Bushcare volunteer Jess Whittaker was shocked when she saw the dune vegetation are she and other had been working to rehabilitate the dune area for the past year.

She said trees had been drilled so as to die "in place" and provide shelter for 300 new local natives which had been plantings planted by the bushcare group three weeks ago.

But another group which needed some chainsaw operating training found themselves using this location after an "error" was made.

Watch: Energy crews remove trampoline from Corrimal power lines

"That was our little spot we look after," Ms Whittaker said.

"A chainsaw trainer came ... they didn't take any notice of the plantings in there, they just cut down these massive trees and cut them all up just to practice on - then left them dumped all over our site.

"I was beside myself - I couldn't believe we'd done all that work and had all those volunteers there, then that could happen."

Ms Whittaker, a Greens candidate at the previous council election, said she at first though a mini-tornado had gone through the area, as is believed to have occurred at Corrimal this week.

"They just left it all over the site," she said.

"Who conducts a training course then leaves all the mess there without cleaning it up?

"I thought 'what's going on here?' It deadset looked like a tornardo."

"It's going to be difficult now as we don't have that shelter.

"The plan we had in place was a good one. It's going to be a really exposed site now. We don't know whether people are even going to come down and want to work to fix it, after what we've been through."

The site, at Port Kembla beach just below the surf club, has since had some attention by council workers who had come and cleaned up much of the debris.

A council spokeswoman said there had been a mistake but said only one recent planting had been damaged.

"Wollongong City Council is aware there was an error around a weed removal training exercise in Port Kembla," she said.

"The acacias - which are declared weeds in the dunes - were removed from the wrong dune site by accident. However, they were in a location, which had been listed for weed removal work at a later date.

"The work was undertaken as part of a training exercise, and we have been advised that one recently planted tube stock plant was damaged. The tube stock has been replaced, and the acacias cut in the training exercise have been stockpiled outside the planting area and will be removed from site by Friday.

"Our passionate Dunecare groups play an important role in our community, and we continue to support their ongoing work."