A sewage leak in New Zealand’s capital Wellington has been described by local authorities as an “environmental disaster,” with repairs to the city’s wastewater treatment plant expected to take months.
Residents of Wellington have been advised not to enter the water, collect seafood or even walk their dogs on local beaches.
On Wednesday, the lower floors of the Moa Point wastewater treatment plant were completely flooded after heavy rain caused sewage to back up into the 1.8km outfall pipe that normally discharges treated wastewater into Cook Strait, according to Wellington Water.
As a result, untreated sewage began flowing through a shorter five-metre outfall pipe into the waters off Wellington’s south coast.
Wellington Water chief executive Pat Dougherty said around 70 million litres of raw wastewater had leaked into surrounding waters, New Zealand’s 1News reported.
Dougherty said he was “at a loss” to explain why the outfall pipe failed, adding: “The outfall pipeline has more capacity than the treatment plant itself, it’s designed to be the one thing that works whatever happens.”
Wellington mayor Andrew Little on Thursday described the leak as a “catastrophic failure,” saying: “This is a sewage plant processing the sewage for a big city, and it has completely failed, it just completely stopped.”
In a Facebook update on Friday morning, Wellington Water said it had partially restored operation of the long outfall pipe and the screening system, which removes sanitary pads and wet wipes from wastewater.
The company said it was currently able to pump “900 litres per second of wastewater through the long outfall pipe,” noting: “This is most of the wastewater during an average day, but during peak flows throughout the day we will need to use the short outfall pipe.”
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“Discharging screened wastewater out to sea via the 1.8km long outfall pipe allows for greater dilution of the wastewater in the Cook Strait,” the company said, adding: “This reduces the amount of untreated wastewater flowing around the coastline – however the risk to public health still remains.”
It continued: “We will continue to work throughout the weekend to increase the volume of flow through the long outfall pipe as much as possible, to reduce the use of the short outfall pipe. The situation is complex, and at this stage we are unable to provide a timeframe of when this may be.”
Local residents, including owners of dive schools operating nearby, have raised concerns about the impact of the spill.
Dave Drane, owner of Dive Wellington, told the Otago Daily Times: “It’s going to affect us financially in lots of ways. Even the bad advertising from it, where people think: ‘Well, I’m not going to learn to dive in Wellington,’ but also the bookings that we’ll have to cancel.” He said up to 30 students had already been forced to cancel planned dives in the nearby reserve.
One local resident, Angus, expressed hesitation to surf, telling RNZ: “I didn’t want to go there because it looked like I don’t know… toilet paper or jellyfish, so I was like I don’t really want to go in on either of those.”
Commenting on the leak, New Zealand’s department of conservation said it was “extremely concerned,” with its principal marine science adviser Shane Geange saying: “Raw sewage and wastewater entering a marine environment poses an immediate and severe threat to a wide range of ecological functions and species, but I think the primary concern is around the public health concern which Greater Wellington health authorities are actively managing.”
Geange added that the department was working with local authorities to determine how far the sewage has spread.