Distribution lines in wetland cell 1 disperse untreated wastewater into the upper sand layer. The proper design and installation of this pressure distribution network which includes pump tank, pipe, electrical controls and effluent pump are critical to maintaining the aerobic environment desired within the soil filters which rest on top of the constructed wetlands.
If properly designed, installed, and maintained, the pressure distribution network will insure that the incoming wastewater is spread evenly over the upper sand layer. A time switch and float switch electrical control combination insures dosing and resting pump cycles. This permits timed control of flow to the soil filters rather than flow based on water use . This control is critical for nitrogen transformation, phosphorus storage, and filtering of organic materials and the often associated disease causing bacteria and viruses (House and Cogger 1985).
Traditional sand filter design includes specifications for the removal of vegetation from the surface as routine maintenance. Since we have discovered that plants are a benefit, rather than a hindrance, it is important to ensure that the plants do not interfere with wastewater distribution.
Each pressure distribution pipe lateral is made of small diameter PVC pipe sleeved within corrugated slotted plastic pipe. Small diameter holes drilled on the upper side of the PVC distribute wastewater along the length of pipe. The corrugate sleeve helps protect the distribution holes from clogging by plant roots. The small diameter distribution pipe is easily removed from within its corrugated sleeve for maintenance.