‘Farterton’ returns: Carterton’s wastewater treatment plants cause bad smell

Carterton District Council has received service requests about the stench after the failure of three aerators at its wastewater treatment plant. Photo / Wairarapa Times-Age

The “Farterton” saga has reared its head again this week, as an unpleasant stench wafts from Carterton’s wastewater treatment plant.

The term was coined in 2021 when residents at the south end of the town complained of a “week-long” stink emanating from the Dalefield Rd plant.

Carterton District Council [CDC] confirmed yesterday it had received service requests regarding the odour after the concurrent failure of three aerators at its plant.

A spokesperson confirmed the odour was coming from the wastewater treatment plant, not the newly commissioned reservoirs.

“Pond 3 is usually the most reliable, but the concurrent failure of three separate aerators is unexpected,” CDC said.

“Our three ponds rely on a fine balance of biochemistry to stop bad odours from travelling most of the time in waste stabilisation ponds.

“There are two distinct layers within ponds, anaerobic [no oxygen] bottom layer and aerobic [top layer].

The lower layer is made of solids that accumulate over time in the bottom of each pond, where they are slowly consumed by microbes.

“These microbes produce bad odours which are consumed as they pass through the aerobic layer.

“However, if that balance is removed by weather changes, chemicals, or high loads in the network, it will impact the ponds, upsetting the aerobic layer and allowing the bad odours to get to the surface.”

The council said it was looking for replacement aerators.

“One is at the end of its life, and our team has been working on a replacement for the last month to get a replacement.

“A second aerator has a fault, and we are waiting for an electrician to check it.

“The final aerator stopped this week. We are investigating today [Friday] as we suspect it is blocked with rags.”

CDC is dosing twice a day in the interim to increase the oxygen level and divert more of the flow to Pond 1.

The council asked residents to “remember the three Ps”: “If it’s not pee, paper, or poo, it doesn’t go down the loo”.

One of the issues CDC is looking to address in its Long-Term Plan [LTP] is the outdated wastewater treatment plant equipment, which was last upgraded more than 60 years ago.

The potential proposed upgrades will address foul air treatment.

The draft LTP will be available to the public from March 22 as part of the Ordinary Council Meeting agenda for March 27.

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