Media Release 26 August 2005

Christchurch sewer overflows into Heathcote River

An interruption in electricity powering alarms and pumps at a sewerage station in Opawa has resulted in an overflow into the Heathcote River.

Mike Bourke, who manages water and waste operations and maintenance for the Christchurch City Council, says the loss of power inside the station on Locarno Street disabled the three-stage system designed to avoid spills.

The outage was discovered at about 10.30am. It is thought the wastewater had been running into the river for about an hour.

Normally, monitors at the station would recognise a rise in flows and switch on additional pumps to push the wastewater further down the network until a normal operating level is reached. If the level continued to rise, the control system would trigger an alarm and staff monitoring the city’s network would boost the pumping rate. The final alert stage is an alarm which signals that there is wastewater overflowing from the station into the waterway.

Mr Bourke believes the electricity was disconnected within the pump station to allow the replacement of electricity metres. It meant all alarms and pumps were unable to operate.

The overflow is engineered so that, in the main, only surface wastewater escapes while heavier material remains in the sewerage.

Environment Canterbury has been informed and signs have been put up along the Heathcote warning of the spill.

“We are very disappointed this has happened and we’ll look again at the operational instructions given to anyone doing electrical work at our stations,” Mr Bourke says.

ENDS

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