ARCHIVED REPORTS_XR0002878 - Laserfiche WebLink

Home Browse Search

5 i 4. SUMMARY OF RESULTS A summary of the analytical results from current and past well sampling is presented in Table 1. Based on the water-level data for June 7, 1999, ATC Associates Inc. has interpreted the groundwater gradient and 1 flow directions for the upper aquifer, as shown on Figure 3. In the local upper aquifer (Monitoring Wells MW-5, MW-6 and MW-7), the groundwater level increased from the previous quarter an average of 0.39 feet, ranging from 0.28 feet in Monitoring Well MW-7, to 0.45 feet in Monitoring Well MW-6. The apparent groundwater flow direction in the local upper was southeasterly at a gradient of approximately ' 0.0037 (Figure 3). ' Based on the water-level data for June 7, 1999 (Table 1), ATC Associates Inc. has interpreted the groundwater gradient and flow directions for the lower aquifer, as shown on Figure 4. In the local lower aquifer (Monitoring Wells MW-1R, MW-2, MW-3 and MW4), the groundwater level increased from the ' previous quarter an average of 0.45 feet, ranging from 0.41 feet in Monitoring Well MW4 to 0.54 feet in Monitoring Well MW-3. The apparent groundwater flow direction in the local lower aquifer was ' southeasterly at a gradient of approximately 0.0037 (Figure 4). Laboratory analysis of the water sample collected on June 7, 1999 indicates that TPH-G and BTEX were not detected in groundwater samples collected from Monitoring Wells MW-1R, MW-3, MW-6, and MW- 7. TPH-G was detected in MW-2 and MW-5. Xylenes were only detected in Monitoring well MW4. ' Laboratory results of fuel oxygenate compounds by EPA Method 8260 indicates that MTBE was detected in the groundwater samples collected from Monitoring Wells MW-1R [100 micrograms per liter (ug/L)], ` MW-2 (8,400 ug/L), and MW-5 (2,900 ug/L). The water sample collected from Monitoring WeII MW-2 was analyzed for fuel oxygenates by EPA Method 8260 at two dilutions. The analytical results for the first dilution of 1:10 showed 5,200 (E) ug/L of MTBE, which exceeded the instrument calibration range, and 110 ug/L of TAME. The sample was then diluted to a 1:50 ratio and re-analyzed, showing a concentration ' of 8,400 ug/L of MTBE and non-detectable concentrations for the other oxygenates (detection limit 250 ug/L). Table 2 summarizes the quantifiable results of these two dilutions: the lowest values within the calibration range of the first dilution and the MTBE result from the second dilution is reported. TBA, DIPE, and ETBE were not detected in any of the groundwater samples. The next quarterly groundwater sampling is scheduled for the third quarter of 1999. 1 1999 Second Quarter Groundwater Monitoring Repon HALEHRMAMQUIKS'I 8132\99rpt-2nd.docjAugua30.3999] 1