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 On October 6, 2021, an accidental release of crude oil and produced water occurred during vacuum truck loading operations at  a facility. An unknown amount of flammable vapors from the released fluids ignited, resulting in a flash fire that seriously injured the vacuum truck driver.
An emulsion layer periodically developed at the oil and water interface within the heater treater at the facility and grew thicker over time. The presence of the emulsion layer impaired the heater treater’s efficiency. To address this problem, the company periodically removed the emulsion layer by transferring fluids from the heater treater to a vacuum truck.
The company's investigation identified the sequence of events as follows:
1. The contractor vacuum truck driver discussed the planned work with an operator, and the operator approved the truck driver to start the loading operation;
2. The vacuum truck driver connected a three-inch hose between the truck and the heater treater;
3. The driver opened valves on each end (the truck inlet valve and the process valve);
4. After these valves were opened, produced water and crude oil flowed from the pressurized heater treater into the vacuum truck (the truck’s vacuum pump was not operating);
5. When the vacuum truck driver detected crude oil, he closed the process valve on the heater treater to stop additional fluid from entering the hose; and
6. The vacuum truck driver disconnected the hose from the heater treater, and the contents flowed out of the truck and into the atmosphere through the open hose. The released fluid contained flammable hydrocarbon vapor that ignited, creating a flash fire that seriously injured the driver.
The company’s investigation concluded that the fired heater treater components may have been the ignition source. The heater treater burner was inadvertently left online during the vacuum truck loading operation. The company's investigation team did not eliminate static electricity as the potential ignition source because the hose components were non-conductive, and the truck was not electrically bonded or grounded.
The company's investigation identified additional causal factors, including:
A. The procedures, training, and administrative controls did not effectively control the hazards associated with draining an emulsion layer from its heater treaters;
B. No safety or hazard analysis was performed to identify or control potential hazards before performing this work;
C. There was no pre-determined location to electrically ground or bond the vacuum truck; and
D. Using system process pressure from the vessel to transfer the fluid to the vacuum truck rather than using the truck’s vacuum pump to pull the fluid into the truck contributed to the incident.

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