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Vegetation sampling in the BRB-1 Phase III bond release block and the Yoast reference areas <br />was conducted in July of 2012 by ESCO Associates and in 2014 by ESCO Associates and Cedar <br />Creek Associates. The 2012/2014 report of the findings for testing revegetation success for the <br />Yoast BRB-1 Phase III bond release evaluation is included as Attachment D — Revegetation <br />Success Supporting Documentation. The Phase III bond release block, reference areas and <br />random sample point locations are shown on Maps 1 - 4 contained in the 2012/2014 revegetation <br />success evaluation report in Attachment D. <br />As a result of sampling and analysis, successful revegetation for the parameters of cover, <br />herbaceous production, woody plant density (background and concentration areas) and <br />species diversity was demonstrated in both 2012 and 2014 vegetation sampling years. The <br />results of those demonstrations are summarized in the following sections. <br />COVER <br />The Yoast cover standard and success evaluation procedures are as follows. The cover success <br />standard is based on a weighted average value (based on the relative extent of primary pre -mine <br />vegetation type contributions to total acreage) for allowable all -hit herbaceous cover derived <br />from sampling in the approved extended reference area. The weighting contribution by type is <br />aspen 24.4%, mountain brush 48.9%, sagebrush 24.0% and steep mountain brush 2.7%. <br />Allowable all -hit herbaceous cover is determined from cover sampling in the Phase III reclaimed <br />lands and the native reference area with subtractions made for woody plants, noxious weeds and <br />cover of annualibiennial weeds in excess of 10% relative cover. The Phase III bond release <br />area sample value will be no less than 90% of the cover success standard at 90% statistical <br />confidence. In the following discussion and the bond release vegetation report attached, cover <br />for the reference area derived standard and the Phase III reclaimed area may be variously <br />referred to as allowable all -hit herbaceous cover or as allowable herbaceous cover. The <br />derivation of the allowable all -hit herbaceous cover for the Phase III bond release block and the <br />reference area types is included in the discussion and data tables in the 2012 and 2014 <br />revegetation success evaluation report included in Attachment D — Revegetation Success <br />Supporting Documentation. <br />SL -6 - 7 <br />