Airing Out Carterton’s Wastewater To Avoid Stench

Monday, 29 April 2024, 4:03 pm
Article: Emily Ireland - Local Democracy Reporter

A breath of fresh air has arrived in Carterton, thanks to a new aerator at the council’s wastewater treatment plant.

All three of the council’s aerators were out of action last month, causing an unpleasant stench.

One aerator had an electrical fault, which was repaired, one had a mechanical fault which was fixed ahead of this permanent replacement, and one had been clogged by rags and items flushed into the wastewater system.

It marked the latest part of the long-running “Farterton” saga, a term coined in 2021 when residents at the south end of the town complained of a “weeklong” stink emanating from the Dalefield Rd plant.

Carterton District Council [CDC] has now installed an Aeris Global “aerdisc aerator” in Pond 3 of its wastewater treatment plant.

The aerator replaces the old paddle type, with improved oxygen transfer and water movement for the same energy usage.

CDC had trialled this new type of aerator which was developed three years ago.

A council spokesperson said the timing of the installation was good “as the old aerator was frequently breaking down and the seasonal change can be problematic for pond systems”.

“Temperature swings can disrupt the process causing odours to be released,” they said.

“Cold, still evenings can create a thermal layer that traps air close to the ground.

“The effect is observed during winter when the mist forms close to the ground which disappears when the sun rises and the temperature goes up.

“So the new, more efficient aerator will help to keep the ponds mixed well and stop any major temperature fluctuations.”

One of the issues CDC is looking to address in its Long-Term Plan [LTP] is the outdated equipment at its wastewater treatment plant.

The plan, which is currently out for consultation, highlighted a “significant risk” to wastewater treatment in the district due to its aged wastewater treatment plant.

Carterton’s wastewater is processed at two different sites – the Dalefield Rd wastewater treatment plant which has been in service since 1940, and the newly constructed wastewater treatment reservoirs on Daleton Farm which reached practical completion in 2023.

CDC wants to make necessary upgrades to the facilities where the wastewater enters the Dalefield Rd wastewater treatment plant at a cost of $6 million.

The other options being consulted on are to “do nothing”, which carries significant risks, and a $12m option which includes three wastewater components: grit and fat removal, a new primary sedimentation tank, and foul air treatment.

This is a vital step to remove grease, oil, and fat from the wastewater so it can be treated.

Submissions on CDC’s LTP consultation close on May 5.

All information and supporting documents are available online here.

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