What is a Rain Garden?

What's a "Rain Garden?"

Perhaps you heard of something called a Rain Garden, but weren’t sure what it is or what it does. Rain Gardens are simply small depressions in the landscape that have runoff from rainfall directed toward them, either through contouring the surrounding land where the water can flow overland to the garden, or by installing shallow pipes that convey the runoff directly to the garden. From there, the Rain Garden “scrubs” the stormwater of pollutants that may be carried by the rainfall.

Common pollutants are oils and other hydrocarbons that are dripped onto pavement from vehicles. Another type of pollutant is phosphorous that comes from the application of fertilizers onto the landscape areas. Both these and other pollutants can have a detrimental affect on nearby streams, wetlands and other water bodies.

Local regulations require development to take care of stormwater impacts to the environment, in terms of both preventing erosion downstream of the site, and removing pollutants from within the water itself, also known as stormwater treatment. The Rain Gardens primary feature for treating runoff is through specially prepared soils that are placed within the bottom of the cell, quite often up to two feet thick. A typical soil amendment contains a high level of composted material, sand and topsoil. The compost provides and environment for bacteria to thrive, which is the workforce behind the removal of the pollutants. The sand allows the water to quickly spread through the material for uniform saturation and maximum performance.

Another key feature of the Rain Garden that makes it very popular is aesthetic beauty. The Rain Garden can be sculpted into a shape that is pleasing to the eye, and can be landscaped with a variety of plants that tolerate periods of saturated soil conditions or flooding. In essence, a botanical garden is created whose hidden objective is playing a key role in site development—stormwater treatment.

For more information on Rain Gardens, please feel free to contact us by phone at 360-794-7811 or by email at harmsenllc.com.