Contractors are to remove tonnes of dirt from behind a Dunedin home later today, after part of a saturated St Leonards hillside slipped away during the weekend's downpour.
However, Dunedin City Council development services manager Kevin Thompson said more of the hillside still perched above the home also needed to be removed, to protect against further landslips.
St Leonards resident Lloyd Hiscock on Sunday told the Otago Daily Times he was woken by loud bangs during the weekend downpour, and discovered a landslip had brought down tonnes of dirt against the back of his house.
He worried more of the hillside would follow, and was concerned the slip might have been caused by inadequate drainage on properties subdivided above his home.
Yesterday, Mr Thompson said the cause was still being investigated by geotechnical engineers Tonkin and Taylor, and it was too soon to speculate.
Farmland above the home had been subdivided. One house had been built there and another was under construction, but it was not clear whether drainage problems associated with the homes - or council roading stormwater systems - contributed to the slip, he said. They were among possibilities being considered, but results of the investigation were not expected for at least a week, Mr Thompson said.
"It's always been farmland and there's always been water run-off, so it's a case now of looking at what actually caused it. Is it from above, or is it something that's just happened on that particular section? "
Council contractor MWH inspected the slip zone on Sunday and again yesterday, and would continue to monitor the site, he said.
Mr Thompson also visited the site on Sunday and said what was left "looked stable at the moment".
The occupants remained in the home in the meantime, but it appeared more material - possibly as much as had already slid down - would have to be removed from above the home, he said. That would happen once the landowner - who was not a neighbour - had been contacted.
The Earthquake Commission and Mr Hiscock's insurance company would together cover the cost of removing the material already piled up at the back of Mr Hiscock's home he said.
