Rain Gardens as a means to control stormwater run-off at the Galloway Municipal Complex

Elizabeth Asher1, Lee Smith1, Tait Chirenje1, Patrick Hossay1 and Barbara Fiedler2

1Richard Stockton College of New Jersey, 2Municipality of Galloway, NJ

A rain garden (bio-filter) is an on-lot retention of stormwater through the use of vegetated depressions designed to collect, store, and infiltrate runoff. It is often planted with deep-rooted native plants and grasses, and located optimally to receive runoff from hard surfaces such as a roof via a downspout, sidewalk or driveway.

What is a rain garden?

Why use rain gardens? Understanding the importance of rain gardens is vital to not only our homes, businesses, and towns, but also to the ecosystem. Through decades of development, we have covered our once lush and permeable land with impervious roofs, driveways, parking lots, and roads, thereby reducing the site’s pre-developed evapotranspiration and infiltration rates.

Clearing and grading can remove surface depressions that store rainfall. Construction activities also compact the soil and diminish its infiltration rate, resulting in increased rates and volumes of stormwater runoff from the development site. This causes not only flooding, but also lowers the vital water tables below ground. Water tables rely on the infiltration of water over long periods of time.

These underground water storage “facilities” act as natural filtration systems for pollution such as metals, suspended solids, hydrocarbons, pathogens, and nutrients. They feed our rivers and streams which not only provide homes for innumerable species, but also perform other ecological functions.

Rain gardens generally slow down the rush of water from hard surfaces (including lawns), holding water and allowing it to naturally infiltrate into the ground.  Other important features include:

• Filtration of runoff from roofs, driveways and lawns. • Conservation of water resources by reducing the need for irrigation. • They are an aesthetic way for homeowners, businesses and municipalities to help ease storm water problems. • Restoration of the functions of wooded wetlands removed by land development• More efficient absorption of runoff – 40% more than a standard lawn control.• Construction of a rain garden is cost efficient, requires less technical experience – often, no permits or heavy equipment required to install.

A Rain Garden will:• filter runoff pollution and improve water quality• conserve water while recharging local groundwater and protecting rivers / streams • remove standing water from yard and reduce mosquito breeding • create habitat for birds and butterflies as well as increase beneficial insects that eliminate pest insects• reduce garden maintenance, increase garden enjoyment and enhance curb appeal

Rain gardens are especially useful now, given the urgency to treat stormwater as a significant contributor of non-point source pollution. The Stormwater Management rules, N.J.A.C. 7:8 specify stormwater management standards that are mandatory for new major development. The New Jersey Stormwater BMP manual provides guidance for these rules. They establish that stormwater needs to be retained and treated on site for all new major developments, whereas in the past stormwater flowed directly into sewers and subsequently sent to treatment plants.

New Jersey Stormwater Rules

The Galloway Project

Through the Sustainable Communities Initiative led by Drs. Hossay and Chirenje, the Richard Stockton College participates in workshops and projects that help communities improve their energy efficiency and other areas of sustainability.

Two classes taught by Drs. Chirenje and Hossay conducted an environmental audit of Galloway township from January to May 2007. A recommendation from the water group was to reduce stormwater flow from the complex (flows into Patriot Lake).

The objective of the Galloway Project was to build a rain garden that would intercept run-off from the front parking lot of the municipal building before it reached the storm drains and proceeded to Patriot Lake.

Native or low maintenance non-native plants

Precipitation catchment areas

Dr. Hossay’s Municipal Policies and Dr. Chirenje’s Intro to Pollution classes and volunteers have been working on the site since 08/30/07.

Above: The crew spreads the organic top soil, and Ecomat (to reduce soil erosion) and rocks to slow down the flow of the runoff into the garden

Berm to holdwater in basin and prevent overflow

Infiltration basin, must allow drainage of excess water not absorbed by plants

www.urbanwaterquality.org/RainGardens/LIDRG1.jpg

http://www.apwa.net/Images/Publications/Reporter/Maplewood1.JPG

http://www.montgomerycountymd.gov/Content/DEP/Rainscapes/images/garden_head.jpg

http://www.carlson-art.com/lifescience/water-runoff_lg.jpg

Adopted from : http://www.nashville.gov/stormwater/images/raingarden_BarrExample2.jpg

Acknowledgements

Rain garden schematic

Choice of plants depends on soil type, amount of shade and water reaching garden

Flow channels designed to reduce erosion

Advantages of using rain gardens

Challenges

Some local homeowner’s rules are not flexible enough to allow rain gardens in front yard; the cultural aesthetic of “lawn appeal” is difficult to change, and rain gardens not widely promoted by developers and municipal governments.

The authors would like to thank Mr. Conover and Berenato from the Atlantic County Utility Authority for their ecosoil donation and student volunteers who donated their time on this project. Funding for the project came from the Richard Stockton College Day of Service Committee to whom we are grateful.

Six months later

Seven months later Eight months later