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iii 71 Ms Lon Duncan April 12,2001 Page 5 of 6 trichloroethene (TCE) at 3 3 ppb The groundwater sample collected from well MW3 (in the former UST location) contained elevated levels of contaminants, including TPH oil and grease (98,000 ppb), TPHg (14,000 ppb), TPHd (4,400 ppb), and benzene (61 ppb) Toluene, ethylbenzene, xylenes and various other constituents were also detected in well MW3 No PCE or TCE was found above the detection limit of 50 ppb in well MW3 No lead was detected in any site well Groundwater analytical results are summarized in Table 5 and the estimated extent of contamination in groundwater is shown on Figure 6 Laboratory reports and chain of custody documentation are included in Attachment C 4.0 SUMMARY • Four groundwater monitoring wells (MW 1-MW4) were installed at the site to further investigate the extent of soil and groundwater contamination at the site • No petroleum hydrocarbons or VOCs were detect in soil samples collected from the capillary fringe zone in the perimeter borings (MW1, MW2, MW4) Lead was present at background levels • Field observations (odors, staining, FID readings) indicated that soil in the immediate vicinity of the former UST (boring MW3) has been contaminated by waste oil that apparently leaked from the former UST An oily sheen was noted in the saturated zone • Groundwater was initially encountered at approximately 23 5-25 5 feet bgs during drilling and stabilized at a depth of approximately 21 5-22 5 feet bgs Groundwater apparently flows northeast The gradient in December 2000 was 0 003 • Groundwater analytical results indicated that petroleum hydrocarbon contamination is present in groundwater in the immediate vicinity of the former UST but does not extend to perimeter wells located approximately 20 feet southwest, 35 feet north, and 40 northeast of the former UST No lead was detected in any well, but various chlorinate solvents were detected in all site wells • PCE was detected at levels exceeding the primary Maximum Contaminant Level (MCL) of 5 ppb in wells MW1 (29 ppb), MW2 (23 ppb), and MW4 (18 ppb) No PCE was detected in well MW3, although the detection limit was elevated to 50 ppb because of sample dilution at the laboratory 5.0 CONCLUSIONS The lateral and vertical extent of soil and groundwater contamination has been defined Petroleum hydrocarbons in soil appear to be limited to a small area in the immediate vicinity of the former UST (see Figure 3) and petroleum hydrocarbon contamination in groundwater does not 0 1DaWGROUNDZE\GABBARDWports\WELLRPT doc