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STnTE OF COlOA400 oT ~•n9 D. ~nuM Gw ran nr DEPORTMENT OF NATUR4L RESOURCES Harms 0 Sherman. E.ecur~va D~rfK for 11L\EU LA~~U RECLAl1A'TION 723 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. 13031 839-3567 Hamlet J. Barry, III, Director June 23, 1980 Mr. Cass Leal Hayden Gulch Coal Co. 333 Quebec St., Suite 8800 Denver, Colorado 80207 RE: Reference Area Selection - H-G Coal Mine Our File No. 77-99 Dear Mr. Legal: The purpose of this letter is to summarize those points which were discussed • during our meeting of June 16, 1980, concerning the selection of reference areas for the H-G Mine. Under the permanent program, this Division intends to evaluate proposed reference areas according to the criteria in 4.15.7(3) of the proposed Colorado regulations. You were given a current copy of 4.15, which contains all recent revisions. As specified in 4.15, the applicant is required to demonstrate statistically that proposed reference areas are comparable to areas to be disturbed, in terms of cover and production of herbaceous plants. You are not required to sample cover and production of woody plants. In order to make this comparison, you must sample randomly within each mapping unit and each corresponding refer- ence area. The same sampling methodologies must be used for both. For the determination of sampling adequacy and for the demonstration of reference area comparability, we are currently utilizing methods specified in the draft document prepared by the Office of Surface Mining, titled "A Statistical Evaluation of Revegetation Success on Coal Londe in the West." In the future, Colorado may develop its own guidelines. Since virtually all of the vegetation types at the H-G Mine qualify as "woody plant communities," as defined in the proposed Colorado regulations, the applicable requirements for the statistical demonstration will be 90X of the mean with 80X confidence. Reference areas are required to represent all plant communities identified in the pre-mine inventory. In your case, however, you will probably want to combine some of the original mapping units, specifically the sage-snowberry, • chokecherry-snowberry and serviceberry-snowberry.