What the Metropolitan Water Reclamation District refers to as "mining" ended yesterday afternoon, when 30 years of excavation for Chicago's Deep Tunnel Project was concluded.
A massive tunnel boring machine sawed through the last of the limestone near south-suburban Riverdale to connect two sections in the Little Calumet Leg.
A group of 26 engineers, officials and journalists stood in the bottom of a construction drop shaft hundreds of feet below surface to witness the event.
The end of the digging does not mean the project is complete. Finishing touches have to be put on some sections of the 109 mile long tunnel, and another reservoir opened. Nevertheless, enough of the tunnel has already been finished that it is doing its job flood-control.
"It will be all finished and operational in early 2006," said MWRD spokeswoman Peg Bradley.
MWRD started Deep Tunnel in 1972 in response to the Clean Water Act, so that flooding could be prevented and the water from what flooding might still occur would not end up in the waterways.