Today I took several students to see the green and blue roofs on the apartment complex next to the campus. Probably the only blue roof in the city, it works like a green roof except without the plants. We are monitoring to see how often the water overflows and ends up in the storm basin below.
Blue roof stores rainwater, but has overflow pipes that return water to a stormwater basin in the parking area of the apartment complex
The green roofs are planted with seedum, a commonly used because they are hardy and grow in wet or dry conditions. The green roofs cover the 2-story portions of the apartment complex and the 4-story portions have the blue roofs.