Characteristics of Shallow Groundwater in An Enhanced Wetland Project along An Urban Stream in Greensboro, NC

The City of Greensboro, NC has designed and implemented an innovative strategy for improving retention and treatment of stormwater in an impacted urban stream, by constructing a dam in the stream channel that is raised following a rainfall event. As water levels rise, the stream flows over constructed berms into the floodplain, where it remains ponded and slowly infiltrates into the soil and presumably discharges back into the stream as water levels drop. This enhanced wetland is proposed to treat common stormwater pollutants such as nutrients and dissolved metals through a combination of processes, including remediation via plants, soil, and microorganisms. Groundwater-surface water interactions are strongly affected at this site as a result of the dam operation, and predictions of bioremediation in the subsurface must take this into account. Data are presented on the hydrologic characteristics of the wetland environment including the extent and response time of water table fluctuations relative to dam deployment, groundwater flow rates and residence time, and basic geochemical conditions. These data provide a necessary foundation for developing more complex models to quantify the level of remediation that is occurring at this site, and to determine if this type of system would be applicable to other urban streams.