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Report on Soil and Ground-Water Evaluation September 11, 1989 Proposed ARCO Station, Woodbridge, California AGS 39044-1 Well Development and Ground-Water Samplins On June 20, 1988, a geologist from Applied GeoSystems was at the site to measure depths to water in the monitoring wells, subjectively analyze the ground water in these wells, and develop the wells. Following initial water-level measurements, the water in the wells was subjectively examined by lowering approximately half the length of a clean Teflon-bailer past the air-water interface to obtain a sample. Any subjective evidence of product detected in the wells was recorded. No floating product or sheen was observed in the wells at that time. The monitoring wells were developed -using a 4-inch-diameter PVC surge block alternately raised and lowered through the water.column in each well. Following surging, the wells were pumped using an air-lift pump to remove excess sediment from the wells. As required by SJLHD guidelines, the wells were not purged or sampled until a minimum of 24 hours had passed after development. On June 22, 1989, our geologist returned to the site to purge and sample the monitoring wells. Water level measurement and subjective-analyses were performed on the wells as described above. _No subjective evidence of hydrocarbon contamination was observed in the monitoring wells. The wells were .purged of approximately four volumes of water using a stainless steel helical rotor, electric submersible pump. During purging, well discharge was monitored for pH, temperature, and conductivity. Stabilization of these parameters was used to indicate that formation water was entering the well. Water purged from the wells r 15 Apn/ied GeoSystems