2015-10-06_PERMIT FILE - C1981019A (3)

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RULE 4 PERFORMANCE STANDARDS post -mining land uses is designed to compensate for revegetation techniques (prescribed ecological reclamation approach) that must discourage grasses to encourage shrubs in the post-revegetated community. For "evolved" sagebrush steppe revegetation, the grassland cover standard will be maintained. A higher percentage of herbaceous cover is not practical or desirable for the following reasons: It is well documented that in mined -land reclamation the establishment of shrubs to reach bond release levels has proven to be very difficult. Perhaps the most detrimental condition affecting shrub establishment is the competition from herbaceous vegetation. At a minimum herbaceous cover levels should be less than the premining condition. If the herbaceous levels to be obtained were set higher than the premining condition, the ability to achieve bond release levels for shrubs would be most adversely affected. Higher levels of herbaceous cover would adversely compete against woody vegetation and hinder its successful establishment. 2. In mined -land reclamation it is important to have adequate herbaceous cover to provide for erosion control. The reference areas for the Collom mining area indicate herbaceous cover values of 62.75%, 51.00% and 51.85% for the mountain shrub, sagebrush and grassland references respectively. The period of highest potential erosion occurs in the springtime during snowmelt. At this time of year, erosion control is provided almost exclusively by herbaceous vegetation. Erosion control by shrub cover is virtually insignificant since the potential erosion occurs from snowmelt rather than raindrop impact. Therefore, if pre -mining levels of herbaceous vegetative cover can be re- established, logically a comparable level of erosion control will be achieved. 3. The ability to achieve adequate levels of herbaceous cover in the Collom mining area is, without question, quite possible. The vegetative monitoring completed at Colowyo during the last three decades, and summarized in Annual Reports, indicates that the premining levels of herbaceous cover are easily achieved. In fact, the vegetative data as summarized in the Various Annual Reports indicate that the levels of herbaceous cover on the reclaimed areas may have exceeded the premine condition by 30% to 50%. The vegetative sampling serves to confirm what can be observed in the field. The revegetation at Colowyo is excellent and there is virtually no evidence of erosion attributable to a lack of cover. In fact the herbaceous cover existing at Colowyo meets or exceeds the premining condition and is undoubtedly providing significant competition with the woody specie seedlings. There is certainly no evidence that herbaceous cover values on the reclaimed areas should be set higher than the herbaceous cover of the premine areas in order to achieve bond release. Herbaceous Production For revegetation (targeting (and achieving) the land use subcomponent of grassland), herbaceous production of the revegetated area will be considered adequate for final bond release if it is not less than 90% of the herbaceous production, as determined from the reference areas with a 90% statistical confidence utilizing a standard students statistical t-test comparison of the means. As allowed under the rules promulgated on 9/14/05, these comparisons may utilize one of three methods detailed under Rule 4.15.11 (2) [( a), (b) or (c)]. As allowed by Rule 4.15.7 (4), either weighted -average or individual protocols will, be followed. For grassland testing the weighted average approach (Rule 4.15.7 (4) (b)) will Collom — Rule 4, Page 39 Revision Date: 9/28/11 Revision No.: PR -03