SEWAGE DEPARTMENT TRAINING PROGRAM
How to Build an Elevated Sandmound Sewage Disposal System
After the sand is installed and raked into shape, some or all of the berm should be placed to keep the sand in place.
Definition of berm material:
Mineral soil containing less than 20% coarse fragments (stones) with no coarse fragment greater than 4 inches in diameter, more stable and less permeable than the sand.
From a practical stand point, the berm soil used should be equal to, or less permeable, than the soil on which it is to be placed.
The berm should extend about a foot higher than the sand to contain the aggregate that will be placed on the sand.