Col. Karl Jansen, St. Paul District commander, recently recognized engineering and construction employees Erin Krug, Loren Soma, Wade Carr and Christina Vasseur with “on-the-spot” awards for their work replacing miter gate anchorages at Lock and Dam 2 near Hastings, Minnesota.
In 2018, after nearly 90 years of service, the Corps decided to replace the lock chamber’s four miter gates with newer, heavier gates to ensure the continued safety and operability of the lock for commercial navigation. The miter gates, which act like doors at each end of the lock, meet at an angle to block the river and allow the lock operator to raise and lower water levels within the chamber so vessels can pass.
Shortly before installation, Corps structural engineers discovered that the existing 90-year-old miter gate anchorages, which act as door hinges for the miter gates, were not strong enough to hold the newer, heavier miter gates. If the anchorages failed, the miter gates would collapse into the lock chamber, preventing navigation on the Upper Mississippi River.
The Corps delayed miter gate installation at Lock 2 until St. Paul District engineers could design new miter gate anchorages. The Corps awarded the contract for the new Lock 2 anchorages in 2019, and a contractor fabricated steel frames for the anchorages in summer 2020. Installation of the anchorages began in fall 2020 during the lock’s winter closure and was scheduled to be completed in mid-March 2021 for the start of the spring navigation season.
However, project construction was delayed when the contractor discovered that two of the four miter gates’ anchor bars, which connect the miter gates to their anchorages, would not connect correctly due to a gudgeon hood alignment issue. Erin Krug, strructural engineer, explained, if a miter gate is like a standard house door, then the gudgeon hood is like the hinge plate attached to the door. The anchorages are like the hinge plate attached to the wall and the gudgeon pin is the pin that connects the two hinge plates together so the door swings about that point.
The misalignment of the gudgeon hood plates prevented the contractor from installing the gudgeon pin through the holes in the plates. Without the gudgeon pin securing the gudgeon hood plates, the miter gates’ two anchorages could not connect, preventing the miter gates from opening and closing.
The St. Paul District’s engineering team researched, evaluated and briefed potential solutions for the gudgeon hood issue until they found a workable solution that the contractor could accomplish. The contractor completed work in February 2021 during the coldest week of the winter, line boring new gudgeon pin holes and welding a new plate onto the bottom gudgeon hood plate.
“There were many challenges throughout the short project. Through collaboration with the contractor and Corps staff, we were able to work through the issues to develop a solution,” said Christina Vasseur, contracting officer’s representative for the project.
The lock successfully reopened to navigation on March 18, one day prior to the arrival of the first tow of the season.
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| Date Taken: | 09.15.2021 |
| Date Posted: | 09.15.2021 10:56 |
| Story ID: | 405295 |
| Location: | HASTINGS, MN, US |
| Web Views: | 97 |
| Downloads: | 0 |
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