Perpetual Treatment of Mines

“Once acid drainage starts it’s impossible to stop. So maybe we should look at the beginning, and say if you are going to have to treat forever you don’t have a mine, you have an interesting ore body, but not a mine.” Dr. Glenn Miller, Professor Emeritus of Environmental Science University of Nevada Reno


Mining has dug a deep history in Nevada, and is now digging a deeper, more reactive story. Images honoring the hardworking miner with a pickaxe can be found throughout the state, but the mining boom that has occurred over the last 50 years was not carried out with pickaxes. Modern industrial mining methods such as pit-mining and heap leaching for microscopic minerals are taking the impacts of mining to levels unimaginable to the archetypical pickaxe miner of yesteryear. New technology and environmental awareness has also brought improved cleanup strategies and regulations. despite these improvements, the impacts of some mines in Nevada will be indefinite.


There are already two mines that will have to treat water forever. Experts believe that there are several other mines that will require for treatment in perpetuity.The Phoenix mine near Battle Mountain is proposing a strategy of treatment practically forever, and is expanding. The Rain mine near Elko is in closure, and will likely generate acid forever. Treating water is needed so that our land and water are not polluted. Mines that will have perpetual care will be changing clean water into polluted water forever, should this be allowed? Mining currently uses 45% of the water in the upper Humboldt river basin according to a recent Desert Research Institute Study, and perpetual pollution will continue to impact water long after the benefits of mining have gone.


When we start talking about this in terms of forever, we have to wonder if the company or other institutions will be there to follow through in 500 years, and what kind of society will be there to ensure it. Perpetual treatment presents a long term economic risk to the state, for taxpayers are likely to pick up the bill for companies which fail to achieve indefinite success. Things get a little fuzzy when we start using words like indefinite, perpetuity, and forever, so this post aims to provide some clarity.


What is perpetual treatment from acid mine runoff?
The Bureau of Land Management defines perpetual treatment as treatment lasting for more than 500 years.
In practical terms perpetual treatment is a situation which arises when:

  1. Reactive material, (often sulfides that are dug up along with the ore), that was buried for thousand of years is brought to the surface.
  2. The material reacts to form acids in the moisture which runs off or pools from mines.
  3. Then acids dissolve heavy metals as well as other contaminants into the water compounding the problem.
  4. This forms a circular chain reaction in which the acids result in more acids and contaminants. Long story short, the process lasts forever and can’t be turned off.


Even the mines of the Romans created acid mine runoff which persists through today; the difference between those mines, and what we are seeing now is scale. The open-pit mines that are being built in Nevada are massive. For example, the Pipeline pit in Crescent Valley will be deeper than lake Tahoe when it fills with water. This size results in perpetual acid runoff that is a serious draw on the limited supply of water in Nevada, and presents catastrophic risk should treatment ever fail.


Mining companies propose to treat water forever by pumping water, treating it in a facility, and then pumping it back, so they can comply with federal and state water quality standards. This takes the water from other uses, and the water that is returned may not be toxic, but it will never be the same quality as it was before treatment.


Running water treatment facilities forever requires an incalculable amount of money, so there is no way that the risk outweighs the benefit. Moreover, there is no likelihood that companies which propose perpetual treatment will last the thousands of years it takes to follow through.


What is pit-ming?


Most of the easy deposits of gold in Nevada have already been mined, so attention has turned to microscopic gold. Pit mining allows for processing huge amounts of earth to access these microscopic minerals. Material is removed from the earth, and a large hole is created. Often, the ore is below the groundwater level, so pumps are installed to keep the pit dry. Once the material is removed, it is crushed up and then processed with chemicals to remove the desired minerals. After mining, there is no requirement to fill the pit, and dewatering pumps are turned off. so what is called a pit-lake forms as the water level re-stabilizes.


What is heap-leaching and tailings?


Heap leaching is a chemical process which separates the desired mineral from the ore that has been removed from a mine. The material is soaked with chemicals called leaching agents. The minerals stick to the leaching agents creating what is called a pregnant solutions. The pregnant solution drains to the bottom of the heap pile, and is captured by the mining company.


Tailings are the end result. Once it is no longer profitable to leach minerals from the ore, the material becomes tailings. This is essentially waste rock which is stored on site, though it can still have the potential to contaminate.


What is acid mine drainage?


Acid mine drainage occurs at heaps, tailings, and pits. This is the result of a chemical reaction between earth that has been brought to the surface, air, and water. Acid mine drainage is a key component of perpetual treatment sites. The acid dissolves other minerals in rock it comes in contact with. The end result is a toxic stew of heavy metals and acid either leaking out from a tailings/heap pile, or pooling in a pit-lake.


What is being done to help?


We are just know coming to understand the magnitude of impacts that results from new mining practices which have been developed over the last fifty years. Many states are acting on the knowledge that large scale acid mine drainage can’t be stopped. Maine and New Mexico have created regulation preventing the creation of perpetuity sites, and there are efforts to do so in Montana and Colorado. Great Basin Resource Watch and the Progressive Leadership Alliance of Nevada are working to pass similar common sense legislation in Nevada. Education on the issue is a concern, for even though Nevada is one of the main global mining regions the impacts are seen as distant in Nevadas urban centers. That is why we are working to inform the public of emerging impacts from modern industrial mining. Public engagement on this issue is needed to allow our policy makers to support legislation which contributes to a healthy sustainable mining industry.


You can help by discussing this issue with other community members, and by contacting your representative to let them know you think water is important to life.


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