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21 October 2020 <br />Project No. 14-3002 <br />Page 14 of 15 <br />beneath the southwest portion of the former power plant. This waste cell is <br />approximately 10,000 square feet with waste observed between four (4) and <br />12.5 feet bsg, and the limits of the waste cell are undefined (Figure 4). <br /> Based on the location and depth of the stormwater basin relative to the property <br />boundary and the investigation performed, it’s unlikely that any additional waste <br />remains west of the property boundary from the South Waste Cell formerly located <br />at 17100 Murphy Parkway. <br /> PCBs were detected above the DTSC-SL of 0.58 mg/kg in one (1) surface sample, <br />eleven (11) samples collected at 3 feet bsg; seven (7) samples collected at 5 feet <br />bsg; four (4) samples collected at 7 feet bsg; and three (3) samples collected at <br />10 feet bsg. PCBs were not detected in samples collected beneath 10 feet bsg <br />(Tables 1 through 6). <br /> The maximum PCB concentration was detected in sample B46-7 at 320 mg/kg. <br />Sample B46-7 was collected just above glass waste that started at eight (8) feet <br />bsg and from clay encountered between 7 and 8 feet bsg. Clay was not <br />encountered above 18 feet bsg in any other borings. The next highest <br />concentrations were detected in B47-5 at 100 mg/kg; B44-3 (Soil/Waste) at <br />48 mg/kg; B48-5 (Waste) at 33 mg/kg; and B47-7 at 21 mg/kg (Tables 1, 3, 4, <br />and 5). <br /> The maximum PCB concentrations were generally detected from borings where <br />waste was encountered. The highest concentrations were detected at five (5) and <br />(7) seven feet bsg, which are the approximate depths where waste was <br />encountered and/or begins beneath the former power plant area (Tables 1, 4, <br />and 5). <br /> The maximum PCB concentrations were also detected beneath the former <br />transformer area in the southwest corner of the power plant. The former <br />transformer area is also the location of the waste cell identified beneath the <br />southwest corner of the former power plant area. <br /> Based on the data distribution, the location of waste cells, and historical <br />information provided about the facility, it’s likely the PCB impact originated from <br />the glass processing waste buried beneath the former power plant. The former <br />power plant area comprises a small portion of the property and is where most of <br />the day to day operations were performed. The approximate extent of PCB- <br />impacted soil above the DTSC-SL at each sampling depth (Surface, 3, 5, 7 and 10 <br />feet) is depicted in Figures 4 through 8. <br /> Elevated concentrations of TPH-d and TPH-mo were detected at 5 feet bsg in B46, <br />B66, B67 and B68; at 10 and 15 feet bsg in B47; and at 15 feet bsg in B65. TPH-d <br />were detected above the DTSC-SL of 500 mg/kg in five (5) samples total with three <br />of the five samples collected at 5 feet bsg (Table 7). Additionally, field evidence of <br />impact was observed (color and odor) in soil collected between three and four feet <br />bsg in borings B45, B47, B51, B53, B55, B65, B66 and B67 (Appendix C). The