2009-05-04_REPORT - C1980007

• Permit No: C1980007
• IBM Index Class Name: REPORT
• Doc Date: 5/4/2009
• Doc Name: 1st, 2nd & 4th Qtr 2007 Seismic Review Memo
• From: TAK
• To: File
• Permit Index Doc Type: Stability Report
• 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 C O L O RA D O
D I V I S I O N o f
Phone: [phone] ON
L N
FAX: [phone] M I
G
- St _7
SAFETY
MEMO
Bill Ritter, Jr.
From: Tom Kaldenbach Governor
Harris D. Sherman
To: File
• Executive Director
West Elk Mine (C-1980-007) Ronald W. Cattany
Division Director
Report Natural Resource Trustee
Seismic Monitoring Reports for 1St, 2"d, and 4th Quarters 2007
Date: May 4, 2009
Re: Summary of DRMS Review
MCC's Subsidence Monitoring Plan requires monitoring of seismicity for identifying the
magnitude of seismic events at Monument Dam (Sections 2.05.6(6(b)(ii), (6)(c(ii), and
(6)(e)(iii) of the permit application). When MCC begins longwall mining in the E seam,
they will be required to make field measurements of monuments on the dam within two
days of any mining-caused seismic event that exceeds peak ground acceleration of 0.15 g
at the dam (permit application page 2.05-168). An accelerometer at the dam
continuously monitors seismic activity. Data from the Monument Dam accelerometer
and nine other accelerometers installed at the West Elk Mine and Bowie II Mine enable
determination of the geographic location and depth of each seismic event. The above-
referenced reports indicate the peak ground accelerations at the dam during the above-
referenced time periods did not exceed the 0.15 g threshold.
cc: Dan Hernandez, DRMS
Kathleen G. Welt, Mountain Coal Company
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines