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DETERMINATION OF SAMPLE ADEQUACY <br /> Sample adequacy for the data collected was evaluated based on total allowable live foliar herbaceous <br /> cover using the following expression: <br /> nmin = t2—S2 <br /> (dk)2 <br /> Where: <br /> nrnin= minimum sample size <br /> s2 = 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 freedom (infinite <br /> 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 DEVELOPMENT OF REFERENCE AREA—BASED PERFORMANCE 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 listed as noxious by the State of Colorado (Colorado Dept. of Agriculture, <br /> Division of Plant Industry, Title 35, Article 5.5, 101-119, Lists A, B, and C of Rules effective December 30, <br /> 2015). For purposes of assessment of reclamation adequacy, all-hit herbaceous cover data from <br /> reference area sampling is used as per SPL Mine permit provisions. <br /> Area Weighted Cover Performance Standard <br /> In order to arrive at a performance standard for cover, as provided for in the permit, the data from the four <br /> Yoast Mine ERAs are weighted in accordance with the original relative abundance of the types in the pre- <br /> mining landscape (24.4% Aspen, 48.9% Mountain Brush, 24.0% Sagebrush/Snowberry and 2.7% Steep <br /> Mountain Brush). In the process of weighting, a reliable estimate of variance is lost. Thus, the reference <br /> 5 <br />