2012-11-28_REVISION - C1981028

• Permit No: C1981028
• IBM Index Class Name: Revision
• Doc Date: 11/28/2012
• Doc Name: Request for Assistance ‎(Emailed)‎
• From: Jared Ebert
• To: Brock Bowles
• Type & Sequence: TR43
• Email Name: BFB
• Email Name: JLE
• Email Name: SB1
• Media Type: D
• Archive: No

DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
MEMO
28 November 2012
TO: Brock Bowles; DRMS
FROM: Jared Ebert, DRMS
STATE OF COLORADO
RE: Keenesburg Mine; C- 1981 -028, Technical Revision No. 43 (TR43)
Review
COLORADO
D I V I S 16 N OF
RECLAMATION
MINING
SAFETY
John W. Hickenlooper
Governor
Mike King
Executive Director
Loretta Pineda
Director
As you requested I reviewed the above referenced technical revision submitted by Coors Energy
Company for the Keenesburg Mine. The revision modifies the regression equations used to predict
vegetative cover and herbaceous production utilized to evaluate revegetation success at the mine based
on precipitation amounts from September to July for a given year of monitoring. The regression
equations are also based on vegetation monitoring data from the original Osgood Sand Reference Area
from the years 1994 to 2005. This revision removes noxious weed cover and production contributions
from the monitoring data from the Osgood Sand Reference Area used to derive the predictive equations.
This allows for a fair comparison of the predicted success standards and the vegetation cover /production
measured at the site for the purposes of vegetation monitoring and bond release since the Division
cannot allow noxious weeds to count toward revegetation success.
The methodologies used originally to determine the predictive equations can be found with the narrative
submitted with TR37 and was subsequently approved by the Division. The method used to derive the
equations have not changed with the current revision; only the cover and production data used to create
the equations have been slightly modified to remove noxious weeds. I was able to verify the new
predictive equations based on the revised vegetation monitoring data using Microsoft Excel®. From my
review I have two recommendations /concerns:
1.) The first paragraph on page 116 of the permit needs to be revised to include a citation that the
predictive equations were subsequently updated with TR43. This will provide clarity to future
reviewers.
2.) Based on the Division's calculations, it appears the precipitation amount from September of 1994 to
July of 1995 should be 16.59 inches instead of the 16.77 inches as indicated in the revision. Coors
Energy Company reported the precipitation amount for September of 1994 to be .81 inches according to
the 1994 Annual Hydrology Report. However, the revision indicates the precipitation for this month
was .99 inches. This appears to be the source of the discrepancy. This precipitation value modifies the
predictive equations slightly and should be revised and the equations updated.
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines