Stormwater Canal Naturalisation in Sydney – Contamination Management

Sydney Water and other government bodies are currently undertaking naturalisation of concrete lined stormwater canals by replacing the bland concrete with river banks of rocks and native trees, which provides more ecological habitat and increase surrounding property value. The project goal is to create a natural environment that encourages native animals, especially birds, to live and nest.

This work is also being undertaken in various Council projects around Sydney and other capital cities in Australia.

While the naturalisation of concrete stormwater canals has great potential for creating native animal habitat, the projects expose some of the contamination and industrial history of Sydney. Several projects are underway.

The Cook’s River naturalisation process transformed 1.1km of degraded concrete stormwater canal lining into a dual purpose wetland habitat and natural filter with sandstone and native plants reinforcing the edges of the canal.

iEnvi has recently discovered that NSW EPA has a new policy as a result in treating  concrete lined stormwater canals as natural waterways (in terms of contamination exposure risk) in case they become naturalised in the future. This includes concrete stormwater canals linked to groundwater contaminated sites.

The transformation projects open pathways from groundwater more directly to natural ecosystems, and also during construction managing contaminated soils, and preventing contamination from the soil to the new creeks is a real challenge.

iEnvi’s Director Michael Nicholls says “The issue is uncertainty of how to manage contamination associated with these projects.  Several Councils and industry have asked iEnvi for advice, and it often involves sampling, risk evaluation and environmental management plans – however there may be novel remediation measures to be implemented, that must be affordable.”

Active groundwater remediation projects may be set at targets that are associated with environmental harm associated with an evaluation of risk to the nearest ecological receptors (which may be far downgradient from where the project site is in relation to the stormwater canal). This new policy resets the remediation goal posts and introduces uncertainty into many of the Council’s, business and property owners.

Many remediation projects may be at approaching completion, however, these new policies are difficult to risk assess in terms of risks to ecological receptors and ANZECC freshwater ecosystem screening levels for contaminants.  The new policy and transformation projects require a balance of discussion with regulators on practical approaches, evaluation of risks, and early scenario and end point evaluation.

iEnvi develops commercially and environmentally viable solutions for contaminated sites. An example is the remediation of a coatings manufacturer site in Sydney which adjoins one of the many Sydney Water concrete lined stormwater canals.

If you are a Council, Property Owner or Business and would like advice on your project or how contamination might be managed strategically with this policy and transformation projects, contact us on [email protected] or 13000 43684 (13000 iEnvi).







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