Wednesday, February 21, 2024

Stopbank work stops as basin work flows

Christchurch City Council has announced the completion of a new 472m-long river stopbank, as work on the first of a series of stormwater basins in the Ōtākaro Avon River Corridor continues to progress.

At approximately three metres high, the long-term stopbank is the first element of a nine-hectare flood management area being constructed beside Anzac Drive and Pages Road.

Christchurch City Council’s Head of Three Waters, Helen Beaumont says the new stopbank along Waitaki St will play a crucial role in the future wetland, and Christchurch’s ability to live with sea-level rise.

“The stop-bank is made from engineered gravel from local quarries, with contractors constructing a half-metre-deep underground raft to provide additional geotechnical strength and stability,” she said.

“After it’s completed by February next year, we propose to remove parts of the old-existing stop-bank near the Ōtākaro Avon River and let that area naturally flood.

“Pending the relevant consents, we will then begin excavating and creating a large stormwater treatment and wetland area between Anzac Drive and the new stop-bank.”

The $12 million Waitaki Street project is expected to take about three years to complete, and, once finished, will treat up to 78% of rain falling on the catchment before it is discharged into the Ōtākaro Avon River.

It is the first of about 17 stormwater projects planned for the OARC over the next 30 years, as the Council brings into effect the Regeneration Plan for the area.

Preliminary designs are also under way for the Bexley estuarine wetland extension (south of Pages Road) and for another flood management wetland between Wainoni Road and Anzac Drive.

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