VIDEO: PDC takes down reinforced smokestack in the Philippines

(Image: PDC)

This was only the second smokestack to be felled by explosives in the country, with PDC delivering the works directly to the client, Aboitiz Thermal.

Originally built in the 1960s without seismic reinforcement, the chimney had later been retrofitted with four large concrete buttresses, each 2.75 metres by 1.25 metres at the base and tapering over 30 metres in height.

The structure, which sat in one of the most seismically active regions on earth known as the Pacific Ring of Fire, had already defeated three previous contractors.

The first had cut the rear reinforcement bars and attempted to push the stack over, the second chipped away at the concrete in an effort to pull it over, while the third lifted a demolition robot to the summit, only to lose the machine as it fell down the flue.

With mechanical methods exhausted, PDC was brought in to find another way.

“What followed was not simply an exercise in explosives engineering. It was a project that demanded equal measures of technical precision and cultural intelligence, conducted under conditions that tested both,” commented Cormac McLean, PDC’s managing director.

The company developed an innovative solution: cutting the first metre of buttress reinforcement while retaining critical corner bars for seismic stability, supported by detailed buckling calculations. The front buttresses were blasted as part of the main shot rather than in advance.

Beyond the technical challenges, the project also demanded careful respect for local cultural beliefs and traditions.

At the client’s request, PDC participated in a series of Filipino ceremonies and customs intended to ensure the safe and successful completion of the work, helping to build trust between the international demolition team and the local workforce.

Furthermore, a 6.9 magnitude earthquake struck the day before the team landed in Cebu, the strongest in recent local history. The following day, a 6.5 magnitude event occurred, and powerful aftershocks continued for weeks.

But through it all the team prevailed. On the day of the shot, the structure collapsed in 22 seconds, within just two seconds of the modelled time. It fell exactly as designed, with all debris contained within the prepared landing zone.

The entire sequence, from initial mobilisation through drilling, pre-weakening, charging and final cleanup, was completed on a compressed programme, with zero damage to nearby infrastructure and a perfect safety record. One hundred percent of the arisings were processed locally by Megabuild 101.

“This project demonstrates that high-hazard explosive demolition can be carried out safely and successfully, even when the ground itself is moving and the cultural landscape is equally sensitive,” concluded McLean.