PETERBOROUGH — Nearly a month after a drilling rig tipped over on Route 202 while working on the Main Street bridge construction project, crews on Monday began the process of righting it.

The work will continue Tuesday and is being done by the project’s general contractor, Franklin-based Beck & Bellucci Inc.

The intersection at Main Street will be closed both days between 7 a.m. and 7 p.m. Drivers are being detoured onto Route 101 and Route 137.

The 90-ton rig tipped over the morning of April 22 while working on the retaining wall portion of the bridge project, landing near the Contoocook River. The cause of the incident — which did not result in any injuries — is still undetermined, according to Seth MacLean, Peterborough’s director of public works.

Teams met daily over the past few weeks to prepare for the rig’s removal, he said in an email. Engineers determined detailed plans to manage and properly distribute the weight of the rig once it’s pulled up onto Route 202, he explained.

The rig was resting against a newly rebuilt section of the Route 202 retaining wall, so after the situation was reviewed for safety, MacLean said, engineers determined no additional stabilization was required.

Starting Monday morning, a tow truck, three rotators and an excavator were coordinated to counterbalance the rig’s weight, and to bring the machine upright in incremental stages, according to MacLean.

Because the Route 202 portion of the project is is being done independently of the Main Street bridge, he said he does not foresee any significant delays to the bridge’s reopening.

Peterborough is replacing the 1940s bridge that connects Main Street to Route 202 across the Contoocook River because it has been on the state’s “red list” of structurally deficient bridges since 2006, a town official told The Sentinel last year.

Voters appropriated $6.6 million for the project two years ago, and in January, authorized another $1.4 million in a specially convened town meeting. Federal funds will cover 80 percent of the cost, with the town bearing the remaining 20 percent.

Construction on the site began in the spring of 2020, town officials said previously.

The Route 202 retaining wall work is funded entirely by federal and state money, MacLean explained, so while both projects are running concurrently and through the same contractor, they are “largely independent of one another in terms of the finances, crews, subcontractors, and scheduling being utilized for each.”

The bridge project was able to continue work the day after the incident, but the retaining wall work has been stalled since, he added.

At this point, MacLean said, the bridge is still slated to open at the end of the year. The project team will discuss the incident’s implications on the retaining wall project after the rig’s removal, he said.

Beck & Bellucci Inc. will be covering the costs to right the rig, which aren’t “fully known at this time,” according to MacLean. The company could not immediately be reached for comment Monday.

Olivia Belanger can be reached at 352-1234, extension 1439, or Follow her on Twitter @OBelangerKS.