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<br />IV.J.1 Gantrol $yatama 1n the 'D' Portal Area and the Railroad Loading Area, control systems <br />consists of the following: <br />a. Diversion dikes and ditches which reroute runoff from undisturbed areas around <br />disturbed areas into natural drainage systems. <br />b. DNersion ditches which collect runoff from disturbed areas and direct it into <br />sedlrnentatlon ponds. <br />c. Sedimentation ponds which collect runoff from disturbed areas, hold the water a <br />required length of time (theoretical detention time) to allow most of the solids to settle <br />out and release the supernatant bade into the natural drainage system. <br />d. Rock check dams in areas otherwise hard to control. <br />In the 'D' Portal Area, special washdown fadlities in and around the preparation plant are provided <br />for areas where significant amounts of fine coal dust might accumulate. Water from plant operations <br />which gets into these areas is collected in sumps and pumped to the process water settling pond. <br />This water is then used in the makeup water cyde. Special attention is given to water containing <br />significant amounts of coal fines as the water might have characteristics more objectionable and more <br />difficult to treat than would runoff from other disturbed areas. <br />In the East Portal Area, which consists of () material storage area, pi) fuel tank area and (ii) turn <br />around area, the drainage and sedimentation will be controlled by various ditches leading to catch <br />basins, berm and sediment control devices along the toe of the fill to intercept sediments from reaching <br />the Scullion Gulch drainage. See Map 139. Western Fuels received a small area exemption from the <br />requirement to install sediment ponds. Page IV-SSA, IV-55B and IV-55C show calculations on <br />drainage area, runoff volume and adequacy volume of catch basins. A small area exemption is also <br />requested for the road base pad by the mine access road. This pad is identified in Map 1. Any <br />sediment leaving the area is controlled by a etch basin or other sediment control devices. Map 146 <br />shows the details of the storage pad, V-ditch and sediment control. Illustration 45 includes SEDCAD <br />runs to estimate runoff volume and V-ditch calculations. <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 <br />storage azea (SS-1 and SS-2). Ditches, berms, and culverts direct runoff from the top of the slot area <br />into SS-1. Diversion ditches direct runoff from a disturbed laydown area on the west side of the slot <br />storage area to SS-2. <br />The sedimentation and drainage control system used in the Refuse Disposal Area are slightly different <br />as shown on Maps 76, 77, 78, 79 and 80. The watershed of a sub-area is progressively disturbed <br />as the sub-area is filled with refuse. During this process, runoff from undisturbed areas is diverted <br />away from disturbed areas by temporary ditches. The purpose of these temporary ditches is to <br />prevent excessive erosion of the refuse and not to prevent mixing of runoff from disturbed areas. Both <br />runoffs are carried by the perimeter diversion ditches into the sedimentation ponds. Both types of <br />runoff are mixed. This is not considered detrimental. <br />(Rev. 11(3/93) IV-55 <br />