One of the best ways to deal with rainwater on site is to let it infiltrate straight into the ground. Last week we talked about the design and benefits of rain gardens, but what about areas that need to be more durable, like driveways, sidewalks and patios? If you have a paving project on your summer to-do list, keep reading!Standard paving surfaces are impervious, meaning they don't allow water or air to circulate through. During a big rain, this can overwhelm the local stormwater system and can send harmful pollutants to local streams and rivers. Getting rid of excess paving is a good first step, but we still need safe and practical areas to park our cars and set our patio furniture. Fortunately, there are several products available that provide a durable, hard surface while also allowing water to find its way back into the earth. Here are a few worth mentioning:
Open Concrete Grids (photo above): In this system, the grid structure is placed over crushed rock and grass is planted within the voids. In addition to infiltrating water, the grid pattern can be incorporated as part of the landscape design.
Pervious Concrete: Similar to regular concrete, this mix includes larger pea gravel and fewer fine particles which means more nooks and crannies for water to travel through. This is a good solution for high traffic areas that need to accommodate heavy vehicles.
Pavers: Most of us are familiar with pavers and probably have a few around the yard. By providing a gap between pavers and installing over a bed of gravel, water is able to infiltrate slowly back into the ground. Similarly, you can also find interlocking pavers which are a good option for driveways and other areas that need more stability.
Plastic Lattices: Also known as "grasscrete", this plastic grid system is used with crushed stone or grass and provides a structure for rain to permeate without pooling or puddling. It can handle light vehicular traffic and could be a clever solution for residential driveways that don't want to scream "concrete!".
(Images: 1. Athens-Clarke County, 2. Pervious Concrete 3. Sutherland Landscape 4. Treehugger)