150-metre Delimara chimney and last remaining HFO boiler being dismantled
● Over 10,000 tonnes of metal and concrete to be removed
The dismantling of the Delimara power station’s 150-metre high chimney and the last remaining Heavy Fuel Oil-fired power plant started yesterday, marking the beginning of the end of the 1992 plant.
A few days ago, the company’s demolition contractors cut and removed the two large exhaust pipes connecting the plant’s heavy fuel oil (HFO) boilers to the chimney. At the same time, other workers started dismantling the first of the two boilers as well. The year-long project includes the complete demolition of the concrete and steel chimney, weighing almost 9,000 tonnes or the equivalent of 6,000 cars, as well as the plant’s boilers, turbines and other auxiliary installations.
Once dismantled, the plant’s materials will be carefully separated on site before they are carted away to authorised disposal sites, Enemalta said in a statement. Over 5,400 cubic metres of concrete and other construction waste are expected to be removed from the site. Another 5,300 tonnes of metal will be exported for recycling.
The 1992 120 MW Delimara 1 power station was switched off and put on cold standby in April 2017, before it was fully decommissioned on 1 September.
A few days later, the Italian demolition contractors selected for this project started delivering the heavy machinery and other equipment required to dismantle the plant.
The plant’s chimney structure comprises a cylindrical concrete shield rising up 50 storeys, with a base diameter of 12 metres. The concrete walls are 80 centimetres thick at the bottom and 30 centimetres on top. Inside the concrete structure there are two 2.3 metre steel exhaust pipes that emitted the smoke produced by the oilfired boilers.
The dismantling process started with the removal of the lowermost part of these two steel pipes, which connect the chimney to the boilers. The remaining metal pipes, ladders and platforms higher up inside the chimney will be lowered to ground level using strand jacks, so that they can be safely dismantled on the ground.
At the same time, outside the chimney concrete walls, the contractors will soon start erecting an auto-lifting platform on five steel columns rising to the topmost part of the structure. Once all the metal inside the structure is removed, remote-controlled demolition robots on top of the platform will start pulling down the top 1.5 metres of the concrete walls. The platform will then be lowered 1.5 metres for the demolition robots to continue the demolition. All debris will reach the base of the chimney through the chimney itself, to minimise dust dispersion. It will then be loaded on trucks at ground level.
This process will be repeated approximately 80 times until the chimney is reduced to 35 metres. At this point, the platform will be dismantled and the remaining part of the stack will be demolished using a high reach demolition excavator from ground level.
Enemalta Chairman Fredrick Azzopardi explained that the Company’s engineers, architects and other employees are monitoring the process and assisting the demolition contractor to make sure that the dismantling works do not disrupt the security and operation of the other power plants nearby, which will continue generating the electricity required to meet the country’s demand. Enemalta is committed to complete this project as soon as possible, yet without putting at risk the health and safety of the workers involved and with the least possible impact on the environment and nearby localities.
“We are currently also dismantling the last few structures of the Marsa Power Station, which was fully decommissioned earlier this year as well. Once we complete the dismantling of the Delimara 1, we would have completely removed the last remaining HFOfired plants which we depended on until a few months ago. Instead, we are now meeting the country’s demand through a diversified, efficient mix of low emission gas-fired plants, the Malta-Italy Interconnector and grid-connected renewable energy sources,” Azzopardi concluded.
Energy Minister Joe Mizzi noted that the chimney stopped being used in April of this year, when Heavy Fuel Oil was phased out. He said works will be carried out in several phases and the necessary precautions to safeguard the environment will be taken.