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July 19, 2002 RWQCB #390187 <br /> Global ID #T0607700132 <br /> Mr Michael J Infurna Jr Confirmation#8463428437 <br /> Senior REHS <br /> County of San Joaquin <br /> Site Mitigation Unit IVILOP <br /> 304 East Weber St , Fifth Floor <br /> Stockton, CA 95202 <br /> RE Former Thrifty Oil Co. Station 071 <br /> ARCO Products Company Station #9600 <br /> 1250 North Wilson Way <br /> Stockton, CA 95205 <br /> 2nd Quarter 2002,Status Report <br /> Dear Mr Infurna <br /> Presented herein is the Second Quarter 2002, Status Report prepared for former Thrifty Oil Co <br /> (Thrifty) Station 4171 at 1250 Wilson Way, Stockton, California(Figure 1) Presented in this report <br /> are the results of the site monitoring and remedial efforts conducted during the second quarter of <br /> 2002 Thrifty has retained the services of Earth Management Company (EMC)to conduct quarterly <br /> monitoring and sampling,monthly sampling,and operation and maintenance activities for the on-site <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 4137 feet below ground surface (bgs) <br /> in monitoring well MW-4 to 43 87 feet bgs in monitoring well MW-6 (Appendix A) A <br /> groundwater elevation contour map based upon May 7, 2002 data is presented as Figure 1, and it <br /> appears that groundwater flows radially away from monitoring wells MW-4 and MW-5 with an <br /> approximate gradient ranging from 0 02 to 0 09 ft/ft <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-5, MW-6, TB-1, TB-7, TB-8, and TB-10 on May <br /> 7, 2002 Groundwater samples were obtained by EMC and delivered in a chilled state following <br /> strict Chain-of-Custody procedures to a state certified laboratory Samples are analyzed for total <br /> petroleum hydrocarbons (TPH-g) by EPA method 8015M modified for gasoline, for volatile <br /> • aromatic compounds of benzene, toluene, ethylbenzene, and xylenes (BTEX), with selected <br />