2008-09-16_PERMIT FILE - C1982056A (4)

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Fish Creek DewaterinE Site At the dewatering site, drainage and sediment will be controlled by the use of ASC'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 around the stockpile to direct runoff from the stockpile to the two gravel 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 ~o 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 gravel, 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 discharge ditch. The berm will provide an area that can act as a sump to hold or direct water from the site. In reference to the boreholes and control building area, collection berms will be established downslope of the area to direct the estimated 0.12 of of runoff (from the 10- year, 24-hour event) to either the containment area to the west, or to the two rock filters on the north side. In order to provide access to the dewatering boreholes; the two light-use roads will be connected to form a pad between the wells. The 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 are within the confines of the 2.0 acre SAE area as 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 established downslope of the area 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 area, or to a pair of rock filters on the north side. Fish Creek Ventilation Borehole -Another SAE exists at the Fish Creek Ventilation Borehole. A vegetative filter will provide sediment control for the 0.6 acre area of disturbance. Until the vegetation becomes reestablished, however, the 0.06 acre-feet of runoff from the 10-year, 24-hour event will flow to the collection area around the • TR07-61 2.05-79.2 07/14/07