Vic pit collapse exclusion zone widened

The exclusion zone around an unstable excavation site in Melbourne has been expanded and will remain indefinitely, police say.

A large section of a 15-metre-deep pit in Burwood partially collapsed on Wednesday night, forcing 10 university students from a nearby block of townhouses to flee.

Police say it's the second time in a week residents have been moved away from the former petrol station site that is being turned into a medical and childcare centre with a double-storey underground car park.

On Thursday afternoon, police at the scene expanded the exclusion zone, closing a westbound lane on Highbury Road and a southbound lane in Huntingdale Road.

WorkSafe, CFMEU, Monash Council and Yarra Valley Water representatives were on Thursday assessing the damage, which is believed to have been caused by heavy rains, and will return to the site on Friday.

No further excavation work will happen until it is deemed safe.

On Tuesday, a back wall of the backyard of one of the townhouses was brought down.

Local shops have had their sewerage closed off and are using portable toilets while authorities work out how to solve the problem, and stop it from occurring again in the future.