The sight of a collapsed turf at AJ Burkitt Oval in Heidelberg on Monday afternoon captured the attention of curious onlookers.

According to Duncan Elliott, the chief executive of the Victorian Infrastructure Delivery Authority (VIDA), two tunnel boring machines were actively working underground only a few meters away from where the incident occurred. These machines are part of the significant North East Link project.

Arnold Dix, an engineer and former president of the International Tunnelling and Underground Space Association, expressed on the Today show that he suspects a connection between the tunneling activities and the appearance of the sinkhole.

“When a sinkhole appears on the surface, it often indicates potential problems beneath the ground,” Dix explained. “It raises concerns about the safety of the workers below and, naturally, the safety of those above ground as well.”

“Clearly, something has gone amiss,” he added.

“And some serious questions have to be answered about how it’s gone wrong, why it’s gone wrong, to make sure it doesn’t happen again.”

He said that such a sinkhole posed a “serious risk”, noting that the oval appeared to have been recently mowed.

“If I was mowing that oval and it had collapsed and I went in, that’s really serious risk,” he said.

“You could be you could be seriously injured or killed if you fell into it.”

But he said the oval would be safe to use again once the issue had been identified and corrected.

“It could be a change in the movement or the ground level of water underneath,” he said.

“It could be that they’ve had more material go into their tunnel boring machine than they were expecting. There’s a whole range of reasons for it.”

However, he said, the fact that the sinkhole had not yet expanded – though he noted that was a possibility – and the fact that nobody had yet been injured, meant it was the sinkhole he’d like to see in his backyard, if he had to have one.

“This is the cute and cuddly sort, this one,” he said.

“Let’s keep it that way.”

A North East Link spokesperson yesterday told 9news.com.au they were aware of the sinkhole “in the vicinity” of the tunnelling operation.

“The area has been secured and crews are closely monitoring the site and surrounding areas – and we strongly advise people to avoid the area while investigations into the cause are underway,” they said.

“No injuries have been reported and there is no immediate threat to the community or residential properties.”