BELLEVIEW, Ky. (AP) Work has started on a massive project to build a tunnel that will carry sewage across western Boone County to a new treatment plant on the banks of the Ohio River.

The $109.4 million tunnel will be about 6 mi. (9.6 km) long, 8.5 ft. (2.6 m) in diameter and up to 300 ft. (91 m) underground, The Kentucky Enquirer reported. Sanitation District No. 1 of Northern Kentucky recently broke ground on the project.

“It’s kind of mind-boggling, a project of that scope happening right here in our backyard,” said board Chairman Bob Elliston. “We’re proud to be associated with such world-class technology and its utilization here.”

Contractor McNally/Kiewit plans to drill 1,000 ft. (305 m) each week for the next 12 to 18 months, said John Swann, construction manager for the sanitation district.

Crews also will build five access shafts at various points along the tunnel for future maintenance and repairs. The tunnel will be made by a 65-ton (59 t) tunnel-boring machine. The 80-ft. (24 m)-long machine has a drill head about 12 ft. (3.6 m) in diameter and powered by four 150-hp (112 kW) hydraulic engines. It will cut the ground at an angle, filtering the dirt out of the tunnel via a conveyor belt on top of the machine.

Crews will install steel ribs at 5 ft. (1.5 m) intervals as they drill to support the shaft.

The concrete tunnel itself, which is designed to last 100 years, will be installed after all 6 mi. are finished. Crews will work around the clock in two shifts: drilling 20 hours per day and doing maintenance on the tunnel boring machine for four, the newspaper reported. There are more than 100 people on the crew, about 70 percent of them Kentuckians.

The tunnel will run from Camp Ernst in Union to the treatment plant, near the intersection of Kentucky 20 and Kentucky 19 in Belleview.

Construction on the $69.2 million plant began in June. It and the tunnel are expected to be operational in 2013.

The project is designed to alleviate the burden on the Dry Creek treatment plant in Kenton County. The tunnel also will be used to store excess water after heavy rains.

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