Report scolds councils over subdivisions
Canterbury councils have been criticised for failing to ensure the risks of building on liquefaction-prone land were investigated before construction began.
More than 6500 properties were written off after the February 22, 2011, earthquake because the land they were on was deemed prone to liquefaction and too damaged to be habitable.
New subdivisions built after the risks had been identified - such as Pacific Park in Bexley and Seafield Lagoon in Brooklands - were hit hard by the September 4 quake. The ground liquefied, badly damaging homes, and land was later red-zoned.
The Canterbury Earthquakes Royal Commission final report released this week found "weaknesses" in the process Environment Canterbury (ECan) and the Christchurch City Council followed when zoning land for redevelopment and approving consents for subdivision.
The process was, however, "sufficient to meet legislative requirements historically applicable".
The weaknesses included a lack of compelling earthquake risk advice before the early to mid-1990s, and a lack of council pressure on developers to investigate the geotechnical risks associated with their plans.
The report said it was incumbent on the city council to consider and manage the earthquake risk involved in any new subdivision or development, regardless of earlier zoning decisions.
"Where appropriate, applicants should have been required to undertake geotechnical investigations or other hazard assessment and if, as a result of those inquiries, risk was found to be present, mitigation actions should have been identified and monitored."
A Government report released last year found about 1200 Christchurch and Kaiapoi sections badly affected by liquefaction had clearly been identified as liquefaction-prone from the early 1990s.
City council resource consents and building policy manager Steve McCarthy said yesterday the approach was "universal" in New Zealand at that time.
"Our city plan placed reliance on building construction standards to manage earthquake risk for foundation design for new developments, rather than on the Resource Management Act (RMA) consenting processes."
A report from resource management consultancy Enfocus to the royal commission said the council's plans appeared to strongly emphasise the risk of earthquakes but this did not translate into demands on developers.
With one exception, ECan also did not push for quake-related conditions on developments, viewing its role as more educational.
The Enfocus report did not solely blame the councils, saying the rules made it unclear how much weight should be given to risk of quakes.
Former National Environment Minister Nick Smith last year blamed "politically correct" conditions in the RMA.
The resulting Resource Management Reform Bill, aimed at giving councils more power over hazard risk, this week passed its first reading in Parliament.
McCarthy said consents for new Christchurch development, where zoning changed from rural to residential, now required a geotechnical report which certified the land was the equivalent of Technical Category 1 or 2.
This report was required before section titles could be issued.
"We have the Engineering Advisory Group from MBIE [Ministry of Business, Innovation and Employment ] reviewing a number of our consents to ensure everyone - architects, engineers and consenting staff - are applying them correctly," he said.
ECan was unable to comment yesterday.