‘We didn’t know how bad the land was’: Historic map shows underground lake near troubled metro sports site
Saturday, 23 September 2023
A key stakeholder in Christchurch’s troubled new metro sports building says he wasn’t aware the soil quality underneath the development was so poor when they committed to the location. CHARLIE GATES reports on how the site has never been on solid ground.
When the 2011 earthquake struck, the old Canterbury Brewery on St Asaph St was flooded with silty water within minutes.
The grey water poured out of the ground, leaving behind great piles of silt once it drained away.
A former employee who worked at the Canterbury Brewery for decades said the liquefaction was everywhere.
“We got a lot of liquefaction,’’ he said.
“It was quite amazing to see it flood the place within minutes
“It was this grey stuff everywhere.”
The distinctive red and black brewhouse sank 15cm and a gap of 10cm opened between the building and a neighbouring office block. Demolition of the whole complex began in 2011 and was completed by 2013.
The former employee, who did not want to be named, said Lion Breweries tested the ground after the earthquakes. They pulled cores from the earth to see what the soil was like deep beneath the site.
“I was there when they tested the ground. It was poo right down to 35 or 40m.
“There wasn’t much dirt there. It was very gravelly.
“It didn’t look too flash to me.”
Lion decided to move operations to Dunedin, ending a history of brewing at the site dating back to the 1850s.
Lion’s former home is now the site for the new metro sports building, which has been under construction since 2019.
The soil beneath the site, which caused so many problems in the quakes, has also complicated an already difficult construction project.
The building, which is officially named Parakiore Recreation and Sport Centre, has been hit by delays and cost rises. It was initially set to be completed in late 2021 and cost $301 million. The budget has now risen to $365m and the completion date has slipped to December 2024.
There were more delays when a section of the site sank by an average of 90cm, requiring the construction of 100 underground columns to stabilise the soil.
They were not the first underground stone columns installed on the site. Before construction began, 7256 of the columns were pushed into the ground to reduce the risk of liquefaction and stabilise the soil. Laid end to end, the one metre thick columns would stretch from Hornby to Ashburton. They weighed a total of 85,000 tonnes.
This underground engineering was needed because of the quality of the ground and also because of the extraordinary load that was going to be placed on the site. The 50m Olympic swimming pool in the facility will be filled with about 2.5 million litres of water. That is a load of 2500 tonnes.
For comparison, a blue whale weighs about 200 tonnes and the Statue of Liberty weighs 150 tonnes. So imagine 12 blue whales flapping about on the site or 16 Statues of Liberty sitting in a pile like firewood.
So, given the problems lurking underground, why was the site chosen for the metro sports building in the first place?
Landscape architect Don Miskell helped choose the site as a leader of the Government’s earthquake recovery blueprint team in 2012. He said they wanted to place the sports centre close to Hagley Park and Christchurch Hospital.
“We thought of sport and recreation as part of health,” he said.
“Also, with a large number of people working at the hospital, we thought they could pop over at lunchtime.
“That was the planning logic.”
He also talked with then Sport Canterbury chief executive Geoff Barry, who was pushing for the building to be close to Hagley Park. At one point, Barry even proposed the facility could be built inside Hagley Park
“They were talking about things like the Weet-Bix TRYathlon. The kids could swim and then run around Hagley Park.”
Barry’s successor, Julyan Falloon, was also involved in the blueprint discussions. He said the sports centre was originally earmarked for the corner of Moorhouse and Fitzgerald avenues, where Red Bus currently stores its vehicles.
“That was right on the edge of the blueprint and the four avenues and ticked a few boxes.”
“But Geoff Barry advocated that it needed to be closer to Hagley Park.”
Miskell said the blueprint team settled for the current site even though they were well aware of its ground quality problems.
“We were certainly aware of the challenges that the site presented from a geotech point of view.
“It didn’t come as a surprise to us when issues have arisen.
“We knew about the high water table and the need for mitigation.”
In 2017, then Ōtākaro chief executive Albert Brantley said the location was “not exactly the best site to build this type of facility on”.
In 2022, new chief executive John Bridgman reiterated the problem.
“With its high water table, this site was always going to be a geographically perfect but geologically tough location.”
And nor should the soft ground have been a surprise. The earliest land survey maps of Canterbury, made in the mid 1800s and known as the Black Maps, show the site has a deep watery history.
The maps reveal that before Christchurch was built, there was a large body of water or wetlands extending from the eastern edge of what is now the metro sports site.
But Miskell said they were reassured those problems could be overcome with underground engineering.
“There were good arguments to accept the challenges of the site. There were geotech issues throughout the city, but they were not insurmountable.”
But Falloon said they were not made aware of the ground problems when they were advocating for the site.
“The problem was we didn’t know how bad the land was in terms of the water table and stabilisation.
“It wasn’t a good site.”
He believed the building would be finished by now if they had stuck with the original site.
“Hindsight is a great thing. The land on that [east] side of town is better.
“Look at the quality of land at Te Kaha [stadium] nearby.
“That is going great guns.”