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20-102489-TIR-2020-06-04-V1
PRELIMINARY TECHNICAL INFORMATION REPORT Papé Kenworth NW – Federal Way NE Corner of I-5 and South 320th Street Federal Way, WA 98003 Prepared for: Papé Properties 355 Goodpasture Island Road Eugene, OR 97401 March 6, 2020 Revised June 4, 2020 Our Job No. 20833 06/04/2020 1.0 PROJECT OVERVIEW 20833.001.doc 1.0 PROJECT OVERVIEW This project is located on a 19.9-acre site within a portion of the Southeast quarter of the Southeast quarter of Section 9, Township 21 North, Range 4 East, Willamette Meridian, City of Federal Way, King County, Washington. More particularly, the site is located at the NE corner of I-5 and South 320th Street, Federal Way, WA 98003, on King County tax parcels 092104-9028, 092104-9139, 092104-9316, 092104-9187, 092104-9140, 092104-9160, and 092104-9206. As a part of this project, a boundary line adjustment and right of way dedication will establish a new lot line. The parcels are currently within unincorporated King County, and is being reviewed by the City of Federal way as if the property has been annexed into Federal Way and zoned Community Business (BC). The existing site is mainly moderate to steep slopes and partially forested. There are two existing transmission towers located on the site, and existing easements with AFN. 5746718, 3139642, 3288633, 4963340, 4972634, & 4972636. These easements run in a NE/SW fashion across the site and total 290-ft in width. There are existing homes and gravel access roads across the various parcels. The west side of the site contains a wetland area that will be protected by appropriate buffers. Of the 19.9 acres, approximately 13.8 acres are buildable due to an existing wetland and buffer. After the necessary ROW dedication, the buildable site is approximately 13 acres in size. The existing easements further encumber 4.15 acres of the site. The proposed development includes a 1.3 acre building, a 0.32 acre building, associated concrete truck docks, asphalt paved parking lot, and vegetation/landscaping. There will also be frontage improvements along S 320th Street and 32nd Avenue South totaling an additional ±1.9 acres. The developed site will be contained within a single basin with approximate area of 13.2 acres, tributary to the onsite wetland. The developed site will contain approximately 90% impervious surface area. Site drainage design is based on the 2016 King County Surface Water Design Manual (KCSWDM), as adopted and amended by the City of Federal Way. The site is within a Conservation Flow Control area and must comply with Level 2 Flow Control. A detention pond is designed to provide flow control for approximately half the site. An infiltration facility is designed to provide full infiltration for the remaining site area. Flow Control BMP requirements for the site are met by providing infiltration. The proposed site use is considered commercial, high-use. Enhanced basic water quality and oil treatment are required for stormwater runoff from pollution generating surfaces. Treatment of stormwater from the pond is proposed using an oil-water separator in addition to a Modular Wetland System, which has general use level designation (GULD) for enhanced treatment per the Department of Ecology (DOE), or equivalent system. Stormwater tributary to the infiltration system will be treated by an oil-water separator and a cartridge filter prior to entering the infiltration facility. The native soils below the site will provide additional filtration benefits, as demonstrated in the Geotechnical Report. The wetland will be protected from sediment laden runoff during the construction process and will not receive any runoff from pollution generating surfaces under the finished condition of the site. The infiltration gallery and detention pond have been sized to take all runoff from the roof, pavement, and the portion of landscaping that drains to the proposed stormwater facilities up to the 100-year storm event. The runoff from paved areas will be treated by water quality facilities, while roof runoff will go directly to the gallery or pond without treatment, as building roof area is a considered non-pollution generating surface. Infiltration facility requirements set forth in KCSWDM Section 5.2.1 have been met by the proposed facility including groundwater protection, consideration of groundwater level impacts, and requirements for infiltration near a water supply well. FIGURE 1 TECHNICAL INFORMATION REPORT (TIR) WORKSHEET KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner ___________________________ Phone _________________________________ Address _______________________________ _______________________________________ Project Engineer _________________________ Company ______________________________ Phone _________________________________ Project Name _________________________ DPER Permit # ________________________ Location Township ______________ Range ________________ Section ________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Landuse (e.g.,Subdivision / Short Subd. / UPD) Building (e.g.,M/F / Commercial / SFR) Clearing and Grading Right-of-Way Use Other _______________________ DFW HPA COE 404 DOE Dam Safety FEMA Floodplain COE Wetlands Other ________ Shoreline Management Structural Rockery/Vault/_____ ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review (check one): Date (include revision dates): Date of Final: Full Targeted Simplified Large Project Directed __________________ __________________ __________________ Plan Type (check one): Date (include revision dates): Date of Final: Full Modified Simplified __________________ __________________ __________________ Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Experimental / Blanket Description: (include conditions in TIR Section 2) ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ Approved Adjustment No. ______________________ Date of Approval: ______________________ 2016 Surface Water Design Manual 4/24/2016 1 Papé Properties Papé Kenworth NW-Federal Way 355 Goodpasture Island Road 21 N Eugene, OR 97401 04 E Benjamin Eldridge, PE SE 1/4 of SEC 9 Barghausen Consulting Engineers NE Corner of I-5 and S 320th St 425-251-6222 Federal Way, WA 98003 3/6/20203/6/2020, 6/4/2020 N/A 4 4 4 4 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ Re: KCSWDM Adjustment No. ________________ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan : ____________________________________________________________________ Special District Overlays: ______________________________________________________________ Drainage Basin: _____________________________________________________________________ Stormwater Requirements: ____________________________________________________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/Stream ________________________ Lake ______________________________ Wetlands ____________________________ Closed Depression ____________________ Floodplain ___________________________ Other _______________________________ _______________________________ Steep Slope __________________________ Erosion Hazard _______________________ Landslide Hazard ______________________ Coal Mine Hazard ______________________ Seismic Hazard _______________________ Habitat Protection ______________________ _____________________________________ Part 10 SOILS Soil Type _________________ _________________ _________________ _________________ Slopes _________________ _________________ _________________ _________________ Erosion Potential _________________ _________________ _________________ _________________ High Groundwater Table (within 5 feet) Other ________________________________ Sole Source Aquifer Seeps/Springs Additional Sheets Attached 2016 Surface Water Design Manual 4/24/2016 2 N/A N/A Hylebos Creek Level 2 flow control, ehanced basic water quality West side of site West side of site West side of site West side of site AgC 8-15% AgD 15-30% Sk - Seattle Muck W - Water 4 4 4 4 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core 2 – Offsite Analysis_________________ Sensitive/Critical Areas__________________ SEPA________________________________ LID Infeasibility________________________ Other________________________________ _____________________________________ LIMITATION / SITE CONSTRAINT _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Core Requirements (all 8 apply): Discharge at Natural Location Number of Natural Discharge Locations: Offsite Analysis Level: 1 / 2 / 3 dated:__________________ Flow Control (include facility summary sheet) Level: 1 / 2 / 3 or Exemption Number ____________ Flow Control BMPs _______________________________ Conveyance System Spill containment located at: _________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: _____________________ Contact Phone: _________________________ After Hours Phone: _________________________ Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality (include facility summary sheet) Type (circle one): 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 (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): ______________ Datum: Flood Protection Facilities Describe: 2016 Surface Water Design Manual 4/24/2016 3 Enhanced water quality providedAdjacent Wetlands Infiltration Trenches Oil-water separators Site (13.23 acres) N/A 4 4 4 2 To be provided at final KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Source Control (comm ercial / industrial land use) Describe land use: Describe any structural controls: Oil Control High-use Site: Yes / No Treatment BMP: ________________________________ Maintenance Agreement: Yes / No with whom? ____________________________________ Other Drainage Structures Describe: 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 Protection of Flow Control BMP Facilities (existing and proposed) Maintain BMPs / Manage Project 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, restore operation of Flow Control BMP Facilities as necessary 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 ________________ ________________ ________________ ________________ ________________ ________________ Vegetated Flowpath Wetpool Filtration Oil Control Spill Control Flow Control BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ ________________ 2016 Surface Water Design Manual 4/24/2016 4 Oil-water separator vault Pond Two gravel trenches Oil-water separator oil-water vault Infiltration trenches Modular Wetland 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Covenant Tract Other ___________________________ Cast in Place Vault Retaining Wall Rockery > 4’ High Structural on Steep Slope Other ______________________________ Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. Signed/Date 2016 Surface Water Design Manual 4/24/2016 5 4 6/4/2020 06/04/2020 FIGURE 2 SITE LOCATION Horizontal: Scale: Vertical: For: Title: VICINITY MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 vmap.cdr REFERENCE: Rand McNally (2020) SITE FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS FIGURE 4 SOILS MAP Horizontal: Scale: Vertical: For: Title: SOIL SURVEY MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 soil.cdr HSG B B B/D - REFERENCE: USDA, Natural Resources Conservation Service LEGEND: AgC = Alderwood gravelly sandy loam, 8-15% slopes SITE AgD = Alderwood gravelly sandy loam, 15-30% slopes Sk = Seattle muck W = Water FIGURE 5 ASSESSOR MAP Horizontal: Scale: Vertical: For: Title: ASSESSOR MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 amap.cdr SITE REFERENCE: King County Department of Assessments (Nov. 2018) FIGURE 6 FEMA MAP Horizontal: Scale: Vertical: For: Title: FEMA MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 fema.cdr REFERENCE: Federal Emergency Management Agency (Portion of Map 53033C1235 F, May 1995) Areas determined to be outside 500-year floodplain. ZONE X OTHER AREAS LEGEND SITE FIGURE 7 SENSITIVE AREAS MAP Horizontal: Scale: Vertical: For: Title: SENSITIVE AREAS MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 sens.cdr SITE REFERENCE: King County iMAP (2019) 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 20833.001.doc 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Analysis of the Eight Core Requirements Core Requirement No. 1: Discharge at the Natural Location. Response: A portion of the site currently infiltrates with the remainder sloped to drain toward the existing wetland. The proposed development will continue to infiltrate within the area containing receptive soils. The remainder of the site is designed for detention within a pond prior to discharging to the slope that drains to the existing wetlands, thus maintaining the natural discharge location. Core Requirement No. 2: Off-Site Analysis. Response: A Level 1 Downstream Analysis is included within this Technical Information Report. Core Requirement No. 3: Flow Control. Response: Level 2 Flow Control is required for the project. An infiltration gallery will provide full infiltration for approximately 45% of the site area, with the remaining runoff draining to a detention pond which is designed per the Level 2 standard. Core Requirement No. 4: Conveyance System. Response: The proposed conveyance system will be designed utilizing a 25-year precipitation event and a Manning's 'n' value of 0.012 for the pipes. Calculations will be provided within the final Technical Information Report. Core Requirement No. 5: Erosion and Sediment Control. Response: This project is proposing to clear and grade the portion of the site to be developed and construct two buildings, routing all runoff from the developed area into a sediment pond prior to discharge towards the existing wetland. There will be a silt fence around the entire perimeter of the site, along with a construction entrance installed from 32nd Avenue South. The clearing limits will be the property boundary to the north, south, and east limits, and along the limits of work to the west. A sensitive area fence will be established to protect the existing wetlands. Temporary v-ditches with rock check dams routing stormwater to a temporary sediment pond will control erosion and sediment on site during construction. Core Requirement No. 6: Maintenance and Operations. Response: The proposal for this development is for all stormwater facilities to be maintained by private parties, a maintenance and operation manual is included in section 10.0 of this report. Core Requirement No. 7: Financial Guarantees and Liability. Response: This project will conform to all financial guarantee and liability requirements that King County and Federal Way require for projects of this nature. 20833.001.doc Core Requirement No. 8: Water Quality. Response: Enhanced Basic water quality treatment is required for this commercial development. A Modular Wetland System, or equivalent, is proposed for treatment of approximately half the site. Modular Wetland Systems have a General Use Level Designation (GULD) for Enhanced Treatment by the Department of Ecology and should meet the treatment standard. The remaining site area will infiltrate through soils which meet the treatment standards of Section 5.2.1 of the KCSWDM. A suitable pretreatment filter (Contech or equivalent) is proposed upstream of the infiltration system. Core Requirement No. 9: Flow Control BMPs. Response: Infiltration is provided for approx. 45% of the proposed improvements. 2.2 Analysis of the Five Special Requirement Special Requirement No. 1: Other Adopted Area-Specific Requirements. Response: This project is located within the Hylebos Creek Drainage basin part of the Puyallup River Watershed. No area specific requirements are noted at this time. Special Requirement No. 2: Flood Hazard Area Delineation. Response: Per FEMA map panel 53033C1235 F, this project in not located within the 500-year floodplain; therefore, there is no flood hazard area delineation required for this project site. Special Requirement No. 3: Flood Protection Facilities. Response: This project does not meet the threshold for this requirement. Special Requirement No. 4: Source Control. Response: This project will provide source controls in accordance with City of Federal Way requirements, which will include at a minimum sweeping the parking lot on a regular basis, covering the trash enclosures, and educating the property owner about the proper use of pesticides and fertilizers on this project site. Special Requirement No. 5: Oil Control. Response: The proposed development is considered a high-use site due to storage and maintenance of diesel trucks. Oil control facilities are proposed for placement in the conveyance system upstream of each flow control facility. 3.0 OFF-SITE ANALYSIS LEVEL 1 OFF-SITE DRAINAGE ANALYSIS Papé Kenworth NW – Federal Way NE Corner of I-5 and South 320th Street Federal Way, WA 98003 Prepared for: Papé Properties 355 Goodpasture Island Road Eugene, OR 97401 June 4, 2020 Our Job No. 20833 06/04/2020 20833.002 TABLE OF CONTENTS TASK 1 STUDY AREA DEFINITION AND MAPS EXHIBIT A Vicinity Map EXHIBIT B Downstream Drainage Map EXHIBIT C Upstream Basin Map TASK 2 RESOURCE REVIEW EXHIBIT D FEMA Map EXHIBIT E Sensitive Areas Folios EXHIBIT F Soil Survey Map EXHIBIT G Assessor’s Map EXHIBIT H Flow Control Applications Map TASK 3 FIELD INSPECTION 3.2 Downstream Drainage Problems Requiring Special Attention 3.1.1 Conveyance System Nuisance Problems (Type 1) 3.1.2 Severe Erosion Problems (Type 2) 3.1.3 Severe Flooding Problems (Type 3) 3.1.4 Potential Impacts to Wetland Hydrology Problem (Type 4) 3.2 Downstream Water Quality Problems Requiring Special Attention 3.2.1 Dissolved Oxygen (DO) Problem (Type 2) 3.2.2 Temperature Problem (Type 3) 3.2.3 High pH Problem (Type 7) TASK 4 DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS TASK 5 MITIGATION OF EXISTING OR POTENTIAL PROBLEMS TASK 1 STUDY AREA DEFINITION AND MAPS 20833.002 TASK 1 STUDY AREA DEFINITION AND MAPS This project is located on a 19.9-acre site within a portion of the Southeast quarter of the Southeast quarter of Section 9, Township 21 North, Range 4 East, Willamette Meridian, City of Federal Way, King County, Washington. More particularly, the site is located at the NE corner of I-5 and South 320th Street, Federal Way, WA 98003, on King County tax parcels 092104-9028, 092104-9139, 092104-9316, 092104- 9187, 092104-9140, 092104-9160, and 092104-9206. As a part of this project, a boundary line adjustment and right of way dedication will establish a new lot line. The parcels are currently within unincorporated King County, and is being reviewed by the City of Federal way as if the property has been annexed into Federal Way and zoned Community Business (BC). The existing site is mainly moderate to steep slopes and partially forested. There are two existing transmission towers located on the site, and existing easements with AFN. 5746718, 3139642, 3288633, 4963340, 4972634, & 4972636. These easements run in a NE/SW fashion across the site and total 290-ft in width. There are existing homes and gravel access roads across the various parcels. The west side of the site contains a wetland area that will be protected by appropriate buffers. Of the 19.9 acres, approximately 13.8 acres are buildable due to the existing wetland and buffer. After the necessary ROW dedication, the buildable site is approximately 13 acres in size. The existing easements further encumber 4.15 acres of the site. The proposed development includes a 1.3 acre building, a 0.32 acre building, associated concrete truck docks, asphalt paved parking lot, and vegetation/landscaping. There will also be frontage improvements along S 320th Street and 32nd Avenue South totaling an additional ±1.9 acres. The developed site will be contained within a single basin with approximate area of 13.2 acres, tributary to the onsite wetland. The developed site will contain approximately 90% impervious surface area. UPSTREAM DRAINAGE ANALYSIS Based on a site survey, it appears there is no upstream flow onto the site. EXHIBIT A Vicinity Map Horizontal: Scale: Vertical: For: Title: VICINITY MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 vmap.cdr REFERENCE: Rand McNally (2020) SITE EXHIBIT B Downstream Drainage Map Kin g C ounty DOW NSTREAM DRAIN AGE MAP Date: 3/6/2020 Notes:±The i nfor ma tion inclu ded on thi s map has been c om pil ed by King Cou nty s taff from a vari ety of so urc es a n d is subject to c ha n ge w ith out n otice. King C ountymakes n o r epr e sentations o r w ar ra ntie s, express o r i mp li ed , as to acc ur a cy, co m pl ete ness, tim e line ss, or ri g hts to the use of s uc h i nform a tion . T hi s doc um e n t i snot intended for us e as a su rvey pr odu ct. King C ounty shall not be l iabl e for an y gene r al , spec ia l, in dire ct, inci de n ta l, or conse que ntia l dam a ges i nclu d in g,but n ot li mi ted to, lost reve n ues o r l os t p r ofi ts resulting fro m the use or mi suse of the i nfor ma tion contained on this m ap. An y s al e of this m ap or in form atio n onthis map is prohibited ex cept by wr itten pe r mis sion of King Cou n ty. Leg end Pa rc els in de x c on to ur s - 10 0 foot co nt ou rs - 5 fo ot (be low 1 00 0feet) an d 10 foo t PROJECT SITE (19.9 AC) DOWNSTREAM FLOW PATH (1/4 MILE) EXHIBIT C Upstream Basin Map Kin g C ounty UPSTREAM DRAINAGE MAP Date: 3/6/2020 Notes:±The i nfor ma tion inclu ded on thi s map has been c om pil ed by King Cou nty s taff from a vari ety of so urc es a n d is subject to c ha n ge w ith out n otice. King C ountymakes n o r epr e sentations o r w ar ra ntie s, express o r i mp li ed , as to acc ur a cy, co m pl ete ness, tim e line ss, or ri g hts to the use of s uc h i nform a tion . T hi s doc um e n t i snot intended for us e as a su rvey pr odu ct. King C ounty shall not be l iabl e for an y gene r al , spec ia l, in dire ct, inci de n ta l, or conse que ntia l dam a ges i nclu d in g,but n ot li mi ted to, lost reve n ues o r l os t p r ofi ts resulting fro m the use or mi suse of the i nfor ma tion contained on this m ap. An y s al e of this m ap or in form atio n onthis map is prohibited ex cept by wr itten pe r mis sion of King Cou n ty. Leg end Pa rc els in de x c on to ur s - 10 0 foot co nt ou rs - 5 fo ot (be low 1 00 0feet) an d 10 foo t TASK 2 RESOURCE REVIEW 20833.002 TASK 2 RESOURCE REVIEW · Adopted Basin Plans: The site is part of the Hylebos Creek Drainage Basin. · Finalized Drainage Studies: No drainage studies were found for the site or surrounding drainage basin. · Basin Reconnaissance Summary Report: This site is located in the Hylebos Creek Drainage Basin. The King County Reconnaissance Report No. 3 Hylebos Creek Basin was reviewed and no water quality problems were noted along the creek within the downstream path. · Critical Drainage Area Maps: King County iMap was reviewed for the site. A wetland is mapped at the west property margin and receives drainage from the site. A Wetland report has been prepared for the site to address this issue. · Floodplain and Floodway FEMA Maps: Please see the enclosed Exhibit D – FEMA Map utilized for this analysis. Based on our review of the FEMA floodplain map, the site is not located within the floodplain. · Other Off-Site Analysis Reports: No other reports were reviewed for this project. · Sensitive Areas Folios: King County iMap was reviewed for the site. Steep slopes are located along the west side of the property. Portions of the slope are mapped as a Landslide Hazard Area. The slopes are also mapped as an Erosion Hazard Area. The wetland noted above is located at the bottom of the slope. A Geotechnical report has been prepared for the site which addresses the existing slopes. · Drainage Complaints: King County iMap was reviewed for drainage complaints for the site and downstream path. There are a couple water quality complaints related to the subject property, but no flooding complaints noted. · Road Drainage Problems: There are no known road drainage problems in the vicinity of the project. · United States Department of Agriculture King County Soils Survey: Based on the Soils Map for this area, the majority of the site area being developed is located within Everett-Alderwood gravelly sandy loam, while the remainder of the site is located within Seattle Muck. See Exhibit F – Soil Survey Map. · Migrating River Studies: This is not applicable. · Department of Ecology 303(d) Waters: No features within the downstream investigation limit are mapped as 303(d) waters. The lower reaches of Hylebos Creek include listings for Dissolved Oxygen, Bacteria, and Temperature. EXHIBIT D FEMA Map Horizontal: Scale: Vertical: For: Title: FEMA MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 fema.cdr REFERENCE: Federal Emergency Management Agency (Portion of Map 53033C1235 F, May 1995) Areas determined to be outside 500-year floodplain. ZONE X OTHER AREAS LEGEND SITE EXHIBIT E Sensitive Areas Folios Horizontal: Scale: Vertical: For: Title: SENSITIVE AREAS MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 sens.cdr SITE REFERENCE: King County iMAP (2019) EXHIBIT F Soil Survey Map Horizontal: Scale: Vertical: For: Title: SOIL SURVEY MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 soil.cdr HSG B B B/D - REFERENCE: USDA, Natural Resources Conservation Service LEGEND: AgC = Alderwood gravelly sandy loam, 8-15% slopes SITE AgD = Alderwood gravelly sandy loam, 15-30% slopes Sk = Seattle muck W = Water EXHIBIT G Assessor's Map Horizontal: Scale: Vertical: For: Title: ASSESSOR MAP Job Number N.T.S.N/A 20833 DATE: 03/04/20 Pape - Kenworth Northwest Auburn, Washington P:\20000s\20833\exhibit\graphics\20833 amap.cdr SITE REFERENCE: King County Department of Assessments (Nov. 2018) EXHIBIT H FLOW CONTROL APPLICATIONS MAP Fife Milton Tacoma DesMoines Edgewood Pacific AuburnFederalWay Kent Hyl e b o s C r e e k W a t e r w a y Bla i r W a t e r w a y P uyallu p R i v erPuget Sound BayDumas PovertyBay Sit c u m W a t e r w a y CommencementBay LakeSteel Star Lake MirrorLake GenevaLake North Lake Lorene Lake JeaneLake EasterLake Dolloff LakeTroutLake FiveMileLakeLake KillarneyHOYT RD SW MILITARY RD SWEST VALLEY HWYS 288th ST DASH POINT R D DASH PT RDMILITARY RD S21st AVE SWPACIFIC HWYMARINE VIEW DRSW 336th ST NORTHSHORE PK W Y INTERSTATE 5E 11th STHWY 18H W Y 18PACIFIC HWY S28TH AVE SENC HAN T ED P KW Y 51st AVE SINTERSTATE 51st AVE SPACIFIC HWY SS 320th ST 21st AVE SWS 336th ST1st AVE SS 312th ST SW 320th ST SW 356th ST S 348th ST SR 99S 272nd ST 33rd ST NE Lower PugetSound Basin HylebosCreekBasin MillCreekBasin LowerGreenRiverBasin 0 0.5 10.25 Mile This map is intended for use as a graphical representation only. The City of Federal Way makes no warranty as to its accuracy. Legend Drainage Basin Boundary Streams City Limits Lakes and Wetlands Scale: City of Federal Way Flow ControlApplications Map Map Date: February, 2010SWM DivisionCity of Federal Way33325 8th Ave SPO Box 9718Federal Way, WA 98063(253) 835-2700www.cityoffederalway.com R:\erike\swm\FlowControl\flowcontrol.mxd Flow Control Basic Flow Control Areas Conservation Flow Control Areas Flood Problem Flow Control Areas Major Receiving Waters1. Puget Sound TASK 3 FIELD INSPECTION & TASK 4 DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS 20833.002 TASK 3 AND 4 – FIELD INSPECTION AND DRAINAGE SYSTEM DESCRIPTION Level 1 Off-site Drainage Analysis: The field reconnaissance for the Level 1 Off-site Drainage Analysis was conducted on May 27, 2020. On the day of the site visit, conditions were clear. Upstream Drainage Basin: There is no upstream drainage basin tributary to the site. The site is higher than the adjacent roads to the south and east. Runoff travels in a general northwest direction from the site toward the wetland along the west side of the property. On-site Drainage Basin: The onsite stormwater drains in a general northwest direction over vegetated terrain, then runs down a moderate to steep slope and into the wetland area located along the west side of the property. The majority of the site is covered in grass, shrubs, or trees, except for gravel roads and a few houses occupying part of the upland area. There are no stormwater features onsite besides the wetland. Downstream Drainage Path: The wetland at the west edge of the property collects the site drainage. Based on review of topographic maps, this wetland appears to collect some of the drainage from properties to the north, as well as part of the freeway to the west. Although the wetland is a local low point, it appears to ultimately drain out to the south within the Hylebos Creek Drainage Basin per the City of Federal Way Flow Control Applications Map. Close inspection of the wetland area was not possible during the site visit. The south property frontage along South 320th Street is collected by a shallow roadside ditch which drains east to west and flows into the onsite wetland area. A portion of the frontage on 32th Avenue South drains south in the road and then enters a catch basin at 320th Street, then joins the ditch flowing west. There were no observed or known problems with the existing conveyance systems along 320th Street. A series of photos are provided below from site visits made on November 22, 2019 and May 27, 2020. 20833.002 Photo 1: Looking west across the power easement. This portion of the site is relatively level. Photo 2: Looking south near east, center part of site. Most of the site is vegetated and sloping northwest. 20833.002 Photo 3: Looking west near the north end of the site. Drainage continues downhill to the northwest. Photo 4: Looking west along the south frontage on 320th Street. The frontage area drains to the ditch and then west and into the wetland. 20833.002 Photo 5: Looking northeast at steep slope which drains into the wetland area at the bottom of the slope. Photo 6: Looking north along the west margin of the site. The bottom of this ravine slopes gently north into the wetland area which begins near the tree line. TASK 5 MITIGATION OF EXISTING AND POTENTIAL PROBLEMS 20833.002 TASK 5 MITIGATION OF EXISTING AND POTENTIAL PROBLEMS Capacity, flooding, erosion, or other stormwater drainage problems were not observed or discovered during the off-site analysis for the proposed development. Runoff from the proposed improvements will be collected and conveyed to appropriate treatment and detention systems conforming to the requirements of the 2016 King County Surface Water Design Manual, as adopted and amended by the City of Federal Way. Treated water will outfall in a controlled manner to the natural discharge location near the wetland. Temporary Erosion and Sediment Control (TESC) measures will mitigate runoff concerns during the project construction. The proposed measures are anticipated to fully mitigate the stormwater impacts of the project. Aggravation or creation of any drainage problem in the downstream system is considered unlikely. No further mitigation is required. 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 20833.001.doc 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN A. Existing Site Hydrology The existing drains to the existing wetland on the west side of the property. A majority of the land is moderate to steep slopes and forested. B. Developed Site Hydrology Under the developed conditions the developed portion of the site will be approximately 90 percent impervious surface. The developed site area and offsite improvements are approximately 13.23 acres with water quality and flow control being provided for this area. Runoff from the roof area will be conveyed directly to the infiltration galleries and detention pond while runoff from pollution generating surfaces will receive water quality treatment before infiltration/detention. The proposed gallery will infiltrate 45% of developed drainage basin, with the remaining 55% being detained by the onsite detention pond prior to discharging towards the existing wetlands. C. Performance Standards This site is located within unincorporated King County for flow control and water quality purposes. Level 2 flow control is required as well as enhanced basic water quality and oil spill protection, per KCSWDM groundwater protection requirements. The SBUH Method will be used for pipe conveyance, as the site is greater than 10 acres. Conveyance calculations will be provided with the final copy of this report. D. Flow Control System Runoff from the north end of the site plus part of the 32nd Ave South frontage, totaling approximately 45% of the improvements, is designed to infiltrate within two trenches located below the north end of the parking lot. Each trench is designed to infiltrate the tributary storms up to and including the 100-year event. Basic water quality facilities, Contech or equivalent, are designed for installation immediately upstream of each trench to provide removal of suspended solids prior to entering the infiltration facility. The two trenches are summarized below: Tributary Area (ac) Length (ft) Width (ft) Depth (ft) Design Infiltration rate (in/hr)* Trench 1 2.22 270 25 7 2.75 Trench 2 3.72 362 25 7 4.5 *Infiltration rates are based on the Geotechnical Report in Section 6. Trench 2 rate includes interpolation between nearest test pit data. The remainder of the site and frontage improvements are proposed for mitigated using a detention pond in the southwest of the site. The pond is designed for Level 2 flow control, with detained water slowly released to the wetland on the west side of the site. The frontage improvements on South 320th Street are located below the pond elevation. A flow splitter plus a duplex pump system are proposed to convey runoff, proportionate to the new impervious area, up to the detention pond. Further details will be included within the final Technical Information Report. 20833.001.doc Refer to the included Developed Basin Map and WWHM reports included on the following pages for additional flow control information. E. Water Quality System The pond system will include an oil-water separator vault located upstream of the pond. A Modular Wetland Systems (MWS) vault is proposed downstream of the pond to provide enhanced treatment of the runoff prior to discharge. The infiltration trenches will include a treatment train consisting of an oil-water separator vault plus a cartridge system (Contech or equivalent) to remove oil and suspended solids prior to entering the trench. Further water quality treatment meeting the enhanced standard is provided by natural filtration through the soils underlying the infiltration trenches. Refer to the Geotechnical report in Section 6 for more soils information. Sizing for the various treatment systems will be provided with the final Technical Information Report. DEVELOPED BASIN MAP DETENTION AND INFILTRATION SIZING CALCULATIONS WWHM2012 PROJECT REPORT DETENTION POND SIZING 6/4/2020 20833-pond 6/4/2020 3:15:50 PM Page 2 General Model Information Project Name:20833-pond Site Name: Site Address: City: Report Date:6/4/2020 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2019/09/13 Version:4.2.17 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year 20833-pond 6/4/2020 3:15:50 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Mod 7.3 Pervious Total 7.3 Impervious Land Use acre Impervious Total 0 Basin Total 7.3 Element Flows To: Surface Interflow Groundwater 20833-pond 6/4/2020 3:15:51 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.52 Pervious Total 0.52 Impervious Land Use acre ROADS FLAT 6.03 POND 0.75 Impervious Total 6.78 Basin Total 7.3 Element Flows To: Surface Interflow Groundwater Trapezoidal Pond 1 Trapezoidal Pond 1 20833-pond 6/4/2020 3:15:53 PM Page 6 Mitigated Routing Trapezoidal Pond 1 Bottom Length:278.00 ft. Bottom Width:37.00 ft. Depth:8.5 ft. Volume at riser head:3.2295 acre-feet. Side slope 1:3 To 1 Side slope 2:3 To 1 Side slope 3:3 To 1 Side slope 4:5 To 1 Discharge Structure Riser Height:7.5 ft. Riser Diameter:18 in. Orifice 1 Diameter:1.36 in.Elevation:0 ft. Orifice 2 Diameter:1.6 in.Elevation:4.8 ft. Orifice 3 Diameter:2.6 in.Elevation:6 ft. Element Flows To: Outlet 1 Outlet 2 Pond Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.236 0.000 0.000 0.000 0.0944 0.240 0.022 0.015 0.000 0.1889 0.244 0.045 0.021 0.000 0.2833 0.249 0.068 0.026 0.000 0.3778 0.253 0.092 0.030 0.000 0.4722 0.257 0.116 0.034 0.000 0.5667 0.262 0.141 0.037 0.000 0.6611 0.266 0.166 0.040 0.000 0.7556 0.270 0.191 0.043 0.000 0.8500 0.275 0.217 0.046 0.000 0.9444 0.279 0.243 0.048 0.000 1.0389 0.284 0.270 0.051 0.000 1.1333 0.288 0.297 0.053 0.000 1.2278 0.293 0.324 0.055 0.000 1.3222 0.297 0.352 0.057 0.000 1.4167 0.302 0.380 0.059 0.000 1.5111 0.306 0.409 0.061 0.000 1.6056 0.311 0.438 0.063 0.000 1.7000 0.316 0.468 0.065 0.000 1.7944 0.320 0.498 0.067 0.000 1.8889 0.325 0.528 0.069 0.000 1.9833 0.329 0.559 0.070 0.000 2.0778 0.334 0.591 0.072 0.000 2.1722 0.339 0.623 0.074 0.000 2.2667 0.344 0.655 0.075 0.000 2.3611 0.348 0.688 0.077 0.000 2.4556 0.353 0.721 0.078 0.000 2.5500 0.358 0.754 0.080 0.000 2.6444 0.363 0.788 0.081 0.000 2.7389 0.367 0.823 0.083 0.000 2.8333 0.372 0.858 0.084 0.000 2.9278 0.377 0.893 0.085 0.000 3.0222 0.382 0.929 0.087 0.000 20833-pond 6/4/2020 3:15:53 PM Page 7 3.1167 0.387 0.966 0.088 0.000 3.2111 0.392 1.002 0.089 0.000 3.3056 0.397 1.040 0.091 0.000 3.4000 0.402 1.077 0.092 0.000 3.4944 0.407 1.116 0.093 0.000 3.5889 0.412 1.154 0.095 0.000 3.6833 0.417 1.194 0.096 0.000 3.7778 0.422 1.233 0.097 0.000 3.8722 0.427 1.273 0.098 0.000 3.9667 0.432 1.314 0.100 0.000 4.0611 0.437 1.355 0.101 0.000 4.1556 0.442 1.396 0.102 0.000 4.2500 0.447 1.439 0.103 0.000 4.3444 0.452 1.481 0.104 0.000 4.4389 0.458 1.524 0.105 0.000 4.5333 0.463 1.568 0.106 0.000 4.6278 0.468 1.612 0.108 0.000 4.7222 0.473 1.656 0.109 0.000 4.8167 0.478 1.701 0.119 0.000 4.9111 0.484 1.746 0.134 0.000 5.0056 0.489 1.792 0.143 0.000 5.1000 0.494 1.839 0.151 0.000 5.1944 0.500 1.886 0.158 0.000 5.2889 0.505 1.933 0.164 0.000 5.3833 0.510 1.981 0.169 0.000 5.4778 0.516 2.030 0.174 0.000 5.5722 0.521 2.079 0.179 0.000 5.6667 0.527 2.128 0.184 0.000 5.7611 0.532 2.178 0.188 0.000 5.8556 0.537 2.229 0.192 0.000 5.9500 0.543 2.280 0.196 0.000 6.0444 0.548 2.332 0.239 0.000 6.1389 0.554 2.384 0.273 0.000 6.2333 0.560 2.436 0.297 0.000 6.3278 0.565 2.489 0.317 0.000 6.4222 0.571 2.543 0.334 0.000 6.5167 0.576 2.597 0.351 0.000 6.6111 0.582 2.652 0.366 0.000 6.7056 0.588 2.707 0.380 0.000 6.8000 0.593 2.763 0.393 0.000 6.8944 0.599 2.820 0.405 0.000 6.9889 0.605 2.876 0.417 0.000 7.0833 0.610 2.934 0.429 0.000 7.1778 0.616 2.992 0.440 0.000 7.2722 0.622 3.050 0.451 0.000 7.3667 0.628 3.109 0.462 0.000 7.4611 0.633 3.169 0.472 0.000 7.5556 0.639 3.229 0.690 0.000 7.6500 0.645 3.290 1.410 0.000 7.7444 0.651 3.351 2.378 0.000 7.8389 0.657 3.413 3.456 0.000 7.9333 0.663 3.475 4.508 0.000 8.0278 0.669 3.538 5.407 0.000 8.1222 0.675 3.602 6.068 0.000 8.2167 0.681 3.666 6.500 0.000 8.3111 0.687 3.730 6.936 0.000 8.4056 0.693 3.795 7.305 0.000 8.5000 0.699 3.861 7.656 0.000 20833-pond 6/4/2020 3:15:54 PM Page 8 8.5944 0.705 3.927 7.991 0.000 20833-pond 6/4/2020 3:15:54 PM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:7.3 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.52 Total Impervious Area:6.78 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.217359 5 year 0.356162 10 year 0.445409 25 year 0.551573 50 year 0.625109 100 year 0.693795 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.140948 5 year 0.220547 10 year 0.287028 25 year 0.389014 50 year 0.479609 100 year 0.584124 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.250 0.097 1950 0.297 0.135 1951 0.475 0.379 1952 0.149 0.089 1953 0.120 0.134 1954 0.185 0.104 1955 0.295 0.103 1956 0.238 0.188 1957 0.192 0.104 1958 0.213 0.111 20833-pond 6/4/2020 3:18:53 PM Page 10 1959 0.183 0.098 1960 0.328 0.307 1961 0.180 0.164 1962 0.112 0.091 1963 0.154 0.108 1964 0.218 0.157 1965 0.145 0.179 1966 0.139 0.105 1967 0.334 0.142 1968 0.188 0.105 1969 0.183 0.102 1970 0.147 0.109 1971 0.166 0.108 1972 0.361 0.300 1973 0.160 0.176 1974 0.177 0.107 1975 0.247 0.101 1976 0.176 0.105 1977 0.026 0.097 1978 0.149 0.137 1979 0.090 0.086 1980 0.424 0.334 1981 0.133 0.106 1982 0.275 0.204 1983 0.235 0.106 1984 0.142 0.092 1985 0.084 0.098 1986 0.372 0.160 1987 0.329 0.272 1988 0.130 0.102 1989 0.086 0.097 1990 0.787 0.299 1991 0.417 0.305 1992 0.170 0.135 1993 0.166 0.092 1994 0.056 0.085 1995 0.238 0.165 1996 0.551 0.365 1997 0.425 0.384 1998 0.104 0.094 1999 0.466 0.314 2000 0.166 0.151 2001 0.030 0.083 2002 0.192 0.174 2003 0.287 0.104 2004 0.306 0.403 2005 0.227 0.105 2006 0.256 0.190 2007 0.595 0.469 2008 0.725 0.358 2009 0.338 0.178 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.7871 0.4693 2 0.7252 0.4029 3 0.5949 0.3844 20833-pond 6/4/2020 3:18:53 PM Page 11 4 0.5512 0.3790 5 0.4749 0.3652 6 0.4664 0.3577 7 0.4254 0.3339 8 0.4244 0.3137 9 0.4175 0.3072 10 0.3725 0.3051 11 0.3605 0.3001 12 0.3381 0.2994 13 0.3338 0.2720 14 0.3288 0.2041 15 0.3277 0.1900 16 0.3065 0.1876 17 0.2969 0.1794 18 0.2954 0.1781 19 0.2868 0.1760 20 0.2752 0.1744 21 0.2558 0.1655 22 0.2502 0.1641 23 0.2466 0.1604 24 0.2384 0.1572 25 0.2380 0.1510 26 0.2355 0.1419 27 0.2274 0.1368 28 0.2184 0.1354 29 0.2133 0.1349 30 0.1921 0.1340 31 0.1921 0.1108 32 0.1879 0.1091 33 0.1849 0.1085 34 0.1829 0.1077 35 0.1828 0.1072 36 0.1802 0.1063 37 0.1771 0.1061 38 0.1762 0.1052 39 0.1705 0.1050 40 0.1664 0.1047 41 0.1657 0.1046 42 0.1657 0.1043 43 0.1598 0.1037 44 0.1539 0.1036 45 0.1490 0.1025 46 0.1489 0.1021 47 0.1468 0.1019 48 0.1451 0.1009 49 0.1418 0.0985 50 0.1395 0.0978 51 0.1332 0.0972 52 0.1298 0.0970 53 0.1204 0.0967 54 0.1121 0.0939 55 0.1041 0.0918 56 0.0901 0.0916 57 0.0859 0.0907 58 0.0842 0.0891 59 0.0559 0.0856 60 0.0298 0.0845 61 0.0258 0.0831 20833-pond 6/4/2020 3:18:53 PM Page 13 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.1087 17312 15389 88 Pass 0.1139 15729 12596 80 Pass 0.1191 14093 11364 80 Pass 0.1243 12859 10654 82 Pass 0.1295 11693 10051 85 Pass 0.1348 10649 9492 89 Pass 0.1400 9730 8857 91 Pass 0.1452 8778 8162 92 Pass 0.1504 8094 7495 92 Pass 0.1556 7424 6821 91 Pass 0.1608 6836 6051 88 Pass 0.1661 6192 5208 84 Pass 0.1713 5754 4530 78 Pass 0.1765 5345 3814 71 Pass 0.1817 4966 3311 66 Pass 0.1869 4631 2834 61 Pass 0.1921 4248 2239 52 Pass 0.1974 3965 1723 43 Pass 0.2026 3675 1658 45 Pass 0.2078 3429 1605 46 Pass 0.2130 3133 1556 49 Pass 0.2182 2926 1508 51 Pass 0.2234 2723 1471 54 Pass 0.2287 2511 1429 56 Pass 0.2339 2348 1391 59 Pass 0.2391 2136 1344 62 Pass 0.2443 1981 1306 65 Pass 0.2495 1838 1260 68 Pass 0.2547 1723 1209 70 Pass 0.2600 1599 1172 73 Pass 0.2652 1445 1122 77 Pass 0.2704 1334 1071 80 Pass 0.2756 1244 1008 81 Pass 0.2808 1160 955 82 Pass 0.2860 1086 900 82 Pass 0.2913 1022 847 82 Pass 0.2965 957 789 82 Pass 0.3017 893 720 80 Pass 0.3069 838 660 78 Pass 0.3121 761 610 80 Pass 0.3173 725 575 79 Pass 0.3226 678 544 80 Pass 0.3278 633 487 76 Pass 0.3330 596 427 71 Pass 0.3382 552 381 69 Pass 0.3434 507 355 70 Pass 0.3486 475 332 69 Pass 0.3539 431 305 70 Pass 0.3591 388 271 69 Pass 0.3643 356 250 70 Pass 0.3695 329 229 69 Pass 0.3747 301 212 70 Pass 0.3799 274 184 67 Pass 20833-pond 6/4/2020 3:18:53 PM Page 14 0.3852 242 160 66 Pass 0.3904 219 152 69 Pass 0.3956 199 140 70 Pass 0.4008 179 125 69 Pass 0.4060 152 111 73 Pass 0.4112 130 106 81 Pass 0.4165 119 101 84 Pass 0.4217 107 88 82 Pass 0.4269 95 80 84 Pass 0.4321 83 66 79 Pass 0.4373 75 60 80 Pass 0.4425 69 53 76 Pass 0.4477 62 46 74 Pass 0.4530 54 41 75 Pass 0.4582 46 35 76 Pass 0.4634 39 25 64 Pass 0.4686 31 8 25 Pass 0.4738 25 0 0 Pass 0.4790 22 0 0 Pass 0.4843 20 0 0 Pass 0.4895 18 0 0 Pass 0.4947 14 0 0 Pass 0.4999 13 0 0 Pass 0.5051 8 0 0 Pass 0.5103 7 0 0 Pass 0.5156 7 0 0 Pass 0.5208 7 0 0 Pass 0.5260 6 0 0 Pass 0.5312 6 0 0 Pass 0.5364 6 0 0 Pass 0.5416 6 0 0 Pass 0.5469 6 0 0 Pass 0.5521 5 0 0 Pass 0.5573 5 0 0 Pass 0.5625 5 0 0 Pass 0.5677 5 0 0 Pass 0.5729 5 0 0 Pass 0.5782 5 0 0 Pass 0.5834 5 0 0 Pass 0.5886 4 0 0 Pass 0.5938 4 0 0 Pass 0.5990 3 0 0 Pass 0.6042 3 0 0 Pass 0.6095 3 0 0 Pass 0.6147 3 0 0 Pass 0.6199 3 0 0 Pass 0.6251 3 0 0 Pass 20833-pond 6/4/2020 3:20:06 PM Page 18 Appendix Predeveloped Schematic 20833-pond 6/4/2020 3:21:40 PM Page 19 Mitigated Schematic 20833-pond 6/4/2020 3:23:13 PM Page 24 Disclaimer Legal Notice This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions, Inc. disclaims 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. has been advised of the possibility of such damages. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com WWHM2012 PROJECT REPORT INFILTRATION TRENCH #1 FACILITY SIZING 6/3/2020 20833-Upper Infil 6/3/2020 12:41:58 PM Page 2 General Model Information Project Name:20833-Upper Infil Site Name: Site Address: City: Report Date:6/3/2020 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2019/09/13 Version:4.2.17 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year 20833-Upper Infil 6/3/2020 12:42:00 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Mod 2.22 Pervious Total 2.22 Impervious Land Use acre Impervious Total 0 Basin Total 2.22 Element Flows To: Surface Interflow Groundwater 20833-Upper Infil 6/3/2020 12:42:01 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre PARKING FLAT 2.22 Impervious Total 2.22 Basin Total 2.22 Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 20833-Upper Infil 6/3/2020 12:42:03 PM Page 6 Mitigated Routing Gravel Trench Bed 1 Bottom Length:270.00 ft. Bottom Width:25.00 ft. Trench bottom slope 1:0 To 1 Trench Left side slope 0:0 To 1 Trench right side slope 2:0 To 1 Material thickness of first layer:6 Pour Space of material for first layer:0.4 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 Infiltration On Infiltration rate:2.75 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):348.849 Total Volume Through Riser (ac-ft.):0 Total Volume Through Facility (ac-ft.):348.849 Percent Infiltrated:100 Total Precip Applied to Facility:0 Total Evap From Facility:0 Discharge Structure Riser Height:6 ft. Riser Diameter:18 in. 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 0.155 0.000 0.000 0.000 0.0778 0.155 0.004 0.000 0.429 0.1556 0.155 0.009 0.000 0.429 0.2333 0.155 0.014 0.000 0.429 0.3111 0.155 0.019 0.000 0.429 0.3889 0.155 0.024 0.000 0.429 0.4667 0.155 0.028 0.000 0.429 0.5444 0.155 0.033 0.000 0.429 0.6222 0.155 0.038 0.000 0.429 0.7000 0.155 0.043 0.000 0.429 0.7778 0.155 0.048 0.000 0.429 0.8556 0.155 0.053 0.000 0.429 0.9333 0.155 0.057 0.000 0.429 1.0111 0.155 0.062 0.000 0.429 1.0889 0.155 0.067 0.000 0.429 1.1667 0.155 0.072 0.000 0.429 1.2444 0.155 0.077 0.000 0.429 1.3222 0.155 0.082 0.000 0.429 1.4000 0.155 0.086 0.000 0.429 1.4778 0.155 0.091 0.000 0.429 1.5556 0.155 0.096 0.000 0.429 1.6333 0.155 0.101 0.000 0.429 1.7111 0.155 0.106 0.000 0.429 1.7889 0.155 0.110 0.000 0.429 20833-Upper Infil 6/3/2020 12:42:04 PM Page 7 1.8667 0.155 0.115 0.000 0.429 1.9444 0.155 0.120 0.000 0.429 2.0222 0.155 0.125 0.000 0.429 2.1000 0.155 0.130 0.000 0.429 2.1778 0.155 0.135 0.000 0.429 2.2556 0.155 0.139 0.000 0.429 2.3333 0.155 0.144 0.000 0.429 2.4111 0.155 0.149 0.000 0.429 2.4889 0.155 0.154 0.000 0.429 2.5667 0.155 0.159 0.000 0.429 2.6444 0.155 0.163 0.000 0.429 2.7222 0.155 0.168 0.000 0.429 2.8000 0.155 0.173 0.000 0.429 2.8778 0.155 0.178 0.000 0.429 2.9556 0.155 0.183 0.000 0.429 3.0333 0.155 0.188 0.000 0.429 3.1111 0.155 0.192 0.000 0.429 3.1889 0.155 0.197 0.000 0.429 3.2667 0.155 0.202 0.000 0.429 3.3444 0.155 0.207 0.000 0.429 3.4222 0.155 0.212 0.000 0.429 3.5000 0.155 0.216 0.000 0.429 3.5778 0.155 0.221 0.000 0.429 3.6556 0.155 0.226 0.000 0.429 3.7333 0.155 0.231 0.000 0.429 3.8111 0.155 0.236 0.000 0.429 3.8889 0.155 0.241 0.000 0.429 3.9667 0.155 0.245 0.000 0.429 4.0444 0.155 0.250 0.000 0.429 4.1222 0.155 0.255 0.000 0.429 4.2000 0.155 0.260 0.000 0.429 4.2778 0.155 0.265 0.000 0.429 4.3556 0.155 0.270 0.000 0.429 4.4333 0.155 0.274 0.000 0.429 4.5111 0.155 0.279 0.000 0.429 4.5889 0.155 0.284 0.000 0.429 4.6667 0.155 0.289 0.000 0.429 4.7444 0.155 0.294 0.000 0.429 4.8222 0.155 0.298 0.000 0.429 4.9000 0.155 0.303 0.000 0.429 4.9778 0.155 0.308 0.000 0.429 5.0556 0.155 0.313 0.000 0.429 5.1333 0.155 0.318 0.000 0.429 5.2111 0.155 0.323 0.000 0.429 5.2889 0.155 0.327 0.000 0.429 5.3667 0.155 0.332 0.000 0.429 5.4444 0.155 0.337 0.000 0.429 5.5222 0.155 0.342 0.000 0.429 5.6000 0.155 0.347 0.000 0.429 5.6778 0.155 0.351 0.000 0.429 5.7556 0.155 0.356 0.000 0.429 5.8333 0.155 0.361 0.000 0.429 5.9111 0.155 0.366 0.000 0.429 5.9889 0.155 0.371 0.000 0.429 6.0667 0.155 0.383 0.273 0.429 6.1444 0.155 0.395 0.869 0.429 6.2222 0.155 0.407 1.636 0.429 6.3000 0.155 0.419 2.501 0.429 20833-Upper Infil 6/3/2020 12:42:05 PM Page 8 6.3778 0.155 0.431 3.386 0.429 6.4556 0.155 0.443 4.216 0.429 6.5333 0.155 0.455 4.924 0.429 6.6111 0.155 0.467 5.468 0.429 6.6889 0.155 0.479 5.848 0.429 6.7667 0.155 0.491 6.205 0.429 6.8444 0.155 0.503 6.512 0.429 6.9222 0.155 0.515 6.805 0.429 7.0000 0.155 0.527 7.086 0.429 20833-Upper Infil 6/3/2020 12:42:06 PM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:2.22 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:2.22 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.066101 5 year 0.108312 10 year 0.135453 25 year 0.167739 50 year 0.190102 100 year 0.21099 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.076 0.000 1950 0.090 0.000 1951 0.144 0.000 1952 0.045 0.000 1953 0.037 0.000 1954 0.056 0.000 1955 0.090 0.000 1956 0.072 0.000 1957 0.058 0.000 1958 0.065 0.000 20833-Upper Infil 6/3/2020 12:43:18 PM Page 10 1959 0.056 0.000 1960 0.100 0.000 1961 0.055 0.000 1962 0.034 0.000 1963 0.047 0.000 1964 0.066 0.000 1965 0.044 0.000 1966 0.042 0.000 1967 0.102 0.000 1968 0.057 0.000 1969 0.056 0.000 1970 0.045 0.000 1971 0.050 0.000 1972 0.110 0.000 1973 0.049 0.000 1974 0.054 0.000 1975 0.075 0.000 1976 0.054 0.000 1977 0.008 0.000 1978 0.045 0.000 1979 0.027 0.000 1980 0.129 0.000 1981 0.041 0.000 1982 0.084 0.000 1983 0.072 0.000 1984 0.043 0.000 1985 0.026 0.000 1986 0.113 0.000 1987 0.100 0.000 1988 0.039 0.000 1989 0.026 0.000 1990 0.239 0.000 1991 0.127 0.000 1992 0.052 0.000 1993 0.051 0.000 1994 0.017 0.000 1995 0.073 0.000 1996 0.168 0.000 1997 0.129 0.000 1998 0.032 0.000 1999 0.142 0.000 2000 0.050 0.000 2001 0.009 0.000 2002 0.058 0.000 2003 0.087 0.000 2004 0.093 0.000 2005 0.069 0.000 2006 0.078 0.000 2007 0.181 0.000 2008 0.221 0.000 2009 0.103 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.2394 0.0000 2 0.2205 0.0000 3 0.1809 0.0000 20833-Upper Infil 6/3/2020 12:43:18 PM Page 11 4 0.1676 0.0000 5 0.1444 0.0000 6 0.1418 0.0000 7 0.1294 0.0000 8 0.1291 0.0000 9 0.1270 0.0000 10 0.1133 0.0000 11 0.1096 0.0000 12 0.1028 0.0000 13 0.1015 0.0000 14 0.1000 0.0000 15 0.0996 0.0000 16 0.0932 0.0000 17 0.0903 0.0000 18 0.0898 0.0000 19 0.0872 0.0000 20 0.0837 0.0000 21 0.0778 0.0000 22 0.0761 0.0000 23 0.0750 0.0000 24 0.0725 0.0000 25 0.0724 0.0000 26 0.0716 0.0000 27 0.0692 0.0000 28 0.0664 0.0000 29 0.0649 0.0000 30 0.0584 0.0000 31 0.0584 0.0000 32 0.0571 0.0000 33 0.0562 0.0000 34 0.0556 0.0000 35 0.0556 0.0000 36 0.0548 0.0000 37 0.0539 0.0000 38 0.0536 0.0000 39 0.0518 0.0000 40 0.0506 0.0000 41 0.0504 0.0000 42 0.0504 0.0000 43 0.0486 0.0000 44 0.0468 0.0000 45 0.0453 0.0000 46 0.0453 0.0000 47 0.0446 0.0000 48 0.0441 0.0000 49 0.0431 0.0000 50 0.0424 0.0000 51 0.0405 0.0000 52 0.0395 0.0000 53 0.0366 0.0000 54 0.0341 0.0000 55 0.0317 0.0000 56 0.0274 0.0000 57 0.0261 0.0000 58 0.0256 0.0000 59 0.0170 0.0000 60 0.0091 0.0000 61 0.0079 0.0000 20833-Upper Infil 6/3/2020 12:43:18 PM Page 13 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0331 17075 0 0 Pass 0.0346 15490 0 0 Pass 0.0362 14067 0 0 Pass 0.0378 12803 0 0 Pass 0.0394 11567 0 0 Pass 0.0410 10515 0 0 Pass 0.0426 9565 0 0 Pass 0.0442 8750 0 0 Pass 0.0457 8031 0 0 Pass 0.0473 7347 0 0 Pass 0.0489 6733 0 0 Pass 0.0505 6188 0 0 Pass 0.0521 5728 0 0 Pass 0.0537 5309 0 0 Pass 0.0553 4924 0 0 Pass 0.0568 4569 0 0 Pass 0.0584 4235 0 0 Pass 0.0600 3951 0 0 Pass 0.0616 3643 0 0 Pass 0.0632 3388 0 0 Pass 0.0648 3133 0 0 Pass 0.0664 2915 0 0 Pass 0.0680 2701 0 0 Pass 0.0695 2490 0 0 Pass 0.0711 2314 0 0 Pass 0.0727 2136 0 0 Pass 0.0743 1972 0 0 Pass 0.0759 1822 0 0 Pass 0.0775 1702 0 0 Pass 0.0791 1577 0 0 Pass 0.0806 1442 0 0 Pass 0.0822 1325 0 0 Pass 0.0838 1232 0 0 Pass 0.0854 1147 0 0 Pass 0.0870 1084 0 0 Pass 0.0886 1020 0 0 Pass 0.0902 946 0 0 Pass 0.0917 886 0 0 Pass 0.0933 824 0 0 Pass 0.0949 760 0 0 Pass 0.0965 725 0 0 Pass 0.0981 674 0 0 Pass 0.0997 623 0 0 Pass 0.1013 590 0 0 Pass 0.1029 552 0 0 Pass 0.1044 506 0 0 Pass 0.1060 469 0 0 Pass 0.1076 427 0 0 Pass 0.1092 389 0 0 Pass 0.1108 356 0 0 Pass 0.1124 329 0 0 Pass 0.1140 298 0 0 Pass 0.1155 270 0 0 Pass 20833-Upper Infil 6/3/2020 12:43:18 PM Page 14 0.1171 241 0 0 Pass 0.1187 218 0 0 Pass 0.1203 197 0 0 Pass 0.1219 176 0 0 Pass 0.1235 153 0 0 Pass 0.1251 130 0 0 Pass 0.1266 119 0 0 Pass 0.1282 104 0 0 Pass 0.1298 95 0 0 Pass 0.1314 83 0 0 Pass 0.1330 75 0 0 Pass 0.1346 69 0 0 Pass 0.1362 61 0 0 Pass 0.1378 53 0 0 Pass 0.1393 46 0 0 Pass 0.1409 39 0 0 Pass 0.1425 29 0 0 Pass 0.1441 25 0 0 Pass 0.1457 22 0 0 Pass 0.1473 20 0 0 Pass 0.1489 17 0 0 Pass 0.1504 14 0 0 Pass 0.1520 12 0 0 Pass 0.1536 8 0 0 Pass 0.1552 7 0 0 Pass 0.1568 7 0 0 Pass 0.1584 7 0 0 Pass 0.1600 6 0 0 Pass 0.1615 6 0 0 Pass 0.1631 6 0 0 Pass 0.1647 6 0 0 Pass 0.1663 6 0 0 Pass 0.1679 5 0 0 Pass 0.1695 5 0 0 Pass 0.1711 5 0 0 Pass 0.1727 5 0 0 Pass 0.1742 5 0 0 Pass 0.1758 5 0 0 Pass 0.1774 5 0 0 Pass 0.1790 4 0 0 Pass 0.1806 4 0 0 Pass 0.1822 3 0 0 Pass 0.1838 3 0 0 Pass 0.1853 3 0 0 Pass 0.1869 3 0 0 Pass 0.1885 3 0 0 Pass 0.1901 3 0 0 Pass 20833-Upper Infil 6/3/2020 12:43:18 PM Page 16 LID Report 20833-Upper Infil 6/3/2020 12:43:57 PM Page 18 Appendix Predeveloped Schematic 20833-Upper Infil 6/3/2020 12:45:13 PM Page 19 Mitigated Schematic 20833-Upper Infil 6/3/2020 12:46:34 PM Page 32 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2020; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com WWHM2012 PROJECT REPORT INFILTRATION TRENCH #2 FACILITY SIZING 6/3/2020 20833-Lower Infil 6/3/2020 1:33:43 PM Page 2 General Model Information Project Name:20833-Lower Infil Site Name: Site Address: City: Report Date:6/3/2020 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2019/09/13 Version:4.2.17 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year 20833-Lower Infil 6/3/2020 1:33:43 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Mod 3.72 Pervious Total 3.72 Impervious Land Use acre Impervious Total 0 Basin Total 3.72 Element Flows To: Surface Interflow Groundwater 20833-Lower Infil 6/3/2020 1:33:43 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.2 Pervious Total 0.2 Impervious Land Use acre PARKING FLAT 3.52 Impervious Total 3.52 Basin Total 3.72 Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 20833-Lower Infil 6/3/2020 1:33:43 PM Page 6 Mitigated Routing Gravel Trench Bed 1 Bottom Length:350.00 ft. Bottom Width:25.00 ft. Trench bottom slope 1:0 To 1 Trench Left side slope 0:0 To 1 Trench right side slope 2:0 To 1 Material thickness of first layer:5 Pour Space of material for first layer:0.4 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 Infiltration On Infiltration rate:4.5 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):568.962 Total Volume Through Riser (ac-ft.):0 Total Volume Through Facility (ac-ft.):568.962 Percent Infiltrated:100 Total Precip Applied to Facility:0 Total Evap From Facility:0 Discharge Structure Riser Height:5 ft. Riser Diameter:18 in. 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 0.200 0.000 0.000 0.000 0.0667 0.200 0.005 0.000 0.911 0.1333 0.200 0.010 0.000 0.911 0.2000 0.200 0.016 0.000 0.911 0.2667 0.200 0.021 0.000 0.911 0.3333 0.200 0.026 0.000 0.911 0.4000 0.200 0.032 0.000 0.911 0.4667 0.200 0.037 0.000 0.911 0.5333 0.200 0.042 0.000 0.911 0.6000 0.200 0.048 0.000 0.911 0.6667 0.200 0.053 0.000 0.911 0.7333 0.200 0.058 0.000 0.911 0.8000 0.200 0.064 0.000 0.911 0.8667 0.200 0.069 0.000 0.911 0.9333 0.200 0.075 0.000 0.911 1.0000 0.200 0.080 0.000 0.911 1.0667 0.200 0.085 0.000 0.911 1.1333 0.200 0.091 0.000 0.911 1.2000 0.200 0.096 0.000 0.911 1.2667 0.200 0.101 0.000 0.911 1.3333 0.200 0.107 0.000 0.911 1.4000 0.200 0.112 0.000 0.911 1.4667 0.200 0.117 0.000 0.911 1.5333 0.200 0.123 0.000 0.911 20833-Lower Infil 6/3/2020 1:33:43 PM Page 7 1.6000 0.200 0.128 0.000 0.911 1.6667 0.200 0.133 0.000 0.911 1.7333 0.200 0.139 0.000 0.911 1.8000 0.200 0.144 0.000 0.911 1.8667 0.200 0.150 0.000 0.911 1.9333 0.200 0.155 0.000 0.911 2.0000 0.200 0.160 0.000 0.911 2.0667 0.200 0.166 0.000 0.911 2.1333 0.200 0.171 0.000 0.911 2.2000 0.200 0.176 0.000 0.911 2.2667 0.200 0.182 0.000 0.911 2.3333 0.200 0.187 0.000 0.911 2.4000 0.200 0.192 0.000 0.911 2.4667 0.200 0.198 0.000 0.911 2.5333 0.200 0.203 0.000 0.911 2.6000 0.200 0.208 0.000 0.911 2.6667 0.200 0.214 0.000 0.911 2.7333 0.200 0.219 0.000 0.911 2.8000 0.200 0.225 0.000 0.911 2.8667 0.200 0.230 0.000 0.911 2.9333 0.200 0.235 0.000 0.911 3.0000 0.200 0.241 0.000 0.911 3.0667 0.200 0.246 0.000 0.911 3.1333 0.200 0.251 0.000 0.911 3.2000 0.200 0.257 0.000 0.911 3.2667 0.200 0.262 0.000 0.911 3.3333 0.200 0.267 0.000 0.911 3.4000 0.200 0.273 0.000 0.911 3.4667 0.200 0.278 0.000 0.911 3.5333 0.200 0.283 0.000 0.911 3.6000 0.200 0.289 0.000 0.911 3.6667 0.200 0.294 0.000 0.911 3.7333 0.200 0.300 0.000 0.911 3.8000 0.200 0.305 0.000 0.911 3.8667 0.200 0.310 0.000 0.911 3.9333 0.200 0.316 0.000 0.911 4.0000 0.200 0.321 0.000 0.911 4.0667 0.200 0.326 0.000 0.911 4.1333 0.200 0.332 0.000 0.911 4.2000 0.200 0.337 0.000 0.911 4.2667 0.200 0.342 0.000 0.911 4.3333 0.200 0.348 0.000 0.911 4.4000 0.200 0.353 0.000 0.911 4.4667 0.200 0.358 0.000 0.911 4.5333 0.200 0.364 0.000 0.911 4.6000 0.200 0.369 0.000 0.911 4.6667 0.200 0.375 0.000 0.911 4.7333 0.200 0.380 0.000 0.911 4.8000 0.200 0.385 0.000 0.911 4.8667 0.200 0.391 0.000 0.911 4.9333 0.200 0.396 0.000 0.911 5.0000 0.200 0.409 0.000 0.911 5.0667 0.200 0.423 0.273 0.911 5.1333 0.200 0.436 0.771 0.911 5.2000 0.200 0.450 1.404 0.911 5.2667 0.200 0.463 2.123 0.911 5.3333 0.200 0.476 2.882 0.911 5.4000 0.200 0.490 3.632 0.911 20833-Lower Infil 6/3/2020 1:33:43 PM Page 8 5.4667 0.200 0.503 4.326 0.911 5.5333 0.200 0.516 4.924 0.911 5.6000 0.200 0.530 5.401 0.911 5.6667 0.200 0.543 5.754 0.911 5.7333 0.200 0.557 6.014 0.911 5.8000 0.200 0.570 6.338 0.911 5.8667 0.200 0.583 6.597 0.911 5.9333 0.200 0.597 6.846 0.911 6.0000 0.200 0.610 7.086 0.911 20833-Lower Infil 6/3/2020 1:33:43 PM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:3.72 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.2 Total Impervious Area:3.52 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.110764 5 year 0.181496 10 year 0.226976 25 year 0.281076 50 year 0.318549 100 year 0.353551 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.127 0.000 1950 0.151 0.000 1951 0.242 0.000 1952 0.076 0.000 1953 0.061 0.000 1954 0.094 0.000 1955 0.151 0.000 1956 0.121 0.000 1957 0.098 0.000 1958 0.109 0.000 20833-Lower Infil 6/3/2020 1:46:54 PM Page 10 1959 0.093 0.000 1960 0.167 0.000 1961 0.092 0.000 1962 0.057 0.000 1963 0.078 0.000 1964 0.111 0.000 1965 0.074 0.000 1966 0.071 0.000 1967 0.170 0.000 1968 0.096 0.000 1969 0.093 0.000 1970 0.075 0.000 1971 0.084 0.000 1972 0.184 0.000 1973 0.081 0.000 1974 0.090 0.000 1975 0.126 0.000 1976 0.090 0.000 1977 0.013 0.000 1978 0.076 0.000 1979 0.046 0.000 1980 0.216 0.000 1981 0.068 0.000 1982 0.140 0.000 1983 0.120 0.000 1984 0.072 0.000 1985 0.043 0.000 1986 0.190 0.000 1987 0.168 0.000 1988 0.066 0.000 1989 0.044 0.000 1990 0.401 0.000 1991 0.213 0.000 1992 0.087 0.000 1993 0.085 0.000 1994 0.028 0.000 1995 0.122 0.000 1996 0.281 0.000 1997 0.217 0.000 1998 0.053 0.000 1999 0.238 0.000 2000 0.084 0.000 2001 0.015 0.000 2002 0.098 0.000 2003 0.146 0.000 2004 0.156 0.000 2005 0.116 0.000 2006 0.130 0.000 2007 0.303 0.000 2008 0.370 0.000 2009 0.172 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.4011 0.0000 2 0.3695 0.0000 3 0.3032 0.0000 20833-Lower Infil 6/3/2020 1:46:54 PM Page 11 4 0.2809 0.0000 5 0.2420 0.0000 6 0.2377 0.0000 7 0.2168 0.0000 8 0.2163 0.0000 9 0.2127 0.0000 10 0.1898 0.0000 11 0.1837 0.0000 12 0.1723 0.0000 13 0.1701 0.0000 14 0.1675 0.0000 15 0.1670 0.0000 16 0.1562 0.0000 17 0.1513 0.0000 18 0.1505 0.0000 19 0.1462 0.0000 20 0.1403 0.0000 21 0.1303 0.0000 22 0.1275 0.0000 23 0.1256 0.0000 24 0.1215 0.0000 25 0.1213 0.0000 26 0.1200 0.0000 27 0.1159 0.0000 28 0.1113 0.0000 29 0.1087 0.0000 30 0.0979 0.0000 31 0.0979 0.0000 32 0.0957 0.0000 33 0.0942 0.0000 34 0.0932 0.0000 35 0.0932 0.0000 36 0.0918 0.0000 37 0.0903 0.0000 38 0.0898 0.0000 39 0.0869 0.0000 40 0.0848 0.0000 41 0.0844 0.0000 42 0.0844 0.0000 43 0.0814 0.0000 44 0.0784 0.0000 45 0.0759 0.0000 46 0.0759 0.0000 47 0.0748 0.0000 48 0.0739 0.0000 49 0.0723 0.0000 50 0.0711 0.0000 51 0.0679 0.0000 52 0.0661 0.0000 53 0.0614 0.0000 54 0.0571 0.0000 55 0.0530 0.0000 56 0.0459 0.0000 57 0.0438 0.0000 58 0.0429 0.0000 59 0.0285 0.0000 60 0.0152 0.0000 61 0.0132 0.0000 20833-Lower Infil 6/3/2020 1:46:55 PM Page 13 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0554 17075 0 0 Pass 0.0580 15481 0 0 Pass 0.0607 14070 0 0 Pass 0.0634 12797 0 0 Pass 0.0660 11567 0 0 Pass 0.0687 10515 0 0 Pass 0.0713 9561 0 0 Pass 0.0740 8750 0 0 Pass 0.0766 8031 0 0 Pass 0.0793 7347 0 0 Pass 0.0820 6733 0 0 Pass 0.0846 6188 0 0 Pass 0.0873 5724 0 0 Pass 0.0899 5309 0 0 Pass 0.0926 4924 0 0 Pass 0.0953 4569 0 0 Pass 0.0979 4235 0 0 Pass 0.1006 3957 0 0 Pass 0.1032 3645 0 0 Pass 0.1059 3394 0 0 Pass 0.1085 3133 0 0 Pass 0.1112 2915 0 0 Pass 0.1139 2710 0 0 Pass 0.1165 2490 0 0 Pass 0.1192 2323 0 0 Pass 0.1218 2136 0 0 Pass 0.1245 1977 0 0 Pass 0.1272 1827 0 0 Pass 0.1298 1702 0 0 Pass 0.1325 1579 0 0 Pass 0.1351 1443 0 0 Pass 0.1378 1328 0 0 Pass 0.1404 1233 0 0 Pass 0.1431 1147 0 0 Pass 0.1458 1086 0 0 Pass 0.1484 1020 0 0 Pass 0.1511 949 0 0 Pass 0.1537 887 0 0 Pass 0.1564 827 0 0 Pass 0.1591 761 0 0 Pass 0.1617 725 0 0 Pass 0.1644 675 0 0 Pass 0.1670 623 0 0 Pass 0.1697 590 0 0 Pass 0.1723 549 0 0 Pass 0.1750 506 0 0 Pass 0.1777 469 0 0 Pass 0.1803 427 0 0 Pass 0.1830 388 0 0 Pass 0.1856 356 0 0 Pass 0.1883 328 0 0 Pass 0.1910 298 0 0 Pass 0.1936 270 0 0 Pass 20833-Lower Infil 6/3/2020 1:46:55 PM Page 14 0.1963 242 0 0 Pass 0.1989 218 0 0 Pass 0.2016 198 0 0 Pass 0.2042 174 0 0 Pass 0.2069 152 0 0 Pass 0.2096 130 0 0 Pass 0.2122 119 0 0 Pass 0.2149 104 0 0 Pass 0.2175 95 0 0 Pass 0.2202 84 0 0 Pass 0.2229 74 0 0 Pass 0.2255 69 0 0 Pass 0.2282 61 0 0 Pass 0.2308 53 0 0 Pass 0.2335 46 0 0 Pass 0.2361 39 0 0 Pass 0.2388 29 0 0 Pass 0.2415 25 0 0 Pass 0.2441 22 0 0 Pass 0.2468 20 0 0 Pass 0.2494 17 0 0 Pass 0.2521 14 0 0 Pass 0.2548 12 0 0 Pass 0.2574 8 0 0 Pass 0.2601 7 0 0 Pass 0.2627 7 0 0 Pass 0.2654 7 0 0 Pass 0.2680 6 0 0 Pass 0.2707 6 0 0 Pass 0.2734 6 0 0 Pass 0.2760 6 0 0 Pass 0.2787 6 0 0 Pass 0.2813 5 0 0 Pass 0.2840 5 0 0 Pass 0.2866 5 0 0 Pass 0.2893 5 0 0 Pass 0.2920 5 0 0 Pass 0.2946 5 0 0 Pass 0.2973 5 0 0 Pass 0.2999 4 0 0 Pass 0.3026 4 0 0 Pass 0.3053 3 0 0 Pass 0.3079 3 0 0 Pass 0.3106 3 0 0 Pass 0.3132 3 0 0 Pass 0.3159 3 0 0 Pass 0.3185 3 0 0 Pass 20833-Lower Infil 6/3/2020 1:46:55 PM Page 16 LID Report 20833-Lower Infil 6/3/2020 1:47:36 PM Page 18 Appendix Predeveloped Schematic 20833-Lower Infil 6/3/2020 1:48:57 PM Page 19 Mitigated Schematic 20833-Lower Infil 6/3/2020 1:50:17 PM Page 32 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. 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Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 20833.001.doc 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN The conveyance system sizing utilizes the SBUH method with a Manning’s “n” value of 0.012 for the pipe sizing calculations. Conveyance calculations will be provided within the final Technical Information Report. 6.0 SPECIAL REPORTS AND STUDIES 20833.001.doc 6.0 SPECIAL REPORTS AND STUDIES Special reports for this project include: · Revised Geotechnical Engineering Report prepared by GeoResources – May 28, 2020 · Revised Wetland and Fish and Wildlife Habitat Assessment and Buffer Averaging Plan by Soundview Consultants L.L.C. – May 22, 2020 Papé Kenworth NW – Federal Way Proposed Truck Sales and Maintenance Facility Revised Geotechnical Engineering Report May 28, 2020 Prepared by: GeoResources, LLC 4809 Pacific Highway E Fife, Washington 98424 (253) 896-1011 Prepared for: Papé Properties 355 Goodpasture Island Rd, Unit 300 Eugene, OR 97401 Attn: Mr. Quinn Closson Document ID: PapeKenworthNW.FederalWay.RG.rev01 Table of Contents INTRODUCTION ..................................................................................................................................................... 2 SCOPE ................................................................................................................................................................. 2 SITE CONDITIONS .................................................................................................................................................. 3 Surface Conditions .................................................................................................................................. 3 Site Soils ................................................................................................................................................... 4 Site Geology ............................................................................................................................................ 4 Subsurface Explorations .......................................................................................................................... 4 Subsurface Conditions ............................................................................................................................. 6 Infiltration Testing ................................................................................................................................... 8 Laboratory Testing .................................................................................................................................. 9 Groundwater Conditions ....................................................................................................................... 10 ENGINEERING CONCLUSIONS AND RECOMMENDATIONS ................................................................................. 11 Erosion Hazard Areas ............................................................................................................................ 11 Landslide Hazard Areas ......................................................................................................................... 12 Slope Stability Analysis .......................................................................................................................... 13 Recommended Buffer and Setback from Steep Slopes ........................................................................ 13 Seismic Design ....................................................................................................................................... 14 Foundation Support .............................................................................................................................. 15 Alternative Foundation Support ........................................................................................................... 16 Signal Pole Foundation Support ............................................................................................................ 17 Luminaire Foundation Support ............................................................................................................. 19 Floor Slab Support ................................................................................................................................. 19 Below Grade Walls ................................................................................................................................ 19 Retaining Structures .............................................................................................................................. 20 Below Grade Walls and Retaining Wall Drainage ................................................................................. 22 Temporary Excavations ......................................................................................................................... 23 Site Drainage ......................................................................................................................................... 24 Pavement Section Design ...................................................................................................................... 24 Stormwater Recommendations ............................................................................................................ 28 Detention Pond ..................................................................................................................................... 31 EARTHWORK RECOMMENDATIONS ................................................................................................................... 32 Site Preparation .................................................................................................................................... 32 Structural Fill ......................................................................................................................................... 33 Suitability of On-Site Materials as Structural Fill ................................................................................... 33 Erosion Control ...................................................................................................................................... 34 Wet Weather Earthwork Considerations .............................................................................................. 34 LIMITATIONS ....................................................................................................................................................... 35 Figures Figure 1: Site Location Map Figure 2: Site & Exploration Plan Figure 3: Site Topographic Survey Figure 4: Site Slopes Map Figure 5: NRCS Soils Map Figure 6: Geologic Map Figure 7: Typical Structural Setback Detail Figure 8: WA DNR Geologic Hazards Map Figure 9: Typical MSE Wall Detail Figure 10: Typical Wall Drainage and Backfill Detail Figure 11: IBC Keying and Benching Appendices Appendix A – Subsurface Explorations Appendix B – Laboratory Test Results Appendix C – Global Stability Analyses PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 1 INTRODUCTION This revised geotechnical engineering report summarizes our site observations, our subsurface explorations, geotechnical data review and engineering analyses, and provides geotechnical recommendations and design criteria for the proposed Papé-Kenworth Northwest truck sales and maintenance facility to be constructed on seven contiguous parcels (PN: 0921049- 028, -139, -140, -160, -187, -206, and -316) located at the northwest corner of South 320th Street and 32nd Avenue South in the Federal Way area of King County, Washington. We understand the parcels will be annexed to the City of Federal Way during the development; we have therefore addressed the City development codes in this report. The approximate site location is shown on the Site Location Map, included as Figure 1. Revisions to our previous report are bolded and italicized. Our original report was prepared on March 5, 2020. This revised report addresses the technical review comments from the City of Federal Way dated April 24, 2020. The City’s comments were provided to us by you on April 27, 2020. Our understanding of the project is based on our correspondences with you and members of the design team; our understanding of the City of Federal Way Critical Areas Ordinance and Development Codes; our review of the Site Plan prepared by H.G. Kimura Architect PLLC dated March 6, 2020 and the ALTA/NSPS Land Title Survey prepared by Barghausen Consulting Engineers dated December 7, 2019; and our past experience in the site area. We understand that the site consists of seven contiguous parcels. Portions of the site are currently developed, including three single-family residences in the southern portion of the site and a single-family residence, barn, and horse paddocks in the northern portion of the site. There is also an easement in the southern portion of the site for a Bonneville Power Administration transmission line, and a delineated wetland area in the western portion of the site. We further understand that you propose to develop the site with a new heavy truck dealership. Based on our project review, the development will include: An approximate 56,500 square-foot building that will house the showroom, office, shop and part storage and a detached 14,000 square-foot maintenance shop building. We anticipate the proposed buildings will be one or two story, wood or steel framed structures founded on shallow foundations; and that the maintenance facilities will include subgrade walls for maintenance pits. Associated parking areas and drive lanes consisting of asphalt concrete pavement (ACP) or Portland cement concrete (PCC). Typical underground utilities. Retaining walls to support fills in the northwestern portion of the project area. The currently proposed wall configuration consists of three tiered walls with heights of 8 to 14 feet. A stormwater detention pond in the southwest portion of the project area. Improvements along the 32nd Avenue South right-of-way, including traffic signal poles at the intersection of South 320th Street and 32nd Avenue South and luminaires. Because of the steep slopes in the vicinity of the site, we anticipate that the City of Federal Way will require a geotechnical engineering report to address the City’s Critical Areas Ordinance per PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 2 the Federal Way Revised Code (FWRC) Chapter 19.145. Our Site & Exploration Plan, attached as Figure 2, is based on the current proposed site plan dated March 6, 2020 and shows proposed improvements described above. SCOPE The purpose of our services was to evaluate the surface and subsurface conditions across the site as a basis for providing geotechnical recommendations and conclusions for the proposed development. Specifically, the scope of services for this project included the following: 1. Reviewing the available geologic, hydrogeologic, and geotechnical data for the site area; 2. Observing subsurface conditions across the site by monitoring the excavation of 16 test pits at selected locations across the project site; 3. Monitoring the drilling of three hollow-stem auger borings to depths of 21 feet in the northwest portion of the site using a track mounted drill rig, operated by a licensed driller and completing the borings as groundwater observation wells; 4. Monitoring groundwater levels within the wells periodically during one wet season (December 1 – April 30); 5. Monitoring the drilling of two hollow-stem auger borings to depths of 15 feet at the intersection of South 320th Street and 32nd Avenue South for signal pole and luminaire foundation design per WSDOT Geotechnical Design Manual; 6. Performing three small scale Pilot Infiltration Tests (PIT) at the approximate bottom elevation of the proposed infiltration system in accordance with the 2016 King County Surface Water Design Manual (KCSWDM), as amended by the City; 7. Describing surface and subsurface conditions, including soil type, depth to groundwater, and an estimate of seasonal high groundwater levels; 8. Addressing the appropriate criteria for geologic hazards per the current City of Federal Way Critical Areas Ordinance; 9. Providing geotechnical conclusions and recommendations regarding site grading activities including; site preparation, subgrade preparation, fill placement criteria, suitability of on-site soils for use as structural fill, temporary and permanent cut and fill slopes, drainage and erosion control measures; 10. Providing recommendations for seismic design parameters, including 2015 IBC soil profile type; 11. Providing geotechnical conclusions regarding foundations and floor slab support and design criteria, including bearing capacity and subgrade modulus as appropriate; 12. Providing recommendations regarding deep foundation elements, as necessary for signage or canopy foundations; 13. Providing recommendations regarding the traffic signal pole and luminaire foundations and design criteria; 14. Providing a standard duty and heavy duty hot mix asphalt (HMA) and a heavy duty Portland cement concrete (PCC) pavement section designs based on traffic data provided by you; 15. Providing our opinion about the feasibility of onsite infiltration including a design infiltration rate based on our infiltration testing per the 2016 KCSWDM; PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 3 16. Providing conclusions regarding suitable types of retaining walls and soil design parameters for the walls to be designed by others; 17. Performing slope stability analyses using computer program Slide 2018 by RocScience, in order to assess the global stability of the existing and proposed conditions at the site, including the proposed retaining walls and pond embankment; 18. Providing recommendations for erosion and sediment control during wet weather grading and construction; and, 19. Preparing this written Geotechnical Engineering Report summarizing our site observations and conclusions, and our geotechnical recommendations and design criteria, along with the supporting data. Our original scope of work was summarized in our Proposal for Geotechnical Engineering Services dated September 26, 2019. We received written authorization to proceed from you on September 27, 2019. Our scope for additional services, including in-situ infiltration testing, borings, and groundwater monitoring was summarized in our Proposal for Geotechnical Engineering Services dated December 17, 2019, and authorized by you on December 19, 2019. SITE CONDITIONS Surface Conditions As stated, the subject site consists of seven contiguous parcels located northwest of the intersection of South 320th Street and 32nd Avenue South in the Federal Way area of King County, within an area of existing commercial and residential development. The site is irregular in shape, measures approximately 625 to 815 feet wide (east to west) by 1,195 feet deep (north to south), and encompasses about 21.43 acres The site is bounded by 32nd Avenue South to the east, South 320th Street to the south, interstate I-5 to the west, and by undeveloped land to the north. The proposed development is shown on the Site & Exploration Plan, Figure 2, while the existing topography and site configuration is shown on the Site Topographic Survey, Figure 3. Areas of slopes between 15 to 39 percent and greater than 40 percent are shown on the Site Slopes Map, Figure 4. Based on review of the King County GIS website, the site can be divided into two topographic areas: eastern upland and western lowland. The eastern upland is level to gently sloping at 10 to 25 percent. The ground surface between the upland and lowland slopes down to the west, being steepest in the south with inclinations on the order of 35 to 42 percent with vertical relief of about 45 feet. The northern portion of this transitional slope is inclined down to the west at about 16 to 24 percent with vertical relief of 50 feet. The western lowland is generally level to gently sloping. From the toe of the transitional slope, the ground surface is inclined up to the west at about 10 percent or less. Total topographic relief across the site is on the order of 70 feet. The northern parcel is developed with an existing single-family residence, barn, and horse paddocks. Three of the parcels in the south and southeast portion of the site are developed with existing single-family residences. Two large transmission line towers are located in the south central portion of the site. The large center, southwest most, and southeast most parcels of the site are currently undeveloped. Vegetation across the undeveloped, western and central portions of the site consists of moderate to dense stands of deciduous and coniferous trees with a moderate understory of ferns, blackberries, and other native and invasive shrubs. The transmission line easement is well vegetated with shrubs and a dense understory of blackberries and other low-growing plants. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 4 Vegetation near the existing residences generally consists of grasses and typical residential landscaping. No evidence of erosion or slope movement was observed at the site at the time of our site visit. Site Soils The USDA Natural Resource Conservation Survey (NRCS) Web Soil Survey maps most of the site, including the areas of proposed development, as being underlain by Alderwood gravelly sandy loam (AgB, AgC, AgD). An area in the western portion of the site (approximately coincident with the wetland area) is mapped as being underlain by Seattle Muck (Sk). The Alderwood soils are typically derived from glacial till or outwash and form on slopes of 0 to 8 (AgB), 8 to 15 (AgC) and 15 to 30 (AgD) percent. These soils are listed as having a “slight” (AgB), “moderate,” (AgC), and “moderate to severe” (AgD) erosion hazard when exposed, and are included in hydrologic soils group B. Seattle Muck (Sk) is derived from grassy organic material, forms on level ground, does not have a listed erosion hazard, and is included in hydrologic soils group B/D, with the “D” designation typically for the deeper, unweathered more fine grained deposits. An excerpt from the NRCS soils map for the site area is included as Figure 5. Site Geology The Geologic Map of the Poverty Bay 7.5-Minute Quadrangle, Washington (Booth, Waldron, and Troost, 2003) maps most of the site and the adjacent areas as being underlain by glacial till (Qvt), while an area in the western portion of the site is mapped as underlain by wetland deposits (Qw). The glacial till soils were deposited during the Vashon Stade of the Frasier Glaciation. Glacial till generally consists of a heterogeneous mixture of gravel, sand, silt, and clay that was deposited at the base of the advancing continental ice mass, and was subsequently overridden. As such, it is considered to be over consolidated, and generally has high strength and low compressibility characteristics where undisturbed. Due to the compact nature and high fines content of glacial till, the potential for stormwater infiltration is low. Wetland deposits (Qw) are derived from peat and alluvium deposits and generally consist of pebbly sand or sandy silt that is moderately sorted with an organic component. These soils are considered to be normally consolidated. Soil deposits with high fines contents (including peat) generally have moderate to low strength characteristics, and may exhibit significant settlement over time. No areas of landslide deposits or mass wasting are mapped within the vicinity of the site. An excerpt of the referenced map is included as Figure 6. Subsurface Explorations On October 9, 2019, a field representative from GeoResources, LLC (GeoResources) visited the site, monitored the excavation of 13 test pits at the site (TP-1 through TP-13), logged the subsurface conditions encountered in each test pit, and obtained representative soil samples. On January 7, 2020, a representative from GeoResources returned to the site and monitored the drilling of five borings to depths of about 15 to 20 feet below the existing ground surface. On January 24, 2020, a representative from GeoResources returned to the site and performed in-situ infiltration testing and monitored the excavation of three additional test pits (TP-101 through TP-103). The test pits were excavated by track mounted excavation equipment operated by a licensed earthwork contractor. The borings were drilled by a licensed drilling contractor operating a truck-mounted drill rig working under subcontract to GeoResources. The specific number, locations, and depths of our explorations were selected based on the configuration of the proposed development, and were adjusted in the field based on consideration PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 5 for underground utilities, existing site conditions, and access limitations. Representative soil samples obtained from our explorations were placed in sealed plastic bags and then taken to our laboratory for further examination and testing as deemed necessary. During drilling, soil samples were obtained at 2½- and 5-foot depth intervals in accordance with Standard Penetration Test (SPT) as per the test method outlined by ASTM D: 1586. The SPT method consists of driving a standard 2-inch-diameter split-spoon sampler 18-inches into the soil with a 140-pound hammer. The number of blows required to drive the sampler through each 6-inch interval is counted, and the total number of blows struck during the final 12 inches is recorded as the Standard Penetration Resistance, or “SPT blow count”. The resulting Standard Penetration Resistance values indicate the relative density of granular soils and the relative consistency of cohesive soils. Soil densities presented on the test pit logs are based on the difficulty of excavation and our experience. The monitoring wells in borings B-1, B-2, and B-3 were installed by inserting closed-end, screened casing to the target depth. The borings not completed as observation wells (B-4 and B-5) were backfilled with bentonite chips and abandoned by the driller in accordance with the WAC 173- 160-381. The test pits were backfilled with the excavated soils and bucket tamped, but not otherwise compacted. The subsurface explorations completed as part of this evaluation indicate the subsurface conditions at specific locations only, as actual subsurface conditions can vary across the site. Furthermore, the nature and extent of such variation would not become evident until additional explorations are performed or until construction activities have begun. Based on our experience in the area and extent of prior explorations in the area, it is our opinion that the soils encountered in the explorations are generally representative of the soils at the site. Our test pit, boring, and PIT locations were estimated based on taping and pacing existing from locatable features. Surface elevations at exploration locations were estimated by interpolating between contours presented on the 2019 topographic survey. As such, our exploration locations and elevations should only be considered accurate to the degree implied by our measuring methods. The soils encountered were visually classified in accordance with the Unified Soil Classification System (USCS) and ASTM D: 2488. The USCS is included in Appendix A as Figure A-1. The approximate locations and numbers of our exploration are shown on the attached Site & Exploration Plan, Figure 2, while the descriptive logs of our explorations are included in Appendix A as Figures A-2 through A-11. Table 1, below, summarizes the approximate functional locations, surface elevations, and termination depths of our subsurface explorations. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 6 TABLE 1: APPROXIMATE LOCATIONS, ELEVATIONS, AND DEPTHS OF EXPLORATIONS Exploration Number Functional Location Surface Elevation1 (feet) Termination Depth (feet) Termination Elevation1 (feet) TP-1 TP-2 TP-3 TP-4 TP-5 TP-6 TP-7 TP-8 TP-9 TP-10 TP-11 TP-12 TP-13 NE portion of site North center portion of site NW of proposed shop West of proposed shop East of proposed shop Southern portion of proposed shop West of proposed showroom Proposed showroom East of proposed showroom West portion of site, N of overhead lines SW portion of site Proposed body shop East portion of site 457 446 440 470 476 481 468 478 484 476 480 486 484 10½ 9½ 9½ 10 7½ 9 10 9 6½ 9 8½ 8½ 9 446½ 436½ 430½ 460 468½ 472 458 469 477½ 467 471½ 477½ 475 TP-101 TP-102 TP-103 Proposed detention pond Proposed detention pond NW portion of site 471 469 446 12 9 9 459 460 437 PIT-1 PIT-2 PIT-3 Northwest portion of site Northwest portion of site Northern portion of site 460 442 452 6 6½ 10 454 435½ 442 B-1 / OW-1 B-2 / OW-2 B-3 / OW-3 B-4 B-5 Northern portion of site Northern portion of site Northwest portion of site Adjacent to 32nd Ave South Intersection of S 320th St & 32nd Ave S 450 452 451 484 474 21½ 20½ 21½ 15½ 15½ 428½ 431½ 429½ 468½ 458½ Notes: 1 = Elevation datum: NAVD 88 per December 2019 survey by Barghausen Consulting Engineers, Inc Subsurface Conditions At the locations explored, we encountered somewhat variable subsurface conditions that partially differed from the mapped stratigraphy. In general, we encountered surficial materials, including undocumented fill, overlying glacial till and advance outwash. Table 2, below, summarizes the approximate thicknesses, depths, and elevations of selected soil layers. Surficial Materials and Fill Where encountered, topsoil thicknesses at the locations explored generally ranged between about 6 and 15 inches. Test pits TP-1, TP-3, and TP-4, in the vicinity of the existing barn did not encounter a distinct topsoil layer. Based on our site reconnaissance and subsurface explorations, the area north and west of the existing barn, including a steep slope with vertical relief of about 12 feet, appears to consist of loose fill material including manure. This area includes borings B-1 and B-3, which encountered about 7 to 8 feet of loose silty sand that we interpret as fill. Test pit TP-102, in the vicinity of the proposed pond, PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 7 encountered about 3½ feet of silty sand with gravel and scattered construction debris underlying the topsoil, which we interpret as fill material. Weathered Soils Underlying the topsoil and fill, where encountered, we generally observed 1½ to 3 feet of tan to gray silty sand with variable amounts of gravel in a medium dense, moist condition. We interpret these soils to be consistent with weathered glacial till and weathered outwash soils. The weathered soils were not observed in test pit TP-102 and borings B-1 and B-5. Glacial Till Underlying the topsoil and weathered soils, 11 of 21 of our explorations in the south and east portions of the site (upland area) encountered gray silty sand with gravel in a dense to very dense, moist condition. We interpret these soils to be consistent with undisturbed glacial till. Test pits TP-5, TP-6, TP-9, TP-11, TP-12, and TP-13 and borings B-4 and B-5 encountered glacial till to the full depth explored, while test pits TP-2, TP-8, and TP-10 extended through the glacial till into the underlying advance outwash. A thin (2 to 3 feet thick), discontinuous glacial till layer appears to extend into the north central portion of the site in the vicinity of test pit TP-2 and PIT-3; this layer was not encountered in the northeast or northwest portions of the site. Advance Outwash Underlying the weathered soils in the north and west portion of the site and the glacial till in test pits TP-2, TP-8, and TP-10, our explorations encountered brown gravel soils in dense to very dense condition. We interpret these dense gravelly soils as consistent with advance outwash. The gravels had variable fines content, as shown in our laboratory test results below. The near surface soils in the vicinity of the existing barn are classified as silty gravel, with fines contents between 15 and 20 percent. The native gravels north (TP-2) and south (PIT-1) of the existing development had fines contents of 1.8 to 3.3 percent and the deeper gravel in the vicinity of the development (boring B- 2), had a fines contents of 8.7 percent. As stated above, surficial organic fill material was encountered in the vicinity of the existing barn and we therefore anticipate that fines have migrated to the underlying native gravel soils over time. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 8 TABLE 2: APPROXIMATE THICKNESS, DEPTHS, AND ELEVATION OF SOIL TYPES ENCOUNTERED IN EXPLORATIONS Exploration Number Thickness of Topsoil / Fill (feet) Thickness of Weathered Till/Outwash (feet) Depth to Glacial Till (feet) Elevation1 of Top of Glacial Till (feet) Depth to Advance Outwash (feet) Elevation1 of Top of Advance Outwash (feet) TP-1 TP-2 TP-3 TP-4 TP-5 TP-6 TP-7 TP-8 TP-9 TP-10 TP-11 TP-12 TP-13 NE 1¼ NE NE ½ ½ ½ ½ ¾ ½ ½ 1¼ 1 2 2¾ 2½ 2 2½ 2½ 1½ 2 1¾ 2½ 2½ 2¼ 2½ NE 4 NE NE 3 3 NE 2½ 2½ 3 3 3½ 3½ NE 442 NE NE 473 478 NE 475½ 481½ 473 477 482½ 480½ 2 5½ 2½ 2 NE NE 2 6 NE 8 NE NE NE 455 440½ 437½ 468 NE NE 466 472 NE 468 NE NE NE TP-101 TP-102 TP-103 ½ 4 ½ 3 NE 1½ NE NE NE NE NE NE 3½ 4 2 467½ 465 444 PIT-1 PIT-2 PIT-3 ½ ½ 2½ 1½ 2 2 NE NE 4½ NE NE 447½ 2 2½ 7½ 458 439½ 444½ B-1 B-2 B-3 B-4 B-5 8 NE 7 NE 1 NE 3 2 3 NE NE NE NE 3 1 NE NE NE 481 473 8 3 9 NE NE 442 449 442 NE NE Notes: 1 = Elevation datum: NAVD 88 per December 2019 survey by Barghausen Consulting Engineers, Inc NE = not encountered Infiltration Testing On January 24, 2020, a field representative from GeoResources performed three small scale pilot infiltration tests (PIT), in the northwest portion of the site in the general vicinity of the proposed infiltration facilities. Infiltration tests PIT-2 and PIT-3 were performed north and west, respectively, of the proposed facilities because of existing development. Infiltration testing was performed in general accordance with the 2016 KCSWDM, Reference 6A. The specific number, location, and depth of our PITs were adjusted in the field based on consideration for underground utilities, existing site conditions, site access limitations, water access limitations and encountered stratigraphy. The approximate locations of the infiltration tests are shown on the attached Site and Exploration Plan, Figure 2. The excavations for the PITs were excavated by a track-mounted excavator operated by a licensed contractor working for PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 9 GeoResources. The excavations were backfilled with the excavated soils and bucket tamped, but not otherwise compacted. TABLE 3: SMALL-SCALE PIT TEST RESULTS Infiltration Test Depth of Testing Surface (ft) Soil Type Surface Area (ft2) Measured Infiltration Rate (in/hr) PIT-1 2 SP 25.0 14.5 PIT-2 3 GM 27.5 6.25 PIT-3 8 GM 13.5 6.25 It should be noted that these measured short term infiltration rates only represent the encountered silty gravel and poorly graded sand with gravel soils. Recommendations regarding the stormwater infiltration are discussed and included in the “Infiltration Recommendations” section below. Laboratory Testing Geotechnical laboratory tests were performed on select samples retrieved from the test pit explorations to determine soil index and engineering properties encountered. Laboratory testing included visual soil classification per ASTM D: 2488, moisture content determinations per ASTM D: 2216, grain size analyses per ASTM D: 6913, modified proctor per ASTM D: 1557, and California bearing ratio (CBR) test per ASTM D: 1883 standard procedures. The CBR test and the corresponding modified proctor were performed by an independent analytical laboratory subcontracted by GeoResources. The results of the laboratory tests are included in Appendix B, and summarized below in Table 4, below. TABLE 4: LABORATORY TEST RESULTS FOR ON-SITE SOILS Sample Soil Type Lab ID Number Gravel Content (percent) Sand Content (percent) Silt/Clay Content (percent) D10 Ratio (mm) TP-2, S-1, 6-8’ TP-5, S-1, 5-7’ TP-8, S-2, 7-9‘ TP-13, S-3, 2-4’ Advance Outwash (GP) Glacial Till (SM) Advance Outwash (GP-GM) Weathered Till (SM) 098502 098506 098509 098514 48.8 24.6 49.7 16.7 47.9 42.8 39.8 35.6 3.3 32.6 10.5 47.7 0.2772 <0.074 <0.074 <0.074 B-2, S-1, 5’ B-2, S-2, 20’ Advance Outwash (GM) Advance Outwash (GW-GM) 099001 099004 43.8 49.5 41.2 41.8 15.0 8.7 <0.074 0.1047 PIT-1, 3’ PIT-2, 3’ Advance Outwash (SP) Advance Outwash (GM) 099110 099111 46.2 49.6 52.0 30.5 1.8 19.9 0.2920 <0.074 PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 10 Groundwater Conditions Mottling and orange iron-oxide staining was observed as shallow as about 1½ to 2½ feet below the existing ground surface in the test pits excavated in the south and east portions of the site that are underlain by glacial till. These characteristics are generally indicative of a seasonal perched groundwater table, which generally develops when a higher permeability soil is underlain by a lower permeability soil such as glacial till. TABLE 5: APPROXIMATE DEPTHS AND ELEVATIONS OF GROUNDWATER ENCOUNTERED IN EXPLORATIONS Exploration Number Depth to Groundwater (feet) Elevation of Groundwater1 (feet) Date Observed TP-1 NE NE October 9, 2019 (ATE) TP-2 NE NE October 9, 2019 (ATE) TP-3 3½ 436½ October 9, 2019 (ATE) TP-4 NE NE October 9, 2019 (ATE) TP-5 NE NE October 9, 2019 (ATE) TP-6 NE NE October 9, 2019 (ATE) TP-7 NE NE October 9, 2019 (ATE) TP-8 NE NE October 9, 2019 (ATE) TP-9 NE NE October 9, 2019 (ATE) TP-10 NE NE October 9, 2019 (ATE) TP-11 NE NE October 9, 2019 (ATE) TP-12 NE NE October 9, 2019 (ATE) TP-13 NE NE October 9, 2019 (ATE) TP-101 7½ 463½ January 24, 2020 (ATE) TP-102 8½ 460½ January 24, 2020 (ATE) TP-103 8 438 January 24, 2020 (ATE) B-1 / OW-1 NE 14 15½ NE 436 434½ January 7, 2020 (ATD) January 24, 2020 March 5, 2020 B-2 / OW-2 NE 15 17½ NE 437 434½ January 7, 2020 (ATD) January 24, 2020 March 5, 2020 B-3 / OW-3 18 14½ 19 433 436½ 432 January 7, 2020 (ATD) January 24, 2020 March 5, 2020 B-4 NE NE January 7, 2020 (ATD) B-5 NE NE January 7, 2020 (ATD) 1 = Elevation datum: NAVD 88 per December 2019 survey by Barghausen Consulting Engineers, Inc ATE = At the time of exploration ATD = At the time of drilling PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 11 No mottling was observed in the northwest portion of the development underlain by advance outwash soils. However, groundwater seepage was observed in the north and west portions of the site in our test pit explorations and standing groundwater was observed in our monitoring wells, as summarized in Table 5 above. In the northwest portion of the site, a groundwater “peak” was observed in our observation wells at approximately elevation 436 to 438 feet during our January 24, 2020 site visit. In the southwest portion of the site, in the vicinity of the proposed pond, groundwater seepage was observed at approximately elevation 460 to 463 feet. Because we did not observe any seepage along the face of the site slopes, we anticipate the groundwater surface in the western portion of the site generally parallels the slope face until reaching the free water surface of the wetlands area at the toe of the slope. The surface water observed in the wetland at the time of our January 24, 2020 site visit was at approximately elevation 418 feet. Based on a review of nearby borings by others and our understanding of regional stratigraphy, we anticipate the advance outwash is underlain at depth by older pre-Vashon glacial till deposits and that the observed groundwater is perched within the more permeable outwash soils. We anticipate fluctuations in the local groundwater levels will occur in response to precipitation patterns, off-site construction activities, and site utilization. ENGINEERING CONCLUSIONS AND RECOMMENDATIONS Based on the results of our data review, site reconnaissance, subsurface explorations and our experience in the area, it is our opinion that the construction of the proposed commercial development at the site is feasible from a geotechnical standpoint. Provided the geotechnical recommendations contained in this report are included in the project plans and specifications, the development will have minimal impact on the steeper slope in the western portion of the site. This report satisfies the requirements of the FWRC 19.145.250 for a geotechnical engineering report for potential geologically hazardous areas. Erosion Hazard Areas The FWRC, Chapter 19.05.070.G(1) defines erosion hazard areas as “those areas identified by the U.S. Department of Agriculture’s (USDA) Natural Resource Conservation Service (NRCS) as having a moderate to severe or severe to very severe rill and inter-rill erosion hazard due to natural agents such as wind, rain, splash, frost action or stream flow; those areas containing the following group of soils when they occur on slopes of 15 percent or greater: Alderwood-Kitsap (“AkF”), Alderwood gravelly sandy loam (“AgD”), Kitsap silt loam (“KpD”), Everett (“EvD”), and Indianola (“InD”); and those areas impacted by shore land and/or stream bank erosion” As previously stated, the soils mapped in the areas of proposed development are AgB, AgC, and AgD which have a slight, moderate, and moderate to severe erosion hazards when exposed, respectively. The AgD soil type is mapped underlying the northwest corner of the proposed development and underlying the more steeply sloping portion of the site to the west of the proposed development. In our opinion the potential erosion hazard can be mitigated by installing conventional construction BMPs prior to beginning construction. Properly installed and maintained BMPs should provide adequate erosion control for the disturbed areas of the site. It is critical that the installed erosion control measures be monitored and maintained, and if necessary modified based on changing site conditions. In the event that the site is not worked for 7 days or more, the disturbed areas should be adequately erosion protected and maintained in the event of a significant storm event. This may include the use of plastic sheeting or mulch. Erosion control should PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 12 specifically include the installation of silt fencing along the downslope and side slopes of the active construction area. Straw wattles and berms may also be necessary. We have not been provided with a copy of the proposed Temporary Erosion and Sediment Control (TESC) plan at this time. However, provided standard BMP’s are installed prior to beginning construction, the potential for erosion or sediment leaving the site should be minimal. Landslide Hazard Areas The FWRC, Chapter 19.05.070.G(2) defines landslide hazard areas as “those areas potentially subject to episodic downslope movement of a mass of soil or rock including but not limited to the following areas.” These are typically characterized as having the following indicators: a. Any area with a combination of: i. Slopes greater than 15 percent; ii. Permeable sediment overlying a relatively impermeable sediment or bedrock; iii. Springs or groundwater seeps. b. Any area which has shown movement during the Holocene epoch, from 10,000 years ago to the present, or which is underlain by mass wastage debris of that epoch. c. Any area potentially unstable as a result of rapid stream incision, stream bank erosion or undercutting by wave action. d. Any area located in a ravine or on an active alluvial fan, presently or potentially subject to inundation by debris flows or flooding. e. Those areas mapped as Class U (unstable), UOS (unstable old slides), and URS (unstable recent slides) by the Department of Ecology’s Coastal Zone Atlas. f. Areas designated as quaternary slumps, earthflows, mudflows, lahars, or landslides on maps published by the U.S. Geological Survey or Washington State Department of Natural Resources. g. Slopes having gradients greater than 80 percent subject to rockfall during seismic shaking h. Any area with a slope of 40 percent or steeper and with a vertical relief of 10 or more feet except areas composed of consolidated rock. A slope is delineated by establishing its toe and top and is measured by averaging the inclination over at least 10 feet of vertical relief. The site has slopes steeper than 15 percent, but no areas of permeable soils overlying relatively impermeable soil are mapped or were encountered at the site. No areas of mapped landslide debris or activity were noted on the published USGS geologic map. No streams are mapped in the vicinity of the site and the site is not located along a shoreline. No areas of alluvial fans are mapped nor were any alluvial fans noted in the vicinity of the site at the time of our past site visits. The site is not within the area mapped by the Coastal Atlas; given the slope angles and mapped geology, we would anticipate the eastern portion of the site would be mapped as stable. No areas of mass wasting or landslide deposits are mapped at the site by the geologic map or the Washington DNR Geologic Information Portal. The site slopes are not steeper than 80 percent and are not subject to rock fall during seismic shaking. Slopes steeper than 40 percent with a vertical relief of up to 28 feet are identified on the site survey in the southwest portion of the site. This area is to the west of the southern portion of the proposed project area. Based on the 2019 site survey, the site has one of the above indicators (slopes steeper than 40 percent with 10 feet or more of vertical relief) and therefore this portion of the project site meets PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 13 the technical definition of landslide hazard area. We did not observe evidence of active or ongoing movement or slope instability at the time of our site visit. No grading is planned on this portion of the site. Additionally, our global stability analysis of the slope (described in the “Slope Stability Analysis” section below) indicates the slope is in a stable condition with factors of safety for static and dynamic conditions of 2.2 and 1.2, respectively. Based on the results of our slope stability analyses, the existing slope conditions meet or exceed the minimum factors of safety required by the City of Federal Way. Slope Stability Analysis We performed global stability analyses for static and seismic conditions of both the existing and proposed slope geometries using cross sections A-A’ and B-B’, as shown on Figure 2. These cross sections were selected as the most critical sections given the height and steepness of the slopes, and the proximity of the proposed development. Profile A-A’ was selected based on the location of the proposed detention pond and profile B-B’ was selected given the anticipated height of fill required. The slope stability results for the existing and proposed configurations are included as Appendix C. Seismic loading of 0.26g was added to the stability models based on the peak ground acceleration with a 2% probability of exceedance within a 50-year period. We used the computer program SLIDE 2018, from RocScience, to perform the slope stability analyses. The computer program SLIDE uses a number of methods to estimate the factor of safety (FS) of the stability of a slope by analyzing the shear and normal forces acting on a series of vertical “slices” that comprise a failure surface. Each vertical slice is treated as a rigid body; therefore, the forces and/or moments acting on each slice are assumed to satisfy static equilibrium (i.e., a limit equilibrium analysis). The FS is defined as the ratio of the forces available to resist movement to the forces of the driving mass. A FS of 1.0 means that the driving and resisting forces are equal; an FS less than 1.0 indicates that the driving forces are greater than the resisting forces (indicating failure). We used the Generalized Limit Equilibrium method using the Morgenstern-Price analysis, which satisfies both moment and force equilibrium, to search for the location of the most critical failure surfaces and their corresponding FS. The most critical surfaces are those with the lowest FS for a given loading condition, and are therefore the most likely to move. Based on our analyses, the existing and proposed configurations meet static and dynamic global stability criteria, which requires minimum factors of safety of 1.5 and 1.1, respectively. Additional discussion of the proposed retaining wall and detention pond configurations is included in the “Retaining Walls” and “Detention Pond” sections below. Recommended Buffer and Setback from Steep Slopes Buffers and setbacks are typically used to protect critical areas from disturbance and also to protect the proposed development from damage due to the potential hazard. The following discussions regarding critical area buffers and structure setbacks are based on FWRC Chapter 19.145.230 and IBC 1808.7, respectively. Buffers typically consist of an undisturbed area of native vegetation, retained or established, that extend from the edge of the critical area or hazard. The width of the buffer should be a reflection of the potential hazard and associated risks. Buffer widths are generally measured from the edge of the critical area being protected, in this case top of slope. Per FWRC 19.145.230, landslide hazard areas should have a standard buffer of 50-feet, which may be reduced when a qualified professional demonstrates that the improvements will not increase the slide hazard. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 14 The area with slopes steeper than 40 percent and more than 10 feet of relief has been identified on Figure 2. Based on our review of the provided preliminary site plan, we understand that no structures are currently proposed within 50 feet of the top of th is steep slope. However, the base of the proposed detention pond embankment is approximately 15 to 30 feet from the top of the steep slope. We evaluated the global stability of the existing and proposed site conditions as described above. Based on our stability analyses, it is our opinion that the proposed improvements will not create an increased slide hazard and therefore the standard 50-foot buffer required by the City of Federal Way can be reduced per FWRC 19.145.230.(4). We recommend the buffer be reduced to 15 feet to correspond to the required IBC setback as described below. A setback is the minimum distance a structure can be placed near a critical area or hazard. In general, setback distances are greater than buffer widths. The 2015 International Building Code (IBC), Section 1808.7 requires a building setback from slopes that are steeper than 3H:1V (Horizontal: Vertical) or 33 percent with greater than 10 feet in vertical height, unless evaluated and reduced and/or a structural setback is provided by a licensed geotechnical engineer. The setback distance is calculated based on the vertical height of the slope. The typical 2015 IBC setback from the top of the slope equals one third the height of the slope or 40 feet, whichever is less, while a setback from the toe of the slope equals one half the height of the slope or 15 feet, whichever is less. As stated above, the portion of the ground surface in the southwest portion of the site that slopes at more than 33 percent has a vertical height of up to 40 feet. Per the 2015 IBC, the minimum building setback from the top of the slope should be 14 feet. As currently shown on the proposed site plan, used as basis for Figure 2, the proposed retaining walls, parking areas, and buildings will meet or exceed this setback distance. Where the setback from the top of the slope cannot be met, a structural setback may be used. A structural setback is created by deepening the foundation elements so that, when measured horizontally from the font of the foundation to the face of the slope, the top of slope setback discussed above is met. We have provided recommendations for deepened foundations in the “Foundation Support” section of this report. A typical structural setback diagram is included as Figure 7. Seismic Design Based on our observations and the subsurface units mapped at the site, we interpret the structural site conditions to correspond to a seismic Site Class “C” in accordance with the 2015 IBC (International Building Code) documents and ASCE 7-10 Chapter 20 Table 20.3-1. This is based on the SPT (Standard Penetration Test) blow counts recorded during our borings and the anticipated range of SPT (Standard Penetration Test) blow counts for the soil types observed during test pit excavation. These conditions were assumed to be representative for the subsurface conditions for the project site in general. For design of seismic structures using the IBC 2015, mapped short-period and 1-second period spectral accelerations, SS and S1, respectively, are required. SS and S1 are for a maximum considered earthquake, which corresponds to ground motions with a 2 percent probability of exceedance in 50 years or about a 2,500-year return period (with a deterministic maximum cap in some regions). The U.S. Geological Survey (USGS) completed probabilistic seismic hazard analyses (PSHA) for the entire country in November 1996, which were updated and republished in 2002 and 2008. We used the ATC Hazard by Location website to estimate seismic design parameters at the site. Table 6, below, summarizes the recommended design parameters. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 15 TABLE 6: 2015 IBC PARAMETERS FOR DESIGN OF SEISMIC STRUCTURES Spectral Response Acceleration (SRA) and Site Coefficients Short Period 1 Second Period Mapped SRA Ss = 1.289 S1 = 0.493 Site Coefficients (Site Class C) Fa = 1.000 Fv = 1.307 Maximum Considered Earthquake SRA SMS = 1.289 SM1 = 0.645 Design SRA SDS = 0.859 SD1 = 0.430 Peak Ground Acceleration The mapped peak ground acceleration (PGA) for this site is 0.522g. To account for site class, the PGA is multiplied by a site amplification factor (FPGA) of 1.000. The resulting site modified peak ground acceleration (PGAM) is 0.522g. In general, estimating seismic earth pressures (kh) by the Mononobe-Okabe method or seismic inputs for slope stability analysis are taken as 30 to 50 percent of the PGAM, or 0.16g to 0.26g. Earthquake-Induced Geologic Hazards Earthquake-induced geologic hazards may include liquefaction, lateral spreading, slope instability, and ground surface fault rupture. According to the Department of Natural Resources Geologic Hazards Map, Figure 8, the site is located within the mapped Tacoma Fault Zone. However, no faults are mapped within 300 feet of the subject site. No evidence of ground fault rupture was observed in the subsurface exploration or our site reconnaissance. In our opinion, the proposed development has no greater risk for ground fault rupture than other structures located in this portion of the Tacoma Fault Zone. Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in water pressure. The increase in pore water pressure is induced by vibrations. Liquefaction mainly affects geologically recent deposits of loose, fine-grained sands that are below the groundwater table. Based on the dense nature of the glacial till and advance outwash soils observed on the site, it is our opinion that the risk for liquefaction to occur at this site during an earthquake is negligible. Provided the design criteria listed below are followed, the proposed development should have no greater risk of seismic damage than other appropriately designed structures in the Puget Sound area. Foundation Support As stated, we anticipate the proposed structures will be founded on conventional shallow foundations, while deep foundations such as pin piles or helical anchors may be necessary to provide additional uplift capacity for proposed signage or canopies. Design criteria and recommendations for conventional shallow foundations are included in this section. Design criteria and recommendations for deepened foundations are included in the “Alternative Foundation Support” section below. We recommend that spread footings for any new structures be founded on the native glacial soils or on structural fill that extends to suitable native soils. The soil at the base of the footing PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 16 excavations should be disturbed as little as possible. All loose, soft or unsuitable material should be removed or recompacted per the “Structural Fill” section of this report. We recommend a minimum width of 24 inches for isolated footings and at least 18 inches for continuous wall footings. All footing elements should be embedded at least 18 inches below grade for frost protection. Footings founded on the properly placed and compacted structural fill or the shallow weathered glacial soils can be designed using an allowable soil bearing capacity of 2,500 psf (pounds per square foot) for combined dead and long-term live loads. Footings founded on the dense glacial till or advance outwash can be designed using an allowable soil bearing capacity of 4,000 psf. The weight of the footing and any overlying backfill may be neglected. The allowable bearing value may be increased by one-third for transient loads such as those induced by seismic events or wind loads. Lateral loads may be resisted by friction on the base of footings and floor slabs and as passive pressure on the sides of footings. We recommend that an allowable coefficient of friction of 0.35 be used to calculate friction between the concrete and the underlying soil. Passive pressure may be determined using an allowable equivalent fluid density of 350 pcf (pounds per cubic foot). Passive resistance from soil should be ignored in the upper 1 foot. Factors of safety have been applied to these values. We estimate that settlements of footings designed and constructed as recommended will be less than 1-inch, for the anticipated load conditions, with differential settlements between comparably loaded footings of ½-inch or less. Most of the settlements should occur essentially as loads are being applied. However, disturbance of the foundation subgrade during construction could result in larger settlements than predicted. We recommend that all foundations be provided with footing drains in accordance with the 2015 IBC, Section 1805.4.2. We also recommend that a GeoResources representative evaluate the condition of the exposed subgrade soils prior to setting the forms and installation of the reinforcing steel. Alternative Foundation Support Since uplift capacities for canopies or signs may require greater resistance than can be provided by conventional shallow foundations, the use of deep foundations such as helical anchors or reinforced concrete piers may be more appropriate to provide additional uplift capacities while minimizing the size of the perimeter foundation. Helical Anchors Helical anchors (such as the proprietary systems offered by AB Chance and Atlas Systems) typically consist of a square or circular shaft (1.5-inch square is typical) with and 8 to 12-inch diameter helix located at the leading edge. The helix is rotated and is advanced into the soil like a screw, similar to soil augers commonly used for drilling. Depending on the capacity required, one or more helices may be located along the shaft, typically at about 3-foot intervals. The smallest helix is the one at the tip of the anchor, with the sizes becoming progressively large at shallower depths. Helical anchors are screwed into the ground with rotary-type torque motor until refusal conditions are met. Refusal is typically defined as achieving a specific torque that corresponds to a specific compressive capacity based on soil conditions and installation equipment used. Anchors should be spaced a minimum distance of three times the largest helix diameter measured from the edges of the helices to avoid group effects. The lateral capacity of the battered piling may be taken as the horizontal vector of the axial pile capacity. The Chance anchor system is a proprietary system which utilizes helical anchors affixed to a square steel shaft. The uplift capacity PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 17 of the anchor is related to the torsion resistance encountered as the anchor is installed. Torque monitoring of individual anchors is completed as the anchors are installed using a shear pin that shears once the design load (torque) is achieved. The number, size, and spacing of helix plates required to achieve the design loads should be determined by the anchor contractor and manufacturer using the attached subsurface exploration logs. We recommend that load testing should be performed in accordance with the Quick Load Test Method, ASTM D: 1143. Reinforced Concrete Piers Alternatively, uplift capacity could be provided by using steel-reinforced concrete piers. Because of the density of the soils, drilled or augercast concrete piles may be easier to install to the required depth than helical anchors or driven steel pin piles. We typically recommend that the piers be a minimum of 12-inches in diameter and be structurally connected to the footing elements. Where the 12-inch diameter piers bear on dense granular soil, we recommend a preliminary end bearing value of 4,000 pounds per square foot (psf) and a skin friction value of 1,000 plf. These values are for piles installed by open-hole techniques. Uplift capacity is generally taken as about 1/2 to 2/3 of allowable pile skin friction resistance (about 500 to 650 plf). Piers of this capacity are generally acceptable for lightly loaded structures. The concrete piers are usually short and are analyzed as rigid bodies with respect to lateral design. The short concrete piers are usually installed with a “highway” auger or similar truck mounted drill rig. On steeply sloping sites, or for deeper piers, a larger crane type mounted drill rig is required. This may also require a large bench excavation in order to provide the drill rig access to the pier locations. This recommended capacity is based on a minimum penetration equal to a minimum of 5 feet into suitable bearing soils that were encountered at about 2 to 4 feet below the existing ground surface. Minimum embedment depths will depend on finish floor elevations. Once the site plan is finalized, we can review minimum embedment depths. The piers are typically placed on 4 to 6 foot centers starting at the corners of the individual shallow foundation elements. Piers with center-to-center spacing less than 3 pile diameters may need to account for group effects. Signal Pole Foundation Support We understand that existing signal poles at the intersection of South 320th Street and 32nd Avenue South may be relocated as part of the proposed development. Standard foundation depths range from 6 to 20 feet, depending on the foundation type, the pole class, resultant horizontal tension, and the soil conditions. Table 7 below presents the recommended minimum foundation depths for various factors, based on WSDOT design criteria, for Type IV and V strain pole foundations. Because of the proximity of the anticipated pole location to an existing slope, the foundation depth may need to be extended. For slopes flatter than 3H:1V no adjustment is necessary. For poles located on slopes inclined at 3H:1V, the foundations depths should be extended 0.5B, where “B” is the foundation diameter. For poles located on slopes inclined at 1.5H:1V the foundations depths should be extended 1.0B. Interpolation of foundation depths between indicated slope inclinations is permitted. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 18 TABLE 7: RECOMMENDED MINIMUM DRILLED PIER DEPTHS FOR SIGNAL POLE FOUNDATIONS Allowable Lateral Bearing Pressure Drilled Pier Diameter “B” (feet) Pole Class – Resultant Horizontal Tension1 (lbs) 1900 2700 3700 4800 5600 6300 7200 Drilled Pier Depth (feet) on Level Ground2 1,000 psf to 1,500 psf 3 4 11 10 13 11 15 13 16 15 18 15 19 16 20 18 1,500 psf to 2,500 psf 3 4 9 8 11 9 12 10 14 12 15 13 15 13 16 14 >2,500 psf 3 4 7 6 8 7 9 8 10 9 11 10 12 10 13 11 Corrugated Metal Pipe Depth (feet) on Level Ground2 1,000 psf to 1,500 psf 3 4 11 10 13 11 15 13 16 15 18 15 19 16 20 18 1,500 psf to 2,500 psf 3 4 9 8 11 9 12 10 14 12 15 13 15 13 16 14 > 2,500 psf 3 4 7 6 8 7 9 8 10 9 11 10 12 10 13 10 Ref: Design Manual – Type IV and V Strain Pole Traffic Signal Foundation, Standard Plan J-27.10-01 Notes: 1 For actual resultant horizontal tension factors between the design values shown, use the next higher value. 2 For 2H:1V ground slopes add 0.5B to depth; For 1.5H:1V ground slopes add 1.0B to depth. Interpolation between these values is permitted. Signal pole foundations should not be placed on slopes steeper than 1.5H:1V We understand the signal pole northwest of the intersection will be located in the general vicinity of boring B-5. At the location of boring B-5, very dense glacial till with blow counts greater than 50 blows per foot (bpf) was encountered at about 2 feet below the ground surface (approximately elevation 472 feet). The very dense glacial till was mantled by dense crushed surfacing rock in the existing driveway. Correlations between SPT blow count and lateral bearing pressure are provided in Table 17-2 of the WSDOT Geotechnical Design Manual (Foundation Design for Signals Signs, Noise Barriers, Culverts, and Buildings, M 46-03.8, dated October 2013). Using the blow count data from boring B-5, all foundation embedment depths greater than 5 feet will have an allowable lateral bearing pressure in excess of 4,500 psf. Therefore, in our opinion, the signal pole foundation may be sized using Table 7, above, using the row of design values for allowable lateral bearing pressure greater than 2,500 psf. Once the signal pole class and location for proposed signal poles have been selected, we can provide additional comments on the required minimum embedment depth. Based on our explorations, we anticipate that the foundation holes can be drilled with a conventional auger. The drilling or excavation contractor should realize that differing soil conditions might be encountered at the specific pole locations. Because of the proximity of existing underground utilities, careful utility locating will be required before the foundations are installed. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 19 Luminaire Foundation Support We understand that luminaires are proposed along the 32nd Avenue South right-of-way as part of the proposed development. The WSDOT standard design for luminaire foundations is shown on WSDOT Standard Plan J-28.30-03. Foundation Type A has a minimum embedment depth of 4.5 feet on ground surfaces inclined at 4H:1V or less and a minimum allowable lateral bearing pressure of 2,000 psf. Foundation Type B has a minimum embedment depth of 8 feet on slopes inclined steeper than 4H:1V, but not exceeding 2H:1V, and an allowable lateral bearing capacity of 1,500 psf. Luminaires founded in the dense to very dense glacial till encountered in borings B-4 and B- 5 may be designed using Foundation Type A or B. All loose, soft or unsuitable material should be removed or recompacted per the “Structural Fill” section of this report. Luminaires founded in structural fill placed as described in the “Structural Fill” section may also be designed using Foundation Type A or B. We understand that only minor amounts of grading are proposed along the 32nd Avenue South right-of-way and therefore anticipate the proposed luminaires will be founded in native glacial till soils. Floor Slab Support We anticipate that the proposed buildings may include slab-on-grade floors that should be supported on the native soils or on structural fill prepared as described below. Although not encountered in our explorations in the vicinity of the proposed buildings, any areas of old fill material should be evaluated during grading activity for suitability of structural support. Areas of significant organic debris should be removed as described in accordance with the “Site Preparation” section of this report. We recommend that floor slabs be directly underlain by a minimum 4-inch thick pea gravel or clean crushed rock with less than 2 percent fines. This layer should be placed in one lift and compacted to an unyielding condition. A synthetic vapor retarder is recommended to control moisture migration through the slabs. This is of particular importance where th e slab is underlain by silty till soils or where moisture migration through the slab is an issue, such as where adhesives are used to anchor carpet or tile to the slab. A subgrade modulus of 250 pci (pounds per cubic inch) may be used for subgrades prepared as recommended. We estimate that settlement of the floor slabs designed and constructed as recommended, will be ½ inch or less over a span of 50 feet. Below Grade Walls We do not expect the buildings will have basements, but subgrade walls could be constructed in association with maintenance pits. The lateral pressures acting on below grade walls will depend upon the nature and density of the soil behind the walls. It is also dependent upon the presence or absence of hydrostatic pressure. If the walls are backfilled with granular well-drained soil, the design active pressure may be taken as 35 pounds per cubic foot (pcf) (equivalent fluid density). For subgrade walls that are restrained from deflection, an at-rest pressure of 55 pcf may be used. These design values assume a level backslope and drained conditions as described below. Where required by code, a seismic surcharge of 10H is recommended for active conditions, calculated using the Mononobe-Okabe method. This surcharge is in addition to the static lateral earth pressure and should be assumed to have resultant at 2/3H, and assumes the wall will be backfilled with adequately compacted structural fill. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 20 Lateral loads may be resisted by friction on the base of wall footings and as passive pressure on the sides of footings and the embedded portion of the wall, as described in the “Foundation Support” section. Retaining Structures Retaining walls are proposed to support fills along the western and northwest portion of the project area and provide up to 41 feet of grade separation. Per the FWRC 19.120.120, walls for commercial developments are limited to six feet in height, and rockeries and retaining walls visible from a public right-of-way shall be composed of rock, brick, or other textured/patterned wall styles as approved by the City. We understand you are requesting a deviation to construct retaining walls up to about 14 feet in height. The proposed configuration provides up to 41 feet of grade separation and consists of three tiered walls with individual maximum heights of 10 to 14 feet that are horizontally separated by terraces sloping at up to 3H:1V. While not currently proposed, we anticipate additional shorter retaining walls may be required to support cuts in the southeastern portion of the project area. Where the proposed parking lot will be within 1H:1V from the base of the proposed retaining walls, we recommend a live load surcharge of 250 psf be applied to model traffic loading. As proposed, the building is sufficient setback so that it will not impose a surcharge on the walls. We recommend the following geotechnical design parameters be used for the design of retaining walls: TABLE 8: RECOMMENDED SOIL PROPERTIES OF ON-SITE SOILS FOR WALL DESIGN Soil Type Moist Unit Weight (pcf) Cohesion1 (psf) Phi (degrees) Equivalent Fluid Pressure (pcf) Weathered Till/Outwash (medium dense) Gravelly Advance Outwash (dense) Glacial Till (dense) Structural Fill (Common Borrow) 125 135 138 130 0 0 500 0 34 42 38 35 35 27 33 35 Notes: 1Cohesion should only be used to model foundation soil, not retained soil Mechanically Stabilized Earth Walls Mechanically stabilized earth (MSE) walls are constructed using compacted soil with layers of reinforcing material, such as geosynthetics or steel strips, that extend behind the wall face to create a reinforced soil mass. Detailed wall design should be performed by the wall designer, including internal and external stability, sliding resistance, and required reinforcement layout and properties. Wall backfill should consist of structural fill and should be compacted to 95% of the maximum dry density (MDD) as determined by the Modified Proctor (ASTM D: 1557). The soil drainage zone within 12- to 18-inches of the wall should be compacted to approximately 90 percent of the MDD. Typical facings for MSE walls with geogrid or geotextile reinforcement are small modular concrete blocks (such as Cornerstone, Keystone, and others) or large modular concrete blocks (such as Redi-rock, Ultrawall, and others). As stated above, rockeries may be considered for use as a decorative facing in front of wrapped face geosynthetic MSE walls. In our opinion, MSE walls with steel reinforcement (or gabion style wall) such as the Hilfiker wall systems, would also be feasible PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 21 from a geotechnical perspective, however the wall facing may not meet the City style requirements described above. Grid lengths for wall under 6 feet in height are typically on the order of 0.7H, where H is the total height of the wall. Grid lengths for walls over 6 feet are typically on the order of 1.1H. Greater lengths may be required for tiered wall configurations when the upper wall surcharges the lower wall, typically when the upper wall is located within 1H:1V from the base of the lower wall. Our recommended grid lengths for the proposed configuration are described below in the ”Preliminary Global Stability Analysis” section. A typical detail for a tiered MSE retaining wall constructed using small concrete block facing and geogrid reinforcement is included as Figure 9. Rockeries Rockeries should not be used unless the retained material would be stable without the rock facing. Rockeries are considered to act principally as erosion protection and they are not considered to provide strength to the slope unless designed as a buttress using limit equilibrium slope stability methods. Based on our review of the subsurface explorations and the proposed plans, it is our opinion that cuts in the southeast portion of the site will likely encounter dense glacial till which has historically been shown to be stable with rockery facings at minimal heights. We do not recommend rockeries be constructed in front of fill with more than 3 feet of exposed height, such as the proposed fills in the western portion of the project area, unless constructed as a wrapped-face MSE wall with rockery facing. We recommend tiered rockeries be separated by level terraces at least equal to the height of the lower rockery, so that the upper rockery does not place a surcharge load on the lower rockery. Proposed rockeries should be constructed in accordance with the ARC Rock Wall Construction Guidelines. Gravity Walls Large modular concrete block walls (such as Redi-Rock or Ultrawall) may also be feasible if designed as gravity walls (without geosynthetic reinforcement). Gravity walls depend primarily on the weight of the concrete blocks to resist failure from overturning and sliding. Taller wall sections and walls subject to surcharge loading (including tiered wall configurations with less than 1H:1V separation) will require larger block sizes to resist the forces acting on the wall. Gravity walls constructed using Redi-Rock or Ultrawall blocks are typically feasible up to heights of about 12 feet, where no surcharge loads are applied. Preliminary Global Stability Analysis We analyzed the global stability of the proposed tiered wall configurations along cross- section B-B’ as shown on Figure 2. We understand the proposed configuration consists of 3 tiered walls with exposed heights of up to 14 feet with up to 3H:1V slopes between the walls. Our global stability model assumed a total vertical separation of 41 feet from the base of the lower wall to the top of the upper wall, consisting of two 11 foot tall walls (lower and middle walls), one 9 foot tall wall (upper wall), and two terraces each with a horizontal distance of 15 feet and vertical height of 5 feet (3H:1V slope). Our results indicate the lower walls should have a minimum reinforcement length of 1.8H and the upper wall should have a minimum reinforcement length of 1.0H, where H is the total height of the MSE wall (including embedment). These recommended reinforcement lengths would meet static and dynamic global stability criteria, which requires minimum factors of safety of 1.5 and 1.1, PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 22 respectively. We did not perform detailed internal, external, or compound stability analyses of the proposed walls. We recommend the wall designer be required to perform these analyses and to determine the required reinforcing strengths, lengths, and spacing where MSE walls are used. The actual design length of reinforcement may be controlled by internal or external stability considerations and may be greater. TABLE 9: RETAINING WALLS GLOBAL STABILITY ANALYSES RESULTS Cross Section Condition Loading Condition Factor of Safety B-B’ Existing Static Dynamic 3.3 1.5 Proposed Static Dynamic 1.8 1.2 Based on the measured infiltration rates in the advance outwash, we do not anticipate significant mounding will occur below the proposed infiltration trenches. However, to account for potential local groundwater mounding and the corresponding impact to global stability, our model for the proposed developed conditions includes a water table elevated by 3 to 4 feet below the proposed infiltration trenches. The proposed walls at the site should be constructed with adequate drainage, as described below, to reduce the development of hydrostatic pressure acting on the proposed retaining walls. Our stability analyses assumed saturated conditions would not develop in the reinforced zones of the proposed MSE walls. Below Grade Walls and Retaining Wall Drainage Adequate drainage behind subgrade walls and retaining structures is imperative. Positive drainage which controls the development of hydrostatic pressure can be accomplished by placing a zone of drainage behind the walls. Granular drainage material should contain less than 2 percent fines and at least 30 percent greater than the US No. 4 sieve. A soil drainage zone should extend horizontally at least 18 inches from the back of the wall or back of reinforced zone. The drainage zone should also extend from the base of the wall to within 1 foot of the top of the wall. The soil drainage zone should be compacted to approximately 90 percent of the MDD. Over-compaction should be avoided as this can lead to excessive lateral pressures. A geocomposite drain mat may also be used instead of free draining soils, provided it is installed in accordance with the manufacturer’s instructions. Typical wall drainage and backfill is shown on Figure 10. A minimum 4-inch diameter perforated or slotted PVC pipe should be placed in the drainage zone along the base and behind the wall to provide an outlet for accumulated water and direct accumulated water to an appropriate discharge location. We recommend that a nonwoven geotextile filter fabric be placed between the soil drainage material and the remaining wall backfill to reduce silt migration into the drainage zone. The infiltration of silt into the drainage zone can, with time, reduce the permeability of the granular material. The filter fabric should be placed such that it fully separates the drainage material and the backfill, and should be extended over the top of the drainage zone. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 23 Tiered MSE Retaining Wall Drainage Where tiered MSE walls are constructed, we recommend a minimum 4-inch diameter perforated or slotted PVC collector pipe should be placed at the back of the reinforcement zone at the base of the wall as shown on Figure 9. The collector pipe should be surrounded by ¾ inch to 1½ inch washed gravel and wrapped in filter fabric. The drain should run the entire length of the wall and have proper outlets to an approved discharge point at the ends and/or at regularly spaced points along the wall. Solid pipe should be used for outlets through the face or under the retaining wall, and should be connected to the perforated collector pipe. Potential additional drainage requirements, such as blanket and chimney drains, should be determined by the wall designer based on the final wall design. Temporary Excavations All job site safety issues and precautions are the responsibility of the contractor providing services/work. The following cut/fill slope guidelines are provided for planning purposes only. Temporary cut slopes will likely be necessary during grading operations or utility installation. All excavations at the site associated with confined spaces, such as utility trenches and retaining walls, must be completed in accordance with local, state, or federal requirements including Washington Administrative Code (WAC) and Washington Industrial Safety and Health Administration (WISHA). Excavation, trenching, and shoring is covered under WAC 296-155 Part N. Based on WAC 296-155-66401, it is our opinion that the glacial till deposits would be classified as Type A soils, and the advance outwash and weathered glacial deposits would be classified as Type B soils, except where seepage occurs and would then be classified as Type C. Existing fill soils encountered at the site should also be classified as Type C. According to WAC 296-155-66403, for temporary excavations of less than 20 feet in depth, the side slopes in Type C soils should be sloped at a maximum inclination of 1.5H:1V or flatter from the toe to top of the slope, the side slopes in Type B soils should be sloped at a maximum inclination of 1H:1V or flatter, and side slopes in Type A soils should be laid back at a slope inclination of 0.75H:1V or flatter. All exposed slope faces should be covered with a durable reinforced plastic membrane during construction to prevent slope raveling and rutting during periods of precipitation. These guidelines assume that all surface loads are kept at a minimum distance of at least one half the depth of the cut away from the top of the slope and that significant seepage is not present on the slope face. Flatter cut slopes will be necessary where significant raveling or seepage occurs, or if construction materials will be stockpiled along the slope crest. Where it is not feasible to slope the site soils back at these inclinations, a retaining structure should be considered. Retaining structures greater than 4-feet in height (bottom of footing to top of structure) or that have slopes of greater than 15 percent above them, should be engineered per WAC 51-16-080 item 5. This information is provided solely for the benefit of the owner and other design consultants, and should not be construed to imply that GeoResources assumes responsibility for job site safety. It is understood that job site safety is the sole responsibility of the project contractor. Permanent Cut and Fill Slopes We recommend a maximum slope of 2H:1V (Horizontal:Vertical) for permanent cut slopes and for fill slopes up to 6 feet in height. Fill slopes taller than 6 feet should be sloped at 3H:1V per FWRC 19.120.100. Where slopes are not feasible, retaining structures as discussed above should be considered. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 24 Fill slopes constructed on grades that are steeper than 5H:1V should be constructed in accordance with Appendix J of the 2015 IBC and the King County Surface Water Design Manual, as amended by the City of Federal Way and FWRC Title 16, as well as Chapter 16.142. Fill slopes should utilize proper keying and benching methods. An excerpt from the 2015 IBC, Appendix J is included as Figure 11. The benches should be 1½ times the width of the equipment used for grading and be a maximum of 3 feet in height. Subsurface drainage may be required in areas where significant seepage is encountered during grading. Collected drainage should be directed to an appropriate discharge point. Surface drainage should be directed away from all slope faces. All permanent slopes should be protected from erosion as soon as feasible after grading is completed. Typical erosion control methods per the 2016 KCSWDM should be sufficient for proposed site grading activities. Additionally, permanent slopes should be planted with a hardy vegetative groundcover, mulched, or armored with quarry spalls as soon as feasible after grading is completed. Site Drainage All ground surfaces, pavements and sidewalks at the site should be sloped to direct surface water away from the structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and or catch basins, and conveyed to an appropriate discharge point. Collected water should not be discharged onto slopes steeper than 30 percent. We recommend that footing drains are installed for the buildings in accordance with 2015 IBC 1805.4.2, and basement walls (if utilized) have a wall drain as describe above. The roof drain should not be connected to the footing drain. Pavement Section Design We understand that several pavement sections may be used for the onsite portion of the development, including flexible pavement design consisting of hot mix asphalt (HMA) in the passenger car parking stalls, passenger car drive lanes, and either HMA or rigid pavement design consisting of Portland cement concrete (PCC) in the truck traffic areas. We were provided with a draft Memorandum prepared by Transportation Engineering Northwest (TENW) dated October 8, 2019 which provided estimates of weekday peak hour traffic at the proposed facility. Pavement Subgrades Pavement subgrade areas should be prepared by removing any soft or deleterious material down to firm and unyielding soils in accordance with the “Site Preparation” section of this report. The prepared subgrade should be evaluated by proof-rolling with a fully-loaded dump truck or equivalent heavy point load equipment. Soft, loose, or wet areas that are identified should be recompacted or removed, as appropriate. Over-excavated areas should be backfilled with compacted structural fill. Where fill is placed, the upper 2 feet of roadway subgrade should have a maximum dry density of at least 95 percent of the MDD, as determined in accordance with the ASTM D: 1557. On-Site Pavement Sections We have prepared this analysis in accordance with the 1993 AASHTO flexible and rigid pavement design methods. The AASHTO 93 design method quantifies traffic loading in terms of 18- Kip ESALs (equivalent single axle loads). The estimated ESALs over the entire design life were determined using the provided traffic data and assumed vehicle loads, and extending the daily value PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 25 over a 20- or 40-year design life. We have assumed that commercial truck traffic will drive across the heavy HMA and PCC pavement sections, while the parking stall and light HMA pavement sections will only be used by passenger cars and occasional delivery trucks. We assumed that each passenger car applies an average of 0.008 ESALs. We assumed that commercial trucks would apply 1.2 ESALs. Based on our bearing ratio (CBR) test results, we have assumed an equivalent subgrade modulus value of 8 ksi. These assumptions should be verified prior to construction, and, if the assumptions contained herein are not correct, we should be notified and allowed to review our calculations. Table 10, below, summarizes our assumptions and inputs for the design of the pavement sections, and Table 11, below, summarizes the recommended pavement section thicknesses. TABLE 10: INPUT DATA FOR PAVEMENT DESIGN Parameter Parking Stalls HMA Light HMA Heavy HMA PCC Design Life (years) 20 20 20 40 Design Traffic Load (ESALs) 3,504 162,644 525,600 1,051,200 Initial Serviceability 4.2 4.2 4.2 4.5 Terminal Serviceability 2.3 2.3 2.3 2.5 Reliability, R 85% 85% 85% 80% Elastic Modulus, E (ksi) N/A N/A N/A 4,000 Modulus of Subgrade Reaction, k (pci) N/A N/A N/A 200 Resilient Modulus, Base Course (ksi) 28 28 28 N/A Resilient Modulus, Subgrade (ksi) 8 8 11 N/A Layer Coefficient, HMA (a1) 0.44 0.44 0.44 N/A Layer Coefficient Base Course (a2) 0.13 0.13 0.13 N/A Drainage Coefficient (m, Cd) 1 1 1 1 Notes: ESALs – Equivalent Single Axle Loads ksi – kips per square inch pci – pounds per cubic inch TABLE 11: SECTION THICKNESS RECOMMENDATIONS Section Parking Stalls (inches) Light HMA (inches) Heavy HMA (inches) PCC (inches) Pavement 2 3.5 4.5 6.5 CSBC or CSTC 4 7 7.5 N/A1 Notes: CSBC – Crushed Surface Base Course per WSDOT 9-03.9(3) CSTC – Crushed Surface Top Course per WSDOT 9-03.9(3) 1 Leveling course as needed below PCC (typically about 2- to 4-inches of crushed rock) The above recommended section thicknesses meet the AASHTO 93 design standards based on the assumed traffic loading. Additional loading may contribute to premature failure of the pavement section. We anticipate heavy vehicle traffic from construction traffic or emergency vehicles would likely exceed the design loading of the parking stall HMA section. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 26 Off-Site Pavement Sections We have also prepared pavement sections in accordance with the 1993 AASHTO flexible and rigid pavement design methods for 32nd Avenue South. Based on the City of Federal Way Comprehensive Plan, Map III-4 we understand 32nd Avenue South is considered a minor arterial with street section type “K”. Per the City’s Minimum Street Design Standards, Table 1 street section “K” has an average daily traffic of 5,000 to 15,000. No off-site traffic data was provided. We assumed an initial average daily traffic value of 15,000, equal to the maximum value for a street section type “K”. We as sumed 2% annual traffic growth. Based on traffic count information retrieved from the WSDOT Traffic GeoPortal website for Highway 509 (a street section type “K” roadway in the City of Federal Way), we assumed the following traffic percentages: 96.75% passenger cars, 2.5% single-unit trucks, and 0.75% multi-unit trucks. We assumed that each passenger car applies an average of 0.008 ESALs, the single-unit trucks would apply 1.8 ESALs (HS-20 loading), and the multi-unit trucks would apply 3 ESALs. These assumptions should be verified prior to construction, and, if the assumptions contained herein are not correct, we should be notified and allowed to review and update our calculations, as appropriate. Table 12, below, summarizes our assumptions and inputs for the design of the pavement sections, and Table 13, below, summarizes the design pavement section thicknesses. TABLE 12: INPUT DATA FOR PAVEMENT DESIGN Parameter HMA PCC Design Life (years) 20 40 Design Traffic Load (ESALs) 10,621,154 25,791,510 Initial Serviceability 4.2 4.5 Terminal Serviceability 2.3 2.5 Reliability, R 85% 80% Elastic Modulus, E (ksi) N/A 4,000 Modulus of Subgrade Reaction, k (pci) N/A 200 Resilient Modulus, Base Course (ksi) 28 N/A Resilient Modulus, Subgrade (ksi) 9 N/A Layer Coefficient, HMA (a1) 0.44 N/A Layer Coefficient Base Course (a2) 0.13 N/A Drainage Coefficient (m, Cd) 1 1 Notes: ESALs – Equivalent Single Axle Loads ksi – kips per square inch pci – pounds per cubic inch PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 27 TABLE 13: 32nd AVENUE SOUTH DESIGN SECTION THICKNESS Section HMA (inches) PCC (inches) Pavement 7 11 CSBC or CSTC 11 N/A1 Notes: CSBC – Crushed Surface Base Course per WSDOT 9-03.9(3) CSTC – Crushed Surface Top Course per WSDOT 9-03.9(3) 1 Leveling course as needed below PCC (typically about 2- to 4-inches of crushed rock) While our calculations indicate the above HMA section would support the assumed traffic loading, per the City Public Works drawing number 3-2K, the minimum HMA pavement sections for a minor arterial street section type “K” consist of the below options. TABLE 14: MINIMUM PAVEMENT SECTION, TYPE K, MINOR ARTERIAL Section (inches) (inches) HMA ½-inch 8 10 HMA 1-inch 6 N/A CSTC N/A 10 Notes: CSTC – Crushed Surface Top Course per WSDOT 9-03.9(3) In our opinion, either minimum pavement section is suitable for 32nd Avenue South. We recommend a total crushed rock base course thickness of 11-inches, consisting of either CSTC or CSBC, be placed below HMA pavement sections. Pavement Frost Conditions Frost-susceptible soil is generally regarded as having greater than 3 percent finer than 0.02 millimeter (mm). Soil with a fines content not exceeding 7 percent passing the No. 200 sieve, based on the minus ¾-inch fraction, can normally be expected to have 3 percent or less finer than 0.02 mm. Based on the soils observed during our construction monitoring, most of the near-surface soils could be considered frost-susceptible. Based on information provided in the WSDOT Pavement Policy, we recommend assuming the frost depth would be about 18 inches. For both rigid and flexible pavements, WSDOT recommends that the total depth of the pavement section be at least 50 percent of the frost depth. The recommended parking stall HMA pavement section is less than 9- inches thick and therefore may be susceptible to frost heave damage; a thicker CSBC base layer could be used with our recommended parking stall HMA pavement section to provide frost protection, or additional maintenance should be anticipated. Pavement Materials and Construction In general, the aggregate base course, HMA, and PCC should be constructed in accordance with WSDOT Standard Specifications for Road, Bridge, and Municipal Construction (WSDOT Standard Specifications, 2016). HMA should conform to Section 5-04 in the WSDOT Standard Specifications and the PCC should conform to Section 5-05 of the WSDOT Standard Specifications. We recommend that PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 28 crushed rock used as CSBC in pavement sections consist of material of approximately the same quality as “crushed surfacing (base course)” (or better) described in Section 9-03.9(3) of the WSDOT Standard Specifications. We further recommend that CSBC material be compacted to at least 95 percent of the MDD based on the modified Proctor procedure (ASTM D: 1577). Stormwater Recommendations We understand that the City of Federal Way uses the 2016 King County Surface Water Design Manual (KCSWDM) for stormwater management. Stormwater facilities should be designed and constructed in accordance with the 2016 KCSWDM. All infeasibility criteria and minimum setbacks should be considered prior to the selection of a stormwater management method. Infiltration facilities should not be located within 200 feet of a steep slope hazard area, defined in the 2016 KCSWDM as an area on a slope of 40 percent inclination or more with a vertical elevation change of at least 10 feet. Therefore, infiltration facilities should not be located within 200 feet of the top of the steep slope as shown on Figure 2 in the southwest portion of the site. Based on the current site plans, we understand no infiltration facilities are proposed within 200 feet of the steep slope. In accordance with Section 5.2 of the 2016 KCSWDM, a minimum separation of 3 feet between the bottom of an infiltration facility and the top of a seasonal high groundwater table or other impermeable layer is required. Per the 2016 KCSWDM, evidence of seasonal high groundwater includes mottling or iron oxide staining. In our opinion, the minimum separation requirements for infiltration facilities can be met where advance outwash was encountered, including in the vicinity of test pits TP-1, TP-2, TP-3, TP-4, TP- 7, and TP-103 and borings B-1, B-2, and B-3 in the western portion of the project area. Where glacial till was encountered mantling advance outwash, including test pits TP-8 and TP-10, infiltration should be feasible if the bottom elevation of the facility is located within the gravelly outwash soils. Therefore, it is our opinion that onsite infiltration is feasible for the proposed development if the facilities are located in the vicinities of test pits TP-1, TP-2, TP-3, TP-4, TP-7, TP-8, TP-10, or TP-103 provided the minimum vertical separation requirements can be achieved through design. Our groundwater monitoring measured groundwater at approximately elevation 463 feet in the northwest portion of the site. Our test pit explorations in the south and east portions of the site, in the vicinity of test pits TP-5, TP-6, TP-9, TP-11, TP-12, and TP-13 and borings B-4 and B-5 encountered glacial till to the full depth explored with evidence of seasonal groundwater as shallow as 2 feet below the existing ground surface. The minimum required vertical separation between the bottom of an infiltration facility and evidence of seasonal high groundwater likely cannot be met in these portions of the site. Therefore, it is our opinion that onsite infiltration in the vicinity of test pits TP-5, TP-6, TP-9, TP-11, TP- 12, and TP-13 is not feasible. Additionally, onsite infiltration should not occur within fill material unless the fill is placed and compacted under the supervision of a geotechnical engineer and the fill has a minimum measured infiltration rate of 8 inches per hour. As noted, we understand you propose to fill the western portion of the project site. We do not recommend infiltration facilities have bottom elevations located within the fill, unless it meets the above requirements. Materials such as Permeable Ballast (WSDOT Spec 9- 03.9(2)) or Gravel Backfill for Drains (WSDOT Spec 9-03.12(4)) can provide the required infiltration rate. Design Infiltration Rate We performed three small scale pilot infiltration tests (PIT-1, PIT-2, and PIT-3) in general accordance with the 2016 KCSWDM. No indicators of an impermeable layer underlying the test PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 29 locations pits were observed during over-excavation. Based on our test results, we recommend allowable long-term design infiltration rates of 2.75 inches per hour be used to design infiltration facilities within the silty gravel soils in the vicinity of PIT-2, PIT-3, TP-3, B-1, B-2, and B-3 (north and west of the existing barn); and a design infiltration rate of 6.5 inches per hour be used to design infiltration facilities within the poorly graded gravel and poorly graded sand soils in the vicinity of PIT-1, TP-4, TP-7, TP-8, and TP-103 (southwest of the existing barn). The recommended infiltration rates and locations are summarized below in Table 15. TABLE 15: RECOMMENDED DESIGN INFILTRATION RATE OF ON-SITE SOILS Infiltration Rate (in/hr) Soil Type Location Approximate Depths Encountered (ft) 2.75 GM / GW-GM PIT-2 PIT-3 TP-3 B-1 B-2 B-3 2 – 7+ 7 – 10+ 2½ - 9½+ 8 – 21+ 4 – 21+ 9 – 21+ 6.5 GP / SP PIT-1 TP-4 TP-7 TP-8 TP-103 1½ - 6+ 2 – 10+ 2 – 10+ 6 – 9+ 2 – 9+ We recommend that a representative from our firm be onsite at the time of excavation of the proposed infiltration facilities to verify that the soils encountered during construction are consistent with the soils observed in our subsurface explorations. The design infiltration rate is determined based on the procedure provided in section 5.2.1 of the 2016 KCSWDM. Three correction factors are applied to account for testing (Ftesting), geometry (Fgeometry), and plugging (Fplugging). The design infiltration rate is determined as follows: Idesign = Imeasured X Ftesting X Fgeometry X Fplugging Where: Idesign = Infiltration rate to be used for design of infiltration facility Imeasured = Infiltration rate measured in the field or estimated by grain size analysis Ftesting = Accounts for test method used (0.4 to 0.75) Test Method Correction Factor (Ftesting) Large Scale PIT 0.50 Small Scale PIT 0.50 Single Ring Percolation Test 0.30 PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 30 Fgeometry = Accounts for the influence of facility geometry and depth to water table or other impervious strata. Fgeometry must be between 0.25 and 1.0 and is determined by: Fgeometry = 4 D/W + 0.05 Where: D = depth from the bottom of the proposed facility to the nearest impervious layer. W = Width of Facility Fplugging accounts for reductions in infiltration rates over the long term due to plugging of soils. Soil Type Correction Factor (Fplugging) Loams and sandy loams 0.7 Fine sands and loamy sands 0.8 Medium sands 0.9 Coarse sands or cobbles 1.0 Based on the definitions and criteria outlined above, for infiltration rates determined by the small scale PIT method, we used a value of 0.5 for Ftesting, a value of 1.0 for Fgeometry, and a value of 0.9 for Fplugging. Permeable Pavement Per 2016 KCSWDM, Section C.2.7, permeable pavement is not feasible where the seasonal high ground water or an underlying impermeable/low permeability layer (hardpan) would create saturated conditions within 1 foot of the bottom of the lowest gravel base course. Based on the soils encountered in our test pits, it is our opinion that permeable pavement is feasible at the site provided the vertical separation can be met and maintained after site grading. Where the upper weathered till soils are proposed to be removed during grading, we anticipate the vertical separation from seasonal high groundwater cannot be met. We recommend we be on site to observe the vertical separation to the undisturbed glacial till near the central and southeast portions of the site if permeable pavement is proposed to be used in those areas. Based on a soil gradation analysis performed in accordance with ASTM D: 6913, where infiltration is feasible, we recommend a preliminary long-term design infiltration rate of 0.5 inches per hour in the medium dense tan silty sand with gravel soils generally encountered at depths of 0.5 to 2.5 feet across the site. Once the final permeable pavement section design is determined, the City of Federal Way will likely require in-situ infiltration performance testing be performed to verify the design infiltration rate in accordance with the 2016 KCSWDM. Treatment Capacity Cat-ion exchange capacity (CEC) and organic content testing were also performed on four samples by an independent laboratory to evaluate the treatment capacity of the shallow onsite soils for LID methods. The results of the laboratory tests are included in Appendix B and summarized in Table 16 below. The shallow onsite soils in the vicinity of both the proposed parking areas (TP-4 PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 31 and TP-11) and the proposed infiltration trenches (TP-3 and TP-11) meet treatment requirements per the KCSWDM. TABLE 16: TREATMENT CAPACITY OF ON-SITE SOILS Location Sample Lab ID Number Cation Exchange Capacity (mEq/100g) Organic Content (percent) Minimum Requirement for Treatment 5.0 1.0 Proposed infiltration trench TP-3, S-1 TP-7, S-1 098503 098507 23.8 11.3 2.4 3.0 Proposed paved area TP-4, S-1 TP-11, S-1 098505 098511 11.5 8.53 3.5 3.2 Construction Considerations Suspended solids could clog the underlying soil and reduce the infiltration rate. To reduce potential clogging of the infiltration systems, the infiltration system should not be connected to the stormwater runoff system until after construction is complete and the site area is landscaped, paved or otherwise protected. Additional measures may also be taken during construction to minimize the potential of fines contamination of the proposed infiltration system, such as utilizing an alternative storm water management location during construction or leaving the bottom of the permanent systems 1 to 2 feet high, and subsequently excavating to the finished grade once the site soils have been stabilized. All contractors working on the site (builders and subcontractors) should divert sediment laden stormwater away from proposed infiltration facilities during construction and landscaping activities. No concrete trucks should be washed or cleaned, and washout areas should not be within the vicinity of the proposed infiltration facilities. After construction activities have been completed, periodic sweeping of the paved areas will help extend the life of the infiltration system. Detention Pond A stormwater detention pond is currently proposed to be located in the southwest portion of the site. As currently designed, the pond will have a constructed embankment on the downhill (western) side and a cut slope on the uphill (eastern) side, as shown on the attached site plan. We recommend that the fill portion of the embankment (the downhill, western portion of the embankment) be constructed by excavating a keyway at the bottom of the berm, per section 5.1.1.1 of the KCSWDM. We recommend the keyway be at least 5 feet wide at the bottom and the side slopes should be no steeper than 1H:1V. The keyway should extend into the native soils a minimum of 4 feet. The keyway should reduce ground water seepage along the embankment/native soil contact. The minimum 5-foot width may require the use of small compaction equipment, such as a hoe-pack. The contractor may opt to widen the keyway in order to use a wheel roller. All material placed as fill for the pond embankment should be placed as structural fill. Structural fill in the embankment should be compacted to at least 95 percent of MDD (maximum dry density as determined in accordance with ASTM D: 1557) and be at or slightly over the optimum moisture content. Per the KCSWDM, structural fill material placed for construction of the embankment shall have a fines content between 20 and 60 percent, and a maximum of 60 percent sand. We also recommend the structural fill contain less than 30 percent gravel. Based on our grain PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 32 size analyses, the native glacial till soils located at the site generally meet these gradation requirements. The surface of the fill embankment should be protected from erosion by covering it with a minimum of 3 inches of 1¼-inch compacted crushed rock. The crushed rock should be underlain by Mirafi 140N non-woven geotextile or approved equivalent. Preventing erosion on the embankment slopes is paramount to the long-term stability, performance, and level of required maintenance of the pond embankment. We recommend that the proposed pond be lined with a low permeability liner to reduce infiltration and reduce seepage from occurring below the downslope embankment. We anticipate the bottom of the proposed pond will encounter silty gravel soil that may have a moderate infiltration rate. The pond should not be designed to use infiltration, because of the proximity to the adjacent steep slope. The native glacial till soils encountered in the upland portion of the site generally meet the requirements of section 6.2.4.1 of the KCSWDM and in our opinion are suitable for re-use as a compacted till liner. The compacted till liner should be compacted to at least 95 percent of MDD and be 18 inches after compaction. Alternatively, a geosynthetic pond liner, such as PVC or HDPE, may be installed along the pond and the pond embankment to prevent excessive seepage and saturation of soils. We recommend that a representative from GeoResources should be present during construction to verify conditions as they are exposed and to verify that the fill and pond are constructed per the approved plan and recommendations contained herein. Slope Stability Based on our slope stability analyses, the proposed pond embankments meet or exceed a FS of 1.5 and a FS of 1.1 in static and seismic conditions, respectively, provided our recommendations are incorporated into the project design and construction. Details of the slope stability analyses are included in Appendix C and a summary of the results is provided in Table 17 below. TABLE 17: POND EMBANKMENT SLOPE STABILITY ANALYSES RESULTS Cross Section Water Condition Loading Condition Factor of Safety A-A’ Full Full Emptied (Rapid Drawdown) Static Dynamic Static 2.0 1.1 2.0 As stated above in the “Recommended Buffer and Setback from Steep Slopes” section, because our stability analyses indicate the proposed improvements will not create an increased slide hazard, we recommend the buffer above the steep slope be reduced to 15 feet. We understand the base of the proposed detention pond embankment is approximately 15 to 30 feet from the top of the steep slope, meeting or exceeding our recommended buffer. EARTHWORK RECOMMENDATIONS Site Preparation All structural areas on the site to be graded should be stripped of vegetation, organic surface soils, and other deleterious materials including existing structures, foundations or abandoned utility PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 33 lines. Organic topsoil is not suitable for use as structural fill, but may be used for limited depths in non-structural areas. Stripping depths ranging from about 6 to 18 inches should be expected to remove these unsuitable soils in the undeveloped areas of the site. Areas of thicker topsoil or organic debris may be encountered in areas of heavy vegetation or depressions. Where placement of fill material is required, the stripped/exposed subgrade areas should be compacted to a firm and unyielding surface prior to placement of any fill. Excavations for debris removal should be backfilled with structural fill compacted to the densities described in the “Structural Fill” section of this report. We recommend that a member of our staff evaluate the exposed subgrade conditions after removal of vegetation and topsoil stripping is completed and prior to placement of structural fill. The exposed subgrade soil should be proof-rolled with heavy rubber-tired equipment during dry weather or probed with a 1/2-inch-diameter steel rod during wet weather conditions. Soft, loose or otherwise unsuitable areas delineated during proofrolling or probing should be recompacted, if practical, or over-excavated and replaced with structural fill. The depth and extent of over excavation should be evaluated by our field representative at the time of construction. The areas of old fill material should be evaluated during grading operations to determine if they need mitigation, recompaction, or removal. Structural Fill All material placed as fill associated with mass grading, as utility trench backfill, pond embankment, under building areas, or under roadways and pavement areas should be placed as structural fill. The structural fill should be placed in horizontal lifts of appropriate thickness to allow adequate and uniform compaction of each lift. Structural fill should be compacted to at least 95 percent of MDD (maximum dry density) as determined in accordance with ASTM D: 1557. The appropriate lift thickness will depend on the structural fill characteristics and compaction equipment used. We recommend that the appropriate lift thickness be evaluated by our field representative during construction. We recommend that our representative be present during site grading activities to observe the work and perform field density tests. The suitability of material for use as structural fill will depend on the gradation and moisture content of the soil. As the amount of fines (material passing US No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult to achieve. During wet weather, we recommend use of well-graded sand and gravel with less than 5 percent (by weight) passing the US No. 200 sieve based on that fraction passing the ¾-inch sieve, such as Gravel Backfill for Walls (WSDOT 9-03.12(2)). If prolonged dry weather prevails during the earthwork and foundation installation phase of construction, higher fines content (up to 10 to 12 percent) may be acceptable. Requirements for pond embankment fill are discussed in the “Detention Pond” section of this report. Material placed for structural fill should be free of debris, organic matter, trash, and cobbles greater than 6-inches in diameter. The moisture content of the fill material should be adjusted as necessary for proper compaction. Suitability of On-Site Materials as Structural Fill During dry weather construction, any nonorganic onsite soil may be considered for use as structural fill, provided it meets the criteria described above in the “Structural Fill” section and can be compacted as recommended. If the moisture content of the soil is over optimum when excavated, it will be necessary to aerate or dry the soil prior to placement as structural fill. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 34 The native weathered till and glacial till soils generally consisted of silty sand with gravel. These soils are generally comparable to common borrow (WSDOT 9-03.14(3)) and are suitable for use as structural fill provided the moisture content is maintained within 2 percent of the optimum moisture level. However, these soils may become difficult to adequately compact during extended periods of wet weather or where seepage occurs. As stated, the native glacial till generally meets gradation requirements for use in detention pond embankments and as a compacted till liner per the 2016 KCSWDM. The native advance outwash soils generally consist of poorly-graded gravel with variable amounts of silt. These soils are generally comparable to select borrow (WSDOT 9-03.14(2)) and are suitable for use as structural fill provided the moisture content is maintained within 3 percent of the optimum moisture level. The upper advance outwash soils in the vicinity of the existing barn in the northwest portion of the site had a higher fines content (about 15 to 20 percent), and are generally comparable to common borrow. The undocumented fill soils encountered northwest of the existing barn appear to contain a significant amount of organic content and we do not recommend these soils be re-used as structural fill. The undocumented fill soil encountered in test pit TP-102 in the southwest portion of the site appeared to consist of reworked native soils, and should be suitable for re-use as structural fill provided any encountered debris is removed. We recommend that completed graded areas be restricted from traffic or protected prior to wet weather conditions. The graded areas may be protected by paving, placing asphalt-treated base, a layer of free-draining material such as pit run sand and gravel or clean crushed rock material containing less than 5 percent fines, or some combination of the above. Erosion Control Weathering, erosion and the resulting surficial sloughing and shallow land sliding are natural processes. As noted, no evidence of surficial raveling or sloughing was observed at the site. To manage and reduce the potential for these natural processes, we recommend erosion protection measures will need to be in place prior to grading activity on the site. Erosion hazards can be mitigated by applying BMPs outlined in the 2016 King County Surface Water Design Manual. Wet Weather Earthwork Considerations In the Puget Sound area, wet weather generally begins about mid-October and continues through about May, although rainy periods could occur at any time of year. Therefore, it is strongly encouraged that earthwork be scheduled during the dry weather months of June through September. Most of the soil at the site contains sufficient fines and is highly susceptible to changes in water content and tends to become unstable and impossible to proof-roll and compact if the moisture content exceeds the optimum. In addition, during wet weather months, the groundwater levels could increase, resulting in seepage into site excavations. Performing earthwork during dry weather would reduce these problems and costs associated with rainwater, construction traffic, and handling of wet soil. However, should wet weather/wet condition earthwork be unavoidable, the following recommendations are provided: Grading and earthwork should not be accomplished during periods of heavy, continuous rainfall. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 35 The ground surface in and surrounding the construction area should be sloped as much as possible to promote runoff of precipitation away from work areas and to prevent ponding of water. Work areas or slopes should be covered with plastic when not being worked. The use of sloping, ditching, sumps, dewatering, and other measures should be employed as necessary to permit proper completion of the work. Earthwork should be accomplished in small sections to minimize exposure to wet conditions. That is, each section should be small enough so that the removal of unsuitable soils and placement and compaction of clean structural fill could be accomplished on the same day. The size of construction equipment may have to be limited to prevent soil disturbance. It may be necessary to excavate soils with a backhoe, or equivalent, and locate them so that equipment does not pass over the excavated area. Thus, subgrade disturbance caused by equipment traffic would be minimized. Fill material should consist of clean, well-graded, sand and gravel, of which not more than 5 percent fines by dry weight passes the No. 200 mesh sieve, based on wet-sieving the fraction passing the ¾-inch mesh sieve. The gravel content should range from between 20 and 50 percent retained on a No. 4 mesh sieve. The fines should be non-plastic. No exposed soil should be left uncompacted and exposed to moisture. A smooth-drum vibratory roller, or equivalent, should roll the surface to seal out as much water as possible. In-place soil or fill soil that becomes wet and unstable and/or too wet to suitably compact should be removed and replaced with clean, granular soil (see gradation requirements above). Excavation and placement of structural fill material should be observed on a full-time basis by a geotechnical engineer (or representative) experienced in wet weather/wet condition earthwork to determine that all work is being accomplished in accordance with the project specifications and our recommendations. We recommend that the above requirements for wet weather/wet condition earthwork be incorporated into the contract specifications, where applicable. LIMITATIONS We have prepared this report for use by the Papé Group, Cobalt Development, Barghausen Engineering, H.G. Kimura Architect, Soundview Consultants, and other members of the design team, for use in the design of a portion of this project. The data used in preparing this report and this report should be provided to prospective contractors for their bidding or estimating purposes only. Our report, conclusions and interpretations are based on our site reconnaissance, subsurface explorations, and data from others, and should not be construed as a warranty of the subsurface conditions. Variations in subsurface conditions are possible between the explorations and may also occur with time. A contingency for unanticipated conditions should be included in the budget and schedule. Sufficient monitoring, testing and consultation should be provided by our firm during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork and foundation installation activities comply with contract plans and specifications. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 36 The scope of our services does not include services related to environmental remediation and construction safety precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. If there are any changes in the loads, grades, locations, configurations or type of facilities to be constructed, the conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate. PapeKenworthNW.FederalWay.RG.rev01.kss May 28, 2020 page | 37 We have appreciated the opportunity to be of service to you on this project. If you have any questions or comments, please do not hesitate to call at your earliest convenience. Respectfully submitted, GeoResources, LLC Neil A. Ferguson, PE Project Geotechnical Engineer Keith S. Schembs, LEG Eric W. Heller, PE, LG Principal Senior Geotechnical Engineer NAF:EWH:KSS/naf Doc ID: PapeKenworthNW.FederalWay.RG.rev01 5/30/2020 Approximate Site Location (Map created from King County Public GIS http://gismaps.kingcounty.gov/iMap/) Not to Scale Site Location Map Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F May 2020 Figure 1 Preliminary Site Plan prepared by H.G. Kimura Architect , LLC dated May 18, 2020 Approximate Test Pit Location Global Stability Cross-section Approximate Boring Location Geologically Hazardous Area Buffer (15 feet) Scale 1” = 100’ Site & Exploration Plan Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc: PapeKenworthNW.FederalWay.F May 2020 Figure 2 TP-1 TP-2 TP-3 TP-4 TP-5 TP-7 TP-8 TP-6 TP-9 TP-10 TP-11 TP-13 TP-12 A A’ B TP-101 TP-103 B-1 B-2 B-3 B-5 B-4 PIT-1 PIT-2 PIT-3 B’ Geologically Hazardous Area TP-102 ALTA/NSPS Land Title Survey prepared by Barghausen Consulting Engineers, Inc dated December 7, 2019 Not to Scale Site Topographic Survey Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc: PapeKenworthNW.FederalWay.F May 2020 Figure 3 ALTA/NSPS Land Title Survey prepared by Barghausen Consulting Engineers, Inc dated December 7, 2019 15 to 39 percent slope 40 percent or greater slope Not to Scale Site Slopes Map Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc: PapeKenworthNW.FederalWay.F May 2020 Figure 4 Approximate Site Location (Map created from NRCS Web Soil Survey) Soil Type Soil Name Parent Material Slopes Erosion Hazard Hydrologic Soils Group AgB Alderwood Gravelly Sandy Loam Glacial till and/or glacial outwash 0 – 6 Slight B AgC 6 – 15 Moderate B AgD 15 – 30 Moderate to Severe B Sk Seattle Muck Grassy organic material Level None B/D W Water - - - - Not to Scale NRCS Soils Map Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F May 2020 Figure 5 Approximate Site Location An excerpt from the Geologic Map of the Poverty Bay 7.5-Minute Quadrangle, Washington, By Derek B. Booth, Howard H. Waldron, and Kathy G. Troost (2003) Qvt Glacial Till Qw Wetland deposits Not to Scale Geologic Map Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F May 2020 Figure 6 Conventional Footing Footing Extension Typical Structural Setback Detail Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F May 2020 Figure 7 Setback Distance Slopes Greater Than 30 Percent Foundation Element Residential Structure Footing Extension Slopes Greater Than 30 Percent Setback Distance Foundation Element Residential Structure Approximate Site Location Map created from Washington DNR Geologic Information Portal (https://geologyportal.dnr.wa.gov/) Not to Scale WA DNR Natural Hazards Map Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F May 2020 Figure 8 Tacoma Fault Zone Notes Typical Wall Drainage and Backfill Detail Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F May 2020 Figure 10 1. Washed pea gravel/crushed rock beneath floor slab could be hydraulically connected to perimeter/subdrain pipe. Use of 1” diameter weep holes as shown is one applicable method. Crushed gravel should consist of 3/4” minus. Washed pea gravel should consist of 3/8” to No. 8 standard sieve. 2. Wall backfill should meet WSDOT Gravel Backfill for walls Specification 9-03-12(2). 3. Drainage sand and gravel backfill within 18” of wall should be compacted with hand-operated equipment. Heavy equipment should not be used for backfill, as such equipment operated near the wall could increase lateral earth pressures and possibly damage the wall. The table below presents the drainage sand and gravel gradation. 4. All wall back fill should be placed in layers not exceeding 4” loose thickness for light equipment and 8” for heavy equipment and should be densely compacted. Beneath paved or sidewalk areas, compact to at least 95% Modified Proctor maximum density (ASTM: 01557-70 Method C). In landscaping areas, compact to 90% minimum. 5. Drainage sand and gravel may be replaced with a geocomposite core sheet drain placed against the wall and connected to the subdrain pipe. The geocomposite core sheet should have a minimum transmissivity of 3.0 gallons/minute/foot when tested under a gradient of 1.0 according to ASTM 04716. 6. The subdrain should consist of 4” diameter (minimum), slotted or perforated plastic pipe meeting the requirements of AASHTO M 304; 1/8-inch maximum slot width; 3/16- to 3/8- inch perforated pipe holes in the lower half of pipe, with lower third segment unperforated for water flow; tight joints; sloped at a minimum of 6”/100’ to drain; cleanouts to be provided at regular intervals. 7. Surround subdrain pipe with 8 inches (minimum) of washed pea gravel (2” below pipe” or 5/8” minus clean crushed gravel. Washed pea gravel to be graded from 3/8-inch to No.8 standard sieve. 8. See text for floor slab subgrade preparation. Materials Drainage Sand and Gravel ¾” Minus Crushed Gravel Sieve Size % Passing by Weight Sieve Size % Passing by Weight ¾” 100 ¾” 100 No 4 28 – 56 ½” 75 – 100 No 8 20 – 50 ¼” 0 – 25 No 50 3 – 12 No 100 0 – 2 No 100 0 – 2 (by wet sieving) (non-plastic) IBC Keying and Benching Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F May 2020 Figure 11 Appendix A Subsurface Exploration SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP SYMBOL GROUP NAME COARSE GRAINED SOILS More than 50% Retained on No. 200 Sieve GRAVEL More than 50% Of Coarse Fraction Retained on No. 4 Sieve CLEAN GRAVEL GW WELL-GRADED GRAVEL, FINE TO COARSE GRAVEL GP POORLY-GRADED GRAVEL GRAVEL WITH FINES GM SILTY GRAVEL GC CLAYEY GRAVEL SAND More than 50% Of Coarse Fraction Passes No. 4 Sieve CLEAN SAND SW WELL-GRADED SAND, FINE TO COARSE SAND SP POORLY-GRADED SAND SAND WITH FINES SM SILTY SAND SC CLAYEY SAND FINE GRAINED SOILS More than 50% Passes No. 200 Sieve SILT AND CLAY Liquid Limit Less than 50 INORGANIC ML SILT CL CLAY ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY Liquid Limit 50 or more INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT CH CLAY OF HIGH PLASTICITY, FAT CLAY ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS: 1. Field classification is based on visual examination of soil Dry- Absence of moisture, dry to the touch in general accordance with ASTM D2488-90. Moist- Damp, but no visible water 2. Soil classification using laboratory tests is based on ASTM D2487-90. Wet- Visible free water or saturated, usually soil is obtained from below water table 3. Description of soil density or consistency are based on interpretation of blow count data, visual appearance of soils, and or test data. Unified Soil Classification System Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F May 2020 Figure A-1 Test Pit TP-1 Location: Northeast portion of site Approximate Elevation: 457’ Depth (ft) Soil Type Soil Description 0 - 2 SM Tan silty SAND with some gravel and small roots (medium dense, moist) (weathered outwash) 2 - 10½ GP Tan poorly-graded GRAVEL with sand, grades to very dense and lightly cemented below 9.5 feet (dense, moist) (advance outwash) Terminated at 10½ feet below ground surface. No mottling observed. No caving observed. No groundwater seepage observed. Test Pit TP-2 Location: Northwest portion of site Approximate Elevation: 446’ Depth (ft) Soil Type Soil Description 0 - 1¼ - Topsoil/rootzone 1¼ - 4 SM Tan silty SAND with some gravel (medium dense, moist) (weathered outwash) 4 - 5½ SM Gray silty SAND with gravel, moderately cemented (dense, moist) (glacial till) 5½ - 9½ GP Tan to brown poorly-graded GRAVEL with sand, trace silt (dense, moist) (advance outwash) Terminated at 9½ feet below ground surface. No mottling observed. No caving observed. No groundwater seepage observed. Logged by: NAF Excavated on: October 9, 2019 Test Pit Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-2 Test Pit TP-3 Location: Northwest of proposed shop Approximate Elevation: 440’ Depth (ft) Soil Type Soil Description 0 - 2½ SM Tan to dark brown silty SAND with some gravel (medium dense, moist) (weathered outwash) 2½ - 6½ GP-GM Dark brown poorly-graded GRAVEL with silt and sand (medium dense to dense, moist to wet) (advance outwash?) 6½ - 9½ GM Tan silty GRAVEL with sand (medium dense to dense, moist) (advance outwash?) Terminated at 9½ feet below ground surface. No mottling observed. Moderate caving observed below 3 feet. Groundwater seepage observed from 3½ to 5 feet bgs. Test Pit TP-4 Location: West of proposed shop Approximate Elevation: 470’ Depth (ft) Soil Type Soil Description 0 - 2 SM Tan silty SAND with some gravel and small roots (medium dense, moist) (weathered outwash) 2 - 10 GP Brown poorly-graded GRAVEL with sand (dense, moist) (advance outwash) Terminated at 10 feet below ground surface. No mottling observed. No caving observed. No groundwater seepage observed. Logged by: NAF Excavated on: October 9, 2019 Test Pit Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-3 Test Pit TP-5 Location: East of proposed shop Approximate Elevation: 476’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 3 SM Tan silty SAND with gravel, mottled at bottom contact (medium dense, moist) (weathered till) 3 - 7½ SM Gray silty SAND with gravel, moderately cemented (dense to very dense, moist) (glacial till) Terminated at 7½ feet below ground surface. Mottling observed from 2½ to 3 feet bgs. No caving observed. No groundwater seepage observed. Test Pit TP-6 Location: Southern portion of proposed shop Approximate Elevation: 481’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 3 SM Tan to mottled gray silty SAND with gravel (medium dense, moist) (weathered till) 3 - 9 SM Gray silty SAND with gravel, moderately cemented (dense to very dense, moist) (glacial till) Terminated at 9½ feet below ground surface. Mottling observed from 2 to 3 feet bgs. No caving observed. No groundwater seepage observed. Logged by: NAF Excavated on: October 9, 2019 Test Pit Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-4 Test Pit TP-7 Location: West of proposed showroom Approximate Elevation: 468’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 2 SM Tan silty SAND with some gravel and small roots (medium dense, moist) (weathered outwash) 2 - 10 GP Brown poorly-graded GRAVEL with sand (dense, moist) (advance outwash) Terminated at 10 feet below ground surface. No mottling observed. No caving observed. No groundwater seepage observed. Test Pit TP-8 Location: Proposed showroom Approximate Elevation: 478’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 2½ SM Tan silty SAND with gravel, mottled at bottom contact (medium dense, moist) (weathered till) 2½ - 6 SM Gray silty SAND with gravel, moderately cemented (dense to very dense, moist) (glacial till) 6 - 9 GP-GM Brown poorly-graded GRAVEL with silt and sand (dense, moist) (advance outwash) Terminated at 9 feet below ground surface. Mottling observed from 2 to 2½ feet bgs. No caving observed. No groundwater seepage observed. Logged by: NAF Excavated on: October 9, 2019 Test Pit Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-5 Test Pit TP-9 Location: East of proposed showroom Approximate Elevation: 484’ Depth (ft) Soil Type Soil Description 0 - ¾ - Topsoil/rootzone ¾ - 2½ SM Tan to mottled gray silty SAND with gravel (medium dense, moist) (weathered till) 2½ - 6½ SM Gray silty SAND with gravel, moderately cemented (very dense, moist) (glacial till) Terminated at 6½ feet below ground surface. Mottling observed from 1½ to 2½ feet bgs. No caving observed. No groundwater seepage observed. Test Pit TP-10 Location: West portion of site, north of transmission lines Approximate Elevation: 476’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 3 SM Tan silty SAND with gravel and small roots (medium dense, moist) (weathered till) 3 - 8 SM Gray silty SAND with gravel and occasional cobbles, moderately cemented (dense to very dense, moist) (glacial till) 8 - 9 GP Brown poorly-graded GRAVEL with silt and sand (dense, moist) (advance outwash) Terminated at 9 feet below ground surface. No mottling observed. No caving observed. No groundwater seepage observed. Logged by: NAF Excavated on: October 9, 2019 Test Pit Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-6 Test Pit TP-11 Location: Southwest portion of site Approximate Elevation: 480’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 3 SM Tan silty SAND with gravel and roots, mottled at bottom contact (medium dense, moist) (weathered till) 3 - 8½ SM Gray silty SAND with gravel, moderately cemented (dense to very dense, moist) (glacial till) Terminated at 8¼ feet below ground surface. Mottling observed from 2 to 3 feet bgs. No caving observed. No groundwater seepage observed. Test Pit TP-12 Location: Vicinity of proposed body shop Approximate Elevation: 486’ Depth (ft) Soil Type Soil Description 0 - 1¼ - Topsoil/rootzone 1¼ - 3½ SM Tan to mottled gray silty SAND with gravel (medium dense, moist) (weathered till) 3½ - 8½ SM Gray silty SAND with gravel, moderately cemented (dense to very dense, moist) (glacial till) Terminated at 8½ feet below ground surface. Mottling observed from 2½ to 3½ feet bgs. No caving observed. No groundwater seepage observed. Test Pit TP-13 Location: Eastern portion of site Approximate Elevation: 484’ Depth (ft) Soil Type Soil Description 0 - 1 - Topsoil/rootzone 1 - 3½ SM Tan to mottled gray silty SAND with gravel (medium dense, moist) (weathered till) 3½ - 9 SM Gray silty SAND with gravel and occasional cobbles, moderately cemented (dense to very dense, moist) (glacial till) Terminated at 9 feet below ground surface. Mottling observed from 2 to 3½ feet bgs. No caving observed. No groundwater seepage observed. Logged by: NAF Excavated on: October 9, 2019 Test Pit Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-7 Test Pit TP-101 Location: Proposed detention pond Approximate Elevation: 471’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 3½ SM Tan to gray silty SAND with gravel (medium dense, moist) (weathered outwash) 3½ - 12 GP-GM Grayish brown GRAVEL with silt and sand (dense, moist to wet) (advance outwash) Terminated at 12 feet below ground surface. No mottling observed. No caving observed. Groundwater seepage observed below 7½ feet bgs. Test Pit TP-102 Location: Proposed detention pond Approximate Elevation: 469’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 3 SM Tan to gray silty SAND with gravel and scattered construction debris (medium dense, moist) (fill) 3 - 4 SM Gray silty SAND with gravel and occasional cobbles (dense, moist) (till fill) 4 - 9 GP-GM Grayish brown GRAVEL with silt and sand (dense, moist to wet) (advance outwash) Terminated at 8½ feet below ground surface. No mottling observed. No caving observed. Minor groundwater seepage observed at 8½ feet bgs. Logged by: NAF Excavated on: January 24, 2020 Test Pit Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-8 Test Pit TP-103 Location: NW portion of site Approximate Elevation: 446’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 2 SM Tan to brown silty SAND with small roots (medium dense, moist) (weathered outwash) 2 - 5 SP Brown SAND with trace gravel (medium dense, moist) (advance outwash) 5 - 9 GP Gray GRAVEL with sand (dense, moist) (advance outwash) Terminated at 9 feet below ground surface. No mottling observed. No caving observed. Groundwater seepage observed below 8 feet bgs. Logged by: NAF Excavated on: January 24, 2020 Test Pit Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-9 Pilot Infiltration Test PIT-1 Location: Northwest portion of site Approximate Elevation: 460’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil/rootzone ½ - 2 SM Tan silty SAND with some gravel and small roots (medium dense, moist) (weathered outwash) 2 - 6 SP Brown poorly-graded SAND with gravel (dense, moist) (advance outwash) Terminated at 6 feet below ground surface. No mottling observed. No caving observed. No groundwater seepage observed. Pilot Infiltration Test PIT-2 Location: Northwest of proposed shop Approximate Elevation: 442’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil ½ - 2½ SM Tan to dark brown silty SAND with some gravel (medium dense, moist) (weathered outwash) 2½ - 6½ GM Dark brown silty GRAVEL (medium dense to dense, moist) (advance outwash) Terminated at 6½ feet below ground surface. No mottling observed. No caving observed. No groundwater seepage observed. Logged by: NAF Excavated on: January 24, 2020 PIT Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-10 Pilot Infiltration Test PIT-3 Location: Northern portion of site Approximate Elevation: 452’ Depth (ft) Soil Type Soil Description 0 - ½ - Topsoil ½ - 2½ SM Tan to gray silty SAND and relict topsoil (loose to medium dense, moist) (fill / reworked soil) 2½ - 4½ SM Tan silty SAND with gravel (medium dense, moist) (weathered till) 4½ - 7½ SM Gray silty SAND with gravel (dense, moist) (glacial till) 7½ - 10 GM Tan silty GRAVEL with sand (dense, moist) (advance outwash) Terminated at 10 feet below ground surface. No mottling observed. No caving observed. No groundwater seepage observed. Logged by: NAF Excavated on: January 24, 2020 PIT Logs Proposed Commercial Development xxx South 320th Street Federal Way, Washington PN: 0921049-028, -139, -140, -160, -206, and -316 Doc ID: PapeKenworthNW.FederalWay.F February 2020 Figure A-11 0 5 10 15 20 25 30 450 445 440 435 430 425 420 Brown to gray silty sand with trace gravel (loose, moist) (SM) (fill) Grayish brown GRAVEL with silt and sand (medium dense to very dense, moist) (GP- GM) (advance outwash) Bottom of Boring Completed1/7/20 1 2 3 4 72 3 4 6 7 9 9 16 20 38 7 27 45 TOTAL DEPTH:21.5 EXCAVATION METHOD:LOGGED BY:NAF TOP ELEVATION:450 EXCAVATION COMPANY:Boretec HAMMER TYPE:Cat-head LATITUDE:EQUIPMENT:TD-85 HAMMER WEIGHT:140 lb LONGITUDE:NOTES: NOTES Proposed Commercial Development 1. Refer to log key for definition of symbols, abbreviations and codes 2. USCS designation is based on visual manual classification Federal Way, WA and selected lab testing 3. Groundwater level, if indicated, is for the date shown and may vary 4. N.E. = Not Encountered LOG OF BORING B-1 JOB: PapeKenworthNW.320th Sheet 1 of GeoResources, LLC FIG.DepthElevationSOIL DESCRIPTION Drilling Notes SampleSamplerSymbolTest Results (new title) TEST RESULTS 10 20 30 40 50 Penetration - (blow per foot) % Fines (<0.075mm) % Water Content Plastic Limit Liquid Limit Blow Count GroundWater1 0 5 10 15 20 25 30 450 445 440 435 430 425 Brown to gray silty SAND with gravel (medium dense, moist) (SM) (weathered advance) Grayish brown silty GRAVEL with sand (dense, moist) (GM) (advance outwash) Grayish brown well-graded GRAVEL with silt and sand (dense to very dense, moist) (GW- GM) (advance outwash) Bottom of Boring Completed1/7/20 1 2 3 4 100 73 15 23 25 25 23 20 50/3" 15 27 44 TOTAL DEPTH:20.5 EXCAVATION METHOD:LOGGED BY:NAF TOP ELEVATION:452 EXCAVATION COMPANY:Boretec HAMMER TYPE:Cat-head LATITUDE:EQUIPMENT:TD-85 HAMMER WEIGHT:140 lb LONGITUDE:NOTES: NOTES Proposed Commercial Development 1. Refer to log key for definition of symbols, abbreviations and codes 2. USCS designation is based on visual manual classification Federal Way, WA and selected lab testing 3. Groundwater level, if indicated, is for the date shown and may vary 4. N.E. = Not Encountered LOG OF BORING B-2 JOB: PapeKenworthNW.320th Sheet 1 of GeoResources, LLC FIG.DepthElevationSOIL DESCRIPTION Drilling Notes SampleSamplerSymbolTest Results (new title) TEST RESULTS 10 20 30 40 50 Penetration - (blow per foot) % Fines (<0.075mm) % Water Content Plastic Limit Liquid Limit Blow Count GroundWater1 0 5 10 15 20 25 30 450 445 440 435 430 425 420 Brown to gray silty sand with trace gravel (loose, moist) (SM) (fill) Brown to gray silty SAND with gravel (medium dense, moist) (SM) (weathered advance) Grayish brown GRAVEL with silt and sand (dense to very dense, moist to wet) (GP- GM) (advance outwash) Bottom of Boring Completed1/7/20 1 2 3 4 100 100 2 2 1 14 20 18 22 50/6" 18 50/4" TOTAL DEPTH:21.5 EXCAVATION METHOD:LOGGED BY:NAF TOP ELEVATION:451 EXCAVATION COMPANY:Boretec HAMMER TYPE:Cat-head LATITUDE:EQUIPMENT:TD-85 HAMMER WEIGHT:140 lb LONGITUDE:NOTES: NOTES Proposed Commercial Development 1. Refer to log key for definition of symbols, abbreviations and codes 2. USCS designation is based on visual manual classification Federal Way, WA and selected lab testing 3. Groundwater level, if indicated, is for the date shown and may vary 4. N.E. = Not Encountered LOG OF BORING B-3 JOB: PapeKenworthNW.320th Sheet 1 of GeoResources, LLC FIG.DepthElevationSOIL DESCRIPTION Drilling Notes SampleSamplerSymbolTest Results (new title) TEST RESULTS 10 20 30 40 50 Penetration - (blow per foot) % Fines (<0.075mm) % Water Content Plastic Limit Liquid Limit Blow Count GroundWater1 0 5 10 15 20 25 30 480 475 470 465 460 455 Tan silty SAND with gravel (medium dense, moist) (SM) (weathered till) Gray silty SAND with gravel (very dense, moist) (SM) (glacial till) Bottom of Boring Completed1/7/20 1 2 3 82+ 100 100 10 32 50/5" 50/4" 50/5" TOTAL DEPTH:15.5 EXCAVATION METHOD:LOGGED BY:NAF TOP ELEVATION:484 EXCAVATION COMPANY:Boretec HAMMER TYPE:Cat-head LATITUDE:EQUIPMENT:TD-85 HAMMER WEIGHT:140 lb LONGITUDE:NOTES: NOTES Proposed Commercial Development 1. Refer to log key for definition of symbols, abbreviations and codes 2. USCS designation is based on visual manual classification Federal Way, WA and selected lab testing 3. Groundwater level, if indicated, is for the date shown and may vary 4. N.E. = Not Encountered LOG OF BORING B-4 JOB: PapeKenworthNW.320th Sheet 1 of GeoResources, LLC FIG.DepthElevationSOIL DESCRIPTION Drilling Notes SampleSamplerSymbolTest Results (new title) TEST RESULTS 10 20 30 40 50 Penetration - (blow per foot) % Fines (<0.075mm) % Water Content Plastic Limit Liquid Limit Blow Count GroundWater1 0 5 10 15 20 25 30 470 465 460 455 450 445 Well-graded GRAVEL (dense, moist) (GW) (surficial crushed rock) Gray silty SAND with gravel (very dense, moist) (SM) (glacial till) Bottom of Boring Completed1/7/20 1 2 100 100 100 40 50/4" 50/2" 50/2" TOTAL DEPTH:15.5 EXCAVATION METHOD:LOGGED BY:NAF TOP ELEVATION:474 EXCAVATION COMPANY:Boretec HAMMER TYPE:Cat-head LATITUDE:EQUIPMENT:TD-85 HAMMER WEIGHT:140 lb LONGITUDE:NOTES: NOTES Proposed Commercial Development 1. Refer to log key for definition of symbols, abbreviations and codes 2. USCS designation is based on visual manual classification Federal Way, WA and selected lab testing 3. Groundwater level, if indicated, is for the date shown and may vary 4. N.E. = Not Encountered LOG OF BORING B-5 JOB: PapeKenworthNW.320th Sheet 1 of GeoResources, LLC FIG.DepthElevationSOIL DESCRIPTION Drilling Notes SampleSamplerSymbolTest Results (new title) TEST RESULTS 10 20 30 40 50 Penetration - (blow per foot) % Fines (<0.075mm) % Water Content Plastic Limit Liquid Limit Blow Count GroundWater1 Appendix B Laboratory Test Results These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By: Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 34.7 14.1 2.4 26.9 18.6 3.36 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM D 422 & ASTM D 1140) Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-2, S-1, D:6-8' Sample Number: 098502 Client: Project: Project No:Figure poorly graded gravel with sand 3.0 2.5 2.0 1.5 1.25 1 .75 .5 .3125 #4 #10 #20 #40 #60 #100 #200 100.0 100.0 100.0 88.4 88.4 75.4 65.3 58.2 55.3 51.2 48.8 43.0 21.9 7.1 4.3 3.3 NP NV NP GP A-1-a 39.6492 29.9556 14.0964 3.0690 0.5544 0.3315 0.2772 50.86 0.08 Moisture: 4.7-percent 10/9/19 10/15/19 NF KSS PM 10/9/19 Pape Group Proposed Commercial Development Pape.S320th PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-1 These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By: Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 13.5 11.1 4.5 13.4 24.9 32.66 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM D 422 & ASTM D 1140) Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-5, S-1, D: 5-7' Sample Number: 098506 Client: Project: Project No:Figure silty sand with gravel 3.0 2.5 2.0 1.5 1.25 1 .75 .5 .3125 #4 #10 #20 #40 #60 #100 #200 100.0 100.0 100.0 100.0 100.0 97.4 86.5 84.3 81.3 75.4 70.9 65.9 57.5 48.8 40.5 32.6 NP NV NP SM A-2-4(0) 20.8988 14.4894 0.5219 0.2683 Moisture: 8.7-percent 10/9/19 10/15/19 NF KSS PM 10/9/19 Pape Group Proposed Commercial Development Pape.S320th PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-2 These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By: Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 22.7 27.0 9.1 18.4 12.3 10.56 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM D 422 & ASTM D 1140) Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-8, S-2, D: 7-9' Sample Number: 098509 Client: Project: Project No:Figure poorly graded gravel with silt and sand 3.0 2.5 2.0 1.5 1.25 1 .75 .5 .3125 #4 #10 #20 #40 #60 #100 #200 100.0 100.0 100.0 100.0 100.0 91.1 77.3 67.8 62.4 50.3 41.2 32.8 22.8 15.6 12.3 10.5 NP NV NP GP-GM A-1-a 24.8048 22.3624 7.1814 4.6305 0.6982 0.2285 Moisture: 4.6-percent 10/9/19 10/15/19 NF KSS PM 10/9/19 Pape Group Proposed Commercial Development Pape.S320th PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-3 These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By: Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 7.1 9.6 3.9 10.2 21.5 47.76 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM D 422 & ASTM D 1140) Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-13, S-3, D: 2-3.5' Sample Number: 098514 Client: Project: Project No:Figure silty sand with gravel 3.0 2.5 2.0 1.5 1.25 1 .75 .5 .3125 #4 #10 #20 #40 #60 #100 #200 100.0 100.0 100.0 100.0 100.0 96.4 92.9 88.3 86.8 83.3 79.4 75.5 69.2 61.0 53.7 47.7 NP NV NP SM A-4(0) 14.7889 6.1111 0.2327 0.0980 Moisture: 9.7-percent 10/9/19 10/15/19 NF KSS PM 10/9/19 Pape Group Proposed Commercial Development Pape.S320th PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-4 These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By: Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 27.4 16.4 6.8 16.9 17.5 15.06 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM D 422 & ASTM D 1140) Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Source of Sample: B-2 Depth: 5 Sample Number: 1 Client: Project: Project No:Figure silty gravel with sand 3.0 2.5 2.0 1.5 1.25 1 .75 .5 .3125 #4 #10 #20 #40 #60 #100 #200 100.0 100.0 100.0 100.0 100.0 85.4 72.6 70.0 66.0 56.2 49.4 42.1 32.5 25.3 20.0 15.0 NP NV NP GM A-1-b 27.2488 25.1699 5.7966 2.1668 0.3527 Moisture: 8.5% 1/7/20 1/9/20 NAF KSS PM 1/7/20 Pape Kenworth NW Proposed Commercial Development PapeKenworthNW.320th PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-5 These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By: Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 12.8 36.7 12.2 19.7 9.9 8.76 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM D 422 & ASTM D 1140) Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Source of Sample: B-2 Depth: 20 Sample Number: 4 Client: Project: Project No:Figure well-graded gravel with silt and sand 3.0 2.5 2.0 1.5 1.25 1 .75 .5 .3125 #4 #10 #20 #40 #60 #100 #200 100.0 100.0 100.0 100.0 100.0 100.0 87.2 73.2 65.0 50.5 38.3 27.2 18.6 14.1 11.4 8.7 NP NV NP GW-GM A-1-a 20.2726 17.8574 6.6410 4.5801 1.0545 0.2784 0.1047 63.44 1.60 Moisture: 7.0% 1/7/20 1/9/20 NAF KSS PM 1/7/20 Pape Kenworth NW Proposed Commercial Development PapeKenworthNW.320th PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-6 These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By: Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 19.3 26.9 12.1 23.5 16.4 1.86 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: PIT-1, S-1 Sample Number: PIT1 S1 Client: Project: Project No:Figure poorly graded SAND with gravel 3.0 2.5 2.0 1.5 1.25 1.0 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 100.0 100.0 89.6 89.6 89.6 80.7 74.9 68.3 53.8 41.7 31.6 18.2 6.6 2.8 1.8 NP NV NP SP A-1-a 38.5116 21.8721 6.3959 3.6190 0.7839 0.3667 0.2920 21.90 0.33 Moisture: 5.1% 1/29/2020 MM KSS PM 1/24/2020 Pape Kenworth NW Proposed Commercial Development PapeKenworthNW.320th PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-7 These results are for the exclusive use of the client for whom they were obtained. They apply only to the samples tested and are not indicitive of apparently identical samples.Tested By: Checked By: Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 21.6 28.0 9.1 11.8 9.6 19.96 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: PIT-2, S-1 Sample Number: PIT2 S1 Client: Project: Project No:Figure silty GRAVEL with sand 3.0 2.5 2.0 1.5 1.25 1 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 100.0 100.0 91.7 91.7 85.3 78.4 70.3 62.2 50.4 41.3 35.4 29.5 24.8 22.0 19.9 NP NV NP GM A-1-b 29.9367 25.0571 8.3680 4.5826 0.4523 Moistue: 7.5% 1/24/2020 1/29/2020 MM KSS PM 1/24/2020 Pape Kenworth NW Proposed Commercial Development PapeKenworthNW.320th PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-8 BEARING RATIO TEST REPORT ASTM 01883-16 500 CBR at 95% Max. Density = 5.0% for 0.10 in. Penetration 11 9 ~5~1-- 400 V-17 -~ / 0 -g: 7 V m 125 blows I -0 'iii / L Q. 5 -V ! III 300 u V .1~~"----C I 1\1 -3 I III 'iii / 112 116 120 124 128 132 III Molded Density (pet) g: c V 0 .. 2 e -200 V III I~ c III / 1.6 /-D. L--------1.2 ~ 0 / L-------- 100 / ...-' -; ~ / .----'" 0.8 ~ ~ ------- 0.4 ~ ~ 0 0 0 0.1 0 .2 0.3 0.4 0.5 0 24 48 72 96 Penetration Depth (in.) Elapsed Time (hrs) Molded Soaked eBR "I.;) Linearity Surcharge Max. Density Percent of Moisture Density I Percent of 1 Moisture 0.10 in. 0.20 In. Correction (Ibs.) Swell (pet) Max. Dens. (%) (pet) Max. Dens. (%) (in.) (%) 1 • 117.4 90.9 9.6 ~ 90.1 I 15.5 3.7 4.8 -0.054 10 0.9 -I 2 • 124.3 96.2 9 .7 123 .0 *8 5.6 7.4 -0.048 10 1 ----- 3 • 129.1 99.9 9.8 127.1 98.4 11.4 8.4 11.2 -0.036 10 1.5 Material Description Max. Optimum uses ~:~. Moisture LL PI (%) Brown silty sand with gravel. -129.2 9.7 -- Project No: 066-19359 Test Description/Remarks: Project: Pape -S. 320th #098514 ASTMD1557 Source of Sample: Client Supplied Sample Sample Number: 19L556 Sample ID: 19L556 Sample Date: 1 0-9-19 Date: 10-9-19 6i1Krazan Figure Appendix C Global Stability Analyses 2.22.2 W W 2.22.2 Material Name Color Unit Weight (lbs/Ō3)Strength Type Cohesion (psf) Phi (deg)Water Surface Hu Type Ru Weathered Soil 125 Mohr-Coulomb 100 34 Water Surface AutomaƟcally Calculated Glacial Till 138 Mohr-Coulomb 500 38 None 0 Advance Outwash 135 Mohr-Coulomb 100 42 Water Surface AutomaƟcally Calculated600500400300 -100 -50 0 50 100 150 200 250 300 350 400 450 Analysis Description Global Stability Analysis Company GeoResources, LLCScale1:700Drawn By NAF File Name Pape.320th.PondStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 8.029 1.21.2 W W 1.21.2 Material Name Color Unit Weight (lbs/Ō3)Strength Type Cohesion (psf) Phi (deg)Water Surface Hu Type Ru Weathered Soil 125 Mohr-Coulomb 100 34 Water Surface AutomaƟcally Calculated Glacial Till 138 Mohr-Coulomb 500 38 None 0 Advance Outwash 135 Mohr-Coulomb 100 42 Water Surface AutomaƟcally Calculated 0.26 Safety Factor 0.0 0.3 0.5 0.8 1.0 1.3 1.5 1.8 2.0 2.3 2.5 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 4.8 5.0 5.3 5.5 5.8 6.0+600550500450400350300-100 -50 0 50 100 150 200 250 300 350 400 450 Analysis Description Global Stability Analysis Company GeoResources, LLCScale1:700Drawn By NAF File Name Pape.320th.PondStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 8.029 2.02.0 W W 2.02.0 Material Name Color Unit Weight (lbs/Ō3)Strength Type Cohesion (psf) Phi (deg)Water Surface Hu Type Hu Ru Weathered Soil 125 Mohr-Coulomb 100 34 Water Surface AutomaƟcally Calculated Glacial Till 138 Mohr-Coulomb 500 38 None 0 Advance Outwash 135 Mohr-Coulomb 100 42 Water Surface AutomaƟcally Calculated Till Fill / Liner 135 Mohr-Coulomb 100 35 Water Surface Custom 1 Saturated Advance Outwash 135 Mohr-Coulomb 100 42 None 0 Water 62.4 No strength None 0600550500450400350 300-100 -50 0 50 100 150 200 250 300 350 400 450 Analysis Description Global Stability Analysis Company GeoResources, LLCScale1:700Drawn By NAF File Name Pape.320th.PondStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 8.029 1.11.1 W W 1.11.1 0.26 Material Name Color Unit Weight (lbs/Ō3)Strength Type Cohesion (psf) Phi (deg)Water Surface Hu Type Hu Ru Weathered Soil 125 Mohr-Coulomb 100 34 Water Surface AutomaƟcally Calculated Glacial Till 138 Mohr-Coulomb 500 38 None 0 Advance Outwash 135 Mohr-Coulomb 100 42 None 0 Till Fill / Liner 135 Mohr-Coulomb 100 35 None 0 Saturated Advance Outwash 135 Mohr-Coulomb 100 42 Water Surface AutomaƟcally Calculated Safety Factor 0.0 0.3 0.5 0.8 1.0 1.3 1.5 1.8 2.0 2.3 2.5 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 4.8 5.0 5.3 5.5 5.8 6.0+700600500400-100 -50 0 50 100 150 200 250 300 350 400 450 Analysis Description Global Stability Analysis Company GeoResources, LLCScale1:700Drawn By NAF File Name Pape.320th.PondStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 8.029 2.02.0 W W 2.02.0 Material Name Color Unit Weight (lbs/Ō3)Strength Type Cohesion (psf) Phi (deg)Water Surface Hu Type Ru Weathered Soil 125 Mohr-Coulomb 100 34 Water Surface AutomaƟcally Calculated Glacial Till 138 Mohr-Coulomb 500 38 None 0 Advance Outwash 135 Mohr-Coulomb 100 42 None 0 Till Fill / Liner 135 Mohr-Coulomb 100 35 None 0 Saturated Advance Outwash 135 Mohr-Coulomb 100 42 Water Surface AutomaƟcally Calculated650 600550500450400350-100 -50 0 50 100 150 200 250 300 350 400 450 Analysis Description Global Stability Analysis Company GeoResources, LLCScale1:700Drawn By NAF File Name Pape.320th.PondStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 8.029 1.51.5 W W 1.51.5 Material Name Color Unit Weight (lbs/Ō3)Strength Type Cohesion (psf) Phi (deg)Water Surface Hu Type Ru Weathered Soil 125 Mohr-Coulomb 100 34 Water Surface AutomaƟcally Calculated Glacial Till 138 Mohr-Coulomb 500 38 None 0 Advance Outwash 135 Mohr-Coulomb 100 42 Water Surface AutomaƟcally Calculated Muck 80 Mohr-Coulomb 100 26 Water Surface AutomaƟcally Calculated Undocumented Fill 115 Mohr-Coulomb 0 30 Water Surface AutomaƟcally Calculated 0.26700 600500400-50 0 50 100 150 200 250 300 350 400 450 500 Analysis Description Global Stability Analysis Company GeoResources, LLCScale1:700Drawn By NAF File Name Pape.320th.WallStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 8.029 3.33.3 W W 3.33.3 Material Name Color Unit Weight (lbs/Ō3)Strength Type Cohesion (psf) Phi (deg)Water Surface Hu Type Ru Weathered Soil 125 Mohr-Coulomb 100 34 Water Surface AutomaƟcally Calculated Glacial Till 138 Mohr-Coulomb 500 38 None 0 Advance Outwash 135 Mohr-Coulomb 100 42 Water Surface AutomaƟcally Calculated Muck 80 Mohr-Coulomb 100 26 Water Surface AutomaƟcally Calculated Undocumented Fill 115 Mohr-Coulomb 0 30 None 0550500450400350300 250-50 0 50 100 150 200 250 300 350 400 450 500 Analysis Description Global Stability Analysis Company GeoResources, LLCScale1:700Drawn By NAF File Name Pape.320th.WallStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 8.029 1.81.8 W W 1.81.8 RuHu TypeWater Surface Allow Sliding Phi (deg) Cohesion (psf)Strength TypeUnit Weight (lbs/ ft3)ColorMaterial Name Automatically CalculatedWater Surface34100Mohr-Coulomb125Weathered Soil 0None38500Mohr-Coulomb138Glacial Till Automatically CalculatedWater Surface42100Mohr-Coulomb135Advance Outwash Automatically CalculatedWater Surface350Mohr-Coulomb130Structural Fill 0NoneYesInfinite strength130MSE Wall Automatically CalculatedWater Surface400Mohr-Coulomb135Gravel Backfill Automatically CalculatedWater Surface26100Mohr-Coulomb80Muck700600 500400-50 0 50 100 150 200 250 300 350 400 450 500 Scenario Proposed Retaining Walls - StaticGroupGroup 3 Company GeoResources, LLCDrawn By NAF File Name Pape.320th.WallStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 9.005 1.21.2 W W 1.21.2 RuHu TypeWater Surface Allow Sliding Phi (deg) Cohesion (psf)Strength TypeUnit Weight (lbs/ ft3)ColorMaterial Name Automatically Calculated Water Surface34100Mohr- Coulomb125Weathered Soil 0None38500Mohr- Coulomb138Glacial Till Automatically Calculated Water Surface42100Mohr- Coulomb135Advance Outwash Automatically Calculated Water Surface350Mohr- Coulomb130Structural Fill 0NoneYesInfinite strength130MSE Wall Automatically Calculated Water Surface400Mohr- Coulomb135Gravel Backfill Automatically Calculated Water Surface26100Mohr- Coulomb80Muck 0.26700 600500400-50 0 50 100 150 200 250 300 350 400 450 500 Scenario Proposed Retaining Walls - SeismicGroupGroup 3 Company GeoResources, LLCDrawn By NAF File Name Pape.320th.WallStability.rev1.slmdDate20191104 Project Pape.S320thSt SLIDEINTERPRET 9.005 Soundview Consultants LLC Environmental Assessment • Planning • Land Use Solutions 2907 Harborview Dr., Suite D, Gig Harbor, WA 98335 Phone: (253) 514-8952 Fax: (253) 514-8954 1779.0002 Papé Properties 1 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 To: Quinn Closson, Papé Properties Inc. File Number: 1779.0002 From: Matt DeCaro, Soundview Consultants LLC Revision Date: May 22, 2020 Re: Revised Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Papé Kenworth NW – Federal Way Dear Mr. Closson, Soundview Consultants LLC (SVC) conducted a wetland and fish and wildlife habitat assessment of an approximately 19.94-acre property located at 3014 South 320th Street and 31625 32nd Avenue South in Federal Way, Washington (Figure 1). The property consists of seven tax parcels located in the Southeast ¼ of Section 9, Township 21 North, Range 04 East, W.M. (King County Tax Parcel Numbers 0921049028, 0921049139, 0921049140, 0921049160, 0921049187, 0921049206 and 0921049316). SVC investigated the site to evaluate if any potentially regulated wetlands, streams, or other fish and wildlife habitat conservation areas are located on or adjacent to the subject property. The wetland assessment portion of this Technical Memorandum (SVC, 2019) was reviewed by the City’s third-party consultant ((Landau Associates, 2019) and subsequently approved by the City of Federal Way on December 24, 2019 (City of Federal Way, 2019). A revised Technical Memorandum (SVC, 2020) was submitted to include an administrative wetland buffer averaging plan to accommodate the proposed commercial development project by Papé Properties Inc. (Applicant). The March 2020 Technical Memorandum was reviewed by the City of Federal Way’s third-party consultant; this Technical Memorandum has been revised to address those comments (Landau Associates, 2020). Figure 1. Aerial Photograph of Subject Property. Technical Memorandum Subject Property Location 1779.0002 Papé Properties 2 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Background Data Prior to the site investigation, SVC staff conducted background research using the City of Federal Way’s Critical Areas Map, King County iMAP, Washington Department of Fish and Wildlife (WDFW) Priority Habitat and Species (PHS) and SalmonScape mapping tools, Washington Department of Natural Resources (DNR) stream typing system, U.S. Fish and Wildlife Service (USFWS) National Wetland Inventory (NWI), Natural Resource Conservation Service (NRCS) soil survey (Attachment B), and various orthophotographic resources. The Federal Way Critical Areas Map (Attachment C1), WDFW PHS map (Attachment C3), USFWS NWI map (Attachment C5), and King County iMap (Attachment C6) identify one potential wetland on the western portion of the subject property, extending offsite to the north and southwest. No other wetlands are identified on or within 225 feet of the subject property. No streams or other priority habitats and species are identified within 225 feet of the site by any of the critical area inventories, including by the Federal Way Critical Areas Map, WDFW SalmonScape (Attachment C2), WDFW PHS Map, DNR stream typing inventory (Attachment C4), or King County iMap. The nearest documented stream (Mill Creek) is mapped 0.5-mile to the east of the subject property. The NRCS soil map (Attachment C7) identifies the following soils on the subject property: two types of Alderwood gravelly sandy loam (8 to 15 percent and 15 to 30 percent slopes) and Seattle muck. Alderwood gravelly sandy loam (8 to 15 percent and 15 to 30 percent slopes) are listed as primarily non-hydric soils with potential hydric soil inclusions. Seattle muck is listed as a hydric soil (NRCS, 2019) and is mapped on the western portion of the site within the mapped wetland area. Abbreviated Project Description The proposed project will construct a truck maintenance building with areas for office, showroom and parts warehouse and a separate structure to be used as a body shop. Improvements and construction activities will include demolition of existing residential structures, grading, paved truck and trailer parking and maneuvering areas, stormwater facility, water and sanitary sewer extensions, landscaping, roadway improvements and franchise utility extensions. The subject property is currently undergoing an annexation process with the City of Federal Way. A boundary line adjustment will be processed to configure the seven existing lots to the new site layout. Methods Formal site investigations were performed by qualified SVC staff in June and September 2019 and May 2020. The investigations consisted of walk-through surveys of the subject property and any accessible areas within 225 feet of this area for potentially regulated wetlands, streams, and other fish and wildlife habitat conservation areas as specified in Federal Way Revised Code (FWRC) Chapter 19.145 (Environmentally Critical Areas). Wetlands, streams, and select fish and wildlife habitats and species are regulated features per FWRC Chapter 19.145 and subject to restricted uses/activities under the same title. Wetland boundaries were determined in accordance with FWRC 19.145.410(1) and as outlined in the U.S. Army Corps of Engineers (USACE) Wetlands Delineation Manual (Environmental Laboratory, 1987), as modified 1779.0002 Papé Properties 3 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 according to the guidelines established in the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region, Version 2.0 (USACE, 2010) and Field Indicators of Hydric Soils in the United States (USDA, 2018). Qualified SVC wetland scientists marked boundaries of any onsite wetlands with orange surveyor’s flagging labeled alpha-numerically and tied to vegetation along the wetland boundary. SVC only delineated the onsite wetland boundaries facing the proposed development; the remaining wetland boundaries were estimated using visual observations and/or aerial imagery. Pink surveyor’s flagging was labeled alpha-numerically and tied to 3-foot lath or vegetation at formal sampling locations (DP-1 through DP-6) to mark the points where detailed data was collected. Additional tests pits were excavated at regular intervals inside and outside of the wetland boundaries to further confirm the delineation. Following the delineation, the wetland flags were surveyed by a professional land survey company. Wetlands were classified using both the hydrogeomorphic (Brinson, 1993) and Cowardin (Cowardin, 1979; Federal Geographic Data Committee, 2013) classification systems. Following classification and assessment, wetlands were rated and categorized using the current Washington State Wetland Rating System for Western Washington (Hruby, 2014) and guidelines established in FWRC 19.145.420(1). The fish and wildlife habitat assessment was conducted during the same site visit by qualified fish and wildlife biologists. The experienced biologists made visual observations using stationary and walking survey methods for both aquatic and upland habitats noting any special habitat features or signs of fish and wildlife activity. SVC performed a follow-up investigation in May 2020 to assess vegetation conditions in the wetland buffer areas. Precipitation Precipitation data was obtained from the National Oceanic and Atmospheric Administration (NOAA) weather station at the Seattle-Tacoma International Airport Station in order to acquire percent of normal precipitation during and preceding the site investigation. A summary of data collected is provided in Table 1. Table 1. Precipitation Summary1. Site Visit Date Day Of Day Before 1 Week Prior 2 Weeks Prior 30 Days Prior (Observed/Normal) Year to Date (Observed/Normal)2 Percent of Normal3 6/13/2019 0.00 0.00 0.11 0.11 0.73/1.91 14.08/18.24 38/77 9/12/2019 0.24 0.00 1.16 1.16 1.61/1.13 18.38/21.09 142/87 1. Precipitation volume provided in inches. Data obtained from NOAA (http://w2.weather.gov/climate/xmacis.php?wfo=sew) for Sea-Tac International Airport. 2. Year-to-date precipitation is for the 2019 calendar year. 3. Percent of normal is for the 30 days prior/2019 calendar year. Precipitation levels during the September 2019 site investigation, when the formal delineation fieldwork was performed, were elevated for the previous 30 days (142 percent of normal) and within normal range for the 2018 calendar year (87 percent of normal). This precipitation data suggests that relatively normal hydrologic conditions were encountered during the September 2019 investigation which was performed near the end of Summer when conditions were generally dry, although greater than 1 inch of precipitation accumulation was reported for the previous week. The June 2019 1779.0002 Papé Properties 4 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 reconnaissance was performed earlier in the growing season during a period of relatively low precipitation. Such conditions were considered in making professional wetland determinations. Results The 19.89-acre subject property is located in an urban-residential setting in unincorporated King County. The southern portion of the site is developed with three single-family residences and a high voltage transmission line corridor. The northern portion of the property is developed with a single- family residence with a horse barn and multiple paddocks. The subject property abuts South 320th Street to the south; Interstate 5 to the west; an undeveloped, forested lot to the north; and an access road/32nd Avenue South to the west, with single-family residences beyond. Vegetation on the western portion of the site is generally dominated by a forested community of red alder (Alnus rubra), black cottonwood (Populus balsamifera), and western red cedar (Thuja plicata) with an understory of non-native invasive Himalayan blackberry (Rubus armeniacus), salmonberry (Rubus spectabilis), salal (Gaultheria shallon), red huckleberry (Vaccinium parvifolium), and trailing blackberry (Rubus ursinus). Where undeveloped and vegetated, the eastern portion of the site is generally dominated by bigleaf maple (Acer macrophyllum), black cottonwood, Himalayan blackberry, narrowleaf plantain (Plantago lanceolata), and various grasses. Topography is relatively flat on the eastern portion of the subject property with an elevation of approximately 485 feet above mean sea level (amsl), while the western portion of the site slopes moderately downward to the west to an elevation of approximately 420 feet amsl within a depression at the bottom of the Interstate 5 road embankment (Attachment C8). Wetland Findings SVC identified one potentially regulated wetland (Wetland A) on the subject property. The identified wetland contained indicators of wetland hydrology, hydric soils, and a predominance of hydrophytic vegetation according to current wetland delineation methodology. The onsite wetland is depicted on the site plan in Attachment A. No other potentially regulated wetlands, streams, and/or other fish and wildlife habitat conservation areas were observed on or within 225 feet of the site. The wetland data forms, wetland rating form, and wetland rating maps are provided in Attachments D, E, and F, respectively. A summary of the identified wetland is provided in Table 2 below. Table 2. Wetland Summary. Wetland Predominant Wetland Classification / Rating Wetland Size Onsite (SF) Buffer Width (feet)5 Cowardin1 HGM2 WSDOE3 City of Federal Way4 A PFO/ABE Depressional III III ~ 80,689 80 Table 1 Notes: 1. Cowardin et al. (1979) or NWI Class based on vegetation: PFO = Palustrine Forested, AB = Palustrine Aquatic Bed; Modifiers for Water Regime: E = Seasonally Flooded/Saturated 2. Brinson, M. M. (1993). 3. Current WSDOE wetland rating system for western Washington (Hruby, 2014). 4. FWRC 19.145.420(1) wetland definitions. 5. FWRC 19.145.420(2) wetland buffer standards. 1779.0002 Papé Properties 5 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Wetland A Wetland A is approximately 80,689 square feet (1.85acres) in size onsite and is located within a depressional area on the western portion of the subject property, extending offsite to the south and north. Hydrology for Wetland A is likely provided primarily by a high groundwater table, direct precipitation and surface sheet flow, with some stormwater runoff from South 320th Street and Interstate 5. Wetland vegetation onsite is dominated by red alder, hardhack (Spiraea douglasii), crab apple (Malus fusca), salmonberry (Rubus spectabilis), twinberry honeysuckle (Lonicera involucrata), yellow pond lily (Nuphar polysepala), water parsley (Oenanthe sarmentosa), nodding beggartick (Bidens cernua), and smartweed (Persicaria sp). Soil within Wetland A met hydric soil indicator F1 (Loamy Mucky Mineral). Wetland A is a Palustrine Forested/Aquatic Bed, Seasonally Flooded/Saturated wetland (PFO/ABE). Per FWRC 19.145.420(2), Wetland A is classified as a Category III depressional wetland with a low habitat score of 5 total points. Wetland A does not appear to contain an outlet, but instead is impounded by Interstate 5 to the west and South 320th Street to the south. The wetland receives overflow from upgradient storm ponds located on the opposite side of 32nd Avenue South, at the far northern offsite extent of the wetland (greater than 600 feet north of the subject property). No surface water outlet was identified. The southern portion of the wetland (approximately 17 percent of the total wetland area) ponds long enough during the growing season to exhibit aquatic bed plants, but the wetland lacked surface water during our September 2019 investigation. Our observations during multiple seasons indicate that the water storage during wet periods is less than 2 feet of water in the seasonally ponded area, due in part to the shallow nature of the ponded portion of the depression. The seasonally ponded area (17 percent) does not comprise greater than 25 percent of the total wetland area. Regulatory Considerations The wetland assessment portion of this Technical Memorandum (SVC, 2019) was reviewed by the City’s third-party consultant ((Landau Associates, 2019) and subsequently approved by the City of Federal Way on December 24, 2019 (City of Federal Way, 2019). A revised Technical Memorandum (SVC, 2020) was then submitted to include an administrative wetland buffer averaging plan to accommodate the proposed commercial development project. The March 2020 Technical Memorandum was reviewed by the City of Federal Way’s third-party consultant; this Technical Memorandum has been revised to address those comments (Landau Associates, 2020). These review letters are provided in Attachments G and H of this Technical Memorandum, respectfully. Wetland Buffer Requirements FWRC 19.145.420.(1) has adopted the current wetland rating system used by WSDOE. Category III wetlands score between 16 and 19 points, generally provide a moderate level of function, have usually been disturbed in some way, and are often less diverse and/or more isolated in the landscape than Category II wetlands (Hruby, 2014). Wetland A is a Category III depressional wetland with a low habitat score of 5 points which requires a standard 80-foot buffer per FWRC 19.145.420(2). An additional 5-foot building setback is required from the outer wetland buffer edge per FWRC 19.145.160. 1779.0002 Papé Properties 6 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Abbreviated State and Federal Considerations Onsite Wetland A is potentially unregulated under Section 404 of the Clean Water Act (CWA) due to its lack of surface water connection and distance to Waters of the U.S. Should the U.S. Army Corps of Engineers not assert jurisdiction under the CWA, then WSDOE would assert jurisdiction as WSDOE regulates natural wetlands and surface waters under RCW 90.48. The proposed project avoids direct impacts to the identified wetland, therefore state and federal wetland authorizations will not be required. Proposed Buffer Modifications The proposed project includes site development for parts and service, sales, office space, parking, and equipment. Minor administrative wetland buffer averaging is proposed as allowed under FWRC 19.145.440(5) (Buffer Averaging) to accommodate the proposed commercial development. A site plan is provided in Attachment A of this Technical Memorandum. Mitigation Sequencing Mitigation sequencing for the proposed project is required under FWRC 19.145.130 to demonstrate that all reasonable efforts have been examined with the intent to avoid and minimize impacts to critical areas, the definition of which includes wetland buffers per FWRC 19.145.030. The following discussion addresses specific actions taken to fulfill mitigation sequencing for this project. 1. Avoiding the impact altogether by not taking a certain action or parts of actions. The proposed project will avoid direct impacts to Wetland A; however, minor administrative buffer averaging is required in the northwest portion of the subject property. The site plan has undergone numerous revisions in attempts to avoid the standard buffer area entirely; however, due to the existing BPA powerline corridor, the need for required fire access and drive aisles for traffic movement, and topographical constraints, the northwest corner of proposed development requires limited buffer decrease by a minor 951 square feet to accommodate necessary grading and retaining wall installation. 2. Minimizing impacts by limiting the degree or magnitude of the action and its implementation by using appropriate technology or by taking affirmative steps to reduce impacts. The proposed project has undergone several variations in site design to minimize buffer impacts to the greatest extent feasible. The only proposed activity that will impact the standard buffer area is the required grading and retaining wall construction in the northwest corner of the subject property which will require 951 square feet of buffer reduction in an area that is currently degraded by fill material and invasive vegetation including Himalayan blackberry, poison hemlock (Conium maculatum), and English holly (Ilex aquifolium). A few native species are present in the buffer reduction area such as red alder, cascara buckthorn (Frangula purshiana), and western swordfern (Polystichum munitum), though the majority of the area is dominated by Himalayan blackberry. Although a 25 percent buffer reduction is technically allowed per FWRC 19.145.440(5), the project proposes a maximum 15 percent buffer decrease (down to 68 feet) at the narrowest point. All appropriate best management practices (BMPs) and temporary erosion and sediment control (TESC) measures, including construction fencing and silt fencing, will be implemented and maintained during construction on the site to minimize any potential temporary construction impacts to the remaining buffer area. 1779.0002 Papé Properties 7 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 3. Rectifying the impact by repairing, rehabilitating, or restoring the affected environment to the conditions existing at the time of the initiation of the project. Not applicable. Minor, administrative wetland buffer averaging is proposed which does not require traditional mitigation actions (e.g., buffer enhancement) per FWRC 19.145.440(5). 4. Reducing or eliminating the impact over time by preservation and maintenance operations during the life of the action; If required by the City, the modified buffer area will be placed in a separate critical areas tract in accordance with 19.145.150. Because the project does not propose a subdivision, short subdivision, or binding site plan, however, this requirement is not anticipated. 5. Compensating for the impact by replacing, enhancing, or providing substitute resources or environments; and The Applicant proposes buffer averaging to result in a net increase of protected wetland buffer area. Buffer reduction of 951 square feet is proposed in one select location in the northwest corner to facilitate necessary grading and retaining wall construction; to compensate for the minor impacts, buffer addition of 1,422 square feet is proposed within a higher functioning portion of the general buffer area (Attachment A) that contains native vegetation and does not exhibit past anthropogenic disturbances. The proposal will result in a net gain of 471 square feet of protective buffer. Currently, the area selected for buffer reduction is the lower functioning portion of the buffer area. It currently has low species diversity and contains non-native invasive species such as Himalayan blackberry and fill material. The proposed buffer averaging plan will improve ecological functions by reducing the lower functioning portion of the buffer and adding to the higher functioning portion of the buffer, resulting in an overall net increase in wetland buffer area and gain in ecological functions. 6. Monitoring the hazard or other required mitigation and taking remedial action when necessary. Because buffer averaging is proposed and no restoration or enhancement actions are required, formal monitoring is not warranted. Wetland Buffer Averaging Wetland A is subject to a standard 80-foot buffer and additional 5-foot building setback. To accommodate the proposed project objectives, minor buffer averaging is proposed per FWRC 19.145.440(5). A site plan depicting the proposed buffer averaging plan is included in Attachment A of this Technical Memorandum. Wetland buffer averaging may be permitted when all of the following criteria are met: a. The total area of the buffer after averaging is equal to the area required without averaging; The proposed buffer averaging plan will result in a net gain of 471 square feet of protective buffer. Specifically, approximately 951 square feet of onsite buffer area will be decreased to facilitate necessary grading and proposed retaining wall in the northwest portion of the site, and approximately 1,422 square feet will be increased to the south of the buffer decrease area. The modified buffer line will maintain the natural, parallel buffer from the wetland edge to the greatest extent feasible. 1779.0002 Papé Properties 8 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 May 22, 2020 b. The buffer is increased adjacent to the higher functioning area of habitat or more sensitive portion of the wetland and decreased adjacent to the lower functioning or less sensitive portion; The buffer increase area (1,422 square feet) is located within and adjacent to a higher functioning habitat area as it contains native vegetation and does not exhibit past anthropogenic disturbances. The buffer increase area consists of native vegetation with an overstory of western red cedar, red alder, and bigleaf maple, and an understory of salal, snowberry (Symphoricarpos albus), vine maple (Acer circinatum), western swordfern, Pacific bleeding heart (Dicentra formosa), and Siberian spring beauty (Claytonia sibirica). The buffer increase area exhibits native species diversity within all three strata and minimal non-native invasive species present. Whereas, the buffer decrease area is located within a relatively low-functioning area from a habitat standpoint due to the presence of non-native invasive species such as Himalayan blackberry and fill material. Representative photographs of the buffer decrease and increase areas are provided in Attachment B. c. The buffer at its narrowest point is not reduced to less than 75 percent of the required width; and The modified buffer will be never be less than 75 percent (60 feet) of the standard width (80 feet). Although a 25 percent buffer reduction is technically allowed per FWRC 19.145.440(5), the project proposes a maximum 15 percent buffer decrease (down to 68 feet) at the narrowest point. The 5-foot building setback is provided along the entire length of the onsite buffer. d. Unless authorized in writing by a consenting neighboring property owner, the averaging will remain on the subject property. The buffer averaging plan will remain on the subject property. Conclusions SVC identified and delineated one Category III wetland (Wetland A) on the subject property. Wetland A has a low habitat score of 5 points and, therefore, requires a standard 80-foot buffer and additional 5-foot building setback as approved by the City of Federal Way (2019). No other wetlands, streams, or other fish and wildlife habitat conservation areas were identified on or within 225 feet of the subject property. To accomplish the Applicant’s commercial development objectives, minor administrative wetland buffer averaging is necessary as indicated on the site plan provided in Attachment A. The proposed buffer averaging plan conforms to FWRC 19.145.440(5) and will result in a net gain of ecological function onsite relative to standard buffer requirements. If you have any questions, please contact me at your earliest convenience. Sincerely, ____________________________ _________________ Matt DeCaro Date Senior Scientist/Environmental Planner 1779.0002 Papé Properties 9 Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 References Brinson, M. M. 1993. A hydrogeomorphic classification for wetlands, Technical Report WRP-DE-4, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. City of Federal Way. 2019. File #19-105322-AD; 3rd Party Wetland Review Letter. December 24, 2019. Cowardin, L.M. V. Carter, F. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish & Wildlife Service. Washington D.C. Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual. Technical Report Y-87-1, US Army Engineer Waterways Experiment Station, Vicksburg, Mississippi. Federal Way Revised Code (FWRC). 2018. Title 19.145 – Environmentally Critical Areas. Website: https://www.codepublishing.com/WA/FederalWay/#!/FederalWay19/FederalWay19145.htm l#19.145 Current through July 02, 2019. Hitchcock, C.L. and A. Cronquist. 1973. Flora of the Pacific Northwest. University of Washington Press. Seattle, Washington. Hruby, T. 2014. Washington State Wetland Rating System for Western Washington: 2014 Update. Washington State Department of Ecology Publication # 14-06-029. Landau Associates, Inc. 2019. Peer Review Pape Wetland Delineation – Federal Way, Washington Technical Memorandum. December 23, 2019. Lichvar, R.W., D.L. Banks, W.N. Kirchner, and N.C. Melvin. 2016. The National Wetland Plant List: 2016 wetland ratings. Phytoneuron 2016-30: 1-17. Published 28 April 2016. ISSN 2153 733X Natural Resources Conservation Service (NRCS). 2019. Hydric Soils List: King County Area, Washington. Website: https://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/use/hydric/. Sheldon, D., T. Hruby, P. Johnson, K. Harper, A. McMillan, T. Granger, S. Stanley, and E. Stockdale. 2005. Wetlands in Washington State - Volume 1: A Synthesis of the Science. Washington State Department of Ecology. Publication #05-06-006. Olympia, WA. March 2005. Snyder, Dale E., Philip S. Gale, Russell F. Pringle. 1973. Soil Survey of King County Area, Washington. United States Department of Agriculture, Soil Conservation Service, in cooperation with the Washington Agricultural Experiment Station. Munsell Color. 2000. Munsell soil color charts. New Windsor, New York. Soundview Consultants LLC. 2019. Wetland and Fish and Wildlife Habitat Assessment Technical Memorandum. October 29, 2019. U.S. Army Corps of Engineers (USACE). 2010. Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0), ed. J. S. Wakeley, R. W. Lichvar, and C. V. Noble. ERDC/EL TR-10-13. Vicksburg, MS: U.S. Army Engineer Research and Development Center. U.S. Department of Agriculture, Natural Resources Conservation Service. 2018. Field Indicators of Hydric Soils in the United States, Version 8.2. L.M. Vasilas, G.W. Hurt, and J.F. Berkowitz (eds.). USDA, NRCS, in cooperation with the National Technical Committee for Hydric Soils. 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment A – Existing Conditions Exhibit and Site Plan !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!'& '&'& '& '& '& A-9 A-8 A-7 A-6 A-5 A-4 A-3 A-2 A-1 DP-6 DP-5 A-24 A-23 A-22 A-21 A-19 A-20 DP-2 DP-4 DP-3 A-18 A-17 A-16 A-15 A-14 A-13 A-12 A-11 A-10 DP-1 King County SOUTH 320TH & I5 - EXISTING CONDITIONS ¢ 0 180 36090 Fee t 3014 S 320TH STFEDERAL WAY, WA 98003KING COUNTY PARCEL NUM BER:0921049028, 0921049139, 0921049140, 0921049160, 0921049187, 0921049206 & 0921049316 SOUTH 320TH & I5 www.soundviewconsultants.com 2907 Harbor view Dr., Suite D, Gig Harbor, WA 98335Phone: (253) 514-8952 Fax: (253) 514-8954 Soundview ConsultantsEnvironmental Assessment • Planning • Land Use SolutionsLLC DATE: JOB: BY: SCALE: FIGURE NO. 9/23/2019 1779.0002 DLS/RJK 11 " = 180 ' àààààààà à à Wetland '&Data Point Wetland Flag !!!!!!Drainage 80' Wetland Buffer !!5' Building Setback Site Boundary Wetland ACategory III 80' Projected Buffer Based on2014 Weltand Rating and Federal Way RevisedCode Buf fer Requirements SH0PPARTS WAREHOUSESHOWROOMOFFICEBODY SHOPBUILDING ABUILDING BS. 316TH ST.S. 320TH STREET32ND AVE. SOVERHEAD TRANSMISSION LINES, OLYMPIC PIPELINE AND CONST. EASEMENTSNO BUILDING STRUCTURES WITHIN THESE LINESSP-1OVERALL SITE PLANVICINITY MAPSITE DATA:ORAGEEX. SITE AND BUILDING AREAS:SITEOVERALL SITE PLANSHEET INDEX:H.G. K i m u r a A r c h i t e c t P L L CRenton, Washington 98058Fax 425.271.2383E-MAIL: hgkimura@comcast.netTel 425.271.187518012 W. Lake Desire Drive SEP.O. Box 59415Federal Way, WA 98001NE Corner I-5 and S. 320th StreetPAPE - Kenworth NW - Federal Way3-6-2020 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment B – Photographs Data Plot DP-1 DP-1 Soils DP-1 Setting Data Plot DP-2 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 DP-2 Soils DP-2 Setting Data Plot DP-3 DP-3 Soils 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 DP-3 Setting Data Plot DP-4 DP-4 Soils DP-4 Setting 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Data Plot DP-5 DP-5 Soils DP-5 Setting Data Plot DP-6 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 DP-6 Soils DP-6 Setting Representative Photograph of Seasonally Ponded Portion of Wetland A 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Existing Vegetation in Buffer Decrease Area. Note heavy cover of Himalayan blackberry. Proposed Buffer Increase Area 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C – Background Information This attachment includes a City of Federal Way Wetland Inventory (C1); WDFW SalmonScape Map (C2); WDFW PHS Map (C3); DNR Stream Typing Map (C4); USFWS NWI Map (C5); King County Sensitive Areas iMap (C6); NRCS Soil Survey Map (C7); and King County Topographic Map (C8). 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C1 – City of Federal Way Wetland Inventory Subject Property Location 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C2 – WDFW SalmonScape Map Subject Property Location 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C3 – WDFW PHS Map Subject Property Location 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C4 – DNR Stream Typing Map Subject Property Location 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C5 – USFWS NWI Map Subject Property Location 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C6 – King County Sensitive Areas iMap Subject Property Location 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C7 – NRCS Soil Survey Map Subject Property Location 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment C8 – King County Topographic Map Subject Property Location 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment D – Data Forms US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 WETLAND DETERMINATION DATA FORM – Western Mountains, Valleys, and Coast Region Project/Site: City/County: Sampling Date: Applicant/Owner: State: Sampling Point: Investigator(s): Section, Township, Range: Landform (hillslope, terrace, etc.): Local relief (concave, convex, none): Slope (%): Subregion (LRR): Lat: Long: Datum: Soil Map Unit Name: NWI classification: Are climatic / hydrologic conditions on the site typical for this time of year? Yes No (If no, explain in Remarks.) Are Vegetation , Soil , or Hydrology significantly disturbed? Are “Normal Circumstances” present? Yes No Are Vegetation , Soil , or Hydrology naturally problematic? (If needed, explain any answers in Remarks.) SUMMARY OF FINDINGS – Attach site map showing sampling point locations, transects, important features, etc. Hydrophytic Vegetation Present? Yes No Hydric Soil Present? Yes No Wetland Hydrology Present? Yes No Is the Sampled Area within a Wetland? Yes No Remarks: VEGETATION – Use scientific names of plants. Absolute Dominant Indicator Tree Stratum (Plot size: 30 ft) % Cover Species? Status 1. 2. 3. 4. = Total Cover Sapling/Shrub Stratum (Plot size: 15 ft) 1. 2. 3. 4. 5. = Total Cover Herb Stratum (Plot size: 5 ft) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. = Total Cover Woody Vine Stratum (Plot size: 30 ft) 1. 2. = Total Cover % Bare Ground in Herb Stratum Dominance Test worksheet: Number of Dominant Species That Are OBL, FACW, or FAC: (A) Total Number of Dominant Species Across All Strata: (B) Percent of Dominant Species That Are OBL, FACW, or FAC: (A/B) Prevalence Index worksheet: Total % Cover of: Multiply by: OBL species x 1 = FACW species x 2 = FAC species x 3 = FACU species x 4 = UPL species x 5 = Column Totals: (A) (B) Prevalence Index = B/A = Hydrophytic Vegetation Indicators: Rapid Test for Hydrophytic Vegetation Dominance Test is >50% Prevalence Index is ≤3.01 Morphological Adaptations1 (Provide supporting data in Remarks or on a separate sheet) Wetland Non-Vascular Plants1 Problematic Hydrophytic Vegetation1 (Explain) 1Indicators of hydric soil and wetland hydrology must be present, unless disturbed or problematic. Hydrophytic Vegetation Present? Yes No Remarks: 1779.0002 - South 320th Street & I-5 Federal Way / King 09/12/2019 Pape Properties Inc WA DP-1 Rachael Hyland, Jake Layman 9 / 21N / 04E Depression None 2 A2 47.316476 -122.29508700 WGS 84 Seattle Muck PEM1F All three wetland criteria met. Data collected within southern portion of Wetland A. Alnus rubra 65 Yes FAC 3 3 65 100% Rubus spectabilis 5 Yes FAC 5 Solanum dulcamara 40 Yes FAC Nuphar polysepala 10 No OBL Persicaria hydropiperoides 5 No OBL 55 0 45 Hydrophytic vegetation met through dominance test. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 SOIL Sampling Point: Profile Description: (Describe to the depth needed to document the indicator or confirm the absence of indicators.) Depth Matrix Redox Features (inches) Color (moist) % Color (moist) % Type1 Loc2 Texture Remarks 1Type: C=Concentration, D=Depletion, RM=Reduced Matrix, CS=Covered or Coated Sand Grains. 2Location: PL=Pore Lining, M=Matrix. Hydric Soil Indicators: (Applicable to all LRRs, unless otherwise noted.) Indicators for Problematic Hydric Soils3: Histosol (A1) Sandy Redox (S5) 2 cm Muck (A10) Histic Epipedon (A2) Stripped Matrix (S6) Red Parent Material (TF2) Black Histic (A3) Loamy Mucky Mineral (F1) (except MLRA 1) Very Shallow Dark Surface (TF12) Hydrogen Sulfide (A4) Loamy Gleyed Matrix (F2) Other (Explain in Remarks) Depleted Below Dark Surface (A11) Depleted Matrix (F3) Thick Dark Surface (A12) Redox Dark Surface (F6) 3Indicators of hydrophytic vegetation and Sandy Mucky Mineral (S1) Depleted Dark Surface (F7) wetland hydrology must be present, Sandy Gleyed Matrix (S4) Redox Depressions (F8) unless disturbed or problematic. Restrictive Layer (if present): Type:________________________________ Depth (inches):________________________ Hydric Soil Present? Yes No Remarks: HYDROLOGY Wetland Hydrology Indicators: Primary Indicators (minimum of one required; check all that apply) Secondary Indicators (2 or more required) Surface Water (A1) Water-Stained Leaves (B9) (except MLRA Water-Stained Leaves (B9) (MLRA 1, 2, High Water Table (A2) 1, 2, 4A, and 4B) 4A, and 4B) Saturation (A3) Salt Crust (B11) Drainage Patterns (B10) Water Marks (B1) Aquatic Invertebrates (B13) Dry-Season Water Table (C2) Sediment Deposits (B2) Hydrogen Sulfide Odor (C1) Saturation Visible on Aerial Imagery (C9) Drift Deposits (B3) Oxidized Rhizospheres along Living Roots (C3) Geomorphic Position (D2) Algal Mat or Crust (B4) Presence of Reduced Iron (C4) Shallow Aquitard (D3) Iron Deposits (B5) Recent Iron Reduction in Tilled Soils (C6) FAC-Neutral Test (D5) Surface Soil Cracks (B6) Stunted or Stressed Plants (D1) (LRR A) Raised Ant Mounds (D6) (LRR A) Inundation Visible on Aerial Imagery (B7) Other (Explain in Remarks) Frost-Heave Hummocks (D7) Sparsely Vegetated Concave Surface (B8) Field Observations: Surface Water Present? Yes No Depth (inches): Water Table Present? Yes No Depth (inches): Saturation Present? Yes No Depth (inches): (includes capillary fringe) Wetland Hydrology Present? Yes No Describe Recorded Data (stream gauge, monitoring well, aerial photos, previous inspections), if available: Remarks: DP-1 0 - 5 10YR 2/2 100 ----SaLo Mucky sandy loam 5 - 14 10YR 2/1 100 ----SaLo Mucky sandy loam with cobble and gravel None -- Hydric soil indicators met through indicator F1. None 18 14 Hydrologic criteria observed through secondary indicators B9, C2, and D2. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 WETLAND DETERMINATION DATA FORM – Western Mountains, Valleys, and Coast Region Project/Site: City/County: Sampling Date: Applicant/Owner: State: Sampling Point: Investigator(s): Section, Township, Range: Landform (hillslope, terrace, etc.): Local relief (concave, convex, none): Slope (%): Subregion (LRR): Lat: Long: Datum: Soil Map Unit Name: NWI classification: Are climatic / hydrologic conditions on the site typical for this time of year? Yes No (If no, explain in Remarks.) Are Vegetation , Soil , or Hydrology significantly disturbed? Are “Normal Circumstances” present? Yes No Are Vegetation , Soil , or Hydrology naturally problematic? (If needed, explain any answers in Remarks.) SUMMARY OF FINDINGS – Attach site map showing sampling point locations, transects, important features, etc. Hydrophytic Vegetation Present? Yes No Hydric Soil Present? Yes No Wetland Hydrology Present? Yes No Is the Sampled Area within a Wetland? Yes No Remarks: VEGETATION – Use scientific names of plants. Absolute Dominant Indicator Tree Stratum (Plot size: 30 ft) % Cover Species? Status 1. 2. 3. 4. = Total Cover Sapling/Shrub Stratum (Plot size: 15 ft) 1. 2. 3. 4. 5. = Total Cover Herb Stratum (Plot size: 5 ft) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. = Total Cover Woody Vine Stratum (Plot size: 30 ft) 1. 2. = Total Cover % Bare Ground in Herb Stratum Dominance Test worksheet: Number of Dominant Species That Are OBL, FACW, or FAC: (A) Total Number of Dominant Species Across All Strata: (B) Percent of Dominant Species That Are OBL, FACW, or FAC: (A/B) Prevalence Index worksheet: Total % Cover of: Multiply by: OBL species x 1 = FACW species x 2 = FAC species x 3 = FACU species x 4 = UPL species x 5 = Column Totals: (A) (B) Prevalence Index = B/A = Hydrophytic Vegetation Indicators: Rapid Test for Hydrophytic Vegetation Dominance Test is >50% Prevalence Index is ≤3.01 Morphological Adaptations1 (Provide supporting data in Remarks or on a separate sheet) Wetland Non-Vascular Plants1 Problematic Hydrophytic Vegetation1 (Explain) 1Indicators of hydric soil and wetland hydrology must be present, unless disturbed or problematic. Hydrophytic Vegetation Present? Yes No Remarks: 1779.0002 - South 320th Street & I-5 Federal Way / King 09/12/2019 Pape Properties Inc WA DP-2 Rachael Hyland, Jake Layman 9 / 21N / 04E Hillslope Convex 5 A2 47.316490 -122.29494723 WGS 84 Alderwood gravelly sandy loam N/A No wetland criteria met. Data collected east of Wetland A in southern portion of the site. Alnus rubra 40 Yes FAC 2 5 40 40% Gaultheria shallon 25 Yes FACU Spiraea douglasii 15 Yes FACW Rubus spectabilis 10 No FAC Malus fusca 5 No FACW 55 Pteridium aquilinum 20 Yes FACU Rubus ursinus 15 Yes FACU Polystichum munitum 5 No FACU 40 0 60 No hydrophytic vegetation criteria met; prevalence index not warranted due to lack of wetland hydrology and hydric soils. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 SOIL Sampling Point: Profile Description: (Describe to the depth needed to document the indicator or confirm the absence of indicators.) Depth Matrix Redox Features (inches) Color (moist) % Color (moist) % Type1 Loc2 Texture Remarks 1Type: C=Concentration, D=Depletion, RM=Reduced Matrix, CS=Covered or Coated Sand Grains. 2Location: PL=Pore Lining, M=Matrix. Hydric Soil Indicators: (Applicable to all LRRs, unless otherwise noted.) Indicators for Problematic Hydric Soils3: Histosol (A1) Sandy Redox (S5) 2 cm Muck (A10) Histic Epipedon (A2) Stripped Matrix (S6) Red Parent Material (TF2) Black Histic (A3) Loamy Mucky Mineral (F1) (except MLRA 1) Very Shallow Dark Surface (TF12) Hydrogen Sulfide (A4) Loamy Gleyed Matrix (F2) Other (Explain in Remarks) Depleted Below Dark Surface (A11) Depleted Matrix (F3) Thick Dark Surface (A12) Redox Dark Surface (F6) 3Indicators of hydrophytic vegetation and Sandy Mucky Mineral (S1) Depleted Dark Surface (F7) wetland hydrology must be present, Sandy Gleyed Matrix (S4) Redox Depressions (F8) unless disturbed or problematic. Restrictive Layer (if present): Type:________________________________ Depth (inches):________________________ Hydric Soil Present? Yes No Remarks: HYDROLOGY Wetland Hydrology Indicators: Primary Indicators (minimum of one required; check all that apply) Secondary Indicators (2 or more required) Surface Water (A1) Water-Stained Leaves (B9) (except MLRA Water-Stained Leaves (B9) (MLRA 1, 2, High Water Table (A2) 1, 2, 4A, and 4B) 4A, and 4B) Saturation (A3) Salt Crust (B11) Drainage Patterns (B10) Water Marks (B1) Aquatic Invertebrates (B13) Dry-Season Water Table (C2) Sediment Deposits (B2) Hydrogen Sulfide Odor (C1) Saturation Visible on Aerial Imagery (C9) Drift Deposits (B3) Oxidized Rhizospheres along Living Roots (C3) Geomorphic Position (D2) Algal Mat or Crust (B4) Presence of Reduced Iron (C4) Shallow Aquitard (D3) Iron Deposits (B5) Recent Iron Reduction in Tilled Soils (C6) FAC-Neutral Test (D5) Surface Soil Cracks (B6) Stunted or Stressed Plants (D1) (LRR A) Raised Ant Mounds (D6) (LRR A) Inundation Visible on Aerial Imagery (B7) Other (Explain in Remarks) Frost-Heave Hummocks (D7) Sparsely Vegetated Concave Surface (B8) Field Observations: Surface Water Present? Yes No Depth (inches): Water Table Present? Yes No Depth (inches): Saturation Present? Yes No Depth (inches): (includes capillary fringe) Wetland Hydrology Present? Yes No Describe Recorded Data (stream gauge, monitoring well, aerial photos, previous inspections), if available: Remarks: DP-2 0 - 6 5YR 2.5/1 100 ----SaLo Sandy loam with organics 6 - 12 5YR 3/2 100 ----SaLo Sandy loam 12 - 14 10YR 3/3 100 ----SaLo Gravelly sandy loam None -- No hydric soil indicators. None None None No hydrologic criteria met. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 WETLAND DETERMINATION DATA FORM – Western Mountains, Valleys, and Coast Region Project/Site: City/County: Sampling Date: Applicant/Owner: State: Sampling Point: Investigator(s): Section, Township, Range: Landform (hillslope, terrace, etc.): Local relief (concave, convex, none): Slope (%): Subregion (LRR): Lat: Long: Datum: Soil Map Unit Name: NWI classification: Are climatic / hydrologic conditions on the site typical for this time of year? Yes No (If no, explain in Remarks.) Are Vegetation , Soil , or Hydrology significantly disturbed? Are “Normal Circumstances” present? Yes No Are Vegetation , Soil , or Hydrology naturally problematic? (If needed, explain any answers in Remarks.) SUMMARY OF FINDINGS – Attach site map showing sampling point locations, transects, important features, etc. Hydrophytic Vegetation Present? Yes No Hydric Soil Present? Yes No Wetland Hydrology Present? Yes No Is the Sampled Area within a Wetland? Yes No Remarks: VEGETATION – Use scientific names of plants. Absolute Dominant Indicator Tree Stratum (Plot size: 30 ft) % Cover Species? Status 1. 2. 3. 4. = Total Cover Sapling/Shrub Stratum (Plot size: 15 ft) 1. 2. 3. 4. 5. = Total Cover Herb Stratum (Plot size: 5 ft) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. = Total Cover Woody Vine Stratum (Plot size: 30 ft) 1. 2. = Total Cover % Bare Ground in Herb Stratum Dominance Test worksheet: Number of Dominant Species That Are OBL, FACW, or FAC: (A) Total Number of Dominant Species Across All Strata: (B) Percent of Dominant Species That Are OBL, FACW, or FAC: (A/B) Prevalence Index worksheet: Total % Cover of: Multiply by: OBL species x 1 = FACW species x 2 = FAC species x 3 = FACU species x 4 = UPL species x 5 = Column Totals: (A) (B) Prevalence Index = B/A = Hydrophytic Vegetation Indicators: Rapid Test for Hydrophytic Vegetation Dominance Test is >50% Prevalence Index is ≤3.01 Morphological Adaptations1 (Provide supporting data in Remarks or on a separate sheet) Wetland Non-Vascular Plants1 Problematic Hydrophytic Vegetation1 (Explain) 1Indicators of hydric soil and wetland hydrology must be present, unless disturbed or problematic. Hydrophytic Vegetation Present? Yes No Remarks: 1779.0002 - South 320th Street & I-5 Federal Way / King 09/12/2019 Pape Properties Inc WA DP-3 Rachael Hyland, Jake Layman 9 / 21N / 04E Depression Concave 0 A2 47.318100 -122.29473055 WGS 84 Seattle muck PFO All three wetland criteria met. Data collected in northern portion of Wetland A. 6 6 0 100% Lonicera involucrata 60 Yes FAC Rubus spectabilis 20 Yes FAC 80 Lysichiton americanus 35 Yes OBL Solanum dulcamara 30 Yes FAC Athyrium cyclosorum 25 Yes FAC Oenanthe sarmentosa 25 Yes OBL Urtica dioica 5 No FAC 120 0 0 Hydrophytic vegetation met through dominance test. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 SOIL Sampling Point: Profile Description: (Describe to the depth needed to document the indicator or confirm the absence of indicators.) Depth Matrix Redox Features (inches) Color (moist) % Color (moist) % Type1 Loc2 Texture Remarks 1Type: C=Concentration, D=Depletion, RM=Reduced Matrix, CS=Covered or Coated Sand Grains. 2Location: PL=Pore Lining, M=Matrix. Hydric Soil Indicators: (Applicable to all LRRs, unless otherwise noted.) Indicators for Problematic Hydric Soils3: Histosol (A1) Sandy Redox (S5) 2 cm Muck (A10) Histic Epipedon (A2) Stripped Matrix (S6) Red Parent Material (TF2) Black Histic (A3) Loamy Mucky Mineral (F1) (except MLRA 1) Very Shallow Dark Surface (TF12) Hydrogen Sulfide (A4) Loamy Gleyed Matrix (F2) Other (Explain in Remarks) Depleted Below Dark Surface (A11) Depleted Matrix (F3) Thick Dark Surface (A12) Redox Dark Surface (F6) 3Indicators of hydrophytic vegetation and Sandy Mucky Mineral (S1) Depleted Dark Surface (F7) wetland hydrology must be present, Sandy Gleyed Matrix (S4) Redox Depressions (F8) unless disturbed or problematic. Restrictive Layer (if present): Type:________________________________ Depth (inches):________________________ Hydric Soil Present? Yes No Remarks: HYDROLOGY Wetland Hydrology Indicators: Primary Indicators (minimum of one required; check all that apply) Secondary Indicators (2 or more required) Surface Water (A1) Water-Stained Leaves (B9) (except MLRA Water-Stained Leaves (B9) (MLRA 1, 2, High Water Table (A2) 1, 2, 4A, and 4B) 4A, and 4B) Saturation (A3) Salt Crust (B11) Drainage Patterns (B10) Water Marks (B1) Aquatic Invertebrates (B13) Dry-Season Water Table (C2) Sediment Deposits (B2) Hydrogen Sulfide Odor (C1) Saturation Visible on Aerial Imagery (C9) Drift Deposits (B3) Oxidized Rhizospheres along Living Roots (C3) Geomorphic Position (D2) Algal Mat or Crust (B4) Presence of Reduced Iron (C4) Shallow Aquitard (D3) Iron Deposits (B5) Recent Iron Reduction in Tilled Soils (C6) FAC-Neutral Test (D5) Surface Soil Cracks (B6) Stunted or Stressed Plants (D1) (LRR A) Raised Ant Mounds (D6) (LRR A) Inundation Visible on Aerial Imagery (B7) Other (Explain in Remarks) Frost-Heave Hummocks (D7) Sparsely Vegetated Concave Surface (B8) Field Observations: Surface Water Present? Yes No Depth (inches): Water Table Present? Yes No Depth (inches): Saturation Present? Yes No Depth (inches): (includes capillary fringe) Wetland Hydrology Present? Yes No Describe Recorded Data (stream gauge, monitoring well, aerial photos, previous inspections), if available: Remarks: DP-3 0 - 7 7.5YR 3/1 100 ----MeLo Mucky medium loam 7 - 11 2.5Y 3/1 100 ----SaLo Sandy loam 11 - 14 2.5Y 4/2 93 5YR 4/6 2 C M SiLo Silt loam 11 - 14 2.5Y 5/4 5 C M None -- Hydric soil criteria met through indicators A11 and F1. 14 12 Hydrology criteria met through primary indicator A2. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 WETLAND DETERMINATION DATA FORM – Western Mountains, Valleys, and Coast Region Project/Site: City/County: Sampling Date: Applicant/Owner: State: Sampling Point: Investigator(s): Section, Township, Range: Landform (hillslope, terrace, etc.): Local relief (concave, convex, none): Slope (%): Subregion (LRR): Lat: Long: Datum: Soil Map Unit Name: NWI classification: Are climatic / hydrologic conditions on the site typical for this time of year? Yes No (If no, explain in Remarks.) Are Vegetation , Soil , or Hydrology significantly disturbed? Are “Normal Circumstances” present? Yes No Are Vegetation , Soil , or Hydrology naturally problematic? (If needed, explain any answers in Remarks.) SUMMARY OF FINDINGS – Attach site map showing sampling point locations, transects, important features, etc. Hydrophytic Vegetation Present? Yes No Hydric Soil Present? Yes No Wetland Hydrology Present? Yes No Is the Sampled Area within a Wetland? Yes No Remarks: VEGETATION – Use scientific names of plants. Absolute Dominant Indicator Tree Stratum (Plot size: 30 ft) % Cover Species? Status 1. 2. 3. 4. = Total Cover Sapling/Shrub Stratum (Plot size: 15 ft) 1. 2. 3. 4. 5. = Total Cover Herb Stratum (Plot size: 5 ft) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. = Total Cover Woody Vine Stratum (Plot size: 30 ft) 1. 2. = Total Cover % Bare Ground in Herb Stratum Dominance Test worksheet: Number of Dominant Species That Are OBL, FACW, or FAC: (A) Total Number of Dominant Species Across All Strata: (B) Percent of Dominant Species That Are OBL, FACW, or FAC: (A/B) Prevalence Index worksheet: Total % Cover of: Multiply by: OBL species x 1 = FACW species x 2 = FAC species x 3 = FACU species x 4 = UPL species x 5 = Column Totals: (A) (B) Prevalence Index = B/A = Hydrophytic Vegetation Indicators: Rapid Test for Hydrophytic Vegetation Dominance Test is >50% Prevalence Index is ≤3.01 Morphological Adaptations1 (Provide supporting data in Remarks or on a separate sheet) Wetland Non-Vascular Plants1 Problematic Hydrophytic Vegetation1 (Explain) 1Indicators of hydric soil and wetland hydrology must be present, unless disturbed or problematic. Hydrophytic Vegetation Present? Yes No Remarks: 1779.0002 - South 320th Street & I-5 Federal Way / King 09/12/2019 Pape Properties Inc WA DP-4 Rachael Hyland, Jake Layman 9 / 21N / 04E Toe of Slope Concave 1 A2 47.318038 -122.29462011 WGS 84 Alderwood gravelly sandy loam N/A No wetland criteria met. Data collected east of Wetland A in northern portion of the site. Thuja plicata 25 Yes FAC 3 Alnus rubra 15 Yes FAC Pseudotsuga menziesii 10 Yes FACU 7 50 43% Gaultheria shallon 20 Yes FACU Rubus spectabilis 10 Yes FAC Sambucus racemosa 5 No FACU Vaccinium parvifolium 5 No FACU 40 Rubus ursinus 40 Yes FACU Polystichum munitum 25 Yes FACU 65 0 35 No hydrophytic vegetation criteria met; prevalence index not warranted due to lack of wetland hydrology and hydric soils. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 SOIL Sampling Point: Profile Description: (Describe to the depth needed to document the indicator or confirm the absence of indicators.) Depth Matrix Redox Features (inches) Color (moist) % Color (moist) % Type1 Loc2 Texture Remarks 1Type: C=Concentration, D=Depletion, RM=Reduced Matrix, CS=Covered or Coated Sand Grains. 2Location: PL=Pore Lining, M=Matrix. Hydric Soil Indicators: (Applicable to all LRRs, unless otherwise noted.) Indicators for Problematic Hydric Soils3: Histosol (A1) Sandy Redox (S5) 2 cm Muck (A10) Histic Epipedon (A2) Stripped Matrix (S6) Red Parent Material (TF2) Black Histic (A3) Loamy Mucky Mineral (F1) (except MLRA 1) Very Shallow Dark Surface (TF12) Hydrogen Sulfide (A4) Loamy Gleyed Matrix (F2) Other (Explain in Remarks) Depleted Below Dark Surface (A11) Depleted Matrix (F3) Thick Dark Surface (A12) Redox Dark Surface (F6) 3Indicators of hydrophytic vegetation and Sandy Mucky Mineral (S1) Depleted Dark Surface (F7) wetland hydrology must be present, Sandy Gleyed Matrix (S4) Redox Depressions (F8) unless disturbed or problematic. Restrictive Layer (if present): Type:________________________________ Depth (inches):________________________ Hydric Soil Present? Yes No Remarks: HYDROLOGY Wetland Hydrology Indicators: Primary Indicators (minimum of one required; check all that apply) Secondary Indicators (2 or more required) Surface Water (A1) Water-Stained Leaves (B9) (except MLRA Water-Stained Leaves (B9) (MLRA 1, 2, High Water Table (A2) 1, 2, 4A, and 4B) 4A, and 4B) Saturation (A3) Salt Crust (B11) Drainage Patterns (B10) Water Marks (B1) Aquatic Invertebrates (B13) Dry-Season Water Table (C2) Sediment Deposits (B2) Hydrogen Sulfide Odor (C1) Saturation Visible on Aerial Imagery (C9) Drift Deposits (B3) Oxidized Rhizospheres along Living Roots (C3) Geomorphic Position (D2) Algal Mat or Crust (B4) Presence of Reduced Iron (C4) Shallow Aquitard (D3) Iron Deposits (B5) Recent Iron Reduction in Tilled Soils (C6) FAC-Neutral Test (D5) Surface Soil Cracks (B6) Stunted or Stressed Plants (D1) (LRR A) Raised Ant Mounds (D6) (LRR A) Inundation Visible on Aerial Imagery (B7) Other (Explain in Remarks) Frost-Heave Hummocks (D7) Sparsely Vegetated Concave Surface (B8) Field Observations: Surface Water Present? Yes No Depth (inches): Water Table Present? Yes No Depth (inches): Saturation Present? Yes No Depth (inches): (includes capillary fringe) Wetland Hydrology Present? Yes No Describe Recorded Data (stream gauge, monitoring well, aerial photos, previous inspections), if available: Remarks: DP-4 0 - 4 5YR 3/1 100 ----MeLo Medium loam 4 - 8 2.5Y 5/3 100 ----SaLo Sandy loam with <1% concretions 8 - 13 10YR 3/1 100 ----SiLo Silt loam 13 - 15 10YR 4/2 95 10YR 6/8 5 C M SaClLo Sandy clay loam None -- No hydric soil indicators met. None None None No hydrologic criteria met. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 WETLAND DETERMINATION DATA FORM – Western Mountains, Valleys, and Coast Region Project/Site: City/County: Sampling Date: Applicant/Owner: State: Sampling Point: Investigator(s): Section, Township, Range: Landform (hillslope, terrace, etc.): Local relief (concave, convex, none): Slope (%): Subregion (LRR): Lat: Long: Datum: Soil Map Unit Name: NWI classification: Are climatic / hydrologic conditions on the site typical for this time of year? Yes No (If no, explain in Remarks.) Are Vegetation , Soil , or Hydrology significantly disturbed? Are “Normal Circumstances” present? Yes No Are Vegetation , Soil , or Hydrology naturally problematic? (If needed, explain any answers in Remarks.) SUMMARY OF FINDINGS – Attach site map showing sampling point locations, transects, important features, etc. Hydrophytic Vegetation Present? Yes No Hydric Soil Present? Yes No Wetland Hydrology Present? Yes No Is the Sampled Area within a Wetland? Yes No Remarks: VEGETATION – Use scientific names of plants. Absolute Dominant Indicator Tree Stratum (Plot size: 30 ft) % Cover Species? Status 1. 2. 3. 4. = Total Cover Sapling/Shrub Stratum (Plot size: 15 ft) 1. 2. 3. 4. 5. = Total Cover Herb Stratum (Plot size: 5 ft) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. = Total Cover Woody Vine Stratum (Plot size: 30 ft) 1. 2. = Total Cover % Bare Ground in Herb Stratum Dominance Test worksheet: Number of Dominant Species That Are OBL, FACW, or FAC: (A) Total Number of Dominant Species Across All Strata: (B) Percent of Dominant Species That Are OBL, FACW, or FAC: (A/B) Prevalence Index worksheet: Total % Cover of: Multiply by: OBL species x 1 = FACW species x 2 = FAC species x 3 = FACU species x 4 = UPL species x 5 = Column Totals: (A) (B) Prevalence Index = B/A = Hydrophytic Vegetation Indicators: Rapid Test for Hydrophytic Vegetation Dominance Test is >50% Prevalence Index is ≤3.01 Morphological Adaptations1 (Provide supporting data in Remarks or on a separate sheet) Wetland Non-Vascular Plants1 Problematic Hydrophytic Vegetation1 (Explain) 1Indicators of hydric soil and wetland hydrology must be present, unless disturbed or problematic. Hydrophytic Vegetation Present? Yes No Remarks: 1779.0002 - South 320th Street & I-5 Federal Way / King 09/12/2019 Pape Properties Inc WA DP-5 Rachael Hyland, Jake Layman 9 / 21N / 04E Hillslope None 3 A2 47.317108 -122.29307512 WGS 84 Alderwood gravelly sandy loam N/A No wetland criteria met. Data collected in central-eastern portion of the site. Populus balsamifera 15 Yes FAC 2 Acer macrophyllum 10 Yes FACU 5 25 40% Rubus armeniacus 20 Yes FAC Populus balsamifera 1 No FAC 21 Tanacetum vulgare 35 Yes FACU Plantago lanceolata 15 Yes FACU Phalaris arundinacea 10 No FACW Trifolium repens 2 No FAC Cirsium vulgare 2 No FACU Gnaphalium uliginosum 2 No FAC Rubus laciniatus 2 No FACU 68 0 32 No hydrophytic vegetation criteria met; prevalence index not warranted due to lack of wetland hydrology and hydric soils. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 SOIL Sampling Point: Profile Description: (Describe to the depth needed to document the indicator or confirm the absence of indicators.) Depth Matrix Redox Features (inches) Color (moist) % Color (moist) % Type1 Loc2 Texture Remarks 1Type: C=Concentration, D=Depletion, RM=Reduced Matrix, CS=Covered or Coated Sand Grains. 2Location: PL=Pore Lining, M=Matrix. Hydric Soil Indicators: (Applicable to all LRRs, unless otherwise noted.) Indicators for Problematic Hydric Soils3: Histosol (A1) Sandy Redox (S5) 2 cm Muck (A10) Histic Epipedon (A2) Stripped Matrix (S6) Red Parent Material (TF2) Black Histic (A3) Loamy Mucky Mineral (F1) (except MLRA 1) Very Shallow Dark Surface (TF12) Hydrogen Sulfide (A4) Loamy Gleyed Matrix (F2) Other (Explain in Remarks) Depleted Below Dark Surface (A11) Depleted Matrix (F3) Thick Dark Surface (A12) Redox Dark Surface (F6) 3Indicators of hydrophytic vegetation and Sandy Mucky Mineral (S1) Depleted Dark Surface (F7) wetland hydrology must be present, Sandy Gleyed Matrix (S4) Redox Depressions (F8) unless disturbed or problematic. Restrictive Layer (if present): Type:________________________________ Depth (inches):________________________ Hydric Soil Present? Yes No Remarks: HYDROLOGY Wetland Hydrology Indicators: Primary Indicators (minimum of one required; check all that apply) Secondary Indicators (2 or more required) Surface Water (A1) Water-Stained Leaves (B9) (except MLRA Water-Stained Leaves (B9) (MLRA 1, 2, High Water Table (A2) 1, 2, 4A, and 4B) 4A, and 4B) Saturation (A3) Salt Crust (B11) Drainage Patterns (B10) Water Marks (B1) Aquatic Invertebrates (B13) Dry-Season Water Table (C2) Sediment Deposits (B2) Hydrogen Sulfide Odor (C1) Saturation Visible on Aerial Imagery (C9) Drift Deposits (B3) Oxidized Rhizospheres along Living Roots (C3) Geomorphic Position (D2) Algal Mat or Crust (B4) Presence of Reduced Iron (C4) Shallow Aquitard (D3) Iron Deposits (B5) Recent Iron Reduction in Tilled Soils (C6) FAC-Neutral Test (D5) Surface Soil Cracks (B6) Stunted or Stressed Plants (D1) (LRR A) Raised Ant Mounds (D6) (LRR A) Inundation Visible on Aerial Imagery (B7) Other (Explain in Remarks) Frost-Heave Hummocks (D7) Sparsely Vegetated Concave Surface (B8) Field Observations: Surface Water Present? Yes No Depth (inches): Water Table Present? Yes No Depth (inches): Saturation Present? Yes No Depth (inches): (includes capillary fringe) Wetland Hydrology Present? Yes No Describe Recorded Data (stream gauge, monitoring well, aerial photos, previous inspections), if available: Remarks: DP-5 0 - 7 10YR 3/3 100 ----SiLo Silt loam 7 - 13 10YR 4/3 95 5YR 4/6 5 C PL SiLo Silt loam, cemented layer None -- No hydric soil indicators met. Second layer is extremely compacted and cemented, shovel refusal at 13" due to compaction. None None None No hydrologic criteria met. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 WETLAND DETERMINATION DATA FORM – Western Mountains, Valleys, and Coast Region Project/Site: City/County: Sampling Date: Applicant/Owner: State: Sampling Point: Investigator(s): Section, Township, Range: Landform (hillslope, terrace, etc.): Local relief (concave, convex, none): Slope (%): Subregion (LRR): Lat: Long: Datum: Soil Map Unit Name: NWI classification: Are climatic / hydrologic conditions on the site typical for this time of year? Yes No (If no, explain in Remarks.) Are Vegetation , Soil , or Hydrology significantly disturbed? Are “Normal Circumstances” present? Yes No Are Vegetation , Soil , or Hydrology naturally problematic? (If needed, explain any answers in Remarks.) SUMMARY OF FINDINGS – Attach site map showing sampling point locations, transects, important features, etc. Hydrophytic Vegetation Present? Yes No Hydric Soil Present? Yes No Wetland Hydrology Present? Yes No Is the Sampled Area within a Wetland? Yes No Remarks: VEGETATION – Use scientific names of plants. Absolute Dominant Indicator Tree Stratum (Plot size: 30 ft) % Cover Species? Status 1. 2. 3. 4. = Total Cover Sapling/Shrub Stratum (Plot size: 15 ft) 1. 2. 3. 4. 5. = Total Cover Herb Stratum (Plot size: 5 ft) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. = Total Cover Woody Vine Stratum (Plot size: 30 ft) 1. 2. = Total Cover % Bare Ground in Herb Stratum Dominance Test worksheet: Number of Dominant Species That Are OBL, FACW, or FAC: (A) Total Number of Dominant Species Across All Strata: (B) Percent of Dominant Species That Are OBL, FACW, or FAC: (A/B) Prevalence Index worksheet: Total % Cover of: Multiply by: OBL species x 1 = FACW species x 2 = FAC species x 3 = FACU species x 4 = UPL species x 5 = Column Totals: (A) (B) Prevalence Index = B/A = Hydrophytic Vegetation Indicators: Rapid Test for Hydrophytic Vegetation Dominance Test is >50% Prevalence Index is ≤3.01 Morphological Adaptations1 (Provide supporting data in Remarks or on a separate sheet) Wetland Non-Vascular Plants1 Problematic Hydrophytic Vegetation1 (Explain) 1Indicators of hydric soil and wetland hydrology must be present, unless disturbed or problematic. Hydrophytic Vegetation Present? Yes No Remarks: 1779.0002 - South 320th Street & I-5 Federal Way / King 09/12/2019 Pape Properties Inc WA DP-6 Rachael Hyland, Jake Layman 9 / 21N / 04E Hillslope Convex 6 A2 47.316032 -122.29437407 WGS 84 Alderwood gravelly sandy loam N/A Not all three wetland criteria met; only hydrophytic vegetation present. Data collected within powerline easement, approximately 215 feet east of Wetland A. 2 3 0 67% Rubus armeniacus 25 Yes FAC Cytisus scoparius 1 No UPL 26 Plantago lanceolata 35 Yes FACU Agrostis capillaris 25 Yes FAC Hedera helix 15 No FACU Hypericum perforatum 1 No FACU 76 0 24 Hydrophytic vegetation criteria met through the dominance test. US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0 SOIL Sampling Point: Profile Description: (Describe to the depth needed to document the indicator or confirm the absence of indicators.) Depth Matrix Redox Features (inches) Color (moist) % Color (moist) % Type1 Loc2 Texture Remarks 1Type: C=Concentration, D=Depletion, RM=Reduced Matrix, CS=Covered or Coated Sand Grains. 2Location: PL=Pore Lining, M=Matrix. Hydric Soil Indicators: (Applicable to all LRRs, unless otherwise noted.) Indicators for Problematic Hydric Soils3: Histosol (A1) Sandy Redox (S5) 2 cm Muck (A10) Histic Epipedon (A2) Stripped Matrix (S6) Red Parent Material (TF2) Black Histic (A3) Loamy Mucky Mineral (F1) (except MLRA 1) Very Shallow Dark Surface (TF12) Hydrogen Sulfide (A4) Loamy Gleyed Matrix (F2) Other (Explain in Remarks) Depleted Below Dark Surface (A11) Depleted Matrix (F3) Thick Dark Surface (A12) Redox Dark Surface (F6) 3Indicators of hydrophytic vegetation and Sandy Mucky Mineral (S1) Depleted Dark Surface (F7) wetland hydrology must be present, Sandy Gleyed Matrix (S4) Redox Depressions (F8) unless disturbed or problematic. Restrictive Layer (if present): Type:________________________________ Depth (inches):________________________ Hydric Soil Present? Yes No Remarks: HYDROLOGY Wetland Hydrology Indicators: Primary Indicators (minimum of one required; check all that apply) Secondary Indicators (2 or more required) Surface Water (A1) Water-Stained Leaves (B9) (except MLRA Water-Stained Leaves (B9) (MLRA 1, 2, High Water Table (A2) 1, 2, 4A, and 4B) 4A, and 4B) Saturation (A3) Salt Crust (B11) Drainage Patterns (B10) Water Marks (B1) Aquatic Invertebrates (B13) Dry-Season Water Table (C2) Sediment Deposits (B2) Hydrogen Sulfide Odor (C1) Saturation Visible on Aerial Imagery (C9) Drift Deposits (B3) Oxidized Rhizospheres along Living Roots (C3) Geomorphic Position (D2) Algal Mat or Crust (B4) Presence of Reduced Iron (C4) Shallow Aquitard (D3) Iron Deposits (B5) Recent Iron Reduction in Tilled Soils (C6) FAC-Neutral Test (D5) Surface Soil Cracks (B6) Stunted or Stressed Plants (D1) (LRR A) Raised Ant Mounds (D6) (LRR A) Inundation Visible on Aerial Imagery (B7) Other (Explain in Remarks) Frost-Heave Hummocks (D7) Sparsely Vegetated Concave Surface (B8) Field Observations: Surface Water Present? Yes No Depth (inches): Water Table Present? Yes No Depth (inches): Saturation Present? Yes No Depth (inches): (includes capillary fringe) Wetland Hydrology Present? Yes No Describe Recorded Data (stream gauge, monitoring well, aerial photos, previous inspections), if available: Remarks: DP-6 0 - 3 7.5R 4/3 100 ----SaLo Sandy loam 3 - 11 10YR 5/3 100 ----SaLo Gravelly sandy loam None -- Shovel refusal at 11 inches due to compaction. No hydric soil indicators met, and no possible indicators due to bright matrices despite the refusal at 11 inches. None None None No hydrologic criteria met. 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment E – Wetland Rating Form Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 1 Rating Form – Effective January 1, 2015 Score for each function based on three ratings (order of ratings is not important) 9 = H,H,H 8 = H,H,M 7 = H,H,L 7 = H,M,M 6 = H,M,L 6 = M,M,M 5 = H,L,L 5 = M,M,L 4 = M,L,L 3 = L,L,L RATING SUMMARY – Western Washington Name of wetland (or ID #): _________________________________ Date of site visit: _____ Rated by____________________________ Trained by Ecology?__ Yes ___No Date of training______ HGM Class used for rating_________________ Wetland has multiple HGM classes?___Y ____N NOTE: Form is not complete without the figures requested (figures can be combined). Source of base aerial photo/map ______________________________________ OVERALL WETLAND CATEGORY ____ (based on functions___ or special characteristics___) 1.Category of wetland based on FUNCTIONS _______Category I – Total score = 23 - 27 _______Category II – Total score = 20 - 22 _______Category III – Total score = 16 - 19 _______Category IV – Total score = 9 - 15 FUNCTION Improving Water Quality Hydrologic Habitat Circle the appropriate ratings Site Potential Landscape Potential Value TOTAL Score Based on Ratings 2.Category based on SPECIAL CHARACTERISTICS of wetland CHARACTERISTIC CATEGORY Estuarine I II Wetland of High Conservation Value I Bog I Mature Forest I Old Growth Forest I Coastal Lagoon I II Interdunal I II III IV None of the above A A 09/12/19 Rachael Hyland, Matt DeCaro 4 9/2016 Depressional 4 ESRI ArcGIS III 4 M M M M H L L L M 5 6 5 16 N/A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 2 Rating Form – Effective January 1, 2015 Maps and figures required to answer questions correctly for Western Washington Depressional Wetlands Map of: To answer questions: Figure # Cowardin plant classes D 1.3, H 1.1, H 1.4 Hydroperiods D 1.4, H 1.2 Location of outlet (can be added to map of hydroperiods) D 1.1, D 4.1 Boundary of area within 150 ft of the wetland (can be added to another figure) D 2.2, D 5.2 Map of the contributing basin D 4.3, D 5.3 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) D 3.1, D 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) D 3.3 Riverine Wetlands Map of: To answer questions: Figure # Cowardin plant classes H 1.1, H 1.4 Hydroperiods H 1.2 Ponded depressions R 1.1 Boundary of area within 150 ft of the wetland (can be added to another figure) R 2.4 Plant cover of trees, shrubs, and herbaceous plants R 1.2, R 4.2 Width of unit vs. width of stream (can be added to another figure) R 4.1 Map of the contributing basin R 2.2, R 2.3, R 5.2 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) R 3.1 Screen capture of list of TMDLs for WRIA in which unit is found (from web) R 3.2, R 3.3 Lake Fringe Wetlands Map of: To answer questions: Figure # Cowardin plant classes L 1.1, L 4.1, H 1.1, H 1.4 Plant cover of trees, shrubs, and herbaceous plants L 1.2 Boundary of area within 150 ft of the wetland (can be added to another figure) L 2.2 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) L 3.1, L 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) L 3.3 Slope Wetlands Map of: To answer questions: Figure # Cowardin plant classes H 1.1, H 1.4 Hydroperiods H 1.2 Plant cover of dense trees, shrubs, and herbaceous plants S 1.3 Plant cover of dense, rigid trees, shrubs, and herbaceous plants (can be added to figure above) S 4.1 Boundary of 150 ft buffer (can be added to another figure) S 2.1, S 5.1 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) S 3.1, S 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) S 3.3 A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 3 Rating Form – Effective January 1, 2015 HGM Classification of Wetlands in Western Washington 1. Are the water levels in the entire unit usually controlled by tides except during floods? NO – go to 2 YES – the wetland class is Tidal Fringe – go to 1.1 1.1 Is the salinity of the water during periods of annual low flow below 0.5 ppt (parts per thousand)? NO – Saltwater Tidal Fringe (Estuarine) YES – Freshwater Tidal Fringe If your wetland can be classified as a Freshwater Tidal Fringe use the forms for Riverine wetlands. If it is Saltwater Tidal Fringe it is an Estuarine wetland and is not scored. This method cannot be used to score functions for estuarine wetlands. 2. The entire wetland unit is flat and precipitation is the only source (>90%) of water to it. Groundwater and surface water runoff are NOT sources of water to the unit. NO – go to 3 YES – The wetland class is Flats If your wetland can be classified as a Flats wetland, use the form for Depressional wetlands. 3. Does the entire wetland unit meet all of the following criteria? ___The vegetated part of the wetland is on the shores of a body of permanent open water (without any plants on the surface at any time of the year) at least 20 ac (8 ha) in size; ___At least 30% of the open water area is deeper than 6.6 ft (2 m). NO – go to 4 YES – The wetland class is Lake Fringe (Lacustrine Fringe) 4. Does the entire wetland unit meet all of the following criteria? ____The wetland is on a slope (slope can be very gradual), ____The water flows through the wetland in one direction (unidirectional) and usually comes from seeps. It may flow subsurface, as sheetflow, or in a swale without distinct banks, ____The water leaves the wetland without being impounded. NO – go to 5 YES – The wetland class is Slope NOTE: Surface water does not pond in these type of wetlands except occasionally in very small and shallow depressions or behind hummocks (depressions are usually <3 ft diameter and less than 1 ft deep). 5. Does the entire wetland unit meet all of the following criteria? ____The unit is in a valley, or stream channel, where it gets inundated by overbank flooding from that stream or river, ____The overbank flooding occurs at least once every 2 years. For questions 1-7, the criteria described must apply to the entire unit being rated. If the hydrologic criteria listed in each question do not apply to the entire unit being rated, you probably have a unit with multiple HGM classes. In this case, identify which hydrologic criteria in questions 1-7 apply, and go to Question 8. A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 4 Rating Form – Effective January 1, 2015 NO – go to 6 YES – The wetland class is Riverine NOTE: The Riverine unit can contain depressions that are filled with water when the river is not flooding 6. Is the entire wetland unit in a topographic depression in which water ponds, or is saturated to the surface, at some time during the year? This means that any outlet, if present, is higher than the interior of the wetland. NO – go to 7 YES – The wetland class is Depressional 7. Is the entire wetland unit located in a very flat area with no obvious depression and no overbank flooding? The unit does not pond surface water more than a few inches. The unit seems to be maintained by high groundwater in the area. The wetland may be ditched, but has no obvious natural outlet. NO – go to 8 YES – The wetland class is Depressional 8. Your wetland unit seems to be difficult to classify and probably contains several different HGM classes. For example, seeps at the base of a slope may grade into a riverine floodplain, or a small stream within a Depressional wetland has a zone of flooding along its sides. GO BACK AND IDENTIFY WHICH OF THE HYDROLOGIC REGIMES DESCRIBED IN QUESTIONS 1-7 APPLY TO DIFFERENT AREAS IN THE UNIT (make a rough sketch to help you decide). Use the following table to identify the appropriate class to use for the rating system if you have several HGM classes present within the wetland unit being scored. NOTE: Use this table only if the class that is recommended in the second column represents 10% or more of the total area of the wetland unit being rated. If the area of the HGM class listed in column 2 is less than 10% of the unit; classify the wetland using the class that represents more than 90% of the total area. HGM classes within the wetland unit being rated HGM class to use in rating Slope + Riverine Riverine Slope + Depressional Depressional Slope + Lake Fringe Lake Fringe Depressional + Riverine along stream within boundary of depression Depressional Depressional + Lake Fringe Depressional Riverine + Lake Fringe Riverine Salt Water Tidal Fringe and any other class of freshwater wetland Treat as ESTUARINE If you are still unable to determine which of the above criteria apply to your wetland, or if you have more than 2 HGM classes within a wetland boundary, classify the wetland as Depressional for the rating. A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 5 Rating Form – Effective January 1, 2015 DEPRESSIONAL AND FLATS WETLANDS Water Quality Functions - Indicators that the site functions to improve water quality D 1.0. Does the site have the potential to improve water quality? D 1.1. Characteristics of surface water outflows from the wetland: Wetland is a depression or flat depression (QUESTION 7 on key) with no surface water leaving it (no outlet). points = 3 Wetland has an intermittently flowing stream or ditch, OR highly constricted permanently flowing outlet. points = 2 Wetland has an unconstricted, or slightly constricted, surface outlet that is permanently flowing points = 1 Wetland is a flat depression (QUESTION 7 on key), whose outlet is a permanently flowing ditch. points = 1 D 1.2. The soil 2 in below the surface (or duff layer) is true clay or true organic (use NRCS definitions).Yes = 4 No = 0 D 1.3. Characteristics and distribution of persistent plants (Emergent, Scrub-shrub, and/or Forested Cowardin classes): Wetland has persistent, ungrazed, plants > 95% of area points = 5 Wetland has persistent, ungrazed, plants > ½ of area points = 3 Wetland has persistent, ungrazed plants > 1/10 of area points = 1 Wetland has persistent, ungrazed plants <1/10 of area points = 0 D 1.4. Characteristics of seasonal ponding or inundation : This is the area that is ponded for at least 2 months. See description in manual. Area seasonally ponded is > ½ total area of wetland points = 4 Area seasonally ponded is > ¼ total area of wetland points = 2 Area seasonally ponded is < ¼ total area of wetland points = 0 Total for D 1 Add the points in the boxes above Rating of Site Potential If score is: 12-16 = H 6-11 = M 0-5 = L Record the rating on the first page D 2.0. Does the landscape have the potential to support the water quality function of the site? D 2.1. Does the wetland unit receive stormwater discharges? Yes = 1 No = 0 D 2.2. Is > 10% of the area within 150 ft of the wetland in land uses that generate pollutants? Yes = 1 No = 0 D 2.3. Are there septic systems within 250 ft of the wetland? Yes = 1 No = 0 D 2.4. Are there other sources of pollutants coming into the wetland that are not listed in questions D 2.1 -D 2.3? Source_______________ Yes = 1 No = 0 Total for D 2 Add the points in the boxes above Rating of Landscape Potential If score is: 3 or 4 = H 1 or 2 = M 0 = L Record the rating on the first page D 3.0. Is the water quality improvement provided by the site valuable to society? D 3.1. Does the wetland discharge directly (i.e., within 1 mi) to a stream, river, lake, or marine water that is on the 303(d) list? Yes = 1 No = 0 D 3.2. Is the wetland in a basin or sub-basin where an aquatic resource is on the 303(d) list? Yes = 1 No = 0 D 3.3. Has the site been identified in a watershed or local plan as important for maintaining water quality (answer YES if there is a TMDL for the basin in which the unit is found)? Yes = 2 No = 0 Total for D 3 Add the points in the boxes above Rating of Value If score is: 2-4 = H 1 = M 0 = L Record the rating on the first page NOTES and FIELD OBSERVATIONS: A 3 4 3 0 10 1 1 0 0 2 0 0 0 0 D 3.2 - Wetland A does not appear to have a hydrologic connection to any water on the 303(d) list. The only nearby 303(d) waters (Lake Dolloff and Mill Creek) are located in a separate sub-basin. D 3.3 - There are no water quality improvement projects covering the wetland according to WSDOE's Water Quality Atlas. Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 6 Rating Form – Effective January 1, 2015 DEPRESSIONAL AND FLATS WETLANDS Hydrologic Functions - Indicators that the site functions to reduce flooding and stream degradation D 4.0. Does the site have the potential to reduce flooding and erosion? D 4.1. Characteristics of surface water outflows from the wetland: Wetland is a depression or flat depression with no surface water leaving it (no outlet) points = 4 Wetland has an intermittently flowing stream or ditch, OR highly constricted permanently flowing outletpoints = 2 Wetland is a flat depression (QUESTION 7 on key), whose outlet is a permanently flowing ditch points = 1 Wetland has an unconstricted, or slightly constricted, surface outlet that is permanently flowing points = 0 D 4.2. Depth of storage during wet periods: Estimate the height of ponding above the bottom of the outlet. For wetlands with no outlet, measure from the surface of permanent water or if dry, the deepest part. Marks of ponding are 3 ft or more above the surface or bottom of outlet points = 7 Marks of ponding between 2 ft to < 3 ft from surface or bottom of outlet points = 5 Marks are at least 0.5 ft to < 2 ft from surface or bottom of outlet points = 3 The wetland is a “headwater” wetland points = 3 Wetland is flat but has small depressions on the surface that trap water points = 1 Marks of ponding less than 0.5 ft (6 in) points = 0 D 4.3. Contribution of the wetland to storage in the watershed: Estimate the ratio of the area of upstream basin contributing surface water to the wetland to the area of the wetland unit itself. The area of the basin is less than 10 times the area of the unit points = 5 The area of the basin is 10 to 100 times the area of the unit points = 3 The area of the basin is more than 100 times the area of the unit points = 0 Entire wetland is in the Flats class points = 5 Total for D 4 Add the points in the boxes above Rating of Site Potential If score is: 12-16 = H 6-11 = M 0-5 = L Record the rating on the first page D 5.0. Does the landscape have the potential to support hydrologic functions of the site? D 5.1. Does the wetland receive stormwater discharges? Yes = 1 No = 0 D 5.2. Is >10% of the area within 150 ft of the wetland in land uses that generate excess runoff? Yes = 1 No = 0 D 5.3. Is more than 25% of the contributing basin of the wetland covered with intensive human land uses (residential at >1 residence/ac, urban, commercial, agriculture, etc.)? Yes = 1 No = 0 Total for D 5 Add the points in the boxes above Rating of Landscape Potential If score is: 3 = H 1 or 2 = M 0 = L Record the rating on the first page D 6.0. Are the hydrologic functions provided by the site valuable to society? D 6.1. The unit is in a landscape that has flooding problems. Choose the description that best matches conditions around the wetland unit being rated. Do not add points. Choose the highest score if more than one condition is met . The wetland captures surface water that would otherwise flow down -gradient into areas where flooding has damaged human or natural resources (e.g., houses or salmon redds): Flooding occurs in a sub-basin that is immediately down-gradient of unit. points = 2 Surface flooding problems are in a sub-basin farther down-gradient. points = 1 Flooding from groundwater is an issue in the sub-basin. points = 1 The existing or potential outflow from the wetland is so constrained by human or natural conditions that the points = 0 water stored by the wetland cannot reach areas that flood. Explain why __________________ There are no problems with flooding downstream of the wetland. points = 0 D 6.2. Has the site been identified as important for flood storage or flood conveyance in a regional flood control plan? Yes = 2 No = 0 Total for D 6 Add the points in the boxes above Rating of Value If score is: 2-4 = H 1 = M 0 = L Record the rating on the first page _____________________________________________________________________________ A 4 3 3 10 1 1 1 3 0 Roadways (I-5 and 320th) act as levees and decouple Wetland A from downstream flooding. 0 0 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 13 Rating Form – Effective January 1, 2015 These questions apply to wetlands of all HGM classes. HABITAT FUNCTIONS - Indicators that site functions to provide important habitat H 1.0. Does the site have the potential to provide habitat? H 1.1. Structure of plant community: Indicators are Cowardin classes and strata within the Forested class. Check the Cowardin plant classes in the wetland. Up to 10 patches may be combined for each class to meet the threshold of ¼ ac or more than 10% of the unit if it is smaller than 2.5 ac. Add the number of structures checked. ____Aquatic bed 4 structures or more: points = 4 ____Emergent 3 structures: points = 2 ____Scrub-shrub (areas where shrubs have > 30% cover) 2 structures: points = 1 ____Forested (areas where trees have > 30% cover) 1 structure: points = 0 If the unit has a Forested class, check if: ____The Forested class has 3 out of 5 strata (canopy, sub-canopy, shrubs, herbaceous, moss/ground-cover) that each cover 20% within the Forested polygon H 1.2. Hydroperiods Check the types of water regimes (hydroperiods) present within the wetland. The water regime has to cover more than 10% of the wetland or ¼ ac to count (see text for descriptions of hydroperiods). ____Permanently flooded or inundated 4 or more types present: points = 3 ____Seasonally flooded or inundated 3 types present: points = 2 ____Occasionally flooded or inundated 2 types present: points = 1 ____Saturated only 1 type present: points = 0 ____Permanently flowing stream or river in, or adjacent to, the wetland ____Seasonally flowing stream in, or adjacent to, the wetland ____Lake Fringe wetland 2 points ____Freshwater tidal wetland 2 points H 1.3. Richness of plant species Count the number of plant species in the wetland that cover at least 10 ft 2. Different patches of the same species can be combined to meet the size threshold and you do not have to name the species. Do not include Eurasian milfoil, reed canarygrass, purple loosestrife, Canadian thistle If you counted: > 19 species points = 2 5 - 19 species points = 1 < 5 species points = 0 H 1.4. Interspersion of habitats Decide from the diagrams below whether interspersion among Cowardin plants classes (described in H 1.1), or the classes and unvegetated areas (can include open water or mudflats) is high, moderate, low, or none. If you have four or more plant classes or three classes and open water, the rating is always high. None = 0 points Low = 1 point Moderate = 2 points All three diagrams in this row are HIGH = 3points A 2 1 2 1 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 14 Rating Form – Effective January 1, 2015 H 1.5. Special habitat features: Check the habitat features that are present in the wetland. The number of checks is the number of points. ____Large, downed, woody debris within the wetland (> 4 in diameter and 6 ft long). ____Standing snags (dbh > 4 in) within the wetland ____Undercut banks are present for at least 6.6 ft (2 m) and/or overhanging plants extends at least 3.3 ft (1 m) over a stream (or ditch) in, or contiguous with the wetland, for at least 33 ft (10 m) ____Stable steep banks of fine material that might be used by beaver or muskrat for denning (> 30 degree slope) OR signs of recent beaver activity are present (cut shrubs or trees that have not yet weathered where wood is exposed) ____At least ¼ ac of thin-stemmed persistent plants or woody branches are present in areas that are permanently or seasonally inundated (structures for egg-laying by amphibians) ____Invasive plants cover less than 25% of the wetland area in every stratum of plants (see H 1.1 for list of strata) Total for H 1 Add the points in the boxes above Rating of Site Potential If score is: 15-18 = H 7-14 = M 0-6 = L Record the rating on the first page H 2.0. Does the landscape have the potential to support the habitat functions of the site? H 2.1. Accessible habitat (include only habitat that directly abuts wetland unit). [(% moderate and low intensity land uses) /2] = _______% Calculate: % undisturbed habitat + If total accessible habitat is: > 1/3 (33.3%) of 1 km Polygon points = 3 20-33% of 1 km Polygon points = 2 10-19% of 1 km Polygon points = 1 < 10% of 1 km Polygon points = 0 H 2.2. Undisturbed habitat in 1 km Polygon around the wetland. [(% moderate and low intensity land uses) /2] = _______% points = 3 points = 2 points = 1 Calculate: % undisturbed habitat + Undisturbed habitat > 50% of Polygon Undisturbed habitat 10-50% and in 1-3 patches Undisturbed habitat 10-50% and > 3 patches Undisturbed habitat < 10% of 1 km Polygon points = 0 H 2.3. Land use intensity in 1 km Polygon: If > 50% of 1 km Polygon is high intensity land use points = (- 2) ≤ 50% of 1 km Polygon is high intensity points = 0 Total for H 2 Add the points in the boxes above Rating of Landscape Potential If score is: 4-6 = H 1-3 = M < 1 = L Record the rating on the first page H 3.0. Is the habitat provided by the site valuable to society? H 3.1. Does the site provide habitat for species valued in laws, regulations, or policies? Choose only the highest score that applies to the wetland being rated. Site meets ANY of the following criteria: points = 2 It has 3 or more priority habitats within 100 m (see next page) It provides habitat for Threatened or Endangered species (any plant or animal on the state or federal lists) It is mapped as a location for an individual WDFW priority species It is a Wetland of High Conservation Value as determined by the Department of Natural Resources It has been categorized as an important habitat site in a local or regional comprehensive plan, in a Shoreline Master Plan, or in a watershed plan Site has 1 or 2 priority habitats (listed on next page) within 100 m points = 1 Site does not meet any of the criteria above points = 0 Rating of Value If score is: 2 = H 1 = M 0 = L Record the rating on the first page A 3 9 1.26 1.79 2.1550000000000002 0 1 15.87 19.52 25.63 -2 -1 1 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 15 Rating Form – Effective January 1, 2015 WDFW Priority Habitats Priority habitats listed by WDFW (see complete descriptions of WDFW priority habitats, and the counties in which they can be found, in: Washington Department of Fish and Wildlife. 2008. Priority Habitat and Species List. Olympia, Washington. 177 pp. http://wdfw.wa.gov/publications/00165/wdfw00165.pdf or access the list from here: http://wdfw.wa.gov/conservation/phs/list/) Count how many of the following priority habitats are within 330 ft (100 m) of the wetland unit: NOTE: This question is independent of the land use between the wetland unit and the priority habitat. Aspen Stands: Pure or mixed stands of aspen greater than 1 ac (0.4 ha). Biodiversity Areas and Corridors: Areas of habitat that are relatively important to various species of native fish and wildlife (full descriptions in WDFW PHS report). Herbaceous Balds: Variable size patches of grass and forbs on shallow soils over bedrock. Old-growth/Mature forests: Old-growth west of Cascade crest – Stands of at least 2 tree species, forming a multi- layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha ) > 32 in (81 cm) dbh or > 200 years of age. Mature forests – Stands with average diameters exceeding 21 in (53 cm) dbh; crown cover may be less than 100%; decay, decadence, numbers of snags, and quantity of large downed material is generally less than that found in old-growth; 80-200 years old west of the Cascade crest. Oregon White Oak: Woodland stands of pure oak or oak/conifer associations where canopy coverage of the oak component is important (full descriptions in WDFW PHS report p. 158 – see web link above). Riparian: The area adjacent to aquatic systems with flowing water that contains elements of both aquatic and terrestrial ecosystems which mutually influence each other. Westside Prairies: Herbaceous, non-forested plant communities that can either take the form of a dry prairie or a wet prairie (full descriptions in WDFW PHS report p. 161 – see web link above). Instream: The combination of physical, biological, and chemical processes and conditions that interact to provide functional life history requirements for instream fish and wildlife resources. Nearshore: Relatively undisturbed nearshore habitats. These include Coastal Nearshore, Open Coast Nearshore, and Puget Sound Nearshore. (full descriptions of habitats and the definition of relatively undisturbed are in WDFW report – see web link on previous page). Caves: A naturally occurring cavity, recess, void, or system of interconnected passages under the earth in soils, rock, ice, or other geological formations and is large enough to contain a human. Cliffs: Greater than 25 ft (7.6 m) high and occurring below 5000 ft elevation. Talus: Homogenous areas of rock rubble ranging in average size 0.5 - 6.5 ft (0.15 - 2.0 m), composed of basalt, andesite, and/or sedimentary rock, including riprap slides and mine tailings. May be associated with cliffs. Snags and Logs: Trees are considered snags if they are dead or dying and exhibit sufficient decay characteristics to enable cavity excavation/use by wildlife. Priority snags have a diameter at breast height of > 20 in (51 cm) in western Washington and are > 6.5 ft (2 m) in height. Priority logs are > 12 in (30 cm) in diameter at the largest end, and > 20 ft (6 m) long. Note: All vegetated wetlands are by definition a priority habitat but are not included in this list because they are addressed elsewhere. A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 16 Rating Form – Effective January 1, 2015 CATEGORIZATION BASED ON SPECIAL CHARACTERISTICS Wetland Type Check off any criteria that apply to the wetland. Circle the category when the appropriate criteria are met. Category SC 1.0. Estuarine wetlands Does the wetland meet the following criteria for Estuarine wetlands? The dominant water regime is tidal, Vegetated, and With a salinity greater than 0.5 ppt Yes –Go to SC 1.1 No= Not an estuarine wetland SC 1.1. Is the wetland within a National Wildlife Refuge, National Park, National Estuary Reserve, Natural Area Preserve, State Park or Educational, Environmental, or Scientific Reserve designated under WAC 332 -30-151? Yes = Category I No - Go to SC 1.2 SC 1.2. Is the wetland unit at least 1 ac in size and meets at least two of the following three conditions? The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing, and has less than 10% cover of non-native plant species. (If non-native species are Spartina, see page 25) At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un-grazed or un- mowed grassland. The wetland has at least two of the following features: tidal channels, depressions with open water, or contiguous freshwater wetlands. Yes = Category I No = Category II SC 2.0. Wetlands of High Conservation Value (WHCV) SC 2.1. Has the WA Department of Natural Resources updated their website to include the list of Wetlands of High Conservation Value? Yes – Go to SC 2.2 No – Go to SC 2.3 SC 2.2. Is the wetland listed on the WDNR database as a Wetland of High Conservation Value? Yes = Category I No = Not a WHCV SC 2.3. Is the wetland in a Section/Township/Range that contains a Natural Heritage wetland? http://www1.dnr.wa.gov/nhp/refdesk/datasearch/wnhpwetlands.pdf Yes – Contact WNHP/WDNR and go to SC 2.4 No = Not a WHCV SC 2.4. Has WDNR identified the wetland within the S/T/R as a Wetland of High Conservation Value and listed it on their website? Yes = Category I No = Not a WHCV SC 3.0. Bogs Does the wetland (or any part of the unit) meet both the criteria for soils and vegetation in bogs? Use the key below. If you answer YES you will still need to rate the wetland based on its functions. SC 3.1. Does an area within the wetland unit have organic soil horizons, either peats or mucks, that compose 16 in or more of the first 32 in of the soil profile? Yes – Go to SC 3.3 No – Go to SC 3.2 SC 3.2. Does an area within the wetland unit have organic soils, either peats or mucks, that are less than 16 in deep over bedrock, or an impermeable hardpan such as clay or volcanic ash, or that are floating on top of a lake or pond? Yes – Go to SC 3.3 No = Is not a bog SC 3.3. Does an area with peats or mucks have more than 70% cover of mosses at ground level, AND at least a 30% cover of plant species listed in Table 4? Yes = Is a Category I bog No – Go to SC 3.4 NOTE: If you are uncertain about the extent of mosses in the understory , you may substitute that criterion by measuring the pH of the water that seeps into a hole dug at least 16 in deep. If the pH is less than 5.0 and the plant species in Table 4 are present, the wetland is a bog. SC 3.4. Is an area with peats or mucks forested (> 30% cover) with Sitka spruce, subalpine fir, western red cedar, western hemlock, lodgepole pine, quaking aspen, Engelmann spruce, or western white pine, AND any of the species (or combination of species) listed in Table 4 provide more than 30% of the cover under the canopy? Yes = Is a Category I bog No = Is not a bog A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 17 Rating Form – Effective January 1, 2015 SC 4.0. Forested Wetlands Does the wetland have at least 1 contiguous acre of forest that meets one of these criteria for the WA Department of Fish and Wildlife’s forests as priority habitats? If you answer YES you will still need to rate the wetland based on its functions. Old-growth forests (west of Cascade crest): Stands of at least two tree species, forming a multi-layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha) that are at least 200 years of age OR have a diameter at breast height (dbh) of 32 in (81 cm) or more. Mature forests (west of the Cascade Crest): Stands where the largest trees are 80- 200 years old OR the species that make up the canopy have an average diameter (dbh) exceeding 21 in (53 cm). Yes = Category I No = Not a forested wetland for this section SC 5.0. Wetlands in Coastal Lagoons Does the wetland meet all of the following criteria of a wetland in a coastal lagoon? The wetland lies in a depression adjacent to marine waters that is wholly or partially separated from marine waters by sandbanks, gravel banks, shingle, or, less frequently, rocks The lagoon in which the wetland is located contains ponded water that is saline or brackish (> 0.5 ppt) during most of the year in at least a portion of the lagoon (needs to be measured near the bottom) Yes – Go to SC 5.1 No = Not a wetland in a coastal lagoon SC 5.1. Does the wetland meet all of the following three conditions? The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing), and has less than 20% cover of aggressive, opportunistic plant species (see list of species on p. 100). At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un -grazed or un- mowed grassland. The wetland is larger than 1/10 ac (4350 ft2) Yes = Category I No = Category II SC 6.0. Interdunal Wetlands Is the wetland west of the 1889 line (also called the Western Boundary of Upland Ownership or WBUO)? If you answer yes you will still need to rate the wetland based on its habitat functions. In practical terms that means the following geographic areas: Long Beach Peninsula: Lands west of SR 103 Grayland-Westport: Lands west of SR 105 Ocean Shores-Copalis: Lands west of SR 115 and SR 109 Yes – Go to SC 6.1 No = not an interdunal wetland for rating SC 6.1. Is the wetland 1 ac or larger and scores an 8 or 9 for the habitat functions on the form (rates H,H,H or H,H,M for the three aspects of function)? Yes = Category I No – Go to SC 6.2 SC 6.2. Is the wetland 1 ac or larger, or is it in a mosaic of wetlands that is 1 ac or larger? Yes = Category II No – Go to SC 6.3 SC 6.3. Is the unit between 0.1 and 1 ac, or is it in a mosaic of wetlands that is between 0.1 and 1 ac? Yes = Category III No = Category IV Category of wetland based on Special Characteristics If you answered No for all types, enter “Not Applicable” on Summary Form A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 18 Rating Form – Effective January 1, 2015 This page left blank intentionally A 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment F – Wetland Rating Maps King County SOUTH 320TH & I5 - COWARDIN MAP ¢ 0 300 600150 Feet 3014 S 320TH STFEDERAL WAY, WA 98003KING COUNTY PARCEL NUMBER:0921049028, 0921049139, 0921049140, 0921049160, 0921049187, 0921049206 & 0921049316 SOUTH 320TH & I5 www.soundviewconsultants.com 2907 Harborview Dr., Suite D, Gig Harbor, WA 98335Phone: (253) 514-8952 Fax: (253) 514-8954 Soundview ConsultantsEnvironmental Assessment • Planning • Land Use Solutions LLC DATE: JOB: BY: SCALE: FIGURE NO. of 5 9/27/2019 1779.0002 DLS 11 " = 300 ' Wetland Rating Maps Site Boundary Aquatic Bed Forested 330' Boundary King County PAPÉ KENWORTH 320TH SITE - HYDROPERIOD MAP ¢ 0 300 600150 Feet 3014 S 320TH STFEDERAL WAY, WA 98003KING COUNTY PARCEL NUMBER:0921049028, 0921049139, 0921049140, 0921049160, 0921049187, 0921049206 & 0921049316 PAPÉ KENWORTH 320TH SITE www.soundviewconsultants.com 2907 Harborview Dr., Suite D, Gig Harbor, WA 98335Phone: (253) 514-8952 Fax: (253) 514-8954 Soundview ConsultantsEnvironmental Assessment • Planning • Land Use Solutions LLC DATE: JOB: BY: SCALE: FIGURE NO. of 5 10/29/2019 1779.0002 DLS 21 " = 300 ' Wetland Rating Maps Site Boundary Saturated Only Seasonally Flooded (17%) 150' Boundary King County SOUTH 320TH & I5 - CONTRIBUTING BASIN MAP ¢ 0 400 800200 Feet 3014 S 320TH STFEDERAL WAY, WA 98003KING COUNTY PARCEL NUMBER:0921049028, 0921049139, 0921049140, 0921049160, 0921049187, 0921049206 & 0921049316 SOUTH 320TH & I5 www.soundviewconsultants.com 2907 Harborview Dr., Suite D, Gig Harbor, WA 98335Phone: (253) 514-8952 Fax: (253) 514-8954 Soundview ConsultantsEnvironmental Assessment • Planning • Land Use Solutions LLC DATE: JOB: BY: SCALE: FIGURE NO. of 5 9/27/2019 1779.0002 DLS 31 " = 400 ' Wetland Rating Maps àààààààààààààààà àààà àààà Wetlands ! !! !! !! !! !! !! !! !! !! !! !! !!!! !! !! !! !! !! !! !! !!!! !! !! !! !! !! !! !! ! Intensive Land Use Contributing Basin Area of Contributing Basin (SF)2,293,140 Area of Wetland A (SF)184,396 Percent of Wetland A within Contributing Basin 8.041% Area of Contributing Basin 2,293,140 Area of Intensive Human Land Uses 709,642 Percent of Intensive Human Land Use within Contributing Basin 31% D.4.0 D.4.3 D.5.0 D.5.3 King County PAPÉ KENWORTH 320TH SITE - HABITAT MAP ¢ 0 1,750 3,500875 Feet www.soundviewconsultants.com 2907 Harborview Dr., Suite D, Gig Harbor, WA 98335Phone: (253) 514-8952 Fax: (253) 514-8954 Soundview ConsultantsEnvironmental Assessment • Planning • Land Use Solutions LLC DATE: JOB: BY: SCALE: FIGURE NO. of 5 8/26/2019 1779.0002 DLS 41 " = 1,750 ' Wetland Rating Maps Site Boundary 1 KM Polygons ! !! !!!!!!!! !! !!!!!!!! !!!!!!!!!! !! !!!!!!!Accessible Habitat High Intensity Moderate & Low Intensity Relatively Undisturbed Habitat SITE Abutting Undisturbed Habitat 1.26% Abutting Moderate & Low Intensity Land Uses 1.79% Accessible Habitat 2.16% Undisturbed Habitat 15.87% Moderate & Low Intensity Land Uses 19.52% Undisturbed Habitat in 1 KM Polygon 25.63% High Intensity Land Use in 1 KM Polygon 64.61% H.2.2 H.2.3 H.2.0 Wetland A H.2.1 PAPÉ KENWORTH 320TH SITE 3014 S 320TH STFEDERAL WAY, WA 98003KING COUNTY PARCEL NUMBER: 0921049028, 0921049139, 0921049140, 0921049160, 0921049187, 0921049206 & 0921049316 PAPÉ KENWORTH 320TH SITE - 303(D) MAP ¢ 0 1 20.5 Miles www.soundviewconsultants.com 2907 Harborview Dr., Suite D, Gig Harbor, WA 98335Phone: (253) 514-8952 Fax: (253) 514-8954 Soundview ConsultantsEnvironmental Assessment • Planning • Land Use Solutions LLC DATE: JOB: BY: SCALE: FIGURE NO. of 5 8/26/2019 1779.0002 DLS 51 " = 1 mi Wetland Rating Maps Sub Basin Water Quality Improvement Project Category 5 Assessed Waters Note: There are no Category 4A assessed waterslocated within HUC No. 171100190205 SITE PAPÉ KENWORTH 320TH SITE 3014 S 320TH STFEDERAL WAY, WA 98003KING COUNTY PARCEL NUMBER: 0921049028, 0921049139, 0921049140, 0921049160, 0921049187, 0921049206 & 0921049316 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment G – Third-Party Review Letters Technical Memorandum 130 2nd Avenue South • Edmonds, Washington 98020 • (425) 778-0907 TO: Stacy Welsh, Senior Planner, City of Federal Way FROM: Steven Quarterman DATE: April 15, 2020 RE: Peer Review Pape – Wetland and Fish and Wildlife Habitat Assessment and Buffer Averaging Plan NE Corner of I-5 and South 320th Street, Federal Way Parcel Nos. 0921049028, 0921049139, 092104-9140, 0921049160, 0921049187, 0921049206, and 0921049316 (File No. 19-105322-AD) Federal Way, Washington LAI Project No. 0238090.010 Introduction This technical memorandum provides Landau Associates, Inc.’s (LAI’s) peer review comments on the March 5, 2020 Wetland and Fish and Wildlife Habitat Assessment and Buffer Averaging Plan, Pape Kenworth NW (March 2020 Report), prepared by Soundview Consultants, LLC (2020). The March 2020 Report documents the assessment of wetland and fish and wildlife habitat and proposed a wetland buffer averaging plan at the subject property (i.e., King County Tax Parcel Nos. 0921049028, 0921049139, 0921049140, 0921049160, 0921049187, 0921049206, and 0921049316). The purpose of this peer review was to provide a professional opinion regarding applicable regulatory requirements in the City of Federal Way (City) Revised Code (FWRC) Title 19.145 (Environmentally Critical Areas), specific to the Article IV Wetlands and the proposed buffer averaging plan proposed in the March 2020 Report. LAI provided comments regarding the wetland assessment in a previous technical memorandum (LAI 2019). Peer review comments regarding the March 2020 Report are as follows: 1) LAI is clarifying that the net gain of the proposed buffer is 617 square feet, as opposed to 612 square feet identified in the March 2020 Report. 2) LAI concurs with the proposed buffer averaging plan, provided that additional descriptions and/or representative photographs of referenced “native vegetation” and “invasive species and fill material” in the area of the buffer increase area and buffer impact area, respectively, are provided. The response provided to criteria in FWRC 19.145.440(5)(b) references that the buffer increase area contains native species, but does not provide details of the species present. The response also identifies that the area of buffer encroachment is located within a relatively low-functioning area from a habitat standpoint due to the presence of invasive species and fill material, but does not provide details regarding the type of invasive species or fill in the area. Based on LAI’s review of the site from the reconnaissance conducted on December 18, 2019, LAI recalls trails located in the buffer encroachment area, which are also shown on the base survey of the project area provided by the City (separate from the March 2020 Report). The presence of these trails may provide additional justification for the lower quality of buffer functions. Landau Associates Peer Review Pape Wetland Delineation – Federal Way, Washington 2 April 15, 2020 * * * * * This technical memorandum has been prepared for use by the City in evaluating the adequacy of the summary of baseline conditions presented in the March 2020 Wetland and Fish and Wildlife Habitat Assessment and Buffer Averaging Plan, Pape Kenworth NW. The purpose of the review was to assess the adequacy of the submitted documents for compliance with City requirements, as promulgated in FWRC Title 19, and conformance with conventionally accepted wetland/waterway delineation practices. No other party is entitled to rely on the information, conclusions, and recommendations included in this document without the express written consent of LAI. Further, the reuse of information, conclusions, and recommendations provided herein for extensions of the project or for any other project, without review and authorization by LAI, shall be at the user’s sole risk. LAI warrants that within the limitations of scope, schedule, and budget, these services have been provided in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing in the same locality under similar conditions as this project. LAI makes no other warranty, either express or implied. LAI appreciates this opportunity to be of service to the City. Please contact me if you have any questions or if I may be of further service. LANDAU ASSOCIATES, INC. Steven Quarterman Senior Associate SJQ/JAF/ccy P:\238\090\R\LAI Pape Buffer Avg Peer Review_tm - 04-15-20.docx References LAI. 2019. Technical Memorandum: Peer Review, Pape - Wetland Delineation, NE Corner of I-5 and South 320th Street, Federal Way, Parcel Nos. Parcel Nos. 0921049028, 0921049139, 0921049187, 0921049140, 0921049160, 0921049316, and 0921049206 (File No. 19-105322-AD), Federal Way, Washington. Landau Associates, Inc. December 23. Soundview Consultants LLC. 2020. Wetland and Fish and Wildlife Habitat Assessment and Buffer Averaging Plan, Pape Kenworth NW, Federal Way, Washington. March 5. Technical Memorandum 130 2nd Avenue South • Edmonds, Washington 98020 • (425) 778-0907 TO: Stacy Welsh, Senior Planner, City of Federal Way FROM: Steven Quarterman DATE: December 23, 2019 RE: Peer Review Pape —Wetland Delineation NE Corner of I-5 and South 320th Street, Federal Way Parcel Nos. 092104-9028, 092104-9139, 092104-9187, 092104-9140, 092104-9160, 092104-9316, and 092104-9206 (File No. 19-105322-AD) Federal Way, Washington LAI Project No. 0238090.010 Introduction This technical memorandum provides Landau Associates, Inc.’s (LAI’s) peer review comments on the October 2019 Wetland and Fish and Wildlife Habitat Assessment, 3014 South 320th Street & 31625 32nd Avenue South (October 2019 Report), prepared by Soundview Consultants, LLC (Soundview Consultants LLC 2019).1 The assessment evaluated wetland and fish and wildlife habitat at the parcels noted above, collectively referred to as the subject properties. The purpose of this peer review was to provide a professional opinion regarding applicable regulatory requirements in the City of Federal Way (City) Revised Code (FWRC) Title 19.145 (Environmentally Critical Areas), specific to Article IV Wetlands. Peer review comments regarding the October 2019 Report are as follows: 1) LAI staff conducted a reconnaissance of the subject properties on December 18, 2019 and agree with the delineated boundary and rating of Wetland A included in the October 2019 report. LAI was able to locate all sample plot and boundary flagging, as shown on Figure 1 of the October 2019 Report. The boundary of Wetland A was observed to generally follow the grade change of the subject properties. 2) LAI recommends that the wetland boundary flagging be surveyed, if not already completed, for inclusion on future site plans. LAI acknowledges that Figure 1 of the report presents a scaled site map of the wetland boundary and flagging; however, the report does not provide an indication of the method used for locating the boundary flagging shown on the figure (i.e., GPS or other land- survey methods are not referenced). LAI also notes that evidence of possible survey activities on the subject properties may have been initiated or completed, based on the presence of additional flagging on the subject properties and minor clearing, which would provide access to the wetland and associated boundary flagging. 3) LAI acknowledges the intent of the October 2019 Report was to provide a summary of existing conditions on the subject properties, and it satisfies the applicable reporting requirements of 1 Soundview Consultants LLC. 2019. Wetland and Fish and Wildlife Habitat Assessment, 3014 South 320th Street & 31625 32nd Avenue South, Federal Way, Washington. October 29. Landau Associates Peer Review Pape Wetland Delineation – Federal Way, Washington 2 December 23, 2019 FWRC 19.145.080(2) (a through f) and FWRC 19.145.410(2)(a and c through g). Discussions of impacts, mitigation sequencing, and other applicable development requirements included in FWRC 19.145.080(2) (g through j) and FWRC 19.145.410(2)(b) are expected to be included in subsequent development application submittals, as necessary. * * * * * This technical memorandum has been prepared for use by the City in evaluating the adequacy of the summary of baseline conditions presented in the October 2019 Wetland and Fish and Wildlife Habitat Assessment, 3014 South 320th Street & 31625 32nd Avenue South. The purpose of the review was to assess the adequacy of the submitted documents for compliance with City requirements, as promulgated in FWRC Title 19, and conformance with conventionally accepted wetland/waterway delineation practices. No other party is entitled to rely on the information, conclusions, and recommendations included in this document without the express written consent of LAI. Further, the reuse of information, conclusions, and recommendations provided herein for extensions of the project or for any other project, without review and authorization by LAI, shall be at the user’s sole risk. LAI warrants that within the limitations of scope, schedule, and budget, these services have been provided in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing in the same locality under similar conditions as this project. LAI makes no other warranty, either express or implied. LAI appreciates this opportunity to be of service to the City. Please contact me if you have any questions or if I may be of further service. LANDAU ASSOCIATES, INC. Steven Quarterman Senior Associate SJQ/JAF/ccy P:\238\090\R\LAI Pape Critical Areas Peer Review_tm - 12-23-19.docx 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment H – City Review Letter 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Attachment I — Qualifications All field inspections, jurisdictional wetland boundary delineations, habitat assessments, and supporting documentation, including this Wetland and Fish and Wildlife Habitat Assessment and Buffer Averaging Plan Technical Memorandum prepared for Papé Properties Inc., were prepared by, or under the direction of, Matt DeCaro of SVC. In addition, site inspections and report preparation were assisted by Racheal Hyland and Jake Layman. Matt DeCaro Senior Scientist / Environmental Planner Professional Experience: 10+ years Matt DeCaro is a Senior Scientist/Environmental Planner with a diverse background in environmental planning, wetland science, stream ecology, water quality, site remediation, and environmental regulatory compliance. Matt currently provides permitting and regulatory compliance assistance for land use projects from their planning stages through review, approval, and construction. Matt performs wetland, stream, and shoreline delineations and fish & wildlife habitat assessments; provides land use planning assistance for residential, commercial, and industrial projects; conducts code and regulation analysis; prepares reports and permit applications; and provides restoration and mitigation design. Matt earned a Bachelor of Science degree with a focus in Environmental Science from the Evergreen State College in Olympia, Washington, with additional graduate-level coursework and research in aquatic restoration and salmonid ecology. Matt has received 40-hour wetland delineation training (Western Mtns, Valleys, & Coast and Arid West Regional Supplement), and he is a Pierce County Qualified Wetland Specialist and Wildlife Biologist. Matt has been formally trained in the use of the Washington State Wetland Rating System and Determination of Ordinary High-Water Mark by the Washington State Department of Ecology. He has attended USFWS survey workshops for multiple threatened and endangered species, and he is a Senior Author of WSDOT Biological Assessments. Matt holds 40-hour HAZWOPER training and has managed Phase I Environmental Site Assessments, subsurface investigations, and contaminant remediation projects throughout the Pacific Northwest. His diverse experience also includes NEPA compliance for federal projects; noxious weed abatement; army ant research in the Costa Rican tropical rainforest; spotted owl surveys on federal and private lands; and salmonid spawning and migration surveys. Rachael Hyland Environmental Scientist Professional Experience: 6 years Rachael Hyland is a Wetland Professional in Training (WPIT) through the Society of Wetland Scientists and a Certified Associated Ecologist through the Ecological Society of America. Rachael has a background in wetland and ecological habitat assessments in various states, most notably Connecticut, Massachusetts, Rhode Island, Ohio, and Washington. She has experience in assessing tidal, stream, and wetland systems, reporting on biological evaluations, permitting, and site assessments. She also has extensive knowledge of bats and white nose syndrome (Pseudogymnoascus destructans), a fungal disease affecting bats which was recently documented in Washington. 1779.0002 Papé Properties Soundview Consultants LLC Wetland and Fish & Wildlife Habitat Assessment & Buffer Averaging Plan Revised May 22, 2020 Rachael earned a Bachelor of Science degree in Ecology and Evolutionary Biology from the University of Connecticut, with additional ecology studies at the graduate level. Rachael has completed Basic Wetland Delineator Training with the Institute for Wetland Education and Environmental Research, received 40-hour wetland delineation training (Western Mountains, Valleys, & Coast and Arid West Regional Supplement), and received formal training from the Washington State Department of Ecology in the Using the Revised 2014 Wetland Rating System for Western Washington, How to Determine the Ordinary High Water Mark, Navigating SEPA, and Selecting Wetland Mitigation Sites Using a Watershed Approach. Jake Layman Environmental Scientist Professional Experience: 10+ years Jake Layman is an Environmental Scientist with a varied background in fisheries, wildlife, and aquatic invertebrate biology and stream and lake ecology. Jakes’s expertise includes endangered species monitoring, lake limnology assessments, water chemistry profiles, off-channel habitat characterization, laboratory management, and terrestrial and aquatic amphibian identification with associated habitat assessments. Jake also has experience in fish population assessments, stream typing, spawning escapement, environmental disaster recovery, and amphibian toxicology research. Jake has over 10 years of experience at the federal and state level conducting ecological monitoring surveys throughout eastern and western Washington. He worked with the National Park Service to conduct environmental compliance monitoring on park construction projects, infrastructure maintenance projects, and federal highways projects. This position also included environmental spill response, fish exclusion surveys in support of construction, and effectiveness monitoring on Engineered Log Jam (ELJ) projects. Jake has worked with the Washington State Department of Fish and Wildlife (WDFW) to assess and inventory fish passage barriers and monitor culvert removal projects throughout Western Washington. While working for WDFW, Jake managed the daily operation for the intensive habitat study, on off- channel wetlands, for the Chehalis Aquatic Resources Protection Plan (ASRP). Jake earned Bachelor’s degrees in both Biology, with an Ecology specialization, and Geography, with a Natural Resource Management specialization, from Central Washington University. In addition, Jake also has a Minor in Environmental Studies and a Certificate in Geographic Information Systems (GIS) and Cartography form Central Washington University. Jake has received training from the Washington State Department of Ecology in Environmental Negotiations; Navigating SEPA, Conducting Forage Fish Surveys, Puget Sound Coastal Processes, Shoreline Modifications, and Beach Restoration, and Using the Marine Shoreline Design Guidelines for Marine Shoreline Stabilization. Jake has electro-fisher operation and safety training from Smith-Root INC and Department of the Interior (DOI). 7.0 OTHER PERMITS 20833.001.doc 7.0 OTHER PERMITS Other permits required for this development include: · SEPA Determination · NPDES Permit from the Department of Ecology · Site Development Permit from the City of Federal W ay · Building Permit from the City of Federal Way · Water and sewer main extension permits from Lakehaven Water and Sewer District. 8.0 ESC ANALYSIS AND DESIGN 20833.001.doc 8.0 ESC ANALYSIS AND DESIGN This project is proposing to clear and grade the portion of the site to be developed and construct two buildings, routing all runoff from the developed area into a sediment pond prior to discharge towards the existing wetland. There will be a silt fence around the entire perimeter of the site, along with a construction entrance installed from 32nd Avenue South. The clearing limits will be the property boundary to the north, south, and east limits, and along the limits of work to the west. A sensitive area fence will be established to protect the existing wetlands. Temporary v-ditches with rock check dams routing stormwater to a temporary sediment pond will control erosion and sediment on site during construction. 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATIONS OF COVENANT 20833.001.doc 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT Appropriate bond quantity worksheets and facility summary forms will be included within the final TIR. 10.0 OPERATIONS AND MAINTENANCE MANUAL 20833.001.doc 10.0 OPERATIONS AND MAINTENANCE MANUAL The following pages of this report are the maintenance checklists for the various stormwater facilities around the project site. Please use these pages as guidance when performing maintenance around the site which should occur at a minimum every fall and spring, as well as after every storm event exceeding 1 inch of precipitation in 24 hours. APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 1 – DETENTION PONDS Maintenance Component Defect or Problem Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Storage Area Sediment accumulation Accumulated sediment that exceeds 10% of the designed pond depth. Sediment cleaned out to designed pond shape and depth; pond reseeded if necessary to control erosion. Liner damaged (If Applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Inlet/Outlet Pipe. Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Emergency Overflow/Spillway Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. Rock missing Only one layer of rock exists above native soil in area five square feet or larger or any exposure of native soil on the spillway. Spillway restored to design standards. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-2 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 2 – INFILTRATION FACILITIES Maintenance Component Defect or Problem Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Infiltration Pond, Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Infiltration Pond, Tank, Vault, Trench, or Small Basin Storage Area Sediment accumulation If two inches or more sediment is present or a percolation test indicates facility is working at or less than 90% of design. Facility infiltrates as designed. Liner damaged (If Applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Infiltration Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Infiltration Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-3 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 2 – INFILTRATION FACILITIES Maintenance Component Defect or Problem Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Infiltration Pond, Tank, Vault, Trench, or Small Basin Filter Bags Plugged Filter bag more than 1/2 full. Replace filter bag or redesign system. Infiltration Pond, Tank, Vault, Trench, or Small Basin Pre- settling Ponds and Vaults Sediment accumulation 6" or more of sediment has accumulated. Pre-settling occurs as designed Infiltration Pond, Rock Filter Plugged High water level on upstream side of filter remains for extended period of time or little or no water flows through filter during heavy rain storms. Rock filter replaced evaluate need for filter and remove if not necessary. Infiltration Pond Emergency Overflow Spillway Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-4 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Structure Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the structure opening or is blocking capacity of the structure by more than 10%. No Trash or debris blocking or potentially blocking entrance to structure. Trash or debris in the structure that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the structure. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Sediment Sediment exceeds 60% of the depth from the bottom of the structure to the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Sump of structure contains no sediment. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering structure through cracks, or maintenance person judges that structure is unsound. Structure is sealed and structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering structure through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Structure has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder rungs missing or unsafe Ladder is unsafe due to missing rungs, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. FROP-T Section Damage T section is not securely attached to structure wall and outlet pipe structure should support at least 1,000 lbs of up or down pressure. T section securely attached to wall and outlet pipe. Structure is not in upright position (allow up to 10% from plumb). Structure in correct position. Connections to outlet pipe are not watertight or show signs of deteriorated grout. Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. Any holes—other than designed holes—in the structure. Structure has no holes other than designed holes. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-7 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate. Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one maintenance person. Gate moves up and down easily and is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing Control device is not working properly due to missing, out of place, or bent orifice plate. Plate is in place and works as designed. Obstructions Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having the potential of blocking) the overflow pipe. Pipe is free of all obstructions and works as designed. Deformed or damaged lip Lip of overflow pipe is bent or deformed. Overflow pipe does not allow overflow at an elevation lower than design Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates (If Applicable) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-8 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Structure Sediment Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-9 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Metal Grates (Catch Basins) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 6 – CONVEYANCE PIPES AND DITCHES Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/roots Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vegetation Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If Applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-11 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 8 – ENERGY DISSIPATERS Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed. Site Trash and debris Trash and/or debris accumulation. Dissipater clear of trash and/or debris. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Rock Pad Missing or moved Rock Only one layer of rock exists above native soil in area five square feet or larger or any exposure of native soil. Rock pad prevents erosion. Dispersion Trench Pipe plugged with sediment Accumulated sediment that exceeds 20% of the design depth. Pipe cleaned/flushed so that it matches design. Not discharging water properly Visual evidence of water discharging at concentrated points along trench (normal condition is a “sheet flow” of water along trench). Water discharges from feature by sheet flow. Perforations plugged. Over 1/4 of perforations in pipe are plugged with debris or sediment. Perforations freely discharge flow. Water flows out top of “distributor” catch basin. Water flows out of distributor catch basin during any storm less than the design storm. No flow discharges from distributor catch basin. Receiving area over- saturated Water in receiving area is causing or has potential of causing landslide problems. No danger of landslides. Gabions Damaged mesh Mesh of gabion broken, twisted or deformed so structure is weakened or rock may fall out. Mesh is intact, no rock missing. Corrosion Gabion mesh shows corrosion through more than ¼ of its gage. All gabion mesh capable of containing rock and retaining designed form. Collapsed or deformed baskets Gabion basket shape deformed due to any cause. All gabion baskets intact, structure stands as designed. Missing rock Any rock missing that could cause gabion to loose structural integrity. No rock missing. Manhole/Chamber Worn or damaged post, baffles or side of chamber Structure dissipating flow deteriorates to ½ or original size or any concentrated worn spot exceeding one square foot which would make structure unsound. Structure is in no danger of failing. Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch or any evidence of soil entering the structure through cracks, or maintenance inspection personnel determines that the structure is not structurally sound. Manhole/chamber is sealed and structurally sound. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No soil or water enters and no water discharges at the joint of inlet/outlet pipes. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-13 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 9 – FENCING Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Site Erosion or holes under fence Erosion or holes more than 4 inches high and 12- 18 inches wide permitting access through an opening under a fence. No access under the fence. Wood Posts, Boards and Cross Members Missing or damaged parts Missing or broken boards, post out of plumb by more than 6 inches or cross members broken No gaps on fence due to missing or broken boards, post plumb to within 1½ inches, cross members sound. Weakened by rotting or insects Any part showing structural deterioration due to rotting or insect damage All parts of fence are structurally sound. Damaged or failed post foundation Concrete or metal attachments deteriorated or unable to support posts. Post foundation capable of supporting posts even in strong wind. Metal Posts, Rails and Fabric Damaged parts Post out of plumb more than 6 inches. Post plumb to within 1½ inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence (including post, top rails, and fabric) more than 1 foot out of design alignment. Fence is aligned and meets design standards. Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or protective coating Part or parts that have a rusting or scaling condition that has affected structural adequacy. Structurally adequate posts or parts with a uniform protective coating. Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-14 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 11 – GROUNDS (LANDSCAPING) Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Site Trash or litter Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Trees and Shrubs Hazard Any tree or limb of a tree identified as having a potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. No hazard trees in facility. Damaged Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-16 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 12 – ACCESS ROADS Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Site Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet (i.e., trash and debris would fill up one standards size garbage can). Roadway drivable by maintenance vehicles. Debris which could damage vehicle tires or prohibit use of road. Roadway drivable by maintenance vehicles. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Blocked roadway Any obstruction which reduces clearance above road surface to less than 14 feet. Roadway overhead clear to 14 feet high. Any obstruction restricting the access to a 10- to 12 foot width for a distance of more than 12 feet or any point restricting access to less than a 10 foot width. At least 12-foot of width on access road. Road Surface Erosion, settlement, potholes, soft spots, ruts Any surface defect which hinders or prevents maintenance access. Road drivable by maintenance vehicles. Vegetation on road surface Trees or other vegetation prevent access to facility by maintenance vehicles. Maintenance vehicles can access facility. Shoulders and Ditches Erosion Erosion within 1 foot of the roadway more than 8 inches wide and 6 inches deep. Shoulder free of erosion and matching the surrounding road. Weeds and brush Weeds and brush exceed 18 inches in height or hinder maintenance access. Weeds and brush cut to 2 inches in height or cleared in such a way as to allow maintenance access. Modular Grid Pavement Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damaged or missing Access surface compacted because of broken on missing modular block. Access road surface restored so road infiltrates. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-17