By Barbara Kessler
Green Right Now
A new study has found that fracking for natural gas poses the greatest threat to waterways and drinking water via approved, regular disposal Â of “fracking water” at municipal and industrial wastewater treatment facilities.
This type of disposal, used in the Marcellus Shale region in the Northeast U.S., is failing to adequately cleanse the wastewater produced by gas wells, according to the study. The result is that ostensibly “treated” water is being Â discharged into streams and waterways still Â contaminated with chemicals and minerals that accumulate during the fracking process.
The research by Dr. Sheldon Reaven and engineering doctoral student Daniel Rozell at Stony Brook University in Stony Brook, N.Y., appears in the August 2012 issue of Risk Analysis, published by the Society for Risk Analysis.
The pair set out to survey all the potential risk factors to water posed by hydraulic fracturing, the process by which gas companies extract natural gas from shale rock by shattering the rock with high pressure water mixed with sand, lubricants and chemicals. The two scientists looked at five potential “pathways” in which water could be contaminated by fracking operations: Transportation spills, well casing leaks, leaks through fractured rock, drilling site discharge, and wastewater disposal.
Using a “probability bounds analysis” they found that despite the public’s fears of spills and underground fracking fluid migration, the most significant threat to fresh and drinking water sources was the routine disposal of “produced” wastewater — water that’s been recovered from the gas well after it’s used to crack open shale rock thousands of feet beneath the surface. The higher threat arose because each gas well drilled using horizontal fracking techniques produces a large volume of “produced” or backflow of wastewater that must be discarded, even if its recycled for a second use. (The study didn’t rule out contamination from a direct wastewater spill or other accidents, it simply identified the wastewater process as the most likely to pollute water.)
Even if only 10 percent of the Marcellus Shale region was developed by natural gas companies, the result would be 40,000 gas wells producing a volume of fracking backflow equivalent in the aggregate to a few thousand Olympic-sized swimming pools, the Reaven and Rozell reported.
This fracking wastewater is sent to Â municipal and industrial water treatment facilities, but research has shown that this process fails to adequately cleanse the water, according to the Stonybrook team.
“We were aware that some (of the used fracking water) was going to industrial waste water treatment and municipal plants, said Rozell, an environmental engineer. “The surprise was finding that it wasn’t coming out clean from the industrial plants.”
A key problem, according to the study, “Water Pollution Risk Associated with Natural Gas Extraction from the Marcellus Shale”:
Municipal wastewater treatment facilities are not designed to handle hydraulic fracturing wastewater containing high concentrations of salts or radioactivity two or three orders of magnitude in excess of federal drinking water standards. As a result, high salinity and dissolved solids in Appalachian rivers have been associated with the disposal of Marcellus Shale hydraulic fracturing wastewater after standard wastewater treatment.
The water that comes into contact with shale deposits is very salty, Rozell said, because the shale deposits were formed from a marine environment millions of years ago. The salinity alone can kill freshwater fish and vegetation, and can cause problems when that water is being reclaimed for municipal use, he said.
“If a very salty water is now suddenly flowing into the intake pipes of the local drinking water plant, they have to do very expensive treatment to get it back to drinking water standards,” Rozell said. “…You can clean any water, it’s just not free.”
The Stonybrook team also relied on research by Dr. Daniel Volz of the University of Pittsburgh showing that treated “flowback water” from fracking remained highly salty and contaminated with certain chemicals when discharged as treated wastewater Â into streams.
Volz testified to Congress in 2011 that “studies of effluent from a commercial facility in Pennsylvania that treats fluids only from gas and oil operations shows discharge of 9 pollutants in excess of national recognized human and/or aquatic health standards into a nearby stream.”
Those pollutants, Volz said, included:
- Barium at 8 times the “Minimum Risk Level” (MRL) for children and 27 times what the EPA considers safe for fish.
- Stable Strontium, found in effluent 43.29, 51.68 and 97.90 times the drinking water MRLâ€™s for intermediate exposures for adult men, adult women, and children, respectively. Strontium levels found in effluent were 29,811 times the reporting limit in the plants NPDES permit.
- Bromide, which forms mixed chloro-bromo byproducts in water treatment facilities that have been linked to cancer and other health problems were found in effluent at 10,688 times the levels generally found acceptable as a background in surface water.
- Benzene, a known carcinogen, is present in effluent water at over 2 times its drinking water standard, over 6 times its EPA consumption criteria, and 1.5 times the drinking water MRL for chronic exposure for children.
- 2-butoxyethanol (2-BE), a glycol ether and used as an antifoaming and anti-corrosion agent in slick-water formulations for Marcellus Shale gas extraction was found in effluent water at 24.48, 29.21, and 55.14 times the drinking water MRLâ€™s for intermediate exposure to adult males, adult females, and children, respectively â€“based on hepatic health effects.
- Â Chlorides, the concentration of chlorides in the effluent was 138 and 511 times the EPA maximum and continuous concentration criteria set for the health of aquatic organisms, respectively.
The Stonybrook study notes that regulators are getting stricter with their guidelines for wastewater from gas operations, which is causing some gas drillers to recycle their water.
Gas drillers should also could move to less water-intensive drilling methods, such as those that use nitrogen or nitrogen-based foams, carbon dioxide or even liquefied natural gas.
“Although water-based fracturing is the most commonly used for reasons of cost, familiarity, and effectiveness on low permeability, high pressure formations like the Marcellus, nitrogen-based fracturing is the least expensive and most often used alternative due to its ability to improve low-pressure well production and reduce waste costs,” the study notes.
Others have suggested that such operational changes could save water expended on natural gas extraction, regardless of disposal methods, and particularly in drier parts of the country, like Texas, where fracking water is more commonly disposed of in deep injection wells, such as abandoned oil wells.
The public and regulators will have to decide how best to manage the problem of water pollution from fracking, Rozell said.
“My hope here is that studies like this one and some other ones will help regulators make sure the process is as clean as it could be.”
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