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<br />4. Please address the potential for drainage from mine roof and <br />ribs in the South Portals area to build up behind the concrete <br />seals, eventually causing failure of the seals. If warranted, <br />amend the plan to provide for permanent drainage from behind the <br />seals, prior to backfilling the remaining portion of the portals <br />outby the seals. <br />5. The permanent drainage plan for the South Portal facilities area <br />includes riprap diversion channels that terminate at the lower <br />facilities area where "a hole will be cut in the former conveyor <br />culvert and grating installed to allow drainage from this area <br />to go to the river." Please provide a profile sketch of the <br />conveyor culvert to verify the design grade assumptions and <br />calculations in Appendix 14-6. If the culvert will not convey <br />design flows, alternative drainage designs will need to be <br />provided. <br />2.05.9(2)(d) <br />6. The South Portal reclamation plan narrative indicates that the <br />necessary 18" of non-toxic refuse cover to be used in <br />reclamation of the final graded RSRDA refuse slopes would be <br />obtained ~~from diversion excavation and excavation in the <br />current parking and preparation plant area." Sampling data <br />indicates the presence of some suitable soil material in these <br />areas, but it is not clearly established that a sufficient <br />volume of suitable soil material will be available within these <br />disturbance areas. Please identify an alternative borrow area <br />and provide documentation regarding the availability of <br />sufficient non-toxic cover material, in the event that <br />sufficient material is not available within the immediate South <br />Portal facilities disturbance area. <br />2.05.9(2)(e <br />7. Recent monitoring of revegetated areas, as well as more casual <br />observation, has indicated poor establishment of herbaceous <br />perennials in some areas. Specifically, the south facing slopes <br />of the CRDA-2 refuse area are stabilized by a dense stand of <br />fourwing saltbush and a few other shrubs, but the slopes are <br />essentially devoid of perennial herbaceous vegetation. <br />Likewise, major portions of the North Decline are dominated by <br />cheatgrass, with minimal perennial herbaceous cover. As noted <br />in the conclusion of the 1999 Vegetation Monitoring Report, <br />prepared by Savage and Savage, Inc., "species composition for <br />the majority of the reclaimed areas does not fulfill final <br />species composition success standards." Unless interseeding, <br />possibly combined with other mitigative measures, is undertaken <br />on areas with poor herbaceous establishment, final bond release <br />7 <br />