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24 May 2021 <br />Project No. 14-3002 <br />Page 21 of 23 <br /> <br />PCB Aroclor 1254, dioxins, Pb and TPH. Maximum concentrations of COCs were <br />detected in waste samples and in soil samples collected either directly above or beneath <br />waste. Waste Cell No. 2A encompasses a large area of the southwestern corner of the <br />Facility including the former transformer area. The maximum PCB concentrations in <br />Waste Cell No. 2A were encountered between five and seven feet bsg and north of the <br />former transformer location. PCB-containing materials were historically utilized in <br />electrical transformers and components. However, the age of the former transformers at <br />the Site (1990 to 2013) and the data collected, specifically the depth of PCB impact, does <br />not indicate the PCB contamination originated from the former transformers at the Facility. <br /> <br />Cross-sections A-A’ through E-E’ (Figures 17 through 21) illustrate the relationship <br />between the buried glass waste and the COCs detected at the Site. COC contamination <br />and waste extents correlate in most locations. <br /> <br />COCs were detected at considerably higher concentrations in AOC2 than AOC1. This is <br />likely attributed to the volume of waste encountered in AOC2. Using an average thickness <br />for each waste cell, approximately 33,000 cubic feet of waste is located in AOC1 and <br />approximately 120,000 cubic feet of waste is located in AOC2; The larger volume of waste <br />in AOC2 subsequently contained a larger volume of contamination and at higher <br />concentrations than the waste buried in AOC1. It is likely the wastes were deposited at <br />different times and from different batches of waste glass produced at the former LOF/PNA <br />facility. It is also likely that glass waste containing higher concentrations of PCBs, dioxins, <br />and TPH was used in the Facility area where it was eventually covered and contained <br />when the Facility was constructed. <br /> <br />The glass waste buried beneath the Facility released elevated levels of COCs into the <br />subsurface environment. PCB Aroclor 1254 exceeded the RSL in over 20 samples and <br />two samples exceeded the California Hazardous Waste Limit of 50 mg/kg. PCB Aroclor <br />1254 was not detected above the RSL in any of the surface samples or samples collected <br />in the collection pond area south of the Facility. Samples that exceeded the hazardous <br />waste limits and most of the samples that exceeded the RSL were detected at 5.0 and <br />7.0 feet bsg. The data indicates that the elevated and hazardous levels of PCBs are <br />associated with the wastes that begin at approximately 4.0 feet bsg and extend to <br />approximately 12 and 14 feet bsg in AOC2. The vertical extent of PCB contamination is <br />defined and does not extend to the water table. Dioxins and TPH-d migrated through the <br />porous waste cells and the sands below the waste to impact groundwater in AOC2; but <br />the dioxin concentrations were detected significantly below the MCL and TPH-d exceeded <br />the MCL Priority in only two samples. <br /> <br />COC contamination in AOC2 appears to be confined to the waste encountered in the <br />Facility area. Although, Waste Cell No. 2A is undefined to the west and south and COC <br />contamination, specifically PCB Aroclor 1254, may extend outside of the Facility area in <br />these directions. Only surface samples were collected to the immediate south and west <br />of the Facility. <br />