McCrae braces for another landslide day after luxury house destroyed

Residents living above a luxury home that plunged 50m down cliffs in McCrae believe an underground stream contributed to the chaotic landslide, with fresh potholes evidence of a bigger problem below the surface.

McCrae residents living above a luxury beachside home that plunged 50m down the cliffs on Tuesday believe an underground stream contributed to the chaotic landslide.

The Prospect Hill Rd locals pointed to new, large potholes near their home as evidence of a bigger problem below the surface.

The couple, who did not want to be named, said the pothole appeared near the corner of Coburn Ave and Prospect Hill Rd on Wednesday morning as more cars used the road to detour around the landslide hot zone.

Tradie Keith, who used to live on Coburn Ave, said the ground was “always boggy” on either side of the road and the fresh potholes were further evidence of the amount of water just below the surface.

“Those potholes have just opened up and are getting wider and deeper as the day goes on,” he said.

“You can also often hear the water rushing through the drains, even when it’s not raining.”

Fresh potholes that sink deeper when driven over have appeared in Coburn Ave above the McCrae landslide hot zone. Picture: Lucy Callander

La Trobe University Emeritus Professor John Webb, who specialises in groundwater research with a focus on land use and climate change, confirmed there were underground water channels in the area.

Professor Webb said there was a significant amount of water that had to find its way from the top of nearby Arthur’s Seat to the bay.

“The sudden appearance of potholes and the way they have been described suggests water has flowed beneath the surface, creating space, and potentially leading to the road sinking in that area,” he said.

Professor Webb said the case was likely to end up in court and he expected land use and zoning in the area would be examined.

He said it was inappropriate for him to speculate on whether residents would be able to return to the evacuated houses on the McCrae cliffs or if the structures should have been built in the first place.

However he said there was “ inherent risk” in building on a steep slope.

Monash University department of civil engineering head Ha Bui said landslides were caused by prolonged rainfall, unstable soil, underground water seepage and human activities such as excavation.

Traffic is being detoured through back streets around McCrae as part of Point Nepean Rd is expected to be shut for at last a week. Picture: Lucy Callander

“On the Mornington Peninsula, recent weather patterns, along with reports of persistent underground water bubbling in the area, point to the possibility of internal erosion – a process that gradually weakens the soil structure due to underground seepage flow, ultimately leading to slope instability and triggering a collapse.”

He said a failed slope was more prone to further landslides if underlying conditions were not resolved.

Early detection systems, such as real time monitoring, satellite imaging and geotechnical modelling, were crucial to reducing risk, he said.

McCrae braces for more landslides day after home destroyed

Authorities are bracing for further landslide activity as rain and thunderstorms hit the Mornington Peninsula where a house was destroyed in a landslide on Tuesday.

Point Nepean Rd in McCrae is likely to be closed for at least a week after a luxury beachside home plunged more than 50m during Tuesday’s chaotic landslide.

A council worker inspecting the home at the time was rushed to hospital with injuries to his lower body.

He remains at the Frankston Hospital in a stable condition.

Sorrento SES unit controller Mark Daw said an additional “tiny” slip had occurred on Wednesday morning but the potential for heavy rain could cause further damage.

“We’ve had FRV monitoring up on the slope to make sure there’s no real movement,” he told 3AW on Wednesday morning.

“We had a tiny little bit (of movement) in the early hours of this morning which was just 2mm, but since then it has not moved.

A home in McCrae after a landslide near Point Nepean Rd. Picture: 9News

A council worker was forced to ‘leap for his life’ from the property when it went sliding down the hill. Picture: David Crosling

“We’ve got a lot of thunder and lightning happening and we’re concerned about the potential for rain … we might have up to 20mm coming through.

“We can’t predict what potentially could come down, we know that there probably will be another slip but we’re unsure of how much.”

But only 2mm of rain had been recorded at the nearest Bureau of Meteorology site at Cerberus by 1pm on Wednesday.

Mr Daw said traffic diversions would be in place for at least a week until specialist crews could properly assess the site.

“Realistically, I’d say, at a minimum, for a week, but it could potentially be more,” he added.

“Until we can get the geotechs and work out a game plan of how to mitigate what’s up top, and what could potentially come down, it probably will stay closed for a while.”

Emergency services said several agencies would remain on site throughout the day.

The Penny Lane home before the landslide. Picture: Supplied

“Site assessments will continue today and the site will be monitored for any further subsidence caused by the storms forecast this afternoon,” an alert read.

Eleven homes within the 150m “hot zone” of the site have been deemed uninhabitable, including seven homes that were evacuated in the hours after the landslide.

“We’ve got a hot zone set up, we’re worried about potential further slips, so at the moment, we’ve got probably 100m to 150m on either side, houses evacuated from the top of the hill down to Point Nepean Rd just in case,” Mr Daw added.

Owners of the holiday home Nick and Kellie Moran said his family was “in shock” in a statement released on Wednesday.

The house was reduced to rubble in the landslide. Picture: David Crosling

The owners were not in the home at the time. Picture: David Crosling

“We are very grateful that nobody died yesterday,” Mr Moran said.

“We have engaged a lawyer and insurance and will be working through them.”

Mr Daw confirmed that the Moran’s home was subject to a separate landslide just last week.

“I was the incident controller for that one also, that was a week ago, there was a small slip that went into the property that now is destroyed,” he added.

“It impacted and then it was inhabitable, after that, the council had been monitoring over the course of the week and doing further tests with their geotech.

“And unfortunately what they didn’t think was going to happen, happened.

“At least (the council worker suffered) minor injuries. He will, from what I’m told, make a full recovery.”

Originally published as McCrae braces for another landslide day after luxury house destroyed