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4 SUMMARY OF FINDINGS <br /> PSC continues to monitor subsurface conditions and the plume of gasoll ne-impacted <br /> ' groundwater at the Earthgram's facility PSC's data from this current monitoring <br /> event and from previous assessments indicates that the plume of groundwater <br /> impacted with detectable hydrocarbons is approximately 100 feet wide, and some 550 <br /> ' feet long, elongated in the same east-northeast direction as groundwater flow The <br /> highest concentrations of petroleum hydrocarbon compounds are centered around the <br /> former gasoline USTs near wells MW-1, SP-1, and PZ-1 <br /> ' The lateral extent to the north, south, and west had been delineated by historic, non- <br /> detectable, petroleum concentrations measured in groundwater samples collected <br /> ' from wells in those directions To the east, a TPH-G concentration of 100 µg/l was <br /> measured 1n a groundwater sample collected from CPT-3 during the May 1999 site <br /> investigation This CPT-3 sample did not contain benzene, and Acculabs <br />' characterized the TPH-G analysis as being uncharacteristic of a typical gasoline, <br /> suggesting that the impact was more characteristic of degraded petroleum <br />' The oxygenate compound DIPE has been detected in samples collected from wells in <br /> relatively close proximity to the source The oxygenate compound TBA, not observed <br /> this quarter, has only been detected sporadically PSC will continue to monitor <br /> oxygenate levels to assess site condylions <br /> Petroleum hydrocarbon concentrations have not yet shown a significant decrease <br /> since the installation and operation of the site's air spargyng and venting remediation <br />' system It is PSC's opinion that concentration decreases have not yet occurred <br /> because of the inconsistent operation of this system due to the frequent energy <br /> disruptions in the area It is PSC's opinion that a more continuous operation of the <br />' system will result in the expected decrease of petroleum hydrocarbon impact PSC <br /> intends to perform the next round of groundwater monitoring 1n October 2001 <br /> 11 <br /> July 2001 <br /> Groundwater Monitoring and <br /> Remedial Action Results <br /> The Earthgrains Company <br /> 2651 South Airport Way <br /> Stock-ton,California <br /> Prepared for THE EARTHGRAINS COMPANY Prepared by Philip Services Corp <br /> H TNV1624001324121382EGLStockton\Stockton10701mon doc August 14 2001 <br />