The historic Bowersock Dam is critical to the community of Lawrence, Kansas. The 140-year-old structure helps safeguard the area’s water supply, property, and life.

Over time, the powerful churn of the Kansas River eroded the bedrock, which threatened the stability and reliability of a portion of the dam. The City of Lawrence and Bowersock Mills and Power Company, who jointly operate and maintain the dam, called on Olsson to assist with repair designs.

Olsson project manager Grant Luckenbill said there were holes in the dam’s exposed bedrock. The scour holes, if left unresolved, could continue to enlarge and undermine the integrity of the dam. The exposed downstream foundation needed a long-lasting, yet efficient solution that could be built in a challenging environment.

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‍The Solution

Before designing a plan for rehabilitation, we needed a riverboat.  Olsson’s surveyors used boat-mounted sonar technology to analyze the contours of the bedrock to understand the extent of the damage.  After we identified the dimensions of the riverbed and investigated the properties of the shale bedrock, it was time for design.

The solution required 1,000 cubic yards of concrete, 50 tons of rebar, and a whole lot of collaboration.

We cleaned, prepared, and filled the scour holes with fiber-reinforced concrete and rebar anchors.  Next, we installed a new concrete wall to protect the dam’s exposed bedrock face and anchored the system together with heavy rock nails.  An inclined concrete toe-wall and concrete apron were also added to mitigate undercutting water, erosion, and scour holes in the future.

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Building in a Challenging Environment

Grant said the design solution was straight-forward. Building in a riverbed – 25 feet below a river with fluctuating water levels - was not.

“Communication and safety were key parts of this project, because it was a challenging environment to work in,” Grant said. “It was a group effort to make sure the contractor could do the work safely.”

Throughout construction Grant had weekly coordination calls with project partners, including the City of Lawrence, Bowersock Mills and Power Company, Olsson engineers and scientists, contractor Dondlinger Construction, and the U.S. Army Corp of Engineers (USACE).

Together, the team navigated the work and the weather.

Each week, the group coordinated with USACE staff members, who controlled water discharges from multiple upstream dams, to anticipate water levels at the site and adjust work accordingly.

The City of Lawrence worked closely with project partners to maintain the dam’s headwaters and keep the work area safe. More than 12,000 cubic yards of rock and clay were installed upstream and downstream of the dam to help trap water. They required continuous maintenance and dewatering to maintain dry and safe conditions during construction.

“The quick turnaround and timeline were other factors front of mind,” Grant said. “The five-month project timeline had a hard stop in February to avoid spring rains and snow melt that could create unsafe conditions and significant project delays.”

The project team completed the project on time and under budget. The rehabilitated dam has been up and running since 2022.

During the project, Dondlinger Construction carefully relocated native fish downstream that were caught within the dewatering area. Post-construction, the team created a safe and environmentally conscious fish habitat at the dam's base by anchoring precast concrete pipe to the riverbed. Today, our structural team is reviewing designs for the installation of protective structures to help manage Asian carp, an invasive fish species.

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An Award-Winning Project

The Bowersock Dam project was recently recognized for engineering excellence:

• 2024 ACEC National Recognition Award

• 2024 ACEC Kansas Recognition Award

• 2023 APWA Kansas Structural Project of the Year

We have enjoyed partnering with the City of Lawrence and the Bowersock Mills and Power Company for many years. For the Bowersock Dam, we’ve provided engineering services for more than 15 years and designed the north power plant in 2008.