BNR expansion project at Mangere Wastewater Treatment Plant underway

Projects, 2/08/2017

Work on expanding the new Biological Nutrient Removal (BNR) facility​ at the plant is progressing well and is on track to be completed by the end of the year.

Earthworks began in late 2013 and since then, up to 250 contractors a day have been on site as the $141 million project has taken shape. A new four-stage treatment reactor, two new 52-metre diameter clarifiers and associated pump stations, pipes and blower facilities have been built. The focus is now on installing 70 kilometres of data and power cables.

The new facility will increase Mangere’s BNR capacity as Auckland’s population grows by an estimated one million people over the next 30 years.

BNR project manager Sven Harlos has overseen the design and construction: "The project has gone extremely well, despite some torrential rain we’ve experienced earlier this year.

"Construction activity will taper off in September and then commissioning will begin, followed by performance testing next year."

The plant’s increased capacity will ensure the highest quality treated wastewater continues to be discharged to the Manukau Harbour, even during heavy rainfall, which is good news for the environment. 

In order for work to take place, a new road linking Ascot Road and Puketutu Island had to be constructed. The public has benefitted too, with the creation of a new pathway between the hugely popular Watercare Coastal Walkway and Greenwood Road Park. 

We have carried out extensive planting in the area as part of the Mangere Coastal Restoration project in the early 2000s. With BNR construction, more landscaping and planting of 100,000 native plants was done to shield the facility, which lies to the south of the existing Mangere treatment plant.  

Mangere Otahuhu Local Board Chair Lydia Sosene said: "The new Mark Ford Drive, landscaping and planting around the facility is looking great, helping to screen the new facility while also improving opportunities for walking and cycling in the area." 

Both Mangere and Rosedale wastewater treatment plants use primary (mechanical), secondary (biological) and tertiary (filtration and ultraviolet radiation) methods to treat wastewater before it’s discharged into the Manukau and Waitemata harbours.