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Preliminary Adequacy Review Wolf Creek Technical Revision (No .7) Seneca II Mine (File C-005-80) 1) Rule 4.05.3(6)(b) requires that all channels be designed with 0.3 foot of freeboard. Channel design calculations presented in tabs 7 and 12 do not take this amount of freeboard into account. The channels should be redesigned to incorporate the required freeboard. 2) The use of vegetal retardance class 'B' (Barfield et al, 1981) does not appear appropriate. Specifically, it is the Division's position, based upon sampling and experience at similar sites that vegetation sufficient to control erosive velocities may not be established for 3 to 5 years, if ever. Peabody should propose other methods (in addition to revegetation); specifically riprap, contouring, matting, energy dissipators or other measures for achieving non-erosive velocities in the reestablished channels. 3) The Manning's N values of 0.077 and 0.063 appear to be too high. Peabody should reevaluate the roughness coefficient of the reclaimed channel, and provide supporting evidence for the N values selected. 4) Stipulation 3 of the September 25, 1984 Wolf Creek Permit Revision Approval requires the applicant submit a "...detailed plan for erosion control...". Based upon comments 2 and 3 above, the Division does not feel that this stipulation has been adequately addressed. Additional information to satisfy comments 2 and 3 above should resolve this concern. 5) Page 7.5 references Appendix 12-1 for "...Specific Design of Drainage Controls During Mining..." Appendix 12-2 lists culvert sizing calculations, however Appendix 12-1 was not submitted. 6) An unnamed road is referred to on Page 12-7, second paragraph. Will this road be abandoned back to its intersection with Road E6? If so, what is the reclamation schedule for this road? 7) In the third paragraph of Page 12-7 reference is made to Roads ElA and E4A. These roads should appear on Map 12-1 "Operation Plan", but are not included on this map lZonfls A-~/+~ ~i7 Fh/J V~9../jn ~, r</ S.. n..,>/q/ ••^T o^- •Snp /~-~ 8) Table 12-3a lists culvert specifications. This table indicates that culverts 216, 288 and 346 are undersized by 6 inches or more. Culverts 356 and 366 are slightly (1" to 3") undersized. The permittee should resubmit resized designs. 9) The underdrains proposed to be constructed beneath the Wolf Creek Fill are being deposited by gravity segregation, using dragline spoil placement. Site inspection has determined that this technique appears to work in the upper and internal segments of the fill, which had been constructed as of last summer. The Division is concerned, that the use of this gravity segregation technique in the portion of the underdrain immediately adjacent to the toe of the fill might compromise the facial stability of the fill. Any reduction in the