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ATC Associates Inc. %T(: 1117 Lone Palm Avenue,Suite 201 Modesto,California 95351 209-579-2221 fax:209-579-2225 ASS O C I ATE S I N C . hydrocarbons were not detected at or above laboratory reported detection limits in the groundwater samples collected from MW-1, MW-2, or MW-3. On April 19, 1988, an additional monitoring well (MW-4) was installed north of the former location of the USTs. Based on Kleinfelder's Additional Monitoring Well report dated April 22, 1998, petroleum hydrocarbons were detected in the groundwater sample collected from MW-4 on April 19, 1988. In late April 1988, the open excavation associated with the former USTs was expanded by excavating petroleum impacted vadose zone soils. As reported in Kleinfelder's Soil Removal Report dated May 3, 1988, approximately 350 to 400 cubic yards of soil were excavated from April 25 to 28, 1988. Laboratory analyses of soil samples collected from the sidewalls of the enlarged excavation indicated low concentrations of petroleum hydrocarbons remained at the south and southeastern portion of the excavation. On February 26, 1993, Parker Environmental Services (P.E.S.) advanced seven soil borings (BH- 1 through BH-7). Soil samples were collected from each boring and a groundwater sample was collected from each boring except BH-7. Petroleum hydrocarbons were detected in soil samples collected from all the borings except BH-1 and BH-3. Petroleum hydrocarbons were detected in all of the groundwater samples. Water levels measured at the site on March 2, 1993, indicated the groundwater flow direction was to the southeast. Refer to P.E.S.'s Interim Report on Subsurface Investigation Work at Cheaper! #37 dated April 20, 1993 for more details. From July to October 1995, P.E.S. conducted subsurface investigation activities that included installing four monitoring wells (MW-5 through MW-8) on-site and advancing 14 hand augured soil borings (B-8 through B-21). Borings B-15 through B-21 were advanced off-site to the west, southwest, and south. Groundwater was encountered at approximately 6.5 feet bgs. Soil and groundwater samples were collected from B-8, B-10 through B-18, B-20, B-21, and MW-5 through MW-7. A groundwater sample was also collected from MW8. Petroleum hydrocarbons were detected in all of the soil samples except for the samples collected from MW-5 through MW-7, B-14 located east of the former UST location, and B-20 and B-21 located off-site to the southwest and south, respectively. Petroleum hydrocarbons were detected in the groundwater samples except the samples collected from B-14, B-20, B-21, MW-1, MW-2, MW-3, MW-6, and MW-7. MW-4 was not sampled due to the presence of approximately 0.02 inches of free product. Refer to the report prepared by P.E.S. titled Environmental Site Investigation Methods and Findings: Drilling of Soil Borings, Drilling and Installation of Groundwater Monitoring Wells Collection and Analyses of Soil and Groundwater Samples, dated November 17, 1995 for more information. In a letter dated April 11, 2002, the SJCEHD indicated that upgradient monitoring wells MW-2 and MW-3 could be reduced to annual monitoring and that the lateral and vertical extent of soil contamination remains undefined. SAEnvironmenta1\25847\37 Tracy\Reports\Response 2009 Aug.doc 2