The first of the three milestone phases of the new lock construction at Sault Ste. Marie, Michigan is complete.
Channel dredging on the west side — the Lake Superior side — of the proposed US$1-billion lock has wrapped up, according to a July 22 news release from the U.S. Army Corps of Engineers, the operator of the locks.
The dredging contractor, Trade West, began work on the so-called North Channel two years ago. In the process, approximately 300,000 cubic yards of overburden and bedrock was removed using excavator buckets, stone grinders and a hydraulic ripper, a submersible attachment, to break up the rock.
The company broke through bedrock, mostly sandstone, up to six feet thick and over a three-quarter-mile stretch in the channel to dig down to a 30-foot depth, the draft required to accommodate the largest freighters on the Great Lakes. This work was all done from barges.
The excavated material is piled up on a west-end pier which will act as a windbreak for passing ships.
The largest rock weighed 55 tons, as heavy as an adult humpback whale, according to the Corps.
“We are waiting on final survey results and anticipate they will show the deepened areas as complete, really only have some punch-list type items, groundskeeping and site cleanup remaining,” said Rachel Miller, the project’s supervisory civil engineer.
The new lock will be constructed on the site of the existing Davis and Sabin Locks, two decommissioned and obsolete locks built around the time of the First World War. Those two locks will be demolished. The new lock will have the same dimensions — 1200 feet by 110 feet — as the existing Poe Lock, which handles the largest ships on the lakes.
The Poe accommodates almost 90 per cent of all the commercial vessel traffic between Lakes Superior and Huron. The construction of a second similar sized lock was deemed by the U.S. government as a vital piece of national security infrastructure, should the Poe unexpectedly be closed.
But two major phases of lock construction still remain.
The second phase involves fixing and upgrading the existing west side approach walls, which allow ships to tie up and wait their turn to pass through the next lock. Work by Kokosing-Alberici LLC, a Ohio and Missouri construction consortium, started last year.
Activity shut down for the winter and resumed in mid-April. The Corps said this work should be completed by the summer of 2024.
Earlier this month, the Phase 3 contract to dig out and build the new lock chamber and rehabilitation the downstream (Lake Huron side) approach walls was awarded to Kokosing Alberici Traylor, LLC, a joint venture construction firm from Ohio.
The contractor is cleared to start construction this summer. This phase is expected to take seven years to complete.
“We’ll build coffer cells to block off and dewater the construction site,” said Miller. “Power needs to be rerouted through the facility, the Sabin Lock chamber demolished, a new 1,200 foot by 110-foot chamber constructed, the Davis Lock filled in, a new pump well installed and the downstream approach walls rehabilitated.”
Construction of the new lock was authorized in 1986 but actual construction didn’t start until 2020.