Although concrete lasts a long time whenever the ground is covered with it, rain doesn’t seep into the soil. As the rain accumulates and water starts flowing off the concrete, it can create problems. But porous pavement materials are now available to provide a solid base and still allow water to seep through. Alternative materials which include pervious asphalt, pervious concrete, interlocking pavers, and plastic grid pavers, allow rain and snowmelt to seep through the surface down to underlying layers of soil and gravel. In addition to reducing the runoff from the rain that falls on them, permeable pavements can help filter out pollutants that contribute to water pollution. Permeable pavements can also reduce the need for road salt and reduce construction costs for residential and commercial development by reducing the need for some conventional drainage features.
What Are Your Options?
For patios or walkways, consider installing permeable concrete pavers. The pavers are solid, but if they’re spaced correctly, water drains between them. Pavers are placed over a bed of sand or gravel, which filters water before it percolates into the soil. Permeable pavers are made from concrete or cut stone and are available in several styles.
When replacing or creating a driveway or parking area, consider either permeable pavers or open-cell concrete blocks. These blocks are designed to support vehicles, but are sufficiently open to allow water to drain through them. The spaces are filled with gravel or sand. Grass or low ground cover can grow in the open spaces, which helps reduce heat buildup.
Another product that can be used for driveways is pervious concrete, aka porous pavement. As its name implies, this is a highly porous form of concrete. It’s made from aggregate (small stones) and cement, which binds the aggregate together. However, unlike conventional concrete, pervious concrete contains little, if any, sand. This results in a substantial number of open spaces in the concrete, basically a lot of holes through which water can flow into the ground.
1. Use of pervious concrete eliminates over $260,000 in construction costs in Sultan, Washingon. Read more >>
2. A Minnesota city eschews storm drains for pervious streets. Read more >>
3. To learn more and find sources of materials, visit perviouspavement.org and paversearch.com.
Sources: EPA, Mother Earth News