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ISSE Project: Stormwater Goes Green? Investigating the Benefit and Health of Urban Trees in Green Infrastructure Installations

Team: Jon Hathaway and John Schwartz, Civil and Environmental Engineering; Jennifer Franklin, Forestry, Wildlife and Fisheries; and Bill Hunt, Biological and Agricultural Engineering, NC State

2014-2015 Report

Project Summary: Trees have many important functions within the urban environment including air quality improvements, wildlife habitat, and mitigation of the heat island effect; however, their contribution to stormwater management is not well understood. The goal of this project is to demonstrate the role of trees in stormwater treatment systems in the eastern United States and beyond, and to make recommendations regarding treatment system design and tree species selection to maximize functionality and health. Tree health and function will be quantified using: (1) a field survey of existing stormwater treatment systems, (2) a laboratory experiment to compare tree performance to other types of vegetation, and (3) a field performance study of tree-specific stormwater treatment devices. Based on the results of these studies, design guidelines will be developed which explain how best to integrate trees into stormwater treatment systems.

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Mesocosm design construction at UT

Progress: During this period, substantial advances were made on the project including completion of the sites visits to support the field survey, laboratory design and concept testing, and surveying / design tasks for the field study. Outreach has also begun between project partners and students/staff from West High School in Knoxville, Tennessee. Six mesocosms were constructed with the help of the high school students to test differences in tree growth based on the presence or absence of a submerged ponding zone. Presentations and hands-on learning were provided to the students to allow a better understanding of tree health analyses and the water quality degradation that has been observed due to urban stormwater runoff in the United States.

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Ph.D. student Andrew Tirpak explains mesocosm construction to West High School students