Planning for abandonment at the Willa gold-copper project of Northair Mines Ltd.

• Main Author: Brodie, John B.
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/12877

Development of the Willa gold-copper project, in the Slocan Lake area of British Columbia, has presented some challenging design problems associated with the potential for acid generation from mine waste rock and tailings. Solutions to these problems are available but require early planning and implementation in order to guarantee effectiveness. Important abandonment concepts developed for the Willa project include the following: creating an impervious tailings basin by pond sealing in order to facilitate operation of a permanently flooded system utilizing natural inflows of ground and surface water; encapsulating waste rock in the tailings embankment such that the rock is isolated from air, thus depriving it of a critical reactant in the oxidation process; and modifying the acid/base ratio of tailings deposited in the final months prior to mine closure. Reclamation of the tailings pond as a wetland environment will provide for long-term environmental protection and will also produce an aesthetically pleasing marsh habitat suitable for waterfowl. This type of habitat is currently absent in this region of the Slocan Valley. Three rules are presented for successful abandonment planning when acid mine drainage is a possibility: 1) consider abandonment strategies during initial planning and feasibility studies rather than leaving them until mine shutdown is imminent; 2) provide defence-in-depth for potential problems; and 3) plan for abandonment with the assumption that you or your company will be financially liable for any failures.