Ameren held an official groundbreaking ceremony Monday for its Big Hollow Energy Center project in southern Jefferson County. About 50 people, including Ameren officials and employees, local government and school officials and representatives from contractor groups, gathered at the site to mark the official beginning of construction on the $900 million electricity-generating plant/power storage facility on the site of the former Rush Island coal-fired plant.
The project was announced almost exactly a year ago, and the Missouri Public Service Commission granted the application earlier this year. The new facility will have two distinct parts: an 800-megawatt natural-gas generation facility and a large-scale, lithium-ion battery installation for power storage.
“This will be Missouri’s first integrated production and storage facility,” said Ajay Arora, vice president and chief growth and development officer for Ameren. “Together they will strengthen the grid.”
Work has been ongoing at the site since the late 2024 closure of the Rush Island operation. There were shutdown procedures, including the removal of the remaining coal supply; preliminary roadwork; and removal of some of the old plant infrastructure. Monday’s ceremony marks the official commencement of work to develop the Big Hollow project.
“We were waiting for the permits to come through,” Arora said. “And during that time, we were moving a lot of stuff around, doing transitional work to get ready for the new plant. Now we begin the actual construction phase.”
A big advantage to putting a new plant in where another one once stood is that much of the infrastructure will remain. The “switchyard” where generated power is fed to transmission lines for distribution to the grid will stay where it is, and four natural gas-fired turbines will be installed to serve it.
A 9.5-mile, 20-inch natural gas pipeline is being constructed under the Mississippi River to supply those turbines with fuel from a main gas pipeline in Monroe County, Ill.
Both company officials and local government representatives emphasized the importance of the ongoing connection between the plant and the community, where it has been a large-scale employer and an important source of tax revenue since it opened in 1976.
“Jefferson County has played a big part in supplying electricity needs to the area,” Arora said. “Big Hollow continues that legacy.”
During the ceremony, he acknowledged both Jefferson County Executive Dennis Gannon and Jefferson R-7 School District Superintendent David Haug for “listening, working through challenges and showing up when needed.”
Rachelle Lengermann, president of Plocher Construction, said she has a long history of working at the site.
“One of my first industrial project manager jobs was a treatment plant we did here,” she said. “We have put a lot of time and care into this site, and we were sad to hear it would be decommissioned. Now we’re excited to be part of it coming back.”
Plocher, in collaboration with Ohio-based Kokosing Industrial, will be responsible for constructing the generating facility part of the project, while McCarthy Building Companies will take care of building the battery storage facility.
Both of those, as well as the pipeline project, are expected to be built at the same time, and Ameren officials estimate the plant will go online in mid-2028.
David Courtway, Jefferson County Director of Administration, said the project will be a boon for the area.
“It took some big decisions by a lot of people, a lot of entities, to make this happen,” he said. “But it’s going to be great for the community.”
Gannon agreed but put it more succinctly.
“The future is happening today.”