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Mr. Kyle, Christie January 30, 1991 Page 5 installed bladder pumps driven by a portable control box and air compressor and were installed in each well to reduce the potential for cross-contamination and to simplify sampling procedures. A dedicated pump was not installed in monitoring well MW-4 du-, to lack of groundwater in the well. Prior to sample collection during the October groundwater sampling event, groundwater was purgf,d from each monitoring well by Brown and Caldwell Consultants personnel using the Well Wizards. The purged groundwater was stored in covered 55-gallon drums on-site. At the end of each sample event day,Armour Petroleum,Inc. (Armour) of Fairfield,California disposed of the groundwater. All of the water produced during the October groundwater sampling event was taken by Armour to the Solano County Fire Training Facility under bill of lading. While purging groundwater from each well, the pH, specific conductance, and volume of water purged was monitored. Table I represents this data. Approximately three well volumes of groundwater were evacuated from all sampled monitoring wells except W-2 and W-3. Due to slow recharge of groundwater into monitoring wells W-2 and W-3,2.28 and 0.8 well volumes,respectively, were evacuated from these wells. The wells were sampled using disposal polyvinyl chloride bailers equipped with bottom-emptying valves. The sample was drained directly from the bottom valve into four 40-milliliter glass bottles with teflon-lined septums. The samples were stored on ice from the time of collection through delivety to Brown and Caldwell's state-certified laboratory. Analytical Results Groundwater levels were measured at approximately 63 to 66 feet below ground surface in October 1990, and the groundwater flow direction was to the south to southwest under a hydraulic gradient of approximately 0.001. Dissolved BETX concentrations in groundwater samples collected during October 1990 are included in Table 2. October 1990 benzene concentrations are shown on Figure 3. Complete laboratory reports of the October 1990 groundwater sample analyses are enclosed as Appendix A. October 1990 analytical results show benzene concentrations in groundwater in monitoring wells W-lA, W-2, W-2B, W-3, W-6, W-7, W-9, W-10, and W-11 are greater than California Department of Health Services (DHS) Maximum Contaminant Level (MCL). DHS MCLs for benzene, ethylbenzene, and xylenes are 1.0 parts per billion (ppb), 680 ppb, and 1,750 ppb, respectively. The concentration of xylenes in g-o-indwater monitoring well W-2 was above tile DHS MCL and below the DHS MCLs J-i all other monitoring wells. Ethylbenzene concentrations in groundwater in all monitoring wells sampled were below the DHS MCLs. Toluene was identified in concentrations greater than the DHS drinking water action level (action level" in ---monitoring-wells-W-2,-W-3, and W-9. BETX concentrations were not identified in off-site monitoring wells W-5, W-8. and W-12.