Plans revealed to raise height of land at Penrith Lakes to mitigate against one-in-500-year flood risk

The potential for a one-in-500-year flood event has prompted a major plan to raise the height of land at Penrith Lakes, but some nearby residents fear the works could exacerbate flood risks.

The potential for a one-in-500-year flood event has prompted a major plan to raise the height of land at Penrith Lakes, but some nearby residents fear the works could exacerbate flood risks by creating a “dam wall” that would loom over homes.

Plans have been revealed to use 22 million tonnes of soil and other material to raise the height of sections of land at Penrith Lakes to create “flood immunity” against the risk of a one-in-500-year flood event.

The Penrith Lakes Development Corporation – which manages the site – has previously had approval to import 13 tonnes of material to raise sections of land at the site.

But the corporation now wants to import an extra 9.7 million tonnes of fill, which it says is needed to raise the height of the eastern section of the lakes by an average of 1.32m to maximum heights of 2.98m.

Plans state the additional material will “support the site’s long-term future”, as well as new housing proposed to be built around the perimeter of the lakes.

An aerial photo of Penrith Lakes.

But some nearby residents fear raising the land could alter the flow of water during extreme flood events by creating a dam that could result in water backing up and potentially overflowing towards homes in Cranebrook.

Multiple government agencies have also requested further information regarding the plans, including the Department of Planning, which wants detailed flood impact assessments on potential flooding impacts.

Concerns over flooding in the area, as pictured here, have prompted the plans.

The Environment Protection Authority has also requested meetings with the Penrith Lakes Development Corporation to discuss the proposed works, noting comprehensive assessments for the site “were conducted a significant time ago”.

A flood impact assessment released as part of the plans indicates raising the height of land at the lakes would not result in a “fundamental change to flooding behaviour” in the area or the wider Nepean River floodplain during flood events.

Plans stated raising the land was designed to “provide sufficient immunity” to protect land at the eastern sections of the lakes areas from flooding during an extreme rainfall event.

Local resident Annette Dwight, in a submission on the plans, said she was concerned about the “negative impact” the huge amount of fill may have on stormwater run-off.

The Department of Planning is considering the proposal.

Submissions have also raised concerns over the amount of trucks required to raise the height of land and the potential for “dangerous dust” to blow towards neighbouring areas during construction periods.

Penrith Council has called for a detailed flood model analysis and impacts on flood evacuation routes.

If the plans are approved, the additional fill material will be sourced from major infrastructure projects including Sydney Metro tunnelling works.

The proposal, which is classified as a state-significant development, has been lodged with the Department of Planning and is currently being considered.

Penrith Lakes Development Corporation was contacted for comment but had not provided a response at the time of publication.