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Bagasse to the Rescue!

2014 August 27

By Kristine Edwards

When I first visited the Crystal Mine site (part of the Basin Mining Area Superfund Site in Jefferson County, Montana) back in 2006, I was so shocked by how bad it looked that I vowed to myself to get it cleaned up before I retired.

Acid mine drainage from old mines is a big problem in historic mining districts across the U.S. The pH of mine water at the Crystal Mine is around 2.7, which is pretty acidic (on a scale of 1-14, with 7 being neutral pH and what we like to see in uncontaminated water), and carries significant concentrations of heavy metals. In order to treat the drainage, we’re working with our contractor on a treatment system.

An environmental contractor was working on mine sites in Peru when they came across a locally grown material that showed a lot of promise for treating acid mine drainage. It’s called sugar cane bagasse, a byproduct of sugar cane. The bagasse is a light weight fibrous material. Additional research at the University of Colorado (Boulder) using sugar cane bagasse showed promise even at low pH levels and low temperatures. Since the Crystal Mine site is at 8,000 ft elevation, it can get very cold there in the winter.

 

Sugar cane bagasse sample

Sugar cane bagasse sample

 

The bagasse is permeable and promotes biological activity by sulfate-reducing bacteria. This converts sulfate in the drainage to sulfide. Dissolved heavy metals like cadmium, copper, iron, lead, nickel, zinc combine with these sulfides to adhere to the fibers, leaving the water much cleaner.

We’re running a treatability study at the Crystal Mine to see if the sugar cane bagasse works better at treating the drainage from this site than the typical methods. The manure and hay, a step in the process, are coming from a nearby barn and the aged wood chips and saw dust are from a local post and pole operation. So, even though the sugar cane bagasse is coming from Louisiana, we’ll be using some local materials as well.

This will be a test that, if successful, could simplify treatment of acid mine drainage at other remote mine sites in this region. It would also lower maintenance costs, if it works the way we hope it will. The study will run from mid-June to October, and then it will take us about a month to interpret the results.

I hope to have a make a decision on how to clean up the site and the design plan in place by June 2015. The Superfund cleanup process can be long and it’s taken several years to complete the investigation of the site. This treatability study with the sugar cane bagasse will help us design the final treatment system and could be something EPA or the state could use at other mine sites with acid mine drainage. I could then retire with a feeling of having accomplished my goal of cleaning up this site, and perhaps help clean up other sites as well!

 

Kristine Edwards at the Crystal Mine Adit Portal

Kristine Edwards at the Crystal Mine Adit Portal

About the author: Kristine Edwards, a “native” Montanan, has always loved hiking, fishing, horseback riding and backpacking in the mountains of Montana. She was hired by EPA out in Seattle (EPA Region 10), and was fortunate to eventually make it back to Montana after 4 years in Seattle and 3 years in Denver.

 

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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4 Responses leave one →
  1. Ferdinand Quinones, PE, Hydrologist permalink
    August 31, 2014

    I am curious as to how it is planned to dispose of the contaminated bagasse. I think this is just shifting the contaminants from one media to the other. There are no easy solutions to mining contamination, and the practical option, albeit expensive, is to build a treatment plant to remove the contaminants from the collected tails and drainage.

  2. Diseño web Barcelona permalink
    September 3, 2014

    There might not be an easy way to clean the mine, but its worth it to keep the work to do something better!
    thank you for your work

    From Barcelona

  3. Taufiq Rahman permalink
    September 4, 2014

    Thanks Admin for share :D

  4. Kristine Edwards permalink
    September 10, 2014

    Good questions! You’re right that there are no easy solutions, but the bagasse accomplishes two things immediately: it removes heavy metals from the water and it greatly reduces the acidity of the water, thereby protecting the watershed downstream of the mine. The bagasse and sludge is removed periodically and placed in the local Luttrell repository, a mine waste repository constructed between the Tenmile NPL site, and the Basin NPL site.

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