Helping to remediate part of Australia’s most well-known rivers
To support the growth of the developing Sydney region in the late 1800s, the Mortlake Gas Works provided essential power services to Sydneysiders for more than 100 years.
When the gas works was officially shut down in 1990, it made way for new residential living in what is now the affluent suburb of Breakfast Point.
Ensuring safe and healthy communities continue to thrive
A legacy impact of the Mortlake Gas Works left large areas of sediments within Kendall Bay with contamination from Tar and Pitch derived hydrocarbons posing potential human health and ecological risk as well as aesthetic impacts.
On behalf of our client, Jemena, our contaminated land management team have been providing technical input into trial and investigation remediation efforts since early 2018. Our initial scope involved providing input during the testing phase and characterising near shore sediments before providing waste classification, validation and controls advice during the trial phase in late 2019.
With remedial works starting in February 2020, we have maintained a full-time on-site presence to help provide input and assistance with remediation and validation techniques and overseeing works in both in-situ stabilisation (ISS) and non-ISS remediation areas. This also included our local ecology experts focusing on the protection of the mangroves running along the southern shoreline of the bay.
Innovation is the key to success
The challenges associated with remediating river-bed contaminants are complex and required an innovative solution not tried before in Australia.
With complexities and potential exposure to impacted sediment occurring during low-tides, our team needed to coordinate works based on tidal cycles in the river to ensure works could be carried out during specific times of the day. Further, we needed to account for wave and tidal action potentially impacting sensitive materials during the remedial works.
With only minimal experience on hand globally, the project team comprising Jemena, the Ventia project team and WSP researched and trialled the best techniques to provide a safe solution for the community and to improve the contamination status of this section of the Parramatta River. The more heavily contaminated materials are being remediated by undertaking in-situ stabilisation (ISS) of the contaminants through direct injection and thus reducing long term leachability of the contaminants. The application of this technique over water is an Australian first and has only been applied internationally on a couple of other occasions on a small scale. Remaining remediation areas are being cleaned up through excavation and replacement with clean material or encapsulation.
WSP is also working closely with Jemena and Ventia to facilitate project continuity during the COVID-19 pandemic while fully meeting both government and company directives.
A solution for greater use
With many industrial factories like the Mortlake Gas Works located along the Parramatta River and other rivers in Australia and around the world, in-situ stabilisation is a great solution to reduce the impact on local community by treating underwater contaminants in place.
As gentrification of former industrial land continues to occur in the region surrounding Kendall Bay, the intent will be that the community will be able to enjoy the flourishing state of local fauna and flora in the Parramatta River once again.
