What is the minimum original soil depth specified for a mound preceded by a treatment technology identified for Treatment Level A?

The minimum original soil depth specified for a mound preceded by a treatment technology identified for Treatment Level A is set at 12 inches. This specification is crucial because it ensures that there is enough unsaturated soil material to effectively filter and treat the effluent before it reaches the groundwater. A depth of 12 inches allows for the necessary biological and physical processes to take place, which are essential for the degradation and removal of pollutants. Adequate soil depth supports optimal drainage and promotes the natural purification of the wastewater, ensuring environmental protection and compliance with health standards. This depth also provides enough space for the root zones of any vegetation, which can further enhance the treatment process by utilizing nutrients and improving soil structure.