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QUARTERLY GROUNDWATER MONITORING MARCH 10 1998 WEGE and Lawrence Tank Testing (LTT) collected quarterly groundwater samples from the three monitor wells at the site on March 10, 1998 See Appendix A for QA/QC, details, methods, procedures, abbreviations, and acronyms used in sampling and analysis DEPTH TO WATER MEASUREMENTS WEGE measured depth to water at all wells on March 10, 1998 The measurements were made from the surveyed elevation at the top of casing at each well using an electrical air/water interface probe (Table 1) No free product or product sheen was observed in any of the monitor wells COLLECTION AND CERTIFIED ANALYSIS OF GROUNDWATER SAMPLES Following depth to water measurements, Lawrence Tank Testing (LTT) purged three well volumes of water from each well using a truck mounted vacuum lift pump and dedicated one inch diameter PVC tubing The purged wastewater was temporarily contained on-site in labeled 55 gallon DOT approved drums Evergreen Environmental Services transported this wastewater to their recycling center under a non-hazardous manifest on April 3, 1998 (see Appendix D) After purging, the wells were allowed to recover to at least 80% of their original well volumes A groundwater sample was then collected from each well with a disposable polyethylene bailer and decanted with no head space into four 40 ml VOA vials containing 0 5 ml HCL acid as a preservative The samples were delivered with accompanying chain of custody documentation to Amencan Environmental Network (DHS Certification 41172) The certified laboratory analyzed the water samples from each monitor well for concentrations of TPH-G, BTEX, and the oxygenants TBA, DIPS, ETBE, TAME, and MTBE (see Appendix A for methods) GROUNDWATER GRADIENT AND FLOW DIRECTION Figure 4 shows the groundwater elevation gradient and flow direction determined from depth to water measurements at the three on-site monitor wells on March 10, 1998 The groundwater elevation has increased by an average of 4 27 feet at the three monitor wells since the previous quarterly monitoring round on September 4, 1997 The flow direction is to the east The overall gradient is 0 003 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 March 10, 1998 are shown in Table I Copies of the laboratory reports are included as Appendix C of this report TPH-G concentrations ranged from a maximum of 4,400 ug/l at the downgradient monitor well MW2 to 2, 400 ug/l at the upgradient monitor well MW1 Benzene concentrations ranged from a maximum of 1300 ug/l at MW2 to 740 ug/l at MWI MTBE concentrations ranged from a maximum of 7 ugll in MW3 to less than laboratory detection limits of 30 ug/l in the remaining two monitor wells The remaining four oxygenants did not show concentrations above laboratory detection limits in any of the three samples from the monitor wells 2 ARC- QM 3-98