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The operator shottld describe how acid generated in the upper part of the diatreme will be neutralized by cm•bonates in the deeper part of the diatreme if groundwater moves domitrartth~ throtegh discrete fractures Lather than more homogeneously through the breccia and other ut:jractured rock.. 2. Appendix A. The static test data in App A accompany no explanation of how samples were measured. It is presumed for purposes of this review that the tests measured the following: a. total sulfur b. sulfide sulfur c. sulfate sulfur d. organic (non-extractable) sulfur -calculated by difference e. ANP by titration or some presumption of titrable alkalinity If these pres:tmptiotrs are ittcon•ect, the Operator should inform the Division of such, providing a explanation of the analytical procedures used for these analyses. Proceeding as if the above presumptions aze correct, it appears the methods may underestimate AGP that might be generated in the field while overestimating field-available ANP. To wit: AGP. Sulfate sulfur analyses include minerals such as the Ca-SO4 family of minerals, which would be non-acid generating, and the jazosite-alunite family ofminerals -hydrous metal sulfate evaporites -which could be variously acid-generating. The Operator should describe the methods by which sulfate species were identified and provide evidence that the jarosite-alunite family ofinetal-sulfate hydrates were adequately accounted for in the calcttlatiot: of AGP. ANP. The ANP method is not stated. For the system at hand, considering the mineralogical composition of the diatreme described in Lindgren and Ransome, it is noted that ANP calculations based on carbon and sulfur, whereby the carbon is total carbon assumed to be either calcite or dolomite and total sulfur values is assumed to be sulfide sulfur would be a preferable method. Tl7e Operator should describe the AGP and ANP methods used fot• the static tests given in Appendir A. If the carbonate minerals it:clttde an appreciable percent of either siderite or ankerite, the ANP should be adjusted accotdit:gly. If total carbon tests were run, and if the rock contains carbon species other than carbonates, those should be t•epot•ted. If the test methods employed titt•atiotts or other ttetttralization reactions that x~ould include silicate bujferit:g, the ANP values should be re-examined. Absent this, the Operator shottld address the question it: a narrative or in further calculations showing that, high estimated NNP values aside, the system still will be able to minimize impacts to the hvdrologic balance.