In July of 2012, the mother of 21-year old Dustin Bergsing filed a wrongful-death suit in Yellowstone County District Court. Bergsing died on January 7 of that year — his first child was born just six weeks prior. The cause of death was hydrocarbon poisoning. More specifically, Bergsing died from inhaling fatal amounts of petroleum vapors after gauging a crude oil tank on a Marathon Oil site in Mandaree, North Dakota. Here is what happened (from a North Dakota Supreme Court apellee brief):

Dustin Bergsing was working for Across Big Sky when he was found dead at a Marathon well-site near Mandaree, North Dakota, in the early morning hours of January 7, 2012. Across Big Sky also submitted a report of death, describing the accident happened when Bergsing was "on the catwalk and was going to gauge the oil level in the production tank." On January 6, 2012, Bergsing left the home he shared with Lacey Breding in Montana to start his shift in North Dakota. The week before, Breding and Bergsing began making plans for their wedding, which was scheduled for June 30, 2012. The night of January 6, Breding and Bergsing were messaging each other, and Bergsing stopped responding around 9:30 p.m. The next contact Breding had was from the Dunn County Sheriff's Department at approximately 4:15 a.m. informing her Bergsing had died… The bloodwork showed Bergsing had ethane, propane, butane, isobutene, pentane, hexane, and cyclohexane in his blood.

The concept of tank gauging is simple: workers check the level of oil in storage tanks at tank batteries by opening a hatch and putting a gauge inside. Here’s how it works:

One of the problems with manual tank gauging is that, as one might imagine, noxious vapors have a tendency to build up inside the tanks and so, when the hatches on top are opened, those vapors are suddenly released into the previously breathable air around the workers. Breathing these hydrocarbon “plumes” can lead to sudden death by asphyxiation and/or cardiac arrest. In some cases, tank gauging is done alone, increasing the risk of fatal accidents.

Nine workers have been killed over the past four years in circumstances that strongly suggest hydrocarbon poisoning as the likely cause of death, and yet so far, only one of the fatalities has been solely attributed to hydrocarbon vapor inhalation.

As far as the oil & gas industry’s position on the dangers of manual tank gauging is concerned, there appear to be two possibilities: either they did not realize that opening a hatch on top of an oil tank and looking inside might expose workers to dangerous fumes, or they did realize this and chose not to do anything about it. Here’s WSJ:

The deaths of Trent Vigus and at least nine other oil-field workers over the past five years had haunting similarities. Each worker was doing a job that involved climbing on top of a catwalk strung between rows of storage tanks and opening a hatch. There were no known witnesses to any of the men’s deaths. Their bodies were all found lying on top of or near the tanks. Medical examiners generally attributed the workers’ deaths primarily or entirely to natural causes, often heart failure… According to some industry-safety and government officials. The industry has been ignoring warning signs for years and has been resistant to implementing some steps that would reduce or eliminate the risk to workers. “I was trying to get workers into respirators and all kinds of things and running an uphill battle,” said a former industrial hygienist for a large oil company who said he had noticed dangerously high hydrocarbon levels in some of his testing as far back as 2009. “They say, ‘Everyone does it this way.’ But that doesn’t make it any less right or wrong.” Some industry officials said that companies hadn’t realized there might be a problem until the pattern of deaths began to emerge, but they now acknowledge the situation needs to be studied further.

One company that surely did “realize there might be a problem” was Marathon because, as the following excerpt from the Billings Montana Gazette details, both sides in the wrongful death suit of Dustin Bergsing agreed that hydrocarbon poisoning was indeed the cause of death and although the exact amount of the settlement wasn’t revealed, someone apparently made a payment to the family “in the seven-figure range”:

A confidential settlement has been reached in a lawsuit involving a Montana man who died working at a Marathon Oil well in North Dakota. An attorney representing the family of Dustin Bergsing said Friday that he could not reveal any details of the settlement. Fredric Bremseth, of the Bremseth Law Firm in Minnetonka, Minn., said only that "the case was resolved for a confidential amount”... In pretrial statements filed by attorneys for the family and Marathon Oil, both sides agreed that Bergsing died of hydrocarbon poisoning… The statement said Marathon Oil "knew or should have known that the oil well and tank facility where Dustin Bergsing worked was unreasonably dangerous due to the presence of a large amount of toxic hydrocarbon gases under pressure in the oil." The statement further said that Marathon "was actually warned by an employee that the accumulation of gases at these wells was ultrahazardous, and could result in a death." A computation of damages hadn't yet been done, the statement continued, "other than to value the case in the seven-figure range."

Fortunately for everyone in the oil & gas industry who may have been hitherto unaware that breathing hydrocarbon vapors emitted out of giant oil tanks might be dangerous, both the CDC and OSHA have put together some helpful information on the subject.

From the CDC:

NIOSH researchers, along with officials from the Occupational Safety and Health Administration (OSHA) and members of the academic community, have continued to investigate these and other reports of worker deaths associated with manual tank gauging and sampling operations in the oil and gas extraction industry. Through this investigation, NIOSH researchers have now identified nine fatalities of oil and gas extraction workers from January 2010 to December 2014 associated with tank gauging or sampling. The degree of detailed information about each case varies but all have in common manually gauging or sampling production tanks at oil and gas well sites… When hatches on production tanks are opened by a worker, a plume of hydrocarbon gases and vapors can be rapidly released due to the internal pressure present in the tank. These gases and vapors can include benzene, a carcinogen, as well as low molecular weight hydrocarbons such as ethane, propane, and butane. In addition to asphyxiation and explosive hazards, exposure to high concentrations of these low molecular weight hydrocarbons can have narcotic effects, resulting in disorientation, dizziness, light-headedness and other effects.

For those wondering what a deadly hydrocarbon plume looks like, here’s an infrared image which shows you just what it is that these workers are breathing when they open the hatches atop the oil tanks...

...and here is OSHA to explain exactly how the buildup occurs and what happens when the vapor is released…

Hatch is closed. No visible emissions, greater than 95% VOCs produced are controlled. Gases and vapors in tank are in equilibrium with gas and vapors in the liquid hydrocarbon. The different gases and vapors are exerting pressure on the container.

Hatch is opened. A large volume of gases (mostly propane and butane) rush out of the hatch very quickly. The “cloud” can displace oxygen in the immediate work area and presents an immediate asphyxiation hazard.

Below, courtesy of the CDC, is a list of the circumstances surrounding each of the nine workers’ deaths. Note that the fatalities are variously attributed to things like atherosclerosis, diabetes, and tobacco use. Particularly absurd is the fact that the following series of events was attributed to ischemic heart disease ("natural causes") with no mention of hydrocarbon vapors:

The employee (52 years old) lost consciousness while pulling an oil sample out of a thief hatch on a tank. The employee fell backwards on the 90 degree corner of the catwalk guardrail. The employee's clothing became hooked to the guardrail. The employee was hanged by his sweatshirt hood. From the toxicology report, autopsy, and extensive air monitoring conducted by the employer and emergency personnel it was determined this individual died from natural causes. The cause of death was sudden cardiac death due to ischemic heart disease. Contributing factors include atherosclerosis and cardiomegaly.

While "natural causes" are blamed in most of these cases, it seems to us that there is a very real possibility that most (or all) of these fatalities were the result of hydrocarbon poisoning and thus could have been entirely avoidable. Of course the likely reason why the proper solutions have not been implemented is that fixing the problem would cost money. Here's WSJ again:

Some industry experts say the industry knew the plumes could unleash potentially dangerous vapors and should have been monitoring the chemical levels all along. And, they say, companies could implement safety fixes that would reduce or remove hazards. One option is to use automated or remote methods to read tank levels. That is done regularly elsewhere, including in Canada. “There’s no question in my mind it was absolutely known” that there were dangerously noxious fumes coming from the tanks, said Dennis Schmitz, a safety consultant for oil companies in North Dakota. “You are absolutely required to evaluate that hazard before you put that employee up there.” “Every hazard should be engineered out,” added Mr. Schmitz, who acknowledged that fixes would add some cost.

We'll leave you with the following quote from Dr. William Massello, a North Dakota state forensic examiner, and a forensic pathologist — these are some of the things that can happen should you inhale toxic hydrocarbon vapors right before you coincidentally die of "natural causes":