Doctoral Dissertations
Date of Award
12-2025
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Civil Engineering
Major Professor
Jon M. Hathaway
Committee Members
John Schwartz, Andrea Ludwig, Sean Schaeffer
Abstract
Urban watersheds result in larger runoff volumes, higher flow intensities, and can transport and concentrate pollutants on land surfaces from anthropogenic activities and concentrate pollutants at the outfall. Conventional stormwater control measures (SCMs) that are positioned at the end of pipe can have limited ability to reduce outflow volumes and peak flowrates. Additionally, SCMs have limited capacity to treat emerging contaminants of concern, such as microplastics, that can have negative ecological and health impacts. Regenerative Stormwater Conveyances (RSCs), a developing green infrastructure design, provides conveyance through dissipating erosive velocities using bioretention pools separated by rock riffles. RSC’s have variable hydrologic performance and case studies investigating environmental and storm conditions’ influence on hydrologic performance and contaminant treatment are limited. This dissertation seeks to address these limitations through three major objectives: 1) characterize the temporal dynamics of microplastics in urban stormflow and identify factors influencing these dynamics, 2) design, construct, and quantify RSC hydrologic performance within an urban watershed, in terms of volume and peak flow reduction, 3) determine the capacity for the implemented RSC to induce microplastic deposition through sedimentation. Within stormflow, microplastic concentrations’ temporal trends were indicative of the front loading within a storm event. Storm characteristics (storm intensity, maximum flow rate, storm duration, and event volume intensity and size) were shown to influence the abundance and distribution of microplastics. In Powell, TN, the RSC reduced normalized volume out and peak flow out by 62.5% and 58.7% respectively, and performance was found to be influenced by seasonal conditions. Groundwater well depths also significantly increased, which provides further evidence of increased subsurface flow paths and groundwater exfiltration promoted by the RSC. Finally, the RSC was found to induce microplastic deposition within the second and third pools, whereas the first pool has lower deposition, which was expected to predominantly dissipate energy. Within Pool 2 and Pool 3, higher average microplastic concentrations were observed for samples near the outer edges of the pool, where low-velocity flow conditions occur. Inlet-outlet comparison of stormflow also showed reduced microplastic concentrations in the outflow. This dissertation demonstrated the pervasiveness of microplastic transport in urban stormwater, as well as demonstrated how RSCs can be used for both the improvement of urban hydrology and pollutant loading, as demonstrated with microplastics.
Recommended Citation
Palino, Gillian M., "REGENERATIVE STORMWATER CONVEYANCES IN POWELL, TN: A PERFORMANCE ANALYSIS AND INVESTIGATION OF EMERGING POLLUTANT REMOVAL. " PhD diss., University of Tennessee, 2025.
https://trace.tennessee.edu/utk_graddiss/13571