Thirty feet of gravel, concrete, steel — and, oh yeah, about $2.2 million — can buy a city a lot of peace of mind when it comes to a 124-year-old dam.
When city-hired construction crews began working in the chilly waters of the Kansas River in November, peace of mind and the Bowersock Dam did not go hand-in-hand.
An engineering firm — also hired by the city — had tied the equivalent of a big red flag to the old structure that is just east of the Kansas River bridges in downtown Lawrence. Black & Veatch engineers had reported that they were unable to “determine if the dam is in immediate danger of failing, as significant structural concerns exist.”
That created concerns from the dam’s chief regulator, the Federal Energy Regulatory Commission, and ultimately set the city down a multimillion-dollar path to repair a historic piece of infrastructure that once was at the center of Lawrence’s industrial world.
Now as crews begin the last one to two weeks of work on the project, city engineers are ready to shred the red flag.
“The repairs that we have done guarantee the stability of the dam for another 100 years,” said Chuck Soules, the city’s director of public works.
But it wasn’t easy.
Pile it up
The job was far from the typical city public works project. Instead of looking at the skies overhead, workers worried about the weather in Manhattan and other points west of Lawrence. If it rained heavily in Manhattan, workers standing in the middle of the Kaw could see river levels rise here.
A major part of the project has been building a road into the river for backhoes and other pieces of equipment to work on the dam. There were fears that high river levels would wash that road away — and add hundreds of thousands of dollars to the project.
That didn’t happen. But floating ice was a problem, and the bitter cold added some costs to the project by requiring special equipment that allows for concrete to be poured in poor weather.
Although the work was hard, the concept behind it was not. Barges drilled a series of holes about 30 feet upstream of the dam. Then steel pilings were driven about 20 feet into the river bed. Crews dumped gravel into the 30-foot void between the pilings and the dam, and then covered the whole thing with concrete.
“Pretty simple, really,” Soules said.
But needed. City officials never were entirely convinced of Black & Veatch’s ominous report on the dam. Soules said he’s still skeptical that the massive structure was in danger of floating away.
“But water does amazing things,” Soules said. “It is hard to say for sure that it wouldn’t have happened.”
It would have been easier to say if large timbers weren’t sticking out the back side of the dam.
The old dam, built in 1886, largely consists of timbers and stones that are encased in concrete. When engineers recently took a look at the dam — the last time anyone had seen its face was more than 30 years ago when the bridges were built — they saw that large chunks of concrete had fallen off. That had allowed rushing water to push timbers through the backside of the dam.
It doesn’t even take an engineer to know that wood and water do not mix.
“The concern was that as the timbers, the superstructure of the dam, started getting wet that there would be rotting, and if that failed, there could be a collapse,” Soules said.
The new structure is designed to stop water flowing through the dam. Crews now are repairing the holes on the back side of the dam.
“We definitely feel the dam is stabilized now,” Soules said.
Water plant help
The city is paying nearly all of the estimated $2.2 million to repair the dam, despite not technically owning the dam. The adjacent Bowersock Mills & Power Co. owns the dam but did not have the financial resources to undertake the repairs.
The city, however, is not doing the repairs out of charity. Since the 1970s, the city has legally been responsible for the maintenance of the dam. A large reason why is the city’s Kaw Water Treatment Plant, which is just upstream of the dam. The dam provides a pool of water that allows the plant to operate efficiently.
The Bowersock power plant, though, is expected to benefit from the improvements. Stephen Hill, president of the Bowersock Mills & Power Co., said he hopes the repairs will allow regulators to approve the raising of the dam’s flashboards. Those boards — which extend the height of the dam — allow Bowersock to increase its electricity production by about 30 percent.
The repairs, though, may have much larger long-term benefits for the privately owned company. Hill said the repairs keep alive hopes that the company can build a second hydroelectric plant, this one on the north banks of the river.
Hill said the company is in negotiations with potential purchasers for the power the plant would produce. The company also has started the federal permit process for a new plant. Hill hopes pieces will fall into place for construction of the plant to begin by Dec. 31.