A Special Earth Day Project Maintaining Green Roofs

A Special Earth Day Project Maintaining Green Roofs

by Dr. Carol Pollio

Program Director, Environmental Science at American Public University

Earth Day in Washington, D.C. this year started out a chilly 41 degrees. But the weather did not stop eighteen motivated folks from doing a service project to recognize the significance of the day. At 9 a.m. recent APU graduate Laura (Stopper) Batts led a team of National Park Service staff members, including APU student Tonya Watts, and me in weeding the Office of Natural Resources and Science’s green roof .  Armed with gloves, trowels, and trash bags, the group quickly got to work removing exotic and woody plants from the roof.

The green roof has been in place since 2005.  Green roofs have many benefits:

• Retention and filtering of rainwater

• Reduction of building heating and cooling costs as well as energy use

• Mitigation of  the urban heat island effect

• Improvement in air quality as plants capture airborne pollutants and release oxygen into the atmosphere

Green roofs are divided into two categories: intensive and extensive.  Intensive green roofs usually consist of a thick soil or substrate capable of supporting root growth for larger shrubs and trees.  Extensive green roofs normally feature a thin layer of soil or substrate, providing the same benefits as intensive roofs, without the weight.  Extensive green roofs are much more easily used retrofitted on existing structures, as was the case here, because they are lightweight as compared to intensive roofs.

This green roof is in the extensive category, consisting of 3 inch deep 2 ft. x 2 ft. square plastic trays, covering 7,000 square feet of the flat roof’s surface.  Despite the shallowness of the trays, plant seeds from a variety of exotic plants and woody species find their way into them, requiring periodic weeding, watering, and general maintenance.

Now back to our weeding team. Batts is a recent M.S. honor graduate APU in Environmental Policy and Management and a volunteer with the National Park Service. She volunteered last year to manage the roof and develop a maintenance plan for its upkeep over the coming years.  Watts is a new student at APU in the Environmental Science Bachelor’s program and a hydrologic technician (student trainee) with the National Park Service.  I manage the staff at the National Park Service and I’m ultimately responsible for the upkeep and maintenance of the green roof.

The spirit of the group remained high all morning, despite the chilly breeze and only brief peeks at the sun through the clouds.  After three hours, the group had finished preparing the green roof for a new growing season.  A celebration picnic was held and everyone settled in to watch the documentary film, “Thin Ice: the Inside Story of Climate Science ” as a fitting close to the day’s events.

About the Author:

Dr. Carol A. Pollio is the Director of the Environmental Science program at APU, and is the Chief of Natural Resources and Science for the National Park Service, National Capital Region. Dr. Pollio’s experience in the National Park System includes gaining expertise in abandoned mine reclamation, environmental contaminants remediation, and biological assessment of disturbed and contaminated sites. She has conducted scientific research, inventory and monitoring, and published her results in several peer-reviewed journals.


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