Oilfield filter socks, used to filter wastewater at drilling sites, have turned up in some odd corners of North Dakota, including a roadside, an Indian Reservation, a city garbage can, and tucked under other waste trucked to landfills.
The socks often contain naturally occurring radioactive materials—radium is the usual suspect—and may be dumped to avoid more costly disposal at radioactive waste depositories out of state.
“Unfortunately, if the only disposal options are out of state, I think that creates a bad environment for people to try to sneak bags of it into landfills,” John Harju of the Energy and Environmental Research Center at the University of North Dakota told the Jamestown Sun. “People don’t know what to do with it.”
Hydraulic fracturing and lateral drilling have spurred an oil boom in western North Dakota so rapid that the region has struggled to house and feed the influx of workers, according to the North Dakota Health Department. Monthly oil production in the state has increased from about 3 million barrels per month in 2008 to 25 million, according to the state's Department of Mineral Resources.
Some of the water injected into deep shale formations during hydraulic fracturing returns to the surface as "flowback water."
"Flowback will contain the chemical additives used during hydraulic fracturing; thus, flowback is an industrial wastewater that requires proper treatment and/or disposal," according to Cornell University's Water Resources Institute. "In addition to chemical additives, flowback water will also contain chemical constituents associated with the shale," which may include high levels of salt, metals, organic compounds, and naturally occuring radioactive materials (NORM).
Filter socks are used to capture the solids in flowback water.
North Dakota prohibits disposal of waste that emits more than 5 picocuries per gram of radiation. Filter socks tested by a Williston, ND landfill operator were found to emit up to 47 pico curies per gram, the Sun reported.
The U.S. Environmental Protection Agency considers NORM a hazard mostly to workers at the site:
"They may inhale radon gas which is released during drilling and produced by the decay of radium, raising their risk of lung cancer. In addition, they are exposed to alpha and gamma radiation released during the decay of radium-226 and the low-energy gamma radiation and beta particles released by the decay of radium-228, according to EPA. "Gamma radiation can also penetrate the skin and raise the risk of cancer."
But North Dakota considers NORM a hazard to the public as well. The state distributes a flyer to oilfield waste haulers that recommends appropriate locations for the disposal of oilfield wastes. The only ones listed that accept radioactive waste are in Colorado, Texas, and South Dakota.
Like North Dakota, Pennsylvania has experienced a drilling boom spurred by fracking. Pennsylvania prides itself as "the only state that by regulation requires radiation detection at landfills" and has launched a study into the impact of naturally occurring radioactive materials.
Filter socks have not posed a disposal problem in Pennsylvania, according to a spokesman from Pennsylvania's Department of Environmental Protection.
"We have not seen problems with filter socks being disposed of illegally," said Kevin Sunday, DEP's deputy press secretary. "On rare occasion, there have been illegal discharges of wastewater and we have worked with the state Attorney General’s Office to prosecute those crimes."
Pennsylvania also has a conservative limit on radiation at landfills and waste that exceeds the limit is likewise sent out of state.
"Filter socks and other wastes from the oil and gas industry, such as drill cuttings or wastewater sludges, can be disposed of at municipal and residual waste landfills – unless the levels of naturally occurring radioactivity in the waste exceed the very conservative protocol we have in place at these landfills," Sunday said. "In those cases, the wastes are shipped to low level radioactive waste disposal sites in places like Texas, Idaho, and Utah."
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