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^. <br />a <br />,~ ''-. <br />fYesr Horizon Mine- 20UT Vegetation Samptirtg for Phase 3 Bond Refease <br />SUMMARY <br />Western Fuels Colorado, LLC (WFC}seeks Phase 3 bond release on reclaimed irrigated <br />Pasture {12T arees) and Drytand Pasture (22 acres) of its Ptew Horizon Mute (NH-2) near Nucla, <br />Colorado under the terms of a permit issued by the State of Colorado, Division of Reclamation, <br />Mining, and Safety {CDRMS}. WFC must demonstrate to CDMRS that vegetatton established <br />by WFC on the reclaimed lands meets standards for bond release. In June 2007, BIC7-logic <br />Environments! (BIQ-Logic) conducted vegetatiron studies on NN-2 reclaimed lands and nearby <br />reference areas, in support of Phase 3 bond release. This report presents an analysis of the <br />vegetation data for purposes of demonstrating adequacy of revegetation for Phase 3 bond <br />release. <br />Cover and production were sampled in the new Irrigated Pasture reference area and the dryland <br />Pasture reference area. These reference area values were used as the standard for vegetation <br />measurements in reclaimed areas. <br />For Irrigated Pasture reclaimed areas {128.6 acres), mean cover (87.2°l°} substantially <br />exceeded Q {51.7%, the target value for revegetation to be deemed successful, equal to 90% of <br />the standard). However, no statistcal comparison of the means acceptable to GDRMS is <br />possible because an insufficlent number of cover samples ware obtained in the Irrigated <br />Pasture reference area. It was not clear at the time of sampling which statistical procedure <br />would be used, and what the minimum sample size would be. Sampling was terminated after <br />15 samples to control fieldwork casts, but ultimately a minimum of 30 samples were required for <br />the appropriate statistical analysis. As a consequence, CDRMS considers that revegetation is <br />not demons#rated to be successful in 2007 for cover. Mean production in the Irrigated Pasture <br />reclaimed areas (3,712.6 Ib/acre} substantially exceeded 4 (2,261.3 Ib/acre}. A 2-sample <br />reverse-null t-test with 5atterthwaite appraximatlans of standard error and degrees of freedom <br />shaved that the reclaimed area mean exceeded Q, and revegetation is deemed successful in <br />2007 for production. <br />For Drytand Pasture rectatrrted areas {21.9 acres), mean cover had to be adjusted to mean <br />cover of countable live vegetation, to allow for CDRMS limits on the amount of cover of,annua! <br />plants allowed.for demonstration of Phase 3 bond release. The mean cover of countable live <br />vegetation in the reclaimed area {26.4%) was slightty less than Q {27.0%). Aone-sample <br />standard null #-test showed that rx>ver in the recaimed area was equal to or greater than Gt, and <br />• revegetation is deemed successful in 2DD7 for cover. Production in the Drytand Pasture <br />reclaimed areas {301.3 Ib/acre} substantially exceeded Q (135.3 IbJacre}. Because sample <br />adequacy was demonstrated in both areas, and the mean exceeds Q; then no statistical <br />comparison is necessary and revegetation is deemed successful in 2007 for production. <br />B/O-Logic EnvFrortmental <br />November 72, 2Eb7 <br />Attachment 1-3 <br />