This method of waste water disposal is used very commonly in Vermont for high water table or difficult soils conditions.  Waste water disposal systems need to operate in a dry area, and mounds are a way to get the dispersal area high enough to be free of ground water or out of impervious soil horizons.  Water dispersal within the mound takes place in a stone or sand bed, on top of a bed of mound sand.  Dispersal piping may be pressured small diameter piping with small orfices, or Presby large diameter gravity piping. 

The "Squirt" Test - confirms equal distribution of water in the mound.

Typical cross sectional view of a mound dispersal area.