# PORT GAMBLE S’KLALLAM TRIBE ADMINISTRATIVE CAMPUS MASTER PLAN > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/tribal%3Aport_gamble_sklallam%3A4baf4d64880672e7 ## Record - **Collection:** Tribal code - **Document type:** Tribal code ## Text Chapter 06 Appendices PORT GAMBLE S’KLALLAM TRIBE ADMINISTRATIVE CAMPUS MASTER PLAN CHAPTER 6: APPENDICES A Utilities Report PORT GAMBLE S’KLALLAM TRIBE ADMINISTRATIVE CAMPUS MASTER PLAN CHAPTER 6: APPENDICES PGST UTILITIES MEMO A technical memorandum for the utilities within the administrative campus. October 11, 2024 Prepared for: The Port Gamble S'Klallam Tribe Prepared by: Zach Barbarick EI, Jonathan Sweet PE Ryan Whittle PE Project Number: 2042681800 PGST Utilities memo Revision Description Author Date 1.0 Existing utility conditions Zach Barbarick 03/28/2024 2.0 Preliminary Design Jonathan Sweet 07/08/2024 Quality Check Project Number: 2042681800 Date Independent Review Date PGST Utilities memo The conclusions in this memo are Stantec’s professional opinion, as of the time of the memo, and concerning the scope described in the memo. The opinions are based on conditions and information existing at the time the scope of work was conducted and do not take into account any subsequent changes. This memo relates solely to the specific project for which Stantec was retained and the stated purpose for which the memo was prepared. It is not to be used or relied on for any variation or extension of the project, or for any other project or purpose, and any unauthorized use or reliance is at the recipient’s own risk. Stantec has assumed that all the information received from The Port Gamble S'Klallam Tribe (the “Client”) and third parties in the preparation of this memo to be correct. While Stantec has exercised a customary level of judgment or due diligence in the use of such information, Stantec assumes no responsibility for the consequences of any error or omission contained therein. This memo is intended solely for use by the Client in accordance with Stantec’s contract with the Client. While it may be provided by the Client to applicable authorities having jurisdiction and to other third parties in connection with the project, Stantec disclaims any legal duty based upon warranty, reliance or any other theory to any third party, and will not be liable to such third party for any damages or losses of any kind that may result. Prepared by: Signature Printed Name Reviewed by: Signature Printed Name Approved by: Signature Printed Name Project Number: 2042681800 PGST Utilities memo Table of Contents 1 EXECUTIVE SUMMARY ..................................................................................................5 2 GENERAL .........................................................................................................................6 Existing Condition .......................................................................................................................................... 6 Demands 6 Utility Corridor ................................................................................................................................................ 6 3 WATER SYSTEM..............................................................................................................7 Existing Condition .......................................................................................................................................... 7 3.1.1 Supply............................................................................................................................................. 7 3.1.2 Distribution Pressure Zones ........................................................................................................... 7 Demand 8 Recommendations ......................................................................................................................................... 8 3.1.3 Water System Plan......................................................................................................................... 8 3.1.4 Transmission Main ......................................................................................................................... 8 3.1.5 Pressure zones .............................................................................................................................. 8 4 SANITARY SEWER ....................................................................................................... 10 Existing Conditions ........................................................................................................................................ 9 Demand 5 Recommendations ....................................................................................................................................... 11 4.1.1 Septic Tanks ................................................................................................................................. 11 4.1.2 Grease Traps ............................................................................................................................... 11 4.1.3 Sewer System Plan ...................................................................................................................... 11 5 STORMWATER MANAGEMENT .................................................................................. 12 Existing Conditions ...................................................................................................................................... 10 5.1.1 Runoff Capture ............................................................................................................................. 12 5.1.2 Conveyance ................................................................................................................................. 12 5.1.3 Treatment ..................................................................................................................................... 12 Demand 1 Recommendations ......................................................................................................................................... 1 5.1.4 Subarea 1 – The Bluff .................................................................................................................... 1 5.1.5 Subarea 2 – Administrative Campus ............................................................................................. 1 5.1.6 Subarea 3 – Baseball field area ..................................................................................................... 1 6 ELECTRIC POWER ..........................................................................................................2 Existing Conditions ........................................................................................................................................ 1 Demands 5 Recommendations ......................................................................................................................................... 2 7 GAS ...................................................................................................................................3 Existing Conditions ........................................................................................................................................ 2 Demand 3 Recommendations ......................................................................................................................................... 3 8 TELECOMMUNICATIONS ...............................................................................................2 Existing Conditions ........................................................................................................................................ 2 Demand 3 Recommendations ......................................................................................................................................... 3 Project Number: 2042681800 PGST Utilities memo 9 IMPACTED UTILITIES......................................................................................................3 LIST OF TABLES Table 1 - Avavilable Service ........................................................................................................................ 3 Project Number: 2042681800 PGST Utilities memo 1 EXECUTIVE SUMMARY In support of the planned redevelopment of the Port Gamble S’Klallam Tribe (Client) administrative campus as presented in the 2024 Administrative Campus Master Plan, this memo summarizes the existing utilities serving Subareas 1-3, discusses utilities that will be impacted by planned redevelopment, and proposes modifications to the various utility systems present on the campus. The existing utility information contained in this memo was collected from GIS data provided by the Client, coordination with their staff, as-built plans, and site observation. Site observation was made both in person and via Google Street View (images dated August 2018). These limited information sources are adequate given the planning nature of this memo, but the location and size of existing utilities should be verified by a licensed Surveyor prior to any future design or construction effort. This memo is intended as a supplement to Campus Development Utility Analysis (Gray & Osborne, Inc, 2018), with an emphasis on the geographic region of the administrative campus and utilities that are impacted by the proposed redevelopment described in the 2024 Master Plan update. Project Number: 2042681800 PGST Utilities memo 2 GENERAL Ownership The Client owns and operates the water, sanitary sewer, and stormwater management infrastructure within the Lower Reservation. Electric and communication infrastructure is owned and maintained by third parties. Utility Corridor Establish a utility corridor whose purpose is to consolidate utility development and operation, present and future, within a narrow zone through the administrative campus. This will disentangle existing utilities in time, which will help future planning efforts, minimize service disruption, and maximize developable area elsewhere on the campus. The utility corridor could be roughly under or alongside the existing campus circulation road that runs from Little Boston Road, south between the police/courts and the proposed Administration Buildings, then west along the southernmost circulation road past the youth center and connecting again to Little Boston Road. Reserve future development within this corridor for utilities and transportation only. See Appendix B for location of recommended utility corridor. Project Number: 2042681800 PGST Utilities memo 3 WATER SYSTEM Existing Condition Supply Two wells actively provide a combined capacity of 288,000 gallons of raw water per day (Gray & Osborne, Inc, 2018). The active wells are located between the Cultural Resources and Housing/Planning buildings, and northwest of the Ball Field’s equipment shed. A third emergency/backup well is located near Gliding Eagle Market; its capacity was not verified and was outside of the scope of this memo. Raw water from the active wells is conveyed to the Treatment Station located on the North end of the Ball Field adjacent to Little Boston Road, then to a concrete water reservoir (Main Tank). A connection from the Kitsap County’s Public Utility District No. 1 (PUD1) water main near Hansville Road provides pressure and volume during emergency conditions (i.e. low pressure events). Distribution Pressure Zones Lower Pressure Zone The portion of potable water distributed to the PGST community from the main tank under gravity head and is designated as the Lower Pressure Zone (LPZ). It provides potable water to portions of the administrative campus, as well as various residential neighborhoods. Buildings within the administrative campus that are served by the LPZ include the Education Center, Elder Center, Childhood Education, Cultural Resources, Community Services, and Human Resources. Analysis by Gray & Osborne, 2018 determines that the LPZ is not adequate for fire service on campus. Upper Pressure Zone A booster station located north of the campus near Little Boston Road provides additional pressure for portions of the PGST community at higher elevations known as the Upper Pressure Zone (UPZ). The UPZ is connected to the LPZ in several other locations via pressure reducing valves (PRV), one of which is located on campus, southeast of the Administration Building and the Youth Center. The UPZ provides potable and fire water to portions of the administrative campus, communities east of and including Cubby Sparks, and the Bud Purser community. Buildings within the administrative campus that are served by the UPZ include the Administration Building, Kitchen, Housing/Planning, Library, Health Clinic, Fisheries Wet Lab, and Youth Center. Analysis by Gray & Osborne, 2018 showed that taking fire flow from the UPZ results in an unacceptable low pressure in uphill neighborhoods (i.e. S’Klallam Hill), except in the case where the UPZ is extended by a booster pump provided near the North Reservoir to serve the East Project Number: 2042681800 PGST Utilities memo Salmonberries development. GIS indicates that such an improvement has been made to the UPZ, in which case volume and pressure of the UPZ are expected to adequately service fire flows at the administrative campus. See Appendix A – Existing Conditions. Demand The new buildings will be sprinklered for fire protection. There will also be increased domestic demand due to the proposed kitchens, locker rooms, and increased restrooms. Recommendations Water System Plan1 Create a water system plan for the Reservation’s water system, as recommended by G&O in 2018. Having a mathematical model of the entire Reservation’s water system allows the Client to better understand system-wide impacts resulting from local changes, for example the proposed addition of a CPZ. A water system plan also enables the Client to discover deficiencies before they manifest, for example fire flows or emergency conditions, and plan for their resolution before they become a problem. Transmission Main It is recommended to convert the existing high pressure main (above 80 psi), currently produced by pumping to serve the higher elevations of the Upper Reservation, into a transmission main. The transmission main will distribute water to pressure zones (discussed in detail below) throughout the Reservation. The transmission main is not suitable for direct domestic or fire service because the pressure is too high. The transmission main would be routed through Little Boston Road to stay clear of future Campus redevelopment. Pressure zones Campus Pressure Zone (CPZ) Create a new pressure zone to serve the Campus only. This new Campus Pressure Zone (CPZ) would be served by the newly created transmission main, with Pressure Reducing Valves (PRV) set to provide ideal domestic and fire pressures to the Campus, with a service main centrally located within the new utility corridor, and domestic and fire services to individual campus buildings branching off of this service 1 A detailed evaluation of this intertie’s effectiveness is recommended during the design phase. Interviews with operations staff revealed that a valve must be manually opened. If this intertie is intended for emergencies, a more automated solution is recommended. This solution should detect the hydrologic conditions of the main in real time. See Appendix ? for intertie as-built. Project Number: 2042681800 PGST Utilities memo main. Conveyance for the CPZ may utilize existing piping currently serving the UPZ and LPZ onsite where appropriate. Lower Pressure Zone (LPZ) Maintain the pressure zone that currently serves the residential portions of the Lower Reservation south of the Administrative Campus by connecting to the transmission main via PRVs with set pressure to provide adequate domestic and residential fire service. The campus will no longer be served by the LPZ. Upper Pressure Zone (UPZ) Maintain the pressure zone that currently serves the higher elevation residential neighborhoods. The campus will no longer be served by the UPZ. See Appendix B for proposed water layout. Project Number: 2042681800 PGST Utilities memo 4 SANITARY SEWER Existing Condition Service Each building on the administrative campus is served by sanitary sewer except for the Longhouse and the Gym because they do not have bathrooms. Each building served with sanitary sewer has its own septic tank. The peak sewer flow rate has been calculated at 3,260 gallons per day for the administrative campus (Gray & Osborne, Inc, 2018). Conveyance Buildings drain via gravity pipe from the buildings, through septic tanks, then by gravity sewer south along Little Boston Road to a pump station, then by force main to the Wastewater Treatment Facility at the Upper Reservation. Treatment A wastewater treatment plant on the Upper Reservation provides sewage treatment for the majority of the Reservation and has been assessed in the General Sewer/Wastewater Facility Plan (Gray & Osborne 2013) to be sufficient in capacity to receive and treat all of the sewage produced on the Reservation through the 20-yr planning period. As a result, we do not see a further need to analysis the treatment system. See Appendix A – Existing Conditions. Demand In addition to maintaining sewer service to existing buildings to remain, the proposed Administration Buildings will also require sewer service. Recommendations Septic Tanks Consolidate the existing septic tank effluent pumping (STEP) infrastructure by removing septic tanks at individual campus buildings and replace with two tanks serving the north and south portions of campus, with additional capacity in each tank for future growth. This would allow for reduced maintenance and reduced cost of future development on the campus. If any building sewers are pumped, this would also allow for consolidation of pumping infrastructure. The north system would serve the Health Clinic, Childhood Education, Housing/Planning, Library, Longhouse, Elder Center and Education Center. The Project Number: 2042681800 PGST Utilities memo south system would serve the new Administration Buildings, Police/Courts, Children and Family Services, Cultural Resources Center, Fisheries Lab, and Youth Center. Grease Traps Buildings with kitchens will require a dedicated grease trap. The south system will also have a conveyance main that utilizes the new utility corridor. In the long-term, connections from the north zone could migrate to the south to further leverage the utility corridor. Sewer System Plan Create a system plan for the Reservation’s sanitary sewer system. Having a mathematical model of the entire Reservation’s sewer system allows the Client to better understand system-wide impacts resulting from local changes, for example, to verify capacity of conveyance within the campus or downstream lift station serving much of the Reservation. A sewer system plan also the Client to plan for future demand. See Appendix B for proposed sewer layout. Project Number: 2042681800 PGST Utilities memo 5 STORMWATER MANAGEMENT Existing Condition Runoff Capture Stormwater from the Longhouse roof drains west directly onto a french drain. The four buildings adjacent to the Longhouse (Library, Housing/Planning, Elder Center, and Education Center) have drip chains to french drains. All other buildings on campus have conventional roof drains that are conveyed with underground piping. Parking lots and site roadways mostly drain to catch basins. Conveyance Conveyance from the campus ultimately discharges into one of two natural drainage channels that flow from east to west into Port Gamble Bay. There is a natural channel north of the campus opposite Little Boston Road, and another is immediately south of the campus. Roof drains from the Kitchen, Gym and Administration Building daylight to a vegetated swale that is east of and parallel to Little Boston Road. Roof drains from the Food Bank/Special Projects Building, Human Resources Building, and Community Services Building daylight to a vegetated swale that is in the southeast of the campus. Roof drains from the Fisheries Wet Lab flows to a dispersion trench located adjacent to the southern natural channel. GIS data provided by the Client did not include stormwater conveyance information. Treatment Runoff from parking and site roadways south of the Administration Building are treated in bioretention ponds located in parking islands south of the Administration Building. Another larger bioretention pond located in the southwest of the site treats runoff from the Administration Building roof drains and asphalt surfaces west and south of the Administration Building. See Appendix A – Existing Conditions. Project Number: 2042681800 PGST Utilities memo Demand The new buildings are likely to increase impervious area on the campus, requiring additional stormwater treatment capacity. Recommendations An Urban Stormwater Assessment is being developed concurrently and is expected to be adopted as early as October 2024. This document will provide various approved measure to promote protection of the Bluff. Any stormwater improvements within Subareas 1, 2, or 3 should be in alignment with this Urban Stormwater Assessment. Subarea 1 – The Bluff Improvements along Little Boston Road should be intercepted, possibly via bioswale, to prevent erosive runoff over the bluff. Subarea 2 – Administrative Campus Create a new stormwater facility in front of the proposed Administration Buildings along the frontage of Little Boston Rd to serve new stormwater demands. Subarea 3 – Baseball field area The Master Plan proposes that the existing ball field be converted into a gravel overflow parking lot. Runoff generated from the new gravel lot should generally slope west and intercepted either by area drains or a conveyance ditch, where it is to be convey to the existing ditch along Little Boston Road ditch, and eventually on to an existing stormwater pond. Expand the existing pond as necessary to account for the increase in runoff. Project Number: 2042681800 A-1 PGST Utilities memo 6 ELECTRIC POWER + TELECOMMUNICATIONS Existing Condition There is a mix of overhead and underground power and telecommunications lines within the administrative campus. Campus as-built drawings provided location of lines on parts of the site, supplemented by poles, junction boxes, meters and building service lines observed using Google Street View. See Appendix A – Existing Conditions. Demands The new Administration Buildings will need electrical power and telecommunications service, but are anticipated to draw a similar amount of power as the previous Administration Buildings. The Client has expressed interest in undergrounding of overhead lines on Little Boston Road to achieve a more scenic view of Port Gamble Bay from the proposed Administration Buildings. Recommendations Provide an electrical and telecommunications backbone through the south portion of the new utility corridor to serve the new Administration Buildings. Other buildings whose electrical or telecommunications service is disrupted by development of the Administration Buildings can also take service from these new backbones. Future development should include an extension of this backbone through the north portion of the utility corridor. Undergrounding of overhead lines in Little Boston Road would incur a significant cost. It is recommended that this improvement not be performed at this time, but be reconsidered by the Client after the new Administration buildings have been occupied for some. See Appendix B for proposed electrical and telecommunications layout. Project Number: 2042681800 A-2 PGST Utilities memo 7 GAS Existing Condition No indicators of piped natural gas were observed using Google Street View and no natural gas data was available by GIS. A 50-lb propane tank was observed west of the Health Clinic and maps from Client staff indicate that other propane tanks exist on the Campus, further suggesting that no piped natural gas is available. Demand The new buildings include multiple kitchens and will therefore need gas supply. Recommendations Provide propane tank service to proposed kitchens, consistent with current gas services on the campus. Future development of gas infrastructure should utilize the new utility corridor. Project Number: 2042681800 A-3 EXISTING LEGEND CAMPUS BOUNDARY WATER METER EXISTING BUILDING POST INDICATOR VALVE UNDERGROUND ELECTRICAL WATER VALVE OVERHEAD ELECTRICAL PRESSURE REDUCING VAULT TELECOMMUNICATIONS SEWER CLEANOUT SEWER FORCEMAIN TELECOM BOX GRAVITY SEWER FIRE DEPARTMENT CONNECTION STORM POND STREET LIGHT UPPER ZONE WATER LINE SANITARY SEWER MANHOLE LOWER ZONE WATER LINE SEPTIC TANK WELL SUPPLY LINE PAD MOUNTED TRANSFORMER WELL STORM POND FIRE HYDRANT WORKING DRAFT - For Discussio 2024.7.31 Stantec Consulting Services Inc. 1687 114th Avenue SE, Suite 100 Bellevue, Washington 98004 Tel:425-289-7333 www.stantec.com EXISTING LEGEND CAMPUS BOUNDARY EXISTING BUILDING UPPER ZONE WATER LINE LOWER ZONE WATER LINE WELL SUPPLY LINE WELL FIRE HYDRANT WATER METER POST INDICATOR VALVE WATER VALVE PRESSURE REDUCING VAULT FIRE DEPARTMENT CONNECTION SERVED BY UPPER ZONE WATER LINE SERVED BY LOWER ZONE WATER LINE WORKING DRAFT - For Discussio 2024.7.31 Stantec Consulting Services Inc. 1687 114th Avenue SE, Suite 100 Bellevue, Washington 98004 Tel:425-289-7333 www.stantec.com EXISTING LEGEND CAMPUS BOUNDARY EXISTING BUILDING SEWER FORCEMAIN GRAVITY SEWER SEWER CLEANOUT SANITARY SEWER MANHOLE SEPTIC TANK STORM POND WORKING DRAFT - For Discussio 2024.7.31 Stantec Consulting Services Inc. 1687 114th Avenue SE, Suite 100 Bellevue, Washington 98004 Tel:425-289-7333 www.stantec.com EXISTING LEGEND CAMPUS BOUNDARY EXISTING BUILDING UNDERGROUND ELECTRICAL OVERHEAD ELECTRICAL TELECOMMUNICATIONS TELECOM BOX STREET LIGHT PAD MOUNTED TRANSFORMER WORKING DRAFT - For Discussio 2024.7.31 Stantec Consulting Services Inc. 1687 114th Avenue SE, Suite 100 Bellevue, Washington 98004 Tel:425-289-7333 www.stantec.com W W W W W W PRV TRANSMISSION - CONTINUE EXISTING UPZ THROUGH LITTLE BOSTON ROAD. -TRANSMISSION SERVES LPZ AND CPZ (SHOWN) AND UPZ (NOT SHOWN). L TE E E BOOSTER PUMP E W W TEEL W W W TEEL W W E W W W E W TEEL W W E W W TEEL CAMPUS PRESSURE ZONE (CPZ) - REPURPOSE EXISTING UPZ AND LPZ PIPING ON CAMPUS. - CONNECT TO UPZ IN TWO PLACES VIA PRV. - SET PRV PRESSURES TO ADEQUATELY SERVE CAMPUS' DOMESTIC AND FIRE SERVICE DEMANDS WITHIN A SINGLE PRESSURE ZONE. W W W W W W W W W W E W W W W W SS W E W W SS TEL W E W W W W W W W TEL W W E SS SS E TEL W W E W W E SS W W PROPOSED LEGEND E SS EXISTING LEGEND SS TEL W W CAMPUS BOUNDARY E EXISTING BUILDING W W XE ELECTRICAL LINE XT XT TELECOMMUNICATION LINE XFM XFM SEWER FORCEMAIN XSS XSS GRAVITY SEWER E E TEL E SS XE TEL W W SS W W W W W E SS SS STORM POND W W W E W W SS E W SS SS W W WATER LINE - ADMIN PRESSURE ZONE W W TEEL FIRE HYDRANT WM TEEL SS E WATER LINE - WELL SUPPLY WELL WATER METER POST INDICATOR VALVE WATER VALVE L TEE SS PRV E TELE WATER LINE - LOW PRESSURE ZONE SS W W W XW E W PRV XW SS W W WATER LINE - HIGH PRESSURE ZONE SS W E E XW SS W W SS PRV PRESSURE REDUCING VAULT SCO SEWER CLEANOUT TELE TELECOM BOX PRV W FIRE DEPARTMENT CONNECTION STREET LIGHT SANITARY SEWER MANHOLE SEPTIC TANK W LOWER PRESSURE ZONE (LPZ) -CONNECT TO UPZ VIA PRV TO MAINTAIN SERVICE TO LITTLE BOSTON COMMUNITY. - LPZ NO LONGER SERVES CAMPUS. TEEL SS W W SS W TEEL SS W XW TFMR PAD MOUNTED TRANSFORMER UTILITY CORRIDOR WORKING DRAFT - For Discuss 2024.9.26 Stantec Consulting Services Inc. 1687 114th Avenue SE, Suite 100 Bellevue, Washington 98004 Tel:425-289-7333 www.stantec.com E L TE E PRV W W W W W W E W W TEEL W W W TEEL W W E W TEEL W W E W W TEEL W W E W W W W W W W W W W W E W W W W W SS W E W W SS TEL W E W W W W W W W TEL W W E SS SS E TEL W W E W W E SS W W CONSOLIDATED STEP SYSTEM - NORTH ZONE - REMOVE SEPTIC TANKS AT INDIVIDUAL BUILDINGS. - INSTALL SINGLE SEPTIC TANK OVER EXISTING LINE. - PROVIDE ADDITIONAL CAPACITY FOR FUTURE GROWTH. PROPOSED LEGEND E SS EXISTING LEGEND SS TEL W W CAMPUS BOUNDARY E EXISTING BUILDING W W XE ELECTRICAL LINE XT XT TELECOMMUNICATION LINE XFM XFM SEWER FORCEMAIN XSS XSS GRAVITY SEWER E E TEL E SS XE TEL W W W E SS W W W W SS SS SS W W WATER LINE - LOW PRESSURE ZONE WATER LINE - ADMIN PRESSURE ZONE W W W W W WATER LINE - WELL SUPPLY FIRE HYDRANT TEEL WM TEEL SS E W WELL WATER METER POST INDICATOR VALVE WATER VALVE L TEE SS PRV E TELE XW SS W W W XW E W PRV WATER LINE - HIGH PRESSURE ZONE SS W W XW SS E W E XW SS W W E SS W W STORMWATER MANAGEMENT - INSTALL BIORETENTION PONDS ALONG LITTLE BOSTON ROAD FRONTAGE. TEEL SS E W SS W TEEL SS STORM POND W W SS PRV PRESSURE REDUCING VAULT SCO SEWER CLEANOUT TELE TELECOM BOX PRV SS FIRE DEPARTMENT CONNECTION W STREET LIGHT SANITARY SEWER MANHOLE W SEPTIC TANK CONSOLIDATED STEP SYSTEM - SOUTH ZONE - REMOVE SEPTIC TANKS AT INDIVIDUAL BUILDINGS. - LAY SEWER MAIN WITHIN UTILITY CORRIDOR. - INSTALL SINGLE SEPTIC TANK. - PROVIDE ADDITIONAL CAPACITY FOR FUTURE GROWTH. TFMR PAD MOUNTED TRANSFORMER UTILITY CORRIDOR WORKING DRAFT - For Discuss 2024.9.26 Stantec Consulting Services Inc. 1687 114th Avenue SE, Suite 100 Bellevue, Washington 98004 Tel:425-289-7333 www.stantec.com E L TE E PRV W W W W W W E W W TEEL W W W TEEL W W E W TEEL W W E W W TEEL W W E W W W W W W W W W W W E W W W W W SS W E W W SS TEL W E W W W W W W W TEL W W E SS SS E TEL W W E W W E SS W W SS E EXISTING LEGEND SS TEL W W PROPOSED LEGEND E CAMPUS BOUNDARY W W EXISTING BUILDING XE ELECTRICAL LINE XT XT TELECOMMUNICATION LINE XFM XFM SEWER FORCEMAIN XSS XSS GRAVITY SEWER E SS XE TEL W W W E SS W E E TEL SS SS W W W W STORM POND W W E TEEL W W XW WATER LINE - LOW PRESSURE ZONE WATER LINE - ADMIN PRESSURE ZONE W W SS WATER LINE - WELL SUPPLY WELL TEEL FIRE HYDRANT WM WATER METER POST INDICATOR VALVE L TEE SS SS SS W XW SS WATER VALVE E PRV PRESSURE REDUCING VAULT SCO SEWER CLEANOUT TELE TELECOM BOX SS PRV W FIRE DEPARTMENT CONNECTION STREET LIGHT SANITARY SEWER MANHOLE W PRV E TELE TEEL SS W W W WATER LINE - HIGH PRESSURE ZONE E W PRV XW E W W XW SS W W E W SS W W SS W TEEL E SS W SS W SS W SEPTIC TANK TFMR PAD MOUNTED TRANSFORMER UTILITY CORRIDOR WORKING DRAFT - For Discussio 2024.9.26 Stantec Consulting Services Inc. 1687 114th Avenue SE, Suite 100 Bellevue, Washington 98004 Tel:425-289-7333 www.stantec.com B Soil and Geotechnical Report PORT GAMBLE S’KLALLAM TRIBE ADMINISTRATIVE CAMPUS MASTER PLAN CHAPTER 6: APPENDICES Preliminary Geotechnical Study Port Gamble S’Klallam Tribe – Administrative Campus Master Plan Kingston, Washington for Port Gamble S’Klallam Tribe May 15, 2024 1101 South Fawcett Avenue, Suite 200 Tacoma, Washington 98402 253.383.4940 Preliminary Geotechnical Study Port Gamble S’Klallam Tribe – Administrative Campus Master Plan Kingston, Washington File No. 0181-010-00 May 15, 2024 Prepared for: Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. 720 Third Avenue, Suite 1500 Seattle, Washington 98104 Attention: Ryan Whittle Prepared by: GeoEngineers, Inc. 1101 South Fawcett Avenue, Suite 200 Tacoma, Washington 98402 253.383.4940 Christopher R. Newton, PE Senior Geotechnical Engineer Dennis (D.J.) Thompson, PE Associate Geotechnical Engineer CRN:DJT:atk Disclaimer: Any electronic form, facsimile, or hard copy of the original document (email, text, table, and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Table of Contents 1.0 Introduction and Project Description .............................................................................. 1 2.0 Scope Of Services ......................................................................................................... 1 3.0 Site Conditions ............................................................................................................. 1 3.1 Site Limits and Vicinity.................................................................................................................. 1 3.2 Literature Review .......................................................................................................................... 2 3.2.1 Geologic Mapping .............................................................................................................. 2 3.2.2 Natural Resources Conservation Service Description .................................................... 3 3.2.3 Critical Areas: Geologic Hazards....................................................................................... 4 4.0 Geotechnical Engineering Evaluation ............................................................................. 5 4.1 General .......................................................................................................................................... 5 4.2 Anticipated Soil and Groundwater Conditions ............................................................................ 6 4.3 Seismic Site Class ......................................................................................................................... 6 4.4 Foundation Support ...................................................................................................................... 6 4.5 Retaining Walls and Below-Grade Structures ............................................................................. 7 4.5.1 General............................................................................................................................... 7 4.5.2 Gravity Walls ...................................................................................................................... 8 4.5.3 Shoring and Other Walls ................................................................................................... 8 4.5.4 Preliminary Design ............................................................................................................ 9 4.6 Infiltration Feasibility Assessment ............................................................................................... 9 4.7 Earthwork Considerations ............................................................................................................ 9 4.7.1 Stripping, Clearing, and Subgrade Preparation ............................................................... 9 4.7.2 Wet Weather Considerations .......................................................................................... 10 4.7.3 Cut and Fill Slopes........................................................................................................... 10 4.7.4 Groundwater Handling .................................................................................................... 10 4.7.5 Fill Materials and Compaction ........................................................................................ 11 5.0 Recommendations for Further Studies ......................................................................... 12 6.0 Limitations.................................................................................................................. 13 7.0 References.................................................................................................................. 13 List of Figures Figure 1. Vicinity Map Figure 2. Site Plan Figure 3. Lidar Map Figure 4. Geologic Map Figure 5. Soil Survey Map Figure 6. Seismic Hazards Map Appendices Appendix A. Report Limitations and Guidelines for Use File No. 0181-010-00 i Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 1 1.0 Introduction and Project Description GeoEngineers, Inc. (GeoEngineers) is pleased to present this preliminary geotechnical study for the Port Gamble S’Klallam Tribe - Administrative Campus Master Plan project. The project site is located at 31912 Little Boston Road NE (Tribal Headquarters) in Kingston, Washington, as shown in the Vicinity Map, Figure 1. Our understanding of the project is based on discussions with you and review of Stantec’s Preliminary Base Maps dated February 2024. We also reviewed the “AS BUILTS, ADMINISTRATION CAMPUS PROJECT: CIVIL DRAWINGS, PORT GAMBLE INDIAN RESERVATION” dated November 7, 2011, prepared by U.S. Department of the Interior, Bureau of Indian Affairs. The overall project consists of developing a master plan for design and construction of a new multi-story Administration Building with below-grade parking and associated improvements. The proposed development areas are shown as Subareas 1 through 3 in the Site Plan, Figure 2. The new Administration Building is planned to be constructed in Subarea 1. The master planning process will include a review and analysis of the existing site, public engagement to gather input and feedback to proposed master plan concepts, cost estimates on the preferred and final master plans, and associated phasing and funding strategies. We envision geotechnical-related project elements could include shallow foundations and below-grade building wall design, temporary cut slopes and/or shoring, site grading, new pavement areas, stormwater facilities, and underground utility installation. 2.0 Scope Of Services For our study, we reviewed existing information in the project vicinity to develop an understanding of surface and subsurface conditions in the area. Based on this information, we have prepared this report providing our preliminary opinion on the suitability of the considered Subareas 1 through 3 for future development with regards to geotechnical considerations. The results of our services are intended to support decisions regarding site selection, preliminary project engineering, and future planning. This is a preliminary geotechnical study and is not intended to support final design of site improvements. Additional geotechnical services, including site specific explorations and other engineering design and analysis will be required to support final design for future development. Our services have been provided in accordance with our signed agreement with Stantec dated January 5, 2024. 3.0 Site Conditions 3.1 SITE LIMITS AND VICINITY The Tribal Headquarters Campus (Campus) is occupied by several buildings for administration and education and includes a gymnasium, a library, health clinics, police, court, and other services. A ball field is located near the northeast corner of the Campus. Other site features include landscaping, asphalt pavements, sidewalks, and drainage features such as swales and ditches. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 2 The proposed development areas are shown as Subareas 1 through 3 in the Site Plan, Figure 2. Subarea 1 is in the southwest quadrant of the site and currently includes the existing Administration Building, Natural Resources, gymnasium, kitchen, playground, and parking. Subarea 2 is toward the west of the Campus, and contains a few vacant homes, a tribal arts center, and cemetery. Subarea 3 is in the north-central portion of the Campus on the northwest edge of the ball field, adjacent to a parking lot driveway and Little Boston Road NE. The project site is bordered to the north by Little Boston Road NE and forested area to the east and south. Little Boston Road NE also intersects the site on the western half between the Campus and Subarea 2 A bluff separates the upland Subarea 2 from Port Gamble Bay to the west. Overall, project site topography is generally flat, as shown by the lighter shading in the Lidar Map, Figure 3. Other topographic features at or near the site shown on the Lidar Map include a stream or creek channel ravine to the north of site, a stream or creek channel running through the southeast corner of the site, and a shallow ravine on the southwest corner of the site. 3.2 LITERATURE REVIEW 3.2.1 Geologic Mapping We reviewed the Washington State Department of Natural Resources (DNR) Geologic Information Portal to develop an understanding of site geology using the 1:100,000-scale (100k) surface mapping. The mapping reports glacial soils underlie the site and surrounding areas. Soils present below glacial ice are glacially overridden (glacially consolidated) and typically dense to very dense; these soils are generally characterized by relatively high strength, high allowable bearing pressures, and low compressibility. Examples of glacially consolidated soils include glacial till, advance glacial outwash, and glacial drift. Soils deposited after glacial recession were not glacially overridden and, in general, are relatively less dense. Examples of post-glacial soils include alluvium (river and stream deposits) and recessional glacial outwash. Per the DNR Geologic Information Portal, four geologic units are mapped at or adjacent to the site, and are shown on the Geologic Map, Figure 4: ■ Continental Glacial Outwash, Fraser-age (Qgo): Mapped along the northwest half of the site and contains most of Subareas 2 and 3. Glacial outwash typically consists of a mixture of sand and gravel in a loose to dense condition and can include localized coarser- or finer-grained constituents. Glacial outwash is deposited from meltwater from a receding glacier and commonly overlies glacial till and is not glacially consolidated. Cobbles and boulders can be present within glacial outwash deposits. In this report we refer to material mapped as Continental glacial outwash as “recessional outwash.” ■ Continental Glacial Till, Fraser-age (Qgt): Mapped over the southeast half of the site and contains most of Subarea 1. Glacial till typically consists of a compact mixture of clay, silt, sand, and gravel. Cobbles and boulders can be present within glacial till deposits. It is not uncommon for the upper few feet of glacial till to be weathered and relatively less dense. ■ Continental Glacial Drift, pre-Fraser (Qgp): Mapped at and adjacent to the southwest corner of the site. In the region, pre-Fraser glacial drift typically consists of clay, silt, sand, and gravel that is in a medium dense to very dense condition. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 3 ■ Advance Continental Glacial Outwash, Fraser-age (Qga[t]): Mapped at and adjacent to the southeast corner of the site. Advance glacial outwash (advance outwash) typically consists of sand and gravel that is deposited by meltwater in front of an advancing glacier and then overridden by the glacier and is generally observed to be in a dense to very dense condition. Advance outwash commonly underlies glacial till, and a gradual transition in material gradation may be present upward into the overlying glacial till. Cobbles and boulders can be present within advance outwash deposits. Although not mapped, we anticipate fill placed during previous site development activities (i.e., establishing building pad elevations and grading for parking lot and driveway surfaces) are present at the site. 3.2.1.1 WATER WELL INFORMATION We searched the DNR Geologic Information Portal for water well log reports in the project vicinity. Our search identified two water well log reports located at residential properties about 1 to 1.1 miles north of the project site. Reported subsurface information from the reviewed water well log reports are shown in Table 1 below. TABLE 1. SUBSURFACE INFORMATION FROM WELL LOGS REPORTED DEPTH TO STATIC GROUNDWATER (DATE OF MEASUREMENT) WELL LOCATION WELL DEPTH REPORTED SOIL CONDITIONS 33700 Hood Canal Drive NE 88 feet 57 feet (09/23/92) “Till” and sand and gravel 33787 Hood Canal Drive NE 161 feet 80 feet (03/18/93) “Hard pan,” sand and gravel, clay Soils reported in the reviewed well log reports appear to predominantly consist of glacial deposits. Based on review of Google Earth, the ground surface elevations between the above two properties appear to differ by at least 30 feet, with the 33787-property shown to be lower in elevation. We interpret static groundwater levels reported in the reviewed well log reports to be representative of a deeper regional groundwater table(s) in the project vicinity. Due to the ground surface elevation difference between the above properties and where static groundwater levels are reported in each well, it is possible that they are two different aquifers, with the well installed at the 33787-property targeting a deeper aquifer than the well at the 33700-property. Shallower perched groundwater could also be present in the project vicinity, as described in the “Anticipated Soil and Groundwater Conditions” section of this report. 3.2.2 Natural Resources Conservation Service Description According to the Natural Resources Conservation Service (NRCS) Web Soil Survey, the project site is underlain by the three soil types shown on the Soil Survey Map, Figure 5: Indianola-Kitsap complex, 45 to 70 percent slopes (Map Unit 21), Kitsap silt loam, 2 to 8 percent slopes (Map Unit 28), and Ragnar fine sandy loam, 0 to 6 percent slopes (Map Unit 44). The parent materials of these soils mapped at the site are primarily derived from glacial deposits, which is generally consistent with the above geologic mapping. Additional information pertaining to each mapped soil type is presented in Table 2 below. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 4 TABLE 2. NRCS MAPPED SOIL TYPES EROSION HAZARD RATING SOIL TYPE Indianola-Kitsap complex Severe HYDROLOGIC SOIL GROUP PARENT MATERIAL Indianola: Glacial outwash Indianola: A Kitsap: Lacustrine deposits with volcanic ash in the upper part Kitsap: C COMMENTS Indianola: Described as “somewhat excessively drained” with a “high” capacity of the most limiting layer to transmit water. Kitsap: Described as “moderately well drained” with a “moderately low to moderately high” capacity of the most limiting layer to transmit water. Kitsap silt loam Moderate Lacustrine deposits with volcanic ash in the upper part C Described as “moderately well drained” with a “moderately low to moderately high” capacity of the most limiting layer to transmit water. Ragnar fine sandy loam Slight Glacial outwash with some volcanic ash in the upper part A Described as “well drained” with a “high” capacity of the most limiting layer to transmit water. 3.2.3 Critical Areas: Geologic Hazards Per the Kitsap County Critical Areas Map, most of Subarea 2 along the western bluff side is mapped as a “high” geologically hazardous area, which is categorized for areas of high erosion hazard, and/or landslide hazard, and/or seismic hazard. We also reviewed the Kitsap County Geologically Hazardous Maps related to landslide, erosion, and seismic hazards. A general discussion of these geologic hazards is provided in the sections below and should be reviewed in coordination with other jurisdictional requirements, as project design progresses. 3.2.3.1 LANDSLIDE HAZARDS Per the Kitsap County Landslide Hazards Map, Subarea 2 along the western bluff side is mapped as “moderate” for shallow and deep landslides. The Kitsap County Critical Areas Map defines “moderate” landslide hazards as: ■ Shallow landslides with factors of safety (FS) of 1.5 to 2.5; and/or ■ “Slopes of 15 percent or greater and not classified as I, U, UOS, or URS (intermediate, unstable, unstable old slide, or unstable recent slide as defined by the Coastal Zone Atlas), with soils classified by the U.S. Department of Agriculture NRCS as ‘highly erodible’ or ‘potentially highly erodible; or slopes of 15 percent or greater with springs or groundwater seepage;” and/or; ■ Slopes in all areas equal to or greater than 40 percent (2.5H:1V [horizontal to vertical]). File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 5 According to the DNR Geologic Information Portal, no known landslides or landslide hazard areas are mapped at the site. The Coastal Zone Atlas (presented on the Washington State Department of Ecology’s online Coastal Atlas Map) appears to have eliminated this site area from their mapping. 3.2.3.2 EROSION HAZARDS Per the Kitsap County Erosion Hazards Map, most of Subarea 2 along the western bluff side is mapped as “high” for coastal erosion and the channel migration zone. The Kitsap County Critical Areas Map defines high erosion hazards as: ■ Areas with coastal erosion having a “sediment source rating value of 0.6 to 1.0;” and/or ■ Channel migration zones that are mapped by the Washington State Department of Ecology. The Kitsap County Erosion Hazards Map is generally consistent with the NRCS “severe” erosion hazard rating defined in Table 2 above for the Indianola-Kitsap complex soil unit, which occupies most of Subarea 2. 3.2.3.3 SEISMIC HAZARDS Per the Kitsap County Seismic Hazards Map, no seismic hazards were mapped at the site. According to the DNR Geological Information Portal, the approximate northwest half of the site is mapped as “low” potential for liquefaction, while the approximate southeast half is mapped as “very low.” Further, the nearest mapped fault or other seismogenic feature is more than 1 mile away from the site. For reference, a portion of the seismic hazards map from the DNR Geological Information Portal is reproduced in this report as Figure 6. Based on the reviewed seismic mapping, our understanding of site geology, and anticipated soil conditions, it is our opinion the site has low potential for liquefaction and seismic surface rupture caused by faults and other seismogenic features. Based on our assessment of the potential for soil liquefaction and current site topography, in our opinion this site also has a low potential for lateral spreading. 4.0 Geotechnical Engineering Evaluation 4.1 GENERAL Based on our review of soil and geologic information described above, it is our opinion that the project site is generally suitable for development with regards to geotechnical considerations. However, for development at Subarea 2, we recommend additional critical area studies be conducted and reviewed in regard to infrastructure location since most of this area is identified by Kitsap County as a geologic hazard related to landslides and erosion, as described above. As such, we envision that development at Subarea 2 will be more limited, depending on the results of a geologic critical area study, and likely will be constrained by slope setback buffers and special erosion protection measures. We anticipate potential erosion hazards can be mitigated through engineering controls such as limiting ground disturbance, site grading, planting, and other erosion control measures. We did not identify geotechnical related conditions that would prohibit or significantly constrain overall project design and construction at Subareas 1 and 3. Regardless, the project layout and design will need to incorporate geotechnical considerations as discussed herein. In our opinion, these geotechnical considerations can be managed through appropriate site layout, engineering design, and construction methods. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 6 Preliminary recommendations provided in the sections below are intended to support initial design development, preliminary engineering, cost estimating, and future site planning. These recommendations are not intended to support final project design. Ultimately, we recommend site and project specific geotechnical explorations and analysis be completed as a part of final design of future improvements. Refer to the “Recommendations for Further Studies” section below for discussion and considerations on further geotechnical studies at the site. 4.2 ANTICIPATED SOIL AND GROUNDWATER CONDITIONS Soil conditions at the site are expected to consist of a variable thickness of topsoil and fill underlain by glacial soils. Fill thickness is expected to be greatest in areas of past development or areas where prior grading activities were completed. Topsoil (and forest duff) thicknesses are expected to be greatest in undeveloped forested areas (east and south edges of the site). Based on overall topography and surrounding site grade, we expect that, with the exception of isolated areas, topsoil and fill units will likely be less than a few feet thick at this site. Underlying the topsoil and fill, and as described above, we anticipate the northwest half of site (Subareas 2 and 3) to consist of recessional outwash (Qgo) and the southeast half (Subarea 1) glacial till (Qgt). The recessional outwash will likely consist of medium dense sand and gravel with variable silt and cobble content. The glacial till will likely consist of dense to very dense silty sand with variable gravel and cobble content. Boulders could be present within these glacial soils at the site. We also anticipate that the upper few feet of the glacial soils could be weathered and relatively less dense than underlying intact soils. Based on our understanding of site geology, it is our opinion that the groundwater well data described above is not enough information to infer groundwater depths at the project site. Typically, in upland areas of glacial deposits like this project site, we observe static groundwater deeper than 10 feet, and we envision groundwater to be near the same elevation as the nearby creeks described previously. However, perched groundwater could be encountered at relatively shallow depths across the site. Perched groundwater is typically due to infiltration of surface water that slows or terminates atop underlying less permeable layers of soil (e.g., on top of glacial till deposits). The presence of fill, discontinuities, utilities, and other factors also influence the presence and volume of perched water. 4.3 SEISMIC SITE CLASS We assume improvements will be designed in accordance with the International Building Code (IBC). The 2021 edition of the IBC state structures shall resist the effects of earthquake motions in accordance with American Society of Civil Engineers (ASCE) 7-16 “Minimum Design Loads and Associated Criteria for Buildings and Other Structures.” In accordance with IBC 2021 and ASCE 7-16, we recommend a seismic Site Class D be considered for preliminary, simplified code-based seismic design and analysis. As planning and design progresses, site exploration and testing should be completed to confirm the seismic Site Class. Based on project location, there is a possibility that Site Class C may be appropriate with additional explorations and studies. 4.4 FOUNDATION SUPPORT We envision that structures at this site can be adequately supported on shallow foundations and slab-ongrade floors bearing on existing site soils. Shallow foundations should be established at least 18 inches below the lowest adjacent grade, primarily for frost protection. Interior column footings can be founded a minimum of 12 inches below the bottom of the interior floor slabs. Isolated spread footings should have a minimum width of 24 inches. Continuous spread footings for walls should be at least 18 inches wide. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 7 The presence of fill should be evaluated during any final studies to determine if the fill is suitable for bearing support. Re-compaction and/or removal and replacement of existing fill beneath foundations may be required depending on the condition, amount of organic and/or deleterious material, and overall matrix. Ultimately, foundation bearing support recommendations will depend on soil type, structure loads, foundation elevations, and performance requirements and should be incorporated as part of future geotechnical studies. Topsoil, or soils with a high organic content, will need to be completely removed from below foundations and foundation elements. For preliminary design, we estimate allowable soil bearing resistance of near surface soils (including existing fill and weathered glacial soils) will be on the order of 2,000 to 3,000 pounds per square foot (psf). Higher bearing resistances (3,000 to 6,000 psf) will likely be achievable if foundations are supported directly on undisturbed glacially consolidated soils (i.e., glacial till or advance outwash) at depth. For preliminary planning, increasing these values by about one third may be considered for transient or infrequent extreme loading conditions, such as forces induced by earthquakes. For the bearing conditions and resistances presented above, we anticipate that total and differential foundation settlements can be limited to 1 and ½ inch, respectively, for typical foundation sizes and structures considered. Lateral resistance for building design is typically accommodated from backfill around foundation elements and as friction developed on the bottom of foundations. For published soil types and structural fills anticipated for this site, we suggest a preliminary value of 300 pounds per cubic foot (pcf) as a passive resistance for native materials or structural fill against embedded elements. A coefficient of friction for concrete against anticipated soil materials can be assumed to be around 0.40. These values include a factor of safety of about 1.5. Slab-on-grade floors can likely be adequately supported on existing fill and/or underlying glacial soils. Subgrades for slab-on-grade floors should be compacted to a uniformly firm and unyielding condition. For preliminary design, floor slab loads should be limited to 300 psf. Typical in-place subgrade modulus values on the order of 200 to 300 pounds per cubic inch (pci) are common in glacial deposits. For mat foundations or larger footings, modifications to this value may be required depending on the specific foundation sizes used in design. 4.5 RETAINING WALLS AND BELOW-GRADE STRUCTURES 4.5.1 General We anticipate retaining walls may be required to maintain desired site grades and construct below-grade elements (i.e., basement parking for the new Administration Building). The specific retaining wall type used will depend in part on the application and wall height. For this site, we expect that modular block walls, cast-in-place walls, structural earth walls, soil nail walls, and soldier piles walls are all feasible for use. Additional excavation to develop stable temporary slopes behind retaining walls are commonly required for worker safety and for construction access and should also be considered in overall planning. Sites with limited area for back slope excavations may require a different type of shoring or retaining wall system. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 8 4.5.2 Gravity Walls Cast-in-place walls may be considered in either cut or fill applications and are typically most efficient for intermediate wall heights that are taller than about 5 feet but less than about 10 feet. Typically, foundation base widths of at least half the height of the wall are required for weight and overall stability. This width can be modified by the use of keyways and other foundation geometry options as determined by a structural engineer. Modular block walls typically consist of larger blocks of concrete stacked in a staggered pattern on-top of each other. Examples include “ecology block” walls and other segmental-type block walls (i.e., Redi-Rock, Hilfiker, SierraScape, Ultra Block, etc.). Modular block walls are typically most effective for relatively short walls (less than about 6 feet tall) and can be used in cut and fill grading applications. Modular block walls taller than about 6 feet will require additional considerations including revised base width design and additional batter (angle away from vertical). Structural earth walls are also a type of modular block wall but typically encompass smaller or different blocks (Keystone, Redi-Rock, Mesa, SierraScape, etc.) as facing and include reinforcing grid or “geo-grid” installed behind the facing. Typical vertical spacing between the grid is about 18 to 24 inches. Grid lengths are typically about 70 to 90 percent of the wall height and decrease in overall lengths near the bottom of the wall. Structural earth walls are best suited for use in fill applications and can be designed to retain grade differentials greater than 20 feet. 4.5.3 Shoring and Other Walls Soil nail and soldier pile walls are best suited for cut wall applications and are most often used to retain or reinforce tall slopes or as temporary shoring to construct below-grade building elements. These wall types are commonly used where site constraints do not allow for temporary cut slopes, where the excavation needs to be limited to the building or work area, where movement of nearby structures and/or utilities needs to be limited or applies a surcharge loading. Both wall types are constructed as the excavation is advanced, i.e., “top-down construction”. The use of tiebacks for soldier pile walls, or “nails” for soil nail walls requires horizontal space or soil area behind the wall. The tiebacks or nails may encroach upon rights-of-way or into other structures. This should be a consideration as a part of determining wall type. Soldier pile walls are constructed with vertical steel “H” piles installed in a drilled hole (typically 24 to 36 inches in diameter) and filled with lean-mix or structural concrete. The piles are typically spaced 5 to 10 feet apart. The space between piles is typically spanned with wood lagging, shotcrete, or pre-cast concrete panels. Depending on loading conditions, depth of excavation, and other conditions, tie-back anchors that are connected to the H piles can be installed for additional lateral support. Typically, soldier pile walls taller than about 15 feet are more economical to build with the use of tie- back anchors. Soil nail walls are constructed in lifts by first excavating about 3-to-5-feet and drilling near horizontal 6- to 8-inch diameter holes and installing a steel threadbar nail into the hole. This is done throughout the wall spacing, typically 6 to 10 feet on-center but with each row staggered. Each lift is completed by placing steel reinforcing over the cut face and nails, followed by shotcrete facing, and a bearing face plate and nut at the exposed end of the soil nail. Each 3-to-5-foot lift is finalized before excavating another lift. For some soil types that are more prone to raveling and caving, vertical elements are drilled and installed before excavation to help support the cut face while the soil nail wall is constructed. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 9 4.5.4 Preliminary Design For preliminary planning purposes, we recommend evaluating walls using an active equivalent fluid density of 35 pounds per cubic foot (pcf) (triangular distribution). This assumes that the walls will not be restrained against rotation when backfill is placed and the backfill behind the wall is level. For walls restrained from rotation at the top (i.e., at-rest condition), an equivalent fluid density of 55 pcf (triangular distribution) can be used. These values assume drained conditions behind the wall (i.e., do not account for the effects of hydrostatic conditions). For sloping backfill conditions up to 2H:1V, this value should be increased by about 50 percent. Lateral resistance of retaining walls can be evaluated assuming a passive equivalent fluid density of 300 pcf and an allowable frictional resistance of 0.4 (these values include a factor of safety of about 1.5). These values must be confirmed as part of the final design. Retaining walls should be designed with a drainage system to prevent the buildup of hydrostatic pressures behind the wall. This is typically accomplished with a zone of free draining material placed behind the wall, on the order of 18 inches in thickness, for nearly the full height of the wall. The drainage material should be connected to a perforated rigid piping placed near the bottom of the wall and sloped to drain to an appropriate discharge. “Waffle” drain mats can also be considered provided they are protected from the backfill soil and connect to a drain. 4.6 INFILTRATION FEASIBILITY ASSESSMENT Stormwater infiltration into the recessional outwash soils as mapped on the northwest half of the site is anticipated to be feasible but will depend on depth to groundwater and underlying impeding layers (i.e., glacial till). The glacial till mapped on the southeast half of the site is anticipated to have a relatively high fines content and have a very low infiltration potential. We envision some infiltration is possible into near-surface fill or weathered glacial till deposits; however, overall rates will likely be reduced due to soil layering and shallow depth to intact glacial till. Based on our experience in similar soil conditions, we recommend intact glacial till soils be considered relatively impermeable for preliminary planning. Accordingly, new stormwater systems on the southeast half of the site will likely need to consider some form of detention. 4.7 EARTHWORK CONSIDERATIONS 4.7.1 Stripping, Clearing, and Subgrade Preparation Existing surfaces within proposed development areas should be cleared and stripped of all vegetation and organics prior to site development. In areas containing trees and shrubs, we expect that stripping depths could exceed 6 inches. In existing landscape areas, stripping depths could be around 2 to 4 inches. Subgrades that will support structural elements and pavements should be thoroughly compacted to a uniformly firm and unyielding condition on completion of stripping/excavation and before placing structural fill. If soft or otherwise unsuitable subgrade areas are observed and cannot be compacted to a stable and uniformly firm condition, we recommend that: (1) the unsuitable soils be scarified (e.g., with a ripper or farmer’s disc), aerated and recompacted, if practical; or (2) the unsuitable soils be removed and replaced with compacted structural fill, as needed. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 10 Existing structural improvements (e.g., pavements, hardscaping, and foundations) within proposed development areas should be demolished and removed prior to redeveloping the site. Recycling or incorporating old foundation or pavement elements into fill areas can be considered but must be evaluated on a case-by-case basis. All existing utilities within the new building footprint(s) should be re-routed and/or removed, as needed. If necessary, abandoned utilities may be left in place if properly filled with a controlled density, cementitious fill. 4.7.2 Wet Weather Considerations We expect that the majority of the soils at the site will contain a significant percentage of fines (materials smaller than the No. 200 U.S. sieve) and will be sensitive to small changes in moisture content. If these moisture sensitive soils become wet, they will be very difficult or impossible to work with and be highly susceptible to disturbance. We recommend that earthwork activities at this site be completed during periods of predominantly dry weather. During dry weather, site soils will be less susceptible to disturbance, provide better support for construction equipment, and be more likely to meet the required compaction criteria. If earthwork must occur during wet weather, we recommend that contingencies be included to account for additional management of materials and over-excavation and replacement of saturated and disturbed soils. Additionally, if wet weather construction is proposed or required, we recommend considering for a “net cut” site rather than a balanced cut and fill site, to reduce the amount of overall soil management and less handling of materials exposed to wet conditions. 4.7.3 Cut and Fill Slopes To maintain site grading and provide safe working conditions, we recommend planning for temporary excavations and cut slopes to be inclined no steeper than about 1.5H:1V. Flatter cut slopes will be necessary where seepage occurs or if surface surcharge loads are anticipated. If 1.5H:1V temporary slopes are not feasible, temporary shoring, such as a soldier pile or soil nail wall, may be necessary. We envision this may be the case when excavating the basement for the new Administration Building due to proximity of surrounding buildings and other improvements. Depending on the depth of excavation, and site layout, cut slopes in combination with shoring elements, or use of ecology block wall systems may also be appropriate for temporary shoring. Where dense glacial till deposits are present, there could be an option to construct steeper 1H:1V temporary slopes provided that these conditions are verified as a final geotechnical study and during construction. We recommend permanent slopes with maximum inclination of about 2H:1V be considered for preliminary planning purposes. Where 2H:1V permanent slopes are not feasible, protective facings and/or retaining structures should be considered. Where access for landscape maintenance is desired, we recommend a maximum inclination of 3H:1V. Flatter cut slopes or additional drainage measures could be necessary where seepage occurs or if surface surcharge loads are anticipated. 4.7.4 Groundwater Handling The level of effort required for groundwater management during construction will depend to a great extent on the time of year during which construction is completed. Groundwater handling needs will typically be lower during the late summer and early fall months. We recommend earthwork be completed in the late summer or early fall months when the groundwater level is typically at its lowest elevation and to take advantage of generally dry prevailing conditions. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 11 Shallow perched groundwater should be expected to be present where more permeable layers are underlain by less permeable layers, specifically in areas where fill or weathered zones are over undisturbed glacial till. Based on our experience in similar glacial soil conditions, slow to moderate groundwater seepage (3 gallons per minute [gpm] or less) is typical in these soil types, particularly during the wet season. We anticipate that this type of shallow perched groundwater, if encountered, can be handled adequately with sumps, pumps, and/or diversion ditches, as necessary. As described above, static groundwater at the site is anticipated to be deeper than 10 feet below existing site grades. For preliminary planning purposes, anticipate that excavations extending 10 feet below existing site grades could require dewatering systems, groundwater cut off elements, wells, or additional sumps in order to maintain dry conditions. Ultimately, completing subsurface explorations will provide better information on groundwater levels at the site. 4.7.5 Fill Materials and Compaction 4.7.5.1 REUSE OF ON-SITE SOILS AS STRUCTURAL FILL We anticipate the majority of the site footprint is underlain by glacial till (Qgt) deposits, which typically consist of a mixture of silt, sand, gravel and cobbles. Glacial till soils can be considered for reuse as structural fill provided, they can be adequately moisture conditioned, placed, and compacted, as recommended and do not contain organic or other deleterious material. Site soils will likely be very difficult or impossible to properly compact when wet and we recommend they be avoided for reuse if earthwork is planned during wet weather months. In addition, it is possible that existing soils will be generated at moisture contents above what is optimum for compaction. In this case, the soils would need to be moisture conditioned prior to re-use. Space for drying out material during dryer weather or covering on-site materials generated during wet weather should be considered and incorporated into schedules and budgets. During wetter or even slightly colder times of year, accommodations to cover stockpiled material generated on site that will be used as structural fill should be planned. If earthwork occurs during a typical wet season, or if the soils are persistently wet and cannot be dried back due to prevailing wet weather conditions, we recommend project budgets include contingencies for using imported materials as structural fill. 4.7.5.2 IMPORT STRUCTURAL FILL Imported structural fill should be free of debris, organic contaminants, and rock fragments larger than 6 inches. For most applications, we recommend that structural fill consist of material similar to “Select Borrow” or “Gravel Borrow” as described in Section 9-03.14 of the Washington State Department of Transportation (WSDOT) Standard Specifications. If imported fill is needed during wet weather conditions, we recommend using fill consisting of well-graded sand and gravel or crushed rock with a maximum particle size not exceeding 6 inches and less than 5 percent fines by weight based on the minus ¾-inch fraction. In our opinion, material conforming to WSDOT Standard Specifications Sections 9-03.9 (Aggregates for Ballast and Crushed Surfacing), 9-03.10 (Aggregate for Gravel Base) and 9-03.14 (Borrow) are suitable for use as imported fill material during wet weather, with the exception that the fines content should be limited to 5 percent or less based on the minus ¾-inch fraction. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 4.7.5.3 Page 12 TOPSOIL AND STRIPPINGS Topsoil and strippings (e.g., sod and forest duff) may be placed on site provided they are placed in non-structural areas that can tolerate some long-term total and differential settlements. Settlements of organic-rich soils are highly variable and difficult to quantify. Settlement could continue for several years after construction is completed as the organics break down and decompose. Alternatively, topsoil strippings can be hauled off site. 4.7.5.4 FILL COMPACTION In general, we recommend that all structural fills be compacted to at least 95 percent of the maximum dry density (MDD) based on ASTM D-1557. Provisions for less compaction effort may be considered and reduced to about 92 percent, where deeper fills are placed, such as below pavement areas. Typically, landscape areas require about 85 to 90 percent compaction efforts. 5.0 Recommendations for Further Studies Final site design will need explorations to develop recommendations for foundation support, shoring design (where necessary), seismic design parameters, and stormwater infiltration. Overall, we recommend substantial structures include borings as a final consideration for subsurface explorations and geotechnical design. Borings are typically best suited where refined geotechnical design parameters are necessary. For example, soil strength parameters and seismic Site Class can be determined from correlations to the standard penetration test (SPT) completed during sampling. Borings can also be helpful where limited surface disturbance is necessary, and/or where excavations are planned to be deeper than about 8 to 10 feet. For temporary shoring, borings will be needed for use by shoring designers and should typically extend at least two times the depth of the proposed excavation and be spaced no greater than about 200 feet of wall length. We recommend borings be considered, at or near corners of proposed buildings, and one in the center, as applicable, for the majority of structures proposed for this project. Converting a boring(s) to a groundwater monitoring well(s) is also suggested as it could help characterize fluctuations in groundwater levels for general construction and temporary excavations and help with design for shoring, permanent below-grade walls, and for determining depth limits of infiltration facilities. A piezoelectric pressure transducer can be installed in a monitoring well to record groundwater levels at programmed intervals throughout the seasons. For near-grade smaller structures, test pits in many cases may be appropriate for subsurface exploration and geotechnical design. Test pits are also the primary investigation technique for stormwater infiltration studies. If stormwater infiltration is included in project design, we recommend field testing, such as Pilot Infiltration Tests (PITs), be completed to determine design infiltration rates. PITs should be completed within the footprint of proposed infiltration facilities and at the proposed infiltration depths. PITs are best completed once preliminary site planning and layout has occurred. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 13 6.0 Limitations We have prepared this report for the exclusive use of Stantec and the Port Gamble S’Klallam Tribe for the Administrative Campus Master Plan project in Kingston, Washington. Stantec and the Port Gamble S’Klallam Tribe may distribute copies of this report to authorized agents and regulatory agencies as may be required for the project. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices for geotechnical engineering in this area at the time this report was prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment, and experience. No warranty, express or implied, applies to the services or this report. Any electronic form, facsimile, or hard copy of the original document (email, text, table and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. Please refer to Appendix A titled “Report Limitations and Guidelines for Use” for additional information pertaining to use of this report. 7.0 References American Society of Civil Engineers, 2016, “Minimum Design Loads and Associated Criteria for Buildings and Other Structures, ASCE/SE 7-2016.” International Code Council, 2021, “International Building Code.” Kitsap County Department of Community Development. 2017. “Critical Areas, Kitsap County, Washington.” April 27. Kitsap County Department of Community Development. 2017. “Geologically Hazardous Map, Erosion Hazards, Kitsap County, Washington.” February 23. Kitsap County Department of Community Development. 2017. “Geologically Hazardous Map, Landslide Hazards, Kitsap County, Washington.” February 23. Kitsap County Department of Community Development. 2017. “Geologically Hazardous Map, Seismic Hazards, Kitsap County, Washington.” February 23. United States Department of Agriculture, Natural Resources Conservation Service. 2024. Web Soil Survey. https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx, accessed May 6 and 7, 2024. United States Department of the Interior, Bureau of Indian Affairs. 2011. “AS BUILTS, ADMINISTRATION CAMPUS PROJECT: CIVIL DRAWINGS, PORT GAMBLE INDIAN RESERVATION.” Project Number P10 09000. November 7. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page 14 Washington State Department of Natural Resources. 2024. Washington Geologic Information Portal. https://geologyportal.dnr.wa.gov/, accessed May 6, 2024. Washington State Department of Transportation. 2024. “Standard Specifications for Road, Bridge, and Municipal Construction.” Washington State Department of Transportation and the American Public Works Association, M41-10. File No. 0181-010-00 Figures Legend Site Boundary Subarea Boundary Subarea 3 Little B Source(s): · Aerial from Microsoft Bing Coordinate System: WA State Plane, North Zone, NAD83, US Foot Disclaimer: This figure was created for a specific purpose and project. Any use of this figure for any other project or purpose shall be at the user's sole risk and without liability to GeoEngineers. The locations of features shown may be approximate. GeoEngineers makes no warranty or representation as to the accuracy, completeness, or suitability of the figure, or data contained therein. The file containing this figure is a copy of a master document, the original of which is retained by GeoEngineers and is the official document of record. Subarea 1 N 0 120 Feet Port G Site Plan amble P:\0\0181010\CAD\00\Geotech\018101000_F02_Site Plan.dwg 2 Date Exported:5/13/2024 7:49 AM - by Mike C. Rau d. NE oston R Subarea 2 N N Port Gamble S’Klallam Tribe Administrative Campus Master Plan Kingston, Washington Figure 2 00181-010-00 Date Exported: 05/06/2024 Stream or Creek Ravine Site Stream or Creek Shallow Ravine Lidar Map Notes: 1. This drawing has been reproduced from mapping available online by the Washington State Department of Natural Resources. GeoEngineers cannot warrant or guarantee the accuracy or completeness of information provided or compiled by others. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: 1:100,000-scale Geologic Map, Washington State Department of Natural Resources online Geologic Information Portal Port Gamble S’Klallam Tribe - Administrative Campus Master Plan, Kingston, Washington Figure 3 00181-010-00 Date Exported: 05/06/2024 Map Symbol Geologic Unit Name Qgo Continental glacial outwash, Fraser-age Qgt Continental glacial till, Fraser-age Qgp Continental glacial drift, pre-Fraser Qga(t) Advance continental glacial outwash, Fraser-age Site Qgo Qgt Qga(t) Qgp Geologic Map Notes: 1. This drawing has been reproduced from mapping available online by the Washington State Department of Natural Resources. GeoEngineers cannot warrant or guarantee the accuracy or completeness of information provided or compiled by others. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: 1:100,000-scale Geologic Map, Washington State Department of Natural Resources online Geologic Information Portal Port Gamble S’Klallam Tribe - Administrative Campus Master Plan, Kingston, Washington Figure 4 00181-010-00 Date Exported: 05/06/2024 Map Symbol Soil Unit Name Parent Material Indianola: Glacial outwash 21 Indianola-Kitsap complex Kitsap: Lacustrine deposits with volcanic ash in the upper part Lacustrine deposits 28 Kitsap silt loam with volcanic ash in Site the upper part 44 Ragnar fine sandy loam Glacial outwash with some volcanic ash in the upper part Soil Survey Map Notes: 1. This drawing has been reproduced from the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Web Soil Survey (WSS). GeoEngineers cannot warrant or guarantee the accuracy or completeness of information provided or compiled by others. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: Parent Material, USDA NRCS Web Soil Survey Port Gamble S’Klallam Tribe - Administrative Campus Master Plan, Kingston, Washington Figure 5 00181-010-00 Date Exported: 05/06/2024 Site Seismic Hazards Map Notes: 1. This drawing has been reproduced from seismic hazard mapping available online by the Washington State Department of Natural Resources. GeoEngineers cannot warrant or guarantee the accuracy or completeness of information provided or compiled by others. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: Washington State Department of Natural Resources online Geologic Information Portal Port Gamble S’Klallam Tribe - Administrative Campus Master Plan, Kingston, Washington Figure 6 Appendices Appendix A Report Limitations and Guidelines for Use Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page A-1 Appendix A Report Limitations and Guidelines for Use1 This appendix provides information to help you manage your risks with respect to the use of this report. Read These Provisions Closely It is important to recognize that the geoscience practices (geotechnical engineering, geology and environmental science) rely on professional judgment and opinion to a greater extent than other engineering and natural science disciplines, where more precise and/or readily observable data may exist. To help clients better understand how this difference pertains to our services, GeoEngineers includes the following explanatory “limitations” provisions in its reports. Please confer with GeoEngineers if you need to know more how these “Report Limitations and Guidelines for Use” apply to your project or site. Geotechnical Services Are Performed for Specific Purposes, Persons and Projects This report has been prepared for the exclusive use of Stantec and the Port Gamble S’Klallam Tribe for the Administrative Campus Master Plan project. Stantec and the Port Gamble S’Klallam Tribe may distribute copies of this report to authorized agents and regulatory agencies as may be required for the project. This report is not intended for use by others, and the information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. For example, a geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs of a construction contractor or even another civil engineer or architect that are involved in the same project. Because each geotechnical or geologic study is unique, each geotechnical engineering or geologic report is unique, prepared solely for the specific client and project site. Our report is prepared for the exclusive use of our Client. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with the Client and generally accepted geotechnical practices in this area at the time this report was prepared. This report should not be applied for any purpose or project except the one originally contemplated. A Geotechnical Engineering or Geologic Report Is Based on a Unique Set of Project-specific Factors. This report has been prepared for the Port Gamble S’Klallam Tribe - Administrative Campus Master Plan project located in Kingston, Washington. GeoEngineers considered a number of unique, project-specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, it is important not to rely on this report if it was: 1 Developed based on material provided by GBA, GeoProfessional Business Association; www.geoprofessional.org File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page A-2 ■ Not prepared for you, ■ Not prepared for your project, ■ Not prepared for the specific site explored, or ■ Completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: ■ The function of the proposed structure; ■ Elevation, configuration, location, orientation or weight of the proposed structure; ■ Composition of the design team; or ■ Project ownership. If changes occur after the date of this report, GeoEngineers cannot be responsible for any consequences of such changes in relation to this report unless we have been given the opportunity to review our interpretations and recommendations. Based on that review, we can provide written modifications or confirmation, as appropriate. Environmental Concerns are Not Covered Unless environmental services were specifically included in our scope of services, this report does not provide any environmental findings, conclusions, or recommendations, including but not limited to, the likelihood of encountering underground storage tanks (USTs) or regulated contaminants. Information Provided by Others GeoEngineers has relied upon certain data or information provided or compiled by others in the performance of our services. Although we use sources that we reasonably believe to be trustworthy, GeoEngineers cannot warrant or guarantee the accuracy or completeness of information provided or compiled by others. Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by man-made events such as construction on or adjacent to the site, new information or technology that becomes available subsequent to the report date, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. If more than a few months have passed since issuance of our report or work product, or if any of the described events may have occurred, please contact GeoEngineers before applying this report for its intended purpose so that we may evaluate whether changed conditions affect the continued reliability or applicability of our conclusions and recommendations. File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page A-3 Geotechnical and Geologic Findings are Professional Opinions Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies the specific subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data and then applied its professional judgment to render an informed opinion about subsurface conditions at other locations. Actual subsurface conditions may differ, sometimes significantly, from the opinions presented in this report. Our report, conclusions and interpretations are not a warranty of the actual subsurface conditions. Geotechnical Engineering Report Recommendations are Not Final We have developed the following recommendations based on data gathered from subsurface investigation(s). These investigations sample just a small percentage of a site to create a snapshot of the subsurface conditions elsewhere on the site. Such sampling on its own cannot provide a complete and accurate view of subsurface conditions for the entire site. Therefore, the recommendations included in this report are preliminary and should not be considered final. GeoEngineers’ recommendations can be finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers cannot assume responsibility or liability for the recommendations in this report if we do not perform construction observation. We recommend that you allow sufficient monitoring, testing and consultation during construction by GeoEngineers to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes if the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork activities are completed in accordance with our recommendations. Retaining GeoEngineers for construction observation for this project is the most effective means of managing the risks associated with unanticipated conditions. If another party performs field observation and confirms our expectations, the other party must take full responsibility for both the observations and recommendations. Please note, however, that another party would lack our projectspecific knowledge and resources. A Geotechnical Engineering or Geologic Report Could Be Subject to Misinterpretation Misinterpretation of this report by members of the design team or by contractors can result in costly problems. GeoEngineers can help reduce the risks of misinterpretation by conferring with appropriate members of the design team after submitting the report, reviewing pertinent elements of the design team’s plans and specifications, participating in pre-bid and preconstruction conferences, and providing construction observation. Give Contractors a Complete Report and Guidance To help reduce the risk of problems associated with unanticipated subsurface conditions, GeoEngineers recommends giving contractors the complete geotechnical engineering or geologic report, including these “Report Limitations and Guidelines for Use.” When providing the report, you should preface it with a clearly written letter of transmittal that: File No. 0181-010-00 Port Gamble S’Klallam Tribe c/o Stantec Consulting Services, Inc. | May 15, 2024 Page A-4 ■ Advises contractors that the report was not prepared for purposes of bid development and that its accuracy is limited; and ■ Encourages contractors to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer. Contractors are Responsible for Site Safety on Their Own Construction Projects Our geotechnical recommendations are not intended to direct the contractor’s procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on-site personnel and adjacent properties. Biological Pollutants GeoEngineers’ Scope of Work specifically excludes the investigation, detection, prevention or assessment of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations, recommendations, findings or conclusions regarding the detecting, assessing, preventing or abating of Biological Pollutants, and no conclusions or inferences should be drawn regarding Biological Pollutants as they may relate to this project. The term “Biological Pollutants” includes, but is not limited to, molds, fungi, spores, bacteria and viruses, and/or any of their byproducts. A Client that desires these specialized services is advised to obtain them from a consultant who offers services in this specialized field. Geotechnical, Geologic and Environmental Reports Should Not Be Interchanged The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study and vice versa. 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 USTs or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. File No. 0181-010-00 C Natural Resources Assessment Report PORT GAMBLE S’KLALLAM TRIBE ADMINISTRATIVE CAMPUS MASTER PLAN CHAPTER 6: APPENDICES Memo To: Joe Sparr, Planning Director From: Port Gamble S’Klallam Tribe, Kingston, WA Project/File: 2042681800 - Task 1.4.2 Tim Nightengale; Darrell Rowe (Stantec) Bellevue, WA Date: June 19, 2024 Reference: Environmental Site Analysis (ESA) for the Port Gamble S'Klallam Tribe Administrative Campus CONTENTS 1 PROJECT DESCRIPTION / PURPOSE AND NEED STATEMENT ......................................................................... 1 2 ENVIRONMENTAL IMPACTS .................................................................................................................................. 4 2.1 2.2 Methods .............................................................................................................................................................. 4 Existing Conditions and Sensitive Areas............................................................................................................. 4 2.2.1 Subarea 1 ................................................................................................................................... 4 2.2.2 Subarea 2 ................................................................................................................................... 6 2.2.3 Subarea 3 ................................................................................................................................... 6 3 ALTERNATIVES....................................................................................................................................................... 8 4 REFERENCES.......................................................................................................................................................... 9 1 Project Description / Purpose and Need Statement Stantec and Ferguson Architects are contracted to create an Updated Master Plan for the Port Gamble S’Klallam Tribe Administrative Campus (Figure 1), focusing on planned improvements and land uses for three areas of the campus, shown in Figure 2 as Subarea 1, 2, and 3. Subareas 1 and 2 will include future improvements to the new Administrative Campus, including a new Administration building, community center, gym, village commons (plaza), and planned subterranean parking garage, along with additional parking, sidewalks, and park space. Subarea 3 will include structures to support Tribal Public Works and Facilities Operations and event space parking. As stated in Chapter 24.04.07 of the Port Gamble S’Klallam Tribe (PGST) Law and Order Code (LOC), the purpose of the Environmental Site Analysis (ESA) is to “identify design modifications or mitigation measures that will avoid or minimize adverse environmental impacts and achieve compliance with the purpose and standards of this title.” This ESA report has been prepared to: 1) identify any sensitive areas present within and around each of the proposed subareas on the Administrative Campus; 2) provide an analysis of any potential adverse environmental impacts by applying the Environmental Standards detailed in Chapter 24.08 of the PGST LOC; and 3) provide recommendations for potential mitigation or minimization of any potential adverse environmental impacts. These findings will be applied to the conceptual site planning and incorporated into the revised Master Plan. June 19, 2024 Joe Sparr, Planning Director Page 2 of 9 Reference: 2042681800 Figure 1. Existing Vicinity Map (Source: Google Earth & PGST Master Plans) June 19, 2024 Joe Sparr, Planning Director Page 3 of 9 Reference: 2042681800 Figure 2. Subarea Map for the Administrative Campus (Source: Google Earth) June 19, 2024 Joe Sparr, Planning Director Page 4 of 9 Reference: 2042681800 2 Environmental Impacts 2.1 Methods Stantec biologists first performed a desktop review of available public-domain information prior to their critical areas site visit. These online sources included U.S. Fish and Wildlife Service (USFWS) National Wetland Inventory (NWI) maps (USFWS 2024a), Washington Department of Fish and Wildlife’s (WDFW) Statewide Washington Integrated Fish Distribution (SWIFD) mapping (WDFW 2024b), Kitsap County’s GIS website (maps.kirklandwa.gov) for wetlands, streams, floodplains, and shoreline designations. A US Fish and Wildlife Service (USFWS) Information Planning and Conservation (IPAC) report was downloaded from their Trust Resources Database to determine any listed species or designated critical habitat areas within the vicinity of or in the project area (USFWS 2024b). Also, WDFW’s Priority Habitats and Species (PHS) lists were downloaded and an official PHS report was obtained for the project area (WDFW 2024a). GIS maps created by Soundview Consultants showing streams and wetlands on the Reservation were also reviewed by Stantec biologists for a general information about the Little Boston Creek, and if any wetlands were within or near the Project Area. Finally, Stantec biologists reviewed the Environmental Protection regulations (Title 24) within the PGST LOC for details on the environmental standards to be applied. On April 11, 2024, Stantec biologists Tim Nightengale, and Darrell Rowe walked Administrative Campus, around the perimeter of the campus, as well as the length of Little Boston Creek from the mouth to Little Boston Road, and the strip of land along the bluff on the west side of Little Boston Road. Using an Arrow 100 GNSS receiver in tandem with an iPhone12, Stantec biologists digitally recorded coordinates at each photograph taken, capturing images of the creek, stormwater drainage features, drainage ditches located around the perimeter of the ball field, and any potential wetlands and associated vegetation, specifically at areas where sensitive areas and their buffers would potentially intersect with Subareas 1, 2, or 3. Using the GPS Kit app, photographs were taken and GPS-located. Attachment A contains representative photographs from this site visit. 2.2 Existing Conditions and Sensitive Areas The Administrative Campus is approximately 22.0 acres, currently the located along the eastern side of Little Boston Road NE before it turns east and then north (Figures 1 and 2). Subarea 1 is approximately 2.9 acres and contains the Administration Building, Gym, Kitchen, Natural Resources Department building, and playground area. Subarea 2, approximately 4.0 acres, is located to the west of Little Boston Road NE, and runs along the bluff bordering Port Gamble Bay. Subarea 2 contains the Tribal Arts Center and Tribal Cemetery; the vacant residence pictured in Figure 2 had been demolished and cleared as of the April 2024 site visit. Subarea 3 is approximately 1.1 acres in size, located to the west of the ball field and south of Little Boston Road NE. The subarea contains several maintenance buildings and a parking area. 2.2.1 SUBAREA 1 Initial desktop review of critical areas within the vicinity of the Administration Campus revealed that the closest critical area near Subarea 1 was an unnamed fish bearing stream to the south of the property (Figure 3). The designated 150-foot stream buffer for fish bearing streams does not extend into Subarea 1, and only minimally extends onto the campus, near the equipment yard of the Natural Resources Laboratory area. Stantec biologists walked the perimeter of the campus to observe any other possible critical areas O Legend Fish bearing stream Wetland Wetland buffer (50 ft) Parcels 300 Feet (At original document size of 8.5x11) 1:3,000 Bluff buffer (150 ft) Stream buffers (150 ft fish bearing and 100 ft non fish bearing) 150 N ffi � � Stantec Project Location Prepared by NZ on 2024.06.18 Kitsap County, WA Client/Project Notes 1. Coordinate System: NAO 1983 StatePlane Washington North FIPS 4601 Feet 2. Data Sources: 3. Background: Port Gamble S'Klallum Tribe Figure No. 3 Title Critical Areas and Buffers Administrative Campus Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Staniec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data. June 19, 2024 Joe Sparr, Planning Director Page 6 of 9 Reference: 2042681800 that would extend buffers into Subarea 1. Biologists did trace drainage ditches along the perimeter, from the ball field perimeter, around the southeastern edge of the campus and down to the Natural Resources Laboratory area (see Attachment A, Photos 12-18). A stormwater drainage system appeared to be recently installed, with lines running from the ball field down to a storm drain near the Natural Resources Laboratory, which connected to the stormwater system and eventually flows into a drainage ditch that joins with the perimeter drainage ditch flow at the northwest corner of the Natural Resources Laboratory area (see Attachment A, Photos 19-21). The drainage ditches merge and flow into a thicket of Himalayan blackberries (Rubus armeniacus). Water was not observed beyond this point. Flow lines, signs of swept-away leaf litter, and deposited sediment was observed along the forested floor to the south of the campus area, but Stantec biologists did not observe any established stream bed or material, and no signs of wetland (hydrophytic) indicator plant species that would suggest stream or wetland conditions. It is likely the stormwater and drainage flows are newer and are infrequent, and that most flows quickly infiltrate into the ground. Therefore, no critical areas or buffers were observed that would be impacted by development within Subarea 1. 2.2.2 SUBAREA 2 Initial desktop review of critical areas within the vicinity of the Administration Campus revealed that the closest critical area near Subarea 2 was the marine bluff along the western edge of the subarea (Figure 2). Stantec biologists investigated the extent of Subarea 2 to observe any other possible critical areas or concerns. The top of slope of the bluff was generally 15 feet west of the cleared and mowed limits of the area. Towards the southern end of Subarea 2, the top of the bluff was typically covered with Himalayan blackberry, with red alder (Alnus rubra) and Western red cedar trees (Thuja plicata) trees further downslope. As the biologists neared the Tribal Art Center, the top of slope vegetation shifted to Nootka rose (Rosa nutkana) clusters, salal (Gaultheria shallon), and low Oregon grape (Mahonia nervosa), with larger Douglas fir trees (Pseudotsuga menziesii) and a more forested slope existing towards the northern end of Subarea 2 as it neared Little Boston Creek. The Environmental Standards stated in Chapter 24.08.01(g) of the PGST LOC give the marine bluff at 150foot setback limit, measured from the mean high-water level or at a distance equal to the height of the bluff, whichever is greater. The height of the bluff is around 60-70 feet, so a 150-foot buffer was extended inland from the boundary limit of the reservation (and western parcel boundaries), as shown in Figure 3. The Marine Bluff Setback regulations also indicate that this applies to structures and activities that are not marine shoreline dependent, which would include the proposed development use of Subarea 2, with additional parking and park space. The setback limit appears to extend approximately 30-40 feet beyond the top of the bluff, leaving the cemetery and art center largely outside of the setback. 2.2.3 SUBAREA 3 Initial desktop review of critical areas within the vicinity of the Administration Campus revealed that Little Boston Creek is immediately north of the property and could project a stream buffer into Subarea 3. Stantec biologists investigated Little Boston Creek during the site visit, following it from the creek mouth and the hatchery, upstream to the diversion structure which routes water to the hatchery. The stream was not accessible through the impounded area behind the diversion structure, so Stantec biologists walked around to Little Boston Road NE and re-entered further upstream. The stream lies within a ravine with steep slopes, with numerous Western red cedar and Douglas fir trees with an understory Western sword fern (Polystichum munitum). The streambanks featured salmonberry (Rubus spectabilis), osoberry (Oemleria cerasiformis), vine maple (Acer circinatum), lady fern (Athyrium filix-femina), sword ferns, Western red cedars, with clusters of youth-on-age (Tolmiea menziesii) and false lily-of-the-valley (Maianthemum dilatatum). See Attachment A for site photos 1-8. June 19, 2024 Joe Sparr, Planning Director Page 7 of 9 Reference: 2042681800 Exiting the stream at its crossing under Little Boston Road NE, Stantec biologists continued along the road, south towards the ball field. The shallow roadside ditch along the east side of the road was flowing north, with water running to the creek. Following the ditch further, flow was traced to a potential wetland area located along the east side of the gravel access road leading to Subarea 3 and the ball field, shown in Figure 3 (Attachment A, Photos 9-11). The area had standing water and featured filamentous algae growing throughout, strong indicators of wetland conditions. However, no formal delineation or hydric soil test was performed; a formal wetland delineation of this feature should be performed to confirm. The biologists continued to follow the perimeter of the ball field, and found that a shallow ditch was excavated around the perimeter, possibly to aid in the drainage of the ball field area. The ditch was nearly half full of water at the time of the site visit. Water likely was draining down to the potential wetland area and then continuing to the creek via the roadside ditch. The Environmental Standards stated in Chapter 24.08.01(c) of the PGST LOC places a natural buffer of 150 feet on all fish bearing streams, including Little Boston Creek, and a buffer of 50 feet on all wetlands. Figure 3 shows the application of this buffer limit on Little Boston Creek, revealing that the buffer extends across Little Boston Road NE and onto the Administrative Campus, particularly into the northern portions of Subarea 3 along the roadway. The buffer from the potential wetland also extends across the access road and into Subarea 3. The PGST LOC does not indicate how buffers should be applied when crossing existing substantial improvements (typically public infrastructure or buildings), termed “interrupted buffers.” Other municipal codes and shoreline master programs (SMPs) were reviewed for interrupted buffer regulations. Washington State Department of Transportation (WSDOT) only applies buffer areas on the same side of existing roadways as the associated critical area feature (e.g., wetlands or streams). The reasoning for this decision is that “buffer areas physically separated from a wetland or other water by an existing road can’t provide functions (such as screening, noise reduction, and water quality improvement) for the sensitive area” (WSDOT 2023); however, their guidelines also say to always review and apply regulations from the local municipal code. The City of Bremerton’s SMP contains regulation for interrupted buffers in Chapter 7.010(b)(3), stating: “When a buffer contains an existing legally established public or private road, the Director may allow development on the landward side of the road provided that the development will not have a detrimental impact to the shoreline. The applicant may be required to provide a report to describe the potential impacts. In determining whether a report is necessary, the City shall consider the extent and permanence of the buffer interruption and potential impact on shoreline ecological functions.” The City of Tacoma’s Municipal Code (Chapter 3.11, Critical Areas Preservation) also contains similar language, detailing that where “proposed activities that are within the critical area or buffer but are separated from the remaining critical area by a permanent substantial improvement, or are located in an existing permanent substantial improvement, may be allowed provided that the detrimental impact to the critical area does not increase.” The City of Tacoma also evaluates whether there is a potential of a hydrologic, geologic, and/or biological habitat connection along with the extent and permanence of the interruption. As a final example of interrupted buffer regulations, the City of Tukwila establishes an administrative waiver process for an interrupted buffer, using criteria that are similar to those stated by Tacoma and Bremerton regulations. To qualify for the waiver, the existing legal improvement creates a substantial barrier to the buffer function; the interrupted buffer does not provide additional protection of the critical area from the proposed development; and the interrupted buffer does not provide significant hydrological, water quality, and wildlife buffer functions relating to the portion of the buffer adjacent to the critical area. June 19, 2024 Joe Sparr, Planning Director Page 8 of 9 Reference: 2042681800 Given that both the stream buffer and the buffer from the potential wetland extend across existing roadways, the interrupted buffer scenario is applicable. It is unlikely that potential buffer area within Subarea 3 provides additional protection to Little Boston Creek or the potential wetland area or provides significant hydrological, water quality or wildlife habitat functions to those critical areas. As such, the functional buffer limits likely end at the roadway edge, and do not extend across the roadway into Subarea 3, any decision would need to be made at the discretion of Planning Director, in consultation with the Natural Resources Department. 3 Alternatives Review of the critical areas within and in the surrounding adjacent areas of the Administrative Campus during the April 11, 2024 site visit revealed no critical areas or buffers within Subarea 1, but a protective setback limit from the marine bluff in Subarea 2, and potential buffer areas from Little Boston Creek and a potential wetland area extending into Subarea 3. For development within Subarea 2, avoidance of construction within the setback limit should be avoided or minimized to the greatest extent possible. Should development plans extend into the setback, a geotechnical review should be conducted to determine any impacts to the slope stability and potential for erosion impacts. Construction activities near the setback limit should implement temporary erosion and sediment control (TESC) plans using appropriate storm water Best Management Practices (BMPs; silt fencing, straw wattles, clean gravel bags, etc.) to avoid and minimize contaminant-laden stormwater from leaving the Project area. Post-construction activities should include a restoration of vegetation to the top of the bluff, which would include the removal of invasive plants such as the Himalayan blackberries and scotch broom (Cytisus scoparius), and enhancements with native plants that would be suitable for the bluff and marine shoreline habitat. For development within Subarea 3, mitigation efforts will depend on how the Planning Director and Natural Resources Department will treat the interrupted buffers that extend into the subarea. At a minimum, any construction activities should implement TESC plans using appropriate storm water BMPs (silt fencing, straw wattles, clean gravel bags, etc.) to avoid and minimize contaminant-laden stormwater from leaving the Project area and entering the potential wetland and roadside ditch, eventually leading to Little Boston Creek. Additional BMPs would include wheel washes to prevent sediment from tracking out on tires and sweeping Little Boston Creek Road to prevent any sediment runoff from entering the buffer on the stream side of the road. Post-construction activities should include a restoration of vegetation on the other side of the road to enhance and restore buffer functions to the existing buffer. Efforts would include the removal of invasive plants, replacing them with native plants to match the existing riparian vegetation. Should the decision be to extend the buffer areas into Subarea 3, avoidance or minimization would require no structures or development of the northern and eastern edges of the subarea. If that is not possible, a recommendation would be to employ buffer averaging, which would reduce the standard buffer width of the stream or wetland in the subarea back to the road edge, and then increase the buffer width in other locations by an equal or greater amount of area. Those new buffer areas would be receive vegetation restoration or enhancements to provide protection for water quality and habitat to the stream or wetland. June 19, 2024 Joe Sparr, Planning Director Page 9 of 9 Reference: 2042681800 4 References United States Fish and Wildlife Service (USFWS). 2024a. National Wetland Inventory (NWI) online maps. < https://fwsprimary.wim.usgs.gov/wetlands/apps/wetlands-mapper/ > Accessed May 2024. USFWS. 2024b. Information for Planning and Consultation (IPAC).< https://ipac.ecosphere.fws.gov/ > Accessed June 2024. Washington Department of Fish and Wildlife (WDFW). 2024a. WDFW’s Priority Habitats and Species (PHS on the web) maps. < https://geodataservices.wdfw.wa.gov/hp/phs/ > Accessed June 2024. WDFW. 2020b. Statewide Washington Integrated Fish Distribution (SWIFD) mapping. < https://geo.nwifc.org/swifd/ > Accessed June 2024. Washington State Department of Transportation (WSDOT). (2023). How to document buffers for wetlands & other waters. WSDOT Environmental Services Office. Updated April 2023. < https://wsdot.wa.gov/sites/default/files/2021-10/Env-Wet-DelinGuideRdwyBuffer.pdf > Accessed June 2024. Attachment A. Administrative Campus Site Visit Photo Log Figure A-1 Administrative Campus Overview Map with Photo Points. D Environmental Site Assessment Report PORT GAMBLE S’KLALLAM TRIBE ADMINISTRATIVE CAMPUS MASTER PLAN CHAPTER 6: APPENDICES Phase I Environmental Site Assessment Port Gamble S'Klallam Tribe Subarea 2 and 3 Kingston, Washington 98346 Report Date: April 25, 2024 ASTM Expiry Date: September 6, 2024 Prepared for: Port Gamble S'Klallam Tribe 31912 Little Boston Road Northeast Kington, Washington 98346 Prepared by: Stantec Consulting Services Inc. 3400 188th Street SW, Suite 285 Lynnwood, Washington 98037 Project No.: 2042681800 Sign-off Sheet and Signatures of Environmental Professionals This document entitled Phase I Environmental Site Assessment, Port Gamble S'Klallam Tribe, Subarea 2 and 3, Kingston, Washington 98346 was prepared by Stantec Consulting Services Inc. (“Stantec”) for the account of Port Gamble S'Klallam Tribe (the “Client”). The conclusions in the Report are Stantec’s [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/tribal%3Aport_gamble_sklallam%3A4baf4d64880672e7. Public record. Not legal advice.