Parking islands, if properly designed, serve a number of purposes beyond controlling traffic circulation within a parking lot. Parking lots are, more times than not, constructed with impermeable surfaces. Stormwater runoff rate and quantity increase due to impermeable surfaces resulting in channel flow and erosion. Pollutants emitted from vehicles are also carried away in runoff, damaging adjacent watersheds and aquatic habitats. This section explores sustainable strategies that may be implemented to improve the functionality of a parking island.

Sustainable strategies such as rain gardens, tree wells and dry wells are effective methods to reduce stormwater runoff and pollutants through evapo-transpiration and/or infiltration. These methods may be implemented into a wide variety of applications including existing parking islands. Slope and grade of parking lots should be designed to direct water to the rain garden, tree well, etc. Curb surrounding a parking island may also be partially or fully removed. Ensure parking island vegetation does not cause a safety hazard by obstructing drivers’ views of other cars or signage. See the rain garden and tree well pages for more information regarding these sustainable strategies.

Figure 1. Parking lot improvement design at Ramstein AB

Parking island improvement expenses may be offset by the reduced need for conventional stormwater systems such as drain inlets and culverts. Expenses to remediate pollutants and erosion may also be avoided.

Figure 2. Well designed parking improvements at Ramstein AB

Improving the function of parking islands is a potential strategy to achieve the intent of LEED SS Credit 6.1 and SS Credit 6.2. Refer to the LEED Guidance section for specific requirements.