Central Otago District Council (CODC) has confirmed today that repairs have been completed at Alexandra Wastewater Treatment Plant, following the installation of a new gearbox handmade in Auckland.

The treatment plant was constructed in 1988 and recent gearbox failure brought forward works on the plant that is set to also process Clyde’s wastewater within the next three years.

On Tuesday 13 October 2020, a mechanical fault saw a small amount of partially treated wastewater released in to the Mata-au Clutha River. 

The release was within current Government standards for safe swimming water, however on becoming aware of the fault Council sought advice from consulting engineers. 

A temporary fix was put into place within a few hours to stop any further overflow discharging river. 

Within three days an innovative geobag system was installed to allow continued operation of the treatment plant at a reduced capacity whilst a new gearbox was ordered. 

The new gear box was installed on Thursday 29 October and the plant was refilled on Thursday night to achieve full capacity by this Sunday 1 November.

Whilst works were being undertaken septic tank trucks were used to transport 320,000 litres of partially treated effluent to the recently upgraded Cromwell Wastewater Treatment Plant in order to reduce pressure on the Alexandra plant.

Central Otago District Council Water Services Manager Peter Greenwood said Council’s Water Services Team had been working closely with Otago Regional Council staff to ensure daily monitoring was undertaken on both the plant and the river.  

“We are confident that at no stage were there any health risks to our local community and we are very pleased with the quality of the new gearbox that has been installed.” 

Councillor Nigel McKinlay, Three Waters and Waste Portfolio Chair, said “whilst this event is a rare occurrence, it reflects the age of Alexandra’s Treatment Plant and why it has been prioritised by Council to be upgraded, particularly as it will also be processing Clyde’s wastewater within the next three years.”

The estimated cost to get the plant back into full operation is expected to be between $400k to $500k

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