2011-04-06_REVISION - C1980005 (3)

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Seneca 11 Mine March 2011 SL-5 Phase 11 Bond Release Request • C? The Seneca II Mine cover success standard and evaluation for success is as follows. The cover success standard is based on a weighted average determination (based on the two premine vegetation type contributions to total acreage) for first hit adjusted herbaceous cover derived from sampling in the following two premine types in the approved Seneca II Mine reference areas and represented by their premine contribution to total area: Mountain Brush 83% and Sagebrush 17%. First hit cover is determined from cover sampling in the above two 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 to determine the allowable first hit herbaceous cover, is weight averaged by the percent contribution of the two representative native types to develop the basis for the cover success standard. This basis value is multiplied by two to arrive at the cover success standard. For the Phase IT bond release block, all hit cover is sampled and the first hit herbaceous cover value is derived. The allowable first hit herbaceous cover is determined 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 derivation of the first hit allowable herbaceous cover for the Phase II bond release block and reference areas is included in the discussion and tables in the 2010 revegetation success evaluation report in Attachment E - Revegetation Supporting Documentation. The Phase II bond release block value will be no less than 90% of the cover success standard at 90% statistical confidence. Vegetation sampling in the Phase IT bond release block and the Seneca II Mine reference areas was conducted in July 2010 by ESCO Associates. Map 1 Phase HBond Request Areas, shows the Seneca II Mine Phase II bond release block. The 2010 revegetation success evaluation report for the Seneca II Mine Phase IT bond release evaluation is included as Attachment E - Revegetation Supporting Documentation. The Phase II bond release block, reference areas and random sample point locations are shown on Maps 1 and 2 of the 2010 revegetation success evaluation report. Table 1 provides a summary of the cover attributes for the Phase II bond release block and the mountain brush and sagebrush native types in the reference area. Table 1 also provides the 6