Permeable Pavers Transform Walkways and Parking Lots: Design, Function and Sustainability

By Monica Helms, consultant to Pavestone Company

Surrounded by 20 acres of beautiful trees and hills is the Ignatius House, a nonprofit, non-denominational retreat center geared toward helping people maintain their sense of spiritual well-being. Located on a tributary which flows into the Chattahoochee River, the lush, green acreage helps promote the sense of peace and serenity its participants gain while on religious retreats. The owners of Ignatius House have a vested interest in maintaining that sense of calm; not just for the people who participate in those retreats, but for the environment, as well.

The Ignatius House is a non-denominational religious retreat center in Sandy Springs, GA. Shown above, 4300 square feet of Eco-Venetian™ by Pavestone permeable pavers and about 3200 square feet of Villa Stone™ pavers were used in renovations to the buildings, walkways and main driveways.

So when the time came for Ignatius House to undergo renovations to the buildings, walkways and main driveway, it was decided that 4300 square feet of Eco-Venetian™ by Pavestone permeable pavers and about 3200 feet of Villa Stone™ pavers would be used. Permeable pavers were chosen due to their porous nature and ability to allow rainwater to filter through them. Without explanation, this may at first sound unimpressive; however, when compared to the potential environmental impact of pouring new concrete, the lightly colored permeable pavers were not only a more aesthetically pleasing choice, but a more practical one as well.

Through the design of drains underneath the system, water is absorbed through expanded joints in the pavers. As the water is collected, it goes down into a storage area and is then drained into the area west of the chapel, where a bioswale was built to collect and filter the water before it drains back into the river.

Storm water runoff occurs when rainwater washes over a surface, rather than becomes absorbed into it. It can wash hydrocarbons and debris over concrete and any other nonporous surface, washing whatever it takes with it into nearby rivers and streams. Not only does this create pollution via the debris that sometimes winds up in that runoff, but the hydrocarbons and other chemical pollutants will go with it. The sediment can affect the growth of aquatic plants, and the pollution can sometimes kill fish, as well as contaminate drinking water for land animals and even the people nearby.

With the aid of the permeable pavers’ filtration abilities, the Ignatius House parking lot and walkways will effectively eliminate the impact of rainwater run-off and pollution of the nearby tributaries which lead to the Chattahoochee River.

Another reason why the permeable pavers were a more practical choice for Ignatius House was because of their solar reflectance index (SRI). Like many Southern cities, Sandy Springs experienced a fierce summer this year. Unlike dark-colored asphalt or concrete, the light-colored permeable pavers reflect heat rather than absorb it, reducing what’s known as heat island effect. When covering large enough areas, this heat island effect can produce secondary meteorological effects, such as changes to local wind patterns, clouds, fog, humidity and rates of precipitation. This reflection from the parking lot will play a role in reducing discomfort for those walking across it in coming summers, as well as help reduce future energy costs for the structures that make up the Ignatius House campus.

Dan Kalar, who worked with Benning Construction and GT Hardscapes to design and build the new parking lots, noted that the owners of Ignatius House were worried about the repercussions associated with pouring new, nonporous concrete. They also knew that this would create an ideal surface for pollutants to wash into the Chattahoochee River as undesirable run-off when it rains. Bearing this in mind, Kalar worked in conjunction with both Benning and the owners of Ignatius House to design and build a method for directing water to the west side of the Ignatius Chapel. This was accomplished through the design of drains underneath the system, where water is absorbed through expanded joints in the pavers. As the water is collected, it goes down into a storage area and is then drained into the area west of the chapel, where a bioswale was built to collect and filter the water before it drains back into the river.

Keeping sustainability in mind, the permeable pavers were selected for their ability to reduce rainwater run-off and reduce heat island effect that would normally accompany a nonporous, dark-colored asphalt surface.

This system of water filtration not only limits the collection of water in the courtyard on rainy days, it also filters and removes any other miscellaneous pollutants which may have been present. Basically, said Kalar, the water is being funneled into the river even cleaner than when it was found. The end result is an eco-friendly parking lot and courtyard, thus beautifying the Ignatius House campus with the pavers while simultaneously helping to maintain the vibrant greenery and vegetation around it. The resulting view of the aesthetically pleasing appearance of the pavers doesn’t hurt, either. With the combination of practicality, aesthetics and sustainability for the surrounding environment, these permeable pavers will provide Saint Ignatius with years of use.