2018-04-25_PERMIT FILE - C1981038 (2)

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~cr ~a~A~ _ ' -~ ~~ HARNER & ASSOCIATES INCORPORATED C303) 794-5201 5721 S. SPOTSWOOD ST. LITTLETON, COLORADO 80120 September 2b, 1986 C,. ,rado Westmoreland Inc. Attn: Kathy Welt P.0. Box 1299 Paonia, CO 81428 Dear Kathy, ~ ~<,r~ Z. Doc Date:1211112001 III IIIIIIIIIIIIIIII sss S EP :' 6 i966 We have reviewed the current literature concerning topsoil depth and vegetation establishment and can now make a recommendation concerning the amount of topsoil to be salvaged and used in the final reclamation. But first, we will include a brief review of the literature. The literature indicates that salvage and replacement of topsoil over spoil materia] greatly increases the performance of revegetation. The depth of topsoil required to enhance vegetation performance, however, depends upon the desired intent of the revegetation. Cook et al. (1979) made a general recommendation that at least 10 inches of topsoil be used to reclaim sites in the mountainous areas of Colorado. Barth (1984) noted that maximum perennial grass cover may be achieved with 20 inches of topsoil and that additional topsoil depth did not significantly increase grass production in the Northern Great Plains. Redente and others (1984) reported that total above ground biomas increased with increasing topsoil up to a depth of 35 inches over retorted shale. However 89 percent of the total production observed was achieved with 12 inches of topsoil and 92 percent was achieved with 24 inches of topsoil. Redente and others (1984) did note that shrub production consistently increased with increasing topsoil depth but species diversity, decreased with increasing topsoil depth. McGinnies and Nicholas (1980) in field trials at the Energy Fuels mine indicated that above ground biomass increased linearly with increasing depth up to 18 inches. Deeper topsoil depths were not evaluated, such that the "leveling off" effect was not noted. The literature indicates that topsoil depth can indeed influence plant community productivity composition and diversity. Therefore the depth utilized in the reclamation process should be selected that best suits the desired land use goals. The land use goals for the Orchard Valley Mine West site is to produce a permanent ,,di-verse vegetation • cover suitable for rangeland and wildlife habi To me these goals ~-~ we recommend that an average topsoil depth of 4 inches'~be returned to the reclaimed surface. Because the reclaimed su will be returned to