Porirua, Wellington to get more secure water
29 August 2005
Porirua, Wellington to get more secure water supply
Works to make the main water supply to Porirua and Wellington’s northern suburbs more secure from earthquake damage started today.
A section of Greater Wellington’s Te Marua to Wellington water main near the junction of State Highways 2 and 58 at Haywards Hill is being realigned, to avoid a hillside that is vulnerable to landslides. About a third of the region’s reticulated water supply flows through the main at this point, which passes only a few hundred metres from the Wellington Fault. Strong shaking is likely in this area during a sizeable earthquake.
The new pipeline route provides two advantages. It runs through more stable ground, which lessens the probability of pipe rupture and extensive damage. If the pipeline did fail, the more gentle terrain of the new route would make access much easier, meaning faster repair.
John Duggan, Greater Wellington’s Engineering Consultancy Group Projects Manager, said the work, once completed, would help to minimise disruption to residents after an earthquake.
“Reinstating a water supply to local cities could take several weeks after a movement along the Wellington Fault. The realignment is expected to cut repair time for this section of the main by up to twelve days, which would certainly be worthwhile to the region’s recovery effort.”
The pipeline route currently follows a steep gully up the northern edge of Transpower’s Haywards Substation site, from SH2 to SH58. The realignment will take the pipeline further south along the edge of SH2, up McDougall Grove, across the southern edge of Transpower’s boundary, then north up SH58 to rejoin the existing main, at the intersection with Old Haywards Road.
There will be minor disruption to the traffic flows on SH2 and McDougall Grove until mid October, but these are not expected to cause significant delays. The works on SH58, scheduled for December and January, will require the northbound overtaking lane to be closed and speed restrictions to be applied. Motorists are asked to take care around these road-works.
About 1200 metres of new steel water main will be laid as part of the contract, with the total project expected to cost in the region of $2.3 million. The realignment work is scheduled to be completed in late March 2006.
This upgrade to water supply security is part of a steady “toughening” of the Wellington metropolitan area’s wholesale and urban water supply infrastructure, spanning more than a decade. Local water supply agencies are continuing to work together with the Region’s Civil Defence and Emergency Management Group to improve key infrastructure and better prepare for the aftermath of a major earthquake.
Rex Kirton, Chairman of Greater Wellington’s Utility Services Committee, said that while local water suppliers were preparing for a damaging earthquake, water users also needed to be ready.
“We’re well aware that our water network is vulnerable to earthquake damage and we’re taking sensible steps to address that. Unfortunately we can’t remove the risk entirely, so we need everyone to be ready by storing an emergency supply of water, for at least three days, at home.”
A fact sheet about storing emergency water is available from www.gw.govt.nz (Hazards and Emergency Management) or by contacting Greater Wellington Regional Council.