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i <br /> THRIFTY URL CU , <br /> ' October 16, 2000 <br /> ' Mr Michael J Infurna Jr <br /> Senior REHS ' <br /> County of San Joaquin t� <br /> ' Site Mitigation Unit IV/LOP } <br /> 304 East Weber St , Fifth Floor _ <br /> Stockton, CA 95202 <br /> RE Former Thrifty Oil Co. Station #171 <br /> ' 1250 North Wilson Way <br /> Stockton, CA 95205 <br /> 3rd Quarter 2000, Status Report <br /> ' Dear Mr Jnfurna <br /> ' Presented herein is the Third Quarter 2000, Status Report prepared for former Thrifty Oil Co <br /> (Thrifty)Station#171 at 1250 Wilson Way, Stockton,California(Figure 1) Presented in this report <br /> are the results of the site monitoring efforts conducted during the Third Quarter 2000 Thrifty has <br /> retained the services of Earth Management Company (EMC) to conduct quarterly monitoring and <br /> sampling activities at this site <br /> ' Groundwater Monitoring <br /> Depth to groundwater is measured in each monitoring well on a quarterly basis In general, <br /> ' groundwater occurs under water table conditions beneath the station at depths ranging from 39 57 <br /> feet below ground surface(bsg)in monitoring well TB-10 to 4178 feet bgs in monitoring well MW- <br /> 6 (Appendix A) A groundwater elevation contour map based upon August 23, 2000 data is <br /> presented as Figure 1,and data indicates the direction of groundwater flow is generally toward the <br /> east with a hydraulic gradient ranging from of approximately 0 007 feet/foot to 0 012 feet/foot <br /> Local flow toward the west is present in the southeastern corner of the site <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 August <br /> 23, 2000 Groundwater samples were obtained by EMC and delivered in a dulled state following <br /> strict Cham-of Custody procedures to a state certified laboratory and analyzed total petroleum <br /> hydrocarbons as gasoline (TPH-g) by EPA method 8015 modified and for volatile aromatic <br /> ' compounds of benzene, toluene, ethylbenzene, and xylenes (BTEX), using EPA method 8021E <br /> Starting in the third quarter of 1997, as required by the Central Valley Regional Water Quality <br /> Control Board (CVRWQCB), samples were analyzed for oxygenates by EPA Method 8260 The <br /> ven oxygenates which were analysed"are" Di-isopropyl ether(RIPE), Ethanol, Ethyl tert-Butyl <br /> 13539 E Foster Road, Santa Fe Springs, CA 90670-0138 • (562) 923-9876 <br />