Ponded water is standing water in a closed depression. If present, it can float a septic tank, infiltrate wastewater lines and structures, and prevent a drainfield from functioning properly. The depth of the high water table from the surface of the ground, in inches. Shallow groundwater prohibits the biological and chemical reactions within the soil that make up the final treatment step for wastewater. LOWK The lowest measured value of soil permeability, in inches per hour.
Soil permeability is the quality of the soil that enables water or air to move through it.
Drainfields cannot be installed in soils with permeabilities that are too low, because of the likelihood of the wastewater surfacing. Coarse soils that are very permeable do not perform the necessary filtration of wastewater. This is the steepest slope on the soil map unit. The map unit typically gives a range of slope values, in percent. Overly-steep slopes require special engineering so that wastewater will not surface atop the ground.