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1 <br /> 11 November 1999 <br /> AGE-NC Project No 97-0230 <br /> Page 6 of 7 <br /> ground water flow direction toward the northeast in southeast Stockton, regional depth to <br /> ground water maps also published by the SJCFCD indicate a depth to first encountered <br /> ground water near the site of approximately 50 feet bsg <br /> • General llthology beneath the site consists of brown/gray, damp to moist, fine sandy silt was <br /> encountered from approximately 5 feet bsg to 10 feet bsg Between 10 feet bsg and 25 feet <br /> bsg, a brown/gray, damp to moist, silty fine sand was encountered A brown/gray, damp to <br /> moist, fine sandy silt was encountered from 25 feet bsg to 35 feet bsg At depths in excess <br /> of 35 feet bsg, a brown, damp to moist, silty fine sand was encountered <br /> • Faint to intense hydrocarbon odor was noted in duplicate soil samples collected from P-3 at <br /> depths between 5 feet bsg and 15 feet bsg and from boring P-4 at 15 feet bsg <br /> • Organic vapor was detected in soil sample duplicates from P-1, P-3 and P-4 using a PID at <br /> concentrations as high as 844 parts per million (ppm) <br /> • TPH-g was detected In soil samples collected from probe borings P-1, P-3 and P-4 at <br /> concentrations as high as 60 mg/kg <br /> • TPH-d was detected in soil samples collected from P-1,P-3 and P-4 at concentrations as high <br /> as 110 mg/kg <br /> • BTEX compounds were detected in soil samples collected from P-3 and P-4 at <br /> concentrations as high as 4 4 mg/kg <br /> • MTBE was detected In soil samples collected from P-1, P-3, P-4 and P-5 at concentrations <br /> as high as 39 mg/kg <br /> Based on data collected during the August 1999 preliminary site Investigation, AGE concludes <br /> • The soil horizon at the site consists of approximately 10 feet of fine sandy silt underlain by <br /> approximately 15 feet of silty fine sand underlain by 10 feet of fine sandy silt, which in turn <br /> Is underlain by a silty sand of undetermined thickness <br /> • The soli underlying the former UST pit has been Impacted by petroleum hydrocarbons to <br /> depths as great as 35 feet bsg <br /> • The mayor portion of the petroleum hydrocarbon soil-impact at the site appears to have been <br /> caused by a gasoline release, a minor portion may have been the result of a dleseI release <br /> • The horizontal extent of petroleum hydrocarbon-impacted soil Is not known northeast and <br /> southeast of P-4, the vertical extent of petroleum hydrocarbon-impacted soil is not known <br /> . in the areas of P-3 and P-4 <br /> • Ground water at the site may have been Impacted by petroleum hydrocarbons <br /> A&anced GeoEn-.ironmentai,Inc <br />