After a series of costly clean-up operations this year, the Dunedin City Council is threatening to prosecute anyone caught dumping oil into the city's wastewater system.
Council staff yesterday confirmed they were attempting to trace the source after a series of incidents in which petroleum products - including engine oils and diesel - were dumped illegally into the city's sewerage system.
The Green Island wastewater treatment plant has been repeatedly contaminated, disrupting its biological processes, and just one of the clean-up operations had cost ratepayers more than $9500.
Council senior education and compliance officer Frank van Betuw urged those responsible to stop, saying they risked prosecution and a fine of up to $200,000 if found to have breached the trade waste bylaw.
''The DCC will also recover any related clean-up costs from offenders,'' he said.
Council staff were testing the oil to trace those responsible, and had identified ''potential sources'' in Green Island, Brighton and Fairfield, he said.
Council staff could offer advice on how to dispose of the materials, and anyone witnessing the illegal dumping of substances into the sewerage system was urged to contact the council.
