The oil and gas company Woodside Energy has applied for federal approval for dredging and pipeline construction in waters near the Western Australian Dampier Archipelago marine reserves.

The company has sought the approval as part of its proposed Scarborough gas project, an offshore development about 380km from the Burrup peninsula that would use a 430km pipeline to transport gas to its existing Pluto liquefied natural gas facility on the peninsula.

A development proposal for the state waters component of the project was published by the federal environment department on Christmas Eve. Under environment protection and biodiversity conservation regulations the public has only 10 business days to comment once a referral is published.

Other components of the Scarborough project, including those in commonwealth waters, will be the subject of separate applications to other government agencies, including the National Offshore Petroleum Safety and Environmental Management Authority.

The proposal published on Monday includes the dredging of up to 2.7m cubic metres of the sea floor of Mermaid Sound – up to 1.6m cubic metres of which will be located in state waters – for the installation of 32.7km of steel pipeline adjacent to an existing trunkline.

In the application, Woodside says it believes the proposal does not require a full assessment under the Environment Protection and Biodiversity Conservation Act because it “does not consider that the elements of the proposal that have been assessed, involve an action that is likely to have a significant impact upon matters of national environmental significance (MNES) or other protected matters”.

The document says the company had assessed the potential for direct and indirect impacts on the Dampier Archipelago, located 1.6km from the proposed pipeline at its nearest point, and found potential for indirect impacts on water quality as a result of dredging.

The proposal also says marine species could be affected, including the endangered loggerhead turtle which has been found in locations that intersect with some of the development area. Direct risks included “vessel strikes and/or entrainment during dredging”.

A spokeswoman for Woodside said the project’s scope was “essentially a repeat of the Pluto trunkline scope that was completed in 2008-2009”.

“An extensive environmental monitoring program was conducted for Pluto, which confirmed that impacts were limited to significantly less than permitted under both state and commonwealth approvals,” she said.

“This monitoring data, associated research, and similarity with the previous scope means that impacts and risks can be confidently and reliably predicted.”

The spokeswoman added that the original Pluto development had also involved port construction and 14m cubic metres of dredging and the volumes for the new proposal “are significantly less”.

But conservationists said the project was complex and questioned why the development proposal had been put on public exhibition immediately before the Christmas shutdown period.

“When in Scott Morrison’s Christmas address he said this a time for ‘barbecues, boardies, holidays, family’, it makes you wonder why Melissa Price’s department started the 10-day public consultation period on Christmas Eve for one of the most complex projects ever assessed under the EPBC Act,” said Tim Beshara, the Wilderness Society’s federal policy director.

Beshara said the project had the potential to impact on the health of the ecosystems in the marine reserves that surround the excavation zone, particularly some newly discovered corals and sponge beds.

“The former owner of this gas project had tried to avoid unnecessary environmental damage by proposing to set up a floating processing plant, but Woodside, the new owner, has chosen against doing this,” he said.

He called on the environment minister, Melissa Price, to immediately extend the public notification period “to show that this wasn’t timed to minimise public scrutiny for a project approval for a Liberal party donor”.

A spokeswoman for the environment department said the referral had been processed on 20 December and had been automatically registered and put out for public comment for 10 days “as per normal process”.

The department has 20 business days to determine if the project is a controlled action that requires further assessment.

“Woodside have stated in the referral documents that they do not believe this is a controlled action under the EPBC Act, but as is normal practice the department will review the referral material and comments to determine this in January,” the spokeswoman said.

Woodside’s spokeswoman said the proposal had also been submitted to the WA Environmental Protection Authority and this had not been published yet for public comment.

“Noting that the commonwealth public comment period is open until 10 January 2019, Woodside would support extension of the commonwealth public comment period to align with the state, if deemed necessary by the Department of Environment and Energy,” she said.