Click on image to veiw larger size - A typical raingarden design.

Above is a typical design for a raingarden.

CEI's Low Impact Development (LID) Committee has designed and with financing from CEI created seven raingarden demonstration projects throughout New England.

For more information on these raingardens follow the links below.

What is LID/Raingardens

Raingardens, also called infiltration basins, and bio-retention basins, are utilized as a new and environmentally friendly way of managing storm water runoff, while at the same time beautifying the neighborhoods. Simply speaking, a raingarden is a landscape area, that is slightly sunken or depressed to help collect and soak up rainwater from impervious surfaces such as roofs, driveways, and parking lots rather than letting it run off into the street and drainage system and eventually into our lakes and streams.

Why do we need raingardens?

Rain is a natural occurrence in nature; stormwater is not. Government studies have shown that up to 70% of the pollution in our streams, rivers and lakes is carried there by stormwater. About half of the pollution that stormwater carries comes from things we do in our yards and gardens such as pesticides and fertilizers.

Once the gardens are planted and the plants begin to mature, the depressed area will literally be disguised by a nice aesthetic addition to our neighborhood landscaping. The plants, however, serve a more important function than just looking nice. They facilitate the infiltration of rainwater into the deeper soils and the recharge of our groundwater aquifers. They also continue to open up and aerate the soil to maintain the garden's infiltration characteristics, minimize yard waste and the use of fertilizers and pesticides.

Keeping rain where it falls, by putting it into a raingarden is a natural solution to preventing 1000 of gallons of stormwater that runs off roofs and driveways to the street and into the storm drain, carrying pollution with it.

The areas that are to become rain gardens will be over-excavated, in order to prepare them for planting, by placing a mixture of 50% native soil and 50% compost topped with shredded wood mulch. Peat and compost have been shown to provide considerable pollutant removal. Drainage piping may also be located in or near the gardens if necessary to provide an overflow outlet from the raingardens. Though the plants, which are utilized for the rain gardens, are capable of handling periods of wet conditions, the techniques used in the design of the garden help ensure that any water standing in the rain garden area is able to dissipate quickly.

Raingardens are intended to retain water only for a short period, eliminating the risk that the area will become a breeding ground for mosquitoes. A raingarden can actually reduce the number of mosquitoes by providing a habitat for species that prey on them.

Where should the raingarden be placed and how big will it be?

Rain gardens should be constructed at least 10 feet down slope of building foundations and septic system leaching fields.

Rain gardens should be sized based on the total impervious area draining into them. Typically, a rain garden for a single-family home can range from 12 ft. x 12 ft. to 20 ft. x 20 ft.

Gardens cannot be located over gas or water services. Always call dig safe before starting any digging project in your property. Gardens should be placed so as to not interfere with existing trees and shrubs.