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volumes are very limited and there has been no evidence to date of any <br />surface instability on the adjacent coal refuse stockpile slopes. Minor <br />surface erosion from the coal refuse stockpile outslopes does result in <br />increased sediment deposition in the access road collection ditch. In <br />order to assure that the ditch continues to function effectively, EFCI, as <br />part of the regular maintenance program for the access road, periodically <br />cleans and grades the ditch to remove accumulated sediment deposits and <br />maintain full design flow capacity. <br />Upon completion of mining and related activities all temporary diversions <br />will be removed and the effected lands reclaimed when no longer required <br />for sediment control, as provided in the reclamation plans discussed in <br />Section 2.05.4, Reclamation Plan. Reclamation will consist of full or <br />partial filling of the diversion ditches with material from adjacent areas <br />consistent with the design post-mining drainage configuration, grading to <br />blend ditch areas with surrounding terrain, replacement of available <br />topsoil and reseeding using the seeding mixture presented as Table 33, <br />Proposed Temporary and Permanent Seed Mixtures and Seeding Rates. <br />None of the existing diversions will drain into underground mines. <br />Permanent diversions have been designed with sufficient gradient to ensure <br />continuous flow even if the ground surface is affected by subsidence. <br />Potential for subsidence will generally be limited and is not expected to <br />significantly impact surface structures as described in Section 2.05.6, <br />Mitigation of Surface Coal Mining Operation Impacts. Upon completion of <br />mining and related activities, EFCI will seal and backfill the mine <br />portals to prevent any significant exchange between surface and <br />groundwater systems. Details of portal sealing are discussed in Section <br />2.05.4, Reclamation Plan, and 4.07, Sealing of Drilled Holes and <br />Underground Openings. <br />Ci <br />4.05-1OR Revised -November, 1990 <br />