As Hanson welcomed federal environment minister Sussan Ley's decision last week to approve the expansion, which will see 52 hectares of koala habitat cleared from the Brandy Hill site, campaigners fighting for the protection of koalas were left "shocked" and "frustrated".

"This is definitely setting a dangerous precedent... that's why we were trying to achieve the impossible and win this campaign," Chantal Parslow Redman, a Brandy Hill resident and founder of the Save Port Stephens Koalas campaign, said.

"This Brandy Hill quarry expansion is a gateway project to a lot more that's happening in this area. That's what is really scary. If this has been approved, then what's stopping the 200 hectares of koala habitat in Raymond Terrace, flagged in the Kings Hill development, from being approved or the other major developments around the Seaham and Brandy Hill areas?"

Delivering her decision on October 27, three days earlier than expected, Ms Ley gave the expansion project the final tick of approval but outlined strict new conditions, which included Hanson being required to establish of a 74-hectare koala habitat corridor.

In a statement to the Examiner, Hanson said it had sought to understand the concerns of the community throughout the assessment process.

"This feedback is demonstrated in the expansion plans, which include: re-vegetation of a 74ha koala habitat corridor, conservation of approximately 450ha of vegetation under a biodiversity offset, construction of new bus bays and a shared pathway along Brandy Hill Drive, enclosure of all processing equipment for best practice management of dust and noise [and] a program of community engagement and events," the statement outlined.

"Hanson is committed to protecting all wildlife and recognises the importance of the koala to the Australian community. Over the past six years, the project has been refined to reduce environmental impacts."

The quarry expansion was granted by the Independent Planning Commission in July, but required federal approval because the project had been deemed likely to have a significant impact on a matter of national environmental significance.

The approval will see the Brandy Hill quarry extraction area extend by 55 hectares and the company more than double its rock production from 700,000 tonnes to 1.5 million tonnes per annum.

While the expansion plans had been in the pipeline for many years, it wasn't until it was approved in July that the campaign against the decision, largely based on koala habitat fears and concerns about increased heavy vehicles on the roads, gained greater momentum.

The Save Port Stephens Koala campaign was formed and within three months had gained widespread attention in the media and attracted celebrities such as Olivia Newton John, Jimmy Barnes, Magda Szubanski and Celeste Barber who added their voices to the koala campaign.

Ms Ley had twice delayed her decision about the rock quarry expansion to have more time to consider reports about the site and the impact the project could have on the marsupial's population and habitats, including her department commissioning a study by koala expert Dr Stephen Phillips.

The minister said that study used on-site assessments to map the extent of the koala population and land use. She said the study determined that as few as one or two koalas were present in the proposed construction area.

"This is not a region where bushfires have impacted local populations or habitat, it is not a site that is supporting breeding populations and, having reviewed the department's recommendations, I have approved the proposal," she said.

Ms Parslow Redman, who holds an honours degree in environmental politics and was previously a strategic policy advisor to the Victorian environment minister, and fellow Save Port Stephens Koalas campaign manager Dr Victoria Jack, a practitioner and scholar in the fields of community engagement and crisis communication, said they were concerned with Ms Ley's comments around the Brandy Hill koala population.

The group had crowdfunded an expert report by University of Newcastle scientists (read the report in full below) which found "the area to be cleared contains healthy male and female koalas that are also likely to be breeding" and "the potential impact of the development should be considered in the context of the current declining status of koalas in NSW".

"The minister's decision has not been based on the facts," Ms Parslow Redman said. "She had the best evidence, we provided it to her, she chose to ignore that and use other sources of information. It's really disappointing.

"Her report said that there were only one or two koalas in the area, which is not true. Locals have recorded 120 koala sightings within a 10 kilometre radius of the quarry in the past nine months alone. She also says that the area has not been impacted by bushfires, which makes it more critical than ever to protect because it has been untouched by bushfires and supports an inland koala hub."

The minister's decision also drew anger from Anna Bay resident and past president of the Port Stephens Koalas care organisation, Carmel Northwood.

"After more than 10 years caring for koalas in Port Stephens, I have frequently helped write reports to counter development applications that will compromise the local koala population and have made submissions to government such as the recently published NSW parliamentary inquiry into koala populations and habitat. We rarely gain even a smidgen of success," she said.

"The Brandy Hill quarry campaign has, in my eyes, been successful in opening so many others' eyes to the reality of extinction of wild koalas in our lifetime. It's not just koalas, but all the flora and fauna that will suffer the gradual destruction of 52 hectares of bushland, with only the promise of planting other saplings that may not survive."

Hanson said it has dedicated an area of 74ha on the quarry site to koala habitat establishment, which would be replanted in five stages across 10 years at a cost of more than $2 million.

"The establishment of this habitat will ultimately provide koala habitat that is of greater quality than currently exists as Hanson will also implement supplementary measures to improve the habitat. This includes bushfire suppression, drought protection, appropriate fencing, weed management and feral animal controls."

Save Port Stephens Koalas is encouraging residents to sign the Save the NSW Koalas change.org petition and take part in the Save Our Koalas Week of Action ending November 10.