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28 October 1997 <br />�! AGE-NC Project No 97-0330 <br /> Page 2 of 4 <br /> installation of domestic water wells at 1635 North Sierra Nevada Avenue and 2135 Orwood <br /> Avenue However, neither property owner had any knowledge of any domestic water wells <br /> on their properties Furthermore, both property owners indicated that water was provided by <br /> the City of Stockton water system <br /> According to PHS-EHD files on record, a septic tank system is located approximately 100 <br /> feet south-southwest of the former UST area Based on depth to ground water at the site <br /> (approximately 65 feet bsg) and the presumed up-gradient location of the septic tank system, <br /> it is unlikely that the septic tank system is a receptor for any UST hydrocarbon release to <br /> ground water <br /> Laboratory analysis of a composite sample collected from stockpiled soil at the site detected total <br /> petroleum hydrocarbons quantified as diesel (TPH-d) at a concentration of 4,700 parts per million <br /> (ppm), and toluene, ethylbenzene and xylenes at concentrations as high as 0 52 ppm We recommend <br /> that the limited volume (< 2 cubic yards) of soil cuttings be sparsely spread throughout the site <br /> Elevated concentrations of TPH-d were detected in a soil sample from probe boring P-1 at a depth <br /> of 20 feet bsg and from P-2 at depths of 25 and 35 feet bsg Reduced concentrations of TPH-d were <br />�b detected from P-2 at 45 and 50 feet bsg It appears that soil impacted by TPH-d between the former <br /> UST area and the former dispenser area is limited in vertical extent to depths slightly greater than 50 <br /> feet bsg Volatile aromatics (benzene, toluene, ethylbenzene and xylenes BTEX) and poly-nuclear <br /> aromatics (PNAs) were detected from P-1, P-2 and from stockpiled soil, however all detected <br /> constituents were below the State of California Maximum Contaminant Levels (MCLs) for drinking <br /> water and the EPA's Preliminary Remediation Goals for Planning Purposes Therefore, it is unlikely <br /> that any known BTE&X and PNA compounds in soil beneath the site pose a significant <br /> environmental threat to ground water <br /> Although TPH-d was encountered in ground water samples collected at P-3 and P-4, the <br /> concentrations of dissolved TPH-d appear to rapidly decline between P-3 to P-4, assuming ground <br /> water flow towards the north-northeast Volatile aromatics (benzene, toluene, ethylbenzene and <br /> xylenes BTEX) and poly-nuclear aromatics (PNAs) were not detected in ground water samples <br /> collected at the site Therefore, it is unlikely that the known dissolved petroleum hydrocarbons <br /> beneath the site pose a significant environmental threat to ground water <br /> SITE CLOSURE REQUEST <br /> The responsible party (RP)for this site is Mr Shanjibhai Ranchhod, who is seeking a closure for this <br /> site The San Joaquin County PHS-EHD has indicated a willingness to consider granting closure for <br /> this site and has requested AGE to provide a rational for closure The following discussion presents <br /> Advanced GeoE?n%lronmentai,Inc <br />