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n <br />LJ <br />Propasel Nrdmtogicd Moduug Plan far Jie Mwflavw~ MLu: 2 <br />slow the oxidation of pyrite,-slowing the production of acid. Sdcond, it will neutralize the <br />acid that is produced. The core samples that exhbited low paste pH's are surrounded by <br />non-acid producing, calcite-bearing racks. The water that contacts the low-paste pH <br />materials will have 5rst reacted with calcite, and therefore developed a pH-buffer capacity <br />of its own The groundwater monitoring data indicate that mixed overburden and <br />interburden water Lave near neutral pH's. Sample pH's less than 6 are associated only with <br />the lower Dakoia coal. Where the coal's permeability is high enough m produce about S <br />gpm during sampling, the acid-producng reactions do not appear to be fast enough to <br />maintain tte pH of the water less than S. Oxidation rates may increase because of the <br />mining process. However, the supply of oxidation is only one of the constraints on the <br />production of acid. Other constraints are imposed by the quantity of calcite present, and <br />the reactivity of the pyrite. The paste-pH test, wnducted under oxidi2iog conditions, <br />indicates that a very small proportion of the overburden is likely to produce add. The acid <br />that is produced will be quickly neutraiized. During the mining process, WFC will test the <br />overburden and if acidic layers are encountered, trey will be mixed with non-acidic layers <br />to neutralize arty add forming effects. <br />Potential impacts of replaced atwt7 on goundwater quality. The analysis of geochemit:al <br />• wntrols on groundwater quality suggests that the water chemistry and concentrations of most <br />elemenu of concern aze controlled by mineralogic reactions that will resist changes in water <br />chemistry. Production of add may occur in very local settings and is probably most <br />prevalent in ttte waI which will be mined. Calculations indicate that neutralization of the <br />add will occur rapidly with mixing of water, or with movement of addic water into calcito- <br />bearing rocks. Also, the analysis conducted indicates trot chemit:al changes are not likely <br />to occur. <br />Effects of mining on the loca~eomorphology. Impacts from mining on the local <br />geomorphology will be long term, but appeaz to be of minimal significance. The <br />reestablished reach of the drainage which will be mined will result in a shorter, slightly <br />steeper stream channel. The potential for increased sediment loads m the drainage (once <br />pond (107 is removed) should be offset by the stable banksides and the relatively small <br />change in overall gradient. TLe increased runoff and wrtsequent erosion potential on <br />disturbed basins in the mining area due to the temporary loss of topsoil stricture should be <br />of minimal signifit:ance. Contour ripping, mulcting and revegetation have been demonstrat- <br />ed to minim;vr. soil erosion and will be used t0 mitigate the increased R7noff potential until <br />the topsot7 structure is developed.. <br />Effects of sediment ponds on channel characteristia and downstream users. Potential <br />impacts of sediment pond 007 on dowtutream users will involve possible reductions inflow <br />due to impounded water. The watcr augmentation plan discusses the available water which <br />wilt be used should impacts be fdenti8ed. WFC currently has tights m a sufficient quantity <br />11 <br />• <br />Attachment 2.04.7-5-35 <br />