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in the Area 1 Pit. A manhole with manual valves or automated control valves will be used to control flow to the Washplant. • Washplant I Thickener Overflow Sump (Superceded by TR07-59, Washnlant ID -The Washplant 1 Thickener Overflow Sump, located adjacent to the Thickener Tank in the Washplant I area, as shown on Map 24, Surface Facilities, and by Figure EX8w-1 in Exhibit 8w was excavated during Washplant construction to serve as a catch basin for the contents of the Thickener, if required for maintenance or under upset conditions. Impoundment design, operation, maintenance, and reclamation information is provided in Exhibit 8w. While it has not been necessary to utilize the basin for this purpose, it is occasionally used to collect and retain minor quantities of Washplant wash-down water. As an incised and closed basin (ie: no outlet) the only inputs aze thickener overflow, wash-down water from the Washplant, or minor incident precipitation, which aze subsequently pumped back into the system by a portable floating pump installation. Water level in the sump is monitored and managed as part of the ongoing plant operations. Washplant II Thickener Overflow Sumn (TR07-59. Washnlant IIl -For discussion of Washplant II Thickener Overflow Sump please refer to previous discussion under Rule 2.05.3(3), Mine Facilities. SMALL AREA EXEMPTIONS AND ALTERNATIVE SEDIMENT CONTROLS The CDMG has approved several Smal'1~Area Exemptions (SAE'S) and Alternative Sediment Controls (ABC's) within the permit area. Effective drainage and sedimentation control in these areas will be achieved by a variety of methods, including gravel or asphalt surfacing, vegetative filters, installation of fabric filter fences, rock check dams, gravel filters or berms. Rockdust Tank A SAE for sedimentation control has been granted for the rockdust tank and truck access/unloading azea. The total . disturbance will be approximately 0.5 acres. Of the total, 0.3 acres will be surfaced 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-yeaz, 24-hour event is 0.04 acre-feet. Runoff from the topsoil pile is controlled by a berm/swale/rock filter system. In addition to the infiltration screen, flow from the tank and unloading area is conveyed by means of swales and berms to a gravel filter. These measures, in conjunction with existing vegetation, are effective in controlling runoff from the area, as observed during previous inspections. Fish Creek Dewaterine Site At the dewatering site, drainage and sediment will be controlled by the use of ABC's including filter fences, gravel filters, and existing vegetation. In reference to the 0.5 acre topsoil stockpile located to the southwest of the pond, a berm will be established azound the stockpile to direct runoff from the stockpile to the two gavel filters by the stockpile. This will effectively treat the estimated 0.02 AF of runoff from the 10-year, 24-hour event until temporary vegetation is established on the stockpile. Once this occurs, the berm and filters can be removed. The runoff from the 0.2 acre stockpile adjacent to the transformer will drain to the low area of negative drainage northeast of the stockpile where adequate vegetation exists to provide filtering and treatment of the water. The small area exemption is shown on Map 26, Fish Creek Borehole Area Facilities and Access Road. The collection ditch for the ponds and associated disturbed areas will be constructed with two gravel filters 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 azea that can act as a sump to hold or direct water from the site. In reference to the boreholes and control building area, TR07-59 2.05-79.1 03/26/07