2010-07-16_REVISION - C1981019

• Permit No: C1981019
• IBM Index Class Name: REVISION
• Doc Date: 7/16/2010
• Doc Name: 2nd Adequacy Letter
• From: DRMS
• To: Colowoyo Coal Company
• Type & Sequence: TR81
• Email Name: JRS
• Email Name: SB1
• 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]
16 July 2010
Ms. Jennifer Sekulski-Barton
Colowyo Coal Company, LP
5731 State Highway 13
Meeker, CO 81641
Re: Colowyo Mine C-1981-019
Second Adequacy Letter - Technical Revision 81
Dear Ms. Sekulski-Barton:
COLORADO
D I V I S I ON OF
RECLAMATION
MINING
SAFETY
Bill Ritter, Jr.
Governor
Mike King
Executive Director
Loretta E. Pineda
Director
The Colorado Division of Reclamation, Mining and Safety (Division) has received the Colowyo
Coal Company, LP's (Colowyo) responses to the Division's 11 March 2010 Preliminary
Adequacy Letter for Technical Revision 81 - South Taylor Fill and PMT Changes. The
responses were received on 2 June 2010 (dated 1 June 2010). The Division has reviewed
Colowyo's responses and has the following comments and adequacy questions.
Rule 2.05.3(6) - Overburden
1. Response Accepted. Colowyo addressed the subsidence concerns due to highwall mining
on Page 6 of Addendum 3 to the Shannon and Wilson Report (revised 15 April 2010).
2. Response Not Accepted. In its response Colowyo states that "Colowyo has not chosen to
change the swell factor to 15% at this time... in the future when Colowyo deems it
prudent to change the permitted swell factor..." Colowyo's brief answer to the
Division's adequacy question raises as many questions and concerns as the original
statement that it was planning on changing the approved swell factor. The swell factor
for overburden for a surface mine is not only important for cost estimating and
reclamation liability purposes, it is also necessary for making decisions regarding
backfilling and grading plans and schedules, post-mining topography and excess spoil
fills, to name a few. An operator cannot just "deem it prudent" to change a swell factor.
Colowyo has been mining in the same basic geologic formations for more than 30 years
and there is a well established history with regards to the mine's swell factor. The
decision to change a swell factor at Colowyo is not one that is taken lightly. The swell
factor at the Colowyo Mine is either 15% or 20% or some other number that can be
documented and justified. It should represent an average of the swell factors from
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