A spill of "foul condensate" at Kinleith Mill was responsible for residents of Tokoroa waking to a horrible stink this morning.
The mill's operator, Oji Fibre Solutions, said a storage tank overflowed at 8am and was cleaned up in minutes.
Residents of the South Waikato town woke to a strongsmell, but Fire and Emergency have assured them it is non-toxic and not inflammable.
The company's group manager environment and external relations, Philip Millichamp, said: "A storage tank overflowed at 8am and the spill was cleaned up within minutes".
He said the material spilled is a by-product of the pulp making-process, in which wood chips are digested into pulp.
"We would not be surprised if people noticed odour downwind because foul condensate is an extremely odorous liquid containing sulphide compounds like hydrogen sulphide and methyl mercaptan, and these cause odours at trace levels.
"These compounds are the same as those put into natural gas to make it smell, so this can sometimes make people feel they may be smelling a gas leak, but the odour should not be a cause of concern as there is very unlikely to be a danger to people downwind," said Millichamp.
The company has still to determine how much of the liquid was spilled but early indications suggest it was a small amount and was able to be quickly cleaned up.
"The Kinleith Mill has an obligation to control odorous discharges as much as practicable and we will look into the cause of the spill to make sure this doesn't recur," said Millichamp.
A fire truck outside the South Waikato Achievement Centre for disabled workers this morning. Photo / Supplied
One man told the Herald he got up this morning to what he thought was a strong gas smell. He made a coffee and opened the French doors to a horrible stink.
"I went into town and people were saying 'what's that stink'," said the man.
He was told of an incident in Clyde St where the police turned up and said they were considering the closing off the street because of a possible gas leak.
A fire truck was in the street and residents of the South Waikato Achievement Centre for disabled workers were outside, said the man.
South Waikato District Council Mayor Jenny Shattock said the smell was non-toxic and not inflammable and is expected to disappear in the next couple of hours.
On the Tokoroa Public Facebook page, the Tokoroa Volunteer Fire Brigade assured locals that following reports of a strong smell of gas in the town "we have investigated and found it to be non-toxic or flammable and it expect it to slowly disappear over the next couple of hours".
One resident said: "That smell is really horrible and it can't be good for your health."
In a statement, the police said premises on Clyde St reported they were self-evacuating.
"The gas smell was reported to be contained and expected to dissipate within 10-15 minutes," said the statement just after 10am.
