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Mr. Dan Mashews Divirion ofMinerak and Geology Page 4 require that culvertr be placed in a manner to promote conveyance of the derign floor and that all crtlverts be covered by compacted fzl! to a depth of 1 foot. Theefoe, ditch segmenU at culvert crowing /ocationr will need to be deeper than the minimum 2 ft. to avoid overtopping the mad Please ensure that culverts are property constructed to avoid overtopping the road and to avoid plugging or collapse and erosion ar inlets and outlets. Response: At culvert crossings, the installation of the culvert will requite that the immediate area be widened and deepened. All culverts will have a minimum of a two-foot cover and sloped to avoid sedimentation. 2. The `A"Pit r&de area rtability analyrir, Attachment 13-12, MWH letter report of Augurt 11, 2004 appearr to have been properly prepared However, we have a mntern bared on obrervations and abney readings I made on an inrpection of October 26. The following comment is fiam the DMG Inrpeclion Report issued 10-28-04. The A' Pit highwall eduction slope Aide area hat been regarded to a 3:1 dope per DMG recommendation, and rtabik'ty analyrir war provided within ecently rubmitted TA l9. 3:1 nape grade war verified with abney radingr (32%-34%J. Our concern is that the stability analyrir indicated that a dope of 3.5 horiZontad to 1 verticaljurt met (1.34J the required 1.3 rtabikty factor of safety. If the DMG abney level measurements indicating a 3 horizontal to 1 vertical shpe are accurate, the equied 1.3 facor of rafety may not have been achieved Please provide a surveyed As-Built cross section documenting the slope grade through the regarded slide area. If the slope is steeper than 3.5 horizontal ro 1 vertical, a revised stability analysis with the same fiicdon angle of21 degrees will need ro be provided, to demonstrate that the required factor ofsafety is met with the as-built slope. If the 1.3 factor ofsafety cannot be demonstrated for the slope as constructed, further field modification will need to be designed and implemented. Response: SCC understands the Division's concern regazding potential stability problems associated with steep slope final reclamation sites. It is SCC's observation that the previous "problem" azeas (on all three mine sites) have been encountered on buffer azeas adjacent to the highwall backfilled areas. Usually these areas have only had topsoil removed and the remainder of the material is in-situ. In particular, the "A" Pit slide area had pre-mining slopes varying from 2.25V:1H (44.5%) to 2.SV:1H (35.7%) and during mining only topsoil was removed. In order to reconfigure the slope to a grade less than 3V:IH additional area will need to be disturbed of overburden will have to be salvaged from other areas and laid in a veneer of varying thickness over the in-situ slope. The annual aerial photo and updated digital topography aze expected by December 31, 2004. SCC will provide the Division with an updated contour map of the "A" Pit slide azea in AutoCad format which should provide an accurate slope measurement. SCC will consult with the engineer who ptepazed the stability analysis to determine if the analysis was conservative enough to allow fora +/- 0.5 slope variation. If the slope needs to be reconfigured, SCC will discuss the issue with the Division prior to re-disturbing the slope. 3. In a letter ajJuly 12, 2004, the Division diected SCC to asters potential rtability probkmr associated with future steep dope final highwall reclamation sites The letter further equurted SCC to provide modified redamatian designs to include nape edudian, controlled compadian, or rock drain incorporation, as appropriate and necessary to achieve a static safety factor of 1.3. The requert as made in order ro minimize