Clean water and the PolyMet copper-nickel project




It is an unfortunate reality that the mining industry has made mistakes in its past. Many mines currently in operation – some more than 100 years old – began without the foresight and advantage of the modern technologies and mining methods used today. Unfortunately, taxpayers sometimes were left holding the bill to clean up those that closed.

In contrast, modern mines use advanced engineering and invest heavily in monitoring and protection systems to be responsible environmental stewards and meet rigorous environmental standards. Modern regulations – many based on the hard lessons learned from the past –protect both the environment and the taxpayer. Today’s mines must go through an extensive environmental review and permitting process before they can operate. The PolyMet Mining project is nearing completion of this process.

In the environmental review process (Environmental Impact Statement) potential environmental and socioeconomic impacts are identified and then plans are developed and approved to minimize, mitigate and manage those potential impacts. Issues that are identified during operation and after closure must be minimized, mitigated and managed before a permit is ever issued and before mining begins.

PolyMet Mining Reclamation Plan

PolyMet Mining has developed a site-specific reclamation plan for its proposed copper-nickel project near Hoyt Lakes in consultation with Minnesota state agencies. One objective of the site closure or reclamation plan is to identify and implement various reclamation activities and engineered systems to ensure the site meets groundwater and surface water quality protection standards including long after the mine is closed.

During the review and in consultation with state, federal and cooperating agencies, the company developed a water quality model to determine what engineering controls are needed for the project to comply with applicable water quality standards and to predict how water quality in nearby streams, lakes and groundwater may be affected by the project.

This model was designed to help determine what engineering controls are likely necessary, a range of potential impacts that may occur and to help inform the plan for monitoring. Opponents have used information gleaned from earlier drafts of the environmental review to wrongly assert that water treatment at the project will be required into perpetuity.

Water treatment plan in place

While it is true that long term water treatment will be needed, a plan is in place for how that will be accomplished and financial assurances will be in place to guarantee taxpayers don’t foot the bill. Importantly, state law requires those plans and financial assurances before PolyMet can begin construction.

Other aspects of the water treatment issue:

We have the technology today that allows us to meet water quality standards long into the future. For example, we have already treated about three million gallons of water successfully through our reverse osmosis (RO) pilot water treatment plant, demonstrating that water with elevated sulfate levels can be treated to meet Minnesota’s 10 ppm sulfate standard for waters used for the production of wild rice.
We have the benefit with today’s technology and expertise of knowing what protections must be in place before mining even starts to ensure water safety and regulatory compliance over the long run. This is not an advantage that prior generations of mining companies or mining communities enjoyed
We will be responsible for financing all water treatment even post closure. Minnesota law requires a funding mechanism such as a bond to ensure that these plans – and additional plans if necessary — can be fully executed so that the financial responsibility and obligation for ensuring a clean site remains ours. These anticipated costs are already factored into our project costs.
The final amount of financial assurance is ultimately determined by the Minnesota Department of Natural Resources (DNR) as part of the Permit to Mine (not the EIS, as some believe), which will detail the specifics of operations and closure.
Modeling today indicates that treatment will be needed into the future whether we mine or not because of the legacy issues. This is not uncommon for many mining and industrial complexes.
In a “worst case” scenario post closure, the volume of water needing treatment is estimated at about 2000 gallons per minute at the Erie Plant Site (a flow volume of about a 10-inch pipe) and about 300 gpm (flow of about a four-inch pipe) at the mine site.
During operation and initially after closure, the project will actively clean water with two water treatment plants. Water discharged to the environment will be treated with active treatment (RO) until passive water treatment systems are proven and shown with real-time monitoring data that they can meet the protective state and federal water quality standards.
Reverse Osmosis treatment is proven technology that’s widely used including in community drinking water supplies, water bottling operations, the pharmaceutical industry and mining.
The Flambeau Mine in Wisconsin, which finished mining in 1997 and reclamation in 1999, is an excellent example of effective post-mining long-term water management. It is in close proximity to the Flambeau River and has been in full compliance with Wisconsin laws that require monitoring and water quality management throughout its history. Minnesota laws are consistent with those of neighboring states where modern mining is taking place.