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F <br /> Chevron U.S.A. - Page 2 <br /> Control Board, the treated soil was to be placed as backfill <br /> in the pit. At the current time the pit is still seven to <br /> eight feet below surface grade. <br /> i <br /> Aeration of stockpiled soil commenced on March 20, 1990, <br /> as permitted by the San Joaquin County Air Pollution Control <br /> District. The soil is aerated by loosely spreading a lift <br /> about one foot thick over plastic. The lift is exposed to <br /> air and sunlight and left in place as needed to achieve <br /> "none-detected" readings with an HNu photoionization <br /> detector. To date, five lifts have been placed. "Non- <br /> detected" lifts are picked up and stockpiled and a new lift <br /> of contaminated soils are then spread. <br /> Stockpiled, treated soil has been composite sampled and <br /> chemically analyzed prior to placement as engineered fill. <br /> Composite sampling will occur at a frequency of one composite <br /> sample for each 50 cubic yards of stockpiled soil. <br /> A total of twelve composite samples (each composed of <br /> three discreet samples) were submitted to Pace Incorporated <br /> laboratory for chemical analysis. Approximate sample <br /> locations are shown on Plate 2 of this report. Samples were <br /> analyzed for the presence and concentration of benzene, <br /> toluene, xylenes, ethylbenzene (EPA method - 8015 modified) <br /> DAMES sL MOORE <br />