Planting Strategies for Constructed Wetlands for Stormwater Treatment

Constructed wetlands used for stormwater management must be able to adapt to continually varying pollutant loads and volumes of stormwater runoff. Where treatment wetlands are also being used for mitigation, development and maintenance of a proper wetland habitat are key elements to receiving credit. Success of a wetland to effectively treat runoff and maintain the proper habitat can be attributed in part to the types of vegetation and relative location within the wetland with respect to inflows and water depth. Literature suggests that the failure of many constructed wetlands in either of these goals can be attributed to poor planning of planting species and position. The following paper presents the results of several experiments which tested establishment, survival, and biomass accumulation of three types of common wetland vegetation in "bucket" and bench scale wetlands. Typha spp., Scirpus spp., and Phragmites spp. were assessed under various combinations of establishment time, duration of exposure to pollutant loads, and concentration of pollutant load. Results are used to develop effective strategies for planting constructed wetlands to enhance development and survival of constructed wetland systems used for stormwater management and mitigation credit.