Stormwater best management practice evaluation project looks to quantify effectiveness of mitigation
Testing the Waters…
Nonpoint source pollution is exactly what it sounds like: Pollutants entering bodies of water in stormwater runoff that might be traced back to any number of sources within a watershed area with no definitive way to pinpoint their origins. Streams that run through urban areas are particularly susceptible to manmade pollutants — before entering the stream, stormwater runs across roadways, parking lots, areas under development, lawns, gardens and rooftops.
In 1987, the U.S. Congress amended the Clean Water Act in order to put a face on the problem and implement control measures. States were required to assess and report the scope of the problem and to adopt management control programs. Congress annually appropriates funds to help states address the issues, which are facilitated by each state’s Department of Natural Resources.
In 1998, Hinkson Creek appeared on Missouri’s list of impaired waters, and eventually, urban nonpoint source pollution was listed as the source of the impairment. The 26-mile long creek is entirely contained in Boone County, originating east of Hallsville and running through town to join Perche Creek in southwest Columbia. Several of the creek’s tributaries flow into it from within Columbia.
Residential and commercial development proliferates the square footage of impervious surfaces such as roads, parking lots and buildings in the watershed, which increases runoff and pollutants. Immediate stakeholders in the Hinkson Creek watershed, including Boone County, the City of Columbia and the University of Missouri, in partnership with the Missouri Department of Natural Resources (DNR), formed a collaborative adaptive management (CAM) team to work toward decreasing the number of nonpoint source pollutants entering the impaired Hinkson Creek. A water management plan was generated, and all entities have worked together to move mitigation projects forward.
“All three groups have influence and are co-permit holders,” Enos Inniss, assistant teaching professor in the Civil and Environmental Engineering Department, said of the joint MS4 stormwater permit the three entities hold with DNR under Phase II of the National Pollutant Discharge Elimination System (NPDES). The permit formalizes a coordinated plan to manage stormwater.
A committee of the stakeholders met to discuss possible science-based solutions to problems in the Hinkson watershed, and all three groups moved forward based on the committee’s recommendations.
In 2012, Inniss received a grant from DNR to monitor the performance of stormwater best management practices (BMPs) in relation to reduced water loads and improved water quality following precipitation events on the MU campus. Bioengineering Professor Allen Thompson partnered with Inniss on the project. Resulting data, still being collected, can be used to inform future decisions about the installation of BMPs.
Graduate and undergraduate students from engineering, natural resources, environmental science and the bioengineering program were recruited to help with establishing and monitoring the BMP installations as well as assisting in data collection. Students also work collaboratively on Inniss’ shared projects with the City of Columbia. Such hands-on experience can prove invaluable for students hoping to build careers in water resource fields.
The first BMP to be initiated as part of the grant included the planting of hundreds of willow trees in the Hinkson Creek flood plain in an area where the creek meanders and floods. Volumetric water content probes and a station to measure daily differences in solar radiation, precipitation and wind speed also were installed at the site.
Research shows willows take up and transpire water at a rate that makes them an effective management device for reducing excess rainwater. They also take up potential pollutants. Inniss worked with Associate Professor Jason Hubbart from the MU School of Natural Resources and a team of students to plant the trees — and replant them after deer dined freely on them.
“The trees are to serve double use as biomass,” said Pete Millier, MU’s director of landscape services, of the willow project. Millier is the point person on campus for its 20-year Stormwater Master Plan and a collaborator on Inniss’ projects.
The EPA said, ‘You come up with a plan.’ We were able to utilize real-time research to help mitigate the problem,” said Millier of the collaborative efforts, adding that the results will influence future decisions.
Plans for construction of an animal resource center on the southeast side of the MU campus offered an opportunity to build stormwater BMPs that would include monitoring equipment to test their effectiveness. Working with campus to approve the designs, the research team instrumented two bioretention cells to capture and measure runoff and analyze the contents of the water going in and coming out.
“We are interested in how much is being retained in these features and if they’re helping,” said Inniss.
Both rain gardens and bioretention cells are shallow indentations that capture water and hold it for a brief time, decreasing the amount of water flowing into and overflowing waterways. They often are constructed with amended soil mixtures and always include a vegetative element, which can be nondescript or quite beautiful. Both BMPs also are intended to remove pollutants and sediment from the water.
Bioretention cells are more engineered BMPs and are designed with specific criteria in mind. A pipe installed at the bottom of one of the cells Inniss’ group put in place connects to monitoring equipment and also discharges the water into a storm sewer. Rain gardens are a passive version of the bioretention cell.
“Having plants is a critical component,” said Inniss. “We were able to involve environmental science students in this part of the project. They were most interested in native plants that can tolerate both wet and dry periods.
“But the idea that once these features are in place you don’t have to worry about it just isn’t true,” Inniss added. “These are essentially gardens, and so they take some maintenance.”
The campus commitment to improve stormwater quality is ongoing. Millier said that in 2013, there were only four BMPs on campus, and by year-end there will be 38. The campus has installed permeable pavement that filters pollutants and reduces stormwater runoff in places such as Traditions Plaza and near new residence halls. They have constructed wetlands, built vegetative swales and added green roofs to new construction.
“We are working to include these elements in all new development,” said Millier. “It’s not something trendy. It’s what we do. And it’s a lot of fun to see this come to fruition.”
In addition to campus BMP installations, Inniss and student assistants have been testing the efficacy of soil mixes in his lab to see if any are more effective at retaining water and at removing contaminates from water.
“We’re asking questions about the soil,” said Inniss. “Can we do modifications to the soil to make improvements for bioretention?”
Inniss said the basic soil mix they are using is approximately 60 percent sandy loam with added compost and clay. They are testing six variations on the formula.
“One has mulch on top. Things like oil are captured on the surface,” Inniss said.
“Dirty water has negatively charged particles; you add metals that are positively charged, and they bind together and fall out,” he said of another of the soil mixes.
Franck Noupin, a civil and environmental engineering student from Africa, is one of the undergraduates working with Inniss. He said the projects he has been doing with stormwater and soil testing will give him a good start on his future as an engineer.
“In my country, we don’t have good quality water. It will be good to have some knowledge,” he said.
Over the summer, Inniss, Noupin and other students worked with Mike Heimos, the City of Columbia’s water educator, to install a more extensive soil composition test out at the City’s Grissum Building using a series of 150-gallon tubs. Heimos and Inniss have collaborated on a number of projects, and Heimos hires MU students to help with the City of Columbia’s stormwater efforts.
“We are looking at rates of drainage, temperature and pollutants in and out,” said Heimos of the soil tests.
Columbia’s Public Works Department also received a grant from DNR to install several stormwater BMPs on the Grissum site for practical and educational purposes. The grant additionally provided funding for a variety of stormwater management features to be introduced into a subdivision in the Hinkson Creek watershed.
“There are 200 BMPs citywide, 50 of which have been installed by the city — a lot of stormwater infrastructure. We’re way ahead of the curve,” Heimos said. “I get calls from cities like San Antonio, Texas, and Charlotte, N.C., who are just starting to do this, wondering what we’ve done and how we did it.
“A lot of calls are from college towns, but they just don’t have the kind of relationships with the university as we do here. They don’t collaborate. But everyone here is phenomenal. I can call Pete Millier, and he will ask, ‘What do you need and how can I help?’” Heimos said. “My partnership with Inniss is really good, too, and he is good at what he does. He is what a college professor is supposed to be.”
Inniss is working on final reports for the three-year DNR grant, but, he said, three years of data is not enough.
“We have data, but we don’t feel it is the maximum response to the stormwater issue,” he said. “It has been a learning process with a steep curve, and we don’t have all the answers so we will continue to collect data to tell the story.
“As a water quality guy, this is a great opportunity for me and for my students.”