Professor Deborah McGrath was in the weeds on this one. In fact she was pulling the weeds. It was a hot day in early June, and a complex process to design and build a constructed wetland, an innovative wastewater treatment system, was about to come to fruition. A few days later, a landscape crew would come to plant native bulrushes and other wetland plants in the new facility, but for now, McGrath and several students were pulling the weeds that had sprouted in the imported topsoil.
In reality, McGrath has been in the weeds for more than two years, paying close attention to design and construction on the wetland. “It has been a learning experience for all of us,” McGrath says, “and I am really grateful for our longstanding collaboration with the Sewanee Utility District, as well as for the work of our design firm Golder Associates and the construction contractor, LTS. I am an ecosystem ecologist and my faculty colleagues teach chemistry, forestry and law, so construction and design are out of our comfort areas.”
The opening of the wetland is the culmination of a vision years in the making. A decade ago, with an interest in how a changing environment affects human health, McGrath and colleagues at Tennessee Tech began testing for pharmaceutical compounds in the wastewater effluent and streams from Sewanee’s innovative waste treatment system. Without a large river to dilute effluent at the end of the treatment process, the Sewanee Utility District (SUD) Board opted for a land application system. Wastewater effluent at the end of the treatment cycle is sprayed on the forest, and trees take up the remaining nutrient load. The system works great for typical contaminants, but McGrath and chemistry professor Emily White were finding evidence that certain classes of pharmaceuticals were making it through the treatment process and into the streams draining the SUD watershed. Recent studies show this to be true for most water bodies where wastewater effluent is being released.
“These are emerging contaminants that the EPA understands may need to be regulated but that no one has a good idea how to regulate or cost effective ways to treat,” McGrath said one day to a colleague. That colleague was Laurie Fowler, C’80, a professor and an executive at the River Basin Center at the Odum School of the University of Georgia. For her part, Fowler had read about the possibility of constructed wetlands as wastewater treatment tools and proposed a joint project between the Odum School and Sewanee to test such a system as a way to track and sequester emerging contaminants.
Along with forestry professor Scott Torreano, and chemist Emily White and colleagues at Georgia, the team put together planning documents through linked courses at the two institutions. That work formed the basis of a grant proposal to the Coca-Cola Foundation, which was interested in the novel project, thanks in no small part to the advocacy of Claude Nielsen, C’71, chairman of Coca-Cola Bottling Company United, which also provided funds for the project. The Coca-Cola company is widely known for its interest in water quality and has a multi-year, multi-continent project to replenish with clean water as much water it uses in the manufacture and distribution of its products.
Another foundation, the Riverview Foundation of Chattanooga, added on a grant to support the public scholarship being conducted by a University of Georgia graduate student and Sewanee Environment and Sustainability major Emmie Oliver, C’16, that charts public perceptions of water and water treatment.
In late June, two years after the ceremonial groundbreaking, student interns Megan Hopson (Environment and Sustainability C’17) and Anna Williams (Chemistry C’19) turned a valve to release water from the SUD lagoon into the constructed wetland. Less than a week later, the wetland is teeming with tadpoles and a kingfisher flies around sizing up potential meals as Hopson and Williams start a regime of water testing. “We take samples from the source and then as it enters and exits each basin of the wetland,” says Hopson.
Three basins comprise the wetland—the first planted with bulrushes, the second with swamp milkweed, blue flag iris, boneset and swamp hibiscus, and the third with pickerel weed. In addition to being planted with different native plants, each basin has a different planting pattern, each designed to promote different ecosystem processes that lead to chemical breakdown.
For now the water testing regime is designed to test the basic operations of the wetland, charting changes in nitrogen and phosphorus, biological oxygen demand, dissolved oxygen, pH, and conductivity as the wetland plants grow. When the wetland is fully operational, research on emerging contaminants will begin in earnest.
“We are really hoping to build partnerships not just with Georgia but with researchers nearby and abroad who are interested in this subject,” says McGrath. “We are going to have a one-of-a-kind facility, equipped with a weather station set up by the Office of Environmental Stewardship and Sustainability, and SUD’s onsite wet lab facility. We are here at the top of our watershed, so we know that the water coming into our public utility is basically impounded rainwater. We have a very clear understanding of inputs to the terrestrial system coupled with the wetland, and so we can have some meaningful results when we measure what is coming out the end.” Extensive monitoring of the vegetation and soils in the forest irrigation area has been yielding results since the late 1980’s.
The challenges of attracting research dollars and research colleagues is stretching into the near future, but for now McGrath still has weeds on her mind. As a kingfisher noisily flies over our heads, she says, “Look at that crabgrass. This basin has been flooded for a week, and it’s still growing. I hope it doesn’t take over the bulrushes.”
As the tadpoles from nearby tree frogs attest, the wetland promises to provide habitat for all sorts of amphibians, birds and other vertebrates, as well as an excellent opportunity to study how the chemistry of the system changes as plants, animals and microbial communities become established in the new wetland. “The project is a wonderful site for interdisciplinary research and exploration,” says McGrath, “from chemistry to ecology to public policy. We are so excited about the opportunity it presents for us and many other researchers.”
Gifts to Stronger Truer Sewanee established the wetland and can now help Sewanee researchers realize its full potential through gifts supporting research and internships.
If you are interested in a gift that goes beyond current-use dollars, named endowed internship funds begin at the $100,000 level. Named endowed scholarship funds begin at the $150,000 level for the College and $75,000 for the School of Theology.