The cause of a massive fire that burned for almost three weeks at Christchurch’s sewage treatment plant in 2021 has been confirmed.
A fire investigator’s report to the Christchurch City Council’s insurance subcommittee says the blaze was caused by the ignition of flammable material on the roof.
This was blamed on subcontractor staff using an unauthorised heat source during repair work.
Residents were left to live with combined odours from the damaged plant, along with a nearby council-run compost processing facility.
Council chief executive Dawn Baxendale said the investigator’s findings are consistent with a 2022 Fire and Emergency New Zealand report.
Baxendale said the wastewater treatment plant was fully insured, and the council was still working through insurance and legal proceedings.
The council would not disclose how much the claim was worth but said it had spent $23 million since the fire, including the initial response, reconfiguring the plant, removing rotting material from the trickling filters and assessing the damage, RNZ reported.
Earlier this year, the council installed five disc and 11 vertical shaft aerators in the first of the plant's six oxidation ponds to churn more oxygen into the water and improve its biological health, at a cost of $4 million. The smell worsened last month when the disc aerators broke down, but the council said they had now been repaired.
Average hydrogen sulphide levels remained below 0.01 parts per million - well below the 0.03ppm threshold of concern - although odours were still noticeable at times, it said.
- By Geoff Sloan
Public Interest Journalism funded through NZ On Air
- additional reporting RNZ
