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1 <br /> 3rd Quarter 1995,Quarterly Monitoring Report <br /> Former PureGroBrea Facility <br /> 1905 North Broadway Avenue,Stockton,.CaIifornia <br /> Sierra-Pacific Project No.94.055.04 <br /> Nitrate (as NO3) concentrations, ranging from 39 to 110 mg/f N, were detected in water <br /> samples from each of the Broadway Avenue monitoring wells, including the up-gradient well <br /> (MW-3). Monitoring wells MW-2, MW-4, and MW-5 showed increases in nitrogen <br /> concentrations compared to second quarter 1995. Nitrate results shown in Table 3 have been <br /> converted to nitrogen-as-nitrate (N-NO3). Concentrations of 0.22, 13, and 0.23 mg/f TKN were <br /> _- detected in samples from MW-1, MW-2 and MW-3, respectively. A duplicate water sample <br /> from MW-1 reportedly was non-detect for TKN. <br /> Ground-water samples from well MW-11 contained 18 mg/f nitrates, and no TKN was detected. <br /> No volatile halogenated or petroleum hydrocarbons were detected in water samples from MW- <br /> 11 (Appendix C). <br /> • 3.2 Level Data and Predicted Flow Directions <br /> Water level data from earlier measurements indicate that near-surface ground-water levels in <br /> east Stockton rose dramatically in response to heavy winter precipitation during the period from <br /> f 30 December 1994 to 31 March 1995. Water level data since March 1995 have indicated near- <br /> surface ground-water levels have fallen in all wells (Table 1). The potentiometric surface has <br />[ fallen 8.22 feet at MW-1, 5.77 feet at MW-2, 7.21 feet at MW-3, 3.09 feet at MW-4, 1.06 feet <br /> L at MW-5, and 2.85 feet at MW-6 since March 31, 1995 (Figure 3). The flow direction shifted <br /> from S 220 W to S 28°W during the same period. In September 1995, the potentiometric slope <br /> was recalculated using water levels at MW-1, MW-3 (on-site wells) and MW-5 (off-site well). <br /> The calculated gradient was 0.0044 ft/ft. <br /> September 1995 water level measurements indicate that the potentiometric surface is falling, <br /> and flow direction is shifting westward. Ground water was flowing S 28° W on September 18, . <br /> 1995, with a gradient of about 0.44 feet vertically per 100 feet horizontally (Tables 1 and 2). <br /> Sierra-Pati Groundwater Consultants- 4 <br /> .fes - <br /> r _ <br />