Tower footer gets new legs

By Jeff Norwood

Thanks to a great team effort by the Transmission Maintenance group, Transmission Line Services (TLS), and two National Grid contractors, a complex repair of a transmission tower footer was completed safely and efficiently.

A crane is used to support the structure so that crews can make repairs.

According to Marc Bristol, manager, Transmission Maintenance, his team is responsible for a number of inspection and maintenance programs across National Grid’s transmission network in New England and New York.

The inspections take several forms, including visual and infrared helicopter inspections, visual ground patrols, pole inspections, and tower footer inspections. This past summer, our contractor was performing tower footer inspections and repairs in Billerica, MA, a community north of Boston.  A portion of this line would normally be inspected in the winter when the ground is frozen with special equipment. Outside of winter, these structure footers are typically submerged in a few feet of water.  However, because of persistent drought conditions in 2016, accessing these structures for inspection was much easier.

The inspection revealed that a leg on one structure was completely rotted, and the other three were in bad condition.  Typically, the same inspection crew would make any steel repairs and install temporary structure supports as needed, but given the condition of this 60-foot-tall tower, this approach was deemed inadequate and unsafe and a safer method was required.

The deteriorated legs of the transmission structure.

Ben Herbert, a senior supervisor on Bristol’s team, efficiently coordinated the effort to undertake the complex repair job with TLS. TLS was able to offer a safer structure support method, which included lifting the entire structure using a crane. Once lifted slightly, the footer crew was able to safely cut out and replace the rotted steel.

Typically, according to Bristol, this type of inspection and repair would take less than one week.  However, due to the poor condition of the footers, coordinating efforts, and the complexity of the required repair, this was extended it to six weeks.

“This is a great example of a successful collaboration among internal teams and contractors to deliver a complicated project quickly, safely, efficiently and in an environmentally responsible way,” said Fred Raymond, vice president, Electric Project Management and Complex Construction.

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