PERMFILE136515

• Permit No: M2005071
• IBM Index Class Name: Permit File
• Doc Date: 9/5/2006
• Doc Name: Request to review and comment on draft Board Order
• From: Gregory D. Lazear
• To: MLRB
• Media Type: D
• Archive: No

SEP-07-2006 05:15PM FROM-DIV RECLAIAAT'nN MINING & SAFETY 3038329102 T-109 P.002/005
1
RECEIVED RECE~vE~
SEP 13 2006 2U06 ~/ August 29, 2006
SEP 0 5 Lion. ~m.-t Gregory D. Lazeaz ~~
Division of f~eciamation, D1Vision of Redama
Mining and Safety - ana safety . 20508 Brimstone Rd.
Ntm~ng Cedaredge, Colorado 81413
(970) SS6-6810
Benson Brothers Red Shale Quarry
File No. M-2005-07I~ ~_~~Y~ x' C~1"~'~"'
1, Y'~~~ ~ "i~
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~0. Dear MLR BOard,`~~ ~Lq ueS+- 'Fo ,- /~~.J d-Q©Mr,C? ~o~'!J~q F~
o,.~ O(~d~~ L~
As a party to the hearings, T am requesting to be allowed to review and comment
on the draft clarification produced by the Board regarding monitoring of vibrations at the
proposed Benson Brothers Red Shale Quarry in Coalby Valley, Delta County, Colorado.
A summary of my position with regard to the proposed clarification is as follows.
1) Hitting operations will proceed from north to south over the lifetime of the
quarry (20 years).
2) The closer the operation gets to the Rollins sandstone cliff that lies on the south
boundary, the greater the risk of rockfall damage to adjoining property.
3) Lowering of the south ridge by 50 feet will pose the greatest rockfail threat due
to vibrations produced while ripping bedrock in close proximity to the cliff, aad
by exposing bedrock joints near the cliff to direct infiltration by precipitation.
4) Natural resonance phenomena can produce greatly enhanced vibration
amplitudes that will change over time as mining alters the geometry of the ore
body.
S) Therefore, rockfall hazard induced by the mining operation istime-varying,
and requires periodic monitoring throughout the life of the operation.
6) The current proposal to monitor vibrations for up to 30 days following start-up
was hastily thrown together at the end of the MI.RB hearing in order to address
the obvious lack of any relevant data regazding rockfall risk at the proposed
quarry site. It does not constitute a well thought-out monitoring program
designed to address citizen concerns of rockfall risk throughout the life of the
quarry.
7) I urge the DMG staff to design, and the MLRB to require, a periodic
monitoring program, with measurements taken at repeatable sites, that will
detect changes in vibration impacts and rockfall risk as the mining operation
proceeds. This would provide an early warning if vibration amplitudes approach
dangerous levels. Monitoring of piezometric head in bedrock joints near the
cliff would provide a baseline dataset prior to removal of the south ridgeline.
This data would allow the detection of mining induced changes in joint pressure
that can greatly increase rockfall risk.
8) A well designed monitoring program would serve as insurance to protect
citizens from collateral property damage, and could protect Beason Brothers
from costly litigation in the event of a damaging rockfall by providing direct
evidence regarding the cause of the fall.
F-295