Ponds unplugged for Sydney’s $8bil Green Square

By Paul Hemsley

City of Sydney Lord Mayor Clover Moore has moved to stop floods from pouring into the massive new Green Square precinct and surrounding areas by installing an huge underground culvert drain pipe network designed to divert waters away from areas that have traditionally been rendered a swampland.

The new waterworks are a significant development for the City’s ambitions to rejuvenate the former industrial area because the issue of flooding in some streets threatened dampen Ms Moore’s $8 billion grand vision of eco-friendly precinct urban renewal comprising of new businesses, apartment blocks, public transport upgrades and sustainability.

As land availability pressures increase, the development and redevelopment of historically flood-prone inner city areas is requiring more ambitions public works to mitigate the potential damage to property and infrastructure and an occurrence known as “ponding” where water is trapped in certain low points because of the topography of the catchment area.

In 2011, the City of Sydney and Randwick City Council identified these low-points in their Green Square West Kensington (GSWK) study, which found that the ponding problems have frequently manifested in Milroy Avenue, McDougall Street, Lenthall Street underpass below South Dowling Street, South Dowling Street, Lachlan Street and in Botany Road.

As a result, the City has announced that it will execute its Green Square West Kensington (GSWK) floodplain strategy and management plan, which will involve the creation of a large underground drainage culvert spanning 2.3 km through the Green Square town centre from Link Road in Zetland to the Alexandra Canal.

The proposed drainage culvert will stretch from Link Road in Zetland to the Alexandra Canal, draining floodwaters away from homes, businesses and roads in and around Joynton Avenue, Lachlan Street, South Dowling Street and Botany Road.

According to the City of Sydney, the proposed drainage work valued at $80 million will take up to three years to complete and will be co-funded by Sydney Water.

As the GSWK floodplain risk management plan is the first plan of its kind to be submitted to the council, the City has committed $1.8 million to city-wide Floodplain Risk Management Studies, including $600,000 in grants from the New South Wales government and the federal government.

The City has also allocated $57 million for essential infrastructure drainage improvements in Green Square and $59 million over the next 10 years for drainage capacity works across Sydney.

Not only has the City committed to draining away the pond waters, it has also announced that its plan will include so-called “stormwater water quality improvement devices”, such as “pollutant traps” and “rain gardens” to meet the objectives of its Decentralised Water Master Plan.

This plan aims to reduce storm water pollutants entering waterways, which often include cigarette butts, cans, food wrappers, plastic bags, leaves, fertilisers, oil or detergents.

As a plan that drains flood water away from the flood-prone area, the City of Sydney has pressed the drainage plan as an initiative that is meant to combat the effects of climate change, which has alarmed governments to the potential risks to infrastructure that isn’t resistant to flooding.

It’s a problem that has troubled Queensland in recent years because its own series of deluges that has resulted in the state government funding councils to upgrade their infrastructure to become more resistant to floods – which is likely to cover the insurance risks that Queensland councils potentially face if the flooding seasons continue.

Ms Moore said with the effects of climate change taking hold, it is likely that more extreme weather events will put pressure on Sydney’s infrastructure.

“We are taking the first ever city-wide look at the drainage issues and flood risks that exist in Sydney. The Green Square West Kensington catchment is one of the lowest lying areas of our city, and subject to water ponding and flooding,” Ms Moore said.

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