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i GROUNDWATER GRADIENT AND FLOW DIRECTION Fi4`ure 4 shows the groundwater elevation gradient and flow direction determined from depth to water measurements at the three on-site monitor wells on September 27, 2000 The groundwater elevation has decreased by an average of 1 3 feet at the three monitor v,ells since the previous quarterly monitoring round on June 8, 2000 The flow direction is to the west-northwest The overall gradient is 0 001 feet/linear foot RESULTS OF CERTIFIED ANALYSIS OF GROUNDWATER SAMPLES The results of the certified analyses of groundwater samples collected from the three monitor wells on September 27, 2400 are shown in Table 1 Copies of the laboratory reports are included as Appendix C of this report TPH-G concentrations ranged from a maximum of 16000 ug/l at monitor well MW 1 to 4200 u,,/l at monitor well MW2 Benzene concentrations ranged from a maximum of 7000 ug/1 at NM to 540 ug/l at MW2 MTBE concentrations ranged from a maximum of 67 ug/1 at MW3 to 25 ug/1 at MW2 • Neither 1,2 dichloroethane nor dibromoethane were detected in any of the three groundwater samples from MW1, MW2, or NIW3 Figure 5 shows the distribution of TPH-G, BTEX, and MTBE in groundwater and the estimated lateral limits of the TPH-G in groundwater as determined from groundwater _ samples collected on September 27, 2000 The decrease in overall groundwater elevation since the previous quarterly monitoring round was accompanied by an increase in TPH- G, BTEX, and MTBE concentrations at the three monitor wells RECOMMENDATIONS 1) Implement September 28, 1999 workplan to install additional groundwater monitoring wells following pre-approval of costs by the UST Cleanup Fund 2) Re-survey monitor well casing elevations at MWI, MW2, and MW3 following installation of additional monitoring wells to insure proper determination of groundwater gradient and flow direction s 3 Arc Pump QM 7-9, 2000