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The null hypothesis being tested would be that the bond release block mean (µ) was less than or <br />equal to 90°l0 of the standard, stated as H°: µ < O, If fc was greater than the 1-tailed t table value <br />for alpha error probability of .20, with (n-1) degrees of freedom (infinite degrees of freedom may <br />be used if n>30), then Ho was rejected, and revegetation would be deemed successful. <br />For the above (one-sample) t-test, it is necessary to have achieved sample adequacy in the <br />reference area sampling. Were adequacy NOT to have been achieved in the reference areas, <br />then the more complex calculations associated with atwo-sample t-test (CDMG rules) are <br />undertaken. <br />Cover was addressed in hypothesis testing as percent absolute all-hit herbaceous vegetation <br />cover as adjusted for any contribution of noxious weeds, and excessive contribution by annual / <br />biennial species (CDMG 1995, Guidelines Regarding Selected Coal Mine Bond Release Issues, <br />1 (IV)A(4)). <br />Pertormance Standards <br />COVER and HERBACEOUS PRODUCTION: For purposes of comparison only, cover and <br />herbaceous production performance standards were calculated in accordance with procedures <br />• contained in the Yoast permit. Aline that indicates 90 percent of this standard has been placed <br />on Figures 1a and 2 for informational purposes. At such time as bond release is formally sought, <br />revegetation will be considered successful for cover when mean cover for a bond release block is <br />at least 90% of the calculated success standard or approved technical standard. <br />WOODY PLANT DENSITY: For purposes of comparisons in this document, general (background) <br />woody plant density at the Yoast Mine is evaluated using a technical standard of 200 shrubs per <br />acre. Shrub concentration areas such as may be included in eventual bond release blocks are <br />judged by a standard of 2000 stems per acre. <br />Climatic Data <br />Precipitation data were collected at the nearby Seneca IIW Mine during the period 1990 through <br />2006. Since the data record for Seneca IIW exists for only a relatively short period, the long term <br />average monthly precipitation data from the Western Regional Climate Center (WRCC) for the <br />nearby town of Hayden (56 years) was used as an appropriate base for comparison. Information <br />on degree-days was based on temperature data from met station 2 at the Seneca IIW Mine. <br />I <br />7 <br />