“Hellmouth”: ground opens up on Collins St

By Marco Holden Jeffrey

Some Melburnians were questioning if the end of the world was upon them when a sinkhole opened up on Collins St on Tuesday, June 2.

The sinkhole - dubbed a “Hellmouth” by one online commenter - was discovered by a resident overnight and stopped eastbound traffic on the roadway between Queen and Elizabeth streets.

A council spokesperson said the one cubic metre sinkhole was caused by a crack in the stormwater drain running down Collins St.

A roadworks crew used CCTV drainage robot cameras to identify and repair the crack, as well as identify another crack developing further along the drain.

The road was reopened once repairs were completed on Friday, June 5, and closed briefly on Thursday, June 11 for additional asphalting works before reopening the same day.

The spokesperson said the City of Melbourne had scheduled the drain to be replaced in full in 2021.

Sinkholes in urban areas often appear when faulty drains, pipes and water mains leak into the soil or clay under a road and wash it away, causing the road to collapse - or more accurately - sink.

But University of Melbourne earthquake professor Mark Quigley said it wouldn’t be feasible - or even a priority - to focus on preventing future sinkholes in the city.

“Prevention is quite challenging because to do that you’d have to basically ensure that there’s no leaky ageing infrastructure under an entire city,” he said.

Instead council could focus on predicting where sinkholes would emerge, before “a pinprick in a water main becomes something that could engulf a car.”

Prof Quigley said a regular survey of the area using a ground-penetrating radar to detect voids underneath the street that could develop into sinkholes would be a more feasible solution for council.

He also encouraged locals to learn to recognise the warning signs of sinkholes - “circular shaped cracks and anomalous depressions” in the road - and report them to council if spotted •