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20-104021_11 Preliminary TIR_09-28-2020-V1Commons at Federal Way Pads F, H, & I Water Quality Treatment Update Preliminary Modified Technical Information Report September 28, 2020 Prepared for Merlone Geier Partners 457 SW 148th Street Suite #202 Burien, WA 98166 Submitted by ESM Consulting Engineers, LLC 33400 8th Avenue S, Suite 205 Federal Way, WA 98003 253.838.6113 tel 253.838.7104 fax www.esmcivil.com 09/28/2020 \\esm8\engr\esm-jobs\2013\001\018\document\rprt-001.docx Table of Contents 1. Project Overview ...............................................................................................................1 2. Conditions and Requirements Summary ...........................................................................3 3. Off-Site Analysis ................................................................................................................5 4. Flow Control & Water Quality Facility Analysis and Design ................................................6 5. Conveyance System Analysis and Design .........................................................................8 6. Special Reports and Studies .............................................................................................9 7. Other Permits ..................................................................................................................10 8. ESC Analysis and Design ................................................................................................11 9. Bond Quantities, Facility Summaries, and Declaration of Covenant ................................12 10. Operations and Maintenance .........................................................................................13 Appendix A: Reference Maps ..............................................................................................14 Appendix B: Developed Site Conditions ..............................................................................15 Appendix C: Treatment Vault Details ...................................................................................16 Appendix D: Geotechnical Engineering Report ....................................................................17 1 1. Project Overview The purpose of this report is to encapsulate the documents and analysis required by the City of Federal Way (City) in the form of a Preliminary Modified Technical Information Report (report) for the redevelopment of The Commons at Federal Way Pads F, H, and I. The project is considered a redevelopment site because the existing impervious surface coverage is more than 35%. Existing Site: The Commons at Federal Way – Pads F, H, and I (Commons) project site is located in the NW quarter of Section 16, Township 21, Range 04E, W.M., at 1701 S Commons in the City of Federal Way, WA. The site is located on King County parcel 7622400015 (11.48 acres) and is zoned CC-C. See Figure 1.1 for the vicinity map and the existing site conditions. Existing Site Hydrology: The project site is currently developed as parking lot with landscaping, lighting and storm drainage facilities. The area in and around the project site is generally flat and is located in the Hylebos Creek drainage basin (WRIA number: 10). See Section 3 for more information and Appendix D for soils information. Stormwater runoff from the parking lot area is collected an existing conveyance system. Proposed Site Improvements: The proposed development includes the demolition of existing parking lot and the construction of 3 buildings, parking, utility services, and landscape islands on 1.48 acres. See Appendix B for the proposed site improvements. Proposed Site Hydrology: Stormwater will continue to generally flow as it is currently routed in the existing stormwater drainage system. Flow Control: Flow control for the entire Commons property (which includes the proposed improvements in the project site) is provided by existing detention facilities. Since this project is considered a redevelopment site, flow control mitigation is not required. Flow Control BMP’s: Since flow control is not required for this redevelopment project, Flow control BMPs are also not required. Water Quality Treatment: Per City Municipal Code 19.30.120 - Nonconforming water quality improvements, the project is required to upgrade water quality treatment facilities to current stormwater standards as specified in the 2016 King County Surface Water Design Manual (SWDM). The current stormwater standards require upgrading the existing basic water quality treatment to enhanced water quality treatment. The entire Commons property was updated to at the time current water quality standards between 2005 and 2014 to meet the standards of the 2009 SWDM. The property was divided into 14 water quality sub-basins. The project site is located within water quality Sub-Basins #1, #2, and #14. The project will update the existing water quality treatment system for the affected Sub-Basins #1 & #14 to the current stormwater performance criteria. See Section 4 of this report for more information. 2 Figure 1.1 – Vicinity Map 3 2. Conditions and Requirements Summary Review of the 9 Core Requirements and 5 Special Requirements This section describes how the project will meet the SWDM Core and Special Requirements (as applicable). Core Requirement No. 1 Discharge at the Natural Location The entire site is fully developed and will continue to drain to the natural discharge location upon project completion. Core Requirement No. 2 Off-site Analysis The off-site analysis has been documented in previously submitted Technical Information Reports for the Commons property and is not proposed to be altered for this project; therefore, an off-site analysis is not required. Core Requirement No. 3 Flow Control Flow Control is not required for this project because it is a redevelopment site. Core Requirement No. 4 Conveyance System Stormwater conveyance will perform as it does in the existing condition because the net impervious area onsite will be slightly reduced from the original design conditions for the existing conveyance system and the proposed system will use components (pipes, catchbasins, etc.) of equal or greater capacity. No conveyance calculations are needed for this project. Core Requirement No. 5 Erosion and Sediment Control Erosion and sediment controls to prevent the transport of sediment from the project site to downstream drainage facilities, water resources, and adjacent properties will be provided with the final TIR and on the construction plans. Core Requirement No. 6 Maintenance and Operations The Operations and Maintenance manual will be included with the final TIR. Core Requirement No. 7 Financial Guarantees and Liability All drainage facilities constructed or modified for projects will comply with the financial guarantee requirements as provided in the King County Bond Quantities Worksheet. Bond Quantities will be provided in the final TIR. Core Requirement No. 8 Water Quality Enhanced Basic Water Quality Treatment will be provided by a water quality filter vault for each Sub-Basin being upgraded (#1 & #14). See Section 4 of this report for details. Core Requirement No. 9 Flow Control BMP’s Since flow control is not required for this redevelopment project, Flow control BMPs are also not required. 4 Special Requirement No. 1 Other Adopted Area-Specific Requirements This project does not have any Adopted Area-Specific Requirements; therefore, Special Requirement No. 1 does not apply. Special Requirement No. 2 Flood Hazard Area Delineation The developed project site location is not in a 100-year floodplain. Special Requirement No. 2 does not apply. Special Requirement No. 3 Flood Protection Facilities The developed project site is not protected by an existing flood protection facility. The proposed site improvements do not include the modification of an existing flood protection facility. Special Requirement No. 3 does not apply. Special Requirement No. 4 Source Control No source control measures are being proposed at this time for the site. Special Requirement No. 5 Oil Control The project does not have a “high-use site characteristic” and is not a redevelopment of a high-use site. Special Requirement No. 5 does not apply. 5 3. Off-Site Analysis A Level 1 downstream analysis has been performed for the site as part of previously accepted TIR documents for the Commons of Federal Way and is not required for this project. 6 4. Flow Control & Water Quality Facility Analysis and Design Existing Site Hydrology: The project site is currently developed as parking lot with landscaping, lighting and storm drainage facilities. The existing impervious area is 1.33 acres and the existing landscaped area is 0.15 acres for a total project site acreage of 1.48. Developed Site Hydrology: The developed condition of this project will drain to the same location as existing with very similar flow rates due to the similarity in the land use type proportion. Since the project site will remain predominantly impervious and match the existing stormwater drainage characteristics, the site will have hydrology that matches the existing conditions. Sub-Basin #1 will remain approximately the same in total area but will grow and shrink to absorb the changes to Sub-Basins #2 & #14. Sub-Basin #2 will increase with the addition of non- pollution generating roof and sidewalk area. Sub-Basin #14 will be reduced but the treatment flow rate from the original basin area has been used to conservatively size the treatment facility. The basin areas are summarized below: Proposed Area (acres) Pad F Roof 0.17 Pad H Roof 0.10 Pad I Roof 0.10 Sidewalk 0.34 Pavement 0.74 Total Impervious 1.45 Landscaping 0.03 Total Area 1.48 Flow Control: Flow control for the entire Commons property (which includes the proposed improvements in the project site) is provided by existing detention facilities. Since this project is considered a redevelopment site, flow control mitigation is not required. Flow Control BMP’s: Since flow control is not required for this redevelopment project, Flow control BMPs are also not required. Water Quality System: Per City Municipal Code 19.30.120 - Nonconforming water quality improvements, the project is required to upgrade water quality treatment facilities to current stormwater standards as specified in the 2016 King County Surface Water Design Manual (SWDM). The current stormwater standards require upgrading the existing basic water quality treatment to enhanced water quality treatment. The parcel that contains the project site is located within water quality Sub-Basins #1, #2, #12 #13, and #14. The project site is located within Sub-Basins #1, #2, and #14. Since there are no proposed improvements to Sub-Basins #12-13, water quality improvements will be deferred to a later date, when improvements in these sub-basins are completed, to the standards current at that time. Sub-Basin #1 contains approximately 34%, Sub-Basin #2 contains approximately 33%, and Sub-Basin #14 contains approximately 33% of the 1.48-acre project site. With the proposed 7 development and new building and parking layout, the proposed project will re-direct approximately 0.17 acres from Sub-Basin #2 and 0.24 acres from Sub-Basin #14 to Sub- Basin #1, resulting in a revised percentage for Sub-Basin #1 at 68%, Sub-Basin #2 at 16%, and Sub-Basin #14 at 16% for the project site. The proposed design will direct only clean stormwater runoff (Pad F, sidewalks, and landscaping) to Sub-Basin #2 and less area, therefore, a water quality upgrade is not proposed for this basin. The project will update the existing water quality treatment system for the affected Sub- Basin #1 (6.39 acres originally, increased to 6.80 acres, modeled at 100% impervious) to the current stormwater performance criteria of enhanced water quality. The required water quality treatment flow rates for the existing Sub-Basin #1 is 0.6581 cubic feet per second (CFS) and the existing Sub-Basin #14 is 0.0411 CFS. Since the developed site hydrology will match the existing site hydrology and the existing site water quality treatment system was updated and sized with the Western Washington Hydrology Model (WWHM) in 2013 (using WWHM3), the existing site treatment flow rate is acceptable for the proposed development. As part of the update, Sub-Basin #1 has been re-modeled in the current Dept. of Ecology version of WWHM (WWHM2012) to verify treatment flows. The current project site model shows the off-line water quality treatment flow rate to be 0.6243 CFS. Since this is less than the existing water quality treatment flow of 0.6581 CFS from the previous model, the existing flow was used for the water quality treatment vault sizing to provide factor of safety in Sub- Basin #1. The proposed enhanced water quality treatment system for Sub-Basin #1 is a 10- ft by 24-ft BioPod XL (or approved equivalent) which has a treatment capacity of 0.72 CFS and sufficient peak flow capacity for the tributary basin. Since the proposed Sub-Basin #14 has a building where the existing water quality treatment facility is located, a new treatment facility has been sized to current standards. The proposed building roof and replaced parking lot area will be directed to Sub-Basin #1, resulting in an overall reduction in Sub-Basin #14 tributary area and subsequently a reduction in required treatment flow rate; however, the existing flow rate of 0.0411 CFS was used in sizing to provide factor of safety in Sub-Basin #14. The proposed enhanced water quality treatment system for Sub-Basin #14 is a 4-ft by 6-ft BioPod Biofilter Underground (or approved equivalent) which has a treatment capacity of 0.057 CFS and sufficient peak flow capacity for the tributary basin. An excerpt from the proposed site conditions PDF, as generated by WWHM, for Sub-Basin #1 has been included in this section of the report with the relevant flow rate information highlighted. WWHM2012 PROJECT REPORT Commons 9/28/2020 4:41:18 PM Page 2 General Model Information Project Name: Commons Site Name: Commons at Federal Way Site Address: City:Federal Way Report Date: 9/28/2020 Gage:Seatac Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 0.000 (adjusted) Version Date: 2019/09/13 Version: 4.2.17 Commons 9/28/2020 4:42:09 PM Page 21 Mitigated Schematic Commons 9/28/2020 4:41:18 PM Page 6 Mitigated Land Use Dev - Sub-Basin #1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 6.39 Impervious Total 6.39 Basin Total 6.39 Element Flows To: Surface Interflow Groundwater Commons 9/28/2020 4:41:18 PM Page 7 Dev Sub-Basin #2 to Sub-Basin #1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 0.17 Impervious Total 0.17 Basin Total 0.17 Element Flows To: Surface Interflow Groundwater Commons 9/28/2020 4:41:18 PM Page 8 Dev Sub-Basin #14 to Sub-Basin #1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 0.24 Impervious Total 0.24 Basin Total 0.24 Element Flows To: Surface Interflow Groundwater Commons 9/28/2020 4:41:18 PM Page 11 Analysis Results POC 1 x Mitigated Mitigated Landuse Totals for POC #1 Total Pervious Area: 0 Total Impervious Area: 6.8 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 2.592599 5 year 3.274754 10 year 3.738231 25 year 4.339428 50 year 4.799569 100 year 5.270883 Commons 9/28/2020 4:41:48 PM Page 17 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0.8363 acre-feet On-line facility target flow: 1.1048 cfs. Adjusted for 15 min: 1.1048 cfs. Off-line facility target flow: 0.6243 cfs. Adjusted for 15 min: 0.6243 cfs. Commons 9/28/2020 4:42:10 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 8 5. Conveyance System Analysis and Design Since Sub-Basins #2 & #14 are being reduced overall, the existing stormwater conveyance systems are anticipated to continue to operate as under current conditions; therefore, conveyance or backwater calculations are not provided. The total area draining to Sub-Basin #1 will be increased by 0.41 acres (approximately 6%), 0.17 acres from Sub-Basin #2 and 0.24 acres from Sub-Basin #14. Since this increase is negligible, the existing stormwater conveyance system for Sub-Basin #1 is anticipated to continue to operate as under current conditions; therefore, conveyance and backwater calculations are not provided. 9 6. Special Reports and Studies The Geotechnical Engineering Report by GeoTest Services, Inc., dated July 23, 2019 is included in Appendix D. The following reports were used as a reference in preparing this Preliminary Modified Technical Information Report. ·Commons at Federal Way by ESM Consulting Engineers, LLC, dated March 2005 ·Future Pads C, D, E, F, & G: Commons at Federal Way by ESM Consulting Engineers, LLC, dated February 2006. ·Memorandum to Kevin Peterson, City of Federal Way, by ESM Consulting Engineers, LLC, dated March 13, 2013. 10 7. Other Permits Building and NPDES permits will be required for this project, together with permits for utility connections. 11 8. ESC Analysis and Design The Erosion and Sedimentation Control will be provided with the final TIR and on the construction plans. 12 9. Bond Quantities, Facility Summaries, and Declaration of Covenant The Bond Quantities worksheet will be provided with the final TIR. 13 10. Operations and Maintenance The Operations and Maintenance manual for the proposed enhanced water quality upgrade will be provided with the final TIR. Appendix A: Reference Maps This portion of sub-basin #2 will drain to sub-basin #1 (0.17 Ac) This portion of sub-basin #14 will drain to sub-basin #1 (0.24 Ac) Ex StormFilter Vault to be replaced 8 ft18 ft Ex StormFilter Catch Basin to be replaced Appendix B: Developed Site Conditions PIV IR PB PB PBPB PB PB PB PB PB IR PB IR IR IR PB PB PB PB PB PBPB D IR S S IR IR D P P G PP PP W P STOPSPEEDBUMPP G PP PP PP PP PP IR IR P PB PB PB IR PB PB PBPB PB PB PB PB PB IR PB IR IR IR PB PB PB PB PB PBPB IR S S IR IR P P µ ΒΝΜΣΝΤΘ ΗΜΣ∆ΘΥ≅Κ < 0& ΡΒ≅Κ∆9 0! < 0 10 1/& 4020 Ρ 21/ΣΓ ΡΣΘ∆∆Σ S 320TH STREET{(PUBIC RIGHT OF WAY)} Κ∆Φ∆ΜΧ9 PROPOSED STORM DRAINAGE PROPOSED 8"%%C SANITARY SEWER PROPOSED 8"%%C WATER EXISTING STORM DRAINAGE EXISTING SANITARY SEWER EXISTING WATER EXISTING GAS N ETRAB .G A RU A 40111ANO R WFOE A SH NGTON T E RED SG ENGNEE EFOR P TS SS TA ER N A E G H LIGHT ASPHALT PAVING \pxt6;HEAVY ASPHALT PAVING NO.DESCRIPTION/DATE BY REVISIONS DWG. NAME: DESIGNED BY: DRAWN BY: CHECKED BY: DATE: OF SHEETS JOB NO.: PRINT: DATE OF \\\\esm8\\engr\\esm-jobs\\2013\\001\\018\\plots\\Process III\\UT-01.dwg9/24/2020 2:36 PMPlotted:File:Plotted By: Greg FedoreEVERETTFEDERAL WAYΒ Ν Μ Ρ Τ Κ Σ Η Μ Φ ∆ Μ Φ Η Μ ∆ ∆ Θ ΡΚ Κ ΒCivil EngineeringProject ManagementLand SurveyingLandscape ArchitectureLand Planningwww.esmcivil.com(253) 838-6113(425) 297-9900Public WorksΕδχδθκ ςξ+ ς≅ 87//2223// 7σγ ≅υδ Ρ+ Ρτησδ 1/4Λ∆ΘΚΝΜ∆ Φ∆Η∆Θ Ο≅ΘΣΜ∆ΘΡΣΓ∆ ΒΝΛΛΝΜΡ ≅Σ Ε∆Χ∆Θ≅Κ ς≅Ξ , Ο≅ΧΡ Ε+ Γ+ % ΗPRELIMINARY UTILITY PLANWASHINGTONCITY OF FEDERAL WAY2013-001-018 UT-01 LGB GFF 09/25/2020 ΤΣ,/0 4 7 ∆ΩΒ∆ΟΣΗΝΜ EXCEPTION{(NOT A PART)} ΣΘ≅ΒΣ Β ∆ΩΗΡΣΗΜΦ ∆ΜΣΘΞ ΧΘΗΥ∆Ο≅Χ Ε PAD F{(7,500 SF)} \pxqc;OUTDOOR SEATING AREA TRASH / RECYCLE G W SS SD CONCRETE PAVING PIVPIVDD IR PB S S PB IR PB S PB PB IR PB PB PB IR D D IR IRIR IR ~ D D D PB PB COCO DD IR PB S S PB IR PB S PB PB IR PB PB PB IR D D IR IRIR IR ΒΝΜΣΝΤΘ ΗΜΣ∆ΘΥ≅Κ < 0& ΡΒ≅Κ∆9 0! < 0 10 1/& 4020 Κ∆Φ∆ΜΧ9 PROPOSED STORM DRAINAGE PROPOSED 8"%%C SANITARY SEWER PROPOSED 8"%%C WATER EXISTING STORM DRAINAGE EXISTING SANITARY SEWER EXISTING WATER EXISTING GAS N ETRAB .G A RU A 40111ANO R WFOEA SH NGTON T E RED SG ENG NEE EFOR P TS SS TA ER N A E G H LIGHT ASPHALT PAVING \pxt6;HEAVY ASPHALT PAVING NO.DESCRIPTION/DATE BY REVISIONS DWG. NAME: DESIGNED BY: DRAWN BY: CHECKED BY: DATE: OF SHEETS JOB NO.: PRINT: DATE OF \\\\esm8\\engr\\esm-jobs\\2013\\001\\018\\plots\\Process III\\UT-02.dwg9/25/2020 8:19 AMPlotted:File:Plotted By: Greg FedoreEVERETTFEDERAL WAYΒ Ν Μ Ρ Τ Κ Σ Η Μ Φ ∆ Μ Φ Η Μ ∆ ∆ Θ ΡΚ Κ ΒCivil EngineeringProject ManagementLand SurveyingLandscape ArchitectureLand Planningwww.esmcivil.com(253) 838-6113(425) 297-9900Public WorksΕδχδθκ ςξ+ ς≅ 87//2223// 7σγ ≅υδ Ρ+ Ρτησδ 1/4Λ∆ΘΚΝΜ∆ Φ∆Η∆Θ Ο≅ΘΣΜ∆ΘΡΣΓ∆ ΒΝΛΛΝΜΡ ≅Σ Ε∆Χ∆Θ≅Κ ς≅Ξ , Ο≅ΧΡ Ε+ Γ+ % ΗPRELIMINARY UTILITY PLANWASHINGTONCITY OF FEDERAL WAY2013-001-018 UT-02 LGB GFF 09/25/2020 ΤΣ,/1 5 7 G W SS SD CONCRETE PAVING µ Ο≅ΒΗΕΗΒ ΓςΞ Ρ PACIFIC HWY S{(PUBIC RIGHT OF WAY)}∆ΩΗΡΣΗΜΦ ∆ΜΣΘΞ ΧΘΗΥ∆Ο≅Χ Γ PAD H{(4,299 SF)}∆ΩΗΡΣΗΜΦ ∆ΜΣΘΞ ΧΘΗΥ∆Ο≅Χ Η PAD I{(4,200 SF)} Appendix C: Treatment Vault Details ISOMETRIC VIEW BPU-IB C US Patents Pending THIS DOCUMENT IS THE PROPERTY OF OLDCASTLE INFRASTRUCTURE, INC. IT IS SUBMITTED FOR REFERENCE PURPOSES ONLY AND SHALL NOT BE USED IN ANY WAY INJURIOUS TO THE INTERESTS OF SAID COMPANY. COPYRIGHT © 2020 OLDCASTLE INFRASTRUCTURE, INC. ALL RIGHTS RESERVED. BioPod  Biofilter Underground Vault with Internal Bypass Oldcastle Oldcastle Oldcastle Bioretention/ Biofiltration A PLAN VIEW A SECTION A-A BPU-IB C US Patents PendingSAUDFI1325-0510USAXXXXTHIS DOCUMENT IS THE PROPERTY OF OLDCASTLE INFRASTRUCTURE, INC. IT IS SUBMITTED FOR REFERENCE PURPOSES ONLY AND SHALL NOT BE USED IN ANY WAY INJURIOUS TO THE INTERESTS OF SAID COMPANY. COPYRIGHT © 2020 OLDCASTLE INFRASTRUCTURE, INC. ALL RIGHTS RESERVED. MODEL VAULT SIZE 1 (ID) VAULT FOOTPRINT 1 (OD) TREATMENT FLOW CAPACITY (GPM/CFS) A DIM B DIM C DIM A1 DIM B1 DIM 1.6 GPM/SF (WA GULD2) 1.8 GPM/SF (NJCAT3) BPU-46IB 4' 6' 1.5'5'7' 25.6 / 0.057 28.8 / 0.064 BPU-48IB 4' 8' 1.5' 5' 9' 38.4 / 0.086 43.2 / 0.096 BPU-412IB 4' 12' 1.5' 5' 13' 64.0 / 0.143 72.0 / 0.160 BPU-66IB 6' 6' 1.5' 7' 7' 38.4 / 0.086 43.2 / 0.096 BPU-68IB 6' 8' 1.5'7'9'57.6 / 0.128 64.8 / 0.144 BPU-612IB 6' 12' 2' 7' 13' 91.2 / 0.203 102.6 / 0.229 BPU-812IB 8' 12' 2' 9' 13' 121.6 / 0.271 136.9 / 0.305 BPU-816IB 8' 16' 2' 9' 17' 172.8 / 0.385 194.4 / 0.433 BioPod  Biofilter Underground Vault with Internal Bypass FIDSAUXXXX USADFI11540010 FIDSAUXXXX USADFI11540010 SITE SPECIFIC DATA Structure ID Model Size Orientation (Left or Right) Treatment Flow Rate (cfs) Peak Flow Rate (cfs) Rim Elevation Pipe Data Pipe Location (Front or Side)Pipe Size Pipe Type Invert Elevation Inlet Outlet Notes: 1 All Dimensions are nominal, ID=Inside Dimension, OD=Outside Dimension. 2 Treartment flow capacity at 1.6 gpm/sf media surface area based on an WA Ecology GULD Approval for Basic, Enhanced & Phosphorus. 3 Treatment flow capacity at 1.8 gpm/sf media surface area based on an NJCAT Verification & NJ DEP Certification. Bioretention/ Biofiltration A PLAN VIEW 1'-0" TOP 25'-6" WALL OD 26'-6" SLAB OD 11'-6" WALL OD 12'-6" FOOTING RIM ELEV 24'-0" WALL ID 10'-0" WALL ID 9" TYPICAL WALL THICKNESS 7'-10" 10" BASE SECTION A-ASECTION D-D 10'-1"8" INLET IE D RIM ELEV SECTION B-B A D SAUDFI1325-0510USAXXXXSAUDFI1325-0510USAXXXXINLET, Ø24" MAXIMUM 2X 6"x24" INLET WINDOW COBBLES FOR ENERGY DISSIPATION. 6X Ø4.00" SLOTTED PVC UNDERDRAIN PIPE. INTERIOR/EXTERIOR JOINT SEALANT REQUIRED, (CONSEAL CS-231 OR EQUIVALENT), BY OTHERS. 2X Ø36.00" BOLTED & GASKETED ACCESS COVERS, FIELD POURED CONCRETE COLLAR REQUIRED, BY OTHERS. GRADE RINGS AS REQUIRED. 6X Ø4.00" SLOTTED PVC UNDERDRAIN PIPE. UNDERDRAIN OUTLET ORIFICE INTO OUTLET CHAMBERINTERIOR/EXTERIOR JOINT SEALANT REQUIRED, (CONSEAL CS-231 OR EQUIVALENT), BY OTHERS. BYPASS WEIR EL INTERIOR/EXTERIOR JOINT SEALANT REQUIRED, (CONSEAL CS-231 OR EQUIVALENT), BY OTHERS. 2X 6"x24" INLET WINDOW 3X Ø4.00" SLOTTED PVC UNDERDRAIN PIPE. 6.00" DRAIN ROCK. 18.00" StormMix MEDIA 2.00" MULCH. UNDERDRAIN OUTLET ORIFICE INTO OUTLET CHAMBER FIDSAUXXXX USADFI11540010 FIDSAUXXXX USADFI11540010 B DRAIN DOWN DEVICE 2'-6"10'-1"8" B OUTLET, Ø24" MAXIMUM DRAIN DOWN DEVICE 2X 6"x24" INLET WINDOW COBBLES FOR ENERGY DISSIPATION. 2X Ø24.00" BOLTED & GASKETED ACCESS COVERS, FIELD POURED CONCRETE COLLAR REQUIRED, BY OTHERS. INLET, Ø24" MAXIMUM OUTLET, Ø24" MAXIMUM BAFFLE WALL BAFFLE WALL DRAIN DOWN DEVICE SAUDFI1325-0510USAXXXX 6'-0" (STANDARD) 2'-10" (STANDARD) BYPASS WEIR EL OUTLET IE 2.2' [26"] DROP RECOMMENDED, 6" MIN. 7'-4" MINIMUM RIM TO INVERT OUT (STANDARD) Bioretention/ Biofiltration INTERNAL DRAWING ID REVISION OF SHEET MFG DRAWN ENGINEER CHECKEDDATE SALES ORDER REV DATE BioPod™ Biofilter Underground 10' X 24' Panel Vault with Internal Bypass THIS DOCUMENT IS THE PROPERTY OF OLDCASTLE INFRASTRUCTURE, INC. IT IS CONFIDENTIAL, SUBMITTED FOR REFERENCE PURPOSES ONLY AND SHALL NOT BE USED IN ANY WAY INJURIOUS TO THE INTERESTS OF, OR WITHOUT THE WRITTEN PERMISSION OF OLDCASTLE INFRASTRUCTURE, INC. COPYRIGHT © 2019 OLDCASTLE INFRASTRUCTURE, INC. ALL RIGHTS RESERVED. CUSTOMER JOB NAME 09/06/19 PPS ARG ARG 1BPU1024-IB-PV 1 Ph: 800.579.8819 | www.oldcastleinfrastructure.com/stormwater BPU1024-IB-PV.dwg, 2019-09-06 1:56 PM Generes, Ayn 6.220NOTES: 1.DESIGN LOADINGS: A. AASHTO HS-20-44 W/ IMPACT. B. DESIGN FILL: X' MAXIMUM. C. ASSUMED WATER TABLE = 5' BELOW GRADE. D. DRY LATERAL EARTH PRESSURE (EFP) = 40 PCF. E. LATERAL LIVE LOAD SURCHARGE = 80 PSF (APPLIED TO 8' BELOW GRADE). F. NO LATERAL SURCHARGE FROM ADJACENT BUILDINGS, WALLS, PIERS, OR FOUNDATIONS. 2.CONCRETE 28 DAY COMPRESSIVE STRENGTH SHALL BE 5,000 PSI MINIMUM. 3.STEEL REINFORCEMENT: REBAR, ASTM A-615 OR A-706, GRADE 60. 4.MESH REINFORCEMENT: ASTM A-1064, S1.2, GRADE 80. 5.CEMENT: ASTM C-150 SPECIFICATION. 6.REFERENCE STANDARD: A. ASTM C 890 B. ASTM C 913 7.THIS STRUCTURE IS DESIGNED TO THE PARAMETERS NOTED HEREIN. PLEASE VERIFY THAT THESE PARAMETERS MEET PROJECT REQUIREMENTS (I.E. LIVE LOAD, FILL RANGE, WATER TABLE). IF DESIGN PARAMETERS ARE INCORRECT, REVIEWING ENGINEER/AUTHORITY SHALL NOTIFY OLDCASTLE INFRASTRUCTURE UPON REVIEW OF THIS SUBMITTAL. 8.OVERSIZED HOLES TO ACCOMMODATE SPECIFIC PIPE TYPE MUST BE CONCENTRIC TO PIPE ID. AFTER PIPES ARE INSTALLED, ALL ANNULAR SPACES SHALL BE FILLED WITH A MINIMUM OF 3000 PSI CONCRETE FOR FULL THICKNESS OF PRECAST WALLS. 9.CONTRACTOR RESPONSIBLE TO VERIFY ALL SIZES, LOCATIONS AND ELEVATIONS OF OPENINGS. 10. CONTRACTOR RESPONSIBLE TO ENSURE ADEQUATE BEARING SURFACE IS PROVIDED (I.E. COMPACTED AND LEVEL PER PROJECT SPECIFICATIONS). 11. ADAPTORS/ANGLES AND EXTERNAL PIPING BY OTHERS. 12. SYSTEM SHIPPED EMPTY. INTERNAL PIPE, FILTER MEDIA & DRAIN ROCK PROVIDED IN BULK & INSTALLED BY OTHERS. 13. MAXIMUM PICK WEIGHT: = 45,000 LBS . (MEDIA SHIPPED SEPARATELY AND INSTALLED BY CONTRACTOR). 14. OLDCASTLE REPRESENTATIVE TO BE ON SITE TO OVERSEE THE INSTALLATION OF ALL INTERNAL COMPONENTS BY INSTALLING CONTRACTOR. BPU1024-IB-PV *WADOE GULD APPROVED* Max Treatment Flow = 0.72 cfs Max Peak Flow = 20 cfs SITE SPECIFIC DATA Structure ID Model Size Orientation (Left or Right) Treatment Flow Rate (cfs) Peak Flow Rate (cfs) Rim Elevation Pipe Data Pipe Location (Front or Side)Pipe Size Pipe Type Invert Elevation (IE) Inlet Outlet Notes: Appendix D: Geotechnical Engineering Report Geotechnical Engineering Report The Commons Merlone Geier Partners 457 SW 148th Street, Suite 202 Burien, WA 98166 Attn: Glenn Goodman Prepared For: GeoTest Services, Inc. The Commons – Federal Way, WA - Revised July 23, 2019 GeoTest Project No. 19-0193 July 23, 2019 Project No. 19-0193 Merlone Geier Partners 457 SW 148th Street, Suite 202 Burien, Washington 98166 Regarding: Geotechnical Engineering Report - Revised The Commons 32000 Block of Pacific Highway South Federal Way, Washington 98003 Dear Mr. Goodman, As requested, GeoTest Services, Inc. (GeoTest) is pleased to submit the following report summarizing the results of our geotechnical evaluation for the proposed development at The Commons located on the 32000 Block of Pacific Highway South in Federal Way, Washington (Vicinity Map, Figure 1). This report has been prepared in general accordance with the terms and conditions established in our services agreement dated March 12, 2019 and authorized by Mr. Glen Goodman. We appreciate the opportunity to provide geotechnical services on this project and look forward to assisting you during the construction phase. Should you have any further questions regarding the information contained within the report, or if we may be of service in other regards, please contact the undersigned. Respectfully, GeoTest Services, Inc. Kurt Parker, L.E.G. Edwardo Garcia, P.E. Geotechnical Department Manager Geotechnical Department Manager Enclosure: Revised Geotechnical Engineering Report GeoTest Services, Inc. The Commons – Federal Way, WA - Revised July 23, 2019 GeoTest Project No. 19-0193 TABLE OF CONTENTS PURPOSE AND SCOPE OF SERVICES .................................................................................................................................. 1 PROJECT DESCRIPTION ............................................................................................................................................................... 1 SITE CONDITIONS ............................................................................................................................................................................. 1 Surface Conditions ......................................................................................................................................................................... 1 Subsurface Soil Conditions ...................................................................................................................................................... 2 General Geologic Conditions ................................................................................................................................................. 3 Groundwater ..................................................................................................................................................................................... 4 GEOLOGIC HAZARDS ................................................................................................................................................................... 4 Landslide Hazard ........................................................................................................................................................................... 4 Erosion Hazard ................................................................................................................................................................................ 4 Seismic Hazard ................................................................................................................................................................................. 5 Volcanic Hazard ............................................................................................................................................................................... 5 CONCLUSIONS AND RECOMMENDATIONS ...................................................................................................................6 Site Preparation and Earthwork ..........................................................................................................................................7 Fill and Compaction .....................................................................................................................................................................7 Reuse of On-Site Soil ............................................................................................................................................................. 8 Structural Fill ............................................................................................................................................................................... 8 Compaction of Structural Fill .......................................................................................................................................... 8 Wet Weather Earthwork .......................................................................................................................................................... 9 Seismic Design Considerations ........................................................................................................................................... 9 Foundation Support .................................................................................................................................................................. 10 Allowable Bearing Capacity ............................................................................................................................................. 11 Foundation Settlement ....................................................................................................................................................... 11 Floor Support .................................................................................................................................................................................... 11 Foundation and Site Drainage ........................................................................................................................................... 12 Resistance to Lateral Loads .................................................................................................................................................. 13 Temporary and Permanent Slopes ................................................................................................................................ 14 Utilities ................................................................................................................................................................................................. 14 Pavement Subgrade Preparation .................................................................................................................................... 15 Reuse of Existing Material ................................................................................................................................................ 15 Flexible Pavement Sections – Light Duty .............................................................................................................. 16 Concrete Pavement Sections ........................................................................................................................................ 16 Stormwater Infiltration Potential ...................................................................................................................................... 16 Stormwater Treatment ....................................................................................................................................................... 17 Geotechnical Consultation and Construction Monitoring ............................................................................. 17 USE OF THIS REPORT .................................................................................................................................................................. 18 REFERENCES ................................................................................................................................................................................... 20 GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 1 July 23, 2019 GeoTest Project No. 19-0193 PURPOSE AND SCOPE OF SERVICES The purpose of this evaluation is to establish general subsurface conditions beneath the site from which conclusions and recommendations pertaining to project design can be formulated. Our scope of services includes the following tasks: · Exploration of soil and groundwater conditions underlying the site by advancing 8 hollow stem auger borings with a subcontracted drilling service to evaluate subsurface conditions. · Laboratory testing on representative samples to classify and evaluate the engineering characteristics of the soils encountered. · To provide a written report containing a description of subsurface conditions, exploration logs, findings and recommendations pertaining to site preparation and earthwork, fill and compaction, seismic design, foundation recommendations, concrete slab-on-grade construction, foundation and site drainage, utilities, temporary and permanent slopes, utilities, pavement, stormwater infiltration feasibility, geotechnical consultation and construction monitoring. PROJECT DESCRIPTION GeoTest understands that there are plans to construct three new single-story retail buildings and associated infrastructure at the above location. The new structures will contain a total of approximately 28,300 SF of new retail building space along with parking stall and drive access. We were provided a conceptual site plan for the purpose of project planning and report composition. SITE CONDITIONS This section includes a description of the general surface and subsurface conditions observed at the project site during the time of our field investigation. Interpretations of site conditions are based on the results and review of available information, site reconnaissance, subsurface explorations, laboratory testing, and previous experience in the project vicinity. Surface Conditions The subject area is presently surfaced with asphalt and contains established drive lanes and parking. The project site and vicinity are generally level in all directions and contain retail businesses in an urban environment. The project site is bordered to the north by South 320th Street, to the west by Pacific Highway South, and to the east and south by asphalt parking and drive lanes, with The Commons retail shopping mall further to the south. The area is sparsely vegetated with landscape plantings including GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 2 July 23, 2019 GeoTest Project No. 19-0193 various grass lawns, shrubs, hedges and deciduous trees. There was no observed surface water noted at the time of our exploration. Photo 1. Site surface conditions taken from the vicinity of B-6 in the north-central area of the project near South 320th Street. View looking southwest. Subsurface Soil Conditions Subsurface conditions were explored by advancing 8 soil borings (B-1 through B-8) on April 26, 2019. The explorations were advanced to depths of between 16.5 and 21.5 feet below ground surface (BGS) using a 6-inch diameter, hollow-stem auger soil drill on a trailer-mounted assembly. Samples were generally taken at 2.5-foot and 5-foot intervals. A GeoTest Staff Geologist directed and observed drilling operations and logged the soils encountered. Upon completion, all of the boring locations were backfilled with soil tailings and bentonite, and the upper approximately 6 inches of the boring were capped with compacted cold patch asphalt. Please refer to the attached Site and Exploration Plan, Figure 2, for approximate boring locations. The borehole logs can be found in Appendix A (A-1 through A-8) of this report, with laboratory analysis attached as A-9 and A-10. Disturbed but representative samples were obtained during drilling by using the Standard Penetration Test (SPT) procedure in accordance with American Society for Testing and Materials ASTM D1586 during the explorations. This test and sampling method consists of driving a standard 2-inch outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a height of 30 inches. The number of blows for each 6-inch interval is recorded and the number of blows required to drive the sampler the final 12 inches is known as the Standard GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 3 July 23, 2019 GeoTest Project No. 19-0193 Penetration Resistance (“N”) or blow count. If a total of 50 blows is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are reported on the attached boring logs. The subject site was generally surfaced by 2 inches of asphalt pavement in locations tested. Below the pavement surfacing, imported, structural quality fill was found to about 2.5 feet BGS before encountering native borrow fill soils. The native borrow fill soils were observed in all locations, in varying thicknesses before encountering native soil conditions. Native borrow fill soils were encountered to depths between 10 and 16.5 feet BGS. These soils ranged from medium dense to very dense, with occasional loose intervals, were of variable color and were primarily silty, gravelly sand with occasional construction debris. Native soils encountered are interpreted to be glacial till. In majority, the underlying native soils were dense to very dense, light brown to gray, silty, gravelly sand. The native soils extended to the full depth of all explorations. The drill-rig generally had difficultly advancing through this soil horizon and blow counts or N-Values were commonly over 50 for a one-foot interval. Photo 2. Drilling in progress at borehole B-6 in the north-central area of the site, adjacent to South 320th Street. View looking south. General Geologic Conditions General geologic conditions at the site are mapped as glacial till of the Vashon Stade of the Fraser Glaciation, specifically known as Vashon Till (Booth, 2004). Glacial till GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 4 July 23, 2019 GeoTest Project No. 19-0193 refers to heterogeneous soils mixed, transported, and deposited directly by a glacier. Glacial till is generally compact diamicton containing subrounded to well-rounded clasts in a massive, silt- or sand-rich matrix. Generally, the glacial till is a few meters to a few tens of meters thick, forming undulatory surfaces. Till typically exhibits excellent bearing characteristics and low permeability due to its poor grain size sorting and high density. Areas within this mapped deposit may locally contain peat, non-glacial sediments, artificial fill and modified lands. Our on-site explorations indicate that the encountered native subsurface soil conditions are in accordance with the mapped soil units. Groundwater Subsurface water was observed at depths of approximately 10.5 to 19.5 feet below the existing ground surface at the time of our explorations. We interpret the encountered water to be perched horizons or transient water conditions that fluctuate seasonally and with storm events. The Washington State Department of Ecology Well Report Viewer indicates that nearby resource protection wells reported for The Commons shopping mall area in 2016 from depths of 11 to 16 feet BGS were in a dry condition. The groundwater conditions reported on the exploration logs are for the specific locations and dates indicated, and therefore may not be indicative of other locations and/or times. Groundwater levels are variable, and conditions will fluctuate depending on local subsurface conditions, precipitation, and changes in on-site and off-site use. GEOLOGIC HAZARDS Landslide Hazard Landslide hazard areas are those locations potentially subject to episodic downslope movement of a mass of soil or rock. There are no steep slopes mapped in the vicinity of the project site. As such, no slope related hazards exist for the new development per the Federal Way Revised Code (FWRC 19.05.070). No mitigation is recommended for this potential geologic hazard. Erosion Hazard According to the FWRC 19.05.070 an erosion hazard area is identified by 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 shoreline and/or stream bank erosion. GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 5 July 23, 2019 GeoTest Project No. 19-0193 The site is generally level and does not contain slopes greater than 15 percent with the above-mentioned soil types and are considered not susceptible to rill and inter-rill erosion; therefore, no mitigation is recommended for potential erosion hazards per FWRC 19.05.070. Seismic Hazard According to the FWRC 19.05.070, seismic hazard areas “are those areas subject to severe risk of earthquake damage as a result of seismically induced ground shaking, slope failure, settlement or soil liquefaction, or surface faulting. These conditions occur in areas underlain by cohesionless soils of low density usually in association with a shallow groundwater table.” Field findings and mapped resources indicate the site is not susceptible to severe seismic induced settlement, shaking, lateral spreading, surface faulting or slope failure because of the generally flat topography, dense, glacially compacted soils and lack of structural fault zones in the vicinity of the subject site. The site is mapped by Palmer et al., in the Liquefaction Susceptibility Map of King County, Washington (2004) as having a “very low” liquefaction susceptibility for native soils. Due to the nature of the near surface fill soils being granular, in a medium dense or greater condition in majority, and in combination with a relatively low subsurface water level, GeoTest considers the upper fill soils to be of a low risk for liquefaction induced settlement. Two locations to the south and west of the proposed development are mapped as having “low to moderate” susceptibility to liquefaction. Given the relative density and granular nature of the near surface soils as a whole, GeoTest does not recommend any specific mitigations related to a liquefaction hazard for the proposed development location. Volcanic Hazard The City of Federal Way and vicinity are in proximity to potential volcanic hazards of the Mount Rainier stratovolcano. Direct volcanic hazards associated in the City of Federal Way include lahars (volcanic mudflows) and tephra (ash fall), according to the DNR Geologic Hazards Maps webpage. Lahars are generally described as volcanic mudflows that can travel long distances from their source volcano. We recommend no mitigation for this potential geologic hazard based on project elevation and proximity to the hazard. Tephra or volcanic ashfall related hazards exist at the subject site, as they do for the entire Pacific Northwest region, which could be affected by an eruption of Mount Rainier or other Cascade Range volcanoes. We recommend no additional mitigation for this type of volcanic hazard, however the client and owner should be aware that volcanic ash “can pose significant disruption and damage to buildings, transportation, water and wastewater, power supply, communications equipment, and agriculture, leading to potentially substantial societal impacts and costs, even at thicknesses of only a few millimeters or inches. Fine-grained ash, when ingested, can cause health impacts to humans and animals” according to DNR sources. GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 6 July 23, 2019 GeoTest Project No. 19-0193 CONCLUSIONS AND RECOMMENDATIONS Based on the evaluation of the data collected during this investigation, it is our opinion that the subsurface conditions at the site are suitable for the proposed development, provided the recommendations contained herein are incorporated into the project design. As previously stated, our explorations generally encountered native dense to very dense, silty, gravelly sand glacial till soils underlying varying depths of medium dense to very dense native borrow fill from previous development. The native soils will provide excellent bearing capacity but poor to negligible permeability. Glacial till was found at depths that are not considered to be cost effective if utilizing traditional shallow foundation construction techniques. Our delineation of the existing borrow fill sections was determined in part by topographic map review, as well as encountering of construction debris at depths of near 10 feet BGS. The 1949 Poverty Bay, Washington topographic map published by the USGS depicts the site as having low lying or swampy areas in the southwest area of the project as well as a seasonal creek channel on the eastern margin. GeoTest assumes that site was filled to near present grade with locally sourced material during development of The Commons shopping mall and other local vicinity areas. Due to the assumed relatively light loading conditions of the new structures, we recommend placing new foundations on properly compacted structural fill over the existing native borrow fill soils found across the site. GeoTest recommends that the new foundation locations be supported by at least 2 feet of structural fill, following removal of the existing borrow fill. Geotest also recommends the use of a woven geotextile fabric such as TenCate® Mirafi® RS280i (or industry equivalent) be placed at the interface between the existing fill soil and the new imported structural fill for uniform support across the foundation alignments. Foundation support may be provided by placing foundations directly on undisturbed dense to very dense, glacial till encountered at depths ranging between 10.5 and 16.5 feet BGS. Removal of the native borrow fill sections may not be feasible due to the depth to which they extend and the associated cost of removal and replacement. If it is the intent of the designer to place foundations in direct contact with the native glacial till soils, we recommend that a deep foundation system be considered in lieu of significant overexcavation and removal of existing material. Further recommendations for deep foundation systems can be made on request. The majority of on-site near surface soils contain elevated fines content ranging from 20 to 40 percent. We consider the reuse of existing fill soils to be feasible across the site if the soils are at or within 3 percent of optimum moisture content. Soils with a fines content greater than 5 to 10 percent can be difficult or impossible to compact to industry standards when over optimum moisture levels. We recommend existing soils be reused during the dry season (April through October) or as conditions permit. GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 7 July 23, 2019 GeoTest Project No. 19-0193 Based on the presence of the uncontrolled and variable density native borrow fill soils, GeoTest does not recommend that on-site infiltration be incorporated as part of stormwater design for the proposed development. Low Impact Development stormwater management with the use of raingardens or bioswales can be considered by the designer, however existing fill and dense native conditions may dictate the use of detention or retention systems, depending on final design. Site Preparation and Earthwork The portions of the site proposed for new foundation(s), floor slabs, pavement and/or sidewalk development should be prepared by removing existing pavements, topsoil, deleterious material and significant accumulations of organics. We recommend that new foundations be supported by a minimum of 2 feet of structural fill with TenCate® Mirafi® RS280i (or industry equivalent) geotextile fabric placed at the existing fill interface before placing new imported fill. Areas planned for floor slabs, pavement and walkways may be prepared by removing at least 1 foot of existing fill soils and replacement with structural fill as discussed further herein. Prior to placement of any foundation elements or structural fill, the exposed subgrade under all areas to be occupied by soil-supported floor slabs, spread, or continuous foundations should be recompacted to a firm and unyielding condition. Verification of compaction can be accomplished through proof rolling with a loaded dump truck, large self-propelled vibrating roller, or similar piece of equipment applicable to the size of the excavation. The purpose of this effort is to identify loose or soft soil deposits so that, if feasible, the soil disturbed during site work can be recompacted. Proof rolling should be carefully observed by qualified geotechnical personnel. Areas exhibiting significant deflection, pumping, or over-saturation that cannot be readily compacted should be overexcavated to firm soil. Overexcavated areas should be backfilled with compacted granular material placed in accordance with subsequent recommendations for structural fill. During periods of wet weather, proof rolling could damage the exposed subgrade. Under these conditions, qualified geotechnical personnel should observe subgrade conditions to determine if proof rolling is feasible. Proof rolling may not be feasible for certain locations within excavated footings, trench areas, or other difficult access zones when using a full-size dump truck or other large machinery. In this situation, we recommend alternate means of verification such as nuclear-densometer testing, Dynamic Cone Penetrometer (DCP) testing or soil probe methods be employed to verify suitability of field conditions. Fill and Compaction Structural fill used to obtain final elevations for footings and soil-supported floor slabs must be properly placed and compacted. In most cases, any non-organic, predominantly granular soil may be used for fill material provided the material is properly moisture conditioned prior to placement and compaction, and the specified degree of compaction is obtained. Fill soil containing topsoil, wood, trash, organic GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 8 July 23, 2019 GeoTest Project No. 19-0193 material, or construction debris is not suitable for reuse as structural fill and should be properly disposed offsite or placed in nonstructural areas. Soils containing more than approximately 5 percent fines are considered moisture sensitive and are difficult to compact to a firm and unyielding condition when over the optimum moisture content by more than approximately 2 percent. The optimum moisture content is that which allows the greatest dry density to be achieved at a given level of compactive effort. Reuse of On-Site Soil The on-site fill soils are considered suitable for reuse as structural fill if free from prior construction debris and significant organic material and are within 2 percent of optimum moisture content. As such, we recommend reuse of these soils be limited to use during the dry season (April through October) or as conditions permit. The existing fill soils may be used for landscape and other non-structural fill elements. During the winter wet season, it may be difficult or impossible to reuse the existing fill soil as structural fill and compact to acceptable standards due to high fines content. Structural Fill GeoTest recommends that imported structural fill consist of clean, well-graded sandy gravel, gravelly sand, or other approved naturally occurring granular material (“pit run”) with at least 30 percent retained on the No. 4 sieve, or a well-graded crushed rock. Structural fill for dry weather construction may contain up to 10 percent fines (that portion passing the U.S. No. 200 sieve) based on the portion passing the U.S. No. 4 sieve. The use of an imported fill having more than 10 percent fines may be feasible, but the use of these soils should generally be reviewed by the design team prior to the start of construction. Imported structural fill with less than 5 percent fines should be used during wet weather conditions. If construction occurs during the wet season or rainy conditions, soil moisture contents could be high enough that it may be difficult to compact even clean imported select granular fill to a firm and unyielding condition. Soils with an over-optimum moisture content should be scarified and dried back to a suitable moisture content during periods of dry weather or removed and replaced with drier structural fill. Compaction of Structural Fill Structural fill should be placed in horizontal lifts. The structural fill must measure 8 to 10 inches in loose thickness and be thoroughly compacted with machinery appropriate to the task. All structural fill placed under load bearing areas should be compacted to at least 95 percent of the maximum dry density, as determined using test method ASTM D1557. The top of the compacted structural fill should extend outside all foundations and other structural improvements a minimum distance GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 9 July 23, 2019 GeoTest Project No. 19-0193 equal to the thickness of the fill. We recommend that compaction be tested after placement of each lift in the fill zones. Wet Weather Earthwork The existing fill and native soils are particularly susceptible to degradation during wet weather. As a result, it may be difficult to control the moisture content of site soils during the wet season. If construction takes place during wet weather, GeoTest recommends that structural fill consist of imported, clean, well-graded sandy gravel or gravelly sand with low fines content as described above. If fill is to be placed or earthwork is to be performed in wet conditions, the contractor may reduce soil disturbance by: · Limiting the size of areas that are stripped of topsoil and left exposed · Accomplishing earthwork in small sections · Limiting construction traffic over unprotected soil · Sloping excavated surfaces to promote runoff · Limiting the size and type of construction equipment used · Providing gravel ‘working mats’ over areas of prepared subgrade · Removing wet surficial soil prior to commencing fill placement each day · Sealing the exposed ground surface by rolling with a smooth drum compactor or rubber-tired roller at the end of each working day · Providing up-gradient perimeter ditches or low earthen berms and using temporary sumps to collect runoff and prevent water from ponding and damaging exposed subgrades Seismic Design Considerations The Pacific Northwest is seismically active and the site could be subject to movement from a moderate or major earthquake. Consequently, moderate levels of seismic shaking should be accounted for during the design life of the project, and the proposed structure should be designed to resist earthquake loading using appropriate design methodology. For structures designed using the seismic design provisions of the 2015 International Building Code, the existing fill and glacial till soils underlying the site within the upper 100 feet is classified as Site Class D, according to 2010 ASCE -7 Standard – Table 20.3-1, Site Class Definitions. The corresponding values for calculating a design response spectrum for the soil profile type is considered appropriate for the site. Please reference the following values for seismic structural design purposes: Conterminous 48 States – 2015 International Building Code Zip Code 98003 Central Latitude = 47.3145, Central Longitude = -122.3120 GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 10 July 23, 2019 GeoTest Project No. 19-0193 Short Period (0.2 sec) Spectral Acceleration Maximum Considered Earthquake (MCE) Value of Ss = 1.294 (g) Site Response Coefficient, Fa = 1 (Site Class D) Adjusted spectral response acceleration for Site Class D, SMS = Ss x Fa = 1.294 (g) Design spectral response acceleration for Site Class D, SDS = 2/3 x SMs = 0.862 (g) One Second Period (1 sec) Spectral Acceleration Maximum Considered Earthquake (MCE) Value of S1 = 0.496 (g) Site Response Coefficient, Fv = 1.504 (Site Class D) Adjusted spectral response acceleration for Site Class D, SM1 = S1 x Fv = 0.746 (g) Design spectral response acceleration for Site Class D, SD1 = 2/3 x SM1 = 0.497 (g) Foundation Support Continuous or isolated spread footings founded on two feet of properly compacted structural fill placed over the native borrow fill soils can provide foundation support for the proposed improvements. We recommend that a woven geotextile fabric, such as Tencate® Mirafi® RS280i (or industry equivalent), be placed directly on native borrow fill soils prior to the placement of structural fill. GeoTest recommends that the existing fill be recompacted prior to the placement of geotextile fabric. We recommend that qualified geotechnical personnel confirm that suitable bearing conditions have been reached prior to placement of geotextile fabric, structural fill or foundation formwork. To provide proper support, GeoTest recommends that any pavement, construction debris, deleterious material or soil with organic content greater than 3 percent be removed from beneath the building foundation area(s) and be replaced with properly compacted structural fill as described in the Fill and Compaction section of this report. Localized overexcavation, if necessary, can be backfilled to the design footing elevation with structural fill or lean concrete. The limits of the excavation should extend laterally beyond the edge of each side of the footing a distance equal to the depth of the excavation below the base of the footing. If lean concrete is used to backfill the excavation, the limits of the excavation need only extend a nominal distance beyond the width of the footing. In addition, GeoTest recommends that foundation elements for the proposed structure(s) bear entirely on similar soil conditions to help prevent differential settlement from occurring. Continuous and isolated spread footings should be founded 18 inches, minimum, below the lowest adjacent final grade for freeze/thaw protection. The footings should be sized in accordance with the structural engineer’s prescribed design criteria and seismic considerations. GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 11 July 23, 2019 GeoTest Project No. 19-0193 Allowable Bearing Capacity Assuming the above foundation support criteria are satisfied, continuous or isolated spread footings founded on geotextile supported, compacted structural fill placed directly over existing fill soils may be proportioned using a net allowable soil bearing pressure of up to 2,000 pounds per square foot (psf). The "net allowable bearing pressure" refers to the pressure that can be imposed on the soil at foundation level. This pressure includes all dead loads, live loads, the weight of the footing, and any backfill placed above the footing. The net allowable bearing pressure may be increased by one-third for transient wind or seismic loads. Foundation Settlement Settlement of shallow foundations depends on foundation size and bearing pressure, as well as the strength and compressibility characteristics of the underlying soil. If construction is accomplished as recommended and at the maximum allowable soil bearing pressure, GeoTest estimates the total settlement of building foundations to be less than one inch. Differential settlement between two adjacent load-bearing components supported on competent soil is estimated to be less than one half the total settlement. Floor Support Conventional slab-on-grade floor construction is feasible for the planned site improvements. Floor slabs may be supported on properly placed and compacted structural fill placed over properly prepared native soil. We recommend that floor slabs be supported by at least 1 foot of imported structural fill, which may include a capillary break as addressed below. Prior to placement of structural fill, the native borrow fill soil should be recompacted if disturbed and proof-rolled or otherwise verified as firm and unyielding as recommended in the Site Preparation and Earthwork section of this report. Floor slabs may be supported by existing fill soils that were found at our borehole locations below the asphalt surfacing, however the potential for differential settlement exists and may be mitigated by placing 6 inches of structural fill below 6 inches of capillary break material prior to concrete placement. GeoTest recommends verification of existing conditions by shallow potholing prior to placement of imported fill and concrete elements if proof rolling is not feasible. All existing fill soils to remain in place for slab support should be recompacted with proper equipment such as a large vibrating roller or hoe-pack prior to new fill placement. GeoTest recommends that interior concrete slab-on-grade floors be underlain with at least 6 inches of clean, compacted, angular free-draining gravel. The gravel should contain less than 3 percent passing the U.S. Standard No. 200 sieve (based on a wet sieve analysis of that portion passing the U.S. Standard No. 4 sieve). The purpose of this gravel layer is to provide uniform support for the slab, provide a capillary break, GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 12 July 23, 2019 GeoTest Project No. 19-0193 and act as a drainage layer. To help reduce the potential for water vapor migration through floor slabs, a continuous 10 to 15-mil minimum thickness polyethylene sheet with tape-sealed joints should be installed below the slab to serve as an impermeable vapor barrier. The vapor barrier should be installed and sealed in accordance with the manufacturer’s instructions. Exterior concrete slabs-on-grade, such as sidewalks, may be supported directly on properly placed and compacted structural fill or existing fill; however, long-term performance will be enhanced if exterior slabs are placed on a layer of clean, durable, well-draining granular material. Foundation and Site Drainage GeoTest understands that new development will likely utilize the existing drainage system in part and incorporate additional stormwater controls, as necessary, on completion of the final design and site layout. Positive surface gradients should be provided adjacent to the proposed building(s) to direct surface water away from the structure and toward suitable drainage facilities. Roof drainage should not be introduced into the perimeter footing drains but should be separately discharged directly to the stormwater collection system or similar municipality-approved outlet. Pavement and sidewalk areas should be sloped, and drainage gradients should be maintained to carry surface water away from the buildings toward an approved stormwater collection system. Surface water should not be allowed to pond and soak into the ground surface near buildings or paved areas during or after construction. Construction excavations should be sloped to drain to sumps where water from seepage, rainfall, and runoff can be collected and pumped to a suitable discharge facility. To reduce the potential for groundwater and surface water to seep into interior spaces, GeoTest recommends that an exterior footing drain system be constructed around the perimeter of new building foundations as shown in the Typical Footing Drain Section (Figure 3) of this report. The drain should consist of a perforated pipe measuring 4 inches in diameter at minimum, surrounded by at least 12 inches of filtering media. The pipe should be sloped to carry water to an approved collection system. The filtering media may consist of open-graded drain rock wrapped in a nonwoven geotextile fabric such as Mirafi 140N (or industry equivalent). For foundations supporting retaining walls, drainage backfill should be carried up the back of the wall and be at least 12 inches wide. The drainage backfill should extend from the foundation drain to within approximately 1 foot of the finished grade and consist of open-graded drain rock containing less than 3 percent fines by weight passing the U.S. Standard No. 200 sieve. The invert of the footing drain pipe should be placed at approximately the same elevation as the bottom of the footing or 12 inches below the adjacent floor slab grade, whichever is deeper, so that water will be contained. This GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 13 July 23, 2019 GeoTest Project No. 19-0193 process prevents water from seeping through walls or floor slabs. The drain system should include cleanouts to allow for periodic maintenance and inspection. Resistance to Lateral Loads The lateral earth pressures that develop against foundation walls will depend on the method of backfill placement, degree of compaction, slope of backfill, type of backfill material, provisions for drainage, magnitude and location of any adjacent surcharge loads, and the degree to which the wall can yield laterally during or after placement of backfill. If the wall is allowed to rotate or yield so the top of the wall moves an amount equal to or greater than about 0.001 to 0.002 times its height (a yielding wall), the soil pressure exerted comprises the active soil pressure. When a wall is restrained against lateral movement or tilting (a nonyielding wall), the soil pressure exerted comprises the at rest soil pressure. Wall restraint may develop if a rigid structural network is constructed prior to backfilling or if the wall is inherently stiff. GeoTest recommends that yielding walls under drained conditions be designed for an equivalent fluid density of 35 pounds per cubic ft (pcf) for structural fill and 40 pcf for existing fill or native material in active soil conditions. Nonyielding walls under drained conditions should be designed for an equivalent fluid density of 55 pcf for structural fill and 60 pcf for existing fill or native material in at-rest conditions. Design of walls should include appropriate lateral pressures caused by surcharge loads located within a horizontal distance equal to or less than the height of the wall. For uniform surcharge pressures, a uniformly distributed lateral pressure equal to 35 percent and 50 percent of the vertical surcharge pressure should be added to the lateral soil pressures for yielding and nonyielding walls, respectively. Passive earth pressures developed against the sides of building foundations, in conjunction with friction developed between the base of the footings and the supporting subgrade, will resist lateral loads transmitted from the structure to its foundation. For design purposes, the passive resistance of well-compacted structural fill placed against the sides of foundations is equivalent to a fluid with a density of 250 pounds per cubic foot. If utilizing native soil as backfill, the passive resistance of well- compacted existing or native fill placed against the sides of foundations is equivalent to a fluid with a density of 250 pounds per cubic foot. The recommended value includes a safety factor of about 1.5 and is based on the assumption that the ground surface adjacent to the structure is level in the direction of movement for a distance equal to or greater than twice the embedment depth. The recommended value also assumes drained conditions that will prevent the buildup of hydrostatic pressure in the compacted fill. Foundation walls should include a drain system constructed in general accordance with the recommendations presented in the Foundation and Site Drainage section of this report. In design computations, the upper 12 inches of passive resistance should be neglected if the soil is not covered by floor slabs or pavement. If future plans call for the removal of the soil providing resistance, the passive resistance should not be considered. GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 14 July 23, 2019 GeoTest Project No. 19-0193 An allowable coefficient of base friction of 0.35, applied to vertical dead loads only, may be used between the underlying imported granular structural fill and the base of the footing. We recommend an allowable coefficient of friction of 0.30 for native soil or existing fill. If passive and frictional resistance are considered together, one half the recommended passive soil resistance value should be used since larger strains are required to mobilize the passive soil resistance as compared to frictional resistance. A safety factor of about 1.5 is included in the base friction design value. GeoTest does not recommend increasing the coefficient of friction to resist seismic or wind loads. Temporary and Permanent Slopes Actual construction slope configurations and maintenance of safe working conditions, including temporary excavation stability, should be the responsibility of the contractor, who is able to monitor the construction activities and has direct control over the means and methods of construction. All applicable local, state, and federal safety codes should be followed. All open cuts should be monitored during and after excavation for any evidence of instability. If instability is detected, the contractor should flatten the side slopes or install temporary shoring. Temporary excavations in excess of 4 ft should be shored or sloped in accordance with Safety Standards for Construction Work Part N, WAC 296-155-66403. Temporary unsupported excavations in the fill and native soil encountered at the project site are classified as a Type B soil according to WAC 296-155-66401 and may be sloped as steep as 1:1 (Horizontal: Vertical). All soils encountered are classified as Type C soil in the presence of groundwater seepage and shall be sloped at 1.5:1 (H:V). Flatter slopes or temporary shoring may be required in areas where groundwater flow is present and unstable conditions develop. Temporary slopes and excavations should be protected as soon as possible using appropriate methods to prevent erosion during periods of wet weather. We recommend that permanent cut or fill slopes be designed for inclinations of 2H:1V or flatter. Sloped areas that contain ponds, reservoirs or other water retaining/detaining structures shall be designed for inclinations of 3H:1V or flatter geometry. All permanent slopes should be vegetated or otherwise protected to limit the potential for erosion as soon as practical after construction. Utilities Utility trenches must be properly backfilled and compacted to reduce cracking or localized loss of foundation, slab, or pavement support. Excavations for new shallow underground utilities are expected to be placed within very dense glacial till soils or in existing fill, dependent on elevation and location. Trench backfill in improved areas (beneath structures, pavements, sidewalks, etc.) should consist of structural fill as defined in the Fill and Compaction section of this report and may consist of imported, existing or native soils. The selection of soil GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 15 July 23, 2019 GeoTest Project No. 19-0193 material for trench backfill will depend on moisture contents and general seasonal conditions. Outside of improved areas, trench backfill may consist of reused native material or existing fill provided the backfill can be compacted to the project specifications. Trench backfill should be placed and compacted in general accordance with the recommendations presented in the Fill and Compaction section of this report. Surcharge loads on trench support systems due to construction equipment, stockpiled material, and vehicle traffic should be included in the design of any anticipated shoring system. The contractor should implement measures to prevent surface water runoff from entering trenches and excavations. In addition, vibration as a result of construction activity and traffic may cause caving of the trench walls. The contractor is responsible for trench configurations. All applicable local, state, and federal safety codes should be followed. All open cuts should be monitored by the contractor during excavation for any evidence of instability. If instability is detected, the contractor should flatten the side slopes or install temporary shoring. If groundwater or groundwater seepage is present, and the trench is not properly dewatered, the soil within the trench zone may be prone to caving, channeling, and running. Trench widths may be substantially wider than under dewatered conditions. Pavement Subgrade Preparation The final design and lateral extent of new pavements at the project site is unknown at present. We assume that some areas of the project site will be designed for new pavements, while other locations may be designated for resurfacing by crack/chip seal, grind and overlay or other similar methods. Some locations are anticipated to incorporate new imported fill, while other areas may be suited to use the in-place near surface fill material typically encountered in the upper 2 feet for asphalt pavement support. The following recommendations are meant as a guideline for the design engineer to develop final pavement sections in accordance with current codes and standards. Reuse of Existing Material We understand that the reuse of the existing gravel base material is being considered by the design team for parking and driveway subgrade support. Soils explored in boreholes B-1 through B-8 were similar in composition in the upper 2 to 2.5 feet and consisted of generally medium dense, brown, dry to damp, silty, gravelly sand. These near surface soils were considered to be of structural fill quality and, in our opinion, are suitable for reuse as parking subgrade soil provided that they are placed and/or remedially compacted to structural fill requirements per the plans and specifications. During construction and where site grading lowers the site by more than 2 vertical feet, we recommend that the material being considered for reuse be separated from the underlying native borrow fill and stockpiled separately. GeoTest should observe stripping and stockpiling operations in order to document issues or concerns with the stripping process. GeoTest is specifically concerned about the mixing of the “clean”, GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 16 July 23, 2019 GeoTest Project No. 19-0193 low silt content structural fill quality materials and the siltier borrow fill materials at depth. After the near-surface soils have been appropriately stripped and stockpiled, they can be placed and compacted as structural fill per our report. In areas where the near-surface soils are left in place and remedially compacted to structural fill requirements, GeoTest should perform suitable testing methods such as nuclear densometer testing or proof roll observation to confirm that the required densities per the plans and specifications are obtained. Flexible Pavement Sections – Light Duty If utilized within light vehicle parking and driveway areas, we recommend a standard, or “light duty”, pavement section consist of 2 inches of Class ½-inch HMA asphalt above 2 inches of Crushed Surfacing Top Course (CSTC) meeting criteria set forth in the Washington State Department of Transportation (WSDOT) Standard Specification 9-03.9(3). The base material for the road section should consist of “gravel base” which may include 8 inches of gravel borrow (with 100% passing the 2-inch sieve) or 6 inches of Crushed Surfacing Base Bourse (CSBC) as classified by WSDOT 9-03.9(3) Standards and Specifications. Concrete Pavement Sections Concrete pavements could be used for access drives, parking areas, sidewalks, aprons and other features such as garbage enclosures. Design of concrete pavements is a function of concrete strength, reinforcement steel, and the anticipated loading conditions for the roads. For design purposes, a vertical modulus of subgrade reaction of 200 pounds per cubic inch (pci) should be expected for concrete elements constructed over properly placed and compacted Structural Fill. GeoTest expects that concrete pavement sections, if utilized, will be at least 4 inches thick and be founded on a minimum of 6 inches of compacted gravel base. The design of concrete access and parking areas will need to be performed by a structural engineer. GeoTest recommends that subgrade soils supporting concrete pavement sections include minor grade changes to allow for passive drainage away from the pavement. GeoTest is available to further consult, review and/or modify our pavement section recommendations based on further discussion and/or analysis with the project team/owner. The above pavement sections are initial recommendations and may be accepted and/or modified by the site civil engineer based on the actual finished site grading elevations and/or the owner’s preferences. Stormwater Infiltration Potential Based on the presence of the uncontrolled and variable density native borrow fill soils overlying dense to very dense native conditions, GeoTest does not recommend that on-site stormwater infiltration be incorporated as part of the design for the proposed development. The designer may consider Low Impact Development (LID) design such as raingardens or bioswales be incorporated in combination with detention facilities. GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 17 July 23, 2019 GeoTest Project No. 19-0193 Stormwater Treatment The stormwater facilities on-site may require some form of pollutant pretreatment with an amended soil prior to on-site infiltration or offsite discharge. The reuse of on- site soil is often the most sustainable and cost-effective method for pollutant treatment purposes. Cation exchange capacities, organic contents, and pH of site subsurface soils were also tested to determine possible pollutant treatment suitability. Cation exchange capacity, organic content, and pH tests were performed by Northwest Agricultural Consultants on four soil samples collected from the explorations shown in Table 1. A summary of the laboratory test results is presented below. TABLE 1 Cation Exchange Capacity, Organic Content, and pH Laboratory Test Results Test Pit ID Sample Depth (ft) Geologic Unit Cation Exchange Capacity (meq/100 grams) Organic Content (%) pH B-3 2.5 Native Fill 5.8 0.83 7.0 B-4 2.5 Native Fill 6.3 1.91 7.1 B-4 5.0 Native Fill 6.3 2.10 6.5 B-7 5.0 Native Fill 13.0 5.06 5.9 Suitability for onsite pollutant treatment is determined in accordance with SSC-6 of the 2012 Washington State Department of Ecology Stormwater Management Manual for Western Washington. Soils with an organic content of greater than or equal to 1 percent and a cation exchange capacity of greater than or equal to 5 meq/100 grams are characterized as suitable for stormwater treatment. Based on the results shown in Table 1, soils within the upper 5 feet are generally meet the organic and CEC criteria. However, due to the elevated fines content, variable construction debris volume and potential for low to negligible infiltration, the owner may elect to import amended soils with the desired properties for planned treatment facilities. GeoTest is available to perform additional laboratory testing as part of an expanded scope of services. Geotechnical Consultation and Construction Monitoring GeoTest recommends that we be involved in the project design review process. The purpose of the review is to verify that the recommendations presented in this report are understood and incorporated in the design and specifications. GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 18 July 23, 2019 GeoTest Project No. 19-0193 We also recommend that geotechnical construction monitoring services be provided. These services should include observation by GeoTest personnel during structural fill placement, compaction activities and subgrade preparation operations to confirm that design subgrade conditions are obtained beneath the areas of improvement. Periodic field density testing should be performed to verify that the appropriate degree of compaction is obtained. The purpose of these services is to observe compliance with the design concepts, specifications, and recommendations of this report. In the event that subsurface conditions differ from those anticipated before the start of construction, GeoTest Services would be pleased to provide revised recommendations appropriate to the conditions revealed during construction. GeoTest is available to provide a full range of materials testing and special inspection during construction as required by the local building department and the International Building Code. This may include specific construction inspections on materials such as reinforced concrete, reinforced masonry, wood framing and structural steel. These services are supported by our fully accredited materials testing laboratory. USE OF THIS REPORT GeoTest Services has prepared this report for the exclusive use of Merlone Geier Partners and their design consultants for specific application to the design of the proposed The Commons development located at the 32000 Block of Pacific Highway South in Federal Way, Washington. Use of this report by others is at the user’s sole risk. This report is not applicable to other site locations. Our services are conducted in accordance with accepted practices of the geotechnical engineering profession; no other warranty, express or implied, is made as to the professional advice included in this report. Our site explorations indicate subsurface conditions at the dates and locations indicated. It is not warranted that these conditions are representative of conditions at other locations and times. The analyses, conclusions, and recommendations contained in this report are based on site conditions to the limited depth and time of our explorations, a geological reconnaissance of the area, and a review of previously published geological information for the site. If variations in subsurface conditions are encountered during construction that differs from those contained within this report, GeoTest should be allowed to review the recommendations and, if necessary, make revisions. If there is a substantial lapse of time between submission of this report and the start of construction, or if conditions change due to construction operations at or adjacent to the project site, we recommend that we review this report to determine the applicability of the conclusions and recommendations contained herein. The earthwork contractor is responsible to perform all work in conformance with all applicable WISHA/OSHA regulations. GeoTest Services, Inc. is not responsible for job site safety on this project, and this responsibility is specifically disclaimed. GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 19 July 23, 2019 GeoTest Project No. 19-0193 Attachments: Figure 1 Vicinity Map Figure 2 Site and Exploration Plan Figure 3 Typical Footing and Wall Drain Section Figure 4 Soil Classification System and Key Figures 5-12 Field Exploration Logs Figures 13-14 Laboratory Testing Attached NW Agricultural Consultants Results Attached Limitations and Use of This Report GeoTest Services, Inc. The Commons – Federal Way, WA - Revised 20 July 23, 2019 GeoTest Project No. 19-0193 REFERENCES Bakeman, S., Dan, G., Howie, D., Killelea, J., Labib, F., & Ed, O. (n.d.). 2012 Stormwater Management Manual for Western Washington, as Amended in December 2014 (The 2014 SWMMWW) (pp. 1-1042) (United States, Washington State Department of Ecology). Booth, D. B.; Waldron, H. H.; Troost, K. G., 2004, Geologic map of the Poverty Bay 7.5' quadrangle, King and Pierce Counties, Washington: U.S. Geological Survey Scientific Investigations Map 2854, 1 sheet, scale 1:24,000. Federal Way Revised Code – Zoning and Development Code - Definitions, §§ 19.05 (2019). Palmer et al., 2004. Liquefaction Susceptibility Map of King County, Washington [Map]. Washington State Department of Natural Resources, Division of Geology and Earth Resources, Open File Report 2004-20 Structural Engineers Association of California/ Office of Statewide Health, Planning and Development (SEAOC/OSHPD) Seismic Design Maps Tool, Retrieved May 2019 from https://seismicmaps.org United States Geological Survey, Department of the Interior, 7.5-Minute Topographic Map of Poverty Bay, Washington (1949-2017) Retrieved May 2019 from https://store.usgs.gov/map-locator Washington Geologic Information Portal. (n.d.). Retrieved May 2019, from https://geologyportal.dnr.wa.gov/ Washington State Department of Ecology. (n.d.). Well Report Viewer, Retrieved May 2019 from https://fortress.wa.goc/ecy/wellconstruction/map Date:Scale: GGEEOOTTEESSTT SSEERRVVIICCEESS,,IINNCC.. 741 Marine Drive Bellingham, WA 98225 phone: (360) 733-7318 fax: (360) 733-7418 Figure By:Project THE COMMONS PACIFIC HIGHWAY SOUTH FEDERAL WAY, WA98406 19-0193 1 5-20-19 ZC As Shown VICINITY MAP 2 Miles PROJECT LOCATION MMAAPP RREEFFEERREENNCCEEDD FFRROOMM EEssrrii TTooppooggrraapphhiicc Date:Scale: GGEEOOTTEESSTT SSEERRVVIICCEESS,,IINNCC.. 741 Marine Drive Bellingham, WA 98225 phone: (360) 733-7318 fax: (360) 733-7418 Figure By:Project THE COMMONS PACIFIC HIGHWAY SOUTH FEDERAL WAY, WASHINGTON 19-0193 2 5-20-19 ZC As Shown SITE AND EXPLORATION PLAN N B-#=Approximate Boring Location 1100'' B-1 B-3 B-2 B-4 B-5 B-6 B-7 B-8 100 Feet Date:Scale: GGEEOOTTEESSTT SSEERRVVIICCEESS,,IINNCC.. 741 Marine Drive Bellingham, WA 98225 phone: (360) 733-7318 fax: (360) 733-7418 Figure By:Project THE COMMONS PACIFIC HIGHWAY SOUTH FEDERAL WAY, WA 19-0193 3 5-22-19 ZC None TYPICAL FOOTING & WALL DRAIN SECTION Notes: Footings Should be properly buried for frost protection in accordance with International Building Code or local building codes (Typically 18 inches below exterior finished grades) The footing drain will need to be modified from this typical drawing to fit the dimensions of the planned monolithic footing and slab configuration SHALLOW FOOTINGS WITH INTERIOR SLAB-ON-GRADE Slope to drain away from structure. Floor Slab Suitable Soil Suitable Soil Free Draining Sand and Gravel Fill Coarse Gravel Capillary Break (6 inch minimum typically clear crushed) Four Inch Diameter, Perforated, Rigid PVC Pipe (Perforations oriented down, wrapped in non-woven geotextile filter fabric, directed to suitable discharge) Drainage Material (Drain Rock or Clear Crushed Rock w/ no fines) Approved Non-woven Geotextile Filter Fabric (18 inch minimum fabric lap) Compacted Impervious Soil (12 inch minimum) or Pavement (2 inch minimum) Appropriate Waterproofing Applied to Exterior of Wall Vapor Barrier Typical Framing 4The Commons Pacific Highway South Federal Way, WA 1 Silty gravel; gravel/sand/silt mixture(s) Clayey gravel; gravel/sand/clay mixture(s)GC 1. Soil descriptions are based on the general approach presented in the Standard Practice for Description and Identification of Soils (Visual-Manual Procedure), as outlined in ASTM D 2488. Where laboratory index testing has been conducted, soil classifications are based on the Standard Test Method for Classification of Soils for Engineering Purposes, as outlined in ASTM D 2487. 2. Soil description terminology is based on visual estimates (in the absence of laboratory test data) of the percentages of each soil type and is defined as follows: SW ROCK ML Field and Lab Test DataDrilling and Sampling Key Portion of Sample Retained for Archive or Analysis Sample Depth Interval Recovery Depth Interval Code Description Code Sample Identification Number ATD Groundwater Approximate water elevation at time of drilling (ATD) or on date noted. Groundwater levels can fluctuate due to precipitation, seasonal conditions, and other factors. a b c d e 1 2 3 4 HIGHLY ORGANIC SOIL CLEAN GRAVEL Inorganic clay of low to medium plasticity; gravelly clay; sandy clay; silty clay; lean clay Soil Classification System Organic silt; organic, silty clay of low plasticity 50% - "GRAVEL," "SAND," "SILT," "CLAY," etc. 50% - "very gravelly," "very sandy," "very silty," etc. 30% - "gravelly," "sandy," "silty," etc. 12% - "slightly gravelly," "slightly sandy," "slightly silty," etc. 5% - "trace gravel," "trace sand," "trace silt," etc., or not noted. Inorganic clay of high plasticity; fat clay Peat; humus; swamp soil with high organic content OLCOARSE-GRAINED SOIL(More than 50% of material islarger than No. 200 sieve size)Poorly graded gravel; gravel/sand mixture(s); little or no fines > 30% and < > 12% and < > 5% and < < Primary Constituent: Secondary Constituents: Additional Constituents: (Liquid limit less than 50) Asphalt concrete pavement or Portland cement pavement Well-graded gravel; gravel/sand mixture(s); little or no fines (More than 50% of materialis smaller than No. 200 sievesize)FINE-GRAINED SOILInorganic silt and very fine sand; rock flour; silty or clayey fine sand or clayey silt with slight plasticity PT OH SAND AND SANDY SOIL GRAVEL AND GRAVELLY SOIL SP MH (Liquid limit greater than 50) Notes: > _ _ _ _ (Little or no fines) GRAVEL WITH FINES (Appreciable amount of fines) (Little or no fines) CLEAN SAND SAND WITH FINES GRAPHIC SYMBOL LETTER SYMBOL GP GM Organic clay of medium to high plasticity; organic silt Inorganic silt; micaceous or diatomaceous fine sand Well-graded sand; gravelly sand; little or no fines GRAPHIC SYMBOL (Appreciable amount of fines) DB AC or PC SM SC RK Description SAMPLER TYPESAMPLE NUMBER & INTERVAL CL GW CH SILT AND CLAY 3.25-inch O.D., 2.42-inch I.D. Split Spoon 2.00-inch O.D., 1.50-inch I.D. Split Spoon Shelby Tube Grab Sample Other - See text if applicable 300-lb Hammer, 30-inch Drop 140-lb Hammer, 30-inch Drop Pushed Other - See text if applicable PP = 1.0 TV = 0.5 PID = 100 W = 10 D = 120 -200 = 60 GS AL GT CA (More than 50% of coarse fraction retained on No. 4 sieve) (More than 50% of coarse fraction passed through No. 4 sieve) Pocket Penetrometer, tsf Torvane, tsf Photoionization Detector VOC screening, ppm Moisture Content, % Dry Density, pcf Material smaller than No. 200 sieve, % Grain Size - See separate figure for data Atterberg Limits - See separate figure for data Other Geotechnical Testing Chemical Analysis SILT AND CLAY WOOD DEBRIS Rock (See Rock Classification) Wood, lumber, wood chips Construction debris, garbage Poorly graded sand; gravelly sand; little or no fines USCS LETTER SYMBOL Silty sand; sand/silt mixture(s) Clayey sand; sand/clay mixture(s) PAVEMENT WD OTHER MATERIALS TYPICAL DESCRIPTIONS MAJOR DIVISIONS TYPICAL DESCRIPTIONS(1)(2) Soil Classification System and Key Figure Perched Conditions, ATD 46 25 25 4 50/ 5" b2 b2 b2 b2 b2 Boring Completed 04/26/19 Total Depth of Boring = 16.5 ft. AC SM SM SM 1 2 3 4 5 W = 4 GS Pavement (Asphalt) Medium dense, brown, dry to damp, silty, gravelly SAND (Fill) Very dense, gray to blue, damp, silty, very gravelly SAND with occasional organics (Native Borrow Fill) -Relative density changes to Medium Dense Dense, light brown to gray, wet, silty, gravelly SAND (Glacial Till) -Relative density changes to Very Dense 0 2 4 6 8 10 12 14 16 18 Graphic Symbol1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. Bortec1 Inc. B-1 Drilling Method: SAMPLE DATA Ground Elevation (ft): Drilled By:19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOGGROUNDWATER Sampler TypeNotes: SOIL PROFILE Blows/FootWater LevelUSCS SymbolDepth (ft)Sample Number& IntervalNot Determined Hollow-stem Auger Test DataFigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOG5Log of Boring B-1 Perched Conditions, ATD 26 22 50/ 5" 50/ 6" 50/ 3" b2 b2 b2 b2 b2 Boring Completed 04/26/19 Total Depth of Boring = 16.5 ft. AC SM SM SM 6 7 8 9 10 W = 6 GS W = 11 GS Pavement (Asphalt) Medium dense, brown, dry to damp, silty, gravelly SAND (Fill) Medium dense, gray to blue, damp, silty, very gravelly SAND with occasional organics (Native Borrow Fill) - Relative density changes to Medium Dense - Relative density changes to Very Dense - Rock lodged in sampler - Brick and metal debris observed in sampler Dense, light brown to gray, wet, silty, gravelly SAND (Glacial Till) -Relative density changes to Very Dense 0 2 4 6 8 10 12 14 16 18 Graphic Symbol1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. Bortec1 Inc. B-2 Drilling Method: SAMPLE DATA Ground Elevation (ft): Drilled By:19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOGGROUNDWATER Sampler TypeNotes: SOIL PROFILE Blows/FootWater LevelUSCS SymbolDepth (ft)Sample Number& IntervalNot Determined Hollow-stem Auger Test DataFigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOG6Log of Boring B-2 Perched Conditions, ATD 16 50/ 5" 13 60 48 50/ 5" b2 b2 b2 b2 b2 b2 Boring Completed 04/26/19 Total Depth of Boring = 21.5 ft. AC SM SM SM 11 12 13 14 15 16 W = 18 GS Pavement (Asphalt) Medium dense, brown, dry to damp, silty, gravelly SAND (Fill) Very dense, gray to blue, damp, silty, gravelly SAND with occasional organics (Native Borrow Fill) - Relative density changes to Very Dense - Relative density changes to Medium Dense Very dense, light brown to gray, wet, silty, gravelly SAND (Glacial Till) - Relative density changes to Dense - Relative density changes to Very Dense 0 2 4 6 8 10 12 14 16 18 20 22 Graphic Symbol1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. Bortec1 Inc. B-3 Drilling Method: SAMPLE DATA Ground Elevation (ft): Drilled By:19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOGGROUNDWATER Sampler TypeNotes: SOIL PROFILE Blows/FootWater LevelUSCS SymbolDepth (ft)Sample Number& IntervalNot Determined Hollow-stem Auger Test DataFigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOG7Log of Boring B-3 Perched Conditions, ATD 12 28 8 23 35 65 b2 b2 b2 b2 b2 b2 Boring Completed 04/26/19 Total Depth of Boring = 21.5 ft. AC SM SM SM 17 18 19 20 21 22 Pavement (Asphalt) Medium dense, brown, dry to damp, silty, gravelly SAND (Fill) Medium dense, gray to brown, damp, silty, gravelly SAND with occasional organics (Native Borrow Fill) - Relative density changes to Loose - Relative density changes to Medium Dense Dense, light brown to gray, wet, silty, gravelly SAND (Glacial Till) - Relative density changes to Very Dense 0 2 4 6 8 10 12 14 16 18 20 22 Graphic Symbol1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. Bortec1 Inc. B-4 Drilling Method: SAMPLE DATA Ground Elevation (ft): Drilled By:19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOGGROUNDWATER Sampler TypeNotes: SOIL PROFILE Blows/FootWater LevelUSCS SymbolDepth (ft)Sample Number& IntervalNot Determined Hollow-stem Auger Test DataFigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOG8Log of Boring B-4 Perched Conditions, ATD 12 13 5 6 34 40 b2 b2 b2 b2 b2 b2 Boring Completed 04/26/19 Total Depth of Boring = 21.5 ft. AC SM SM SM 22 23 24 25 26 27 W = 9 GS Pavement (Asphalt) Medium dense, brown, dry to damp, silty, gravelly SAND (Fill) Medium dense, gray to blue, damp, silty, gravelly SAND with occasional organics (Native Borrow Fill) - Relative density changes to Loose - Color grades to brown Dense, gray, wet, silty, gravelly SAND (Glacial Till) 0 2 4 6 8 10 12 14 16 18 20 22 Graphic Symbol1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. Bortec1 Inc. B-5 Drilling Method: SAMPLE DATA Ground Elevation (ft): Drilled By:19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOGGROUNDWATER Sampler TypeNotes: SOIL PROFILE Blows/FootWater LevelUSCS SymbolDepth (ft)Sample Number& IntervalNot Determined Hollow-stem Auger Test DataFigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOG9Log of Boring B-5 Perched Conditions, ATD 30 9 12 29 85 79 b2 b2 b2 b2 b2 b2 Boring Completed 04/26/19 Total Depth of Boring = 21.5 ft. AC SM SM SM 28 29 30 31 32 33 W = 11 GS Pavement (Asphalt) Medium dense, brown, dry to damp, silty, gravelly SAND (Fill) Medium dense, gray to blue, damp, silty, gravelly SAND with occasional organics (Native Borrow Fill) - Relative density changes to Loose - Relative density changes to Medium Dense - Brick debris observed in sampler - Relative density changes to Very Dense Very dense, gray, wet, silty, gravelly SAND (Glacial Till) 0 2 4 6 8 10 12 14 16 18 20 22 Graphic Symbol1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. Bortec1 Inc. B-6 Drilling Method: SAMPLE DATA Ground Elevation (ft): Drilled By:19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOGGROUNDWATER Sampler TypeNotes: SOIL PROFILE Blows/FootWater LevelUSCS SymbolDepth (ft)Sample Number& IntervalNot Determined Hollow-stem Auger Test DataFigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOG10Log of Boring B-6 Perched Conditions, ATD 19 5 24 32 65 50/ 4" b2 b2 b2 b2 b2 b2 Boring Completed 04/26/19 Total Depth of Boring = 21.5 ft. AC SM SM SM 34 35 36 37 38 39 W = 7 GS Pavement (Asphalt) Medium dense, brown, dry to damp, silty, gravelly SAND (Fill) Medium dense, gray to blue, damp, silty, gravelly SAND with occasional organics (Native Borrow Fill) - Relative density changes to Loose - Relative density changes to Medium Dense - Relative density changes to Dense Very dense, gray to brown, wet, silty, gravelly SAND (Glacial Till) 0 2 4 6 8 10 12 14 16 18 20 22 Graphic Symbol1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. Bortec1 Inc. B-7 Drilling Method: SAMPLE DATA Ground Elevation (ft): Drilled By:19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOGGROUNDWATER Sampler TypeNotes: SOIL PROFILE Blows/FootWater LevelUSCS SymbolDepth (ft)Sample Number& IntervalNot Determined Hollow-stem Auger Test DataFigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOG11Log of Boring B-7 Perched Conditions, ATD 65 60 26 11 41 50/ 6" b2 b2 b2 b2 b2 b2 Boring Completed 04/26/19 Total Depth of Boring = 21.5 ft. AC SM SM SM 40 41 42 43 44 45 W = 18 GS Pavement (Asphalt) Medium dense, brown, dry to damp, silty, gravelly SAND (Fill) Very dense, gray to blue, damp, silty, gravelly SAND with occasional organics (Native Borrow Fill) - Relative density changes to Medium Dense Dense, gray to brown, wet, silty, gravelly SAND (Glacial Till) - Relative density changes to Very Dense 0 2 4 6 8 10 12 14 16 18 20 22 Graphic Symbol1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. Bortec1 Inc. B-8 Drilling Method: SAMPLE DATA Ground Elevation (ft): Drilled By:19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOGGROUNDWATER Sampler TypeNotes: SOIL PROFILE Blows/FootWater LevelUSCS SymbolDepth (ft)Sample Number& IntervalNot Determined Hollow-stem Auger Test DataFigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ SOIL BORING LOG12Log of Boring B-8 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110100 Grain Size in Millimeters GravelCobbles 3 U.S. SIEVE OPENING IN INCHES 1.5 % Fine Gravel 1/2 ClassificationDepth 3/8 Cu 50 To be well graded: 1 < Cc < 3 and Cu > 4 for GW or Cu > 6 for SW LL PL % Medium Sand 16 Point Grain Size Test Data 6 103 Depth U.S. SIEVE NUMBERS 8 %Coarse Gravel 2 143/4 2006 Cc = D30 2/(D60* D10) Cu = D60/D10 1 medium % Coarse Sand finecoarse 4 40420 D10D30 % Fine Sand PointPercent Finer by Weight140 PI % FinesD60 fine D50 Cc 100 Silt or ClaySand coarse 6030 HYDROMETER D90 8.0 13.0 28.1 21.2 11.5 14.9 10.4 13.6 16.2 13.6 20.7 16.6 17.2 20.2 16.1 19.9 6.3 5.8 6.6 15.1 40.8 32.5 18.1 13.7 3.82 2.408 0.474 1.196 0.718 0.569 0.089 0.214 0.112 SLIGHTLY SILTY, VERY GRAVELLY SAND (SM) SLIGHTLY SILTY, VERY GRAVELLY SAND (SM) SILTY, GRAVELLY SAND (SM) SILTY, GRAVELLY SAND (SM) 5.0 2.5 15.0 20.0 5.0 2.5 15.0 20.0 B-1 B-2 B-2 B-3 B-1 B-2 B-2 B-3 0.73 56.59 6.316 4.295 1.219 2.323 16.845 14.61 12.87 28.648 FigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ GRAIN SIZE W/STATS13 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110100 Grain Size in Millimeters GravelCobbles 3 U.S. SIEVE OPENING IN INCHES 1.5 % Fine Gravel 1/2 ClassificationDepth 3/8 Cu 50 To be well graded: 1 < Cc < 3 and Cu > 4 for GW or Cu > 6 for SW LL PL % Medium Sand 16 Point Grain Size Test Data 6 103 Depth U.S. SIEVE NUMBERS 8 %Coarse Gravel 2 143/4 2006 Cc = D30 2/(D60* D10) Cu = D60/D10 1 medium % Coarse Sand finecoarse 4 40420 D10D30 % Fine Sand PointPercent Finer by Weight140 PI % FinesD60 fine D50 Cc 100 Silt or ClaySand coarse 6030 HYDROMETER D90 27.0 41.6 27.1 24.8 6.8 7.7 10.6 9.4 16.6 19.6 16.6 15.8 10.8 11.2 14.3 11.9 14.3 2.7 11.4 4.8 24.4 17.2 19.9 33.3 1.018 0.163 0.847 1.436 0.102 0.102 0.141 SILTY, VERY GRAVELLY SAND (SM) VERY SILTY, GRAVELLY SAND (SM) SILTY, VERY GRAVELLY SAND (SM) SILTY, VERY GRAVELLY SAND (SM) 5.0 20.0 15.0 2.5 5.0 20.0 15.0 2.5 B-5 B-6 B-7 B-8 B-5 B-6 B-7 B-8 4.065 0.381 2.35 3.983 28.261 10.454 20.335 16.271 FigureThe Commons Pacific Highway South Federal Way, WA19-0193 6/11/19 C:\USERS\KURTP\DESKTOP\GINT LOGS\THE COMMONS.GPJ GRAIN SIZE W/STATS14 2545 W Falls Avenue Kennewick, WA 99336 509.783.7450 www.nwag.com lab@nwag.com Sample ID pH Organic Matter Cation Exchange Capacity B-3 @ 5.0’ 7.0 0.83% 5.8 meq/100g B-4 @ 2.5’ 7.1 1.91% 6.3 meq/100g B-4 @ 5.0’ 6.5 2.10% 6.9 meq/100g B-7 @ 5.0’ 5.9 5.06% 13.0 meq/100g Method SM 4500-H+ B ASTM D2974 EPA 9081 GeoTest Services Inc. 741 Marine Drive Bellingham, WA 98225 Report: 48139-1-1 Date: May 22, 2019 Project No: 19-0193 Project Name: The Commons 1 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) REPORT LIMITATIONS AND GUIDELINES FOR ITS USE1 Subsurface issues may cause construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help: Geotechnical Services are Performed for Specific Purposes, Persons, and Projects At GeoTest our geotechnical engineers and geologists structure their services to meet specific needs of our clients. A geotechnical engineering study conducted for a civil engineer may not fulfill the needs of an owner, a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineer who prepared it. And no one – not even you – should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report is Based on a Unique Set of Project-Specific Factors GeoTest’s geotechnical engineers consider a number of unique, project-specific factors when establishing the scope of a study. Typical factors include: the clients goals, objectives, and risk management preferences; the general nature of the structure involved its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless GeoTest, who conducted the study specifically states otherwise, do not rely on a geotechnical engineering report that was: · not prepared for you, · not prepared for your project, · not prepared for the specific site explored, or · completed before important project changes were made. 2 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: · the function of the proposed structure, as when it’s changed, for example, from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, · elevation, configuration, location, orientation, or weight of the proposed construction, · alterations in drainage designs; or · composition of the design team; the passage of time; man-made alterations and construction whether on or adjacent to the site; or by natural alterations and events, such as floods, earthquakes or groundwater fluctuations; or project ownership. Always inform GeoTest’s geotechnical engineer of project changes – even minor ones – and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. Do not rely on the findings and conclusions of this report, whose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctuations. Always contact GeoTest before applying the report to determine if it is still relevant. A minor amount of additional testing or analysis will help determine if the report remains applicable. Most Geotechnical and Geologic Findings are Professional Opinions Our site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoTest’s engineers and geologists review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ – sometimes significantly – from those indicated in your report. Retaining GeoTest who developed this report to provide construction observation is the most effective method of managing the risks associated with anticipated or unanticipated conditions. 3 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) A Report’s Recommendations are Not Final Do not over-rely on the construction recommendations included in this report. Those recommendations are not final, because geotechnical engineers or geologists develop them principally from judgment and opinion. GeoTest’s geotechnical engineers or geologists can finalize their recommendations only by observing actual subsurface conditions revealed during construction. GeoTest cannot assume responsibility or liability for the report’s recommendations if our firm does not perform the construction observation. A Geotechnical Engineering or Geologic Report may be Subject to Misinterpretation Misinterpretation of this report by other design team members can result in costly problems. Lower that risk by having GeoTest confer with appropriate members of the design team after submitting the report. Also, we suggest retaining GeoTest to review pertinent elements of the design teams plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having GeoTest participate in pre-bid and preconstruction conferences, and by providing construction observation. Do not Redraw the Exploration Logs Our geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors of omissions, the logs included in this report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable; but recognizes that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, consider advising the contractors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited; encourage them to confer with the GeoTest and/or to conduct additional study to obtain the specific types of information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available, while requiring them to at least share some of the financial responsibilities 4 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) stemming from unanticipated conditions. In addition, it is recommended that a contingency for unanticipated conditions be included in your project budget and schedule. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering or geology is far less exact than other engineering disciplines. This lack of understanding can create unrealistic expectations that can lead to disappointments, claims, and disputes. To help reduce risk, GeoTest includes an explanatory limitations section in our reports. Read these provisions closely. Ask questions and we encourage our clients or their representative to contact our office if you are unclear as to how these provisions apply to your project. Environmental Concerns Are Not Covered in this Geotechnical or Geologic Report The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated containments, etc. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk management guidance. Do not rely on environmental report prepared for some one else. Obtain Professional Assistance to Deal with Biological Pollutants Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts biological pollutants from growing on indoor surfaces. Biological pollutants includes but is not limited to molds, fungi, spores, bacteria and viruses. To be effective, all such strategies should be devised for the express purpose of prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional biological pollutant prevention consultant. Because just a small amount of water or moisture can lead to the development of severe biological infestations, a number of prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of this study, the geotechnical engineer or geologist in charge of this project is not a biological pollutant prevention consultant; none of the services preformed in connection with this geotechnical engineering or geological study were designed or conducted for the purpose of preventing biological infestations.