A power house of power

Jul 22 - McClatchy-Tribune Regional News - Collin Calderwood The Hawk Eye, Burlington, Iowa

July 22--KEOKUK -- A claim like "the largest power house in the world" wouldn't be associated with Iowa today, but 100 years ago, Keokuk made the claim.

In an effort to produce hydroelectric power and, at the same time, make the Des Moines Rapids more navigable, Hugh L. Cooper undertook the challenge of building the Keokuk hydroelectric dam, the first and still only such dam on the Mississippi River.

Cooper fought with investors, many of whom believed inexpensive coal in the Mississippi Valley made the project a waste of money.

According to John Hallwas, author of "Keokuk and the Great Dam," Cooper was turned down 58 times and spent most of his money in the process of trying to be named the engineer on the project.

Cooper finally found funding for the project, allowing construction to begin immediately. The dam ended up costing investors just over $25 million, about $578 million in today's dollars.

A hefty portion went to Cooper's engineering fee, a staggering $12,000 a month, the equivalent of about $280,000 a month today. The average civil engineer in 2010, according to government statistics, earned about $78,000 a year -- and Cooper wasn't a licensed engineer.

Excavation work began on the Illinois side, 1920, followed by construction on the Iowa side in December.

Throughout the construction of the dam, many important people came to see its progress, from engineers and stockholders to government leaders.

To accommodate the visitors, the Hugh L. Cooper Co. rented a large home on the bluff, operating it as a hotel and calling it the "Riverview Club." Accommodations were free for anyone important enough to get invited. People reacted with awe in seeing the engineering marvel.

"The visitors were amazed and delighted with what they saw," The Hawk Eye reported July 13, 1912. "They absorbed information and filled up on wonders," a reaction that isn't re-created by astronauts traveling to and from the international space station today.

As construction on the dam moved along, it grew tougher with each completed section. Eventually, on July 22, 1912, both sides of the dam were connected by a single timber.

Imagine sliding a thumb over the end of a running garden hose. As more of the thumb covers the opening, the water has to squeeze through a smaller opening, making it nearly impossible to fully plug the stream with just your thumb.

That's the same basic principle the dam workers contended with as the dam grew closer to completion.

"They never closed off the entire river at once," said Ed Kiedaisch, an engineer and member of the Lee County Iowa Historical Society board. "All they were doing was building the archways, not the spillways (the doors in the arches), so they weren't really blocking the flow of the river."

Eventually, once the arches were built, the spillways needed to be poured.

"After the arches were built, they fit beams across both faces of an arch, pumped out the water, and then poured only five feet of concrete before moving on down the line, at the end they would go back to the beginning and pour five more feet," Kiedaisch said.

The dam wasn't completed until almost a year later on May 31, 2013, when the last bucket of concrete was placed in the dam at a ceremony celebrating the structure's completion.

On June 3, 1913, electric current traveled from the powerhouse to Keokuk, signifying the project was days from completion.

A week later the first steamers used the lock, as many people spectated from the lock's walls and nearby bluffs.

Now, 100 years later, there have been some slight changes.

"They started facing the concrete 15 years ago, adding 12 inches to 18 inches of concrete on the downriver side of the dam," Kiedaisch said.

Currently, the original turbines are being replaced with stainless steel ones.

"They are going to stainless steel, which is much more resistant to cavitation," Kiedaisch said.

Kiedaisch explained cavitation happens with all water turbines, even boat props. The spinning creates low pressure and bubbles form in the vacuum, which pulls off pieces of metal. To fix these small holes left by the bubbles, the wheels have to be pulled out and the pockets welded shut. Kiedaisch estimated once the new turbines are in place, they will reduce the already low maintenance another 80 to 90 percent and increase efficiency by 3 percent.

"Three percent doesn't sound like much, but over the course of the next hundred years, it will be quite a lot," Kiedaisch said.

He also explained over the last century, the dam always has made roughly the same amount of power.

"It is pretty much the same now as it was then, the process of replacing the turbines will help, but it can only produce as much power as water is flowing," Kiedaisch said, "nature really determines how much power it produces."

Most people think of power lines running from a power plant to their home when thinking about how a power plant works, but that is just not the case, and in this instance, the Keokuk dam never produced power for homes.

"It was originally built to provide power to St. Louis for street lights and street cars," Kiedaisch said, "Now Ameren doesn't even have power distribution in Iowa, it all goes south. I'm not sure what they are doing now, but electricity goes into the grid and goes a million places."

Kiedaisch compares the electrical grid to a lake.

"Unless it's a private power plant, no power plant powers just one thing," he said, "It's like a lake with anyone from around the lake who needs water coming to fill up."

Even though the Mississippi is one of the world's largest rivers, this is the only commercial hydroelectric plant on the river.

"Technically, someone may have a small operation producing a couple kilowatts, like a backyard wind turbine, but as far as commercial operations, this is the only one,"

He said the reason is the Mississippi is a pretty flat river, and dams need some drop. The largest drop on the Mississippi River is at Keokuk, making it the only suitable location for a hydroelectric plant, though new technology has permitted other communities, including Burlington, to investigate hydro options.

While the Keokuk dam was built 100 years ago, it has by no means out lived its usefulness.

"Back in the 1980s, Union Electric's Vice President of Production said there was no other asset they were keeping in their production plans for more than 50 years, but they were keeping the dam in their plans for the next 200 years, and there was no reason that it wouldn't be around in 300 to 400 years," Kiedaisch said.