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C - 13 - Backfillino and Gradi - Rules 2.05.3(6)(b i 2,05.3(9), 2.05,4(2)(a) and (c) lo, `' The applicant proposes to construct an excess spoil fill adjacent to each box cut. Utilizing its considerable experience from the adjacent ~ry ites, the operator projects an excess of approximately 7,8 million cubic yards of backfilled material. The mine plan proposes to accommodate approximately 3.3 million cubic yards in several excess F --''- spoil fills and to distribute approximately 4,5 million cubic yards _ ~~ throughout the 274 acre five-year plan's mined area, resulting in an ' 1 7 f Th' 1 ~,Y i ~~ } ~r~ ~~ • t. ; ~~~ ll, ~, 4: I ~ ~~ average rise in a evation of approximately eet. is genera ,_}~ backfilling and grading scheme would be approvabie, if an approvable ~.~t post-mining topography and an acceptable excess spoil structure design are provided within the application. ~ v _. ~ ~ _~ '~: I + •L~ L ij ~Z'~"';X~';: \ ~~, Our examination of the operator's proposed post-mining topography, as depicted on map number 14 and associated cross-sections, maps number 4A and number 48, has determined one unapprovable component of the proposed post-mining configuration. Cross-sections A-A', B-B', and C-C', each depict a Swale and a convex ridge paralleling and adjoining the upgradient boundary of the surface pit. This configuration, which reflects the downslope migration of dragline excavated overburden, results in a steepening of post-mine slopes relative to pre-mined slopes. The slopes on the upgrade side of the Swale, adjoining the highwall, and the downslope face of the ridge are both significantly steeper than the pre-mining slopes in those locations. Rule 4.14.2, entitled "General Grading Requirements", in its opening sentence, states; "(1) The final graded slopes shall not exceed in grade either the approximate pre-mining slopes or any lesser slopes approved by the Division based on consideration of the soil, climate, or other characteristics of the surrounding area," The applicant must amend the proposed post-mining topography to eliminate these over steepened slopes. The spoils in the final cut and adjoining cuts will have to be appropriately regraded in order to achieve an acceptable post-mining topographic configuration, whose ~ grades more closely approximate the original topographic contour, ` The applicant proposes to deposit the box cut spoil, and a portion of subsequent cuts' spoil, within engineered excess spoil disposal structures. The application, retying on considerable previous experience in the immediate adjoining areas, demonstrates that excess spoil will result from the proposed mining operations. The permit revision application includes, as Exhibit 19, a report of geotechnical investigation and fill embankment stability analysis, prepared by Golder Associates, consultant to the applicant.