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1'., y~_ Ninc ~Prelimiuary Adequacies irw •~ Grand Mesa Coal Co. - Red Chnyon Mine May 8, 1981 The applicant should ana.iyze the critical worst c.,se slope section of the enlarged proposed fill using a sophisticated mathematical technique, such as the modified bishop's method utilized by Armstrong 6 Assoc., Inc., in their earlier analysis. Pfechanical properties used in the earlier analyses are probably representative, but should be reviewed by the professional preparing the new analysis to ascertain their appropriateness. In keeping with the Division's request during past reviews, the applicant will have to install appropriate piezometcr/test wells to monitor yround water quality and elevation above, within anr7 below the propo.scrl refuse disposal site. 2.05.4 Reclamation ('la 2.05.4 (2) (a) Reclamation Timetable 1. The application states that reclamation of ttre waste disposal pile will involve a continuing cycle of overburden and topsoil stripping and replace- ment. The applicant should provide estimates of the acreage to be disturbed by various phases of the reclamation process during each year of the permit term. This would include projections for ncrcage from which topsoil and overburden has been stripped, area of active disposal, area backfilled, topsoiled, and area reseeded each year. 2. The applicant states that specific dates Cor the various reclamation activities are dependent upon the rate of fill. Rowevcr, projections on waste disposal requirements during each year sfrould be made far enouyh in advance to allow for topsoil salvage and redistribution to be carried out during the summer and fall. Seeding and mulching operations should be carried out in the late fall, to the extent possible, or in the spring, not "from late fall to early spring", as is stated in the application. 2.05.9 (2) (b) Reclamation Costs This section appears to be complete. The Division has not yet completed the detailed review. Comments may be forthcoming as the review progresses. 2.05.9 (2) (c) Backfillin4 and Grad 1. Any proposed overburden stockpiles (other than the waste disposal pile and the k2 mine bench) should be more clearly indicated on the proposed Surface Disturbance Map. A stockpile is referenced in relation to 6ack- filling the proposed sediment pond, but evidenti~J the stocY.pile boundaries blend in with the contour lines on the map. 2.05.9 (2) (c) Topsoil (Redistribution) I. It is stated in section 2.05.3(5) of the application that topsoil will be replaced at a depth of 6 inches in the refuse disposal site. The applicant should indicate the proposed depth of topsoil redistribution within the areas disturbed by "D" portal development and the proposed sediment pond.