Urban Stormwater Management

Students are introduced to the sub-units of the hydrologic cycle and urban stormwater management through two lessons: Natural and Urban "Stormwater" Water Cycles and Green Infrastructure and Low-Impact Development Technologies. The lessons maybe be conducted in any order, however students should complete both lessons' PowerPoint® presentations and associated tasks (handout, design scenario sketching) prior to conducting each lesson's associated activities. One activity directly follows the water cycle lesson and three activities follow the GI/LID technologies lesson. The final rain garden activity builds on all the activities—both concepts and materials—as teams construct personal rain gardens that can be incorporated into school grounds or home yards.

In terms of cost, many materials are introduced and then reused in later activities (both expendable and non-expendable items), with most items being pulled together for the culminating rain garden activity.Table 1. The suggested order to conduct the unit's lessons and activities.

Watch a video about the National Science Foundation-sponsored program that generated this unit (7:17 minutes), USF-Green Space Based Learning at https://www.youtube.com/watch?v=8UWeJ8ky43w. Starting at about minute 4, the personal rain garden unit project is discussed, and then images are provided of students involved in the surveying, project management, site assessment, project sizing, excavation, underdrain sample port installation, media layer and planter selection and installation, and final elevation grading to install a bioretention rain garden on a Florida school campus.

Examples of human-made infrastructure that rely on engineers fully understanding the hydrologic cycle include stormwater ponds, earthen dams, levees, treatment facility influent and effluent; sheet, overland and channelized flows; stream flow and base flow. Practical applications of hydrology are found in such tasks as the design and operation of hydraulic structures, drinking water supply, wastewater treatment and disposal, recreational water use, and fish and wildlife protection.

Engineers are involved in analyzing the problems involved in these urban infrastructure tasks and then designing solutions and providing guidance for planning and management of water resources. Civil and geotechnical engineers must have a comprehensive understanding of in situ soil mechanics, groundwater flow and influent runoff in order to properly design systems to manage stormwater. In order to design technologies that address water quality and treatment of stormwater, groundwater and remediation projects, environmental engineers must understand the movement of water as it percolates through different soil layers.

Rain gardens are a promising green infrastructure (as opposed to "gray infrastructure") and low-impact development technology for managing stormwater at its sources using natural means to restore the water quality of developed sites to near pre-development conditions. Rain gardens are typically constructed with high-permeability media, consisting of soil, sand and organic matter, designed to maximize infiltration, improve water quality and promote vegetative growth. (Roy-Poirier, 2010)

Today's engineering graduates and global citizens are charged with the responsibility of creating sustainable solutions to 21st century "grand engineering challenges." (NAE, 2008) From an environmental perspective, rain gardens recharge groundwater, provide natural stormwater management, reduce energy usage, improve water quality, reduce heat-island effects, and increase habitat. Social aspects to consider are the beautification and increase in recreational opportunities, improved health through cleaner air and water, and improved psychological well-being. Economic concerns that are met range from reducing the future costs of stormwater management to increasing property values and tourism.

References

Davis, A. P., Shokouhian, M., Sharma, H., and Minami, C. (2006). Water quality improvement through bioretention media: Nitrogen and phosphorus removal. Water Environment Research , 78(3), 284-293. doi: 10.2175/106143005x94376

Kadlec, R. H., and Wallace, S. D. Treatment Wetlands. Boca Raton, FL: CRC Press, 2009.

NAE. (2008). National Academy of Engineering Summit Series – Face the Challenge http://www.grandchallengesummitorg. Retrieved November 2010.

Roy-Poirier, A., Champagne, P., and Filion, Y. (2010). Review of Bioretention System Research and Design: Past, Present, and Future. Journal of Environmental Engineering-Asce , 136(9), 878-889. doi: 10.1061/(asce)ee.1943-7870.0000227