Slip holds up power project work
A slip is developing near Murchison, forcing the closure of Matiri West Bank Rd and hindering work on a planned hydroelectric power scheme.
Tasman District Council transportation manager Jamie McPherson said the road had been closed to all vehicles, based on advice from a specialist geotechnical engineer, because of the risks posed by the slip, which was about 50m high and 120m across but still developing.
While the slip and surrounding area were being inspected recently, fresh cracks appeared ‘‘literally before their eyes’’, McPherson said.
‘‘The slip is being monitored daily for movement. This monitoring will take place over at least two weeks.’’
It appeared that wet weather had set off the slip, ‘‘so it is important we are able to understand how it is behaving under different conditions’’, McPherson said. The council, its specialist engineer and contractor were planning how to ‘‘minimise water getting into the slip area’’.
‘‘This is a bit of a challenge, given its scale and the terrain involved.’’
Meanwhile, a ford was being developed across the Matiri River, several kilometres north of the slip, he said. ‘‘This will provide some interim access for landowners until full access can be restored.’’
A site meeting was held last Friday with affected parties, including landowners and Fonterra. ‘‘They, along with DOC, will continue to be kept fully informed,’’ McPherson said.
Pioneer Energy Ltd is one of those affected parties. It recently started work extending Matiri West Bank Rd to the west branch of the Matiri River – the first phase of its project to construct a hydroelectric power scheme at Lake Matiri.
‘‘Worst-case scenario, the whole thing could let go.’’ Jamie McPherson, Tasman District Council transportation manager
Project development and delivery general manager Peter Mulvihill said the slip was an impediment. A ford might be helpful in the ‘‘very short term’’’, as long as the river level was low, but there were concerns about moving machinery across it.
‘‘We’re working with the council to find the best way of getting long-term access restored.’’
Pioneer Energy hoped to ‘‘wind up’’ work over summer to get the project completed, Mulvihill said. The optimistic plan was to have it finished by March next year, but the timeline was partly dependent on the weather.
McPherson said the slip was well known, and there were some large landslides in the area during the 1929 Murchison earthquake, ‘‘so we’re picking people’s brains in the area so we can get an idea of the history’’.
‘‘Worst-case scenario, the whole thing could let go. If it did, that it might actually dam the Matiri River, which could cause a whole range of issues. Best-case scenario, it could settle down.’’