PERMFILE63007

• Permit No: M2005071
• IBM Index Class Name: Permit File
• Doc Date: 4/20/2006
• Doc Name: Reveiw Stability during quarry ops
• From: DMG acs
• To: sss
• Media Type: D
• Archive: No

STATE OF
DIVISION OF MINERALS ANO GEOLOGY
Department of Natural Resources
1313 Sherman S[., Room 215
Denver, Colorado 80203
Phone: {303) 866-3567
FAX: (303) 832$106
DATE: April 20, 2006 Y
TO: SCeve Shuey
FROM: Allen Sorenson ~~
COLORADO
DIVISION O F
MINEBRALS
GEOLOGY
RECLANATION•NiNING
SAffTY•SCIENCE
sin ovens
Governor
Russell George
Executive oin±ctor
Ronald W. Cottony
l Division DirMar
y',/ Naturzl Resource Trustee
RE: Review of Rollins Sandstone Cliff Stability during Quarry Operations,
Benson Brothers, Red Shale Pit, File No. M-2005-071 /'
The Division of Minerals and Geology (DMG) engineering staff have reviewed the following
documents relating to the potential for rock fall to be caused by operations at the proposed Red Shale
Pit/Quarry:
• Revey and Associates, Inc., "Impacts of Mechanical Equipment at Benson Brothers Proposed
Red Shale Quarry on Rock Bluffs," Report of Investigations, February 2006
• Gregory D. Lazear, "A Review of the Revey and Associates, Inc., Report of Investigations,"
April, 11, 2006
• Robert Flinn, "Memo to Greg Lazear, Red Shale Quarry Report," April 10, 2006
• Gregory D. Lazear, "Follow up Letter to: A Review of the Revey and Associates, Inc., Report
of Investigations," April, 13, 2006
• Paul Peter Urone and Patricia Urone, "Objection to the Benson Brothers Red Shale Quarry in
Coalby Canyon," April 18, 2006
• Revey and Associates, Inc., "Response to concerns regarding the Seismic Stability of the
Rollins Sandstone Bluffs adjacent to the proposed Red Shale Quarry in Delta County, CO"
April 19, 20(16
While DMG recognizes that the additional vibration analysis rigor suggested by objectors to the DMG
recommendation to approve the permit application has some scientific merit, it is DMG's
determination that additional pre-mining investigations are unnecessary to assure that offsite damage
will be prevented.
DMG has considerable experience in similar quarry proposals, where the potential for quarry
operations to cause damaging rock fall has been evaluated. In particular, the South Table Mountain
Quarry application (file no. M-1992-112} was denied, in part, because the potential for the proposed
operation to exacerbate rock fall had not been sufficiently resolved. Similarly, operations at the
Summit Pit {file no. M-1988-102) were curtailed and eventually terminated, partly due to the inability
of the Operator to demonstrate that damaging rock fall would not result from on-going operations.
One of the chief differences between these quarries and the proposed Red Shale Quarry is that both
South Table Mountain and the Summit Pit would use blasting to fragment rock for further processing.
Office of Office of Colorado
Mined Land Reclamation Atlive and InaEtive Mines Geological Survey