Photo By Kelcy Schroder | Kirk Atwater, Mississippi River Project Maintenance Project Engineer, assists the...... read more read more
Miter gate repairs were recently needed at Lock and Dam 14 on the Mississippi River in Pleasant Valley, Iowa. Ideally, repairs are done during the winter months to minimize impacts to the commercial navigation industry but due to one miter gate being extensively damaged during a recent incident at the lock, the repairs to the miter gate could no longer wait.
Miter gates are critical to the operation of a lock. At each end of the chamber, a set of miter gates is needed to allow vessels to pass. Over the last several years, miter gates at Rock Island District locks and dams have been getting upgraded to better handle situations such as these, when damages arise. The new gates are more maintenance friendly, with bolted connections rather than being fully welded together. Bolted connections allow the maintenance department to quickly remove and replace damaged components rather than needing to use torches to disassemble the gate. This approach minimizes downtime since replacement components can be fabricated and painted before the gate is lifted.
The new miter gates were also designed to be repaired in a flat, horizontal position rather than having the gate standing upright. Rolling feet are needed to minimize the risk of inadvertently damaging the gate while it is laid on its side. Depending on the lock, these gates can weigh anywhere from 150,000 to 400,000 pounds, so any unexpected movement or shifting of the gate could cause additional damage or a threat to those working on the structure. Given the custom nature of the Corps’ hydraulic steel structures, damaged components are not readily available, or quick to fabricate, so it is critical to prevent damaging them in the first place.
The damaged miter gate at Lock and Dam 14 was the first time one of the newer, maintenance friendly gates needed repair. Mississippi River Project Maintenance Project Engineer, Kirk Atwater, took the opportunity to use his ingenuity to design and engineer rolling feet for the miter gate so the repairs could be done in the ideal, horizontal position.
“There were many components that went into the process of designing these rolling feet.” Said Atwater, “Since the feet needed to be compatible with all the bolt-together gates on the Mississippi, I needed to start with the as-built drawings of all the gates to determine the overall weight range to build the feet for the heaviest gate rather than just the gate at Lock and Dam 14 so they can be used again. I had to take into consideration the gate’s center of gravity with respect to both the crane and the bearing point on the rolling feet for all positions as the gate rotates. If that is incorrect, the crane operator would be fighting gravity throughout the laydown process and there would be a greater risk of the gate wanting to flop over rather than going smoothly and causing a shock load crane boom.”
One of the top priorities throughout the design process was to create feet that could be installed with minimal effort. Ideally, they didn’t want to have to drill any extra holes or weld anything onto the gate to use the rolling feet since that would require additional work before the repair could get underway. Atwater’s ultimate solution was removing six existing skin plate bolts on the downstream size of the gate, once the bolts were removed, the feet could be installed using those existing holes, with longer bolts. On the upstream side of the gate, the rolling feet connected to a large gusset plate with clamps to hold the feet in place, preventing it from dropping when the crane is supporting it with the rolling feet still attached.
Laying the miter gate down using the rolling feet anytime repairs are needed is much safer for employees and quicker because it does not require scaffolding to be constructed around the upright gate. The plan is to use the rolling feet anytime the Corps has significant structural repairs needed to miter gates in the future.
After the repair of the miter gate, Atwater concluded, “The rolling feet worked as intended! Yes, we will be making some minor changes for their next use. They will be a critical component for all future repairs to miter gates on the Mississippi River moving forward.”
| Date Taken: | 08.04.2022 |
| Date Posted: | 08.11.2022 11:45 |
| Story ID: | 426799 |
| Location: | ROCK ISLAND ARSENAL, ILLINOIS, US |
| Web Views: | 123 |
| Downloads: | 0 |
This work, Ingenuity Leads to Successful Repair, by Kelcy Schroder, identified by DVIDS, must comply with the restrictions shown on https://www.dvidshub.net/about/copyright.
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