GENERAL42418

• Permit No: M1980244
• IBM Index Class Name: General Documents
• Doc Date: 6/15/1995
• Doc Name: FAX COVER PROVISION OF INFORMATION UPDATING THE ESITMATION OF LEAKAGE RATES
• From: CRIPPLE CREEK & VICTOR GOLD MINING CO
• To: DMG
• Media Type: D
• Archive: No

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~~ Cripple Creek & Victor Gold Mining Company ~iUN 15 1995
A Joinl Venture -Pikes Peak Mining Company, Manager
~R 7 Operations Office Englewood Ottlce OivlSiOn ~~f rviin61815 n GB010
`~/ P.O. Box 191, 2755 State Highway 67 5251 DTC Parkway, Suite 700, Englewood 9Y
Victor, Colorado 80860 Colorado 80111
[phone] • FAX [phone] [phone] • FAX [phone]
June 13, 1995
SENT BY FACSIMILE AND EXPRESS MAIL
Mr. Berhan Keffelew
Environmental Protection Specialist
Colorado Department of Natural Resources
Division of Minerals and Geology
Office of Mined Land Reclamation
1313 Sherman Street, Room 215
Denver, Colorado 80203
Reference: Provision of Information Updating the Estimation of Leakage Rates.
Dear Mr. Keffelew:
This letter provides the information that the Office of Mined Land Reclamation ("OMLR") has
requested on a number of occasions and which the Cripple Creek & Victor Gold Mining
Company ("CC&V") agreed, in our meeting of May 28th, to provide by mid-June. This
information updates section 4.8 of that portion of the approved Mining and Reclamation Plan
contained in Volume II of the Application (as "Appendix 1") and titled "Permitting Level Design
Evaluation of the Expansion of the Mining and Ore Processing Facilities -Cresson Project."
That section draws upon experience with solid waste land fills to project anticipated leakage rates
and to identify actions that an operator would undertake should leakage meet numeric levels.
This update has been developed by Golder Associates and is necessary to conform the
projections with the as-built conditions. The focus of the update is on the Pregnant Liner System
("PLS").
The premise for modeling purposes remains the same for these calculations as in the past, that
is the presence of one hole, 2 mm in diameter, per acre. The input and the model are those
presented by the EPA for landfills (rather than mining operations). The input to the model was
updated for the Phase I PLS configuration.
Results of the projections for the 50th, 90th, and 98th percentiles of the probabilistic
computations are provided as the Attachment to the Golder Associates letter of May 24, 1995
which is included with this letter as Attachment 1. Linear extrapolation between points is
acceptable.
We need to stress that the EPA developed its guidance (referenced in the Golder Associates
Attachment) to mitigate the potential for solution accumulating between the top and bottom liner
of a leak detection system. The EPA worked from cases in which the leak detection system was