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SECOND QUARTER 2003 GROUNDWATER MONITORING REPORT AND ADDMONAL ASSESSMENT REPORT JAMAR OIL DISTRIBUTION JUNE 2003 Groundwater Analysis Groundwater samples were analyzed for TPH G and-TPH D by EPA Method 8015M and for BTEX, 1,2-DCA, EDB, and the fuel oxygenates(MTBE, TBA, DIPE, ETBE, and TAME)using EPA Method 8260B. The analyses were conducted by SunStar Laboratories Inc., a California State-certified laboratory, in accordance with state guidelines and EPA protocol. SITE EVALUATION Sensitive Receptor Survey A sensitive receptor survey was conducted within a '/z mile radius of the subject site. Banks Information Solutions, Inc. (Banks) conducted a Department of Water Resources (DWR) search of wells located within a'h mile radius of the subject site. Ten domestic and one California Water Service well were located by the Banks search. GHH also performed a door to door well search in the vicinity of the subject site. Four wells were identified during this door to door well search. GHH's search also included trying to find the eleven wells located by the Banks search. Table 3 of this report details all fifteen wells which were identified either by Banks or GHH as being within 2000 feet of the subject site. One of the identified wells,the F. Calwell well at 1200 South Oro Avenue, is located downgradient of the subject site. This well was identified on the Banks report but was not located by GHH in the field. The other wells do not appear to be directly downgradient but are more up or cross-gradient. The Banks Water Well Report is included as Appendix C. Aquifer Performance Tests A step drawdown Aquifer Performance Test(APT)was conducted on May 22, 2003 at the subject site. The objectives of this testing were to: evaluate the hydraulic conditions beneath the site; to estimate the influence a possible pumping system may have on the migration of TPH constituents in the groundwater; and to evaluate whether there is hydraulic communication between existing wells onsite. The distance drawdown data and calculations are summarized on Table 4. The hydrologic data, test parameters, and data for the slug tests and 3 gallon per minute (gpm)pump test are included in Appendix D. On May 22, 2000, fixed volume slug tests were performed on two of the onsite monitoring wells and the extraction well (MW-1, MW-4, and EW-1), to obtain an estimate of well hydraulic parameters. Two new bailers were placed in EW-1 and one new bailer was placed in both MW-1 and MW-4 and the wells were allowed to equilibrate. 8