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Technical and long-term questions remain about Encana’s aquifer exemption request


The Wyoming Oil and Gas Conservation Commission recently okayed an aquifer exemption that would permit Encana Oil and Gas to pump waste water from their oil and gas projects in the Moneta Divide into the Madison Aquifer, about 60 miles outside of Casper. Wyoming Public Radio’s Irina Zhorov reports that the exemption isn’t exactly a rarity, but it does bring up some big questions.

IRINA ZHOROV: Encana says it needs to dispose of produced water into the Madison aquifer in order to grow its operations in the Moneta Divide oil and gas field. Encana first proposed the injection well in 2011. The Wyoming Oil and Gas Conservation Commission gave the project the go-ahead then, as long as Encana could show that the water quality in the Madison at the pump site contained more than 5,000 milligrams per liter of total dissolved solids, or TDS. In other words, they okayed it contingent on the water being of pretty poor quality. But Encana came back after sampling and said the water is actually of pretty good quality. That surprised everyone, including Encana. So Encana’s lawyer, Walter Eggers, says instead of basing their request on water quality, they’re basing their request on the fact that it’s too hard to get to for public consumption.

Speaking at the Commission’s public hearing in March, he explained that there are different criteria for granting an exemption. He admits that this one is rare.

WALTER EGGERS:…if the aquifer is situated at a depth or location which makes recovery of fresh and potable water economically or technologically impractical…and that’s Chapter 4…section 12….

ZHOROV: The proposed injection well is 15,000 feet deep. Water wells are usually much shallower than that. It’s expensive to drill that deep, and Encana’s Paul Ulrich says no one ever will.

PAUL ULRICH: We took a look at many other potential sources of water that could be used, at shallower depths and at much shallower depths and out analysis demonstrated to us and clearly to the Commission that there are many other sources that would be used for many many many years, for 50, 100 years, instead of drilling a 15,000 foot, 10 million dollar well.

ZHOROV: So what Ulrich is saying is that water managers will have other sources to pick from before they would ever turn to this section of the Madison aquifer.

The Commission agreed with Encana. And the Department of Environmental Quality - which initially expressed concerns about the exemption - withdrew them. But some questions remain. The state geologist, Tom Drean, who sits on the Commission, voted against the project.

TOM DREAN: It boiled down to me that in the modeling they really took too simplistic of a geologic view. That they were treating the Madison formation as one ubiquitous or similar rock body throughout the whole 300 foot thickness. When in reality we know from a geologic point of view that that’s not accurate.  

ZHOROV: The Environmental Protection Agency is with Drean. They sent a letter to the Commission after they approved the project saying Encana’s model is “very general” and recommended that the model be modified to actually reflect the geology in the area. It matters because the aquifer slopes up from the injection well, getting shallower, and eventually hits the surface. Encana says they’ll affect a 4.5 mile area around the well. Drean says that might not be accurate.

DREAN: If their model is incorrect and if they are affecting a bigger area and if you look at the dips of the beds, of the rock formation as it comes out of the basin, if it begins to affect a significantly larger area than that well all of a sudden it comes up to shallower depths. And then as it comes up to shallower depths, well, all of a sudden you're getting closer and closer and closer to what might be economically viable or a useful water resource for the public.   

ZHOROV: The other question is a bit broader. Should we be taking relatively fresh water sources off the table just because they’re not viable now?

The American Water Works Association is a nonprofit focused on improving water quality and supply. The Association’s Alan Roberson says Encana is probably right about this well not being practical as a fresh water source…

ALAN ROBERSON: But I think it’s a question where the science is evolving, that we’re not really sure how far out to go. The question, or I would say the science, is evolving right now.

ZHOROV: For one, Roberson says that perhaps 100 years, the timeframe Encana’s model uses, isn’t actually that long when planning for water needs. But also, Roberson says already people are drilling deeper and transporting water for longer distances than they had previously done.

ROBERSON: People are going further away. The easier sources have already been used.

ZHOROV: And it should be noted that the number of aquifer exemption requests is growing along with the energy industry’s activity. That includes oil, gas, and uranium. In 2011 and 2012, the EPA permitted 73 aquifer exemptions in Wyoming alone.   

Powder River Basin Resource Council’s Jill Morrison says that’s a troubling trend, especially if aquifers of relatively fresh water are going to be part of that development.

JILL MORRISON: The concerns are more long-term for future water use and the fact that we’re potentially eliminating an aquifer from future water use and setting up that precedent.

ZHOROV: Wyoming currently relies on groundwater for nearly 40% of its water needs.

Indeed, the very same Madison Aquifer is used for drinking water in other parts of the state and country.

Drean, the geologist, says he’s for energy development in the state and might have voted for the exemption had Encana’s model been better, but he does say that predicting what will be viable in the future is hard.

DREAN: The one thing I think we do know, when it comes to water resources, is that they’ve always been precious in states like Wyoming and I think as time goes by fresh water and drinking water is going to become more and more previous around the world. 

Encana is still formulating its response to EPA’s questions and cannot use their well until the EPA signs off on the project. The well would only be used to dispose of produced water from the 280 currently operating production wells. But the project is just beginning; Encana is proposing to drill over 4,000 wells in the Moneta Divide Project. For Wyoming Public Radio, I’m Irina Zhorov.

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