Parking lots are a primary contributor to stormwater runoff in our cities due to their scale and impervious character. Parking lots, unless they are low-frequency use parking lots, must have a certain level of imperviousness to them for the functional aspect of vehicle movement.
A Parking Lot along Main Street in Pueblo, Colorado
However, there are tools that can be used to decrease the runoff and make use of the rainwater for these parking lots. Many have referred to this kit of parts as low-impact development (or LID). Tom Low’s book, Light Imprint, identifies a lot of the same tools as low-impact development, yet identifying options as they relate to the urban-to-rural transect.
The following image is a graphic I produced to illustrate some of the sustainable aspects of the parking lots in the Pueblo Municipal Complex. In the sketch, you will notice that the areas of the parking lot where vehicles are parked are semi-porous brick. The brick utilized for these areas is designed and constructed to maximize the size of openings at the surface to maximize infiltration. Another feature that you may see are the trees and tree grates within the parking lot. There are trees located in islands as there are in many parking lots, however additional trees are incorporated in tree grates, rotated 45 degrees. These trees are able to gather rainwater at the grates.
Porous paving, additional trees in grates and depressed landscape islands are all sustainable parking lot features in this image.
The parking lot’s islands are also designed in a manner to capture runoff. The are designed with curbs, curb openings and plants at the same or lower grade of the parking lot surface. All of these features utilize what is a precious resource-rainwater. Rainwater, unfortunately, is too often disregarded and redirected to storm sewers rather than being used as a resource. In addition, the addition of trees and brick pavers decrease the heat-island effect common with parking lots.
Update: We are working on utilizing similar features to these on our current projects at EV Studio Planning. Check us out at www.EVstudio.com for other updates.