Heavy overnight rain has caused a breach in a major Nelson sewerage main, sending diluted, untreated wastewater into local waterways and prompting warnings for people to stay out of the water.
Heavy rainfall overnight Monday (1 June) overwhelmed the Paru Paru Road wastewater system, causing a burst pipe and releasing between 100 and 200 litres per second of diluted, untreated wastewater into Saltwater Creek, the mouth of the Maitai River and Nelson Haven.
“The peak flows overnight overwhelmed the Paru Paru Road wastewater system resulting in a burst pipe and flows of between 100 and 200 litres per second of diluted, untreated wastewater being released into the creek, river and Haven,” Nelson Mayor Nick Smith says.
“Council staff and contractors are working at pace to repair the breach, and we expect to have it fixed within 48 hours. The wastewater is highly diluted from the heavy rain, but it will be unsafe for a number of days to swim, recreate or take shellfish from the Haven.”
Nick says the incident has highlighted a known weak point in the city’s infrastructure during major storm events.
“Nelson’s wastewater system is in much better shape than most cities, but we have identified the vulnerability of the Paru Paru Road system in a storm event and are well advanced in our plans to upgrade the pump station as part of the Bridge to Better project.
“The new pump station will increase the capacity more than fivefold, from 56 litres per second to 320 litres per second, and provides 800,000 litres of storage. This $23 million project is fully budgeted with $10 million of Government support and is due for completion by the end of 2027. We are currently constructively engaged with interested parties on the consenting.”
Minister for Emergency Management and Recovery Mark Mitchell, who travelled to the region as a precaution due to the severe weather warning, has been briefed on the wastewater overflow and visited the site.
“Councils have a done a good job of the emergency management of this severe weather event for the region, of which they have had too much experience in recent years.
“Nelson’s wastewater system is in much better shape due to a long and ongoing history of investment. I have been impressed by the fast response of Nelson City Council and its contractors to this breach. This incident also reinforces the importance of councils investing in improving the resilience of their wastewater networks,” Mark says.
