2011-09-07_REVISION - C1994082 (2)

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• • Revegetation (Cover) Success • • Yoast Mine SL -3 February 2011 Phase!! Bond Release Request 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 II bond release is being requested for these bond release blocks at the Yoast 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 II revegetation success evaluations were based on the applicable success standard requirements spelled out in Chapter 22 of the Yoast 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 Chapter 22. The cover success standard and evaluation for success at the Yoast Mine is as follows. The cover success standard is based on a weighted average determination (based on the four premine vegetation type contributions to total acreage) for all hit adjusted herbaceous cover derived from sampling in the following four premine types in the extended reference area and represented by their premine contribution to total area: Aspen 24.4 %, Mountain Brush 48.9 %, Steep Mountain Brush 2.7 %, and Sagebrush 24.0 %. The all hit cover is sampled from the four native types in the reference area and after adjustments for woody plants, noxious weeds and no more than 10% relative cover of annual/biennial weeds, is weight averaged by the four representative native types to develop the cover success standard. For the Phase II bond release block, all hit cover is sampled and the resulting herbaceous all hit cover value is derived similarly by adjusting for woody plants, noxious weeds and excessive annual/biennial cover. In both the reference area derived standard and the Phase II reclaimed area, the adjusted herbaceous cover is herein referred to as the allowable herbaceous cover. The Phase II reclaimed area value will be no less than 90% of the cover success standard at 90 %statistical confidence. The composition and diversity evaluation will be based on an evaluation of no single plant species in the reclaimed area having greater than 60% relative cover (Test A) plus any two of the following: total species density comparisons between reclaimed and native areas (Test B), assessment of the distribution of species abundance among lifeforms in comparison to the reference areas (Test C) or an assessment of the presence of native species (Test D). Note that all species in the region are cool season so seasonality is not evaluated. See Tab 22 of the Yoast Mine permit for a detailed discussion of these evaluation methods. Vegetation sampling in the Phase II bond release parcel and the Yoast Mine extended reference area was conducted in July 2010 by ESCO Associates. Exhibit A shows the Yoast Mine Phase II bond release block. The 2010 vegetation monitoring report for the Yoast Mine Phase II bond release evaluation is included as Attachment E. The Phase II bond release 4