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AOC Work Plans <br /> 4.2 Former Teepee Structure <br /> Site Summary <br /> During the 1960s to the late 1970s,wood waste and trash were burned and disposed of in a metal <br /> teepee structure located south of the former cover plant building and north f the former box <br /> factory building on the west side of the railroad track traversing the properly(Plate 4.2). No <br /> further information on the historical use of this AOC was available. <br /> Soil was excavated from the former teepee structure in 1994 and stockpile (along with soil <br /> removed from the burn pits; discussed below in Section 4.3)on the north ai id east sides of the <br /> northern bum pit(Plate 4.3). The volume of soil excavated from the teeped area was estimated to <br /> be approximately 425 cy based on a drawing showing a circular area with 2 57-foot diameter that <br /> was excavated to a depth of 4.5 feet bgs(AGE, 2001). The stockpiled soil was disposed at Forward <br /> Landfill in Manteca,California in June 2004. <br /> Previous Investigations. <br /> In 1992,Kleinfelder collected three soil samples(at depths of 7 inches bgs from teepee structure <br /> and analyzed them for metals only which were detected in all soil samples. With the exception of <br /> arsenic (detected at a maximum concentration of 11 mg/kg)none of the dei ected concentrations of <br /> metals exceeded their respective residential PRG. <br /> After excavation of soil in 1994, Stockton Service Station Equipment Com any(SSSE)collected <br /> three soil samples from the excavation floor and walls(at depths of 4.5 fee bgs)of the teepee <br /> structure and analyzed them for arsenic,copper,lead and zinc only. Labor tory analyses detected <br /> arsenic,copper,lead, and zinc at maximum concentrations of 0.55, 39, 7.1 and 61 mg/kg <br /> respectively. The arsenic concentration of 0.55 was just above the residen al PRG 0.34 mg/kg <br /> residential. Concentrations of the remaining metals were below residentia PRGS. <br /> Draft <br /> KB61125 workplan-ESC MACTEC Engineering and Consulting, Inc. 30 <br /> September 28,2005 <br />