A FENCE made of steel beams and 25 millimetre wire was still "no match for the antisocial destructive tendencies of four-wheel-drive drivers," says Lloyd Hedges.
Mr Hedges, the Menai Wildflower Group's representative on the Lucas Heights waste facility community reference group, says the damage has allowed vehicles to illegally enter Georges River National Park.
He said trespassing by 4WD vehicles and trail bikes, together with illegal rubbish dumping, was causing enormous environmental harm to the area.
Mr Hedges said the proposed expansion of the Lucas Heights waste facility would give the state government the money to tackle both problems.
The government's planned levy of at least $120 a tonne on dumped rubbish would net an extra $1 billion from a 8.3 million tonne increase.
Mr Hedges said the the environmental problems were largely due to some of the major stakeholders around Mill Creek being "unwilling to accept their responsibility to stop their land being abused".
Although National Parks and Wildlife Service and Sutherland Shire Council had made "concerted efforts," there was no similar commitment by the Australian Nuclear Science and Technology Organisation (ANSTO) and Gandangara Local Aboriginal Land Council.
"Whatever ANSTO has done is inadequate," Mr Hedges said.
"A walk along the edge of Old Illawarra Road will confirm that they clearly do not place enough importance on the state of the land they control."
But Mr Hedges said the Aboriginal land council, which is under administration, was "the weakest link".
"They were granted title to the majority of the area by Greiner Liberal government in the early 1990s.
"Since then, the dumping and 4WD activity has increased dramatically."
An ANSTO spokesman said the organisation was ‘‘one part of a local, state, federal and community effort to keep bushland in the Lucas Heights area pristine’’.
“ANSTO patrols the area and while the focus is security, if we identify dumping or trespass, we take appropriate action,’’ he said.