Bulk wastewater storage - Collins Road

Project summary

Bulk wastewater storage tanks allow wastewater to be stored and later returned to the network. These large tanks will be used when there is heavy rain and it flows into our wastewater system, and the storage of these excess volumes reduces the risk of overflows into the environment or nearby properties. They add further resilience to our network across the city and help us protect public health and the environment, as well as meeting our regulatory responsibilities and supporting growth.

The Collins Road site is the first site of several planned across the city over coming years and is part of the city’s long-term planning. Bulk storage tanks are used successfully in other cities, including in residential areas in Auckland, but are new to our network.

The tanks, each longer than three city buses, have a combined capacity of around two million litres. They will be installed underground and connect to our network via the new connections on Collins Road we installed in mid-2023. Planning, final design and contract award is expected in late 2023 with construction between January and July 2024. Much of the work will be done away from the main transport routes but some road closures are expected at times.

Once the project is complete, most people won’t even realise the underground tanks are there. The site will be re-grassed, with the only visible features being equipment such as a transformer and electrical cabinets, tank access hatches and a driveway for vehicle access, similar to what is seen at wastewater pump station sites around the city. The tanks are sealed and are designed to avoid odour issues.

This project will

Protect public health and the environment
Reflect customer and mana whenua priorities
Support sustainable economic growth

Project features

Two million litres
Combined, the tanks can hold up to two million litres of wastewater and return it to the network at off-peak times.
Underground storage
Underground storage means the community can still use the land above for roads, cycleways or park areas.
First of eight
The Collins Road site is the first of eight areas across the city planned in coming years, and the first to have a site selection process completed.

Where we're at with progress

Stage 1 - Approval

2022-2023
Collins Road multi-criteria analysis, site selection and design.
Stage 2 - Planning

Mid-late 2023
Final design, tender process and construction award.
Stage 3 - Underway

Jan - July 2024
Construction, installation, integrating into network, site remediation and reinstatement of access and cycleways.

Frequently asked questions

Why is this needed?

We need our wastewater network to work well to support a growing city and protect our residents, the environment and meet our regulatory obligations. Our network is reaching capacity in some areas and we need to make improvements to keep our systems safe and reliable for our community.

Why are you starting with Collins Road?

Residents have experienced wastewater overflows in the Melville and Deanwell area in the past, particularly during and after storm events, so this area is a high priority for installation of bulk wastewater storage tanks. Other parts of the city will follow in coming years.

What will be the impacts for residents and traffic?

The site for the tanks is on a council-owned road reserve and is not on Collins Road itself. Much of the work will be done away from the main transport routes but some road closures are expected at times. We’ll maintain access for nearby residents throughout. During the construction, there will be some vibration, noise and some extra traffic and trucks on the road at points. We will be working hard to reduce disruption while this work is carried out.

What will the site look like after the works?

Once the project is complete, most people won’t even realise the underground tanks are there. The site will be re-grassed, with the only visible features being equipment such as a transformer and electrical cabinets, tank access hatches and a driveway for vehicle access, similar to what is seen at wastewater pump station sites around the city. The tanks are sealed and there will be no odour issues.

Does this mean more intensive housing in the area?

Melville and Deanwell are already high-growth areas. These works are needed because there is limited capacity in this area of the wastewater network to accommodate this growth and because we want to have better environmental protection than we have had in the past. This project is designed as a long-term benefit to the area, so we have planned for some growth but it’s primary aim is to get better outcomes for our community from the local and city-wide wastewater network.

Where are the other sites for this programme?

Identifying areas of most need has been happening for some years and has identified eight broad areas of the city for development in the next decade. The Collins Road site, in the southwest of the city, is the first which has been confirmed. In 2024 we will complete a multi-criteria analysis process to identify two more preferred sites in the southeast of the city. Once the locations are finalised, we will work through a planning, design and tender process with a view to construction by 2025/26, subject to funding availability.