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coal than most other areas at these sites. This assumption is documented <br />by comparing the OM levels of the very old coal contaminated soils and the <br />very old refuse piles. Upon comparing the mean values for these two <br />subsets of data the mean OM level of the very old coal contaminated soils is <br />2.56 percent while 4.49 percent OM values were associated with the very old <br />refuse piles samples. Using a t-test comparison these means are <br />significantly different at the 0.05 level of significance. Unfortunately, it is not <br />possible to compare the OM levels in the new and old refuse materials for the <br />reasons outlined by Bauer et. al. (1976) wherein they discovered that the level <br />of grinding has more of an affect on OM levels than does the actual coal <br />content on OM values. Since it is obvious that the coal cleaning <br />methodologies presenty util'¢ed resuR in signficanUy more grinding than <br />were associated with the old coal clean techniques, it is not possible to <br />directly compared OM levels to determine the approximate coal content. <br />However, since the very old coal contaminated and refuse samples were <br />generated by similar methods ft is possible to compare these values. <br />The increased ratio of coal with respect to waste rock associated with the <br />old refuse piles would logically suggest that more acidity would be generated <br />in these very old refuse piles than on the more recent refuse sites where less <br />coal and correspondingly more waste rock are available to counteract the <br />acidity generated by the oxidizing sulfur associated with the coal. Upon <br />excluding these four samples from the suitability comparison, no differences <br />• in suitability exist with respect pH for the refuse and soil materials. <br />Examination of the Southfield Mine refuse materials with respect to acid <br />base potentials suggests that there is no potential acidity problem for these <br />materials. In the present evaluation, acid base potentials were calculated on <br />total sulfur and not pyritic sulfur as recommended in the NMMMD Guidelines <br />or pyritic and organic sulfur as recommended in the WDEO Guidelines. This <br />comparison represents much more of a "worst case scenario' than mandated <br />by regulations because R assumes that even those sulfur forms that have <br />previously been oxidized will again oxidize. Such a phenomenon is <br />chemically impossible. Clearly this set of conditions and the failure to <br />document acidic conditions seven years after refuse deposition suggests that <br />sufficient carbonates exist in these refuse materials to offset any potential <br />problems with acidfication. In all previously reported conditions involving <br />acidification, a reduction in pH has occurred in a very short period of time. <br />The failure of the Southfield Mine refuse materials to acidify after seven years <br />of weathering supports the acid base potential calculations that preclude acid <br />formation in these materials. <br />The Southfield Mine refuse samples contain much more waste rock and <br />hence have a much lower potential of acidfication than do these very old <br />refuse piles. This is best indicated by the neutralization and acid base <br />potentials calculated from this waste material. The average acid base <br />potential of the Southfield Mine refuse, based on total sulfur, is an excess <br />22.13 tons of CaCO3 per 1000 tons of material with a range of 12 to 38 tons. <br />. Using only the pyritic sufur as recommended by the NMMMD, the average <br />acid base potential of the Southfield Mine refuse is an excess 30.5 tons of <br />CaCO3 per 1000 tons of material with a range of 18 to 49.5 tons. Application <br />of the WDEO procedure of using the sum of the pyritic and organic sulfur the <br />average acid base potential is an excess 23.6 tons of CaCO3 per 1000 tons <br />40 <br />