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I QUARTERLY GROUND WATER MONITORING REPORT SECOND QUARTER 1993 Montgomery Ward Auto Service Center 5400 Pacific Avenue Stockton, California 1 ' 1.0 MMODUCTION ' This document constitutes a quarterly ground water monitoring report for the Montgomery Ward Auto Service Center property located at 5400 Pacific Avenue, Stockton, California (see Figure 1) for the period April 1993 through June 1993 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 Corporation gasoline station located at 5606 Pacific Avenue, Stockton, California ' 2.0 D WORK 2 1 GROUND WATER ELEVATION SURVEY On June 28, 1993, prior to purging or sampling activities, depth measurements to fluid levels were obtained using an interface probe accurate to 0 01 foot from the two wells (MW-1 and MW-2) located on the Montgomery Ward site and Unocal Corporation wells MW-6 MW- 10, MW-11, MW-12 and MW-13 located across Robinhood Drive (see Figure 2) No free- product was detected in any of these seven wells The water level measurements for each well were converted to mean sea level (MSL) datum by subtracting the measured water level for each well from the ground level datum (see Table 1) The data in Table 1 were used to f construct a ground water elevation map (see Figure 2) The data show that at the time of measurement, the predominant direction of ground water flow is south-southwest ? ' 2 2 GROUND WATER SAMPLING On June 28, 1993, ground water samples were collected from the two Montgomery Ward wells for analytical testing Prior to sampling, the wells werepurgead using a Grundfos ' MP-1 submersible pump Temperature, conductivity, pH and tui rd6 rry were recorded to evaluate the effectiveness of 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 water 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 Infurna of the County was on-site during purging and sampling activities Each water sample was sealed in five 40-milliliter (ml) VOA vials with Teflon septa lined lids The 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 ' Project No 1232 1 ENVIRONMENTAL AUDIT,INC®