The top point of the II stage Vent Stack is at the elevation +150,000 m. The stack is a cylinder 75.5 m high with a permanent 9.00 m ID. In order to perform dismantling works a tube of the stack is cut in 7 separate sections, which are dismantled in turn in the separate fragmentation site where they will be inspected and after removed to the disposal place. The workers, who are carrying out dismantling works, had passed special training and are equipped with the up-to-date technical equipment and protection means.