Does Tony Hayward’s environmental record influence your view of the PolyMet mining project?

Tony Hayward was leading BP in 2010 when the Deepwater Horizon exploded and killed 11 workers in the Gulf of Mexico. The accident is the largest oil spill in marine waters. Hayward now leads Swiss company Glencore Xstrata which is the largest investor in the proposed PolyMet copper-nickel mining project in northern Minnesota.

Background on the environmental issues and remedies

Why are environmentalists concerned about the PolyMet proposal?

They say copper-nickel mining is much more dangerous than iron ore mining, because the minerals are trapped in rock containing sulfide. When that ore is unearthed and exposed to air and water, it produces sulfuric acid, which if not contained, can leach heavy metals and contaminate ground and surface water. That process is often called “acid rock drainage” or “acid mine drainage.” Environmental groups say a copper-nickel mine has never operated without polluting surrounding waterways, even when environmental impact statements for projects have been approved. They say it’s too risky to permit mines with this track record in a water-rich and sensitive environment that drains into Lake Superior (the PolyMet proposal) or the Boundary Waters (the Twin Metals proposed development).

They are also concerned that PolyMet could pave the way for other nearby mines. Currently eleven other companies are exploring for copper, nickel and precious metals in the surrounding area. If those mines are all approved, mining opponents fear the cumulative impact of the operations could have damaging effects not only on water quality but on the pristine wilderness character of the area.

How does PolyMet plan to contain pollution?

At the mine site, waste rock with the lowest sulfur content will be placed in a stockpile with a groundwater containment system. Remaining waste rock will be temporarily stored on foundations and liners, and eventually backfilled into the mining pit and covered with water to reduce the potential for acid generation. Water control systems will be installed to capture and treat water that has come in contact with waste rock or the mining pits.

At the processing plant site, PolyMet has proposed to build a groundwater containment system to collect water seepage from the tailings basin, which covers an area roughly two square miles in size. That water would then be funneled into a water treatment plant that would use “reverse osmosis” to purify the water.

What is reverse osmosis and how effective is it?

Reverse osmosis is a technology that forces water under high pressure through a semipermeable membrane that traps minerals, salts, chemicals and other impurities in the water. It’s been used in water desalination plants since the 1970s. It’s also employed at wastewater treatment facilities. More recently some mines have begun to use it to treat water before discharging it to the environment.

PolyMet is proposing to build a reverse osmosis water treatment plant at the processing plant site during mine operation, and a second facility at the mine site after closure. The company has built a test facility in Virginia where it has successfully processed about three million gallons of water. PolyMet officials say they added the technology to mine plans after the initial draft EIS was criticized by the EPA in 2010 to meet Minnesota’s 10 mg/liter sulfate emission standard designed to protect wild rice.

Mine critics don’t question the technology itself, but they’re skeptical as to whether PolyMet will be able to successfully capture all the water at the mine site and from the tailings basin that will then be treated by reverse osmosis. For example, they say the bedrock under the tailings basin is fractured, and argue that some water will escape the site before it can be treated by reverse osmosis. They also say the technology is very energy intensive, and produces a byproduct known as “brine” that has to be disposed of properly. Finally, they argue that the technology is very expensive to run, and question who will pay to operate the plants if they’re needed for up to 500 years or even longer after the mine is closed.

More FAQ: Everything you need to know about PolyMet

Today’s Question: Does Tony Hayward’s environmental record influence your view of the PolyMet mining project?