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~. ~~~ I~~I~~I~~~~I~~~~ To: Jce Dudash From: Larry Routte i~ Subject: Trapper Mine, MR-71; Reveg success stds. Date: April 7, 1997 MEMORANDUM I reviewed Trapper's MR 147. The revision basically proposes to change the success standards for shrub density and species diversity. Since the Trapper permit already contains "technical" standards for cover and production, the company proposes to eliminate their vegetation reference areas with the changes to shrub and diversity standards..The revision also clarifies some of the sampling plans that Trapper will follow while collecting data related to bond release applications. Here are two sets of comments/questions for your consideration. The f rst set of general comments have to do with parts of the Trapper permit which are only indirectly involved in this MR. You may want to deal with them now, or later. The second set of comments pertain to MR-147. General Comments The permit contains a success standard for cover which is derived by back-calculating the amount of cover required to hold erosion to an amount which the NRCS says is acceptable for the soils disturbed by the mine. There are two concerns with these standards. A. This means of establishing revegetation success standards is referred to as "technical standards" in the regulations. DMG is only allowed to approve technical standards in conjunction with OSM approval, which was not done in the case of the standards in the Trapper permit. DMG is presently in the preliminary stages of arule-making effort in which allowance will be made for DMG to approve technical standards. In the mean time, there is no regulatory basis for the cover standards in the Trapper permit. B. The live vegetative cover standards for range sites A, B and C are 33%, 29%, and 25%, respectively. These values are relatively low in comparison to other northwest Colorado coal mines. The Trapper permit acknowledges that one of the factors that should be considered in assessing cover success standards is the rate of soil genesis. The USLE assumptions that the Trapper standards are derived from allow for annual loss of 4 tons/acre year of topsoil. This would be equivalent to loss of one foot of topsoil in 464 years. In northwest Colorado, it takes thousands of years for a foot of topsoil to form. Finally, the 1980 baseline information in the Trapper permit indicates that the live vegetative cover in the mountain shrub and sage/grass reference areas was 37.7% and 33.0%, respectively. ^