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,• r • • topographic sheet base) showing alluvium in these streams including valley bottoms and flood plain terraces. Identification of areas of existing or historic flood irrigation practice, vegetation which suggests sub- irrigation, and a discussion of regional flood irrigation practices in areas of similar or smaller drainage size for considering any potential flood irrigation must be included. In either case if a positive AVF determination is made then Sheridan Enter- prises must comply with 2.06.8(4) and 4.24. All demonstrations discussing material damage etc. must be quantitatively justified. Please refer to the June 11, 1980 OSM AVF guideline for further direction. 4.28 Coal Processing Plants and Support Facilities not Located at or Near the Mine Site or not Within the Permit Area for the Mine 1. Page N2-36 of the application states that the Loma Rail Loadout is isolated from all surface water runoff other than direct precipitation and irrigation waste water. This should be described in detail and demonstrated on a topographic map to indicate how the area is isolated from adjacent watersheds. 2. The proposed berms at the loadout are viable for sediment control however their size should be specified and a cross-section of a typical berm should be provided. The cross-sections in Figure 2.2-15 are not adequate. It must be demonstrated that any runoff will be contained in the loadout area. 3. A sedimentation pond must be constructed at the topographically lowest part of the Zoadout to contain all runoff generated from the loadout area. The applicant must submit a plan for the proposed design of the structure with supporting calculations demonstrating that it will contain the 10 year 24 your event and include an emergency spillway which will pass the 25 year 29 hour event. This is needed to comply with 9.28.3(4). A monitoring pro- gram should be implemented to determine whether discharge from the pond will require treatment. 9. What is the area west of the culvert and berm to be used for? What kind of drainage system exists in this area. 5. Please describe the irrigation wastewater ditch. Which .sources provide this flow? How far is the source from the loadout? Is the ditch isolated from the runoff from contiguous areas? 6. The applicant must supply a letter from the surface owned approving the intended post-mining land use of the loadout facility. 7. A detailed narrative must be provided of the backfilling, grading and abandonment plan to describe the method to be employed to obtain the pro- posed post-mining configuration. Please include an "approved manner" for the disposal of "coal like material" (page 2-37). A map of post-mining topography must also be provided. 8. A11 costs associated with the reclamation of the Zoadout should be included in the calculation of the bond. Please refer to item 2.05.4 N7 of this letter for listing of the required information. (11)