Tallassee Shoals Hydroelectric Facility, Middle Oconee River, Athens

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Betty A. Smith, Tallasee Shoals Hydroelectric Facility HAER No. GA-59 (Page 2) Tallassee Shoals in Athens, Georgia, is the site of the existing Tallassee Shoals hydro facility. The Tallassee Shoals plant, constructed in was one of three plants built to bring electricity to Athens. Prior to this in a small steam plant near Mitchell's Bridge supplied electricity to this area. By more power was needed and a hydroelectric plant was built at Mitchell's Bridge. Also, by this time, electrical power was being used for other purposes in addition to running the electric street cars. In an additional turbine was installed at the Mitchell's Bridge plant. By the company (Athens Railway and Electric Company) needed additional generating capability, thus creating the Tallassee Shoals hydro facility.

"A substation was erected on Prince Avenue and three phase electric current from Mitchell's Bridge was merged with that generated and transmitted from Tallassee on a common switchboard and from that switchboard distributed throughout the city." (Rowe, When low water caused disruption of power generation in a combined steam plant and substation was installed at the site of the original steam plant. The steam turbine installed there was the first horizontal turbine used in Georgia. (Ibid.) In the water power at Earnett Shoals was developed into a third hydroelectric plant. By the Athens Railway and Electric Company was generating nearly (Ibid.) While these developments were occurring in Athens, other hydroelectric facilities were being constructed in other Georgia cities.

In the Georgia Power Company was organized and, between these hydroelectric facilities were consolidated under Georgia Power Company. (Wright Georgia Power continued utilizing the Tallassee Shoals hydroelectric plant until After that time, the equipment was removed from the powerhouse and, in the dam was breached. The following is a description of the original Tallassee Shoals power plant, taken from Hall and Hall Tallassee Shoals Power Completed in water backed four miles and covered 189 acres. The power head is 45 feet. The dam is 30 feet high, made of dry rock masonry and timber floored, and has rock abutment. The spillway is 366 feet long. The canal has 270 square feet of waterway and is feet long. The powerhouwe is of brick and stone masonry 30 feet by 50 feet.

Tailrace is 40 feet wide and 700 feet long. Tallassee Shoals Hydroelectric Facility HAER No. GA-59 (Page 3) Machinery. Two horizontal, 24-inch Victor turbines, 360 650 each, directly connected to 450 kW. generators, 3-phase, 60-cycle, volts. Total wheel capacity, Between and Georgia Power Company replaced the Victor turbines with two Leffel turbines with a combined output of kW. The foundation of the original powerhouse was expanded to accommodate more modern transformers and associated electrical equipment, in addition to the new turbines. A more technical description of the dam and associated facilities, as they exist today, is given below. This description is the result of field investigations and an extensive literature search.

The dam is approximately 365 feet long, 45 feet wide, 25 feet high at its maximum section and has a three-foot wide top. It is constructed of quarry rock, varying in size from a few inches up to several cubic yards. The upstream face of the dam is sloping on approximately a 1.5 horizontal to 1.0 vertical. The downstream face is essentially vertical. The downstream vertical face was constructed by hand, placing various size rocks in bands four to six feet wide. These rocks are held in place by the use of cement mortar. The gravel for grout in the cement is limestone, perhaps from northwest Georgia (Smith, B.A.}. Some surface or dental grouting was performed on the downstream vertical face. Upstream of the vertical band, rock appears to have been placed by hand with some mechanical help.

This rock varies in size from small boulders up to large rock in the range of two to three cubic yards. At least some of the rocks used in the construction of the dam were quarried and brought into the area. (Ibid.) Smaller fragments were used to fill in the voids created by the placement of the larger rock. A concrete grout cap was constructed over the top of the dam to give a uniform flow area as the water flowed over the dam. The front face of the dam appears to have been covered with wooden boards to help reduce seepage through the dam. The dam was breached in creating a 70-foot wide hole near the middle of the channel.

Concrete Grout Cap- Flow Wood Flooring

Tallassee Shoals Hydroelectric Facility HAER No. GA-59 (Page 4) The headrace gates at the original site were located in the left (east) abutment and, as of were in a state of complete disrepair. A sluiceway, six feet, eight inches high and four feet wide, is located just to the west of the head gates. The top of the sluiceway is approximately 14 feet, 8 inches below the top of the dam. The headrace to the powerhouse is approximately feet long, extending from the aforementioned gates to the inlet to the penstocks. The channel creates an additional 15 feet of head at the facility. The headrace is an earthen canal, approximately 20 feet wide on the bottom with sideslop at approximately two horizontal to one vertical.

The channel is heavily overgrown with small trees and brush and, in several places, has been destroyed where access roads to the river have been graded across it. The transition structure, from the earthen channel to the penstock, is a combination stone and reinforced concrete structure. When the site was abandoned, large blocks of stone and great quantities of earth was pushed into the openings, evidently to prevent accidents. The two penstocks, which funnel the water from the transition structure to the two turbines, are approximately eight feet in diameter and are 60 and 100 feet long respectively. They were installed in and, as of appeared to be in sound condition. The powerhouse foundation and turbines are all that remain of the original structure.

The turbines are of the vertical type, James Leffel, circa with adjustable wicket gates. There are two in place at the site. There are two in place at the site. Records indicate an operating rating of 750 kW (approximately horsepower) for this type of turbine. The powerhouse superstructure at Tallassee was destroyed when the site was abandoned in the early It was a brick structure, housing the previously-described electrical equipment and included a bridge crane to facilitate raising the various components of the turbine/generator for removal and repair. There are no generators, switching equipment or transformers on the site now. The original generators were 750 kW, volt, 3 phase, 60 cycle, mounted directly over the turbines.

The tailrace from the powerhouse back to the stream is approximately 700 feet in length. The lower end of the tailrace is silted in and no longer drains back into the river except during periods of unusually high rainfall. Oglethorpe Power Corporation is rebuilding the Tallassee Shoals Dam, in order to reactivate the hydroelectric power plant. When the dam is completed, waters will be impounded to a full pool level at the 645 Mean Sea level contour. Tallassee Shoals Hydroelectric Facility HAER NO. GA-59 (Page 5) BIBLIOGRAPHY 1. Hall, B. B. and M. R. Hall Third Report on the Water Powers of Georgia. Geological Survey of Georgia, Bulletin No. 16. 2. Rowe, H. J. History of Athens and Clark County. Athens, Georgia: The McGregor Company 3.

Smith, Betty A., Principal Investigator, Archaeological Survey of the Proposed Tallassee Shoals Hydroelectric Project, Jackson and Clarke Counties, Georgia. 4. Wright, Wade H. "Georgia Power Company and its Predecessors as Factors in the Establishment, Growth, and Development of the Electrical Industry in Georgia." Atlanta Historical Society Bulletin