It is necessary to have suitable soil if the drainfield is to function properly. Simply speaking, the most suitable soil would be well-drained sandy soil. However, there is great variation in types of soils within Washtenaw County. It is essential that a careful check be made of soil and drainage conditions before planning the installation and use of on-site sewage systems.
The occurrence of saturated soil, or ground water, is an important factor since the sewage systems drainfield must be installed in well drained soil, at least 2 feet above the highest ground water elevation, in order to function properly. In selecting a building site, factors such as soil drainage, permeability, topography and ground water must be considered and are best determined by a soil evaluation.