Wollongong City Council crews were quick to respond, using gravel to fill in the holes the next day.

But much of the gravel has since eroded, and resident Beth Lynn said she was concerned the next big downpour would again lead to large rivulets opening up in the street's bitumen.

"It's starting to erode already, and that was from a little rain," she said.

"If it rains again, it's going to be back in the same predicament."

Ms Lynn said the initial damage was so bad, her son's vehicle was left with its wheels hanging over a 30 centimetre deep crack. "If he didn't have those wheels on the gutter, he would have been in the ditch," she said.

"It's destroying my car as it's hitting all the potholes all the time.

"You're worried if you go to sleep and it rains [your car] is going to be in a ditch."

Council crews arrived on Boxing Day to fill in the holes, which stretch between the end of Wilga Street at Corrimal Memorial Park and intersecting Rothery Street.

Employees were paid double their usual rate due to it being a holiday.

The damage occurred when more than 70 millimetres of rain fell in parts of Wollongong on Christmas evening.

Ms Lynn said the holes were made worse because many motorists used the street as a back entrance to a shopping centre.

"Council said they're going to fix the road but they didn't really fix it, they just put gravel down," she said.

A council spokeswoman said workers have been undertaking subsoil drainage work on the street for approximately two weeks in preparation for the road to be resurfaced, which is scheduled for January 6.

"The subsoil drainage work requires a number of holes to be made in the road, which have been temporarily filled," she said. "Unfortunately, due to heavy rain over Christmas, some of these holes became deeper, with the temporary filling washing out."

The spokeswoman said on Boxing Day, council workers added gravel to one hole that had become "particularly eroded". "It was not considered practical or financially viable to put a more permanent fill on the hole given that the entire road will be resurfaced within a matter of days," she said.