Abandoned coal mines in Pennsylvania may be a technically viable source of water for hydraulic fracturing (fracking) operations, but economics and regulations ultimately could decide whether operators find the solution feasible, according to a recent report by the Rand Corp.

In hundreds of old coal mines in the state, underground water may seep into seams, gather chemicals and potentially pollute reservoirs or streams. Because some of these mines often are near shale operations requiring water supplies, drillers long have considered using coal mine water (CMW) for operations, but many have been hesitant because of technical and regulatory concerns.

Although not a major water user by industrial standards, a typical Marcellus Shale well may require between 3.9 million and 5.6 million gallons of water for completion activities, and the industry is eager to reduce its fresh water consumption for economic and environmental reasons.

“The process of using mine water is just one more way that our industry is working to preserve water resources, reduce transportation and logistical burdens and even more closely connect the economic and environmental benefits of American natural gas development,” Marcellus Shale Coalition (MSC) President Kathryn Klaber said. “Members of our coalition look forward to working with all stakeholders — from industry and environmental groups to academics and government officials — on policy initiatives that advance the use of this technology in a safe and sustainable manner.”

The Rand report, funded by the MSC, grew out of a day-long conference last December where representatives from industry, government and academia met to discuss the opportunities and challenges for using CMW, also known as Acid Mine Drainage (AMD). They found that the challenges aren’t technical. The amount of available CMW in Pennsylvania likely exceeds the amount of water required for fracking operations over the coming decade “by a large margin,” but the chemical composition and the location of each source will determine viability on a case by case basis. The composition is crucial because improper chemistry may damage shale formations and reduce productivity.

In experiments during the early days of Barnett Shale development in Texas, operators found that calcium caused scaling, bacteria caused corrosion and iron could plug wells. While active mines have treatment facilities on site to manage chemicals, and operators can alter the chemical composition of CMW, the report recommended additional research to better specific sources.

Additionally, because trucking is often the largest cost component for water sourcing, fresh water sources may continue to be the cheapest option for certain drilling operations. However, the bigger concern among Pennsylvania operators is regulatory — specifically, companies are concerned that using CMW could create liability problems under the Pennsylvania Clean Stream Law.

The Pennsylvania Department of Environmental Protection released a draft white paper at the December meeting suggesting ways to alleviate those concerns (see Shale Daily, Jan. 30), but the report warned that tinkering could have unintended consequences for other environmental issues. The report also concluded that while shale development could help alleviate the AMD problem in Pennsylvania, it couldn’t solve it entirely, even at full capacity, and therefore policymakers needed to continue to study broader watershed quality issues across the state.