Massive demolition site

This Issue This is a part of the Canterbury earthquakes feature

By - , Build 126

Christchurch’s CBD red zone is currently the largest work site in New Zealand. So what’s going on behind the 3.7 km perimeter fence on this 71.4 hectare site?

It is estimated that 1,500 buildings could need to be demolished or partially demolished in the CBD red zone. By early September, 503 works were completed (383 buildings demolished and 120 partially demolished) and 124 buildings had work under way. The Canterbury Earthquake Recovery Authority (CERA) plans to have demolitions in the CBD completed by the end of April 2012, although significant tall buildings are expected to take longer due to their complexity.

Impressive machinery

Between 75 and 120 demolition and construction teams are working on buildings within the cordon, and 1,400–1,500 traffic movements occur in and out every day. Most are trucks carrying rubble to the Burwood Resource Recovery Park, but some take clean rubble for land reclamation to Lyttelton Port.

Some of the country’s largest cranes, high-reach diggers, crushers, bobcats, crawlers and excavators are in the CBD.

Dangerous work site

The red zone is a dangerous worksite. Health and safety measures include traffic management plans, hazard signage, designated contractor parking, on-site Department of Labour enforcement officers and regular ‘toolbox meetings’.

Contractors are dealing with the usual risks such as the potential for hazardous substances, asbestos or gas cylinders on site, but there is also the risk from earthquakes. Falling debris or building collapse during an aftershock is a real threat – a message brought home after the 13 June aftershocks when over 215 buildings in the CBD required urgent or partial demolition because of the hazard they posed to people and property.

Powers changed over time

From 22 February to 30 April 2011, a National State of Emergency was in place under the Ministry of Civil Defence and Emergency Management (MCDEM). Work to make greater Christchurch safe was done under these powers.

From 1 May to 12 July 2011, a transition period occurred where CERA emergency management measures, including demolition started during the MCDEM period, continued under section 85 of the Canterbury Earthquake Recovery Act 2011. Demolition work continued, much of it under CERA, in agreement with the building owner. Works are invoiced to the building owner and/or the building owner’s insurance company. Costs include initial planning of the demolition, demolition and making the site safe, disposal of debris and management of the project.

Heritage buildings

For restoration reasons, some buildings or parts of buildings are carefully deconstructed to preserve heritage materials or building façades. This only happens if the building owner agrees and it can be safely done. Sometimes, the cost and time to save heritage materials is prohibitive, but CERA works with building owners to assist where possible.

Process

Work under CERA begins when a building is identififified by CERA engineers as dangerous and needing demolition or partial demolition work. A building demolition report is prepared with a completed risk assessment. The CERA demolition manager reviews the report and signs it off.

A section 38 notice is sent to the building owner and interested parties. Usually, CERA has already talked with the building owner and insurers who will have begun forming a demolition plan or decided to have CERA organise the demolition on their behalf. The owner has 10 days to respond to the letter.

If the building owner wishes to manage the work themselves, they need to supply CERA with a health and safety plan, a traffic management plan, demolition methodology, contractor name, start and finish dates, site services capping plan, treatment proposal for basements, piles, footpaths, kerbs and ground service (topsoil and seeding), a hazard management plan and a waste management plan. They also need resource consents for heritage listed buildings.

CERA reviews the documents and liaises with the owners to monitor the work. Once the work is completed, the owner/contractor returns the completion certificate to CERA.

If the building owner selects CERA to manage the project, CERA scopes the work and allocates it to one of its accredited contractors. The work is monitored and the final account analysed before the completion certificate is lodged.

Demolition Manager Warwick Isaacs says, ‘Reopening the central city as quickly as possible, and working towards the recovery of greater Christchurch are top priorities for CERA. We are working closely with building owners and their insurance companies to get building treatments under way in a fast, well managed way.’

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