Kris Bachtell, the vice president of collections and facilities at the Morton, said the parking lot and lake projects are indicative of the Morton’s commitment to sustainable design and construction.

The arboretum's main parking lot project employs best management practices for dealing with storm water runoff and contaminants. The surface is permeable, interlocking concrete pavers atop four feet of gravel that filters storm water and slows its progress through the groundwater system. Water also temporarily collects in bioswales along the parking lot aisles, which help filter contaminants in the water.

Rain falling on the parking lot and into the bioswales enters nearby Meadow Lake and eventually the DuPage River. The Morton Arboretum restored Meadow Lake by draining and reshaping the lake, installing a wall and several devices to stabilize the lake's water level, regrading the shoreline, amending the soil and planting 68,000 native plants.

The Morton Arboretum www.mortonarb.org is a leader in tree science and education. The 1,700-acre outdoor museum features 4,117 kinds of trees, shrubs and other plants from around the world.

The U.S. Green Building Council, a stakeholder in SITES, anticipates incorporating the guidelines and performance benchmarks into future iterations of its LEED Green Building Rating System.