2010-03-11_REVISION - C1980007

• Permit No: C1980007
• IBM Index Class Name: REVISION
• Doc Date: 3/11/2010
• Doc Name: Adequacy Review Comments
• From: DRMS
• To: Mountain Coal Company, LLC
• Type & Sequence: TR120
• Email Name: TAK
• 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]
March 11, 2010
Kathleen G. Welt
Mountain Coal Company, LLC
P.O. Box 591
Somerset, CO 81434
Re: West Elk Mine (Permit No. C-1980-007)
Technical Revision No. 120 (TR-120)
Refuse Pile Expansion East
Dear Ms. Welt:
COLORADO
DIVISION OF
RECLAMATION
MINING
SAFETY
Bill Ritter, Jr.
Governor
James B. Martin
Executive Director
Additional adequacy review comments 16 through 22 are provided below. In addition to new comments,
the comments document Marcia Talvitie's previous comments of February 24, MCC's March 9th
responses to those comments, and her follow-up comments of March 10.
16. DRMS 24-Feb: Section 2.2.2 (Model Parameters) explains that Standard Penetration Tests
(SPTs) were conducted on in-place materials in the LRP. Data from the SPTs were analyzed to
establish the range of potential friction angle and undrained shear strength values to be
modeled. SPT and laboratory data for the LRP holes do not appear to have been provided with
Volume I OC. Please provide: a) a map showing the locations of the LRP borings in plan
view; and b) the boring logs, SPT values and laboratory results obtained for the LRP borings.
DRMS 10-Mar: a) In their March 9th response, MCC provided "Figure 1 - LRP Soil Boring
Locations". Please incorporate this map into the Figures of Volume IOC (suggestion: as
Figure 1-4).
DRMS 10-Mar: b) Boring Logs, SPT values and laboratory results for the LRP investigation
have been provided. Please incorporate the boring logs into Volume IOC -Appendix A.
Laboratory test results for the LRP were previously intermingled in Appendix B with results
from the RPE East investigation. Please organize the information presented in Appendix B
to make it easier to differentiate between the various investigations
17. DRMS 24-Feb: Figure 2-1 depicts friction angles of materials in the LRP plotted as a function
of depth. According to Section 2.2.2, the friction angles have been "determined from a blow
count correlation developed by Kulhawy and Mayne...". The friction angles so inferred range
from 26 to 58 degrees (or 62 degrees, as shown on Figure 2-2). Friction angles greater than 45
degrees are unlikely, even in well-compacted sandy gravels. I reviewed the K and M study
(available on the internet), and observed nothing in that report that supports the extremely high
Office of Office of
Mined Land Reclamation Denver - Grand Junction - Durango Active and Inactive Mines