Granite wins $215m sewer overflow tunnel contract

Map showing the route of the NSIT tunnel through Akron, Ohio (Image supplied by Granite)

US construction contractor Granite has won a $215 million contract to build a tunnel aimed at preventing sewer overflows in the city of Akron, Ohio.

Granite will build the Northside Interceptor Tunnel Project (NSIT) to prevent sewage entering the Cuyahoga River during typical storms.

The project’s primary structure will be a 16.5-foot (5 metres) internal diameter tunnel along the river. The tunnel will consist of 6,600 linear feet (2km) of precast-concrete-segment-lined rock tunnel.

It will also feature an array of control structures, flow drop shafts, connecting sewers and overflow structures.

The aim of the tunnel is to prevent combined sewer overflows by collecting overflows at four locations and storing them. The storage capacity of the tunnel is more than 10 million gallons (37.9 million litres).

Granite vice president of regional operations, Jim Nickerson said, “Spanning 6,660 feet in length and descending over 100 feet below ground into rock NSIT will be a feat of engineering and is set to become a symbol of innovation and environmental stewardship for the entire region.

“We have a great working relationship with the City of Akron from the previous Ohio Canal Interceptor Tunnel Project. The city is committed to contracting work to local firms and our contracting plan was able to exceed Akron’s local contracting goals and provide major economic benefit to the community.”

The project is planned to begin in September 2023 and is expected to be completed in July 2027.