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4 SUMMARY OF FINDINGS <br /> PSC continues to monitor subsurface conditions and the plume of gasoline-impacted <br /> groundwater at the Earthgrains facility PSC's data from this current monitoring event <br /> and from previous assessments indicates that the plume of groundwater impacted <br /> with detectable hydrocarbons is approximately 100 feet wide, and some 550 feet long, <br /> elongated in the same east-northeast direction as groundwater flow The highest <br /> concentrations of petroleum hydrocarbon compounds are centered around the former <br /> 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 in 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 conditions <br /> Current analytical results suggest that the air sparging and soil venting remedial <br /> operations are beginning to prove successful in removing dissolved phase gasoline <br />' contaminants in groundwater TPH-G and BTEX concentrations in the recent MW-1 <br /> groundwater sample are significantly lower than those previously measured in July <br /> 2001 TPH-G concentrations in MW-1 samples have reduced from 20,000 µg/l (in <br />' July 2001) to 11,000 pg/1 (in October 2001) Benzene concentrations have also <br /> reduced from 970 µg/1 to 190 µg/l Similar reductions, however, have not yet been <br /> observed in the SP and PZ wells located near the former gasoline USTs The <br /> remediation system will continue to operate to remove contaminants from the <br /> subsurface <br /> 11 <br /> October 2001 <br /> Groundwater Monitoring Report <br /> THE EARTHGRAINS BAKING COMPANY <br /> 2651 South Airport Way <br /> Stockton,California <br /> Prepared for THE EARTHGRAINS BAKING COMPANY Prepared by Philip Services Corp <br /> H1£NV%24001321121382EGVSwcklonLStockfon11001mondoc November 16,2001 <br />