What is a rain garden? What does "bioretention" mean?
Rain gardens are shallow depressions designed to capture, treat, and infiltrate stormwater. The philosophy with rain gardens is that even a small rain garden can enhance a residential landscape and also make a difference in reducing the impacts of runoff on creeks and adjacent and downstream properties, especially when many property owners install them. The terms bioretention and rain garden are essentially synonymous, with bioretention more typically referring to a larger practice, often designed by a Professional Engineer or Landscape Architect and regulated through a land use permit. Rain garden is a more informal, user-friendly, and illustrative term. "Bio" refers to the fact, that unlike "retention only" practices designed to store water, "bioretention" practices also include plantings and a media that is conducive to infiltration and biologically mediated processes that filter and treat runoff to improve the quality of water. The associated infiltration and evapotranspiration means less water runs off.
What is involved in planning for and designing a rain garden? Where can design assistance be obtained?
The first design step is siting a rain garden so it is properly placed and sized and is able to handle flow into and overflow out of the finished garden. Rain gardens can use native soil, but often require amendments to the soil to improve infiltration. If the native soils are heavier, an underdrain may be needed or a backyard wetland may be a better choice than a rain garden. The most appropriate rain garden plants are native to the region and do well in both wet and dry conditions. The links and resources on this page are intended to help with planning and design. The contractor's directory lists professionals working in Carrboro. A new residential assistance program may be available later in 2024 to offer design and cost sharing assistance.
What is involved in building a rain garden? Where can installation assistance be obtained?
Small rain gardens may be able to be built by hand, but typically, grading equipment is used to dig a depression and a berm that defines the rain garden. A soil media capable of infiltrating runoff may be added along with appropriate plants. Erosion control measures may need to be taken during construction. The contractor's directory lists professionals working in Carrboro. A new residential assistance program may be available later in 2024 to offer installation assistance.
Where can I learn more?
More information is available from the below links and the "Rain Garden Resource" documents --->
