Encana plan for injecting 750,000 gallons of oil and gas production waste a day for 50 years into aa Wyoming aquifer faces EPA scrutiny

Encana plan for Wyoming aquifer wastewater well faces EPA scrutiny by Adam Voge, April 11, 2013, Star-Tribune
The U.S. Environmental Protection Agency wants a company asking to inject oil and gas well wastewater into an aquifer in central Wyoming to do more to prove it won’t pollute the aquifer and show it won’t be used for drinking water. The EPA’s demands mirror concerns about the project from the state’s environmental agency and some oil and gas industry regulators. The Wyoming Oil and Gas Conservation Commission overruled some of its members — both geologists — last month in approving the Encana Oil and Gas injection well. Encana wants to inject about 25,000 barrels a day of wastewater from oil and gas wells into the Madison geologic formation west of Casper. The EPA, which could nix the plan, said it wants the company to add to its modeling of the well’s effect on the aquifer.

Encana had claimed the aquifer’s water — about 15,000 feet below ground in that location — was too expensive to treat and transport to nearby communities as drinking water, a claim questioned by the agency. The Encana official who manages the project said Wednesday he hadn’t seen the EPA requests, but added his company will provide whatever information it can to clarify its plans. “We are looking forward to reviewing their comments and meeting with the EPA very soon,” Paul Ulrich, company project manager, said. “We’re very confident with our application.”

The company has proposed to drill a wastewater injection well into the Madison formation — which lies beneath much of the state — in a field about 60 miles west of Casper. The well would be used to service existing oil and gas production wells for 50 years at a rate of about 750,000 gallons per day. … A different part of the same formation supplies water to Gillette residents. While the state commission ultimately voted to approve the company’s request in early March, at least two commissioners took issue with the plan for different reasons. State Geologist Tom Drean and Mark Doelger, also a geologist, voted against the proposal because of concerns about Encana’s modeling. Both said they didn’t know whether the company’s model correctly accounted for varying rock thicknesses and porosity in the formation, both of which could affect how far injected wastewater spreads. The EPA’s request to amend the company model backs those concerns. The agency called Encana’s data “very general” and asked that models be altered with more specific information.

The agency also wants to know how the injection permit could be used in future development of the project, which is slated to eventually include 4,200 wells. The injection plan, as approved, would only apply to about 280 existing wells in the area. Ulrich said the company is keeping its wastewater disposal options open for the larger Moneta Divide project. “Our long-term water management plan has lots of options,” he said. “We want to keep the current door open for a robust treatment program in producing clean water, the use of evaporation pits and the use of injection in general.” [Emphasis added]

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