Up on the Roof -- The Green Roof

How often do you notice a roof? If it's the roof on the Richmond Department of Public Utilities' (DPU) Wastewater Treatment Plant effluent filtration building, you'll be sure to notice it because it is green and covered in plants.

A green roof is a permanent rooftop planting system that contains live plants. DPU installed this green roof in the fall of 2010. The building's existing roof is able to withstand the added weight of the plants.

Green roofs offer numerous benefits:

• Stormwater runoff reduction: Green roofs can absorb up to 99 percent of one inch of rainfall. Water is slightly filtered as it flows through the soil. Even during heavy rainfall, water is delayed running off the roof, allowing additional time for the sanitary sewer system to catch up.
• Energy savings: Green roofs provide natural insulation and can reduce heating and cooling costs. During summer months, the green roofs absorb sunlight and heat.
• Wildlife: Plants provide natural habitat for birds and small mammals.
• Noise reduction: Studies have shown that green roofs can reduce sound by as much as 40 decibels.
• Longer life than traditional roofs: Green roofs are better protected against ultraviolent radiation, large fluctuations in temperature, drying winds and punctures.

An added bonus is a roof covered in plants is attractive. They provide long-lasting blooms and a change of scenery for city workers. Plants on this green roof include sedum, alliums and euphorbia, all drought-tolerant, low-maintnenace varieties with a shallow root structure.

Green roofs are not new. They have existed for thousands of years and only now are experiencing a resurgence. Consult an engineer to install a green roof on your home or business for environmental and financial benefits, or just to have a peaceful place where the air is fresh and sweet "up on the roof."