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January 3, 2025 <br />HWA Project No. 2021-159-21 <br />Geotechnical Engineering Report 11 HWA GEOSCIENCES INC. <br />Port Gardner Storage Facility <br />• VOCs (including acetone, carbon disulfide, 2-butanone, isopropylbenzene, and p- <br />isopropyltoluene) were detected in the three samples at concentrations below CULs. No <br />Ecology end use guidelines have been established for these VOCs. No other VOCs were <br />detected above laboratory reporting limits. <br />• Of the RCRA 8 Metals, barium and total chromium were detected in all three samples at <br />concentrations below CULs. No Ecology end use guidelines have been established for <br />these metals. Total chromium was detected at a concentration of 47 mg/kg in sample <br />HWA-14P-S05-12.5’, collected at a depth of 12.5 feet bgs. The MTCA Method A CUL <br />for hexavalent chromium is 19 mg/kg. Therefore, that sample was subsequently analyzed <br />for hexavalent chromium. Hexavalent chromium was not detected in that sample. No <br />other metals were detected above laboratory reporting limits. <br />• Of the SVOCs analyzed, which includes cPAHs: <br />o cPAHs were not detected in any of the samples above laboratory reporting limits. <br />o The SVOCs naphthalene, phenanthrene, fluoranthene, pyrene, and/or di-n- <br />butylphthalate were detected in two of the samples at concentrations below <br />MTCA CULs. Naphthalene’s Category 1 reuse guideline is 0.05 mg/kg, and the <br />concentrations detected in these samples did not exceed that. No Ecology end use <br />guidelines have been established for the other SVOCs mentioned above. No other <br />SVOCs were detected above laboratory reporting limits. <br />• PCBs were not detected in any of the samples above laboratory reporting limits. <br />3.6.2 Analytical Results for Groundwater Samples <br />Analytical results for groundwater samples collected from wells HWA-14P and HWA-16P in <br />October 2023 are summarized in Table C-2. The analytical results indicate: <br />• Gasoline-range TPH was detected in the sample obtained from HWA-14P at a <br />concentration of 560 micrograms per liter (μg/L), which is below MTCA CUL. Gasoline- <br />range petroleum hydrocarbons were not detected above laboratory reporting limit in <br />sample HWA-16P. <br />• Diesel- and oil-range TPH were detected in sample HWA-14P at concentrations of 2,700 <br />and 1,300 μg/L, which both exceed MTCA Method A CULs. There were no detections of <br />these analytes at concentrations exceeding the laboratory reporting limits in sample <br />HWA-16P.