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Frol—ITASCK <br /> Denver, Inc. <br /> environmental conditions of the site. Site-specific factors such as the ambient humidity, reactive <br /> surface area, water-to-rock ratio, and attenuation reactions may influence the analyte <br /> concentrations observed at the site relative to concentrations observed during laboratory <br /> testing. <br /> Six of the 12 samples had circumneutral pH, two were mildly acidic (i.e., pH between 5 and 6), <br /> and four samples (1312, L2, PC3, and PP6) were acidic with pH values less than 5.0. As shown in <br /> Figure 3-8, metal concentrations in MWMP leachate generally increase with decreasing pH. The <br /> Precambrian-biotite schist/gneiss sample PC3 generally had the highest solute concentrations of <br /> all the samples, with a total dissolved solids (TDS) concentration of 2,160 milligrams per liter <br /> (mg/L)and a sulfate concentration of 1,200 mg/L.The rest of the samples had TDS concentrations <br /> of approximately 600 mg/L or less. Solutes such as aluminum, cadmium, cobalt, fluoride, iron, <br /> manganese, nickel, sulfate, uranium, and zinc were elevated in samples with acidic pH relative to <br /> the circumneutral samples. <br /> 3.6 STATIC TESTING SUMMARY <br /> The following statements summarize the static testing results: <br /> • The Phase I results indicate that these samples reasonably represent the range of NNP <br /> values of the overall population estimated from the LECOW data. <br /> • The ABA, NAG, mineralogy, and static leaching results of the samples are not strongly <br /> correlated to the sample rock-type group. This was also noted based on the analysis of <br /> the Project LE COW database. <br /> • Twenty-seven of the 29 samples that underwent Phase I testing (ABA and mineralogical <br /> testing) had net acid-generating NNP values (less than 0 kg CaCO3/t). Seven of these <br /> samples had negative NNP values that were between -20.0 and 0 kg CaCO3/t, indicating <br /> that their potential to generate acidity is uncertain. Two samples had NNP values that are <br /> greater than zero but less than 20.0 kg CaCO3/t, indicating that they are mildly net <br /> neutralizing. <br /> 23 <br />