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Designs reveal that the dip-sections will not pass the design peak flows without overtopping. <br /> In 1982,the permittee submitted justification that the dip-sections would be as environmentally sound <br /> as designs which would comply with Rule 4.03.1(4)(e)(i). Since the dip-sections are constructed of <br /> reinforced concrete, they will not erode if overtopped. In addition, the upstream and downstream <br /> sections of the stream are protected by riprap so they will not be undermined. The overtopping of the <br /> dip-sections will likely be a gradual event. The water will Flow over the top of the smooth concrete <br /> surface with very little turbulence being induced by the dip-section. According to calculations done <br /> by the permittee, the dip-sections would be overtopped for a total of 3.4 hours during a 20-year, <br /> 24-hour precipitation event. The installations are therefore acceptable to the Division. <br /> In conjunction with reclamation activities within each of the surface facilities areas, most roads will <br /> be removed and restored to approximate original condition. All culverts will be removed, natural <br /> drainage patterns across each road will be reestablished, and all disturbed areas will be revegetated. <br /> Certain roads will be retained for postmining use, in accordance with landowner requests for use <br /> following completion of mining and reclamation. Road retention narrative and documentation is <br /> provided on Page 14-14 and in Appendix 14-5. In addition to the haul road and access road segments <br /> specified below, portions of Light Use Road 1 and Light Use Road 6, which were pre-existing, <br /> minimally modified and used only occasionally by the operator,will be retained following reclamation <br /> in accordance with landowner requests. <br /> A. Haul Roads <br /> I. The permittee has made a demonstration, based on site-specific precipitation rates, percent <br /> of grade, and soil properties, that use of alternative specifications for culvert and bridge <br /> sizing will not result in increased erosion. The Division therefore proposes to approve the <br /> use of the alternative specifications for the following culverts or bridges, also referred to <br /> as the "dip-sections," where Haul Roads 2, 3, and 4,cross Coal Gulch. The structures are <br /> depicted on Exhibits 8A, 9A, 1 OB, 19, and 51 (4.03.1(4)(e)(vi)). <br /> 2. The operator and landowners have requested retention of Haul Road 4 from the CRDA-1 <br /> turnoff to the CRDA-3 turnoff,the entire length of Haul Road 5,and Haul Road 3 between <br /> the county road and the rail loop. The subject roads comply with all applicable <br /> performance standards, retention is compatible with the approved postmining land use,and <br /> written landowner requests for road retention have been provided(4.03.l(l)(f). <br /> B. Access Roads <br /> 1. The operator and landowners have requested the retention of Access Roads 2 and 3 as <br /> documented in Appendix 14-5. Retention is compatible with the approved post mining <br /> land use and landowner desires, and the roads comply with all applicable performance <br /> standards. Therefore, the Division proposes to approve retention of the access roads as <br /> specified in Appendix 14-5 (4.03.2(I)(f)). <br /> 23 <br />