2013-08-27_REVISION - M1977342

• Permit No: M1977342
• IBM Index Class Name: REVISION
• Doc Date: 8/27/2013
• Doc Name: TR-20 REQUEST
• From: OPERATOR
• To: DRMS
• Type & Sequence: TR20
• Email Name: PSH
• Email Name: TAK
• Media Type: D
• Archive: No

Climax Molybdenum COLORADO OPERATIONS
Henderson Mine and Mill
P.O. Box 68
A Freeport- McMoRan Company Empire, CO 80438
Phone [phone]
Fax [phone]
August 23, 2013 P 5 �/� A4,
Certified Mail: 7006 2150 8831 9681 RECEIVED
Mr. Peter Hays AUG 2 7 2013
Environmental Protection Specialist
1313 Sherman Street, Room 215 DIMSION OF RECLAMATION
Denver, CO 80203 MINING AND SAFETY
Re: Climax Molybdenum Company, Henderson Mill, Permit No. M- 1977 -342
Proposed Technical Revision No. 20, Droptower 17 Removal
Dear Mr. Hays,
Climax Molybdenum Company (CMC) is hereby submitting this request for a new Technical
Revision (TR -20) for the removal of droptower 17 from the tailing delivery line (TDL). The
droptowers in this line serve primarily as energy dissipation structures, which limit the energy
potential in the tailing slurry flowing within. As the elevation of the tailing facility increases,
these droptowers are periodically removed when the downstream energy has reached
manageable levels. When left in place longer than necessary, these structures can inhibit the
required flow to the leadoff and spigot deposition structures, providing inadequate pressures.
Removal of this structure will ensure that adequate flow velocity and pressure is seen at the
deposition points.
To address this, Henderson, in conjunction with W.W. Wheeler & Associates has developed the
attached plan to remove droptower 17 and replace 1,025 linear feet of reinforced concrete pipe
(RCP) with 42 -inch HDPE pipe. With this project, a new transition block will be constructed
roughly 75 -feet upgradient of the current droptower 17 location. This block will serve as a
transition from the 36 -inch RCP up- gradient to the 42 -inch HDPE pipe on the down- gradient
side. Also planned for this project is the installation of a vent riser and a level sensor installation
on droptower 16. The purpose of the level sensor (currently located on droptower 17) is to alert
mill personnel that there is a blockage of tailing flow in the TDL.
This project is scheduled to begin on September 27, 2013. All construction activities will follow
the included construction drawings, provided by W.W. Wheeler & Associates, the engineer of
record for the project. Following the completion of this project, Henderson will supply the
DRMS with an engineering certification and as -built drawing for your files. A check is also
included with this submittal for the new Technical Revision fee and an email with all of this
information will be sent to you on August 23, 2013.