Southington ammonia leak stopped, “shelter-in-place” order lifted

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A “shelter-in-place” order has been lifted after an ammonia leak in Southington Sunday night.

The ammonia escaped from Diamond Ice, 93 Industrial Avenue, where it is used in the ice-making process. No one was injured.

Several 911 calls about a strong ammonia smell in the area of Elizabeth Drive, near the Bristol line, came in shortly before 8 p.m., fire officials said. When firefighters arrived, they, too, could smell the pungent odor and saw a plume venting through the roof with the help of thermal imaging cameras. They confirmed the substance was anhydrous ammonia, which is used as a refrigerant and becomes a toxic gas when released into the air.

Authorities alerted residents in both Southington and Bristol through an automated notification system and door-to-door visits, warning them to stay inside and close their windows.

The leak was stopped early Monday, fire officials said.

It happened when a refrigeration compressor failed and a relief valve released anhydrous ammonia into a closed refrigeration room, said Meghan Bard, a DEEP spokeswoman. That activated an ammonia evacuation system, which caused the ammonia vapors to be released into the air through the roof.

Hazardous materials teams from DEEP and Waterbury went into the room in protective suits with self-contained breathing apparatus to close the valve and stop the leak, Bard said, while another crew from the Hartford area went in to measure the amount of ammonia in the air.

After the leak was stopped, dangerous levels of ammonia lingered in the building, she said. The ammonia was expected to dissipate overnight because the building was ventilated.

The air outside the building was monitored the entire time to be sure no hazardous ammonia affected the community, Bard said.

Diamond Ice hired a contractor, Environmental Services Inc. of South Windsor, to vacuum up runoff from the ice-making process. The water had a high pH level because of its contact with the anhydrous ammonia.

The contractor was expected to confirm Monday that the level of ammonia has dropped.

Christine Dempsey may be reached at

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