As communities across North Carolina continue to develop into jungles of impervious concrete, mitigation of issues such as stormwater and polluted runoff have become more imperative. This sense of urgency has sparked awareness across the state to alleviate this infiltration of polluted runoff into our lakes and streams. But what exactly is stormwater and polluted runoff and what is the Museum’s contribution to cleaner water?

Impervious surfaces such as parking lots, driveways, homes and paved walkways are often referred to as “stormwater superhighways”. Rainwater that once infiltrated the ground is now carried over these impermeable surfaces on their way to storm drains, and eventually our streams. Along the way, this stormwater is picking up pollutants, pesticides and fertilizers, automobile oil and sediment and depositing them into nearby bodies of water. Sediment carried by stormwater is North Carolina’s number one source of pollution in streams. This overload of sediment can ruin an aquatic ecosystem, wipe out fish and freshwater mussel populations and increase the chances of flooding.

In January 2005, six Museum Youth Partners were chosen to work with two Museum staff on a year and one half long project called MODELS (Mentors Opening Doors: Experiential Links to Science). Funded by the Burroughs Wellcome Fund and the Environmental Education Fund, MODELS is designed to introduce 18 area high school students (over three years) from the Museum’s Youth Partner program to scientists involved in research happening in the Triangle. This year’s group of six students spent the spring exploring science topics primarily related to stormwater and polluted runoff. The MODELS Youth Partners will finish their commitment by creating science lessons that they will teach through workshops for area teachers during the spring of 2006.

Over the past six months, the MODELS group attended a dozen evening inquiry sessions focusing on stormwater and polluted runoff. Twelve subsequent Saturday sessions were spent in the field observing North Carolina’s solutions to reducing stormwater as well as exposing the students to field research. All sessions were led by area scientists and professionals in the environmental field.

Using the knowledge that they acquired this past spring, the MODELS set out to design their summer project. A decision was made to construct a rain garden just above the Magic Wings Butterfly House to capture the stormwater runoff from the walkways leading from the Museum’s Caterpillar Café and Train Station.

A rain garden is basically what it sounds like–-a landscaped area that soaks up stormwater from impervious surfaces rather than allowing it to enter storm drains or sewers. Each rain garden may seem small, but collectively they lead to a healthier environment. The benefits of rain gardens are numerous. A reduction of flooding occurs when the amount of stormwater that enters our streams is decreased. The beautification of backyards, neighborhoods and businesses is achieved while providing valuable habitat for birds, butterflies and many beneficial insects. Rain gardens also replenish ground water and regional aquifers while the plants help remove harmful pollutants.

With their knowledge and skills finely tuned, the MODELS were ready to begin the design of their rain garden. Surveying instruments were used to determine the area of impervious surface that would drain into the garden. The total drainage area was calculated to be around 3,300 square feet. Using this figure they then calculated the minimum size of their garden in order to capture all of the runoff. For a rain garden to function properly, its size needs to be at least 5% of the total drainage area. This meant that their garden needed to be at least 170 square feet. With Durham’s average annual rainfall of forty-three inches, the rain garden could capture approximately 90,000 gallons of stormwater; water otherwise headed into the Ellerbe Creek.

With all the statistics clearly defined, the MODELS went to the drawing board. Each student completed four drawings to scale: 1) a bird’s-eye view of the total drainage area (picture 2), 2) the dimensions and placement of the rain garden, 3) a list of all the plants and wildflowers and their placements within the garden (picture 3) and 4) a cross-sectional view of the garden looking at plant height and drainage considerations.

Before any plants were chosen, the MODELS participants were required to research the types of plants that would survive brief periods of inundation normally associated with rain gardens. The MODELS discussed each plant’s origin, soil and water requirements, aesthetics, height, flower color, fall foliage, nectar production and whether it could serve as a food for butterfly larvae. It was decided that the garden would be planted entirely with native plants and wildflowers.

A native plant is a plant that naturally occurs in its indigenous area prior to human disturbance. They are well adapted to our climate with a built in resilience to temperature and rainfall fluctuations. They attract more wildlife such as butterflies and birds; require fewer fertilizers, pesticides and watering and, most importantly, are part of the region’s intricate web of life.

In August 2005 the MODELS group broke ground on the construction of their rain garden. The completed garden now serves as an outdoor exhibit for both Museum visitors and private landowners. The MODELS will staff the rain garden to help educate visitors on the importance of rain gardens, gardening with native plants and the conservation of our rivers and lakes. They will also host workshops next spring for both area teachers and the public to learn more about rain gardens and other stormwater-related issues.

Unless we act now as curators of the earth, stormwater and polluted runoff will continue to impair our waters and flood our neighborhoods. Next time it rains, throw on your rain jacket, grab the umbrella and take a walk outside around your house. If you do not mind getting too wet, take a stroll around the neighborhood. Look for impervious surfaces such as rooftops and driveways. Observe the water as it travels through stormwater superhighways destined to find its way to the closest storm drain. While on your walk, please remember, we all live downstream!

Special thanks to the following individuals for their wisdom and support of the MODEL program:
Mitch Woodward, North Carolina Cooperative Extension Service
Laura Webb Smith, City of Durham, Department of Public Works, Stormwater Services Division

Links of Interest: 

http://www.bae.ncsu.edu/topic/raingarden/ 

http://www.ncstormwater.org/

http://www.bae.ncsu.edu/people/faculty/hunt/

http://www.ncwater.org/