2018-11-05_GENERAL DOCUMENTS - C1981044

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Williams Fork Mines Prepared by: R. Reilley M.S. GISP C1981044 5 November 2018 17 The design report prepared by C.T.L. Thompson (Exhibit 17) demonstrates that the existing roads were designed with sound engineering practices and are structurally stable. For the purpose of examining road cuts and road embankment conditions, the operator looked at the worst-case road segments at the mine. The roads at the mine were designed for proper road drainage as well as compatibility with the sediment control system. A few access and light-use road segments did not require roadside drainage ditches to collect runoff due to the fact that the grade is only two to five percent. An example is the access road on the southeast edge of the surface facilities area. Roads were pitched to allow sheet runoff to disperse into adjacent grassland. On steeper roads, roadside drainage ditches are used to collect runoff and safely discharge it. Much of the runoff from the roads is passed through a sedimentation pond to decrease suspended solids. Culverts are provided at intersections with drainage channels so as not to interfere with the natural stream flows. The permittee’s design for the road bridge that crosses the Williams Fork River indicates the bridge will safely pass the river flow resulting from a 100-year storm event. The Division is removing a previously-granted variance from culvert spacing requirements for haul roads and access roads that apparently existed in the regulations at some time in the past. As these requirements do not appear in the 2014 version of the regulations, such a variance is no longer required. Several roads in the permit area are proposed to be retained as permanent features. These roads are shown on Map 29: Reclamation Plan. The roads include the main haulroad leading from State Highway 13 to the No. 5 portal; old Highway 13, which provides access to the No. 5A portals; and a portion of road at Williams Fork Strip Pit. If there is interest from the County, Old Highway 13 may be returned to Moffat County. MCM must provide the documentation required by Rule 4.03.1(1)(f) and 4.03.2(1)(g) for these roads to remain as permanent features. Prior to Bond release, MCM must submit this documentation and include it as part of the permit application through a revision. II. Hydrologic Balance - Rule 4.05 A. Small Area Exemptions (SAEs) Map 26 in the permit application shows the disturbed areas where the Division has previously approved exemptions from the requirement to pass drainage through a sediment pond or treatment facility, as allowed in Section 4.05.1(4). All calculations and demonstrations for SAEs are found in Exhibit 18 of the permit. Each exemption was granted based on: small area, no mixing of surface drainage with discharge from underground mine workings, and sediment ponds or treatment facilities are not necessary for the drainage to meet the effluent limitations of 4.05.2 and applicable State and Federal water quality requirements for receiving waters. The