How safe are saltwater spills?

Saltwater leaks have been reported in alarming numbers throughout North Dakota since the state’s oil boom began.

spillsPosted 1/16/14

By Bryce Martin

While it is the duty of oil companies to report such events, residents and landowners may be unaware of a leak’s potentially serious impacts.

A leak of about 50 barrels of “salty water” was reported to have occurred Jan. 8 in Bowman County, according to the North Dakota Department of Health. The leak originated from a Denbury Onshore, LLC saltwater reservoir, deep below the earth’s surface. It is the most recent leak within Bowman County, following a major leak in November of nearly 17,000 barrels of saltwater.

Varying accounts of just how much chloride was contained in last week’s leak caused contention between Denbury and the Department of Health.

“I know our press release came out and said salt water; I know Denbury isn’t very happy about that,” said Kris Roberts, an environmental geologist and environmental response team leader with the North Dakota Department of Health. “But it is a saltier water. It cannot be considered fresh.”

Denbury said the leak was of source water.

“It is saltier than fresh water by quite a bit, but it is not as salty as many of the produced waters,” Roberts said.

Descriptions of saltwater vary depending upon at what stage it is leaked.

Source water is naturally occurring water extracted from the earth that contains salt. The 17,000-barrel saltwater leak from Denbury’s Bowman County pipeline in November also was source water. The leak occurred in a portion of pipeline going from the well to the tank battery. The tank battery is where chemicals are added to the solution before it’s put into tankers to minimize corrosion. Because the solution had not reached the tank battery, it contained no additive chemicals, said Dennis Fewless, director of the Water Quality Division of the Department of Health.

Another type of saltwater is produced water, which contains saltwater as a byproduct from a producing well; it is a mixture of saltwater, oil and gas.

Chloride concentrations of Miller #9, the water supply well involved in last week’s leak, contained chloride concentrations of 663 to 1,042 parts per million over a given period of time.

“That’s saltier than you want,” Roberts said.

Saltwater is pumped from shale formations and out to a water plant. From the plant, it is re-pressurized with pumps and split out to various injection well locations. It was one of these lines coming from the water plant that experienced a leak, on the edge of Kid Creek, into which the water flowed.

The leak in November flowed into the Big Gumbo Creek in Bowman County, which has a continuous route to the Little Missouri River with no dams backing it up.

Cleanup of the Big Gumbo Creek reached below the health department’s satisfactory amount of chloride, meaning the levels of saltwater contained within the creek were adequate.

From sampling completed by the department, Fewless said the contamination did not reach the Little Missouri River.

Kid Creek, which Roberts said is currently flowing, feeds into an irrigation reservoir about one mile downstream of the 50-barrel leak’s origin. The irrigation is used on a large hay field nearby. Roberts said because the dilution would be extreme, it minimizes any negative impacts from the leak as long as Denbury is correct in estimating its size.

“They have to estimate on this one,” Roberts said. “Their meters aren’t fully calibrated – they’re close, but they’re not fully calibrated.”

The Department of Health is examining the possibility of asessing fines to Denbury following these two recent leaks. Environmentally, however, both the company and the health department work hard to minimize any impacts of a saltwater release, Roberts said.

“We have not yet seen a company that has balked at doing everything they can to clean something like that up,” he said.

On the other hand, as Roberts indicated, there is possibility in Bowman County that there will be some leaks that could go beyond containment and flow into the Little Missouri River. Some also could lead into other irrigation reservoirs.

Throughout the winter months, there is no irrigation. Had the leak occurred in the spring or summer, when irrigation actively occurs, it could have been a serious issue, said Dean Pearson, Bowman County Emergency Manager.

“They would have been spraying saltwater over the entire field and it would have decimated the field,” Pearson said.

The possibility is great for saltwater contamination to reach draining systems, streams and into the fresh water surface supply following a release, which represents the biggest concern.

“If a pipeline breaks in the middle of someone’s field, the saltwater is much more of an issue than the oil,” Pearson said.

According to Pearson, oil, in a true sense, is almost a fertilizer of sorts. It can be burnt off, scraped off or mixed with the soil; plants can actually use it to grow, he said. If mixed with production water, however, the salt kills everything.

“Oil makes a big mess, but you can usually clean it up and make it productive again,” he said. “Once saltwater hits the ground, you have a hard time getting salt out of the ground.”

Roberts agreed, saying, severity-wise, most in the industry and on the environmental side would rather try to clean up an oil spill than a saltwater spill.

“Saltwater spills are harder; they cause more damage,” he said.

As far as an area’s drinking water supply, the possibility for contamination is much less common but still exists.

Only a catastrophic event would cause saltwater contamination to Bowman’s drinking water supply, Pearson said. If there were a problem with what goes down through the ground, if that would happen to break at the horizon of where the drinking water originates it would be an avenue for contamination, but that is cased in concrete and multiple layers of steel.

“It would take something catastrophic to actually perforate the casing of the level of our drinking water,” Pearson said. “It’s more of a contamination issue … if that line should break, it’s going to go into the surface – (a) long way above our drinking water source.”

The real, worst-case scenarios for Bowman County would be a contamination flowing into the Little Missouri River, Pearson said. It is a nationally recognized waterway and if that happens, the Environmental Protection Agency gets involved. Also, if saltwater gets into the middle of someone’s field where they have crops growing, it would contaminate the soil, which would have to be dug out and replaced.

Environmental consequences of such contamination would be significant.

If, in a case like the 50-barrel leak, there were a very salty water release into an irrigation pond at a very high volume, drastic damage to the field would result, according to Roberts. Aquatic life also would be in danger. Fish could be killed or the source of food for the fish could be damaged.

“Our aquatic environment could be damaged to the point where there would be a negative impact,” Roberts said.

About 1.5 miles below the surface of southwestern Bowman County is the Lodgepole Formation. Oil companies have permits to pump out naturally occurring saltwater from the formation, which is then used for water flooding.

Water flooding is a means to promote oil production and recovery. Oil companies extract water from natural saltwater reservoirs, such as the Lodgepole Formation, and elsewhere inject it back into the ground under pressure. The saltwater pushes the oil out of the particular formation and into the well that is sucking it from the ground.

Bowman County has a lot of shale formations, of which the Pure Formation is the deepest. The Lodgepole producing water is about 4,000 to 5,000 feet below the bottom of the Pure Formation.

The water supply for the city of Bowman stems from either the Hell Creek Formation or the Pure Formation, according to Pearson.

If saltwater contamination occurs to either a human or livestock drinking supply, it is required by law that the company responsible for the release provides an alternate water source.

“And they will,” Roberts said. “We’ve had that happen.”

The city of Alexander, located about two hours north of Bowman, experienced saltwater contamination to Charbonneau Creek in 2006. It was the worst saltwater leak of the last decade, according to Roberts. Following the leak, the company responsible provided an alternate water source for the area.

In 2010, the health department assisted in the cleanup of a water line leak in Bottineau County that had a strong negative impact on 23 acres of farmland, which also contained a wetland easement from the U.S. Fish and Wildlife Service. Several ponds were filled with high concentrations of saltwater.

“We are still dealing with both of those situations to get them fully remediated,” Roberts said.

Because Bowman County is more involved in the production side of oil recovery, opposed to active drilling, the infrastructure is already in place and is aging, presenting possible sources for saltwater leaks.

“When the frost gets in the ground in the fall and things freeze up or when they thaw out in the spring, a lot of times you have movement of the earth and that could separate some older pipes,” Pearson said. “We’re probably more prone to leaks.”

Pearson said a leak of either oil or saltwater occurs two or three times a month on average, but generally they are small.

The companies responsible for saltwater leaks are generally not considered negligent, according to Pearson. Because of the aging lines in Bowman County, Pearson said several companies replace old pipeline on a regular basis. They also conduct pressure testing to determine which lines may be prone to possible leaks.

One of the issues in the past for most oil-producing counties, however, is county officials not being notified when a leak occurs.

“That’s one of the things we’ve been trying to get the state to do is, when the oil companies notify the state, that they also send the notice out to us so that we know what’s happening in our own county,” Pearson said. “Sometimes that happens, sometimes we don’t hear about if for a couple days.”

 


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