2020-07-09_REVISION - C1981028 (12)

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Coors Energy Company: Keenesburg Mine Technical Revision 47 Modification of Reclamation Success Standards thickspike wheatgrass,Elymus lanceolatus) and two cultivated cool season perennial species (crested wheatgrass,Agropyron cristatum and intermediate wheatgrass, Thinopyrum intermedium) in the older reclamation. Only two of these six species (Indian ricegrass and thicksprike wheatgrass) are currently included in the seed mixture and only one of them (Indian ricegrass) is included at a seeding rate that would result in greater than 3%relative cover. 5 POST-MINING LAND USE Revegetation cover and production success standards are set at minimum levels to support the permitted post-mining land use of rangeland(i.e., grazing and wildlife use). These success standards remain unchanged by this revision. A diverse community provides a varied food source for cattle and wildlife and protects against pest or disease infestations that could impact a single-species monoculture. The species composition standard is set at a minimum level to represent a healthy vegetation community composition. TR47 does not change the overall goal of species diversity, nor does it change the goal of providing a vegetation community capable of supporting productive grazing and wildlife use. 5.1 Diversity Reclaimed plant communities at the Keenesburg Mine have greater species diversity, as well as greater grass diversity, than was observed in the OSRA data in 2000-2004 or in the undisturbed area monitored in 2019 (Table 4). Also, reclaimed land diversity is greater than would be expected from the seed mixture. On average, in 2019, the seven reclamation units monitored had over 24 non-noxious species observed across all transects including almost eight warm season perennial grasses and over three cool season perennial grasses. Table 4: Non-Noxious Species Richness Osgood Sand Un- Reclamation Areas 2019 Reference Area disturbed Area Seed Species 25 29 30 31 32 33 34 2000 2001 2002 2003 2004 2019 Mix Warm Season 8 8 9 8 7 7 8 3 3 3 3 2 5 7 Perennial Grass Cool Season 6 2 1 4 3 4 4 1 2 2 2 3 0 2 Perennial Grass Other Non-Noxious 13 15 15 11 9 9 19 2 11 6 8 5 20 1 Species Total 27 25 25 23 19 24 31 6 16 11 13 10 25 14 5.2 Grazing Value The value of a pasture for grazing is based on its herbaceous biomass production and the nutritional value of that biomass. Herbaceous production data are collected each year to determine if the reclamation meets the production standard. However, the biomass is not separated by species, it is only separated by growth duration (i.e.,perennial or annual/biennial). The allowable biomass production that is compared to the standard includes all non-noxious perennial biomass and can include annual/biennial biomass up to 10% of the total. 5 July 2020