Clarks Beach Wastewater Treatment Plant upgrade passes first milestone

Our upgrade of the Clarks Beach Wastewater Treatment Plant has reached its first significant milestone with the commissioning of a new ultra-filtration unit.

Programme delivery manager Dave Kennerley says the treatment plant upgrade and outfall project will deliver significant improvements to the community and to the environment.

“This upgrade introduces sophisticated technology that will allow the plant to produce exceptionally high-quality treated wastewater, which ultimately benefits the Manukau Harbour. The treated wastewater will be discharged via a new outfall that extends 100 metres into the Waiuku Channel at a highly dynamic part of the harbour where it will quickly disperse.

“The treatment plant upgrade and outfall also support population growth in the short term. The existing plant treats wastewater from about 2500 people in Clarks Beach and Glenbrook. The upgraded plant will treat wastewater from up to 6000 people, which is expected to cover growth through to 2030.”

Project manager Sophia Chan says significant progress has been made since work started on site in August.

“The existing plant – located within the grounds of the Clarks Beach Golf Course – features a membrane bioreactor, oxidation ponds, gravel beds, sand filters and UV treatment. There’s very limited space so we are essentially building a whole new treatment plant on top of the existing treatment plant. We need to decommission the gravel bed and sand filters to make way for the new membrane aerated bioreactors (MABR), which will provide high quality treatment using technology that is ideal for rural treatment plants.

"But in the meantime, we need to keep the plant running and make sure it’s compliant. This is why we’ve installed ultra-filtration equipment – it will effectively provide the same treatment as the gravel bed and sand filters.

The ultra-filtration went into service in early November, which means the space used for the gravel beds becomes available for construction of the MABR.

Photo: The first 10-metre-long tank arrives on site and is lifted into place by a 40-tonne crane on wheels

Chan says the delivery of the first tank that will house the membranes was another milestone.

“The 10-metre-long tank came from another Watercare project in Wellsford and had to be lifted off the truck and put in place with a special 40-tonne crane on wheels.”

The first MABR tank will be commissioned in time for winter next year. The wastewater treatment plant upgrade and outfall are expected to be completed in June 2026.

Chan says every effort is made to minimise disruption to the golf course.

“We’re in regular communication with the golf course management because our access road crosses the course, and as construction ramps up there will be a lot of truck movements. We try to plan our major activities for the golf course’s quieter days.”

Meanwhile, construction consents for the new outfall have been granted, and the golf course’s irrigation pipework has been relocated to allow access to the outfall site.

Creating access to the outfall site will involve road works on Stella Drive, as well as the construction of a ramp into the treatment plant.

The outfall will be built using a tunnel boring machine, which is expected to start tunnelling in April 2025.