Sydney Water

Refresh Woolloomooloo: Sustainable Urban Renewal


Stormwater / wastewater assets

Contract Type

ECI, Design and Construction

Year of Completion




Revitalising Woolloomooloo’s Waterways

Sydney Water’s Refresh Woolloomooloo project blends heritage preservation with modern infrastructure solutions, enriching community life and environmental stewardship.

Project Overview

Diona undertook the challenging task of retrofitting 4.8 kilometres of wastewater pipes in Woolloomooloo and Darlinghurst for Sydney Water. This project aimed to separate the existing combined stormwater / wastewater system to minimise pollution in Woolloomooloo Bay, preserve local ecological communities, and maintain the health of the surrounding residential properties and businesses. The complexity of working within one of Australia’s oldest and most culturally sensitive precincts required innovative solutions and sensitive stakeholder management.

Project Need

The Woolloomooloo area’s stormwater/wastewater system, consisting of seven interceptors, faced capacity issues during wet weather, leading to wastewater discharge into Woolloomooloo Bay. This project was essential for separating the stormwater and wastewater systems to protect the bay’s ecological health and ensure the longevity of infrastructure amidst the area’s historical and heritage significance.

Project Solution

The solution involved detailed planning and execution to retrofit the wastewater system without disrupting the area’s dense residential and commercial fabric. Heritage preservation was paramount. The project team navigated the complexities of working near heritage buildings and a convict-built brick pipe, an oviform, dating back to the 1820s. The project successfully laid 5km of new wastewater and stormwater pipes, built 95 new maintenance holes, and engaged with over 30,000 community stakeholders, demonstrating Diona’s capability in managing technically challenging and community-sensitive projects.

Value Add | Benefit
Community Engagement and Heritage Conservation

Diona’s efforts in managing communications with over 30,000 stakeholders and preserving historical finds underline the project’s commitment to community well-being and heritage conservation.

Innovative Noise Management

The use of specialist equipment and acoustic barriers, along with scheduling works around local school exams and a newborn’s sleep schedule, showcased Diona’s dedication to minimising community disruption.

Technical Excellence in Heritage Areas

Successfully separating the stormwater and wastewater systems in a heritage-protected area highlights Diona’s expertise in delivering complex infrastructure projects while preserving cultural heritage.

ESG Alignment

Enhancing ecological health and water quality by improving water sanitation and minimising pollution in Woolloomooloo Bay, supporting sustainable land use and biodiversity conservation.

Ensuring community well-being through minimal disruption during construction, preserving cultural heritage, and fostering sustainable urban development in densely populated areas.

The project contributes to improving water quality and minimising pollution in Woolloomooloo Bay by separating the stormwater and wastewater systems.

By ensuring minimal disruption in a densely populated area and preserving the ecological and cultural heritage of the precinct, the project supports sustainable urban development and enhances community well-being.

The project’s efforts to reduce wastewater discharge into the bay aid in preserving local ecosystems and biodiversity, aligning with the goal of sustainable land use and protection of life on land.

Industry Awards

Winner: Wastewater Project of the Year

“This was an extremely high-impact project as a result of the densely populated location, affecting more than 30,000 customers in the Woolloomooloo, Potts Point and Darlinghurst areas. The location challenges led the team to adopt advanced technologies like prefabricated manholes, that reduced installation times from 21 days to 3-5 days. State-of-the-art trenchless construction techniques such as bed bores, stitch boring and micro tunnelling were deployed, reducing noise impacts and minimising the impact on the environment.

The improved system now captures and transfers wet weather wastewater overflows in the Woolloomooloo catchment into the Bondi treatment plant. It has also eliminated wafted odours during the dry weather, which were a main cause of complaint for the surrounding community. The new separated system ameliorates the liveability of the area, minimises the contamination of the Sydney Harbour and bay, enhances its water quality and improves marine life.”

  • Finalist: Infrastructure (Construction Phase) Project category
  • Finalist: Environment category