December 2007, Vol. 19, No.12

Research Notes

Water Pollution May Be Reduced With Stormwater Analysis System

Streams, lakes, and bays soon may be cleaner, thanks to an innovative approach to managing stormwater runoff being developed at Virginia Polytechnic Institute and State University (Virginia Tech; Blacksburg, Va.) and funded by the U.S. Environmental Protection Agency (EPA).

A new software application will help engineers and planners select the most efficient and site-specific methods, or best management practices (BMPs), of controlling the amount of pollutants that enter receiving waters through stormwater runoff, according to a Virginia Tech news release.

The U.S. Congressional Research Service reported earlier this year that as much as 50% of water pollution problems in the United States are attributed to stormwater runoff, the news release notes.

The application is the product of collaboration between faculty and researchers from Virginia Tech’s Virginia Water Resources Research Center, the Center for Geospatial Information Technology (CGIT) in the College of Natural Resources, and the Via Department of Civil and Environmental Engineering in the College of Engineering at Virginia Tech.

The new BMPs selection approach, called the Analytical Hierarchy Process (AHP), will factor in dozens of site-specific criteria, such as soil types, land slopes, or maintenance accessibility, before choosing the optimal BMPs for a particular location.

“This technique is expected to drastically reduce the BMP selection time and will also eliminate the human error from such a complex process,” said project coordinator Tamim Younos, water center associate director and research professor of water resources in the Department of Geography in the College of Natural Resources. Other project leaders include Randy Dymond, CGIT co-director, and David Kibler, professor of civil and environmental engineering.

Traditionally, the selection of BMPs has been made 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,” explained Kevin Young, research associate at CGIT.

Young adds that personal bias all too often has led to “cookie-cutter” solutions to complex stormwater management needs, resulting in poor control of the pollutants.

A widely used, conventional BMP 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,” Younos said. “Pond overflow that still may contain dissolved pollutants reaches streams, rivers, and lakes and possibly groundwater.”

Other types of BMPs are trenches and porous pavement that enable the stormwater to infiltrate the ground, vegetated wetlands, and sand filters that help sift the pollutants, or proprietary stormwater technologies, such as hydrodynamic separators.

The new tool will be pilot-tested on Blacksburg’s stormwater system and the local Stroubles Creek watershed. The AHP software will be used by the research team to select BMPs within the watershed contributing runoff to Stroubles Creek, the town's main receiving waterbody. Two existing computer models then will be used to simulate how efficient the selected BMPs are at removing the stormwater runoff pollutants.

“The best part about conducting a pilot test on Blacksburg is that the town will be able to implement our recommendations,” Younos said. “We are very pleased by the town's enthusiasm and support for this project.” Other stakeholders include the New River Planning District Commission, Virginia Department of Environmental Quality, and Virginia Department of Conservation and Recreation.

The software, expected to be available next year, will be free for use by all interested engineers and planners, localities, and BMP review authorities, and will be applicable in other states with geographic and climatic environments similar to Virginia.

Contact Younos at tyounos@vt.edu.
 

WERF Begins Study To Optimize Utility Operations, Reduce Costs

As operational costs at wastewater facilities have been escalating during the past decade, wastewater utilities are seeking cost-effective solutions to optimize and sustain wastewater and solids treatment operations, according to the Water Environment Research Foundation (WERF; Alexandria, Va.). In addition, solids treatment operations, such as thickening and dewatering and solids handling, transport, and disposal, account for a significant portion of these energy costs.

According to WERF, energy use accounts for about 35% of wastewater treatment facilities’ total cost to provide wastewater services, second only to labor costs, with municipal water and wastewater utilities among the most energy-intensive entities owned and operated by local governments. Disposal of biosolids offsite requires transportation and land availability. There is increasing recognition by the wastewater industry that biosolids are resources to be utilized for energy or other (for example, phosphorus) types of recovery in addition to beneficial use as a soil supplement, WERF states.

To address the issue of energy for wastewater utilities, WERF is starting a 5-year research challenge for the Optimization of Wastewater and Solids Operations (OWSO). WERF subscribers were involved in identifying and prioritizing research challenges through direct input at meetings, surveys, committees, and other forms of outreach. Three original challenges and goals as identified by WERF subscribers pertain to optimization and sustainability of wastewater facilities:
 

  • Solids volume reduction. Develop cost-effective methods to minimize the volume and quantity of wastewater treatment solids generated without sacrificing product value and quality.
  • Resource recovery. Identify new resource recovery opportunities for wastewater solids, including biogas production, cogeneration of heat and energy, and extraction and reuse of constituents.
  • Energy management. Develop strategies, methods, processes, and tools for cost-effective management of energy use in wastewater operations, with due recognition given their impact on carbon footprint and reduction on greenhouse gas emissions.

The foundation decided it was logical to integrate these challenges into OWSO to build a comprehensive, long-term program with a goal to develop and demonstrate cost-effective and environmentally responsible processes that improve wastewater treatment and solids management operations efficiency and reduce costs by at least 20%.

To date, the WERF board of directors has approved a total of $870,000 in research funds for the OWSO challenge, and several projects are under way. The projects include Cost-effective Energy Recovery From Anaerobic Digested Wastewater Solids; Evaluation of Processes To Reduce Activated Sludge Solids Generation and Disposal; and Evaluation of the Co-Digestion of Organic Waste Products With Wastewater Solids To Maximize Anaerobic Digester Performance.

To follow the progress of the research under the OWSO challenge, see www.werf.org, or contact Lauren Fillmore, program director, at lfillmore@werf.org.