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Construction of the light use road to access 6 Seam ventilation shaft facilities required installing culverts <br />. at three places along the access route. Two locations each have a 72-inch culvert; the third location has <br />a 30-inch culvert. Map 151 shows the locations and dimensions of the culverts installed. The 25-year <br />24-hour runoff from the watershed above the proposed 30-inch culvert was modeled using SEDCAD. <br />These runoff volumes as well as the culvert sizing calculations for the 30-inch culvert are included in <br />Illustration 44. <br />From Illustration 10, the 25-year 24-hour peak runoff for the SGW-1 watershed, shown on Map 23, is <br />235 CFM. Using 235 CFM, the culvert sizing utility in SEDCAD was used to size the two culverts where <br />the access road crosses Scullion Gufch. These calculations demonstrate that a 72-inch culvert is <br />adequate to pass this flow. These calculations are also included in Illustration 44. <br />IV.J.1 Control Systems Control systems consists of the following: <br />a. Diversion dikes and ditches which reroute runoff from undisturbed areas around disturbed <br />areas into natural drainage systems. <br />b. Diversion ditches that collect runoff from disturbed areas and direct it into sedimentation <br />ponds. <br />c. Sedimentation ponds hold runoff from disturbed areas a required length of time (theoretical <br />detention time) to allow most of the solids to settle out and release the supernatant back into <br />the natural drainage system. <br />d. Rock check dams in areas otherwise hard to control. <br />e. Rip-rap lined ditches. <br />f. Use of a chemical flocculent such as Nalco Enact 7888 or equivalent for decreasing settling <br />time in sediment ponds. <br />In the "D" Portal Area, special washdown facilities in and around the preparation plant are provided for <br />areas where significant amounts of fine coal dust might accumulate. Water from plant operations which <br />gets into these areas is collected in sumps and pumped to the process water settling pond. This water <br />is then used in the makeup water cycle. Special attention is given to water containing significant <br />amounts of coal fines as the water might have characteristics more objectionable and more difficult to <br />Veat than would runoff from other disturbed areas. <br />Sediment control systems along the conveyor consist of ditches and berms to return runoff to a natural <br />drainage area, Culverts are also used for controlling drainage. Two ponds are used at the slot storage <br />area (SS-1 and SS-2). Ditches, berms, and culverts direct runoff from the top of the slot area into SS-1. <br />Diversion ditches direct runoff from a disturbed laydown area on the west side of the slot storage area to <br />5S-2. <br />Mine Permit Renewal #3 (Rev. 8/9g) IV-38 <br />