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ASPECT CONSULTING <br />80 FINAL PROJECT NO. AS190583A-08  MAY 21, 2025 <br /> Arsenic and copper in groundwater <br /> Mercury and zinc in soil <br />Constituents that were not detected at concentrations greater than the PCLs in soil or <br />groundwater samples collected within the Warehouse Subarea of Unit A include benzene, <br />ethylbenzene, and toluene, and metals, VOCs, and SVOCs, which are not included in the <br />list above. <br />The soil and groundwater data for the Warehouse Subarea are summarized on <br />Tables 6-7 and 6-8, respectively. The sample locations for constituents detected at <br />concentrations exceeding the PCLs in the Warehouse Area of Unit A are presented on <br />Figures 6-A2 through 6-A11. The data for constituents detected at concentrations <br />exceeding the PCLs are summarized by constituent group in the following subsections. <br />6.5.1.1.1 Petroleum Hydrocarbons, BTEX, and PAHs <br />As described in Section 2.2.4, Unit A includes a pair of historical bulk fuel <br />storage/distribution facilities operated by the Standard Oil and Associated Oil companies <br />prior to construction of the warehouse. The former Associated Oil bulk fuel storage <br />facility encompassed land beneath the western portion of the warehouse and immediately <br />north of it. The area north of the warehouse included large ASTs for Bunker C fuel oil and <br />smaller ASTs for gasoline in the northwesternmost part of the area (area addressed by <br />Bunker C ASTs IA). The Standard Oil facilities were located beneath the eastern and <br />central portions of the warehouse, as shown on Figure 6-A2. <br />The IA successfully removed accessible TPH-contaminated soil within the area of the <br />former Bunker C ASTs located immediately north of the warehouse. Additional soil <br />excavation in this area was precluded by the presence of the warehouse foundation. <br />Detected concentrations of TPH-G and/or TPH-D+O exceeded soil PCLs in sidewall soil <br />samples collected at the southern edge of the IA excavation (north edge of warehouse) at <br />depths ranging from 2 to 8 feet bgs, which extends into the saturated zone (Figures 6-A2 <br />and 6-A3; Table 6-7). Concentrations of TPH-G and/or TPH-D+O exceeding PCLs were <br />also detected in soil samples collected within the areas of the historical bulk fuel facilities <br />beneath the warehouse (within the saturated zone; Figures 6-A2 and 6- A3). <br />Two total xylenes detections in soil exceeded the PCL (Figure 6-A4 and Table 6-7). The <br />soil PCL is based on leaching to groundwater and considers volatilization from <br />groundwater to indoor air (VI). However, there are no xylene exceedances in sub-slab or <br />indoor air in that area (WH-North collocated sub-slab air and indoor air sample location; <br />Figure 6-A1; Tables 6-15a, 6-15b, and 6-15c). Also, there are no exceedances of xylenes <br />in groundwater in this area (Table 6-8). The air and groundwater data, described above, <br />empirically demonstrate that the soil xylene concentrations in that area, as long as the <br />warehouse remains as an effective cap, are protective of groundwater and air. <br />Total cPAH (TMEQ) concentrations exceed the soil leaching PCL in samples of soil <br />contaminated with Bunker C oil located along the north edge of the warehouse <br />(Figure 6-A5). Maximum cPAH TMEQ concentrations in the saturated zone of the <br />Warehouse Subarea exceeded 2 mg/kg at several locations (one location has <br />concentrations greater than 7 mg/kg), which is greater than 10 times the saturated soil