2013-01-29_PERMIT FILE - C1981022A (3)

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S'e~tinn - ?.OS.G significant changes in water chemistry for the receiving drainages. ]n addition, disnubcd area runoff and anv mine water discharge flows will be buffered by signiftcantly greater volumes of normal nmoff from undisturbed cirainagc basin areas. Contact between disturbed area runoff and surficial materials exposed to weathering and oxidation, drainage Fram coal stockpiles and mine development waste disposal areas, and any discharge of excess mine drainage Flows may result in increases in 1-DS and individual chenucal constituents in surface runoff flows. In addition, one of the natural consequences of surface dishirbance and any associated minor erasion will be increases in sediment loading and 1'SS levels for the disnrrbcd area runoff. Surface water in the mine area is generally neutral to moderately alkaline utith cacvared levels of TICS, "I'SS, and iron. IVlirung and related activities will probably not result in any significant change in surface water pH although TUS and "I'SS levels may increase slightly in the disturbed area runoff and any mine water discharge. '1'hc same considerations and mitigation measures previcxisly disatssed For potential changes in surface water chemistry arc also applicable for potential increases in '1'llS and indnndual chemical constituents. Potential increases in TSS levels will be effectively addressed on a short-terra basis by establishment and operation of the drainage and sediment control system, control of any necessary mine watcc discharge, the use of large-capacity underground retention sumps, and compliance under the required CUPS permits with applicable monitoring requirements and discharge effluent limitations. Reclamation and restoration of effective surface drainage conditions will address all potential mining and related surface water impacts over the long-term. C)h4I.l.C; or its predecessors have previously placed approximately 1,150 feet of 9-foot diameter culvert through the I?lk Creek Support C~acilities area to safely carne Llk Creek through this area and to isolate the creek from potential raining-related impacts. O~•f1,LC: will culvert two additional segments totaling an additional I,G(?0 feet of the creek to safely carn• the crock under portions of the fak Creek Itline portal benches and minimize pc>tenria) long-term mining-related impacts. (;uh•erting and diversion ma}~ temporaril}~ effect stream flows during construction, and constnuction activities may result in increases in sediment contributions both during constnrction and for a short period of time following diversion of flows as the new channel scgtnenC stabili~cs uncicr varying flaw conditions. Similarly, C)IaLLI,C will culvert approximately ~15C)' of chc ephemeral l3rar Crock with installation taking place during a no flow period. OIvLLL.C well effectively minimize the impacts to stream flows and sedimentation by scheduling culvert placement, removal, and stream channel restoration during seasonal low flaw condirions, if feasible; utilizing siltation fences to minimize potential sediment contributions both during and following construction; extensive use of riprap and other erosion control materials in both the channel and adjacent bank areas; and, revegctating all construction disturbance areas. UIVtLLC is progressively constructing a permanent mine development waste pile in the first ephemeral drainage west of EU: Crock and may, dependent an total development waste disposal requirements, develop one or more additional similar wastepile areas in the funirc. pile constntction blacks normal flow through the existing ephemeral channel, associated disturbance may change surface runoff conditions and result in additional sediment contributions, and leaching of infiltration through the wastc•pilc may result in changes in water chernistn' and specific chemical constiurents. 'TR-G() 2.05-93a Rcv. Nov. 3008