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iiiiuiuiiuiuiii <br />STATE OF COLORADO <br />Roy Romer, Gove <br />DEPARTMENT OF NATURAL RESOURCES <br />MINED LAND RECLAMATION DIVISION <br />FRED R. BANTA, Dlreetor <br />April 7, 1989 <br />Mr. Tom Augustine <br />Wyoming Fuels Company <br />Star Route 1 <br />Weston, CO 81091 <br />Re: Response to Stipulation 44 For New Elk <br />Stipulation 36 For Golden Eagle Mining <br />Refuse Pile Drainage Ditches To Safely <br />Event. <br />Dear Mr. Augustine: <br />Mining Permit (C-81-012), And <br />Permit (C-81-013), Design For <br />Pass a 100-Year, 24-Hour Storm <br />The Division has completed review of the above-mentioned ditch design. The <br />designs for New Elk were submitted by Mr. Steve Magnuson on February 27, 1989, <br />and the Golden Eagle by Mr. Mike Kolin on March 3, 1989. <br />Referring to Map 13 of the New Elk permit application, the structures in <br />question drain the old refuse pile, and include ditches D2, D3, and D4, and <br />culverts C7 and C8. All three ditches are listed as being Type B, triangular <br />in shape with 7.5 foot top width, 1.5 foot depth, and 2.5:1 side slopes. <br />Calculated 100-year peak flows of 6.0 cfs in D3 and 8.7 cfs in D4 will flow at <br />a velocity of approximately 3.5 ft/sec (using Manning's equation, n = .035), <br />and will be conveyed by Type B ditches. However, for D2 a peak flow of 17.8 <br />cfs and velocity of 2.4 ft/sec was calculated. A type B ditch would overflow <br />under these conditions, therefore D2 should be upgraded to a Type C ditch. It <br />appears that culverts C7 and C8 will safely pass the runoff from D4. <br />The North and South ditches draining the refuse disposal area at Golden Eagle <br />mine, as designed, would safely pass a 100-year, 24-hour precipitation event. <br />Following a field inspection on April 4, 1989, however, it was found that the <br />ditches are not built exactly as designed. The North ditch terminates without <br />extending around the west end of the pile, which could possibly allow drainage <br />to escape onto the adjacent road and pad area. Similarly, the South ditch <br />ends at the access road to the mine portal. In order to meet the designs, <br />both ditches should be extended around the upper (west) end of the pile. The <br />lower sections of both ditches appear to be adequate. <br />215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567 <br />