Laserfiche WebLink
IF" ITASCK <br /> Denver, Inc. <br /> 4.2 RESULTS <br /> A statistical summary of the HCT effluent water quality is provided in Table 4-1, laboratory reports <br /> are provided in Appendix B, and the full results are tabulated in Appendix C. Additionally, the <br /> concentrations of selected analytes and calculated values over time are plotted in Figures 4-1a <br /> through 4-1i, and plots of each analyte over time are provided in Appendix D. <br /> Samples B2, B3, and AP7 produced circumneutral leachate throughout humidity-cell testing <br /> (Figure 4-1g). Samples PP2 and PP4 produced leachate with pH values that ranged from <br /> approximately 5.8 to 7.0. The deionized water added to the samples had pH values between 5.0 <br /> and 6.0, as indicated by the analyses of the blank sample. Thus,the pH of the HCT leachate from <br /> samples PP2 and PP4 is higher than the pH of the HCT influent water, and it is apparent that the <br /> samples did not contribute acidity to the HCT leachate. Leachate from B5 generally had pH values <br /> between 5.0 and 6.0, and leachate from samples B7, B8, and B12 was generally between pH 4.0 <br /> and 5.0. Samples L2 and PP6 had pH values of approximately 4.3 at the beginning of testing, and <br /> approximately 3.6 at the end of testing. Sample PC3 had the lowest pH value during each week <br /> of testing, ranging from 3.3 to 3.9. <br /> As shown in Figure 4-1a through 4-1h, each HCT showed a "first flush," or elevated <br /> concentrations of most solutes during the first week to approximately five weeks of testing. This <br /> behavior is considered indicative of readily soluble material being released from the samples, <br /> and is not representative of their long-term solute leaching behavior. Samples AP7, B2, B3, PP2, <br /> and PP4 all had first flushes of alkalinity, but B2 was the only sample with consistently detectable <br /> levels of alkalinity (Figure 4-1b). In addition to a first flush, some HCTs had elevated solute <br /> concentrations in later weeks as well. For example, Figures 4-1a and 4-1h show that acidity and <br /> sulfate in leachate from samples L2 and PP6 were elevated between weeks 20 and 45 as well. <br /> Figure 4-1i shows the ratio of sulfate to acidity for the acidic HCTs over time. The ratio of sulfate <br /> to acidity for theoretical pyrite oxidation (Equation 3.1) is 1.0, and for theoretical acid-sulfate <br /> 26 <br />