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.:if 1 MJT AI i n District -- Environmental Health Division (the County) . The work plan was subsequently approved by the .County and the scope of work has been completed by WESTON. 3.0 Field Work Field work involved the drilling and installation of three monitor wells and the sampling of soil and groundwater at the three wells. Placement of the wells was designed to provide site specific gradient information and upgradient and downgradient water quality information on the first encountered groundwater system. Additionally, information was collected on the lithology present at the site and on the presence or 'absence of diesel residues in the soils at the well locations The wells were spaced roughly equidistant around the excavated area in a triangular configuration (Figure 1) . Radial distances from the center of the excavated area to the wells are approxi- mately 100 feet. Each well is screened 10 to 15 feet into saturated soils, with the screen extending an additional 15 feet or more above the water table to allow for the measurement of any floating hydrocarbon data year round. Soil samples were collected at 5 foot intervals from ground � _. surface to the water table to provide lithologic information. Additionally, all samples were screened with a photoionizer and inspected for possible diesel residues. If a sample appeared suspect, it was to be submitted for chemical analysis. In all cases, the two samples closest to saturated soils at each monitor well location were submitted for chemical analysis, as described in Section 5.0. One soil sample was submitted as a duplicate to provide a check on the laboratory methods; the sample was not identified to the laboratory as a duplicate. Following development of the wells, groundwater samples were obtained. The procedure at each well involved: checking for the presence of floating hydrocarbons and, if present, measuring its thickness; bailing a sample from the surface of the Mater column for a total petroleum hydrocarbons analysis; purging at least three standing well volumes; bailing an aromatic volatile organ- ics sample from the well; and submission of the samples under chain-of-custody to the laboratory for analysis. Also submitted to the laboratory were one duplicate sample (to check laboratory procedures) and one field rinsate blank (to check the effective- ness of field -decontamination"proceduras)-.----Ne ither-of- these— samples were identified to the laboratory as a duplicate or blank sample. Specifics of the field program, including equipment - 2 -