The Queen Anne Avenue neighborhood in east Medford has a time bomb ticking under its alleys.

The approximately 100-year-old sewer pipes are failing and need to replaced.

Medford City Council voted unanimously Thursday to authorize a nearly $505,952.59 contract with Northcore USA LLC to replace the pipes.

Northcore was the lowest of three bids received by the city for the project. 

The other bids were from Central Pipeline Inc. for $565,020 and Whitaker Construction Company Inc. for $626,060.

The sewer pipes in the neighborhood “are at risk of imminent failure,” according to a report from Public Works.

Located behind Roosevelt Elementary School, the alleys connect to Academy Place.

The three alleys are located between Queen Anne and Reddy Avenue, Reddy and Euclid Avenue, and between Euclid and Main Street. Some 50 houses are located around the alleys.

Over the past 20 years, Public Works has had ongoing maintenance to deal with deterioration and root intrusion, but the pipes are too degraded from multiple failures and spot repairs.

Since 2016, other parts of the city have seen pipe repairs with a trenchless technology that wraps the inside of the pipe with a cured-in-place plastic.

Crews line the inside of pipes with felt and then saturate it with epoxy, and they inflate and cure it.

The city prefers to use the cured-in-place method to treat pipes because it requires less digging in roads, less disruption to neighborhood and is generally far cheaper.

Because the three alleys near Queen Anne are so narrow and the pipes are so degraded, this type of technology wouldn’t be possible, according to the Public Works report.

Also, the relatively short length of the pipes has many connections to the sewer lines leading to houses, which is more difficult to deal with for the cured-in-place plastic.

Originally, the sewer line replacement was scheduled for the 2021-23 biennial budget. However, the Medford Water Commission has been replacing water mains in the same area, though this work is scheduled for completion by the end of the month.

The city has been actively fixing old sewer and storm drain pipes. More than four miles of pipes were treated with the cured-in-place liner over the summer at a cost of almost $2 million.

Prior to the treatment of four miles of pipeline over the summer, the city has used the cured-in-place technology on 120,284.2 feet of sewer pipe and 22,752.7 feet of storm water pipe.

Many of the aging pipes are made of concrete and have cracked over time, creating leaks and allowing root intrusion. The city has 280 miles of sewer pipe, about half of which are concrete pipe.

Excess water flowing into the lines also puts a burden on the city’s sewage treatment plant.