Unitec Carrington Backbone Enabling Works

The Unitec Carrington Backbone Enabling Works project involved the extensive demolition and asbestos removal of 20 buildings at Unitec’s Carrington Road campus in Auckland. This project, valued at approximately $4.8 million, took place from January 2023 through to June 2024. Henderson Demolition Ltd was contracted to carry out the works, which demanded careful planning and strict adherence to safety regulations, particularly given the heritage value of some of the buildings, the hazardous materials on-site, and the complexities of operating within a high-traffic urban environment.

Scope of Work

The demolition and asbestos removal efforts were conducted across 20 buildings, including a gymnasium (recreational centre), which involved the removal of large mass concrete footings on both sides of the structure. The project also included stabilising the building footprints with metal and geotextile layers, installing silt fences on the western and northern perimeters, and carefully controlling runoff to protect adjacent construction areas.

Building 1, in particular, presented unique challenges due to its heritage status. This building was a Category 1 Historic Place, requiring strict adherence to a Heritage Protection Plan. The plan outlined temporary protection measures for the building's remaining structures, as parts of the building were retained post-demolition. Salvaging the building’s brickwork and native flooring was a priority, though difficult due to the extreme brittleness of the materials.

Heritage Preservation

A key aspect of this project was the deconstruction of Building 1, originally part of the Oakley Hospital, built in the mid-19th century as Auckland’s first lunatic asylum. Given the building’s heritage status under the Heritage New Zealand Pouhere Taonga Act 2014, significant public interest surrounded the work. The community raised concerns about demolishing a building that held deep historical significance, despite its dilapidated and dangerous condition.

The demolition was performed in alignment with a detailed Heritage Protection Plan that called for careful handling of the heritage fabric to avoid excessive vibration and settlement in the remaining sections of the structure. Temporary weatherproofing and reinforcement were also implemented to safeguard exposed walls post-demolition.

Asbestos Removal

The presence of friable asbestos within several buildings added significant complexity to the project. Hazardous materials, including asbestos, PCBs, and other contaminants, were located in subfloors, underground service tunnels, transformers, lift shafts, and chimneys. Meticulous care was taken to ensure the safe removal and disposal of these materials at licensed waste facilities.

Due to the historic nature of some structures, undocumented services such as stormwater and sewer lines complicated the work. In addition, asbestos was unexpectedly discovered in electrical cupboards and lifts, necessitating further control measures to protect both workers and the public.

Challenges and Solutions

The Unitec Carrington site presented a number of operational challenges. High levels of vehicle and foot traffic, along with frequent break-ins and vandalism, added an element of security risk to the project. Workers were subjected to threats, including incidents involving gun violence, making site security and worker safety a top priority throughout the duration of the project.

The site also experienced access limitations. Steep gradients in the surrounding area and a lack of access to Unitec’s carpark required the construction of temporary roads to facilitate safe and efficient transport of materials and equipment. These logistical challenges were compounded by the need to carefully separate recyclable materials during demolition, with the goal of maximising recycling and minimising landfill waste.

The process of separating roofing materials, pipework, ductwork, suspended ceiling tiles, windows, and other internal structures formed an integral part of the project’s waste management plan. The only materials exempt from recycling were the hazardous materials and soft demolition debris that could not be safely processed.

Health and Safety

The health and safety of the demolition team and the general public was paramount during the course of this project. Temporary fencing and other security measures were implemented to prevent unauthorised access to the site, especially in light of the frequent vandalism and trespassing incidents. Henderson Demolition Ltd ensured that site access adhered strictly to New Zealand health and safety regulations, submitting a comprehensive methodology to control access points, mitigate risks, and maintain safety protocols.

Staged Demolition

In order to ensure the safety of both the workers and the surrounding community, a staged demolition approach was adopted. A strict methodology was used to lower the superstructure of the gymnasium to the ground, ensuring that all hazardous materials were securely contained and removed prior to structural demolition. This phased process allowed for careful monitoring of the site and adherence to heritage guidelines while reducing the risk of airborne contaminants and structural instability.

Project Outcome

The Unitec Carrington Backbone Enabling Works project was a complex and multifaceted endeavour that successfully combined heritage conservation with modern demolition techniques. The recovery of building materials, such as native timber floors and bricks from Building 1, demonstrated a commitment to sustainability and preserving the historical legacy of the site, while the removal of hazardous asbestos ensured that the site could be safely redeveloped for future use.

Despite the challenges posed by undocumented services, security threats, and public scrutiny, Henderson Demolition Ltd completed the project within the allocated timeframe, ensuring the safety of all involved while adhering to the highest standards of health, safety, and environmental protection.

As this project concluded in mid-2024, it stood as a testament to the careful balance of heritage preservation, environmental stewardship, and effective demolition practices. The lessons learned from this project will inform future demolition efforts on historically significant sites throughout New Zealand.