The city’s plan to repair the aging Bowersock Dam is taking shape.

But city commissioners at their meeting tonight will need to give the go-ahead to start work as early as August on the upstream portion of the dam just north of downtown Lawrence.

“What we’re trying to do is a more permanent, longer-term solution,” said Chuck Soules, the city’s public works director.

City and state officials have said the two Kansas River bridges could be seriously compromised if the dam — built in the 1870s — were to fail. They have voiced concerns about rotting of the upstream portion of the dam, which is made of timber.

If the dam were to fail, it would be difficult for the nearby Kaw Water Treatment Plant to operate.

In March, the original plan for dam repairs included going underwater and placing grout bags against the dam to try to plug the flow of water through the structure, but Soules said it was risky to rely on that method to handle all of the leaks.

Instead, the city is proposing a $2 million to $2.5 million project to create a temporary cofferdam with rocks west of the dam. That would lower the water level and allow workers to add steel sheet piles and concrete to fill holes on the dam.

A major portion of the plan calls for waiving the bidding procedure to allow Hamm Construction and United Construction companies to do the work, mostly because the companies are contractors for the Kansas Turnpike Authority’s bridge construction just upstream.

“They’re mobilized, and they’re ready to go. Those types of issues can save a little bit on a project, and they know what they’re doing,” Soules said.

The city has set aside about $1 million for dam repairs, and city officials have said they would likely seek additional funding from state, federal and private sources.

One city commissioner said the project’s benefits include boosting hydroelectric power generation at the adjacent Bowersock Mills and Power Co. The company technically owns the dam, but the city is responsible for maintenance cost because of a 1977 deal when the city purchased land for the current city hall.

“It’s a relationship and a responsibility that we created many years back, and something that I think yields or has potential to yield a great amount of opportunity for the city,” Commissioner Mike Dever said.

The meeting begins at 6:35 p.m. today at City Hall, 6 E. Sixth St.

Commissioners will also receive an update on the Lawrence Community Shelter’s situation. Shelter leaders are still looking for a larger and more permanent site away from downtown, but they are seeking ways to boost their capacity at the current shelter, 214 W. 10th St., after The Salvation Army closed its overnight shelter in June.