2007-06-01_PERMIT FILE - C1981019A (2)

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~. Since the initial sagebrush reference area had been shown to be statistically comparable to the premine sagebrush 'community, Colowyo located another sagebrush reference area which was statistically comparable to the existing reference area. This new reference area was intensively sampled for herbaceous cover and production, using the same sampling methodologies and statistical tests that were used to compare the present reference area to the premine area. On August 21, 1981 Colowyo submitted revised vegetative data summarizing the results of the selection of an alternative sagebrush reference area. Both the new sagebrush reference area and old sagebrush reference area were intensively sampled for herbaceous cover and production using the same methodologies and statistical tests as used on all previous vegetative sampling programs with the following two exceptions. For the purpose of sample adequacy, the 90% confidence level has been attained for cover and production, whereas, in the past the 80% confidence level had been attained. For production sampling, a larger 60cm. x 60 cm. frame was used rather than the 30cm. x 60 cm. frame used to gather baseline production data for the original permit application. The use of a larger frame reduced the sampling variance, thus reducing the numbers of samples needed to achieve sample adequacy. The vegetative data is summarized on Table 5, Herbaceous Cover of the Sagebrush Type, Old (1980) and New (1981) Reference Areas-and Table 6, Herbaceous Production of the Sagebrush Type, Old (1980) and New (1981) Reference Areas. For the location of the current sagebrush reference area, refer to Map 3, Regional Vegetation. • Currently the mountain shrub reference area is located in an area where grazing can be managed in accordance with the approved postmining land use. The reference areas will be fenced, as necessary, to insure that the proper grazing management can be implemented. Comparisons of weighted averages between reference areas and revegetated areas under Subsection 4.15.7(4) (b) will be utilized to determine revegetation success. The same methodologies and statistical tests used to compare premine and reference areas will be used to compare reference areas and revegetated areas. 4.15.8 Reveeetation Success Criteria Colowyo will meet the requirements of this Subsection to insure that the postmining vegetation will be adequate for final bond release. • 4.15-17 Revision Date: 3/18/92 Revision No.: