Just because he's in a flood plain doesn't mean he has to use piers. You just need to be above the specified height. Regional codes may instruct that piers be used is some places, but outside that, and the possibility of erosion of the support pad, why use piers?
Unless the OP is in a flow path of a flood plain, just fill and build.
Unless the OP is in a flow path of a flood plain, just fill and build.