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APPROVED STM RESUB2 BLD2023-0640+Storm_Drainage_Report+4.11.2024_4.59.51_PM+4191983STORM DRAINAGE REPORT For: Koh Residence 15604 75th PI W, Edmonds, WA 98026 Parcel ID: 00513100002410 Applicant: Motionspace Architecture + Design PLLC 3104 Western Ave #107 Seattle, WA 98121 Nazim Nice nazim@motion-space.com (206) 204-0490 Engineer: Bush, Roed & Hitchings 15400 SE 30th PI Ste 100 Bellevue, WA 98007 Jay Decker, PE jayd@brhinc.com (206) 323-4144 Date: March 14th, 2024 RECEIVED Apr 12 2024 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT BLD2023-0640 ►-t O• Dfc e► �F WAsy� Bch d 31195 S�/S AL COMPLIES WITH APPLICABLE CITY STORMWATER CODE 05/17/2024 Koh Residence Storm Drainage Report Table of Contents 1.0 — PROJECT OVERVIEW........................................................................................................................1 2.0 — MINIMUM REQUIREMENTS................................................................................................................2 3.0 — SITE ANALYSIS...................................................................................................................................4 3.1 - Existing Site......................................................................................................................................................4 3.2 - Offsite/Downstream Analysis.............................................................................................................................4 3.3 - Groundwater and Soil Type...............................................................................................................................4 3.4 - Critical Areas.....................................................................................................................................................5 4.0 — PERMANENT STORMWATER CONTROL.........................................................................................6 4.1 - On -Site Stormwater Management.....................................................................................................................6 4.2 - Conveyance System Analysis and Design........................................................................................................7 5.0 — SPECIAL REPORTS AND STUDIES...................................................................................................7 6.0 — OTHER PERMITS................................................................................................................................ 7 7.0 — CONSTRUCTION STORMWATER POLLUTION PREVENTION (MR-2)............................................8 9.0 — APPENDICES....................................................................................................................................12 Appendix A — Hard Surface Summary for Proposed Design........................................................................................12 AppendixB — Onsite Plans..........................................................................................................................................13 AppendixC — Geotechnical Report..............................................................................................................................14 AppendixD — WWHM Report......................................................................................................................................15 Appendix E — Operation and Maintenance Manual......................................................................................................16 List of Figures Figure 1 Vicinity Map ....................................... Figure 2 Minimum requirements Flow Chart.... 1 2 Koh Residence Storm Drainage Report 1.0 — PROJECT OVERVIEW The project site is located at 15604 75th PI W, Edmonds WA, 98026 (Parcel ID: 00513100002410) and bounded by 75th PI W on the east, private properties to the north and south, and the Burlington Northern Santa Fe Railroad to the west. The site has an area of 29,364 square feet (sf), with a limit of disturbance on -site of 11,631 sf. The existing site is undeveloped, but there is evidence of periodic brush clearing on the site. Surface runoff on the existing site sheet flows downhill to the west is flows into the Burlington Northern Santa Fe (BNSF) ROW and discharges into Puget Sound immediately to the west. Drainage from the adjacent properties to the north and south do not run onto the project property and drainage in 75th PI W are controlled through existing drainage structures. The project proposes to construct a single -story single family residence with a basement level. In the proposed design, the total amount of new and replaced surface is 7,328 sf, consisting of 4,687 sf of building roof, 2,422 sf of driveway, 148 sf of concrete walk, and 71 sf of uncovered deck. Runoff from all hard surfaces onsite will be collected and discharged downhill to the west into the BNSF ROW using a standard BNSF discharge detail approved under a separate BNSF permit. The discharge then runs off into Puget Sound to the west, similar to the existing conditions. Pollution source control is proposed for the construction phase of the project. See Section 7 — Construction Stormwater Pollution Prevention. See Appendix A — Hard Surface Summary and Appendix B — Onsite Plans. i SH72 EDMONDS f pvit v'F`N'A 3 148TH ST SW 168THSTSW-� 176TH ST SW LYNNWOOD A 180TH ST SW �P 3 a 0 z Figure 1— Vicinity Map Page 1 Koh Residence Storm Drainage Report 2.0 — MINIMUM REQUIREMENTS The "2019 Stormwater Management Manual for Western Washington" (SWMMWW), the city of Edmonds's Stormwater Addendum to the SWMMWW, and the city of Edmonds Stormwater Management Code are referenced for this project. Minimum Requirements Analysis The site proposes 7,328 sf of new plus replaced hard surface. Minimum Requirement #1 through #9 apply to this project. See Appendix A — Hard Surface Summary for Proposed Design. See Flow Chart below for more details on minimum requirements selection process. Does the project result in 2.000 square feet, or greater. of new plus replaced hard surface arm? OR Does the land disturbing activity total 7,000 square feet or greater? Yes No ., -.r, \ • I 1-....,,11 aphlc Minimum Requirement No. 2applies Next Question Does the project add 5.000 square feet or more of new plus replaced hard surfaces? OR Convert 0.75 acres or more of vegetation to lawn or landscaped areas? OR Convert 2.5 acres or more of native vegetation to pasture. Yes No No Yer Is this a road related project? Does the project add 5.000 square feet or No more of new hard surfaces? Yea All Minunum Requirements Yes i I to the new and replaced PP Y P Do new hard surfaces add 509'0 or hard surfaces and convened more to the existing hard surfaces vegetation areas. within the project limits? All Minimum Requirements No No additional apply to the new hard surfaces requirements. and converted ea ed vegetation arms. Figure 2 — Minimum Requirement Flow Chart Page 2 Koh Residence Storm Drainage Report 1. Preparation of Stormwater Site Plans: A stormwater site plan has been prepared and has been submitted for review and acceptance. 2. Construction Stormwater Pollution Prevention Plan: A CSWPP Plan has been prepared and is included as section 7 of this report in accordance with the ECY Manual. 3. Source Control of Pollution: Source control BMPs S411 for Landscaping and LawnNegetation Management, S453 for Formation of a Pollution Prevention Team, S454 for Preventive Maintenance/Good Housekeeping, S455 for Spill Prevention and Cleanup, S456 for Employee Training, S457 for Inspections, and S458 for Record Keeping will be implemented. 4. Preservation of Natural Drainage Systems and Outfalls: Existing stormwater flows downhill to the west and discharges into Puget Sound. The proposed stormwater system will continue to drain directly into Puget Sound using a standard BNSF discharge detail approved under a separate BNSF permit. 5. On -Site Stormwater Management: The 2,000 SF impervious surface threshold has been exceeded but the site discharges directly into Puget Sound, therefore a subset of BMPs from List #2 were evaluated as per the city of Edmonds stormwater management code chapter 18.30.060.D.5. BMP T5.13 will be applied to landscaped areas. No BMPs were feasible for the roof and other pavement surfaces. See Appendix A — Hard Surface Summary for Proposed Design and Section 4.1 — On -Site Stormwater Management. 6. Runoff Treatment: The total amount pollutant generating hard surface does not exceed 5,000 sf, therefore runoff treatment is not required. 7. Flow Control: The site discharges directly to Puget Sound to the west, therefore, flow control is not required per chapter 18.30.060.D.7 of the city of Edmonds stormwater management code. 8. Wetlands Protection: Stormwater on -site does not discharge to a wetland. No wetlands will be impacted by the proposed redevelopment. 9. Operation and Maintenance: See Appendix E — Operation and Maintenance Manual. Page 3 Koh Residence Storm Drainage Report 3.0 — SITE ANALYSIS 3.1 - Existing Site The existing site slopes steeply to the west towards the BNSF ROW. The existing ground cover onsite consists of dense brush and vegetation. Several existing trees also border the west property line at the downslope end of the property. An existing concrete foundation is located on the east portion of the site. There is no existing pollutant generating hard surface. 3.2 - Offs ite/Down stream Analysis Drainage from properties to the east of 75th PI W are collected and controlled through existing drainage structures in 75th PI W. Drainage from the adjacent properties to the north and south does not run onto the project property. Drainage from the slope between the property and 75th PI W runs onto the project property. Combined with surface runoff on the existing site, drainage sheet flows downhill to the west for approximately 200 LF and flows into the BNSF ROW. Drainage than sheet flows for approximately 80 LF into Puget Sound to the west. There are no existing drainage or stormwater facilities present onsite. The entire site is located in a landslide hazard area, but it has been noted by the geotechnical report that no large-scale movements of the landslide mass have not been documented since the 1950's. There are no other areas of potential off -site impacts from stormwater discharge. As the site discharges directly to Puget Sound to the west, there are no concerns regarding flow capacity of existing drainage systems. For the proposed stormwater design, the existing drainage condition will be maintained and drainage will discharge into the BNSF ROW. Stormwater for the roof and other pavement will be collected onsite and tightlined downhill for approximately 131 If to an outfall and diffuser at the southwest corner of the site. The stormwater will then be dispersed into the BNSF ROW and drain into Puget Sound immediately west of the BNSF ROW. 3.3 - Groundwater and Soil Type Groundwater seepage was no encountered by the geotechnical engineer at the time of exploration, but moist to wet zones were encountered. These areas are interpreted as a result of groundwater collecting in sandier and less dense areas and there is potential for shallow perched water. The soil onsite is mapped as old landslides (Qols) with Whidbey Formation deposits nearby. Subsurface explorations by the geotechnical engineer confirm these soil types. According to the Soil Survey of Snohomish County Area, Washington, the onsite soils are also classified as Alderwood gravelly sandy loam and Alderwood-Everett gravelly sandy loams. See Appendix C — Geotechnical Report. Page 4 Koh Residence Storm Drainage Report 3.4 - Critical Areas The soils onsite have a low potential for liquefaction and amplification of ground motion but could become unstable if significant seismic activity is experienced. The soil types onsite are also listed as a severe erosion hazard. For areas that are not disturbed, or vegetation cover is not removed, the erosion hazard can be categorized as low to moderate. The site is also mapped within the North Edmonds Earth Subsidence and Landslide Hazard Area Report. Certain features such as the restriction of cuts and fills are required. See Appendix C — Geotechnical Report. Page 5 Koh Residence Storm Drainage Report 4.0 — PERMANENT STORMWATER CONTROL 4.1 - On -Site Stormwater Management As per the city of Edmonds stormwater management code chapter 18.30.060.D.5, the project does not need to consider the LID performance standard, bioretention, rain gardens, permeable pavement, or full dispersion, as the site discharges directly to Puget Sound. A subset of the List #2 BMPs were evaluated for the project, and no BMPs were feasible for the roof and other impervious surfaces (see BMP analysis below). Infiltration and dispersion on or near site slopes are not recommended by the geotechnical engineer. See Appendix C — Geotechnical Report. Drainage onsite will be collected and tightlined to a BNSF diffuser and outfall in the SW corner of the site, where water will be dispersed into the BNSF ROW. List #2 BMP Analvsis: Landscaped Areas: All proposed landscaped areas will utilize amended soils per BMP T5.13: Post Construction Soil Quality and Depth. Roof: 1. Full Dispersion evaluation not required. 2. Downspout Full Infiltration is infeasible due to proximity to steep slopes and landslide hazard areas. 3. Bioretention evaluation not required. 4. Downspout Dispersion is infeasible due to proximity to steeps slopes and landslide hazard areas. 5. Detention vaults or pipes are not feasible due to the proximity of steep slopes and landslide hazard areas. 6. Perforated Stub -Out Connections are infeasible due to proximity to steeps slopes and landslide hazard areas. 7. Concentrated Flow Dispersion is infeasible due to proximity to steeps slopes and landslide hazard areas. 8. Sheet Flow Dispersion is infeasible due to proximity to steeps slopes and landslide hazard areas. Walkways: 1. Full Dispersion evaluation not required. 2. Full Infiltration is infeasible due to proximity to steep slopes and landslide hazard areas. 3. Bioretention evaluation not required. 4. Perforated Stub -Out Connections are infeasible due to proximity to steeps slopes and landslide hazard areas. 5. Concentrated Flow Dispersion is infeasible due to proximity to steeps slopes and landslide hazard areas. 6. Sheet Flow Dispersion is infeasible due to proximity to steeps slopes and landslide hazard areas. 7. Detention vaults or pipes are not feasible due to the proximity of steep slopes and landslide hazard areas. Page 6 Koh Residence Storm Drainage Report 4.2 - Conveyance System Analysis and Design A Conveyance System Analysis and Design can be provided upon request. 5.0 — SPECIAL REPORTS AND STUDIES The Geotechnical Engineering Report is in Appendix C for this report. The Geotechnical Engineering Study was prepared by: Engineer: Nelson Geotechnical Associates Inc. Date: 06/23/2022 6.0 — OTHER PERMITS BNSF Stormwater Discharge Permit Page 7 Koh Residence Storm Drainage Report 7.0 — CONSTRUCTION STORMWATER POLLUTION PREVENTION (MR-2) The CSWPPP was developed per the requirements in Volume II of the 2019 Stormwater Management Manual for Western Washington. 13 Elements: 1. Preserve Vegetation/Mark Clearing Limits Construction Limits will be marked by chain link fencing and/or high visibility fence where necessary (BMP C103), which will be moved as necessary for construction phasing of the various project elements. 2. Establish Construction Access Entrance to the site will be through a stabilized construction entrance per BMP C105 as shown in the TESC plan. Trucks will be positioned to avoid exposed soil and excavation equipment will be washed on -site prior to transfer off -site, per BMP C106. 3. Control Flow Rates Exposed soils are mostly limited to the area within the new foundation, which will contain sediment and runoff. A sediment trap will be used as necessary to contain runoff from the construction area. The sediment trap was sized using the provided formula in the SWMMWW from BMP C240: Sediment Trap. The 2-year flow (Q2) is 0.1061 cfs and was determined using the WWHM. The surface type is assumed to be parking with an area of 0.27 acres. See Appendix D — WWHM Report for 2-year flow. SA = (2080 sf/cfs) * (0.1061 cfs) =z 221 sf min 4. Install Sediment Controls Perimeter protection will be provided in the form of a silt fence (BMP C233). A sediment trap (BMP C240) will also be implemented to contain runoff in the construction area. 5. Stabilize Soils Exposed soils will be limited to the building foundation, utility trenching and pavement restoration. Landscaped surfaces will be given topsoil per BMP C125, and other exposed soils will be mitigated with plastic covering per BMP C123 as necessary. The entire site will apply dust control per BMP C140 during dry weather periods. Page 8 Koh Residence Storm Drainage Report 6. Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner that minimizes erosion. BMP C120: Temporary and Permanent Seeding and BMP C122: Nets and Blankets are proposed. 7. Protect Drain Inlets Proposed catch basin onsite will be protected during construction per BMP C220: Inlet Protection. 8. Stabilize Channels and Outlets BMP C122: Nets and Blankets and BMP C207: Check Dams are proposed to stabilize interceptor swales during the construction process. 9. Control Pollutants BMP C151: Concrete Hadnling, C152: Sawcutting and Surfacing Pollution Prevention, and C251: Construction Stormwater Filtration are proposed. In addition, the equipment used will be in good working order and wheel washing will be used. 10. Control Dewatering Construction is relatively shallow, and groundwater is not anticipated during construction. All trench and building excavation will be self-contained to prevent runoff. If groundwater is encountered, sump pumps will pump to either the sediment trap or sediment tanks prior to discharge. 11. Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMPs specifications. Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 12. Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: - Design the project to fit the existing topography, soils, and drainage patterns. - Emphasize erosion control rather than sediment control. Page 9 Koh Residence Storm Drainage Report - Minimize the extent and duration of the area exposed. - Keep runoff velocities low. - Retain sediment on site. - Thoroughly monitor site and maintain all ESC measures. - Schedule major earthwork during the dry season. The project will be managed according to the following key project components: Phasing of Construction The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the maximum extent possible, the transport of sediment from the site during construction. Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C 162). Seasonal Work Limitations From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt -laden runoff will be prevented from leaving the site through a combination of the following: • Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and • Limitations on activities and the extent of disturbed areas; and • Proposed erosion and sediment control measures. Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. The following activities are exempt from the seasonal clearing and grading limitations: • Routine maintenance and necessary repair of erosion and sediment control BMPs; • Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and • Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions Page 10 Koh Residence Storm Drainage Report Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. Inspection and Monitoring All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: Assess the site conditions and construction activities that could impact the quality of stormwater, and • Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. A Certified Erosion and Sediment Control Lead shall be always on -site or on -call. Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP This SWPPP shall be retained on -site or within reasonable access to the site. The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. See Appendix B — Onsite Plans for TESC Plans and additional details. 13. Protect Low Impact Development BMPs N/A — No construction phase LID BMPs are proposed for the project. Page 11 Koh Residence Storm Drainage Report 9.0 — APPENDICES Appendix A — Hard Surface Summary for Proposed Design Page 12 HARD SURFACE SUMMARY: BUILDING ROOF =4,687 SF DRIVEWAY =2.422 SF d CONC WALK =148 SF v 30 15 0 30 60 SCALE IN FEET 1 "=30' TOTAL NEW AND REPLACED HARD SURFACE =7,328 SF SITE AREA =29,364 SF Koh Residence Storm Drainage Report Appendix B — Onsite Plans Page 13 c� 0 w w ry W 0 0 0 / z Q W W z 0 i i Cn w w co z Q J 0 / c� z w w z z W / N N 0 N / N N 0 N / 0 N 0 N X N SEWER EASEMENT PER AFN FOUND REBAR/CAP 8306230289 N 89`54'04" E (RAD) LS/48374 ON LINE -___,- RR°nn'nz,c i oo qc - - 'I 1 KOH RESIDENCE 15604 75TH PL W, EDMONDS, WA 98026 REBAR/CAP 1800 SURVEY LEGEND: ASPHALT SURFACE BUILDING LINE CENTERLINE 1 C CABLE/TELCOM LINE (UNDERGROUND) I I w LLJ CONIFER TREE Z z:Z �/� DECIDUOUS TREE Q1 I '; JI Ld J ELECTRIC LINE (UNDERGROUND) �I FENCE LINE (CHAIN LINK) 0 r oI G GAS LINE Of ry CL W 0I ❑ GM GAS METER �-I I PROPOSED BUIDING r F� GRAVEL SURFACE 0 �-� PARCEL NUMBER: 1 ` I MB Q _ MAILBOX (RESIDENTIAL) I 00513100002410 ° (�) MANHOLE (AS NOTED) \ \'; I I MAJOR CONTOUR LINE MINOR CONTOUR LINE z Z ~ MW0 MONITORING WELL/BORE 11.4 r�,j I \ \.Fj I ►j� MONUMENT IN CASE W E7 REBAR (AS NOTED) SEWER LINE [� EX NATIVE GROWTH PROTECTION `\, \ \\'; I 11.4 I SIGN EASEMENT PER AFN \ \:,I a I - - STEEP SLOPE STORM DRAIN LINE Q 200010235001 ... \ SUBJECT PARCEL PROPERTY LINE z\ E-iI WATER LINE & I \ � �WM WATER METER WALL (AS NOTED) \0 EX 15' INGRESS AND EGRESS EASEMENT PER AFN 200010235001 o N\0 �NI e I 20 10 0 20 40 - - - - S 87°38'29" E� SCALE IN FEET I - M 1 "=20' FOUND REBAR/CAP 20.02' LS/18898 0.16' N k 0.49' N' OF PROP. CC' I I GENERAL NOTES: 1. ALL MATERIALS AND WORK SHOWN ON THESE PLANS SHALL CONFORM TO THE CITY ELEVATION, REMOVE AND REPLACE WITH COMPACTED STRUCTURAL FILL PER 32. EXISTING UTILITY LINES IN SERVICE WHICH ARE DAMAGED DUE TO CONSTRUCTION OF EDMONDS STANDARD PLANS AND DETAILS, THE FOLLOWING SPECIFICATIONS AND GEOTECHNICAL REPORT. WORK SHALL BE REPAIRED AT CONTRACTOR'S EXPENSE AND INSPECTED AND CODES, AND ALL OTHER APPLICABLE LOCAL MUNICIPAL, STATE, AND FEDERAL CODES, 15. SEE SURVEY AND ARCHITECTURAL DRAWINGS FOR DIMENSIONS AND LOCATIONS OF ACCEPTED BY CITY OF EDMONDS AND OWNER'S REPRESENTATIVE PRIOR TO RULES AND REGULATIONS: BUILDINGS, LANDSCAPED AREAS AND OTHER PROPOSED OR EXISTING SITE FEATURES. BACKFILLING. - CURRENT INTERNATIONAL BUILDING CODE (IBC) 16. SEE ARCHITECTURAL DRAWINGS FOR PERIMETER FOUNDATION DRAINS. FOUNDATION 33. NEW UTILITY LOCATIONS ARE GENERALLY SHOWN BY DIMENSION, WHERE NO - 2023 WSDOT/APWA STANDARD SPECIFICATIONS FOR ROAD, BRIDGE AND MUNICIPAL DRAINS SHALL BE INDEPENDENT OF OTHER SITE DRAIN LINES AND SHALL BE DIMENSIONS ARE INDICATED, LOCATIONS MAY BE SCALED FROM DRAWINGS. FIELD CONSTRUCTION 11GHTLINED TO THE STORM DRAIN SYSTEM WHERE INDICATED ON THE PLANS. ADJUSTMENTS SHALL BE APPROVED BY OWNER'S REPRESENTATIVE AND CITY. - 2019 WASHINGTON STATE DEPARTMENT OF ECOLOGY STORMWATER MANAGEMENT 17. ALL REQUIRED STORMWATER FACILITIES MUST BE CONSTRUCTED AND IN OPERATION 34. FIELD STAKE ALL UTILITY STUBS AT THE PROPERTY LINE. MANUAL PRIOR TO INSTALLATION OF ANY PAVEMENT UNLESS OTHERWISE APPROVED BY THE 35. TRENCH BACKFILL OF UTILITIES LOCATED WITHIN THE CITY RIGHT-OF-WAY SHALL BE 2. STANDARD PLAN AND TYPE NUMBERS INDICATED ON THESE DRAWINGS REFER TO CITY ENGINEER. COMPACTED TO 95X COMPACTION TEST REPORTS SHALL BE PROVIDED TO THE CITY OF EDMONDS STANDARD DETAILS, UNLESS NOTED OTHERWISE 18. ALL ROOF DRAINS, PERIMETER FOUNDATION DRAINS, CATCH BASINS AND OTHER PRIOR TO PAVING. 3. A COPY OF THESE APPROVED PLANS MUST BE ON THE JOBSITE WHENEVER EXTERNAL DRAINS SHALL BE CONNECTED TO THE STORM DRAINAGE SYSTEM, UNLESS 36. WHERE NEW PIPE CLEARS AN EXISTING OR NEW UTILITY BY 6" OR LESS, PLACE CONSTRUCTION IS IN PROGRESS. NOTED OTHERWISE. ETHAFOAM 200 AS A CUSHION BETWEEN THE UTILITIES. 4. DEVIATIONS FROM THESE PLANS MUST BE APPROVED BY THE ENGINEER OF RECORD 19. ALL FOOTING DRAINS SERVING THE BUILDING AND WALLS SHALL CONNECT TO THE 37. SEE MECHANICAL DRAWINGS (WHERE APPLICABLE) FOR CONTINUATION OF SITE AND THE LOCAL GOVERNING AUTHORITY. DRAINAGE SYSTEM AT THE DOWNSTREAM END UTILITIES WITHIN THE BUILDING. 5. CONTRACTOR SHALL RECORD ALL APPROVED DEVIATIONS FROM THESE PLANS ON A 20. CONTRACTOR SHALL OBTAIN AND PAY FOR ALL PERMITS REQUIRED FOR INSTALLATION 38. SEE ELECTRICAL DRAWINGS WHERE APPLICABLE FOR EXTERIOR ELECTRICAL WORK. SET OF "AS -BUILT" DRAWINGS AND SHALL SUMMARIZE ALL AS -BUILT CONDITIONS ON OF ALL SITE IMPROVEMENTS INDICATED ON THESE DRAWINGS. ( ) ONE SET OF REPRODUCIBLE DRAWINGS FOR SUBMITTAL TO THE OWNER PRIOR 21. A SEPARATE IRRIGATION PERMIT MUST BE OBTAINED FROM THE CITY PUBLIC WORKS 39. SEE LANDSCAPE DRAWINGS (WHERE APPLICABLE) FOR SITE IRRIGATION SYSTEM. PROJECT COMPLETION AND ACCEPTANCE. A SET OF AS -BUILT DRAWINGS SHALL BE DEPARTMENT. PRIOR TO FINAL CONSTRUCTION ACCEPTANCE, PROVIDE TO THE CITY 40. PIPE MATERIAL AND SIGNAGE SUBMITTALS SHALL BE PROVIDED TO CITY ENGINEERING SUBMITTED TO THE CITY OF EDMONDS PRIOR TO FINAL APPROVAL OF THE BUILDING WATER QUALITY TECHNICIAN, A COPY OF THE BACKFLOW TEST REPORT. TEST DIVISION FOR APPROVAL PRIOR TO INSTALLATION. OCCUPANCY/FINAL PROJECT APPROVAL. REPORTS CAN BE FAXED TO 425-744-6057 OR EMAILED TO 41. THE SUBJECT PROJECT SITE IS LOCATED WITHIN THE EARTH SUBSIDENCE LANDSLIDE 6. ELEVA11ONS SHOWN ARE IN FEET. SEE SURVEY FOR BENCHMARK INFORMATION. JEFF.KOBLYK@EDM ONDSWA. GOV. BACKFLOW TESTING SHALL BE COMPLETED BY THE HAZARD AREA. IN ACCORDANCE WITH ECDC 19.10.080, "REQUESTS FOR EARLY SITE 7. THE LOCATIONS OF EXISTING UTILITIES AND SITE FEATURES SHOWN HEREON HAVE OWNER ANNUALLY THEREAFTER. ACCESS IN ADVANCE OF BUILDING PERMIT APPROVAL OR IN THE TIME PERIOD BEEN FURNISHED BY OTHERS BY FIELD SURVEY OR OBTAINED FROM AVAILABLE 22• AS A MINIMUM REQUIREMENT, ALL DISTURBED AREAS ON AND OFF SITE SHALL BE BETWEEN OCTOBER 1ST AND APRIL 30TH FOR ANY PURPOSE SHALL BE SUBMITTED RECORDS AND SHOULD THEREFORE BE CONSIDERED APPROXIMATE ONLY AND NOT RETURNED TO THE EQUIVALENT OF THEIR PRECONSTRUCT ION CONDITION IN TO THE BUILDING OFFICIAL ACCOMPANIED BY WRITTEN CONCURRENCE OF THE NECESSARILY COMPLETE. IT IS THE SOLE RESPONSIBILITY OF THE CONTRACTOR TO ACCORDANCE WITH APPROPRIATE REQUIREMENTS AND STANDARDS. OWNER/APPLICANTS GEOTECHNICAL ENGINEER OF RECORD." INDEPENDENTLY VERIFY THE ACCURACY OF ALL UTILITY LOCATIONS SHOWN AND TO 23. ALL DISTURBED SOIL AREAS SHALL BE COMPOST AMENDED AND SEEDED OR STABILIZED BY OTHER ACCEPTABLE METHODS FOR THE PREVENTION OF ONSIIE FURTHER DISCOVER AND PROTECT ANY OTHER UTILITIES NOT SHOWN HEREON WHICH EROSION AFTER THE COMPLETION OF CONSTRUCTION. SEE EROSION CONTROL PLANS UTILITY PURVEYORS: NATURAL GAS: MAY BE AFFECTED BY THE IMPLEMENTA110N OF THIS PLAN. CONTRACTOR SHALL FOR SPECIFIC GRADING AND EROSION CONTROL REQUIREMENTS. PUGET SOUND ENERGY CUSTOMER VERIFY LOCATION, DEPTH, SIZE, TYPE AND CONDITION OF EXISTING UTILITY LINES AT 24. THE CONTRACTOR SHALL KEEP OFF -SITE STREETS CLEAN AT ALL TIMES BY STORMWATER: CONSTRUCTION SERVICES CONNECTION OR CROSSING POINTS BEFORE TRENCHING FOR NEW UTILITIES. ENGINEER SWEEPING. WASHING OF THESE STREETS WILL NOT BE ALLOWED WITHOUT PRIOR ASSUMES NO RESPONSIBILITY FOR THE COMPLETENESS OR ACCURACY OF THE APPROVAL. CITY OF EDMONDS, PUBLIC WORKS & UTILITIES 3130 S 38TH ST EXISTING UTILITIES AND SITE FEATURES PRESENTED ON THESE DRAWINGS. ENGINEER 25THIS PROJECT IS NOT A BALANCED EARTHWORK PROJECT. BOTH EXPORT AND IMPORT CITY HALL - 1ST FLOOR 121 5TH AVE N TACOM A, WA 98409 . SHALL BE NOTIFIED IMMEDIATELY OF CONFLICTS THAT ARISE. OF SOIL AND ROCK MATERIALS ARE REQUIRED. EDMONDS, WA 98020 PH: 253 476-6421 8. CONTRACTOR SHALL LOCATE AND PROTECT ALL UTILITIES DURING CONSTRUCTION AND 26. SLOPE OF FINISHED GRADE SHALL BE CONSTANT BETWEEN FINISHED CONTOURS OR - ( ) SHALL CONTACT THE UNDERGROUND UTILITIES LOCATION SERVICE (1-800-424-5555) PH: (425) 771 0241 AT LEAST 48 HOURS PRIOR TO CONSTRUCTION. SPOT ELEVATIONS SHOWN. POWER: 9. CONTRACTOR SHALL VERIFY ALL CONDITIONS AND DIMENSIONS AT THE PROJECT SITE 27• FINISHED GRADE SHALL SLOPE AWAY FROM BUILDING WALLS AT MINIMUM 5% SLOPE WATER: SNOHOMISH COUNTY PUBLIC BEFORE STARLING WORK AND SHALL N011FY OWNER'S REPRESENTATIVE OF ANY FOR A MINIMUM DISTANCE OF 10 FEET. DISCREPANCIES. 28. CONTRACTOR SHALL BE RESPONSIBLE FOR AND SHALL INSTALL AND MAINTAIN CITY OF EDMONDS, PUBLIC WORKS & UTILITIES UTILITY DISTRICT SHORING AND BRACING AS NECESSARY TO PROTECT WORKERS, EXISTING BUILDINGS, CITY HALL - 1ST FLOOR 121 5TH AVE N 2320 CALIFORNIA ST 10. PIPE LENGTHS WHERE SHOWN ARE APPROXIMATE AND MAY CHANGE DUE TO FIELD STREETS, WALKWAYS, UTILITIES AND OTHER EXISTING AND PROPOSED IMPROVEMENTS EDMONDS, WA 98020 EVERETT, WA 98201 CONDITIONS. AND EXCAVATIONS AGAINST LOSS OF GROUND OR CAVING EMBANKMENTS. 11. CONTRACTOR SHALL OBTAIN A COPY OF THE GEOTECHNICAL REPORT (WHERE CONTRACTOR SHALL ALSO BE RESPONSIBLE FOR REMOVAL OF SHORING AND BRACING, PH: (425) 771-0241 PH: (425) 783-1000 APPLICABLE) AND SHALL THOROUGHLY FAMILIARIZE HIMSELF WITH THE CONTENTS AS REQUIRED. THEREOF. ALL SITE WORK SHALL BE PERFORMED IN STRICT COMPLIANCE WITH THE 29. CONTRACTOR SHALL OBTAIN APPROVAL FROM THE CITY AND FOLLOW CITY SANITARY SEWER: PHONE AND CABLE: RECOMMENDATIONS OF THIS REPORT. PROCEDURES FOR ALL WATER SERVICE INTERRUPTIONS, HYDRANT SHUTOFFS, STREET CITY OF EDMONDS, PUBLIC WORKS & UTILITIES ZIPLY FIBER 12. STRUCTURAL FILL MATERIAL AND PLACEMENT SHALL CONFORM TO THE CLOSURES OR OTHER ACCESS RESTRICTIONS. CONTRACTOR SHALL NOT RELOCATE OR RECOMMENDATIONS OF THE PROJECT GEOTECHNICAL REPORT. ELIMINATE ANY HYDRANTS WITHOUT FIRST OBTAINING WRITTEN APPROVAL FROM THE CITY HALL - 1ST FLOOR 121 5TH AVE N PH: 1 (866) 699-4759 13. SUBGRADE SOILS IN ALL AREAS WHERE RAIN GARDENS, INFILTRATION OR PERVIOUS FIRE MARSHAL. EDMONDS, WA 98020 PAVEMENT IS TO BE PLACED SHALL BE DELINEATED AND PROTECTED AT ALL TIMES 30. COORDINATE AND ARRANGE FOR ALL U1ILITY CONNECTIONS, UTILITY RELOCATIONS PH: (425) 771-0241 COMCAST FROM COMPAC11VE ACTIVITIES (i.e. HEAVY EQUIPMENT, STOCKPILING). AND/OR SERVICE INTERRUPTIONS WITH THE AFFECTED OWNERS AND APPROPRIATE 14. MANHOLES, CATCH BASINS, UTILITIES AND PAVEMENT SHALL BEAR ON MEDIUM DENSE UTILITY COMPANIES. CONNECTIONS TO EXISTING UTILITIES SHALL BE MADE ONLY WITH PH: (800) 934-6489 TO VERY DENSE NATIVE SOIL OR COMPACTED STRUCTURAL FILL. IF SOIL IS ADVANCE WRITTEN APPROVAL OF THE AUTHORITIES GOVERNING SAID UTILITIES. DISTURBED, SOFT, LOOSE, WET OR IF ORGANIC MATERIAL IS PRESENT AT SUBGRADE 31. ALL UTILITIES SHALL BE PLACED UNDERGROUND. '� 6_ n -11 i t SHEET INDEX: '4wau C1.0 COVER SHEET AND NOTES C2.0 TESC PLAN C2.1 TESC DETAILS C3.0 GRADING AND UTILITY PLAN C3.1 GRADING AND UTILITY DETAILS .! 14M a ow w.v.w i C3.2 ADDITIONAL DETAILS AND PROFILES C4.0 BNSF OUTFALL EXHIBIT PLAN - FOR REFERENCE C4.1 BNSF OUTFALL EXHIBIT DETAILS - FOR REFERENCE PROJECT CONTACTS OWNER: YVETTE SYLVI A AN N XAVI ER MICHAEL KOH BENG CHYE 12 JALAN SETIAKASIH 1, DAMNSARA HEIGHTS 54090 KUALA LUMPUR, MALAYSIA michael.yvette@gmail.com PH: (616) 634-1293 ENGINEER: BUSH ROED & HITCHINGS 15400 SE 30TH PL STE 100 BELLEVUE, WA 98007 CONTACT: JAY DECKER, P.E. jayd@brhinc.com PH: (206) 323-4144 SURVEYOR: GROUNDMARK LAND SURVEYING, PLLC 2712 E FIR ST SEATTLE, WA 98122 sean@groundmarkls.net PH: (206) 580-3801 ARCHITECT: MOTIONSPACE ARCHITECTURE + DESGIN PLLC 3104 WESTERN AVE #107 SEATTLE, WA 98121 CONTACT: NAZIM NICE nazim@motion-space.com PH: (206) 204-0490 f r I!M 91 5W S APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION 3 � Q 0 0 o CGS. I NC a W:4 `HS0 �m L.L U W 0 z w Itoo z Iq O U U) - N�z C0 O - (D z �0CE z w Cam = J T 0 O 00 06 O � V�//�� T 06 / W C o C) 0 a W W =`�o 0 > oU jr CY) LJ C- .. Lu W>� _ 0J� U)0 J T W .� m Q tk( I M1 F-- LJ J 0 U Z oz Z Lu Q 0 U) W LLJ = CE (n = W 0 0 U Z 0 U)L Z> 0 Ld Ld Z 0 Q Z 0 0 0 N O Z U) 0 0 W W 0 0 LU drawn by checked by DP JDD scale I date AS SHOWN 03/14/24 job no. 2022117 sheet V I . V of 0 z Q n U C0 IJ_I N 0 z Q w z 0 i i Cn w w co z Q J n 0 / c� z w w z z W / N N 0 N / N N 0 N / 0 N 0 N X N CONSTRUCTION SEQUENCE: 1. SCHEDULE A PRE —CONSTRUCTION MEETING THROUGH MyBuildingPermit.com WITH EMAIL engineeringpermits0edmondswa.gov 2 DAYS IN ADVANCE OF DATE REQUESTED. 2. REVIEW TEMPORARY EROSION AND SEDIMENT CONTROL NOTES 3. CALL FOR UTILITY LOCATES. 4. INSTALL TESC MEASURES AND MAINTAIN DUST CONTROL WHILE PREVENTING DISTURBANCE OF ANY AREAS OF VEGETATION OUTSIDE THE CONSTRUCTION ZONE. 5. HAVE EROSION CONTROL MEASURES INSPECTED BY CITY OF EDMONDS ENGINEERING INSPECTOR. ALL TEMPORARY SEDIMENTATION AND EROSION CONTROL MEASURES MUST BE IN PLACE AND INSPECTED PRIOR TO ANY CONSTRUCTION OR SITE CLEARING. EROSION AND SEDIMENTATION CONTROL PRACTICES AND/OR DEVICES SHALL BE MAINTAINED UNTIL PERMANENT VEGETATION IS ESTABLISHED. 6. ROUGH GRADE SITE AS REQUIRED TO INSTALL DRAINAGE FEATURES. 7. CLEAR, GRUB & ROUGH GRADE SITE. COMPOST AMEND AND REVEGETATE DISTURBED AREAS NOT SUBJECT TO ADDITIONAL SURFACE DISTURBANCE IMMEDIATELY AFTER ROUGH GRADING. OTHER EXPOSED AREAS SHALL BE STABILIZED PER EROSION CONTROL NOTES BELOW 8. INSTALL PROPOSED BUILDING, UTILITIES, AND BNSF DRAINAGE PIPE OUTFALL. 9. STABILIZE AND COMPOST AMEND ALL EXPOSED SOILS PRIOR TO REVEGETATION OF ENTIRE SITE PER CITY OF EDMONDS STANDARD DETAIL SD-642. 10. ESTABLISH LANDSCAPING AND PERMANENT VEGETATION. ALL TEMPORARY EROSION CONTROL MEASURES SHALL BE REMOVED UPON FINAL SITE STABILIZATION AND APPROVAL BY CITY INSPECTOR. EROSION CONTROL NOTES: APPROVAL OF THIS EROSION/SEDIMENTATION CONTROL (ESC) PLAN DOES NOT CONSTITUTE AN APPROVAL OF DRAINAGE DESIGN. THE IMPLEMENTATION OF THIS ESC PLAN AND THE CONSTRUCTION, MAINTENANCE, REPLACEMENT, AND UPGRADING OF THESE ESC BMPS IS THE RESPONSIBILITY OF THE APPLICANT UNTIL ALL CONSTRUCTION IS COMPLETED AND APPROVED AND VEGETATION/LANDSCAPING IS ESTABLISHED. CLEARLY FLAG THE BOUNDARIES OF THE CLEARING LIMITS SHOWN ON THIS PLAN IN THE FIELD PRIOR TO CONSTRUCTION. DURING THE CONSTRUCTION PERIOD, NO DISTURBANCE BEYOND THE FLAGGED CLEARING LIMITS SHALL BE PERMITTED. THE FLAGGING SHALL BE MAINTAINED BY THE APPLICANT FOR THE DURATION OF CONSTRUCTION. CONSTRUCT THE ESC BMPS SHOWN ON THIS PLAN IN CONJUNCTION WITH ALL CLEARING AND GRADING ACTIVITIES, AND IN SUCH A MANNER AS TO ENSURE THAT SEDIMENT AND SEDIMENT LADEN WATER DO NOT ENTER THE DRAINAGE SYSTEM, ROADWAYS, OR VIOLATE APPLICABLE WATER STANDARDS. THE ESC BMPS SHOWN ON THIS PLAN ARE THE MINIMUM REQUIREMENTS FOR ANTICIPATED SITE CONDITIONS. DURING THE CONSTRUCTION PERIOD, UPGRADE THESE ESC BMPS AS NEEDED FOR UNEXPECTED STORM EVENTS AND TO ENSURE THAT SEDIMENT AND SEDIMENT —LADEN WATER DO NOT LEAVE THE SITE. THE APPLICANT SHALL INSPECT THE ESC BMPS DAILY AND MAINTAIN THEM AS NECESSARY TO ENSURE THEIR CONTINUED FUNCTIONING. INSPECT AND MAINTAIN THE ESC BMPS ON INACTIVE SITES A MINIMUM OF ONCE A MONTH OR WITHIN THE 48 HOURS FOLLOWING A MAJOR STORM EVENT (I.E. A 24—HOUR STORM EVENT WITH A 10—YR OR GREATER RECURRENCE INTERVAL). AT NO TIME SHALL THE SEDIMENT EXCEED 60—PERCENT OF THE SUMP DEPTH OR HAVE LESS THAN 6—INCHES OF CLEARANCE FROM THE SEDIMENT SURFACE TO THE INVERT OF THE LOWEST PIPE. ALL CATCH BASINS AND CONVEYANCE LINES SHALL BE CLEANED PRIOR TO PAVING. THE CLEANING OPERATION SHALL NOT FLUSH SEDIMENT LADEN WATER INTO THE DOWNSTREAM SYSTEM. INSTALL STABILIZED CONSTRUCTION ENTRANCES AT THE BEGINNING OF CONSTRUCTION AND MAINTAINED FOR THE DURATION OF THE PROJECT. ADDITIONAL MEASURES MAY BE REQUIRED TO ENSURE THAT ALL PAVED AREAS ARE KEPT CLEAN FOR THE DURATION OF THE PROJECT. ALL DISTURBED AREAS TO BE COMPOST AMENDED PER 2019 SWMMWW BMP T.5.13. INSTALL AND MAINTAIN ALL TESC ACCORDING TO APPROVED PLANS, CITY OF EDMONDS STANDARD DETAILS, AND ALL OTHER MEASURES THAT MAY BE REQUIRED DURING CONSTRUCTION. FILTER SOCKS AND INLET PROTECTION TO BE ADDED TO ANY CATCH BASINS DOWNSTREAM. PERMANENT SLOPES SHOULD BE COVERED WITH EROSION CONTROL MATTING AND VEGETATED. BMP C123: DESIGN AND INSTALLATION SPECIFICATIONS • PLASTIC SLOPE COVER MUST BE INSTALLED AS FOLLOWS: 1. RUN PLASTIC UP AND DOWN THE SLOPE, NOT ACROSS THE SLOPE. 2. PLASTIC MAY BE INSTALLED PERPENDICULAR TO A SLOPE IF THE SLOPE LENGTH IS LESS THAN 10 FEET. 3. PROVIDE A MINIMUM OF 8—INCH OVERLAP AT THE SEAMS. 4. ON LONG OR WIDE SLOPES, OR SLOPES SUBJECT TO WIND, TAPE ALL SEAMS. 5. PLACE PLASTIC INTO A SMALL (12—INCH WIDE BY 6—INCH DEEP) SLOT TRENCH AT THE TOP OF THE SLOPE AND BACKFILL WITH SOIL TO KEEP WATER FROM FLOWING UNDERNEATH. 6. PLACE SAND FILLED BURLAP OR GEOTEXTTLE BAGS EVERY 3 TO 6 FEET ALONG SEAMS AND TIE THEM TOGETHER WITH TWINE TO HOLD THEM IN PLACE. 7. INSPECT PLASTIC FOR RIPS, TEARS, AND OPEN SEAMS REGULARLY AND REPAIR IMMEDIATELY. THIS PREVENTS HIGH VELOCITY RUNOFF FROM CONTACTING BARE SOIL, WHICH CAUSES EXTREME EROSION. 8. SANDBAGS MAY BE LOWERED INTO PLACE TIED TO ROPES. HOWEVER, ALL SANDBAGS MUST BE STAKED IN PLACE. • PLASTIC SHEETING SHALL HAVE A MINIMUM THICKNESS OF 6 MIL. • IF EROSION AT THE TOE OF A SLOPE IS LIKELY, A GRAVEL BERM, RIPRAP, OR OTHER SUITABLE PROTECTION SHALL BE INSTALLED AT THE TOE OF THE SLOPE IN ORDER TO REDUCE THE VELOCITY OF RUNOFF. MAINTENANCE STANDARDS • TORN SHEETS MUST BE REPLACED AND OPEN SEAMS REPAIRED. • COMPLETELY REMOVE AND REPLACE THE PLASTIC IF IT BEGINS TO DETERIORATE DUE TO ULTRAVIOLET RADIATION. • COMPLETELY REMOVE PLASTIC WHEN NO LONGER NEEDED. • DISPOSE OF OLD TIRES USED TO WEIGHT DOWN PLASTIC SHEETING APPROPRIATELY. 70 W4 50' z r _OT 1 LIMIT OF DISTURBANCE \ LIMI S T 8•0 ^N T FENCE R EDMONDS ER-900 (POSED CB BE ITECTED 11.50' R 0 PLACE NT OR WHERE np LOCATION NING WALL PER R OC DENSE BRUSH,) .. ^ .. I I I N I 15. d: E , X'� I I o m EASEMENT P I BORE HOLE I W I AW/ NO COVER l LOC. PER ) I I " 1 BRUSH) N I 1 . " L )T 2 0 \ —R " 1e AP \ \ \ \ > INTERCEPT } SWALE APLE` I I \ \ \ 5 CHECK DAIS (TYP) -x —x— —� I � N N 8738'195. ' (195.1 R1) I I� °i CONC. I. I f\ 4' OUARR SPALLS 1 I \ X 'ROPERTYED �( AyE D OIL WITH 9MP � \ I l/I III I I I �C.2 ASERSHET �i �� I I IIC N UC110N SAND � RVE ETAiE I I I 20 10 0 20 40 SCALE IN FEET 1 "=20' a COVER STOCKPILE WITH PLASTIC COVERING WITHIN 2" OURS 20'10 vv 1, oo$o U . W y N 5'p_p 8* 1 STABILIZED CONSTRUCTION 2 IM@ ENTRANCE PER EDMONDS �MBSTD ER-901 C2.1 OB \ ,...1. CB RIM-96.21' PVC N I.E=97.50' 6 PVC E I.E.=97.00' B' PVC S I.E.-96.90' INLET 3 PROTECTION PER EDMONDS C2• STD ER-902 SDMH RIM=93.:. IE DIR X' TYPE=X.X I I APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION 3 1-10c 0) Q o o �G5. I NC o 00 `HSIR . (n U W 'q0o� z W It00 z 10 0 U) — Nmz c� C,0_ 0 z 16T- z W NMm = T 0 0 06 o T W C �o C) 0 r� /1 1 W W I c0 E 0 > o�U `Y) w C- w::)� (f) > U) 0 0 Lu -1 U)0 J Q LU T W .� J Q W �0 oz W 0 0 Z Q U) Z W CE I u0 Ld Z 0 U)U) Z -> 0 Lu w z 0 Q Z_ 0 0 N O Z U) 0 0 W W 0 z 0 0 w drawn by checked by DP JDD scale date AS SHOWN 03/14/24 job no. 2022117 sheet �-/ L . U of 2" x 2" WOOD/STEEL FILTER FABRIC SECURED TO 2" x 2' 14 GA WIRE FABRIC EQUAL NATIVE BACKFILL MATERIAL 8" 0 I N FILTER FABRIC MATERIAL IN CONTINOUS ROLLS USE STAPLES OR WIRE RINGS TO ATTACH FABRIC TO WIRE 2" x 2" WOOD/STEEL POSTS -\ I I I CE FPORT FIRE MESH ILTER FABRIC I `BURY BOTTOM OF FILTER MATERIAL 8" TO 12" NOTES: 1. CONTRACTOR/DEVELOPER SHALL MAINTAIN AND ENSURE PROPER EROSION CONTROL THROUGHOUT PROJECT. CITY INSPECTION REQUIRED ON 2. SILT FENCE TO BE PLACED DOWNSLOPE OF CONSTRUCTION ALL EROSION CONTROL METHODS ACTIVITY. BEFORE OTHER WORK CAN BEGIN `sl. 189\' SILT FENCE NOT TO SCALE REVISION DATE CITY OF EDMONDS FILTER FABRIC FENCE JANUARY 2018 FILTRATION SYSTEMS PUBLIC WORKS STANDARD DEPARTMENT DETAIL APPROVED BY: R. ENGLISH E R - 9 00 Surface area determined at top of weir 1' Min. � 3.5' - 5' c'1 + 1.5' Min. Note: Trap may be formed by berm or by partial or complete excavation. 4' Min. Overflow 1' Min 1' Min. %4" - 1.5" J Washed gravel Geotextile 2" - 4" Rock Rip Rap Discharge to stabilized conveyance, outlet, or level spreader NOT TO SCALE Cross Section of Sediment Trap Revised June 2016 DEPARTMENT OF ECOLOGYPlease see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. SEDIMENT TRAP _LS 4 TH IN DE FULL WIDTH GRESS/EGRESS DETAIL NOTES: THE MINIMUM LENGTH SHALL BE EXTENDED AS NECESSARY TO ENSURE MATERIAL IS NOT TRACKED OFF SITE O AND/OR INTO THE PUBLIC RIGHT-OF-WAY. O ATB DRIVEWAY RAMP AND/OR SITE ACCESS ROAD 15' WIDE MIN. SEE TABLE BELOW FOR REQUIRED LENGTH. NOTES: 1. SURFACE WATER - ALL SURFACE WATER FLOWING OR DIVERTED TOWARD CONSTRUCTION ENTRANCES SHALL BE PIPED ACROSS THE ENTRANCE. IF PIPING IS IMPRACTICAL, A MOUNTABLE BERM WITH 5:1 SLOPES WILL BE PERMITTED. 2. MAINTENANCE - THE ENTRANCE SHALL BE MAINTAINED IN A CONDITION WHICH WILL PREVENT TRACKING OR FLOWING OF SEDIMENT OFF SITE AND/OR ONTO PUBLIC RIGHT-OF-WAY. THIS MAY REQUIRE PERIODIC TOP DRESSING WITH ADDITIONAL QUARRY SPALLS AS CONDITIONS DEMAND AND REPAIR AND/OR CLEANOUT OF ANY MEASURES USED TO TRAP SEDIMENT. ALL SEDIMENT SPILLED, DROPPED, WASHED OR TRACKED OFF SITE AND/OR ONTO PUBLIC RIGHT-OF-WAY MUST BE REMOVED IMMEDIATELY. 3. WHEELS SHALL BE CLEANED TO REMOVE SEDIMENT PRIOR TO LEAVING THE SITE. WHEN WASHING IS USED, IT SHALL BE DONE ON AN AREA STABILIZED WITH QUARRY SPALLS AND WHICH DRAINS INTO AN APPROVED SEDIMENT TRAPPING DEVICE. 4. INSPECTION AND NEEDED MAINTENANCE SHALL BE PROVIDED AFTER EACH RAIN. PROJECT SIZE MIN LENGTH OF (FEET) QUARRY SPALLS* < 1/4 ACRE 30 < 1 ACRE 50 < 3 ACRE 100 > 3 ACRE 100 *PROVIDE ATB OR ASPHALT TRANSITION WHERE FRONTAGE ROAD IS AN ARTERIAL. LENGTH TO BE DETERMINED BY CITY INSPECTOR. CITY INSPECTION REQUIRED ON ALL EROSION CONTROL METHODS BEFORE OTHER WORK CAN BEGIN REVISION DATE CITY OF EDMONDS STABILIZED CONSTRUCTION JANUARY 2018 ENTRANCE E()e" PUBLIC WORKS STANDARD DEPARTMENT DETAIL APPROVED BY: R. ENGLISH E R - 9 01 STABILIZED CONSTRUCTION ENTRANCE NOT TO SCALE View Looking Upstream Note: Key stone into channel banks and extend it beyond the abutments a minimum of 18" (0.5m) to prevent flow around dam. Section A -A Spacing Between Check Dams DEPARTMENT OF ECOLOGY State of Washington CHECK DAMS A 18„ 12" (0.5m) (150mm) Cp 24" (0.6m) 'L' = the distance such that points 'A' and 'B' are of equal elevation. Rock Check Dam NOT TO SCALE Revised June 2016 Please see http://www.ecy.wa.govlcopyright.html for copyright notice including permissions, limitation of liability, and disclaimer. CATCH BASIN FILTER SOCK WITH OVER FLOW HOLES (TYP) :IN NOTES: 1. CONTRACTOR/DEVELOPER SHALL MAINTAIN THIS APPLICATION AT ALL TIMES DURING CONSTRUCTION PERIOD. 2. ANY SEDIMENT IN CATCH BASIN INSERT SHALL BE REMOVED WHEN INSERT IS ONE-THIRD FULL. 3. CITY INSPECTION REQUIRED ON ALL EROSION CONTROL METHODS BEFORE OTHER WORK CAN BEGIN. REVISION DATE CITY OF EDMONDS TEMPORARY JANUARY 2018 SEDIMENT TRAP T PUBLIC WORKS FOR CATCH BASINS STANDARD DEPARTMENT DETAIL Is l 1 g 9 APPROVED BY: R. ENGLISH E R— 9 0 2 INLET PROTECTION NOT TO SCALE APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION 3 u0 � Q 110 C) NC � a ado � "�� o � `HSIR . 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DEDICATION ..........I..:....... 1 "=10' 2" SEWER :::: :::::::::I :: ::: I ` ICONSTRUCTIO 0) I 1� ILo G' I' I I' 1 (n 0 I W 1 r-- FORCE MAIN .. .::I . _ :::: :::::::::I ......... .....................I......._..........................................................I..... i.................................... I�' I' I I I I I I F-► 85 .......... � � III III � I C)�V�.� �, ► °�-�.\- �,�--_-� °' �� NOTE: PROPOSED UTILITIES SHOWN ARE IN PARALLEL ACCESS ROAD WALL AND UTILITY CROSSING A -IT I SCALE• 1" = 10H 1=5V I I 11 I 1 1 I I I I I I i, I „ �� I - - � � TYPE OF AREA SQUARE FOOTAGE STORMWATER FACILITY LAWN AND 11,782 N/A LANDSCAPE ROOFS 4,687 BNSF OUTFALL HARD SURFACES 2,580 BNSF OUTFALL INSTALL NEW 1" METER IN EMPTY METER BOX PER EDMONDS STANDARDS 1 - RESTORE C3.1 PAVEMENT PER EDMONDS STD GU-410 (TYP) ASPHALT ACCESS ROAD 4" HMA OVER 2' GRANULAR STRUCTURAL FILL OR CRUSHED ROCK PER GEOTECH RECOMMENDATION CLEAN SAWCUT AT EXISTING EDGE OF PAVEMENT AT 75TH PL W AND APPLY AR4000 SEALER AT JOINT - SIDE SEWER STUB IE=94.3f APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: CITY ENGINEERING DIVISION o � o U) U °C OC) z W �o� W �00 ? CO LO U ��_ �) m z W N - J m� _ T U U � 0 O = 06 o� cc �co o 0 O I: a L W W T>`�o O > �> U 11 CY5Wc ) 5; �J 0W V0 J � z `� MW m J 04 Ln a s� Z J a_ LU �0 �z 0 U) Z LU Q CE U I z 0 0 � Q Z 0 o W w Of z 0 F Q z 0 a' 0 0 0 N O Z 2 0 0 cr� C0 CD o 2 0 drawn by checked by DP JDD scale date AS SHOWN 03/14/24 job no. 20221 17 sheet C 3 . 0 of FINAL JOINT SHALL BE A NEAT SAW CUT STRAIGHT LINE. ALL EXPOSED VERTICAL HMA CLASS 1/2" EDGES SHALL BE TACKED NEATLY PER PG 58H-22 WSDOT STANDARD SPECIFICATIONS 5-04.3(4) (SEE NOTES 4 & 5) 1' APPROVED TACK OR APPROVED EQUAL AND SEALED PER WSDOT STD 5-04.3(4)A. 1' SLOPE EXCAVATION TO AVOID UNDERMINING EXISTING PAVEMENT. EXISTING HMA..... :....:..:......:..:::::....::::.:...:....'.-,:_..:'..,.....,.::,..,:._.,::-,:,-:.,.....::,...:,......:::.;::.::::,':.:•� EXISTING BEDDING MATERIAL (1-1/4" MINUS) CRUSHED SURFACE BASE COURSE (SEE NOTE 3) IMPORT BACKFILL SHALL BE COMPACTED TO 95% MAXIMUM DENSITY (SEE NOTE 2) TRENCH WIDTH NOTES: 1. SEE CITY OF EDMONDS MODIFICATIONS TO DIVISION 9 OF THE CURRENT WSDOT STANDARD SPECIFICATIONS FOR BACKFILLING REQUIREMENTS. 2. SUBMIT PROCTOR AND DENSITY TESTS FROM CERTIFIED TESTING COMPANIES DOCUMENTING THAT THE BACKFILL MEETS A MINIMUM OF 95% DENSITY PER ASTM D 1557. 3. CSBC DEPTH SHALL BE A MINIMUM OF 6", AND SHALL BE INSTALLED IN MULTIPLE EQUAL THICKNESS LIFTS NOT EXCEEDING 6". 4. ROADWAY HMA DEPTH SHALL BE A MINIMUM OF 4" FOR RESIDENTIAL ROADS AND 6" FOR COLLECTORS/ARTERIALS. 5. ALLEY HMA DEPTH SHALL BE A MINIMUM OF 2" THICK. UNLESS APPROVED BY THE ENGINEER, ANY DEPTH GREATER THAN 2" SHALL MATCH EXISTING. 6. UNLESS APPROVED BY THE ENGINEER, THE HMA SHALL BE INSTALLED IN MULTIPLE EQUAL THICKNESS LIFTS NOT EXCEEDING 2". 7. FINAL PAVEMENT JOINTS SHALL BE NEATLY SAW CUT AND UNIFORMILY SEALED WITH WSDOT STANDARD SPECIFICATIONS 5-04.3(4)A APPROVED JOINT SEALANT OR APPROVED EQUAL. ' REVISION DATE CITY OF EDMONDS TYPICAL HMA AND APRIL 2021 UTILITY PATCH PUBLIC WORKS STANDARD DEPARTMENT DETAIL APPROVED BY: R. ENGLISH G U - 41 0 TYPICAL HMA AND UTILITY PATCH NOT TO SCALE w z'mJw J > w Z_ ?? O Z M~du wQw .10 Lo a U a Qom 10' /- (IF STUB FOR FUTURE DEVELOPMENT) SEWER STUB SHALL BE LOCATED 10' INSIDE PROPERTY LINE & STAKED. PLACE 2"x4" TIMBER AT END OF SIDE SEWER STUB AND CUT TO LENGTH TO ENSURE 3 FEET EXTENDS ABOVE GRADE. PAINT TOP 18 INCHES WHITE. IN 3 INCH HIGH LETTERS, STENCIL THE NUMBER OF EVEN FEET FROM GROUND ELEVATION TO THE SEWER STUB INVERT. 8 GAUGE WIRE TO BE DOUBLE WRAPPED AROUND PIPE AND 2 x 4 STAKE AT OR ABOVE FINISHED GRADE. w Z J a `LOCKING CLEANOUT COVER / PER COE STD DTL SS-200 a 6" LATERAL SEWER SLOPE - 2% MIN TO 50% MAX 22.5' OR 45' BEND 6" TEST TEE 6" WYE/6" ROMAC SADDLE SEE NOTES 1 AND 2 POSSIBLE SEWER MAIN LOCATION 22.5' OR 45' BEND 6" TEST TEE 6" TEE POSSIBLE I SEWER MAIN LOCATION NOTES: 1. WHEN TAPPING INTO EXISTING MAIN A ROMAC STYLE CB SADDLE SHALL BE USED. PLACEMENT OF TEE SHALL DEPEND ON DEPTH OF SEWER MAIN. AS A MINIMUM, THE TEE SHALL BE PLACED AT A 45 DEGREE ANGLE FROM PIPE SPRINGLINE. 2. IF CONNECTING EXISTING PRIVATE SIDE SEWER TO NEW CITY LATERAL, A CONCRETE/PVC STRONGBACK FERNCO RC SERIES OR ROMAC COUPLING SHALL BE USED AND SECURED PER MFR'S INSTRUCTIONS. 3. BORING OF SERVICES WITHIN RIGHT OF WAY IS NOT ALLOWED. 4. SEWER PIPE SHALL BE SDR-35 AND JOINTS SHALL BE GASKETED. 5. IF STUB FOR FUTURE DEVELOPMENT, USE RUBBER JOINT BISCUIT PLUG OR OTHER APPROVED WATERTIGHT PLUG. CITY OF EDMONDS NEW LATERAL NEW FOR EXISTING PUBLIC WORKS SEWER MAIN PIPE DEPARTMENT APPROVED BY: R. ENGLISH SEWER LATERAL NOT TO SCALE REVISION DATE FEBRUARY 2023 STANDARD DETAIL SS-202 SEE COE STD DTL GU-410 { oz v� 0m BEDDING MATERIAL (1-1/4" MINUS) 6" MIN ,� / ,� / / ,� CRUSHED SURFACE BASE COURSE (SEE NOTE 2 BELOW) Ld w n EL 6" MIN FOUNDATION (IF REQUIRED) SEE NOTE 4 nIN 8" MIN NOTE NOTES: 1. MAXIMUM WIDTH OF TRENCH AT TOP OF PIPE • 18" OR LESS FOR 6" AND SMALLER DIAMETER PIPE • 24" FOR 8" DIAMETER PIPE • 36" FOR 12" DIAMETER PIPE • O.D. PLUS 18" FOR PIPE LARGER THAN 12" NOMINAL DIAMETER 2. REFER TO DIVISION 9 OF WSDOT STANDARD SPECIFICATIONS FOR MATERIAL GRADATION AND ADDITIONAL INFORMATION. 3. TRENCH BACKFILL SHALL MEET A MINIMUM COMPACTION OF 95% DENSITY PER ASTM D 1557. 4. IF UNSTABLE MATERIAL IS ENCOUNTERED BELOW PIPE ZONE, CONTRACTOR SHALL REMOVE AND REPLACE AS REQUIRED BY CITY ENGINEER. 181 - REVISION DATE CITY OF EDMONDS APRIL 2021 TYPICAL TRENCH SECTION PUBLIC WORKS STANDARD DEPARTMENT DETAIL APPROVED BY: R. ENGLISH G U - 400 TYPICAL TRENCH SECTION NOT TO SCALE DWELLING PROPERTY OWNER PUBLIC RIGHT-OF-WAY w RED FLASHING ALARM, z VISIBLE FROM ROW PER HANDOUT E-61 AND E-62 w ROADWAY a PUMP CONTROL FINISHED O PANEL GRADE a SIDE SEWER r 5' MIN BACKFLOW PREVENTER PER COE STD DTL SS-220 GRAVITY FLOW FROM DWELLING 3' MIN COVER CLEANOUT SEE COE STD DTL SS-200 TYPICAL J SIDE SEWER TRACER WIRE SEE DETAIL "A" FOR CONNECTION IN THIS AREA FORCE MAIN 2" IPS POLY HI-MOL PIPE GRAVITY SEWER MAIN (200 PSI) GRINDER PUMP ASSEMBLY PROPERTY OWNER PUBLIC RIGHT-OF-WAY PER COE STD DTL SS-241 OR SS-242 NOTES: 1. WRAP AND TAPE 12 GAUGE TRACER WIRE EVERY 10' TO THE FORCE MAIN. 2. THE LOCATION OF THE STUB SERVICE TERMINATION SHALL BE MARKED BY THE CONTRACTOR WITH A 2"x4" TIMBER EXTENDED VERTICALLY FROM THE PLUG END TO GLUED - A MINIMUM OF 3 FEET ABOVE THE GROUND SURFACE. IN ADDITION: 2" FORCE MAIN • A 12-GAUGE GALVANIZED WIRE SHALL BE ATTACHED TO THE TIMBER FROM END TO END ENSURING THAT NEITHER THE WIRE NOR THE 2"x4" TIMBER SHALL BE 2" BRASS MIP x IPS w z J w a 0 a 6" SDR 35 PIPE ATTACHED TO THE SEWER PIPE OR PLUG. COMPRESSION FITTING 6" SD 35 SPIGOT • THE EXPOSED PORTION OF THE 2"x4" TIMBER SHALL WITH STAINLESS (W/ 6" GASKET) BE PRE -PAINTED TRAFFIC WHITE WITH THE WORDS STEEL INSERT x 4" SCH 40 HUB "GRINDER PUMP SEWER CONNECTION" STENCILED ON 4"x2" SCH 80 SLIP WITH BLACK PAINT. x THREAD BUSHING • THE END OF THE 2"x4" TIMBER SHALL BE PRE -MARKED IN PERMANENT INK WITH THE LENGTH DETAIL OF THE TIMBER INSTALLED. CITY INSPECTION REQUIRED PRIOR TO BACKFILL REVISION DATE a CITY OF EDMONDS GRINDER PUMP SERVICE SEPTEMBER 2023 CONNECTION TO PUBLIC WORKS GRAVITY SEWER MAIN STANDARD DEPARTMENT DETAIL FS t . 189�3 APPROVED BY: R. ENGLISH S S - 2 1 0 GRINDER PUMP SERVICE NOT TO SCALE SEE APPLICABLE STANDARD DETAILS FRAME AND GRATE PIPE ALLOWANCES PIPE MATERIAL MAXIMUM INSIDE DIAMETER REINFORCED OR 12" PLAIN CONCRETE ALL METAL PIPE 15" SOLID WALL PVC 15" (WSDOT STD SPEC 9-05.12.(1)) PROFILE WALL PVC 15" (WSDOT STD SPEC 9-05.12(2)) 5 2p 4 2 S 5 \2", 4", 6", OR 12" ?i NOTES: RISER SECTION 1. CATCH BASINS SHALL BE CONSTRUCTED IN ACCORDANCE WITH WSDOT STANDARD SPECIFICATION 9-05.50(3). 2. AS AN ACCEPTABLE ALTERNATIVE TO REBAR, WELDED WIRE 4y FABRIC HAVING A MIN. AREA OF 0.12 SQUARE INCHES PER > M/,y FOOT MAY BE USED. WELDED WIRE FABRIC SHALL COMPLY ?2, TO ASTM A497 (AASHTO M 221). WIRE FABRIC SHALL NOT 26 BE PLACED IN KNOCKOUTS. e 3. APPLY NON -SHRINK GROUT TO INSIDE AND OUTSIDE OF ALL JOINTS, RINGS, RISERS AND FRAMES. 4. ROUND KNOCKOUTS MAY BE ON ALL 4 SIDES, WITH MAX / DIAMETER OF 20". KNOCKOUTS MAY BE EITHER ROUND OR "D" SHAPE. a . 5. THE MAX DEPTH FROM THE FINISHED GRADE TO THE PIPE INVERT IS 5'-0 6. THE TAPER ON THE SIDES OF THE PRECAST BASE SECTION AND RISER SECTION SHALL NOT EXCEED 1/2"/FT. 7. CATCH BASIN FRAME AND GRATE SHALL BE IN ACCORDANCE WITH STANDARD SPECIFICATIONS. MATING SURFACES SHALL BE FINISHED TO ASSURE NON -ROCKING FIT WITH ANY COVER POSITION. (MEASUREMENT AT THE TOP OF THE BASE) 8. VERTICAL EDGE OF RISER SHALL NOT BE MORE THAN 2" PRECAST BASE SECTION FROM VERTICAL EDGE OF CATCH BASIN WALL. `St. 18y- TYPE I CB NOT TO SCALE CITY OF EDMONDS PUBLIC WORKS DEPARTMENT CATCH BASIN TYPE 1 APPROVED BY: R. ENGLISH GRIPPER PLUG SEE COE STD DTL SS-200 COLLAR 4" ABS/PVC INSERT PIPE* FLAPPER/ASSEMBLY FLAPPER 6" ABS/PVC FEMALE ADAPTER 6" ABS/PVC RISER PIPE* VALVE BODY FLOW CLEANOUT SEE COE STD DTL SS-200 6" SIDE SEWER WITHIN 2'-4' OF BUILDING 2' FLOW I 6" TO 4" REDUCER 4" SIDE SEWER REVISION DATE SEPTEMBER 2023 STANDARD DETAIL SD-303 STREET -SIDE HOUSE -SIDE * BOTH RISER PIPE AND INSERT PIPE CAN BE EXTENDED -CONTACT MANUFACTURER. NOTES: 1. THREADED PLUG, FEMALE ADAPTER, INSERT PIPE, AND RISER PIPE MAY BE SUPPLIED BY OTHERS. 2. BACKFLOW PREVENTER SHALL BE LOCATED FROM HOUSE BETWEEN 2' TO 4'. 3. BACKFLOW PREVENTER VALVE SHALL BE A CLEAN CHECK, INC. MODEL #: EBV-P401 OR EQUIVALENT. CITY OF EDMONDS SIDE SEWER BACKFLOW PREVENTER PUBLIC WORKS DEPARTMENT `St. 1Vy SEWER BACKFLOW PREVENTER NOT TO SCALE APPROVED BY: R. ENGLISH REVISION DATE JANUARY 2018 STANDARD D ETAI L SS-21 1 NOTES: 1. WATER DURING CONSTRUCTION WILL BE PROVIDED BY NEW 1" WATER METER INSTALLED IN EMPTY METER BOX. 2. UNDERGROUND WIRING REQUIREMENTS OF ECDC 18.05 SHALL BE FOLLOWED. ALL UTILITY SERVICES SHALL BE INSTALLED UNDERGROUND. 3. DRIVEWAY SLOPES SHALL NOT EXCEED 14% PER ECDC 18.80.060. 4. MINIMUM 3' HORIZONTAL SEPARATION AND 1' VERTICAL SEPARATION BETWEEN DRY UTILITIES AND SEWER, WATER, AND STORM, AND 5' FROM ANY CITY MAIN LINES. 5. FINAL RESTORATION WITHIN THE RIGHT-OF-WAY SHALL BE COMPLETED BY THE CONTRACTOR, NOT THE CITY OF EDMONDS. 6. EXISTING FAILING FRONTAGE IMPROVEMENTS SHALL BE REMOVED AND REPLACED AS DETERMINED BY THE CITY ENGINEERING INSPECTOR. 7. BNSF INSPECTION REQUIRED FOR BNSF OUTFALL. CITY OF EDMONDS WILL NOT BE RESPOPNSIBLE TO INSPECT THE OUTFALL PIPE, ANCHORS, AND DISCHARGE TO BNSF ROW. 8. INSTALL CONTROL PANEL ON EAST SIDE OF HOUSE FACING STREET. ELECTRICAL CONTRACTOR TO LOCATE WHERE IT FITS BEST. SEE SHEET A3.0. 9. HOSE BIB TO BE INSTALLED WITHIN 15' OF GRINDER PUMP SUMP. SEE SHEET A2.0. 10. SEWER CLEANOUTS SHALL HAVE A 12" CAST IRON LAMPHOLE COVER WITH J" HEX BOLTS AND A PICK HOLE AND CONCRETE PAD PER CITY OF EDMONDS STANDARD DETAIL SS-200. 11. FOR BNSF OUTFALL, GEOTECHNICAL INSPECTION OF EXCAVATIONS AND SUBGRADE CONDITIONS AT CONCRETE PIPE ANCHOR. 12. FOR BNSF OUTFALL, GEOTECHNICAL INSPECTION OF PIPE SURFACE ANCHORS TO VERIFY THE PIPE IS ADEQUATELY RESTRAINED. 13. IF UTILITY PATCHES ARE WITHIN 20' OF EACH OTHER, COMBINE PATCHES INTO A SINGLE PATCH. 14. FORCE LINE CONNECTION TO GRAVITY CONNECTION PER EDMONDS STD SS-210. CONNECTION SHALL NOT BE AT A 90' BEND. APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION I 3 1-10 � Q 110 O m) UL.L W qCo� z W It00 z 00 VJ - NCLOz Co O - c� z �11 0CE z W 00m 2 � T Uv � O 06 O 0) T W C 06 p� o C) 0 C LLI W 1: (0 o 0> 0 0 LLI E LU : - (f)>� _ 0 -1 0 J z T_ �W/•�� T W .� m Q U� 0 (%) I Q Ld W oU �z W U) 0 ui z � Q (D 0 z � 0 NQ CD z 0 0 N z -> O ui 0) w o' z 0 Q z 0 O O O N O z U) 0 0 (f) (f) 0 z 0 0 Lu drawn by checked by DP JDD scale date AS SHOWN 03/14/ job no. 2022117 sheet C3.1 of c� 0 z Q J I w c� Q z Q 0 0 z Q 0 z a CY CD r� 0 co z Q J w co z 0 cn w w (n z Q J I I 0 c� z CY w w z CD z w / N N O N / N N O N / 0 0 N O N I� 4X N STAINLESS STEEL VALVE EXTENSION HANDLE SIMPLEX PIPE TRACER WIRE 24" BASIN COVER JUNCTION BOX FASTENED TO WALL STRUCT PLASTIC STRUCT PLASTIC SST FASTENERS 1 1/2" CONDUIT r� 2" FINISHED GRADE FLANGE Z EY CONDUIT SEAL N (REQ'D BY OTHERS) ro ELECTRICAL "4 RAIL MOUNTING FLANGE � CONDUIT LIFTOUT CHAIN ANIT-SIPHON VALVE, PVC (IF REQ'D) AIR VENT CONNECT TO DWELLING TOP HOLDDOWN PLUMBING VENTILATION INLET FITTING, TYP RISER PIPE (FIELD INSTALLED) GRAVITY FLOW 4" INLET FROM DWELLING 2" HI-MOL POLY FORCE MAIN 2" BRASS MIP x IPS COMPRESSION FITTING WITH STAINLESS STEEL FIBERGLASS OR HIGH STIFFENER DENSITY POLYETHYLENE BASIN HIGH WATER "ALARM" LEVEL SHALL BE A MIN OF 6" BELOW GUIDE PLATE INVERT OF 4" SEWER INLET Z � PUMP "ON" LEVEL N e RAILS DISCHARGE PIPE PUMP "OFF" LEVEL d. SWING CHECK VALVE a & DISCONNECT ASSY GRINDER PUMP ° ° a a 4 ° DISCHARGE CASE da ANTI -FLOATATION PLATE .. OR FLANGE CONCRETE ANTI -FLOTATION BASE NOTES: 1. REFER TO CITY HANDOUT E62 FOR ADDITIONAL DESIGN AND PERMIT REQUIREMENTS. 2. ASSEMBLIES SHOULD NOT BE PLACED IN AREAS SUBJECT TO VEHICULAR TRAFFIC. IF LOCATED IN TRAFFIC AREAS, THE LID SHALL BE TRAFFIC RATED AND SHALL BE INSTALLED FLUSH IN ASPHALT OR CONCRETE. CITY INSPECTION REQUIRED PRIOR TO BACKFILL 24" SIMPLEX GRINDER REVISION DATE OCTOBER 2021 -CITY OF EDMONDS PUMP WITH REMOTE STANDARD PUBLIC WORKS MOUNTED CONTROL PANEL v DEPARTMENT DETAIL FSt. 189� SS-241 APPROVED BY: R. ENGLISH GRINDER PUMP NOT TO SCALE 100 95 85 75 70 0+00 105 100 95 85 80 0+00 RESIDENCE z J a 0 CLEANOUT a WITH 45' BEND AND CAP CLEANOUT (MAX) (n'P) NOT TO EXCEED 100' BETWEEN CLEANOUTS CLEANOUT (WYE WITH CAP AND CLEANOUT COVER) AND CONCRETE LEVELING COLLAR 2"t r-FINISHED GRADE 12" LOCKING COVER SEE NOTE 3 END OF PIPER GRIPPER PLUG (CHERNE 27061 OR APPROVED EQUAL) WATER TIGHT CAP LEVELING COLLAR J J SEE NOTE 4 45" RISER J/ 12" PVC SLEEVE 45' 131. 6" RISER y 6" WYE AND 6" CITY STUB 4" OR 6" SIDE SEWER 45' BEND GENERAL CLEANOUT DETAIL 4" OR 6" SIDE SEWER CLEANOUT DETAIL 12" LOCKING COVER AT PROPERTY LINE/CITY EASEMENT \� SEE NOTE 3 Ss � uJ X w LEVELING COLLAR j a- o w SEE NOTE 4 1. SEWER PIPE SHALL BE SDR-35 AND JOINTS SHALL BE IL a ASPHALT SURFACE GASKETED. 2. PIPE SLOPE TO BE 2Y MIN AND UP TO 50% MAX. 12" f 3. SEWER CLEANOUT TO BE 12" CAST IRON CLEANOUT COVER WITH 1/2" HEX BOLTS AND A PICK HOLE. EAST JORDAN 1 FOOT LONG 12" PVC IRON WORKS PRODUCT #00366102 OR APPROVED EQUAL. SLEEVE 6" RISER END OF PIPE GRIPPER 4. LEVELING COLLAR SHALL BE CONSTRUCTED AS FOLLOWS: PLUG (CHERNE 270261 IN ROADWAYS PER COE STD DWG GU-424 OR APPROVED EQUAL) • IN SIDEWALK/LANDSCAPED AREAS, EITHER 24"x24"x6" TYPICAL CLEANOUT DEEP CONCRETE COLLAR OR 24" DIAMETER x 6" DEEP UNDER ASPHALT OR CONCRETE CONCRETE COLLAR REVISION DATE CITY OF EDMONDS SEWER CLEANOUT DETAILS FEBRUARY 2023 PUBLIC WORKS STANDARD DEPARTMENT DETAIL FS t . 18g3 r APPROVED BY: R. ENGLISH SS-200 SEWER CLEANOUT NOT TO SCALE 0+50 1 +00 FORCEMAIN PROFILE — ONSITE CONNECTION SCALE: 1 "=10H, 1 "=5'V 0+50 1 +00 FORCEMAIN PROFILE — NEIGHBORLY CONNECTION SCALE: 1 "=10H, 1 "=5'V STREAM 6" MIN 5' MAX GROUND/FLOOR 1121911210-1 1. APPROVED PRESSURE VACUUM BREAKER ASSEMBLY MUST BE INSTALLED VERTICALLY, 6" MIN ABOVE THE HIGHEST POINT OF USE AND ALL DOWN STREAM PIPING 2. 6" MIN ABOVE FLOOD LEVEL FOR GENERAL PLUMBING 3. DESIGNED FOR BACK SIPHONAGE ONLY, NOT FOR BACK PRESSURE 4. THOROUGHLY FLUSH LINES PRIOR TO INSTALLATION OF BACKFLOW PREVENTER 5. IF AVB IS INSTALLED INDOORS, CONSIDERATION MUST BE GIVEN TO WATER LEAKAGE IF THE BACKFLOW PREVENTER FAILS (EXCESSIVE WATER SPILLAGE) 6. DO NOT INSTALL IN AN AREA SUBJECT TO FLOODING 7. MUST BE PROTECTED FROM FREEZING CONDITIONS B. THE BACKFLOW ASSEMBLY SHALL BE A STATE APPROVED MODEL 9. A PLUMBING PERMIT IS REQUIRED- OBTAIN PERMIT FROM CITY OF EDMONDS DEVELOPMENT SERVICES 10. NO DOWNSTREAM VALVES ARE ALLOWED 11. THIS DEVICE DOES NOT REQUIRE TESTING BY A BACKFLOW ASSEMBLY TESTER (ABOVE GROUND INSTALLATION ONLY) REVISION DATE ATMOSPHERIC/ANTI—SIPHON JANUARY 2018 CITY OF EDMONDS VACUUM BREAKER ASSEMBLY T PUBLIC WORKS (AVB) 2" AND SMALLER STANDARD DEPARTMENT DETAIL sy �g�0 APPROVED BY: R. ENGLISH WA— 165 ATMOSPHERIC VACUUM BREAKER NOT TO SCALE 1 +50 1 +50 105 100 95 85 80 1 +58 100 95 85 75 70 1+68 FIELD JOINT REQUIRED FOR MODELS DH151-129 / DR151-129 B DH151-160 / DR151-160 POWER/ALARM CABLE 6 CONDUCTOR W/GND NEMA 6P (EQD) QUICK DISCONNECT ASSY.— (304 S.S.) S.S. CAST BALL VALVE DISCHARGE 1 1/4' FPT 1 1/4' DISCHARGE LINE (304 S.S.) 43.9 in 1115 mm CHECK VALVE (NQRYL) ANTI -SIP ON VALVE (NQRYL POLYETHYLENE TANK 1/2" NOMINAL WALL THICKNESS 150 GALLON CAPACITY / SEMI -POSITIVE DISPLACEMENT TYPE PUMP DIRFCTI Y DRIVFN BY A 1 HP MOTOR WIRED OPTIONS :❑ DH 151 LEVELLRCONTROLS) ❑ DR 151 LEVELICONTROLS) GASKETED LID, HOPE STRAIN RELIEF CORD CONNECTOR / E/ONE EQUALIZER DUAL WALL, CORRUGATED HDPE ACCESSWAY INTERNAL WELL VENT 2.0' DIAMETER Y INLET, GROMMET TO ACCEPT 4.50' O.D. PVC PIPE (STANDARD). DUST COVER SUPPLIED FOR SHIPMENT (NOT SUITABLE FOR BURIAL) ALARM 38.4 in 975 mm 29 in ON 737 mm OFF ` 116 gal 439 L 21 in 17 in 534 mm 432 mm 84 gal 66 gal 318 L 1 250 L 0 38.8 in- mm CONCRETE BALLAST MAY BE REQUIRED SEE INSTALLATION INSTRUCTIONS FOR DETAILS NOTE: DIMENSIONS ARE FOR REFERENCE ONLY EONE GRINDER PUMP NOT TO SCALE BMP T5-13: U� DPI et NSF Op SOIL RETENTION RETAIN, IN AN UNDISTURBED STATE, THE DUFF LAYER AND NATIVE TOPSOIL TO THE MAXIMUM EXTENT PRACTICABLE. IN ANY AREAS REQUIRING GRADING, REMOVE AND STOCKPILE THE DUFF LAYER AND TOPSOIL ON SITE IN A DESIGNATED, CONTROLLED AREA, NOT ADJACENT TO PUBLIC RESOURCES AND CRITICAL AREAS, TO BE REAPPLIED TO OTHER PORTIONS OF THE SITE WHERE FEASIBLE. SOIL QUALITY ALL AREAS SUBJECT TO CLEARING AND GRADING THAT HAVE NOT BEEN COVERED BY IMPERVIOUS SURFACE, INCORPORATED INTO A DRAINAGE FACILITY OR ENGINEERED AS STRUCTURAL FILL OR SLOPE SHALL, AT PROJECT COMPLETION, DEMONSTRATE THE FOLLOWING: 1. A TOPSOIL LAYER WITH A MINIMUM ORGANIC MATTER CONTENT OF 10% DRY WEIGHT IN PLANTING BEDS, AND 5% ORGANIC MATTER CONTENT IN TURF AREAS, AND A PH FROM 6.0 TO 8.0 OR MATCHING THE PH OF THE UNDISTURBED SOIL. THE TOPSOIL LAYER SHALL HAVE A MINIMUM DEPTH OF EIGHT INCHES EXCEPT WHERE TREE ROOTS LIMIT THE DEPTH OF INCORPORATION OF AMENDMENTS NEEDED TO MEET THE CRITERIA. SUBSOILS BELOW THE TOPSOIL LAYER SHOULD BE SCARIFIED AT LEAST 4 INCHES WITH SOME INCORPORATION OF THE UPPER MATERIAL TO AVOID STRATIFIED LAYERS, WHERE FEASIBLE. 2. MULCH PLANTING BEDS WITH 2 INCHES OF ORGANIC MATERIAL. 3. USE COMPOST AND OTHER MATERIALS THAT MEET THE FOLLOWING ORGANIC CONTENT REQUIREMENTS: A. THE ORGANIC CONTENT FOR 'PRE —APPROVED" AMENDMENT RATES CAN BE MET ONLY USING COMPOST MEETING THE COMPOST SPECIFICATION FOR BMP T7.30: BIORETENTION, WITH THE EXCEPTION THAT THE COMPOST MAY HAVE UP TO 35% BIOSOLIDS OR MANURE. THE COMPOST MUST ALSO HAVE AN ORGANIC MATTER CONTENT OF 40% TO 65%, AND A CARBON TO NITROGEN RATIO BELOW 25:1. THE CARBON TO NITROGEN RATIO MAY BE AS HIGH AS 35:1 FOR PLANTINGS COMPOSED ENTIRELY OF PLANTS NATIVE TO THE PUGET SOUND LOWLANDS REGION. B. CALCULATED AMENDMENT RATES MAY BE MET THROUGH USE OF COMPOSTED MATERIAL MEETING (A.) ABOVE; OR OTHER ORGANIC MATERIALS AMENDED TO MEET THE CARBON TO NITROGEN RATIO REQUIREMENTS, AND NOT EXCEEDING THE CONTAMINANT LIMITS IDENTIFIED IN TABLE 220—B, TESTING PARAMETERS, IN WAC 173-350-220. THE RESULTING SOIL SHOULD BE CONDUCIVE TO THE TYPE OF VEGETATION TO BE ESTABLISHED. APPROVED FOR CONSTRUCTION l CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION `CGS. I Nc goo (p — 4 �o. 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EX :DITCFf ...:... : °. q::.....::..::....::........::........::........::........::........::........::........::........::........::........::........::........::........::...... .................W.I.L........................................................................................................................................................................ ...... .... , 15 0+00 0+50 1 +00 1 +50 2+00 2+48 DRAINS FOR STEEP SLOPES m a 8 12" Installation of the pipeline will be 0 _ _ - - � difficult due to the slope in which the ------- ° M --- pipe will be laid. Any damage to the ---- °--; o-° o'� slope due to construction must be • ,_, , _ o repaired to its original condition. A o , a i- large load on the conrete anchor which .____ a; V o supports the pipe at the top of the a a slope will result due to this installation. = - _ _ _ _ _ - = - ^"`.' ° - _ `- - - This anchor should be moved as far concrete collar � Undisturbed ground away from the face of the slope as Plan View possible to maximize its support capability. The pipeline should be de- signed to withstand the weight of the Ground line 6" Min. Cover ° - water within the pipe. . °:° See details below commonly used to •a Rebar ° ° ° ° support and hold the pipe in place, ` o a Elev. View which should be used for this install- = ° ' " 4" Max. ation. If the pipeline fails, it will be the owners responsibility to reinstall the _ = ,, °a pipeline. If damage occurs to railway a -° e, property due to the failure of the Undisturbed ground pipeline, the property owner will be PIPE ANCHOR DETAIL responsible for damages. The property owner must not deposit grass clippings, yard waste, trees or other debris on the slope at any time. •a u- shaped tabor bent to pipe If possible the diffus should be placed at the petty line. shape and placed not less thou 30" into ground at 25'intervols. C Clon-ps The diffuser mu a placed out of BNSF dr age ditch. Application show a cross - section dr of the ditch in g Maximum a" Pie p I relations ' to the existing Solid pipe and able track. a drawin must ive to withstand weight, Duolcobles. %" Minimum. I g g of water in entire pipe. both rizontal and vertical I dis ces with reference to X x e ing top of rail. L o' o R\ Place 3" 6" spalls : ` Cable Clamps around the pipe and around the ends fo. 1'/p" x Vie" Goly. Straps erosion control. , 0 a U yz" Steel Bolts �` ,a: y } 3 X - X 3' - Underdroin / Open Ends CLAMP DETAIL DIFFUSER NO TO SCAT E BURLINGTON NORTHERN & SANTA FE RAIL WA Y CO. o,, ,59B BNSF DRAINS FOR STEEP SLOPE NOT TO SCALE OUTFALL PIPE - AT TOP OF TIMBER PORTION OF WALL 8' LONG 4" PVC T-JUNCTION MIDAIR OVER EX BNSF DITCH OUTFALL PIPE PROFILE SCALE: 1'=10'H, 1'=10'V EX PILE/TIMBER WALL ALTERNATIVE TERMINATION DETAIL - MIDAIR T-JUNCTION NOT TO SCALE NOTE: GEOTECHNICAL INSPECTION OF EXCAVATIONS AND SUBGRADE CONDITIONS AT CONCRETE PIPE ANCHOR. GEOTECHNICAL INSPECTION OF PIPE SURFACE ANCHORS TO VERIFY THE PIPE IS ADEQUATELY RESTRAINED. BNSF TO PERFORM INSPECTION OF OUTFALL LINE. FOR FZE�']EFZEI�CE OlV]LX �'0]� �l�s�' ]P]PROVAL SON �� I N ��? � N • J `��d M � is 1� PR°� o I 5. N �G � E _ rn x o W 1, 0 o � 0 eucA� . (n U zW �o� W r to 0 — z �o� �� — U ♦♦^^ N C) VJ z c� o — I C� Z o 0 0 W m z_ N � I T J � U U — o 00 0 0T0 �,^J T V / �/ / w c o O0) -C J •— wI- W � E W c� 2 0 O U 0 C'� -U W W � �� U) (n w 0 �/� p J VJ 0 J �Wo � z T m ._ m J M CV 3 O Z 0 fn rn o W 5 w Of Z O F Z 0 X O O U cV 0 Z Q V) J Q III W U F-- Z W I I I 2 000 C_n 0 J LLI o J [f Z I— �0 O � L.t_ Cn 0 Z 0 m � N n drawn by checked by DP JDD scale date AS SHOWN 03/14/24 job no. 2022117 sheet \./ `t. � of Koh Residence Storm Drainage Report Appendix C — Geotechnical Report Page 14 NELSON GEOTECHNICAL ASSOCIATES. INC. June 23, 2022 Michael Koh Beng Chye c/o Nazim Nice Motionspace Architecture and Design VIA Email: nazim@motion-space.com Preliminary Geotechnical Engineering Evaluation Proposed Koh Residence 15604 — 75`h Place West Edmonds, Washington NGA File No. 1360822 Dear Mr. Koh: 17311-1351h Ave. N.E. Suite A-500 Woodinville, WA 98072 (425) 486-1669 www.nelsongeotech.com We are pleased to submit the attached report titled "Preliminary Geotechnical Engineering Evaluation — Proposed Koh Residence —15604 - 751h Place West —Edmonds, Washington." This report summarizes the existing surface and subsurface conditions within the project site, and provides preliminary geotechnical recommendations for design and construction of the proposed site improvements. Our services were completed in general accordance with the proposal signed by you on April 20, 2022. The site is situated on gently to steeply sloping ground that descends to the right-of-way for the Burlington Northern Santa Fe railroad and the shore of Puget Sound. Current project plans consist of constructing a multi -story single-family residence within the eastern portion of the property. Retaining walls and shoring systems may be needed to construct the proposed structure into the sloping ground. Specific grading, and utility plans were not available at the time this report was prepared. Stormwater management plans have also not been prepared at this time, but we expect that they will likely include tightlining the runoff down to the bottom of the slope. We should be retained to review final development plans prior to applying for a permit. The site is mapped as part of the large historic/prehistoric North Edmonds Earth Subsidence and Landslide Hazard Area and is located in the designated "Zone A" within the lower portion of the slide complex. This report provides information and discussion to fulfill the requirements of the City of Edmonds for construction within this area of Edmonds. It is important to recognize that the site and overall vicinity is part of this ancient landslide, and that development plans and future activity on this property should take that into consideration. Based on our site reconnaissance and explorations, and our understanding of the preliminary project plans, we have concluded that development on this site as proposed should be feasible, from a geotechnical standpoint. We did not observe indications of recent deep-seated slope instability on the property during our visit. The recommendations presented in this report should aid in maintaining and/or improving the current stability of the site. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Summary - Page 2 Because of the significant slide debris encountered in our explorations, we recommend supporting the entire planned residence on a deep foundation system consisting of drilled augercast piles in order to advance the structure loads through the loose/soft upper soils down to the more competent native deposits at depth. The augercast piles are intended to provide support for the residence and also provide an effective setback from the steep slopes within the lower portion of the property. Specific recommendations for foundation design and installation are provided in the attached report. Specific grading plans were not available at the time this report was prepared. Temporary or permanent shoring walls may be needed to support cut excavations for structure construction. These walls can ultimately be incorporated into the buildings as permanent retaining walls, if feasible. We recommend that all runoff generated within this site, including roof downspouts, driveways, yard and footing drains, and all runoff entering the property from the road, be collected in a tightline and routed to the bottom of the slope. If this alternative is not feasible, the collected water should be directed into the existing sewer system in the roadway. No water should be infiltrated or dispersed on or near the site slopes. Such activity may cause instability of the steep slopes. In the attached report, we have also provided general recommendations for site grading, structural slabs, structural fill placement, retaining walls, erosion control, and drainage. These recommendations are preliminary in nature. We should be retained to review and comment on final development plans and observe the earthwork phase of construction. We also recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. We appreciate the opportunity to provide service to you on this project. Please contact us if you have any questions regarding this report or require further information. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. �A� Khaled M. Shawish, PE Principal NELSON GEOTECHNICAL ASSOCIATES, INC. TABLE OF CONTENTS INTRODUCTION..........................................................................................................1 SCOPE........................................................................................................................ 2 SITECONDITIONS....................................................................................................... 3 SurfaceConditions....................................................................................................... 3 Subsurface Conditions.................................................................................................. 3 Hydrogeologic Conditions............................................................................................ 4 SENSITIVE AREA EVALUATION.................................................................................... 5 SeismicHazard............................................................................................................. 5 ErosionHazard............................................................................................................. 6 Landslide Hazard/Slope Stability.................................................................................. 6 CONCLUSIONS AND RECOMMENDATIONS.................................................................. 8 General......................................................................................................................... 8 Erosion Control and Slope Protection Measures....................................................... 10 StructureSetbacks..................................................................................................... 11 Site Preparation and Grading..................................................................................... 12 Temporary and Permanent Slopes............................................................................. 12 Soldier Pile Shoring Wall............................................................................................ 13 DeepFoundations...................................................................................................... 15 StructuralFill.............................................................................................................. 16 RetainingWalls........................................................................................................... 17 StructuralSlab............................................................................................................ 18 PavementSubgrade................................................................................................... 18 SiteDrainage.............................................................................................................. 18 USE OF THIS REPORT................................................................................................ 20 LIST OF FIGURES Figure 1— Vicinity Map Figure 2 — Site Plan Figure 3 — Cross -Section A -A' Figure 4 — Soil Classification Chart Figures 5 and 6 — Boring Logs Preliminary Geotechnical Engineering Evaluation Proposed Koh Residence 15604 — 75t" Place West Edmonds, Washington INTRODUCTION The property is roughly square in shape in shape and covers 0.6 acres in area. The parcel number for the property is 00513100002410. It is currently unoccupied and undeveloped. The property is bordered by 75th Place West to the east, by a residence to the south, by an undeveloped parcel to the north, and by a railroad right-of-way that separates the property from Puget Sound to the west. Topographically, roughly the northeastern half of the site slopes gently to moderately down to the west with a steep west -facing slope descending toward the railroad and then Puget Sound. We understand the proposed development will include the construction of a new single-family residence within the property. Critical areas including landslide hazard areas and erosion hazard areas have been mapped within the site. The site is also located within a designated Earth Subsidence and Landslide Hazard Area (ESLHA). We have been requested to provide this report for determination of geological hazards affecting the site, as well as development considerations for the proposed residence development. For our use in preparing this proposal, we were provided with a preliminary site plan. This plan shows two-story residence in the northeast portion of the site. A garage will be at the northeast corner of the first floor, and we understand a driveway along the east side of the residence will access the driveway. We anticipate that the west portion of the residence will be elevated above the ground surface. We also received a packet of several geotechnical documents concerning previously planned development within the property. The site is situated on gently to steeply sloping ground that descends from 75th Place West to the right- of-way of the Burlington Northern Santa Fe (BNSF) railroad and the shore of Puget Sound. We antipitate that the development will consist of constructing a multi -story, single-family residence within the upper, eastern portion of the property. Stormwater plans may include tightlining runoff down to the bottom of the slope. The current site layout is shown on the Site Plan in Figure 2. The site is mapped as part of the large historic/prehistoric North Edmonds Earth Subsidence and Landslide Hazard Area. Slide movement from both the large-scale slide complex and smaller localized slides within the complex can affect this property. The proposed residence design will have to take this into consideration. Preliminary Geotechnical Engineering Evaluation Proposed Koh Residence Edmonds, Washington SCOPE NGA File No. 1360822 June 23, 2022 Page 2 The purpose of this study is to explore and characterize the site surface and subsurface conditions, and provide opinions and recommendations for the proposed site development. Specifically, our scope of services includes the following: 1. Review available soil and geologic maps of the area as well as other relevant geotechnical information, as provided. 2. Explore the subsurface soil and groundwater conditions within the proposed development areas with two geotechnical boreholes using a limited -access drill rig. Drilling services were subcontracted by NGA. 3. Install two inclinometer casings in the drilled holes. 4. Map the conditions on the site slopes using shallow, hand -tool explorations where necessary to construct geological cross sections and qualitatively evaluate slope stability. 5. Perform laboratory grain -size sieve analysis on soil samples, as necessary. 6. Provide recommendations for structure setbacks from geologic hazards, as necessary. 7. Provide recommendations for earthwork and foundation support. 8. Provide recommendations for retaining walls, as warranted. 9. Provide recommendations for temporary and permanent slopes. 10. Provide recommendations for subsurface utilities and pavement subgrade preparation. 11. Provide our opinion on stormwater infiltration feasibility. 12. Provide general recommendations for site drainage and erosion control. 13. Document the results of our findings, conclusions, and recommendations in a written geotechnical report. continued on next page — NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation Proposed Koh Residence Edmonds, Washington SITE CONDITIONS Surface Conditions NGA File No. 1360822 June 23, 2022 Page 3 The site is situated on a west -facing slope overlooking Puget Sound. The property is currently undeveloped, but we understand that a house was formerly located within the property. A driveway has been cut into the site's southeast corner to provide access from 75th Place West. From 75th Place West, the ground declines into the site up to about 25 vertical feet at an inclination of 35 degrees (70 percent), with the height of this slope taller to the north. Below this slope, the ground surface slopes gently down to the west at a gradients of approximately 10 degrees (18 percent). From this gently sloping area that is roughly 70 feet wide, the site steepens and declines to the existing railroad tracks and Puget Sound at gradients in the range of approximately 20 to 37 degrees (36 to 75 percent). The existing site conditions, site topography, and interpreted subsurface conditions are presented on Cross - Section A -A' in Figure 3. The site is thickly vegetated with blackberry vines, ivy, brush, and scattered deciduous trees. The site is bordered to the north and south by residential properties, to the east by 75th Place West and to the west by the BNSF railroad tracks and Puget Sound. The existing site conditions are shown on the Site Plan in Figure 2. Subsurface Conditions Geology: The geologic units for the site vicinity are shown on the Preliminary Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington, by Mackey Smith (USGS, 1975). The site is mapped as old landslides (Qols) with Whidbey Formation deposits mapped nearby. The old landslide deposits are described as large slumps that occurred during the ablation of the Puget Lobe of the Vashon ice sheet by lowering of water -table level. The Whidbey Formation is described as nonglacial river flood plain deposits consisting of bedded layers of clay, silt, and sand with a few lenses of small pebbles. Our subsurface explorations generally encountered landslide deposits underlain by silt and fine sand that we interpreted as native Whidbey Formation soils. Explorations: The subsurface conditions within the site were explored on May 18, 2022 by drilling two borings using a limited -access drill rig to depths of approximately 41.0 and 41.5 feet below the existing ground surface. The approximate locations of our explorations are shown on the Site Plan in Figure 2. A Standard Penetration Test (SPT) was performed on each of the samples during drilling to evaluate relative soil density at depth. The SPT consists of driving a 2-inch outer -diameter, split -spoon sampler 18 inches using a 140-pound hammer with a drop of 30 inches. The number of blows required to drive the sampler the final 12 inches is referred to as the "N" value and is presented on the boring logs. The N value is used to evaluate the strength and density of the deposit. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 4 A geologist from NGA was present during the explorations, examined the soils and geologic conditions encountered, obtained samples of the different soil types, and maintained logs of the borings and hand augers. The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 4. The logs of our boring explorations are attached to this report and are presented as Figures 5 and 6. We present a brief summary of the subsurface conditions in the following paragraphs. For a detailed description of the subsurface conditions, the boring logs should be reviewed. Boring B-1 encountered silt with fine sand that was medium stiff at 2.5 feet, became medium stiff to stiff at 5 feet, stiff at 10 feet, and very stiff at 25 feet. We interpret these materials as landslide deposits, including blocks of intact materials. The boring continued into hard clayey silt at 30 feet, interpreted as native soils underlying the landslide deposits. Very dense sand was revealed at 36 feet, and continued to the base of the boring 41 feet below the surface. In Boring B-2, located in the upper part of the site, we observed loose sand with gravel to a depth of about 9.5 feet and then loose silty sand to sandy silt to about 13 feet. The upper loose soils were underlain by silt to sandy silt that was stiff to very stiff from 15 to 30 feet, and became hard at 35 feet. The hard silt continued to the explored depth of 41.5 feet. Inclinometer casing was installed in the lower boring, B-1, to a depth of 38 feet. The borehole was filled with cementitious grout after the inclinometer casing was installed. Hydrologic Conditions Groundwater seepage was not encountered in our explorations. However, some moist to wet zones were encountered, interpreted to result from groundwater collecting within sandier/less dense lenses. It is our opinion that there is also potential for a shallow perched water condition to develop. Perched water occurs when surface water infiltrates through less dense, more permeable soils and accumulates on top of relatively low permeability materials. The more permeable soils on this site would consist of the looser, surficial soils. The low permeability soil consists of the underlying silt. Perched water does not represent a regional groundwater "table" within the upper soil horizons. Perched water tends to vary spatially and is dependent upon the amount of rainfall. We would expect the amount of perched groundwater to decrease during drier times of the year and increase during wetter periods. However, there may be areas of seepage and wet soils on the slopes even in the drier times of the year. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 5 SENSITIVE AREA EVALUATION Seismic Hazard Older landslide debris and medium stiff to hard cohesive soils were encountered underlying the site at depth within the property. Based on the 2018 International Building Code (IBC), the site conditions best fit the description for Site Class D. Table 1 below provides seismic design parameters for the site that are in conformance with the 2018 IBC, which specifies a design earthquake having a 2% probability of occurrence in 50 years (return interval of 2,475 years), and the 2008 USGS seismic hazard maps. Table 1— 2018 IBC Seismic Design Parameters Site Class Spectral Acceleration Spectral Acceleration Site Coefficients Design Spectral at 0.2 sec. (g) at 1.0 sec. (g) Response Ss S1 Parameters Fa Fv Sos SM D 1.33 0.473 1 null 0.887 null Hazards associated with seismic activity include liquefaction potential and amplification of ground motion by soft or loose geologic deposits. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit beneath the groundwater table. It is our opinion that the medium dense/stiff or denser soils interpreted to underlie the site have a low potential for liquefaction or amplification of ground motion; however these materials could experience instability as a result of significant seismic activity. The competent cohesive soils interpreted to form the core of the site slopes at depth are considered stable with respect to deep-seated slope failures. However, the overlying loose surficial materials and landslide deposits have the potential for shallow sloughing failures during seismic events. Such events should not affect the planned residence provided our recommendations for foundation support are incorporated in the project designs. Hazards associated with seismic activity include liquefaction potential and amplification of ground motion by soft or loose geologic deposits. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit beneath the groundwater table. It is our opinion that the medium dense/stiff or better native soils interpreted to underlie the site have a low potential for liquefaction or amplification of ground motion; however these materials could experience instability as a result of significant seismic activity. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 6 Erosion Hazard The criteria used for determining the erosion hazard for the site soils includes soil type, slope gradient, vegetation cover, and groundwater conditions. The erosion sensitivity is related to the vegetative cover and the specific surface soil types, which are related to the underlying geologic soil units. The Soil Survey of Snohomish County Area, Washington, by the Soil Conservation Service (SCS), was reviewed to determine the erosion hazard of the on -site soils. The site surface soils were classified using the SCS classification system as Alderwood gravelly sandy loam, 15 to 30 percent slopes, and Alderwood-Everett gravelly sandy loams, 25 to 70 percent slopes. These soils are listed as having a severe erosion hazard. These soils should have a low to moderate hazard for erosion in areas that are not disturbed and where the vegetation cover is not removed. Landslide Hazard/Slope Stability The criteria used for the evaluation of landslide hazards include soil type, slope gradient, and groundwater conditions. The proposed development area within the east -central portion of the site slopes gently down to the west, at a gradient of approximately 10 degrees (18 percent). Continuing to the west, the terrain continues to slope moderately to steeply down to the west to the existing railroad tracks and Puget Sound at gradients of approximately 30 to 37 degrees (57 to 73 percent). The existing site conditions, site topography, and interpreted subsurface conditions are presented on Cross -Section A -A' in Figure 3. We did not observe groundwater seepage emitting from the site slopes during our site visit. We also did not observe any indications of recent slope movement or sloughing during our site visit. This site and the surrounding vicinity are within the ancient North Edmonds Earth Subsidence and Landslide Hazard area. The 2007 Landau Associates "North Edmonds Earth Subsidence and Landslide Hazard Area Summary Report, Edmonds, Washington" describes the landslide as a massive block of land that extends from the shore of Puget Sound to the steep bluffs several hundred feet to the east. In the 1980's, the City of Edmonds improved drainage in and around the North Edmonds landslide area to increase stability of the landslide block by lowering groundwater levels. The Landau Associates' report summarizes that large-scale movements of the landslide mass have not been documented since the 1950's. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 7 We were provided with a preliminary geotechnical report for a previously planned development at the site and the adjacent northern parcel by AESI dated October 24, 1997. That report describes a 2 to 3 foot tall fresh landslide scarp near the north edge of the adjacent parcel to the north and states that the ground below that scarp likely shifted the previous winter. The report describes another, overgrown scarp that was a few inches tall near the west side of the gently -sloping portion of the subject site. New development in the neighborhood has taken place in the form of single-family residences and roadways. Although the likelihood of the ancient slide to become active in the foreseeable future is low, extreme environmental conditions coupled with inadequate human practices could re -activate the ancient landslide. Such external factors could include severe and prolonged weather events and/or significant seismic activity. The site falls within 'Zone A" of the North Edmonds Earth Subsidence and Landslide Hazard Area Report prepared by Landau Associates for the City of Edmonds. This designation requires that certain features be included (or excluded) in the design. Such features include the restriction of cuts and fills, the need for tightlining runoff into an approved system, the need to design foundations and retaining walls to withstand high lateral earth pressures and potential loss of soil beneath parts of the foundation, the need to vegetate slopes with deeply rooted drought -tolerant vegetation, and the elimination of any and all irrigation systems. We have addressed these requirements in the remainder of this report. We encountered soils interpreted as landslide deposits to depths of about 30 feet within our explorations. Competent hard silt and very dense sand soils were encountered below this material within our explorations and we interpret the core of the slope at depth to consist primarily of this relatively stable material. Localized areas of surface instability and surface sliding can occur on steep slopes, particularly where modified through grading activities. Backwasting (movement of near -surface soil) through soil erosion processes or local surface slides is common to slopes, particularly where the soils are exposed to weathering. Normal surface erosion and shallow sloughing failures should be expected to continue on the steeply sloping portions of the site, but we have provided geotechnical recommendations for deep - foundation support, erosion control, and other development considerations that should reduce the potential impact of site development on the site slopes and the steep slopes to the west and below the proposed development area. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 8 CONCLUSIONS AND RECOMMENDATIONS General It is our opinion, from a geotechnical standpoint, that the site is compatible with the proposed development of a single-family residence provided that the geotechnical recommendations presented in this report are incorporated into project plans and followed during construction. However, it should be understood that there is some potential for movement of the historic landslide block that underlies and surrounds the site. Such movement could be triggered by extreme natural conditions and/or poor grading and/or drainage activities within the site and by other human activity in the general site vicinity. We recommend that foundation loads from the entire residence be supported on a deep foundation system consisting of augercast piles extending through the upper landslide debris and into the underlying undisturbed dense/hard soils at depth. This is further described in the Deep Foundations subsection of this report. It is important to understand that this is intended to be a preliminary report, and that additional geotechnical consultation will be required by the City of Edmonds to satisfy their code requirements. We anticipate that the City will require numerical slope stability analysis of the proposed development, which can be performed after a topographic survey of the existing conditions has been prepared and a grading plan showing the proposed ground surface has been developed. We should be also retained to review geotechnical aspects of the project plans, and to monitor earthwork and foundation system installation during construction. Additionally, we recommend that we be retained to periodically monitor the recently -installed inclinometer casing, which would detect slope movement within the site. In general, based on our review of historic documents and our subsurface explorations, the site currently appears fairly stable with respect to deep-seated movement. However, the site vicinity is mapped within an older landslide complex and our explorations encountered evidence of past ground movement. The potential for landslide and erosion hazards will depend on how the site is graded and how surface water and near surface water are controlled. We recommend that site grading be kept to a minimum and that grading and site drainage plans be subjected to geotechnical engineering review prior to construction. This review would include specific stability analysis of proposed cuts and fills and would provide recommendations for accomplishing the desired grading without reducing site stability. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation Proposed Koh Residence Edmonds, Washington NGA File No. 1360822 June 23, 2022 Page 9 We anticipate that the proposed residence will be setback at least 20 feet away from the top of the steep western slope. It is our opinion that this setback distance will reduce the potential for shallow sloughing events on the steep slope to impact the proposed residence, provided that our recommendations for deep foundations and erosion control management are followed. We further discuss the setbacks in the Structure Setbacks subsection of this report. Grading plans had not been prepared at the time of this report, but cuts may be needed to allow construction of the residence foundation. If these cuts cannot be sloped back to a safe inclination due to site constraints, we recommend that the cuts be shored with a soldier pile retaining wall or a similar system. The need for a shoring system should be determined during final design. This wall could be designed as a permanent wall and incorporated into the residence foundation. We provide recommendations for temporary and permanent cut slopes in the Temporary and Permanent Slopes section of this report. We also provide recommendations for soldier pile shoring walls in the Soldier Pile Shoring Wall subsection of this report. We recommend that any floor slab be designed as a structural slab and be supported on the deep foundation system. For other hard surfaces, such as paved areas or walkways that are supported on the existing soil, some risk of future settlement, cracking, and maintenance should be expected. To reduce this risk, we recommend over -excavating a minimum of two feet of the upper soil from those areas and replacing this material with compacted pit run or crushed rock structural fill. This recommendation is only for hard surfaces to be supported on grade and is not intended for the lower floor structural slab. Even with the recommended treatment, some settlement of the underlying loose material should be anticipated, which could result in distress of site improvements. The control of surface and near -surface water is very important for the long-term stability of the site and steep slopes. We highly recommend that temporary and final site grading be designed to direct surface water away from the structures and away from the steep site slopes. Final drainage plans have not been developed at this time, but we anticipate that all stormwater generated on the site will be collected in tightlines and transported to the bottom of the slope to the west of the property via a pipe anchored to the slope. No water should be infiltrated or dispersed within the site. We discuss general site drainage in the Site Drainage subsection of this report. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation Proposed Koh Residence Edmonds, Washington NGA File No. 1360822 June 23, 2022 Page 10 The soils encountered within our explorations are considered extremely moisture sensitive and will disturb easily when wet. We recommend that construction take place during extended periods of dry weather if possible. If construction takes place during wet weather, additional expenses and delays should be expected due to the wet conditions. Additional expenses could include the need to export on -site soil, the import of clean, granular soil for fill, and the need to place a blanket of rock spalls or crushed rock in the construction traffic areas and on exposed subgrades prior to placing structural fill or structural elements. In this report, we have also provided recommendations for drainage, erosion control, and other development considerations intended to reduce the potential impact of development on the site and the steep slope to the west. We should be retained to review final project plans prior to construction. We also recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. Erosion Control and Slope Protection Measures The erosion hazard for disturbed on -site soils is considered severe, but the actual hazard will be dependent on how the site is graded and how water is allowed to concentrate. Best Management Practices (BMPs) should be used to control erosion. Areas disturbed during construction should be protected from erosion. Erosion control measures may include diverting surface water away from the stripped or disturbed areas. Silt fences and/or straw waddles should be erected to prevent muddy water from leaving the site or flowing over the site slopes and the steep slope to the west of the property. Disturbed areas should be planted as soon as practical and the vegetation should be maintained until it is established. The erosion potential for areas not stripped of vegetation should be low to moderate. Also, irrigation systems should not be installed within the site. Protection of the slopes should be performed as required by the City of Edmonds. Specifically, we recommend that the slopes not be disturbed or modified through placement of any fill or future structures outside the planned development areas. No additional material of any kind should be placed on the steep slope or any portion of sloping ground, such as excavation spoils and soil stockpiles. Trees may be cut down and removed from the slopes as long as a mitigation plan is developed for maintaining slope stability, such as the replacement of vegetation for erosion protection. A vegetation cover should be preserved on the slopes outside the proposed development area. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 11 Replacement of vegetation should be performed in accordance with the City of Edmonds code. Under no circumstances should water be allowed to concentrate on the slopes. Any sloping areas disturbed during construction should be planted with vegetation as soon as practical to reduce the potential for erosion. Structure Setbacks Uncertainties related to building along the top of steep slopes are typically addressed by the use of building setbacks. The purpose of the setback is to establish a "buffer zone" between the structure and the top of the slope so that ample room is allowed for normal slope recession during a reasonable life span of the structure. In a general sense, the greater the setback, the lower the risk of slope failures to impact the structure. From a geological standpoint, the setback dimension is based on the slope's physical characteristics, such as slope height, slope gradient, soil type, and groundwater conditions. Other factors such as historical slope activity, rate of regression, and the type and desired life span of the development are important considerations as well. Based upon the conditions described above, it is our opinion that there is a potential for shallow sloughing -type failures and small-scale landslides to take place on the steeper site slopes, especially during wet weather. This condition can be exacerbated where water is present or where the slopes become locally very steep. Backwasting through sloughing of steep slopes can occur up the slope, such that a loss of ground could occur. We anticipate that the proposed residence may be setback at least 20 feet from the top of the steep slope within the western portion of the property. In our opinion, this setback distance is adequate; however, due to the potentially unstable debris found on the site and the history of the area, we have recommended that the residence be supported entirely on deep foundations in the form of augercast piles. We recommend that the piles extend a minimum of 5 feet into the competent hard or dense soils encountered below the landslide deposits. We anticipate that the piles will need to extend approximately 40 feet below the existing ground surface. Soil should not be stockpiled in any area between the top of the slope and the residence footprint. continued on next page — NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 12 Site Preparation and Grading Plans for site grading should minimize cuts and fills to reduce the potential to detrimentally impact site stability. Site preparation should consist of excavating the residence footprint and driveway areas down to planned elevations. If shoring walls are needed to support cut excavations, we recommend that the excavation for the building should only be attempted after the shoring systems are installed. Site preparation should also consist of stripping any organic topsoil and/or loose/soft soils in areas that will support pavement or structural fill. The stripped material should not be stockpiled in any area between the top of the slope and the residence footprint. If the exposed soils are loose/soft, they should be compacted to a non -yielding condition. Areas observed to pump or weave during compaction should be over -excavated and replaced with rock spalls. If significant surface water flow is encountered during construction, this flow should be diverted around areas to be developed and the exposed subgrade maintained in a semi -dry condition. In wet conditions, the exposed subgrade should not be compacted, as compaction of a wet subgrade may result in further disturbance of the soils. A layer of crushed rock may be placed over the prepared areas to protect them from further disturbance. The site soils are considered extremely moisture sensitive and will disturb easily when wet. We recommend that earthwork construction take place during periods of extended dry weather, and suspended during periods of precipitation if possible. If work is to take place during periods of wet weather, care should be taken during site preparation not to disturb the site soils. This can be accomplished by utilizing large excavators equipped with smooth buckets and wide tracks to complete earthwork, and diverting surface and groundwater flow away from the prepared subgrades. Also, construction traffic should not be allowed on the exposed subgrade. A blanket of rock spalls should be used in construction access areas if wet conditions are prevalent. The thickness of this rock spall layer should be based on subgrade performance at the time of construction. For planning purposes, we recommend a minimum one -foot thick layer of rock spalls. Temporary and Permanent Slopes Temporary cut slope stability is a function of many factors, including the type and consistency of soils, depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open and the presence of surface or groundwater. It is exceedingly difficult under these variable conditions to estimate a stable, temporary, cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations since he is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions encountered. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 13 The following information is provided solely for the benefit of the owner and other design consultants and should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job site safety. Job site safety is the sole responsibility of the project contractor. For planning purposes, we recommend that temporary cuts in the on -site material be no steeper than 2 Horizontal to 1 Vertical (2H:1V). If groundwater seepage is encountered, we would expect that flatter inclinations would be necessary. We should be retained to specifically review proposed geometry for significant cuts planned on this site. We recommend that cut slopes be protected from erosion. Erosion control measures may include covering cut slopes with plastic sheeting and diverting surface water runoff away from the top of cut slopes. We do not recommend vertical slopes for cuts deeper than four feet, if worker access is necessary. We recommend that cut slope heights and inclinations conform to appropriate OSHA/WISHA regulations. Permanent cut and fill slopes should be no steeper than 3H:1V. However, flatter inclinations may be required in areas where loose soils or seepage are encountered. Permanent slopes should be covered with erosion control matting and vegetated. The vegetative cover maintained until established. We should specifically review all plans for grading on this project. We do not recommend grading or filling on the remaining steep slopes outside the proposed building footprint, or placing irrigation systems near the slopes. Soldier Pile Shoring Wall General: Depending on overall heights of the proposed excavation, a solider pile shoring wall could be utilized to support cut excavations around the proposed structure. A solider pile wall typically consists of a series of steel H-beams placed vertically at a certain spacing from one another (typically six to ten feet). The beams are usually placed in drilled shafts that are filled with structural concrete or a lean mix. The concrete shafts are typically embedded below the bottom of the planned excavation a distance equals one to two times the exposed height of the wall. The steel beams extend above the finished ground surface to provide shoring capabilities for the area to be retained. The beams are typically spanned by pressure treated timber lagging or concrete panels. The H-beam size, shaft diameter, shaft embedment, and pile spacing are dependent on the nature of the soils anticipated to be retained by the wall and the soils at depth, wall height, drainage conditions, and the final geometry. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 14 Wall Design: The shoring wall should be designed by an experienced structural engineer licensed in the State of Washington. The lateral earth pressure acting on the shoring wall will be dependent on the nature and density of the soil behind the wall, structure and traffic loads on the wall, and the amount of lateral wall movement that may occur as material is excavated from the front of the wall. If the shoring wall is free to yield at least one -thousandth of the retained height, an "active" loading condition develops. If the wall is restrained from movement by stiffness or bracing, the wall is considered in an "at -rest" loading condition. Active and at -rest earth pressure can be calculated based on equivalent fluid densities. Shoring walls supporting a horizontal surface should be designed to resist a lateral load resulting from a fluid with a unit weight of 50 and 70 pounds per cubic foot (pcf) for the active and at -rest loading conditions, respectively. Higher values would be appropriate if the ground surface slopes behind the shoring. A uniform surcharge of 8H (in psf) should be applied to the wall design to account for seismic loading, if the shoring walls are intended to provide permanent support. H in this case, is the exposed height of the wall. These loads should be applied across the pile spacing above the excavation line. These loads can be resisted by a passive pressure of 150 pcf. The passive pressure should be applied on two -pile diameters under the excavation line. These values of the passive pressure incorporate a factor of safety of 2.0. The upper ten feet of pile embedment should be neglected when calculating the passive resistance for the permanent condition. If the proposed soldier pile walls are designed as temporary, we recommend that the embedded portion of the pile be a minimum of 1.5 times the height of the exposed portion of the wall. The above loads should be applied on the full center -to -center pile spacing above the base of the exposed portion of the wall. A fifty percent reduction of the active pressure could be applied for the purpose of designing the wall lagging. The above pressures assume that the on -site soils retained by the shoring wall are not significantly disturbed. These values do not include the effects of surcharges other than what is described above. The retained soils should be readily drained and collected water should be routed into a permanent storm system. Adequate gaps should be maintained between the lagging elements to allow for any potential water seepage buildup to flow through the wall. All voids behind the lagging should be filled with drain rock. The wall designer should calculate the predicted wall deflection, including deflection resulting from the below -grade movement of the piles. The predicted deflection values should be confirmed in the field through a survey monitoring program. Also, surrounding structures should be monitored for any adverse effects resulting from shoring wall installation. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 15 Shoring Wall Installation: The shoring wall should be installed by a shoring contractor experienced with this type of system. We recommend that the soldier piles be installed similarly to the augercast piles as described in the Deep Foundations subsection of this report. We should be retained to monitor on site activities during the shoring wall installation on a full-time basis. Deep Foundations We recommend that the entire residence be supported on 16- to 24-inch diameter augercast piles extending a minimum of five feet into competent native hard or dense soils to transfer foundation loads past the loose, near -surface landslide deposits. Based on our boring explorations, we anticipate that the piles will need to extend approximately 40 feet below the existing ground surface to achieve the recommended pier embedment into the competent native fine-grained soils. Augercast piles are installed with a hollow -stem auger advanced to the desired pile depth. After reaching a minimum recommended penetration into bearing soils, a pressure head is created when grout is pumped into the hollow stem of the auger before starting auger withdrawal. After the grout head is developed, withdrawal of the auger is timed to maintain the grout pressure head and avoid intrusion of loose soil into the sides of the pile excavation or discontinuity or "necking" of the pile. The actual volume of the concrete pumped into each pile is recorded and compared with the theoretical volume of the pile. Piles with a ratio of actual to theoretical great volume less than 1.1 should be re -drilled. The augercast piles should provide the necessary vertical support for the structure as well as some lateral resistance. The success of this method will depend, in part, on site access for the drill rig and other equipment needed for pile installation. Obstructed piles should be relocated and/or additional piles installed. Some discussion on relocation of piles should be made with your structural engineer prior to start of drilling. It is usually most economical to make any changes while the drill rig is on site. For preliminary pier design, we anticipate that the piles will need to extend approximately 40 feet below the existing ground surface to achieve the recommended embedment into the competent native soils that underlie the landslide materials. Design capacities for an 18-inch diameter augercast pile installed to a depth 40 feet below the existing ground surface can be 80, and 20 tons for axial compression and uplift capacities, respectively. If the piles will be utilized to resist uplift forces, the buoyant unit weight and adequate safety factors should be considered. Lateral resistance of the piles could be calculated based on an equivalent fluid density of 150 pounds per cubic foot (pcf) applied to two pile diameters. The upper 10 feet of loose soils should be neglected for the purpose of calculating the lateral resistance. We should be retained to review the augercast pile design and observe pile installation. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 16 Structural Fill General: Fill placed beneath pavements and other settlement -sensitive structures, or behind retaining walls should be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards and is monitored by an experienced geotechnical professional or soils technician. Field monitoring procedures would include the performance of a representative number of in -place density tests to document the attainment of the desired degree of relative compaction. The area to receive the fill should be prepared as outlined in the Site Preparation and Grading subsection of this report. Sloping areas to receive fill should be benched prior to fill placement. The benches should be level and at least four feet wide. Materials: Structural fill should consist of a good quality, granular soil, free of organics and other deleterious material and be well graded to a maximum size of about three inches. All-weather fill should contain no more than five -percent fines (soil finer than U.S. No. 200 sieve, based on that fraction passing the U.S. 3/4-inch sieve). We do not anticipate placement of significant volumes of structural fill for this project. The on -site soils consist of moisture -sensitive silty materials and slide debris. We recommend that the on -site material not be used as structural fill. We should be retained to evaluate the suitability of proposed structural fill materials at the time of construction. Fill Placement: Following subgrade preparation, placement of structural fill may proceed. All filling should be accomplished in uniform lifts up to eight inches thick. Each lift should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas and pavement subgrade should be compacted to a minimum of 95 percent of its maximum dry density. Maximum dry density, in this report, refers to that density as determined by the ASTM D-1557 Compaction Test procedure. The moisture content of the soils to be compacted should be within about two percent of optimum so that a readily compactable condition exists. It may be necessary to over - excavate and remove wet soils in cases where drying to a compactable condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 17 Retaining Walls Retaining walls may be incorporated into project plans to support below grade portions of the structure. The lateral pressure acting on subsurface retaining walls is dependent on the nature and density of the soil behind the wall, the amount of lateral wall movement which can occur as backfill is placed, wall drainage conditions, the inclination of the backfill, and other possible surcharge loads. For walls that are free to yield at the top at least one thousandth of the height of the wall (active condition), soil pressures will be less than if movement is limited by such factors as wall stiffness or bracing (at -rest condition). We recommend that walls supporting horizontal backfill and not subjected to hydrostatic forces be designed using a triangular earth pressure distribution equivalent to that exerted by a fluid with a density of 50 pcf for yielding (active condition) walls, and 70 pcf for non -yielding (at -rest condition) walls. These recommended lateral earth pressures are for a drained granular backfill and are based on the assumption of a horizontal ground surface behind the wall for a distance of at least the subsurface height of the wall, and do not account for surcharge loads. Additional lateral earth pressures should be considered for surcharge loads acting adjacent to subsurface walls and within a distance equal to the subsurface height of the wall. This would include the effects of surcharges such as traffic loads, floor slab and foundation loads, slopes, or other surface loads. Also, hydrostatic and buoyant forces should be included if the walls could not be drained. We could consult with the structural engineer regarding additional loads on retaining walls during final design, if needed. All wall backfill should be well - compacted; however, care should be taken to prevent the buildup of excess lateral soil pressures, due to over -compaction of the wall backfill. This can be accomplished by placing wall backfill in thin loose lifts and compacting it with small, hand -operated compactors within a distance behind the wall equal to at least one-half the height of the wall. The thickness of the loose lifts should be reduced to accommodate the lower compactive energy of the hand -operated equipment. Retaining walls that are part of the residence should be supported on augercast piles as described above. Retaining walls up to 3 feet tall should be supported on a minimum of two feet of rock spalls to reduce the potential for differential settlement of the walls. The active pressure on the wall can be resisted by friction on the bottom of the wall footing and passive resistance on the below -grade portion of the footing. Frictional resistance should not be considered for pile -supported walls. We recommend using a design soil bearing pressure of no more than 1,000 pounds per square foot (psf) along with a friction coefficient and passive resistance of 0.30 and 150 pcf, respectively. NGA should be retained to review the proposed retaining wall designs prior to finalizing plans. Permanent drainage systems should be installed for retaining walls. Recommendations for these systems are found in the Subsurface Drainage subsection of this report. We recommend that we be retained to evaluate the proposed wall drain backfill material and drainage system installation. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 18 Structural Slab As mentioned earlier, we recommend that the lower floor slab be designed as a structural slab fully supported on the deep foundation system. We recommend that slabs be underlain by at least six inches of free -draining gravel with less than three percent by weight passing the Sieve #200 for use as a capillary break. A suitable vapor barrier, such as heavy plastic sheeting (6-mil minimum), should be placed over the capillary break material. An additional 2-inch-thick moist sand layer may be used to cover the vapor barrier. This sand layer may be used to protect the vapor barrier membrane and to aid in curing the concrete; however, this sand layer is optional and is intended to protect the vapor barrier membrane during construction. Pavement Subgrade Pavement subgrade preparation should be completed as recommended in the Site Preparation and Grading and Structural Fill subsections of this report. Depending on the tolerance to pavement cracking, we recommend that the upper two feet of the existing material be removed and replaced with granular structural fill or crushed rock. The pavement subgrade should be proof -rolled with a heavy, rubber -tired piece of equipment, to identify soft or yielding areas that may require repair prior to placing any structural fill and prior to placing the pavement base course. We should be retained to observe the proof -rolling and recommend repairs prior to placement of the asphalt or hard surfaces. If the existing soil is left in place, the pavement section should be thickened to further reduce the effects of settlement. Site Drainage Surface Drainage: The finished ground surface should be graded such that stormwater is directed to an appropriate stormwater collection system. Water should not be allowed to collect in any area where footings, slabs, or retaining walls are to be constructed. Final site grades should allow for drainage away from the structure and away from the steep slopes. We suggest that the finished ground be sloped at a minimum gradient of three percent, for a distance of at least 10 feet away from the structure and slopes. Surface water should be collected by permanent catch basins and drain lines, and be discharged into an appropriate discharge system. Under no circumstances should water be allowed to flow uncontrolled over the site slopes or excavation walls. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation NGA File No. 1360822 Proposed Koh Residence June 23, 2022 Edmonds, Washington Page 19 We recommend that all stormwater generated on the site, including roof downspouts, footing drains, pavement and yard drains, and any water flow from the road, be tightlined to the bottom of the slope to the west. This should entail directing all collected runoff into a main catch basin placed at least 10 feet above from the top of the steep slope, from which a HDPE pipe should be extended to the bottom of the slope along the BNSF right-of-way. A concrete collar should be placed around the pipe between the catch basin and top of the slope to help anchor the pipe. The pipe should be laid on the slope surface but should be anchored using T-posts and metal straps. The pipe should end with a perforated tee section approximately eight feet long that is capped on both ends and embedded onto a crushed rock pad at the toe of the steep slope along the railroad tracks. The project civil engineer should design the size and alignment of the HDPE pipe, as well as other aspects of the stormwater system. Subsurface Drainage: If groundwater is encountered during construction, we recommend that the contractor slope the bottom of the excavations and collect water into ditches and small sump pits where the water can be pumped out of the excavations and routed into an appropriate outlet. We recommend the use of footing drains around the planned structure and behind retaining walls. Footing drains should be installed at least one -foot below planned finished floor elevation. The drains should consist of a minimum four -inch -diameter, rigid, slotted or perforated, PVC pipe surrounded by free -draining material, such as washed rock, wrapped in a filter fabric. We recommend that an 18-inch-wide zone of clean (less than three -percent fines), granular material be placed along the back of the walls above the drain. Washed rock is an acceptable drain material, or drainage composite may be used instead. The free -draining material should extend up the wall to one -foot below the finished surface. The top foot of backfill should consist of low permeability soil placed over plastic sheeting or building paper to minimize the migration of surface water or silt into the footing drain. Footing drains should discharge into tightlines leading to an appropriate collection and discharge point with convenient cleanouts to prolong the useful life of the drains. Roof drains should not be connected to footing drains. Roof drains should also be installed around the structure. Roof drains should consist of gutters and downspouts collecting stormwater runoff from the roof. The downspouts should discharge to catch basins and 4-inch minimum diameter, rigid, PVC tightline pipes. The drains should be directed into catch basins and then into the controlled drainage system. The footing and roof drains should discharge via independent (separate) tightlines into catch basins/cleanouts leading to the stormwater system. Surface water from the driveway and yard areas should also be collected in a catch basin and tightlined separately to the stormwater system. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation Proposed Koh Residence Edmonds, Washington NGA File No. 1360822 June 23, 2022 Page 20 USE OF THIS REPORT NGA has prepared this preliminary report for Michael Koh Beng Chye and associated agents, for use in the planning and design of the development planned on this site only. The scope of our work does not include services related to construction safety precautions and our recommendations are not intended to direct the contractors' methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions between the explorations and also with time. Our report, conclusions, and interpretations should not be construed as a warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the budget and schedule. We recommend that we be retained to review final project plans and provide consultation regarding specific structure placement, site grading, foundation support, and drainage. We also recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. We should be contacted a minimum of one week prior to construction activities and could attend pre -construction meetings if requested. All people who own or occupy homes on or near hillsides should realize that landslide movements are always a possibility. The landowner should periodically inspect the slope, especially after a winter storm. If distress is evident, a geotechnical engineer should be contacted for advice on remedial/preventative measures as soon as possible. The probability that landsliding will occur is substantially reduced by the proper maintenance of drainage control measures at the site (the runoff from the impervious surfaces should be led to an approved discharge point). Therefore, the homeowner should take responsibility for performing such maintenance. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering practices in effect in this area at the time this report was prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the owner. NELSON GEOTECHNICAL ASSOCIATES, INC. Preliminary Geotechnical Engineering Evaluation Proposed Koh Residence Edmonds, Washington NGA File No. 1360822 June 23, 2022 Page 21 We appreciate the opportunity to provide service to you on this project. If you have any questions or require further information, please call. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. Thor Christensen, PE Project Engineer M. p WA - i f 35215 I�Na� 6.23.2022 Khaled M. Shawish, PE Principal TRC:KMS:dy Six Figures Attached NELSON GEOTECHNICAL ASSOCIATES, INC. Ingo Development; Inc19 Norma Beach Rd ar & Gemar9 ■Restrob mAN �uri;a u� Wffarf Park 3 Q� r 3 Pa•�_:�is E'-�1ci:e�r__. � VICINITY MAP Not to Scale Abe Aalami 0 145th SI SW �a�th St sW W Pv e �s ,too"efthRd Norma Beach Home Care19 QApple Hardwood \48th PI SW Floors and Construction �8her Rd 1501h PI SW Project Site r _ ® Puget Sound video 1561h St SW 414o a 0 A Pa reenland Q 19 Mid -East China Consulting Corporation QNetwork Electric y A 152nd St SW Fairbank Animal Farm to Trailside at Meadowdale Beach 52,0, Meadowdale Photography 1561h SI SW Q Crozier Beach Park �G� 3 157th PI SW o. s n CG C �3 f m Energy Management 1601h St SW Services a a h g Northwest Cane Supply 1641h St SW 164th St SW Q QOxford House Meadowdale 1651h PI Skk . 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Schematic Site Plan _ z MOD PQ 3CT F;S CD • 94 0 rn CD CD fn C7 CD I Cn CD G > ■ CD_ 0 3 i m N� m cn vlDmOCn Cn � O o m —I C) • C=-i =_ Z LEGEND 0 ° - Property line B-1 + Number and approximate o location of boring A A' Approximate location W t t of cross-section D 0 A Reference: Site plan based on field measurements, C:\Users\DannyNelson\Nelson Geotechnical Associates, Inc\Nelson Geotechnical Associates, Inc - Co observations, and aerial parcel map review. noanv\2022 NGA Proiect\13608-22 Koh Residence Develooment B-1 A 3 � y f• 0 40 80 Approximate Scale: 1 inch = 40 feet A AN T ,o CD 05 0z CD rQ PQ m East West 120 120 0 n0 0 cn ch a. cn (D (/A 35° (D_ m 0 0 90 B-2 90 D m Sand (SW) B-1 D m 9 �i ? 6 ? �0 3 0 8 6 s 31° CD � � 25 s g ^' > 60 Silt (ML) 37° 60 w 28 J16 37 23 _ 76 y+ 36 ? L ? ? 30° 3 m r— < 30 Sand (SP) 0-6 35° 30 s,o a ;<: O Cn m= CA = 33° o a o cmn r�r7 0 0 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I >� n 0 30 60 90 120 150 180 210 240 Exploration Distance (feet) v d m Boring Designation B-1 23 <-- SPT N-value y Groundwater Level � 1 23 NOTES: 3 During Exploration 23 1) Stratigraphic conditions are interpolated between 23 Geologic Contact ? _ —? 2) the explorations. Actual conditions may vary. Elevations are arbitrary. o W (approximate) Reference: Cross Section is based on field measurements usinq a hand-held clinometer and 100-ft tape measure. W A n C:\Users\DannyNelson\Nelson Geotechnical Associates, Inc\Nelson Geotechnical Associates, Inc - Company\2022 NGA Project\13608-22 Koh Residence Development Edmonds\Drafting\CS.dwg UNIFIED SOIL CLASSIFICATION SYSTEM GROUP MAJOR DIVISIONS GROUP NAME SYMBOL CLEAN GW WELL -GRADED, FINE TO COARSE GRAVEL COARSE- GRAVEL GRAVEL GP POORLY -GRADED GRAVEL GRAINED MORE THAN 50 % GRAVEL GM SILTY GRAVEL OF COARSE FRACTION RETAINED ON SOILS NO.4 SIEVE WITH FINES GC CLAYEY GRAVEL SAND CLEAN SW WELL -GRADED SAND, FINE TO COARSE SAND SAND SP POORLY GRADED SAND MORE THAN 50 % RETAINED ON MORE THAN 50 % NO. 200 SIEVE OF COARSE FRACTION SAND SM SILTY SAND PASSES NO. 4 SIEVE WITH FINES SC CLAYEY SAND FINE - SILT AND CLAY ML SILT INORGANIC GRAINED LIQUID LIMIT CL CLAY LESS THAN 50 % SOILS ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY MH SILT OF HIGH PLASTICITY, ELASTIC SILT INORGANIC MORE THAN 50 % PASSES LIQUID LIMIT CH CLAY OF HIGH PLASTICITY, FAT CLAY NO. 200 SIEVE 50 % OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: 1) Field classification is based on visual SOIL MOISTURE MODIFIERS: examination of soil in general accordance with ASTM D 2488-93. Dry - Absence of moisture, dusty, dry to the touch 2) Soil classification using laboratory tests is based on ASTM D 2488-93. Moist - Damp, but no visible water. 3) Descriptions of soil density or Wet - Visible free water or saturated, consistency are based on usually soil is obtained from interpretation of blowcount data, below water table visual appearance of soils, and/or test data. Project Number nELSOn GEOTEnninl_ No. Date Revision By cK 1360822 Koh Residence Development Soil Classification Chart ' ASSOCIATES, inc ui W.o mvllle—.. Wenatchee—.. 1 1/8122 Original DPN ABR Figure 4 311 135th Ave. NE, A-500 105 Palouse St. Woodinville,WA98072 Wenatchee, WA 98801 www.nelsongeotech.com (425) 486-1669 / Fax: 481-2510 (509) 665-7696 / Fax: 665-7692 BORING LOG B-1 Soil Profile Sample Data Penetration Resistance (Blows/foot -) 10 20 30 40 50 50+ I I I I 0) N Piezometer Installation - Ground Water Description E o> J 0- �° o E 3 Q m Moisture Content (Percent - �) Data o COv L 0 O (Depth in Feet) c� U) co 10 20 30 40 50 50+ p J Light gray silt with fine sand and roots (medium stiff, moist) 5 -becomes medium stiff to stiff 8 5 1 ................................................... 5 -becomes gray, no wood content 8 ' 10 ....... ............................................ 10 -becomes stiff g ' -becomes clayey silt ML 11 ' 15 ........ ........................................... 15 11 ' 20 .................................................... 20 -becomes very stiff 23 ' 25 ................................................... 25 LEGEND ❑ Solid PVC Pipe Concrete M Moisture Content Limits Depth Driven and Amount Recovered 0 Slotted PVC Pipe Bentonite A AtterbergGrain-size P G Grain -size Analysis with 2-inch O.D. Split -Spoon Sampler Monument/ Cap Native Soil DS Direct Shear to Piezometer PP Pocket Penetrometer Readings, tons/ft Depth Driven and Amount Recovered ❑ Silica Sand P �k Liquid Limit P Sample Pushed with 3-inch Shelby Tube Sampler + Plastic Limit 1 Water Level T Triaxial NOTE: Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Project Number IIELSOtI GEOTECHnICAL No. Date Revision By CK 6/8/22 Original DPN ABRFigure 1360822 Koh Residence Development Log nASSOCIATES, II1C1 ,P-70 °.Weetllnvllla Office Wenatchee Office 17311-135th Ave. NE, A-500 105 Palouse 51. Woodinville, WA 98072 Wenatchee, WA 98801 5Boring Page1 2 g of www.nelsongeolech.wm (425) 486-1669 / Fax: 481-2510 (509) 665-7696 / Fax: 665-7692 N N O N 1 0 O 0 0 Q BORING LOG B-1 (cont.) Soil Profile Sample Data Penetration Resistance (Blows/foot - 10 20 30 40 50 50+ Piezometer Installation - �, Ground Water Description Q � �° o 3 Q m Moisture Content (Percent - �) Data @ o m v L o (Depth in Feet) c� U) co 0 CL 10 20 30 40 50 50+ p J -becomes hard 36 ML 78 ' 35 ................................................... 35 Gray -brown, fine to medium sand (very dense, moist) SP :.'. :•. " 40 ................................................... 40 50-6 Boring terminated at 41.0 feet below existing grade on 05/19/2022. Groundwater seepage was not encountered during drilling. 45 .................................................... 45 50 .................................................... 50 55 .................................................... 55 LEGEND ❑ Solid PVC Pipe Concrete M Moisture Content 0 Slotted PVC Pipe Bentonite A Atterberg Limits Depth Driven and Amount Recovered G Grain -size Analysis with 2-inch O.D. Split -Spoon Sampler Monument/ Cap Native Soil DS Direct Shear to Piezometer PP Pocket Penetrometer Readings, tons/ft Depth Driven and Amount Recovered ❑ Silica Sand P * Liquid Limit P Sample Pushed with 3-inch Shelby Tube Sampler + Plastic Limit 1 Water Level T Triaxial NOTE: Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Project Number IIELSOtI GEOTECHnICAL No. Date Revision By CK 1 6/8/22 Original DPN ABR 1360822 Koh Residence Development Boring Log SSOCIATES, incI1 ,P-70 °.Woodinville Office Wenatchee Office 17311-135th Ave. NE, A-500 105 Palouse 51. Woodinville, WA 98072 Wenatchee, WA 98801 Figure 5 Page2 2 g of www.nelsongeolech.wm (425) 486-1669 / Fax: 481-2510 (509) 665-7696 / Fax: 665-7692 N N O N 1 0 O 0 0 Q BORING LOG B-2 Soil Profile Sample Data Penetration Resistance (Blows/foot -) 10 20 30 40 50 50+ I I I I 0) N Piezometer Installation - Ground Water Description E o> J 0- �° o E 3 Q m Moisture Content (Percent - �) Data o CO v 0 L O (Depth in Feet) 0 U) cn 10 20 30 40 50 50+ p J Topsoil Brown, fine to coarse sand with gravel (loose, moist) . 5 -becomes very moist :... ,.. SW 5 5 .......................................... .... 5 9 — — — — — — — — — — — — — — — Red -brown to gray -brown, silty fine sand to fine, sandy ' — 10 10 silt (loose, moist) 6 .'•' SM Gray silt to fine, sandy silt with a 2 inch seam of wet fine sand (stiff to very stiff, moist) 18 -becomes fine, sandy silt to clayey silt, very stiff 25 ' 20 ................................................... 20 ML -becomes clayey silt, stiff 16 ' 25 ................................................... 25 LEGEND ❑ Solid PVC Pipe Concrete M Moisture Content Limits Depth Driven and Amount Recovered 0 Slotted PVC Pipe Bentonite A AtterbergGrain-size P G Grain -size Analysis with 2-inch O.D. Split -Spoon Sampler Monument/ Cap Native Soil DS Direct Shear to Piezometer PP Pocket Penetrometer Readings, tons/ff Depth Driven and Amount Recovered ❑ Silica Sand P �k Liquid Limit P Sample Pushed with 3-inch Shelby Tube Sampler + Plastic Limit 1 Water Level T Triaxial NOTE: Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Project Number IIELSOtI GEOTECHnICAL No. Date Revision By CK 1 6/8/22 Original DPN ABR 1360822 Koh Residence Development Boring Log SSOCIATES, incI1 ,P-70 °.Weetllnvllla Office Wenatchee Office 17311-135th Ave. NE, A-500 105 Palouse 51. Woodinville, WA 98072 Wenatchee, WA 98801 Figure 6 Page1 2 g of www.nelsongeolech.wm (425) 486-1669 / Fax: 481-2510 (509) 665-7696 / Fax: 665-7692 N N O N 1 0 O 0 0 Q BORING LOG B-2 (cont.) Soil Profile Sample Data Penetration Resistance (Blows/foot - 10 20 30 40 50 50+ Piezometer Installation - �, ` Ground Water Description Q o Q o o o c E m Moisture Content (Percent - �) a o m U L 0 O (Depth Feet) c� U) co 10 20 30 40 50 50+ -p J -becomes silt to clayey silt, very stiff 28 35 .................................................... 35 -becomes clayey silt, hard ML 37 ' 40 ............................................ ....... 40 76 Boring terminated at 41.5 feet below existing grade on 05/19/2022. Groundwater seepage was not encountered during drilling. 45 .................................................... 45 50 .................................................... 50 55 .................................................... 55 LEGEND ❑ Solid PVC Pipe Concrete M Moisture Content 0 Slotted PVC Pipe Bentonite A Atterberg Limits Depth Driven and Amount Recovered G Grain -size Analysis with 2-inch O.D. Split -Spoon Sampler Monument/ Cap Native Soil DS Direct Shear to Piezometer PP Pocket Penetrometer Readings, tons/ft Depth Driven and Amount Recovered ❑ Silica Sand P * Liquid Limit P Sample Pushed with 3-inch Shelby Tube Sampler + Plastic Limit 1 Water Level T Triaxial NOTE: Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Project Number IIELSOtI GEOTECHnICAL No. Date Revision By CK 1 6/8/22 Original DPN ABR 1360822 Koh Residence Development Boring Log SSOCIATES, incI1 ,P-70 °.Woodinville Office Wenatchee Office 17311-135th Ave. NE, A-500 105 Palouse 51. Woodinville, WA 98072 Wenatchee, WA 98801 Figure 6 Page2 2 g of ww.nelsongeolech.wm (425) 486-1669 / Fax: 481-2510 (509) 665-7696 / Fax: 665-7692 N N O N 1 0 O 0 0 Q Koh Residence Storm Drainage Report Appendix D — WWHM Report Page 15 WWHM2012 PROJECT REPORT General Model Information Project Name: RUN 01 Site Name: Site Address: City: Report Date: 11 /14/2023 Gage: Everett Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 0.800 Version Date: 2021 /08/18 Version: 4.2.18 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year RUN 01 11/14/2023 12:58:39 PM Page 2 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre PARKING MOD 0.2669 Impervious Total 0.2669 Basin Total 0.2669 Element Flows To: Surface Interflow Groundwater RUN 01 11/14/2023 12:58:39 PM Page 3 Mitigated Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre PARKING MOD 0.2669 Impervious Total 0.2669 Basin Total 0.2669 Element Flows To: Surface Interflow Groundwater RUN 01 11/14/2023 12:58:39 PM Page 4 Routing Elements Predeveloped Routing RUN 01 11/14/2023 12:58:39 PM Page 5 Mitigated Routing RUN 01 11/14/2023 12:58:39 PM Page 6 Analysis Results POC 1 p F )U 0 J iL 10E-5 10E-4 10E3 10E-2 10E-1 1 1ii loll Percent Time Exceetlir�g + Predeveloped Predeveloped Landuse Totals for POC #1 Total Pervious Area- 0 Total Impervious Area- 0.2669 Mitigated Landuse Totals for POC #1 Total Pervious Area- 0 Total Impervious Area- 0.2669 x Mitigated Flow Frequency Method- Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.106055 5 year 0.142777 10 year 0.169526 25 year 0.206203 50 year 0.235686 100 year 0.267081 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.106055 5 year 0.142777 10 year 0.169526 25 year 0.206203 50 year 0.235686 100 year 0.267081 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.107 0.107 1950 0.110 0.110 1951 0.138 0.138 1952 0.104 0.104 1953 0.121 0.121 1954 0.164 0.164 1955 0.133 0.133 1956 0.058 0.058 1957 0.089 0.089 1958 0.235 0.235 RUN 01 11/14/2023 12:58:39 PM Page 7 1959 0.098 0.098 1960 0.099 0.099 1961 0.303 0.303 1962 0.122 0.122 1963 0.118 0.118 1964 0.069 0.069 1965 0.094 0.094 1966 0.093 0.093 1967 0.194 0.194 1968 0.099 0.099 1969 0.205 0.205 1970 0.085 0.085 1971 0.106 0.106 1972 0.143 0.143 1973 0.115 0.115 1974 0.140 0.140 1975 0.113 0.113 1976 0.083 0.083 1977 0.083 0.083 1978 0.063 0.063 1979 0.129 0.129 1980 0.109 0.109 1981 0.084 0.084 1982 0.092 0.092 1983 0.112 0.112 1984 0.103 0.103 1985 0.140 0.140 1986 0.136 0.136 1987 0.124 0.124 1988 0.108 0.108 1989 0.094 0.094 1990 0.084 0.084 1991 0.110 0.110 1992 0.103 0.103 1993 0.082 0.082 1994 0.089 0.089 1995 0.080 0.080 1996 0.134 0.134 1997 0.115 0.115 1998 0.136 0.136 1999 0.055 0.055 2000 0.239 0.239 2001 0.067 0.067 2002 0.073 0.073 2003 0.101 0.101 2004 0.188 0.188 2005 0.081 0.081 2006 0.118 0.118 2007 0.109 0.109 2008 0.097 0.097 2009 0.081 0.081 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.3033 0.3033 2 0.2385 0.2385 3 0.2353 0.2353 RUN 01 11/14/2023 12:59:00 PM Page 8 4 0.2046 0.2046 5 0.1937 0.1937 6 0.1881 0.1881 7 0.1642 0.1642 8 0.1426 0.1426 9 0.1404 0.1404 10 0.1399 0.1399 11 0.1381 0.1381 12 0.1363 0.1363 13 0.1362 0.1362 14 0.1344 0.1344 15 0.1334 0.1334 16 0.1286 0.1286 17 0.1236 0.1236 18 0.1218 0.1218 19 0.1208 0.1208 20 0.1185 0.1185 21 0.1176 0.1176 22 0.1155 0.1155 23 0.1150 0.1150 24 0.1133 0.1133 25 0.1122 0.1122 26 0.1105 0.1105 27 0.1101 0.1101 28 0.1091 0.1091 29 0.1089 0.1089 30 0.1077 0.1077 31 0.1065 0.1065 32 0.1057 0.1057 33 0.1037 0.1037 34 0.1030 0.1030 35 0.1029 0.1029 36 0.1008 0.1008 37 0.0992 0.0992 38 0.0992 0.0992 39 0.0984 0.0984 40 0.0969 0.0969 41 0.0938 0.0938 42 0.0935 0.0935 43 0.0931 0.0931 44 0.0921 0.0921 45 0.0890 0.0890 46 0.0889 0.0889 47 0.0854 0.0854 48 0.0839 0.0839 49 0.0837 0.0837 50 0.0833 0.0833 51 0.0827 0.0827 52 0.0825 0.0825 53 0.0813 0.0813 54 0.0810 0.0810 55 0.0801 0.0801 56 0.0729 0.0729 57 0.0686 0.0686 58 0.0672 0.0672 59 0.0631 0.0631 60 0.0581 0.0581 61 0.0550 0.0550 RUN 01 11/14/2023 12:59:00 PM Page 9 RUN 01 11/14/2023 12:59:00 PM Page 10 Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail 0.0530 888 888 100 Pass 0.0549 784 784 100 Pass 0.0567 705 705 100 Pass 0.0586 624 624 100 Pass 0.0604 561 561 100 Pass 0.0623 505 505 100 Pass 0.0641 441 441 100 Pass 0.0659 397 397 100 Pass 0.0678 367 367 100 Pass 0.0696 334 334 100 Pass 0.0715 298 298 100 Pass 0.0733 279 279 100 Pass 0.0752 253 253 100 Pass 0.0770 240 240 100 Pass 0.0789 221 221 100 Pass 0.0807 203 203 100 Pass 0.0825 189 189 100 Pass 0.0844 167 167 100 Pass 0.0862 150 150 100 Pass 0.0881 142 142 100 Pass 0.0899 131 131 100 Pass 0.0918 123 123 100 Pass 0.0936 114 114 100 Pass 0.0955 108 108 100 Pass 0.0973 101 101 100 Pass 0.0992 97 97 100 Pass 0.1010 90 90 100 Pass 0.1028 84 84 100 Pass 0.1047 77 77 100 Pass 0.1065 69 69 100 Pass 0.1084 63 63 100 Pass 0.1102 56 56 100 Pass 0.1121 52 52 100 Pass 0.1139 47 47 100 Pass 0.1158 44 44 100 Pass 0.1176 40 40 100 Pass 0.1194 37 37 100 Pass 0.1213 34 34 100 Pass 0.1231 32 32 100 Pass 0.1250 31 31 100 Pass 0.1268 31 31 100 Pass 0.1287 29 29 100 Pass 0.1305 27 27 100 Pass 0.1324 26 26 100 Pass 0.1342 23 23 100 Pass 0.1361 21 21 100 Pass 0.1379 18 18 100 Pass 0.1397 17 17 100 Pass 0.1416 14 14 100 Pass RUN 01 11/14/2023 12:59:00 PM Page 11 0.1508 12 12 100 Pass 0.1527 11 11 100 Pass 0.1545 11 11 100 Pass 0.1563 11 11 100 Pass 0.1582 11 11 100 Pass 0.1600 10 10 100 Pass 0.1619 9 9 100 Pass 0.1637 9 9 100 Pass 0.1656 8 8 100 Pass 0.1674 8 8 100 Pass 0.1693 8 8 100 Pass 0.1711 8 8 100 Pass 0.1730 8 8 100 Pass 0.1748 8 8 100 Pass 0.1766 8 8 100 Pass 0.1785 8 8 100 Pass 0.1803 8 8 100 Pass 0.1822 8 8 100 Pass 0.1840 8 8 100 Pass 0.1859 8 8 100 Pass 0.1877 8 8 100 Pass 0.1896 7 7 100 Pass 0.1914 7 7 100 Pass 0.1933 6 6 100 Pass 0.1951 5 5 100 Pass 0.1969 5 5 100 Pass 0.1988 5 5 100 Pass 0.2006 5 5 100 Pass 0.2025 5 5 100 Pass 0.2043 5 5 100 Pass 0.2062 4 4 100 Pass 0.2080 4 4 100 Pass 0.2099 4 4 100 Pass 0.2117 4 4 100 Pass 0.2135 4 4 100 Pass 0.2154 4 4 100 Pass 0.2172 4 4 100 Pass 0.2191 4 4 100 Pass 0.2209 4 4 100 Pass 0.2228 4 4 100 Pass 0.2246 4 4 100 Pass 0.2265 4 4 100 Pass 0.2283 4 4 100 Pass 0.2302 4 4 100 Pass 0.2320 4 4 100 Pass 0.2338 4 4 100 Pass 0.2357 3 3 100 Pass RUN 01 11/14/2023 12:59:00 PM Page 12 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. RUN 01 11/14/2023 12:59:00 PM Page 13 LID Report LILTesYinique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Total Volume Infiltrated 0.00 0.00 0.00 0.00 0.00 0% No Treat. Credit Duration Compliance with LID Analysis Standard 8% of 2-yr to 50% of Result = 2 yr Passed RUN 01 11/14/2023 12:59:00 PM Page 14 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. RUN 01 11/14/2023 12:59:16 PM Page 15 Appendix Predeveloped Schematic asin 1 RUN 01 11/14/2023 12:59:16 PM Page 16 Mitigated Schematic asin 1 RUN 01 11/14/2023 12:59:18 PM Page 17 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 END GLOBAL FILES <File> <Un#> END FILES OPN SEQUENCE 2009 09 30 UNIT SYSTEM 1 <-----------File Name ------------------------------>*** *** INGRP INDELT 00:15 IMPLND 12 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FIL1 1 Basin 1 MAX END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO PYR DIG2 FIL2 YRND 1 2 30 9 <PLS ><------- Name ------- >NBLKS Unit -systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* END PRINT -INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** RUN 01 11/14/2023 12:59:19 PM Page 18 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** END PWAT-PARM4 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > Unit -systems Printer *** # - # User t-series Engl Metr *** in out *** 12 PARKING/MOD 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 12 0 0 1 0 0 0 END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 12 0 0 4 0 0 0 1 9 END PRINT -INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 12 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 12 400 0.05 0.1 0.08 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 12 0 0 END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 12 0 0 END IWAT-STATEI END IMPLND AGWRC AGWETP GWVS RUN 01 11/14/2023 12:59:19 PM Page 19 SCHEMATIC <-Source-> <Name> # Basin 1*** IMPLND 12 ******Routing****** END SCHEMATIC <--Area--> <-Target-> MBLK <-factor-> <Name> # Tbl# 0.2669 COPY 501 15 NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------ >< --- > User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT -INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------ ><-------- ><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><-------- > <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC -ACTIONS END SPEC -ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 0.8 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 0.8 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP RUN 01 11/14/2023 12:59:19 PM Page 20 END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <Name> <Name> # #<-factor-> <Name> MASS -LINK 15 IMPLND IWATER SURO 0.083333 COPY END MASS -LINK 15 END MASS -LINK END RUN <-Grp> <-Member->*** <Name> # #*** INPUT MEAN RUN 01 11/14/2023 12:59:19 PM Page 21 Mitigated UCI File RUN 01 11/14/2023 12:59:19 PM Page 22 Predeveloped HSPF Message File RUN 01 11/14/2023 12:59:19 PM Page 23 Mitigated HSPF Message File RUN 01 11/14/2023 12:59:19 PM Page 24 Disclaimer Legal Notice This program and accompanying documentation are provided 'as -is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by: Clear Creek Solutions, Inc. 2005-2023; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com RUN 01 11/14/2023 12:59:19 PM Page 25 Koh Residence Storm Drainage Report Appendix E — Operation and Maintenance Manual Page 16 Storm Drainage System Operations and Maintenance Manual For Koh Residence Snohomish County, WA Prepared by: Bush, Roed, & Hitchings, Inc. 15400 SE 301h Pl Ste 100 Bellevue, Washington (206) 323-4144 (206) 323-7135 (Fax) BRH Job No. 2022117 TABLE OF CONTENTS Introduction Functional Description of Units Operation and Maintenance Catch Basin Maintenance Energy Dissipator Maintenance General Information 2 7 Recommended Format for Maintenance Activity Log 8 INTRODUCTION This Storm Drainage System Operations and Maintenance Schedule is intended to provide guidance with respect to the maintenance of the private storm drainage systems contained on the Handley Residence. The storm drainage in place on -site are as follows: 1. Catch Basin Maintenance 2. Energy Dissipator It is the responsibility of the homeowners to ensure that all the drainage facilities contained on the property are in working order and that the maintenance personnel are following the recommendations within this manual. At the end of this manual is an example of a maintenance activity log. This log, or one similar, should be filled out any time that maintenance is performed upon the storm drainage systems. The log must be kept onsite in a location that is accessible to the city of Edmonds for inspection. FUNCTIONAL DESCRIPTION OF UNITS Catch Basins: • These units are located throughout the side (roads, etc.) and are identified typically by their vein -grate lids that collect surface runoff from the site. • The purpose of these units is to collect water for conveyance through attached pipe systems. These units contain a sump which collects sediment. • Failure to clean these units results in sediment buildup and plugging of the interconnecting pipes. Energy Dissipator: • A diffuser tee per the Burlington Northern Santa Fe Railroad (BNSF) Utility Accommodation Policy is used to dissipator stormwater collect from site at the bottom of the slope. • The tee will be located at the downstream end of a storm pipe adjacent to the southern and western property lines. • Failure to clean this unit may result in the facility to properly dissipate stormwater. 2 OPERATION AND MAINTENANCE Catch Basin Maintenance Inspect monthly and after storm events as needed Common Maintenance Considerations: The most common equipment for cleaning catch basins is a heavy-duty, combination power - washing and vacuum truck, also known as a vactor truck. It provides high-pressure washing for walls and the bottom of catch basins and a high -power vacuum for removing water that is mixed with sediment, oil, grease, gasoline, vegetation debris, and trash. Generally, this is the best and most effective way to clean catch basins. Table WAX: Maintenance Standards - Catch Basins Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed Trash or debris which is located immediately in front of the catch basin opening or is blocking inletting capacity of the basin by more than 10%. No Trash or debris located Trash or debris (in the basin) that exceeds 60 percent of the sump depth as immediately front of catch basin or on grate opening. measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of six inches clearance from the debris No trash or debris in the catch Trash & Debris surface to the invert of the lowest pipe. basin. Trash or debris in any inlet or outlet pipe blocking more than 1/3 of its height. Inlet and outlet pipes free of trash Dead animals or vegetation that could generate odors that could cause complaints or debris. or dangerous gases (e.g., methane). No dead animals or vegetation present within the catch basin. Sediment (in the basin) that exceeds 60 percent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in Sediment no case less than a minimum of 6 inches clearance from the sediment surface to No sediment in the catch basin the invert of the lowest pipe. General Top slab has holes larger than 2 square inches or cracks wider than 1/4 inch. Top slab is free of holes and Structure Damage to (Intent is to make sure no material is running into basin). cracks. Frame and/or Top Slab Frame not sitting flush on top slab, i.e., separation of more than 3/4 inch of the Frame is sitting flush on the riser frame from the top slab. Frame not securely attached rings or top slab and firmly attached. Maintenance person judges that structure is unsound. Basin replaced or repaired to Fractures or Cracks in Grout fillet has separated or cracked wider than 112 inch and longer than 1 foot at design standards. Basin Walls/ Bottom the joint of any inlet/outlet pipe or any evidence of soil particles entering catch Pipe is regrouted and secure at basin through cracks. basin wall. Settlement/ If failure of basin has created a safety, function, or design problem. Basin replaced or repaired to Misalignment design standards. Vegetation growing across and blocking more than 10% of the basin opening. No vegetation blocking opening to basin. Vegetation Vegetation growing in inlet/outlet pipe joints that is more than six inches tall and vegetation or root growth less than six inches apart. present. pr Contamination and Pollution See Table V-A.1: Maintenance Standards- Detention Ponds No pollution present. Cover Not in Place Cover is missing or only partially in place. Any open catch basin requires Cover/grate is in place, meets maintenance. design standards, and is secured Catch Basin Locking Mechanism Mechanism cannot be opened by one maintenance person with proper tools. Bolts Mechanism opens with proper Cover Not Working into frame have less than 1/2 inch of thread. tools. Cover Difficult to One maintenance person cannot remove lid after applying normal lifting pressure. Cover can be removed by one Remove (Intent is keep cover from sealing off access to maintenance.) maintenance person. Ladder Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, not securely attached to basin wall, Ladder meets design standards and allows maintenance person misalignment, rust, cracks, or sharp edges. safe access. Grate opening Unsafe Grate with opening wider than 7/8 inch. Grate opening meets design standards. Metal Grates (If Trash and Debris Trash and debris that is blocking more than 20% of grate surface inletting capacity. Grate free of trash and debris. Applicable) Grate is in place, meets the Damaged or Missing. Grate missing or broken member(s) of the grate. design standards, and is installed and aligned with the flow path. Energy Dissipator Maintenance Inspect every month and after storm events as needed Table V-A.7: Maintenance Standards - Energv Dissipators Maintenance Defect Conditions When Maintenance is Needed Results Expected When Components Maintenance is Performed External: Missing or, Moved Rock Only one layer of rock exists above native soil in area five square feet or Rock pad replaced to design larger, or any exposure of native soil. standards. Rock Pad Erosion Soil erosion in or adjacent to rock pad. Rock pad replaced to design standards. Pipe Plugged with Accumulated semenexceeds lated sediment that ds 20% of the design depth. Pipe cleaned/flushed so that it Sediment matches design. Not Discharging Water Visual evidence of water discharging at concentrated points along trench "sheet Trench redesigned or rebuilt to Property (normal condition is a (normalflow"- of water along trench). Intent is to standards. erosion damage. Dispersion Trench Perforations Plugged. Over 112 of perforations in pipe are plugged with debris and sediment. Perforated pipe cleaned or replaced. Water Flows Out Top of Maintenance person observes or receives credible report of water flowing Facility rebuilt or redesigned to "Distributor" Catch Basin. out during any storm less than the design storm or its causing or appears standards. likely to cause damage. Receiving Area Over- Water in receiving area is causing or has potential of causing landslide No danger of landslides. Saturated problems. Internal: Worn or Damaged Post, Structure dissipating flow deteriorates to 1/2 of original size or any Structure replaced to design Manhole/Chamber Baffles, Side of Chamber concentrated wom spot exceeding one square foot which would make standards. structure unsound. Other Defects See Table V-A.S: Maintenance Standards -Catch Basins See Table V-A.S: Maintenance Standards - Catch Basins DRA INS FOR STEEP SLOPES m n u 12" 0 Installation of the pipeline will be o difficult due to the slope in which the pipe will be laid. Any damage to the slope due to construction must be repaired to its original condition. A large load on the conrete anchor which >; o ° N supports the pipe at the top of the o slope will result due to this installation. _ _ °o _ °_ _ - This anchor should be moved as far Concrete Collar Undisturbed ground away from the face of the slope as Plan View possible to maximize its support capability. The pipeline should be de- signed to withstand the weight of the Ground line s" Min. Cover water within the pipe. ° See details below commonly used to +a Rebor support and hold the pipe in place, ` o ° o a Elev. View which should be used for this install- N a Max ation. If the pipeline fails, it will be the owners responsibility to reinstall the pipeline. If damage occurs to railway a ' _° property due to the failure of the Undisturbed ground pipeline, the property owner will be PIPE ANCHOR DETAIL responsible for damages. The property owner must not deposit grass clippings, yard waste, trees or other debris on the slope at any time. +a u- shaped rebar bent to pipe If possible the diffuser should be placed at the property line. shape and placed not less than 30" into ground at 25'intervals. Cable Clamps The diffuser must be placed out of BNSF drainage ditch. Application must show a cross - section drawing of the ditch in Maximum a" Pie P relationship to the existing Solid pipe and cble track. The drawin must ive to withstand weightDual cables. 3/e" Minimum. ; I ; g g of water in entire pipe. both horizontal and vertical distances with reference to 1IY existing top of rail. Lo' 'off , place the ?palls]d- around the pipe a Cable Clamps around the ends fol 1�/2" x 3/1s" Galy. Straps erosion control. d %y" Steel Bolts 3" X - X 3' _ Underdrain / Open Ends ------------ CLAMP DETAIL DIFFUSER NOT rO SCALE BURLINGTON NORTHERN & SANTA FE RAILWAY CO. °cr 1998 GENERAL INFORMATION The homeowners should become familiar with this manual and educate the appropriate personnel on the requirements. Inspection/maintenance items listed in this manual require different degrees of handling. The following general outline is offered to assist in setting up a program: 1. Items that should be accomplished by maintenance or contractor personnel: a. General site inspection of units. b. Cleaning out of trash and debris from pipes or facilities. c. Reporting of structural damage, sediment/sludge buildups, plugging, etc., to appropriate personnel. 2. Items that should be accomplished by maintenance or contractor personnel: a. Replacement of broken or damaged structures and/or structure components. b. Cleaning of sediment from pipes and drainage facilities. 7 MAINTENANCE ACTIVITY LOG Date Drainage Component Defect Maintenance Performed