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DISCUSSION <br /> Results of this monitoring event indicate that concentrations of dissolved gasoline hydrocarbons <br /> decreased in well MW-5 since the previous sampling event The levels of dissolved hydrocarbons in <br /> wells MW-1 through MW-4 are generally consistent with levels detected in previous sampling events <br /> The groundwater flow direction (east) and gradient were generally consistent with previous sampling <br /> events Groundwater elevation increased 0 25 foot in the wells from the previous sampling-event <br /> (August 1997) <br /> Per ARCO's request, oxygenates tertiary butanol, methyl tertiary butylether (MTBE), di-isopropyl ether, <br /> ethyl tertiary butyl ether, and tertiary amyl methyl ether were analyzed using U S Environmental <br /> Protection Agency Method 8260 for the two monitoring wells with the highest concentrations of total <br /> petroleum hydrocarbons as gasoline, benzene, toluene, ethylbenzene, and total xylenes, and MTBE <br /> EMCON evaluated third quarter data and selected wells MW-1 and MW-5 to be analyzed for these <br /> oxygenates Wells MW-1 and MW-5 contained 3 6 and 24 micrograms per liter of MTBE, respectively <br /> No other oxygenates were detected in the samples from wells MW-1 and MW-5 (see Table 2) <br /> ATTACHMENTS. <br /> • Table 1 Groundwater Monitoring Data <br /> • Table 2 Additional Groundwater Analytical Data <br /> • Figure 1 Site Vicinity Map <br /> • Figure 2 Generalized Site Plan <br /> • Figure 3 Groundwater Contour Map (November 18, 1997) <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 /> cc Elizabeth Thayer, California Regional Water Quality Control Board <br /> Will Smith, Lincoln Properties <br /> SAON\PJM805\0805 L 400 7D8-98\pzusmer 1 <br />