On the morning of June 20, 2021, Andrew Hallett faced a career-defining moment. A senior project manager at Pittsfield, Maine-based Cianbro, Hallett helped lead a team that built a 5,338-ton concrete precast structure that would serve as the entrance of a new navigation lock basin at Portsmouth Naval Shipyard. The massive, one-of-a-kind structure, which had been cast entirely on a floating barge for more than a year at Cianbro’s Ricker’s Wharf facility in Portland, Maine, set off that day down the Fore River and into Casco Bay, en route to the Navy shipyard. The high-profile project not only had the attention of the client, NAVFAC, it also had attracted some curious onlookers.
“There was a quite a gathering of people following the tug and the barge, all gathered up to watch it come around the corner,” he recalls. “There was a lot of nervousness as it was coming up the river.” Precisely timed with the tidal charts, the barge bore the structure into place during high tide June 21, where it was secured to strand jacks. As the tide went out, the barge dropped below the suspended structure and the strand jacks held it as the barge left. The real moment of truth came as the structure was lowered into the basin, where it had to set down precisely on four drilled shafts underwater. With a tolerance of only 1⁄8-in. , crews were able to set the structure in its final resting spot. “It was an extremely detailed plan,” he recalls. “Everybody knew what they needed to do in all regards—from the tugboat operators to the craft guys out on site—and it went off like clockwork.”