Work will continue at the site of a major slip on the Southern Scenic Route in the Catlins at the end of this month.
The Chaslands Highway was closed from June 22 until July 16 after the slip, and the Southland District Council plans to close the Catlins road again for 33 hours.
The road will close from 6am on Wednesday, August 26, to 3pm the following day to test the integrity of the ground underneath.
When the Southern Scenic Route reopened in July, the council's roading asset management engineer, Hartley Hare, called the temporary measure a $15,000 quick fix: a 75m section of road had been temporarily moved to allow one-way traffic.
He said at the time further geotechnical analysis would be required before a permanent fix could be determined.
Mr Hare said the slip was still moving at the site, 2.8km from where the Chaslands Highway connects to the Niagara-Tokanui Highway - up to a week after the road was initially closed.
Once a geotechnical engineer's report was completed, the council would consider whether to re-form the road or shift it, he said.
A detour - from the Niagara-Tokanui Highway to the Papatowai Highway via Waikawa Valley Rd and Tahakopa Valley Rd - would be in place, as it was the last time the road was closed.
The date of the work might change if there was heavy rain.
