Rosie hasn’t been quite as mighty as anticipated.

When the massive tunnel-boring machine began its mission last October, city officials were hoping its journey would be completed by late May. Now, the estimate is Labor Day.

The machine experienced some challenges when it was mining through a combination of rock and soil. Once it reached full rock, Rosie was able to keep a better pace.

“It’s always difficult to estimate exactly when these projects will be completed because you can’t predict with any certainty what the ground conditions will be,” said Ellen Lander Nischt, a city spokeswoman. “However — knock on rock — we are confident that the remainder of the tunneling should be on schedule.”

The machine, named after a local World War II-era female riveter, began its voyage Oct. 18 at the Little Cuyahoga River north of the Mustill Store on the Ohio & Erie Canal Towpath. It is boring its way to Lock 1 of the canal at West Exchange Street in downtown.

Rosie is both making a tunnel and laying sewer line. The tunnel will be 27 feet in diameter and 6,240 feet or about a mile long.

The tunnel is designed to control sewer overflow at nine locations and will store more than 25 million gallons of storm water. The $184.1 million project is part of Akron’s overhaul of its combined sewer/storm water system to curb sewage overflows into local waterways and respond to a federal environmental lawsuit.

Rosie has completed about 2,500 feet of 6,240 and is almost past Glendale Cemetery, said Deputy Service Director Chris Ludle.

She bored under Market Street and the St. Vincent-St. Mary High School football field without any issues, Ludle said.

The Akron Zoo was concerned the tunnel digging could disturb the animals, which has happened in other cities in which tunnels have been dug, but that hasn’t proved to be a problem, Nischt said.

After Rosie’s trek is complete, the city will begin the second phase of the project, which involves connecting the tunnel to new and existing sewer lines below city streets.

For more information on the project, including updates on Rosie’s progress and live webcam footage of the dirt and rock Rosie is depositing, visit akronwaterwaysrenewed.com/ocit.

Stephanie Warsmith can be reached at 330-996-3705 or swarsmith@thebeaconjournal.com. Follow on Twitter: @swarsmithabj and on Facebook: www.facebook.com/swarsmith.