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r <br /> LTH <br /> October 25, 1995 <br /> C!� l" Fntit 4 t4 9. 03 <br /> Michael Infurna, Sr RENS %cES1 <br /> San Joaquin County PHS <br /> Environmental Health Division <br /> P. O Box 388 <br /> Stockton, CA 95201-0388 <br /> Re Seventh Quarterly Groundwater Monitoring Report, 1500 Shaw Road, Stockton, CA, Site <br /> Code 1727 <br /> Dear Mr Infurna <br /> This report summarizes the monitoring and sampling event conducted on August 31, <br /> 1995 Field activities at the above referenced Canteen facility include monitoring and sampling <br /> of the seven monitor wells onsite and the two offsite monitor wells (MW-8 and MW-9) from the <br /> U S Chemical property, which were monitored and sampled and included with this data for the <br /> first time <br /> Based on the groundwater elevations from the monitor wells, the groundwater gradient <br /> was 0 44 feet per 100 feet and the general direction of groundwater flow was to the south Fluid <br /> level measurements for this event and historical events are summarized in Table 1 and the <br /> Potentiometric Surface map is included as Figure 1 <br /> Free product was not detected in any of the monitor wells <br /> The groundwater elevation was significantly higher (15 feet) during the previous <br /> monitoring event (March 29) due to increased rainfall The groundwater elevation for this event <br /> was still higher than the first six events and above the top of the screened intervals in each well, <br /> however, groundwater was 5 6 feet lower than the March 29th event The two offsite wells <br /> (MW-8 and MW-9), which were contoured with the Canteen monitor wells, were consistent with <br /> the established groundwater flow direction (south) <br /> The benzene, toluene, ethylbenzene, total xylenes (BTEX), and TPH-G concentrations <br /> decreased or remained the same in monitor wells MW-1, MW-2, MW-4, MW-5, MW-6, and <br /> MW-7, with the exception of the TPH-G concentration in MW-2, which increased from 200 to <br /> 210 µglL Monitor well MW-3, the monitor well downgradient of the former tank hole, had <br /> an increase in benzene, BTEX, and TPH-G concentrations with 7,560 µg/L, 9,296 µg/L, and <br /> 40,000 µg/L, respectively The two monitor wells on the U S Chemical property, MW-8 and <br /> MW-9, had benzene, total BTEX, and TPH-G concentrations below method detection limits <br /> 16415 Addison Road, Suite 700• Dallas, Texas 75248-2460•Tel (214) 380-9555 • Fax (214) 380-5553 <br />