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DISCUSSION <br /> • Results of this monitoring event indicate that concentrations of dissolved gasoline hydrocarbons in wells <br /> MW-1 through MW-7 and MW-10 are generally consistent with results from previous sampling events <br /> The highest levels of TPHG and benzene, were detected in MW-2 at concentrations of 435 µg/l and 33 <br /> pg/I, respectively As in previous quarters, no constituents were detected in wells MW-3, MW-4, and <br /> MW-7 <br /> Oxygenates, TBA, MTBE, DIPS, ETBE, and TAME were analyzed in samples collected from groundwater <br /> monitoring wells MW-1 through MW-7, and MW-10 using USEPA Method 8260 MTBE was detected only <br /> in MW-2 at a concentrations of 6 3 µg11, within the range of previous sampling results MTBE was not <br /> detected in MW-5 after being detected the previous eight quarters No other oxygenates were detected in <br /> the wells <br /> The groundwater gradient (0 0015) and direction of groundwater flow (east-northeast) were generally <br /> consistent with previous data Groundwater elevation decreased an average of approximately 2 56 feet <br /> from the previous sampling event(March 2000) <br /> The soil vapor extraction system has not been operational since November 1987 Inspection of the <br /> system in June, 2000 indicates that the heating coil needs replacement <br /> ATTACHMENTS <br /> • Table 1 Groundwater Monitoring Data <br /> • Table 2 Groundwater Analytical Results for Oxygenates <br /> • Table 3 Operational Uptime Information of the Soil Vapor Extraction System <br /> • Table 4 Flow Rates and Results of Air Sample Analyses <br /> . • Table 5 Extraction and Emission Rates <br /> • Table 6 Air Sparge and Air Bubbling Flow Rates and Dissolved Oxygen Levels <br /> • Figure 1 Site Location Map <br /> • Figure 2 Groundwater Elevation Contours (Second Quarter 2000) <br /> • Figure 3 Groundwater Analytical Summary (Second Quarter 2000) <br /> • Appendix A Sampling and Analysis Procedures <br /> • Appendix B Chain-of-Custody Records and Laboratory Analysis Records <br /> • Appendix C Operation and Maintenance and Groundwater Monitoring Field Data Sheets <br /> C IARC0121301QT'RLY1200012130g200 doe Delta <br /> 09/19/00 <br />