Here is a challenge written up in a recent comment on a previous blog posting:
I would love to see someone write a paper on the merits of a wet tailings pond. Today’s lovechild seems to be the filtered tailing concept but let’s hear some kudos for a properly designed wet tailings pond. It gives the ability to deal with seasonal or short term storm water surges, the ability to store water for use in low flow periods, avoids needing to continually withdraw process water from rivers or lakes, keeps ARD materials submerged, lower capex & opex, lower power consumption via natural clarification instead of mechanical clarification, and less greenhouse gas emissions related to lower power consumption. Where are the friends of the conventional tailings pond or have they gone into hiding from the filtered tailings mob?
Today I had lunch with John Gadsby who is 82 and still active in tailings. Way back in 1983, he and Syd Hillis were the peer reviewers of my work on the design and construction of the Cannon Mine tailings facility besides Wenatchee, Washington. I asked him the questions implicit in the comment above.
He quickly reminded me that the Cannon tailings facility was a very successful wet tailings deposition facility that was also designed to contain lots of water from heavy rains in the catchment area of the Cascades. He reminded me that that facility was built to be secure as it is upgradient of a significant part of Wenatchee. He said he thought the facility must surely represent the best tailings technology for wet tailings deposition ever. And now it is closed and part of the Dry Gulch Riding Stables–an asset to the local community.
Without being too bold & boastful, I know this dam was good, is good, and will remain stable for a very long time hence. It proves, in my mind, that you can mine close to communities, can safely manage wet tailings in sensitive environments, and can close mine sites for sustainable use. Here are links to some papers I wrote on its design & construction:
You can get all these papers by going to the InfoMine Library and doing a search for Cannon Caldwell. You can also get a lot more information at the official Cannon Mine website.
So now let us have a debate about whether this tailings facility built in 1983 and 1984 represent current best practice or best available technology for wet tailings management. I think it does, but then I am hopelessly prejudiced. And I recognize parochial sentiments sometime inhibit cross-boarder admiration of engineering works. Still you can get there in a four-hour drive from Vancouver. Go see it sometime.