by Brianna Crandall — August 4, 2014—Green roof innovator Vegetal i.D. has announced a collaboration between the Milwaukee Metropolitan Sewerage District (MMSD), Fund For Lake Michigan, The Water Council, the University of Wisconsin (UW)-Milwaukee, and UW-Whitewater to closely monitor the performance of a new stormwater management solution. The technology being tested is an advanced system combining a blue roof with a green roof that is poised to bring green roof-based stormwater management performance to a whole new level.
Green and blue roofs are a component of a new form of low-cost high-impact stormwater management known as green infrastructure, explains Vegetal i.D. The goal of green infrastructure programs is to mimic natural systems in order to manage stormwater on-site and minimize problems such as polluted runoff and basement backups.
The alternative solution involves the expansion and maintenance of traditional grey infrastructure systems, which can be extremely expensive and often do not completely solve the problem, points out the company. This is why cities are turning to green infrastructure systems such as green roofs to deal with rainwater at the source, and minimize taxpayer expenses.
In the Greater Milwaukee Area of Wisconsin, the Milwaukee Metropolitan Sewerage District has spearheaded the green infrastructure movement for over 10 years. The goal, known as Fresh Coast 740, is to capture 740 million gallons of water every time it rains. To achieve this goal the program invests in high-impact green infrastructure such as rainwater harvesting, porous pavement, and bio-swales, and by obtaining key pieces of land to remediate into greenways and wetlands that manage great amounts of stormwater naturally and increase resistance to flooding.
Green roofs absorb and retain water on the roof and use it to grow plants that cool cities, clean water, add biodiversity to urban areas, and improve property values, says Vegetal i.D. “Green roofs are like sponges and absorb lots of water, but when the soil is fully saturated from previous rainfall, it doesn’t have much effect,” according to Galle Bergès, of Vegetal i.D. This is why Vegetal i.D. is launching a new stormwater management complement to green roof systems known as STOCK & FLOW.
STOCK & FLOW is a reservoir below the green roof that adds two inches of rainwater capacity to a traditional green roof, passively irrigates the plants, and controls the way in which water is released from the roof. The system irrigates itself with the water it captures during rainfall, while the excess water retained in the reservoir of STOCK & FLOW is released to the sewer system at a slow and constant rate to make it easier for the city to manage while it is simultaneously preparing it for the next rain event.
This month, Vegetal i.D. and its partners launched a pilot project to demonstrate the performance of STOCK & FLOW. The project will compare stormwater management performance of two versions of STOCK & FLOW, a typical extensive green roof, and a standard roof. They will also measure performance metrics such as the productivity of the plants and their ability to cool the roof.
This study will also assess the costs and benefits associated with these systems. This will enable policy makers and sewer system managers like MMSD to better understand the costs and benefits associated with these systems. The information can be used to better incentivize and regulate stormwater management, which helps to drive the use of green infrastructure solutions.
Vegetal i.D. is a branch of Le Prieuré, an innovation-focused French company that installed its first green roof in 1989. In 2000, Vegetal i.D. patented HYDROPACK , said to be the first modular green roof system in Europe. HYDROPACK is a tray system that is sold fully vegetated, with water reservoirs packed into stackable trays that can be easily transported and installed on rooftops of nearly any pitch. Since its inception, HYDROPACK has been installed on over 2,000 rooftops. The North American branch of Vegetal i.D. launched in 2011.
