Update from Roger Sutton, Chief Executive: 2 April 2012

Release Date: 02 April 2012

Mr Roger Sutton. The latest land decision, zoning red 251 properties in the Avon Loop, Richmond South and Linwood, was also one of the most complicated.

While the announcement will have been welcomed by some residents and not by others, it has provided all with certainty and the ability to move on with their lives.

These rezonings are among the last of 10,000 properties initially zoned orange, and have been the most difficult to make.

It’s important, however, such decisions are well-informed and robust, and CERA and others have worked hard to get the detailed information necessary to make them.

The properties in question along the Avon River face complex geotechnical issues and the land has been severely affected by horizontal land movement, known as lateral spread. A possible remedial option of a large-scale underground retaining wall down one side of the river to protect these properties was investigated. This was one of the reasons the land decision took the time it did.

Ultimately it was determined the work required would be expensive – and the total expense uncertain. The best location for the wall meant several houses would have had to be demolished anyway to allow it to be built. It was also probable other, already-damaged houses would be further weakened by potentially severe vibration involved in such a project. That’s to say nothing of the considerable disruption to residents for a significant period of time – as long as 18 months or more – while work was completed. In the end, this remedial option just did not stack up.

We need to be clear; red zoning is about damage to land. Some houses in red zones may not be substantially damaged, or have no visible damage at all, but the land is too damaged for them to remain. There’s a risk of serious harm to such houses in any future earthquakes. CERA is looking into the possibility of relocating relatively undamaged red zone houses in cases where Government offers are accepted.

At CERA we’re very aware the recent decision leaves 401 Southshore properties as the last orange zone. I can understand the frustration of home-owners involved, after a series of land decisions have been made in other areas, leaving this long band of land – along the lower western side of the sand-spit - without similar certainty. We’re absolutely committed to getting this certainty.

West Southshore faces land drop, lateral spread, and probable change to the estuary bed which could have long-term implications for residents. Southshore’s proximity to the sea means there’s little surface crust. As a result the land is softer and deeper piles or stronger horizontal foundations may be needed.

The area also has a potential remediation option of an underground wall along the edge of the estuary. Most geotechnical works are now done, but investigations into remediation and rebuild options, including reviewing cost estimates, are ongoing.

As always, however, there’s no waiting around once all the information is in. Nothing is as urgent for us as this rezoning decision and an announcement will be made as soon as possible.

Roger Sutton
Chief Executive
Canterbury Earthquake Recovery Authority