HEB Construction was awarded a $105m design and construct contract to upgrade the Mangere Wastewater Treatment Plant (MWTP) in June 2015.

The project included the construction of a biological nutrient removal (BNR) facility, which has increased the treatment capacity to serve an additional 250,000 people.

Along with our fully integrated joint venture partner McConnell Dowell, HEB constructed two reactor tanks, two clarifiers, flow splitter box, blower building, several pump stations, and interconnecting pipe work with the existing plant, including a twin 1400 dia pipeline 1.2kms long.  

A new interstage pumpstation and blended sludge storage tank was constructed within the existing plant.

The JV was responsible for the design and construction of the reactor and clarifier tanks, where the JV elected to construct a post tensioned precast concrete structure.

Large precast concrete panels were cast and erected on site to form the tank walls. This has provided an economic and safer construction methodology by reducing the work at heights requirements.

There are underlying soft soils in the area, which has seen these large tanks founded on some 2400 driven piles.