2021-08-06_PERMIT FILE - C1982056A (2)

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It is proposed that the stocking of woody plants within the reclaimed area be 1,000 stems per acre based on the following testable hypothesis: • The density of shrubs will equal or exceed 90 percent of a standard of 200 stems per acre in background areas and 2,000 stem per acre in concentration areas. Hay Cropland - Revegetation success for Hay Cropland will be determined by employing a performance-based standard. This standard is based on Routt County Historical Cropland Statistics for hay crop production. Table 1 lists hay cropland statistics for Routt County. The average yield for alfalfa and other hay crops for the last five years of the period of record (2004-2008) is 1.73 tons per acre. The performance standard used in the success evaluations will be based on the most current five-year average at the time of sampling. Reclaimed area hay crop production will be collected from the revegetated areas for the last two consecutive growing seasons of the extended liability period. Production may be collected from total harvest clip plots of one square meter, randomly located in the revegetated area. An alternative method is to weigh randomly selected bales in the revegetated hay crop field. In either case, sample adequacy will be calculated using the methods and formulas presented earlier in this section. Hay Cropland shall be deemed successful when the production value determined from the sample data in the reclaimed area is at least 90 percent of the performance standard derived from the Routt County Historic Cropland Statistics. Reclamation Sample Adequacy Assessment and Hypothesis Testing - Formal (statistical) hypothesis testing will be assessed for the Foidel Creek Mine reclaimed areas and the corresponding reference areas. Sample adequacy for cover within the reclamation area will be evaluated based on "First Hit" vegetation cover of vascular plants using the following expression: •t 2 S 2 nnz Fd�x )2 Where: nm = Minimum Reclaimed Area Sample Size s = Sample variance (n-1 degrees of freedom) d =Precision (0.10 for cover and production; 0.15 for woody plant density) x =Sample arithmetic mean t = The ((x=.10) t -table value for a 1 tail t-test, n-1 degrees of freedom (infinite degrees of freedom may be used if n>30) n = Sample size If the mean "First Hit" vegetation cover or herbaceous production of an adequate sample from the reclaimed area is less than 90 percent of the cover standard, then a one -sample t-test will be made in the following form to test the hypothesis of reclamation success for cover (CDRMS Coal Section, 4.15.11 (2)(b)): t =Q—x S- X Where: x = Reclaimed Area Sample Mean • Q = 90 percent of Standard Sx = Standard error of mean [ s / F ] RN08-05 2.05-117.3 03/12/10