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from the wells and equipment decontamination water was placed in Department of Transportation (DOT) approved 17H drums. The contents of the drums were transported by a licensed waste hauler for ' disposal at a licensed waste treatment facility. The volume of groundwater removed from the wells and other measured sampling parameters are noted on the water sampling logs included in Appendix B. 3.0 LABORATORY ANALYSIS ' The groundwater samples were transported to STL Chromalab Analytical Labs, Inc,, a state-certified laboratory, located in Pleasanton, California. The groundwater samples were analyzed for the presence of TPH-G, BTEX, the five fuel oxygenates, and 1,2 DCA and EDB in accordance with USEPA Method 8260B. Copies of the laboratory analytical report and chain of custody record are in Appendix C. 4.0 SUMMARY OF RESULTS Based on thegroundwater-level data for September 11, 2003 (Table 1), the groundwater flow direction ' in both the upper and lower aquifers was generally towards the east-southeast at gradients of approximately 0.002 and 0.001,respectively(see Figure 3 and Figure 4). The average depth to water in upper aquifer wells MW-5, MW-6, MW-7 and MW-10 increased approximately 0.65 feet, and the ' average depth to water in the lower aquifer wells MW-1R, MW-2, MW-3, MW-4, MW-8 and MW-9 increased 0.57 feet since last quarter sampling event. The groundwater flow directions and gradients noted during this sampling event are consistent with historical trends. Analytical results of groundwater samples collected from current and past sampling events are presented in Table 1 and Table 2. Analytical laboratory results of groundwater samples collected on September 11, 2003 indicate that TPH-G was present at co centrations of 130 micrograms per liter (µg11) in monitoring well MW-1R, 940 }tg/l in MW-4, and 1,8D0 µg11 in MW-5. BTEX compounds were reported as below method detection limit concentrations in all wells except MW-4 and MW-6, where toluene and ethylbenzene were reported at concentrations of 0.52 pg/l and 0.66 µg11, respectively. MTBE was reported in lower aquifer wells MW-1R, MW-2, MW-4 and MW-9 at concentrations ranging from 4.8 gg/I at MW-9 to 1,200 µg/l at MW-2. MTBE was also reported in groundwater samples collected from upper aquifer wells MW-5,MW-7 and MW-10 at concentrations of 1,300 gg/l, 1.1 µgll and 0.68 µg/l. . Fuel oxygenates (TBA, DIPS, ETBE, TAME) other than MTBE, and 1,2-DCA and EDB were not detected in the groundwater samples collected from wells sampled this quarter with the exception of TBA in wells MW-1R (5.8 pg/l), MW-2 (130 µg11), and MW-5 (370 gg/l) and TAME in wells MW-1R (0.67 µg/l), MW-2 (23 gg/]), and MW-5 (13 ggll). The next quarterly groundwater sampling is scheduled for the Fourth Quarter of 2003. ' 4.1 Recommendations The compounds 1,2-DCA and EDB have never been detected in groundwater samples collected at this site for the past two years. Based on these results, ATC recommends that future laboratory analysis for these analytes be discontinued. ' Quarterly GW Monitoring Report-3ro Qtr 2003 NVATC Quik Slop No. 132 Quik Stop Markets, Inc. t JAPROJECTSMIK STOP UKTMS 132vtepoes%2DD 3b OirmMpµ ATC Project No.75.62503.3204 November 6,2003 Page 2 of 3