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C~ Mr. Gregg Squire -2- January 7, 1985 areas actually disturbed. The inclusions of prelaw mining disturbance are too small to reference and will be discounted during revegetation success :. measurement. Such discounted acreages will be judged successful if: _ o The revegetation procedures employed on .the newly disturbed sites are utilized on the prelaw disturbances; and, ~ -- o Erosion is controlled according to the provisions of the current (1984) MLRB coal mining regulations. • Methods to obtain cover, herbaceous productivity, woody plant density, and species diversity data on the reclaimed area and reference areas will be the same as those approved for use at the Perma Resource Chimney Rock Mine. Sample locations for cover and production will be randomly selected on reference and affected areas by use of a numbered grid system (interval = 50 meters on-the-ground) overlain on the vegetation map of the mine permit area. This in turn will be overlain with the areas actually disturbed by mining. A random numbers table will be used to identify coordinates for the sample locations. Sample locations will be numbered and shown on the map. Sample locations in the field will be determined by pacing from recognizable landmarks. A minimum of 15 cover and production samples will be taken, then sample adequacy will be calculated using the formula: Nmin = T2 S? D Where Nmin = The minimum number of observations needed TZ = 1.28 for the 80% of confidence level, and 1.64 for the 90% of confidence level S2 = Variance of initial sample D = .lA sample mean (x) times level of accuracy (+ 10%) Sampling will continue until the required number of samples to meet adequacy has been taken, up to a maximum of 50 on affected areas and 50 on each reference area; the confidence level achieved with the maximum number of samples will be calculated if Nmin is greater than the maximum number taken.