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Novel application promises cleaner waters, better management

In the future, we may see cleaner streams, lakes, and bays thanks to an innovative approach to management of stormwater runoff that is being developed by a team of researchers from Virginia Tech’s Via Department of Civil and Environmental Engineering, Virginia Water Resources Research Center (VWRRC), and Center for Geospatial Information Technology (CGIT).

    Map of management plan to control stormwater runoff pollutants

A novel software application will help engineers and planners select the most effective site specific methods of controlling the amount of pollutants that enter receiving waters through urban stormwater runoff. These methods are called best management practices.

The project is funded by the United States Environmental Protection Agency and brings together Kevin Young, engineering research associate, Tamim Younos, VWRRC associate director and research professor of water resources in the geography department, David Kibler, professor of engineering, Randy Dymond, CGIT co-director and associate professor of engineering, and engineering graduate students David Lee and Dan Phipps.

Stormwater runoff, a major pollutant source

   

Trash accumulated on a stormwater drain Trash often accumulates on stormwater drains after heavy rainfall.

The Congressional Research Service reported in 2007 that up to 50 percent of water pollution problems in the United States are attributed to urban stormwater runoff. The pollutants are washed off of the roads, parking lots, or other surfaces by stormwater and include toxic motor oil, pesticides, metals, bacteria, and trash.

For many years, civil engineers have used a variety of methods to control the stormwater runoff and contaminants that enter surface and ground waters with varying degrees of success. A widely used approach to manage stormwater runoff is to build detention ponds near commercial or residential areas, regardless of the actual construction site needs and conditions.

“The stormwater is directed to a detention pond where gravity takes over, depositing sediment and some pollutants onto the bottom,” says Younos, who serves as project coordinator. “The pond overflow which still may contain dissolved pollutants reaches streams, rivers and lakes, and possibly groundwater.”

Other best management practices are trenches and porous pavement that allow the stormwater to infiltrate into the ground, vegetated wetlands, and sand filters that help filter the pollutants and proprietary stormwater technologies such as hydrodynamic separators.

New tool will eliminate guesswork

Traditionally, the selection of best practices has been done only by proficient stormwater experts guided by little more than vaguely written regulations, experience, and intuition. “They rely heavily on past knowledge, tradition, or even personal preference for particular methods of controlling stormwater runoff,” explains Young.

   

Pollutants entering retention pond The management plan aims to control the amount of pollutants entering retention ponds.

Young adds that often personal bias has led to “cookie-cutter” solutions to very complex stormwater management needs, resulting in poor pollutant control.

The new best management practices selection approach developed at Virginia Tech uses the Analytical Hierarchy Process (AHP) Optimization Tool. This approach factors in dozens of site-specific criteria such as soil types, land slopes, maintenance accessibility, and cost so optimal solutions for a particular location can be selected.

“Our technique is expected to reduce the [best management practice] selection time and minimize human error from such a complex process,” says Younos. The new tool is not designed to replace professional judgment, but rather enhance it with the most accurate information available.

Young developed the principles of this novel approach to managing stormwater runoff in his master’s thesis, under the guidance of professors Kibler and the late G. V. Loganathan.

Other project stakeholders include the New River Planning District Commission, Virginia Department of Environmental Quality, and Virginia Department of Conservation and Recreation.

    Bio-retention best management practice example near the Smithfielf parking lot on campus.

The software, expected to be completed in summer 2008, will be available for free to all interested engineers and planners, localities, and best management practice-review authorities. It will be applicable in areas with geographic and climatic environments similar to those of Virginia.

  • For more information on this topic, contact Ana Constantinescu at arconsta@vt.edu or (540) 231-8490.

Did you know?

Common contaminants in U.S. waters include a variety of sediments. Some of the most common ones are

  • Sediments;
    soil, sand, and minerals washed from land into water, usually after rain
  • Nutrients;
    nitrogen and phosphorous
  • Pathogens;
    disease causing micro-organisms
  • Mercury; and
    a neurotoxin that affects the immune system, alters genetic and enzyme systems, and damages the nervous system
  • Endocrine disruptors.
    mostly synthetic chemicals such as pesticides that disrupt hormonal activities in humans and may cause cancer

Contaminant sources

The top sources of contaminants in U.S. waters include

  • Agricultural production;
  • Urban stormwater runoff;
  • Industrial discharge;
  • Sewer discharge;
  • Underground fuel storage tanks; and
  • Landfills.

Water quality FYI

  • Overall, the number of impaired areas of rivers, streams, lakes, and estuaries has increased during the past decade.
  • In 2006, 19 percent of Virginia's rivers and streams mileage, 94 percent of the lake mileage, and 98 percent of the estuary areas were reported as impaired.
  • A long-term analysis of Virginia's surface waters showed improved levels of certain contaminants such as bacteria, nitrogen, phosphorus, and suspended solids.
  • Virginia's groundwater is generally of good quality, but there are variations in quantity, and quality across the state.

Source: Virginia Department of Environmental Quality

Pilot study benefits

The optimization tool will be pilot-tested on the town of Blacksburg's stormwater system and the local Stroubles Creek watershed.

Multiple computer software platforms are currently used to simulate how effective the selected practices are at removing the pollutants.

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