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'.I /.II ~~1 ~ l~l d. l.lai y ii:.nL li ~ :... ... ...... UII'n11I MF rJI Ur r1lU UFi n1 FFF S(N 111C 15 U Mnnlc I'a •.~.n r. F .:ru live Uura u~ Fia rch 12, 1!!Ai 423 Centennial rlu ild ing, 1313 Sherm an Street Oenvcr. Go brarlo 80203 Tcl (3031 839-3567 David C. Shelton Director TO: Torn Gi.17is, Rcclarrution Spccin.list ~ _~~ PROM: J.im Pr~n d2 cton, .Beni or Gcoloyi:;t RE: Review of Backfilling and Cra ng Asp is of Colorado Westmoreland, Inc.'s Orchard Valley Mine Plan Pursuant to your request, I have completed a review of the amended permanent program permit application submitted by Colorado Westmoreland, Inc. for the Orchard Va11c_y t'rnl hfine. This memorandum presents comments for your cons.ideratiorr rc:gardiny the backfilli.nq and grading aspects of that permit application. The surface facilities of the Orchard Valley Coal Mine sit astride a stair step series of cut and fill benches iiuilt upon a steep slope comprised of the Mesa Verde and Mancos shale formations. Colorado Westmoreland, Inc.'s amended anplication includes a request for variance from approximate original contour restoration requirements. Applicant proposes to partially backfill the area of the mine's surface facilities. No back filling is proposed for terraces north of the portal area, and the diversion ditch is proposed as a permanent structure. Ideally, all disturbed areas of the mine should be restored to the approximate original contour. The regulations of the permanent regulatory program do allow for variance in steep slope situations, providing that the conditions of Rule 2.06.5 and 4.27.4 are .satisfied. The primary mechanical concern for steep slope backfill situations, which holds whether or not a variance is granted, is expressed in Rule 9.27.3(3): "The person who conducts the surface coal mining operation must demonstrate to the Board or Division, using standard geotechnical analysis, that the minimum static factor of safety for the stabi li.ty of all portions of the reclaimed land is at least 1.3." The required analytical dennnstration of slope stability must be made For the proposed reclairnc~l conf.iyuraCion reynrrlless of whether a variance is granted under Rule 2. fi(,5, The criteria enumerated in Rule 2.00.5 for granting of a variance deal with Land use, sediment yeneration and surface drainage. As such, Jerry Zimpfer will have to assist you in judyiny Che application's merit in this regard. (cont'd) r,