ABSTRACT
The resting drain field serves as backup system should the operational drain field need repairs. When replacing a drain field which has become clogged, it is wise to keep the clogged drain field as an alternate. This alternating of drain fields is most beneficial in soils with slow percolation rates and where the application rate of effluent into the soil is very high. Elevated drain fields are used where conventional subsurface drain fields cannot be installed due to limited soil depth above bedrock or ground water. A very important design consideration for elevated drain fields is that of the system elevation as compared to the septic tank and house sewer. In many areas where there is extremely porous subsoil, slowly permeable soil, a high ground water table, or shallow soil above bedrock or other relatively impermeable layer, an elevated drain field cannot be raised high enough to provide adequate separation distance between the disposal excavation and the limiting soil condition.
