Pahiatua Water Treatment Plant

Project Updates

17 February: Walls have been erected on site, building is starting to take shape

15 January:  Workers are back on site, and have nearly completed drainage. The panels are being built offsite concurrently to drainage works. 

16 December 2019: Modifications have been made to the initial design prior to building consent being issued, and a focus is on completing ducting, drainage and foundation work. 

26 September: The Iwi blessing of the water treatment plant site and build process has taken place, with ground works commencing with civil contractors Morris & Bailey working on site. 

The resource consent has also been granted, and finalisation and peer review of the last design elements is underway. The building is going through some final design changes, in preparation for the build work to commence.

2 September: As at the beginning of September, the Detailed Design of the Plant has been substantially completed and construction can now start. See full project update... (290KB pdf)

Project Progress

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Why are we doing this?

This project aims to deliver quality water to the Pahiatua community and visitors that meets NZ Drinking Water Standards and that manages the aesthetics of water for taste, odour and discolouration.

What is proposed?

The Pahiatua Water Treatment Plant is a new plant that will take water from the existing Pahiatua bore and the Mangatainoka River. It will use high quality membrane technology with multiple filters to cope with the impurities and counteract the smell, clarity and taste issues that those waters have. 

The new plant will be able to treat water to high levels of turbidity (cloudiness or haziness), but having two sources also improves resilience as the river can be shut off during periods of very high turbidity or bad algae bloom, with the bore and the  new 6,000 cubic metre reservoir providing supply until the river water clears.

The plant will be located adjacent to the existing water and wastewater treatment plants. It will be built to reduce the noise impact on neighbours. The plant will also be future proofed with room for more filters should they become necessary for population or demand growth and as new technology becomes available.

The plant will be operated remotely and only require staff to visit infrequently. A truck delivery of chemicals will happen once every 4-6 weeks.

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Why is a new water treatment plant required?

Pahiatua’s water supply is drawn from two sources – the Pahiatua bore and the Mangatainoka River. Following a decline in volume of Pahiatua’s bore and with ongoing issues arising from the river water supply (i.e. taste, odour and discolouration), the search for a water source to supplement supply has been ongoing and unfortunately, not successful. Several sites were assessed but no satisfactory source has been found for the volume required.

Continued use of the Mangatainoka River as the additional source is currently the only option with certainty for available volume.

Have neighbouring properties been considered?

The new Water Treatment Plant, which is proposed to be located adjacent to existing water and wastewater treatment plants, will be purpose built to reduce noise impacts on neighbours.

Council hosted an on-site session in April 2019 for neighbours to ask questions of Council staff, and get further information.

What is Council doing to future-proof this new asset?

The Water Treatment Plant will be built to “Importance Level 3 of the Building Code”, ensuring that the Plant is designed for a greater level of earthquake shaking than ordinary commercial structures.

Additionally, the Plant will be future-proofed with room for more filters should they become necessary for population or demand growth (and as new technology becomes available).

Will there be impacts on street traffic?

Residents on the north side of Hamilton Street will experience increased traffic along the Council access way at the back of their properties during the construction of the Plant. This is unavoidable during the construction phase. 

Once construction is complete, this will return to normal (if not reduced) levels of traffic. Chemical deliveries to the Plant will occur less often with a larger truck coming every 6 weeks or so (in comparison to the current situation of smaller, more frequent deliveries).