Auckland Council Healthy Waters Strategy head Andrew Chin speaks about the College Hill sinkhole and the process to fix it. Video / NZ Herald
The pipe that led to a sinkhole opening up in central Auckland was considered an “emergency” by Auckland Council months before it opened up, official papers show.
Officers were aware in early April the pipe had suffered an “acute failure” and needed fixing “as soon as possible”, but it wasn’tuntil after the sinkhole appeared that contractors were on site to replace it.
On July 24, the 108-year-old stormwater pipe cracked, leading groundwater to seep in during this year’s heavy rain, taking fill with it, and leading it to collapse.
Documents released to the Herald under the Official Information Act show several plans were talked about to replace the 108-year brick pipe down College Hil - a busy route into the city from the inner western suburbs, and a route to the Northern Motorway.
Contractors at the site of the sinkhole in central Auckland after it appeared on July 24. Photo / Dean Purcell
The pipe was on the council’s renewals programme and regularly surveyed for replacement, but the matter became urgent after a sinkhole occurred on the same pipe a bit further down College Hill near the corner of Victoria Park during the January 27 floods. This sinkhole, on a busy intersection, was quickly filled in.
The council’s Healthy Waters stormwater division sought to declare the pipe an “emergency works” in early April after a section of College Hill was found to be slumping and covered at the time with a steel plate.
“We anticipate that works will start in the next few weeks,” a civil engineering firm told Auckland Transport on April 17.
A day later on April 18, a council communications officer said “construction is likely to start in the next four to six weeks”.
By late May, the start date for construction was pushed back to July 1, and timed during the school holidays when there is less traffic on the roads.
In mid-June, a mailout about the works was underway for local residents and businesses, but the tender process dragged on to July 17 when Kerry Drainage was awarded the contract.
The documents show it was the police, whose Auckland headquarters are just off College Hill, and Auckland Transport who initiated a callout on July 21 to some “developments” with the failing pipe.
Work unde rway for the temporary fix on the sinkhole on College Hill. Photo / Michael Craig
A Fulton Hogan contractor visited College Hill to find “significant damage”, including rocks and debris scattered along the road, and Auckland Transport and Downers Traffic reported the slumping in the road as “unstable”.
Two days later, the road collapsed and formed a large sinkhole, with one AT officer saying he believed the same pipe had failed 15 to 20 years earlier.
Asked why work did not start earlier for what was considered an emergency, Healthy Waters head of design and delivery Chris Stumbles today said the pipe was identified as a renewal project in February 2022 with a timeline for construction to begin within two years.
“The safety of the public and other users of this busy location has been at the forefront of the council’s approach, and the project priority was escalated after the effects of the major weather events this year.
“A fit-for-purpose solution is being delivered alongside significant cost savings and this project is on track to be completed by December 2023,” Stumbles said.
When the sinkhole appeared, Healthy Waters’ strategy manager Andrew Chin apologised for what happened.
“We would have much preferred the project to happen in a much more planned and systematic way. Unfortunately, that hasn’t been the case and we are playing catch-up now,” Chin said.
The new pipe is being progressively installed in stages to minimise traffic disruption on College Hill.
