PERMFILE128720

• Permit No: M2007014
• IBM Index Class Name: Permit File
• Doc Date: 5/30/2007
• Doc Name: Adequacy Review and Engineering analysis and Agency Responses
• From: DRMS
• To: Byzantine Quarries
• 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: (303)832$106
DATE: May 25, 2007
TO: Deb Zack ~~~
FROM: Allen Sorenson ~f- `--~
COLORADO
DIVISION OF
RECLAMATION
MINING
- &-
SAF ETY
gill Ritter, jr.
Governor
Harris D. Sherman
Executive Director
Ronald W. Cattany
Division DireROr
Natural Resource Trustee
RE: Quarry Wall Stability, Larsen Colorado, L.L.C., Byzantine Quarry, File No. M-2007-014
The Division of Reclamation, Mining, and Safety (DBMS) engineering staff has reviewed the
geotechnical stability exhibit to the above referenced application. Section 6.5-1 of the exhibit is a
geotechnical report prepared by J.A. Cesare and Associates. This report describes geotechnical
observations and measurements made at the quarry face following the first production blast, and provides
recommendations for future quarry development to provide a highwall configuration that will be stable in
the long term. The report describes two types of geologic structures that influence highwall design; those
being bedding planes and joints. The joints are described as clay filled and dipping into the quarry face.
With this dip angle, the joints will not be a source of instability. The bedding planes dip out of the quarry
face and aze described as moderately rough and without clay filling. The report goes on to recommend
stable quany face angles and benching criteria. The Operator has committed to abide by the
recommendations contained in the report, and the DBMS concurs that the recommendations are
appropriate to provide a stable highwall. Therefore, DBMS engineering staff recommends that the quarry
face angles and benching criteria provided in the report be approved as an enforceable component of the
permit, but the Applicant must commit to the following:
During each year when development and/or production blasting occurs in the quarry, the Operator
shall include a geotechnical section into the annual reclamation report providing updated
geotechnical observations and measurements and associated recommendations for quarry
development to provide a safe highwall during operations and a long term stable highwall at the
time of reclamation. In particular, the geotechnical observations and measurements will include
evaluation of the presence or absence of clay filling in geologic structures that dip out of the quarry
face, and will evaluate any changes in orientation, spacing, and roughness of geologic structures
observed relative to the observations documented in the initial report.
This commitment is necessary because the benched highwall could fail along low friction bedding planes
as illustrated in the attached diagram, and also because the nature and orientation of the geologic structure
will vary as quarrying proceeds. DBMS notes that the J.A. Cesaze report states "(t)he stability of the
quarry walls should be continually monitored and evaluated as mining progresses.
Office of Office of
Mined Land Reclamation Denver Grand Junction Durango Active and Inactive Mines