Hey Glenn,
if you mean the unevenness, this is eliminated by flattening the spoilboard.
However if your machine bed is not coplanar (twisted), this cannot be eliminated by surfacing the wasteboard and your machine can only produce twisted workpieces as a result.
Useful for adjusting coplanarity is if you have the QCW Frame which now includes the Any Surface Leveling System, or height-adjustable feet or casters on your table. If the latter is the case, please be aware that rarely a table that is not welded of thick steel profiles and annealed for stress relief is stiff enough not to twist if moved around because of ground unevenness, and that you need to re-check for coplanarity everytime you moved the machine around.