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Backfilling and Grading 1. Information on backfilling and grading is found in Sections 2.05.3 and 2.05.4, and on Maps 10, 11,12, 13, and 16, of the permit application. There were two sections of the permit area where backfilling and grading operations were concentrated: The Middle Creek Portal Pit and the Energy Mine No. 3 surface mine. CYCC proposed to backfill and grade the Middle Creek Portal Pit area. Sufficient material was available to achieve the designed post-mining topography from two existing overburden stockpiles and previously disturbed ground adjacent to County Road No. 179 above the portal pit area. In preparation for final reclamation, slopes were graded from 5h:ly, to gently sloping. The proposed slopes should be geotechnically stable and will achieve the approved post-mining topography. In addition, the final topographic configuration did not present any difficulties for topsoil redistribution or revegetation. The estimated time for backfilling the portal pit was eighteen weeks, weather conditions permitting. Backfilling and grading in the portal pit area completed during the 1984 construction season. At the Energy Mine No. 3 a total of 1,033,000 bank cubic yards fBCY) of overburden were removed. Of this overburden material, 250,000 BCY was temporarily stockpiled for backfilling the final cut. The remaining overburden material was backfilled into the surface pit within 180 days after coal removal. Final reclaimed slope configurations were graded to achieve adequate drainage, with the last area top soiled during 1986. The proposed post-mining topography appears geotechnically stable and should present no problems for top soiling and revegetation. The temporary overburden stockpile did not exceed 50 feet in height, had 1.Sh:ly side slopes, and was constructed in 8 foot lifts to provide for compaction and to increase geotechnical stability. Surface runoff was intercepted by the proposed pit above the stockpile location. Because the upper slope drainage was diverted away from the stockpile and the observed 1.25h:1v slopes in dragline spoils have had no failures, the designed temporary overburden stockpile was a stable configuration. This stockpile was used for final backfilling and grading at the end of the anticipated two year mine life. No acid forming or toxic forming materials have been encountered within the proposed permit area; therefore, no special handling will be required. The Division finds the proposed backfilling and grading plan is in compliance with this section. -33-