MnDOT I-35W Stormwater Storage Facility CM/GC


Heavy rain events along I-35 West in Minneapolis have in the past caused major highway flooding and, despite existing stormwater tunnels, manholes would sometimes blow off due to high water pressure into the interstate. The original 50-year-old tunnel system was inadequate to handle the volume of water. To mitigate flooding incidents, the Minnesota Department of Transportation (MnDOT) contracted a joint venture for construction led by Kraemer North America, to build six concrete underground tanks that hold up to 4.8 million gallons of water and are 42-feet in diameter and 88-feet deep. This $75 million CMGC project featured the Kraemer-Nicholson J.V. advising the engineering teams to select the optimal way to construct these structures with limited access, challenging geology, and extremely high-water tableThe tanks are designed to accommodate a six-year flood event by storing the water while the drainage system catches up and is gradually released through drainage pipes to the Mississippi River. In addition to the shafts, Kraemer was responsible for performing excavation, concrete works, passageway tunneling, dewatering, upper passageways, weir and suspended pipe construction, along with the related mechanical, electrical, pump station, auxiliary lane widening and final site restoration. Over 36,000 cy of excavation was performed at depths to 95 feet, and 26,000 cy of concrete was placed while always dewatering the siteThe leadership of Kraemer North America enabled MnDOT to safely design and construct this innovative and signature project while not interfering with the adjacent freeway reconstruction project.