Imperial
Oil Limited

Decommissioning and Preparatory Work
Prior to demolition, Delsan-AIM has carefully decommissioned all equipment and structures by disconnecting associated services and removing all residual products. In addition, an environmental scope of work has been carried out, including the removal and disposal of hazardous materials such as asbestos, mercury, ozone-depleting substances, and polychlorinated biphenyls (PCBs).

To facilitate safe demolition, all associated equipment and services have been carefully disconnected, and specific safety measures have been implemented to ensure the structural integrity of the surrounding refinery infrastructure throughout the process.

Demolition Operations
Demolition is proceeding in accordance with engineered procedures, employing mechanical methods using primarily 45-tonne excavators equipped with specialized attachments, in addition to a 117-ft high-reach excavator.

For structures that cannot be demolished by conventional means due to their height or proximity to live services or equipment, alternative methods are used, including mobile crane removal, mechanical lowering, or controlled demolition (e.g., controlled dropping). All materials are source-separated by waste type and transported off-site to licensed recycling or disposal facilities, in compliance with regulatory requirements.

Demolition of Key Structures
A key structure being demolished is a 301-ft. high, brick-lined concrete stack with a base diameter of 24.5 ft. tapering to 17 ft. at the top. The concrete shell is supported on a reinforced concrete foundation at grade level, while the 118-ft. high brick liner sits on a 2-ft. thick suspended concrete slab inside the stack at the 62-ft. level.

The demolition process involves systematically lowering the stack using small demolition equipment to an elevation that allows the bottom portion to be demolished from ground level with the high-reach excavator. During this phase, debris is safely conveyed inside the stack to the 62-ft. level, where the breaching has been enlarged to allow for periodic cleaning of the stack interior by the high-reach excavator.

Preparation and Safety Measures
Delsan-AIM arranged for the installation of high-capacity mast climber work platforms around the entire circumference of the stack to provide worker access during the lowering process.
The interior brick liner is being removed using a remote-controlled mini-excavator, which is supported by a custom-designed platform suspended inside the stack by a 400-tonne mobile crane. The mini-excavator, equipped with cameras, is operated remotely by a worker positioned outside the stack on the climber platform.

In a similar manner, the outer concrete shell is being lowered using remote-controlled mini-excavators mounted on both the crane and climber platforms. These mini-excavators are systematically pulverizing the concrete, allowing debris to fall within the stack's confines. The climber platforms provide protection around the stack's circumference, containing dust and small debris while offering access for workers to operate the mini-excavators and use torch-cutting equipment to cut reinforcing bars as work progresses.

Final Stages and Completion
As the stack is lowered, the climber platforms are dismantled in parallel. The final phase of the project will involve the high-reach demolition of the remaining lower portion of the stack, completing the demolition process.