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Roberts. Gil Company May 23, 1988 Project No. 1628G Page 2 results suggested that ground -water contamination is probably of limited extent on the site. The April 1987 assessment work performed by the previous consultant indicated a ground -water flow direction toward the southeast. Monitoring wells MW -1 through MW -4 (installed by Kleinfelder and Associates), were measured for depth to water and free-floating product by Exceltech on March 31, 1988. The measuring devices (electronic measuring tape and clear acrylic bailer) were thoroughly cleaned with a tri -sodium phosphate solution and rinsed with distilled water between wells to prevent cross contamination. The depth to ground -water measurements were reduced to elevation data utilizing available survey information. Figure 2 presents the ground -water surface elevation contour data for the March 31, 1988 monitoring event. Floating product was observed in monitoring well MW -1, and as a result no ground -water sample was collected. Well MW -1 was purged of approximately 2 gallons of a diesel/water mixture. The purge water was placed in a 55 gallon drum and labeled accordingly. Field measurements indicate that well MW -1 is approximately 45 feet deep. Monitoring wells MW -2, MW -3, and MW -4 were sampled on March 31, 1988 and April 14, 1988. The April 5 sampling was performed in response to a request by the San Joaquin Local Health District (SJLHD). Each well was purged of at least four well -casing volumes of ground water to assure that the sample was representative of formation water. During this process the well water was monitored for pH, temperature, and specific conductance changes. The samples were collected with a nitrogen gas submersible bladder pump (March sampling) and a stainless steel bailer (April sampling). The sampling equipment was thoroughly cleaned prior to and between sampling events in a manner similar to that used for the ground -water measuring devices. Each ground -water sample was placed in the appropriate container for analysis of total volatile hydrocarbons as gasoline (TVH), total extractable hydrocarbons as diesel (TEH),