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<br />Williams Fork Mines Prepared by: R. Reilley M.S. GISP <br />C1981044 5 November 2018 <br /> <br /> <br /> 28 <br />abandoned Eagle No. 9 Mine's Portal Excavation, depicted on Permit Map 25. The details of this <br />disposal plan are presented on Map 28 of the amended permit application, including a detailed <br />site plan and appropriate cross sections. Mining ceased at the No. 9 Mine in 1985. <br /> <br />The combined capacities of these two disposal areas represent the refuse generated by the <br />production of 60 million tons of coal, or about 15 to 20 years of mining. <br /> <br />The pile was designed with maximum facial outslopes of 4:1 (horizontal to vertical) and a <br />maximum height of 55 feet. A stability analysis performed by CTL/Thompson, Inc. ascertained <br />a minimum static slope safety factor of 3.6, assuming an angle of internal friction of 42º and <br />cohesion of 0 pounds per square foot. Confirming laboratory testing performed by the applicant <br />determined an angle of internal friction of 42º and a cohesion of 1,500 pounds per square foot. <br />Therefore, the safety factor determination presented within the preliminary stability analysis has <br />proven to be conservative in nature and exceeds the required 1.5 minimum acceptable static <br />slope safety factor required by the regulations. <br /> <br />The foundation area of the coal processing waste pile was prepared by removal of topsoil and <br />unacceptable subsoils and the installation of a gravel and tile subdrain and peripheral toe drain. <br />These drains prevent ground water from flowing into the waste material. Waste material was <br />placed in 24-inch horizontal lifts, compacted to 90 percent of the waste material's maximum dry <br />density, as determined utilizing AASHTO testing specification T-99. Compliance with the <br />certified inspection requirements of Rule 4.10.2 will assure compliance with the approved plans <br />and construction standards. <br /> <br />A. The Division proposed to re-approve plans for use, construction, and maintenance of a <br />coal mine waste disposal area (4.10.1(1)) through MR54, Solid Waste Dump Site Cleanup. <br /> <br />B. The disposal area was inspected on a regular basis by a qualified professional specialist <br />under the direction of the professional engineer, experienced in construction of similar earth and <br />waste structures. The Division approved inspection by this person as appropriate (4.10.2(1)). <br /> <br /> <br />VII. Backfilling and Grading <br /> <br />Rule 2.05.5 requires a plan/schedule for backfilling and grading in sufficient detail to allow the <br />Division to evaluate the feasibility of the proposed post-mining topography and the required <br />bond estimate. Volumes of material to be moved were presented on Table 63 of the permit <br />application, and the final backfilled topography is depicted on Map 29. <br /> <br /> <br />The applicant received approval of technical revisions in May of 1986 to extend development <br />work from the No. 5 Mine to the F seam of the No. 6 Mine. The waste rock produced was <br />approved for placement against the existing highwall of the 5A Portal. Designs for this <br />development rock placement are included in Exhibit 40. The total volume approved for <br />placement is 12,000 cubic yards.