Green Infrastructure on UT Campus
On the main campus of the University of Toledo (UT), Dr. Cyndee Gruden led two stormwater demonstration projects which will be monitored by UT students. These projects are part of a series of projects in Lucas and Wood counties which are measuring the effectiveness of green infrastructure. See the case study of a project in Oregon on the TMACOG blog here.
Dr. Gruden’s goal is to make direct observations and measure chemistry and flow from the installations in order to build up hard data on the usefulness of various stormwater control strategies. The studies will help guide people deciding how to incorporate stormwater management installations in new construction or in redevelopment projects. Dr. Gruden’s work is complemented by the data collection program being managed at TMACOG. (See the previous article) She noted that the data collection managed by TMACOG is “really important.” The combination of the data and the practical costs will provide planners with valuable information.
Dr. Gruden said that in the eastern part of Ohio, the beneficial effects of green infrastructure are more obvious due to native soil conditions. Bioswales and other structures can infiltrate stormwater easily. In northwest Ohio where much of the land is flat and the soil is sand and clay, more research is needed to see what strategies are most effective. The project at the campus is particularly challenging because the area where the projects are installed has been the site of construction projects, riverbank stabilization, and channelization. The soil was mostly construction fill and clay.
The projects at the University of Toledo include a bioswale between a parking lot and the bank of the Ottawa River adjacent to Savage Arena, and a tree filter at the upstream end of the campus. Water from four catch basins in a parking lot near the Law School is directed to the tree filter. The system includes a concrete box, open on the top, sides, and bottom. Soil underneath the open bottom is engineered to allow drainage and a perforated pipe is installed beneath that. The pipe collects any water that drains that far into the soil for discharge. Dr. Gruden noted that during a ¼-inch rain her students observed, 5,000 gallons of water went into the filter and none came out. All the stormwater filtered through the soil and either returned to ground water or directly to the Ottawa River. “Nature is awesome at cleaning things up,” said Gruden. “We mimic nature because it works.”
In some projects that Dr. Gruden is studying, data is collected by pumps which take stormwater samples on a regular basis during rain. On the UT campus, students are collecting samples looking at metals, bacteria, nitrates and phosphates, and solids. Students are also using computer models to predict the amount of rain flowing to and from the demonstration projects. Some of the early student results have been interesting. Dr. Gruden noted that student studies show that snowmelt is actually dirtier than rainwater. The theory is that as snow sits in a parking lot, particulates from the air are deposited and water melting in the parking lot and running through the snowpack leaves its petroleum and solids in the snow.
Construction of the projects on the UT campus was funded by a grant from the Great Lakes Restoration Initiative, Surface Water Improvement Fund. The monitoring projects are funded through a small grant from the University of Michigan Water Center Graham Sustainability Institute. That grant began in 2013 and runs through June, 2015. A final report will be published in August, 2015.