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Division's finding that species diversity is sufficient for bond release. Based on the comparison <br />shown in Table 3, the Division finds that species diversity on the bond release block has met the <br />requirements for Phase II and Phase III bond release. <br />Comparison of shrub stem density of bond release block with success criteria. As approved by <br />the Division, HGCC compared [he number of shrub stems counted in transects to the final bond <br />release regttiremen[ of 200 shrub stems per acre. Sample adequacy was not achieved for woody plant <br />density in 1996 or 1997: therefore, HGCC applied a "reverse null" t-test to each year of data for <br />demonstrating that reclaimed densities exceeded the 200-stem per acre requirement. This is a <br />statistically valid approach that was recommended to HGCC by the Division. The t-tests were <br />applied at the 9090 level of statistical confidence. In each case, the null hypothesis that stem density <br />was less than 180 stems per acre (9090 of the standard) was rejected. The hypothesis is rejected, that <br />is the 180-stem per acre minimum is met, if the calculated t-value is greater than the table t-value. <br />The comparison of the t-values is shown in Table 4, below. <br />Table d <br /> Com parison of t-values <br />Number of No. of stems t-value t-value calculated <br />Year transects per acre picked from counts of <br />(samples) (sample from t- stems on bond <br /> mean) table release parcel <br />1996 89 301 1.29 2.53 <br />1997 50 336 i.30 1.61 <br />Division's finding that shrub stem density is sufficient for bond release. As shown in Table 4, <br />the calculated t-values exceeded the table t-values, thus indicating shrub stem density on the bond <br />release block exceeded the 180-stem per acre minimum. Based on the comparison in Table 4, the <br />Division finds that shrub density on the bond release block has met the requirements for Phase II and <br />Phase III bond release. <br />Division's finding that revegetation is capable of supporting the postmining land use. The bond <br />release block has 7890 vegetative cover composed of a variety of life forms (grasses, fortis, and <br />woody shntbs-) and species. This cover appears to support the following wildlife that regularly has <br />been sighted (or sign found) on the block during inspections over the last few years: elk, deer, sage <br />grouse, small mammals, various water fowl and raptors. Livestock have inadvertently grazed on the <br />site numerous times. The seasonality of the vegetative species appears to be suitable for the post- <br />mining land use of livestock grazing, rangeland, and wildlife habitat. The bond release parcel's <br />requirements for vegetation production, species diversity, and shrub stem density were based on what <br />would be necessary for supponing the postmining land use. The bond release block has met those <br />requirements. Based on [he achievement of those requirements. and the observed wildlife and <br />livestock use of [he site, the Division finds that the revegetation on the bond release block is capable <br />of supporting the postmining land use. <br />Hayden Gulch Mine Page 9 May 25, 1999 <br />Phase II/III Bond Release <br />