6 November 2024:

The Te Mārua Water Treatment Plant Optimisation project for Wellington Water has reached a key milestone.

The first of three DAF (dissolved air flotation) ‘trains’, which Fulton Hogan’s Wellington Civil team is delivering with the support of Civil’s inhouse mechanical and electrical department, was commissioned on 31 October. This will add 20 megalitres per day to Wellington’s water network.

Civil Operations Manager – Southern, James Harrison, says the 31 October date was a stretch target, and completing it on that date says much about the quality of the team.

“They’re a great team doing a great job,” James says.

The remaining DAF trains will be commissioned next year after the summer peak. Dissolved air flotation is a process that separates solids and liquids by introducing fine air bubbles into the water. The air bubbles attach to the suspended solids and float them to the surface of the water, where they are skimmed off and removed.

Fulton Hogan proposed completing one DAF train ahead of the other two to bring increased volume on stream sooner to help alleviate summer peak water demand experienced in Wellington.

Fulton Hogan Commissioning Manager, Geoff Ryan, and Project Manager, Laurence Da Silva.

Project Manager Laurence Da Silva says the greater capacity has the additional benefit of making it easier to close parts of the site for planned maintenance in future.

The plant is also notable for being just 30m from the main fault line, necessitating a significant amount of additional engineering resilience built into the concrete and steel structure to survive a one-in-2500-year earthquake.

The Te Mārua DAF is unusual as DAF systems are typically used in the treatment of wastewater, particularly in New Zealand’s dairy industry. This is believed to be only the third DAF constructed in the country for treating drinking water.

To see time lapse of the development, you may wish to watch: www.youtube.com/watch?v=bRdSa0w2DmU