Porous pavement to help reduce runoff

The “porous alley” between West Canton Street and Holyoke Street in Boston’s South End helps absorb rainwater and filters it back into the ground.

By Nicole Dungca  http://ht.ly/GePIy

The average city street collects a lot of pollutants over time: Dog poop. Leaked oil. Leaves. When a storm hits, the microorganisms, phosphorus, and heavy metals from such debris make their way into the stormdrain system and often into the overflow that enters the Charles River.

City officials are hoping a solution to that problem lies in a small alleyway between West Canton and Holyoke streets in Boston’s South End. Mayor Martin J. Walsh on Friday afternoon announced the completion of a new “porous alley” that absorbs storm water and filters it into the ground, rather than allowing it to make its way into the sewer system. The 508-square-foot alley was completed in September, but officials held a ribbon-cutting ceremony on Friday.

During the ceremony, Walsh called Public Alley 543 a forward-looking way of tackling the problem. “This project’s important because it really is about the future of storm water and being able to capture storm water,” he said.

The innovative alley, developed with the Charles River Watershed Association and the Boston Groundwater Trust, is the city’s second “green alley.” The first was constructed in 2013 by the Boston Architectural College, in between the college’s buildings on Boylston and Newbury streets in Back Bay, in conjunction with the city.

Construction of the alleys marks another step in efforts to boost the quality of water in the rivers that flow into the harbor of Boston. In 2012, the Boston Water and Sewer Commission had to pay a fine for violating the Clean Water Act and take measures to minimize pollutants going into the waters.