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li <br /> Current Phase of Project: Monitoring <br /> Frequency of Groundwater Sampling: MW-1 through MW-4, and VW-3= Quarterly <br /> Frequency of Groundwater Monitoring: Quarterly <br /> Sample Date: September 21, 1998 <br /> Is Free Product (FP) Present on Site: No <br /> FP Recovered this Quarter: NA <br /> Cumulative FP Recovered to Date: NA _ <br /> Approximate Depth to Groundwater: 38.67 to 40.31 <br /> Direction of Groundwater Flow: East-Northeast <br /> Groundwater Gradient: 0.003 <br /> DISCUSSION: <br /> Groundwater samples were analyzed for TPHG, BTEX, and the oxygenates tertiary butanol, MTBE, DIPE, <br /> ETBE, and TAME. Results of this monitoring event indicated that dissolved gasoline hydrocarbons were <br /> generally consistent with previous monitoring events, with the exception of well VW-3. Well VW-3 contained <br /> an MTBE concentration of 15.9 micrograms per liter (µg/L), using USEPA Method 8020. The groundwater <br /> gradient and direction of groundwater flow (east-northeast) were generally consistent with the previous <br /> sampling events. Groundwater elevation decreased 3.57 feet from the previous sampling event (June <br /> 1998). <br /> Groundwater samples were also analyzed for the oxygenates tertiary butanol, MTBE, di-isopropyl ether, <br /> ethyl tertiary butyl ether, and tertiary amyl methyl ether using USEPA Method 8260. MTBE was detected in <br /> wells MW-1 and VW-3 at concentrations of 138 tcg/L and 23.5 gg/L, respectively. MTBE by USEPA Method <br /> 8260 was below laboratory detection limits for wells MW-2, MW-3, and MW-4. In addition, tertiary butanol <br /> was detected at a concentration of 310 µg/L in well VW-3. All other oxygenates were below laboratory <br /> detection limits for all wells. <br /> ATTACHMENTS: <br /> • Table 1 Groundwater Monitoring Data <br /> • Table 2 Groundwater Analytical Results for Oxygenates <br /> • Figure 1 Site Location Map <br /> • Figure 2 Groundwater Analytical Summary (Third Quarter 1998) <br /> • Figure 3 Groundwater Elevation Contours (Third Quarter 1998) <br /> • Appendix A Sampling and Analysis Procedures <br /> • Appendix B Laboratory Analysis Reports and Chain-of-Custody Records <br /> • Appendix C Field Data Sheets <br /> i <br /> CP\D:%QMRI3RDQTR--112186Q398.DOC-98\???:1 <br /> Rev.11/30/98 <br />