A Heads Rd business has been warned to upgrade its plant after it was forced to dump hydrogen sulphide into the already overloaded wastewater treatment plant.
A strong sulphurous smell was again noticeable over the city in the weekend and the Wanganui District Council's infrastructure manager, Mark Hughes, said this was due to an industrial trade waste issue.
Mr Hughes said the business, which he would not name, contacted the council early on Friday morning to inform them that the pump into their sulphide tank had broken down, and they were unable to hold or treat any more waste. "We were asked to assist by taking the hydrogen sulphide through Beach Road pumping station. We took the hydrogen sulphide as slowly as we could for most of Friday and transferred to the treatment plant," Mr Hughes said.
He said the alternative was to let it go through the stormwater system. "That would have caused considerable environmental and health issues through the river, port and beyond," Mr Hughes said.
He said council officers told the business it would not be allowed to dump its waste in the pumping station again.
"This industry needs to improve its maintenance and upgrade this part of their plant," Mr Hughes said.
This is the latest issue for the city's wastewater treatment plant, which malfunctioned several weeks ago when an extra 56 tonnes of protein waste a day was pushed into the system in a few days. The normal daily input from wet industries is 10 tonnes a day.
The council is investigating which business was responsible for the dump. The malfunction caused a strong and unpleasant odour to waft across the city.
Mr Hughes said the plant's settling ponds were unable to absorb the sulphide waste, so it would be removed by sucker truck. Meanwhile, pipe experts from New Plymouth arrived in Wanganui on Monday to investigate problems with the outfalls pipes. Mr Hughes said the council wished to apologise to everyone who has had to put up with the smell.
"Be assured we are committed to doing everything we can. We would also like to take this opportunity to thank organisations and individuals for what they are doing, and have offered to do, to assist," Mr Hughes said.