2019-02-08_PERMIT FILE - C1981019A

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RULE 4 PERFORMANCE STANDARDS suitability of using native species at the mine site. Test plots were used to simulate the disturbance that would result from surface mining. The complete details of the four-year revegetation study are found in Exhibit 10, Vegetation Information. Also, in 1977 an additional shrub study was initiated in conjunction with the Soil Conservation Service, Upper Colorado Environmental Plant Center. Approximately 35 species of shrub seedlings from the Plant Materials Center were being evaluated for potential use in mined land revegetation. Field trials have been, and continue to be, an ongoing effort at Colowyo since these initial studies indicated above (1975 and 1977). The most recent evaluation of efforts to establish shrubs and trees in pre -2000 revegetation resulted in the following assessment by Cedar Creek Associates, Inc. (2006): "Given the assumptions presented, past and present shrub counts, as well as recent shrub mapping, it can be postulated that the planting of bare root shrubs and containerized trees from 1979 through 2000 can be considered a failure (<10% survival). Shrub populations or patches on an overwhelming majority of reclaimed surfaces [prior to 2000] are well below the [old] success standard of 1,000 woody plants per acre (except within fenced enclosures) and a majority of the surviving shrubs in open (unfenced) revegetation were not planted, but were apparently included in the seed mix (i.e. Big Sagebrush - Artemisia tridentata). There is no doubt that browsing by big game species, as well as competition from aggressive grass species such as smooth brome (Bromus inermis) and intermediate wheatgrass (Agropyron intermedium) have prevented germination and growth of shrub populations on pre -2000 revegetation. Therefore, future bare -root planting of shrubs on new and older reclamation is not recommended based on very poor performance in the past. Any effort to increase shrub densities on older (pre -2000) revegetation will prove to be very difficult and expensive with little or no chance for success given the present competition from established grass species and big game grazing pressures. Therefore, it is recommended that Colowyo continue discussions with the state agencies to alter, through technical revision, target land uses and bond release standards applicable to at least pre -2000 revegetation areas." In 2000, Colowyo Mine, along with the Seneca II and Trapper Mines, participated in a shrub establishment program identified as the "CSU/DMG Shrub Establishment Field Trials." This program is described below: Rule 4 Performance Standards 4-50 Revision Date: 11/27/18 Revision No.: TR -129