Upgrade Project at South Holston Dam Underway

As TVA works to upgrade the hydro generation unit in one of its most valuable dams, South Holston Dam Road in Sullivan County, Tenn., will be closed for approximately one year.

MARCH 13, 2017—The South Holston Dam, which spans the South Fork Holston River in upper East Tennessee, is one of TVA’s top plants in terms of value, providing power production, municipal water supply, flood risk reduction and excellent recreational opportunities among other benefits.

However, the rock-and-fill dam’s generating unit, rated at 49 megawatts, has degraded over the years, and now produces only 42 megawatts—a significant decline in power production.

That’s why TVA is executing a plan to restore the unit—original to the dam—by upgrading the turbine runner, wicket gates, turbine and generator shafts, the main transformer, generator rewind, generator leads/bus, exciters, powerhouse controls and auxiliary power equipment.

Other equipment at the site will be refurbished, such as the turbine shaft, the generator shaft and shaft bearings. Electrical and switchyard components will be rewired and/or replaced.

“The unit at South Holston Dam has been a workhorse, and it’s never had a major rehab in its 65 years of service,” says David Rowland, senior project manager, Hydro Generation Projects. “Once the upgrades have been made and we’ve installed a better-designed turbine, we’ll gain about 5,000 MWh of annual generation due to efficiency gains. That’s huge.”

Before any work on the unit can happen, there will be period of “pre-outage” activities at the site. A warehouse will be built on site to store parts and equipment needed for the project. The powerhouse crane will be rehabilitated, fiber optic lines will be laid to provide electronic communications and internet connections for the plant. and a public viewing area will be established on the north side of the dam to display the old turbine (which will be pulled from the powerhouse during the upgrade project).

While the work is happening TVA will temporarily close South Holston Dam Road in Sullivan County, Tenn., for approximately one year starting March 13, 2017. Holston View Dam Road and access to the top of the dam, overlooks, picnic areas and weir dam will not be impacted.

“We’ll be doing our work on the river-facing side of the dam, and we’ll still be releasing water through the dam at normal rates through the sluice gates,” Rowland explains. “All the lake access and fishing areas—including the weir—will remain open to the public. From a recreation standpoint, it will be business as usual.”