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FITASCA" <br /> Denver, Inc. <br /> the equivalents of NaOH added to reach the pH 8.3 endpoint. The titration results are reported <br /> in units of kg CaCO3/t. <br /> In addition to the titration-derived ANP value,carbon forms were evaluated and used to estimate <br /> ANP using the following procedure: <br /> 1. Total carbon is measured by combustion-infrared spectrophotometer. <br /> 2. Residual carbon after decomposition in dilute HCI is attributed to organic carbon. <br /> 3. Total inorganic carbon (TIC) (total carbon minus residual carbon after decomposition) is <br /> attributed to carbonate carbon and used to estimate ANP (kg CaCO3/t) by multiplying the <br /> percentage of carbon by a factor of 83.4, based on the stoichiometry of Equation 3.2. <br /> 3.1.1.4 Net Neutralization Potential <br /> The NNP is the difference between the ANP and AGP (NNP = ANP —AGP) and is indicative of the <br /> overall balance between acid-generating and acid-neutralizing components. Samples with a <br /> negative NNP value are classified as potentially acid-generating (PAG), and samples with a <br /> positive NNP value are generally classified as not potentially acid-generating(non-PAG). Samples <br /> that are only marginally net acid-neutralizing are often classified as indeterminate or uncertain <br /> due to uncertainties associated with the assumptions inherent in the ABA methods. Guidance <br /> from the U.S. Bureau of Land Management (BLM) indicates that samples with NNP values <br /> between 0 and 20 kg CaCO3/t should be considered uncertain regarding their potential to <br /> generate acidity (BLM 2013). In Itasca's professional experience, samples with NNP values <br /> between -20 and 0 kg CaCO3/t are also uncertain regarding their potential to generate acidity. <br /> The results of other geochemical tests are used to further evaluate the potential for samples with <br /> NNP values near 0 kg CaCO3/t to generate acidity, as discussed in Sections 3.2.2 and 4.3. <br /> 3.1.1.5 Neutralization Potential Ratio <br /> The neutralization potential ratio (NPR) is the ratio of ANP to AGP of a sample. The NPR value is <br /> also used as an indicator of the overall balance between acid-generating and acid-neutralizing <br /> 13 <br />