From the Chicago Tribune:

Chicago’s Deep Tunnel was billed as an engineering marvel that would “bottle rainstorms,” but one of the nation’s most expensive public works projects was no match for the biggest rainstorm in the city’s recorded history.

Last weekend’s deluge quickly saturated aging sewers in the city and suburbs and soon overwhelmed the Deep Tunnel, a cavernous $3 billion backup system built to prevent flooding and protect Lake Michigan, the Chicago River and suburban waterways from water pollution. Read more.