At a 15.5 tonne axle load, that'd work out to 95 tankers a day, based on a 20-tonne tare weight. Do QR have that much capacity in terms of motive power and route-qualified crews for that corridor?
Aurizon has spare crew and locomotive capacity at Willowburn (Toowoomba) due to falling coal demand on the West Moreton system to handle an upswing in the south, while the Mt Isa Line and North Coast Line should have crew and locomotive capacity as the cattle season winds down and GrainCorp contract ends. Aurizon has several sets of container wagons stored between Ayr and Gympie at the moment that could be used, plus the cattle sets could have their crates removed and used to carry tanktainers as well. Using two-TEU wagons, 47-wagon sets could be run throughout between Richmond and Stanthorpe. It is almost certainly doable, just a matter of someone funding it.
As stated earlier, running trains out of Toowoomaba would be a more sensible solution.
Currently advanced planning is underway to move 1.6-megalitres in 45 semi-trailer loads of water per day from Warwick to Stanthorpe (pop,5,400) at a cost of $2-milliion per month, however Warwick's Leslie Dam is already down to 5% capacity.