The Morton Arboretum recently tested a unique, new porous pavement made of crushed, recycled beer bottles, other glass, and granite fragments. The test is consistent with a decades-long commitment to protecting trees and the environment.

"We are constantly looking for more sustainable techniques, systems, and products. This porous pavement may be the way of the future," says Kris Bachtell, Arboretum Director of Collections and Facilities.

Only a handful of Chicago-area locations have installed the material, and the Arboretum is on the leading edge of efforts to test it, Bachtell says. The glass has been specially processed to round its edges and is "structurally sound and as safe as any traditional surface," according to manufacturer Presto Geosystems, of Appleton, Wis.

Porous materials, such as pavement or certain bricks, help the environment by trapping dirt and other pollutants, thereby keeping them out of the groundwater. On a traditional surface such as asphalt, these pollutants are usually swept away by fast-moving rainwater, and deposited into storm drains, detention areas, and streams.

Additionally, porous pavement can actually reduce the "heat island" effect by trapping and mitigating heat, rather than reflecting it, as a blacktop surface does. Such reduced heat in the pavement and surrounding soil is beneficial to tree roots.