Water treatment plant taking shape
New plant will future proof water supplies for the next 40-50 years
Work is now well under way on the construction of the most visible part of the Waia¯ri Water Supply Scheme. The scheme involves developing a water abstraction facility on the Waia¯ri Stream, a water treatment plant in No 1 Rd, Te Puke, and an underground water pipeline from the plant to Pa¯pa¯moa.
It is a Tauranga City Council project, with the water to be used to supply around 35,000 homes, enabling both infill growth and new greenfield development across the city.
Once completed, the water treatment plant will be a dominant building on No 1 Rd, close to Trevelyan’s packhouse.
“The intake works are very much in the valley itself and the pipeline is largely buried, so really it’s only the treatment plant that has visibility,” says Tauranga City Council’s water services manager Peter Bahrs.
He says the hope is that the whole project will be commissioned mid to late 2022. “They key thing for me is to have it on line before the summer of 2022-23. “There are a number of elements to the treatment plant and most of that should be finished in the first quarter of 2022, but all the elements [of the water supply scheme] need to be brought together in terms of making sure we commission them individually, then commission
Tauranga City Council’s water services manager Peter Bahrs. them as a whole.”
The city council’s Oropi Water treatment plant was upgraded in 2003.
“Fundamentally the process [at the new plant] is very similar to Oropi, but it’s a new generation of technology.
“We are still using, in essence, micro filtration but the robustness of the membranes and the way in which you clean them and utilise them is quite a lot different from the generation that we have at Oropi. There are efficiency and quality improvements. The membranes last a lot longer as well which is a big efficiency for us.”
While the treatment plant is taking shape, the less visible extraction plant holds the key to the project being completed on time.
“It is probably one of the things that we started first, but has had most of the challenges in terms of the ground stabilisation works — the extraction plant is more crucial than the water treatment plant on whether or not deadlines are met.”
The difficulties have come from the need to stabilise the ground at the extraction point.
“Being a river bank there has been huge amounts of debris and wood and things deposited at depth. When you are building a structure like this you have to consider its long term resilience.
“Overcoming and mitigating liquefaction was probably the key to ensuring that we’ve got a good solution from a ground stabilisation point of view.
“There have been some real design and implementation challenges, but they have been resolved and we are well on the way to building something that will have that longevity.”
As a unique engineering project, the extraction plant has attracted a lot of interest.
“We’ve had quite a few technical people wanting to go and see what’s happening. There have been learnings come out of this and it’s really important that that type of information gets shared.”
Peter says the scheme is hugely important to Tauranga’s future water supply.
“It effectively, not doubles, but pretty much future proofs the supply for the next 40-50 years.”
The water will be piped to a reservoir in Pa¯pa¯moa and will serve the eastern part of the district.
”Currently we are feeding that side of the city from one of our existing treatment plants, so the idea is that the Waia¯ri would feed the Pa¯pa¯moa area and ultimately the whole of the coastal strip up to the Mount.”
That will free up supply from the existing treatment plants to be made available to feed the growth in the west of the district.
Peter says he is enjoying being involved in the project.
“It’s always an amazing opportunity and a unique challenge. For me it’s about balancing it with all the other challenges that come my way, but I’m enjoying it and it’s amazing to be part of something like this,” he says.
“To commission a plant like that is quite challenging but special at the same time.”