The marvel in the mountain

The marvel in the mountain

Hollowed into a S.C. mountain 25 years ago, engineering wonder Bad Creek hydro plant supplies power to 850,000 homes

Against gently sloping mountains and soothing sapphire-blue waters, Duke Energy blasted through tons of granite to carve a modern-day wonder. 

Hollowed into the side of a mountain in northwest South Carolina, it resembles James Bond villain Dr. No’s underground lair. But Bad Creek Hydroelectric Station near Salem, S.C., about 140 miles southwest of Charlotte, is actually a power plant with the ability to supply about 850,000 homes with energy on short notice.

It's a plant that has intrigued sightseers since 1991.

This year, Bad Creek celebrates its 25th anniversary with a private ceremony on Sept. 8. Duke Energy is also looking toward the future by upgrading the units. When the planned upgrades are complete in 2023, the plant will be able to power a million homes. 

An intelligent design

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Looking down at a draft tube gate in the Bad Creek Pumped Storage Hydro Station. The draft tube gates keep the area dry, protecting employees and equipment during maintenance.

The plant’s location is perhaps its most intriguing aspect, just steps away from Lake Jocassee in the foothills of the Blue Ridge Mountains. Winding, twisting roads lead to the site, which is secluded and surrounded by state park land. Access is restricted inside the mountain, though public tours were given years ago.

"It sits below Lake Jocassee buried inside a mountain," Station Manager Preston Pierce said. "The rustic part is, you really can’t tell that it’s there."

Why is the plant in a mountain? It’s a matter of engineering.

The plant’s pumped-storage design dictated the mountainside location. For the design to be most efficient, the powerhouse had to be located a certain distance below the reservoir.

Just like any hydroelectric station, Bad Creek uses the flow of water to produce electricity. During times of peak demand, water is released from the Bad Creek Reservoir at the top of the mountain through a concrete tunnel that travels nearly three quarters of a mile to the underground powerhouse. The water then spins huge turbine generators to produce electricity.

Because about 1,200 feet separate the reservoir and the lake, Bad Creek is able to take advantage of gravity to produce more electricity.

As a pumped-storage hydroelectric station, Bad Creek differs from traditional hydropower because when energy demand is low, the plant uses excess energy from other plants to power the turbines to pump water from Lake Jocassee to the reservoir at the top of the mountain.

It works like a battery – the water is stored and easily accessed by releasing the water down the mountain when customers need energy the most. Pumped-storage plants like Bad Creek account for 97 percent of the United States’ energy storage according to the National Hydropower Association.

Having pumped storage available, the U.S. Department of Energy’s Vision Report said, could help integrate renewables by being able to produce and consume power quickly when solar and wind energy production varies.

There are 40 pumped-storage hydropower plants in the United States and, according to the National Hydropower Association, about 270 in the world. Bad Creek is one of the newer plants. Its construction took roughly 10 years and cost $1 billion – it was finished one year ahead of schedule and $90 million under budget when it opened in 1991.

Richard Miller, Duke Energy communications operations manager, helped build the plant and said he hadn’t seen such a massive entrance tunnel before. The entrance slices through a chunk of solid granite and is large enough for a city bus to enter.

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Even more interesting than the entrance tunnel, Miller said, was the powerhouse cavern, which houses the turbines and generators that power the plant.

“The wow factor behind Bad Creek was how deep it was into the mountain and how big that powerhouse cavern was,” Miller said.

It was so spacious that the tallest building between Charlotte, N.C., and Atlanta, the 25-story Daniel Building in Greenville, S.C., could fit horizontally inside it and still have a little wiggle room.

Though the floors are roomy, overhead lighting sometimes casts a yellow tint, creating a cavern-like feel.

“It’s literally a cave,” Pierce said. “A lot of the walls are rock or concrete because it was chiseled out of a mountain.”

Monstrous machinery fills the space and vibrates the floors of the plant, which is cooled to compensate for the warmth of the machines. Miles and miles of pipe snake along the rough, deeply pocked and fissured walls like a maze. 

Water routinely drips from the jagged walls, and a safety net hangs from the vaulted ceiling to catch any stray rocks. For safety’s sake, equipment was installed to provide a celIphone signal strong enough to cut through 600 feet of rock.

The surrounding beauty

The engineering wizardry of the plant often takes a back seat to the spectacular background scenery ­– which is how planners wanted it.

“Even during construction,” Miller said, “you could be hiking, fishing or camping and not even know it’s there.”

A day of boating on the pristine waters of Lake Jocassee can take your breath – and your words – away, leaving only tranquility and reverence. Fall is spectacular, with the trees painting the hillsides fiery red, serene green and pumpkin orange. The season wraps a cloak of color around misty waterfalls and rugged gorges.

As part of the construction, Duke Energy built 43 miles of the Foothills Trail where the Bad Creek Warehouse is one of a dozen trail entry points. Pierce said it’s well used, and hikers might spot black bears, deer, turkeys, hogs and snakes.

It’s an outdoor office to Allan Boggs, a compliance supervisor based at Bad Creek. As part of his job, he often spends time outdoors on the water. Boggs considers Bad Creek worthy of the awe it’s received over the years and said it will always hold a special place with him.

“It’s a wonderful place to live and work,” he said. “It’s paradise.”

illumination Staff Writer Jessica Wells contributed to this article.

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