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MCKGROUND MW-2, with the greatest benzene concentrations detected in groundwater samples reflected from well MW-7. In October 1991, slug was were conducted in wells MW-4, MW-h, and MW-g to evaluate hydraulic Program" of the aguifr. I lydraulic conductivity (K) was calculated using the Uo ever and Rice method for each well. The K values rmnge from 0.00147 m 0.0021y feet per minute and am representative ofsibs and silty sand. In November 1991, a tidal innuence study was conducted on well MW-4 to evaluate tidal fluctuations in the Port of Stockton. Depth to watermeasurcmerm collected fiom M W-4 over a 4.5 Imur period documented a 0.1 trot increase in the groundwater elevation. In April 1993, another tidal study was conducted by measuring depth to water in wells MW-4, M W-5, M W-b, M W-] and M W-g over a 5.5 hour period were maximum difference in tidal stage at the Port of Stockton. The groundwater elevation did not change in any of the wells will, the exception m-MW-fi where a OD2 fool increase in elevation was observed. In July 1995, groundwater monitoring wells M W-2A and MW-3A were installed In replace wells M W-2 and MW-3 which went dry due to a drop in the regional groundwater table. In addition to installing the deeper wells, monitoring well MW-3 was abandoned. During the installation of monitoring well M W-2A, free product was observed in mil samples, and a sham was observed is groundwater samples. Petroleum hydrocarlmna were not detected in mil or groundwater samples collected from monitoring well MW-3A. In August 19%, groundwater monitoring well MW-9 wars installed in the parking lot acmes Washington Street and mush of the former USTs to assess groundwater conditions upgradient of well MW-2A. Soil boring HH-13 was drilled adjacent to MW-2A to assess the vertical extent of soil comamthation below the groundwater table. The work was conducted in response to rcquess from the San Joaquin County Public Health, Environmental Health Division (EHD). San Joaquin County Capital Projects and the POD agreed that one year of quarterly groundwater monitoring would be performed, followed by preparation of Corrective Action Plan (CAP).