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1.0 INTRODUCTION This report documents Fourth Quarter 1993 ground water monitoring at the AT&T Communications, Inc. (AT&T) facility (site) located at J110 West Turner Road, Stockton, California 1.1 PREVIOUS WORK AT&T has operated four underground fuel storage tanks (USTs) at this site. Those tanks were removed by Kleinfelder in May 1987 and overexcavation of soil containing diesel fuel ' was completed immediately following tank removal. The data from the UST removal and overexcavation were presented in a report prepared by Kleinfelder dated May 21, 1987. That report stated that only one soil sample from the base of the northern portion of the excavation contained petroleum hydrocarbons exceeding method detection limitS. This sample, designated SS-07, contained 21 milligrams per Kilogram(mg/Kg) or parts or million (ppm) total petroleum hydrocarbons as diesel (TPH-D) and was collected at a depth of 18 feet below ground surface (bgs) The location of the former tank and the limits of the overexcavation is provided on Figure 1 In late October and early November 1990 ESE drilled five soil borings within and near the ' former excavation (Figure 1). Three of those soil borings were converted to ground water monitoring wells (MW-1, MW-2 and MW-3). Soil boring B-2Y was terminated at an ' approximate depth of 15 feet below ground surface (bgs) due to auger refusal caused by construction debris A grab composite sample of soil cuttings, reported to contain asphalt ' chips, was collected and analyzed at the direction of a San Joaquin County Public Health Services/Environmental Health Division (PHS/EHD) representative The concentration ' of TPH-D in that sample was reported at 110 mg/Kg. Analytical results for soil samples ' collected from soil borings MW-1, MW-2, and MW-3 (later converted to ground water monitoring wells) and B 2X indicated concentrations of TPH-D less than 4 mg/Kg. 1 Environmental Science F\6935186\4gmr 93 1 &Engineering,Inc 1