USATODAY.com - Rain, runoff, subject of UNH research center

DURHAM, N.H. — Who ever thought a rain-soaked parking lot could provide so much information? In this season of stormy weather and floods, the University of New Hampshire has been studying the runoff that flows off parking lots, roads and lawns — the chief source of water pollution in the country.

Until now, there's been little scientific data to compare how various treatment techniques work when conditions are controlled so they're the same from one to the next. The UNH Stormwater Center is unique in doing this research.

Retention ponds and gullies lined with gravel are the most common approaches to treating stormwater runoff. But as co-director Robert Roseen and other researchers found, they're among the least effective at preventing pollution.

The Stormwater Center was set up with help from the Cooperative Institute for Coastal and Estuarine Environmental Technology and the National Oceanic and Atmospheric Administration and funded with federal grants secured by Sen. Judd Gregg.

"The water from storms and flooding like New Hampshire experienced has the potential to be contaminated with pollutants from a variety of unknown sources," Gregg said as he prepared to celebrate the center's one-year anniversary Thursday. "This Stormwater Center is working to solve that precise problem."

The Stormwater Center uses a 9-acre watershed next to a university parking lot to test various stormwater treatment systems.

Each system is guaranteed an equal share of the runoff from the parking lot and pipes underground collect the water to see how quickly and how successfully each system treats the water.

The testing area is set up with a self-guided tour so each system can be viewed from above, with a panel illustrating how it functions.

One recessed area contains two feet of coarse sand acting as a water filter. Another has a combination of sand, soil, wood chips and compost planted with native wetlands plants. Yet another tests a selection of manhole covers equipped with devices designed to separate out sediment and oil.

Among the discoveries has been that layering soils and plants to mimic a natural wetland is highly successful at containing sediment, absorbing excess nutrients and breaking down petroleum products so they don't pollute nearby waterways or groundwater.

When the Stormwater Center started, communities in the Chesapeake Bay had used this approach successfully but no one knew if it would work in New England where the ground freezes for part of the years.

Not only did the wetland not freeze over (Roseen theorizes the compost in the soil generates enough heat to prevent this), it continued to clean out a wide array of pollutants throughout the year.

This fall the center celebrates it's first anniversary, having amassed a year's worth of data on how various approaches work.

Roseen said it's the lack of information that made it difficult for states, municipalities and businesses to evaluate options for treating runoff.

The combination of comparative data and opportunities for engineers, planners and others to see the systems in action means communities stand a better chance of picking a system that works for their needs.

Some systems can be set up under a parking lot, others work alongside roads or on urban sidewalks. Some handle larger volumes of water better than others; some can be arranged to take out specific pollutants.

"It's not enough to say one system is better than another," Roseen said. The center is not in the business of promoting any particular system, he said, and does not accept money from manufacturers.

Among the creative ideas the center is testing is porous asphalt. The asphalt, which was applied in another parking area on campus, contains tar and gravel but not sand.

Without the sand, the surface looks rougher, but it has tiny holes that allow water to filter through. The surface doesn't crack in winter, and if filter material is layered underneath, it can treat runoff as it comes through the pavement.

Looking to the years ahead, the Stormwater Center will begin to analyze the longevity and maintenance costs of these systems. This stands to be particularly helpful to smaller communities facing new requirements under the Clean Water Act without engineers on staff to help them evaluate treatment options.