Calderwood Dam
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Calderwood Dam is a
hydroelectric dam Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...
located along the
Little Tennessee River The Little Tennessee River is a tributary of the Tennessee River that flows through the Blue Ridge Mountains from Georgia (U.S. state), Georgia, into North Carolina, and then into Tennessee, in the southeastern United States. It drains portio ...
in Blount and Monroe counties, in the U. S. state of
Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...
. Completed in 1930, the dam is owned and maintained by Tapoco, a subsidiary of the
Aluminum Company of America Alcoa Corporation (an acronym for Aluminum Company of America) is a Pittsburgh-based industrial corporation. It is the world's eighth-largest producer of aluminum. Alcoa conducts operations in 10 countries. Alcoa is a major producer of primary ...
(Alcoa), although the
Tennessee Valley Authority The Tennessee Valley Authority (TVA) is a federally owned electric utility corporation in the United States. TVA's service area covers all of Tennessee, portions of Alabama, Mississippi, and Kentucky, and small areas of Georgia, North Carolina ...
controls the dam's reservoir levels from
Fontana Dam Fontana Dam is a hydroelectric dam on the Little Tennessee River in Swain and Graham counties, North Carolina, United States. The dam is operated by the Tennessee Valley Authority, which built the dam in the early 1940s to satisfy the skyrocketin ...
further upstream.Alcoa
Calderwood Development
, 2010. Retrieved: 2010-01-04.
Calderwood Dam is named for Alcoa engineer Isaac Glidden Calderwood (1871–1941), who supervised much of the company's early Little Tennessee River operations.Russell Parker, "Alcoa, Tennessee: The Early Years, 1919–1939." ''East Tennessee Historical Society Publications'' Vol. 48 (1976), p. 85. Calderwood Dam was one of four dams— along with Cheoah, Santeetlah, and Chilhowee— built in the Little Tennessee Valley by Alcoa in the 20th century to provide electricity to its aluminum smelting operations in Blount County. The dam was one of the last to be completed in the Tennessee River watershed before TVA took control of the watershed in 1933. Alcoa developed the community of Calderwood, Tennessee, just downstream from the dam to house construction and maintenance crews for its Little Tennessee Valley operations. In 1989, Calderwood Dam was placed on the
National Register of Historic Places The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic v ...
. The listing was expanded in 1990 and again in 2004 to include most of the dam's substructures.Philip Thomason and Teresa Douglas, National Register of Historic Places Continuation Sheet - Supplementary Listing Record for Calderwood Dam, 2003-10-14.


Location

Calderwood Dam is located approximately upstream from the mouth of the Little Tennessee River, which flows westward from North Carolina and empties into the
Tennessee River The Tennessee River is the largest tributary of the Ohio River. It is approximately long and is located in the southeastern United States in the Tennessee Valley. The river was once popularly known as the Cherokee River, among other names, ...
. The area is surrounded by mountains on all sides, with the
Great Smoky Mountains The Great Smoky Mountains (, ''Equa Dutsusdu Dodalv'') are a mountain range rising along the Tennessee–North Carolina border in the southeastern United States. They are a subrange of the Appalachian Mountains, and form part of the Blue Ridge ...
rising to the north and the
Unicoi Mountains The Unicoi Mountains are a mountain range rising along the border between Tennessee and North Carolina in the southeastern United States. They are part of the Blue Ridge Mountain Province of the Southern Appalachian Mountains. The Unicois are ...
rising to the south.
U.S. Route 129 U.S. Route 129 (US 129) is an auxiliary route of US 29, which it intersects in Athens, Georgia. US 129 currently runs for from an intersection with US 19/ US 27 ALT/ US 98 in Chiefland, Florida, to an interchang ...
runs roughly parallel to the Blount County side of the river, providing the only major road access to the Calderwood area. The Calderwood complex graces a horseshoe bend in the river known as "The Narrows." The dam is located along the upstream end of this bend, and the powerhouse, service building, and old Calderwood community (now a recreation area) are located along the downstream end of this bend. The service building, recreation area, and historical community structures are accessible via Housley Road (gated at night), which connects US-129 to Growdon Road at the service building. Growdon Road continues past the service building to the powerhouse, although this section of the road is only publicly open to foot traffic. The Calderwood Overlook, located along US-129 just south of the road's intersection with Housley Road, provides a sweeping view of the Calderwood Reservoir. A gravel road, also open only to public foot traffic, connects the overlook to Calderwood Dam.


Design

Calderwood Dam is a thin-section concrete structure high and wide,Tennessee Valley Authority, ''Mechanical Design of Hydro Plants'', Technical Report no. 24, vol. 3 (Washington, D.C.: U.S. Government Printing Office, 1952), pp. 4-5. and has a 24-gate arched-crest spillway. A lower-gravity "cushion" dam is located downstream from the main dam, creating a pool of water that protects the riverbed. The pool's effectiveness is enhanced by a deflection unit at the base of the main dam.James Jones, Jr., National Register of Historic Places Nomination Form for Calderwood Hydroelectric Station, May 1990. Calderwood's powerhouse is located downstream from the dam, on the opposite side of the horseshoe bend in the river. A submerged intake just upstream from the dam diverts water into a concrete tunnel, which carries the water to the other side of the peninsula, where it spills down three
penstock A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills. H ...
s to a valvehouse. The penstocks measure approximately in diameter, and range in length from to . The valve house is built of steel-reinforced concrete, and is equipped with three
Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The proces ...
s. The powerhouse, a larger brick structure adjacent to the valvehouse, is equipped with three Westinghouse generators with a combined capacity of 140.4 megawatts. The powerhouse complex, located adjacent to a rockslide-prone cliffslope, is protected by a V-shaped reinforced concrete wall. Calderwood's reservoir covers approximately with a drainage area of . The elevation of Calderwood Reservoir is 1087.8 feet (USGS), and the reservoir covers an stretch of the river. About half of Calderwood Reservoir lies in Tennessee, with the remainder extending into
North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
.


History

Alcoa began developing the Little Tennessee Valley in 1909 to provide the enormous amounts of electricity needed to power to its aluminum smelting operations in Blount County. Superintendent I.G. Calderwood oversaw the extension of a railway line from Chilhowee to what is now Calderwood (railroad bridge support columns are still visible in the river just downstream from the dam). Southern Railway engineers had suggested that the construction of this rail line would take six months, but Calderwood and his team accomplished the task in just six weeks.Inez Burns, ''History of Blount County, Tennessee: From War Trail to Landing Strip, 1795-1955'' (Nashville: Benson Print Co., 1957), p.284. The first of Alcoa's Little Tennessee Valley dams, Cheoah, was completed in 1919, and the second, Santeetlah, was completed in 1928. Preliminary work on Calderwood Dam began in 1918, but test drilling suggested the site might not be satisfactory. Subsequent tests confirmed the site's stability, however, and construction began in 1927. The first two generating units went into operation on June 22, 1930, and a third unit was added in 1938. The "cushion pool" design of Calderwood was influenced by natural cascade waterfall formations. The dam's arched-crest design may have been influenced by the design of Ocoee Dam No. 1, which was completed in 1911 along the
Ocoee River The Toccoa River and Ocoee River are the names in use for a single river that flows northwestward through the southern Appalachian Mountains of the southeastern United States. It is a tributary of the Hiwassee River, which it joins in Polk Coun ...
a few miles to the south. Calderwood's use of a conduit tunnel to carry water to a powerhouse further downstream resembles the Great Falls Dam complex, completed in 1916 on the
Caney Fork The Caney Fork River is a river that flows through central Tennessee in the United States, draining a substantial portion of the southwestern Cumberland Plateau and southeastern Highland Rim regions. It is a major tributary of the Cumberland River ...
in
Middle Tennessee Middle Tennessee is one of the three Grand Divisions of the U.S. state of Tennessee that composes roughly the central portion of the state. It is delineated according to state law as 41 of the state's 95 counties. Middle Tennessee contains the s ...
. The community of Calderwood, Tennessee, located downstream from the dam and powerhouse, was developed in 1912 to house construction crews for Alcoa's Little Tennessee projects. This community was initially known as "Alcoa," but its name was changed to "Calderwood" in 1920 when the company reapplied its name to its main company town north of Maryville. The Calderwood community grew to include nearly two dozen houses, two churches, a school, and a theater, but as construction and maintenance crews were no longer needed, the community was largely abandoned in the 1950s. Its houses were all razed, but the school and theater (now used as storage) were added to Calderwood Dam's National Register listing in 2004.


References


External links


Calderwood Development
— Brookfield Renewable Energy Partners
Calderwood Dam
— TVA site

— Tennessee Wildlife Resources Agency official site {{Little Tennessee River dams Alcoa Power Generating dams Buildings and structures in Blount County, Tennessee Buildings and structures in Monroe County, Tennessee Dams completed in 1930 Dams in Tennessee Dams on the National Register of Historic Places in Tennessee Energy infrastructure completed in 1930 Hydroelectric power plants in Tennessee Dams on the Little Tennessee River National Register of Historic Places in Blount County, Tennessee National Register of Historic Places in Monroe County, Tennessee 1930 establishments in Tennessee