Forgione, Erica RoseExcess stormwater runoff caused by rapid urbanization and exacerbated by climate change generates many challenges for public safety and the environment. Large runoff volumes contribute to flooding and pollutants in stormwater runoff pose risks to human and environmental health, including toxicity to the aquatic environment caused by heavy metals and nutrient pollution leading to eutrophication, the cause of harmful algal blooms. An effort is being made to improve the efficiency of existing highway stormwater control systems which have limited performance in terms of volume reduction and pollutant removal. To address this issue, amendment of highway Vegetated Filter Strips (VFS) with a Vegetated Compost Blanket (VCB), a layer of seeded compost placed on an established slope, has been proposed. Compost has high water holding capacity and organic matter content which can immobilize contaminants of concern. However, the high nutrient content of compost poses a threat to net beneficial performance since excess nutrient leaching occurs after application. This research has posed the question: Can a VCB be used as a stormwater control measure (SCM) while avoiding excessive nutrient leaching?The VCB/VFS system was assessed through lab-scale, greenhouse-scale, and field-scale experiments. Hydrologic performance was evaluated in field and greenhouse experiments through evaluation of dynamic flow modification, event volume storage, and cumulative volume retention. Water quality performance was assessed through analysis of Total Suspended Solids (TSS), Nitrate + Nitrite (NOx), Total Kjeldahl Nitrogen (TKN), Total Nitrogen (TN), Total Phosphorus (TP), filtered and total Copper, and total Zinc concentrations. Nitrogen (N) and phosphorus (P) in compost are naturally transformed from organic to inorganic, soluble forms through the microbially-mediated process of mineralization. Nutrient removal occurs through adsorption as compost leachate passes through the VFS soil layer. To further investigate nutrient movement, small scale laboratory experiments were completed to determine the N and P compost mineralization rates and theoretical soil adsorption capacities. Nutrient data from greenhouse and field experiments were empirically evaluated using the lab-obtained mineralization data. Nutrient release was simulated and compared to experimental field data using a new open-source software, OpenHydroQual, which combines hydraulic and water quality modeling. VCBs were found to have a significant impact on both flow and volume reduction, though at the highest flowrates, VCBs were unable to significantly reduce flow and instead acted as conveyance. A useful design estimate for representative storage capacity using the saturated moisture content and wilting point of both the VCB and VFS was determined. Significant TSS removal was observed in both the field and greenhouse studies and particulate metals were largely removed; however dissolved copper leaching was observed in the field experiment, as has been observed previously for some compost in stormwater systems. Highly elevated concentrations of nutrients (as high as 100 mg/L TN and 12 mg/L TP) were observed in the effluent of both field and greenhouse experiments, resulting in net nutrient leaching and concentrations above recommended EPA freshwater limits even after 1-2 years. Additionally, mass loading rates at the field site (as high as 41 kg/ac/yr for TN and 14 kg/ac/yr for TP) were 1-2 magnitudes higher than observed influent mass loading rates (~3.8 kg/ha/yr for TN and ~0.47 kg/ha/yr for TP). Through laboratory mineralization studies, N and P mineralization rates were found to differ between compost batches, with initial nutrient content and age/leaching of compost being important factors. Adsorption experiments indicated increasing P adsorption from compost leachate with increasing soil Al+Fe content. Comparisons to greenhouse and field data showed differences in N speciation, likely due to differences in moisture content and temperature causing differing amounts of nitrification and volatilization. OpenHydroQual modeling showed modest results, with varying levels of accuracy for storm hydrograph simulation and mass release. VCBs are not currently recommended for use due to the risk of nutrient and metals pollution, especially in nutrient and metals sensitive watersheds. However, several impactful factors were identified that may reduce nutrient leaching, including compost composition, compost age/leaching, and VFS soil type.enDissertationEnvironmental engineeringCivil engineeringEnvironmental sciencecompostgreen infrastructurenutrientsstormwaterstormwater control measurevegetated compost blanket