2008-12-05_REVISION - C1980007 ‎(2)‎

• Permit No: C1980007
• IBM Index Class Name: REVISION
• Doc Date: 12/5/2008
• Doc Name: Summary of Review
• From: TAK
• To: File
• Type & Sequence: TR115
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203 C O L O RA D O

Phone: [phone] DIVISION O F
RECLAMATION
FAX: [phone] MIN ING

SAFETY
MEMO
Bill Ritter, Jr.
Date: December 5, 2008 Governor
Harris D. Sherman
Executive Director
TO: File
Ronald W. Cattany
West Elk Mine (C-80-007) Division Director
TR-115 Natural Resource Trustee
From: Tom Kaldenbach
Re: Summary of Review
I have reviewed the mine operator's SEDCAD inputs for reasonableness, including:
drainage areas, structure routing, slope magnitudes, slope lengths, particle size
distributions, design storm rainfall depths, LS factors, K factors, and runoff curve
numbers. I verified the inflow volumes for each pond for 10-year and 25-year storms
using the Rational method in the attached spreadsheet calculation.
My review found:
a) All SEDCAD input values appear reasonable.
b) The ponds appear capable of containing the 10-year storm runoff (each pond is
more than three times larger than the calculated 10-year storm inflow); therefore,
discharges are not likely to exceed the 50 ml/l discharge limitation.
c) Pond discharges will have adequate freeboard during 25-year storms (minimum 1
foot between emergency spillway water level and top of embankment).
d) Ditches and culverts appear adequately sized for 10-year peak discharge.
e) Ditches are adequately lined for preventing excessive erosion in a 10-year storm.
The mine operator's notice was published on November 12, 2008. No comments have
been received.
DRMS is preparing a reclamation cost estimate for TR-115.
cc: Dan Hernandez, DRMS
Ryan Sweetwood, MCC
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines