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3.0 LABORATORY ANALYSIS The groundwater samples were transported to Severn Trent Laboratories, Inc. (STL), a state-certified laboratory, located in Pleasanton, California. The groundwater samples were analyzed in accordance with San Joaquin County Environmental Health Department's March 2004 letter as follows: ■ Wells MW-IR, MW-9 and MW-10 were analyzed for the presence of MTBE by Method 826013; ■ Wells MW-2 and MW-5 were analyzed for the presence of MTBE, TAME, and TBA by Method 8260B; ■ Well MW-4 was analyzed for TPH-G (by Method'8015B), BTEX (Method 8021B) as wells as for MTBE(by Methods 8015B-8021 B); Copies of the laboratory analytical report and chain of custody record are provided in Appendix C. 4.0 SUMMARY OF RESULTS Based on groundwater elevation data for March/42005 the groundwater flow direction in both the upper and lower aquifers was towards the southeast at gradients of approximately 0.006 feet per foot (ft/ft) and 0.002 ftlft, respectively (Figures 3 and 4). The groundwater flow directions and gradients noted during this sampling event are consistent with historical trends. •r TPH-G was analyzed only in MW-4 which samples the lower aquifer;the results were non-detect. BTEX compounds were sampled in MW-4; only toluene was found above the detection limits (concentration.of 68 µg/L). MTBE was reported in groundwater samples collected from upper aquifer well MW-5 at a concentration of 190 µg/L. MTBE was also reported in lower aquifer wells MW-1R and MW-2 at concentrations of 1.5 µg/L, 130 µg/L, respectively. Figures 5 and 6 provide maps of TPH-G, benzene and MTBE concentration distributions in site wells based on the March 14, 2005 sampling event. J ,M $14'o,� The fuel oxygenate TAME was not detected in groundwater samples collected from any of the monitoring wells sampled this quarter. However, TBA was reported in groundwater samples collected from well�` and MW-5 at concentrations of 1 µg/L and 110 µglL, ray. Both TBA and MTBE concentrations in water samples from MW-5 have trended downward significantly during between 2004 and 2005. However, MW-2 has shown a slight increase in MTBE since the last sampling event in December 2004. Cumulative analytical results of groundwater samples collected from current and past sampling events are presented in Tables 1 and 2. Well construction details are provided in Table 3. Quarterly GW Monitoring Report-1st Qtr 2005 MATC Quik Stop No. 132 Quik Stop Markets, Inc. ATC Project No.75.62503.3205 April 11,2005 Page 2 of 4