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�1 2 . 0 GROUNDWATER FLOW DIRECTION AND GRADIENT On January 31, 2001, ASE associate geologist Ian Reed measured the depth to water in five (5) site groundwater monitoring wells using an electric water level sounder The surface of the groundwater was also checked f o r the presence of free-floating hydrocarbons or sheen No free-floating hydrocarbons or sheen were observed in any of the site groundwater monitoring wells Groundwater elevation data is presented as Table One A groundwater potentiometric surface map is presented as Figure 2 The groundwater flow direction is to the northwest with a gradient of approximately 0 005 ft/ft This gradient and flow direction is consistent with previous findings 3 . 0 GROUNDWATER SAMPLE COLLECTION AND ANALYSIS Prior to sampling, each monitoring well was purged of four well casing volumes of groundwater using dedicated bailers The parameters pH, temperature, and conductivity were monitored during the well purging Samples were not collected until these parameters stabilized Groundwater samples were collected from each well using dedicated polyethylene bailers The samples were decanted from the bailers into 40-m1 volatile organic analysis (VOA) vials, pre-preserved with hydrochloric acid The samples were capped without headspace, labeled and placed in a cooler with wet ice for transport to Kiff Analytical, LLC of Davis, California (FLAP #2 2 3 6) under appropriate chain-of-custody documentation Well sampling field logs are presented in Appendix A The groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPH-G), benzene, toluene, ethyl benzene, a n d total xylenes (collectively known as BTEX), fuel oxygenates, lead scavengers, and alcohols by EPA Method 8260 The analytical results for this and previous sampling periods are presented in Table Two The certified analytical report and chain-of-custody documentation are included as Appendix B TPH-G, benzene, and MTBE isoconcentration maps are presented at Figures 3, 4, and 5, respective 4.0 CONCLUSIONS The groundwater samples collected from monitoring well MW-1 contained 150 parts per billion (ppb) methyl-tertiary-butyl ether (MTBE) and 23 p p b Singh's Unical Service Station Quarterly Report - January 2001 Sampling -2-