PERMFILE54329

• Permit No: M2007044
• IBM Index Class Name: Permit File
• Doc Date: 11/14/2007
• Doc Name: Cost estimate for water impounding concrete bulkheads
• From: DRMS
• To: File
• Media Type: D
• Archive: No

STATE OF COLORADO
I ~ DIVISION OF RECLAMATION, MINING AND SAFETY /
---CCC Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
DATE: November 14, 2007
TO: Russ Means
FROM: Allen Sorenson
~~ S
~~ ~ ~( ,'~
GL~ ~'
COLORADO
DIVISION OF
RECLAMATION
MINING
- &-
SAFETY
eil4 Ritter, {r.
Governor
Harris D. Sherman
Executive Director
Ronald W. Cottony
Division Director
Natural Resource Trustee
RE: Cost Estimate or Water Impounding Concrete Bulkheads, Energy Fuels Resources
Mine, File No. M-2007-044 ;/
The Division of Reclamation, Mining, and Safety (DBMS) engineering staff have completed a review of the
underground water impounding bulkhead information provided in the Whirlwind Mine permit application
as supplemented by the Bulkhead Locations plan provided by Lewicki and Associates and dated October
27, 2007. The Applicant proposes a main bulkhead 148 feet in elevation below the decline portal where the
decline dimensions are 12' x 9' and there is approximately 470 feet of ground cover. A secondary bulkhead
is proposed for a location 134 feet in elevation below the decline portal. Lewicki and Associates has
recently communicated to the DBMS that the upper bulkhead is no longer deemed necessary since the
Bureau of Land Management is requiring the decline portal to be backfilled. However, the DBMS will
require that an upper water impounding bulkhead be bonded as a contingency as discussed in the memo
dated November 6, 2007 (Allen Sorenson to Russ Means). The same memo describes the need to bond for
a contingency bulkhead in the Packrat Mine workings. For the purpose of estimating a cost, DBMS will
assume conservatively that the Packrat Mine bulkhead would be installed 268 feet in elevation below the
decline portal where the adit dimensions are 12' x 9' and at a location where there is sufficient ground cover
to prevent hydrofracing of the formation around the bulkhead. It is indicated in the application that precise
location selection and detailed designs for the bulkheads is premature at this time; DBMS concurs. It is
necessary to preliminarily consider design basis for the bulkheads in order to estimate costs, and this memo
provides an analysis of the type of bulkheads that will be necessary in order to develop costing information
and estimate the amount of bulkhead bond to be required.
Einarson and Abel (1990) present astep-by-step procedure for design of underground water impounding
bulkheads. Conservatism in design of the bulkheads is necessary because of the safety and environmental
implications of a bulkhead failure, the long life required for the bulkheads, and the ultimate inaccessibility
of the bulkheads. The American Concrete Institute's "Building Code Requirements for Reinforced
Concrete (ACI 318-89)" is used because the bulkheads are analogous to reinforced deep-beam concrete
structures and because of the inherent conservatism of the code. The analysis presented in this memo
generally follows the Einarson and Abel template.
The maximum hydraulic head and pressure at the proposed main bulkhead are as follows:
H =148 feet
P_ Hyw 2 _148x62.4 =64 psi
144in / ft 144
Office of Office of
Mined Land Reclamation Denver Grand lunMion Durango Active and Inactive Mines