STORMWATER TREATMENT SYSTEM/APPARATUS

A method and apparatus for treating contaminated stormwater runoff from roads and adjacent lands. A multi-stage and self-contained system designed to collect the "first flush" of stormwater runoff (which contains the majority of pollutants) and to treat the pollutants using sedimentation, filtration and constructed wetlands. The apparatus is mass-produced to provide standardized hydrologic controls, important to the reliability of the constructed wetland component of the apparatus. Raw stormwater enters the central sedimentation chamber of the apparatus which is divided into multiple segments designed to provide a series of sedimentation/filtration chambers. Each chamber is divided by a removable filter bulkhead sequenced from coarse to fine sediment sizes. Effluent from the final sedimentation chamber is discharged to the constructed wetland system which surrounds the central sedimentation basin. Water flows through the perimeter wetland system in subsurface/saturated conditions and contacts the root zone of the constructed wetland where biochemical interactions attenuate pollutants. Hydrologic control valves in the apparatus regulate the flow of water from the sedimentation basin to the wetland and the effluent discharge rate out of the wetland. This control and the standardization of the construction allows for precise hydrologic controls designed to provide a 5-10 day holding time within the apparatus.