Metro West Water Tunnel, Massachusetts

The Norumbega Covered Storage Facility, located next to the Massachusetts Turnpike in Weston, holds 115-million gallons of drinking water, and sits atop a vertical shaft, Shaft N, that extends 400 feet down to the main tunnel for Boston's water supply, the Metro West Tunnel. The Metro West Tunnel is a 15-foot diameter shaft, 17.6 miles long (extending the length between loop highways 495 and 128), bored through largely solid granite underneath suburban Boston. Built between 1996 and 2003, at an estimated cost of $665 million, the tunnel carries 85% of Boston's water supply, and enabled the leaky Hultman aqueduct to be shut down and repaired. The Hultman, which runs along the surface of the ground, is visible adjacent to the Norumbega storage facility.