Winmalee Wastewater System Improvement Program

The Winmalee Wastewater System Improvement Project aims to ensure the system continues to operate efficiently and safely.

About the problem

The Blue Mountains Sewer Tunnel is an important part of the wastewater network in the Blue Mountains. It is 39 km long, and transports wastewater from North Katoomba and other towns in the mountains to Winmalee Wastewater Treatment Plant.

There are sections of the tunnel that are joined by vertical shafts so that it can follow the steep contours of the land. These are called drop shafts.

During heavy rain, stormwater enters the wastewater system, increasing the flows in the system by up to 15 times. Two drop shafts at Lugano Court and Lawson Road in Springwood are currently significantly undersized. It is thought that, over time, the pressure on the drop shafts during wet weather will increase the risk of the drop shafts failing.

Ways to solve the problem

Sydney Water has identified three options to solve this problem. All of the options involve releasing some of the dilute wastewater from the system during very heavy rain to relieve pressure on the drop shafts.

The options are:

• Bednal Road emergency relief structure (ERS): releasing into Springwood Creek
• Lawson Road ERS: releasing into an unnamed creek that flows into Fitzgeralds Creek
• Winmalee Wastewater Treatment Plant bypass: releasing into an unnamed creek that flows into the Nepean River.

To know more about the project and the options, read our project summary booklet and fact sheets.

• Winmalee Wastewater System Improvement Project - summary booklet (PDF - 1857KB)
• Option 1: Bednal Road ERS fact sheet (PDF - 2870KB)
• Option 2: Lawson Road ERS fact sheet (PDF - 3575KB)
• Option 3: Winmalee Wastewater Treatment Plant bypass fact sheet (PDF - 3826KB)

Other options considered

When selecting these options for the project, Sydney Water explored the following options, and found that they are not feasible.

• Stopping stormwater entering the wastewater system.
• Lining the Blue Mountains Sewer Tunnel.
• Building a tank or dam to temporarily store the wastewater.
• Upgrading the Winmalee Wastewater Treatment Plant to treat extra flows.

To know more about why these options are not feasible, read our fact sheets on options considered.

• Fact sheet on options considered for the project - August 2011 (PDF - 1004KB)

Environmental considerations

In early to mid-2011, Sydney Water engaged specialists to study water quality, aquatic ecology, Aboriginal heritage, hydrology and erosion, and plants and wildlife at each of the option sites. These reports help us to understand the environment at each of the proposed sites. The key findings from each of these reports can be found in the fact sheets below.

• Hydrology and erosion fact sheet (PDF - 106KB)
• Water quality and aquatic ecology fact sheet (PDF - 111KB)
• Plants and wildlife fact sheet (PDF - 107KB)

Our work with the community

Between May and September 2011, Sydney Water consulted the community and other stakeholders about the project and options.

Eighty interested stakeholders and members of the community completed feedback forms to let us know their views on the options.

Sydney Water hosted an information session for the local community and doorknocked properties near the option sites.

Sydney Water also formed a Community Working Group for this project. The group represented a broad range of local interests and included property owners and residents, government stakeholders, and representatives from council, local environment and community groups.

The group participated in three workshops in August 2011 to provide feedback about the values and preferences of the wider community.

Deciding on an option

Sydney Water is still considering all options for the project and has not yet made a decision on a preferred approach.

This is a very important project for the local area and Sydney Water, and we want to make sure we make an informed decision on a preferred approach.

To achieve this, Sydney Water decided more information was needed on:

• the structural integrity of the drop shafts and the risk of them failing
• the potential for erosion at the sites for Options 2 and 3.

These studies will be ongoing over the coming months.

We will share the results of the studies with you when they are finished.

Sydney Water will not study Option 1 any further at this stage. This is because Springwood Creek flows into a declared Wild River, and the creek passes through a Greater Blue Mountains World Heritage Listed Area.

Next steps

When making a decision about a preferred approach for the project, Sydney Water will consider community and stakeholder feedback, and potential environmental impacts, cost and other factors.

We should have more information on the project in mid-2012 and we will continue to keep you up to date with our progress.

Before Sydney Water can commit to build any of the options, we will do an environmental impact assessment. Sydney Water will consult you as part of this process.