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Laboratory Analyses of Ground-Water Samples <br /> American Environmental Network, a State-certified analytical laboratory located in <br /> Pleasant Hill, California, analyzed the ground-water samples for total chromium by EPA <br /> Method 6010, hexavalent chromium by EPA Method 7196, and general minerals. The <br /> laboratory data reports are attached as Appendix A and field data sheets are attached in <br /> Appendix B. <br /> As shown in Table 1, neither total nor hexavalent chromium were detected in any of the <br /> ground-water samples (below a reporting limit of 10 ug/L). <br /> Table 1. Dissolved Chromium in Ground-Water Samples <br /> Well No. Total Chromium (mg/L) Hexavalent Chromium <br /> (mg/L) <br /> MW-5S < 0.01 < 0.01 <br /> MW-7S < 0.01 < 0.01 <br /> MW-10 < 0.01 < 0.01 <br /> MW_11 < 0.01 < 0.01 <br /> MW-12 < 0.01 < 0.01 <br /> CONCLUSIONS <br /> The data shown in Table 1 indicates that chromium in the brine solution has not <br /> adversely affected ground water beneath the suspected brine release area. The chromium <br /> analyses that WHF had performed on soil samples collected during the drilling of <br /> monitoring wells MW-10, MW-11, and MW-12 showed results that are consistent with <br /> this conclusion. As previously reported by WHF, six soil samples were collected from <br /> these borings, with total chromium concentrations ranging from 7.0 mg/kg to 11.8 <br /> mg/kg, which are within the typical background range expected (Scott, 1991). <br /> To confirm that chromium in the suspected brine release has not adversely affected <br /> ground water, Union Ice Company is planning to have wells MW-5S, MW-7S, MW-10, <br /> MW-11, and MW-12 re-sampled and analyzed for total and hexavalent chromium in early <br /> 1994, after the winter rains. If the results of that follow-up investigation confirm the <br /> findings reported here, we feel that the brine release matter at the Site should be closed. <br /> 3 <br />