Our Warkworth Wastewater Treatment Plant expands to cater for growth


First Christchurch had a post-quake shopping mall made entirely of containers. Now, in a New Zealand first … Warkworth has its own ‘container wastewater treatment plant'.
Warkworth is one of Auckland’s fastest growing regions and the town’s existing wastewater treatment plant, located off Alnwick St needs upgrading but until the replacement plant (located in Snells Beach) is completed in four years’ time, a temporary $3.2 million ‘container expansion’ has been put in place that connects to the existing facilities.
Housed within four shipping containers, the new 'membrane biological reactor’ (MBR) side stream facilities will increase capacity to allow for an additional 300 new connections. 
Watercare project manager Alan Brooks says the equipment is working well: “We’re at the cold commissioning stage in which everything is rigorously tested. We hope to be fully operational by the end of October.
“One of the joys of this project is that it’s so sustainable because when we’ve finished with the current need, the containers have the unique benefit of being able to be disconnected and relocated to another site. We haven’t had to waste money on constructing a building that would have to be demolished in a few years’ time, as all the equipment is already sitting inside the containers.”

The modular MBR units also provide resilience, as they can be easily transported to another site in the event of a natural disaster or another emergency.
The containers arrived by trucks four weeks ago from Timaru, South Island. Over five hours, a 200-tonne crane carefully lifted each container into place. Since then contractors have been quickly assembling pumps and filter membranes and plumbing them into the existing plant.
The four containers have been converted into two MBR treatment trains which can work together or independently. Wastewater is pumped into screens, located on the container roof. After that, it travels through a complete activated sludge treatment process, filter with membranes, before returning to the existing plant to be disinfected by UV.
The containers were cut open and lined with fibreglass to create water tanks. Stairs and walkways allow access for maintenance inspections.
Warkworth is phase 1 of a 3 stage, $7 million MBR container project to cope with residential growth. Containers will travel by ferry to our Owhanake Wastewater Treatment Plant, Waiheke Island, before Christmas and work will take place at Clarks Beach Wastewater Treatment Plant, near Waiuku, early next year.
In a further test of innovation and sustainability, the Clarks Beach container treatment plant will trial the use of recycled drinking water membranes sourced from our Waikato Water Treatment Plant, Tuakau, which still have integrity and a remaining useful life.