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0 — s2 <br />Mm = (d -)z <br />Where: nm = minimum sample size <br />s = sample variance (n-1 degrees of freedom) <br />d = precision (0.10 for cover and production) <br />x = sample arithmetic mean <br />t = the (a=.10) t -table value for a 1 tail t-test, n-1 degrees of <br />freedom (infinite degrees of freedom may be used if n>30) <br />n =sample size <br />All such calculations were based on data from a minimum of fifteen samples. <br />NOTES ON THE COMPARISON OF DATA TO APPLICABLE REFERENCE AREA STANDARDS <br />Corrections for Noxious Weeds and Excess Annuals <br />Upon the formal comparison of cover and production data from reclaimed areas to applicable <br />performance standards, observed total all -hit herbaceous cover percentage and collected production, <br />must be adjusted for excessive contribution by annual / biennial species (i.e. no more than 10 percent <br />relative cover or production, CDMG 1995, Guidelines Regarding Selected Coal Mine Bond Release <br />Issues, 1(IV) A(4)). Herbaceous cover and production values used in such comparisons also must <br />exclude values for species present on the Routt County Prohibited or Restricted Noxious list or that are <br />listed as noxious by the State of Colorado (Colorado Dept. of Agriculture, Division of Plant Industry, Title <br />35, Article 5.5, 101-119, Lists A, B, and C of Rules effective December 30, 2015). For purposes of <br />assessment of reclamation adequacy, allowable all -hit herbaceous cover data from reference area <br />sampling is used as per SCC Mine permit provisions. <br />Upward Adjustment of the Steep Mountain Brush Cover Standard <br />Sample adequacy for total allowable all hit vegetation cover in 2015 was achieved for the reference areas <br />and BRB-3, the Aspen ERA, the Sagebrush ERA, the Mountain Brush ERA and the Western Wheatgrass <br />ERA, but it was not achieved for the Steep Mountain Brush ERA. <br />In consideration of the lack of a sample size sufficient to detect a 10% reduction in the mean with 90 % <br />confidence (i.e. sample adequacy), the upper limit of the possible values of the true mean (with a sample <br />size of 16) was determined for the 2015 Steep Mountain Brush ERA. This can be done either by <br />calculating the confidence interval for 90% confidence and adding it to the mean or by way of rearranging <br />0 <br />