Thurmond Dam turbines getting inspected

Through the dim glare of a flashlight, Phinizy Davis gazed at a part of Thurmond Dam most people never see.


"This is the first time they've opened this one," the power project manager said, examining the interior of the dam's Unit 2 turbine, where engineers are performing a series of inspections this month.

The dam's original seven turbines, built in the 1940s, were replaced one-by-one during a $70 million renovation that began in the late 1990s. After the first few years of operation, the new units are shut down, one at a time, for an inspection to gauge how well they are performing.

"We bring in engineers from outside our project -- electrical and mechanical people," Davis said. "We're doing Unit 2 now, we'll do Unit 3 in three weeks and by the end of the year we'll try to get to 5 and 6."

The inspections have found no problems with the mammoth aluminum turbines. Weighing 40 tons apiece, and producing 72,500 horsepower per unit, they are vastly more efficient than the 59-ton iron turbines installed in the dam when it was built.

"We still look for condition changes, cracks, things like that," he said. "We don't expect to find anything but we still look."

Inspectors work within the cavelike pipes -- called penstocks -- that force lake water through the dam to operate the turbines.

Unlike the original units retired over the past decade, the new turbines have an oxygen-injecting "venting" feature to increase oxygen downstream, which enhances water quality and makes the lower channel more suitable for fish. The new units also generate 30 percent more electricity.

The oxygen injectors are manually engaged by the dam operators whenever hot weather reduces dissolved oxygen levels in the lake and river -- usually in late summer and early fall.

"Each unit has three valves," Davis said. "We can open one, two or all three."

So far, the added oxygen has nearly doubled oxygen levels during warm weather months, while still producing adequate volumes of electricity.

Reach Rob Pavey at (706) 868-1222, ext. 119, or


See a gallery of nine Thurmond Dam photos at