PERMFILE44448

• Permit No: M1996052
• IBM Index Class Name: Permit File
• Doc Date: 6/20/1997
• Doc Name: STABILITY OF THE SINCLAIR PIPELINE OWENS BROTHERS CONCRETE CO DEL CAMINO PIT FN M-96-052
• From: DMG
• To: GARY CURTISS
• Media Type: D
• Archive: No

•
DIVISION OF MINERALS AND GEOLOGY
Deparlmem of Natural Resources
131 {Sherman 51., Room ? I S
Denver, Colorado A0203
Phone: [phone]-J 567
FA%:13031 A3?-A106
~ III IIIIIIIIIIIIIIII
STATE OF COLOlZADO
~~
DEPARTMENT OF
NATURAL
RESOURCES
Roy Romer
DATE : June 2 0 , 1997 envernor
lames 5. Luchhead
EwecWive Dveaor
TO: Gary Curtiss ~~
Michael B. Long
Division Dvecmr
FROM: Allen Sorenson
RE: Stability of the Sinclair Pipeline, Owens Brothers Concrete
Company, Del Camino Pit, File No. M-96-052
I have completed a review of the letter report prepared by David Glater
titled "Geotechnical Engineering Opinion and Response to Comments Post-
Mining Stability of the Sinclair Pipeline Easement." This report is dated
November S, 1996 and was prepared in support of the Owens Brothers
Concrete Company permit application for the Del Camino Pit, File No. M-96-
052. The following issues related to the conclusions and proposals
contained in the report must be addressed before the Division can accept
the engineering evaluation that the integrity of the pipeline will not be
affected by the proposed mining operation.
1. It is proposed in the 11/8/96 letter report that the applicant will
maintain temporary pit slopes no steeper than O.SH:1V. It would be
unprecedented for the Division to accept a commitment to mine at a slope
no steeper than O.SH:1V, and such a permit commitment would give rise to
a number of concerns.
a) Maintenance of O.SH:1V temporary slopes is not possible using
conventional gravel mining methods in which the gravel is excavated
from the toe of a cut or in which the gravel is pushed down into the
pit from the top of the bank. For the Division to accept a
commitment to mine at O.5H:lV, the applicant would have to provide
a detailed description, in terms of the mechanics of earth moving,
as to how this slope will be maintained.
b) The Division must be concerned about the rigor that would be
applied during pit operations to assure that temporary slopes are no
steeper than O.5H:1V. To often, commitments such as this are made
in permits and not adequately communicated to the workers that are
actually digging the gravel. To better assure compliance with any
such commitment, the applicant would have to commit to a strict
slope surveying and reporting program, such as monthly slope surveys
certified by a professional licensed surveyor or other qualified
individual, with the results of the surveys provided to the
Division, also on a monthly basis. I would, however, strongly