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27 January 2004 AGE-NC Project No. 97-0360 Page 7 of 9 No additional wells were located within 2,000 feet of the subject property on the Department of Water Resources(DWR)database or the San Joaquin County Flood Control and Water Conservation _ District (SJCFC&WCD) map. No other wells were identified during the physical survey. Figure 3 depicts the approximate location of the domestic water wells and ground water monitoring wells located during the receptor survey. A review of files on record with the EHD did not locate any septic pits or septic systems located on the site. 5.0. ASSESSMENT OF HYDROCARBON-IMPACTED SOIL AND GROUND WATER On 25 October and 24 November 1999, hush Geosciences Inc., excavated trenches T1 through T8 to a maximum depth of approximately 10 ft bsg,.to assess soil and ground water conditions at the site. The trenches were located in the vicinity of the former USTs'. As a result of the initial findings further investigation of the site was preformed. rr - Between July 2000 and August-2003, eight soil probe borings (P-1 through P-8), five ground water monitoring wells(MW-1 through MW-5) and one extraction well (EW-1)were installed at the site; seven ground water monitoring/sampling events were performed at the site to investigate the extent of hydrocarbon-impacted ground water in the vicinity of the former USTs. _ The greatest concentrations of petroleum hydrocarbon-impacted soil was encountered in soil probe boring P-4 at a depth of 10 feet bsg (Table 2); P-4 is located southwest of the former UST pit (Figure 2) Low concentrations of TPH-d-impacted ground waier have been encountered on three occasions in samples collected from well EW-1. Concentrations of TPH-g decreased in wells MW-1, MW-2, MW-4, MW-5 and EW-1 from 270 µg/1, 200 ug/1,,380 pg/l,230 µg/1,and 360 ug/l,respectively,to non detectable concentrations between the January 2002 and August 2003 ground water monitoring events No other petroleum constituents of concern were detected from the ground water monitoring events. Analytical results of ground water samples are summarized in Tables 3 and 5. Generally, gray to brown, damp to saturated, clay was encountered from surface grade to approximately 20 feet bsg in monitoring well borings MW-4,MW-5 and EW-1, from surface grade to approximately 15 feet bsg in monitoring well borings MW-1 and MW-3 and from 25 feet to 30 feet bsg in monitoring well boring MW-2. Dark brown, saturated, silty sand was encountered from 15 feet bsg to 20 feet bsg in monitoring well borings MW-1 and MW-3 and from30 feet to 35 feet bsg in monitoring well boring MW-2. Lines of cross section are illustrated on Figure 2 and stratigraphic cross sections are depicted on Figures 1 1 and 12. Advanced GIUEnvirOnfTlCntal,Inc.