Great Falls Hydroelectric Station, Rock Island Tennessee

Date added: October 12, 2023 Categories: Tennessee Power Plant Hydroelectric Power
Downstream view of powerhouse at Great Falls, from Caney Fork River Bank (note surge tank), looking southeast

The Great Falls Hydroelectric Station is an early large-scale, professionally-designed steel-reinforced concrete hydroelectric engineering project typical throughout the early days of electrical power development in the State of Tennessee. While its scale is Promethean by comparison, its design, especially when considering its water intake system, shares consistency in construction materials, genre, temporal limits, and utilitarian functions with other smaller pre-TVA hydroelectric sites on Tennessee's smaller rivers, such as the Shoals Creek No. 1 site in Lawrenceburg. Hydroelectricity has been continually produced at Great Falls since 1917, serving a wide variety of industrial and domestic electric needs of the area.

After reconnaissance surveys on the Caney Fork River had been completed in 1898, the Great Falls Power Company was established in March of 1901. After years of being unable to raise the necessary capital for the hydroelectric project, by 1909, the promoters had found the venture capital for investment in the H. M. Byllesby & Company of Chicago. Shortly thereafter, the Chicago firm purchased controlling interest, much in the way the E. M. Clark Company of Philadelphia had assumed its interests in the Ocoee River projects.

The Great Falls Hydroelectric Station was part the transition from private, local possession of property, to both intra-state and out-of-state corporate proprietorship, to public ownership of public utilities that occurred from 1901 to 1933 in Tennessee. It was also part of the introduction of a new public utility business, that of supplying electricity, that would become one of the major hallmarks of the twentieth century in Tennessee and thus is fundamentally representative of a change in the business of trading, production, commerce, communications, and commodities in a wide range of territories in the State of Tennessee. The Station was also built for flood control planning, as manifested by its eighteen floodgates.

On April 24, 1912, the Tennessee Power Company was organized, and it purchased the Great Falls Power Company and began buying land and developing plans for a power development. After initial work was stopped by floods, the Byllesby interests were sold to the E. M. Clark Company of Philadelphia, by this time the owner of the Nashville Railway and Light Company and directing interest in the Parksville project on the Ocoee River. There was spasmodic activity at the site until 1915 when construction began in earnest. By 1916-17, a dam was built, and the first tunnel through the isthmus was drilled through the narrows of the Collins and Caney Fork Rivers. The penstock, powerhouse, and transmission equipment were in place. The Great Falls site was first placed in operation on New Year's Day, 1917. Further construction completed in 1925 raised the height of the dam some thirty-five feet, augured a second tunnel, and built a second penstock, and placed a second, newer and higher-capacity generator in the expanded power plant, essentially as it appears today. The floods of 1929, while devastating to many, were controlled by the men at the Great Falls plant, and the dam's usefulness as a flood control unit was revealed. The property was acquired by TEPCO soon after its formation in 1922, and was sold to TVA in 1939. It is still operated by TVA today.

Site Description

Operated by the Tennessee Valley Authority since 1939, the Great Falls Hydroelectric Station is immediately downstream from the mouth of the Collins River, in Warren (population 32,653) and White (population 19,567) counties, about one-half mile downstream from Rock Island, Tennessee. The hydroelectric station is located at the peninsula formed by the meeting of the Caney Fork and Collins Rivers about two-thirds of a mile from Rock Island, at Caney Fork River mile 91.1, immediately downstream of the Collins River, one-half mile northwest from Rock Island, Tennessee, just off U. S. Highway 70, on the Rock Island Road.

The facility includes a dam, intake tunnels, penstocks, and powerhouse, and a circa 1955 control building. The dam was completed in 1916, but was redesigned in 1925, which resulted in its height being raised thirty-five feet. The dam, which creates a reservoir of the waters of the confluence of the Caney Fork and Collins Rivers, is essentially a concrete gravity non-overflow structure that includes an emergency spillway in its design. The reservoir extends into White, Warren, and Van Buren counties. The non-overflow section is 230 feet in length, while the spillway section is 535 feet long. Along with the cut-off wall at the dam's left abutment, which is thirty-five feet in length, the entire structure stretches 800 feet across the Collins River. There are eighteen crest gates, each twenty-five feet wide and fourteen feet high, separated by five-foot-thick piers. A fifteen-foot-wide roadway crosses the dam.

The intake structures are located on the left bank of the Collins River's arm of the reservoir, two-thirds of a mile west of the dam. These two conformations are of reinforced concrete and feature three openings, each fourteen feet wide. A stationary hoist, driven by an electric motor, controls the thirteen-by-fifteen caterpillar-type Broome gates. The two horseshoe-shaped intake tubes are concrete lined, leading to steel plate penstocks on the Caney Fork River side of the Collins River-Caney Fork River Peninsula. The No. 1 horseshoe tunnel is fourteen feet in diameter, while No. 2 has a diameter of sixteen feet. The tunnels are each 450 feet in length. The massive steel penstocks are both 160 feet in length while penstock No. 1 has a diameter of twelve feet and No. 2, fourteen feet. The two surge tanks, buffers protecting the two vertical Francis-type turbines and generators from sudden rushes of water, are of two types. Both are partially buried, while No. 1 is of steel and No. 2 is of steel-reinforced concrete. No. 1 has a height of ninety-one feet and a diameter of twenty feet, and No. 2 is seventy-four feet high and has a diameter of twenty-five feet.

The powerhouse is located on the left-downstream (south) bank of the Caney Fork River, and is located about two-thirds of a mile downstream from the dam. It is a rectangular-shaped structure, two and a half stories high, constructed of concrete, structural steel, and brick, with clerestory lighting. It is 135 feet long by thirty-two feet wide. It houses two generators driven by two hydraulic vertical Francis turbines made by Allis-Chalmers Manufacturing Company.

A utility building of unknown date is adjacent to the powerhouse, which is surrounded by a concrete wall, added to by the TVA as a flood protection measure. Additionally, after TVA ownership was secured leakage, problems that had developed through the Collins River-Caney Fork River Peninsula were corrected.

A circa 1955 two-story brick control building is located above the power house.

Great Falls Hydroelectric Station, Rock Island Tennessee Site Map
Site Map

Great Falls Hydroelectric Station, Rock Island Tennessee Great Falls Dam and bridge, looking northeast
Great Falls Dam and bridge, looking northeast

Great Falls Hydroelectric Station, Rock Island Tennessee Downstream view of powerhouse at Great Falls, from Caney Fork River Bank (note surge tank), looking southeast
Downstream view of powerhouse at Great Falls, from Caney Fork River Bank (note surge tank), looking southeast

Great Falls Hydroelectric Station, Rock Island Tennessee Powerhouse (note penstocks and surge tank), looking southeast
Powerhouse (note penstocks and surge tank), looking southeast

Great Falls Hydroelectric Station, Rock Island Tennessee Allis-Chalmers Generator, at Great Falls powerhouse
Allis-Chalmers Generator, at Great Falls powerhouse

Great Falls Hydroelectric Station, Rock Island Tennessee Interior of Great Falls powerhouse, note clerestory lighting
Interior of Great Falls powerhouse, note clerestory lighting

Great Falls Hydroelectric Station, Rock Island Tennessee Outbuilding on site
Outbuilding on site