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 blocked Lavergne Avenue at Montrose Avenue Monday as part of the second phase of a $20 million project to replace a 100-year-old sewer in an effort to keep Jefferson Park homes from flooding.

Eastbound Lawrence Avenue is set to reopen Dec. 24 as the first phase of the project wraps up, and crews concentrate on work at Avondale and Lavergne avenues and begin work at Montrose and Lavergne avenues.

Crews have been working since August to tunnel under Lawrence Avenue to replace the crumbling sewer, which has flooded area basements during strong storms — at times using explosives to blast their way through 200 feet of bedrock to connect to the city's Deep Tunnel.

Two deep shafts are being dug at Avondale and Lavergne avenues as well as at Montrose and Lavergne avenues as part of the next phase of the project. No explosives will be used in either location, Ald. John Arena (45th) said.

The two Lavergne Avenue intersections — often used by residents as a way to avoid perpetually congested Cicero Avenue — will be closed for several months.

For more neighborhood news, listen to DNAinfo Radio here: