Cincinnati -- Researchers in the University of Cincinnati College of Engineering have shown that a modified filtration system along interstate highways can prevent heavy metals from polluting nearby water supplies.
The system, known as a partial exfiltration trench (PET), was designed and built by research assistant professor John Sansalone as part of his doctoral research in the department of civil and environmental engineering at UC. The PET replaces the normal sand used in highway storm drainage systems with an iron oxide coated sand. That makes the sand signficantly more effective at trapping heavy metals such as cadmium, copper, lead and zinc.
"Polluted water flows in, and clean water flows out," explained Steven Buchberger, associate professor of environmental engineering and Sansalone's thesis adviser.
Sansalone presented data from a year-long field test during the recent World Congress of the International Association for Hydraulic Research (IAHR) in San Francisco. A prototype PET system was installed along a stretch of Interstate 75 near downtown Cincinnati. It is the second busiest stretch of interstate highway in the state of Ohio.
The effectiveness of the PET system varied for each specific metal, but the overall trapping efficiencies ranged from 82 to 97 percent. The PET even holds up well during heavy rainstorms. The system can handle up to one inch of rain per hour. That's when Sansalone discovered a side benefit to his novel system.
"The PET not only works as a water quality device, but it can act like a water quantity control device to reduce surface flooding," said Sansalone. That discovery was completely unexpected in the Cincinnati area where clay soils are common.
Sansalone will continue his research by looking at ways to
make the system more economical and efficient. It took ten tons
of coated sand to treat 20 meters of highway during the field
test, so Sans
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Contact: Chris Curran
chris.curran@uc.edu
513-556-1806
University of Cincinnati
29-Sep-1997