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2012 EPA Research Progress Report

Tapping Green Infrastructure

Researchers examine a soil core for analysis at a potential green infrastructure site in Omaha, Nebraska.

EPA researchers are studying green infrastructure, water management techniques that tap or mimic natural conditions to achieve efficient, sustainable stormwater management systems. Examples of green infrastructure include: rain gardens, rain barrels, green roofs, cisterns, daylighted streams, and retention ponds. The environmentally-friendly techniques of green infrastructure present sustainable options for reducing urban water problems and health risks.

The work will provide cities and local communities with tools and guidance they can use to combat water-quality issues such as flooding, combined sewer overflows, and nutrient impairment.

With research ranging from soil analysis to best placement modeling, EPA researchers are working to inform city managers and decision makers about green infrastructure practices. Research data are also used to inform the development and evaluation of stormwater modeling tools such as the Storm Water Management Model (see A Tool for Urban Stormwater Management in this report). EPA green infrastructure research includes the following.

  • Urban Soil Assessment: Researchers assessed characteristics of urban soils in various locations to inform the development of an Urban Soil Assessment Protocol. By accounting for how excess stormwater will (or will not) move through surface and deeper soils, this protocol helps direct communities when and how to use green infrastructure in an economically feasible way.
  • Guiding Green Infrastructure in Omaha: In collaboration with the City of Omaha and the Nebraska Department of Environmental Quality, EPA scientists analyzed soils and prepared monitoring equipment for the introduction of green infrastructure to selected sites throughout the city. EPA is providing guidance on how the city and state can incorporate green infrastructure into their combined sewer overflow control plan. EPA will also work with the local U.S. Geological Survey to establish monitoring sites around the green infrastructure installations to determine how well they perform with respect to water capture and infiltration.
  • Researchers take samples from a buried stream

  • Daylighting Streams to Improve Water Quality: Researchers recently compared the effectiveness of buried streams (streams routed into underground pipes) versus open-air streams for removing harmful nitrogen from water systems. Early research results suggest that buried streams are less effective at removing nitrogen than daylighted streams—streams above ground and open to the air. These findings suggest that daylighting streams could prove a sustainable method for nitrogen removal and improved water quality. The outcomes of this study and further research will be used to inform a new modeling tool for urban managers. This tool will help identify places within a city where daylighting streams would be most effective.
  • Monitoring Green Infrastructure: Green infrastructure pilot projects are underway in Cincinnati, Ohio, and EPA scientists are monitoring the hydrology (water flow patterns) and water quality at select rain garden and permeable pavement sites. The Metropolitan Sewer District of Louisville, Kentucky is working with EPA scientists to develop a monitoring plan to demonstrate the performance of individual green infrastructure controls and the aggregated effectiveness of these measures on combined sewer flow. Additionally, EPA is monitoring the long-term performance of green infrastructure best management practices at the EPA facility in Edison, New Jersey.
  • Cleveland’s Vacant Lots: Based on technical guidance from EPA experts, Cleveland, Ohio has incorporated a green infrastructure pilot program into its combined sewer overflow consent decree. This program takes advantage of the city’s vacant land, turning that land into greenspaces that not only absorb excess stormwater, but also improve the social and economic fabric of neighborhoods historically lacking greenspace.

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