Northern Kentucky University
Can Constructed Wetlands Improve Stormwater Runoff Quality?
Institution
Northern Kentucky University
Faculty Advisor/ Mentor
Kristine Hopfensperger
Abstract
Waterways in the U.S. transport nutrient pollutants into our estuaries creating large annual hypoxic zones. Constructed wetlands can act as natural filters by reducing nutrient levels carried by stormwater. The purpose of this research project was to examine the function of a constructed wetland by calculating its nutrient flux during storm events. The constructed wetland studied was located at an elementary school in Boone County, KY. Water samples were collected at wetland inlet and outlet locations during five storm events from April through June of 2013. Water quality analyses including total dissolved solids, total suspended solids, phosphorus, ammonium, and nitrate concentrations were performed. Levelogger equipment was installed to provide information on the volume of water in the wetland. A flow meter was added to capture outflowing velocity data. Overall, we found improved runoff water quality from the constructed wetland. Specifically, nitrate, ammonium, and phosphorus levels all showed a decrease in concentration at the outlet compared to the inlet during storm events. In addition, we found that while the wetland was designed to hold water for 48 hours, our volume data showed that the wetland is actually holding water for 72 hours. Holding the water for a longer period of time allows further cycling to occur during larger storm events. The nutrient data combined with the volume and velocity data will be used to calculate total nutrient flux in the stormwater wetland. Our results will be used by the U.S. EPA to help guide green infrastructure and promote stormwater wetland construction in other urban areas around the U.S.
Can Constructed Wetlands Improve Stormwater Runoff Quality?
Waterways in the U.S. transport nutrient pollutants into our estuaries creating large annual hypoxic zones. Constructed wetlands can act as natural filters by reducing nutrient levels carried by stormwater. The purpose of this research project was to examine the function of a constructed wetland by calculating its nutrient flux during storm events. The constructed wetland studied was located at an elementary school in Boone County, KY. Water samples were collected at wetland inlet and outlet locations during five storm events from April through June of 2013. Water quality analyses including total dissolved solids, total suspended solids, phosphorus, ammonium, and nitrate concentrations were performed. Levelogger equipment was installed to provide information on the volume of water in the wetland. A flow meter was added to capture outflowing velocity data. Overall, we found improved runoff water quality from the constructed wetland. Specifically, nitrate, ammonium, and phosphorus levels all showed a decrease in concentration at the outlet compared to the inlet during storm events. In addition, we found that while the wetland was designed to hold water for 48 hours, our volume data showed that the wetland is actually holding water for 72 hours. Holding the water for a longer period of time allows further cycling to occur during larger storm events. The nutrient data combined with the volume and velocity data will be used to calculate total nutrient flux in the stormwater wetland. Our results will be used by the U.S. EPA to help guide green infrastructure and promote stormwater wetland construction in other urban areas around the U.S.