Dry-Stack vs. Wet Tailings

Posted by Stop Ajax Mine on February 23rd, 2015 4:16am

Earlier this week, the Mount Polley Review Panel recommended that BC mines use dry-stack tailings storage instead of wet tailings storage.  Today’s Kamloops This Week announced that KGHM Ajax will be studying a return to the dry-stack storage facility which was part of the orginal mine plan.  This study could take 2-3 months, which may cause a delay in the company’s application which was expected in May, 2015.

Here is the article.  Note that the Tailings Storage Facility in the present mine plan would not only cover Goose Lake, but also the Antoniak ranch and a portion of the Goose Lake Road.

KGHM Ajax to revisit dry-stack tailings option at proposed mine

By: Cam Fortems , February 4, 2015    

KGHM Ajax will conduct a “trade-off study” to determine whether it will return to a dry-stack tailings system for its proposed mine in wake of a report advocating the technology.

The Mount Polley Review Panel report recommends B.C.’s mining industry adopt dry-stack tailings, what it calls best-available technology, that would ensure a dam breach cannot happen at a new mine.

Clyde Gillespie, manager of project development for KGHM Ajax, told KTW the company committed to looking closely at the Mount Polley report in wake of the dam breach that flooded Polley and Quesnel lakes. “We’re revisiting our tailings-management plan and revisiting whether dry-stack tailings is the best fit with Ajax,” Gillespie said.

The technology is relatively new. It was proposed in KGHM Ajax’s first mine concept, which the company abandoned in order to move its footprint farther south and switch to a wet-tailings pond. KGHM’s original dry-stack tailing pile would have been visible from the Coquihalla Highway and also raised public concerns about dust.

“Most commonly used in dry climates where economy in water consumption is important, it has also been adapted to cold regions,” the Mount Polley report stated. “This method has been used since start-up of the Greens Creek mine in Alaska under conditions not unlike coastal B.C.”

Gillespie acknowledged it will be expensive and time-consuming to conduct the trade-off study that will measure dry-stack tailings against the current plan to store tailings beneath a pond over what is today Goose Lake. Since the Mount Polley breach, there have been public concerns about a breach of the proposed dam that could lead to a wall of water down Peterson Creek and into downtown Kamloops. The study will also look at locating the dry-stack tailings pile at the location where the wet-tailings pond is now planned.

Gillespie estimated the study will take two to three months. The chosen method will be included in KGHM Ajax’s application, expected early this year, as the preferred option.

Meanwhile, the corporation that controls undeveloped property in Aberdeen is concerned about effects of KGHM Ajax’s proposed wet-tailings dam that it says could increase underground pressures and have “catastrophic” consequences to existing homes and developable property.

Aberdeen Highlands Development Corp. expressed the concerns in a letter to the provincial Environmental Assessment Office (EAO) as part of its public comment period, which is now closed. “Groundwater seepage from the pit and the tailings-storage facility will impact the lands downslope and north of the mine in many ways . . .” Aberdeen Highlands wrote. “Any additional rises in piezometric pressures will have catastrophic consequences to existing homes and any future development of the stakeholder lands.”

The corporation cites a report from engineering firm Golder Associates that notes groundwater recharges from as far as Chuwels Mountain, 19 kilometres away, makes their way to the Aberdeen neighbourhood. “Certainly a wet-storage tailings lake (two kilometres from Aberdeen) with a projected capacity of 400-million tonnes of tailings will have significant influence on the piezometric pressures in the Aberdeen neighbourhood . . .” Aberdeen Highlands wrote.

Aberdeen Highlands did not respond to phone calls from KTW requesting an interview.

The letter from the developer says the city has designated Aberdeen to receive 48 per cent of its future growth, a potential Aberdeen Highlands says could be compromised by the mine and its tailings storage. The corporation also makes a number of suggestions for KGHM Ajax’s proposed application, including new groundwater wells that would be monitored for at least a year to gain understanding. The letter also asks the EAO to determine whether there is bonding or insurance in case of tailings failure or other negative impacts.

KGHM Ajax declined to comment on the letter, stating it will respond as part of the EAO process.

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