Landscape Architect Articles

A Walk through the Woods on Porous Pavement12-06-16 | News

A Walk through the Woods on Porous Pavement

The new half-mile trail of porous pavement (20,000 sq. ft. of 'Porous Pave XL' poured in place) is adjacent to the Charles River in Wellesley, Mass. The path was constructed with the financial support of the John Hancock Real Estate Finance Group on land owned by the Massachusetts Department of Conservation and Recreation.

Trevor Smith, lead designer for Land Escapes Design Studio in Belmont, Mass., the landscape company that installed the path, explains that 2 inches of porous pavement was poured on a base of six inches of 1/4-inch crushed gravel. The tested infiltration rate of the product has tested at between 5,800 and 6,300 gallons per hour per square foot, a rate that leaves no surface puddles even during heavy rains.

When a path was proposed along the Charles River in Wellesley, Mass. (pop. 27,982), a community just southwest of Boston, the local conservation commission had to approve plans for the path, explains Dan Driscoll, director of recreation facilities planning and design for the Massachusetts Department of Conservation and Recreation. The Wellesley Wetlands Protection Committee required a pervious material to allow rainwater to drain through the surface to minimize runoff into the nearby Charles River.

The winding path through the woodlands is a public trail, and frequently used by workers at the nearby Wellesley Office Park.

"The path is only 50-75 feet from the river, and sections are in a flood zone," explained Horace Aikman, senior associate with CRJA-IBI Group of Boston, the landscape architecture firm that designed the path. "In addition to permeability and walking surface comfort and safety, we needed a strong paving material that can hold up against periodic flooding."

The porous pavement is made from 50 percent recycled rubber chips and 50 percent chipped granite aggregate. Stormwater infiltration through Porous Pave has a tested rate of 5,800 - 6,300 gallons per hour per square foot, leaving no puddles on the surface even during heavy rains. With the recycled rubber content, the material is freeze and frost-heave resistant for durability and provides significant traction. It is tough enough to be shoveled or plowed in winter. After snow removal, residual melted water permeates down into the material rather than freezing and forming ice on top.

The pervious pavement for the path is a brown color to help blend in with the woodland landscape. While this path is fairly flat, porous paving can be installed on grades up to 30 degrees. The curing time is only 24 hours.