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THRIFTY OIL CO. <br /> 4 <br /> • January 12, 2006 0.63309 <br /> 1 <br /> Mr Michael J Infurna Jr RWQCB #390187 <br /> Senior RENS Global ID #T0607700132 <br /> County of San Joaquin Confirmation #7172596573 <br /> Site Mitigation Unit IV/LOP <br /> 304 East Weber St , Fifth Floor "IE C E(J j�fj ED <br /> Stockton, CA 95202 LL'�� (�L! 11 <br /> RE Former Thrifty Oil Co. Station #171 <br /> JAN 1 7 2006 <br /> ARCO Products Company Station #9600 ENVIRONMENT HEALTH <br /> 1250 North Wilson Way PERMIT/SERVICES <br /> Stockton, CA 95205 <br /> 41h Quarter 2005, Status Report <br /> Dear Mr Infurna <br /> Presented herein is the Fourth Quarter 2005, Status Report prepared for former Thrifty Oil Co <br /> (Thnfty) Station#171 at 1250 Wilson Way, Stockton, California(Figure 1) This report <br /> presents the results of the site monitoring and remedial efforts conducted during the fourth <br /> quarter of 2005 Thrifty has retained the services of Earth Management Company(EMC) to <br /> conduct quarterly monitoring and sampling of the groundwater monitoring wells, and monthly <br /> sampling/weekly operation and maintenance activities for the on-site soil vapor extraction (SVE) <br /> remediation system <br /> Groundwater Monitoring <br /> Depth to groundwater is measured in each monitoring well on a quarterly basis In general, <br /> groundwater occurs beneath the station at depths ranging from 47 73 feet below top of casing <br /> (btc) in monitoring well TB-10 to 49 72 feet btc in monitoring well MW-6 (Appendix A) A <br /> groundwater elevation contour map based upon November 22, 2005, data is presented as Figure <br /> 2, and groundwater generally flows northeast under a gradient of approximately 0 0012 feet/foot <br /> Data from well TB-7 was not included because it was considered anomalous <br /> Quarterly Groundwater Sampling <br /> As part of the groundwater-monitoring program, groundwater samples were obtained from <br /> monitoring wells MW-2, MW-3R, MW-4, MW-6, TB-1, TB-7, T13-8, TB-10, EW-5s, and EW- <br /> 5d on November 22, 2005 Groundwater samples were obtained by EMC and delivered in a <br /> chilled state following strict Chain-of-Custody procedures to a state certified laboratory <br /> Samples were analyzed for total petroleum hydrocarbons (TPHg) by EPA Method 8015M, and <br /> for benzene, toluene, ethylbenzene, and xylenes (BTEX), and selected oxygenates (di-isopropyl <br /> ether(DlPE), Ethyl tert-Butyl Ether(ETBE), Methyl tert-Butyl Ether(MTBE), Tert-Amyl <br /> Methyl Ether (TAME), and Tert-Butanol (TBA)), and 1,2-DCA using EPA Method 8260B As <br /> requested by the San Joaquin County Environmental Health Department (SJCEHD) in their letter <br /> dated December 9, 2004, ethanol and methanol were analyzed by ASTM Method 8015M <br /> QO <br /> 13116 Imperial Highway, Santa Fe Springs, CA 90670• (562) 921-3581 <br />