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<br />en <br />OROOKS TOWERS <br />1020 I STH STREET <br />DENVER, COLORADO 80202 <br />FEB 1 ~ 1~~? <br />United States Department of the Interior <br />OFFICE OF SURFACE MINING <br />Reclamation and Fnforcem t <br />_~; ~ ~ III IIIIIIIIIIIII III 8"`7 "' <br />FEB 1 7 1981 <br />MINED tAND RECWAATION;COA4' <br />Ms. Carol Pahlke Sp!A, Pte. GF LrAluRAL 1lESOD~[ES <br />Colorado Mine Land Roard <br />1313 Sherman St., Room 423 <br />Denver, CO 80203 <br />Dear Carol: <br />This letter is to inform you and the Colorado staff working on the vegetation <br />section for the McClave Canyon Mine, of problems with the baseline vegetation <br />data collection. In Volume I, page 4-70 of the mine plan, the company has <br />stated that sample adequacy for cover was calculated using a one tailed <br />t-statistic value of .84 at a 80% confidence level. <br />In the attached letter dated October 14, 1980 from OSM to Dave Johnson of <br />Western Resources Development Corp. (Sheridan Enterprises Consultant), OSM and <br />Colorado Mine Land Aoard made it clear in item one that sample adequacy would <br />}n~~~~ be calculated at a 90% level for cover. I have recalculated sample adequacy <br />a' for all vegetation units sampled and found that the number of samples <br />collected for Greasewood and Shadscale Shrublands is sufficient, but that the <br />Juniper Community has been undersampled (attached table 4.5-25). All other <br />~~(a,c1o` sampled components (production and density) are likewise undersampled but the <br />v;,~ ~ctober 14 OSM letter did not require that these vegetation components would <br />r~R be treated tl)e same as the cover requirement. There seems to be other <br />~~~ problems such as to whether the 3-10 metered bare spots in the Greasewood <br />Shrubland vegetation complex were accounted for in the cover sampling <br />(reference, Vol. I, p. 4-76). <br />I would like to suggest that a letter from Colorado Mine Land Roard be sent to <br />both Dave Johnson and Sheridan Enterprises informing them of this situation, <br />and stating that a resampling of the cover for the Pinyon-Juniper vegetation <br />community and comparable reference area will have [o be made along with a <br />comparison of these two at a 95% level of comparison using a statistical <br />t-test (see reference X13, attached October 14, 1980 letter). <br />Your response on these points would be greatly appreciated. <br />Sincerely, <br />~y5~ <br />Rocky Beavers <br />Range Conservationist <br />Attachment <br /> <br />r <br /> <br />r <br />