The risk to people or property from a gas leak – or explosion – from the proposed Port Kembla gas terminal is “very low”, according to the environmental impact statement.
The statement also pointed out the terminal – located in the inner harbour next to the coal loader – would be several kilometres from homes.
The terminal would use a vessel called a floating storage and regasification unit (FSRU) to store the gas delivered by tankers.
That gas is delivered and stored in the FSRU as liquid and only converted to gas so it can enter the pipeline.
The statement found the liquefied natural gas (LNG) is stored at temperatures around minus 160 degrees Celsius.
“Should the LNG meet air at ambient temperatures it would turn to vapour and dissipate,” the statement said.
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That vapour is only flammable if there was both an ignition source present and a methane concentration in the air of five to 15 per cent.
The report said the “hazard potential” was greater when it was in its gaseous state.
“In each case for a hazardous event to occur there would need to be an uncontrolled release of gas, a failure of leak detection and safety mechanisms, as well as an ignition event such as faulty sparking equipment, hot works occurring in the vicinity or an otherwise sufficient source of heat for ignition,” the report said.
Despite identifying the chances of a fire of explosion as “very low” the statement still ran modelling of “the worst case consequences” of a range of incidents.
The most likely hazards were from a jet fire or flash fire – the former is a spurt of gas in a specific direction that ignites and the latter is a fire resulting ignition of a vapour cloud.
Less likely is a pool fire, where the LNG would need to be released and pool on the ground – an unlikely event given that liquefied gas tends to turn to vapour and dissipate.
Even less likely was the risk of an explosion which could occur in only a few locations.
“In the unlikely event that these hazardous events occur, the actual consequences to people and property, including radiant heat from fire and overpressure from explosions, would depend on the distance of people and property from the place where the hazardous event occurs,” the environmental impact statement read.
“The terminal itself is located more than two kilometres from the nearest residence. The pipeline is around 6.3 kilometres long and runs mainly through industrial land and is more than 200 metres from the nearest residence.”
The risk of fatality in industrial areas was higher than for residential area but the statement estimated that risk to be just 50 in one million.