2015-10-13_REVISION - C1981014 (12)

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For each area evaluated, a minimum of 30 forage production transects were collected as required by the CDRMS regulations pertaining to final bond release. After clipping, the harvested plant materials were dried in a drying oven at 105 degrees C until a constant dry weight (+/- 0.1 gram) was obtained. In the discussion of the results, these data are presented in both grams and pounds per acre. Species Diversity. The Southfield Mine Permit contains two species diversity standards. One requires that the four dominant species cannot contribute more than 80 % of the total relative cover and a second which relates to the contribution of the warm season grass species to the plant cover. In order to standardize the definition of what species are warm season grasses, we followed the recommendations made by Ms. Binns and used the USDA Plants website to identify warm season (C-4) grass species which are identified in Table 1, Southfield - Plant Species List. The second species diversity standard requires that the reclaimed areas at both the Southfield Mine and Southfield Loadout areas must be equal to or greater than the number of warm season grass species possessing three percent or greater on the four reference areas. Statistical Methods. As required by the Division's regulations at Rule 4.15.11(2)c, it is not always necessary to achieve sample adequacy for reclamation monitoring for Phase III bond release sampling efforts provided that the success standard has been achieved, and/or the "reverse null" hypothesis is used and at least 30 transects have been collected. All of the data collected in this evaluation were analyzed for sample adequacy to determine whether the sample adequacy requirements had been satisfied. The sample adequacy formula contained in the CDRMS regulations in Rule 4.15.10(2)(a) was used, wherein a precision of 0.10 was used for plant cover and forage production and a precision of 0.15 was used for shrub density. The CDRMS has historically used different sample adequacy formulas over the course of their regulatory program. Page 15 of the Vegetation Guideline says that the "t -value" which is to be used in the sample adequacy formula is to be "1.64 (which is the t table value for a double - tailed t test with infinite degrees of freedom at the 90% confidence interval)." Rule 4.15.10(2)(a) states that the "t -value" in the formula is "the (alpha=0.10) t -table value for a 1 tail t-test, n-1 degrees of freedom ... " Page 20 of the Bond Release Guideline says that the "t -value" in the sample adequacy formula is "the (alpha=0.10) t -table value for a single tailed t- test with (n-1) degrees of freedom." Therefore, as used in this evaluation, the t -value for a one - tailed t-test was used in all statistical sample adequacy calculations. On the various reclaimed blocks and reference areas sampled in this evaluation, all of the field data was analyzed in the field for sample adequacy both in terms of "total plant cover" and "allowable plant cover" to determine whether sample adequacy was achieved prior to leaving the site. For plant cover and forage production sampling, a minimum of either 15 or 30 samples were collected and the data analyzed for sample adequacy before the "reverse null" statistical approach was applied.