2008-08-13_REVISION - C1981013 (2)

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reference area production by a wide margin. In the final bond release report, the operator presented two separate t-test demonstrations for the 2005 rangeland production data. The first test was a two sample reverse null t-test, based on the sample size of 90 in the reclaimed area and reference area (each uq adrat treated as an independent observation). The second test was a two sample reverse null t-test, based on a sample size of 15 in the reclaimed area and reference area (each transect treated as an independent observation). Both tests are based on "corrected" quadrat data (undesirable component removed from the data from each quadrat prior to calculation of sample statistics). Both tests conclude that the reclaimed area production exceeds the reference area production; therefore, the Division accepts the data as a valid demonstration of success. Production data in 2006 was collected using thirty randomly located 0.5 m2 plots. Sample adequacy was not achieved using the standard formula for any of the four sampling units. As allowed by Rule 4.15.11 (2)(c), a reverse null approach was used. In both cases, the null hypothesis of equality was rejected; the alternative hypothesis (reference area mean less than reclaim area mean) was accepted. This was a statistical confirmation of what was intuitively obvious from the data. The t-tests demonstrated that the reclaimed area sample means in both the pastureland and the rangeland exceed their respective reference area sample means at the 90% level of statistical confidence, pursuant to Rule 4.15.11(2)(c). Production is considered successful for the reclaimed pasture and the reclaimed rangeland. Three undesirable species were encountered in the revegetation sampling effort. Canadian thistle is listed on the State's B list of noxious species and field bindweed is on the State's C list. Neither one of these species is listed on the Las Animas County noxious weed list. The operator also encountered a large crop of yellow sweetclover during 2005 in the reclaimed rangeland area. The operator subtracted out the cover value for these undesirable species in excess of 10% relative cover as suggested by the Division's 1995 bond release guideline It should also be noted that the summer of 2006 was extremely dry in Las Animas County. The vegetation sampling effort was undertaken during this period. The low 2006 cover and production sampling results reflect the lack of moisture. Arcadis representatives sampling vegetation, Golden Eagle Mine