VERTICAL SEPARATION DISTANCE

(Water Quality) A phrase used to describe the distance between the bottom of a sewage septic system's drain field and the underlying water table. The separation distance allows Pathogens (disease-causing bacteria, viruses, or protozoa) in the effluent to be removed by the soil before it comes in contact with the groundwater. Many different factors can affect pathogen removal and directly impact the separation distance needed for removal, including temperature, seasonal high groundwater tables, groundwater mounding, and soil type.