Akron in Ohio, US, has granted American construction company Granite a $215m contract to build the Northside Interceptor Tunnel Project (NSIT).

This project will help prevent combined sewage overflows (CSOs) from affecting the Cuyahoga River during storms.

The Ohio Environmental Protection Agency’s (EPA) Water Pollution Control Loan Fund is financing the project.

NSIT is a critical component of the US EPA’s mandatory consent decree and is expected to transform the sewage system of the city and drastically decrease CSOs.

A tunnel that is located along the Cuyahoga River serves as the major component of the project and will play a key part in reducing CSOs by collecting and storing overflows at four locations.

This storage capacity of over ten million gallons is said to reduce the environmental repercussions of CSOs while protecting surrounding waterways.

One of the main components of this project is a 6,660ft long, 16.5ft diameter precast concrete segment-lined rock tunnel that is intended to support combined sewage storage and sewage flow in both dry and rainy conditions.

Furthermore, the project includes several control structures, connecting sewers, flow drop shafts, and overflow structures.

Granite Regional Operations vice-president Jim Nickerson said: “Spanning 6,660ft in length and descending over 100ft 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 scheduled to commence this September and be finished in July 2027.