2010-10-14_REVISION - C1981019

• Permit No: C1981019
• IBM Index Class Name: REVISION
• Doc Date: 10/14/2010
• Doc Name: Preliminary Adequacy Review Letter
• From: DRMS
• To: Colowyo Coal Company, LP
• Type & Sequence: TR87
• 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
AD
Denver, Colorado 80203
F
D IV I ON
DV IS
OF
Phone: [phone] RECLAMATION
FAX: [phone] MINING

SAFETY
14 October 2010
Bill Ritter, Jr.
Governor
Mr. Ryan Pawlowski
Colow o Coal Compan
LP
y Mike King
y, Executive Director
5731 State Highway 13
Meeker
CO 81641 Loretta E. Plheda
, Director
Re: Colowyo Mine C-1981-019
Preliminary Adequacy Review - Technical Revision 87
Dear Mr. Pawlowski:
Technical Revision 87 was submitted in three separate parts. The initial submittal is dated 10
August 2010 (received on 11 August 2010). The second submittal is dated 3 September 2010
(received 7 September 2010). The third submittal is dated 23 September 2010 (received 27
September 2010). The second and third submittals included changes based on abatement steps
for Notice of Violation CV-2010-004 and meetings with the Division. The Division has reviewed
the information from all three submittals at this point.
In addition to other materials submitted, TR-87 presents and proposes three time-specific
SEDCAD models for the Prospect watershed, demonstrating that the sediment control system of
stock tanks, diversion ditches and the Prospect Pond will treat storm runoff to the required
effluent limitations in all three scenarios. Included in the modeling are five stock tanks within the
three constructed drainages above the Prospect Pond. The five stock tanks are included in the
time-specific SEDCAD models when they are constructed. These five stock tanks are no longer
secondary sediment control structures but are primary sediment control structures, which require
them to be designed, constructed and maintained similar to a sediment pond. As primary
structures, the stock tanks are not eligible for an inspection waiver. They will be treated no
differently than a sediment pond once they are constructed and will require a quarterly inspection
pursuant to Rule 4.05.9(14).
The Division has also asked Colowyo to include additional reclamation practices such as contour
ditches, surface roughening, terraces, etc. over the last few years following the issuance of CV-
2008-004, because of the Prospect Pond failure in August 2008. Colowyo has included a
commitment to use surface roughening and contour furrows in the East Pit on revised page 2.05-
30.
The following adequacy questions are based on the Division's review of the three packages of
material submitted by Colowyo for Technical Revision 87.
Office of Office of
Minprd I anrd Rprlamatinn Denver • Grand lunction • Duraneo Active and Inactive Mines