2011-01-27_REVISION - C1981019

• Permit No: C1981019
• IBM Index Class Name: REVISION
• Doc Date: 1/27/2011
• Doc Name: Review of Adequacy Responses ‎(Interoffice Memo)‎
• From: Kent Gorham
• To: Jim Stark
• Type & Sequence: SL4
• Email Name: JRS
• Email Name: SB1
• Email Name: KAG
• Email Name: JHB
• 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
Phone: [phone]
FAX: [phone]
Interoffice Memo
To: Jim Stark
From: Kent Gorham
CC: Sandy Brown
Date: January 27, 2011
RE: Review of Adequacy Responses,
Phase II Sediment Demonstration
SL-04, Colowyo Mine, #C-1981-019
COLORADO
D IV IS I ON OF
RECLAMATION
MINING
SAFETY
I have completed my review of the materials received from Colowyo on December 27,
2010 responding to DRMS adequacy concerns for the Phase II bond release application
(SL-04) for the Colowyo Mine, permit #C-81-019. My comments are specific to the
sediment demonstration made by Colowyo (applicant) as required by Rule 3.03.1(3)(b).
My reviewed focused entirely on the sediment demonstration portion of the bond
release application and were questions #5 and #6 of your adequacy letter.
5. The response is accepted. The applicant made the changes to the "C" factor
values as requested, although may not fully understand the focus of the
Division's concern. It is of primary importance that the applicant understands the
methodology for the comparison needs to be appropriate. The Division's
recommended "C" factor was derived from the 2006-2009 sampling data taken
from the reference areas, rather than attempting to use pre-mining data
from the late 1970's while selecting the reclamation "C" factor values from
2006-2009 sampled data, as was the case with the original submittal. The
operator needs to understand the importance of this point for future
sediment demonstrations.
6. The response is accepted, although again, the operator needs to understand that
the DRMS suggested values were derived based on actual conditions and/or
data derived from sampling and not selected from a textbook.
In the end, using the proper methodology and assumptions, the RUSLE calculation
supports the applicant's contention that the reclaimed parcels included in the Phase II
bond release application produce less sediment than adjacent un-mined areas
(represented by the reference areas sampled concurrently with the reclaimed areas).
Office of office of
Mined Land Reclamation Denver - Grand Junction - Durango Active and Inactive Mines