Land Stability

dirt SG04029Earthquake Update

Prestons suffered no liquefaction or lateral spreading or any other seismically associated hazards during the entire earthquake series.

The site has a low susceptibility to earthquake damage because of the presence of dense dune deposits.

Dune sands on the Prestons development are dense and thus less susceptible to liquefaction than fluvial deposits around rivers and streams.

 

JanKupec-Prestons240

Dr Jan Kupec, technical director for
Aurecon New Zealand Ltd.

Geotechnical Update

Extensive ground tests have been undertaken by Aurecon New Zealand Ltd across the subdivision and the majority of the land is TC1 with some small, localised areas being TC2.

It has been proposed that as a part of the bulk earthworks and construction works for the first stage of the development ground improvement work will be undertaken to the isolated areas of TC2 land.

The aim of this work was to improve the future ground performance to the level of TC1. Ground improvement comprises ground densification with a large compactor. This was subject to stringent quality assurance and control testing to confirm that the ground improvement to TC1 has been achieved.

Aurecon identified some small areas of thin peat layers through their investigations and these were removed. 

The result of the testing was provided as part of the subdivision certification submitted for approval to the Christchurch City Council.

Prestons suffered no liquefaction or lateral spreading or any other seismically associated hazards during the entire earthquake series.