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STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />FAX: (303) 832-8106 <br />COLORADO <br />DIVISION O F <br />MINERALS <br />GEOLOGY <br />RECLANATION•NINING <br />SAf ETY•SCIENCE <br />Bill Owens <br />1 June 2005 cGVernGr <br />Russell George <br />Ezeculive DlreClGr <br />Minrec, Inc. Ronaia w. ca"a°r <br />2768 Compass Drive, Suite 101 Division DirMGr <br />Grand Junction CO 81506 Natural Resource Truztee <br />RE: Blue Ribbon Mine (C-1981-047) 2"d Adequacy Letter, TR-13 <br />Deaz Mr. Stover: <br />The Division has reviewed the adequacy response submittal from Minrec. For the most <br />part, the itemized responses and associated amended text and map aze acceptable, <br />however a couple items require clarification and further amendment. <br />First, in Item 5 under "Letter 1 - 8 Items", the cover letter states that reverse-null testing <br />will be employed, with a minimum sample size of 30, which is consistent with the text <br />under "Testing for Success" on amended page 113iii. However, some further <br />clazification is warranted with respect to the success testing, as explained in the following <br />paragraph. <br />If sample adequacy is achieved in the reference area for cover or production, a one <br />sample reverse-null t-test can be used to demonstrate success, with the reference azea <br />pazameter sample mean treated as the "standard". However, if sample adequacy is not <br />achieved in the reference azea, it is not appropriate to treat the reference azea pazameter <br />sample mean as the "standard". In this situation, the appropriate test procedure is a two <br />sample reverse null t-test, with a minimum sample size of 30 in the reference area as well <br />as in the reclaim azea, to demonstrate that the reclaim area population mean exceeds 90% <br />of the reference azea population mean. Please amend the text to clarify that a two <br />sample reverse null t-test, with a minimum sample size of 30 in both the reference <br />area and the reclaim area will be employed, if sample adequacy is not demonstrated <br />in the reference area. <br />Second, in Item 1 under "Letter 2 - 6 Items", the cover letter states that page 113 was <br />changed to provide detail regarding the date of last interseeding and to delete 2nd <br />narrative paragraph regarding the need for the Division and Operator to jointly agree on <br />the vegetation community boundary. These changes do not appear to have been made on <br />the amended page 113 provided. Please amend the 1s1 narrative paragraph on page <br />Office of Office of Colorado <br />Mined Land Reclamation ARive and Inactive Mines Geological Survey <br />