Courtesy Photo | The Lock and Dam 7 Outdraft Project Delivery Team during a ship simulation exercise at...... read more read more
Changing Upper Mississippi River conditions spurred collaboration between the U.S. Army Corps of Engineers, St. Paul District; the U.S. Army Engineer Research and Development Center; and navigation industry stakeholders to improve navigation at Lock and Dam 7, near La Crescent, Minnesota.
The district began addressing area challenges in 2017 with a hydraulic study, or study about the flow of water, aimed at understanding the increasing outdraft. According to industry standards, an outdraft refers to a river current pulling toward a downstream dam. This study revealed a significant shift in river flow over the past 30 years, with nearly 20% of the flow moving from the old navigation channel on the east side of Dresbach Island to the current channel along the Minnesota bank. This change led to higher water velocities above the lock, intensifying the outdraft issue.
In response, a rock weir was built in 2018 by the St. Paul District maintenance and repair crew, to slow the current, and it was extended by 260 feet in 2020 following input from the navigation industry. Despite offering some initial benefits, the weir did not completely solve the outdraft problem.
In February 2023, navigation industry representatives reported a potential “lifesafety” issue with the increasing outdraft at Lock and Dam 7 at the district’s annual Mississippi Managers Meeting.
“The outdraft makes predictable and consistent maneuverability challenging, which could potentially cause a fatality. The increased risk to the navigation mission made this a top priority for the district,” said Billy Thomson, project manager.
“The upper approach to Lock and Dam 7 is uniquely shallow and narrow, which makes some traditional solutions used on other waterways not feasible.”
The project delivery team was formed shortly after the February 2023 meeting to address the ongoing challenges. “This is a critical project that affects our navigation mission. Vessels are trafficking the lock daily, while lock staff work tirelessly to meet pressing deadlines,” Thomson said.
The team identified both short- and long term actions and decided to take a phased approach. The culmination of Phase 1 was an ERDC ship simulation to identify a feasible design alternative that will improve navigation conditions within the upper approach. Key to this significant effort was 12 months of preparation and data collection. A ship simulation is a system of computers, screens, hardware and software that simulates vessels, ports, weather conditions, and traffic patterns for training, assessment and research, Thomson said.
The team’s preparation also included a June 2023 design charrette with Corps of Engineers regional experts, industry partners and ERDC. A design charrette is a collaborative meeting where a group of people from different backgrounds work together to develop a plan. This event provided valuable input from experienced pilots to explore potential solutions, including the development of a custom vessel model for the simulation to best represent what is operated at Lock and Dam 7, Thomson said.
Preparation included hydraulic modeling, vessel model development and gathering site imagery to replicate the surrounding of Lock and Dam 7 to build the most realistic visuals for the approach in the simulator, Thomson said. The simulation tested different design alternatives to improve the outdraft, which mostly included different configurations of rock weirs. The actual execution at ERDC was eight days using nine different industry pilots.
“This project showcases the true power of ERDC, as it brought together numerous subject matter experts to solve a problem that directly impacts commercial navigation on a daily basis. Having all the decision makers in the same room allows for changes to the design alternatives to be made quickly and evaluated immediately,” said Jacob Hodges, ERDC research civil engineer.
“The success of this project so far is based on the teamwork that we have had with navigation industry and ERDC. Throughout the process, we have also been getting input from captains navigating their vessels through the lock and using that feedback as input for the simulation to get the best result,” Thomson said.
The team ultimately decided on a solution that is called the “Dog-Leg” rock weir design. Phase 2, which began in May 2024, focuses on near-term implementation to effectively reduce the outdraft, which includes preconstruction engineering and design. The project is waiting on funding for construction in 2025-2026.
“It’s a very challenging project, and with the river continuously changing over time, it makes the solution complicated,” Thomson said.
“The Lock and Dam 7 project was a unique opportunity to collaborate with St. Paul on implementing new potentially lifesaving designs to improve navigation efforts on the upper Mississippi,” Hodges said.
The St. Paul District maintains a 9-foot-deep navigation channel on the Upper Mississippi River and operates 12 locks and dams to support navigation from Minneapolis to Guttenberg, Iowa. Keeping this system open is vital to the nation’s economy to reduce the stress on our roads and bridges. A 15-barge tow can move as much bulk commodities as 1,050 semis or more than 200 rail cars.
| Date Taken: | 08.28.2024 |
| Date Posted: | 08.28.2024 13:46 |
| Story ID: | 479665 |
| Location: | ST. PAUL, MINNESOTA, US |
| Web Views: | 101 |
| Downloads: | 0 |
This work, Collaboration and partnership advances solution to potential life safety, by Melanie Peterson, identified by DVIDS, must comply with the restrictions shown on https://www.dvidshub.net/about/copyright.
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