Today marks the final work in the digging phase of the Deep Tunnel project, a massive 109-mile tunnel system designed to keep stormwater out of area basements and waterways. Digging started in 1976, in response to the 1972 Clean Water Act. Although today marks the end of the digging phase, concrete walls still need to be put into the tunnels, in the hopes of opening the project's tunnels by 2006.