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n 11 W-2A, and W-2B. BTX were identified in ground w ter samples from all three monitoring wells (Table 2). Although monitoring wells W-2 a d W-2A are both screened across the water table, BTX in groundwater from monitoring 11 W-2 were significantly higher than in groundwater from monitoring well W-2A. The screened interval of monitoring well W-2 extends higher than the screened interval of monitoring well W-2A and thus is more accessible to hydrocarbons in the vadose zone. Depth to groundwater was approximately 55 feet below ground surface. Between May and July 1988, free product agai accumulated in monitoring well W-2 and to a lesser extent, in monitoring well W-3. Annour removed a total of 22 gallons of free product from monitoring wells W-2 and W-3 du 'ng this time period. In September and October 1988, BC began a program of quarterly groundwater sampling. Laboratory results of the first quarterly ampling identified BTX in all' on-site monitoring wells. No BTX were identified in an off-site monitoring wells (Table 2)_ BTX concentrations in monitoring well W-2 were again significantly higher than BTX concentrations in adjacent monitoring well W-2A. Depth to groundwater was approximately 59 feet below ground surface. A Progress Report was issued on November 8, 1988. The Progress Report described the results of the June 1988 work and the May thro gh July 1988 free product occurrence, and summarized information regarding dissolved product concentrations aridsoil contamination: The second (1988) occurrence off e product accumulation in monitoring wells W-2 and W-3, along with the discrepancy between BTX concentrations in groundwater from monitoring wells W-2 and W-2A pointed to hydrocarbon contamination of the vadose zone as an important continuing sourcc of hydrocarbons to the groundwater. To better characterize hydrocarbon occurrence in the vadose zone, BC developed a soil characterization work plan. Results from this investigation would aid ARCO in the design of a vadose zone remediation system. In November 1988, the work plan was submitted to the County and the Regional Board. As of March 1, 1989, ARCO has not yet received a written response to the soils charact rization work plan from the Regional Board. In December 1988, BC issued the first Quarterly Report describing the results of the September/October 1988 groundwater sampling. In January 1989, BC completed the second quarterly groundwater sampling. BTX were identified in groundwater samples from all on-site monitoring wells. Minor BTX concentrations were also identified in groundwater samples from off-site monitoring we is W-5 and W-6. No hydrocarbon constituents were identified in groundwater samples collected from off-site monitoring wells W-4 and W-7 (Table 2). Depth to groundwater w s approximately 57 feet below ground surface. The second Quarterly Report describin g the results of the January 1989 groundwater sampling was issued on February 23, 1989.