Cross-harbour water pipeline investigated

What lies beneath the surface of Wellington Harbour comes under the spotlight this week, as part of a feasibility study for an emergency water supply pipeline across the harbour.

During the week 7 to 11 April (weather permitting) the survey ship “MV Guru” is checking the proposed pipe route, between Seaview and Wellington for a range of factors that could affect the difficulty and cost of laying a pipeline – such as any obstructions on the sea floor or beneath it and the nature and depth of sea floor sediments.

A cross-harbour pipeline would avoid crossing the Wellington Fault and could supply water either from Waterloo or Wainuiomata Treatment Plants into Wellington city, in the event that the normal supply is disrupted by a major natural disaster, such as a large earthquake.

Currently the pipes that supply Wellington city’s water cross the Wellington Fault at several locations. Water supply would be severely disrupted if there was significant movement of the fault and could take a number of weeks to reinstate these pipelines if damaged. The Regional Council is looking at several options for addressing this problem and the cross-harbour pipeline is one of these.

If the cross-harbour pipeline is considered viable by the Regional Council, it will then be evaluated in conjunction with the other proposed resilience projects under consideration, including a new reservoir between Wellington and Porirua. The preferred resilience projects will be consulted on through the council’s 2015-25 Long-Term Plan process.

“Preparing for natural disasters in New Zealand has been raised to another level in recent years, and we’re part of that” said Chris Laidlow, Greater Wellington Regional Council Water Supply General Manager.

“Recent work by GNS has helped to identify how much water will be needed after an emergency before normal supply is resumed. While we’ve done quite a bit over the last 20 years to reduce the time the bulk mains will be down in the event of a break, it’s important to explore all options that will improve further the resilience of the bulk water network.”

The “Guru” is being leased by Diving and Salvage NZ who will undertake the testing in conjunction with Ocean and Coastal Engineering Ltd from Christchurch and Marine GeoSolutions Pty Ltd from Western Australia. MWH Ltd are the consultants managing the project on behalf of GWRC.

ENDS

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