It took firefighters more than two days and 150,000 litres of water to safely dispose of about 12,000 litres of gas in Mellieħa this week in a 50-hour operation that ensured a potential blast was completely avoided.

Three houses were evacuated on Monday after a Liquigas bowser carrying liquified petroleum gas (LPG) developed a constant leak. A faulty valve led to gas constantly escaping.

Civil Protection Department personnel were informed about the leak on Monday morning, CPD deputy director Peter Paul Coleiro said. With no time to lose, several senior CPD officers, including the director, the deputy director, operations managers, station officers and 20 firefighters were soon on site.

Read: Public urged to avoid Santa Maria Estate as civil protection battle gas leak

The gas could have easily found an ignition source, a spark from a machine or even a mobile phone, that would have caused the 12,000 litres of leaking gas to ignite, Mr Coleiro said.

There was also some danger with a drone that flew overhead

Chemist and university rector Alfred Vella went further: “LPG gas forms a very explosive mixture when released in the air. All it takes is something to ignite it and that could be a combustion engine or even just a spark from a switch being flicked on or off. When you flare it, that risk is dissipated completely.”

At the Mellieħa site, CPD personnel assessed multiple scenarios before deciding that, due to wind conditions and the weather, the safest and most efficient way to address the situation would be to slowly flare the contents. “We mulled closing the leaks with ice but it could have melted and if it found a source of ignition it would have hit off,” Mr Coleiro said right after the operation ended yesterday afternoon.

The CPD used constant water pressure to seal the leak, connected a bowser valve that was still functional to an outlet and then flared the gas in a safe area. The flare burned constantly for the entire 50-hour operation. More water was sprayed into the tank to convert gas to vapour, which was then extracted through a pipe and connected to a flare.

CPD personnel slowly flared the contents.CPD personnel slowly flared the contents.

The process needed to be continuous and multiple fire engines were on stand-by to ensure the water pressure was kept constant. The firefighters monitored and watered down surrounding trees to prevent a fire, Mr Coleiro added.

The most challenging part of the operation were the constantly changing conditions, chief assistance rescue officer Kevin Pace said. “You need to know how to alter the plan to deal with the temperature, weather conditions and the amount of gas inside the bowser,” he added. “We were moving bit by bit and then monitoring,” he continued, noting that this made it impossible for personnel on site to determine when the operation would be over.

Communicating with others outside the zone also proved difficult because use of mobile phones was prohibited as they could be an ignition source, he said.

There was also some danger with a drone that flew overhead, Mr Coleiro added. “Someone tried to fly a drone over the site. Had it come within range, we would have had to hose it down because it could also have been a source of ignition.”

Mr Coleiro noted that use of drones in such operations put officers lives in danger. “He might lose his drone but we would lose our lives,” he warned.

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