Stavis Seafoods of Boston’s South End lost a worker to a massive ammonia leak in March. Now the company will lose $173,000 in fines levied by the Occupational Safety and Health Administration.

“That’s a big fine,” Boston wrongful death attorney and Chair of the Massachusetts Bar Association’s Workplace Safety Task Force Douglas K. Sheff told The Boston Globe. OSHA found 20 safety violations that it considered serious, including deficient design, operation and maintenance for the plant’s ammonia refrigeration system.

On March 23, 43-year-old Brian Caron of Peabody and four other workers were in the Stavis Seafoods cold storage warehouse when an ammonia pipe burst, flooding the space with lethal ammonia gas. Caron was killed in the accident, which left concentrations of ammonia in the air so high that Boston firefighters had to retreat until the air had cleared. A safety valve that should have stopped the flow of ammonia failed.

Following the accident, Stavis closed the warehouse. The company has also worked closely with OSHA and independent safety consultants to improve its safety systems and procedures.

OSHA found holes in the floor and a lack of containment in the machine room that allowed the potentially explosive ammonia gas to fill the building. The company was also cited for failing to label ammonia piping, failure to test and calibrate ammonia sensors and failure to provide a sufficient ventilation system to prevent the explosion of ammonia vapors.

This is the second-largest fine issued by OSHA against a Massachusetts employer in 2016, and the second issued for ammonia system violations.  In January, A.S General Construction, Inc. was fined $188,000 for repeated safety violations that exposed workers to falls of more than 26 feet. Reinhart Food Service LLC was fined $72,000 in May after a valve in a pump room leaked ammonia and ammonia sensors failed to sound an alarm.

“Again we have a sad reminder that workers can never take safety for granted,” Sheff added. “It is not enough to see safety equipment or hear about safety programs. Workers need to be vigilant and ask questions. Employers need to make sure that every bit of safety equipment works as it should and is tested on a regular basis to avoid tragic accidents.”