Wastewater from the house is collected in an underground septic tank. Effluent is pumped through a line buried below the frost line. Many local regulations and guidelines must be followed, to ensure that the pump out location is far enough from property borders and buildings. Lot size, location and environmental impact are factors that have to be address before a system like this can be installed. Some available options to discharge effluent are as follows:
Mound System When site restrictions exist such as slow soil permeability, shallow soil cover or property setbacks a mound system can be installed. A mound is a drainfield that is built above the natural soil surface. The mound is composed of a sand fill that has a gravel-filled bed and a network of small diameter pipes known as the distribution system. From the pump chamber, effluent is pumped through the pipes in controlled, low pressure doses so that uniform distribution is achieved throughout the bed. Treatment occurs as the effluent moves through the sand and returns to the natural soil.
Drainfield A drainfield is a network of perforated pipes (or “laterals”) laid in gravel-filled trenches or beds. Effluent trickles out of the pipes, through the gravel layer, and into the soil where further treatment occurs. The soil filters the wastewater as it passes (or “percolates) through the pore spaces and the soil microbes treat it before it eventually enters the groundwater. These processes work best where the soil is somewhat dry, permeable, and contains plenty of oxygen for several feet below the drainfield.
Open Discharge When local building codes allow for a pump out system effluent can be simply discharged onto the ground. Lot size and setbacks from property lines and buildings have to be maintained for this type of a system to be used.