KEY POINTS:
Waitakere Mayor Bob Harvey says a land slip into a Swanson stream could cause a "large-scale catastrophe" for which local authorities would share the blame.
Tuesday's landslide on a steep bank blocked the stream beside the Redwood Park Country Club.
Mr Harvey, councillors and residents were later briefed by engineering consultant Rodney Hutchison, who said further slips were likely.
Mr Hutchison said the crest of the 50m-wide slip started in a fill embankment formed on the property of Ross Britten, near where another slip blocked the stream three years ago after torrential rain.
Further failures were likely, said Mr Hutchison, because water was ponding in a fill embankment formed on the hillside.
He urged immediate work to stabilise the slope. This included draining deep water from behind the 3m-high embankment, which Mr Britten has formed for a 2km model railway track.
Mayor Harvey disapproves of the former city councillor's project and is frustrated that four years ago it was granted resource consents by an independent commissioner on behalf of the city council.
He said the railway and botanical garden project had been going on for about 20 years.
Meanwhile, truckloads of old tyres, building debris and soil had come on to the property under a consent from the Auckland Regional Council.
Mr Harvey said cleaning up the slip last time cost ratepayers dearly and "it will be over my dead body we pay again".
He said the next slip could dam the major stream, posing a risk of a large-scale catastrophe for properties downstream. "Blame will be laid squarely on the shoulders of the ARC and Waitakere City Council."
A Waitakere City spokesman said the council was forming a temporary stream diversion to avoid water building up behind the slip area.
Mr Britten said: "This is a baby slip compared to some around but it is an excuse to have a crack at me.
"It's 100 per cent weather-related. Everything has been done to ensure there would not be any slips but these were the worst conditions in 10 years."
He said he was pumping out the water from a trench on the embankment and had engaged contractors to do remedial work on the embankment to "engineer's specifications".
The ARC said its clean fill consent predated the Resource Management Act 1991.
