Project FAQs

We investigated several options to increase the capacity of the existing sewer system to meet future population requirements. These options included:

• increasing the size of the pipe in the current Belconnen trunk sewer 
• duplicating the current Belconnen trunk sewer
• installing a new overflow tank
• alternative locations for new pipes
• installation of pinch vales across the network to provide additional storage. 

Each option was assessed against a range of criteria including environmental impact, people and places, public health, work safety and cost. Detailed assessment of these options resulted in our preferred and proposed option of duplicating the current trunk sewer. This option was chosen based on long term performance, cost, risk, impacts to environment and community during construction and operation.

OCU’s are a common part of most sewer networks and are used as a mechanical filter to absorb gases such as hydrogen sulphide, which is a common source of odours from sewerage systems. These gases are removed using activated carbon which is typically replaced annually depending on usage. 

Each OCU unit consists of a carbon scrubber and two large fans which draw air from the sewer main into the filters before expelling the treated air through a ventshaft.  Each OCU is equipped with a smart electronic monitoring system, which continually checks air quality, filter condition and system performance is operating correctly. If a fault is registered, Icon Water is notified in real time and can respond quickly.

As OCUs are designed to treat odours, they do not smell. An Air Quality Impact Assessment has been prepared as part of the statutory approval process.

An Air Quality Impact Assessment has been prepared for each OCU.
The assessment set out to:
 

• consider construction phase impacts which primarily relate to dust and vehicle emissions. Impacts will be very minor due to the small construction footprint with appropriate site environmental controls to be implemented
• analyse the outcomes of the cumulative air dispersion modelling assessment to determine whether odour and H2S emissions from all four OCUs meet the applicable assessment criteria at the nearest identified sensitive receivers
• where appropriate, make recommendations for additional mitigation measures to achieve compliance with applicable assessment criteria. 

Based on the air dispersion modelling assessment, it was concluded that air emissions (odour and H2S) from each of the OCU units are not expected to impact on the surrounding area during continuous operation. 

To view the Air Quality Impact Assessments in full, a copy can be found on the ACT Government EPSDD website, click here. 

• Tree assessment and removal 
Icon Water is committed to minimising any impacts on our local flora and fauna. Due to the necessity for the sewer to be installed in public land and away from private property, trees identified within the construction corridor were assessed and removed. From the initial design, the project has managed to reduce the number of trees to be removed by approximately 20%.

• Wildlife care 
Prior to the removal of any trees, a detailed survey identified trees  along the construction corridor showing habitat features such as hollows, nests, or scratch marks was performed. These trees were specially managed by an onsite ecologist team, ensuring any wildlife discovered during the clearing works was protected and relocated. 

• Rehabilitation and replanting plan 
We followed a rehabilitation and replanting plan endorsed by Transport Canberra and City Services (TCCS). Cleared areas were replanted and landscaped progressively throughout construction, with most of the vegetation comprising of native indigenous species. 

• Repurposing of cleared trees 
All trees removed during the clearing works were mulched and repurposed for use in the surrounding parks and reserves. Trees were not permitted to be collected for private use due to safety reasons. A select number of trees were donated to local organisations for animal care and habitats.

There are several reasons why the new sewer is not proposed to be constructed on the southern side of Ginninderra Drive. These reasons include:  

• location of existing high voltage electricity infrastructure on the southern side of Ginninderra drive and required setbacks from these services and surrounding residences
• challenging topography, which would greatly increase the cost of construction
• a pipe bridge of greater length (than the current option) being required at the western end of the pipe alignment. 

It is important to note that the location of the existing electricity infrastructure and stipulated set back distances prevented the new sewer from being constructed on the southern side of Ginninderra Drive. Even setting this reason aside, the challenging topography and longer length of sewer bridge would significantly increase the cost of the project.

We encourage anyone noticing sewer odour to talk to us. We have a robust process for investigating and addressing odour complaints. Odour can be due to a number is things, such as issues with internal plumbing or within our network. The presence of odour can indicate a fault, or blockage which we needs to be investigated. 

The wetlands project was managed by the ACT Government. It is part of the ACT Healthy Waterways initiative to improve the quality of water flowing into our lakes and waterways and downstream into the Murrumbidgee River system and the wider Murray-Darling Basin. 
 
The Belconnen trunk sewer upgrade is a separate project managed by Icon Water. The trunk sewer upgrade will increase the capacity of our sewerage network to transport more waste to our sewage treatment plant. The increased capacity will also reduce the risk of any wastewater overflow into Ginninderra Creek during extreme wet weather events.  
 
The additional trunk sewer connects into the existing wastewater network near the wetland, on a neighbouring site.

As part of the consultation process between November 2018 and June 2019, several government agencies were consulted including TCCS and EPSDD. Contact was also made with MLAs from Yerrabi and Ginninderra via email to advise of the project and to support responses to enquiries that may be received from constituents.

Local residents were notified of the project and opportunities to provide feedback through the following means:

• November 2018. Community mailbox drop to ~8500 households (all homes within 1km of project sites, including the pipeline corridor and OCU sites).
• January 2019. Community mailbox drop to ~5000 households (all homes within 750m of project sites).
• March 2019. Community mailbox drop to ~3200 households (all homes within 500m of each project site).
• June 2019. Community mailbox drop to ~3200 households (all homes within 500m of each project site).

All community notices relating to the project are available on our Belconnen Trunk Sewer upgrade projects page.

In addition to notices direct to local residents, Icon Water presented at two Belconnen Community Council meetings, held five community drop-in sessions at Melba Copland College, hosted a site walk and open day that included three of the four OCU sites, site signage was installed at several sites including the OCU locations and regular email updates were provided to members of the public and stakeholders who registered an interest in the projects. Icon Water has also engaged with several local community led environmental groups such as the Ginninderra Catchment Group, Umbagong Landcare Group and Friends of the Grasslands in relation to the project.

Due to the position of the original playground conflicting with the wastewater pipeline construction corridor, the old playground was removed and closed to the public to support construction. A new playground has been rebuilt in the same location and is open to the public and features a swing set, slide, animal springers, fire pole, arc bridge, pommel walk and rope scramble.

We would like to thank the local community for their patience during this work.

Our charges are regulated by the Independent Competition and Regulatory Commission (ICRC), which sets the prices for water and sewerage in the ACT. Every five years we prepare a submission detailing what the cost of operations will be for the next five years. The ICRC then sets the prices that Icon Water will charge to cover those costs. We have an obligation to deliver value to the community, and to ensure that our operations are prudent and efficient. In the last regulatory submission, we included the price of the Belconnen trunk sewer upgrade projects in our calculations, and the cost of this project has already been accounted for in the current water and sewerage pricing.

To find out more, please see our factsheet on infrastructure investments and customer pricing.

The Belconnen trunk sewer upgrade project aims to increase the capacity of the sewer network in response to the demand of Canberra’s growing population. By planning and upgrading our sewer network now, we will significantly reduce the likelihood of sewage overflows due insufficient pipe capacity. We have worked closely with the EPA to ensure the project complies with all health measures, and in addition have completed air quality impact assessments and odour dispersion modelling as part of the statutory approval process. The assessments have concluded the sewer and OCUs are not expected to impact on the surrounding area during continuous operation.

As Canberra grows, the demand on our water and wastewater infrastructure increases too. When the Belconnen trunk sewer was completed in 1968 the population of Canberra was approximately 60,000 and whilst future population growth was planned for, it is not efficient to build for what you may not need. So demand is constantly reassessed as the needs of the community change. With population growth in the area, additional capacity is now needed. Increasing the capacity of the sewer also ensures that any risk of overflow into Ginninderra Creek is significantly reduced providing additional protection to the environment and this important waterway.

The new sewer pipe was laid using mainly open trenching techniques, with some sections requiring micro-tunnelling due to environmental sensitivities and desire to avoid traffic impact on a major road (Kingsford Smith Drive). A pipe bridge was built to support the pipeline crossing Ginninderra Creek.

The new length of sewer pipe has been connected into existing wastewater infrastructure (i.e. Latham trunk sewer) at Tillyard drive which flows south to the existing Belconnen Trunk Sewer and on to Lower Molonglo Water Quality Control Centre.

We have returned the area to as close as possible to its original condition. The majority of the construction is located below ground and constructed within open grassed areas. Restoration along the pipeline corridor occurred progressively and was completed in early 2024  

As part of our landscaping plans, areas of high environmental sensitivity including Natural Temperate Grasslands (NTG), are being restored and protected. These NTG areas will continue to be monitored and maintained for until early 2026. 

As part of the initial stages of this project, Icon Water developed several options and undertook a series of feasibility studies to investigate the best location for this project to meet the project needs and objectives. Four key options were considered and assessed against factors including impact on neighbourhoods, community value, safety, environment, financial implications, and potential design effectiveness. 

Following consideration of the options, Icon Water identified the proposed project as the preferred option.

A pipeline bridge is a structure that supports a pipeline across a low area such as a gully or creek. In the case of a trunk sewer pipeline, the bridge is necessary to maintain the correct level of the sewer and to ensure appropriate flow is maintained. The pipeline bridge will support the pipeline above any areas where flooding may occur. The proposed location of Project 1 will mean that a pipeline bridge will be needed to cross Ginninderra Creek.

The pipe was laid at a depth of 2.5m to 6m. The depth varied along the alignment in order to ensure appropriate fall of the gravity fed pipe, and due to the overland topography.