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RULE 2 - PERMITS <br />C einfiltra ion of this runoff into alluvial aquifers Analyses of both actual existing and potential <br />• future coal and mine development waste materials are described in Section 2.04.6, Geology <br />Description. Based on analyses of coal, roof, and floor samples, pH values tend to be slightly to <br />moderately alkaline, overall sulfur content is low, and buffering capacity is relatively high due to <br />the presence of significant quantities of calcium. Consequently, acid - producing potential is low. <br />Similarly, chemical analyses indicate low concentrations of most potentially toxic components. <br />Available analysis results for existing Seneca II spoils, which have been in place a number of years <br />and have had ample opportunity to weather and oxidize, offers an expanded and probably more <br />accurate perspective of potential water quality impacts than chemical analysis results for fresh coal, <br />roof, and floor samples. The weathered mine waste and coal refuse samples show no significant <br />acid, alkaline, or toxicity potentials. Any minor potential impacts due to TDS, iron, or other <br />chemical constituents are expected to be minimized by specific operational measures utilized during <br />construction and reclamation of overburden and coal piles. These measures include: <br />• Controlled placement and compaction <br />• Effective routing of surface drainage around stockpile areas <br />• Collection of disturbed -area runoff in ditches, and treatment in sediment ponds <br />• Reclamation <br />It is anticipated that infiltration to the overburden and coal stockpiles will be minimal given the <br />relatively semi -arid conditions, compaction, and engineering controls that will be implemented. <br />Surface runoff is routed in diversion channels to sedimentation ponds where it is retained and <br />• sampled prior to release to natural drainages. <br />As discussed above, PSCM will utilize sedimentation ponds and associated drainage structures to <br />intercept and route runoff from disturbed areas, retain runoff for sediment control, and to control <br />discharges to stream drainages. Operation of the sedimentation ponds has the potential to affect <br />both ground water quantity and quality by altering the timing and volume of discharge flows, <br />providing additional recharge to alluvial ground water systems, causing changes in water chemistry, <br />increasing TDS levels through evaporation, decreasing TSS levels through settling, and increasing <br />the concentrations of specific mineral components through evaporation. <br />Effects of evaporation will be minimized by limiting detention time in the sedimentation structures <br />to that interval required for effective reduction of suspended solids. Because runoff typically occurs <br />only in response to snowmelt and major storm events, evaporation will be further limited by cold <br />temperatures during spring when the majority of snowmelt occurs. Pond designs, as outlined in <br />Exhibit 2.05.3 -E2, Drainage and Sediment Control Plan, provide for both minimal detention times <br />and effective pond routing so any delay in discharge to the receiving drainages will be limited. <br />With pond routing, discharge will occur continuously once the water reaches the discharge <br />elevation so effects on downstream flows or alluvial aquifers will likewise be minimal. <br />Upon completion of mining, all mine disturbance areas will be reclaimed. Reclamation and <br />establishment of effective vegetative cover will minimize disturbed area runoff to the sedimentation <br />ponds, and result in restoration of natural drainage and direct discharge to the receiving drainages <br />once the non - permanent sedimentation ponds are removed at the end of the extended liability <br />• period. Given this consideration, any potential ground water impacts will be both limited in scope <br />and of a temporary nature. <br />PSCM Permit App. 2.05 -101 Revision 12/17/09 <br />