Stormwater Straight Talk: Rain gardens, low impact development

  • Published
  • 78th Civil Engineer Group

Stormwater runoff is a major cause of water pollution. During a rain event, stormwater flows out of downspouts, runs across lawns and streets, through storm drains, and, ultimately, into lakes, rivers, wetlands and streams. Along the way, stormwater may collect pollutants such as pesticides, fertilizers and vehicle oils before reaching one of these receiving waters.

To help improve the quality of receiving waters, there has been an increased focus on Green Infrastructure and Low Impact Development Best Management Practices. The goal of GI/LID BMPs is to use the natural landscape to control stormwater flow quality and quantity with permeable soils and vegetation. A rain garden is an example of an LID approach to storm water management because it retains and infiltrates rainfall onsite.

Rain gardens are versatile features that can be installed in almost any unpaved space, and they can aid in the reduction of stormwater pollution. Rain gardens are shallow, vegetated basins that capture roof, lawn and driveway runoff. They look like typical gardens, but their porous soil acts as a filter and allows the stormwater to soak slowly into the ground. Vegetation, such as grasses and flowing perennials, can aid in the reduction of pollutants as the plants can use some of the nutrients found in the stormwater runoff.

A rain garden is typically constructed with three zones. At the center of the garden is zone 1, which contains plants that like standing water for long periods of time. Zone 2 surrounds zone 1, and it contains plants that can tolerate occasional standing water. Zone 3 is located along the outer portion of the garden, and zone 3 should be planted with species that prefer drier soil since this zone is usually dry.

Considerations for constructing a rain garden:

- Make sure that the rain garden is located at least 10 feet from houses or other buildings to protect the foundation and at least 50 feet from a septic system.

- Avoid areas with trees to avoid damage to tree roots.

- Place your rain garden in a flat portion of the yard to reduce erosion and allow water enough time to soak into the ground.

- Follow proper procedures, such as calling 811, to locate underground utilities prior to digging.

Rain gardens generally have the same amount of maintenance as other types of gardens, but they can be a beautiful way to reduce stormwater runoff and help filter pollutants from run-off.

For more information, call 478-222-2526.


Editor’s Note: Stormwater Straight Talk is a quarterly column intended to educate and inform base personnel and families about stormwater management.