Contamination in North Dakota linked to fracking spills

http://www.eurekalert.org/pub_releases/2016-04/du-cin042716.php

Public Release: 27-Apr-2016
Contamination in North Dakota linked to fracking spills
Metals, salts and radioactivity in brine-laden wastewater years later
Duke University

Accidental wastewater spills from unconventional oil production in North Dakota have caused widespread water and soil contamination, a new Duke University study finds.

Researchers found high levels of ammonium, selenium, lead and other toxic contaminants as well as high salts in the brine-laden wastewater, which primarily comes from hydraulically fractured oil wells in the Bakken region of western North Dakota.

Streams polluted by the wastewater contained levels of contaminants that often exceeded federal guidelines for safe drinking water or aquatic health.

Soil at the spill sites was contaminated with radium, a naturally occurring radioactive element found in brines, which chemically attached to the soil after the spill water was released.

At one site, the researchers were still able to detect high levels of contaminants in spill water four years after the spill occurred.

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"The magnitude of oil drilling in North Dakota is overwhelming," Vengosh said. "More than 9,700 wells have been drilled there in the past decade. This massive development has led to more than 3,900 brine spills, mostly coming from faulty pipes built to transport fracked wells' flowback water from on-site holding containers to nearby injection wells where it will be disposed underground."

As part of the study, the team mapped the distribution of the 3,900 spill sites to show how they were associated with the intensity of the oil drilling.

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"Unlike spilled oil, which starts to break down in soil, these spilled brines consist of inorganic chemicals, metals and salts that are resistant to biodegradation," said Nancy Lauer, a Ph.D. student of Vengosh's who was lead author of the study. "They don't go away; they stay. This has created a legacy of radioactivity at spill sites."

Soil samples collected downstream from spill sites contained higher levels of radioactivity than soil at the spill sites themselves, Lauer noted. This suggests that radium builds up in the soil as the spilled brine flows through the environment.

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One of the state's largest spills to date occurred in 2014, when an underground pipeline leak caused approximately 1 million gallons of brine to flow down a ravine and into Bear Den Bay, about a quarter mile upstream from a drinking water intake on Lake Sakakawea.

"Many smaller spills have also occurred on tribal lands, and as far as we know, no one is monitoring them," Vengosh added. "People who live on the reservations are being left to wonder how it might affect their land, water, health and way of life."