Torbay/Browns Bay Wastewater Sewer Upgrade Improving beach water quality

Work began in November 2006 on a $5 million project to upgrade a major sewer running through a tunnel between Torbay and Browns Bay. The work will take about a year to complete and will see the existing 40-year-old sewer, which is corroded and running at capacity, replaced with a larger pipe. The tunnel is about 750 metres long and runs deep beneath the headland between Browns Bay and Waiake Beach.

The project is a critical part of Project CARE, which aims to reduce the number of wet weather sewage overflows onto the city’s beaches, by repairing and improving the city’s wastewater network.

Much of the work will take place deep underground with access to the tunnel via portals at the southern end of Waiake Reserve and the northern end of Manly Esplanade. Consequently construction sites will be set up at these portals in late October or early November for the duration of the project.

A small number of vehicle parking spaces will be unavailable for the duration of the project.

Great care will be taken to protect trees at each site, however branches will be trimmed from some trees. A small pohutukawa will be removed from Manly Esplanade and replaced with a new specimen when the works are complete.

It is likely there will be some noise and additional traffic movements from the sites. Construction hours will be limited to 7am to 7pm Monday to Friday and 7am to 4pm on Saturdays.

Once the project is completed both these areas will be reinstated to their original condition. The existing sea wall at the southern end of Waiake Beach will also be restored as part of the project.

The work programme

The first work undertaken will be to construct a temporary pump station at Waiake Reserve and install a pipeline over the ridge to carry existing wastewater flows, while the work in the tunnel is being carried out.

The pipeline will run beneath Beach and Sharon Roads and then down to the northern end of Browns Bay via the section of coastal walkway known as Lotus Walk.

It will be installed by directional drilling to minimise disruption to traffic and residents. Both roads will remain open at all times although traffic may be reduced to a single lane at times. Vehicle and pedestrian access to all properties will be maintained at all times.

Lotus Walk, from Manly Esplanade to Sharon Rd will be closed to the public for the duration of the project, because that section of the diversion pipeline will run along the surface. An alternative route will be available and signposted between Sharon Rd and Manly Esplanade via Clifton Rd and Canaan Way.

A chamber will be built at Waiake Reserve for the temporary pumping station. The pumps, which will operate 24 hours a day, will be underground to minimise noise.

Next steps

Once the diversion pipeline is installed and connected to the existing network, the tunnel entrances will be re-opened and the existing sewer pipe jetted clean. Then our contractors will remove the pipe, and the surrounding backfill by hand. A light-rail system will be installed in the tunnel to help remove the spoil and concrete pipes. The new pipe will then be installed. (see illustration).

As this work progresses, four boreholes will be drilled from small worksites on Clifton Rd, Ridge Rd, and Sharon Rd, down to the tunnel. These will be used for ventilation and for pumping in the cement grout to stabilise the new sewer pipe. The ventilation shafts will be filled and reinstated once the works have been completed.

Keeping in touch.

A project of this magnitude will inevitably cause some inconvenience to the community. However, we will draw on our past experience of major projects and work with our contractors to ensure nuisance is kept to a minimum. We will also maintain regular contact with the local community to ensure you are kept up to date with progress, and any questions you may have about the project are answered.