Beneath the rubble of Liddell Power Station towers lay 'perfect' plan

Liddell Power Station's chimneys were brought down with explosives last week after months of meticulous planning.

Owner AGL says the clean-up is underway following the successful demolition.

The next phase of the demolition will be the toppling of the four boiler towers in November.

After 18 months of meticulous planning, it was all over in about 20 seconds.

The iconic towers at AGL's Liddell Power Station came crashing down in a controlled demolition last Tuesday, bringing an end to more than half a century of coal-fired history.

The company's general manager of site transition, Brad Williams, likened the demolition to "felling a tree", although in this case the two "trees" were 170 metres tall and about 20 metres in diameter.

"There are about 700 holes drilled in the side of the chimney, and they're charged or packed with a small amount of explosives.

"We also cut hinges on either side, effectively triangular sections … and then cut through the reinforcement at the base of the stack."

The two chimneys have been part of the Hunter region's skyline for more than half a century. (Supplied: AGL)

The "small amount of explosives" can add up for a job of this size; about 260 kilograms was packed into each tower.

Mr Williams said extensive modelling on dust, ground vibration and air pressure was done in the lead-up to the blast.

"Lots of planning, lots of engineering, lots of approvals have gone into it," he said.

A 1-kilometre exclusion zone was enforced around the blast site, and charges were also placed beneath about 40 "paddling pools" designed to minimise the spread of dust.

A number of blue paddling pools (bottom left) were set up on each side of the blast site to help with dust minimisation. (Supplied: AGL)

"[They were] timed to go off when the chimneys hit the ground," Mr Williams said.

"That's designed to create a water curtain in order to bring down as much dust as possible.

"We need to make sure that the wind is blowing away from critical infrastructure on site … and the dust disperses as it leaves the site, so it's all about wind speed and direction."

The explosion left about 14,000 tonnes of concrete rubble in its wake, which the company estimates will take three weeks to clean up.

Half a tonne of explosives were packed into the base of the chimneys to bring them crashing down. (Supplied: AGL)

The Liddell Power Station was closed in 2023 after 52 years in operation.

Long before the big bang that brought the towers tumbling down, work was going on to ensure the site was made "cold, dark and dry" and ready for demolition.

"That