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NPDES permit for the Seneca II-W Mine. A storm water permit and spill <br />prevention containment and control plan associated with the NPDES permit also <br />dictate preventative and mitigation measures for ensuring that all water leaving the <br />mine site meets applicable effluent limits. <br />The Division has granted a small area exemption from use of sediment ponds due <br />to the limited size of the area and due to the fact that ponds and treatment facilities <br />aze not necessary for the drainage to meet the effluent limitations of Rule 4.05.2 and <br />applicable State and Federa] water quality standards for receiving streams, and also <br />due to the fact that no mixing of surface drainage with a dischazge from underground <br />workings will occur. The small areas to be exempted are the topsoil stockpiles listed <br />on Table 13-8-1 and shown on Exhibits 13-2 and 13-3. (4.05.2(3)(b)(i)). <br />B. Diversions and Conveyance of Overland Flow <br />All major drainages that aze to be disturbed by mining will be reclaimed to <br />approximate the premising configuration and to blend with the undisturbed drainage <br />above and below the azea to be reclaimed. Table 20-2 provides the pre-and postmine <br />drainage channel summary. The reclaimed drainages are located on Exhibits 20-2 <br />and 20-2A. <br />The average postmining stream gradients will have concave longitudinal profiles <br />which approximate the premising slopes. The premising and postmining drainage <br />areas of the reclaimed channels are similar in acreage and slope. After the <br />watershed has been graded and the location of the drainage channel determined, the <br />channel will be constructed to the required shape. At first, the channel will be <br />untopsoiled to allow for initial stabilization and inspected for stability according to <br />the rill and gully plan in Tab 22. When the channels have been stabilized, they will <br />be topsoiled and vegetated. <br />Seneca Coal Company has permitted stock tanks in both the reclaimed drainage <br />channels at the Seneca II-W Mine and some existing culvert outlets. The stock tanks <br />will slow the peak runoff of precipitation events and help to minimize erosion in the <br />drainage channels. They will also act as an additional alternate sediment control <br />measures, minimizing the potential for sediment from roads to be cazried off the <br />permit site. These small tanks will benefit both livestock grazing and wildlife <br />utilization of the reclamation. <br />C. Sedimentation Ponds <br />Seneca Coal Company will primarily use sediment ponds to prevent additional <br />contributions of sediment to streamflow or runoff outside the permit area due to <br />mining disturbance. Existing sediment ponds include 005, 006 and 009. Ponds <br />proposed for the Seneca II-W south extension area are 015, 016 and 017. <br />Seneca iI-W Findings Document 17 November 3, 1999 <br />