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Seneca Coal Company <br />Phase 11 Bond Release Request <br />May2008 <br /> <br />Parcel Designator Total Veg. <br />Cover (x) <br />s <br />N <br />nmin <br />t <br />BRB-2 49.7 9.6 20 7 1.328 <br />BRB-3 47.0 11.7 30 11 1.338 <br />BRB-4 33.9 11.9 24 21 1.319 <br />Sagebrush R.r1. 64.7 7.8 15 3 1.345 <br />Mountain Brush R.~1. 79.1 8.3 15 2 1.345 <br />Sample point locations for the 2006 vegetation sampling program are shown on Maps 1, 3, and 4 <br />in the Seneca II Mine 2006 Revegetation Monitoring Report (March 2007) prepared by ESCO <br />Associates Inc. and submitted to CDRMS. <br />The revegetation success evaluations show that the cover standard was met for Phase II parcels <br />BRB-2, BRB-3, and BRB-4. The allowable cover value of 46.1 percent fox BRB-2 is well above <br />the reference area standard of 31.9 percent. Since the cover sampling met sample adequacy and <br />the reclaimed area (BRB-2) sample mean exceeds the standard, success is demonstrated and <br />statistical testing is not required (Rule 4.15.11(2)(a)). <br />The 45.1 percent allowable cover for BRB-3 is also well above the reference area standard of 31.9 <br />percent. Cover sampling was to adequacy, and the sample mean exceeded the standard. Success <br />is demonstrated without the need for statistical testing as per Rule 4.15.11(2)(a). <br />The BRB-4 allowable herbaceous cover value of 28.8 percent is slightly below the reference area <br />standard of 31.9 percent. Since the cover sampling met sample adequacy, aone-sided t-test with <br />alpha error probability of 0.10 was used to demonstrate that the reclaimed area mean is not less <br />than 90 percent of the applicable success standard with 90 percent statistical confidence (Rule <br />4.15.11(2)(b)). The equation specified in this rule was used for the test. <br />The calculated t statistic is: t~ _ (31.9 - 28.8)/(11.9/24) = 1.28 <br />The critical t value (table tvalue) = 1.319 (one-tailed, alpha = 0.1, 23 d.£). <br />8 <br />