Preparing an area for a building may not be properly prepared just because it looks good.  Proper compaction of new granular fill used to prepare a site is paramount.  The type of equipment used, and the depth of the new fill will dictate how many times it must be compacted.  The most common equipment used to compact residential sites is a plate compactor.  Their specs vary slightly, but most will compact a maximum of an 8” lift which means care must be taken to not exceed the capabilities of the compactor being used.  Economy Garages’ standard is to place and compact material at lifts near 4”, half of the specified maximum.