Laserfiche WebLink
a Phase II amended design for the drainage facilities at the existing <br />surface facility area of the Orchard Valley Mine. The operator also <br />completed a detailed stability analysis and redesign of the proposed <br />final reclaimed configuration for the surface facilities at the mine. <br />In order to ensure stability and control erosion on final graded <br />slopes, the Division has approved a post-mining topography of cut-and- <br />fill terraces at the main mine. These terraces are compatible with <br />the post-mining land use of grazing and meet all the requirements of <br />4.14.2(2) with the exception of 4.14.2(2)(a). Terraces will all <br />exceed 20 feet in width and range in width according to the reclaimed <br />configuration map series 6A-5. <br />In August 1986, the operator submitted a permit revision application <br />to construct a west portal facility in the East Roatcap Creek valley <br />at the Orchard Valley Mine. This application proposed the <br />construction of a new portal facility and haul road, because the <br />existing portals at the Orchard Valley Mine had been rendered <br />unuseable by an underground coal mine fire. The applicant proposed to <br />upgrade an existing public access road to serve as a coal haul road to <br />the proposed west portal bench, which will be constructed by a <br />balanced cut-and-fill method. The portal bench fill includes a <br />130-foot maximum height terraced earthen fill constructed across East <br />Roatcap Creek.. Maximum interterrace facial slopes shall not exceed a <br />2.5h:l.Ov (horizontal to vertical) slope gradient. A 48-inch concrete <br />culvert was installed beneath the cross valley fill to accommodate the <br />100-year flow of the East Roatcap Creek.. <br />The permit revision application included geotechnical specifications <br />documented. in the OVWM Appendix, Volume 6, prepared by Golder and <br />Associates, consultants to the operator. This appendix presents the <br />results of geotechnical investigations, stability analyses and <br />detailed engineering designs for the west portal bench cut and fill <br />and the accompanying upgraded haul road. The stability analyses are <br />based upon projected slope configurations and material mechanical <br />properties obtained from material sampling and laboratory analyses. <br />Stability analyses were completed for both the operational and <br />reclaimed configurations of the west portal facility area. Curing <br />final reclamation of the OVWM, the fill will be removed. The portal <br />cut will be backfilled with this fill and a slope ranging from 2.5:1 <br />to 1.5:1 (v:h) will be established. This slope will approximately <br />achieve the post-mine configuration. <br />During the 1993 permit renewal process, the Division identified some <br />concerns relating to the highwall reclamation plan. The Division will <br />notify the operator, within sixty (60) days of this permit renewal <br />decision date, of any changes to the reclamation plan that would be <br />required to ensure compliance with the applicable rules and <br />regulations. <br />XI. Revegetation <br />Information pertaining to vegetation baseline may be found on <br />pages 70-75, Part 2.04 of Volume 1, and in the Vegetation Appendix of <br />-35- <br />