A report issued by the RAND Corporation finds that using abandoned mine drainage for hydraulic fracturing gas wells could be employed more frequently in future development, thereby lessening the burden on fresh water supplies. The report, funded by the Marcellus Shale Coalition, concludes that drainage from closed mines is plentiful, and the technology to use it is feasible.
"This is water that is actually harmful for the environment, it's flowing into streams. Instead of using fresh water that's perfectly good, you take the coal mine drainage and use that instead for the process of hydraulic fracturing," said Aimee Curtright, a physical scientist with RAND and lead author of the report.
It was previously thought that water used for fracking had to be as pure as possible, but increasingly, developers are using lower grades of water. Curtright said mine waste water may be more readily available to drillers.
"A lot of these mine sites are close to drilling areas, so you don't have to move water very far in order to use it, so that's another piece of the technical puzzle," she said.
All Water is not Equal
But there is a lot of variability in the properties of the mine drainage. Some of it is acidic, some isn't; different bodies have different levels of minerals dissolved in them; some of the water can be used with little or no treatment, while some may require lots of treatment.
Plus, there are some regulatory concerns on the part of drillers, namely, whether or not they'll be held responsible for the waste water from closed or abandoned mines.
"The Pennsylvania Department of Environmental Protection is actually in the process of figuring out how to get around these regulatory hurdles without removing necessary regulation, but also enable companies to do this in a way that doesn't make them responsible for past environmental sins," said Curtright.
The main takeaway from the report, said Curtright, is that the technology exists and it may be feasible to use, but there are still many questions that need to be answered before the waste water can be used for fracking on a large scale.