The upgrade to meet consent conditions started last month.
Back in October, there was a problem with the Balclutha oxidation pond not processing wastewater efficiently, resulting in elevated odour levels, the Clutha District Council confirmed.
This resulted in the Dunedin City Council accepting a small amount of wastewater for treatment and the subject was raised by Cr Mandy Mayhem at an infrastructure services committee meeting last week.
Asked for more information, a Clutha District Council spokeswoman said restrictions were needed at the site from October 12 to 20.
"Despite actions taken by Clutha District Council to address the issue, such as adding lime to the treatment process, installing aeration equipment and seeding the pond with healthy wastewater transferred from another plant in the district, the continued disposal of waste was not allowing the pond to recover", she said.
There was an agreement to allow sewage to be taken by tanker to Dunedin while some waste — such as oil, grease and industrial wastes — were excluded.
"The pond recovered in a relatively short period of time", the Clutha council spokeswoman said.
The council reimbursed contractors for additional kilometres travelled, amounting to just more than $2500.
A city council spokesman said initial indications were 850cum of material might need to be disposed of, but it turned out the amount was 30cum from October 17 to 20.
The cost to the city council was about $1000, which was recovered.
"There were no issues accommodating this small increase in volume."
The Clutha District Council has historically had some problems with its sewerage systems.
It was fined almost $490,000 in 2020 for failures in managing its wastewater treatment plants and contractor City Care was fined $120,000 last year for its contribution to the failure.
