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i Current Phase of Project Monitoring/Assessment Frequency of Groundwater Sampling Wells MW-1 through MW-6= Quarterly Frequency of Groundwater Monitoring Quarters Sampling Date December 30, 1998 Is Free Product (FP) Present on Site No FP Recovered this Quarter NA Cumulative FP Recovered to Date NA Approximate Depth to Groundwater 25 91 to 27 47 Direction of Groundwater Flow Southeast Groundwater Gradient 0 003 ft/ft DISCUSSION Results of this monitoring event indicate that the levels of dissolved hydrocarbons in wells MW-1 through MW-3, MW-5, and MW-6 are generally consistent with levels detected in previous sampling events, with the exception of wells MW-1 and MW-5 Concentrations of total xylenes were below laboratory detection limits for well MW-1 and decreased to 0 629 micrograms per Liter (jig/L) for well MW-5 The groundwater flow direction (southeast) and gradient were generally consistent with previous sampling events • Groundwater elevation increased 2 13 feet in the wells from the previous sampling event (September 1998) No-purge samples collected from vapor wells VW-1 through VW-4 indicate that the levels of dissolved hydrocarbons were generally consistent with levels detected in the previous sampling event, with the exception of wells VW-1 and VW-4 Concentrations of toluene for well VW-1, and benzene and ethylbenzene for well VW-4 were below laboratory detection limits Toluene was detected at a concentration of 0 562 µg/L in well VW-4 which is slightly above the laboratory detection limit ATTACHMENTS • Table 1 Groundwater Monitoring Data • Table 2 Groundwater Analytical Results for Oxygenates (USEwPA Method 8260) • Figure 1 Groundwater Analytical Summary (Fourth Quarter 1998) • Figure 2 Groundwater Contour Map (Fourth Quarter 1998) • Appendix A Sampling and Analysis Procedures • Appendix B Laboratory Analysis Reports and Chain-of-Custody Records • Appendix C Field Data Sheets CKE 1ARC0\054810TRLY10548Q498 DOC-9811sg 1 ��