Link Alliance site engineer Abhi Amin: “There was a map alright, but what it was telling us and what we actually discovered were two very different things”
Tackling the unexpected below Auckland’s streets
Just a few metres below ground lies a ‘spider’s web’ of utilities stretching right across Auckland that is essential to keep a contemporary city working – and some of them are in the way of the City Rail Link.
The underground web is ‘woven’ together by modern-day arteries and veins – tens of thousands of metres of pipes, tubes, wires and ducting that carry gas, water, electricity, the internet and sewage and waste that a functioning Auckland needs. Essential as all these underground utilities are, many need to be relocated for a project like City Rail Link (CRL).
“Relocating utilities is our first cab off the rank if you like – our first big task, an absolute priority, before the heavy construction machinery can move in,” says Dale Burtenshaw, deputy project director for the Link Alliance, which is delivering the main stations and tunnels contract for City Rail Link Ltd.
Utilities diversions for CRL’s Aotea Station in central Auckland started last September and will continue for some time yet. “While we construct on a huge scale, we’re reducing the risk of cutting an internet connection to a block of apartments, losing power to cafés and offices, or flooding roads and footpaths during a storm,” Mr Burtenshaw says.
“Relocation is technical and challenging work, demanding a lot of planning and integration. At times we are working with utilities up to eight metres deep, and often with half a dozen different utilities services/providers, which all require coordination with each other.”
Relocating utilities at Aotea has uncovered some buried gems from Auckland’s past – including a disused well, a boiler, and bricks from a demolished hall – but not all the surprises found below ground are an historical bonus.
While most of the utilities ‘web’ is well mapped and contractors know exactly where to dig, that is not always the case, as Link Alliance site engineer Abhi Amin discovered. “It’s a reminder for any construction site – to always remember to expect the unexpected! There was a map alright, but what it was telling us and what we actually discovered were two very different things,” Mr Amin says.
The Link Alliance team working on the construction of the new Aotea Station found an old boiler half-buried below the surface
The map related to a pipe of natural gas running at right-angles from a main under Albert Street to the Crowne Plaza hotel and a neighbouring office block.
The pipe was located in the ceiling of a service lane running below Albert Street.
“That pipe wasn’t in our scope – not buried below the service lane where we thought it would be. Its location was exactly where we didn’t want it to be – in the ceiling right in the way of our planned piling for a D-wall (diaphragm wall) to support the new station,” he adds. “Shifting it quickly became a critical part of the construction programme.”
Safely relocating the gas in a trench 70 m long underground was a complex operation that called on Mr Amin’s skills as an engineer – and as a communicator. “The job didn’t look hard on paper, but everything about it was complex. There were a lot of consents needed, a clear route had to be found around other utilities for the new pipe, and a lot of people needed to be kept informed – the hotel, the offices next door, and all the people who relied on the service lane for access and parking,” he notes.
Good communication with the neighbours is paying dividends for the Link Alliance. “During the gas main relocation project, their team kept us well informed every step of the way, and ensured their plans took into account our needs,” says Tony Rose, director of Colwall Property Investment which owns the Crowne Plaza and Atrium complex. “This enabled us to continue our business operations with minimal impact.”
Dale Burtenshaw says promoting clear communications is an important commitment for the Link Alliance. “Disruption – whether it’s a temporary footpath or an intersection like Wellesley Street in the city centre closed to traffic – is unavoidable for New Zealand’s largest transport infrastructure project. But providing good and timely information to our immediate neighbours and to the wider city 24/7 is a priceless objective to allow us to get the job done smoothly and as quickly as possible – that’s a commitment to everyone that will not change.”
Mr Burtenshaw says the work of Abhi Amin’s team tackling the unexpected ticked a lot of boxes. “The gas line was safely relocated and clearly mapped, people received timely information about the work, we’ve had positive feedback, the way is now clear to start D-wall construction for Aotea – a job well done,” Mr Burtenshaw says.