2008-08-22_APPLICATION CORRESPONDENCE - C2008086

• Permit No: C2008086
• IBM Index Class Name: APPLICATION CORRESPONDENCE
• Doc Date: 8/22/2008
• Doc Name: Adequacy Review
• From: Joe Dudash
• To: Mike Boulay
• Email Name: JJD
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
COLORADO
Denver, Colorado 80203 D
DIV IS SION OF
Phone: [phone] RECLAMATION
FAX: [phone] MINING

DATE: August 22, 2008 SAFETY
Bill Ritter, Jr.
Governor
TO: Mike Boulay
Harris D. Sherman
Executive Director
FROM: Joe Dudash Ronald W. Cattany
Division Director
RE: Red Cliff Mine, CAM-Colorado LLC., New Permit Application Natural Resource Trustee
Hydrology Adequacy Review
I have finished a portion of my review of the surface water hydrology for the Red Cliff
Mine new permit application. My review to date involves the Sedcad designs. Questions
numbered 1, 2, 3 and 4 involve basic modeling and the resolution of questions 1 and 2
could result in a complete reworking of the Sedcad designs. Therefore, I will continue my
review but plan to hold off on some of the Sedcad design information until these basic
issues are addressed. Questions 10 through 13 involve map revisions. Since I am not
finished reviewing the Sedcad designs, it might be better to hold off asking these
questions initially. More revisions of these maps may be forthcoming and I am sure the
operator would appreciate revising maps only once.
1. Based on field observations at the McClane Mine and at the Munger Mine over
the years, the Division has concerns about normal hydrologic modeling
procedures accounting for the intensity of the precipitation events in this area. The
Book Cliffs are steep cliffs with little vegetative cover. This area gets hit with
very intense localized summer storms. Large amounts of sediment and other
debris (tree stumps, rocks, etc.) have come down with the runoff from these
intense storms. Relying on the design storm event and SEDCAD modeling to size
sediment control structures doesn't work well in this environment. The Division
highly recommends that CAM consider oversizing the structures, or consider
other measures, to account for the intensity of the storms in the Book Cliffs.
2. The hydrology designs found in Volume IV use 1.4 inches as the 10 year-24 hour
precipitation event, 1.8 inches as the 25 year-24 hour event and 2.2 inches as the
100 year-24 hour event. However, examination of the 1973 NOAA Atlas
"Precipitation -Frequency Atlas of the Western United States" shows larger
precipitation values. The NOAA Atlas values are about 1.7 inches, 2.05 inches
and 2.6 inches respectively. Also, the hydrology designs for the McClane Mine
just to the north used 1.7 inches as the 10 year-24 hour precipitation event. Please
explain CAM's values or revise the Sedcad designs appropriately.
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines