Paeroa Wastewater Treatment Plant Upgrade

August 2025 marked a milestone in the construction of Hauraki District Council’s single biggest investment in infrastructure in the district’s history.

The new $40 million Paeroa Wastewater Treatment Plant reached the halfway mark to completion on budget and on time.

To celebrate the halfway mark, a barbecue lunch was hosted on site by the contractor, Spartan Construction and invitations were extended to the Mayor and Hauraki District Council’s Chief Executive, as well as members of senior management. All were given a site visit to view how construction was progressing.

Council Chief Executive, David Speirs commented: “Last time I was at this site, the focus was on drilling and pouring hundreds of concrete piles to stabilize the ground before any building could occur, so there wasn’t much to see. However, at the 50% completion mark, above ground progress is well underway with sludge tanks, filters, filter tanks all in construction. The site is really taking shape and looks great.”

The upgrade will replace three existing oxidation ponds with a state-of-the-art mechanical plant, which is designed to achieve a higher quality discharge to meet with environmental standards. The new plant will be less than a fifth of the footprint of the existing system.

The project includes the construction of the following: A new screening system; concrete aeration tanks over six metres in height; membrane bioreactor technology; new equipment and administration buildings; 240kL sludge storage tanks; sludge dewatering; chemical dosing; and numerous other ancillary structures.

The project forms part of a ten-year, $100 million investment in wastewater infrastructure across the district that began in 2022. This upgrade is sized to meet Paeroa's growth needs up to 2035 in its first phase, with provisions made for stage two growth catering to 2050 requirements.

A spokesperson for Spartan Construction said: "It's been really challenging but we are making great progress. We have a great team on board from Spartan Construction, Hauraki District Council, Veolia, and other key partners. It's enabled us to keep this complex infrastructure, including civil, structural, and mechanical and electrical engineering aspects, on track. There are lots of moving parts."

They added: “We would also like to take the opportunity to thank all of the local businesses who have supported the project.”

Construction work on the Paeroa Wastewater Treatment Plant upgrade is expected to continue through to early 2026 with the new plant scheduled to be fully commissioned around mid-2026. So, watch this space for further updates.

On Friday 23 February, Hauraki District Council signed a $35 million contract, awarded to Spartan Construction Ltd, for the upgrade of its Paeroa Wastewater Treatment Plant (WWTP).

“This is the single largest infrastructure project that Council has invested in. It’s a bold move, one that the community has been asking for and one that gives us confidence in growing our district for future generations”, said Mayor Toby Adams.

“It’s a journey that originally began in 2017 with the preparation of a business case and plan for our wastewater systems. Covid-19 significantly interrupted the flow of the planning in 2020 and the delays escalated associated costs. Added to that was the uncertainty of the proposed changes to 3-Waters”, said Mayor Toby.

Mayor Toby shaking hands with Spartan Construction Managing Director Greg Dodds at the Paeroa WWTP.

“But as a Council and community, we knew that we wanted to be the masters of our own destiny and get this job done. It’s an important upgrade that is essential to meet the new national discharge standards in our resource consent and prepare for future growth of the area.

These upgrades will provide resilience to Council’s networks, modernise their treatment methods to improve environmental outcomes and provide additional capacity for growth.

The Paeroa WWTP upgrade is part of a ten-year, $100 million investment in wastewater infrastructure across the district that started three years ago, in line with the commitments from Council’s 2021-2031 Long Term Plan.

“Today we gave the green light to this essential Paeroa WWTP project. It’s a substantial cost to the community so it was important we got it right and not delay a decision. We’ve gone with the option that gives the most resilience for growth, meets resource consent discharge standards and provides capacity during natural disasters”, he said.

The upgraded plant will move away from the traditional pond-based system to a “mechanical system” to meet the high national environmental water discharge standards set by government. This investment is sized to meet Paeroa’s growth up to 2035 (stage one). Provision will be made, but not built, for stage two growth which caters for Paeroa to 2050.The building site will be raised and levelled to future proof against unexpected natural disasters such as flooding as well.

Work is expected to start by late 2024 and for the new plant to be fully commissioned by mid to late 2026 all going well.

Mayor Toby confirmed that Council will explore all avenues for other funding where appropriate.

“Going forward, we have decisions to make on how this spend is reflected in the rates over the next ten years. We’ll address that in our 2024-2034 Long Term Plan. For now, I congratulate the elected members and Council staff on the huge amount of work done to get to this moment. We can now face the future with certainty”, he said.

Other wastewater upgrades already completed by Council in the district include the upgrading of wastewater pump stations and moving to a computerised, real-time monitoring system (SCADA) of the pump stations; relining of pipes; desludging of geobags at the Paeroa and Waihī Treatment plants; the major upgrade to the Wellington Street Pump Station and associated rising main to Waihī’s Wastewater Treatment Plant.