Study: Treated water may have impact
Releasing millions of gallons of treated water from hydraulic fracturing wastewater into area surface waters may have had a longer-lasting impact than originally thought, according to a study.
Penn State researchers have revealed that many of the pollutants remained intact after wastewater was treated at facilities.
The study, published in a recent issue of Environmental Science and Technology, considered sediment samples collected from a reservoir in western Pennsylvania.
“There wasn’t a water keeper who was sitting in these rivers collecting these samples at a great continuous clip, so in a way, a lot of information just flowed by,” said Penn State environmental professor Bill Burgos, who along with his colleagues conducted the research.
“But in certain reservoirs, where sediments collect over time, there are layers of sediment that are like rings of a tree; you can look into the sediments and capture time and spatially composite samples.”
The study considered sediments that built up over time to reconstruct the oil and gas activity occurring during the boom days of Marcellus Shale drilling from roughly 2008 to 2015.
“You need a lake or reservoir that allows sediments to lay down undisturbed in those layers,” Burgos said. “The (term) we use is a ‘coherent temporal record.’ You only get a coherent temporal record if it’s a lake that continuously accumulates sediments and isn’t subject to a flood or scour.”
The research noted that large quantities of oil and gas wastewater with high loads of chloride, barium, strontium, radium and organic compounds left high concentrations in the sediments and pore water.
The organic contaminants, nonylphenol ethoxylates and polycyclic aromatic hydrocarbons (carcinogens) were found with the highest concentrations in sediment layers deposited five to 10 years ago during the peak of Marcellus Shale activity.
It was noted that while the findings show long-term contamination of watersheds, the effects on the environment and human health are still unknown and difficult to assess.
A significant drop in the amount of contaminants into surface waters occurred following the voluntary ban on discharge of Marcellus waste requested by the state Department of Environmental Protection beginning in 2011, according to researchers.
Nathaniel Warner, assistant professor of Environmental Engineering at Penn State and co-author of the study, said it’s clear that the discharge of oil and gas waste does impact water quality and sediment quality on a larger scale than previously believed.
He added that among the findings of the research are:
* Tools with multiple lines of evidence are available to demonstrate how oil and gas waste impacted the sediments.
* The voluntary ban on discharge of Marcellus waste had a positive impact on water quality.
* Impact to ecosystem services or health has yet to be determined.
* Sampling is being done farther downstream to determine the total length of the impact.
Marcellus Shale Coalition President David Spigelmyer released the following statement regarding the research: “As an industry committed to protecting and enhancing our environment, we voluntarily committed a full six years ago to stop sending wastewater from shale gas operations to publicly owned treatment facilities because it’s the right thing to do.
“We’re proud of the fact that wastewater recycling was pioneered in the Commonwealth and 90 percent of all water used in Marcellus operations is recycled today.”