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AOC Work Plans <br /> 4.3 Burn Pits <br /> Site Summary <br /> Wood waste and trash were disposed from the 1960s to the late 1970s in tN fo open burn pits located <br /> west of the storm water pond(Plate 4.3). The bum pits were filled in circa 1984 and were <br /> subsequently re-excavated circa 1994. The rationale for re-excavating the soil was not specified in <br /> any of the reports reviewed. <br /> Soil excavated from the burn pits was temporarily stockpiled on the Site north and east of the <br /> northern bum pit. The stockpile generated from the excavation of the nort iern and southern bum <br /> pits were estimated to be approximately 1,100 and 450 cy respectively. Bc th stockpiles were <br /> disposed at Forward Landfill in Manteca,California in June 2004 on the bE sis of stockpile sample <br /> results from a sampling event in April 2004. <br /> Previous Investigations. <br /> In October 1992,Kleinfelder advanced four soil borings(BN-1,BN-2,BS 3,and BS4),two in <br /> each burn pit,to a maximum depth of 20 feet bgs. A total of 10 soil sampl s were collected and <br /> analyzed for TPHd, and the metals copper,chromium, lead,nickel, and zi . One sample, <br /> collected at a depth of 10 feet bgs from the northern bum pit was also analyzed for <br /> dichloromethane(DCMA),trichloroethene(TCE),and tetrachloroethene CE). Concentrations of <br /> DCMA,TCE, and PCE were detected at levels below the residential PRGs of 9.4,0.053,and 1.5 <br /> mg/kg for DCMA,TCE,and PCE respectively. TPHd was detected in thr of the analyzed <br /> samples at concentrations ranging between 15 and 26 mg/kg. Selected me is were also detected in <br /> all soil samples collected at the Bum Pits. Copper and lead exceeded the residential PRGs of 3,100 <br /> and 300 mg/kg,respectively,in one sample collected from the fill in the n h pit. The sample <br /> Draft <br /> KB61125 workplan-ESC MACTEC Engineering and Consulting, Inc. 33 <br /> September 28,2005 <br />