Liquefaction risk to be assessed

New sites identified by the Marlborough District Council as potential suburbs for Blenheim have yet to be assessed for risk of liquefaction after an earthquake.

Council executive project manager Jamie Lyall said yesterday he hoped consultants Opus would be able to do geotechnical testing on the land this year. The testing equipment was in demand after the Christchurch quakes.

However, the council was not "working blind" over land identification. It had used a model of the makeup of the land in Marlborough compiled by the crown research institute Geological and Nuclear Sciences (GNS), he said. This had been built from information gathered from analysis of the 5000-odd wells dug in the region.

At the time the wells were put down to extract water, an inventory of the soil had been taken, Mr Lyall said.

"All that data of 5000 wells has been put into a model, which provides the council with very good data on the underlying strata beneath the plains in Blenheim," he said.

That model had been used by the council to work out areas of land that might be "more receptive to development".

However, the later geotechnical testing could still show that some of the land proposed for new houses and suburbs might end up being at risk of liquefaction too and so not suitable for development.

"But we are trying to reduce the odds of this happening."

Mr Lyall said the GNS model was interesting, showing the different makeup of areas of land.

"Blenheim has quite a lot of swamp."

Marlborough District Council on Monday released a map identifying potential areas for new houses, tagging five sites around the north, west and southern edges of Springlands. Three of the sites surround the Westwood development, which includes Bunnings and Pak'n Save. Another is north of that, bordering Old Renwick Rd and Thomsons Ford Rd, and the fifth site is off Battys Rd.

Letters were sent to about 100 landowners this week saying the council would be interested in rezoning their land for housing. Landowners of neighbouring land could contact the council if they wanted their land to be considered, too.

Population projections suggest another 2500 houses will be needed in Blenheim over the next 20 years.

This latest move is part of a review of the South Marlborough Urban Growth Strategy, after land to the north and east of Blenheim initially earmarked for housing was ruled out in May when engineers said the sites would suffer liquefaction in an earthquake.

Mr Lyall said the council wanted to talk to people about the new areas that had been identified.

Council staff will be available to meet any interested parties to discuss these issues on August 28 and 29, he said.

Appointments could be made by contacting the council.

The council intends to complete consultation with landowners by early September, issuing a draft report reviewing the Southern Marlborough Urban Growth report by mid-September.

That would be open to public feedback, with a final report due by mid-October.

The Marlborough Express