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n i ` r 5 July 1995 AGE-NC-95-0124 Page 2 of 6 ' excavation (total depth of approximately 8 feet) and a second sample was collected from the west wall of the excavation, where soil staining was observed After collection of the soil samples, the 1 excavation was backfilled Total petroleum hydrocarbons quantified as gasoline (TPH-g), ethylene dibromide (EDB) and lead I were detected in the soil sample collected from beneath the UST at concentrations of 15,000 parts per million(ppm), 1,800 ppm and 13 ppm, respectively TPH-g, EDB and lead were detected in the sample from the west sidewall at concentrations of 13,000 ppm, 2,300 ppm and 38 ppm, respectively 2 4 GROUND WATER DEPTH AND FLOW DIRECTION According to the San Joaquin County Flood Control Map (Fall, 1993), depth to ground water at the site is approximately 60 feet and the regional flow direction is south or southeast AGE maintains ' morutonng wells approximately 1,000 feet southeast of the subject site that indicate a ground water depth of 55 feet (April 1995) with a southerly flow direction 3.0. SITE ASSESSMENT AND REMEDIATION ' 3 1 SOIL BORING DRILLING, 28 SEPTEMBER 1993 On 28 September 1993, one soil boring (boring B3) was drilled within the former UST excavation by Geological Audit Services, Inc (GeoAudit) Samples collected from depths of 20, 30 and 35 feet (B3-20, B3-30 and B3-35)were analyzed for TPH-g and volatile aromatics (benzene, toluene, ethyl benzene and xylenes BTE&X) TPH-g`was detected in sample B3-20 at 5 7 mg/kg (ppm), BTE&X were detected in sample B3-20 at concentrations ranging from 0 092 ppm to 0 61 ppm TPH-g and BTE&X were not detected in samples B3-30 or B3-35 Analytical results of the soil samples are summarized in Table 1 The boring log is included in Appendix A The laboratory report and chain of custody are included in Appendix B 1 32 EXCAVATION OF HYDROCARBON IMPACTED SOIL, 27 APRIL 1994 On 27 April 1994, approximately 100 cubic yards of hydrocarbon impacted soil was excavated from the former UST area by Goins Environmental Construction (GEC} of Sacramento An excavator was used to remove soil from the former tank area to a depth of 20 feet The excavation was approximately 15 feet wide by 20 feet long } GeoAudit collected five soil samples from the excavation one from each sidewall and one from the