ROCKLAND — The startling plume of black soot emitting from a Rockland waterfront smokestack July 22 has been traced to a failed relay switch, which runs the fuel flow meter that feeds an oil burner. The stack’s owner, FMC BioPolymer, has subsequently contracted Knight Marine Service to help clean commercial and recreational boats affected by the pollution.

Meanwhile, the Maine Department of Environmental Protection is anticipating today, July 25, a written report from FMC about the incident. The environmental agency is planning to visit the plant next week as part of its investigation.

On Rockland Harbor, FMC produces carrageenan, derived from seaweed, to provide applications for global food processors. The products meet demanding texture requirements and multiple other applications, such as binding agents for toothpaste.

The plant holds an air emission license from the DEP, and the agency’s Louis Fontaine, who is with the air bureau, said: “Most air emission license for boilers limit the amount of smoke that a facility can emit.  Licenses also have allowance for emitting a larger amount of smoke for short periods of time to account for boiler startup, shutdown and combustion variability.  We will be evaluating the information that we get from FMC against the requirements of its air emission license.”

The July 22 incident occurred at 5 p.m. on a sunny and cloudless afternoon. Read: Black cloud of soot settles over Rockland Harbor 

According to company spokeswoman Barbara Delduke, who is based at corporate headquarters in Philadelphia, the sudden emission of heavy soot originated in a boiler burning No. 6 oil. The facility’s boilers are used to generate steam for production, she said.

The faulty relay switch apparently allowed more fuel to enter the boiler, causing nonconverted fuel to turn to soot and flow up and out the stack.

“The switch has been replaced and tested to verify its highest working condition,” she said. “In addition, the site team is continuing to investigate and expects to implement additional fuel management system improvements.”

FMC is in the process of converting from oil to compressed natural gas, and anticipates that to be completed in October.

“Sending too much oil to a boiler can cause it to smoke,” said Fontaine, at the DEP. “There will not be enough air to completely burn the oil, resulting in inefficient and incomplete combustion. Incomplete combustion can also occur during boiler startup and shutdown.”

The DEP has received two complaints concerning the emissions. The Rockland fire department received many calls reporting the plume of soot.

FMC submitted a statement to the community, as well as its Rockland Community Advisory Panel July 24. (See attached PDF)

The company said it provided proper notification to the DEP within the required time period and informed the agency about the situation.

“Our full investigation continues and implementation of improvements by the team are ongoing,” the statement said. “Our team is working closely with everyone who called the site with questions and requests for assistance.”

Editorial Director Lynda Clancy can be reached at lyndaclancy@penbaypilot.com; 207-706-6657.