THEY started pumping river water into the biggest of Wanganui's new waste water treatment ponds last Friday.
Fast forward about another three and-a-half weeks ? March 26 to be precise ? and 200,000 cubic metres of water will have filled the pond, one of two behind Wanganui's airport.
Rick Grobecker, deputy infrastructure
manager for the Wanganui District Council, said consent to start pumping from the Whanganui River came through last Friday and the pumps started their work immediately.
"At the moment we can pump 24 hours a day because the tides are just right," Mr Grobecker said.
Once the first and biggest pond is full, the 15 aerators that accelerate the cleaning of the 19 tonnes of human and industrial waste from the city every day, will be suspended from overhead cables and start the cleansing process.
He said some salt water is sure to be pumped from the tidal river into the settling pond but that wasn't causing too much concern.
"If a little bit of salt gets in there, we don't mind. We don't want to pump straight seawater in there because that's too much salt and that will affect the treatment process," he said.
To make sure the salt levels are minimal, the water will be constantly monitored until the 10m deep pond is full. The ponds have a combined surface area of 35,000 sq m, the equivalent of eight rugby fields.
Construction on the last stage in the city's multi-million dollar waste water scheme started in July last year.
Mr Grobecker said the project was a "little bit behind schedule" at this stage but they were still confident of having it fully commissioned by the deadline at the end of June.
'"The aerators will start working in mid-April with the secondary pond ? which gives the treated waste a final "zap" from 416 ultra-violet lamps ? ready in May."
The treated effluent will be pumped along a 1.4km stretch of concrete pipe into the Tasman Sea.
