Eighteen months of planning ended in about 20 seconds. Last Tuesday the two chimneys at AGL’s Liddell Power Station in the Hunter fell in a controlled demolition, closing out more than half a century of coal-fired history.
Brad Williams, AGL’s general manager of site transition, compared the job to “felling a tree”. The trees in question were 170 metres tall and about 20 metres across. “Rather than using an axe, we use explosives,” he said.
The method took patience. Crews drilled about 700 holes in the side of each chimney and charged them. “We also cut hinges on either side, effectively triangular sections,” Williams said, and then they cut through the reinforcement at the base of the stack. All told, about 260 kilograms of explosives went into each tower.
Keeping the dust down
Dust, ground vibration and air pressure were all modelled in advance. A 1-kilometre exclusion zone surrounded the site. Charges were also placed under about 40 “paddling pools” meant to hold water down, and they were timed to fire as the chimneys struck the ground. The idea was a water curtain to pull dust out of the air.
Wind mattered as much as the blast. “We need to make sure that the wind is blowing away from critical infrastructure on site,” Williams said, so speed and direction decided the timing.
“Lots of planning, lots of engineering, lots of approvals have gone into it,” he said, calling the whole effort “an awful lot of work for a 10-second event”.
The blast left about 14,000 tonnes of concrete rubble. AGL expects the clean-up to take three weeks, and said it was underway.
Before the big bang
The station had closed in 2023 after 52 years of operation. Well before demolition day, crews spent roughly 18 months on what Williams called the make-safe phase, getting the site “cold, dark and dry”. About a million litres of oil were recycled. An estimated 30 kilometres of conveyor belts came out.
Williams said watching the stacks fall was exciting and a little bittersweet. “It’s a huge milestone and very symbolic,” he said. “They’ve been iconic in the Hunter for decades … so it’s important we honour the legacy of the site, but it’s also important that we look to the future. Everything seemed to go perfectly to plan.”
The four boiler towers are next. They are due to be toppled in November.
AGL wants the land to become an industrial energy hub. The 500-megawatt battery there was recently commissioned and is in the final stages of that process, according to Williams. “That project has been very successful,” he said.
