2021-03-31_REVISION - C1982057 (3)

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Woody plant density sampling occurred in the BRBS. Sampling occurred along 50 meter transects.All shrubs and root crowns located within the boundaries of the 2 meter by 50 meter quadrats(100 m2)were tallied according to species and life stage as either seedling,mature or dead. Dead plants were recorded but did not contribute to woody plant density calculations. Two areas were sampled for woody plant density, "background' areas and"volunteer" areas. No fenced tree and shrub concentration areas were located within BRB-5. The woody plant density transects were co-located with the cover transects for the"background" areas. For the "volunteer" areas the woody plant density transects were randomly located and randomly oriented and were not co-located with the cover transects.These methods conform to the approved sampling plan outlined in Tab 22 and are in accordance with Rule 4.15.11(1)(c)(1). Plant species frequency and density measurements were ascertained from the applicable cover sampling data. Sample adequacy was evaluated for each of the sampling efforts and statistical demonstrations for revegetation success for vegetation cover,herbaceous production,and woody plant density was conducted in accordance with Rule 4.15.11. Extended Reference Area Performance Standard(s) As discussed in the CCAI report,the allowable means for cover and production from each of the five reference areas are weighted in accordance with the original relative abundance of the vegetation types in the pre-mining landscape(11.0%aspen,34.5%mountain brush, 31.3%sagebrush/snowberry, 12.8%steep mountain brush and 10.4%Western wheatgrass/alkali sagebrush)(page 7). Sample adequacy was not always achieved when sampling the ERA. In these instances, an"upward adjustment"is made to the appropriate ERA mean value. According to CCAI,the adjustment value can be calculated by using the confidence interval for 90%confidence or by way of rearranging the sample adequacy formula and solving for the detectable percent reduction then multiplying by the mean. The adjustment value is then added to the allowable mean. While not expressly outlined in Tab 22,this adjustment increases the success standard calculated from the ERA data,essentially setting a higher bar for reclamation success to be demonstrated. Success Standards Cover data is be collected from the above five described vegetation types within the ERA. The extent of herbaceous cover in each of the five vegetation types are represented by the"all-hit" measure of cover. An average of the herbaceous cover of the extended reference area types,weighted by their extent in the pre-mining area affected by mine disturbance will be calculated using"all-hit"total herbaceous vegetation cover data. This calculated weighted average mean cover from the ERA is used as the success standard. The revegetated area shall be considered acceptable if they are not less than 90 percent of the weighted average mean cover from the ERA. Reclamation success for herbaceous production is evaluated by comparing herbaceous production in the reclaimed areas to the weighted herbaceous production value determined from sampling of the ERA. Reclamation success for herbaceous production shall be demonstrated when the value of the reclaimed area is greater than or statistically indistinguishable from 90 percent of the herbaceous production standard with 90 percent statistical confidence using a one- sample t-test. There are five woody plant density technical standards;two mandatory standards for the overall reclaimed land and three other(secondary)standards for the concentrated shrub/tree establishment sites two of which must be satisfied. Overall average background density must be>200 stems per acre on 100%of the unfenced reclaimed Permit Number: C1982057 Page 6 of 15 Phase III