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r ' 17 March 1996 AGE-NC Project No 95-0128 Page 5 of 8 grain size) sandy-gravel was encountered from depths of 35 to 45 feet bsg Ara indurated clay underlaid the sandy gravel at depths of 40 to 50 feet bsg Based upon soil samples submitted for geotechnical analysis,the upper clay has a lower permeability than the saturated, poorly graded (coarse-grain size) gravel encountered below, at approximately 30 feet bsg Ground water is present in the gravel It appears that the clay lithology occurring immediately below the ground water bearing zone has a low permeability and might restrict vertical migration of ground water The laboratory report of the geotechnical analysis (CTL Laboratory ID 255-04C) and chaila-of=custody are presented in Appendix I- 42 42 ANALYTICAL RESULTS OF SOIL SAMPLES TPH-g was detected in one of seven soil samples analyzed at a concentration of 1 2 mg/kg (milligrams per kilogram or parts per million ppm) FPH-d was detected in two soil samples at �• concentrations up to 4 1 ppm Low concentrations of volatile aromatics were detected in each sainple analyzed The highest concentration of benzene detected was 0 009 ppm(sample B10-25) MTBE was detected in soil samples analyzed at concentrations up to 0 076 ppm (sample 139-30) Analytical results of soil samples are summarized on Table 1 -Analylical Results of Soil Samples The laboratory report (MAI Laboratory ID 73344 through 73350), QA/QC report and chain-of- custody hain-ofcustody are in Appendix F Analytical results y esu is of soil samples submitted for physicochemical analysis and microbiological enumeration indicate that there were no measurable microbe activity at the site rhe lack of biodegrading bacteria may be due to hydrocarbon concentrations in excess of 10,000 ppm or the presence of biotoxic compounds in the subsurface at the site, such as metals or pesticides However, adequate concentrations of necessary nutrients for microbe growth and sustenance were present in tlhe 5011 di rhe site The microbiological laboratory report (A Keitti Kaufman report dated I,,ebruary 07, 1997) and chain-of-custody form are included in Appendix G 43 GROUND WATER ELEVATION AND GRADIENT The casingelevation of each well was surveyed relative to a Cit of Stockton bench mark The } y elevation of ground water in each well was calculated by subtracting the ground water depth from