2018-03-20_PERMIT FILE - C1981019A (3)

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RULE 4 PERFORMANCE STANDARDS Where necessary, the mean, variance and number of observations for the premine and reference area data were used to perform t-tests on the cover and production data to insure that there were no significant differences, at the 90% level of confidence, between the sets of cover data and production data. A copy of the transect data summaries for cover, production and woody plant density can be found in Exhibit 10, Vegetation Information. During the summer of 1980, when the reference areas were chosen, the final mine plan had not been completed and, the sagebrush reference area was inadvertently located within the area to be mined. Since the reference area is to remain undisturbed during the life of the mining- operation to insure that reclamation success criteria can be measured after final reclamation, another suitable sagebrush reference area was chosen. 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 (1981) 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 (1981) 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 60cm. frame was used rather than the 30cm. x 60cm. 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. For the locations of the current (1981) Sagebrush Reference Area, (1980) Mountain Shrub Reference Area, and (1984) Aspen Reference Area, refer to Map 3, Regional Vegetation. The Sagebrush Reference Area is located north of the office / warehouse complex in the west 1/2 of Section 34, T4N R93W. The Mountain Shrub Reference Area is located on the crest and both east and west slopes of a ridge west of West Pit in the NE 1/4 of the NE 1/4 of Section 8 and the NW 1/4 of the NW 1/4 of Section 9, T4N R93W. The Aspen Reference Area is located approximately 4 miles to the SSW of the South Taylor Area in the SE 1/4 of Section 1, T2N R94W and the SW 1/4 of Section 6, T2N R93W. Currently the reference areas are located in an area where grazing can be managed in accordance with the approved postmining land use. Comparisons of weighted averages between reference areas and revegetated areas under Subsection 4.15.7(4) (b) and Subsection 4.15.11 may be utilized to determine revegetation success. Similar methodologies and statistical tests used to compare premine and reference areas will be used to compare reference areas and revegetated areas. For weighted comparisons of original permit area revegetation (grazinglands), reclaimed area data will be compared against 55% Mountain Shrub Reference Area and 45% Sagebrush Reference Area data. However, some comparisons may be made directly against a single reference area (e.g., Sagebrush Reference Area). In this regard, any sagebrush steppe community that evolves in the reclaimed area will be directly compared against the 1981 sagebrush reference area. For weighted comparisons of South Taylor revegetation, reclaimed area data will be compared against 52% of the 1980 Mountain Shrub Reference Area, 25% of the 1981 Sagebrush Reference Area, and 23% of the 1984 Aspen Woodland Reference Area data. Rule 4 Performance Standards 4-55 Revision Date: 1/31/18 Revision No.: TR -119