Dire predictions of a landslip on the terrace near a controversial industrial landfill opposite Greymouth’s water treatment plant were realised on Friday as a torrential downpour hit.

The slip came down across Taylorville Rd during an early morning localised storm that also flooded parts of Greymouth and its suburbs, including the CBD, and swamped several vehicles.

Two cars ploughed into the slip in the dark, without injury.

Residents and critics of Taylorville Resource Park (TRP), a privately owned landfill taking industrial waste from Christchurch, had warned the West Coast Regional Council that the landfill had been built on an unstable site, as the terrace had slipped before.

Regional council regulatory and policy manager Matt Smith said there had been no complaints about Friday’s slip, and the area where rubbish was dumped in the landfill was not close to Taylorville Rd.

He said the slip did not pose any risk to the Grey District Council’s town water treatment plant.

Although the regional council could not prevent any slippage, it would make sure there was no risk from the landfill to the water treatment plant, he said.

A spokesman for TRP said the landfill was not affected by the slip and continued to operate.

Former Grey district councillor Cliff Sandrey, who is acting for Taylorville Rd residents, said the regional council had a responsibility.

“[TRP] have gone ahead and built it where it is, and part of the argument is that it is prone because of our weather conditions here.

“It is up to the contractor to make sure it is up to par, but it is up to the regional council to make sure that they have done so,” Mr Sandrey said.

Greymouth mayor Tania Gibson, who is being sued by TRP for defamation over previous comments about the proximity of the landfill to the water plant, would not comment when asked if the slip might pose a risk to the plant.

A Grey District Council spokeswoman said they were “unable” to comment further.

However, West Coast Regional Council member for the Grey constituency, Cr Peter Ewen, has previously raised the threat of slips with his council, and he said on Thursday he believed the council had not looked at the historical data about landslips on Taylorville Rd.

“They are not aware of it. But being ignorant of it is not an excuse to say, ‘well, she is safe’. They have got to do their homework.”

Cr Ewen pointed to the advice TRP had received about the site in Taylorville Rd.

“They engaged some consultants to do a report for them … the crux of the report was there is no issue.

“Well, you have had a landslide over the road and a car ran into it — that tells me there is an issue.”

Cr Ewen said it was up to TRP to get more advice on the stability of the site because the first advice they got was incorrect.

He said the West Coast rainfall needed to be taken into account.

“This is the nature of the West Coast landscape. With our climate, you have got to take [it] into account and if you dismiss it or you downplay the risk, it will come back to bite you in the arse.”

Cr Ewen said although the landfill’s location did not pose an immediate threat to the water treatment plant, it was something to be concerned about.

“It is not an immediate threat because it would have been checked by geologists, I imagine, but there would be parties that will be concerned about it and rightly so.”

All parties had a duty of care to be upfront about the risks in Taylorville Rd, he said.

Speaking on behalf of residents, Mr Sandrey said the regional council needed to take responsibility for any risk.

“To me, the Taylorville Resource Park should not exist there, but it does, and it does so legally because the regional council sat on their hands and allowed it to happen.

“So, until they take responsibility for it and do something about it, there is not much that is going to change.”

LDR is local body journalism co-funded by RNZ and NZ On Air.