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• 7.2 Proposal by Trapper Mine to Exclude Drill Seeding oPAppmved Grass Species in our 1991 Derringer Pit Topsoil Replacement Area Trapper Mine proposed to modify its approved seed mixes (RSA, RSB and RSC) in the 1991 Derringer pit replacement area to exclude drilling of perennial grass species. The area is comprised of approximately 11 acres of range site A, 35 acres of range B, and 6 acres of range site C (52 total acres) (see Map 7-1). If approved, both range site A and B would be drilled with approved forb and shrub species only and range site C with forbs only. The motivation behind this proposal is to encourage woody plant establishment on reclaimed azeas by reducing competition from grass plants. Topsoiling of the area will be accomplished entirely through live haul transport. Vegetation sampling will be conducted each year for five years on each range site to evaluate % cover, herbaceous production, and woody stem densities and reported to CMLRD in Trapper's annual report. Appropri- ate remedial action will be taken to control problematic noxious weeds, if necessary, as outlined in our current mining and reclamation permit. Appropriate conservation prac- tices will be performed on the area just as is performed on seeded areas (e.g. topsoil drag- ging, diversion ditch est., gully repair, etc.). Trapper realizes the establishment of this plot does not allow any exception from meeting the reclamation requirements outlined in Section 4.15 of the Colorado regulations. How- ever, it may provide an alternate method for increasing woody plants on reclaim areas while meeting other appropriate vegetation measurements. 73 Proposal to Reduce Allowable Topsoil Amounts on Reclaimed Rangeland Areas. Trapper proposes to modify permit page 4256 "topsoil replacement" to allow for areas less than 5 acres in sue to have topsoil depths replaced to a minimum of 6 inches. This request is based on a recently completed study at Trapper Mine by E.F. Redente, et.al. entitled "The influe~tce of topsotl depth on plant community dynamtcs of a seeded site in Northwest Colorado" (attached}. The report concludes that 10-year-old reclaimed areas with 6 inches of topsoil are the most productive, diverse and have the greatest woody stem densities when compared to adjacent plots with 12, 18 and 24 inches of topsoil. Trapper does not propose to change the overall topsoil amount on reclaim azeas, however would consider establishing relatively small areas (< 5 ac) at reduced topsoil rates to pro- vide amosaic of vegetation response throughout the reclaimed plant community. Areas replaced at 6 inches of topsoil may contribute significantly to the overall revegetation suc- cess as determined in Section 4.15.7 and 4.15.8 of the Colorado Mined Land Reclamation Board Regulations for Coal Mining. 7.4 AOC Determination Trapper Mining Inc, requests the Division make a preliminary determination regarding approximate original contour achievement for Trapper Mine. As previously discussed (7!31!90 Cones), Trapper is submitting to the Division 1) a current postmine topography map, 2) representative landform cross sectional profiles (see Map 7-2 Postmining Topography) which contain pre-mining, approved and actual configuration information for comparison, and 3) channel longitudinal profiles with both approved and actual configurations.