BISMARCK-Until the sheriff came to town, oil companies poured toxic saltwater into open pits to evaporate.
Starting in 1981, the newly created Oil and Gas Division started regulating reclamation and, within two years, those pits were condemned. They were covered over, but they didn't go away.
Call it saltwater, brine or production water, by any name it's a fluid byproduct of oil wells 10 times saltier than ocean water. Today, about 1 million barrels of it are pumped to the surface daily, though protocol now requires it to be trucked or piped to deep injection wells.
When it's spilled, the salts kill plant life, foul water and sterilize soil. A fix is required and increasingly, the old "dig and haul" method is falling out of favor, says Bill Suess, spill investigator for the state Health Department.
"It's quick but expensive. You have to find a place for the contaminated soil to go and find replacement soil that's similar. It can be tough," Suess said.
Those condemned brine pits - like bodies donated to science - may be important teaching tools.
The old so-called "legacy" pits - an estimated 120 of them encompassing about 1,500 acres in Bottineau and Renville counties dating back to wells drilled in the '50s to the '70s - are an example of the very worst impact from brine. For years, the saltwater percolated into the soil unimpeded. Recent studies show the salt continues to expand, deeper and wider, now as far down as 15 feet from pits originally only five feet deep.
They are barren scars of toxicity in those northern counties, but they are also an opportunity to study reclamation and remediation for salt-impacted soils.
The Legislature recently re-upped funding to continue research with the ultimate goal of remediating those legacy pits, a project that could cost an estimated $200 million over the next three decades, says Department of Mineral Resources spokeswoman Alison Ritter.
The research is two-pronged. Half is looking into the best way to engineer a solution with underlying drain tiles and water to leach the salts and properly dispose of the fluid. The other half is studying the use of salt-tolerant grasses and soil amendments to grow plants that potentially draw some salt from the soil and help prevent erosion.
Cody VanderBusch, the department's reclamation specialist, said the engineering-based research by the Energy and Environmental Research Center in Grand Forks and plant studies by North Dakota State University's School of Natural Resource Sciences could be valuable tools in dealing with the hundreds of saltwater spills that occur annually.
"We'll definitely find out and learn what we can use with other salt remediation. If we can get those (pits) cleaned up, there's no reason to not get a spill cleaned up nowadays," VanderBusch said.
Salt in the earth
Reported saltwater spills range from a few barrels to the largest recorded in North Dakota, a 3 million gallon spill out of a flow line owned by Summit Midstream in 2015 that entered Blackwater Creek and the Missouri River near Williston. The Summit spill is still in remediation.
Suess said it would not surprise him if the ultimate reclamation cost is in the $60 million range, similar to what Tesoro will spend to remediate a 20,000-barrel oil spill not too far away.
In fact, brine spills account for roughly one-third of all spills from oil and gas activity, according to health department records.
Last year, there were 494 brine spills, equaling 30,000 barrels. Over the past decade, there were 4,831 spills equaling 390,000 barrels of brine spilled, all of these with toxic potential for soil, plants and water.
Plants and salt
NDSU's soil scientist Thomas DeSutter said there's promise, but no quick fix in the science of phytoremediation - that is, using grasses and plants to help heal the soil.
"Biology takes a long time. No one is breeding plants for salt tolerance," he said.
The research involves using soil amendments and additives and establishing salt-tolerant grasses. One additive is gypsum; the calcium in gypsum coheres soil while the salt chlorides and sodium force it apart. DeSutter said the Leland Olds Station at Stanton brought the product online last year, relatively cheaply.
"Oil companies are well aware of its benefits," he said.
Initial results find promise with inland saltgrass and alkali sacaton grass in combination with soil amendments, though a more definitive interim report is due out in June.
Plant remediation studies may not be the sexiest research topic around, but given the problem in the oil patch and the expense of the old "dig and haul" option, they are certainly topical.
NDSU's extension service, with a $200,000 USDA grant, will start a complementary study this year, says Miranda Meehan, an extension stewardship specialist.
This one, in the Mountrail County area, will involve a salt spill in which the oil company's remediation has had limited success so far, she said.
Meehan said 24 small experimental plots on the spill site will be amended with additives including gypsum, lime, organic leonardite, compost and a crystal inhibitor and planted with barley, cover crops, perennial grasses and a perennial barley mix.
She said the goal is to gain information that will be of real help to companies, agencies and landowners who are dealing with salt-impacted soils, or soils naturally high in salt.
"These studies will have a bigger impact when they're put together," she said.
Bring it on
Suess's work at the state Health Department charges him with overseeing all spills that are not contained within the drill pad location, which is most of them.
Over time, the "dig and haul" method of removing and replacing the salt-impacted soils has been used most often. But increasingly, Suess said, companies are using "in place" methods, in part because the soil disturbance from removing to an approved landfill and replacing contaminated soil can cause other problems with instability and erosion, and ultimately, just moves the problem soil from one place to another.
"They are moving more and more to less invasive and intrusive methods," said Suess, pointing to the installation of drain tiles and using irrigation to flush and collect salts. Another is the use of electro kinetics, subjecting the soil to a low current of electricity to heat the soil and cause a reaction between negative and positive ions to drain away saltwater.
More information on plant remediation, soil amendments and engineering methods will be helpful, he said.
A long haul
"We're looking for anything that could work better, but none is a magic bullet. It's a slow process but, in the long run, it does work. The faster companies get on it, the more aggressive they are, the better off they are," he said.
The Charbonneau Creek spill in western McKenzie County is a case in point of the complexity and time involved in repairing damage from saltwater spills. A saltwater flow line owned by Zenergy Inc. ruptured and spilled more than 1 million gallons of brine into the creek, causing a massive die off of aquatic species and grass downstream.
That spill occurred in 2006 and, after hauling away tons of salty soil and pumping out millions of gallons of contaminated creek water, the company may only now be nearing the end of its obligation a full decade later.
At the Charbonneau, the lingering effect of all that salt still shows up in the groundwater, meaning salt is still leaching from the soil into the water. Initially, tests found concentrations as high as 94,000 parts per million. After all that pumping and soil remediation, the concentration in the groundwater is still in the range of 740 to 2,000 parts per million salt. The acceptable threshold is 250 parts per million.
Suess said the project is reaching its final "chapters" and a walk through the area now would illustrate that land and water can be restored, but it takes time.
"It's been 10 years, and we're still at Charbonneau Creek," he said.