In 2018, construction crews plan on working on the section of the dam over the 12 spill gates as well as the eastern section, applying a six-inch overlay on both the east and west sections of the dam.

With several million pounds of old concrete hydro-blasted off the western section of Ameren Missouri’s Bagnell Dam, phase two of a major structural update project for the hydroelectric facility is well underway.

The $52-million project announced last January and started this spring is expected to take approximately 18 months as construction crews drill 100-feet into the bedrock through the dam to install sixty-eight 19-inch post-tension, low-corrosive steel anchors while pouring 66 million new pounds of concrete to shore up the foundational structure of the gravity dam built in 1930. The new anchors can be unsealed and retightened over the years.

“We’re well along with drilling. We’ve got three anchors completed and there’s probably another about a dozen that are some in stage of drilling for new anchors,” Warren Witt, director of hydro-operations at Bagnell Dam, said on Wednesday morning. “The whole back side is light concrete which means we’ve blasted off the old west retaining section — west of the spill gates — and began pouring concrete into the piers.”

The drilling process involves creating several different sized holes, from three to 15 inches in diameter at different depths of the dam and bedrock before the anchor is installed and tightened. The hydro-blasting process removes up to nine inches of surface concrete that will then be replaced. The series of piers along the top of the face of the dam under the roadway are being filled with concrete to give the dam additional strength and weight.

MC Constructions crew will start on the eastern section of the dam next year as specially designed man-lifts and construction platforms need to be built to support the weight of workers and heavy machinery.

Special troughs and settling ponds, along with a water filtering system, have been constructed to safely filter the concrete-filled water and remove the final product to the Lake Ozark Sewage Treatment Plant as the Missouri Department of Natural Resources monitors the project.

The work is not having any effect on the energy-generating capacity of the Osage Energy Center which provides power to 42,000 homes. Ameren Missouri’s service area covers 64 counties and more than 500 communities including the greater St. Louis area. The utility company estimates a total of 1.2 million electric and 130,000 natural gas customers throughout Missouri.

The last major structural update at Bagnell Dam was completed in the late 1980s when 277 post-tension anchors were installed to hold the dam in the bedrock. The anchors were the best technology at the time and have performed well since they were installed, and the dam continues to remain structurally sound, Witt said this spring.

When the dam was built in 1929-30, it was believed that a maximum flood level would never top the dam. But after further hydrological study, it was determined the lake could reach as high as 670 feet above sea level — well above full pool of 660.

The additional pressure behind the dam could result in catastrophic issues. The analysis in the 1980s indicated it could overflow the dam, but current analysis no longer shows that, according to Witt. The aging dam and the potential for a major flood led Ameren Missouri officials to move forward with the construction project.

In 2018, construction crews plan on working on the section of the dam over the 12 spill gates as well as the eastern section, applying a six-inch overlay on both the east and west sections of the dam.

Ameren estimates the economic impact of the construction project to provide more than 800 direct and indirect jobs and more than $200 million in total economic activity in the Lake of the Ozarks region.