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• <br />• <br />the permit area. The SCS Form 5's may be found in Attachment 2 to this Tab. The use of <br />this technical standard is requested under 4.15.7(2)(d)(ii). Based on baseline vegetation <br />results and evaluation of the reclamation potential of the site, including changes in <br />landform and the anticipated topsoil replacement program, it is felt that the potential of <br />this series represents recovery of productivity levels compatible with the intended <br />postmining land use. The 6-12 percent dry (class determining) phase for grass hay was <br />selected as the most representative when considering the Nucla East area. This value is <br />4.0 tons per acre (annual yield) under a high level of management. Acceptable production <br />will be achieved when the production value determined for the appropriate irrigated <br />pasture reclaimed areas is not less than 90 percent of 4.0 tons per acre with 90 percent <br />statistical confidence. <br />The success standard for cover is based on the Level of premining ground cover (live <br />vegetation plus litter) determined from the 1987 baseline studies conducted within the <br />Nucla East study area (see Tab 10, Addendum 10 -3). The average live vegetation cover <br />determined from these studies was 71.8 percent and the litter value was 22.7 percent for a <br />total ground cover value of 94.5 percent. These values represent long term established <br />perennial vegetation and litter in the type, reflecting a reasonably constant value <br />because of historic irrigation and management. Fluctuations in vegetative cover are small <br />because irrigation has eliminated the climatic variation due to eratic precipitation <br />normally encountered in the semi-arid climate in the Nucla area. At the high levels of <br />production achievable under properly managed irrigated pasture, and specified in the <br />production standard, the vegetation and ground cover will be more than adequate to meet <br />the requirements of 4.15.1(2)(b). Noble (1963) in a paper on watershed rehabilitation <br />stated that research efforts showed that a 60 -70 percent ground cover (including plants <br />and litter) could effectively control surface runoff and erosion during heavy storms. <br />Therefore, the success standard for cover will be 95 percent ground cover with at least 72 <br />percent of this value comprised of live vegetation cover and the remaining 23 percent <br />comprised of litter. The litter component may be made up of litter and any live <br />vegetative cover measured in excess of the required 72 percent. The ground cover for the <br />reclaimed areas will be considered acceptable when the various cover components, as <br />specified above, are not less than 90 percent of these values with 90 percent statistical <br />confidence. <br />Drytand Pasture Type. Areas reclaimed to the dryland pasture type occupy locations where <br />the Travessilla-Pinon channery sandy foams complex (Map Unit Symbol 1E) and sagebrush <br />22 -32 Revised 07/25/91 <br />