Keeping the Waste in Place

Over 600 acres of contaminated land left behind by historic mining and smelting practices has been reclaimed within Butte’s urban Superfund area since the 1980s. To put that number into a more common perspective, a football field is 1.32 acres. That means roughly 600 Naranche Stadiums worth of historic mine waste has been capped in Butte. This reclaimed area total will increase by more than 100 acres once the final cleanup plan for Butte is approved, likely to be later this summer. That’s a lot of ground to cover, both figuratively and literally. 

Reclamation at one of our historic mining sites generally involves smoothing out the surface to gentler slopes (3 horizontal: 1 vertical or less); placing two inches of limestone gravel on top of the acidic wastes at the surface; and then, covering that rock layer with up to two feet of clean cover soil. Depending on how much organic content is in the soil, manure or compost is added to increase the soil’s ability to hold nutrients and water. Once all of this is done, the newly placed “cap,” as it’s referred to in Superfund language, is fertilized and seeded with native plants. 

 

Over the 30-plus years we’ve been capping mine waste sites in Butte, a lot of improvements have come along. Many factors are considered when engineering these caps, from soil texture requirements, to minimum cap thicknesses, to the types of plants in the seed mixes and what times of year you can seed them. Then comes the most important part – taking care of them. Forever.

In fact, one of the biggest advancements was the development of the Butte Reclamation Evaluation System or BRES, (I always pronounced it “Breeze”) back in the early 2000s. The BRES is a tool that trained evaluators use to monitor all of our reclaimed areas to make sure the caps and the waste they hold beneath them are staying in place. The BRES has been continuously refined since its development and is now administered by the Clark Fork Watershed Education Program (CFWEP visit them at http://cfwep.org ), in cooperation with Butte-Silver Bow and EPA. Further, Montana Tech’s Restoration Ecology program is also involved, adding additional details to the evaluation that weren’t there before.

How does the BRES work?

Every year, roughly 20% of all Butte’s reclaimed areas are evaluated using the BRES. This ensures that all 600-plus acres of reclaimed areas are evaluated at least every five years. The BRES field evaluation looks at plant cover and species, erosion, weeds, exposed mine waste, subsidence, among other things.  

Perhaps the best part of the BRES is CFWEP’s role as an objective, third-party evaluator. CFWEP has been working with the BRES for the past decade. Each year, it trains new Montana Tech students to help carry out the annual field evaluations, which take place during June and/or July. 

“We are independent from the county (BSB), EPA and ARCO,” pointed out CFWEP Director Rayelynn Brandl. “Our job is to be totally unbiased in what has or has not been done (maintenance-wise) and evaluate the conditions of the caps at the time we are out.”   

How’s that for citizen science and public participation?

More important, any issues that are identified during the BRES evaluation are reported to and addressed by BSB’s Superfund Operations and Maintenance Program. Even better – all of the data collected during every BRES evaluation is put into a database that tracks the reclamation, evaluation and maintenance history of every site that’s part of the BPSOU.

Over time, it’s encouraging how much Butte’s Superfund reclamation programs and practices have evolved and improved. The rudimentary “waste in place” actions of the 1980s, which drew little public support and much concern can now be considered best-in-practice for mine reclamation and should leave the public with much less to worry about. Simply put, in 2019 reclamation in Butte has become a “breeze.”

PHOTO CUTLINE: The Travona Mineyard is one of the oldest reclaimed caps in the Butte Priority Soils Operable Unit (BPSOU). Thanks to the Butte Reclamation Evaluation System (BRES), the cap at the Travona is still keeping our community and environment safe from the mining wastes it has contained beneath for the past 30 years. Trained evaluators regularly inspect the site to make sure the soil cap is stable and not eroding, and that the plant communities are healthy.