Example of a green roof.

Green roofs consist of a modified base covered in planting media and vegetation instead of traditional roofing material such as asphalt and tiles.

Under the current project, the green roof BMP will include a controlled experiment and a demonstration component involving a larger roof for pollution load reduction.

The demonstration and load reduction part of the green roof BMP consists of a green roof that will be manufactured by American Hydrotech, Inc. This will be constructed on the front veranda of the Pavilion Building at the Center. This green roof will likely consist of the following components:

• Plants selected for their ability to withstand drought and self -regenerate.
• Engineered lightweight growing medium that has suitable pH range, nutrients, and porosity for plant growth.
• Drainage layer that retains water in profiled troughs, and drains away excess water through channels between troughs.
• Insulation layer that resists moisture and situated above roof membrane and root barrier
• Root barrier that prevents roots from affecting the roof membrane.
• Roofing membrane that is made of Hydrotech's Monolithic Membrane®.
• Structural support that is designed to support the weight of the green roof.

The controlled experiment will feature four roof shelters representative of a residential roof with varying green roof designs. Each roof will be divided into four sections to compare four types of growing media that will include different layers of soil, drainage, insulation and roofing membranes. Plants will be selected to withstand minimal maintenance.

All green roofs will be monitored for rainfall, soil storage, and runoff on a continuous basis. Water samples will be collected from the runoff to demonstrate the effectiveness of green roofs in removing pollutants.