Protecting public health and water quality is the goal of an onsite wastewater treatment system. Many treatment technologies are available to meet this goal. The selection of an appropriate technology is dictated by site and soil conditions and by state and local regulations. Mound systems are one type of onsite treatment technology.
When a standard absorption field system is not suitable for onsite sewage disposal based on the site conditions and soil characteristics, a mound system may be used. A mound system can create suitable conditions for disposal above the natural soil surface. After treatment by a sewage treatment system, the effluent flows to a dosing chamber. From there it is pumped to the mound for further treatment and ultimate disposal. Figure 1 demonstrates the cross section of conventional soil absorption and the mound system in relation to ground surface and limiting conditions.
Figure 1. Cross section of conventional soil absorption unit (a) and the mound system (b) in relation to ground surface and limiting conditions. (After Converse and Tyler, 1990, Wisconsin Mound Soil Absorption System: Siting, Design and Construction Manual, University of Wisconsin-Madison.)