When a sinkhole appeared in May 2025 above a key culvert near the US Highway 83, 2, and 52 interchange, the city of Minot faced an immediate threat to safety and traffic flow. Fortunately, the Minot Structure Replacement Project, led by Ulteig, was already underway to replace Structure #83-198.473, a structural steel plate pipe culvert designated as ‘poor’ since 2022.
Mary Boechler, Engineer and Project Manager for the project, explained, “The culvert had been in poor condition for years, and repeated maintenance efforts were no longer sufficient. The sinkhole really demonstrated this structure’s effect on the community. If the replacement hadn’t already been planned, the safety risks could have been much more significant.”
Turning Engineering Complexity into Clear Solutions
Replacing a culvert buried 30 feet below a major interchange required careful planning and coordination. “I was deeply involved in the development of the plans, including structures, work zone traffic control, and erosion control,” Boechler said. Ulteig conducted environmental and topographic surveys, prepared a Documented Categorical Exclusion, and coordinated early and often with five utility companies to accelerate permitting. Public input revealed a preference for concrete over steel, which influenced the final structure selection.
Boechler emphasized, “At the public input meeting, it was apparent that there was a preference for the proposed structure to be concrete instead of steel. It also made clear how important this channel is to downstream communities, which factored into the hydraulic analysis and structure sizing.”
Designing for Durability and Hydraulic Performance
The project replaced the aging structural steel culvert with a single-barrel precast reinforced concrete box culvert. “Although concrete is generally more expensive for this size of structure, it is expected to last longer in the corrosive soils we experienced,” Boechler noted. Hydraulic analysis ensured a ‘no rise’ condition in the FEMA Zone “A” floodplain, while flared wingwalls and a riprap basin were incorporated to prevent scour and protect the surrounding environment.
Managing Traffic Through One of Minot’s Busiest Intersections
Maintaining traffic flow was a major challenge. “One of the biggest challenges were the large trucks expected to pass through the work zone,” Boechler said. “We analyzed truck movements using AutoTurn software and made extra wide lanes where those trucks would be flowing. The Continuous Green-T intersection layout allowed one lane of northbound traffic to flow freely while only two directions were controlled by temporary signals, helping protect drivers and construction crews.”
Temporary concrete barriers and strategic detours kept commuters and workers safe. “Temporary concrete barriers are the most essential tool for keeping workers and drivers safely separated,” Boechler added.
Responding to the Sinkhole: Quick Action, Minimal Disruption
When the sinkhole formed, Ulteig immediately coordinated with NDDOT. “We had a meeting right away with NDDOT to figure out what needed to change and got our designers on the task immediately,” Boechler explained. Change orders were implemented, detours established, and construction accelerated. Close communication with the DOT ensured all needs were met quickly, restoring safety and connectivity.
Delivering Community Value
This project demonstrates how infrastructure projects can extend beyond engineering. “I hope people understand how important a pipe most people never knew was there actually is to their daily commute or trip to Menards,” Boechler said. “Hopefully they take a little more time to look around and appreciate the infrastructure that makes their lives easier every day.”
By completing the project on schedule and on budget, Ulteig not only preserved public resources but also strengthened community trust. “I am very grateful for my team throughout the project,” Boechler reflected. “When faced with an emergency closure, we all came together to meet the client and community needs.”
Infrastructure That Supports Daily Life
Although most commuters rarely notice the culvert beneath them, its replacement ensures safer travel, uninterrupted connectivity, and long-term resilience. The Minot Structure Replacement Project illustrates how integrated planning, public engagement, and technical expertise can turn complex civil engineering challenges into safe, sustainable, and lasting solutions for communities.
We Listen. We Solve.
Ulteig partners with transportation agencies, municipalities, and infrastructure owners to deliver solutions that enhance safety, reliability, and long-term community resilience. From complex structure replacements to innovative traffic management and accelerated project delivery, our teams bring integrated expertise across civil, structural, environmental, and field services.
If your organization is planning a similar project or exploring opportunities to strengthen critical infrastructure, connect with Ulteig to learn how our collaborative approach can support your goals and keep your communities moving forward.
