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Work Plan for Additional Excavation July 27, 1992 A & M Market, Acampo, California QEC 92-120-1W i from below the tanks, at concentrations of 600 parts per million (ppm) and 1,300 ppm (samples S-14-T2W, S-14-T1W, respectively). TPHg was detected in one soil stockpile sample at a concentration of 33 ppm (sample S-0619-1). BTEX was detected in some samples at concentrations indicated in Table 1. EDB ani EDC were not detected in any of the samples. Lead was detected in concentrations ranging from 6 to 14 parts per million. i Proposed Work k This excavation program is proposed to remove hydrocarbon-bearing soil from the tank cavity until either hydrocarbon concentrations in soil remaining in place are acceptable to the SJCLHD or until the safe operating limit of the equipment has been reached. As part of our excavation program we will perform the fdllowing tasks: :i • prepare a site safety plan discussing the precautions and protective equipment required for work at the site. • observe the excavation of hydrocarbon-hearing soil from the tank cavity. We will monitor the excavated soil for levels lof hydrocarbon vapors using a photoionization detector (PID); we anticipate that the area below the west ends of former tanks T-1 and T-2 will be deepened about six feet, and the remainder of the tank cavity will be deepened about two feet; the decision to terminate excavating will be made in the field. • collect relatively undisturbed soil samples from the limits of the excavation after PID readings indicate that hydrocarbon concentrations are less or until the safe operating limits of the equipment Have been reached; we estimate that ten samples will be collected with one from each sidewall of the excavation and one from the base of the excavation below each former tank; soil samples will be collected from the backhoe bucket using a drive-type sampler containing a clean brass sleeve; soil samples will be covered with aluminum foil and plastic end caps, sealed. with tape, then placed in iced storage for transport under Chain-of=Custody protocol to the analytical laboratory. j • submit soil samples to a State-certified laboratory and analyze for TPHg by modified EPA Method 8015 and benzene, toluene, ethylbenzene, and total xylene isomers (BTEX) using EPA Method 18020. i t