"Call before you dig" heh yeah whatever.

In 1992, a construction accident near the Kinzie Street Bridge produced a breach connecting the Chicago River to a tunnel below, which was part of an abandoned freight tunnel system extending throughout the downtown Loop district. The tunnels filled with 250 million US gallons (1,000,000 m3) of water, affecting buildings throughout the district and forcing a shutdown of electrical power. The area was shut down for three days and some buildings did not reopen for weeks; losses were estimated at $1.95 billion.

hm. okay. maybe then.