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1 <br /> THRIFTY OIL CO. <br /> 1 <br /> • April 26, 2005 O 56556 <br /> Mr Mike Infurna, Jr RWQCB #390652 <br /> Senior REHS Global ID #T0607700504 <br />' County of San Joaquin Confirmation #7332374691 <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 /> t Circle K Station #2745449 APR 9, 8 ZQ0 <br /> 5 <br /> 7647 Pacific Avenue <br /> Stockton, CA 95207 EAiMONMENT HEALTH <br />' 1st Quarter 2005, Status Report and PERMYSEAVICFS <br /> Possible New Release andlor Active Source <br />' Dear Mr Infurna <br /> Presented herein is the First Quarter 2005, 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 /> conducted during the first quarter of 2005 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 22, 2005, is presented in Table 1. In general, <br />' groundwater occurs under the site at depths ranging from 32 42 feet below top of casing (btc) in <br /> monitoring well MW-4 to 36 40 feet bte in monitoring well MW-11 (Appendix A) A <br /> groundwater elevation contour map based upon February 22, 2005, data is presented as Figure 2 <br />' Groundwater appears to flow to the northwest at an approximate hydraulic gradient of 0 019 <br /> feet/foot This flow direction is consistent with the previous quarter but represents a reversal of <br /> flow direction from prior to the 4th Quarter 2004 This quarter there was significant rise in <br />' groundwater elevations due to the recent rains which may have affected the groundwater flow <br /> direction In addition, the system was turned off only one day in advance and the pumps were <br /> left in the wells <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 22, 2005, and delivered in a chilled state, in an ice <br />' chest, following strict Chain-of-Custody procedures to a state certified laboratory These <br /> samples were analyzed for volatile aromatic compounds benzene, toluene, ethylbenzene, and <br /> xylenes (BTEX) and selected oxygenates (including MTBE) by EPA Method 8260B, and for <br /> Qo <br />' 13116 Imperial Highway, Santa Fe Springs, CA 90670 0 (562) 921-3581 <br />