A conservation group in the Illawarra is urging federal Environment Minister Tanya Plibersek to use her powers to stop the expansion of a sand mine near the Minnamurra River.
Boral received approval for the expansion in November 2020 from the New South Wales Independent Planning Commission.
Two weeks ago, the company referred part of the expansion plans to the federal environment department to decide whether it needed to be assessed under national environment law, the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
This stage of the project, known as 5B, includes clearing of 7.5 hectares of vegetation, including 38 threatened Bangalay Sand Forest trees bearing 100 hollows.
Friends of Minnamurra River (FOMR) has campaigned against the project for the past five years and was contacted by the federal department to comment on the assessment.
Graham Pike from FOMR said the project was environmentally obscene.
"They are going to allow the total destruction of it [the area] ... levelling the trees and all the animal and bird habitats, including the sea eagle, but they are also going to dig a hole 27 metres deep," Mr Graham said.
"All for a sand mine that is going to last two years.
"Work to install the dredge pipelines has already started. It is a very, very real threat."
Boral, a building and construction products manufacturer, said the sand from dunes in the area was the "optimum source" for construction in Sydney.
It said the mine was necessary because there were insufficient reserves of natural sand to meet demand for natural sand products in the Sydney region up to 2036.
The company also said other extraction sites south of Kiama were ruled out due to increased road transport costs.
It said sites near Albion Park were discounted because of zoning restrictions and other issues including proximity to residential areas, schools and other sensitive land uses.
FOMR president Will Chyra said the federal referral prepared by Boral was "predominantly a desktop study" and was "deficient".
"The report also dramatically increases the number of trees impacted, previously there were only going to be nine removed, now there are 38, they also increased the number of hollows impacted from 30 up to 100 of them now," he said.
"I implore Minister Plibersek to make the right choice, the importance of this site is immense, and she should make the decision ASAP to save this environment.
"There is critically endangered rainforest, coastal saltmarsh and six fauna species listed as threatened along with many other species all at risk."
He said the group only had 10 days to respond and its request for extra time had been denied.
Local state members, Labor Shellharbour MP Anna Watson and independent Kiama MP Gareth Ward, have repeatedly opposed the expansion.
This week Ms Watson said she was seeking meetings with the NSW Environment Minister Penny Sharpe and Planning Minister Paul Scully to see if the state government could mount a fresh challenge to the project.
She said it had been considered under an old planning pathway.
"At least this way we can do a proper audit. We need to hit the pause button," Ms Watson said.
A spokesperson for Ms Sharpe said the issue fell within the planning portfolio, while the planning minster's office referred the matter to the Department of Planning.
A spokesperson from the department said it was important the project remained at "arms length" from government.
"We respect the decision of the IPC and its strict conditions of approval for the Dunmore Lakes Sand project, including that the applicant must prepare a flora and fauna management plan and a rehabilitation management plan," they said.
Ms Plibersek's office requested her department respond to the calls from FOMR.
"If there are likely to be significant impacts on nationally protected matters, including threatened species and ecological communities, it will require assessment and approval before it can proceed," a departmental spokesperson said in a statement.
The minister and department are also still processing four applications lodged by traditional owners to stop the project.
The expansion is near the site of a known massacre where at least six Aboriginal people were killed by white settlers in October 1818.
A spokesperson for Boral said it was awaiting the results.
"Boral looks forwards to the conclusion of the Commonwealth EPBC approval process, following the successful conclusion of the NSW approvals process," they said.