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INTEROFFICE MEMORANDUM TO: fG\RRY kt~\NNGY FROM: )ANE'1' nINNS~ SUBJECT: CHIbfNE ROCK Y~ '1'UV. FI,ASE BOND RL7.EdSE AYPLIGITION DATE: 11 /29/02 CC: UAN HERNANUP."/. I have reviewed Kaiser Resources application for a partial phase III bond release for the alluvial valley floor portion of the Chimney Rock Mine. The post mining land use of the alluvial valley floor is irrigated pasture. Greystone collected vegetation data on the irrigated pasture in July 2001 and June 2002. Sample design entailed random distribution of transect locations for cover. Three production quadrats were laid out at regular intervals along the cover transects. The data from the three production plots were designed to be averaged for each transect. Sample adequacy for production was achieved on the data collected in 2001. Colorado experienced a serious drought during the spring and summer of 2002. The low water level in Stollsteimer Creek precluded irrigation of the reference and reclaimed pastures in 2002. 2002 production data reflect drought and dryland conditions. As a result, herbaceous production data exhibited an extreme degree of variability. Data ranged from a low of O.lg/O.SM2 to a high of 70.4 g/O.SM2 on the reclaimed pasture. This high degree of variability necessitated a high number of samples to be collected to achieve sample adequacy. Greystone presented the 2002 production data as 150 individual quadrats, instead of 50 composited samples. When the 2002 Reclaimed pasture data is analyzed as called for in the design plan, sample adequacy is not met. The Snedecor-Cochran sample adequacy formula recommended by DMG in the Guideline Regarding Selected Coal Mine Bond Release Issues, dated April 18, 1995, on page 21, was used to calculate sample adequacy. Greystone collected 50 random transects with 3 regularly distributed quadrats along each transect. Analyses with the sample adequacy formula calculates a minimum of 91 sample points to achieve sample adequacy of the population. Greystone's analyses of this data as 150 independent points indicates that sample adequacy has been achieved with 150 samples. However, the basic assumption that the 150 points are independent is slightly flawed. Every three production quadrats are dependent upon a randomly located cover transect. Greystone analyzed the 2002 pasture reference area in the same manor, determining [hat 60 quadrats did not achieve sample adequacy. The Division composited the quadrat data to correspond to the 20 cover transect and calculated that 64 quadrats were necessary to achieve sample adequacy. Due to the small size of the reference area, 0.8 acres, Greystone was unable to collect additional samples without the concern of double sampling. Greystone also chose to analyze the data from 2001 differently than the data collected in 2002 although the sample design was the same. 2001 production data was compiled with respect to the cover transect as called for in the design plan. 2002 data was analyzed as independent quadrats.