When Riley Creek overspreads its bank in Bluffton, Ohio, the consequences don’t stop at the village limits. The floodwater, laden with agricultural nutrients, eventually travels downstream and empties into Lake Erie.
For Katelyn Wagner, the floodwater’s journey is personal. Oregon, Ohio, is her hometown and those nutrient-heavy waters contribute to the algal blooms that threaten the safety of her family’s drinking water.
A civil engineering major at Ohio Northern University, Katelyn is now working on a two-for-one solution. Alongside four classmates, she is tackling a senior capstone project in the T. J. Smull College of Engineering intended to both mitigate Bluffton’s flooding and filter harmful nutrients before they head north.
“Flooding is a real-life problem that affects people and habitats,” she said. “Finding solutions to prevent it helps so many.”
Under the guidance of advisor Dr. David Johnstone, professor of civil engineering, the capstone team is moving beyond the classroom. They’ve spent the year collaborating with Bluffton Village Administrator Jesse Blackburn, the mayor, and city council. This April, they will present their final engineering designs to village officials.
“It’s not a textbook problem where everything is cut and dry,” said Johnstone. “The students have to combine everything they’ve learned to make intelligent assumptions and sound engineering judgment.”
A village under water
Just 10 miles west of ONU’s campus, the village of Bluffton is affected by floodwater whenever two or more inches of rain fall in a 24-hour period, said Blackburn. Due to a variety of factors, including a flat terrain and flooding downstream in Findlay, “there’s just nowhere for the water to go, not a fast way to move it out,” he explained.
These rain events cause the flooding of Harmon Field, home of the Bluffton High School football team, and the high school tennis courts along with several roads throughout the village. Portions of Buckeye Park, Village Park, and Bluffton University also fill with water. In severe floods, water threatens residential homes and commercial establishments and can shut down a portion of heavily-traveled I-75.
“We’ve been chasing this problem for some time now,” said Blackburn.
When ONU engineering professors approached Blackburn about a capstone project addressing the flooding, he immediately recognized the educational value and the benefit of an engineering analysis to guide the village’s decision making.
Engineering a “twofer”
In addition to Katelyn, the capstone team includes civil engineering students Kyle Endsley, Preston Ray, Kolten Berner, and Kaelan Howard. This past fall, they visited Bluffton several times to hear the concerns of village officials and explore Bluffton’s creeks and flood zones. They read newspaper articles on past floods and spent countless hours mastering the hydraulic software system, HEC-RAS, used by the Army Corps of Engineers.
“Learning a completely new software to create a model from scratch was pretty tricky,” said Kyle.
For Katelyn, the careful process provided a lesson in patience, as the team worked through multiple scenarios and simulations.
“Waiting and understanding that the problem wouldn’t be answered after a few questions,” she says, “and realizing you may need to ask more questions, have more conversations, and run even more calculations, was the biggest lesson I learned throughout.”
In December, the team presented three potential solutions to village officials, who voted on one to move forward. They selected the team’s proposal of a large retention pond near the junction of Little Riley Creek and Riley Creek, featuring a controlled inlet and outlet structure. Native plantings around the pond help filter harmful nutrients out of the water.
“The idea is to slow the water down to allow some of the nutrients to settle out, temporarily store the water so downstream flooding can recede, and then release it slowly from the detention pond,” said Blackburn.
Blueprint for resilience
The capstone team is currently finalizing their design plan for their April presentation to the village council, working through scenarios for 25-, 50-, and 100-year floods. Blackburn is optimistic about the far-reaching impact of the team’s solution.
“You’re getting a dual benefit,” he said. “You’re making your local community more resilient to flooding, but also impacting the greater community of the Lake Erie watershed by helping to deal with the nutrient loading of the lake.”
Solving municipal flooding is complicated, he notes. By showing a solution is feasible, the capstone team is providing the village with vital momentum. He commends the students’ professionalism and expert work.
“We presented the problem and gave the students free rein into what kind of creative solution they could come up with,” he said. “They really came through, and this project should be a feather in the cap as they embark on their careers,” he said.