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occasionally used to collect and retain minor quantities of Prepazation Plant wash-down water. As an incised and closed basin (ie: no outlet) the only inputs aze thickener overflow, wash-down water from the Preparation Plant, or minor incident precipitation, which aze subsequently pumped back into the system by a portable floating pump i installation. Water level in the sump is monitored and managed as part of the ongoing plant operations. SMALL AREA EXEMPTIONS Twentymile Coal Company has been granted several Srnall Area Exemptions (SAE'S) within the permit area. Effective drainage and sedimentation control in these areas will be achieved through the use of a number of individual or combined methods, including gravel-surfacing; erosion control fabric or materials; berms; contour furrows; sediment traps; rock check dams; vegetative filters; the use of silt fences, straw wattles, or straw bales; or other approved methods. Rockdust Tank - An SAE for sedimentation control has been granted for the rockdust tank and truck access/unloading area. The total disturbance will be approximately 0.5 acres. Of this azea, 0.3 acres will be filled with pit run gravel, which acts as an infiltration screen for any overland flow associated with the rockdust tank and access/unloading area. Estimated peak flow from the area for the 10-year, 24-hour event is approximately 0.04 acre-feet. Runoff from the topsoil pile is controlled by a bem>/swale/rock filter system. In addition to the i~ltration screen, flow from the tank and unloading area is conveyed by means of wwales and berms to a gravel filter. These controls, in conjunction with existing vegetation, will be sufficient to control runoff from the area as observed during previous inspections. Fish Creek DewaterinQ Site - At the dewatering site, sedimentation will be controlled by the use of alternate control systems such as filter fences, gravel filters, and existing vegetation. In reference to the 0.5 ac stockpile located to the southwest of the pond, a berm will be inscribed azound the stockpile to direct runoff from the stockpile to the two gravel filters by the stockpile. This will effectively treat the estimated 0.02 acre-feet of runoff resulting from the 10-yeaz, 24-hour event until vegetation is reestablished. Once this occurs, the berm and filters can be removed. The runoff from the 0.2 acre stockpile adjacent to the transformer will natwally drain to the low azea northeast of the stockpile where adequate vegetation exists to provide filtering and treatment of the water. The SAE is shown on Map 26, Fish Creek Borehole Area Facilities and Access Road. Two gravel filters will be constructed in the collection ditch for the ponds and associated disturbed areas, to act as a secondary sediment control measure. The gravel filters will be constructed of 3-inch minus washed gavel, and will be approximately 24 inches in width. The filters will be placed across the ditch and extend halfway up the sides of the ditch. A berm will be placed on the south side of the road leading into the control building. The berm will be located to keep drainage from this area from entering the dischazge ditch. The berm will provide an area that can act as a sump to hold or duect water from this site. Also, in order to provide access to the dewatering boreholes, the two light duty roads will be connected to form a pad between the boreholes. Available topsoil will be windrowed to the sides of the pad and will be stabilized with the approved seed mixture. The graveled pad and roads aze within the confines of the 2.0 acre SAE shown on Map 26, Fish Creek Borehole and Facilities and Access Road. In reference to the boreholes and control building area, collection berms will be inscribed downslope of the azea to direct an estimated 0.12 acre-feet of runoff from the 10-year, 24-hour event to either the adequately-sized natural depression west of the azea, or to a pair of rock filters on the north side. L~ MROS-194 2.05-79.1 07/2/05