A large contracting company has been found guilty over the appalling state of Clutha’s wastewater treatment plants.

Judge Brian Dwyer found City Care Ltd guilty in the Dunedin District Court on six charges related to discharges or permitting of discharges of contaminants from wastewater treatment plants at Stirling, Owaka, Kaka Point, Tapanui and Lawrence in late 2019.

The Christchurch City Council-owned company failed to prevent essentially untreated wastewater, including human sewage, from escaping the facilities, Judge Dwyer said.

The Three Waters contractor responsible for maintaining the five Clutha wastewater treatment plants left them surrounded by thigh-high grass and weeds, encumbered by sludge, scum and algae and not up to the task for five months after taking over their maintenance.

The company had five months to clean up operations at the treatment plants but failed to do so. Photo / Richard Davison, Otago Daily Times, File

Their filtration systems were known to be “knackered”, yet nothing was done.

However, in his 105-page decision released this week Judge Dwyer said he found the level of blame for City Care’s offending to be “at a considerably lower level” than the Clutha District Council, which he fined $500,000 for the same matter more than two years ago.

City Care only took over the contract for maintaining the facilities in July 2019.

When it did, the company’s wastewater treatment operator found the filtration system to be unfit on his first site visits and reported the situation to his manager numerous times, Judge Dwyer said.

He said “a reasonably prudent contractor” in City Care’s position would have brought the need for immediate replacement of the failing components of the treatment plants to the district council’s attention.

Officers found 'a strong sulphurous and ammonia-like odour ... 'pungent, incredible and really overpowering'. Photo / Supplied, File

Additionally, staff should have had a copy of the resource consents and operations and maintenance manuals for the treatment plants they were supposed to be taking care of, he said.

The company had five months to clean up the operations at the treatment plants and despite the company’s wastewater treatment operator identifying the “primary problem bedevilling operation” of the treatment plants immediately, nothing was done, he said.

Mayor Bryan Cadogan hopes the most 'challenging' times for wastewater treatment are over for the district. Photo / Richard Davison, File

While the burden of proof in the case did not sit with City Care, the company said it could not have made a difference to the discharges from the failing plants.

The sites were non-compliant from the outset of its contract and could not be brought into compliance, let alone improved, without considerable capital work, City Care argued.

The judge found instead that City Care failed to bring the urgent need for replacement of the treatment plants’ BioFiltro beds to the immediate attention of the council.

It failed to adequately instruct its staff about the requirements of discharge permit conditions. It did not provide operations and maintenance manuals, or provide any adequate checking system to ensure compliance with those documents.

Additionally, the company allowed operation of the plants to continue on a limited or “hands off” maintenance basis for a period of five months after taking over their management.

The failures allowed sewage, including human waste, to enter the environment around the treatment plants.

Sentencing would take place later this year, Judge Dwyer said.

Last month, the council announced its water operations and maintenance contract with the company would end by mutual agreement on June 30, a year earlier than the five years originally signed for.

Yesterday, Clutha Mayor Bryan Cadogan said he believed it was important to look ahead and continue the work being done to improve the district’s wastewater treatment operations.

“I am pleased that this challenging time has now come to a phase where we can all move forward.”

- Hamish MacLean, ODT