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4MAR SUM Y OF FINDINGS Philip has continued to monitor subsurface conditions and the plume of gasolme- impacted groundwater at the Earthgrain's facility Philip's data from this current monitoring event, and from previous assessments indicates that the plume of groundwater impacted with detectable hydrocarbons is approximately 100 feet wide, and some 550 feet long, elongated in the same east-northeast direction as groundwater flow The highest ' concentrations of petroleum hydrocarbon compounds are centered near the former gasoline USTs, and around wells MW-1 and SP-1 The lateral extent to the north, south, and west had been delineated by historic, non- detectable, petroleum concentrations measured in groundwater samples collected from wells in those directions To the east, a TPH-G concentration of 100 µg/l was measured in a groundwater sample collected from CPT-3 during the May 1999 site investigation This same sample did not contain benzene, and Acculabs had characterized the TPH-G analysis as being uncharacteristic of a typical gasoline, suggesting that the impact was more characteristic of degraded gasoline Philip will continue to monitor sample results from downgradient well MW-12 to assess conditions to the east The oxygenate compound D1PE was measured at trace levels in samples collected from wells MW-4, MW-12, and PZ-1, and at higher concentrations in samples collected from MW-1 and SP-1 The compound TBA was measured in the sample from MW-1 for the first time since oxygenates have been analyzed for, indicating that this measurement may be an anomalous event Philip will continue to monitor oxygenate levels to assess site conditions ' Based on recent monitoring results, Philip concludes that rate of natural petroleum hydrocarbon degradation is not progressing as effectively as previously estimated Philip ' and Earthgrains are evaluating a plan to implement an air-sparging and soil venting remediation system to initiate petroleum hydrocarbon source removal in the vicinity of the former gasoline USTs Earthgrains has sparge-and-vent remediation equipment ' currently stored at their Stockton facility Philip is inspecting this equipment for effectiveness and eventual use Philip's conceptual plan is to initiate air sparging in wells SP-1 and SP-2, and to control volatilization of the petroleum compounds by venting from wells MW-1, MW-2, MW-5, MW-7, and MW-12 A more fully developed corrective action plan is tentatively scheduled to be submitted to the PHSIEHD in February or March of 2000 Collection of groundwater samples from all of the site monitoring wells, and an evaluation of baseline petroleum hydrocarbon concentrations, will be performed prior to the initiation of the air ' sparging and soil venting remediation 9 November 1999 Groundwater Monitoring Report The Earthgrains Company 2651 South Airport Way Stockton,California Prepared for THE EAKTHGRAINS COMPANY Prepared by Philip Services Corp January 17,2000