-31 38.00$ SY Gravel Road, 4" rock, First 2500 SY RI-32 15.00$ SY Gravel Road, 4" rock, Qty. over 2500 SY RI-33 10.00$ SY Thickened Edge RI-34 8.60$ LF SUBTOTAL THIS PAGE:58,023.65 (B)(C)(D)(E) Page 5 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public Private Right-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) PARKING LOT SURFACING No.2" AC, 2" top course rock & 4" borrow PL-1 21.00$ SY 2" AC, 1.5" top course & 2.5" base course PL-2 28.00$ SY 195 5,460.00 4" select borrow PL-3 5.00$ SY 1.5" top course rock & 2.5" base course PL-4 14.00$ SY SUBTOTAL PARKING LOT SURFACING:5,460.00 (B)(C)(D)(E) LANDSCAPING & VEGETATION No.Street Trees LA-1 200.00$ 1 200.00 Median Landscaping LA-2 Right-of-Way Landscaping LA-3 Wetland Landscaping LA-4 SUBTOTAL LANDSCAPING & VEGETATION:200.00 (B)(C)(D)(E) TRAFFIC & LIGHTING No.Signs TR-1 200.00$ Street Light System ( # of Poles)TR-2 3,000.00$ Traffic Signal TR-3 Traffic Signal Modification TR-4 SUBTOTAL TRAFFIC & LIGHTING: (B)(C)(D)(E) WRITE-IN-ITEMS SUBTOTAL WRITE-IN ITEMS: STREET AND SITE IMPROVEMENTS SUBTOTAL:72,701.65 27,885.00 SALES TAX @ 10%7,270.17 2,788.50 STREET AND SITE IMPROVEMENTS TOTAL:79,971.82 30,673.50 (B)(C)(D)(E) Page 6 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public PrivateRight-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost DRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.) Access Road, R/D D-1 26.00$ SY * (CBs include frame and lid) Beehive D-2 90.00$ Each Through-curb Inlet Framework D-3 400.00$ Each CB Type I D-4 1,500.00$ Each 1 1,500.00 1 1,500.00 CB Type IL D-5 1,750.00$ Each CB Type II, 48" diameter D-6 2,300.00$ Each for additional depth over 4' D-7 480.00$ FT CB Type II, 54" diameter D-8 2,500.00$ Each for additional depth over 4'D-9 495.00$ FT CB Type II, 60" diameter D-10 2,800.00$ Each for additional depth over 4'D-11 600.00$ FT CB Type II, 72" diameter D-12 6,000.00$ Each for additional depth over 4'D-13 850.00$ FT CB Type II, 96" diameter D-14 14,000.00$ Each for additional depth over 4'D-15 925.00$ FT Trash Rack, 12"D-16 350.00$ Each Trash Rack, 15"D-17 410.00$ Each Trash Rack, 18"D-18 480.00$ Each Trash Rack, 21"D-19 550.00$ Each Cleanout, PVC, 4"D-20 150.00$ Each Cleanout, PVC, 6"D-21 170.00$ Each Cleanout, PVC, 8"D-22 200.00$ Each Culvert, PVC, 4" D-23 10.00$ LF Culvert, PVC, 6" D-24 13.00$ LF Culvert, PVC, 8" D-25 15.00$ LF Culvert, PVC, 12" D-26 23.00$ LF Culvert, PVC, 15" D-27 35.00$ LF Culvert, PVC, 18" D-28 41.00$ LF Culvert, PVC, 24"D-29 56.00$ LF Culvert, PVC, 30" D-30 78.00$ LF Culvert, PVC, 36" D-31 130.00$ LF Culvert, CMP, 8"D-32 19.00$ LF Culvert, CMP, 12"D-33 29.00$ LF SUBTOTAL THIS PAGE:1,500.00 1,500.00 (B)(C)(D)(E) Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Page 7 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public PrivateRight-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES DRAINAGE (Continued)Culvert, CMP, 15"D-34 35.00$ LF Culvert, CMP, 18"D-35 41.00$ LF Culvert, CMP, 24"D-36 56.00$ LF Culvert, CMP, 30"D-37 78.00$ LF Culvert, CMP, 36"D-38 130.00$ LF Culvert, CMP, 48"D-39 190.00$ LF Culvert, CMP, 60"D-40 270.00$ LF Culvert, CMP, 72"D-41 350.00$ LF Culvert, Concrete, 8"D-42 42.00$ LF Culvert, Concrete, 12"D-43 48.00$ LF Culvert, Concrete, 15"D-44 78.00$ LF Culvert, Concrete, 18"D-45 48.00$ LF Culvert, Concrete, 24"D-46 78.00$ LF Culvert, Concrete, 30"D-47 125.00$ LF Culvert, Concrete, 36"D-48 150.00$ LF Culvert, Concrete, 42"D-49 175.00$ LF Culvert, Concrete, 48"D-50 205.00$ LF Culvert, CPE Triple Wall, 6" D-51 14.00$ LF Culvert, CPE Triple Wall, 8" D-52 16.00$ LF Culvert, CPE Triple Wall, 12" D-53 24.00$ LF Culvert, CPE Triple Wall, 15" D-54 35.00$ LF Culvert, CPE Triple Wall, 18" D-55 41.00$ LF Culvert, CPE Triple Wall, 24" D-56 56.00$ LF Culvert, CPE Triple Wall, 30" D-57 78.00$ LF Culvert, CPE Triple Wall, 36" D-58 130.00$ LF Culvert, LCPE, 6"D-59 60.00$ LF Culvert, LCPE, 8"D-60 72.00$ LF Culvert, LCPE, 12"D-61 84.00$ LF Culvert, LCPE, 15"D-62 96.00$ LF Culvert, LCPE, 18"D-63 108.00$ LF Culvert, LCPE, 24"D-64 120.00$ LF Culvert, LCPE, 30"D-65 132.00$ LF Culvert, LCPE, 36"D-66 144.00$ LF Culvert, LCPE, 48"D-67 156.00$ LF Culvert, LCPE, 54"D-68 168.00$ LF SUBTOTAL THIS PAGE: (B)(C)(D)(E) Page 8 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public PrivateRight-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES DRAINAGE (Continued)Culvert, LCPE, 60"D-69 180.00$ LF Culvert, LCPE, 72"D-70 192.00$ LF Culvert, HDPE, 6"D-71 42.00$ LF Culvert, HDPE, 8"D-72 42.00$ LF Culvert, HDPE, 12"D-73 74.00$ LF Culvert, HDPE, 15"D-74 106.00$ LF Culvert, HDPE, 18"D-75 138.00$ LF Culvert, HDPE, 24"D-76 221.00$ LF Culvert, HDPE, 30"D-77 276.00$ LF Culvert, HDPE, 36"D-78 331.00$ LF Culvert, HDPE, 48"D-79 386.00$ LF Culvert, HDPE, 54"D-80 441.00$ LF Culvert, HDPE, 60"D-81 496.00$ LF Culvert, HDPE, 72"D-82 551.00$ LF Pipe, Polypropylene, 6"D-83 84.00$ LF Pipe, Polypropylene, 8"D-84 89.00$ LF Pipe, Polypropylene, 12"D-85 95.00$ LF Pipe, Polypropylene, 15"D-86 100.00$ LF Pipe, Polypropylene, 18"D-87 106.00$ LF Pipe, Polypropylene, 24"D-88 111.00$ LF Pipe, Polypropylene, 30"D-89 119.00$ LF Pipe, Polypropylene, 36"D-90 154.00$ LF Pipe, Polypropylene, 48"D-91 226.00$ LF Pipe, Polypropylene, 54"D-92 332.00$ LF Pipe, Polypropylene, 60"D-93 439.00$ LF Pipe, Polypropylene, 72"D-94 545.00$ LF Culvert, DI, 6"D-95 61.00$ LF Culvert, DI, 8"D-96 84.00$ LF Culvert, DI, 12"D-97 106.00$ LF 49 5,194.00 Culvert, DI, 15"D-98 129.00$ LF Culvert, DI, 18"D-99 152.00$ LF Culvert, DI, 24"D-100 175.00$ LF Culvert, DI, 30"D-101 198.00$ LF Culvert, DI, 36"D-102 220.00$ LF Culvert, DI, 48"D-103 243.00$ LF Culvert, DI, 54"D-104 266.00$ LF Culvert, DI, 60"D-105 289.00$ LF Culvert, DI, 72"D-106 311.00$ LF SUBTOTAL THIS PAGE:5,194.00 (B)(C)(D)(E) Page 9 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public PrivateRight-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Specialty Drainage ItemsDitching SD-1 9.50$ CY Flow Dispersal Trench (1,436 base+)SD-3 28.00$ LF French Drain (3' depth)SD-4 26.00$ LF 15 390.00 Geotextile, laid in trench, polypropylene SD-5 3.00$ SY Mid-tank Access Riser, 48" dia, 6' deep SD-6 2,000.00$ Each Pond Overflow Spillway SD-7 16.00$ SY Restrictor/Oil Separator, 12"SD-8 1,150.00$ Each Restrictor/Oil Separator, 15"SD-9 1,350.00$ Each 1 1,350.00 Restrictor/Oil Separator, 18"SD-10 1,700.00$ Each Riprap, placed SD-11 42.00$ CY Tank End Reducer (36" diameter)SD-12 1,200.00$ Each Infiltration pond testing SD-13 125.00$ HR Permeable Pavement SD-14 Permeable Concrete Sidewalk SD-15 Culvert, Box __ ft x __ ft SD-16 SUBTOTAL SPECIALTY DRAINAGE ITEMS:1,740.00 (B)(C)(D)(E)STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch)Detention Pond SF-1 Each Detention Tank SF-2 Each Detention Vault SF-3 Each Infiltration Pond SF-4 Each Infiltration Tank SF-5 Each Infiltration Vault SF-6 Each Infiltration Trenches SF-7 Each Basic Biofiltration Swale SF-8 Each Wet Biofiltration Swale SF-9 Each Wetpond SF-10 Each Wetvault SF-11 Each Sand Filter SF-12 Each Sand Filter Vault SF-13 Each Linear Sand Filter SF-14 Each Proprietary Facility SF-15 Each Bioretention Facility SF-16 Each SUBTOTAL STORMWATER FACILITIES: (B)(C)(D)(E) Page 10 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public PrivateRight-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES WRITE-IN-ITEMS (INCLUDE ON-SITE BMPs)WI-1 WI-2 WI-3 WI-4 WI-5 WI-6 WI-7 WI-8 WI-9 WI-10 WI-11 WI-12 WI-13 WI-14 WI-15 SUBTOTAL WRITE-IN ITEMS: DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:8,434.00 1,500.00 SALES TAX @ 10%843.40 150.00 DRAINAGE AND STORMWATER FACILITIES TOTAL:9,277.40 1,650.00 (B) (C) (D) (E) Page 11 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public Private Right-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Connection to Existing Watermain W-1 2,000.00$ Each 2 4,000.00 Ductile Iron Watermain, CL 52, 4 Inch Diameter W-2 50.00$ LF Ductile Iron Watermain, CL 52, 6 Inch Diameter W-3 56.00$ LF 97 5,432.00 Ductile Iron Watermain, CL 52, 8 Inch Diameter W-4 60.00$ LF Ductile Iron Watermain, CL 52, 10 Inch Diameter W-5 70.00$ LF Ductile Iron Watermain, CL 52, 12 Inch Diameter W-6 80.00$ LF 256 20,480.00 Gate Valve, 4 inch Diameter W-7 500.00$ Each Gate Valve, 6 inch Diameter W-8 700.00$ Each 5 3,500.00 Gate Valve, 8 Inch Diameter W-9 800.00$ Each Gate Valve, 10 Inch Diameter W-10 1,000.00$ Each Gate Valve, 12 Inch Diameter W-11 1,200.00$ Each 1 1,200.00 Fire Hydrant Assembly W-12 4,000.00$ Each 1 4,000.00 Permanent Blow-Off Assembly W-13 1,800.00$ Each Air-Vac Assembly, 2-Inch Diameter W-14 2,000.00$ Each Air-Vac Assembly, 1-Inch Diameter W-15 1,500.00$ Each Compound Meter Assembly 3-inch Diameter W-16 8,000.00$ Each Compound Meter Assembly 4-inch Diameter W-17 9,000.00$ Each Compound Meter Assembly 6-inch Diameter W-18 10,000.00$ Each Pressure Reducing Valve Station 8-inch to 10-inch W-19 20,000.00$ Each WATER SUBTOTAL:34,612.00 4,000.00 SALES TAX @ 10%3,461.20 400.00 WATER TOTAL:38,073.20 4,400.00 (B) (C) (D) (E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR WATER Quantity Remaining (Bond Reduction) (B)(C) Page 12 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.d WATER Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 CED Permit #: Existing Future Public PrivateRight-of-Way Improvements Improvements (D) (E)Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Clean Outs SS-1 1,000.00$ Each 2 2,000.00 Grease Interceptor, 500 gallon SS-2 8,000.00$ Each Grease Interceptor, 1000 gallon SS-3 10,000.00$ Each Grease Interceptor, 1500 gallon SS-4 15,000.00$ Each Side Sewer Pipe, PVC. 4 Inch Diameter SS-5 80.00$ LF Side Sewer Pipe, PVC. 6 Inch Diameter SS-6 95.00$ LF 67 6,365.00 Sewer Pipe, PVC, 8 inch Diameter SS-7 105.00$ LF Sewer Pipe, PVC, 12 Inch Diameter SS-8 120.00$ LF Sewer Pipe, DI, 8 inch Diameter SS-9 115.00$ LF Sewer Pipe, DI, 12 Inch Diameter SS-10 130.00$ LF Manhole, 48 Inch Diameter SS-11 6,000.00$ Each Manhole, 54 Inch Diameter SS-13 6,500.00$ Each Manhole, 60 Inch Diameter SS-15 7,500.00$ Each Manhole, 72 Inch Diameter SS-17 8,500.00$ Each Manhole, 96 Inch Diameter SS-19 14,000.00$ Each Pipe, C-900, 12 Inch Diameter SS-21 180.00$ LF Outside Drop SS-24 1,500.00$ LS Inside Drop SS-25 1,000.00$ LS Sewer Pipe, PVC, _10 Inch Diameter SS-26 115.00$ LFLift Station (Entire System)SS-27 LS SANITARY SEWER SUBTOTAL:8,365.00 SALES TAX @ 10%836.50 SANITARY SEWER TOTAL:9,201.50 (B) (C) (D) (E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR SANITARY SEWER Quantity Remaining (Bond Reduction) (B)(C) Page 13 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.e SANITARY SEWER Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 Planning Division |1055 South Grady Way – 6 th Floor | Renton, WA 98057 (425) 430-7200 Date: Name: Project Name: PE Registration No: CED Plan # (LUA): Firm Name:CED Permit # (U): Firm Address: Site Address: Phone No. Parcel #(s): Email Address:Project Phase: Site Restoration/Erosion Sediment Control Subtotal (a) Existing Right-of-Way Improvements Subtotal (b) (b)118,045.02$ Future Public Improvements Subtotal (c)-$ Stormwater & Drainage Facilities (Public & Private) Subtotal (d) (d)10,927.40$ (e) (f) Site Restoration Civil Construction Permit Maintenance Bond 25,794.48$ Bond Reduction2 Construction Permit Bond Amount 3 Minimum Bond Amount is $10,000.00 1 Estimate Only - May involve multiple and variable components, which will be established on an individual basis by Development Engineering. 2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% will cover all remaining items to be constructed. 3 Required Bond Amounts are subject to review and modification by Development Engineering. * Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton. ** Note: All prices include labor, equipment, materials, overhead and profit. EST1 ((b) + (c) + (d)) x 20% -$ MAINTENANCE BOND */** (after final acceptance of construction) 9,696.94$ 118,045.02$ 187,994.92$ 9,696.94$ -$ 10,927.40$ -$ 197,691.86$ P (a) x 100% SITE IMPROVEMENT BOND QUANTITY WORKSHEET BOND CALCULATIONS 05.09.24 Yoshio L. Piediscalzi 53232 DR Strong Consulting Engineers R ((b x 150%) + (d x 100%)) S (e) x 150% + (f) x 100% Bond Reduction: Existing Right-of-Way Improvements (Quantity Remaining)2 Bond Reduction: Stormwater & Drainage Facilities (Quantity Remaining)2 T (P +R - S) Prepared by: Project Information CONSTRUCTION BOND AMOUNT */** (prior to permit issuance) (425) 827-3063 yoshio.piediscalzi@drstrong.com Bassano Multi-Family PRE19-000196 117 Wells Avenue S. Renton, WA 98057 723150-2025 FOR APPROVAL 620 7th Avenue, Kirkland, WA 98033 Page 14 of 14 Ref 8-H Bond Quantity Worksheet SECTION III. BOND WORKSHEET Unit Prices Updated: 06/14/2016 Version: 04/26/2017 Printed 5/20/2024 ©2024 D. R. STRONG Consulting Engineers Inc. Page 49 BASSANO MULTI-FAMLIY Technical Information Report Renton, Washington APPENDIX “C” GEOTECHNICAL REPORT associated earth sciences incorporated Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, WA 98033 P (425) 827 7701 Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report WELLS AVENUE SOUTH 6-PLEX Renton, Washington Prepared For: BASSANO LLC Project No. 20200163E001 August 13, 2020 Kirkland | Tacoma | Mount Vernon 425-827-7701 | www.aesgeo.com August 13, 2020 Project No. 20200163E001 Bassano LLC P.O. Box 1343 Renton, Washington 98057 Attention: Joe Bernasconi Subject: Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report Wells Avenue South 6-Plex 117 Wells Avenue South Renton, Washington Dear Mr. Bernasconi: We are pleased to present the enclosed copy of our geotechnical report. This report summarizes the results of our subsurface exploration, geologic hazard, geotechnical engineering studies, and offers geotechnical recommendations for the design and development of the proposed project. We have enjoyed working with you on this study and are confident that the recommendations presented in this report will aid in the successful completion of your project. Please contact me if you have any questions or if we can be of additional help to you. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ Matthew A. Miller, P.E. Principal Engineer MM/ld 20200163E001-2 SUBSURFACE EXPLORATION, GEOLOGIC HAZARD, AND GEOTECHNICAL ENGINEERING REPORT WELLS AVENUE SOUTH 6-PLEX Renton, Washington Prepared for: Bassano LLC P.O. Box 1343 Renton, Washington 98057 Prepared by: Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, Washington 98033 425-827-7701 August 13, 2020 Project No. 20200163E001 Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Project and Site Conditions August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 1 I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of Associated Earth Sciences, Inc.’s (AESI’s) subsurface exploration, geologic hazard, and geotechnical engineering study for the subject project. Our understanding of the project is based on communications with Mr. Joe Bernasconi and review of client-provided information including: • Memorandum regarding “Preapplication Meeting for RenFour Multi-Family, PRE 19-000196” prepared by City of Renton Department of Community & Economic Development Planning Division, dated September 19, 2019; • “Steve Dobson, Lot Survey, Record of Survey” prepared by Crones Surveying, Inc., dated August 21, 2019; • “ALTA Commitment for Title Insurance” prepared by American Life Title Insurance Company, dated May 1, 2019; • Sanitary Sewer Availability Certificate, City of Renton, dated April 29, 2019; • 1983 Sanitary Sewer Rehabilitation (As-Built), Wells Avenue South, North of South 2nd Street, dated June 23, 1983; and • Email regarding “Water Availability to tax lots 00072001638 and 7231502025” to Steve Dobson from City of Renton Public Works. Detailed project plans for the proposed project were not available at the time of preparation of this report. The site location is shown on the “Vicinity Map,” Figure 1. The approximate location of the exploration completed for this study is shown on the “Site and Exploration Plan,” Figure 2. A boring log of the subsurface exploration completed for this study is included in the Appendix. 1.1 Purpose and Scope The purpose of this study was to provide subsurface data to be used in the design and development of the subject project. This study included reviewing selected available geologic literature, advancing one exploration boring, and performing geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and shallow groundwater. Geotechnical engineering studies were completed to establish recommendations for the type of suitable foundations, floor support, anticipated liquefaction-induced settlement, lateral earth pressures, and drainage considerations. This report summarizes our fieldwork and offers geotechnical engineering recommendations based on our present understanding of the property and potential future development. We recommend that we be allowed to review the Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Project and Site Conditions August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 2 recommendations presented in this report and revise them, if needed, as the project develops and a design is finalized. 1.2 Authorization Written authorization to proceed with this study was granted by Mr. Joe Bernasconi on July 10, 2020. Our study was accomplished in general accordance with our proposal dated April 30, 2020. This report has been prepared for the exclusive use of Bassano LLC and their agents, for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. 2.0 PROJECT AND SITE DESCRIPTION The subject site consists of an undeveloped, rectangular-shaped property (King County Parcel Nos. 000720-0168 and 723150-2025) totaling approximately 0.14-acres in area located at 117 Wells Avenue South in Renton, Washington (Figure 1, “Vicinity Map”). The property is bordered on the east by Wells Avenue South, and on the north, south, and west by developed single-family residential parcels. The majority of the property is mantled by crushed rock and has been used for overflow parking. A concrete driveway extends from the street into the eastern side of the property. Site topography across the parcel is relatively flat. Based on review of the information listed previously, we understand conceptual plans for the proposed project generally consist of construction of a new multi-family building with no below-grade levels. We understand that parking will be located on the lowest level of the building with residential living space in the upper levels. Other project features will include a new concrete or asphalt driveway along the south side of the new building and utilities. We understand that the property is located within the City of Renton’s Aquifer Protection Area and that on-site stormwater best management practices (BMPs) that rely on infiltration are prohibited. We understand the preliminary project plans are to direct roof water to existing City of Renton-owned storm drainage located in the Wells Avenue South right-of-way. 3.0 SUBSURFACE EXPLORATION Our field study included advancing one exploration boring located in the north-central portion of the property as shown on Figure 2. The conclusions and recommendations presented in this report are based on the exploration completed for this study. The number, location, and depth of the exploration were completed within site and budgetary constraints. Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Project and Site Conditions August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 3 3.1 Exploration Boring The exploration boring was completed by advancing hollow-stem auger tools with a track-mounted drill rig. During the drilling process, samples were obtained at generally 2.5- to 5-foot-depth intervals. The exploration boring was continuously observed and logged by an engineering geologist from our firm. The exploration log presented in the Appendix is based on the field log, drilling action, and observation of the samples secured. Disturbed, but representative samples were obtained by using the Standard Penetration Test (SPT) procedure in accordance with ASTM International (ASTM) D-1586. This test and sampling method consists of driving a standard 2-inch, outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches. The number of blows for each 6-inch interval is recorded, and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance (“N”) or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached exploration boring log. It should be noted that blow counts and resultant N-values can be artificially elevated (“over-stated”) by the presence of coarse rock (gravel and cobbles). The samples obtained from the split-barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification, as summarized in this report. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field exploration accomplished for this study and review of applicable geologic literature. As shown on the boring log, the exploration boring generally encountered less than about 2 feet of existing fill underlain by very soft and very loose, fine-grained overbank alluvium to a depth of about 9.5 feet. These soils are underlain by loose to medium dense, coarse-grained channel alluvium to the maximum depth explored of 31.5 feet. The boring log is included in the Appendix. 4.1 Stratigraphy Existing Fill Loose to very loose fill was encountered to a depth of up to about 2 feet below the existing ground surface. The fill generally consisted of less than about 6 inches of crushed rock Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Project and Site Conditions August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 4 underlain by brown, sand with some amounts of gravel and some amounts of silt. Existing fill may be present in other areas of the site at greater depths associated with existing underground utilities and past development of the property. Existing fill is not suitable for support of structural loads but may be utilized in structural fills if it does not contain excessive organics and if the moisture is within the range to obtain the required level of compaction. Holocene Alluvium - Overbank Facies Exploration boring EB-1 encountered very soft and very loose, light brown, iron-oxide stained, interbedded, silt and fine sand with trace amounts of organics interpreted as overbank alluvium. Overbank alluvium is not considered suitable for foundation support and may require mitigation for slab-on-grade floor support. The observed overbank alluvium is susceptible to static settlement caused by the application of footing loads. Foundations loads will need to extend through the very soft and very loose overbank alluvium as described in the “Design Recommendations” section of this report. Excavated overbank alluvium material may be suitable for reuse in structural fill applications if such reuse is specifically allowed by project plans and specifications. Reuse would include removing excessive organics (if present), and adjusting moisture content (wetting or drying) to allow compaction to the specified level. Based on the exploration completed for this study, we estimate the overbank alluvium was above optimum moisture content for compaction purposes, and therefore may require drying during favorable weather prior to compaction in structural fill applications. Holocene Alluvium - Channel Facies Underlying the overbank alluvium described above, exploration boring EB-1 encountered channel alluvial soils to the maximum depth drilled of 31.5 feet. The channel alluvium generally consisted of light brown to brownish orange, loose to medium dense, gravel ranging to gravelly sand grading downward to very gravelly sand with trace to some amounts of silt throughout. The channel alluvium is suitable for support of foundation loads. Excavated channel alluvial material may be suitable for reuse in structural fill applications but is not anticipated to be encountered in significant quantities during construction of the structure. 4.2 Geologic Mapping Review of the regional geologic maps titled Geologic Map of King County, compiled by Derek B. Booth, et al. (March 2007) and Geologic Map of the Renton Quadrangle, King County, Washington, by D.R. Mullineaux (1965) indicates the subject site is underlain by alluvium. Our interpretation of the sediments encountered at the subject site is in general agreement with the detailed geologic maps. Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Project and Site Conditions August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 5 4.3 Hydrology Groundwater was observed within the alluvium at the time of drilling in boring EB-1 at a depth of approximately 18.8 feet below the surface at the time of drilling. The observed groundwater is interpreted to be representative of the regional unconfined groundwater table. The depth to the groundwater is expected to vary seasonally with the amount and frequency of rainfall, nearby river levels, and on-site and off-site land use. Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Mitigations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 6 II. GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of potential geologic hazards is based on the geologic, slope, and ground and surface water conditions, as observed and discussed herein. 5.0 SEISMIC HAZARDS AND MITIGATION Earthquakes occur in the Puget Lowland with great regularity. The majority of these events are small and are usually not felt by people. However, large earthquakes do occur, as evidenced by the 1949, 7.2-magnitude event; the 1965, 6.5-magnitude event; and the 2001, 6.8-magnitude event. The 1949 earthquake appears to have been the largest in this area during recorded history. Evaluation of return rates indicates that an earthquake of a magnitude between 6.0 and 7.0 is likely within a given 25- to 40-year period. Generally, there are three types of potential geologic hazards associated with large seismic events at this site: 1) surficial ground rupture, 2) liquefaction, and 3) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 5.1 Surficial Ground Rupture The project site is located approximately 8.5 miles northeast of a suspected trace of the Tacoma Fault Zone and approximately 3 miles south of the southern boundary of the Seattle Fault Zone. Geophysical surveys of the Puget Lowland in 1998 suggested the presence of a fault zone along the north side of the Tacoma basin generally between Tacoma and the south end of Hood Canal. More recent studies by the U.S. Geological Survey (USGS) have provided evidence of surficial ground rupture along the Tacoma Fault near Burley, Washington. The recognition of this fault is relatively new, and data pertaining to it are limited, with studies still ongoing. According to the USGS studies, the latest movement of this fault was about 1,100 years ago when several meters of surficial displacement took place. This displacement can presently be seen in the form of raised tidal flats in the Burley Lagoon, Lynch Bay, and North Cove, resulting in the present-day freshwater marshes and forested lowlands. Further evidence of the faulting activity in this system has been seen at Wollochet Bay, where forested areas were inundated by water. Additionally, linear fault scarp features in the ground surface were exposed in recent Light Detection and Ranging (LIDAR) maps. The scarp features are located near Allyn, Washington, and have been described as trending parallel to the Tacoma Fault system. Studies also point to the fault system continuing across the Puget Sound, and it is inferred as continuing Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Mitigations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 7 through Commencement Bay and the Puyallup River Delta. The slip rate along the Tacoma Fault is thought to be approximately 2 millimeters per year. However, very little is known about the recurrence interval of earthquakes along the Tacoma Fault. Our current understanding of the Seattle Fault suggests that several fault traces are spread across a relatively wide zone. Recent studies by the USGS (e.g., Johnson et al., 1994, Origin and Evolution of the Seattle Fault and Seattle Basin, Washington, Geology, v. 22, p. 71-74 and Johnson et al., 1999, Active Tectonics of the Seattle Fault and Central Puget Sound Washington - Implications for Earthquake Hazards, Geological Society of America Bulletin, July 1999, v. 111, n. 7, p. 1042-1053) have provided evidence of surficial ground rupture along a northern splay of the Seattle Fault. The recognition of this fault is relatively new, and data pertaining to it are limited, with the studies still ongoing. According to the USGS studies, the latest movement of this fault was about 1,100 years ago when about 20 feet of surficial displacement took place. This displacement can presently be seen in the form of raised, wave-cut beach terraces along Alki Point in West Seattle and Restoration Point at the south end of Bainbridge Island. The recurrence interval of movement along this fault system is still unknown, although it is hypothesized to be in excess of several thousand years. Related fault systems in the Puget Sound region have been hypothesized to have reoccurrence intervals in excess of several thousand years. Due to the suspected long recurrence interval, and the distance of this fault system from the site, the potential for surficial ground rupture is considered to be low during the expected life of the project, and no mitigation efforts beyond complying with the requirements of the local jurisdictions and the International Building Code (IBC) in use by the local jurisdiction are recommended. 5.2 Liquefaction Liquefaction is a process through which unconsolidated soil loses strength as a result of vibratory shaking, such as that which occurs during a seismic event. During normal conditions, the weight of the soil is supported by both grain-to-grain contacts and by the pressure within the pore spaces of the soil below the water table. Extreme vibratory shaking can disrupt the grain-to-grain contact, increase the pore pressure, and result in a decrease in soil shear strength. The soil is said to be liquefied when nearly all the weight of the soil is supported by pore pressure alone. Liquefaction can result in deformation of the sediment and settlement of overlying structures. Areas most susceptible to liquefaction include those areas underlain by clean sand or silt with low relative densities accompanied by a shallow water table. To assess the risk, we performed a liquefaction hazard analysis for this site in accordance with guidelines published in Seed & Idriss, 1982; Seed et al., 1985; and Kramer, 1996. Our liquefaction analysis was completed with the aid of LiquefyPro computer software Version 5.8 Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Mitigations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 8 (2009) by CivilTech Corporation. The soil and groundwater conditions observed in EB-1 were used to define subsurface conditions at depth for the analysis. The liquefaction potential is dependent on several site-specific factors such as soil grain size, density, site geometry, static stresses, level of ground acceleration considered, and duration of the event. The 2015 IBC seismic design parameter for peak ground acceleration (PGA) was determined by the latitude and longitude of the project site using the USGS U.S. Seismic Design Maps website1. The USGS website interpolated PGA at the project site to be 0.592g, with a 2 percent chance of exceedance in 50 years. The earthquake parameters used in our liquefaction analysis were a magnitude 7 earthquake occurring directly beneath the site with a peak horizontal ground acceleration of 0.592g per the USGS U.S. Seismic Design Maps website. Results of our liquefaction analysis are provided in the Appendix. Based on our liquefaction analysis under the current standard, the subsurface conditions encountered below the site present a risk of seismic liquefaction and associated liquefaction-induced differential settlement. The liquefaction-induced overall settlement for the site with the above-mentioned parameters is estimated to range from approximately 4 to 6 inches. However, the settlement is predicted to occur below a depth of about 19 feet. We estimate that the differential settlement over a distance of 100 feet would be on the order of one-half of the total seismic settlement. As discussed in the “Foundations” section of this report, the proposed structure could be supported on rock-filled trenches to partially mitigate the effects of the liquefaction, such as differential settlement. 5.3 Ground Motion Seismic design of the project should follow the 2015 IBC guidelines. Seismic site class selection is outlined in American Society of Civil Engineers (ASCE) 7-16. Based on our subsurface explorations, the site is considered to be in Seismic Site Class E. 6.0 EROSION HAZARDS AND MITIGATION In order to control erosion and reduce the amount of sediment transport off the site during construction, the following recommendations should be followed: 1. Properly embedded silt fencing should be placed around the construction area. The fencing should be periodically inspected and maintained, as necessary, to ensure proper function. 1 http://earthquake.usgs.gov/designmaps/ Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Mitigations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 9 2. Construction access should be stabilized with gravel to minimize tracking sediment offsite. 3. If possible, construction should proceed during the drier periods of the year. 4. Surface runoff and discharge should be controlled during and following construction. Uncontrolled discharge may promote erosion and sediment transport. 5. If excavated soils are to be stockpiled on the site for reuse, measures should be taken to reduce the potential for erosion from the stockpile. These could include, but are not limited to, covering the pile with plastic sheeting, and the use of straw bales/silt fences around stockpile perimeters. Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Design Recommendations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 10 III. DESIGN RECOMMENDATIONS 7.0 INTRODUCTION It is our opinion that, from a geotechnical standpoint, the site is suitable for the proposed building provided the recommendations contained herein are properly followed. Our explorations generally encountered approximately 9.5 feet of very soft and very loose overbank alluvium underlain by loose to medium dense channel alluvial sediments extending beyond the depth of our exploration. The overbank alluvial sediments are considered normally consolidated and are conducive to post-construction consolidation when subject to new loads such as those from the placement of fill or from new foundations. Based on the exploration and analyses completed to date, we recommend foundations be constructed on rock-filled trenches to mitigate post-construction static consolidation settlement beneath the proposed building. The rock-filled trenches would extend through the loose to very loose overbank alluvium into the medium dense to dense overbank alluvium. Based on our exploration, we estimate that the depth of rock-filled trenches would be on the order of 9 to 10 feet. It is important to note that raising final grades will induce consolidation of the native alluvial sediments but also could partially mitigate liquefaction-induced settlement. We recommend that once final grading plans are developed, we are allowed to review the plans and update our recommendations to account for new loads from proposed fills, or foundation loads. 8.0 SITE PREPARATION Existing buried utilities, vegetation, topsoil, pavement, and any other deleterious materials should be removed where they are located below planned construction areas. All disturbed soils resulting from demolition activities should be removed to expose underlying undisturbed native sediments and replaced with structural fill, as needed. Erosion and surface water control should be established around the clearing limits to satisfy local requirements. Below planned on-site paving, the soft, compressible native soils should be exposed, proof-rolled if possible, and compacted to a firm an unyielding condition as determined by AESI. If a firm and unyielding condition is achieved, no further remedial preparation would be needed. If excessively yielding conditions are encountered, the unsuitable native soils would be partially removed and replaced with imported structural fill. The depth of replacement of the existing fill below paving should be determined at the time of construction when field Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Design Recommendations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 11 conditions are known. Alternatively, soil cement treatment could be used to complete remedial preparation of existing fill below planned new paving areas. 8.1 Temporary and Permanent Cut Slopes In our opinion, stable, temporary construction slopes should be the responsibility of the contractor and should be determined during construction. For planning purposes, we recommend temporary cut slopes of 1.5H:1V (Horizontal:Vertical) within the overbank alluvium and existing fill (if present). Flatter, temporary cut slopes are recommended in areas of groundwater seepage. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should always be followed . 8.2 Subgrade Protection If building construction will proceed during the winter, we recommend the use of a working surface of the existing concrete, crushed rock, or quarry spalls to protect exposed soils, particularly in areas supporting concentrated equipment traffic. Foundation subgrades may require protection from foot and equipment traffic and ponding of runoff during wet weather conditions. Typically, compacted crushed rock or a lean-mix concrete mat placed over a properly prepared subgrade provides suitable subgrade protection. Foundation concrete should be placed and excavations backfilled as soon as possible to protect the bearing surfaces. 8.3 Site Drainage and Surface Water Control The site should be graded to prevent water from ponding in construction areas and/or flowing into excavations. Exposed grades should be crowned, sloped, and smooth drum-rolled at the end of each day to facilitate drainage. Accumulated water must be removed from subgrades and work areas immediately prior to performing further work in the area. If an effective drainage system is not utilized, project delays and increased costs could be incurred due to the greater quantities of wet and unsuitable fill, or poor access and unstable subgrade conditions. Groundwater was observed relatively deep in our boring at the time of drilling. However, depending on the depth of excavation required to construct the proposed improvements, and the time of year construction is performed, the construction contractor should be prepared to perform temporary dewatering of excavations which may include the use of sump pumps. Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Design Recommendations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 12 9.0 STRUCTURAL FILL All references to structural fill in this report refer to subgrade preparation, fill type, placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts, with each lift being compacted to 95 percent of the modified Proctor maximum density using ASTM D-1557 as the standard. Soils excavated onsite are acceptable for use in structural fills if they can be moisture-conditioned and compacted to project specifications for the intended use. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with current City of Renton codes and standards. Where adjacent to slopes, the top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the locations of the perimeter footings or pavement edges before sloping down at an angle of 2H:1V. The contractor should note that any proposed fill soils must be evaluated by AESI prior to their use in fills. This would require that we have a sample of the material 72 hours in advance to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than the No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather conditions. Some of the native soils present onsite contained significant amounts of silt and are considered highly moisture-sensitive. In addition, construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, a select import material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction with at least 25 percent retained on the No. 4 sieve. 10.0 FOUNDATIONS (ROCK-FILLED TRENCHES) As previously stated, the shallow subsurface sediments (overbank alluvium) encountered at the project site are not suitable for support of the new foundation loads without the risk of post-construction settlement. Because the overbank alluvium is considered too deep to economically extend the footings down to suitable bearing soils, rock-filled trenches extended down to the medium dense to dense channel alluvium are recommended for foundation support. Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Design Recommendations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 13 The trenches should have a minimum width of 4 feet (or as designated by the field engineer/engineering geologist) and be excavated down to the medium dense to dense overbank alluvium. Because of the potential for caving, the actual trench width may be greater than specified. It would be appropriate to backfill the trenches as the excavation proceeds to reduce caving. The use of a larger, track-mounted backhoe will greatly speed trench excavation over the use of a conventional, rubber-tired backhoe. In order to reduce disturbance of the bearing soils exposed in the trench, it is strongly recommended that the teeth of the backhoe bucket be covered with a smooth cutting edge. To determine when suitable bearing has been achieved and to verify proper rock placement, the geotechnical engineer/engineering geologist must be present on a full-time basis during footing trench excavation and backfill. A pump may be required to control seepage so that the bearing level can be visually determined. Seepage entering the excavation on an overnight basis must be removed prior to commencing trench excavation the following day. After the bearing stratum has been reached, the trench should be immediately backfilled. We recommend the use of 2- to 4-inch-size crushed rock for backfill. The crushed rock must be tamped into place to achieve a tightly-packed mass; this may be done with either a “Hoepac”-type compactor mounted on the backhoe or with the excavator bucket. Staging areas should be maintained so that the rock is not contaminated by mud prior to placement in the trench. Equipment access to trench locations should also be maintained. Once the rock-filled trenches are suitably backfilled and compacted we recommend an allowable bearing capacity of 2,000 pounds per square foot (psf) for a conventional spread footing foundation. 11.0 DRAINAGE CONSIDERATIONS Traffic across the on-site soils when they are damp or wet will result in disturbance of the stratum. Therefore, during site work and construction, the contractor should provide surface drainage and subgrade protection, as necessary. All perimeter foundation walls should be provided with a drain at the footing elevation. Drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by washed gravel. The level of the perforations in the pipe should be set at the bottom of the footing, and the drains should be constructed with sufficient gradient to allow gravity discharge away from the building. The perforations should be located on the lower portion of the pipe. In addition, any retaining or subgrade walls should be lined with a minimum, 12-inch-thick, washed gravel blanket, backfilled completely with free-draining material, or lined with a drainage mat, such as Mira-Drain 6000, over the full height of the wall (excluding the first 1 foot below the surface). Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Design Recommendations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 14 This drainage material should tie into the footing drains and must be installed and backfilled in strict accordance with the manufacturer’s specifications. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. To minimize erosion, stormwater discharge or concentrated runoff should not be allowed to flow down any steep excavation cuts. In planning, exterior grades adjacent to walls should be sloped downward away from the structure to achieve surface drainage. Runoff water from impervious surfaces should be collected by a storm drain system that discharges into the site stormwater system. 12.0 FLOOR SUPPORT A slab-on-grade floor may be used supported by rock-filled trenches or over structural fill as discussed below. Where moisture transmission through the slab must be controlled, the floor should be cast atop a minimum of 4 inches of washed pea gravel or ½- to ¾-inch washed crushed rock material to provide a capillary break. The floor should also be protected by a moisture vapor retarder (minimum 6-mil-thick polyethylene sheeting). The vapor retarder must be protected from punctures. If a sand “blotter layer” is placed over the vapor retarder, it must be protected from excess moisture prior to placing the slab. If some cracking and settlement of the floor is tolerable, an alternative would be to support the slab on a structural fill pad. After overexcavating at least 3 feet below finish floor grade, a structural fill would be placed. After the fill is completed and approved, the moisture barrier and free-draining layer may be placed. The floor slab can then be cast on top of the free-draining layer. The floor slab should not be tied into the building’s foundation but should be free to settle independent of footings. The slab should contain bar reinforcement to reduce differential movement across any cracks that might develop. If the potential for floor cracking and settlement must be minimized, the floor should be cast on structural fill or rock-filled trenches. Another alternative would be to support the slab on rock trenches. The trenches would be constructed as discussed under the “Foundations” section of this report. The spacing of the trenches would be determined by a structural engineer based on such things as the amount of reinforcement included in the floor slab design and the amount of acceptable settlement or deflection of the slab. Subsurface Exploration, Geologic Hazard, Wells Avenue South 6-Plex and Geotechnical Engineering Report Renton, Washington Design Recommendations August 13, 2020 ASSOCIATED EARTH SCIENCES, INC. FSM/ld - 20200163E001-2 Page 15 13.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We recommend that AESI perform a geotechnical review of the plans prior to final design completion. In this way, our recommendations may be properly interpreted and implemented in the design. This plan review is not included in the current scope of work and budget. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the earthwork and foundations depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this current scope of work. We have enjoyed working with you on this study and are confident these recommendations will aid in the successful completion of your project. If you should have any questions or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ Frank S. Mocker, L.G., L.E.G. Matthew A. Miller, P.E. Project Geologist Principal Engineer Attachments: Figure 1: Vicinity Map Figure 2: Site and Exploration Plan Appendix: Exploration Log Liquefy Pro Results DATA SOURCES / REFERENCES: USGS: 7.5' SERIES TOPOGRAPHIC MAPS, ESRI/I-CUBED/NGS 2013 KING CO: STREETS, CITY LIMITS, PARCELS, PARKS 3/20 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE VICINITY MAP WELLS AVENUE SOUTH 6-PLEX RENTON, WASHINGTON 20200163E001 7/20 1 KING COUNTY RENTON ± 0 2000 Feet PROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLORORIGINAL MAY REDUCE ITSEFFECTIVENESS AND LEAD TOINCORRECT INTERPRETATION DATE:FIGURE:\\kirkfile2\gis\GIS_Projects\aaY2020\200163 Wells Ave S\aprx\20200163E001 F1 VM_Wells.aprx | 20200163E001 F1 VM_Wells | 7/12/2020 6:10 PM¥ ¥ ¥405 ¬«167 ¬«515 !( SR 900Wells Ave SWilliams Ave SKing County Kitsap County SITE ¬«900 EB-1 PROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLORORIGINAL MAY REDUCE ITSEFFECTIVENESS AND LEAD TOINCORRECT INTERPRETATION DATE:FIGURE: ±\\kirkfile2\gis\GIS_Projects\aaY2020\200163 Wells Ave S\aprx\20200163E001 F2 SP_Wells.aprx | 20200163E001 F2 SP_Wells | 8/4/2020 1:01 PMDATA SOURCES / REFERENCES:D.R. STRONG, 117 WELLS AVENUE SOUTH, BOUNDARY ANDTOPOGRAPHIC SURVEY, 7/20/20KING CO: PARCELS, 3/20LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE 0 30 Feet SITE AND EXPLORATION PLAN WELLS AVENUE SOUTH 6-PLEX RENTON, WASHINGTON 20200163E001 8/20 2 King County LEGEND SITE EXPLORATION BORING APPENDIX 112 212 5611 50/6" 988 354 12108 S-1 S-2 S-3 S-4 S-5 S-6 S-7 Bottom of exploration boring at 31.5 feetGroundwater encountered at 18.8 feet with bottom of boring at 20 feet. Relatively stable.Added bentonite mud at 20 feet. FillCrushed rock underlain by brown SAND, some gravel, some silt (SW-SM). Quaternary Alluvium (Overbank)Moist, light brown with slight iron oxide, fine SAND, some silt and finesandy, SILT; stratified to massive (SP-SM/ML). Moist, light brown, fine SAND, trace to some silt; possible thin organiclaminae; stratified (SP-SM). Rocky drill action begins at ~9.5 feet. Quaternary Alluvium (Channel)Moist, light brown, fine to coarse rounded GRAVEL, some fine to coarsesand, trace silt; crudely bedded (GW). Rocky drill action suggestive of gravelly soils with occasional cobbles. Recovery only ~3-inches, redrilled wet (from drilling to 20 feet), fine tocoarse GRAVEL; no recovery (GW). As above; cuttings at top of hole consist of mostly fine to coarse roundedgravel.Rocky drill action. Wet, light brown, fine to medium SAND, some silt and fine to coarseSAND, trace silt; stratified (SP-SM/SW). Less rocky, faster drill action. Layers of rock? Wet, brownish orange, very gravelly, fine to coarse SAND, trace to somesilt; occasional thin interbeds (<2 inches thick) of fine sand, some silt;crudely stratified (SW-SM/SP-SM). As above; less rocky. Slightly more rocky below ~28 feet based on drill action. As above (SW-SM). 1 of 1 NAVD 88 FSM2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples40 5 10 15 20 25 30 EB-1 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Wells Avenue South 6-Plex M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number20200163E001 7/31/20,7/31/20 Logged by: Shelby Tube Sample 140# / 30Geologic Drill Partners / HSA w/ XL Trailer Mounted Drill Well Ground Surface Elevation (ft) Grab SampleSymbol 7 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20200163E001.GPJ August 4, 202033 33 1717 5050/6" 1616 99 1818