Comprehensive Environmental Inc (CEI) - LID Committee - Merrimack, NH Raingarden Demonstration Project

For more information on these raingardens follow the links below.

This photo was taken on May 25, 2005.

Comprehensive Environmental Inc (CEI) provided funds for this Low Impact Design (LID) raingarden Project located in the Merrimack River watershed, in the Town of Merrimack, New Hampshire. CEI's LID Committee personnel served as the technical consultants for this project to identify a location for the project, design the raingarden, as well as providing the labor for the actual construction.

The project location had to fit several criteria:

an area that could capture and infiltrate stormwater runoff discharging to nearby stormdrains and eventually to the Merrimack River watershed.
an area that would provide an educational benefit

The area at the end of the driveway and also an area below a stormdrain near the house were chosen for raingardens.

Construction of Rain Garden

On May 24, 2005 the garden areas were excavated, and on May 25, 2005 the gardens were landscaped. The gardens were completed on May 25, 2005.

In the area at the end of the driveway a hole was excavated in the center of the garden. The raingardens are dug so that they are tied into soils that lie below the normal frostline. Stone or slotted PVC tubing is then used to promote drainage in the bottom of the raingarden. This keeps the drainage working during winter months, preventing total freezing. The area under the stormdrain was prepared to allow stormwater to drain directly to the raingarden.

A 4" mixture of 50% native soil and 50% compost was spread over the garden area landscaped so that a depressed area was formed.

The compost-amended soil has many potential benefits when instituted with establishment of turf and landscaping, including:

increased water conservation,
increased nutrient retention,
better turf aesthetics,
reduced need for chemical use,
improved stormwater retention, and
cost-savings to the private landowner.

The area was planted with live plants and a two inch Hemlock mulch covering, was placed to prevent erosion from the exposed soils and to protect the plants.

Native plants were selected for their ability to grow in various depths of water and soil moisture conditions.

Pre Construction Photos

Pre-construction	Under stormdrain	End of driveway

Completed Raingardens

End of driveway garden	Under Stormdrain garden

Functioning Raingardens

Functioning garden	Functioning garden	Functioning garden

Click any thumbnail for a larger view. Photos above taken by CEI LID Committee members.