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The Trapper Mine technical standards for cover were developed from range -site estimated pre and post mining soil <br />loss based upon lowest % cover, 1979-85, from premine areas. In effect, RUSLE evaluations were used to calculate <br />the amount of cover required to effectively control erosion based on premine estimates. The methodology to the <br />development of the Trapper Mine technical standards is discussed in Exhibit 14a of this approved PAP and <br />summarized below: <br />• Postmine Standard for Range Site A is 33% herbaceous cover and 19% litter cover giving 52% effective <br />cover. <br />• Postmine Standard for Range Site B is 29% herbaceous cover and 23% litter cover giving 52% effective <br />cover. <br />The Trapper Mine production technical standards for each range -site are based on the lower confidence limit of each <br />historical mean. <br />• Postmine Standard for Range Site A is > 62.39 grams/m2 (556.6 lbs /acre) to a 95% confidence <br />• Postmine Standard for Range Site B is > 42.49 grams/m2 (379.1 lbs / acre) to a 95% confidence <br />The diversity standard for this site will be successfully met when four species make up 60% of the relative permit <br />composition in the reclaimed site and no single species will contribute more than 40% of the relative composition. <br />The shrub standard for the Utah Tract will be established at 1,000 stems per acre. A statistical approach for woody <br />plant density presented in Rule 4.15.11 (2) will be used to demonstrate success. <br />Field sampling will meet a statistical minimum of 90% confidence with 10% precision. If sample adequacy is not <br />achieved, the reverse null approach may be used to demonstrate revegetation success [Rule 4.15.11(2)(c)]. Adequacy <br />of sample size will be determined using the following formula. (DMG Vegetation Guideline, page 20). <br />Nm=t S' <br />(d 32 <br />Where: Nm = Minimum number of transects necessary to sample within the prescribed precision <br />and confidence <br />S2 = Sample variance <br />d = Desired level of precision (0.1 for cover, production and 0.15 for WTD) <br />t = the (a = .10) t table value for a single -tailed t-test with (n-1) degrees of freedom <br />x = Sample arithmetic mean <br />Miscellaneous Areas <br />The revegetation success criteria for miscellaneous areas such as sediment ponds and light-duty roads will follow the <br />land use designations as shown on the Reclamation Plan Map (Map 29). The criteria for the land use in each <br />particular area will apply. <br />Maximum Recovery of Coal Resource <br />MCM plans to mine its coal resources in a manner that will ensure maximum coal recovery and will minimize the area <br />to be disturbed. No concurrent surface and underground operations are proposed. MCM plans to extract all coal <br />possible through the use of longwall and room -and -pillar mining systems. Further, a multiple seam extraction plan <br />will optimize recovery of all coal within the permit boundaries. <br />TR16-37 2.05-35.1 Revised 12/23/16 <br />