A second deep shaft is being dug at Avondale and Lavergne avenues as part of the next phase of the project to replace the Lawrence Avenue sewer in Jefferson Park. View Full Caption DNAinfo/Heather Cherone

JEFFERSON PARK — Crews have begun working double shifts and weekends to finish a $20 million project to replace a 100-year-old sewer designed to keep Jefferson Park homes from flooding, Ald. John Arena (45th) said.

In order to finish the project by December, a second shift will work from 3 p.m. to midnight during the week, and from 7 a.m. to 3 p.m. Saturday, Arena said.

Because crews are working to connect the new sewer tunnel to the city's Deep Tunnel sewer and reservoir system, explosives are being used to blast through the bedrock, officials said.

Blasting will be prohibited after 6 p.m.,, but federal work safety rules require crews to activate an air horn every time workers or material are raised or lowered from the drop shaft near Lawrence and Lavergne avenues, Arena said.

"I know this will be a burden for those living close to the shaft," Arena said. "However, the extra shift is needed to keep the project on schedule."

Crews are expected to work a second shift through October, with the entire project finished by December, officials said.

Montrose Avenue, which has been closed from Cicero to Milwaukee avenues since May, is set to reopen Sept. 1, as scheduled, officials said.

Crews are replacing the crumbling sewer along Lavergne Avenue between Lawrence and Montrose avenue, which has flooded area basements during strong storms, and connecting it to the Deep Tunnel system.

The project started more than a year ago when crews began digging up Lawrence Avenue to reach the sewers and Deep Tunnel.

Since December, crews have been working at Avondale and Lavergne avenues, Lawrence and Lavergne avenues and at Montrose and Lavergne avenues as part of the second phase of the project. Those intersections have been closed since the work began.

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