By Izzie Gall. Photography by Ashlyn Kittrell.
Urban green areas do more than break up the monotony of a city block. When designed well, they exemplify the balance of disciplines in the Department of Civil and Environmental Engineering (CEE).
Jon Hathaway, CEE professor and associate director of UT’s Tennessee Water Resources Research Center (TNWRRC), specializes in urban hydrology, or how water moves through urban spaces. He is particularly interested in how green spaces can add multiple dimensions of value to the concrete jungle.
“Natural areas contribute a lot of good to the overall city,” said CEE Professor Jon Hathaway said, the associate director of UT’s Tennessee Water Resources Research Center (TNWRRC). “It’s partly recreation, partly aesthetics, partly animal habitat for animals, and there’s also some really tangible benefits for things that civil engineers are interested in, like stormwater management.”
Rain gardens and other specially designed “green infrastructure” store and filter water, reducing flooding and water pollution during storms. However, the high cost of those installations makes them rare in historically underserved areas, causing disproportionate strain on their storm drains and water recycling systems.
In 2023, Hathaway and his colleagues at the Tennessee Water Resources Research Center TNWRRC, part of the University of Tennessee’s Institute for a Secure & Sustainable Environment (ISSE), received a five-year, $2.6 million grant from the United States Forest Service (USFS) to install a novel, low-cost type of green infrastructure around Knoxville—especially in underserved communities.
Hathaway’s team includes researchers from the College of Arts and Sciences and the School of Natural Resources as well as collaborators from many local organizations, including Socially Equal Energy Efficient Development (SEEED) Knox.
“This is a super interdisciplinary project,” Hathaway said. “Nothing like this works unless you have a good team of people who care and get things done.”
Stormwater Management with Community Impact
Typical rain gardens require specialized soil, pushing installation beyond the financial means of some communities. That inspired the City of Nashville’s former urban forester, Eric Kuehler, to create a low-soil solution called the gravel-tree stormwater system (GTSS).
In a GTSS, the only soil is what comes with the sapling when it’s planted; the rest of the site is filled with inexpensive gravel. As the tree grows, its roots reach down and take up water between the rocks like they would on a rocky riverbed.
When Hathaway helped Kuehler pilot the GTSS, their preliminary results suggested that the new system achieves the same hydrological benefits as other green infrastructure at only one third of the cost.
The first four GTSSs funded by the USFS grant were completed earlier this year through SEEED’s Green Construction Program, which pays young adults in Knoxville to learn sustainable construction skills.
Once Hathaway and his team are satisfied with long-term GTSS performance, they will release the plans for free online—so engineers landscaping sites for office buildings, housing developments, parks, and more will have more options for incorporating inexpensive, effective green infrastructure.
“The goal is to have people in Tennessee and beyond be able to design their own effective, low-cost systems based on GTSS,” said Hathaway. “Rain gardens are always going to have their place. But for places trying to do stormwater management in a more economical way, they can still make a real difference by implementing a system like this.”