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THRIFTY OIL CO. <br /> i1P,;EN P'At'RM <br /> IEA!_ Ii <br /> ^r r 111 13f{ �TMIE <br /> April 21, 2004 04 APR 23 PI1 3 07 <br /> Mr Mike Infurna, Jr RWQCB 4390652 <br /> Senior REHS Global ID #70607700504 <br /> County of San Joaquin Confirmation 47175344765 <br /> Public Health Services/Environmental Health Division <br /> 304 East Weber Avenue, 3rd Floor <br /> Stockton, CA 95202 <br /> RE Former Thrifty Oil Co. Station #172 <br /> TOSCO Station #2705449 T <br /> 7647 Pacific Avenue <br /> Stockton, CA 95207 <br /> I st Quarter 2004, Status Report <br /> Dedr Mr Infurna <br /> Presented herein is the First Quarter 2004, Status Report prepared for former Thrifty Oil Co <br /> (Thrifty) Station #172 located at 7647 Pacific Avenue, Stockton, California (Figure 1) This <br /> report presents the results of the site monitoring and remediation system operation activities <br /> condaued during the first quarter of 2004 Thrifty has retained Earth Management Co (EMC) to <br /> • conduct quarterly monitoring, sampling, and remediation activities at this site <br /> Groundwater Monitoring <br /> Depth to groundwater is measured in each monitoring well on a quarterly basis Gauging data <br /> obtained from June 1991 through February 5, 2004, is presented in Table 1. In general, <br /> groundwater occurs under the site at depths ranging from 32 39 feet below top of casing (btc) in <br /> monitoring well MW-5 to 35 96 feet btc in monitoring well MW-4 (Appendix A) A <br /> groundwater elevation contour map based upon February 5, 2004, data is presented as Figure 2 <br /> Groundwater appears to flow to the southeast and northwest at approximate hydraulic gradients <br /> ranging from 0 04 to 0 054 feet/foot The flow direction in the fourth quarter was to the <br /> southeast Gauging data from the February 5, 2004, monitoring event produced an inconsistent <br /> groundwater elevation contour map According to the field notes, the readings were taken while <br /> it was raining <br /> Quarterly Groundwater Sampling <br /> As part of the groundwater-monitoring program, groundwater samples were obtained from <br /> monitoring wells MW-3 through MW-11 (except MW-8, which was abandoned) Groundwater <br /> samples were obtained by EMC on February 5, 2004, and delivered 1n a chilled state, in an ice <br /> chest, following stnct Cham-of-Custody procedures to a state certified laboratory These <br /> �j samples were analyzed for volatile aromatic compounds benzene, toluene, ethylbenzene, and <br /> Qo <br /> 13116 Imperial Highway, Santa Fe Springs, CA 90670• (562) 921-3581 <br />