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Peabody Sage Creek Mine <br />SL -3 Phase 111 Bond Release Request <br />July 2014 <br />Table 6. 2010 and 2011 Data and Sample Adequacy Summary for Background and <br />Concentrated Area Woody Plant Density, Phase III BRB PSCM -1. <br />Woody Density Area <br />Woody Density <br />s <br />N <br />N,Y,i„ <br />t <br />and Sampling Year <br />(stems /acre) <br />Background DensityT <br />805.3 <br />1404.3 <br />30 <br />233 <br />1.311 <br />2010 BRB PSCM -1 Phase III <br />Concentrated Area Density <br />2092.2 <br />1400.2 <br />50 <br />34 <br />1.299 <br />2010 BRB PSCM -1 Phase III <br />Background Density <br />732.5 <br />1104.8 <br />30 <br />174 <br />1.311 <br />2011 BRB PSCM -1 Phase III <br />Concentrated Area Density <br />2703.3 <br />2666.9 <br />50 <br />122 <br />1.299 <br />2011 BRB PSCM -1 Phase III <br />2010 Woodv Plant Density Success Evaluation <br />The background density of 805.3 stems per acre observed in the 2010 BRB PSCM -1 Phase III <br />bond release area exceeded the 180 stems per acre performance standard. The mean of 2,092.2 <br />stems per acre observed in the concentration areas also exceeds the 1800 stems per acre <br />performance standard. The combined total aerial extent of woody density concentration areas <br />was 229.2 acres, or approximately 22% of the BRB PSCM -1 Phase III bond release block (1028 <br />acres). Hence the standard that there would be at least 5% of the Phase III BRB block with at <br />least 2,000 stems per acre (90% of the standard equals 1800 stems per acre) has been met for <br />2010. <br />A reverse t -test asserting that the 2010 BRB PSCM -1 Phase III background woody plant <br />density is indistinguishable from 90% of the standard is as follows: <br />Y — (0.9 * technical standard) <br />t� _ <br />15 <br />