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Chapter II <br /> c. Diversions. <br /> A number of diversion ditches have been designed and constructed, and are <br /> maintained, to control surface runoff and to minimize water quality degredation. <br /> The ditches have been located so as to divert water away from disturbed areas, or <br /> to convey water flowing out of disturbed areas to treatment facilities. All diversion <br /> ditches which drain disturbed areas lead to sediment ponds. <br /> The diversion ditches were designed according to CMLRB regulations. <br /> Temporary diversion ditches (such as one at the base of the old coal refuse <br /> disposal area) were designed to convey a minimum peak flow from the <br /> 10-year/24-hour storm event, and with a minimum freeboard design of 0.3 feet. The <br /> ditches have been installed as approved by the Board on the inside of all cuts and <br /> fills so that the flow velocities will not cause adverse erosion. The ditches are also <br /> located away from the toe of the fills to prevent undercutting during periods of high <br /> flow. Where necessary, rip/rap and/or vegetative control measures are also <br /> employed. <br /> A permanent diversion ditch has been constructed in the south fork of Dutch Creek. <br /> It was designed to convey the peak flow runoff event from the 100-year/24-hour <br /> storm, and using the best technology currently available to minimize the contribution <br /> of sediment to Dutch Creek. In construction, the culverts were sized and placed in <br /> the stream channel using dozers and a crane. The fill material was placed using a <br /> backhoe and compacted with a vibrator compactor. The outslopes were stabilized <br /> as necessary with rip rap, or were revegetated. <br /> A 100-foot buffer zone has been left below the toe of the spoil, landfill and refuse <br /> disposal area adjacent to the South Fork of Dutch Creek. Diversion ditches have <br /> also been constructed around the preparation plant. <br /> Perimeter ditches and berms have also been constructed around the refuse, landfill <br /> and Adit/Rock Tunnel spoil disposal areas. <br /> An extensive drainage control plan/system was developed in accordance with <br /> CMLRB rules and regulations, section 4.03.0 - Performance Standards for Haul <br /> Roads. The road drainage system has been designed to handle a 10 year/24 hour <br /> rainfall event. See Vol. 3, App. II-B-7, Att. 2. <br /> These roads bisect three major drainages: Coal Creek, Dutch Creek and Bear <br /> Creek. Eleven miles of the total 13.7 miles are within the Dutch Creek drainage. <br /> Natural drainage channels were neither altered nor relocated for construction of the <br /> haul road system, and where the roads cross perennial streams, culverts have been <br /> 31 <br />