While urban areas face obstacles associated with overtaxed drainage systems, other environmental challenges are met on open roads and highways. Erosion can easily occur on roadway embankments due to unmanaged water flow across impervious surfaces or temporary construction. To alleviate the erosion impact of construction along highways, state agencies are required to implement temporary plant seeding strategies.
The Illinois Department of Transportation (IDOT) publishes guidelines that set standards for materials and workmanship for all transportation infrastructure construction work in Illinois. This large volume titled “Standard Specifications for Road and Bridge Construction” includes Clean Water Act-mandated erosion control practices, and it suggests a mixture of perennial rye and oat seed for temporary ground cover seeding.
Unfortunately, according to Mark Grinter, assistant professor of construction, these seed varieties are cool season grasses not well-suited to all seasons and locations in Illinois. In 2013, Grinter and his team received a grant from the Illinois Center for Transportation (ICT) to study alternative seed varieties and make recommendations for improving the standard specifications.
The project explores how different varieties may be best employed according to geographic location and time of year. Grinter’s team, which includes Dr. Peter Minchin, associate professor of biological sciences, Dr. Susan Morgan, professor of civil engineering; Dr. Bill Retzlaff, professor of biological sciences; and biological sciences graduate student Irene Weber, is testing sites ranging from extreme southern Illinois to the state’s northern tier. Thanks to a cooperative agreement with University of Illinois research farms and SIUE’s own campus facilities, the researchers have established seed plots at four locations throughout the state. In nearly 3,000 plots, the team is analyzing seed mixtures for germination, growth rates and optimal soil coverage in all four seasons.
While the team is still analyzing results from recent seasonal shifts, Grinter says that it is already clear that the IDOT standard mixture is not the best performing variety. The team looks forward to recommending varieties that will decrease the environmental impact of construction work in Illinois.
In a similar project, Dr. Abdolreza Osouli, assistant professor of civil engineering, is leading a team of investigators who are assisting IDOT to compile and evaluate post construction best management practices to control or retain storm water runoff. After road construction, surface run off may contain contaminated material due the presence of chemicals, oils, grease, nutrients and metals on road surfaces. Osouli’s team will research how to indirectly control the spread of pollution by reducing the volume of storm water runoff.
Many states have incorporated best practices in managing storm water runoff. These can include biofiltration (the use of living materials to filter pollution, as above); control of water infiltration into the soil; the use of retention ponds; the use of detention basins that temporarily hold and control water flow; or velocity-reducing storm water runoff systems. Methods often vary according to the needs of the particular area, its climate, soils and water table.
Attempting to better control runoff and pollution, the Illinois Environmental Protection Agency is changing requirements for construction permits related to water pollution control. These permits are in conjunction with the National Pollutant Discharge Elimination System (NPDES) and will require new and more rigorous methods by the Illinois Department of Transportation.
In order to best understand practices most suitable to Illinois highways, IDOT has awarded Osouli and team a grant to survey national best practices and test their viability for use on Illinois highways post construction. The team, which consists of Osouli; Grinter; SIUE civil engineering chair Dr. Jianpen Zhou and adjunct faculty member Dr. Laurent Ahiablamet; and Dr. Timothy Start, faculty of civil and environmental engineering from UIUC, will inventory best management practices throughout the country. The team will review and test various best management practices, and review their performance monitoring data. The team will also prepare reliable cost estimates for installing and constructing various practices. Finally, recommendations and guidelines will be provided to IDOT to cost effectively manage storm water runoff at the site with these practices.