Regarded as "state significant infrastucture", the pipeline would connect the imported gas, arriving on LNG tankers an unloaded into a floating terminal, to the rest of NSW.

It would run underground from Spring Hill along Masters Rd, then through the back of Sid Parish Park at Figtree, before running west alongside O'Briens Rd and American Creek then turning northwest near Redgum Forest Way.

It would make its way past Cordeaux Heights through bush towards Mt Keira, where it would reach the heights near where Mr Keira Rd meets Harry Graham Dr. There are several options for how this area between the foothills and the mountain would be negotiated.

Once above the escarpment the pipeline would follow Mt Keira Rd to Picton Rd, as far as Wilton.

These details are in a "scoping report" from consultant GHD available on the NSW Major Projects website, for proposed pipeline developer the APA Group.

"The project will transport gas from the Port Kembla Gas Terminal to the existing gas transmission network allowing for flexibility of supply to Sydney, regional NSW and interstate," the report says.

Initial environmental research showed 125 threatened flora and fauna species in or near the pipeline's path, as well as four endangered ecological communities.

Among the more prominent are the koala, which has a substantial population near Wilton, as well as the broad headed snake and vulnerable frog species.

"APA is in the process of selecting a preferred route from a number of preliminary route options," it said.

"Where possible, use will be made of existing infrastructure corridors including other pipelines and powerlines in order to reduce the extent of disturbance required for the project."

The Port Kembla Gas Terminal was given planning approval in April. Last week a "modification" application went on exhibition - seeking permission to more than double the maximum number of LNG ships arriving per year from 24 to 52.

The consultation period for the ships increase was set for two weeks and ends next Wednesday.