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l THRIFTY OIL CO. <br /> July 28, 2005 0.59099 <br /> Mr Michael J Infurna Jr RWQCB #390187 <br /> Senior REHS Global ID #T0607700132 <br /> County of San Joaquin Confirmation #1755858838 <br /> Site Mitigation Unit IV/LOP <br /> 304 East Weber St , Fifth Floor <br /> Stockton, CA 95202 �� L <br /> RE Former Thrifty Oil Co. Station #171 _ <br /> ARCO Products Company Station #9600 to j ' 1 X005 <br /> 1250 North Wilson Way Ei`�V;h�` �,1E4� HEALTH <br /> Stockton, CA 95205 pERlv11T/SER\110ES <br /> 2nd Quarter 2005, Status Report <br /> Dear Mr Infurna <br /> Presented herein is the Second Quarter 2004, Status Report prepared for former Thrifty Oil Co <br /> (Thrifty) 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 second <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 44 21 feet below top of casing <br /> (btc) in monitoring well EW-5s to 48 60 feet btc in monitoring well MW-2 (Appendix A) A <br /> groundwater elevation contour map based upon May 24, 2005, data is presented as Figure 2, and <br /> groundwater generally flows northeast under a gradient of approximately 0 0033 feet/foot Data <br /> from well TB-8 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, TB-8, TB-10, EW-5s, and EW- <br /> 5d on May 24 and 25, 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 (DIPE), 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 /> idated 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 />