How is the Tunnel Built?

Construction on the tunnel shafts began in January 2018. 

The tunnel-boring machine will arrive at the site in numerous shipments throughout September and October 2018. It will be lowered into the tunnel in pieces and reassembled for operation. It will dig a tunnel 20-feet in diameter and approximately 200 feet below the surface, which is more than 18 stories below ground. The tunnel can store up to 55 million gallons of combined rainwater and wastewater when complete.



Construction Schedule

Working Shaft and Pump Station Shaft Construction Start:

January 2018

Working Shaft and Pump Station Shaft Construction Finish:

July 2018


Retrieval Shaft Construction Start:

April 2018

Retrieval Shaft Construction Finish:

November 2018


Tunnel Boring Machine Arrival and Setup:

September 2018

Tunnel Boring Begins:

October 2018

Tunnel Boring Finishes:

September 2019


Tunnel Concrete Lining Start:

August 2019

Tunnel Concrete Lining Finish:

June 2020


Tunnel Substantially Complete / Operational:

July 28, 2020


Final Completion:

September 26, 2020


Consent Decree Deadline:

December 31, 2020