Stormwater Management

Stormwater Management on the Roof

Climate Change continues to create challenges for municipalities and building developers who need to handle increasing amounts of stormwater. Denser developments, especially in urban areas, often have very limited space for the typical stormwater management techniques. More municipalities are requiring developers to detain larger volumes of water on their sites and to delay the entry of that water into the storm sewer systems. Rooftops are one of the last areas of the development site where highly effective stormwater management BMPs can be employed to deal with rainfall where it lands before it has a chance to immediately run down the drain.

Hydrotech has been involved in stormwater management on rooftops for many years and provides components such as LiteTop® growing media and plant materials that are used to mitigate the effects of stormwater. As time has progressed, Hydrotech continues to stay in the forefront of rooftop stormwater management by offering a wide variety of Assemblies to handle ever increasing amounts of stormwater.

One example is the Northwestern University - Simpson Querrey Biomedical Research Center, where Hydrotech provided its Garden Roof and Blue Roof Assemblies to address
the following obstacles: 

• It was an existing site where caissons were remaining in place, which meant that any underground water storage tank would need to be placed 45 feet below grade.
• The project is located along Lake Michigan in Chicago, which has a high water table. Any underground storage tank would need to have plumbing and electrical running
  to it to dewater the tanks. 
• The project was going to be lot-to-lot construction so there was no room at grade for other stormwater management systems. 

After implementing Hydrotech's Garden Roof and Blue Roof Assembly, the design team was able to detain all 10,000 cubic feet of stormwater on site by taking advantage of the available and usable rooftop space. This satisfied the site's required stormwater detention while adding the additional benefits of a vegetated roof, which include reducing the urban heat island effect, extending the life of the waterproofing membrane, and reintroducing and increasing biodiversity in the urban area.