Work is underway on a nearly $1 million Ameren Missouri substation upgrade that will strengthen development potential along Interstate 70 while providing power for a new CertainTeed Corp. manufacturing complex in Jonesburg.Ameren Missouri is installing a new, larger transformer and replacing feeder breakers at the Jonesburg Substation along West Booneslick Road, just west of Jonesburg.The $969,000 project will provide more dependable power to the Jonesburg area’s approximately 810 customers while adding the capacity to serve CertainTeed as well as potential future growth along nearby I-70.“We’re basically doubling the capabilities of the transformer,” said Gene Unverfehrt, director of Ameren Missouri’s Northeast Missouri Division. “It’s an example of our commitment to updating the electric grid to provide dependable energy while keeping rates affordable.”Work on the project began earlier this month and is scheduled to be completed in June.Ameren Missouri began providing electric power to the CertainTeed site in the fall of 2013.In addition, Ameren Missouri finished installing about 4 miles of new gas lines to power the CertainTeed complex in late 2014, which straddles the Warren-Montgomery County line about 60 miles west of St. Louis.Ameren