In other words, choosing permeable paving (that is, paving that allows water to flow through it rather than race toward the nearest sewer) can be a sound environmental move. And when you can be both environmentally responsible and save some money in the process, what’s not to love? Saving the world one driveway at a time may not seem like much, but with some areas building new roads, sidewalks, and parking lots with permeable paving materials, the larger benefits start becoming apparent. There are many products that can be considered permeable, some rather high tech and others decidedly low-tech.
Grass Driveways
Most driveways begin as grass driveways, intentional or not. If nothing else replaces the grass, it will wear away over time. However, where the weather is fairly dry and mild, a grass driveway may work perfectly well. A better long-term solution to using grass on a driveway is to just add two thin paving strips to provide a path for car tires. You could use a permeable material such as gravel or impermeable concrete for the strips. If you choose the latter, you will still substantially reduce runoff from your property. Two 18-in. wide paving strips produce much less runoff than a single 12-ft. wide concrete slab. The bulk of the driveway will remain grass.
Loose Stones and Gravel
The most common types of permeable paving materials include loose stones and gravel, which have been supporting traffic of all kinds for centuries.
Plastic Grid Systems
Plastic grid systems typically are formed using recycled plastic grids or blocks that form a hard driving or walking surface that allows water to flow through freely. They are long-lasting, easy to install, and maintenance free. Grids can be filled with sand and soil or gravel.
Permeable Pavers
Permeable pavers can be little more than a concrete version of the plastic grid systems by replacing the plastic with open cell concrete blocks. Other, more traditional types are pavers in brick, solid concrete pavers, and cobblestones. The key to creating permeable driveways with these materials is to fill the gaps between pavers with sand.
Permeable Concrete and Asphalt
Odd as it may sound, new types of concrete and asphalt actually allow water to soak through. Permeable concrete and permeable asphalt were developed to allow pavement-style parking and driving surfaces where environmental regulations might otherwise not permit them. Another approach to constructing permeable concrete surfaces is with open cell concrete blocks. Functioning much like the plastic grid systems, open cell concrete blocks let water through yet still handle heavy loads with ease. Fill the open cells with some topsoil and grass and the blocks themselves can become hard to distinguish.
Paving Strips
Paving strips are another old-time approach that seems to be gaining new appreciation in our more environmentally sensitive times. In the early days of automobile-inspired driveways, it was common to run thin paving strips just wide enough to handle a car’s tires. The rest of the driveway remained grass covered. Somewhere along the line, folks began upgrading to solid concrete or asphalt driveways. These had their advantages, but they used much more material, cost more to install, and added significantly to rainwater runoff problems. Paving strips are back in vogue and are showing up in a lot of new, energy efficient homes. They are particularly useful in milder climates where snow removal is of little concern. As long as the lawn around the strips is kept trimmed and well cared for, a driveway composed of paving strips can complement any type of house.
