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January 3, 2025 <br />HWA Project No. 2021-159-21 <br />Geotechnical Engineering Report 10 HWA GEOSCIENCES INC. <br />Port Gardner Storage Facility <br />3.5 AQUIFER PUMP TESTING <br />Aquifer pump testing was performed in early- to mid-August 2024 to evaluate the hydraulic <br />properties of the aquifer in the vicinity of the PGSF site. The purpose of the evaluation was to <br />provide prospective contractors with data to support planning and design of dewatering <br />alternatives for deep excavations. Additional details regarding the aquifer pump test are <br />presented in Appendix E. The information presented in Appendix E is applicable to the location <br />of the test only and may not be representative of conditions elsewhere along the project <br />alignment. <br />An additional pump test was conducted as part of the West Marine View Drive Storm and <br />Combined Sewer (WMVD) project. The draft results of the WMVD pump test are presented in <br />Appendix E-1 for reference. <br />3.6 ENVIRONMENTAL SAMPLING <br />Analytical results for soil and groundwater samples are tabulated in Appendix C, Table C-1 <br />(soil) and Table C-2 (groundwater). Copies of final laboratory reports, including chain-of <br />custody documents, are included in Appendix C. Analytical data is compared to Ecology’s <br />MTCA cleanup levels (CULs), which may not apply to the site and are provided only as a <br />screening level indication of the environmental quality of the site. Soil sample results are also <br />compared to Ecology’s guidelines for reuse of petroleum-contaminated soils, specifically the <br />Category 1 reuse guidelines for unrestricted use. The Ecology Category 1 end use criteria are <br />generally for use in handling soils from petroleum cleanups and also may not apply to this site <br />but are compared for reference only. Previous investigators at the site have compared their <br />results to MTCA Method A (Industrial) CULs, MTCA Method C (Industrial) CULs, Washington <br />State background levels for naturally occurring metals, and site-specific levels for arsenic, <br />copper, lead, mercury, nickel, zinc, and cPAHs. <br />3.6.1 Analytical Results for Soil Samples <br />Analytical results for the three soil samples analyzed from the October 2023 explorations are <br />summarized in the attached Table C-1. The analytical results indicate: <br />• Gasoline-range TPH were not detected above laboratory reporting limits in any of the soil <br />samples. <br />• Diesel- and oil-range TPH were detected in sample HWA-14P-S05-12.5’, collected from <br />a depth of 12.5 feet bgs, at concentrations of 86 and 220 milligrams per kilogram <br />(mg/kg), respectively, which are both below MTCA Method A CULs. However, the <br />concentrations exceed Ecology’s Category 1 end use guidelines for unrestricted reuse.