Water, Waterways  |  Yesterday

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A one-year trial to help stop zinc runoff getting into waterways is underway as part of Christchurch City Council’s commitment to improve urban stormwater quality.

The trial, which utilises technology developed by University of Canterbury engineers, involves three Council-owned buildings all located on Banks Peninsula. The sites were selected by the Smart Christchurch team in collaboration with the Three Waters team.

“Seventeen Storminator units have been installed at the Diamond Harbour Library/Hall, a ranger’s shed in the Akaroa Works Yard, and an Akaroa Wastewater Treatment Plant storage shed. The units help reduce contamination from roof runoff by stopping heavy metals get into our waterways,” says Smart Christchurch Manager Grace de Leon.

“All three sites have zinc used as a protective coating on their corrugated iron roofing and will be monitored to check the water discharge quality improves by using the units.”

Zinc is widely used as a protective coating on many residential and utility buildings across Banks Peninsula – unpainted galvanised roofs or coatings in poor condition – contribute the major source of zinc contamination in stormwater runoff. The Diamond Harbour Library/Hall discharges runoff to the stormwater network, while the two Akaroa facilities discharge water directly to the sea. 

Ms de Leon says heavy metals like zinc can pose risks to aquatic life and the health of ecosystems.

“The trial will help us find an affordable and practical way to reduce heavy metal pollution. Removing these harmful metals from stormwater is vital to protecting aquatic life that rely on healthy waterways in our region.”

The technology is also available to private building owners wishing to improve run off from zinc or copper roofs.

The Council will review the results at the end of the trial to determine whether the technology could be used across other facilities to improve stormwater runoff on a larger scale.