Conservationists have said the oil company Santos has not addressed questions about how its proposed 850-well Narrabri coal seam gas project in New South Wales would affect threatened species.

Two new reports, including one by a former ecologist for the NSW environment and heritage office, say the company had not adequately responded to submissions which raise concerns about animal and plant surveys Santos conducted for its environmental impact statement.



Santos’s formal reply to more than 20,000 public submissions was criticised by opponents when it was released earlier this year.

David Paull, a consultant ecologist who was employed by the NSW government, wrote a response disputing Santos’s findings that endangered box gum woodlands were not present at the project site and that yellow box was either absent or “occurs at such low abundance to be meaningless in terms of plant composition”.

Paull said the company had also failed to conduct surveys for stygofauna, which are species that help purify groundwater, despite a recommendation from the independent expert scientific committee that it do so.

In a separate report, an ecologist, David Milledge, said concerns he raised about animal surveys at the project site in a submission with the North West Alliance “have not been satisfactorily addressed”.

Species surveyed for include the Pilliga mouse, koalas, the south-eastern long-eared bat and the eastern pygmy possum.

A 10-day survey by Landmark Ecological Services – led by Milledge in 2011 – found more than twice the animals in the project area than Santos had recorded from 2010 to 2014.

“Santos’s lack of success in detecting the presence of threatened vertebrate species over four years of surveys in the project area provides little confidence that the proposed scouting framework will be effective in avoiding impacts on significant values,” Milledge wrote.

But a spokeswoman for Santos said the scientific rigour of its surveys was “second to none” and had been designed by experts on each species. The data was then peer-reviewed.

“The EIS has concluded the Narrabri gas project is unlikely to have any significant impact on threatened species and it is now a matter for the NSW independent planning commission and the federal environment minister to make their determination,” she said.

Naomi Hodgson, the Newcastle campaigner for the Wilderness Society, said Santos’s claim there would be no impact was questionable when it still had not made public which parts of the Pilliga forest would be cleared for the project and “its studies seem to massively underestimate wildlife numbers”.

“The federal environment department said the Narrabri gas project would have a ‘likely significant impact’ on 10 endangered species and two ecological communities when it decided the project would need federal approval to proceed,” she said.

“They include the koala, the Pilliga mouse, the spotted-tail quoll, the south-eastern long-eared bat and the regent honeyeater, as well as the Brigalow forests, home to the black-striped wallaby.”

A spokesman for the NSW planning and environment department said it had “asked Santos to provide additional information and clarification on a number of matters relating to the environmental impacts of the project”.

He said the information from the North West Alliance submission, as well as advice on biodiversity matters from the NSW environment and heritage office, was being considered.

The department will refer its final assessment to the independent planning commission, which will make the final decision on the project.