From what I understand...
This intermodal proposal would be north of the railway, in farmland on the Adelaide side of APC. This is what is shown on photos on that sign posted earlier.
Big W DC is south of the railway line. Like I said, they were looking into rail access and they already rail a fair bit of what they offload, usually to the NT I believe.
Anyway, I'm not sure how much connection (if any) there is between the two topics.
One other thing, apparently TFI have been looking into building a meat works out there after the Murray Bridge site burned down earlier this year. No doubt they would they would benefit from rail access as much of their meat is loaded in shipping containers for interstate or export at Outer Harbor.
A fair bit of this is 'word on the street' from people I know who work at these places, but at least there's major companies taking an interest in rail freight at Monarto South.