University of Minnesota Ambulatory Care

Project Details: Stormwater detention system was installed under the driveway of a new multi-story Ambulatory Care.

Challenge: The main challenge of the project was that there was a very limited footprint available as most of the site is building. There was just 5’ of headroom to work with from rim to invert.  Due to the multi-story nature of the property and the fact that the driveway area is considered a fire lane, the solution needed to be able to support fire truck outrigger loads with minimal cover. In addition, the site had contaminated soil so the solution needed to be watertight.

Solution: Most flexible stormwater detention options require around 3’ of cover to handle fire truck outrigger loading which meant those options could not store the volume required in the available footprint. StormTrap custom designed a detention vault system with an 8” roof slab and extra strength concrete that can handle the outrigger loads with only 12” of cover.   This allowed StormTrap to use a 3’-4” internal height system to achieve the required volume within the available footprint area while also notching around a building overhang footing.  A geomembrane liner was specified by the engineer to make the system watertight and protect it from the contaminated soil.