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Table 4. Characterization of Untreated MW-3 Groundwater. <br /> Analyte Units MW-3 <br /> Chromtum <br /> Hexavalent gg/L 4,200 <br /> Total gg/L 6,300 <br /> Alkalinity m /L CaCO3 250 <br /> Metals <br /> Arsenic gg/L < 5 <br /> Copper gg& < 10 <br /> Iron, Total gg/L 2,600 <br /> Iron, Dissolved gg/L 2,400 <br /> Manganese, Total gg/L < 10 <br /> Man anese, Dissolved gg/L <5 <br /> Zinc gg/L < 100 <br /> Nitrogen <br /> Ammonia, total mg/L N < 0 1 <br /> Nitrate mg/L N 35 <br /> ORP mV 314 <br /> pH pH units 734 <br /> TOC mg/L 1 3 <br /> 3.3 Effect of Treatment on Secondary Water Quality <br /> The effect of each reducing agent on secondary water quality parameters is illustrated in <br /> Table 5 Neither reducing agent had a significant effect on dissolved oxygen, methane, <br /> arsenic, copper, zinc, nitrogen (ammonia and nitrate), temperature, or total organic <br /> carbon As expected, treatment with Fe(II) increased conductivity, the concentrations of <br /> dissolved iron and sulfate, and decreased the pH The decrease in pH was mitigated in <br /> the tests using soil due to the natural buffering capacity of the soil Alkalinity decreased <br /> in the tests using groundwater only due to the drop in pH <br /> The concentration of manganese (Mn) increased in the groundwater only tests using <br /> Fe(II) Specifically, the concentration increased to 76 µg/L in the GW Low Fe test and <br /> 140 gg/L in the GW High Fe test Since the concentration of Mn doubled as the <br /> concentration of Fe(H) doubled, and since Mn did not change in the groundwater tests <br /> using Cascade°, the Mn in the groundwater only tests using Fe(H) is probably due to <br /> impurities naturally present in the iron <br /> The concentration of dissolved Mn increased significantly in all of the tests using soil <br /> This may have been due to the reduction of manganese dioxide, which is naturally <br /> present in many soils (though its presence in this soil was not ascertained) The increase <br /> in dissolved Mn was greater in the Fe(II) tests than in the Cascade° tests, possibly, due to <br /> the initially low pH in the Fe(II) tests Evaluation of the long-term fate of the manganese <br /> generated in these tests was beyond this Scope of Work <br /> PRIMA Environmental S Eval of Reductants <br /> January 19,2005 ATC-Diamond Walnut <br />