PERMFILE40906 - Laserfiche WebLink

Home Browse Search

Pond T Topsoil Stockpile The Pond T Topsoil Stockpile covers 0.5 acres between the Pond T embankment face and railroad spur. Runoff from this azea flows downslope between the railroad embankment and Pond T face to the Pond T weir. From there, flow is conveyed under the track by means of a culvert to Foidel Creek. Vegetative filtering is provided by the established temporary vegetation on the topsoil pile and in the area below the topsoil stockpile. Additional filtration is provided by a rock filter, between the stockpile and the culvert, and vegetation on the benches, and cut and fill slopes of the facility itself. Sediment control will be achieved through the installation of an upland clean water diversion ditch, by seeding and mulching the topsoIl piles and cut and fill slopes with 2 tons/acre straw, and by graveling the pads and roads with sufficient gravel to achieve 80 percent gravel cover. Vegetative filters will provide adequate sediment detention to achieve effiuent limitations following a 10-yeaz, 24-hour storm event. Peak flows from the design storm aze estimated at 0.05 cfs, 0.27 cfs, and 1.96 cfs for the east side of the East topsoil stockpile, the south and west sides of the Southwest topsoil stockpile, other topsoIl slopes, and the benches and cut and fill slopes of the facility, respectively. EMD Dewaterine Treatment Facility SF'/, rl~ ~/`I The SAE demonstrations for the EMD dewatering ponds located in the NW'/SW'/ Sec. 21, TSN, R86W, 6th P.M. on Binco silty clay (a D soil) cover approximately 3.12 acres of disturbance and 4.4 acres total. SAE demonstrations have characterized three azeas; the west side of the topsoil pile; the east side of the topsoil pile; and the cut slope west of the dewatering ponds. Sediment control will be achieved by seeding and mulching the topsoil pfle and cut slope with 2 tons/acre straw. Vegetative filters of unmanaged cropland vegetation will provide adequate sediment detention to achieve effiuent limitations following a 10-yeaz, 24-hour storm event. Peak flows from the design storm are 1.14 cfs, 0.64 cfs, and 0.38 cfs for the upland and west side of the topsoil pile, the east side of the topsoil pile and the downgradient area, and the cut slope, respectively. Rockfall Hazard Trenches There aze three rockfall hazard mitigation zones. The zones consist of various combinations of trenches and bemts established between the Twentymile Road and the Twentymile sandstone cliffs north of the facilities area. Two SEDCAD+ demonstrations were developed for each trench; one treating the overlying watershed with the TR 05-45 2.05-82.1 Revised -January 2005