Stormwater Concerns Generate Permeable Asphalt Technology

News National Oceanic & Atmospheric Administration (NOAA) December 01, 2004
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One of the greatest threats to water quality nationwide begins with a storm. Rain washes over agriculture fields and suburban backyards, picking up pesticides, fertilizer and sediment. It streams across urban parking lots and roads spattered with oil and crusted with the residue of salt and heavy metals. Along the way it collects carelessly disposed of trash, toxic chemicals, pathogenic microbes from farm animal and pet waste, and malfunctioning sewer and septic systems.

Eventually, the rain carries this blend of pollutants — known as nonpoint source pollution — into streams, creeks, estuaries and coastal harbors where it degrades water quality and threatens aquatic habitats. So pervasive is the problem that Phase Two of the Clean Water Act mandates stormwater managers to tackle this challenge head-on, yet often they lack the information they need to make decisions about stormwater treatment systems.

A groundbreaking research and development center is addressing this critical need with funding and support from a unique NOAA/University of New Hampshire partnership — the Cooperative Institute for Coastal and Estuarine Environmental Technology. The Center for Stormwater Technology Evaluation and Verification provides rigorous scientific field testing and demonstration of stormwater treatment technologies.

Into the Future

Alongside a scrutiny of the effects of traditional stormwater treatments on water quality, CSTEV’s research also focuses on alternative technologies for the future. In an effort to treat and minimize stormwater at the source, one such project places a new twist on an old technology — a porous parking lot. Roads, parking lots, buildings and other impervious surfaces generate significantly more runoff than permeable soil, making stormwater management in highly developed areas particularly challenging.

The experimental asphalt used to create the parking lot used in this study looks like normal pavement. On closer inspection, however, tiny holes become apparent. The tiny holes allow rainwater to flow through to the soil below, where it can be filtered naturally and eventually replenish groundwater. This winter, CSTEV will monitor the test lot to see how well it reduces runoff compared to other technologies and how it holds up to the freezing and thawing of New Hampshire’s frigid winters.

“People think of stormwater as waste rather than a resource — it has become convenient to just let it go, channel it out,” says Roseen, “but water that is drinkable, swimable and fishable is at premium everywhere. CSTEV and its partners have to start engineering ways to rehabilitate stormwater so that it can replenish our aquifers, springs and streams.”

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