During this seemingly endless winter road crews have been in a continual battle to keep streets and highways safe. Their chief weapon: saltwater. It adheres to the pavement better than bouncing rock salt and keeps ice from forming on top of it. But on some roads this salty solution may contain other potentially harmful substances.
Most state transportation departments mix this brine themselves, using either simple salt and water or natural brine extracted from underground deposits. But in states with conventional natural gas and oil drilling wells, spreading the well wastewater on roads can be a cost-saving way to de-ice. This fluid is called produced brine. Because it circulates among deep rocks and contacts various forms of petroleum, the brine can contain radium, lead or other substances that can be harmful at certain levels of exposure. State regulations of produced brine for de-icing purposes vary greatly, and some experts are calling for more rigorous testing for long-term environmental and health effects.
Conventional drilling wells extract gas and oil vertically from the ground, unlike hydraulic fracturing, or fracking, which uses vertical then horizontal drilling to inject fluid that forces oil and gas to the surface. Water, naturally salty from ancient seas buried deep beneath North America, comes out with the gas and oil in both processes. Almost all of the produced brine used for de-icing in the U.S. comes from conventional oil and gas wells or from naturally occurring deposits. Fracking water is rarely used because it simply is not very salty—the millions of injected gallons dilute the salt, making it impractical as a de-icer. Transportation departments from nine cold-weather states who were contacted because they all have shale oil deposits and most have fracking operations (Colorado, Connecticut, Indiana, Michigan, New Jersey, New York, North Dakota, Ohio and Pennsylvania) said they don't use fracking production brine for de-icing. (Despite this rare use, a number of municipalities, including Westchester County, N.Y., have banned the spread of fracking wastewater on roads.)
A 2014 U.S. Geological Survey study analyzed roadside sediment where produced brine from conventional wells had been spread as a de-icer and found elevated levels of radium, strontium, calcium and sodium. Radium is radioactive and can thus be carcinogenic. At high concentrations, sodium can be unhealthy for humans and animals. In plants high sodium levels disrupt nutrient intake, leading to death. The lead author of the study, research hydrologist Katherine Skalak, says the chemical contents of produced brine vary from well to well. When it flows out of the well, these fluids can also contain carcinogens, hydrocarbons and solvents, says Marilyn Howarth, a physician at the University of Pennsylvania's Center of Excellence in Environmental Toxicology. But there is no way of knowing what is in each well's batch without testing every one before spreading the produced brine on roads. "If the practice is going to continue," Skalak says, "we need to be out there collecting those samples to make sure there's no environmental consequences…so that in 10 years we're not realizing we've created a problem."
The question is how often to test and what to examine. In New York State, for example, before approving a permit application for road spreading its Department of Environmental Conservation (DEC) analyzes a representative brine sample for chloride, total dissolved solids, pH, calcium, sodium, magnesium, iron, barium, lead, sulfates, oil and grease content; it also tests for volatile organic compounds including benzene, ethylbenzene, toluene and xylene. Larger volume brine users may also have to report chemical contents annually. But generally, once the application is approved the DEC does not reanalyze every truckload of produced brine. An agency official, who declined to be named, says the existing process will "avoid any environmental impacts to groundwater or wetlands and surface water bodies adjacent to roadways."
Ohio, in contrast, does not require gas and oil well tests for every application before the raw brine is used as a de-icer. State law does limit where, when and how much produced brine can be spread on roads but leaves it up to local authorities to approve individual applications. State universities have conducted a few research studies on the environmental impacts of the practice but the most recent studies cited by the Ohio Department of Natural Resources in its guiding document (pdf) were done the 1980s and 1990s. Another way to prevent possible problems is to filter certain chemicals out of produced brine before it is used. Nature's Own Source, LLC, based in Ohio, has developed a product called AquaSalina that comes from naturally occurring brine deposits and produced brine from conventional wells; Before the product is considered road-ready it is filtered to remove hazardous substances, such as lead and hydrocarbons. Owner David Mansbery says before going to market in 2004 the company had its products extensively tested by external labs for environmental effects to obtain the necessary permits from Ohio authorities.
The company only uses the brine when the chemical content reaches safe drinking water levels, Mansbery says. They do allow a few chemicals to remain at a higher concentration: magnesium chloride, calcium chloride, bromine chloride and sodium chloride—all salts. AquaSalina, like most of its produced water counterparts, is naturally high in magnesium chloride, which makes it more effective at temperatures down to –26 degrees Celsius (rock salt is only effective to –6.5 degrees C).
The tricky aspect to regulating produced brine, Howarth says, is that there are no federal specifications for the standards it should meet before it is spread on roads. "It's a state-based process, and that's what concerns me because some states have taken the posture that they will not regulate [the oil] industry," she notes. "If unregulated, then we may be putting petroleum products, diesel fuel, solvents, known carcinogens on our roads and increasing the risk of cancer and really serious health effects to people."