A mound system is an engineered drain field for treating wastewater in places with limited access to multi-stage wastewater treatment systems. Mound systems are an alternative to the traditional rural septic system drain field. They are used in areas where septic systems are prone to failure from extremely permeable or impermeable soils, soil with the shallow cover over porous bedrock, and terrain that features a high water table. History The mound system was designed in the 1930s by the North Dakota College of Agriculture. and was known as the Nodak Disposal System. In 1976, the University of Wisconsin studied the design of mound systems as part of the university's Waste Management Project. This project published the first ever design manual for identifying the appropriate site conditions and design criteria for mounds. In 2000, a new manual was released. Suitability Mound systems are used to help purify and transport water efficiently. Some soils are too high in permeability, allowing water to quickly pass through it, hindering purification effectiveness and allowing contamination to spread to nearby water sources or ecosystems. . Areas of low soil permeability, such as areas with high water tables and limited soil cover over porous bedrock, can result in contaminated surface pooling. Design The mound system includes a septic tank, a dosing chamber, and a mound. Wastes from homes are sent to the septic tank where the solid portion sinks to the bottom of the tank. Effluents are sent to a second tank called a dosing chamber, from which they are distributed to the mound at a metered rate (in doses). Wastewater is partially treated as it moves through the mound sand. Final treatment and disposal occur in the soil beneath the mound. The mound system does not allow all the effluent to enter the mound at once, accordingly allowing it to clean the effluent more effectively and helping keep the system from failing. The absorption mound is built in layers. The layer depths are determined by the depth of the limiting layer of the soil, which may be a seasonal water table, bedrock, fragrant, or glacial till. Standards created by Ohio State University state that 24 inches of soil should be above the limiting layer in the soil. A 24-inch layer of specifically sized sand is placed on top of the soil. The distribution pipes that are fed by the dosing chamber are placed on top of