The 24-MW Ocoee Dam No. 1 hydro project helped electrify Tennessee and Georgia after its construction in 1911 and today still provides power and recreational opportunities for residents in the region.
By Bill Sitton
In a region known for harnessing the power of water to improve the lives of area residents, one of the first hydropower projects in the Tennessee Valley - Tennessee Valley Authority's Ocoee Dam No. 1 in Polk County, Tenn. - still reliably generates electricity as it has since the dam was completed in 1911.
In fact, the 100-plus-year-old Ocoee Dam No. 1 began delivering electricity to Chattanooga, Tenn., and the surrounding region more than two decades before TVA was created in 1933. Today, Ocoee Dam No. 1 continues to provide a capacity of 24 MW using the same configuration as when it was built. Ocoee Dam No. 1 has generated an average of nearly 60,000 MWh of electricity over the past five years.
"One hundred years after it went into operation, Ocoee Dam No. 1 is still producing clean, low-cost hydropower for the region," says John McCormick, senior vice president of TVA River Operations and Renewables. "This dam changed the standard of living, the economy and the recreational opportunities in this area as it shaped the Ocoee River."
At the time the dam was built, household electricity was just being introduced. Residential electric usage grew rapidly from its inception, around 1905, to the 1930s, when 70% of homes were electrified. This growth was fueled by the invention of new household electric appliances, such as air conditioners and washing machines, around the time Ocoee Dam No. 1 was under construction.
Ocoee Dam No. 1 was the first in a series of hydro projects currently operated by TVA on the Ocoee River in southeast Tennessee. The river starts as the Toccoa River in the mountains of northwest Georgia, with the name changing at the Georgia/Tennessee state line. The Ocoee River flows into the Hiwassee River, which then joins the Tennessee River.
Ocoee Dam No. 1, the facility furthest downstream on the Ocoee River, was completed by the East Tennessee Power Company, which later became the Tennessee Electric Power Company. TVA acquired the company, along with Ocoee Dam No. 1, Ocoee Dam No. 2 and the Ocoee Flume, in 1939 after passage of the Tennessee Valley Authority Act in 1933. TVA built Ocoee Dam No. 3 in 1942.
|The 24-MW Ocoee Dam No. 1 project began commercial operation in 1912 to deliver electricity to Chattanooga, Tenn., and the surrounding region.|
Ocoee Dam No. 1 history
Work on Ocoee Dam No. 1 began in 1910. Ocoee Dam No. 1 was built on the site of the mid-19th century Park's grist mill in the Parksville community, outside the current town of Ocoee, Tenn. Dam construction took just 18 months and cost $2.7 million. The cyclopean gravity dam, which is 840 feet long and 135 feet high, sits between the steep slopes of Sugar Loaf and Bean mountains. The dam contains 160,000 cubic yards of concrete. More than 600 bucket loads of concrete were placed into 15-foot by 8-foot forms each day by 11 90-foot-high derricks.
Ocoee Dam No. 1 formed the 1,930-surface-acre Parksville Reservoir, which has about 47 miles of shoreline. Ocoee Dam No. 1 helps provide flood control for a drainage area of about 595 square acres. The reservoir level fluctuates about 9 feet from summer to winter, and it has a flood storage capacity of 19,000 acre-feet. The majority of the land surrounding Parksville Reservoir is managed by the U.S. Forest Service as part of the Cherokee National Forest.
To support construction in the remote area, a small town was built for the 1,500 workers and their families. The town featured a waterworks, stores, ice plant, hospital, and fire and police protection. The remains of a railroad trestle built across the river to transport equipment, workers and crushed quarry rocks from Sugar Loaf Mountain are still visible.
The five original generating units - four placed in operation in 1912 and the fifth added in 1914 - provided a total capacity of 18 MW. According to historical documents from Tennessee Electric Power, the original plant equipment was "comprised of five horizontal twin type S. Morgan Smith turbines, each rated at 5,400 horsepower and direct connected to five 3,750 kva 3 phase, 60 cycle Westinghouse alternators operating at 2,300 volts and 360 revolutions per minute." Each turbine is supplied through a separate penstock 30 feet below the normal headwater elevation, allowing water to be drawn during the low-water season.
The facility started generating electricity for machinery, streetcars and homes in January 1912. Transmission lines were built to deliver its power to Chattanooga, Knoxville and Nashville in Tennessee and Rome in Georgia, as well as to the aluminum smelters in Alcoa, Tenn. Today, power from Ocoee No. 1 is fed into the TVA electric grid, which serves nearly 9 million consumers.
The Ocoee Dam No. 1 and powerhouse have undergone only minor changes in nearly 100 years. Between 1934 and 1937, the generators were reconstructed to 4.5 kVa, giving the dam most of its overall generation capacity increase. The generators were rewound in 1991, when the unit governors were upgraded. At the same time, TVA added modern controls in the dam powerhouse, moving them from a balcony that overlooks the powerhouse floor.
"The framework of the dam and powerhouse are essentially the same as when Ocoee Dam No. 1 came online that first time in 1912," said McCormick. "In fact, in the 1970s TVA began an effort to bring Ocoee Dam No. 1 up to modern design standards. Structurally, the dam was performing just as planned more than 60 years ago. The dam only needed to be resurfaced and strengthened, not redesigned."
The Parksville Steam Plant was built adjacent to the dam in 1916 to provide generation during periods of low river flow. Coal was last used at the site in 1954, and the steam plant was later removed.
|Today, Ocoee Dam No. 1 continues to provide clean, low-cost hydroelectric power production, using the same configuration as when it was built.|
Ocoee River power
The three Ocoee dams and powerhouses, along with the Ocoee flume, make ingenious use of topography and the powerful Ocoee River to maximize hydroelectric production. Between Ducktown, Tenn., and Parksville, a distance of 26 miles, the Ocoee River falls 710 feet through the Ocoee gorge. It passes through three Ocoee powerhouses that provide a total combined capacity of 76 MW.
Ocoee Dam No. 2, which is 12.3 miles upstream from Ocoee Dam No. 1, was completed in 1913, just one year after the first dam. Ocoee Dam No. 2 is constructed of a timber crib filled with rock and receives water from the unique Ocoee flume.. The wooden flume carries water 4.6 miles down the Ocoee gorge from the No. 2 dam to its powerhouse, with a slope of just 17.5 feet. When water arrives at the powerhouse, it drops 250 feet down a pipe to reach the turbine-generator units. As a result, the generating capacity of the 30-foot-high Ocoee Dam No. 2 project is roughly equal to what would be achieved if a 250-foot-high dam had been built at the powerhouse site.
Ocoee Dam No. 3, which was built by TVA in 1942, is located 5 miles upstream from Ocoee Dam No. 2. It uses a similar design as the No. 2 dam, sending water through a tunnel 2.5 miles downstream to the powerhouse. The concrete gravity dam is 110 feet high.
After passing through the three Ocoee powerhouses, the same water will produce electricity at seven additional TVA dams on the Tennessee River before eventually reaching the Ohio River. Ocoee No. 1, No. 2 and No. 3 are part of a fleet of 29 conventional hydroelectric facilities that help power daily life in the Tennessee Valley. In total, TVA operates an integrated system of 49 powerhouses.
In September 2011, TVA held a celebration of the centennial of the Ocoee Dam No. 1 project that included food, music, public tours of the power plant and informational displays. In addition, winners were announced in an art and essay contest for local students about their favorite Ocoee experiences.
|A working scale model of the 1996 Atlanta Olympic Games whitewater course built upstream in the Ocoee River sits below Ocoee Dam No. 1. The model allowed designers to plan placement of manmade elements in the riverbed.|
When TVA uses the water of the Ocoee River to generate electricity, the river channel is a bed of dry rocks, with just enough water, in places, for swimming. But when TVA diverts the water for recreation, the Ocoee River churns with whitewater excitement.
While whitewater rafting and paddling have long been a regional attraction on the Ocoee River, they received international attention when the 1996 Summer Olympics were hosted in Atlanta. TVA supported the creation and operation of the only in-river Olympic whitewater slalom course built at the time.
TVA and Olympic planners created a one-tenth scale model of the riverbed in Sugarloaf Mountain Park near Ocoee Dam No. 1 to predict flow patterns, wave heights, flow velocity and water depth. This modeling helped reduce disruption to the riverbed during construction of the course. TVA then diverted water from the riverbed below Ocoee Dam No. 3 to create the quarter-mile course of strategically placed boulders, drops and eddies used for the Atlanta Games competition.
During the Olympic competition, TVA controlled the course's water flow through a precision gauge at Ocoee Dam No. 3. Water from the dam took two hours to travel 2.5 miles downstream to the course, which is still used by paddlers today.
Commercial and individual whitewater rafting, kayaking and paddling receive ongoing support from TVA through scheduled recreation water releases below the three Ocoee dams that vary depending on location from mid-March through early November. TVA sends 1,000 to 1,600 cubic feet per second of water downstream on scheduled release days, which are posted online for public viewing on the TVA website at www.tva.gov/river/recreation/schedules.htm.
"The Ocoee River is both a natural wonder and a playground for families and outdoor enthusiasts," says McCormick. "You can paddle, swim, fish, hike, bike or picnic on the public water and lands that surround TVA dams on the Ocoee River."
The Tennessee Valley Authority, a corporation owned by the U.S. government, provides electricity for distribution utility and business customers in most of Tennessee and parts of Alabama, Mississippi, Kentucky, Georgia, North Carolina and Virginia - an area of 80,000 square miles with a population of 9 million.
TVA operates 29 hydroelectric plants, 11 coal-fired power plants, three nuclear plants and 12 natural gas-fired power facilities and supplies up to about 34,000 MW of electricity, delivered over 16,000 miles of high-voltage power lines.
TVA also provides flood control, navigation, land management and recreation for the Tennessee River system and works with local utilities and state and local governments to promote economic development across the region. TVA, which makes no profits and receives no taxpayer money, is funded by sales of electricity to its customers. Electricity prices in TVA's service territory are below the national average.
Bill Sitton is a communications specialist with the Tennessee Valley Authority.