Design solution secured for Vaucluse Diamond Bay outfalls

02 April 2020

Following geotechnical work in November 2019, the engineering solution design to divert the last three untreated wastewater coastal outfalls in Sydney is nearing completion. Community feedback from the project’s community reference group and local councils has contributed enormously to how the works will be designed to blend with the local environment.

Member for Vaucluse, the Hon Gabrielle Upton said community involvement in guiding the design for the Refresh Vaucluse Diamond Bay project has proved invaluable in identifying local values and priorities.

“Sydney Water listened to our community reference group and councils to minimise as much as possible construction and environmental impacts, while designing solutions that enhance our community amenity at sites where work needs to be done.”

“Local issues require local solutions, so we needed to make sure the solution is right, and the residents’ groups affected were comfortable with the design.

The design for the proposed solution was developed with the help of a Community Reference Group of 12 representatives from the local area, Waverley and Woollahra Councils, and after listening to almost 300 people who attended ‘pop-up’ community information sessions.

“Local priorities have been identified and we have developed a solution that provides long term benefits – such as the construction of a new toilet block facility in Parsley Bay and contributing to the improvement of the iconic clifftop boardwalk at Diamond Bay.

“While there’s no simple or easy way to retrofit a network nearly 100 years old in some places, we have been able to land a concept design that is supported by the community,” Ms Upton said.

Refreshing the wastewater system in Vaucluse Diamond Bay offers multiple environmental benefits – improving the harbour and coast water quality, protecting the health of marine ecology and community, as well as reducing odour – and brings the level of treatment of the wastewater collected in the catchment into line with the rest of Sydney.

Sydney Water’s Liveable City Solutions General Manager, Paul Plowman, said this project couldn’t have been achieved in this way a few years ago, with recent technology advances allowing the use of trenchless drilling over longer distances.

“Almost all the new infrastructure will be located below ground with anything above ground, such as valves or electrical kiosks, will be minimal and designed to blend as much as possible with the existing environment.” Mr Plowman said.

“Sydney Water will be laying a new 1.8 km, 37.5 cm diameter wastewater pipe using trenchless technology up to 80m below ground, which will greatly minimise construction impacts.

“Given limited open space, geology, as well as the highly sensitive heritage, coastal and harbour iconic locations, the main challenge was always to find suitable sites to locate two underground pumping stations and we are comfortable now with what those sites are.”

Mr Plowman said the proposed solution maximises the use of Sydney Water’s existing network by taking the wastewater from the Vaucluse and Diamond Bay catchments and pumping it via the existing networks at Rose Bay and Dover Heights to Bondi Wastewater Treatment Plant.

“When the work at Diamond Bay is finished, we will contribute to Waverley Council’s improvement plans to restore and improve the beautiful boardwalk at Diamond Bay,” he said.

The proposed solution and environmental assessments go on public display in March 2020. Sydney Water will seek formal submissions from the community and will respond to these before finalising the solution and environmental assessments. The construction expected to start in the latter half of 2020.

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