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Customer: Watercare, New Zealand Contract: Construct Location: Queen Street, Auckland   |
Fast Facts:
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We have developed an innovative hybrid of Direct Pipe® and pipe jacking to install a new 1220mm OD diameter wastewater pipeline beneath Queens Street, Auckland, New Zealand.
The hybrid method will be used to install a new 600-metre-long wastewater pipeline for Watercare and lead contractor Fulton Hogan. It’s cost-efficient and reduces the site footprint as much as possible, which is critical for infrastructure projects being built downtown.
We will use a new 1200 mm diameter Herrenknecht Direct Pipe® Pipe micro-tunnel boring machine (mTBM) and slurry system to deliver this unique tunnelling method. The mTBM can fit into an 11m long by 5m wide shaft, which requires much less space than the traditional 28 metres for a traditional Direct Pipe® system.
The key benefit of this method is that the tunnelling can be completed with only three small shafts, reducing disruption in this busy central city location.
Glass Reinforced Plastic (GRP) pipes are being on this project as they are durable, designed specifically for wastewater and can withstand the high pressures required for pipejacking. The GRP pipes are also very resistant to corrosion, which is important for the longevity of wastewater services. Being able to use GRP to pipe jack makes it an ideal, practical, and cost-efficient alternative ‘single pipe’ solution.
Traditional tunnelling uses a two-pipe system; reinforced concrete jacking pipes create the tunnel, and a smaller diameter service pipeline or liner suitable to carry the wastewater is installed inside and grouted into place.
Scope
The project, led by main contractor Fulton Hogan, will be completed in two stages. The first stage, which began late last year, is underway to construct he shafts for tunnelling. MCD will deliver the tunnelling scope, which is planned to commence mid-year.
The new mTBM will install a 580 m long wastewater pipe up to 14 m underneath Queen Street from a shaft at the corner of Queen Street and Mayoral Drive. A second shaft for a manhole will be excavated at the corner of Wellesley St East and Queen St, and it will also be used to service the mTBM head.
The third shaft, where the mTBM will break through and be extracted, will be built at the corner of Victoria St East and Queen St. This shaft will also be used to connect the new pipeline to the existing Ōrākei main sewer.
The new pipe will capture wastewater flows from the city and connect to the existing Ōrākei main sewer. Stage Two of the project includes relining the existing Ōrākei sewer.
This work will improve the resilience of the wastewater network, allow for future population growth, and reduce wastewater overflows, for a cleaner Waitematā Harbour. It is part of a $13.8b infrastructure programme Watercare is delivering over the next 10 years.
Caption: The original tunnellers: workers in an Auckland Metropolitan Drainage Board sewerage tunnel at Ōrākei, Auckland, in 1913. Credit: National Library of New Zealand.
