A meat worker was taken to hospital after ammonia leaked at an Invercargill meat works last night.
A large cloud of gas greeted firefighters as they arrived at Alliance Group's Lorneville Plant after an automatic gas alarm was activated about 6.30pm, Southland area commander Bruce Stubbs said.
A male worker, aged in his 60s, was taken to Southland Hospital for assessment after he discovered the leak and another man, aged in his 30s, was treated by St John staff at the scene.
Mr Stubbs said the incident could have been much worse, considering the volume of gas.
''When ... it starts to vaporise, it basically multiples by 10,'' he said.
''There's a lot of gas in the cloud compared to the [amount of] liquid that came out.
''It is a risk. Dealing with that stuff is always a concern but Alliance have got some good systems in place.''
Six appliances from Wallacetown, Invercargill and Kingswell stations attended and 30 firefighters were involved in isolating and cleaning up the spill.
Alliance Group communications manager Nicole Taylor said the plant's 700 workers were evacuated immediately.
According to company policy, those who identified the leak were assessed by medical staff.
Police assisted the Fire Service in establishing a cordon around the plant in Crowe Rd.
''We treat anything like this very seriously,'' she said.
It was not known what caused the leak, which occurred in a freezer area at the plant, or how much ammonia had leaked.
The plant was expected to reopen for processing last night, she said.
''We are in the process of looking at what has caused it,'' she said.
''It's something that we prepare for and one of those things we have to manage. We do quite a lot of drills and have processes in place to make sure we can respond appropriately.''
Mr Stubbs said the leak was contained by about 7.30pm and the cordon was lifted late last night.
Drains at the plant fed into a holding pond and the liquid ammonia would not escape off site, he said.
Environment Southland was contacted to assist in cleaning up the leak.
The male worker was released from hospital late last night.
