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GROUND WATER MONITORING REPORT FIRST QUARTER 1994 Montgomery Ward Auto Service Center ' 5400 Pacific Avenue Stockton, California 1.0 INTRODUCTION This document constitutes the first quarter 1994 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 January 1994 through March 1994 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 FIELD INVESTIGATION 2 1 GROUND WATER ELEVATION SURVEY On March 29, 1994, 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 the four wells (MW-10, MW- 11, MW-12 and MW-13) located at the Unocal Corporation site (see Figure 2) No free- product was detected in any of these six 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 construct a ground water elevation map (see Figure 2) The data show that, at the tune of measurement, the predominant direction of ground water flow was easterly This represents a change from the previous quarterly monitoring periods where the direction of ground water flow was reported to be southerly 2 2 GROUND WATER SAMPLING - On March 29, 1994, ground water samples were collected from the two Montgomery Ward wells for analytical testing 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 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 lust 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 Project No 1232 1 ENVIRONMENTAL AUDIT, INC