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5 <br /> 4. SUMMARY 4F RESULTS <br /> A summary of the analytical results from current and past well sampling is presented in Table 1. Based <br /> a' on the water-level data for March 17, 1999, ATC Associates Inc. has interpreted the groundwater gradient <br /> and flow directions for the upper aquifer, as shown on Figure 3. In the local upper aquifer (Monitoring <br /> Wells MW-5, MW-6 and MW-7), the groundwater level increased from the previous quarter an average of <br /> 0.61 feet, ranging from 0.59 feet in Monitoring Wells MW-6 and MW-7, to 0.64 feet in Monitoring Well <br /> MW-5. - The apparent groundwater flow direction in the local upper aquifer has changed from <br /> southeasterly last quarter to northeasterly this quarter at a gradient of approximately 0.0014 (Figure 3). <br /> The change may be due to increased water levels in the nearby slough to the west of the site. <br /> Based on the water-level data for March 17, 1999 (Table 1), ATC Associates Inc. has interpreted the <br /> groundwater gradient and flow directions for the lower aquifer, as shown on Figure 4. In the local lower <br /> aquifer (Monitoring Wells MW-1R, MW-2, MW-3 and MW-4), the groundwater level increased from the <br /> previous quarter an average of 0.64 feet, ranging from 0.62 feet in Monitoring Well MW-4 to 0.65 feet in <br /> Monitoring Wells MW-1R, MW-2, and MW-3. The apparent groundwater flow direction in the local <br /> lower aquifer has changed from southeasterly last quarter to easterly this quarter at a gradient of <br /> approximately 0.0006 (Figure 4). <br /> Laboratory analysis of the water sample collected on March 17, 1999 indicates that TPH-G and BTEX <br /> were not detected in groundwater samples collected from Monitoring Wells MW-1R, MW-3, MW-4, <br /> ' MW-5, and MW-6. TPH-G was only detected in MW-2. Toluene and xylenes were only detected in <br /> Monitoring well MW-7. Laboratory results of fuel oxygenate compounds by EPA Method 8260 indicates <br /> that MTBE was detected in the groundwater samples collected from Monitoring Wells MW-1R [27 <br /> micrograms per liter(ug/L)], MW-2 (21,100 ug/L), and MW-5 (1,970 ug/L). TBA was detected in MW-2 <br /> ' (5,870 ug/L). TAME was detected in MW-2 (346 ug/L) and MW-5 (8.4 ug/L). DIPE and ETBE were not <br /> detected in any of the groundwater samples. The next quarterly groundwater sampling is scheduled for <br /> the second quarter of 1999. <br /> 1999 First Quarter Groundwater Monitoring Report <br /> `� %\PLEASANTONISHAREDU.ERRMAMQU1KSTOP1132199rpt-Ist.doe[]uty2.19991 <br />