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Appendix A - Vegetation Sampling for Phase III Bond Release <br />LJ <br />• <br />Herbaceous biomass production data from the clipped quadrats were used to determine sample size <br />adequacy. During the 2005 sampling event, sample size adequacy for herbaceous production was <br />achieved with 15 transects (each representing the averaged value of six 0.1-square-meter quadrats) in the <br />AVF Reference Area and the Irrigated Pasture Reclaimed Area. <br />In 2005, sample adequacy was not achieved in the Rangeland Reference Area or the Rangeland <br />Reclaimed Area (15 transects per area) when the six quadrats per transect were averaged. Upon <br />completion of the 15 transects in each rangeland area, the required minimum number of transects, based <br />on the "wet" weight of the herbaceous production samples, was 41.8 in the Rangeland Reference Area <br />and 129.7 in the Rangeland Reclaimed Area. Evaluation of the data collected combined with visual <br />observation of the reclaimed area versus the reference area resulted in the determination that additional <br />transects would not influence the integrity of the data. Table A-12 summarizes the sample adequacy data <br />for herbaceous production plots with a sample size of 15 transects. The six randomly-located plot <br />locations collected within each strata (transect) can not be considered independent samples according to <br />the recently revised rules instituted by CDMG in September of 2005 (Regulations of the Colorado Mined <br />Land Reclamation Board for Coal Mining, revised 9/14/05) <br />Conducting enough additional transects in the Rangeland Reference Area to reach sample adequacy <br />would have been difficult because of the limited size of the area. Additionally, data collected to that point <br />already displayed herbaceous production four times greater on the Rangeland Reclaimed Area than on the <br />Rangeland Reference Area. The 2005 revised rules state that when sample size adequacy can not be met <br />after 30 samples and herbaceous production exceeds 90% of the production on the reference area, a two- <br />sample, one-tailed t-test employing a reverse-null hypothesis can be conducted to evaluate if the success <br />standard has been met. Because the regulations specifying 30 transect samples were not in effect in 2005, <br />the CMDG stated that rejection of the null hypothesis for each of two separate reverse null hypothesis t- <br />tests, one applied to 15 transects, and the other to the 90 sample plots, would be sufficient to validate the <br />finding that reclamation of the rangeland area was successful in 2005. This test incorporates the <br />Satterthwaite's approximation to determine the appropriate degrees of freedom The calculations and <br />approach required for this test are described below. <br />Step 1: Satterthwaite Standard Error <br />2 <br />SZbr ?•9*Srej? <br />SEsat = + <br />nbr nrej <br />Where: <br />SEsat = Satterthwaite Standard Error <br />sZbr = Bond release area sample variance <br />nbr = Bond release area sample size <br />s,f = Reference area sample standard deviation <br />nref = Reference area sample size <br />note: .9 is inserted in the formula because the standard is 90% of the mean <br /> <br />2215-Go1denEa& PH3BONO 2006 3-10-08.doc A-4