Laserfiche WebLink
iiiiiiiiiiiiiiuiii <br />999 <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Departmem of Natural Resources <br />1313 Sherman SL, Room 215 <br />Denver, Colorado 80203 <br />Phone: 13031 866-356 7 <br />FAX: (303) 832-A 106 <br />DATE: December S, 2000 <br />TO: Sandy Brown <br />FROM: Joe Dudash ~ ~ .~ <br />RE: Hydrology Adequacy Review, Minor Revision No. 55, Elk Creek Mine, <br />Permit No. C-S1-022, Oxbow Mining, Inc. <br />DIVISION OF <br />MINERALS <br />GEOLOGY <br />RECLAMATION <br />MINING•$A FETY <br />Bill Owens <br />Govemo+ <br />GregE Wnlcher <br />Executive Direnor <br />Michael B. Long <br />Division Director <br />At your request, I have reviewed the hydrology aspects of MR-55. The SEDCAD designs appear <br />to be correct and conservative. The following aze my questions and comments concerning other <br />issues of MR-55: <br />Drawing No. 7 was submitted with MR-55. However, this drawing does not cover the <br />same aerial extent as does the approved sheet 3 of 4 for Drawing 2.05-M4, "Drainage and <br />Sediment Control Plan", and, therefore, is not an exact replacement drawing. Please <br />submit a revised sheet 3 of 4 of Drawing 2.05-M4, showing the proposed changes in MR- <br />55. <br />Please add the symbols for the four proposed downdrain culverts to revised Drawing <br />2.05-M4, sheet 3 of 4. <br />Oxbow is proposing to use 12 inch diameter culverts for the four downdrain culverts. <br />Although this diameter culvert will be more than adequate to handle the designed flow, <br />such a small diameter culvert is more prone to blockage at the inlet and clogging in such <br />a potentially active area than a larger diameter culvert. For such high maintenance <br />structures, the access to the structures will not be easy in wet conditions. The Division <br />recommends a larger diameter culvert. Please respond. <br />If you have any questions, please let me know. I have put a copy of this memo on the M drive. <br />c:\ms97lsanborn\mr55adegl <br />m:\coal\jjd\mr55adeq 1 <br />