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t = The (a =.10) t -table value for a 1 tail t -test, n -1 degrees of freedom (infinite <br />degrees of freedom may be used if n >30) <br />n = Sample size <br />All such calculations were based on data from a minimum of fifteen samples. <br />NOTES ON THE COMPARISON OF DATA TO APPLICABLE REFERENCE AREA STANDARDS <br />Upon the formal comparison of cover and production data from reclaimed areas to applicable performance <br />standards, observed total all -hit herbaceous cover percentage and collected production, must be adjusted <br />for excessive contribution by annual / biennial species (i.e. no more than 10 percent relative cover or <br />production, CDMG 1995, Guidelines Regarding Selected Coal Mine Bond Release Issues, 1(IV) A(4)). <br />Herbaceous cover and production values used in such comparisons also must exclude values for species <br />present on the Routt County Prohibited or Restricted Noxious list or that are listed as noxious by the State of <br />Colorado (Colorado Dept. of Agriculture, Division of Plant Industry, Title 35, Article 5.5, 101 -119, Lists A and <br />B of Rules as replaced 2003). For purposes of assessment of reclamation adequacy, all -hit herbaceous <br />cover data from reference area sampling is used as per Seneca IIW Mine permit provisions. <br />It is also to be noted that the data from the five reference areas is weighted in accordance with the original <br />relative abundance of the types in the pre- mining landscape (11% aspen, 35% mountain brush, 31% <br />sagebrush /snowberry, 13% steep mountain brush and 10% western wheat). It was necessary to sample <br />each to adequacy (see above) but in the process of weighting, a reliable estimate of variance is lost. Thus <br />the reference area standard is thereafter in the process treated as a technical standard (i.e. without <br />confidence limits) and one - sample t- testing is used. <br />HYPOTHESIS TESTING APPROACHES <br />For formal hypothesis testing relative to Phase III Bond Release the following procedures were followed: <br />Cover and Production <br />Phase III Revegetation success for cover and production will be demonstrated by one of following <br />statistically approved approaches. Although the CDMG 2010 proposed rules revisions are not finalized at <br />the time of this report, it is ESCO's understanding that they will be by the time the second year of sampling <br />is complete and the final report is written. Therefore, hypothesis testing of BRB -1 relative to revegetation <br />success standards includes approaches found within the CDMG 2010 proposed rules revisions. <br />6 <br />