2012-04-27_REVISION - C2009087 - Laserfiche WebLink

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Vegetation Type Allowable Herbaceous Cover on a first -hit basis' % of Pre - mining Area Brush 15.1 83.0 Sagebrush 44.7 17.0 Peabody Sage Creek Mine SL -1 Phase 11 Bond Release Request April 2012 ` Herbaceous cover adjusted by subtracting noxious weeds and annual/biennial plant cover in excess of 10% of the remainder. 2 Highest possible value with 90% confidence as explained above and detailed in Attachment E.. 2010 Mountain Brush Reference Area First -hit Allowable herbaceous cover 15.1 x 2 = 30.2% 2010 Sagebrush Reference Area First -hit Allowable herbaceous cover 44.7 x 2 = 89.5% 90 percent of the Cover Standard = 0.90 [0.83 X (30.2) + 0.17 X (89.5)] = 36.2% The 2010 Phase II bond release block (BRB) sampling at thirty random locations resulted in cover data that exceeded 90% of the standard (36.2 %). The figure for allowable cover in the 2010 Phase II bond release block (BRB) (37.5 %) is the result of subtracting tree, shrub and non - herbaceous cover (1.2 %), perennial noxious weed cover (0.44 %) and "excess annual/biennial cover" (0.5 %) from the observed first hit total vegetation cover of 39.6 %. The cover value for the Phase II bond release block (BRB) was greater than the cover success standard. A t -test of the null hypothesis that the Phase II BRB PSCM -2 allowable cover is indistinguishable from 90 % of the standard is as follows: This was conducted using the test of the null hypothesis (CDRMS 2005 revised rule, 4.15.11 (2)(b)): A t -test of the (traditional) null hypothesis that the Phase II BRB PSCM -2 allowable cover is indistinguishable from 90% of the standard is as follows: t = (37.5 — 36.2) /(14.2 /sqrt 30) = .501 Since critical t = 0.854 (one - tailed, alpha = 0.2, 29 df) and t is less than this critical value, the hypothesis that the mean is indistinguishable from the standard is accepted, and reclamation success for Phase II BRB PSCM -2 is demonstrated. 10