2010-01-08_REVISION - C1996083 ‎(4)‎

• Permit No: C1996083
• IBM Index Class Name: REVISION
• Doc Date: 1/8/2010
• Doc Name: Review Memo
• From: Mike Boulay
• To: Joe Dudash
• Type & Sequence: TR65
• Email Name: JJD
• 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]
INTEROFFICE MEMORANDUM
TO: Joe Dudash
FROM: Mike Boulay Yl
DATE: January 8, 2010
SUBJECT: Bowie No. 2 Mine, Permit No. C-96-083, Technical Revision No. 65
COLORADO
DIVISION OF
RECLAMATION
MINING
SAFETY
Bill Ritter, Jr.
Governor
Harris D. Sherman
Executive Director
Ronald W. Cattany
Division Director
Natural Resource Trustee
As requested I have reviewed Technical Revision No. 65 (TR-65) regarding groundwater aspects of
the amended B-Seam Mine Plan which includes development of mains to the west beneath Terror
Creek and the North Mains Rooms located above the East Mains, and drilling of one new
geotechnical hole. I have also reviewed Technical Revision No. 66 (TR-66) regarding installation
of a ventilation shaft west of Terror Creek. Since the vent shaft is proposed at the approximate
same location of the geotechnical hole proposed with TR-65 these revisions are interrelated and
were reviewed together. I will submit a separate memorandum to you for TR-66 for scanning and
documentation.
Two separate new mine plan areas (the main entries beneath Tensor Creek and the North Mains
Rooms) need to be addressed with TR-65. Since BRL is proposing new disturbance beyond the
current monitoring network of wells, they will be required to install and monitor additional down
gradient wells. Monitoring will be required in the B-Seam and strata above the B-Seam only. With
recent Permit Revisions (PR-10 and PR-11) BRL successfully demonstrated to the Division that
groundwater beneath the lowest coal seam to be mined (Rollins sandstone) would not be impacted.
Permit text regarding no impact to the Rollins sandstone has been approved and incorporated into
the permit text (see page 2.05-75ii). The Rollins sandstone is a confined aquifer under piezometric
head. Confining shale layers above the sandstone and the piezometric head should prevent any
integration of water from the overlying D-Seam or B-Seam into the Rollins sandstone. It is
reasonable to assume that these same subsurface conditions exist at the west end of the permit
boundary in the vicinity of Terror Creek, which would alleviate the need for additional down
gradient monitoring and point of compliance wells in the Rollins sandstone. BRL should be able to
demonstrate this through drill log data or other geotechnical information and update the permit
accordingly for both the Terror Creek main entries and North Mains Rooms.
Office of
Mined Land Reclamation
Denver • Grand Junction • Durango
office of
Active and Inactive Mines