Quality Cut & Core (QCC), specialising in the deconstruction of concrete structures, was the appointed demolition contractor for the removal of the Old Māngere Bridge in Auckland, a Waka Kotahi NZ Transport Agency project. QCC worked closely with McConnell Dowell to develop a practical, efficient and cost-effective demolition design using a ‘cut and crane’ method. A cut and crane method on temporary staging was chosen, rather than the use of a barge, to ensure that the structure was removed in a controlled, safe manner. This method also resulted in full compliance with the resource consent environmental conditions.
The bridge had 17 spans and 60 piles to remove, comprising of more than 6000 tonnes of concrete. Each span is broken up into eight bridge beam lifts, one headstock and four pile lifts – with the cut sections being placed onto the temporary staging for preparation and cartage to a disposal facility.
With the bridge stretching across the Manukau Harbour, environmental control was paramount to QCC and McConnell Dowell when developing the demolition design. QCC utilised its custom-designed slurry catchment pontoons, which float in the water underneath the cut location. This prevents slurry from entering the marine environment, keeping sea life in the harbour unharmed.
Reliable resourcing is an imperative part of successfully completing a project of this size. QCC, a New Zealand-owned family business, completes projects all over New Zealand and the Pacific Islands, and is mindful of hiring locals to assist the communities’ economy wherever they are, and providing upskilling opportunities. On the Old Māngere Bridge replacement project, QCC allocated a project manager, highly skilled wire saw operators, floor saw operators and a truck driver, and hired three general labourers from the Māngere region. As well as ensuring adequate labour for the project, equipment selection was also key. QCC owns the most efficient range of cutting equipment in New Zealand, and had wire saws, a custom-designed pile cutter, floor saws, and multiple core drills mobilised for this project.
QCC developed an underwater pile-cutting method that successfully removes the piles at seabed level, with a cut time of just 25 minutes, and that eliminates the need for divers. This is an innovative technique that is new to the industry, and QCC is proud to have successfully implemented this.
Kurt Grant, McConnell Dowell Project Director, says, ‘The Team at QCC has done an exceptional job in creating and executing a demolition plan for the Old Māngere Bridge that is safe and efficient. The team’s commitment to safety consciousness and environmental initiatives has impressed McConnell Dowell and our client. Their office and site staff have been a pleasure to work with and their timeliness in executing the project program has exceeded our expectations on this challenging project. A job well done!’
For more information, email admin@qualitycut.co.nz or call 03 344 1469