Wyoming's oil and natural gas commission approved a plan Tuesday to dispose of wastewater into an aquifer used in some parts of the state for drinking water, overruling no votes from the two geologists on the commission.
The Wyoming Oil and Gas Conservation Commission approved an Encana Oil and Gas request for permission to inject water produced from the company's operations into the Madison formation at a rate around 25,000 barrels -- or about 750,000 gallons -- per day for 50 years. The well would serve existing operations in a small field about 60 miles west of Casper.
The commission, which includes Gov. Matt Mead, voted to approve the plan after a lengthy discussion about the proposal at a Tuesday hearing in Casper. The commission approved the plan largely on the grounds that it would be too expensive to pump and treat water from the 15,000 foot-deep aquifer.
Two commissioners -- State Geologist Tom Drean and the recently-appointed Mark Doelger, also a geologist -- voted against the plan.
Drean, who as state geologist oversees geological data about Wyoming, told representatives of the company that he had concerns about company modeling used to project the well's effect on the water-bearing formation.
He told the company that he thought its modeling didn't put enough weight on the possibility that the formation is more porous than Encana believes and exists in varying thicknesses. Both factors could mean the company's projected 4.5-mile wide impact zone around the well is too narrow.
"I am in no way faulting the work that Encana has done," he said late in the hearing. "What I do have questions about is, when they're representing the 4.5-mile impact area, I don't think that's accurate."
Encana first proposed drilling the well, used to dispose of water produced in the oil and gas drilling and production process, in late 2011. The commission initially approved the plan in 2012, contingent on water in the formation hosting a measure of total dissolved solids -- a metric of suspended organic and inorganic matter used to gauge quality -- greater than 5,000 milligrams per liter. The U.S. Environmental Protection Agency recommends drinking only water with a TDS below 500.
Company testing showed the water had a TDS content nearer to 1,000, so the approval wasn't granted.
Encana then resubmitted its proposal. It said because the water is deep and far from civilization, it would be economically and technologically impractical to drill into the formation for drinking water. It would cost about $20 million to purify the water for drinking, according to company estimates.
The commission initially approved the request in January and asked for input from the Wyoming Department of Environmental Quality and EPA. The DEQ originally objected to the plan, but backed off the objection after Encana answered a series of concerns raised in February.
The EPA first submitted a series of questions without a judgment, and is now reviewing the matter and is expected to comment soon.
The plan drew opposition from the Powder River Basin Resource Council, a landowner group based in Wyoming. The council opposed the plan in a formal letter to the commission.
"We are increasingly concerned about future sources of drinking water in Wyoming and in the Wind River and Big Horn Basin," wrote John Fenton, the council's chair. "We believe that a decision to allow a potential drinking water aquifer to be exempted and removed from the potential for future use would be shortsighted."
Commissioner Bruce Williams questioned on Tuesday why the size of the impact zone was significant. Company projections showed that the well would have only a minor effect on water quality on the outskirts of the area affected by injection.
"I agree that the (impacted) area could be larger," he said. "My question is, 'So what?'"