An above-ground, or mound, septic system uses a mound of special sand placed on top of the ground to replace the function of a soil leaching field. This type of septic system is used to handle sewage when the chosen location does not have sufficiently deep, well-drained soil to build a standard system.
An above-ground system consists of two tanks, a pump and a mound. The first tank collects the solids, which need to be pumped out at regular intervals. The liquids flow into a second tank. A pump is used to transfer the liquids from the second tank to the top of the mound of sand. The liquids filter through the sand before reaching the underlying soil. The sand removes any remaining solid waste and treats the wastewater to remove disease-causing organisms and ammonia.
A regular septic tank system consists of a tank and a leaching field. The tank collects the solids, which are pumped out regularly, and the liquids seep into the leaching field, which is an area of deep, well-drained soil. The process of seeping through the soil filters out any remaining solid sewage and dilutes out the ammonia into harmless concentrations. The action of soil bacteria destroys any disease-causing organisms in the sewage. A large area of soil is typically used to treat the sewage. The mound used in above-ground systems creates an artificial area of soil that does not need to be as large.