Flooding has been a decades-long concern for the residents of the Albany Park neighborhood of Chicago, IL. Following a catastrophic flooding event in April 2013, the city pledged to address the problem affecting the residents’ lives, properties and local businesses. The solution was to construct an approximately 1.6-km (1-mile) long tunnel that diverts more than half the river flow during a flood event from the North Branch of the Chicago River (NBCR) to the North Shore Channel (NSC). When the tunnel is filled with the NBCR overflow, the system will operate as an inverted siphon, bypassing approximately 2,000 cu ft/sec of river water during the 1 percent annual chance design event (100-year storm) and less flow for smaller storm events that exceed the NBCR inlet weir elevation. The diverted flow leaves the tunnel system through the outlet shaft by way of the 20-m (64-ft) long outlet structure located along the east bank of the NSC south of the Foster Avenue bridge at River Park. After the NBCR and NSC river levels have subsided, water remaining in the tunnel system will be pumped out by two dewatering pumps installed within the outfall shaft sump.