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<br />this sampling was 43.9 prrcent (Table 1, Appendix 22-i). This value will become the success <br />criteria value and will be compared to the vegetative cover values for the newly revegefated <br />areas where Rule 4.15.10 applies. The two areas will be comparable when the vegetative cover <br />values for the newly revegetated areas are at least 90 percent of the cover value determined <br />,.from the 1988 cover sampling (43.9 percent) with 90 percent statistical confidence. <br />Production. A technical standard as opposed to use of the reference area is proposed for the ,~- <br />revegetation success standard for production. This standard is to be based on the potential <br />productivity of the dominant soils present_on_the_New_Norizon 1 Mine permit area. Potential,; <br />productivity values have been determined by the Soil Conservation Service (SCS) and are <br />included in the soil__survey of Western Montrose and San_Migue--Counties_ presently being <br />~,~,~ "published. The more detailed Nucla Mine Soil Survey (Tab 9) identified the Shavano and <br />^'y~ Persayo soils as the most prevalent and information on potential productivity from the SCS <br />survey was correlated with these soils. The potential productivity of the Shavano and Persayo <br />series was taken from the most recent Soil Survey_Interpretation Sheets (SCS Form 5) from the <br />SCS soil survey noted above. The Shavano series occupies approximately 73 percent of the <br />affected area and has a potential production in favorable years of 500 Ibs acre. The Persayo <br />series occupies the remaining 2~ercent and has a potential production in normal years of 250 <br />Ibs/acre. <br />The production standard for reclaimed areas is as follows.- All dryland pasture areas and the <br />rangeland areas receiving ten 10) inches of topsoil will have acceptable herbaceous production <br />when the production value determined for the reclaimed areas is not less than 90 percent of 500 <br />r - <br />Ibs/acre with 90 percent statistical confidence. " The 500 Ibs/acre value is to be used for these <br />leas because Shavano soils will provide the majority of the replaced topsoil. The remaining <br />reclaimed areas (excluding any yet to be reclaimed pre-law areas or areas previously mined and <br />reaffected by current operations as specified in 4.15.10) will be compared to the potential <br />productivity for the Persayo soils at 250 Ibs per acre. Herbaceous production for these areas will <br />be considered acceptable when it is not lessn 90 percent of 250 Ibs per acre with 90 percent <br />statistical confidence. As specified it 1_S,SO;~previously mined areas reaffected by current <br />-mining operations need not be evaluated for production. Exhibit 22-1 "Postmine Vegetation Map <br />-New Horizon 1 Mine" illustrates the areas reclaimed as dryland pasture, as rangeland receiving <br />ten (10) inches of topsoil, and as other reclaimed rangeland areas. A technical standard for <br />production is appropriate because of a lack of an adequate reference area representing the <br />postmining land use of dryland pasture or rangeland where herbaceous species will dominate. <br />The above technical standard reflects the potential productivity of the soils replaced in the <br />reclaimed areas and the climatic conditions of the general area. <br />22-11 <br />