Auckland sewer sinkhole: Beaches begin to reopen as rāhui over Waitematā starts to lift

Beaches in Auckland are beginning to reopen as a rāhui placed over the Waitematā Harbour a month ago because of a wastewater overflow starts to lift.

Local iwi Ngāti Whātua Ōrākei placed the rāhui over the harbour on September 27 after a sewer collapse opened a 13-metre-deep sinkhole on a private property on St Georges Bay Rd, Parnell, two days earlier.

Deputy Mayor and Ōrākei Ward Councillor Desley Simpson described the sinkhole as “the size of a tennis court” at the time, saying the damage was the result of severe weather and lots of rain.

More than eight million litres of wastewater a day flowed into the harbour since the Herald first reported the collapse.

A temporary bypass to resolve the leak went into operation last Tuesday after a 20-day rush, with Watercare saying these measures would substantially reduce the amount of overflow into the harbour.

Today, Ngāti Whātua Ōrākei Trust chairwoman Marama Royal announced it has lifted the rāhui across the Waitematā Harbour, but it remains in place at Ōkahu Bay, Te Tinana/ Wilsons Beach, Judges Bay, St Marys Bay, and Masefield Beach reserve at Curran St.

A map of the area where a rāhui remains in place.

According to safeswim.org.nz, 14 beaches across Auckland are still unsafe to swim at. They are:

• Chapman Strand
• Herne Bay
• Home Bay
• Judges Bay
• Masefield Beach
• Milford
• Okahu Bay
• Pt Chevalier
• Sentinel Rd Beach
• St Marys Bay
• Taipari Strand
• Te Atatu Beach
• Te Tinana
• Wairau Outlet

Auckland Council said Aucklanders should continue to check the Safeswim website for the most up-to-date information and to make decisions on where it is safe to swim.

“Following rainfall, swimming water conditions can change quickly,” a spokesperson said.

14 beaches across Auckland are still unsafe to swim at. Photo / safeswim.org.nz

Royal said the main purpose of a rāhui was protection and it was important to consider the entire Waitematā Harbour.

“As tangata whenua of central Auckland and upper Waitematā, Ngāti Whātua Ōrākei have a duty as kaitiaki to look after the mauri, or life force, of the Waitematā as well as to keep our communities safe. We will continue to keep the rāhui under review – the health of the Waitematā and of all who enjoy using it are paramount to our iwi,” Royal said.

Deputy Mayor and Ōrākei Ward Councillor Desley Simpson thanked the community for their understanding and support as Watercare fixed the wastewater discharges into the harbour.

“This was a distressing situation with major impacts on recreational users of our Waitematā beaches and waterways, as well as wider impacts for Ngāti Whātua Ōrākei.

Simpson described the sinkhole as “the size of a tennis court” at the time. Photo / Watercare

“I know there have been economic impacts for organisations which run water-based events and activities. I really want to thank Watercare for their efforts to start to fix the Ōrākei Main Sewer, knowing that public health and safety is paramount,” Simpson said.

Watercare’s chief operations officer Mark Bourne said there had been “a monumental effort from our staff, contractors and suppliers to get the bypass planned, the pipes laid, the pump station excavated and concreted, and have six large temporary pumps installed and tested”.

Bourne said a project of this scale would “normally take several months” to complete.

Watercare completed a bypass around the blocked sewer main on Tuesday last week. Photo / Watercare

The temporary pump station installed to divert wastewater can handle 600 litres a second, which should be enough, “sufficient to handle normal flows during dry weather”, Bourne said.

However, he added: “These temporary pumps are more susceptible to blockages than our standard network pumps, so it will be more important than ever for people to only flush the 3Ps - pee, poo and toilet paper. Please don’t flush wet wipes or any other rubbish.

“Just as there was prior to the sinkhole developing, in wet weather, there will still be overflows into the Waitematā Harbour.”

On Tuesday, deputy director-general of New Zealand Food Safety at the Ministry for Primary Industries, Vincent Arbuckle, warned people not gather fish or eat any seafood from contaminated areas for at least 28 days once the sewage has stopped flowing into the harbour.

Contaminated seafood can cause gastroenteritis, which can cause nausea, vomiting and diarrhoea, Arbuckle said.