Kapiti Regional Councillor Nigel Wilson, chairs the committee overseeing water supply for the Greater Wellington region.
Wellington Regional Council is to look at the feasibility of building an emergency water reservoir on the outskirts of Porirua to help resupply residents more quickly after a big earthquake.
Councillors today approved a feasibility study for a possible 500 million-litre reservoir at the 100-hectare Landcorp site near Takapu Road. They also approved negotiations for an option to buy the land if the study found the site to be viable and the project to be cost-effective.
The regional council has put a preliminary estimate of $19 million on excavating and lining the 15-metre-deep reservoir, which would cover 10 hectares and be engineered to withstand a severe earthquake. It would require an earth embankment on only one side, across a gully in otherwise generally flat ground.
The reservoir's capacity would be sufficient to supply Porirua and Wellington City for about 100 days at emergency levels of consumption while repairs to pipes and other infrastructure were carried out. However, some of the water would also be needed for release into pipes to find leaks and test repairs.
Chair Fran Wilde said pursuing the reservoir option was an integral part of the regional council's long-term commitment to earthquake-strengthening infrastructure and making preparations to restore services as quickly as possible.
"During the past 20 years we have spent more than $20 million on quake-strengthening work, and this year's budget includes an allocation of $5.4 million for such work.
"We're taking seriously our commitment to getting the Wellington region prepared for a big shake."
She said the pipeline from the main Te Marua water treatment plant to Porirua and Wellington would be seriously damaged because it crossed the Wellington Fault three times, and repairs could take many weeks to complete.
"By locating a reservoir in this hilltop position, we can rely on gravity to supply Porirua, Wellington and, if necessary, the Hutt Valley without needing power."