Just as the Canterbury Earthquake Recovery Authority was disbanded after five years of painstaking reconstruction, so too will SCIRT be dismantled and ‘normality’, of a sort, be restored. CHRIS WEBB spoke to executive general manager, Ian Campbell, as one of the final chapters in the city’s long road to resurrection draws to a close.
HIMSELF A CANTABRIAN born in Darfield, Ian Campbell holds a civil engineering degree from the University of Canterbury.
Seconded to SCIRT from McConnell Dowell in 2011, he knows only too well the devastation wrought on the South Island’s most populous city by the earthquakes of 2010 and 2011, the latter claiming 185 lives. Now 18 months into the job as general manager of SCIRT, the body charged with rebuilding Christchurch’s horizontal infrastructure at a final cost of some $2.2 billion, he will see the team’s work completed by the end of 2016, finally returning day-to-day work to more traditional stakeholders, including the City Council and NZTA, next March.
It has been a long journey since the earthquakes, but SCIRT has won significant support from the city’s 370,000 dwellers. In a recent survey, Ian points out, 83 percent were satisfied with progress. Which is no small deal in a “post-critical” environment, he adds.
With more than 130 major projects to juggle, and spending peaking at $50 million a week, everyday life has had to go on, so far as it can, requiring disruption to major services to be kept to an absolute minimum. It’s meant close collaboration with the Council, Transport Agency, Christchurch Transport Operations Centre and a host of other agencies.
The earthquakes and ensuing liquefaction destroyed or severely damaged more than a third of the underground infrastructure. SCIRT was charged with the task of restoring functionality to affected infrastructure to a state where, as Ian puts it, “the average level of service throughout the network should be like it was before the earthquakes”.
That means designing to a 70 to 100 year lifetime using new and modern technologies. New materials, more capable of withstanding any future ground trauma have been used, and gravity wastewater systems, typically buried at five to six metres depth, replaced by shallower vacuum systems to aid quicker repair, should the need arise.
Some of these measures received a thorough natural testing almost five years to the day after the February 2011 Canterbury earthquake, when a further shocker measuring 5.7 in magnitude shook the region.
“There was no significant damage,” says Ian.
The level of damage from the earlier Canterbury earthquakes was significant, and work to repair the infrastructure has been ongoing ever since. This huge task resulted in up to 150 work sites operating around the city at any one time under ‘live’ conditions, in which freshwater, stormwater and wastewater services have had to be kept operational while being fixed.
Now more than halfway through the final year of its five-year programme to repair and rebuild Christchurch’s earthquake-damaged roads, underground pipe networks, bridges and retaining walls, SCIRT is completing several months-long bridge repairs. Some of the notable engineering challenges have been in rehabilitating decades-old bridge structures built to earlier standards, and strengthening them to comply with modern building codes. Including the SCIRT budget, the government has committed more than $13 billion to rebuilding the greater Christchurch area.
This year they have included restoration of the iconic war memorial, the Triumphal Arch, standing on the Bridge of Remembrance, which Ian describes as “an extremely technically complex project”. The arch and the bridge have been strengthened to withstand a one in 2500-year earthquake event.
“That reflects the heritage significance of the structures.”
Designers came up with a solution permitting the arch to ‘rock’ in an earthquake, requiring significant steelwork reinforcing to the arch foundations. Heavy steel boxes were manufactured and inserted inside cavities within the two arch limestone columns.
The SCIRT team is now 92 percent through its programme and on track for construction completion in December. The bulk of it – about 80 percent – is focused on the city’s underground pipe networks. The majority of the pipe repair work has been to the wastewater network. The earthquakes cracked wastewater pipe walls and collapsed others, particularly older earthenware pipes. More than a third of the wastewater network has required some form of repair after the earthquakes.
It has been a mammoth task, replacing more than 560 kilometres of wastewater pipe so far. Some 56 kilometres of stormwater pipe has been repaired or replaced and 97 kilometres of fresh water pipes. “The city’s earthquake-damaged wastewater, stormwater and fresh water infrastructure has been repaired and rebuilt using new and modern technology that gives the city a robust network for the future,” Ian says.
Just on 1.365 million square metres of roads have been repaired to date, representing 87 percent of the roading repairs in the SCIRT programme. In May, SCIRT celebrated the completion of complex repairs to one of the city’s biggest and busiest bridges, the Moorhouse Avenue overbridge, five months ahead of schedule. It was one of more than 120 bridges to be repaired under the programme, leaving only a handful of repairs now to complete, including two heritage structures, the Gloucester Street and Helmores Lane bridges, and Durham Street overbridge. In addition, as Contractor went to press a total of 151 retaining walls had been rebuilt or repaired, many of those in the hill suburbs of Christchurch and on Banks Peninsula.
About a quarter of the city’s wastewater pipes are being repaired with trenchless technologies, such as pipelining, which is saving the city millions of dollars. “A significant number of old and damaged earthenware and other similar types of pipes have been replaced with new more flexible PVC [polyvinyl chloride] and PE [polyethylene] pipes which can flex with ground movement and don’t fracture as easily as the older clay pipes,” says Ian.
The city’s wastewater system comprises an extensive network of underground pipes and pump stations which gather wastewater and transport it to the Bromley treatment plant. The system has been updated with the construction of 37 new wastewater pump stations, large and small, and the installation of another 65 new lift stations, which are small pump stations, to ensure that the system works effectively and can handle future needs as the city evolves and develops. In some areas around large new pump stations the ground has been reinforced with columns made of stones and grout and SCIRT has strengthened the connections of pipes to the pump stations so the pipes are able to flex with the station structure.
SCIRT used horizontal directional drilling (HDD) to install a new 400 millimetre wastewater pipe, some 325 metres in length, under the Avon river. Project engineer, Dan Fryer said the rig was the only one of its kind in New Zealand.
“The technology far exceeds anything currently available here. The HDD method is a cheaper alternative, a faster means of installing pipe and is less disruptive because there is no need for road reinstatement.”
The installed pipe is more resilient to future earthquake damage because the alignment is at an acute angle to the river.
“This means that if the ground liquefies and the banks of the river collapse then the pipe can better withstand the movement.” The pipe became operational in June.
The dissolution of SCIRT at the end of 2016 does not mean work on the city’s infrastructure will stop. The Council is ensuring ongoing work is included in upcoming budgets and maintenance programmes.