New Zealand: New Liquefaction Management Areas affecting most Christchurch landowners

Resource Management

In the last two months the City Council has begun placing a new section on the Land Information Memorandum (LIM) they issue, stating:

"Property or property within the Christchurch District Plan Liquefaction Management Area overlay."

A LIM is a Council document with information about a property typically used by a purchaser of a house or section.

The Council's decision to place this section in a LIM has come about as a result of a decision by the Independent Hearings Panel regarding the new Christchurch District Plan. The Panel's decision is that most properties in Christchurch should be included in a Liquefaction Management Area (LMA) in the District Plan.

The properties in Christchurch now subject to a LMA classification are all properties east of a line running from the Waimakariri River to approximately Nunweek Park, Burnside High School, Greers Road, Main South Road to the foot of the Port Hills. The LMA includes Sumner, Redcliffs and Lyttelton but excludes the CBD.

The practical effect of a property being in the LMA is that the Council is saying that the soils in the LMA generally have a greater potential for liquefaction and that more detailed site investigations may be required to determine the appropriateness of a site for subdivision or building. However, being in the LMA only triggers the need for a resource consent in limited situations. So for the purpose of the District Plan the need for further geotechnical investigation will occur only where a resource consent is otherwise required for the proposed development.

The area within the LMA has been based on geotechnical information based on whether liquefaction is more likely to occur than not. Within the LMA, liquefaction risk and appropriate mitigation will be assessed on a site specific basis using best practice geotechnical and engineering methods to determine the performance of infrastructure and buildings.

It is intended that the Council will create guidance documents to detail the types of investigations required to determine the suitability of a site for development. It will also create performance standards so readers would know exactly what is expected in terms of performance of the ground, or the design of the structure, to withstand liquefaction.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.