MARION CO., Tenn. (WRCB-TV) - We began our trek as if driving into the Batcave, through large gates and into a tunnel; a hole that has been carved right into the side of Raccoon Mountain. When in use, water flows through here in a nearly thousand foot shaft through the center of the mountain. For more than 20 hours, it passes over four turbines creating enough energy to keep the power on in excess of 877,000 homes every day.

In a cavernous chamber, huge steel gates either hold the water back or allow it to pass. That is what these engineers are testing. Lights and a camera are mounted on little remote operated vehicle. It nimbly swims, darting about at the touch of a joystick. As the ROV dives, the engineers carefully watch a laptop monitor. They scan the gates and their massive tracks. They look for defects and check on past repairs.

This plant includes a dam, too. At 23 stories high and more than a mile long, it is the largest rock-fill dam ever built by TVA. "We'll certainly look to ensure that proper maintenance is being completed on mechanical equipment essential to the safe operation of the dam," said Jeff Barton of the Dam Safety Governance Organization. He keeps his eyes on the inspectors who, in turn, look at the structural integrity or signs of distress."

 While TVA has had its own safety program for 30 years, Barton's independent agency is new, coming after the coal ash spill of 2008. He makes sure they are ready for the worst. "I think it's important, when you consider the recent events in Virginia," he said, referring to the August earthquake, "to ensure that your facilities are designed and analyzed to withstand that type of seismic event."

And when your business is harnessing mother nature's power, her frequent spats of unpredictability are something that have to be considered. "This last year at Kentucky Reservoir, due to the flooding in the springtime and the significant rainfall, we hit the highest elevation on record for Kentucky Reservoir," Barton explained. "During those time periods, we'll have, or the asset owner will have people out on a daily basis doing special inspections."