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Student research at forefront of stormwater treatment


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When rain washes over roads and parking lots, it sends oil, grease and metal particles into the storm drains – and those pollutants end up in rivers and streams. A team of Sacramento State graduate students has embarked on a research project to improve the way that stormwater runoff is treated.

“The primary objective of this research is to develop solutions to overcome nutrient-leaching from bioretention systems,” says Dipen Patel, research engineer with Sacramento State’s Office of Water Programs (OWP) and the project’s principal investigator.

The students are constructing experimental bioretention filters, layering different compost-sand mixtures and pea gravel in varying depths into 28 large, food-grade plastic cylinders – and topping each cylinder with a planting of wild weeping ryegrass.  The experiments will help them determine the optimum mix for filtering pollutants and allowing biological organisms to successfully attack pollutants.

Their laboratory is at the University’s Sustainable Technology Outdoor Research Center (STORC), alongside the American River levee and near the campus’ stormwater pumps. Students use actual campus stormwater in their experiments.

“Nutrients and metals in urban stormwater are potential problems in many parts of the state,” says John Johnston, professor of civil engineering and OWP’s technical advisor. “With this project, we’re trying to improve the efficiency of relatively low-cost treatment devices.”

The bioretention project is funded by a grant from the California Water Resources Control Board.

For media assistance, contact Sacramento State’s Office of Public Affairs at (916) 278-6156. – Dixie Reid