Until the 1990s, the parking lot of the Morton Arboretum in Lisle, Illinois, was five acres of impervious asphalt at the entrance of the 1,700-acre outdoor museum. Because the parking lot borders Meadow Lake, improperly managed stormwater flowed freely into the East branch of the nearby DuPage River, degrading water quality and creating high land-maintenance costs for the Arboretum.
In the 1990s, the parking lot was reconstructed to reduce stormwater runoff and improve downstream water quality. The cooperative design project enlisted the Arboretum staff, engineers from Christopher B. Burke Engineering, Ltd, landscape architects, regulators, and contractors to reconstruct the parking lot so it retains virtually 100 percent of stormwater through five features:
Permeable pavers – Interlocking concrete pavers are durable and high strength, able to withstand the traffic the Arboretum serves. The pavers are set in stones that allow stormwater to infiltrate into the ground.
Bioswale Medians – Medians planted in between parking bays absorb and filter stormwater as it is absorbed into the ground.
Perforated storm sewers – A perforated sewer system allows stormwater runoff to irrigate and infiltrate into the ground. The sewers in the Morton Arboretum lot are able to withstand a 10-year storm.
Level spreaders – This erosion control tool works to reduce runoff and increase the water absorbed into the ground by mitigating and reducing the speed of flow of stormwater surface runoff. When strategically located upstream from soil, level spreaders can generate native plant growth.
Created wetlands – Wetlands create a final polishing pool for water treatment, work as a sediment trap, and serve as a level spreader to help mitigate stormwater erosion.
The reconstructed parking lot saves the Arboretum substantial costs on infrastructure maintenance, and reduces the cost and time spent maintaining Meadow Lake. Interpretive signage at different features in the parking lot teach visitors the benefits of green stormwater infrastructure design, and community engagement events like lake runs, history walks, and family camps work to inform the community about the benefits of reconstruction.
The data collected by the Landscape Performance Series were first measured in 2004, providing details about the environmental, economic, and social benefits of the parking lot design. Ongoing monitoring and pest management not only prevent the establishment of invasive species, but also show the Morton Arboretum’s commitment to sustainable green design. A member of the Green Power Partnership and certified by the Sustainable Sites Initiative in 2012, Morton Arboretum regularly pilot-tests new products and designs that protect trees and the environment.
For more information about the Morton Arboretum parking lot and other sustainable design initiatives, visit these links:
The Morton Arboretum’s “Green” Parking Lot (paper)
Sustainability at the Arboretum
Landscape Performance Series: The Morton Arboretum Meadow Lake & Permeable Parking Lot – Methodology for Landscape Performance
Taylor Griggs is an undergraduate student at DePaul University, completing a degree in Urban Sociology & Geography.