Extension Master Gardener Volunteers Solve a Stormwater Problem

— Written By

Garden

Extension Master Gardener℠ volunteers of Orange County recently received the 2020 Search For Excellence Award in the Demonstration Garden category for their efforts to turn a problem area into a stormwater management demonstration garden.

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It all started when an Orange County Parks and Recreation staff member asked N.C. Cooperative Extension for help with a frustrating area in the courthouse parking lot, where stormwater regularly overflowed and washed out silt. “During large rain events, water running off this bed contributed to silt buildup in the courthouse’s cistern system,” recalls Extension agent Mart Bumgarner. “If the runoff could be slowed, the cistern system would be less likely to clog. And in the process, an unsightly area would be transformed into a beautiful garden that illustrates how careful design can solve structural problems like stormwater runoff.” 

parking lot median bed

Before planting, compacted soil contributed to stormwater runoff.

At the Orange County Courthouse parking lot, this garden proves how plants can slow stormwater runoff. The project provided an in-depth, hands-on experience for students participating in the 2018 Extension Master Gardener volunteer training class. The process began with site visits, observation of the site during rain events, and research on plant materials that would suit the conditions. Next, small groups of Master Gardener volunteer students, guided by their mentors, drafted designs for the space. Swales, rocks, grasses, and plants were incorporated into the design to capture and slow stormwater. Individual designs were presented to all members of the Master Gardener volunteer training class. Over time, components from the designs were merged into one cohesive landscape plan. “This project helped establish relationships between the new class of Master Gardener volunteers and their mentors”, notes Master Gardener volunteer mentor Mary Leonhardi. “Getting to know one another while learning together creates bonds that make the program stronger and helps keep Master Gardener volunteers engaged and active.”

stormwater demonstration garden images

The use of swales, gravel, and carefully chosen plant materials illustrate stormwater management strategies.

Once the design was finalized, a significant part of the project included the removal of compacted soil. For help with this, Master Gardener volunteers turned to Hillsborough Boy Scout Troop #438. “The Boy Scouts helped with the tedious job of digging out the existing soil and the Parks and Recreation Department hauled it away,” remembers Bumgarner. Master Gardener volunteers were then able to add compost and prepare the bed for planting. 

Plant materials selected to thrive in the difficult conditions include shrubs and perennials with a concentration on native plants. Viburnum (Viburnum obovatum ‘Mrs. Schiller’s Delight’), sweet flag (Acorus gramineus), Stokes aster (Stokesia laevis), and green and gold (Chrysogonum virginianum) are just a few of the many species in the garden.

garden bed in parking lot

Stepping stones through the garden bed accommodate pedestrians.

Plants were generously donated by area nurseries, the NC Botanical Garden and Master Gardener volunteers. Out of pocket expense for the project was under $400 thanks to donations of materials including soil, compost, gravel, stepping stones, stone, and mulch,” recalls Meg Molloy, a member of the 2018 Extension Master Gardener volunteer training class. By far, the largest contribution was the time donated by Master Gardener volunteers to design, install, and maintain the garden, an invaluable contribution to the community. “The partnership between the Extension Master Gardener program and the Orange County Parks and Recreation Department helped this project succeed and their contributions are ongoing. Parks and Recreation bring us mulch, and even shared watering duties as the garden was getting established,” says Bumgarner. As the garden matures, Extension Master Gardener volunteers continue to provide leadership for maintenance and workdays provide valuable experience for new Master Gardener volunteers.

Sharing information about the plants in the garden was an important goal of the project. Once the planting was complete, Margi Stetson, a member of the 2018 Extension Master Gardener volunteer training class, made a plot plan on paper. “Rather than include individual plant labels, which can be difficult to maintain, we decided to provide information about the plants on our website,” shares Stetson. Interpretive signage directs visitors to The Orange Gardener, a website maintained by Master Gardener volunteers. On the site, Master Gardener volunteer Leigh Simpson skillfully transformed Stetson’s plot plan into an interactive map. This lets visitors to the courthouse or nearby farmers’ market go to the website, learn more about a plant they see in the garden and consider planting it in their own yard. 

diagram of planting plan

An interactive plant map provides plant information.

Results of this project are impressive: a pre-garden water survey showed that only 20% of the stormwater entering the bed during a rainstorm was absorbed by the soil and existing plant materials. That meant that 80% was running off into the parking lot. Now, the bed literally holds its own, with 100% of stormwater being absorbed by the garden.

parking lot median bed with gravel path

100% of stormwater is now absorbed by the bed rather than running off into the parking lot.

We applaud the Master Gardener volunteers of Orange County for their efforts to design and install a stormwater demonstration garden in a highly-visible location while educating both new Master Gardener volunteers and the general public. 

Special thanks to project leader Mary Leonhardi, garden coordinators Susan Manning and Margi Stetson, mentors Frances Harris, Ginny Phelan, Dana Klimas, and Lorraine Tuck, and website designer Leigh Simpson.

Congratulations to Master Gardener volunteers Sharon Billings, Marie-France Eloi, Ann Gleason, Luke Grasty, Sherrie Hardy, Jenny Hester, Laura Juel, Donna Kaye, Meg Molloy, Margaret Olson, Mary Beth Powell, Gigi Rashdi, Tommy Tuck, and Jan Watters.

To learn more about the Extension Master Gardener program in Orange County, contact Mart Bumgarner N.C. Cooperative Extension horticulture agent, 919-245-2062.

ABOUT the North Carolina Extension Master Gardener Program

NC State Extension Master Gardener volunteers connect people to horticulture through science-based education and outreach that empowers North Carolinians to cultivate healthy plants, landscapes, ecosystems, and communities. To learn more about the NC State Extension Master Gardener program in your community, contact your local N.C. Cooperative Extension center.