15 Mar 2018

Work will soon begin on boosting storm water storage in Hendersons Basin to reduce the flood risk along the Heathcote River.

The land drainage facility in Halswell – in farmland bounded by Sparks Road, Hendersons Road, Cashmere Road and Sutherlands Road – will also improve water quality by treating storm water runoff in the area.

The Eastman is part of new $40 million storm water facilities.

Stage one of the Eastman Wetlands is part of the city's new $40 million storm water facilities.

The additional storage is part of the new $40 million Eastman/Sutherlands/Hoon Hay storm water facilities.

It is one of four major storage projects the Christchurch City Council is building to store floodwaters during a storm, and then gradually release the water after levels have dropped downstream.

Under the Land Drainage Recovery Programme, these basins will help protect flood-prone homes in Heathcote. The total additional storage added will be able to hold 800,000 cubic metres of water.

The four basins should reduce the risk of above-floor flooding for more than 100 Heathcote properties in a one-in-50-year storm.

“Storm water runoff contains pollutants – such as heavy metal and sediment – that can harm the city’s aquatic life,” Council Land Drainage Manager Keith Davison says.

“However, the runoff can be targeted with treatment basins and wetlands, cutting the impact of urban and rural development on water quality.”

The new facility will also treat the increased sediment coming down from the Port Hills into Hoon Hay Valley Stream. There is less vegetation on the hills following last year’s fires, worsening the sediment problem.

Work on dredging a 700-metre stretch of the Heathcote River between Radley Street and the Woolston Cut is also being brought forward to help reduce the flood risk.