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<br />rather states "if it proves to be a problem" (emphasis added) while referring to problematic <br />rates of acid generation. Thus Dr. Hyatt is discussing a conservative position that would be <br />justified if the drainage from the overburden becomes a problem. <br />In sum, fine grinding (1) is not yet demonstrated to have any favorable impact on full-scale <br />operations and in fact is not a variable in the natural system and (2) is not economically <br />feasible. <br />CC&V takes this opportunity to compare the paste pHs measured for the Cresson overburden <br />with the criterion that the State of South Dakota was stated, in arecently-received <br />communication from Pat Nelson, to have imposed in one case. That criterion was a paste <br />pH of 4.5. Note that essentially all of the Cresson material is above that criterion. The <br />South Dakota correspondence also imposed a Net Acid Generating ("NAG") pH of <3.0 as <br />a criterion. CC&V's NAG pH data show five samples (of 26 samples which span the range <br />of total sulfur content) with NAG pHs lower than 3 (all are >_ 2.5 and there is a significant <br />difference between these five and all others). Each and every one of these lower values <br />represents a sample with the higher total sulfur concentrations that are, in general, labels of <br />overburden that will be segregated as higher sulfide material. <br />Dr. Hyatt does suggest that the differentiation between "more acid-generating material" and <br />material not requiring special management would be lower than the 0.8 percent total sulfur <br />determined to be an appropriate criterion based on analyses of all the data. Dr. Hyatt <br />suggests a criterion of 0.5 percent. Given the information that we have generated, CC&V <br />does not see a different basis to modify our proposal to utilize a criterion of 0.8 percent. <br />This is especially the case when one examines the water quality data generated by the <br />humidity cell tests. It is important, we believe, to distinguish between acid generation that is <br />characteristic of the region and which therefore does not change the chemical system and <br />acid generation that produces at a substantially higher rate. The >_0.8 percent total sulfur <br />material may be in the second category. Tlie <_0.8 percent material falls into the first <br />category. <br />If any questions arise, we should meet to discuss them at your convenience. We are, as you <br />know, proceeding with the segregation procedures submitted by CC&V and accepted by the <br />OMLR to date. <br />ronmental Affairs <br />FILE: POSEYWQ.MEM <br />5 <br />