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MEMO <br />(4) <br />Q - x <br />t <br />_ <br />SIX <br />Where: <br />x = <br />Bond Release Block sample mean <br />Q <br />= 90% of standards <br />Sx <br />= Standard error of the mean [S/ V n ] <br />S— <br />Sample size deviation <br />n = <br />sample size <br />t <br />= Calculated t value <br />c <br />t <br />= Table t value <br />t <br />Following removal of the undesirable species component, a standard null hypothesis t-test (Equation 4) <br />was performed to determine if the reclaimed area sample mean allowable cover (25.3%) was at least 90% <br />of the reference area allowable cover (36.9%) with 90% statistical confidence. The test resulted in a <br />rejection of the null hypothesis that the reclaimed area sample mean was greater than or equal to 90% of <br />the reference area sample mean, indicating that cover requirements were not met. <br />Mean absolute vegetation cover was higher in the reference area due to more robust growth of perennial <br />grasses and the presence of shrubs in the reference area that were not represented in the reclaimed area. <br />Specifically, the mean absolute number of hits for perennial grasses in the reference area was 15.93 <br />versus 10.87 in the reclamation area. For shrubs the comparison is 4.14 for the reference site and zero for <br />the reclaimed site. The largest individual species difference was the grass, blue grama (Bouteloua <br />gracilis), with mean cover of 11.60 on the reference area but just 0.47 on the reclaimed area. <br />Production <br />Average production in the Rangeland Reference Area was 37.1 g m-2, compared to 29.3 g m-2 in the <br />Rangeland Reclaimed Area. The difference in production between the two sites is largely attributable to <br />differences in forb production: the Rangeland Reference Area produced 9.96 g m-2 forb biomass (26.9% of <br />total production on this site), while the Rangeland Reclaimed Area produced 3.67 g m-2 (12.5% of total <br />production). <br />A standard null hypothesis t-test (Equation 4) conducted on mean production values in each site resulted <br />in a rejection of the null hypothesis that mean production on the Rangeland Reclaimed Area is 90 percent <br />or more of the Rangeland Reference Area mean production, indicating that production cover requirements <br />were not met. <br />Both cover and production test results are shown in Table 1. <br />Table 1 Golden Eagle Mine Phase III Bond Release Results: Mean allowable <br />vegetation cover and production in the Rangeland Reference Area <br />and Rangeland Reclaimed Area <br />Mean Allowable Cover (%) I Production (g m-2) <br />arcadis.com Page: <br />4/6 <br />