Wollongong City Council staff say the NSW government should ask for more information before approving changes to the Port Kembla outer harbour expansion, as "a number of key aspects [of the proposal] remain unresolved or unknown".
Last month, the private consortium that leased Port Kembla in 2012 revealed plans to quadruple capacity of the first completed wharf by allowing much bigger ships - and more of them - into the harbour.
The NSW Ports Consortium said it hoped to handle 16 million tonnes of bulk cargo a year, up from a previously approved 4.25 million tonnes at its multi-purpose cargo wharf.
In a draft letter to be considered at Monday night's meeting, council general manager David Farmer said the council "supports the economic benefits from the port expansion" but the proposed 400 per cent increase in bulk cargo was not supported by current rail infrastructure.
Mr Farmer also said the scope of NSW Ports' proposal was too significant to be approved as part of a modification to an existing plan, and requested that NSW Planning refer it to the independent Planning Assessment Commission.
The draft submission also raises a number of freight issues, saying contingency plans and checks were needed to keep the region's roads and rail lines from becoming overloaded.
According to NSW Ports' proposal, no extra road traffic is to be generated by the increased capacity, with the bulk of the extra cargo to be transported by rail.
"[The] council supports this approach, [as] any increase in road freight as part of this modification is not supported as the road network ... is at or near capacity," Mr Farmer said.
However, he also warned that increasing freight without a substantial increase in rail infrastructure would not be possible and recommended that a Rail Master Plan, with clear commitments and time frames for the delivery of rail projects, be developed before extra cargo was shipped through the port.
If this did not happen, Mr Farmer said, new customers taking advantage of the port's increased capacity "may either resort to utilising the existing road network or, if this is not acceptable, be deterred from using the port. Either scenario would be a disappointing outcome."