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

For more information on these raingardens follow the links below.

This photo was taken on July 21, 2005.

Comprehensive Environmental Inc (CEI) provided funds for this Low Impact Design (LID) raingarden Project located in the Winnepesauke River Watershed just upstream of the confluence with the Pemmigewasset River that forms the Merrimack River, in the Town of Franklin, 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 was visible to the public
an area that would provide an educational benefit

The area for the raingarden is along side of the homeowner's driveway. It utilizes an existing grassy depression to treat runoff from the remaining driveway and reduce overall runoff from the site (i.e. roof). A portion of the roadway runoff from the street is incorporated by a diversion berm; however, flows will be high since there is no drainage system for the street

An educational sign was installed in the rain garden.

Construction of Rain Garden

On April 30, 2005 the garden area (12' x 24') was excavated, and on May 1, 2005 the garden was landscaped. Because of multiple storms the plantings were not placed until May 23, 2005. The garden was completed on May 23, 2005.

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 holed area was then covered with filter fabric and filled with bricks and rock provided from the homeowners property.

The rock area was covered with the filter fabric and 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 on May 23, 2005 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

Desired locations

During-construction Photos (04-30-05 thru 05-01-05)

Preparing area	More preparations	Digging hole

During-construction landscaping Photos (05-01-05 thru 05-23-05)

Filling hole with bricks	Landscaping area	Completed landscaped area

Functioning Garden Photos

Functioning raingarden	Functioning raingarden	Functioning raingarden

Summer Photos

Completed garden July 12, 2005	July 21, 2005

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