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21-104309-Preliminary TIR-10-14-2021-V1 MIDWAY SAMOAN CHURCH Preliminary Technical Information Report MC# MAGA-0001 10/11/2021 MC# MAGA-0001 Preliminary Technical Information Report 10/11/2021 Midway Samoan Church i Drainage Report - MAGA0001 Preliminary Technical Information Report 10/11/2021 Prepared for: Magellan Associates Point of Contact: Jamie Trenda, Senior Project Manager Email: Jamie@MagellanArchitects.com Phone: (425) 885-4300 Owner’s Agent: Momentum Civil, LLC. 1145 Broadway, Suite 1150 Tacoma, WA 98402 Prepared by: Liam Ayers, E.I.T. Under the Direction of: Marc Pudists, P.E. Email: MarcP@MomentumCivil.com Phone: 253-319-1505 MC# MAGA-0001 Preliminary Technical Information Report 10/11/2021 Midway Samoan Church ii Drainage Report - MAGA0001 Table of Contents Table of Figures......................................................................................................................................................................... iv Table of Tables ........................................................................................................................................................................... iv Table of Appendices .............................................................................................................................................................. iv Section 1 - Project Overview ................................................................................................................................................ 1 Existing Conditions Summary ..................................................................................................................................... 3 Soils Properties ................................................................................................................................................................. 3 Floodplain Analysis ......................................................................................................................................................... 3 Critical Areas ....................................................................................................................................................................... 3 Proposed Conditions Summary ................................................................................................................................. 5 Section 2 – Conditions and Requirements Summary ....................................................................................... 7 Stormwater Core Requirement Summary .......................................................................................................... 7 Core Requirement #1 – Discharge at the Natural Location ...................................................................... 7 Core Requirement #2 - Offsite Analysis ................................................................................................................. 7 Core Requirement #3 – Flow Control Facilities ................................................................................................. 7 Core Requirement #4 – Conveyance System .................................................................................................... 7 Core Requirement #5 – Construction Stormwater Pollution Prevention (CSWPPP) ............... 8 Core Requirement #6 – Maintenance and Operations ................................................................................ 8 Core Requirement #7 – Financial Guarantees and Liability ..................................................................... 8 Core Requirement #8 – Water Quality Facilities .............................................................................................. 8 Core Requirement #9 – Flow Control BMPs ....................................................................................................... 8 Special Requirement #1: Other Adopted Area-Specific Requirements............................................. 8 Critical Drainage Area ................................................................................................................................................... 8 Master Drainage Plan ................................................................................................................................................... 8 Basin Plans .......................................................................................................................................................................... 9 Salmon Conservation Plans ...................................................................................................................................... 9 Stormwater Compliance Plans ............................................................................................................................... 9 Lake Management Plan .............................................................................................................................................. 9 Flood Hazard Management Plan .......................................................................................................................... 9 Shared Facility Drainage Plans ............................................................................................................................... 9 Special Requirement #2: Flood Hazard Area Delineation .......................................................................... 9 Special Requirement #3: Flood Protection Facilities .................................................................................... 9 Special Requirement #4: Source Controls ........................................................................................................... 9 Special Requirement #5: Oil Control ....................................................................................................................... 9 Section 3 – Offsite Analysis................................................................................................................................................ 14 MC# MAGA-0001 Preliminary Technical Information Report 10/11/2021 Midway Samoan Church iii Drainage Report - MAGA0001 Upstream Tributary Sub-basin .................................................................................................................................. 14 Downstream Analysis ...................................................................................................................................................... 14 Section 4 – Flow Control and Water Quality Analysis and Design .......................................................... 16 Performance Standards ................................................................................................................................................. 16 Existing and Developed Site Hydrology .............................................................................................................. 16 Wetland Volumetric Analysis................................................................................................................................. 16 Flow Control Facilities ..................................................................................................................................................... 16 Water Quality System ..................................................................................................................................................... 16 Section 5: Conveyance System Analysis and Design ....................................................................................... 16 Pipe Capacity Conveyance Analysis ....................................................................................................................... 17 Ditch Capacity Analysis .................................................................................................................................................. 17 Section 6: Special Reports and Studies..................................................................................................................... 18 Section 7: Other Permits .................................................................................................................................................... 18 Section 8: CSWPPP Analysis and Design ................................................................................................................ 18 ESC Plan Analysis and Design ................................................................................................................................... 18 CSWPP Plan Design ......................................................................................................................................................... 19 Section 9: Bond Quantities, Facilities Summaries, and Declaration of Covenant ........................ 20 Bond Quantities Worksheet ...................................................................................................................................... 20 Flow Control and Water Quality Facility Summary Sheet and Sketch ........................................... 20 Declaration of Covenant for Privately Maintained Flow Control and WQ Facilities ............... 20 Section 10: Operations and Maintenance Manual. ............................................................................................. 21 Project Information ........................................................................................................................................................... 21 System Description ............................................................................................................................................................ 21 Description of Stormwater Facilities ..................................................................................................................... 22 Cost Estimate for Maintenance ................................................................................................................................ 23 Stormwater Facility Maintenance Log ................................................................................................................ 24 List of Appendices ................................................................................................................................................................. 26 MC# MAGA-0001 Preliminary Technical Information Report 10/11/2021 Midway Samoan Church iv Drainage Report - MAGA0001 Table of Figures Figure 1: Vicinity Map .............................................................................................................................................................. 2 Figure 2: Existing Conditions Map ................................................................................................................................. 4 Figure 3: Proposed Basin Map .......................................................................................................................................... 6 Figure 4: Figure 1.1.2.A of the 2016 KCSWDM ....................................................................................................... 10 Figure 5: Table 1.1.2.A of the 2016 KCSWDM ..............................................................................................................11 Figure 6: City of Federal Way Flow Control Applications Map .................................................................... 12 Figure 7: City of Federal Way Water Quality Applications Map ................................................................. 13 Figure 8: Offsite Analysis Map .......................................................................................................................................... 15 Table of Tables Table 1: "V" Channel Ditch Capacity............................................................................................................................. 17 Table 2: 303d List for Bingamon Creek .................................................................................................................... 20 Table 3: Cost Estimate for Storm Maintenance (Puyallup Tribe of Indians) ...................................... 23 Table of Appendices Appendix A - Civil Engineering Plans ...................................................................................................................... A-1 Appendix B - Technical Information Worksheet .............................................................................................. B-1 Appendix C - Site Improvement Bond Quantity Worksheet .................................................................... C-1 Appendix D - WWHM Calculations ........................................................................................................................... D-1 Appendix E - Construction Stormwater Pollution Prevention Plan (C-SWPPP) .......................... E-1 Appendix F - USDA Web Soil Survey .........................................................................................................................F-1 Appendix G - Geotechnical Report ............................................................................................................................ G-1 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 1 of 26 Drainage Report - MAGA0001 Section 1 - Project Overview The proposed Midway Samoan Church project will replace the existing church with a new building for the church. The project is located on King County parcel numbers 0421049063 & 0421049032 at 29276 Military Road South in Federal Way, WA 98003. Parcel 0421049063 has a total lot size of 1.99 acres. Parcel 0421049032 has a total lot size of 0.49 acres. Please refer to Figure 1 on the next page for the project Vicinity Map. When complete, this project will include a church, a new parking lot, a new driveway connection to Military Road South, stormwater management systems, domestic water service, sanitary sewer connection to the proposed building, and associated grading and landscaping. Frontage improvements will include a new sidewalk along Military Road South. This project will utilize onsite stormwater BMPs to mitigate runoff generated by the new surfaces. Runoff generated by roofs, parking lot and onsite sidewalk will be collected and conveyed to an onsite stormwater detention system. Additionally, runoff generated from the parking lot and onsite sidewalk will be treated in a media filter device before it enters the onsite detention system. Stormwater generated from the sidewalk within the right-of-way will be collected in the roadside drainage ditch. Cleared and landscape areas will receive soil amendment per Section 16.82.100(G) of the King County 2016 Manual. This Technical Information Report discusses the applicable stormwater requirements and design calculations for the project. The design of the storm system has been prepared following the 2016 King County Stormwater Design Manual (KCSWDM) and the City of Federal Way Addendum to the 2016 KCSWDM, dated January 8th, 2017. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 2 of 26 Drainage Report - MAGA0001 Figure 1: Vicinity Map Project Site MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 3 of 26 Drainage Report - MAGA0001 Existing Conditions Summary The two subject parcels combine are an approximate area of 2.48 acres and is in Federal Way, Washington. The parcel is bound by Military Road South to the west and developed properties to the north, east, and south. Access will be provided to the site by means of a new driveway approach located on Military Road South. Parcel 0421049063 currently has an existing building with two gravel driveways and a gravel parking lot. Parcel 0421049032 currently has an existing singly family residence with a gravel driveway entrance and parking. Please see Figure 2 for representation of the existing conditions. Soils Properties According to the USDA Web Soil Survey, the project site is underlain by Alderwood Gravelly sandy loam. Please refer to Appendix F for the USDA Web Soil Survey Map for the project location. Additionally, a geotechnical engineering study has been prepared by The Riley Group, dated November 13, 2020, located in Appendix G which describes the soils within the project site as “two to seven feet of medium dense to dense fill comprised of sandy gravel, silty gravel with some sand, silty sand with varying amounts of gravel, and 5/8” minus crushed rock over native deposits of soft peat, stiff to very stiff silt with varying amounts of sand, and medium dense silty sand with varying amounts of gravel and sand with some silt and gravel. The geotechnical report states that the existing soils are not suitable for infiltration due to their low permeability rate and the presence of shall groundwater. Floodplain Analysis The project site is located outside the 100-year flood plain as identified by the FEMA FIRM panel 1235G of King County, Washington. Critical Areas Bingamon Creek is located along the eastern property line with a 100-foot buffer. Sanitary sewer connection to the proposed church will be the only disturbance within the 100-foot buffer and is not anticipated to impact the existing stream. Additionally, there is a wetland present in the eastern and northern region of the project site and has an 80-ft buffer from the mapped wetland. The client is preparing a wetland mitigation plan to allow for a 60-foot buffer. Sanitary sewer connection to the proposed church will be the only disturbance within the wetland buffer and is not anticipated to impact the existing wetland. Any disturbance in the buffer will be mitigated via the separate wetland mitigation plan. 1 0 0 ' S T R E AM B U F F E R 12" C O N C . C U L V E R T EL=42 2 . 1 5 'OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP OP OP OP OP OP OP OP OP OP OP OP MB T S P S S 2 4 5 6 7 EXIST I N G BUILD I N G GRAV E L GRAV E L EXIST I N G BUILD I N G CONC R E T E P A D COVE R E D RECR E A T I O N AREA DECK CONC . LAND S C A P I N G BORD E R CONC . LAND S C A P I N G BORD E R DECK CONC R E T E CONC . WALK W A Y STOR A G E CONT A I N E RCONCRETE ROADWAYASPHALT SHOULDERASPHALT SHOULDERASPHALTASPHALT SHOULDERCONCRETE ROADWAYCONC R E T E CENT E R L I N E O F DRAIN A G E D I T C H BUILD I N G EAVE/ O V E R H A N G TYP. BUILD I N G EAVE/ O V E R H A N G T Y P .MILITARY RD S9.7' 4.2' 8.4' 1.3'0.8'SHOULDERGRAV E L WL1-2 WL1-1 WL1-3 WL1-4 WL1-5 WL1-6 WL1-7 WL1-8 WL1-9 WL1-1 0 WL1-1 1 SL# 1 SL# 3 80' WETLAND BUFFER 41 2 412413414 413 41 4 413 414416417418419420421422423423423416 417418419420421422423424423424 41 6421423424425425424424424423422421420419418417416 416 416416417418419420421422423 SURFACE COVERAGE SUMMARY EXISTING POLLUTION GENERATING HARD SURFACE EXISTING NON POLLUTION GENERATING HARD SURFACE TOTAL HARD SURFACE EXISTING LANDSCAPING TOTAL AREA OF DISTURBANCE: FLOW ARROWS AREASURFACE DESCRIPTION 13,650 SQ. FT 6,900 SQ. FT 20,550 SQ. FT 28,770 SQ. FT 49,320 SQ.FT PROJECT NO. DRAWN BY: DESIGNED BY:DATENO.REVISION DESCRIPTIONCKBYDATE: SHEET NO.Save Date: Plot Date: 10/5/2021 12:48 PM10/5/2021 12:49 PMBy: LiamAyersP:\M\MAGA0001\0400CAD\Exhibits\EXI-COND-MAGA0001.dwgLiam AyersBy: File:CHECKED BY: 1145 BROADWAY, SUITE 115 TACOMA, WA 98402 PHONE: 253.319.1504 VERT. DATUM: HORZ. DATUM: REFERENCE NO. SW 1/4 OF NE 1/4 SECTION 4, TOWNSHIP 21N, RANGE 4E, W.M. MAGA0001 FIG. 2 X OF 1 10/7/2021 NAD83/11 NAVD88 FEDERAL WAY, WASHINGTONMIDWAY SAMOAN AG CHURCHMAGELLAN ARCHITECTSEXISTING CONDITIONS29276 MILITARY ROAD SOUTHKYLE M KYLE M MARC P PRELIMINARY DRAFT NORTH FIGURE 2 - EXISTING CONDITIONS MAP 1 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 5 of 26 Drainage Report - MAGA0001 Proposed Conditions Summary A new church will replace the existing church on the subject property. Hot mix asphalt will be used for the parking lot and driveway approach that connects to Military Road South. Onsite sidewalk will connect to new sidewalk along Military Road South. The proposed site improvements will have a storm drainage system that will provide both stormwater quantity and quality control in accordance with the 2016 KCSWDM and the City of Federal Way Addendum to the 2016 KCSWDM. Stormwater quantity control will be accomplished by utilizing full detention for all impervious. Full detention of impervious surfaces will be accomplished by use of Stormtech Detention Chambers. Enhanced basic water quality treatment will be provided by a media treatment device for the impervious pavement sections. Stormwater from the impervious pavement sections will be collected by the media treatment device and conveyed to the onsite detention system. See Section 4 of this report for further discussion of the stormwater quantity and quality control. Please see Figure 3 for representation of the proposed conditions. FDFDFDFDFDFDFD FD FD FD FD FD FD FD FD FD FDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFD RDRDRDRDRDRDRD RD RD RD RD RD RD RD RD RD RDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDXX X X X X X X X XXXXXXXXX X X XX COMPACTCOMPACTW W W W W W W WW W UGP UGP UGP UGP UGP UGP UGPUGP1 0 0 ' S T R E A M B U F F E R 12" C O N C . C U L V E R T EL=42 2 . 1 5 'OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP OP OP MB T S P S 2 4 3 5 6 7CONCRETE ROADWAYASPHALT SHOULDERASPHALT SHOULDERASPHALTASPHALT SHOULDERCONCRETE ROADWAYCENT E R L I N E O F DRAIN A G E D I T C H MILITARY RD SCURB & GUTT E R 9.7' 4.2' 8.4' 1.3'0.8'SHOULDERWL1-2 WL1-1 WL1-3 WL1-4 WL1-5 WL1-6 WL1-7 WL1-8 WL1-9 WL1-1 0 WL1-1 1 SL# 1 SL# 3 420 419418418419 417 416 418 419 41441541641741841942342242142042342242 1 424423422421420423419 418 417 416 41 9 41 8 41 7 4 1 6 419419420 421 42342242342342442442442542542642641 2 41 3 4 1 3 413412 4 1 3 413414 4144 1 5 4 1 4 415414414414415416417418419420421422423424423 422 421 420419 418 417 424423421422422422422 421420419418417416417418419420421422423 418418 419 4 1 64174184 1 9 4 2 0421 41 6 SURFACE COVERAGE SUMMARY POLLUTION GENERATING HARD SURFACE NON POLLUTION GENERATING HARD SURFACE TOTAL HARD SURFACE LANDSCAPING TOTAL AREA OF DISTURBANCE: FLOW ARROWS AREASURFACE DESCRIPTION 13,350 SQ. FT 16,245 SQ. FT 29,595 SQ. FT 19,725 SQ. FT 49,320 SQ.FT PROJECT NO. DRAWN BY: DESIGNED BY:DATENO.REVISION DESCRIPTIONCKBYDATE: SHEET NO.Save Date: Plot Date: 10/5/2021 5:26 PM10/7/2021 3:34 PMBy: LiamAyersP:\M\MAGA0001\0400CAD\Exhibits\PRO-COND-MAGA0001.dwgLiam AyersBy: File:CHECKED BY: 1145 BROADWAY, SUITE 115 TACOMA, WA 98402 PHONE: 253.319.1504 VERT. DATUM: HORZ. DATUM: REFERENCE NO. SW 1/4 OF NE 1/4 SECTION 4, TOWNSHIP 21N, RANGE 4E, W.M. MAGA0001 FIG. 3 1 OF 1 10/11/2021 NAD83/11 NAVD88 FEDERAL WAY, WASHINGTONMIDWAY SAMOAN AG CHURCHMAGELLAN ARCHITECTSPROPOSED CONDITIONS29276 MILITARY ROAD SOUTHKYLE M KYLE M MARC P NORTH FIGURE 3 - PROPOSED CONDITIONS MAP 1 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 7 of 26 Drainage Report - MAGA0001 Section 2 – Conditions and Requirements Summary Stormwater Core Requirement Summary Figure 1.1.2.A of the 2016 King County Surface Water Design Manual was used to determine that a full drainage review is necessary for the project. The flow chart and selection process are provided in Figure 4. The requirements for a full drainage review are listed in Table 1.1.2.A of the 2016 King County Surface Water Design Manual which is provided in Figure 5 The project will comply with Core Requirements #1 through #9 and Special Requirements #1 through #5. Each requirement is listed below with a discussion of how the project will comply with these requirements (if applicable to the project). Core Requirement #1 – Discharge at the Natural Location In the existing conditions, runoff from the project site flows overland into the wetland in the western and northern region of the project site. Runoff then enter the existing stream that is located along the eastern property line. In the developed condition, runoff is collected and conveyed to the onsite detention system. Once the runoff exits the detention system is discharged to the existing wetland on the project site and consequently reaches Bingamon Creek on the eastern property line. Core Requirement #2 - Offsite Analysis See Section 3 for discussion of the Offsite Analysis. Core Requirement #3 – Flow Control Facilities Based on review of the City of Federal Way Flow Control Applications Map (Figure 6), the site is located within a Conservation Flow Control Area. Per Table 1.2.3.A of the KCSWDM, Level 2 flow control is applicable for Conservation Flow Control Areas with no downstream problems. Level 2 flow control dictates that all targeted surfaces in the developed condition must match historic durations for 50% of the 2-yr through 50-yr peaks and must match the historic 2- and 10-year peaks. Level 2 control is being me for all targeted surface in the developed conditions – See Appendix D for WWHM Calculations. Core Requirement #4 – Conveyance System This project will collect runoff from the impervious pavement sections and convey it to the onsite detention system. Once Runoff leaves the detention system is conveyed to a catch basin where runoff is discharged through a 20-foot linear dispersal trench. The proposed collection system has been designed to convey and contain (at a minimum) the 25-year peak flow. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 8 of 26 Drainage Report - MAGA0001 Core Requirement #5 – Construction Stormwater Pollution Prevention (CSWPPP) A Construction Stormwater Pollution Prevention Plan will be prepared prior to final submittal. Core Requirement #6 – Maintenance and Operations The drainage facilities constructed as part of this project will be maintained privately. The maintenance requirements for the proposed facilities are included in Section 10. Core Requirement #7 – Financial Guarantees and Liability This will be addressed at the final engineering stage. Core Requirement #8 – Water Quality Facilities Based on review of the City of Federal Way Water Quality Applications Map (Figure 7), the site is located within a Basic Enhanced Treatment Area. To meet this requirement, a GULD certified media treatment device is proposed for treatment of runoff from the pollution generating hard surfaces for this project. The media treatment device was sized using the offline 6-month water quality flow rate reported by WWHM (0.0313 cfs). Further details for the sizing of the facility are provided in Section 4 of this report and the WWHM sizing calculations are included within Appendix D. Core Requirement #9 – Flow Control BMPs Implementation of flow control BMPs must occur as part of the proposed project, which falls under full drainage review requirements. Detention will be implemented through Stormtech chambers for all proposed impervious surfaces. A 20-foot linear dispersion trench will also be implemented for the outfall from the detention system. Special Requirement #1: Other Adopted Area-Specific Requirements Critical Drainage Area Bingamon Creek is located along the eastern property line with a 100-foot buffer. Sanitary sewer connection to the proposed church will be the only disturbance within the 100-foot buffer and is not anticipated to impact the existing stream. Additionally, there is a wetland present in the eastern and northern region of the project site and has an 80-ft buffer from the mapped wetland. The client is preparing a wetland mitigation plan to allow for a 60-foot buffer. Sanitary sewer connection to the proposed church will be the only disturbance within the wetland buffer and is not anticipated to impact the existing wetland. Any disturbance to the wetland buffer will be addressed by the wetland mitigation plan. Master Drainage Plan No special drainage requirements are applicable to this project. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 9 of 26 Drainage Report - MAGA0001 Basin Plans The project site is in the Lower Green River Basin which is tributary to Elliot Bay. Salmon Conservation Plans Not applicable to this project, as no salmonid or salmon bearing waters will be impacted. Stormwater Compliance Plans Not applicable. Lake Management Plan Not applicable to this project. Flood Hazard Management Plan Not applicable to this project, as the project site is not within a mapped flood zone. Shared Facility Drainage Plans Not applicable to this project. Special Requirement #2: Flood Hazard Area Delineation Not applicable. This project is not mapped as being within the limits of the 100-year flood plain, zero-rise flood fringe, zero-rise floodway, FEMA floodway or channel migration zones. Special Requirement #3: Flood Protection Facilities Not applicable. Special Requirement #4: Source Controls Source controls will be limited to those materials typical for a commercial building project. Special Requirement #5: Oil Control Not applicable as this is not a high-use site because ADT is less than 10,000. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 10 of 26 Drainage Report - MAGA0001 Figure 4: Figure 1.1.2.A of the 2016 KCSWDM MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 11 of 26 Drainage Report - MAGA0001 Figure 5: Table 1.1.2.A of the 2016 KCSWDM MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 12 of 26 Drainage Report - MAGA0001 Figure 6: City of Federal Way Flow Control Applications Map Project Site MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 13 of 26 Drainage Report - MAGA0001 Figure 7: City of Federal Way Water Quality Applications Map Project Site MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 14 of 26 Drainage Report - MAGA0001 Section 3 – Offsite Analysis Upstream Tributary Sub-basin The proposed project will have an upstream tributary sub-basin that is a part of Military Road South. Runoff from the upstream sub-basin will be collected and conveyed through a drainage ditch along Military Road South. Runoff then enters a culvert that goes under the new sidewalk within the right-of-way. Once runoff exits the culvert it travels within a swale in the southern region of the project and discharges to the existing wetland. Downstream Analysis A Level 1 Downstream Analysis was conducted for the site. The analysis follows the four tasks required for a downstream analysis. Task 1: Define and map the study area The study area for the downstream analysis consists of the project site, the existing wetland, and Bingamon Creek along the eastern property line. Task 2: Review all available information on the study area Mapping and stormwater records (including complaints) from King County and from the City of Federal Way were reviewed as part of the downstream analysis. Task 3: Field inspect the study area Momentum Civil engineering staff walked the downstream on multiple occasions during October of 2020 during both rainy and sunny days. Task 4: Drainage System Description and Problem Descriptions Runoff will be collected, treated and discharged into the wetland present onsite which eventually outflows to Bingamon Creek. No severe flooding problems were identified on site or within ¼ mile downstream of the site. There are no known drainage complaints noted for the parcel with King County. There are no known severe erosion, or severe flooding problems on the project site or within ¼ mile downstream of the site. There is a wetland located in the eastern and north region of the project site. Please refer to Section 4 of this report for further information regarding volumetric fluctuations and analysis for the wetlands. Please see Figure 8 for representation of the Offsite Qualitative Analysis. Figure 8 - Offsite Analysis Map Project Site Project Discharge Point Bingamon Creek 1/4 Mile (1,320 feet) Downstream MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 16 of 26 Drainage Report - MAGA0001 Section 4 – Flow Control and Water Quality Analysis and Design Per Core Requirements #3 and #8, flow and water quality control are applicable for this project. Performance Standards The following Flow Control and Water Quality treatment standards apply to this project: • Level 2 Flow Control • Enhanced Basic Treatment Existing and Developed Site Hydrology Since the proposed development will implement detention and dispersion, the existing hydrology of the site will be maintained. Please refer to Figure 2: Existing Conditions Map and Figure 3: Proposed Basin Map for representation of the project basin boundaries and the proposed storm management system. Wetland Volumetric Analysis In the existing condition, the wetland present on this project site has a tributary area of 15.22 acres with roughly 6.26 acres of impervious surface. In the existing and developed conditions the tributary area consists of developed parcels, military road south, and some forested areas. In the developed condition, the amount of impervious surface tributary to the wetland will be increasing by 0.2 acres (an impervious area increase of 3.1%). Please refer to Appendix D for the WWHM wetland volumetric fluctuation results between the proposed and existing conditions. Flow Control Facilities For this project, all impervious surface runoff will be collected and conveyed to Stormtech detention chambers prior to discharge through a linear dispersion trench. Please Appendix D for the WWHM modeling results used to size the detention system. Water Quality System Water Quality Treatment will be provided for the developed project. A GULD certified media treatment device is proposed. The media treatment device was sized using the offline 6-month water quality flow rate reported by WWHM (0.0313 cfs). Please see Appendix D for the WWHM modeling results used to size the water quality facility. Section 5: Conveyance System Analysis and Design The on-site conveyance system is designed to convey the 100-year, 24-hour storm event. In the developed condition, runoff will be collected using a curb inlet catch basin. All collected runoff for will be conveyed to the onsite detention system. See MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 17 of 26 Drainage Report - MAGA0001 Appendix A for the Civil Plans showing the conveyance system and discharge location. Pipe Capacity Conveyance Analysis The maximum calculated runoff flow for the 100-year, 24 hour storm event is 0.76 cfs for the project as calculated using the Santa Barbara Unit Hydrograph (SBUH) methodology. This analysis used a time of concentration of 5 minutes, a 100-year rainfall intensity of 4.0 in/hr, a curve number of 98, and impervious area coverage of 100% for the project (0.80 ac). In this simulation, the most hydraulically constrained pipe has a minimum diameter of 8 inches and a minimum slope of 1.56% which can convey 1.61 cfs when full. This exceeds the maximum runoff flow generated onsite for the entire project. Therefore, no further analysis is warranted for pipe capacity. Ditch Capacity Analysis A ‘V’ channel ditch will be constructed along the eastern shoulder of the roadway to convey the intercepted runoff from the upstream Military Road South. To ensure adequate capacity, the upstream runoff from Military Road South was calculated using the SBUH method. A tributary area of 0.75 acres was used with a curve number of 98 and 100% impervious area. By applying a minimum time of concentration of 5 minutes, and a SCS Type 1A 24-hour rainfall series with a rainfall depth of 4.0 inches for the 100-year event, a peak runoff rate of 0.71 cfs (318 gpm) is calculated. The “V” channel ditch capacity was calculated using Manning’s equation and the following parameters: Table 1: "V" Channel Ditch Capacity Parameter Amount Height 1.0 ft Side Slope 3:1 Area 3.0 sf Wetted Perimeter 1.92 ft Hydraulic Radius 0.474 ft Channel Slope (min) 1.0% Manning’s n 0.03 (earth channel, weedy) Q (ditch flow capacity) 9.04 cfs 4,056 gpm In comparison, the “V” channel ditch has sufficient capacity compared to the anticipated runoff generated by the uphill forested area (9.04 cfs vs 0.71 cfs). MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 18 of 26 Drainage Report - MAGA0001 Section 6: Special Reports and Studies A geotechnical engineering study was prepared for the project by The Riley Group, dated November 13, 2020, and is included as Appendix G. Section 7: Other Permits The following approvals/permits will likely be needed for the project (this list may not include all the necessary approvals/permits). • Clearing and Grading Permit • Right-of-Way Permit Section 8: CSWPPP Analysis and Design ESC Plan Analysis and Design The project will implement Erosion and Sediment Control (ESC) measures appropriate to the site to minimize the potential for transport of sediment and other impacts related to land disturbing activities. Below is a discussion of each category of ESC measures that are considered for application to the project site. 1. Clearing Limits: The Construction Drawings require the contractor to clearly mark the clearing limits prior to the start of work. 2. Cover Measures: Temporary and permanent cover measures will be implemented to protect disturbed areas during construction. Temporary cover will be implemented if an area is to remain unworked for more than seven days during the dry season (May 1 to September 30) or for more than two consecutive working days during the wet season (October 1 to April 30). 3. Perimeter Protection: Perimeter protection will be provided, where necessary, to reduce the amount of sediment transported beyond the disturbed areas of the site. Silt fence will be incorporated at downhill slopes along the periphery of the project limits. 4. Traffic Area Stabilization: A stabilized construction entrance is proposed at the north corner of the site for construction traffic. A wheel wash may be used by the contractor if a stabilizing construction entrance is not feasible. It should be noted that the contractor will be required to sweep adjacent streets on a daily basis if sediment is tracked off the site. 5. Sediment Retention: temporary sediment traps will be implemented as required to prevent silt laden runoff from leaving the site. Inlet protection will be used at existing inlets that will be subjected to sediment laden runoff. 6. Surface Water Collection: an interceptor ditch will be constructed along the eastern edge of the proposed roadway in order to divert runoff from the adjacent forested areas around the roadway. This interceptor ditch will be lined with rock check dams to prevent erosion and scouring of the ditch and to promote sedimentation. During construction, discharge will be monitored as required in the Washington State General Permit for Stormwater Discharges Associated with Construction Activities. If thresholds are exceeded, ESC measures will be repaired or adjusted to meet the thresholds. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 19 of 26 Drainage Report - MAGA0001 7. Dewatering Control: construction de-watering is not anticipated, but if necessary, effluent will be directed to sediment traps or distributed via level flow spreaders after proper sedimentation (if water is sediment laden). 8. Dust Control: Wind transport of dust from exposed surfaces will be controlled by spraying exposed soils until wet. Only enough water to wet the soil will be used so that runoff is not generated by spreading. The contractor will also have the option to use the Dust Control Measures designated in Table D.3.8.A of the KCSWDM. These include but are not limited to Salts, Silicates, Surfactants, Copolymers, Lignin Sulfonate, or Spray on Adhesives. 9. Flow Control: construction phase flow control will be provided via sediment traps or via linear ditches along the proposed roadway to prevent sediment laden runoff from leaving the site. 10. Erosion and Sediment Control Performance and Compliance Provisions will include: a. ESC Supervisor: The contractor will design ate an ESC supervisor who will be responsible for the performance, maintenance, and review of ESC measures and for compliance with all permit conditions. b. Monitoring of Discharges: The ESC supervisor will have a turbidity meter onsite and will use it to monitor surface and storm water discharges from the project site. The project site will be covered under the Washington State General Permit for Stormwater Discharges Associated with Construction Activities and will comply with the requirements of that permit. This includes repair or adjustment of ESC measures if thresholds for turbidity or pH are exceeded. c. ESC Performance: If the ESC supervisor determines that the approved measures are not sufficient and that additional action is required due to failure to meet discharge requirements, then additional measures beyond those specified on the Construction Drawings. CSWPP Plan Design The project will implement a stormwater pollution prevention and spill control plan (SWPPS) measures appropriate to the site to minimize the potential for pollution associated with construction activities. Below is a list of each category of SWPPS measures that are considered applicable for this project. 1. Concrete Handling: 2. Concrete Washout Area: 3. Material Delivery, Storage and Containment 4. Construction Stormwater Filtration 5. Maintain Protective BMPs 6. Manage the Project 7. CSWPPP Performance and Compliance Provisions a. CSWPPP Supervisor b. Monitoring of Discharges c. ESC Performance d. SWPPS Performance e. Roads and Utilities Compliance 8. Critical Areas Restrictions MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 20 of 26 Drainage Report - MAGA0001 The site ultimately discharges to Bingamon Creek which is listed on the 303d list for the following contaminants: Table 2: 303d List for Bingamon Creek LISTING_ID CURRENT_CATEGORY PARAMETER_NAME 9464 1 Copper 9466 5 pH 9467 1 Temperature 9946 2 Bacteria 71692 1 Ammonia-N The construction activity associated with the site will not impact Bingamon Creek for the contaminants of concern on the 303d list. Section 9: Bond Quantities, Facilities Summaries, and Declaration of Covenant Bond Quantities Worksheet The Site Improvement Bond Quantity Worksheet will be completed at final design. Flow Control and Water Quality Facility Summary Sheet and Sketch Not applicable for this project as the water quality facility, detention system and dispersion trench are exclusively located onsite. Declaration of Covenant for Privately Maintained Flow Control and WQ Facilities The Declaration of Covenant for Privately Maintained Flow Control and Water Quality Facilities will be completed at final design. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 21 of 26 Drainage Report - MAGA0001 Section 10: Operations and Maintenance Manual. Project Information Address: Parcel No: 0421049063 & 0421049032 Federal Way, WA System Description The onsite stormwater management system will include the following elements: Stormtech detention chambers, a media treatment device for runoff from proposed impervious surfaces, a catch basin for connection of roof drains to Stormtech detention chambers, and a dispersion trench for the discharge from the detention system. The site will be maintained in compliance with the King County Surface Water Design Manual, 2016. The following pages contain descriptions of the maintenance needs for the components of the drainage system. A maintenance checklist for all system components should be completed on the following schedule: Monthly from November through April Once in later summer (preferably in September) After any major storm (use 1-inch in 24-hours as a guideline) Responsible Party: _______________________ Phone: ___________________________________ Note: A copy of this Operation and Maintenance Manual is to be kept onsite at all times and be available for inspection upon request by the City of Federal Way. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 22 of 26 Drainage Report - MAGA0001 Description of Stormwater Facilities Catch Basins – Catch basins are underground concrete structures typically provided with a slotted grate to collect stormwater runoff and route it through underground pipes. Catch basins can also be used as a junction in a pipe system and may have a solid lid. There are two catch basin types. Both catch basin types typically provide a storage volume (sump) below the outlet pipe to allow sediments and debris to settle out of the stormwater runoff. Some catch basins are also provided with a spill control device (inverted elbow on outlet pipe) intended to contain large quantities of grease or oils within the basin. Compost Amended Soil – Naturally occurring (undisturbed) soil and vegetation provide important stormwater functions including: water infiltration; nutrient, sediment, and pollutant adsorption; sediment and pollutant biofiltration; water interflow storage and transmission; and pollutant decomposition. Compaction from construction can reduce the soils natural ability to provide these functions. Establishing a minimum soil quality and depth in the post-development landscape can regain some of these stormwater functions including increased treatment of pollutants and sediments that result from development and habitation, and minimizes the need for some landscaping chemicals. Sufficient organic content is a key to soil quality. Soil organic matter can be attained through numerous amendments such as compost, composted woody material, biosolids, and forest product residuals. Biopod Filter - Biopod filters are underground concrete or steel structures that may have a slotted grate structure to collect stormwater runoff in addition to a solid lid over the filter unit. Within the device, the structure is divided into at least three compartments: the inlet chamber with sump, the stormfilter cartridge chamber, and the outlet chamber. An overflow weir wall will also be present between the inlet chamber and outlet chamber which allows high flows to bypass the stormfilter cartridge altogether. Biopod filters have filter media that have a finite lifespan and need to be replaced on the order of 3-5 years in order for the device to operate properly. Dispersal Trench - A dispersal trench system includes a gravel bed intended for use in dispersing runoff from impervious surfaces (i.e. roofs and pavement). Dispersal trenches are backfilled with washed drain rock, allowing for temporary storage of stormwater runoff in the voids of the drain rock material. Stored runoff gradually infiltrates and/or percolates upwards where it is distributed overland via a notched grade board into the surrounding soil. A downstream vegetative flowpath disperses the flow and avoids a point discharge of the runoff and potential erosion issues connected with point discharges. The gravel dispersal trench contains a catch basin which is connected to an influent pipe, a perforated pipe laid flat near the bottom of the dispersal trench which distributes runoff into the gravel media, and cleanouts at the end of the perforate pipe for access to the pipe MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 23 of 26 Drainage Report - MAGA0001 Cost Estimate for Maintenance The cost estimate below assumes one worker and necessary equipment would cost $1,000 per day in labor ($200) and equipment costs ($800). Table 3: Cost Estimate for Storm Maintenance (Puyallup Tribe of Indians) Maintenance Activity Frequency Annualized Cost Catch Basins Clear all trash/debris/vegetation blocking basin opening yearly $500 Remove sediment exceeding 60% of sump depth 2x/year $500 Inspect for damage to frame or structure walls Annually $100 Media Filter Device Replace Media Cartridge 1/3 yearly $2,000 Dispersal Trench Remove sediment exceeding 60% of sump depth 2x/year $500 Estimate of Total Annual Cost $3600 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 24 of 26 Drainage Report - MAGA0001 Stormwater Facility Maintenance Log Use copies of this log sheet to track when maintenance checks occur, and which items, if any are repaired and altered. The completed sheets will serve as a record of past maintenance activities and will provide valuable information on how your facilities are operating. This information will be useful for future requirements regarding the types of facilities that are installed. Keep all log sheets in a designated area so that others can easily access them. Site Name: Midway Samoan Church Date: ________ Time: _____________ Site Address: 29276 Military Road South, Federal Way, WA 98003 Weather Condition: _____________________ Checked By: ______________________ MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 25 of 26 Drainage Report - MAGA0001 Part of Facility Checked Observations (Things To Be Done) Follow-up Actions Taken Date Action Taken MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page 26 of 26 Drainage Report - MAGA0001 List of Appendices Appendix A - Civil Engineering Plans ........................................................................................................ A-1 Appendix B - Technical Information Worksheet............................................................................... B-1 Appendix C - Site Improvement Bond Quantity Worksheet ..................................................... C-1 Appendix D - WWHM Calculations ............................................................................................................ D-1 Appendix E - Construction Stormwater Pollution Prevention Plan (C-SWPPP) ........... E-1 Appendix F - USDA Web Soil Survey ......................................................................................................... F-1 Appendix G - Geotechnical Report ............................................................................................................ G-1 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page A-1 of 1 Drainage Report - MAGA0001 Appendix A - Civil Engineering Plans 1 0 0 ' S T R E A M B U F F E R 12" C O N C . C U L V E R T EL=42 2 . 1 5 'OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP OP OP MB T S P S 2 4 3 5 6 7CONCRETE ROADWAYASPHALT SHOULDERASPHALT SHOULDERASPHALTASPHALT SHOULDERCONCRETE ROADWAYCENT E R L I N E O F DRAI N A G E D I T C H MILITARY RD SGUTT E R 9.7' 4.2' 8.4' 1.3'0.8'SHOULDERWL1-2 WL1-1 WL1-3 WL1-4 WL1-5 WL1-6 WL1-7 WL1-8 WL1-9 WL1-1 0 WL1-1 1 SL# 1 SL# 3 FDFDFDFDFDFDFD FD FD FD FD FD FD FD FD FD FDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFD RDRDRDRDRDRDRD RD RD RD RD RD RD RD RD RD RDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDXX X X X X X X X XXXXXXXXX X X XX COMPACTCOMPACTW W W W W W W WW W UGP UGP UGP UGP UGP UGP UGPUGP415415420420425425412 4 1 3 413 4 1 3413 4 1 4 4144144144164164174174184184194194214214224224234234244244 2 6 42641 5420 41 241 3 41 4 41 6419421422 415420416417418419421422423424FFE 419.35 10+0011+0012+0013+0013+47.27SD3CB Type 1L Vaned Grate STA: 11+42.76; 118.46' R RIM: 418.98 IE: 416.75 6" PVC (In-S) IE: 416.75 6" PVC (Out-W) CB Type II - 48" Circular Frame Solid Lid IE: 414.70 12" CPEP (In-SE) STA: 12+23.48; 125.40' R RIM: 418.72 SD2 BIOPOD 46IB IE: 414.84 12" CPEP (Out-NW) STA: 12+03.54; 146.02' R RIM: 417.80 SD1 ECB1 EXCB Type II - 48" Rec. Frame STA: 12+83.68; 1.10' R RIM: 423.29 IE: 416.48 15" EX CONC (In-W) CULVERT IE: 418.00 12" CMP (In-W) STA: 10+06.98; 17.00' RSD6 CULVERT IE: 418.78 12" CMP (Out-E) STA: 10+06.99; 6.00' LSD7 12"∅ CPEP - 29LF @ 0.50% 12"∅ CMP - 23LF @ 3.39% 1 2 4 SD9CB Type II - 48" Circular Frame STA: 11+66.73; 117.79' R RIM: 418.53 IE: 413.00 8" CPEP (Out-E) 5 8"∅ CPEP - 128LF @ 1.56% CB Type 1 IE: 411.00 8" CPEP (In-W) STA: 11+69.81; 245.91' R RIM: 413.00 SD5 6 6 415420416 417 418419420 418418419419421422423424 4 1 5 4 1 6 41741 8 41 9 423 42 3 421 42142242242342042141941941841741641541410 9 8 7 420421SS - 6"∅ PVC - 145LF @ 5.16% CO1SSCO STA: 31+45.39; 0.00' RIM: 419.10 IE: 414.25 6" PVC (In-W) IE: 414.25 6" PVC (Out-E)CONNECTION TO EXISTING SEWER MANHOLE 6"∅ PVC IE = 406.74SANITARY SEWER CONNECTION TO BUILDING 6"∅ PVC IE = 414.35 11 12 12 60.00' WETLAND BUFFE R60.00' WETLAND BUFFER13 13 30.00'14 15.00' R.O.W. DEDICATION 20 .00 ' SDCO w/ Concrete Collar STA: 11+86.73; 235.23' R RIM: 413.00 CO1 CIVIL KEYNOTES BIOPOD (IB46) MEDIA FILTER DEVICE FOR ENHANCED TREATMENT. SEE DETAIL 1 ON SHEET C1.1. STORMTECH SC-740 CHAMBER DETENTION SYSTEM. NOT USED 20 FOOT LINEAL DISPERSAL TRENCH PER KCSWDM FIGURE 4.2.2.B. THE 100-YEAR UNMITIGATED FLOW IS 0.66 CFS FLOW CONTROL STRUCTURE 2-FOOT CURB CUT. NEW 4" FIRE SPRINKLER SERVICE WITH BUILDING MOUNTED POST-INDICATOR VALVE AND DOUBLE DETECTOR CHECK VALVE ASSEMBLY WITHIN FIRE RISER ROOM. 4" FIRE DEPARTMENT CONNECTION MOUNTED ON BUILDING WALL. NEW FIRE HYDRANT. REPLACE EXISTING OVERHEAD POWER SERVICE TO EXISTING BUILDING (BUILDING TO BE DEMOLISHED). FURNISH AND INSTALL NEW PAD-MOUNTED TRANSFORMER. NEW 1.5" DOMESTIC SERVICE WITH 1" METER. 8" DUCTILE IRON PIPE. PLACE PEDSTRIAN BARRICADE AT END OF SIDEWALK. NEW 30' COMMERCIAL DRIVEWAY APPROACH. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 HMA PAVEMENT CONCRETE SIDEWALK CONCRETE PLAZA LANDSCAPING BLDG FOOTPRINT PROPERTY LINE DITCH FLOWLINE WATER SERVICE POWER SERVICE WETLAND BUFFER WETLAND EDGE ROOF DRAIN W UGP RD SITE PLAN LEGEND PROJECT NO. DRAWN BY: DESIGNED BY:DATENO.REVISION DESCRIPTIONCKBYDATE: SHEET NO.Save Date: Plot Date: 10/7/2021 2:04 PM10/7/2021 2:11 PMBy: LiamAyersP:\M\MAGA0001\0400CAD\Sheets\Exhibits\Preliminary Drainage, Grading, And Right-of-Way Plan - MAGA0001.dwgLiam AyersBy: File:CHECKED BY: 1145 BROADWAY, SUITE 115 TACOMA, WA 98402 PHONE: 253.319.1504 VERT. DATUM: HORZ. DATUM: REFERENCE NO. SW 1/4 OF NE 1/4 SECTION 4, TOWNSHIP 21N, RANGE 4E, W.M. MAGA0001 C1.0 1 OF 5 10/11/2021 NAD83/11 NAVD88 FEDERAL WAY, WASHINGTONMIDWAY SAMOAN AG CHURCHMAGELLAN ARCHITECTSPRELIMINARY DRAINAGE, GRADING, & RIGHT-OF-WAY PLAN29276 MILITARY ROAD SOUTHKYLE M KYLE M MARC P PRELIMINARY NORTH IMPERVIOUS SURFACE COVERAGE AREAS EXISTING EXISTING NON-POLLUTION GENERATING IMPERVIOUS SURFACE : 6,900 SF EXISTING POLLUTION GENERATING IMPERVIOUS SURFACE :13,650 SF TOTAL EXISTING IMPERVIOUS SURFACE :20,550 SF PROPOSED PROPOSED NON-POLLUTION GENERATING IMPERVIOUS SURFACE :16,245 SF PROPOSED POLLUTION GENERATING IMPERVIOUS SURFACE :13,350 SF TOTAL PROPOSED IMPERVIOUS SURFACE :29,595 SF APPROXIMATE CUT & FILL QUANTITIES CUT VOLUME :248± CY FILL VOLUME :3,474± CY NET VOLUME :3,226± CY (FILL) NOTE: ALL VOLUMES ARE APPROXIMATE AND ARE PROVIDED FOR PERMITTING PURPOSES ONLY AND REPRESENT FINISH GRADE TO EXISTING GRADE SHOWN. CONTRACTOR SHALL RELY ON THEIR OWN ESTIMATES FOR DETERMINING ACTUAL EARTHWORK QUANTITIES. THE VOLUMES LISTED ABOVE DO NOT ACCOUNT FOR STRIPPINGS, SUBGRADE MATERIALS, TRENCHING, STRUCTURAL EXCAVATION, EXPANSION/COMPACTION FACTORS OR ANY SOIL TYPE RESTRICTIONS. Sheet List Table SHEET #REF. #SHEET TITLE 1 C1.0 Preliminary Drainage, Grading, & Right-of-Way Plan 2 C1.1 Drainage Details 3 C2.0 Clearing & Grading Plan 4 C2.1 Site Sections 5 C3.0 EXISTING CONDITIONS INFORMATION FOR BUILDABLE LANDS CALCULATIONS CATEGORY ACRES GORSS LAND AREA - ACREAGE OF THE SITE PRIOR TO ANY DEDICATIONS OR SET-ASIDES.2.72 CRITICAL AREAS - ACREAGE PRECLUDED FROM DEVELOPMENT DUE TO WETLANDS AND BUFFER; STREAMS AND BUFFERS; REGULATED LAKES AND BUFFERS; SHORELINE SETBACKS; FLOOD HAZARDS AREAS; EROSION HAZARD AREAS; AND/OR LANDSLIDE HAZARD AREAS. 1.63 PUBLIC PURPOSE - ACREAGE OF SITE TO BE USED FOR RETENTION/DETENTION/DRAINAGE FACILITIES; OPEN SPACE AND PARKS; OR OTHER ON-SITE PUBLIC FACILITIES. DO NOT INCLUDE PUBLIC UTILITIES EASEMENTS OF LANDSCAPING. 0.12 NET LAND AREA - GROSS LAND MINUS CRITICAL AREAS, RIGHT-OF-WAY, AND PUBLIC PURPOSE.0.97 PROJECT NO. DRAWN BY: DESIGNED BY:DATENO.REVISION DESCRIPTIONCKBYDATE: SHEET NO.Save Date: Plot Date: 10/7/2021 2:04 PM10/7/2021 2:11 PMBy: LiamAyersP:\M\MAGA0001\0400CAD\Sheets\Exhibits\Preliminary Drainage, Grading, And Right-of-Way Plan - MAGA0001.dwgLiam AyersBy: File:CHECKED BY: 1145 BROADWAY, SUITE 115 TACOMA, WA 98402 PHONE: 253.319.1504 VERT. DATUM: HORZ. DATUM: REFERENCE NO. SW 1/4 OF NE 1/4 SECTION 4, TOWNSHIP 21N, RANGE 4E, W.M. MAGA0001 C1.1 2 OF 5 10/11/2021 NAD83/11 NAVD88 FEDERAL WAY, WASHINGTONMIDWAY SAMOAN AG CHURCHMAGELLAN ARCHITECTSDRAINAGE DETAILS29276 MILITARY ROAD SOUTHKYLE M KYLE M MARC P PRELIMINARY SCALE: NTS BIOPOD BIOFILTER1 1 0 0 ' S T R E A M B U F F E R 12" C O N C . C U L V E R T EL=42 2 . 1 5 'OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP OP OP MB T S P S 2 4 3 5 6 7CONCRETE ROADWAYASPHALT SHOULDERASPHALT SHOULDERASPHALTASPHALT SHOULDERCONCRETE ROADWAYCENT E R L I N E O F DRAI N A G E D I T C H MILITARY RD SGUTT E R 9.7' 4.2' 8.4' 1.3'0.8'SHOULDERWL1-2 WL1-1 WL1-3 WL1-4 WL1-5 WL1-6 WL1-7 WL1-8 WL1-9 WL1-1 0 WL1-1 1 SL# 1 SL# 3 FDFDFDFDFDFDFD FD FD FD FD FD FD FD FD FD FDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFDFD RDRDRDRDRDRDRD RD RD RD RD RD RD RD RD RD RDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDRDCOMPACTCOMPACTW W W W W W W WW W UGP UGP UGP UGP UGP UGP UGPUGP415415420420425425412 4 1 3 413 4 1 3413 4 1 4 4144144144164164174174184184194194214214224224234234244244 2 6 42641 5420 41 241341 4 41 6419421422 415420416417418419421422423424FFE 419.35 10+0011+0012+0013+0013+47.27SD3CB Type 1L Vaned Grate STA: 11+42.76; 118.46' R RIM: 418.98 IE: 416.75 6" PVC (In-S) CB Type II - 48" Circular Frame Solid Lid IE: 414.70 12" CPEP (In-SE) STA: 12+23.48; 125.40' R RIM: 418.72 SD2 BIOPOD 46IB IE: 414.84 12" CPEP (Out-NW) STA: 12+03.54; 146.02' R RIM: 417.80 SD1 ECB1 EXCB Type II - 48" Rec. Frame STA: 12+83.68; 1.10' R RIM: 423.29 IE: 416.48 15" EX CONC (In-W) CULVERT IE: 418.00 12" CMP (In-W) STA: 10+06.98; 17.00' RSD6 CULVERT IE: 418.78 12" CMP (Out-E) STA: 10+06.99; 6.00' LSD7 12"∅ CPEP - 29LF @ 0.50% 12"∅ CMP - 23LF @ 3.39% 1 2 4 SD9CB Type II - 48" Circular Frame STA: 11+66.73; 117.79' R RIM: 418.53 IE: 413.00 8" CPEP (Out-E) 5 8"∅ CPEP - 128LF @ 1.56% CB Type 1 IE: 411.00 8" CPEP (In-W) STA: 11+69.81; 245.91' R RIM: 413.00 SD5 6 6 415420416 417 418419420 418418419419421422423424 4 1 5 4 1 6 4 1 7 41841 9 423 42 3 421 42142242242342042141941941841741641541410 9 8 7 420421SS - 6"∅ PVC - 145LF @ 5.16% CO1SSCO STA: 31+45.39; 0.00' RIM: 419.10 IE: 414.25 6" PVC (In-W) IE: 414.25 6" PVC (Out-E)CONNECTION TO EXISTING SEWER MANHOLE 6"∅ PVC IE = 406.74SANITARY SEWER CONNECTION TO BUILDING 6"∅ PVC IE = 414.35416417 1 C2.1 2C2.1SFSFSF SF SF SF SF SF SFSFSFSFSFSFIN LET PROTECTIO NIN LET PROTECTIO N 3 3 3 3 3 3 2 2 11 12 12 60.00' WETLAND BUFFE R60.00' WETLAND BUFFER13 13 15.00' R.O.W. DEDICATION 14 15 15 20 .00 ' SDCO w/ Concrete Collar STA: 11+86.73; 235.23' R RIM: 413.00 CO1 CIVIL KEYNOTES BIOPOD (IB46) MEDIA FILTER DEVICE FOR ENHANCED TREATMENT. SEE DETAIL 1 ON SHEET C1.1. TEMPORARY SEDIMENT POND PER SECTION D.2.1.5.2 OF THE 2016 KING COUNTY SWMM. SILT FENCE PER SECTION C.3.6 OF THE 2016 KING COUNTY SWMM. 20 FOOT LINEAL DISPERSAL TRENCH PER KCSWDM FIGURE 4.2.2.B. THE 100-YEAR UNMITIGATED FLOW IS 0.66 CFS FLOW CONTROL STRUCTURE 2-FOOT CURB CUT. NEW 4" FIRE SPRINKLER SERVICE WITH BUILDING MOUNTED POST-INDICATOR VALVE AND DOUBLE DETECTOR CHECK VALVE ASSEMBLY WITHIN FIRE RISER ROOM. 4" FIRE DEPARTMENT CONNECTION BUILDING MOUNTED. NEW FIRE HYDRANT. REPLACE EXISTING OVERHEAD POWER SERVICE TO EXISTING BUILDING (BUILDING TO BE DEMOLISHED). FURNISH AND INSTALL NEW PAD-MOUNTED TRANSFORMER. STABILIZED CONSTRUCTION ENTRANCE PER SECTION C.3.1 OF THE 2016 KING COUNTY SWMM. STORM DRAIN INLET PROTECTION PER SECTION C.3.9 OF THE 2016 KING COUNTY SWMM. PLACE PEDESTRIAN BARRICADE AT THE END OF SIDEWALK. NEW 1.5" DOMESTIC SERVICE WITH 1" METER. 8" DUCTILE IRON PIPE. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 HMA PAVEMENT CONCRETE SIDEWALK CONCRETE PLAZA LANDSCAPING BLDG FOOTPRINT EXISTING AREAS WITH 15 TO 40% SLOPE PROPERTY LINE DITCH FLOWLINE WATER SERVICE POWER SERVICE WETLAND BUFFER WETLAND EDGE ROOF DRAIN EXISTING CONTOUR PROPOSED CONTOUR W UGP RD SITE PLAN LEGEND 19 20 PROJECT NO. DRAWN BY: DESIGNED BY:DATENO.REVISION DESCRIPTIONCKBYDATE: SHEET NO.Save Date: Plot Date: 10/7/2021 2:09 PM10/7/2021 2:11 PMBy: LiamAyersP:\M\MAGA0001\0400CAD\Sheets\Exhibits\C&G-MAGA0001.dwgLiam AyersBy: File:CHECKED BY: 1145 BROADWAY, SUITE 115 TACOMA, WA 98402 PHONE: 253.319.1504 VERT. DATUM: HORZ. DATUM: REFERENCE NO. SW 1/4 OF NE 1/4 SECTION 4, TOWNSHIP 21N, RANGE 4E, W.M. MAGA0001 C2.0 3 OF 5 10/11/2021 NAD83/11 NAVD88 FEDERAL WAY, WASHINGTONMIDWAY SAMOAN AG CHURCHMAGELLAN ARCHITECTSCLEARING & GRADING PLAN29276 MILITARY ROAD SOUTHKYLE M KYLE M MARC P PRELIMINARY NORTH Horz. Scale: 1" = 20' | Vert. Scale: 1" = 5' W-E Site Section (STA: 59+75 TO 65+25) 410 412.5 415.0 417.5 420 422.5 425.0 427.5 430 410 412.5 415.0 417.5 420 422.5 425.0 427.5 43059+75 60+00 61+00 62+00 63+00 64+00 65+00 65+25 59+75 60+00 61+00 62+00 63+00 64+00 65+00 65+25EG ±FGEG 423.8±FGEG 422.9±FGEG 418.9±FG 420.13EG 417.7±FG 419.35EG 416.9±FG 419.35EG 416.5±FG 419.35EG 416.0±FG 419.35EG 415.7±FG 419.35EG 415.0±FG 419.30EG 414.7±FG 418.98EG 414.5±FGEG 413.7±FGEG 413.5±FGEG 413.3±FGEG 413.1±FGEG 412.7±FGEG 412.5±FGEG 411.6±FGEG ±FGFG EG 4 H : 1 VEXTERIOR BUILDING WALLEXTERIOR BUILDING WALL6.50' ONSITE SIDEWALK 6.00'NEW SIDEWALK IN R.O.W. PL3.00' PUBLIC DRAINAGE DITCH 38.00' BACK PATIO PL 2%2% Horz. Scale: 1" = 20' | Vert. Scale: 1" = 5' S-N Site Section (STA: -0+25 TO 4+00) 410 412.5 415.0 417.5 420 422.5 425.0 427.5 430 410 412.5 415.0 417.5 420 422.5 425.0 427.5 430-0+25 0+00 1+00 2+00 3+00 4+00 -0+25 0+00 1+00 2+00 3+00 4+00EG ±FGEG 416.8±FG 416.33EG 416.8±FG 419.35EG 416.4±FG 419.35EG 417.2±FG 419.35EG 417.2±FG 419.02EG ±FG 418.58EG 415.8±FG 418.64EG 415.9±FG 418.90EG 416.7±FG 419.62EG 422.1±FGEG 416.1±FGEG 415.0±FGEG ±FGEG ±FGEG FG EXTERIOR BUILDING WALLEXTERIOR BUILDING WALLPL PL 2%5H:1V PROJECT NO. DRAWN BY: DESIGNED BY:DATENO.REVISION DESCRIPTIONCKBYDATE: SHEET NO.Save Date: Plot Date: 10/7/2021 2:09 PM10/7/2021 2:11 PMBy: LiamAyersP:\M\MAGA0001\0400CAD\Sheets\Exhibits\C&G-MAGA0001.dwgLiam AyersBy: File:CHECKED BY: 1145 BROADWAY, SUITE 115 TACOMA, WA 98402 PHONE: 253.319.1504 VERT. DATUM: HORZ. DATUM: REFERENCE NO. SW 1/4 OF NE 1/4 SECTION 4, TOWNSHIP 21N, RANGE 4E, W.M. MAGA0001 C2.1 4 OF 5 10/11/2021 NAD83/11 NAVD88 FEDERAL WAY, WASHINGTONMIDWAY SAMOAN AG CHURCHMAGELLAN ARCHITECTSSITE SECTIONS29276 MILITARY ROAD SOUTHKYLE M KYLE M MARC P PRELIMINARY 1 2 100' STREAMBUFFER12" CONC. CULVERTEL=422.15'OPOPOPOPOPOP OP OP OP OP OP OP OP OP OP OP OPOPOPOPOPOPOPOPMBTSPSSS2451234567EXISTINGBUILDINGGRAVELGRAVELEXISTINGBUILDINGCONCRETE PADCOVEREDRECREATIONAREADECKCONC.LANDSCAPINGBORDERCONC.LANDSCAPINGBORDERDECKCONCRETECONC.WALKWAYSTORAGECONTAINERCONCRETE ROADWAYASPHALT SHOULDERASPHALT SHOULDERASPHALTASPHALT SHOULDERCONCRETE ROADWAYCONCRETECENTERLINE OFDRAINAGE DITCHCENTERLINE OFDRAINAGE DITCHBUILDINGEAVE/OVERHANGTYP.BUILDINGEAVE/OVERHANG TYP.MILITARY RD SAPN 0421049063APN 0421049032CURB &GUTTER9.7'4.2'8.4'1.3'0.8'411.14 1 1 . 9 4 1 2 . 8413.7415.1423.6423.1417.2 4 1 5 . 8 415.3422.8 4 2 2 . 0 422.3415.4415.7415.9417.1418.6 423.2410.7412. 5 412.4410.4409.941 2 . 4 411.041 2 . 6 411.0413 . 0 411.4 413 . 6 411.7 4 1 4 . 0 412.04 1 4 . 1 412.64 1 3 . 1413.8414.5416.1416.3418.6420.04 2 0 . 1 419.6418.6418.7 41 9 . 1 4 1 9 . 2 4 1 8 . 1 4 1 7 . 5 4 1 7 . 0416.4416.9417.6416.24 1 5 . 2 415.8416.04 1 5 . 7 414.5414.8415.2416.04 1 3 . 4 4 1 3 . 3 412.8412.7412.84 1 1 . 6 411.3411.84 1 1 . 2 4 1 1 . 4 4 1 1 . 4412.04 1 2 . 9413.64 1 3 . 2 413.5412.9413.341 3 . 1 411.3410.84 1 3 . 9 4 1 4 . 9415.8416.8420.4421.2419.5 420.04 1 8 . 7 4 1 5 . 7422.7423.3424.1 4 2 1 . 6 420.5420.8413.94 1 2 . 5 414.54 2 1 . 1 419. 4 4 2 3 . 7 415.79415.594 1 6 . 1 3416.19416.43415.66421 .42421.34418.714 1 8 . 1 0 418.4424.9 424.4424.4423.8418.3417.2416.84 1 5 . 0 4 1 4 . 9421.06422.6042 1 . 2 0422.8542 1 . 8 4423.27423.87422.69423.2442 4 .37 42 4 . 8 4 423.98425.09424.37425.47426.20425.61426.18426.46424.03423.67423 . 9 2 424.54425.03425 . 1 7 425.19425.47425.85SHOULDER415420413 41 4416417418419421 422 423 415412413414411 4114 1 2 413 4154 1 4 420 416417 418 419 423424 422420416423420417422420415416 420 425 416 417 41 8 419 421 422 423 424 420 416417418 419 421 422 423 420 417418419412 41 2 41 3414424 425 424 425 426 423 421 GRAVELWL1-2WL1-1WL1-3WL1-4WL1-5WL1-6WL1-7WL1-8WL1-9WL1-10WL1-11WL1-12WL1-13WL1-14SL# 1SL# 2SL# 3TYPE NS STREAMCATEGORY III WETLAND80' WETLANDBUFFEROP OPOPS1OPS31SEWER MANHOLERIM EL=426.97'(W) 8" PVC I.E.=417.37'(NW) 10" CONC. I.E.=417.22'(SE) 10" CONC. I.E.=417.12'2SEWER MANHOLERIM EL=425.55'(NW) 10" CONC. I.E.=416.10'(SE) 10" CONC. I.E.=416.00'3SEWER MANHOLERIM EL=423.86'(NW) 10" CONC. I.E.=414.26'(SE) 10" CONC. I.E.=414.16'4SEWER MANHOLERIM EL=415.74'(E) I.E.=406.74'(SW) 12" CONC. I.E.=406.34'(NE) 12" CONC. I.E.=406.24'(UNABLE TO OBTAIN PIPE SIZE ANDMATERIAL FOR (E) PIPE)5SEWER MANHOLERIM EL=413.69'(SW) 12" CONC. I.E.=405.34'(NW) 12" CONC. I.E.=405.24'6SEWER MANHOLERIM EL=414.87'(SE) 12" CONC. I.E.=405.62'(E) UNABLE TO OBTAIN INVERTELEVATIONS61CATCH BASINRIM EL=425.94'(NW) 15" IRON I.E.=422.04'(SW) 15" CPP I.E.=421.89'2CATCH BASIN(SOLID LID)RIM EL=426.29'(NE) 15" CPP I.E.=421.94'(E) 12" CONC. I.E.=421.89'(W) 12" CMP I.E.=422.19'3CATCH BASINRIM EL=425.72'(NE) 8" CPP I.E.=423.47'4CATCH BASINSOLID LIDRIM EL=426.02'(N,S) 24" CONC. I.E.=419.07'(W) 12" CONC. I.E.=420.72'(SW) UNABLE TO OBTAIN INVERTELEVATION12" CONC. CULVERT EL=422.15'56CATCH BASINRIM EL=425.21'(S) 12" CONC. I.E.=421.71'(NE) 24" CONC. I.E.=417.91'(E) 15" CONC. I.E.=417.51'7CATCH BASINRIM EL=422.03'(W) 15" CONC. I.E.=416.48'(NE) 12" CONC. I.E.=416.33'INLET HOLE IN SIDE OFSTRUCTURE I.E.=420.64' (NOPIPE)90°21'7"(R2)CENTER OF SECTION 4USED FOR DEED CALLSPER (R1)CENTER OF SECTION4 (PER R2)(R2)N. 1/4 COR. SEC. 4,T.21N., R.4E., W.M.FOUND CASED 3" BRASSDISK W/"X" DOWN 0.5'89°35'52"NE COR. SEC. 4,T.21N., R.4E., W.M.FOUND CASED 3"BRASS DISK W/"X"DOWN 0.5'VERTICAL DATUMPOWER METERPOWER POLE W/LIGHT, TRANSFORMER & DROPSTORM DRAIN CATCH BASINGUARD POSTMAIL BOXUNKNOWN MANHOLESEWER MANHOLECOMMUNICATION PEDESTALFIRE HYDRANTWATER METEROPOPOPOPOPBARBED WIRE FENCEWOOD FENCEOVERHEAD UTILITY LINESTORM DRAIN LINESEWER LINETELECOMM PAINT LINEWATER PAINT LINEDISTANCE PER DEEDDISTANCE PER REFERENCEDISTANCE AS MEASUREDDISTANCE AS CALCULATED(D)(R)(M)(C)1 1 OF SHT. CHECKED: EMW FOR: DATE: 9/8/2020 SCALE: 1" = 30' JOB NO.: MOMEN-200707 FIELD CREW:AG,ES LOCATED IN SW 1 4 OF THE NE14 OF SECTION 4, TOWNSHIP 21N, RANGE 4E, W.M. DRAFTED: JR 29276 MILITARY ROAD SOUTH FEDERAL WAY, WA 98003 TAX PARCEL NO. 0421049063 & 0421049032 TOPOGRAPHIC SURVEY MOMENTUM CIVIL ENGINEERING CONSULTANTSNATEAVESTOR LHAM NEGIS T E R WA R E DO F SHIN G TO44651 S T MW TOPOGRAPHICSURVEYCITY OF FEDERAL WAY, KING COUNTY, WALEGAL DESCRIPTIONSURVEYOR'S NOTESHORIZONTAL DATUMREFERENCE SURVEYSLEGENDTHE EXISTING UTILITIES AS SHOWNARE ONLY APPROXIMATE AND AREBASED ON THE BEST AVAILABLEINFORMATION. IT SHALL BE THECONTRACTOR'S RESPONSIBILITY TOVERIFY THE SIZE, TYPE, LOCATION,AND DEPTH OF ALL EXISTING UTILITIESPRIOR TO STARTING CONSTRUCTION,AND INFORM THE DESIGN ENGINEEROF ANY DISCREPANCIES.SEWER STRUCTURE TABLESTORM STRUCTURE TABLEUNKNOWN UTILITY PAINT LINELINE TYPE LEGENDFOUND SECTION 1/4 CORNER (AS SHOWN)FOUND SECTION CORNER (AS SHOWN)WATER VALVEAPPROXIMATE WETLAND FLAG LOCATIONPMTSTMBUinformed land survey PO Box 5137 Tacoma, WA 98415-0137 LAND SURVEYING • MAPPING • CONSTRUCTION LAYOUT Phone: 253-627-2070 admin@i-landsurvey.com www.i-landsurvey.com WETLAND NOTESHEET NO. REFERENCE NO.C3.0 5 OF 5 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page B-1 of 6 Drainage Report - MAGA0001 Appendix B - Technical Information Worksheet Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner Midway Samoan Church Phone Address 29276 Military Road South Federal Way, WA 98003 Project Engineer Marc Pudists, P.E. Momentum Civil Phone (253) 405-4474 Project Name Midway Samoan Church DDES Permit # N/A Location Township 21N Range 4E Section 4 Site Address 29276 Military Road South, Federal Way, WA 98003 Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Landuse Services Subdivision / Short Subd. / UPD Building Services M/F / Commercial / SFR Clearing and Grading Right-of-Way Use Other DFW HPA Shoreline Management COE 404 Structural DOE Dam Safety Rockery/Vault/Wall FEMA Floodplain ESA Section 7 COE Wetlands Other: • Part 5 PLAN AND REPORT INFORMATION Technical Information Report Type of Drainage Review Full / Targeted / (circle): Large Site Date (include revision October 2021 dates): Date of Final: Site Improvement Plan (Engr. Plans) Type (circle one): Full / Modified / Small Site Date (include revision dates): Date of Final: MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page B-2 of 6 Drainage Report - MAGA0001 • Part 6 ADJUSTMENT APPROVALS Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket Description: (include conditions in TIR Section 2) Date of Approval: Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: Completion Date: Describe: • Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: Special District Overlays: Drainage Basin: Lower Green River Basin Stormwater Requirements: Core Req’ts #1 through #9, Special Req’ts #1 through #5. Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/Stream Bingamon Creek Lake Wetlands Closed Depression Floodplain Other Steep Slope Erosion Hazard Landslide Hazard Coal Mine Hazard Seismic Hazard Habitat Protection MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page B-3 of 6 Drainage Report - MAGA0001 Part 10 SOILS Soil Type Alderwood (AgC) Alderwood (AgD) Kitsap (KpB) Slopes 8-15% 15-30% 2-8% Erosion Potential Slight ? Slight High Groundwater Table (within 5 feet) Other Sole Source Aquifer Seeps/Springs Additional Sheets Attached Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core 2 – Offsite Analysis Sensitive/Critical Areas SEPA Other LIMITATION / SITE CONSTRAINT Bingamon Creek, wetlands onsite Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: TDA #1 Code Requirements (all 8 apply) Discharge at Natural Location Number of Natural Discharge Locations: 1 Offsite Analysis: Level 1 / 2 / 3 dated: October 2021 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page B-4 of 6 Drainage Report - MAGA0001 Flow Control (incl. facility summary sheet) Level 1 / 2 / 3 or Exemption Number Small Site BMPs Conveyance System Spill containment located at: N/A Erosion and Sediment Control ESC Site Supervisor: TBD Contact Phone: TBD After Hours Phone: TBD Maintenance and Operation Responsibility: Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality (include facility summary sheet) Type: Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. Landscape Management Plan: Yes / No Special Requirements (as applicable) Area Specific Drainage Requirements Type: CDA / SDO / MDP / BP / LMP / Shared Fac. / None Name: Floodplain/Floodway Delineation Type: Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): N/A Datum: N/A Flood Protection Facilities: Describe: N/A Source Control (comm./industrial land use) Describe land use: Commercial Describe any structural controls: None Oil Control High-use Site: Yes / No Treatment BMP: Maintenance Agreement: Yes / No With Whom? Other Drainage Structures Describe: Conveyance system catch basins and pipes conveying runoff to a media treatment device prior to discharge through a gravel filled dispersal trench. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page B-5 of 6 Drainage Report - MAGA0001 Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION Clearing Limits Cover Measures Perimeter Protection Traffic Area Stabilization Sediment Retention Surface Water Collection Dewatering Control Dust Control Flow Control MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize Exposed Surfaces Remove and Restore Temporary ESC Facilities Clean and Remove All Silt and Debris, Ensure Operation of Permanent Facilities Flag Limits of SAO and open space preservation areas Other: Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Type/Description Water Quality Type/Description Detention Infiltration Regional Facility Shared Facility Flow Control BMPs Other Detention Chambers Dispersion Trench Biofiltration Wetpool Media Filtration Oil Control Spill Control Flow Control BMPs Other BioPod (enhanced) Dispersion Trench Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Easement Tract Other Cast in Place Vault Retaining Wall Rockery > 4’ High Structural on Steep Slope Other: MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page B-6 of 6 Drainage Report - MAGA0001 Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. Signed/Date MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page C-1 of 1 Drainage Report - MAGA0001 Appendix C - Site Improvement Bond Quantity Worksheet MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-1 of 24 Drainage Report - MAGA0001 Appendix D - WWHM Calculations MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-2 of 22 Drainage Report - MAGA0001 WWHM2012 PROJECT REPORT Detention Gallery Sizing _________________________________________________________ Project Name: detention sizing Site Name: samoan church Site Address: 29276 Military Road City : Federal Way Report Date: 10/7/2021 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2019/09/13 Version : 4.2.17 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Flat .567 C, Forest, Mod .567 Pervious Total 1.134 Impervious Land Use acre Impervious Total 0 Basin Total 1.134 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-3 of 22 Drainage Report - MAGA0001 MITIGATED LAND USE Name : Basin 2 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .227 C, Lawn, Mod .227 Pervious Total 0.454 Impervious Land Use acre ROADS FLAT 0.435 ROOF TOPS FLAT 0.245 Impervious Total 0.68 Basin Total 1.134 Name : Gravel Trench Bed 1 Bottom Length: 91.17 ft. Bottom Width: 91.17 ft. Trench bottom slope 1: 0.01 To 1 Trench Left side slope 0: 0.01 To 1 Trench right side slope 2: 0.01 To 1 Material thickness of first layer: 3.5 Pour Space of material for first layer: 0.56 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Discharge Structure Riser Height: 3.5 ft. Riser Diameter: 18 in. Notch Type: Rectangular Notch Width: 0.010 ft. Notch Height: 1.444 ft. Orifice 1 Diameter: 0.653 in. Elevation: 0 ft. Element Flows To: Outlet 1 Outlet 2 ___________________________________________________________________ Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.190 0.000 0.000 0.000 0.0500 0.190 0.005 0.002 0.000 0.1000 0.190 0.010 0.003 0.000 91.17' x 91.17' = 8311 sf which equals the footprint of the Detention Gallery = Average Porosity of Detention Gallery (including Stormtech chamber volume and rock voids) MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-4 of 22 Drainage Report - MAGA0001 0.1500 0.190 0.016 0.004 0.000 0.2000 0.190 0.021 0.005 0.000 0.2500 0.190 0.026 0.005 0.000 0.3000 0.190 0.032 0.006 0.000 0.3500 0.190 0.037 0.006 0.000 0.4000 0.190 0.042 0.007 0.000 0.4500 0.190 0.048 0.007 0.000 0.5000 0.190 0.053 0.008 0.000 0.5500 0.190 0.058 0.008 0.000 0.6000 0.190 0.064 0.009 0.000 0.6500 0.190 0.069 0.009 0.000 0.7000 0.190 0.074 0.009 0.000 0.7500 0.190 0.080 0.010 0.000 0.8000 0.190 0.085 0.010 0.000 0.8500 0.190 0.090 0.010 0.000 0.9000 0.190 0.096 0.011 0.000 0.9500 0.190 0.101 0.011 0.000 1.0000 0.190 0.106 0.011 0.000 1.0500 0.190 0.112 0.011 0.000 1.1000 0.190 0.117 0.012 0.000 1.1500 0.190 0.122 0.012 0.000 1.2000 0.190 0.128 0.012 0.000 1.2500 0.190 0.133 0.012 0.000 1.3000 0.190 0.139 0.013 0.000 1.3500 0.190 0.144 0.013 0.000 1.4000 0.190 0.149 0.013 0.000 1.4500 0.190 0.155 0.013 0.000 1.5000 0.190 0.160 0.014 0.000 1.5500 0.190 0.165 0.014 0.000 1.6000 0.191 0.171 0.014 0.000 1.6500 0.191 0.176 0.014 0.000 1.7000 0.191 0.181 0.015 0.000 1.7500 0.191 0.187 0.015 0.000 1.8000 0.191 0.192 0.015 0.000 1.8500 0.191 0.197 0.015 0.000 1.9000 0.191 0.203 0.016 0.000 1.9500 0.191 0.208 0.016 0.000 2.0000 0.191 0.213 0.016 0.000 2.0500 0.191 0.219 0.016 0.000 2.1000 0.191 0.224 0.017 0.000 2.1500 0.191 0.229 0.017 0.000 2.2000 0.191 0.235 0.018 0.000 2.2500 0.191 0.240 0.020 0.000 2.3000 0.191 0.245 0.021 0.000 2.3500 0.191 0.251 0.022 0.000 2.4000 0.191 0.256 0.024 0.000 2.4500 0.191 0.261 0.025 0.000 2.5000 0.191 0.267 0.027 0.000 2.5500 0.191 0.272 0.028 0.000 2.6000 0.191 0.278 0.030 0.000 2.6500 0.191 0.283 0.032 0.000 2.7000 0.191 0.288 0.034 0.000 2.7500 0.191 0.294 0.035 0.000 2.8000 0.191 0.299 0.037 0.000 2.8500 0.191 0.304 0.039 0.000 2.9000 0.191 0.310 0.041 0.000 2.9500 0.191 0.315 0.043 0.000 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-5 of 22 Drainage Report - MAGA0001 3.0000 0.191 0.320 0.044 0.000 3.0500 0.191 0.326 0.046 0.000 3.1000 0.191 0.331 0.048 0.000 3.1500 0.191 0.336 0.051 0.000 3.2000 0.191 0.342 0.053 0.000 3.2500 0.191 0.347 0.055 0.000 3.3000 0.191 0.352 0.058 0.000 3.3500 0.191 0.358 0.060 0.000 3.4000 0.191 0.363 0.062 0.000 3.4500 0.191 0.368 0.065 0.000 3.5000 0.191 0.374 0.082 0.000 3.5500 0.191 0.383 0.260 0.000 3.6000 0.191 0.393 0.585 0.000 3.6500 0.191 0.403 1.002 0.000 3.7000 0.191 0.412 1.487 0.000 3.7500 0.191 0.422 2.021 0.000 3.8000 0.191 0.431 2.584 0.000 3.8500 0.191 0.441 3.156 0.000 3.9000 0.191 0.450 3.716 0.000 3.9500 0.191 0.460 4.244 0.000 4.0000 0.191 0.469 4.723 0.000 4.0500 0.191 0.479 5.139 0.000 4.1000 0.191 0.489 5.485 0.000 4.1500 0.191 0.498 5.761 0.000 4.2000 0.191 0.508 5.977 0.000 4.2500 0.191 0.517 6.156 0.000 4.3000 0.191 0.527 6.423 0.000 4.3500 0.191 0.536 6.618 0.000 4.4000 0.191 0.546 6.808 0.000 4.4500 0.191 0.555 6.992 0.000 4.5000 0.191 0.565 7.172 0.000 ___________________________________________________________________ Name : Basin 2 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .227 C, Lawn, Mod .227 Pervious Total 0.454 Impervious Land Use acre ROADS FLAT 0.435 ROOF TOPS FLAT 0.245 Impervious Total 0.68 Basin Total 1.134 ___________________________________________________________________ .071 cfs = 100-year flowrate 3.5 feet = 100-year stage elevation MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-6 of 22 Drainage Report - MAGA0001 Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:1.134 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.454 Total Impervious Area:0.68 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.033357 5 year 0.0538 10 year 0.066406 25 year 0.080843 50 year 0.090485 100 year 0.099223 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.018745 5 year 0.028584 10 year 0.03664 25 year 0.048797 50 year 0.05944 100 year 0.071575 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.036 0.014 1950 0.043 0.017 1951 0.074 0.050 1952 0.023 0.013 1953 0.019 0.016 1954 0.029 0.015 1955 0.046 0.015 1956 0.037 0.029 1957 0.029 0.015 1958 0.033 0.016 1959 0.028 0.014 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-7 of 22 Drainage Report - MAGA0001 1960 0.050 0.038 1961 0.028 0.020 1962 0.017 0.012 1963 0.024 0.016 1964 0.033 0.017 1965 0.023 0.024 1966 0.022 0.015 1967 0.049 0.017 1968 0.028 0.015 1969 0.028 0.015 1970 0.023 0.016 1971 0.025 0.016 1972 0.055 0.041 1973 0.025 0.025 1974 0.027 0.016 1975 0.037 0.014 1976 0.026 0.015 1977 0.004 0.012 1978 0.023 0.017 1979 0.014 0.012 1980 0.059 0.045 1981 0.021 0.016 1982 0.041 0.026 1983 0.036 0.016 1984 0.022 0.013 1985 0.013 0.013 1986 0.058 0.018 1987 0.051 0.031 1988 0.020 0.014 1989 0.013 0.013 1990 0.115 0.040 1991 0.065 0.034 1992 0.026 0.018 1993 0.026 0.013 1994 0.009 0.011 1995 0.037 0.019 1996 0.082 0.048 1997 0.066 0.054 1998 0.015 0.013 1999 0.067 0.039 2000 0.026 0.016 2001 0.005 0.010 2002 0.029 0.021 2003 0.040 0.015 2004 0.047 0.044 2005 0.034 0.015 2006 0.040 0.028 2007 0.085 0.064 2008 0.107 0.044 2009 0.051 0.022 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.1146 0.0640 2 0.1075 0.0543 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-8 of 22 Drainage Report - MAGA0001 3 0.0853 0.0501 4 0.0819 0.0482 5 0.0736 0.0447 6 0.0668 0.0443 7 0.0657 0.0438 8 0.0646 0.0408 9 0.0589 0.0395 10 0.0578 0.0388 11 0.0553 0.0375 12 0.0514 0.0335 13 0.0511 0.0309 14 0.0503 0.0288 15 0.0486 0.0277 16 0.0471 0.0264 17 0.0458 0.0246 18 0.0435 0.0244 19 0.0413 0.0218 20 0.0403 0.0209 21 0.0396 0.0196 22 0.0374 0.0194 23 0.0371 0.0176 24 0.0367 0.0176 25 0.0361 0.0173 26 0.0356 0.0169 27 0.0344 0.0167 28 0.0331 0.0167 29 0.0327 0.0163 30 0.0294 0.0161 31 0.0287 0.0160 32 0.0285 0.0159 33 0.0284 0.0159 34 0.0284 0.0158 35 0.0280 0.0158 36 0.0277 0.0157 37 0.0272 0.0155 38 0.0265 0.0152 39 0.0258 0.0152 40 0.0258 0.0151 41 0.0256 0.0151 42 0.0249 0.0151 43 0.0248 0.0150 44 0.0239 0.0149 45 0.0232 0.0146 46 0.0231 0.0145 47 0.0228 0.0141 48 0.0225 0.0139 49 0.0220 0.0139 50 0.0217 0.0138 51 0.0207 0.0131 52 0.0202 0.0130 53 0.0187 0.0127 54 0.0174 0.0126 55 0.0155 0.0125 56 0.0140 0.0125 57 0.0132 0.0124 58 0.0131 0.0122 59 0.0087 0.0115 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-9 of 22 Drainage Report - MAGA0001 60 0.0046 0.0112 61 0.0036 0.0101 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0167 17550 11777 67 Pass 0.0174 15971 9918 62 Pass 0.0182 14647 8874 60 Pass 0.0189 13413 8104 60 Pass 0.0197 12239 7349 60 Pass 0.0204 11171 6827 61 Pass 0.0212 10235 6205 60 Pass 0.0219 9417 5580 59 Pass 0.0226 8673 5080 58 Pass 0.0234 8014 4605 57 Pass 0.0241 7381 4173 56 Pass 0.0249 6823 3846 56 Pass 0.0256 6308 3602 57 Pass 0.0264 5854 3362 57 Pass 0.0271 5467 3181 58 Pass 0.0279 5082 3003 59 Pass 0.0286 4750 2843 59 Pass 0.0294 4445 2671 60 Pass 0.0301 4145 2520 60 Pass 0.0308 3882 2325 59 Pass 0.0316 3604 2127 59 Pass 0.0323 3371 1966 58 Pass 0.0331 3136 1860 59 Pass 0.0338 2935 1746 59 Pass 0.0346 2733 1649 60 Pass 0.0353 2528 1544 61 Pass 0.0361 2370 1408 59 Pass 0.0368 2201 1252 56 Pass 0.0376 2049 1144 55 Pass 0.0383 1906 1051 55 Pass 0.0390 1778 962 54 Pass 0.0398 1674 879 52 Pass 0.0405 1553 816 52 Pass 0.0413 1430 747 52 Pass 0.0420 1319 643 48 Pass 0.0428 1237 580 46 Pass 0.0435 1157 493 42 Pass 0.0443 1095 418 38 Pass 0.0450 1039 344 33 Pass 0.0458 980 305 31 Pass 0.0465 905 266 29 Pass 0.0472 854 233 27 Pass 0.0480 801 210 26 Pass 0.0487 748 189 25 Pass 0.0495 711 173 24 Pass 0.0502 666 153 22 Pass MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-10 of 22 Drainage Report - MAGA0001 0.0510 621 146 23 Pass 0.0517 589 139 23 Pass 0.0525 556 132 23 Pass 0.0532 513 123 23 Pass 0.0540 480 114 23 Pass 0.0547 440 105 23 Pass 0.0554 399 103 25 Pass 0.0562 369 98 26 Pass 0.0569 343 84 24 Pass 0.0577 314 76 24 Pass 0.0584 288 62 21 Pass 0.0592 260 56 21 Pass 0.0599 234 50 21 Pass 0.0607 216 44 20 Pass 0.0614 194 39 20 Pass 0.0622 174 34 19 Pass 0.0629 149 28 18 Pass 0.0636 134 10 7 Pass 0.0644 121 0 0 Pass 0.0651 111 0 0 Pass 0.0659 99 0 0 Pass 0.0666 90 0 0 Pass 0.0674 80 0 0 Pass 0.0681 72 0 0 Pass 0.0689 68 0 0 Pass 0.0696 59 0 0 Pass 0.0704 51 0 0 Pass 0.0711 42 0 0 Pass 0.0718 39 0 0 Pass 0.0726 31 0 0 Pass 0.0733 25 0 0 Pass 0.0741 22 0 0 Pass 0.0748 20 0 0 Pass 0.0756 19 0 0 Pass 0.0763 17 0 0 Pass 0.0771 14 0 0 Pass 0.0778 12 0 0 Pass 0.0786 9 0 0 Pass 0.0793 6 0 0 Pass 0.0800 6 0 0 Pass 0.0808 6 0 0 Pass 0.0815 6 0 0 Pass 0.0823 5 0 0 Pass 0.0830 5 0 0 Pass 0.0838 5 0 0 Pass 0.0845 5 0 0 Pass 0.0853 4 0 0 Pass 0.0860 3 0 0 Pass 0.0868 3 0 0 Pass 0.0875 3 0 0 Pass 0.0882 3 0 0 Pass 0.0890 3 0 0 Pass 0.0897 3 0 0 Pass 0.0905 3 0 0 Pass MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-11 of 22 Drainage Report - MAGA0001 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-12 of 22 Drainage Report - MAGA0001 WWHM2012 PROJECT REPORT Water Quality Device Sizing ___________________________________________________________________ Project Name: WQ Device Site Name: samoan church Site Address: 29276 Military Road City : Federal Way Report Date: 10/5/2021 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2019/09/13 Version : 4.2.17 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Mod .046 Pervious Total 0.046 Impervious Land Use acre ROADS FLAT 0.344 Impervious Total 0.344 Basin Total 0.39 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-13 of 22 Drainage Report - MAGA0001 ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.046 Total Impervious Area:0.344 ___________________________________________________________________ Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.134673 5 year 0.171336 10 year 0.196384 25 year 0.229018 50 year 0.25409 100 year 0.279848 Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0.0438 acre-feet On-line facility target flow: 0.0554 cfs. Adjusted for 15 min: 0.0554 cfs. Off-line facility target flow: 0.0313 cfs. Adjusted for 15 min: 0.0313 cfs. Peak Flow to Filter 14.04 gpm A Biopod Biofilter that is 5' X 7' can accommodate a water quality design flow rate of 14.04 gpm. MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-14 of 22 Drainage Report - MAGA0001 WWHM2012 PROJECT REPORT Wetland Volume Analysis ___________________________________________________________________ Project Name: Wetland Input Site Name: samoan church Site Address: 29276 Military Road City : Federal Way Report Date: 10/5/2021 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2019/09/13 Version : 4.2.17 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat 2.33 A B, Forest, Mod 2.33 SAT, Forest, Flat 4.3 Pervious Total 8.96 Impervious Land Use acre ROADS FLAT 1.6 ROOF TOPS FLAT 4.66 Impervious Total 6.26 Basin Total 15.22 ___________________________________________________________________ MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-15 of 22 Drainage Report - MAGA0001 MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat 2.23 A B, Forest, Mod 2.23 SAT, Forest, Flat 4.3 Pervious Total 8.76 Impervious Land Use acre ROADS FLAT 1.6 ROOF TOPS FLAT 4.86 Impervious Total 6.46 Basin Total 15.22 ___________________________________________________________________ Wetlands Input Volume Average Annual Volume (acft) Series 1: 501 POC 1 Predeveloped flow Series 2: 801 POC 1 Mitigated flow Month Series 1 Series 2 Percent Pass/Fail Jan 3.0292 3.1156 102.8 Pass Feb 2.0625 2.1194 102.8 Pass Mar 1.7061 1.7536 102.8 Pass Apr 1.0035 1.0319 102.8 Pass May 0.5271 0.5431 103.0 Pass Jun 0.4388 0.4525 103.1 Pass Jul 0.1989 0.2052 103.2 Pass Aug 0.3621 0.3736 103.2 Pass Sep 0.5991 0.6182 103.2 Pass Oct 1.4692 1.5158 103.2 Pass Nov 2.9912 3.0836 103.1 Pass Dec 3.0404 3.1304 103.0 Pass Day Series 1 Series 2 Percent Pass/Fail Jan1 0.1336 0.1375 102.9 Pass 2 0.0785 0.0807 102.8 Pass 3 0.0994 0.1023 102.9 Pass 4 0.1203 0.1238 102.9 Pass 5 0.1016 0.1044 102.8 Pass 6 0.1256 0.1292 102.9 Pass 7 0.0880 0.0905 102.8 Pass 8 0.0982 0.1011 102.9 Pass 9 0.0848 0.0872 102.9 Pass 10 0.0773 0.0795 102.9 Pass 11 0.0854 0.0879 102.9 Pass Impervious Acreage increased by 0.2 acres Does not increase by more than 10% in any month or day MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-16 of 22 Drainage Report - MAGA0001 12 0.1101 0.1133 102.9 Pass 13 0.1320 0.1359 102.9 Pass 14 0.0992 0.1020 102.8 Pass 15 0.0917 0.0943 102.8 Pass 16 0.0952 0.0979 102.8 Pass 17 0.1031 0.1061 102.9 Pass 18 0.1055 0.1084 102.8 Pass 19 0.0965 0.0992 102.8 Pass 20 0.0883 0.0907 102.8 Pass 21 0.0850 0.0874 102.8 Pass 22 0.1203 0.1238 102.9 Pass 23 0.1152 0.1185 102.8 Pass 24 0.0775 0.0797 102.7 Pass 25 0.0750 0.0771 102.8 Pass 26 0.0770 0.0792 102.8 Pass 27 0.0789 0.0812 102.8 Pass 28 0.0996 0.1025 102.8 Pass 29 0.0949 0.0976 102.8 Pass 30 0.1067 0.1098 102.9 Pass 31 0.0787 0.0808 102.7 Pass Feb1 0.0744 0.0764 102.8 Pass 2 0.0587 0.0603 102.7 Pass 3 0.0627 0.0645 102.7 Pass 4 0.0505 0.0518 102.7 Pass 5 0.0798 0.0821 102.8 Pass 6 0.0758 0.0778 102.7 Pass 7 0.1079 0.1108 102.7 Pass 8 0.0794 0.0814 102.5 Pass 9 0.0597 0.0614 102.8 Pass 10 0.0561 0.0577 102.9 Pass 11 0.0858 0.0883 102.9 Pass 12 0.0696 0.0716 102.8 Pass 13 0.0648 0.0666 102.8 Pass 14 0.0812 0.0836 102.9 Pass 15 0.0942 0.0969 102.9 Pass 16 0.0801 0.0824 102.8 Pass 17 0.0914 0.0940 102.8 Pass 18 0.1014 0.1043 102.8 Pass 19 0.0577 0.0592 102.6 Pass 20 0.0675 0.0694 102.7 Pass 21 0.0590 0.0607 102.7 Pass 22 0.0642 0.0660 102.8 Pass 23 0.0773 0.0794 102.7 Pass 24 0.0686 0.0706 102.8 Pass 25 0.0566 0.0581 102.7 Pass 26 0.0724 0.0743 102.6 Pass 27 0.0719 0.0738 102.7 Pass 28 0.0578 0.0593 102.7 Pass 29 0.0614 0.0631 102.8 Pass Mar1 0.0585 0.0601 102.8 Pass 2 0.0879 0.0903 102.8 Pass 3 0.0622 0.0639 102.8 Pass 4 0.0799 0.0821 102.6 Pass 5 0.0365 0.0375 102.6 Pass 6 0.0449 0.0461 102.7 Pass 7 0.0629 0.0647 102.9 Pass 8 0.0744 0.0765 102.9 Pass Does not increase by more than 10% in any day MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-17 of 22 Drainage Report - MAGA0001 9 0.0642 0.0660 102.8 Pass 10 0.0727 0.0748 102.8 Pass 11 0.0834 0.0858 102.8 Pass 12 0.0504 0.0517 102.7 Pass 13 0.0547 0.0562 102.8 Pass 14 0.0630 0.0647 102.8 Pass 15 0.0517 0.0531 102.8 Pass 16 0.0490 0.0503 102.7 Pass 17 0.0628 0.0645 102.7 Pass 18 0.0406 0.0416 102.6 Pass 19 0.0390 0.0401 102.8 Pass 20 0.0290 0.0298 102.7 Pass 21 0.0642 0.0661 102.9 Pass 22 0.0643 0.0662 102.9 Pass 23 0.0573 0.0590 102.9 Pass 24 0.0418 0.0429 102.8 Pass 25 0.0417 0.0429 102.8 Pass 26 0.0402 0.0413 102.8 Pass 27 0.0410 0.0421 102.8 Pass 28 0.0492 0.0507 102.9 Pass 29 0.0432 0.0444 102.8 Pass 30 0.0343 0.0352 102.7 Pass 31 0.0375 0.0385 102.8 Pass Apr1 0.0367 0.0378 102.8 Pass 2 0.0386 0.0397 102.8 Pass 3 0.0604 0.0621 102.7 Pass 4 0.0435 0.0447 102.7 Pass 5 0.0375 0.0385 102.8 Pass 6 0.0238 0.0244 102.7 Pass 7 0.0410 0.0422 102.9 Pass 8 0.0454 0.0468 102.9 Pass 9 0.0277 0.0285 102.8 Pass 10 0.0359 0.0369 102.9 Pass 11 0.0338 0.0348 102.9 Pass 12 0.0448 0.0461 102.9 Pass 13 0.0334 0.0343 102.9 Pass 14 0.0304 0.0312 102.8 Pass 15 0.0455 0.0468 102.9 Pass 16 0.0316 0.0325 102.8 Pass 17 0.0160 0.0164 102.7 Pass 18 0.0624 0.0642 102.9 Pass 19 0.0225 0.0231 102.7 Pass 20 0.0136 0.0140 102.7 Pass 21 0.0322 0.0331 102.9 Pass 22 0.0417 0.0428 102.7 Pass 23 0.0232 0.0239 102.9 Pass 24 0.0171 0.0176 102.8 Pass 25 0.0128 0.0132 102.8 Pass 26 0.0336 0.0346 103.0 Pass 27 0.0187 0.0193 102.9 Pass 28 0.0324 0.0334 103.0 Pass 29 0.0300 0.0308 103.0 Pass 30 0.0275 0.0283 102.9 Pass May1 0.0181 0.0186 102.9 Pass 2 0.0145 0.0150 102.8 Pass 3 0.0196 0.0202 102.9 Pass 4 0.0196 0.0202 103.0 Pass Does not increase by more than 10% in any day MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-18 of 22 Drainage Report - MAGA0001 5 0.0222 0.0229 103.0 Pass 6 0.0142 0.0146 102.9 Pass 7 0.0114 0.0117 102.9 Pass 8 0.0120 0.0123 103.0 Pass 9 0.0137 0.0141 103.0 Pass 10 0.0214 0.0220 103.1 Pass 11 0.0112 0.0116 103.0 Pass 12 0.0131 0.0135 103.0 Pass 13 0.0214 0.0221 103.1 Pass 14 0.0161 0.0166 103.1 Pass 15 0.0130 0.0133 103.0 Pass 16 0.0128 0.0132 103.1 Pass 17 0.0170 0.0176 103.1 Pass 18 0.0219 0.0226 103.1 Pass 19 0.0123 0.0127 103.0 Pass 20 0.0096 0.0098 103.0 Pass 21 0.0091 0.0094 103.0 Pass 22 0.0161 0.0167 103.1 Pass 23 0.0170 0.0175 103.1 Pass 24 0.0089 0.0091 103.0 Pass 25 0.0238 0.0245 103.1 Pass 26 0.0175 0.0181 103.1 Pass 27 0.0166 0.0172 103.1 Pass 28 0.0265 0.0274 103.1 Pass 29 0.0244 0.0252 103.1 Pass 30 0.0246 0.0254 103.1 Pass 31 0.0207 0.0213 103.1 Pass Jun1 0.0141 0.0145 103.1 Pass 2 0.0234 0.0241 103.1 Pass 3 0.0241 0.0249 103.1 Pass 4 0.0122 0.0125 103.1 Pass 5 0.0247 0.0255 103.1 Pass 6 0.0200 0.0207 103.1 Pass 7 0.0163 0.0168 103.1 Pass 8 0.0188 0.0194 103.1 Pass 9 0.0189 0.0195 103.1 Pass 10 0.0202 0.0208 103.1 Pass 11 0.0176 0.0181 103.1 Pass 12 0.0058 0.0060 103.0 Pass 13 0.0052 0.0053 103.0 Pass 14 0.0099 0.0102 103.1 Pass 15 0.0109 0.0112 103.1 Pass 16 0.0192 0.0198 103.1 Pass 17 0.0065 0.0067 103.1 Pass 18 0.0071 0.0073 103.1 Pass 19 0.0140 0.0145 103.1 Pass 20 0.0140 0.0144 103.1 Pass 21 0.0077 0.0080 103.1 Pass 22 0.0105 0.0108 103.1 Pass 23 0.0372 0.0383 103.2 Pass 24 0.0100 0.0103 103.1 Pass 25 0.0068 0.0070 103.1 Pass 26 0.0078 0.0081 103.2 Pass 27 0.0120 0.0123 103.2 Pass 28 0.0110 0.0113 103.2 Pass 29 0.0126 0.0130 103.2 Pass 30 0.0138 0.0143 103.2 Pass Does not increase by more than 10% in any day MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-19 of 22 Drainage Report - MAGA0001 Jul1 0.0085 0.0088 103.2 Pass 2 0.0080 0.0083 103.2 Pass 3 0.0052 0.0053 103.2 Pass 4 0.0100 0.0103 103.2 Pass 5 0.0040 0.0041 103.2 Pass 6 0.0082 0.0085 103.2 Pass 7 0.0107 0.0110 103.2 Pass 8 0.0133 0.0137 103.2 Pass 9 0.0076 0.0079 103.2 Pass 10 0.0028 0.0029 103.2 Pass 11 0.0135 0.0139 103.2 Pass 12 0.0096 0.0099 103.2 Pass 13 0.0088 0.0091 103.2 Pass 14 0.0009 0.0009 103.0 Pass 15 0.0191 0.0197 103.2 Pass 16 0.0049 0.0051 103.2 Pass 17 0.0022 0.0023 103.1 Pass 18 0.0056 0.0058 103.2 Pass 19 0.0040 0.0042 103.2 Pass 20 0.0023 0.0023 103.2 Pass 21 0.0055 0.0057 103.2 Pass 22 0.0034 0.0035 103.2 Pass 23 0.0017 0.0018 103.2 Pass 24 0.0025 0.0026 103.2 Pass 25 0.0136 0.0141 103.2 Pass 26 0.0031 0.0032 103.2 Pass 27 0.0026 0.0027 103.2 Pass 28 0.0006 0.0006 103.1 Pass 29 0.0016 0.0017 103.2 Pass 30 0.0012 0.0012 103.2 Pass 31 0.0060 0.0062 103.2 Pass Aug1 0.0083 0.0086 103.2 Pass 2 0.0105 0.0108 103.2 Pass 3 0.0052 0.0053 103.2 Pass 4 0.0012 0.0012 103.1 Pass 5 0.0119 0.0123 103.2 Pass 6 0.0136 0.0140 103.2 Pass 7 0.0017 0.0018 103.1 Pass 8 0.0110 0.0114 103.2 Pass 9 0.0023 0.0024 103.1 Pass 10 0.0047 0.0048 103.2 Pass 11 0.0045 0.0046 103.2 Pass 12 0.0027 0.0028 103.2 Pass 13 0.0165 0.0170 103.2 Pass 14 0.0189 0.0195 103.2 Pass 15 0.0055 0.0057 103.2 Pass 16 0.0097 0.0100 103.2 Pass 17 0.0179 0.0185 103.2 Pass 18 0.0157 0.0162 103.2 Pass 19 0.0073 0.0075 103.2 Pass 20 0.0146 0.0151 103.2 Pass 21 0.0215 0.0222 103.2 Pass 22 0.0329 0.0340 103.2 Pass 23 0.0206 0.0213 103.2 Pass 24 0.0144 0.0149 103.2 Pass 25 0.0179 0.0185 103.2 Pass 26 0.0173 0.0178 103.2 Pass Does not increase by more than 10% in any day MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-20 of 22 Drainage Report - MAGA0001 27 0.0123 0.0127 103.2 Pass 28 0.0174 0.0179 103.2 Pass 29 0.0084 0.0087 103.2 Pass 30 0.0098 0.0102 103.2 Pass 31 0.0143 0.0148 103.2 Pass Sep1 0.0172 0.0177 103.2 Pass 2 0.0109 0.0113 103.2 Pass 3 0.0198 0.0204 103.2 Pass 4 0.0086 0.0089 103.2 Pass 5 0.0184 0.0190 103.2 Pass 6 0.0033 0.0034 103.2 Pass 7 0.0173 0.0178 103.2 Pass 8 0.0102 0.0105 103.2 Pass 9 0.0225 0.0232 103.2 Pass 10 0.0142 0.0146 103.2 Pass 11 0.0058 0.0060 103.2 Pass 12 0.0090 0.0093 103.2 Pass 13 0.0235 0.0243 103.2 Pass 14 0.0135 0.0139 103.2 Pass 15 0.0171 0.0176 103.2 Pass 16 0.0518 0.0535 103.2 Pass 17 0.0205 0.0212 103.2 Pass 18 0.0265 0.0274 103.2 Pass 19 0.0228 0.0235 103.2 Pass 20 0.0184 0.0190 103.2 Pass 21 0.0409 0.0422 103.2 Pass 22 0.0239 0.0247 103.2 Pass 23 0.0225 0.0232 103.2 Pass 24 0.0212 0.0218 103.2 Pass 25 0.0229 0.0237 103.2 Pass 26 0.0239 0.0247 103.2 Pass 27 0.0264 0.0273 103.2 Pass 28 0.0165 0.0170 103.2 Pass 29 0.0353 0.0365 103.2 Pass 30 0.0195 0.0201 103.2 Pass Oct1 0.0207 0.0213 103.2 Pass 2 0.0308 0.0318 103.2 Pass 3 0.0431 0.0444 103.2 Pass 4 0.0291 0.0301 103.2 Pass 5 0.0581 0.0599 103.2 Pass 6 0.0273 0.0282 103.1 Pass 7 0.0652 0.0672 103.2 Pass 8 0.0586 0.0605 103.2 Pass 9 0.0503 0.0519 103.2 Pass 10 0.0222 0.0229 103.1 Pass 11 0.0277 0.0285 103.2 Pass 12 0.0314 0.0324 103.2 Pass 13 0.0341 0.0352 103.2 Pass 14 0.0289 0.0298 103.2 Pass 15 0.0336 0.0347 103.2 Pass 16 0.0535 0.0552 103.2 Pass 17 0.0441 0.0455 103.2 Pass 18 0.0593 0.0612 103.2 Pass 19 0.1028 0.1061 103.2 Pass 20 0.0606 0.0626 103.2 Pass 21 0.0530 0.0547 103.2 Pass 22 0.0444 0.0459 103.2 Pass Does not increase by more than 10% in any day MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-21 of 22 Drainage Report - MAGA0001 23 0.0485 0.0500 103.2 Pass 24 0.0535 0.0552 103.2 Pass 25 0.0629 0.0649 103.2 Pass 26 0.0741 0.0764 103.2 Pass 27 0.0631 0.0651 103.2 Pass 28 0.0552 0.0570 103.2 Pass 29 0.0418 0.0431 103.1 Pass 30 0.0720 0.0742 103.2 Pass 31 0.0624 0.0644 103.2 Pass Nov1 0.0810 0.0836 103.2 Pass 2 0.1084 0.1118 103.2 Pass 3 0.1036 0.1069 103.2 Pass 4 0.0582 0.0600 103.1 Pass 5 0.0971 0.1001 103.2 Pass 6 0.0721 0.0744 103.1 Pass 7 0.0681 0.0703 103.1 Pass 8 0.1019 0.1051 103.2 Pass 9 0.1045 0.1078 103.2 Pass 10 0.1303 0.1344 103.1 Pass 11 0.1127 0.1162 103.1 Pass 12 0.1133 0.1168 103.1 Pass 13 0.0906 0.0934 103.1 Pass 14 0.0715 0.0737 103.1 Pass 15 0.0997 0.1029 103.1 Pass 16 0.0969 0.0999 103.1 Pass 17 0.0826 0.0852 103.1 Pass 18 0.1392 0.1435 103.1 Pass 19 0.1281 0.1319 103.0 Pass 20 0.0890 0.0917 103.0 Pass 21 0.0855 0.0881 103.0 Pass 22 0.1367 0.1409 103.1 Pass 23 0.1427 0.1470 103.0 Pass 24 0.1417 0.1460 103.1 Pass 25 0.0994 0.1024 103.0 Pass 26 0.0868 0.0894 103.0 Pass 27 0.0782 0.0805 103.0 Pass 28 0.0924 0.0952 103.0 Pass 29 0.1172 0.1207 103.0 Pass 30 0.1049 0.1081 103.0 Pass Dec1 0.1111 0.1144 103.0 Pass 2 0.1455 0.1498 103.0 Pass 3 0.0759 0.0782 102.9 Pass 4 0.1086 0.1119 103.0 Pass 5 0.0863 0.0889 103.0 Pass 6 0.0755 0.0778 103.0 Pass 7 0.0838 0.0863 103.0 Pass 8 0.1010 0.1041 103.0 Pass 9 0.1168 0.1204 103.0 Pass 10 0.1088 0.1121 103.0 Pass 11 0.1104 0.1137 103.0 Pass 12 0.1112 0.1145 103.0 Pass 13 0.1125 0.1158 103.0 Pass 14 0.1289 0.1327 102.9 Pass 15 0.0972 0.1000 103.0 Pass 16 0.0767 0.0790 102.9 Pass 17 0.0777 0.0800 102.9 Pass 18 0.0843 0.0868 103.0 Pass Does not increase by more than 10% in any day MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page D-22 of 22 Drainage Report - MAGA0001 19 0.1147 0.1181 103.0 Pass 20 0.0975 0.1004 102.9 Pass 21 0.0849 0.0874 102.9 Pass 22 0.0907 0.0934 102.9 Pass 23 0.0753 0.0775 102.9 Pass 24 0.0874 0.0900 102.9 Pass 25 0.1155 0.1189 102.9 Pass 26 0.1058 0.1089 102.9 Pass 27 0.0593 0.0609 102.8 Pass 28 0.1133 0.1166 103.0 Pass 29 0.1101 0.1133 102.9 Pass 30 0.0689 0.0708 102.8 Pass 31 0.0850 0.0875 102.9 Pass ___________________________________________________________________ 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. 2005-2021; All Rights Reserved. Does not increase by more than 10% in any day MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page E-1 of 1 Drainage Report - MAGA0001 Appendix E - Construction Stormwater Pollution Prevention Plan (C-SWPPP) MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page F-1 of 1 Drainage Report - MAGA0001 Appendix F - USDA Web Soil Survey Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2021 Page 1 of 352428505242900524295052430005243050524310052431505242850524290052429505243000524305052431005243150552620552670552720552770552820552870552920552970553020553070 552620 552670 552720 552770 552820 552870 552920 552970 553020 553070 553120 47° 20' 23'' N 122° 18' 12'' W47° 20' 23'' N122° 17' 48'' W47° 20' 12'' N 122° 18' 12'' W47° 20' 12'' N 122° 17' 48'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 100 200 400 600 Feet 0 30 60 120 180 Meters Map Scale: 1:2,320 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 17, Aug 23, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 6, 2020—Jul 20, 2020 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2021 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI AgB Alderwood gravelly sandy loam, 0 to 8 percent slopes 9.4 36.3% AgC Alderwood gravelly sandy loam, 8 to 15 percent slopes 6.7 25.8% AmB Arents, Alderwood material, 0 to 6 percent slopes 5.2 19.9% Or Orcas peat 4.7 18.0% Totals for Area of Interest 25.9 100.0% Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2021 Page 3 of 3 MC# MAGA-0001 Preliminary Technical Information Report | 100% 10/11/2021 Midway Samoan Church Page G-1 of 1 Drainage Report - MAGA0001 Appendix G - Geotechnical Report Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone 425.415.0551 ♦ Fax 425.415.0311 www.riley-group.com GEOTECHNICAL ENGINEERING REPORT PREPARED BY: THE RILEY GROUP, INC. 17522 BOTHELL WAY NORTHEAST BOTHELL, WASHINGTON 98011 PREPARED FOR: MAGELLAN ARCHITECTS 8383 158TH AVENUE, SUITE 280 REDMOND, WASHINGTON 98052 RGI PROJECT NO. 2020-507-1 MIDWAY SAMOAN AG CHURCH 29276 MILITARY ROAD SOUTH FEDERAL WAY, WASHINGTON NOVEMBER 13, 2020 Geotechnical Engineering Report i November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 TABLE OF CONTENTS 1.0 INTRODUCTION ............................................................................................................................... 1 2.0 PROJECT DESCRIPTION ............................................................................................................... 1 3.0 FIELD EXPLORATION AND LABORATORY TESTING .......................................................... 1 3.1 FIELD EXPLORATION ................................................................................................................................... 1 3.2 LABORATORY TESTING ................................................................................................................................ 2 4.0 SITE CONDITIONS ........................................................................................................................... 2 4.1 SURFACE .................................................................................................................................................. 2 4.2 GEOLOGY ................................................................................................................................................. 2 4.3 SOILS ....................................................................................................................................................... 2 4.4 GROUNDWATER ........................................................................................................................................ 3 4.5 SEISMIC CONSIDERATIONS ........................................................................................................................... 3 4.6 GEOLOGIC HAZARD AREAS .......................................................................................................................... 4 5.0 DISCUSSION AND RECOMMENDATIONS ................................................................................. 4 5.1 GEOTECHNICAL CONSIDERATIONS ................................................................................................................. 4 5.2 EARTHWORK ............................................................................................................................................. 5 5.2.1 Erosion and Sediment Control ..................................................................................................... 5 5.2.2 Stripping and Subgrade Preparation ............................................................................................ 6 5.2.3 Excavations................................................................................................................................... 6 5.2.4 Structural Fill ................................................................................................................................ 7 5.2.5 Wet Weather Construction Considerations ................................................................................. 8 5.3 FOUNDATIONS .......................................................................................................................................... 9 5.4 RETAINING WALLS ................................................................................................................................... 10 5.5 SLAB-ON-GRADE CONSTRUCTION ............................................................................................................... 10 5.6 DRAINAGE .............................................................................................................................................. 11 5.6.1 Surface ....................................................................................................................................... 11 5.6.2 Subsurface .................................................................................................................................. 11 5.6.3 Infiltration .................................................................................................................................. 11 5.7 UTILITIES ................................................................................................................................................ 11 5.8 PAVEMENTS ............................................................................................................................................ 11 6.0 ADDITIONAL SERVICES .............................................................................................................. 12 7.0 LIMITATIONS ................................................................................................................................. 12 LIST OF FIGURES AND APPENDICES Figure 1 ..................................................................................................................... Site Vicinity Map Figure 2 ............................................................................................... Geotechnical Exploration Plan Figure 3 ............................................................................................... Retaining Wall Drainage Detail Figure 4 ....................................................................................................Typical Footing Drain Detail Appendix A .......................................................................... Field Exploration and Laboratory Testing Geotechnical Engineering Report November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 Executive Summary This Executive Summary should be used in conjunction with the entire Geotechnical Engineering Report (GER) for design and/or construction purposes. It should be recognized that specific details were not included or fully developed in this section, and the GER must be read in its entirety for a comprehensive understanding of the items contained herein. Section 7.0 should be read for an understanding of limitations. RGI’s geotechnical scope of work included the advancement of eight test pit explorations to approximate depths of 6 to 10 feet below existing site grades. Based on the information obtained from our subsurface exploration, the site is challenging for development. The peat should be removed from the site and backfilled with structural fill. The following geotechnical considerations were identified: Soil Conditions: The soils encountered during field exploration include two to seven feet of medium dense to dense fill comprised of sandy gravel, silty gravel with some sand, silty sand with varying amounts of gravel, and 5/8” minus crushed rock over native deposits of soft peat, stiff to very stiff silt with varying amounts of sand, and medium dense silty sand with varying amounts of gravel and sand with some silt and gravel. Groundwater: Groundwater seepage was encountered at four location at depths of 4.5 to 8 feet during our subsurface exploration. Foundations: Foundations for the proposed building may be supported on conventional spread footings bearing on structural fill after peat is removed. Slab-on-grade: Slab-on-grade floors and slabs for the proposed building can be supported on structural fill after peat is removed. Pavements: The peat below the proposed parking area should be completely removed to avoid future settlement. However, if some settlement is allowed, the following pavement sections are recommended:  3 inches of hot mix asphalt (HMA) over 6 inches of crushed rock base (CRB) over structural fill after recompaction. Geotechnical Engineering Report 1 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 1.0 Introduction This Geotechnical Engineering Report (GER) presents the results of the geotechnical engineering services provided for the Midway Samoan AG Church in Federal Way, Washington. The purpose of this evaluation is to assess subsurface conditions and provide geotechnical recommendations for the construction of a church building. Our scope of services included field explorations, laboratory testing, engineering analyses, and preparation of this GER. The recommendations in the following sections of this GER are based upon our current understanding of the proposed site development as outlined below. If actual features vary or changes are made, RGI should review them in order to modify our recommendations as required. In addition, RGI requests to review the site grading plan, final design drawings and specifications when available to verify that our project understanding is correct and that our recommendations have been properly interpreted and incorporated into the project design and construction. 2.0 Project description The project site is located at 29276 Military Road South in Federal Way, Washington. The approximate location of the site is shown on Figure 1. The site is currently occupied by a church building, a single-family residence, an outbuilding, and a concrete slab. RGI understands that the existing structures will be removed and a new church with a paved parking lot will be constructed on the site. At the time of preparing this GER, building plans were not available for our review. Based on our experience with similar construction, RGI anticipates that the proposed building will be supported on perimeter walls with bearing loads of one to three kips per linear foot, and a series of columns with a maximum load up to 50 kips. Slab-on-grade floor loading of 250 pounds per square foot (psf) are expected. 3.0 Field Exploration and Laboratory Testing 3.1 FIELD EXPLORATION On October 28, 2020, RGI observed the excavation of eight test pit explorations. The approximate exploration locations are shown on Figure 2. Field logs of each exploration were prepared by the geologist that continuously observed the excavation. These logs included visual classifications of the materials encountered during excavating as well as our interpretation of the subsurface conditions between samples. The test pit logs included in Appendix A represent an interpretation of the field Geotechnical Engineering Report 2 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 logs and include modifications based on laboratory observation and analysis of the samples. 3.2 LABORATORY TESTING During the field exploration, a representative portion of each recovered sample was sealed in containers and transported to our laboratory for further visual and laboratory examination. Selected samples retrieved from the test pit explorations were tested for moisture content and grain size analysis to aid in soil classification and provide input for the recommendations provided in this GER. The results and descriptions of the laboratory tests are enclosed in Appendix A. 4.0 Site Conditions 4.1 SURFACE The subject site is an irregular-shaped site comprised of two parcels totaling approximately 2.48 acres in size. The site is bound to the north by a single family residence and wetland, to the east by a residential development, to the south by a single family residence, and to the west by Military Road South. The existing site is occupied by a church building, a single family residence, an outbuilding, and a concrete slab. The site slopes east with about 10 feet of elevation change across the site. The eastern portion of the site is occupied by a wetland area with a stream extending along the eastern property line. The site is vegetated with grass, wetland plants and shrubs and several scattered medium- to large-diameter trees. 4.2 GEOLOGY Review of the Lidar-Revised Geologic Map of the Poverty Bay 7.5’ Quadrangle, King and Pierce Counties, Washington, by R.W. Tabor, etc. (2014) indicates that the soil in the western edge of the site is mapped as Till (Map Unit Qvt), which is light to dark gray, nonsorted, nonstratified mixture of clay, silt, sand, and gravel. Most of the site is mapped as Recessional outwash deposits (Qvr), which is stratified sand and gravel, silty sand, and silt deposited in outwash channels draining meltwater from the receding glacier. The descriptions for recessional outwash deposits are generally similar to the findings in our field explorations with exception that peat was encountered at shallow depth. 4.3 SOILS The soils encountered during field exploration include two to seven feet of medium dense to dense fill comprised of sandy gravel, silty gravel with some sand, silty sand with varying amounts of gravel, and 5/8” minus crushed rock over native deposits of soft peat, stiff to Geotechnical Engineering Report 3 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 very stiff silt with varying amounts of sand, and medium dense silty sand with varying amounts of gravel and sand with some silt and gravel. More detailed descriptions of the subsurface conditions encountered are presented in the test pit logs included in Appendix A. Sieve analysis was performed on four selected soil samples. Grain size distribution curves are included in Appendix A. 4.4 GROUNDWATER Groundwater seepage was encountered at four location at depths of 4.5 to 8 feet during our subsurface exploration. It should be recognized that fluctuations of the groundwater table will occur due to seasonal variations in the amount of rainfall, runoff, and other factors not evident at the time the explorations were performed. In addition, perched water can develop within seams and layers contained in fill soils or higher permeability soils overlying less permeable soils following periods of heavy or prolonged precipitation. Therefore, groundwater levels during construction or at other times in the future may be higher or lower than the levels indicated on the logs. Groundwater level fluctuations should be considered when developing the design and construction plans for the project. 4.5 SEISMIC CONSIDERATIONS Based on the International Building Code (IBC), RGI recommends the follow seismic parameters for design. Table 1 IBC Parameter 2015 Value 2018 Value Site Soil Class1 D2 Site Latitude 47.3380 Site Longitude -122.2995 Short Period Spectral Response Acceleration, SS (g) 1.304 1.33 1-Second Period Spectral Response Acceleration, S1 (g) 0.498 0.456 Adjusted Short Period Spectral Response Acceleration, SMS (g) 1.304 1.596 Adjusted 1-Sec Period Spectral Response Acceleration, SM1 (g) 0.748 0.841 Numeric seismic design value at 0.2 second; SDS(g) 0.869 1.064 Numeric seismic design value at 1.0 second; SM1(g) 0.499 0.561 1. Note: In general accordance with Chapter 20 of ASCE 7-10. The Site Class is based on the average characteristics of the upper 100 feet of the subsurface profile. 2. Note: The 2015 IBC and ASCE 7-10 require a site soil profile determination extending to a depth of 100 feet for seismic site classification. The current scope of our services does not include the required 100 foot soil profile determination. Test pit explorations Geotechnical Engineering Report 4 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 extended to a maximum depth of 10 feet, and this seismic site class definition considers that similar soil continues below the maximum depth of the subsurface exploration. Additional exploration to deeper depths would be required to confirm the conditions below the current depth of exploration. 3. Note: In accordance with ASCE 11.4.8, a ground motion hazard analysis is not required for the following cases: • Structures on Site Class E sites with SS greater than or equal to 1.0, provided the site coefficient Fa is taken as equal to that of Site Class C. • Structures on Site Class D sites with S1 greater than or equal to 0.2, provided that the value of the seismic response coefficient Cs is determined by Eq. 12.8-2 for values of T ≤ 1.5Ts and taken as equal to 1.5 times the value computed in accordance with either Eq. 12.8-3 for TL ≥ T > 1.5Ts or Eq. 12.8-4 for T > TL. • Structures on Site Class E sites with S1 greater than or equal to 0.2, provided that T is less than or equal to Ts and the equivalent static force procedure is used for design. The above exceptions do not apply to seismically isolated structures, structures with damping systems or structures designed using the response history procedures of Chapter 16. Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in water pressure induced by vibrations from a seismic event. Liquefaction mainly affects geologically recent deposits of fine-grained sands that are below the groundwater table. Soils of this nature derive their strength from intergranular friction. The generated water pressure or pore pressure essentially separates the soil grains and eliminates this intergranular friction, thus reducing or eliminating the soil’s strength. RGI reviewed the results of the field and laboratory testing and assessed the potential for liquefaction of the site’s soil during an earthquake. Since the site is underlain by generally medium dense recessional deposits, RGI considers that the possibility of liquefaction during an earthquake is low to moderate. Review of the Liquefaction Susceptibility Map of King County, Washington by Stephen P. Palmer, etc. (2004) indicates the western edge of the site is mapped as having Moderate Liquefaction Susceptibility and the rest of the site is mapped as having Low to Moderate Liquefaction Susceptibility. 4.6 GEOLOGIC HAZARD AREAS Regulated geologically hazardous areas include erosion, landslide, earthquake, or other geological hazards. Based on review of the City of Federal Way Critical Areas Map, the site does not contain geologically hazardous areas. 5.0 Discussion and Recommendations 5.1 GEOTECHNICAL CONSIDERATIONS Based on our study, the site is challenging for the proposed development. If the building foundation is supported on shallow footings bearing on native soil, it will experience a significant amount of post-construction settlement due to consolidation settlement of peat. To avoid potential damages to building structures, the peat should be completely removed in the building pad area and backfilled with structural fill. Foundations for the proposed building can be supported on conventional spread footings bearing on competent structural fill. Slab-on-grade floors can be similarly supported on structural fill after overexcavation of peat. Geotechnical Engineering Report 5 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 Detailed recommendations regarding the above issues and other geotechnical design considerations are provided in the following sections. These recommendations should be incorporated into the final design drawings and construction specifications. 5.2 EARTHWORK The earthwork is expected to include excavating and backfilling the building foundations and preparing slab subgrades. 5.2.1 EROSION AND SEDIMENT CONTROL Potential sources or causes of erosion and sedimentation depend on construction methods, slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing and weather. The impacts on erosion-prone areas can be reduced by implementing an erosion and sedimentation control plan. The plan should be designed in accordance with applicable city and/or county standards. RGI recommends the following erosion control Best Management Practices (BMPs):  Scheduling site preparation and grading for the drier summer and early fall months and undertaking activities that expose soil during periods of little or no rainfall  Retaining existing vegetation whenever feasible  Establishing a quarry spall construction entrance  Installing siltation control fencing or anchored straw or coir wattles on the downhill side of work areas  Covering soil stockpiles with anchored plastic sheeting  Revegetating or mulching exposed soils with a minimum 3-inch thickness of straw if surfaces will be left undisturbed for more than one day during wet weather or one week in dry weather  Directing runoff away from exposed soils and slopes  Minimizing the length and steepness of slopes with exposed soils and cover excavation surfaces with anchored plastic sheeting  Decreasing runoff velocities with check dams, straw bales or coir wattles  Confining sediment to the project site  Inspecting and maintaining erosion and sediment control measures frequently (The contractor should be aware that inspection and maintenance of erosion control BMPs is critical toward their satisfactory performance. Repair and/or replacement of dysfunctional erosion control elements should be anticipated.) Permanent erosion protection should be provided by reestablishing vegetation using hydroseeding and/or landscape planting. Until the permanent erosion protection is established, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures. Provisions for modifications to the erosion Geotechnical Engineering Report 6 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 control system based on monitoring observations should be included in the erosion and sedimentation control plan. 5.2.2 STRIPPING AND SUBGRADE PREPARATION Stripping efforts should include removal of pavements, vegetation, organic materials, and deleterious debris from areas slated for building, pavement, and utility construction. The test pit explorations encountered 4 to 10 inches of topsoil and rootmass. Deeper areas of stripping may be required in forested or heavily vegetated areas of the site. Subgrade soils that become disturbed due to elevated moisture conditions should be overexcavated to reveal firm, non-yielding, non-organic soils and backfilled with compacted structural fill. In order to maximize utilization of site soils as structural fill, RGI recommends that the earthwork portion of this project be completed during extended periods of warm and dry weather if possible. If earthwork is completed during the wet season (typically November through May) it will be necessary to take extra precautionary measures to protect subgrade soils. Wet season earthwork will require additional mitigative measures beyond that which would be expected during the drier summer and fall months. 5.2.3 EXCAVATIONS All temporary cut slopes associated with the site and utility excavations should be adequately inclined to prevent sloughing and collapse. The site soils consist of medium dense silty sand with trace gravel and sand with some silt and gravel, and soft peat and stiff to very stiff silt with varying amounts of sand. Accordingly, for excavations more than 4 feet but less than 20 feet in depth, the temporary side slopes should be laid back with a minimum slope inclination of 1.5H:1V (Horizontal:Vertical). If there is insufficient room to complete the excavations in this manner, or excavations greater than 20 feet in depth are planned, using temporary shoring to support the excavations should be considered. For open cuts at the site, RGI recommends:  No traffic, construction equipment, stockpiles or building supplies are allowed at the top of cut slopes within a distance of at least five feet from the top of the cut  Exposed soil along the slope is protected from surface erosion using waterproof tarps and/or plastic sheeting  Construction activities are scheduled so that the length of time the temporary cut is left open is minimized  Surface water is diverted away from the excavation  The general condition of slopes should be observed periodically by a geotechnical engineer to confirm adequate stability and erosion control measures Geotechnical Engineering Report 7 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 In all cases, however, appropriate inclinations will depend on the actual soil and groundwater conditions encountered during earthwork. Ultimately, the site contractor must be responsible for maintaining safe excavation slopes that comply with applicable OSHA or WISHA guidelines. 5.2.4 STRUCTURAL FILL RGI recommends fill below the foundation and floor slab, behind retaining walls, and below pavement and hardscape surfaces be placed in accordance with the following recommendations for structural fill. The structural fill should be placed after completion of site preparation procedures as described above. The suitability of excavated site soils and import soils for compacted structural fill use will depend on the gradation and moisture content of the soil when it is placed. As the amount of fines (that portion passing the U.S. No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult or impossible to achieve. Soils containing more than about 5 percent fines cannot be consistently compacted to a dense, non-yielding condition when the moisture content is more than 2 percent above or below optimum. Optimum moisture content is that moisture that results in the greatest compacted dry density with a specified compactive effort. Non-organic site soils are only considered suitable for structural fill provided that their moisture content is within about two percent of the optimum moisture level as determined by American Society of Testing and Materials D1557-09 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (ASTM D1557). Excavated site soils may not be suitable for re-use as structural fill depending on the moisture content and weather conditions at the time of construction. If soils are stockpiled for future reuse and wet weather is anticipated, the stockpile should be protected with plastic sheeting that is securely anchored. Even during dry weather, moisture conditioning (such as, windrowing and drying) of site soils to be reused as structural fill may be required. The onsite soils contain organics and are not suitable for use as structural fill. It is necessary to import clean, granular soils to complete site work that meets the gradation requirements listed in Table 2 to be used as structural fill. Geotechnical Engineering Report 8 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 Table 2 Structural Fill Gradation U.S. Sieve Size Percent Passing 4 inches 100 No. 4 sieve 22 to 100 No. 200 sieve 0 to 5* *Based on minus 3/4 inch fraction. Prior to use, an RGI representative should observe and test all materials imported to the site for use as structural fill. Structural fill materials should be placed in uniform loose layers not exceeding 12 inches and compacted as specified in Table 3. The soil’s maximum density and optimum moisture should be determined by ASTM D1557. Table 3 Structural Fill Compaction ASTM D1557 Location Material Type Minimum Compaction Percentage Moisture Content Range Foundations On-site granular or approved imported fill soils: 95 +2 -2 Retaining Wall Backfill On-site granular or approved imported fill soils: 92 +2 -2 Slab-on-grade On-site granular or approved imported fill soils: 95 +2 -2 General Fill (non- structural areas) On-site soils or approved imported fill soils: 90 +3 -2 Placement and compaction of structural fill should be observed by RGI. A representative number of in-place density tests should be performed as the fill is being placed to confirm that the recommended level of compaction is achieved. 5.2.5 WET WEATHER CONSTRUCTION CONSIDERATIONS RGI recommends that preparation for site grading and construction include procedures intended to drain ponded water, control surface water runoff, and to collect shallow subsurface seepage zones in excavations where encountered. It will not be possible to successfully compact the subgrade or utilize on-site soils as structural fill if accumulated water is not drained prior to grading or if drainage is not controlled during construction. Attempting to grade the site without adequate drainage control measures will reduce the amount of on-site soil effectively available for use, increase the amount of select import fill materials required, and ultimately increase the cost of the earthwork phases of the project. Geotechnical Engineering Report 9 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 Free water should not be allowed to pond on the subgrade soils. RGI anticipates that the use of berms and shallow drainage ditches, with sumps and pumps in utility trenches, will be required for surface water control during wet weather and/or wet site conditions. 5.3 FOUNDATIONS As described above, peat should be removed below the building pad area and backfilled with structural fill. Based on our test exploration, the depth of peat is about 4.5 feet in the building area. After the peat is removed, the building foundation can be supported on spread footing foundation bearing on structural fill. Perimeter foundations exposed to weather should be at a minimum depth of 18 inches below final exterior grades. Interior foundations can be constructed at any convenient depth below the floor slab. Finished grade is defined as the lowest adjacent grade within 5 feet of the foundation for perimeter (or exterior) footings and finished floor level for interior footings. Table 4 Foundation Design Design Parameter Value Allowable Bearing Capacity – Structural Fill 2,500 psf1 Friction Coefficient 0.30 Passive pressure (equivalent fluid pressure) 250 pcf2 Minimum foundation dimensions Columns: 24 inches Walls: 16 inches 1. psf = pounds per square foot 2. pcf = pounds per cubic foot The allowable foundation bearing pressures apply to dead loads plus design live load conditions. For short-term loads, such as wind and seismic, a 1/3 increase in this allowable capacity may be used. At perimeter locations, RGI recommends not including the upper 12 inches of soil in the computation of passive pressures because they can be affected by weather or disturbed by future grading activity. The passive pressure value assumes the foundation will be constructed neat against competent soil or backfilled with structural fill as described in Section 5.2.4. The recommended base friction and passive resistance value includes a safety factor of about 1.5. With spread footing foundations designed in accordance with the recommendations in this section, maximum total and differential post-construction settlements of 1 inch and 1/2 inch, respectively, should be expected. Geotechnical Engineering Report 10 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 5.4 RETAINING WALLS If retaining walls are needed in the building area, RGI recommends cast-in-place concrete walls be used. The retaining wall must be supported on structural fill after peat is completely removed. The magnitude of earth pressure development on retaining walls will partly depend on the quality of the wall backfill. RGI recommends placing and compacting wall backfill as structural fill. Wall drainage will be needed behind the wall face. A typical retaining wall drainage detail is shown in Figure 3. With wall backfill placed and compacted as recommended, and drainage properly installed, RGI recommends using the values in the following table for design. Table 5 Retaining Wall Design Design Parameter Value Allowable Bearing Capacity – Structural Fill 2,500 psf Active Earth Pressure (unrestrained walls) 35 pcf At-rest Earth Pressure (restrained walls) 50 pcf For seismic design, an additional uniform load of 7 times the wall height (H) for unrestrained walls and 14H in psf for restrained walls should be applied to the wall surface. Friction at the base of foundations and passive earth pressure will provide resistance to these lateral loads. Values for these parameters are provided in Section 5.3. 5.5 SLAB-ON-GRADE CONSTRUCTION As described above, the peat should be completely removed in the building pad area and backfilled with structural fill. Once site preparation has been completed as described in Section 5.2, suitable support for slab-on-grade construction should be provided. RGI recommends that the concrete slab be placed on top of structural fill. Immediately below the floor slab, RGI recommends placing a four-inch thick capillary break layer of clean, free- draining sand or gravel that has less than five percent passing the U.S. No. 200 sieve. This material will reduce the potential for upward capillary movement of water through the underlying soil and subsequent wetting of the floor slab. Where moisture by vapor transmission is undesirable, an 8- to 10-millimeter thick plastic membrane should be placed on a 4-inch thick layer of clean gravel. For the anticipated floor slab loading, we estimate post-construction floor settlements of 1/4- to 1/2-inch. Geotechnical Engineering Report 11 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 5.6 DRAINAGE 5.6.1 SURFACE Final exterior grades should promote free and positive drainage away from the building area. Water must not be allowed to pond or collect adjacent to foundations or within the immediate building area. For non-pavement locations, RGI recommends providing a minimum drainage gradient of 3 percent for a minimum distance of 10 feet from the building perimeter. In paved locations, a minimum gradient of 1 percent should be provided unless provisions are included for collection and disposal of surface water adjacent to the structure. 5.6.2 SUBSURFACE RGI recommends installing perimeter foundation drains. A typical footing drain detail is shown on Figure 4. The foundation drains and roof downspouts should be tightlined separately to an approved discharge facility. Subsurface drains must be laid with a gradient sufficient to promote positive flow to a controlled point of approved discharge. 5.6.3 INFILTRATION The native site soils are not suitable for infiltration due to low permeability and shallow ground water level. The stormwater should be routed to the storm drainage system in the right-of-way. 5.7 UTILITIES Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) specifications. For site utilities located within the right-of-ways, bedding and backfill should be completed in accordance with City of Federal Way specifications. At a minimum, trench backfill should be placed and compacted as structural fill, as described in Section 5.2.4. Where utilities occur below unimproved areas, the degree of compaction can be reduced to a minimum of 90 percent of the soil’s maximum density as determined by the referenced ASTM D1557. The onsite soil is not suitable for use as backfill material. Imported structural fill meeting the gradation provided in Table 2 may be necessary for trench backfill. Since the site contains peat that has a potential of settlements, all utilities pipes should use flexible joints for connections to structures. 5.8 PAVEMENTS As described above, peat below the site will cause long term settlement. To avoid settlement, all peat below the site should be removed and backfilled with structural fill. Based on test exploration in the proposed parking area, the excavation depth will be from Geotechnical Engineering Report 12 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 7 to 9 feet in order to remove all the peat. If the amount of overexcavation is too much, the pavement can be supported on existing fill. However, long-term settlement on an order of several inches will be expected. If it is acceptable to the client, the pavement can be supported on existing fill. Pavement subgrades should be prepared as described in Section 5.2 and as discussed below. Regardless of the relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. The subgrade should be proof-rolled with heavy construction equipment to verify this condition. RGI recommends the following pavement sections for parking and drive areas paved with flexible asphalt concrete surfacing.  3 inches of Hot Mix Asphalt (HMA) over 6 inches of crushed rock base (CRB) over existing fill after recompaction The paving materials used should conform to the WSDOT specifications for HMA, and CRB surfacing (9-03.9(3) Crushed Surfacing). Long-term pavement performance will depend on surface drainage. A poorly-drained pavement section will be subject to premature failure as a result of surface water infiltrating into the subgrade soils and reducing their supporting capability. For optimum pavement performance, surface drainage gradients of no less than 2 percent are recommended. Also, some degree of longitudinal and transverse cracking of the pavement surface should be expected over time. Regular maintenance should be planned to seal cracks when they occur. 6.0 Additional Services RGI is available to provide further geotechnical consultation throughout the design phase of the project. RGI should review the final design and specifications in order to verify that earthwork and foundation recommendations have been properly interpreted and incorporated into project design and construction. RGI is also available to provide geotechnical engineering and construction monitoring services during construction. The integrity of the earthwork and construction depends on proper site preparation and procedures. In addition, engineering decisions may arise in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this scope of work. If these services are desired, please let us know and we will prepare a cost proposal. 7.0 Limitations This GER is the property of RGI, Magellan Architects, and its designated agents. Within the limits of the scope and budget, this GER was prepared in accordance with generally Geotechnical Engineering Report 13 November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 accepted geotechnical engineering practices in the area at the time this GER was issued. This GER is intended for specific application to the Midway Samoan AG Church project in Federal Way, Washington, and for the exclusive use of Magellan Architects and its authorized representatives. No other warranty, expressed or implied, is made. Site safety, excavation support, and dewatering requirements are the responsibility of others. The scope of services for this project does not include either specifically or by implication any environmental or biological (for example, mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, we can provide a proposal for these services. The analyses and recommendations presented in this GER are based upon data obtained from the explorations performed on site. Variations in soil conditions can occur, the nature and extent of which may not become evident until construction. If variations appear evident, RGI should be requested to reevaluate the recommendations in this GER prior to proceeding with construction. It is the client’s responsibility to see that all parties to the project, including the designers, contractors, subcontractors, are made aware of this GER in its entirety. The use of information contained in this GER for bidding purposes should be done at the contractor’s option and risk. USGS, 2014, Poverty Bay, Washington 7.5-Minute Quadrangle Approximate Scale: 1"=1000' 0 500 1000 2000 N Site Vicinity Map Figure 1 11/2020 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Midway Samoan AG Church (20-046) RGI Project Number: 2020-507-1 Date Drawn: Address: 29276 Military Road South, Federal Way, Washington 98003 SITE TP-1TP-2TP-3TP-4TP-5TP-6TP-7TP-811/2020Corporate Office17522 Bothell Way NortheastBothell, Washington 98011Phone: 425.415.0551Fax: 425.415.0311Midway Samoan AG Church (20-046)RGI Project Number:2020-507-1Date Drawn:Address: 29276 Military Road South, Federal Way, Washington 98003Figure 2Approximate Scale: 1"=80'04080160N= Test pit by RGI, 10/28/20= Site boundaryGeotechnical Exploration Plan Incliniations) 12" Over the Pipe 3" Below the Pipe Perforated Pipe 4" Diameter PVC Compacted Structural Backfill (Native or Import) 12" min. Filter Fabric Material 12" Minimum Wide Free-Draining Gravel Slope to Drain (See Report for Appropriate Excavated Slope 11/2020 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Midway Samoan AG Church (20-046) RGI Project Number: 2020-507-1 Date Drawn: Address: 29276 Military Road South, Federal Way, Washington 98003 Retaining Wall Drainage Detail Figure 3 Not to Scale 3/4" Washed Rock or Pea Gravel 4" Perforated Pipe Building Slab Structural Backfill Compacted Filter Fabric 11/2020 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Midway Samoan AG Church (20-046) RGI Project Number: 2020-507-1 Date Drawn: Address: 29276 Military Road South, Federal Way, Washington 98003 Typical Footing Drain Detail Figure 4 Not to Scale Geotechnical Engineering Report November 13, 2020 Midway Samoan AG Church, Federal Way, Washington RGI Project No. 2020-507-1 APPENDIX A FIELD EXPLORATION AND LABORATORY TESTING On October 28, 2020, RGI performed field explorations using a backhoe. We explored subsurface soil conditions at the site by observing the excavation of eight test pit explorations to a maximum depth of 10 feet below existing grade. The test pit locations are shown on Figure 2. The test pit locations were approximately determined by measurements from existing property lines and paved roads. A geologist from our office conducted the field exploration and classified the soil conditions encountered, maintained a log of each test exploration, obtained representative soil samples, and observed pertinent site features. All soil samples were visually classified in accordance with the Unified Soil Classification System (USCS). Representative soil samples obtained from the explorations were placed in closed containers and taken to our laboratory for further examination and testing. As a part of the laboratory testing program, the soil samples were classified in our in house laboratory based on visual observation, texture, plasticity, and the limited laboratory testing described below. Moisture Content Determinations Moisture content determinations were performed in accordance with ASTM D2216-10 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass (ASTM D2216) on representative samples obtained from the exploration in order to aid in identification and correlation of soil types. The moisture content of typical sample was measured and is reported on the test pit logs. Grain Size Analysis A grain size analysis indicates the range in diameter of soil particles included in a particular sample. Grain size analyses was determined using D6913-04(2009) Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis (ASTM D6913) on four of the samples. Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Test Pit No.: TP-1 Date(s) Excavated:10/28/2020 Excavation Method:Test Pit Excavator Type:Rubber Tired Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Kelly's Excavating Sampling Method(s)Grab Location 29276 Military Road South, Federal Way, Washington Surface Conditions:Grass Total Depth of Excavation:10 feet bgs Approximate Surface Elevation N/A Compaction Method Bucket USCS SymbolTPSL Fill Fill ML ML SP-SM REMARKS AND OTHER TESTS 29% moisture 19% moisture 19% moisture 6% moistureGraphic LogMATERIAL DESCRIPTION 4" topsoil Brown sandy GRAVEL, dense, moist (Fill) Contains quarry spalls Brown silty SAND with some gravel, medium dense, moist (Fill) Tan mottled SILT with some sand, stiff, moist Becomes gray, very stiff Becomes hard Gray sandy SILT, very stiff, moist to wet Contains sand interbeds Gray SAND with some silt and gravel, medium dense, moist Test Pit terminated at 10'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Test Pit No.: TP-2 Date(s) Excavated:10/28/2020 Excavation Method:Test Pit Excavator Type:Rubber Tired Backhoe Groundwater Level:Seepage at 8' Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Kelly's Excavating Sampling Method(s)Grab Location 29276 Military Road South, Federal Way, Washington Surface Conditions:Grass Total Depth of Excavation:8.5 feet bgs Approximate Surface Elevation N/A Compaction Method Bucket USCS SymbolTPSL ML ML SM SP-SM REMARKS AND OTHER TESTS 27% moisture 14% moisture, 22% fines 22% moistureGraphic LogMATERIAL DESCRIPTION 10" topsoil Gray SILT with trace sand and gravel, very stiff, moist Gray sandy SILT, very stiff, moist Gray silty SAND with trace gravel, medium dense, moist Heavy iron oxide staining Occasional cobble Gray SAND with some silt and gravel, medium dense, moist Becomes wet, light groundwater seepage Test Pit terminated at 8.5'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Test Pit No.: TP-3 Date(s) Excavated:10/28/2020 Excavation Method:Test Pit Excavator Type:Rubber Tired Backhoe Groundwater Level:5' Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Kelly's Excavating Sampling Method(s)Grab Location 29276 Military Road South, Federal Way, Washington Surface Conditions:Gravel Total Depth of Excavation:7.5 feet bgs Approximate Surface Elevation N/A Compaction Method Bucket USCS SymbolFill Fill Peat SM REMARKS AND OTHER TESTS 17% moisture 94% moisture 585% moisture 26% moistureGraphic LogMATERIAL DESCRIPTION 8" gray 5/8" minus crushed rock, dense, moist (Fill) Brown silty SAND with some gravel, medium dense, moist (Fill) Black PEAT, soft, moist Becomes brown, wet Becomes saturated Gray silty SAND with trace gravel, medium dense, wet Test Pit terminated at 7.5'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Test Pit No.: TP-4 Date(s) Excavated:10/28/2020 Excavation Method:Test Pit Excavator Type:Rubber Tired Backhoe Groundwater Level:4.5' Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Kelly's Excavating Sampling Method(s)Grab Location 29276 Military Road South, Federal Way, Washington Surface Conditions:Grass Total Depth of Excavation:9 feet bgs Approximate Surface Elevation N/A Compaction Method Bucket USCS SymbolTPSL Fill Peat ML REMARKS AND OTHER TESTS 765% moisture 25% moistureGraphic LogMATERIAL DESCRIPTION 6" topsoil Brown silty gravelly SAND, medium dense, moist (Fill) Contains concrete debris Black PEAT, soft, wet Becomes brown Becomes saturated Gray SILT with some sand, stiff, moist to wet Trace organics Test Pit terminated at 9'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Test Pit No.: TP-5 Date(s) Excavated:10/28/2020 Excavation Method:Test Pit Excavator Type:Rubber Tired Backhoe Groundwater Level:6' Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Kelly's Excavating Sampling Method(s)Grab Location 29276 Military Road South, Federal Way, Washington Surface Conditions:Grass Total Depth of Excavation:8 feet bgs Approximate Surface Elevation N/A Compaction Method Bucket USCS SymbolTPSL Fill Peat SM REMARKS AND OTHER TESTS 20% moisture, 18% finesGraphic LogMATERIAL DESCRIPTION 4" topsoil Gray silty gravelly SAND, medium dense, moist (Fill) Contains concrete and asphalt debris Black PEAT, soft, wet Heavy seepage Gray silty fine SAND, medium dense, water bearing Test Pit terminated at 8'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Test Pit No.: TP-6 Date(s) Excavated:10/28/2020 Excavation Method:Test Pit Excavator Type:Rubber Tired Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Kelly's Excavating Sampling Method(s)Grab Location 29276 Military Road South, Federal Way, Washington Surface Conditions:Grass Total Depth of Excavation:9.5 feet bgs Approximate Surface Elevation N/A Compaction Method Bucket USCS SymbolTPSL Fill Peat ML REMARKS AND OTHER TESTS 5% moisture, 12% fines 49% moisture 14% moistureGraphic LogMATERIAL DESCRIPTION 5" topsoil Gray GRAVEL with some sand, medium dense, moist (Fill) Trace concrete debris Brown to gray Black PEAT with wood debris, soft, wet Becomes brown Gray sandy SILT with trace gravel, very stiff, moist Test Pit terminated at 9.5'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Test Pit No.: TP-7 Date(s) Excavated:10/28/2020 Excavation Method:Test Pit Excavator Type:Rubber Tired Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Kelly's Excavating Sampling Method(s)Grab Location 29276 Military Road South, Federal Way, Washington Surface Conditions:Gravel Total Depth of Excavation:6.5 feet bgs Approximate Surface Elevation N/A Compaction Method Bucket USCS SymbolFill Fill Peat ML REMARKS AND OTHER TESTS 30% moisture 23% moisture, 87% finesGraphic LogMATERIAL DESCRIPTION 4" 5/8" minus crushed rock, dense, moist (Fill) Brown silty gravelly SAND, medium dense, moist (Fill) Trace metal debris Large boulder Black PEAT, soft, wet Gray SILT with trace sand, stiff, moist Test Pit terminated at 6.5'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Test Pit No.: TP-8 Date(s) Excavated:10/28/2020 Excavation Method:Test Pit Excavator Type:Rubber Tired Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Kelly's Excavating Sampling Method(s)Grab Location 29276 Military Road South, Federal Way, Washington Surface Conditions:Grass Total Depth of Excavation:6 feet bgs Approximate Surface Elevation N/A Compaction Method Bucket USCS SymbolFill Fill Peat ML REMARKS AND OTHER TESTS 362% moisture 21% moistureGraphic LogMATERIAL DESCRIPTION 2" 5/8" minus crushed rock, dense, moist Brown silty SAND with some gravel, medium dense, moist (Fill) Black PEAT, soft, moist to wet Becomes brown Gray SILT with some sand and gravel, very stiff, moist Test Pit terminated at 6'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Midway Samoan AG Church Project Number:2020-507-1 Client:Magellan Architects Key to Logs USCS SymbolREMARKS AND OTHER TESTSGraphic LogMATERIAL DESCRIPTIONDepth (feet)Sample NumberSample TypeElevation (feet)1 2 3 4 5 6 7 8 COLUMN DESCRIPTIONS 1 Elevation (feet): Elevation (MSL, feet). 2 Depth (feet): Depth in feet below the ground surface. 3 Sample Type: Type of soil sample collected at the depth interval shown. 4 Sample Number: Sample identification number. 5 USCS Symbol: USCS symbol of the subsurface material. 6 Graphic Log: Graphic depiction of the subsurface material encountered. 7 MATERIAL DESCRIPTION: Description of material encountered. May include consistency, moisture, color, and other descriptive text. 8 REMARKS AND OTHER TESTS: Comments and observations regarding drilling or sampling made by driller or field personnel. FIELD AND LABORATORY TEST ABBREVIATIONS CHEM: Chemical tests to assess corrosivity COMP: Compaction test CONS: One-dimensional consolidation test LL: Liquid Limit, percent PI: Plasticity Index, percent SA: Sieve analysis (percent passing No. 200 Sieve) UC: Unconfined compressive strength test, Qu, in ksf WA: Wash sieve (percent passing No. 200 Sieve) MATERIAL GRAPHIC SYMBOLS AF SILT, SILT w/SAND, SANDY SILT (ML) Peat Silty SAND (SM) Poorly graded SAND with Silt (SP-SM) Topsoil TYPICAL SAMPLER GRAPHIC SYMBOLS Auger sampler Bulk Sample 3-inch-OD California w/ brass rings CME Sampler Grab Sample 2.5-inch-OD Modified California w/ brass liners Pitcher Sample 2-inch-OD unlined split spoon (SPT) Shelby Tube (Thin-walled, fixed head) OTHER GRAPHIC SYMBOLS Water level (at time of drilling, ATD) Water level (after waiting) Minor change in material properties within a stratum Inferred/gradational contact between strata ?Queried contact between strata GENERAL NOTES 1: Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive, and actual lithologic changes may be gradual. Field descriptions may have been modified to reflect results of lab tests. 2: Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They are not warranted to be representative of subsurface conditions at other locations or times. Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 THE RILEY GROUP, INC. 17522 Bothell Way NE Bothell, WA 98011 PHONE: (425) 415-0551 FAX: (425) 415-0311 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Midway Samoan AG Church SAMPLE ID/TYPE TP-2 PROJECT NO.2020-507-1 SAMPLE DEPTH 4' TECH/TEST DATE EW 10/29/2020 DATE RECEIVED 10/28/2020 WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture Wt Wet Soil & Tare (gm) (w1)285.6 Weight Of Sample (gm)252.0 Wt Dry Soil & Tare (gm) (w2)252.0 Tare Weight (gm) 16.1 Weight of Tare (gm) (w3)16.1 (W6) Total Dry Weight (gm) 235.9 Weight of Water (gm) (w4=w1-w2) 33.6 SIEVE ANALYSIS Weight of Dry Soil (gm) (w5=w2-w3) 235.9 Cumulative Moisture Content (%) (w4/w5)*100 14 Wt Ret (Wt-Tare) (%Retained)% PASS +Tare {(wt ret/w6)*100}(100-%ret) % COBBLES 0.0 12.0"16.1 0.00 0.00 100.00 cobbles % C GRAVEL 0.0 3.0"16.1 0.00 0.00 100.00 coarse gravel % F GRAVEL 11.2 2.5" coarse gravel % C SAND 4.8 2.0" coarse gravel % M SAND 16.6 1.5"16.1 0.00 0.00 100.00 coarse gravel % F SAND 45.0 1.0" coarse gravel % FINES 22.4 0.75"16.1 0.00 0.00 100.00 fine gravel % TOTAL 100.0 0.50" fine gravel 0.375"34.9 18.80 7.97 92.03 fine gravel D10 (mm)#4 42.6 26.50 11.23 88.77 coarse sand D30 (mm)#10 54.0 37.90 16.07 83.93 medium sand D60 (mm)#20 medium sand Cu #40 93.1 77.00 32.64 67.36 fine sand Cc #60 fine sand #100 179.4 163.30 69.22 30.78 fine sand #200 199.2 183.10 77.62 22.38 fines PAN 252.0 235.90 100.00 0.00 silt/clay DESCRIPTION Silty SAND with trace gravel USCS SM Prepared For:Reviewed By: Magellon Architechts RW 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 % P A S S I N G Grain size in millimeters 12"3" 2" 1".75" .375" #4 #10 #20 #40 #60 #100 #200 THE RILEY GROUP, INC. 17522 Bothell Way NE Bothell, WA 98011 PHONE: (425) 415-0551 FAX: (425) 415-0311 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Midway Samoan AG Church SAMPLE ID/TYPE TP-5 PROJECT NO.2020-507-1 SAMPLE DEPTH 7' TECH/TEST DATE EW 10/29/2020 DATE RECEIVED 10/28/2020 WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture Wt Wet Soil & Tare (gm) (w1)449.1 Weight Of Sample (gm)375.7 Wt Dry Soil & Tare (gm) (w2)375.7 Tare Weight (gm) 16.1 Weight of Tare (gm) (w3)16.1 (W6) Total Dry Weight (gm) 359.6 Weight of Water (gm) (w4=w1-w2) 73.4 SIEVE ANALYSIS Weight of Dry Soil (gm) (w5=w2-w3) 359.6 Cumulative Moisture Content (%) (w4/w5)*100 20 Wt Ret (Wt-Tare) (%Retained)% PASS +Tare {(wt ret/w6)*100}(100-%ret) % COBBLES 0.0 12.0"16.1 0.00 0.00 100.00 cobbles % C GRAVEL 0.0 3.0"16.1 0.00 0.00 100.00 coarse gravel % F GRAVEL 0.0 2.5" coarse gravel % C SAND 0.0 2.0" coarse gravel % M SAND 0.8 1.5"16.1 0.00 0.00 100.00 coarse gravel % F SAND 81.1 1.0" coarse gravel % FINES 18.1 0.75"16.1 0.00 0.00 100.00 fine gravel % TOTAL 100.0 0.50" fine gravel 0.375"16.1 0.00 0.00 100.00 fine gravel D10 (mm)#4 16.1 0.00 0.00 100.00 coarse sand D30 (mm)#10 16.1 0.00 0.00 100.00 medium sand D60 (mm)#20 medium sand Cu #40 18.9 2.80 0.78 99.22 fine sand Cc #60 fine sand #100 238.5 222.40 61.85 38.15 fine sand #200 310.5 294.40 81.87 18.13 fines PAN 375.7 359.60 100.00 0.00 silt/clay DESCRIPTION Silty fine SAND USCS SM Prepared For:Reviewed By: Magellon Architechts RW 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 % P A S S I N G Grain size in millimeters 12"3" 2" 1".75" .375" #4 #10 #20 #40 #60 #100 #200 THE RILEY GROUP, INC. 17522 Bothell Way NE Bothell, WA 98011 PHONE: (425) 415-0551 FAX: (425) 415-0311 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Midway Samoan AG Church SAMPLE ID/TYPE TP-6 PROJECT NO.2020-507-1 SAMPLE DEPTH 1.5' TECH/TEST DATE EW 10/29/2020 DATE RECEIVED 10/28/2020 WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture Wt Wet Soil & Tare (gm) (w1)466.1 Weight Of Sample (gm)444.8 Wt Dry Soil & Tare (gm) (w2)444.8 Tare Weight (gm) 16.1 Weight of Tare (gm) (w3)16.1 (W6) Total Dry Weight (gm) 428.7 Weight of Water (gm) (w4=w1-w2) 21.3 SIEVE ANALYSIS Weight of Dry Soil (gm) (w5=w2-w3) 428.7 Cumulative Moisture Content (%) (w4/w5)*100 5 Wt Ret (Wt-Tare) (%Retained)% PASS +Tare {(wt ret/w6)*100}(100-%ret) % COBBLES 0.0 12.0"16.1 0.00 0.00 100.00 cobbles % C GRAVEL 39.9 3.0"16.1 0.00 0.00 100.00 coarse gravel % F GRAVEL 23.7 2.5" coarse gravel % C SAND 5.2 2.0" coarse gravel % M SAND 8.2 1.5"16.1 0.00 0.00 100.00 coarse gravel % F SAND 10.6 1.0" coarse gravel % FINES 12.3 0.75"187.1 171.00 39.89 60.11 fine gravel % TOTAL 100.0 0.50" fine gravel 0.375"255.1 239.00 55.75 44.25 fine gravel D10 (mm)#4 288.9 272.80 63.63 36.37 coarse sand D30 (mm)#10 311.3 295.20 68.86 31.14 medium sand D60 (mm)#20 medium sand Cu #40 346.6 330.50 77.09 22.91 fine sand Cc #60 fine sand #100 380.4 364.30 84.98 15.02 fine sand #200 392.2 376.10 87.73 12.27 fines PAN 444.8 428.70 100.00 0.00 silt/clay DESCRIPTION Silty GRAVEL with some sand USCS GM Prepared For:Reviewed By: Magellon Architechts RW 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 % P A S S I N G Grain size in millimeters 12"3" 2" 1".75" .375" #4 #10 #20 #40 #60 #100 #200 THE RILEY GROUP, INC. 17522 Bothell Way NE Bothell, WA 98011 PHONE: (425) 415-0551 FAX: (425) 415-0311 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Midway Samoan AG Church SAMPLE ID/TYPE TP-7 PROJECT NO.2020-507-1 SAMPLE DEPTH 6' TECH/TEST DATE EW 10/29/2020 DATE RECEIVED 10/28/2020 WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture Wt Wet Soil & Tare (gm) (w1)234.3 Weight Of Sample (gm)193.7 Wt Dry Soil & Tare (gm) (w2)193.7 Tare Weight (gm) 16.2 Weight of Tare (gm) (w3)16.2 (W6) Total Dry Weight (gm) 177.5 Weight of Water (gm) (w4=w1-w2) 40.6 SIEVE ANALYSIS Weight of Dry Soil (gm) (w5=w2-w3) 177.5 Cumulative Moisture Content (%) (w4/w5)*100 23 Wt Ret (Wt-Tare) (%Retained)% PASS +Tare {(wt ret/w6)*100}(100-%ret) % COBBLES 0.0 12.0"16.2 0.00 0.00 100.00 cobbles % C GRAVEL 0.0 3.0"16.2 0.00 0.00 100.00 coarse gravel % F GRAVEL 0.0 2.5" coarse gravel % C SAND 0.2 2.0" coarse gravel % M SAND 1.5 1.5"16.2 0.00 0.00 100.00 coarse gravel % F SAND 11.5 1.0" coarse gravel % FINES 86.8 0.75"16.2 0.00 0.00 100.00 fine gravel % TOTAL 100.0 0.50" fine gravel 0.375"16.2 0.00 0.00 100.00 fine gravel D10 (mm)#4 16.2 0.00 0.00 100.00 coarse sand D30 (mm)#10 16.6 0.40 0.23 99.77 medium sand D60 (mm)#20 medium sand Cu #40 19.2 3.00 1.69 98.31 fine sand Cc #60 fine sand #100 30.1 13.90 7.83 92.17 fine sand #200 39.6 23.40 13.18 86.82 fines PAN 193.7 177.50 100.00 0.00 silt/clay DESCRIPTION SILT with trace sand USCS ML Prepared For:Reviewed By: Magellon Architechts RW 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 % P A S S I N G Grain size in millimeters 12"3" 2" 1".75" .375" #4 #10 #20 #40 #60 #100 #200