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~, <br />J <br />iiiiiiiiiiiiiiuiii • <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depanment of Natural Resources <br />1313 Sherman SI., Room 215 <br />Denver, CO 80203 <br />Phone: 13031 8663567 <br />FA%:13031 83 2-8106 <br />February 23, 1994 <br />Mr. Scott Benowitz <br />Canonie Environmental <br />333 Haggerty Lane <br />Bozeman, Montana 59715 <br />pF Cpl <br />4~ 4 <br />,c ~~ <br />.• <br />~~ <br />r8]6 ~ <br />Roy Romer <br />Governor <br />M¢hael 8. Long <br />D rvision Direuor <br />RE: Hydrologic Evaluation, Bulldog Mine, Homestake Mining Company, <br />Permit No. M-77-215 <br />Dear Mr. Benowitz: <br />Please find enclosed Soil Survey maps and Soil Unit descriptions <br />for the Windy Gulch drainage basin above the Bulldog Mine waste <br />dump. The Soil Survey information indicates that essentially all <br />units in the drainage basin have been classified in Hydrologic Soil <br />Group C (with minor occurrences in Groups D and B). Duplicating <br />the Curve Number selection methodology outlined in your letter to <br />Luke Russell dated January 22, 1994, the placement of the soils in <br />hydrologic group C (instead of B) is, in its self, justification <br />for using a Curve Number in the range of 75 to 82. The Division <br />would accept a TR-55 type hydrologic evaluation, and waste dump <br />stabilization design based on the results of such an evaluation, if <br />Curve Numbers in this range are utilized. <br />If you have any questions, please contact me. <br />Sincerely, <br />., j <br />. i ,,.,. <br />fi r j ~ ~:~ <br />~~~'.~~. fir` <br />Allen C. Sorenson <br />Reclamation Specialist <br />ACS/acs <br />enclosure(s) <br />cc: Luke Russell, Homestake <br />Berhan Keffelew, DMG <br />C:\WP51\BULLDOG <br />