PERMFILE126785

• Permit No: M2003001
• IBM Index Class Name: Permit File
• Doc Date: 1/28/2005
• Doc Name: Review of the Final Slurry Wall Construction Report
• From: DMG-acs
• To: DMG-tas
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OE MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman St., Room 215 lr ~ L ~ RA D ~
Denver, Colorado 80203 D I V 1 5 1 0 N O F
Phone: [phone]Vt 1 N &RA (, $
FAX: [phone] G E <] 1.O G Y
REC LAMATIO N•MI NING
sAFETT•SCIENCE
Bill Owens
DATE: January 28, 2005 cnvernor
Russell George
TO: Tom Schreiner Executive Director
Ronald W. Canany
/j ~
FROM: Allen $OCensOn {~'/ Division Director
Natural Resource Trustee
RE: Review of the Final Slurry Wall Construction Report, Hall Irwin Corporation, Nissen

Farm Resource Pit, Technical Revision TR-001, Permit No. M-2003-001 //
~lvss: P2rmi!-
The Division of Minerals and Geology (DMG) Engineering staff has completed a review of the final
construction report for the Nissen Farm slurry wall and has determined that there is a high probability that
the slurry wall will meet the leakage criteria performance standard established by the State Engineer for
lined pits. This determination makes the Operator eligible for the reduced bonding option for slurry walls
described in DMG's published guidance. However, the construction report identifies approximately 795
feet of the tota19500 feet, or about 8.4 percent, of slurry wall where the bedrock key maybe less than the
required 3 feet in depth. Lack of an adequate keyway may lead to an unacceptable amount of leakage
under the slurry wall. DMG guidance allows Operators that submit an adequate construction report to
bond for 20 percent of the cost for installation of the full slurry wall. With the potential for leakage under
8.4 percent of the slurry wall, DMG will require that for the Nissen Farm Pit the Operator bond for 28.4
percent of the slurry wall cost as follows:
Unit Cost for Slurry Wall: $3.00 per square foot
Nissen Farm Slurry Wall: 446,500 square feet
Bonding Rate: 28.4 percent
(0.284)($3.00/sq. ft.)(446,SOOsq. ft,) _ $380,418
$380,418 for potential leakage mitigation should be input as a direct cost line item in the estimation of
reclamation costs for the Nissen Farm Pit.
cc: Carl Mount, DMG (via email)
c:\acs\LOANER MACHINEU1y Documents\Nissen Farm slurry wall report.doc
Division of Minerals and Geology, "Guide to Specification Preparation for Slurry Walls and Clay Liners as a Component of a
Colorado Mined Land Reclamation Permit," September 2000
Office of Office of Colorado
Mined Land Reclamation Active and Inactive Mines Geological Survey