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recent study shows groundwater contamination can occur when oil and gas wastewater is used on unpaved roads to suppress dust.
A total of 13 states currently allow the use of oil and gas wastewater to suppress dust on unpaved roads or to de-ice roads in cold weather. The practice is most common in rural areas where budgets for road maintenance are tight.
However, the study states the practice is not a good idea as it can lead to water and air pollution. It found the amount of radium leached from road wastewater, as compared to radium discharged from wastewater plants, was four times higher between 2008-2014. It was 200 times higher than the amount of radium leached during wastewater spills.
“Oil and gas wastewaters are known to have high salt, organic, and radioactivity concentrations,” said Travis L. Tasker, a graduate student at Penn State University and the lead author of a paper on the subject recently published in Environmental Science & Technology. “When we found out that this wastewater was being spread on roads, we wanted to evaluate its potential to cause biological toxicity and accumulate in road material or migrate into water resources.”
The wastewater studied did not come from hydraulically fractured wells. It was from conventional oil and gas wells, which are typically drilled vertically. The researchers collected wastewater from communities that use it on roads and did simulations to see where the contaminants in the water ends up.
They found salts wash off in subsequent rain, but some of the metal contaminants like lead remain on the road surface. Some of the radium stays in the road, but some of it washes off in rain events too.
“We would like to do experiments to test how effective the wastewaters are at suppressing dust in comparison to other commercial products,” adds Nathaniel R. Warner, an assistant professor at Penn State and coauthor of the paper. “If the salts in the wastewaters are just as effective, then new regulations or additional treatment prior to spreading could help reduce the concentration of other contaminants of concern that exist in wastewaters, but not in commercial products.”