6. Improve overflows

Overview

Sydney’s sewer system is over 100 years old, and built for a smaller city. So, when it rains, stormwater can flow into the sewer system, causing it to overflow into our creeks and rivers. Understanding where, when and how this happens and putting measures in place to stop it are an essential part of making our river swimmable again.

Recommendation

Improve water quality outcomes through targeted wet weather overflow management, focused on those overflows impacting existing and proposed swimming sites.

Timeframe

Ongoing.

Lead Agency

NSW Environment Protection Authority and Sydney Water.

Current measure

Overflows in the Parramatta River catchment meet all EPA licensing conditions.

Status Update

Sydney Water has been investing in a program of ‘source control works’ to reduce the impact of wet weather overflows from the wastewater network on the Parramatta River. This forms part of a $183 million package of work over four years across five catchments in Greater Sydney. The works have been agreed with the NSW EPA and are regulated under Sydney Water’s risk-based licence. 

The wastewater fix program aims to achieve reduction in overflow volume and frequency from high-risk overflow points.

Works for Parramatta River are being delivered across the upper and mid catchment and are split into three main components: 

Stage 1 (Inflow Reduction) – Asset repairs/replacement of emergency relief structures and manholes to prevent stormwater entering the wastewater network.

• Status: Planning 100% complete, construction 80% complete.
• Only minor updates are required to refine decision making tools. At completion, upgrades to more than 200 emergency relief structures and 600 manholes will have been delivered across the upper and mid Parramatta River catchment.

Stage 2 (Infiltration Reduction) – inspection and relining of pipes to prevent stormwater infiltration.

• Status: Planning 100% complete, construction 60% complete.
• Works in the upper catchment will be finalised by October 2022 with approximately 4km of pipe relined. An additional 13km of pipe is expected to be relined in the mid catchment by August 2023.

Stage 3 (Private Property Works) – identification and rectification of illegal sewer connections on private properties. Sydney Water is installing sensors across the wastewater network to enable the benefits of this program of work to be assessed. It is expected that performance will be able to be fully reported by April 2024.

• Status: Planning 60% complete, construction not yet commenced.
• All stage 3 works are expected to be completed by October 2023. Works will commence in the upper catchment initially, followed by the mid catchment. Overall, inspections are planned for approximately 12,300 private properties, 900 commercial properties, 58 schools, 7 hospitals and 7 industrial properties.

Progress Timeline

Useful Links

Review of Sydney Water Corporation’s sewage treatment Environment Protection Licences.