McCormick Place Stormwater Tunnel

McCormick Place Stormwater Tunnel project includes the construction of the stormwater outfall tunnel and three shafts to direct stormwater from the new 61.8-acre facility roof out under Lake Michigan to an outlet shaft on Northerly Island. This work accompanies a 2.2 million-square-foot expansion of the McCormick Place Convention Center.

The design-build team designed the tunnel and shafts to accommodate a 100-year storm event with a system flow capacity for stormwater run-off of 497 cubic feet per second. The team designed and built the outfall tunnel to reduce impacts on the century-old storm sewers and to create more water resources for Lake Michigan.

Atkinson constructed the 3,450-foot-long, 12.5-foot unlined inside diameter stormwater tunnel through limestone rock using a Tunnel Boring Machine (TBM). We also drilled and blasted the three shafts and TBM starter tunnel.

The shafts consisted of a 7-foot diameter, 200-foot-deep drop shaft on the convention center site, a 20-foot diameter, 235-foot-deep outlet shaft on Northerly Island, and a 155-foot-deep, 22-foot diameter shaft adjacent to Lake Michigan.

Atkinson also performed cutoff grouting in the shafts and tunnel and installed four tide flex valves.