The sound of exploding papa rock will be heard reverberating around the hills of the Whanganui River over the next week.

A 70m stretch of the Atene Skyline Track fell away during last year's flooding, leaving a smooth papa cliff face and work to restore it began this week.

Abseil Access have been contracted to blast a track along the cliff at Atene joining up with the existing track.

"It's just a solid papa cliff face, hence we've got the explosives guys here to blast it out," Department of Conservation recreation ranger Shane Woolley said.


He expected it to take about two weeks.

"This is probably the last of the big flood damage from last year. We've just been flat stick since the flood," he said.

Abseil Access blast technician Quintin Myers said they could blast 5m sections of the cliff at a time at a rate of about two explosions a day.

After drilling a series of holes 1.5m into the side of the cliff face and 1m downwards, explosives are set in the holes.

The road is then closed and there are a two-minute, 20s and 10s warnings. The contractors then retreat down the track and around the corner, where they detonate the explosives.

It blasts about a 1m by 1m track into the cliff face, with rubble cleared by hand.

DoC will come in later and tidy it up.

The conductors have set up abseiling gear on the cliff face to aid them in drilling the holes on the steep and slippery cliff.

"Just being papa, it's just so slippery," Mr Myers said. "As soon as it gets any water on it, it just turns into a mud bowl."
*Video courtesy Abseil Access.