2013-05-15_REVISION - C1982057 (4)

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The documentation for this sampling effort is presented in the Annual Reclamation Reports submitted beginning in the 1990s. Revegetation Success Cover Vegetation establishment will be considered acceptable if the cover of the revegetated area is at least 90 percent of the cover from the reference area or other standard with 90 percent statistical confidence (Rule 4.15.8). Phase Il bond release is being requested for 859.5 acres at the II -W mine. These lands have established vegetation that is at least two years old and are able to support the approved post- mining land use. Phase lI revegetation success evaluations were based on the applicable success standard requirements described in Tab 22 of the II -W mine permit, Rules 3.03.1(2)(b) and 4.15.8 and the Division's Guideline Regarding Selected Coal Mine Bond Release Issues (April 1995). Establishment of vegetation is demonstrated by meeting the appropriate cover success standard based on statistically adequate sampling. Species composition and representation of the species to meet final diversity requirements is addressed by the vegetation cover data and evaluations using species diversity assessments included in Tab 22. The cover success standard and evaluation for success at the II -W Mine is as follows. The cover success standard is based on a weighted average determination (based on the five pre -mine vegetation type contributions to total acreage) for all hit adjusted herbaceous cover derived from sampling in the following five pre -mine types in the extended reference area: 11% Aspen, 35% Mountain Brush, 31% Sagebrush, 13 % Steep Mountain Brush, and 10% Western Wheatgrass /Alkali Sagebrush. Sample adequacy based on all -hit values was achieved for the bond release area and each of the reference areas. Calculation of the 90 percent of the cover standard for the 2012 sampling is demonstrated below. Aspen Reference Area Allowable All -Hit Herbaceous Cover' = 48% Mountain Brush Reference Area Allowable All -Hit Herbaceous Cover' = 26.5% Sagebrush Reference Area Allowable All -Hit Herbaceous Cover' = 23.5% Steep Mountain Brush Reference Area Allowable All -Hit Herbaceous Cover' = 15.1 % Western Wheatgrass /Alkali Sagebrush Reference Area Allowable All -Hit Herbaceous Cover' = 22.3% ' Herbaceous cover adjusted by subtracting noxious weeds and annual /biennial plant cover in excess of 10% of the remainder 90% of the Cover Standard = 0.9 *[0.11(48 %) +0.35(26.5 %) +0.31( 23.5 %) +0.13(15.1 %) +0.10(22.3 %)] = 23.4 The mean allowable all -hit herbaceous vegetation cover sampled in 2012 for the bond release area was 24.8 percent, which exceeds the 23.4 percent required cover standard; thus demonstrating successful revegetation with respect to the cover standard. SL -5 -6