2011-11-08_PERMIT FILE - C1981041A (9)

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Should the parameter sample mean for the reclaimed area be less than 90 percent of the success standard, the following hypothesis testing formula will be utilized to demonstrate the difference is not statistically significant. Nm = (ta + tb) 2 (S 2 ) /( dQ) 2 Where: N = Minimum number of samples required s = Sample variance d = Precision (.10) Q = 90% of reference area sample mean or 90% of success standard t = the (a =.1) t -table value for a single tailed t -test with n -1 degrees of freedom t = the (a =.25) t -table value for a single tailed t -test with n -1 degrees of freedom Regardless of which formula is utilized a minimum of 15 samples will be collected for cover, production and woody plant density data within each reference and /or reclaimed area. Revegetation Success Criteria Determination of revegetation success in fish and wildlife habitat postmine land use areas will be based upon sample data comparison of reclaimed areas with reference areas. Reference area selection for this comparison will be based on slope aspect, position soils and vegetation similarities. This selection process will be made according to DRMS guidelines addressing the use of simple random sampling, proportional allocation or acreage weighted sampling. In 2010 the Operator requested Cedar Creek Associates, Inc. (Cedar Creek) re- evaluate the vegetative cover and production attained following multiple remediation attempts to combat cheatgrass invasion of reclaimed areas (Appendix 14 -11). Based on Cedar Creek's re- evaluation, success criteria for each sampling parameter is defined below: Vegetation Cover — Achieve 90% of the perennial vegetation cover of the approved reference area sample mean at the 90% confidence level. TR -60 14 -22 (Rev 04/11)