If you can be bothered (I wouldn't, so don't blame you) the Burswood site is discussed in some detail further back in the 40 pages of this thread.
It pretty much comes down to yes, it's a terrible site to build on. Most of the land near the Swan River was swamp or a part of the river itself at some point. The alluvial soil moves alot under loading not to mention the water table being high in this area so there is also water flowing beneath the ground. And then there is the issue that some of the site used to be a rubbish tip and concrete factory so there are pollution and chem hazard issues as well.
All that being said, geotech engineering goes pretty well these days and there's some pretty strong rock further down to pile into so it should work fine with some extra $$ thrown at the project.
Cheers mate . Wonder if the extra $$ is worth it....