By Dan Mueller, Director, Natural Gas Exploration and Production - Environmental Defense Fund
Each year, the oil and gas industry produces more than 800 billion gallons of wastewater. Coupling the massive volumes of wastewater generated over the life of the well and the millions of gallons of water needed to hydraulically fracture each well, it’s easy to see that oil and gas exploration and production is just as much a water issue as it is an energy issue.
With growing frequency, this huge volume of oil and gas wastewater – which contains hundreds of chemicals resulting from operations as well as underground water that is usually heavily laden with salt and naturally-occurring pollutants – is being recycled, and some groups are pushing for mandatory recycling policies. Sounds great. After all, recycling is good for the environment, right?
On one level, it is great. In drought-stricken parts of the country, water is a scarce resource and beneficially reusing the huge volume of wastewater the oil and gas industry produces could help mitigate impacts on local water sources. In some counties in Texas, for example, over half the water demand in the county is used for oil and gas exploration and production.
But recycling this wastewater creates some environmental challenges. And if they are not proactively addressed, we run the risk of trading one environmental problem for a host of new ones.
Water Management vs. Conservation
Depending on the local geology, the process of hydraulic fracturing can use up to 15 million gallons of water in a matter of days – the same amount of water used per day by 50,000 American households.
Operators add many chemicals to this fluid to make the process more productive. Once injected deep underground into the well, naturally salty water trapped inside the rock mixes with the chemical-laced fluid and then much of this mixture flows back to the surface.
Recent studies indicate that approximately 70 percent of 400 examined cases of groundwater contamination from oil and gas operations were caused by surface releases – accidents that happened once the wastewater returned to the surface, essentially spills. Increasing reuse and recycling threatens to exacerbate this problem because these processes require increased management and handling of contaminated water at the surface.
A recent Associated Press report highlighted some troublesome numbers. It reported that more than 180 million gallons of oil and gas wastewater spilled from 2009 to 2014 and the source of the spills included ruptured pipes, overflowing storage tanks and deliberate dumping. The report also noted many spills go unreported, meaning actual volumes are surely higher. And the oily content of the wastewater is not the only problem that must be addressed when a spill occurs. The high salt content of the wastewater is more difficult to clean up, and can damage habitat and cropland for decades afterward.
More Storage + More Transportation = More opportunity for recycling mishaps
Wastewater has to be stored in pits and tanks at well sites and central storage facilities, and with recycling it is happening a lot more and for a whole lot longer. That’s because the opportunities to reuse the wastewater often don’t occur immediately. Storage alone doesn’t mean wastewater will spill and cause contamination, but the more drilling companies hold on to this wastewater, the higher risks for spills.
Further, recycling operations also significantly increase transportation requirements, since the wastewater must be moved from where itis generated to treatment facilities, to interim storage, to points of use. Whether the wastewater is moved by truck, pipeline, rail, etc… increased transportation also means more opportunity for accidents and spills.
To avoid this, we need stronger requirements to make sure that tanks, open pits, and pipelines are properly engineered, constructed and managed and other water management operations are conducted to minimize spills. It is also important to rapidly identify and cleanup spills when they do occur. These sorts of requirements have existed for other industry sectors that manage toxic materials for decades.
Wastewater treatment is another possible pollution vector. Oil and gas wastewater contains a varied mixture of: salt and suspended solids in high concentrations; metals, including arsenic and barium; organics like hydrocarbon compounds; and potentially naturally-occurring radioactive material. Important to determining the risks of all constituents is their toxicity, how they move if released into the environment, how long they stay in the environment, and whether they bioaccumulate in the food chain.
Treatment is not a one-size-fits-all challenge. Some “light-treatment” technologies are readily available. More robust treatment technologies have limited real-world track records when treating this highly variable wastewater and when deployed properly are very expensive to construct, operate and maintain. And there are limited accepted standards regarding how to identify what is in each waste stream and how to adequately “clean” it.
What Do We Do With the Waste?
There’s a long list of toxic constituents that can be present in this wastewater, and with successful treatment, the sludge and solids left over can contain very high concentrations of them. The volume and makeup of these waste streams vary and require a variety of handling and disposal guidelines. It’s vital that we understand and address the environmental impact of the wastes produced from recycling when weighing its overall costs and benefits.
Recycling wastewater is a good idea. But it’s not as simple as dropping your bottles and cans in a blue bin. As is the case with the entire oil and gas industry, responsible practices and smart regulations need to make sure we do it right. Industry must use proven engineering practices to identify and minimize spills, and rapidly cleanup spills when they do occur. And we must continue to advance the science on what is in this wastewater, how toxic it is, and what technologies are required to properly treat it. And, during all of this, we must recognize what we know, what we don’t know, and work to fill the knowledge gaps. Otherwise, we’ll just be trading one problem for another.
From Environmental Defense Fund's Energy Exchange Blog.
Image credit: "DSCN3234," WildEarth Guardians © 2014, used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by/2.0/