Riverina Rewind: That time the Wagga sewage works blew up

Methane is very explosive.

It was a lesson learned the hard way by four Wagga men as they looked into a problem with the Wagga septic sewer works in the early 20th century.

A report from The Daily Advertiser on 23 May, 1916, captured the drama.

“The Wagga sewerage treatment tank, a very costly construction, situated in the old police paddock, was considerably damaged yesterday by a violent explosion caused by the ignition of gas which had been penned up in the tank ever since it was erected,” the story reads.

“Provision is made for the gas to escape through jets which are invariably alight. These jets are said to have never worked properly.”

The 30-foot (nine-metre)-wide tank was one of three new additions to the plant and was built of six-inch (15 cm)-thick reinforced concrete and partially sunk into the ground.

It had six burners to deal with the excess gas, and a government inspector had been sent out to take a look but had “failed to give satisfactory results”.

With the captured gas still not being vented, a group of four men, comprising Mr Tinsley, the sanitary inspector, Mr Keogh, the sewerage inspector, Mr Robinson, the council’s waterworks engineer, and another visiting engineer, headed down to examine the tank.

After a long discussion about the possible causes of the problem, they climbed on top and took a closer look at the burners.

From this point, accounts differ as to what caused the explosion.

The Advertiser claims that after several failed attempts to ignite the burner of the gas consumer, the men decided to light one of the air vents.

They struck a match and strode quickly away to a “safe” distance seconds before “a terrific explosion occurred”!

The Sydney Morning Herald repeats the claim that the men applied a flame to the vent, however, the Riverina Times suggests that they were more cautious.

“When Mr. Tinsley suggested replacing the gas burners with new ones, the jets were unscrewed, and the men walked off for the new ones,” the Times reported.

“They had just got clear when the roof of the tank was blown out by the gas.

“Nothing was done to cause the explosion, but the men seem to have arrived there at the moment when the pressure had reached its maximum.”

What all accounts agree on is the scale of the blast!

The noise of the explosion was heard all across town and the men narrowly escaped injury as tonnes of reinforced concrete and iron were thrown into the air.

One tank was destroyed and another damaged, and the whole sewerage system would be shut down while the situation was assessed.

What followed was an extensive round of finger-pointing as the various officials and departments sought to hand off the blame.

Inspector Tinsley claimed that Inspector Keogh had instructed an employee of the public works department to close and seal a manhole with cement, something Inspector Keogh denied.

Discussions in the council suggest that the men had indeed set a vent alight and The Daily Advertiser reported that questions were asked as to “why had not the cover been removed before a haphazard and dangerous experiment was tried?”.

It was confirmed that a flame had burned at the vent for a short time before the tank ignited.