“Sustainable [landscape] design is thinking of rainwater as a resource,” says Scott Johnston, principal of Johnston Design Group in Greenville, South Carolina. “When you start thinking that way, it affects the selection of a lot of things but particularly paving products.”
Johnston says using a well-designed permeable pavement system allows sufficient surface water infiltration and water storage. Permeable pavers allow surface water to drain into their sub-base through gaps or joints within and between each paver. Underneath the pavers, instead of a conventional installation, a series of “open graded” aggregates – gravel without fine particles – is used as a base.
Large stones are placed on the ground, with layers of progressively smaller stones placed on top of them. The pavers are carefully positioned, and the smallest stones are swept into the joints between the pavers. Rainwater flows through to the virgin soil, cleaner and able to recharge the natural water table. The aggregates in the base and sub-base collect the sediment, allowing the natural bacteria to settle in the void storage. The angular shape of the aggregates in this collection process reduces elements and impurities such as nitrogen, bacteria and phosphorus.
By using permeable pavers, landscape professionals can eliminate the need for onsite retention basins. Other construction such as swales or perforated drainage pipes can be added to divert flow or contain it under the pavement, similar to a retention pond. In this way, permeable pavers work with the surrounding environment to promote natural growth and healthy outdoor spaces.
Permeable pavers should last upward of two to three decades. They show a life cycle cost that pays for itself within eight years, whereas asphalt can cost 10 times this much over a 50-year life cycle, according to Belgard Hardscapes. Freeze and thaw cycles have no effect on the system due to the product’s flexibility.
By using environmentally responsible products such as permeable pavers, landscapers can turn any outdoor environment into a green space that is both nurturing and beautiful.
Information compiled from Belgard Hardscapes and Pine Hall Brick.
