Award of Merit - Environmental

Interstate 684-Route 22 Interchange

It's not often that you see a highway construction project lauded for its environmental sensitivity. But the awards jury found plenty to praise about the project at Exit 3 on Interstate 684, with one member calling it "a great case of the environmental interacting with the engineering."

The recently reopened interchange in North Castle, N.Y., has what some in the industry consider the best new methods to control stormwater runoff, including infiltration swales and an infiltration basin. Both hold on to some of the stormwater running off the highway, allowing the soil to absorb dirty water and keep it from a nearby reservoir. Contractors also built a biorentention basin, which temporarily stores dirty water and directs it through a filter bed, which cleanses it.

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The overall commitment to protecting water quality stood out as a remarkable feature of the project to refurbish the exit, which serves as the interchange between Route 22 and I-684 in northern Westchester County. New York's Tectonic Engineering & Surveying Consultants and the rest of the project team working for the New York State Department of Transportation turned the job into a case study for preventing environmental damage through their extensive efforts to mitigate stormwater runoff.

The department had initially embarked on the $7.5 million project to improve features of the interchange between the two highways. It was one facet of a larger project that brought improvements to a longer stretch of Route 22. The Exit 3 location, though, added a significant twist.

The interchange is in the watershed of the Kensico Reservoir, a man-made lake on the Bronx River that is a vital part of New York City's water supply system. Erosion during construction could have damaged the quality of the reservoir's water, which supplies millions of New Yorkers. A worse ongoing problem was stormwater runoff carrying oil, chemicals, silt, and other roadway pollutants into the reservoir.

The designers adhered to strict stormwater management guidelines prescribed by the state Department of Environmental Conservation. Also vital was the full-time onsite presence of both an erosion control specialist and an erosion control inspector who were involved with the entire design and construction phases.

The project's other success was the wide cooperation between contractors, the state, environmental agencies, and advocacy groups. Along the way, the project team gained the faith of "green" watchdogs, showcasing how a big road project in an environmentally sensitive area can still meet stringent water-quality standards.