Laserfiche WebLink
Backfilling and Grading <br />After removal of mine structures and facilities and sealing of mine openings <br />were completed, mine disturbance areas were backfilled and regraded. EFCI <br />specifically designed backfilling and grading activities to meet several <br />objectives: <br />o Cover any coal seams or demolition debris with minimum of four (4) feet <br />of suitable material <br />o Eliminate highwalls <br />o Establish apost-mining configuration which complies with regulatory <br />requirements for long term stability and blends with surrounding <br />undisturbed and reclaimed areas <br />o Reestablish drainage patterns similar to those which existed in the <br />pre-mining environment <br />The design postmining topography developed by EFCI meets these objectives <br />while minimizing any additional disturbance and maintaining minimal gradients <br />consistent with surrounding natural slopes. <br />For the mine area, backfilling activities will involve reducing side-slopes in coal <br />stockpile areas, backfilling the mine portals and portal bench area if the portal <br />facilities are not retained, re-contouring the mine facilities area, and <br />reconstruction of the Magpie Creek diversion to meet applicable regulatory <br />requirements for permanent diversion structures. Backfilling will be <br />accomplished utilizing available on-site equipment including tractor-scrapers, <br />wheel-loaders and trucks, tracked dozers and motor-graders as appropriate. <br />Within the mine area, the design postmining topography will require handling <br />and placement of approximately 55,000 cubic yards of overburden material. The <br />resulting postmining configuration is illustrated by the Mine Area Postmining <br />Topography Map, (Map 28), and the Mine Area Premining and Postmining <br />Cross-Sections, (Map 7). <br />Establishment of the Magpie Creek diversion as a permanent diversion structure <br />will involve widening the channel, laying back the adjacent slopes and limited <br />placement of riprap materials. The permanent Magpie Creek diversion channel <br />has been designed to pass the peak flows resulting from a 100-year, 24-hour <br />storm event. Design calculations are presented in Exhibit 19, Drainage and <br />Sediment Control Ptan, and the diversion channel location and alignment are <br />illustrated by the Magpie Creek Diversion - As Built Drawing, (Map 25), and the <br />Mine Area Postmining Topography Map, (Map 28). <br />2.05.4-10 Revised 10/04/07 <br />MR-55 <br />