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' QUARTERLY GROUND WATER MONITORING Site Code 2163 Montgornery Ward Auto Service Center 5400 Pacific Avenue, Stockton CA ' 1.0 INTRODUCTION / This document constitutes the fourth quarter (October through December) 1995 ground water ' monitoring report for the Montgomery Ward Auto Service Center property located at 5400 Pacific Avenue, Stockton, California (Site) (see Figure 1) The quarterly ground water monitoring and sampling is being conducted in accordance with a request from the San Joaquin ' County Public Health Services Department (County) As requested by the County, the gauging and sampling activities at the Montgomery Ward site ' occurred on the same day that wells were gauged and sampled at the former Unocal service station located at 5606 Pacific Avenue, Stockton, California 2.0 FIELD INVESTIGATION 21 GROUND WATER ELEVATION SURVEY On December 19, 1995, prior to purging or sampling activities, depth measurements to fluid levels were obtained using an interface probe accurate to 0 01 foot from wells MW-1 through MW-6 located on the Montgomery Ward site (see Figure 2 and Table 1) Table 1 also contains well gauging information from wells MW-10 through MW-17 located at the former Unocal site (see Figure 2) No free-product was detected in the Montgomery Ward wells, and no free- product was reported in wells associated with the former Unocal site (see Table 1) The water level measurement for each well was converted to mean sea level (MSL) datum by subtracting the measured water level for each well from its respective "top of well casing elevation" datum (see Table 1) The data in Table 1 were used to construct a ground water elevation map (see Figure 2) ' 22 2 GROUND WATER SAMPLING On December 19, 1995, ground water samples were collected for analytical testing from wells MW-1 through MW-6 located on the Montgomery Ward site Prior to sampling, the wells were purged using a Grundfos MP-1 submersible pump Temperature, conductivity, pH, and turbidity were recorded to evaluate the effectiveness of I purging activities (see Appendix A) The wells were sampled in the order that purging activities were completed Water samples were collected from each well from just below the Xvater surface using Voss Technologies disposable bottom bailers equipped with volatile organic compound samplers The use of these bailers precludes the potential for cross-contamination Mr Michael Infuma of the County was on-site during the onset of purging and sampling activities ■ Each water sample was sealed in four 40-milliliter volatile organic analysis (VOA) vials with Teflon septa lined lids The VOA vials were completely filled so that no head space existed between the sample and the lids The samples were labeled with the sample point identification preservative added, if any, date, time and Environmental Audit, Inc (EAI) project number and immediately placed into an ice chest chilled using frozen blue and crushed ice All samples were . logged on a chain of custody record form (see Appendix B) IProject No 1232 1 ENVIRONMENTAL AUDIT, INC