IMPORTANCE OF SEPARATION FROM GROUNDWATER
Percolation systems’ release of wastewater into soil presumes the ability of soil to continuously absorb it and carry it away. Groundwater rises and falls following with rainfalls; if it rises high enough, a percolation system will fail. Think fixtures that do not drain, open puddles above your septic tank, etc. Generally, one or more holes are drilled deeply as part of a percolation test/report to assess groundwater depth, and a temporary groundwater monitoring well is placed to allow subsequent depth checks. County rules and interpretations on distance to groundwater avoid this condition.
The county also critically reviews percolation system designs because of the potential adverse impact they threaten to the common groundwater resource. Wastewater release presumes natural attenuation of key constituents and pathogens before encountering the water table, again informing approval based on groundwater depth.