CARTERS DAM
COOSAWATTEE RIVER, GEORGIA
PERTINENT DATA
MAIN DAM
GENERAL
Dam site, miles above mouth of Coosawattee River 26.8
Drainage area above dam site, square miles 376
RESERVOIR
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GENERAL
Primary flood control pool elevation, ft. above msl 1,099
Max. power pool elev. (wet season), ft. above msl 1,072
Max. power pool elev. (dry season), ft. above msl 1,074
Min. power pool elev., ft. above msl 1,022
Max. drawdown, feet 52
Area of primary flood control pool, acres 3,880
Area of maximum power pool, acres 3,220
Area of minimum power pool, acres 2,196
Flood storage volume, acre-feet 95,700
Power storage volume, acre-feet 134,900
Dead storage volume, acre-feet 242,200
Maximum elevation of clearing, ft. above msl 1,075
SPILLWAY DESIGN FLOOD
Natural peak discharge at dam site, cfs 194,200
Peak inflow to full reservoir, cfs 203,100
Regulated peak outflow, cfs 199,200
Regulated peak headwater, ft. above msl 1,107.2
STANDARD PROJECT FLOOD
Natural peak discharge at dam site, cfs 97,600
Natural peak stage at dam site, ft. above msl 716.8
Peak inflow to full reservoir, cfs 102,000
Regulated peak outflow, cfs 54,000
Regulated peak headwater, ft. above msl 1,106.5
Regulated peak tailwater, ft. above msl 707.0
NATURAL STREAM FLOW AT DAM SITE
Period of continuous record l937-l963*
Average flow for period of record, cfs 770
Minimum mean monthly flow in period of record, cfs 210
Minimum mean daily flow in period of record, cfs 178
Maximum mean monthly flow in period of record, cfs 2,210
Maximum mean daily flow in period of record, cfs 12,400
Maximum flow during period of continuous record
(flood of April, 1938), cfs 26,700
Peak stage for period of continuous record
(flood of April 1938), ft. above msl 685.9
Floodway capacity for downstream reach,
(dry season), cfs 3,200
Floodway capacity for downstream reach,
(wet season), cfs 5,000
*Flows estimated by correlating Carters flow with
Cartecay River near Ellijay, Georgia
MAIN DAM AND DIKES
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ROCKFILL DAM
Top elevation, feet above msl 1,112.3
Top width, feet 40
Length, feet 2,053
Maximum height, feet above foundation 445
Upstream slope 1 on 1.9
Downstream slope 1 on 1.8
Freeboard, top of dam above Spillway Design Flood, ft. 5.1
EARTHFILL SADDLE DIKES
Top elevation, feet above msl 1,112.3
Top width, feet 30
Number of dikes 3
Total length, feet 700
Maximum height, feet 40
Side slopes 1 on 2.5
Upstream slope protection dumped rock
Freeboard, top of dikes above Spillway Design Flood, ft. 5.1
EMERGENCY GATED SPILLWAY
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GENERAL
Total length, including end piers, ft. 262
Net length, ft. 210
Elevation of crest, ft. above msl 1,070.0
Type of gates tainter
Number of gates 5
Length of gates, ft. 42
Height of gates, ft. 36.5
DIVERSION TUNNEL
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GENERAL
Length, ft. 2,407
Shape horseshoe
Lining none
Bottom width, ft. 23
Maximum height, ft. 23
EMERGENCY LOW-LEVEL SLUICE
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GENERAL
Number of sluices 1
Total length of tunnel, ft. 2,712
TUNNEL UPSTREAM OF GATE STRUCTURE
Length of tunnel, ft. 1,198
Shape circular
Lining concrete
Nominal diameter of excavated tunnel, ft. 19.5
Diameter of lined tunnel, ft. 16.5
Invert elevation at upstream portal, ft. above msl 725
GATE STRUCTURE
Length of structure, ft. 62
Number of water passages 2
Invert elevation of water passages, ft. above msl 723
Number of gates per passage 2
Total number of gates 4
Type of gates slide
Height of gates, ft. 10
Width of gates, ft. 5
Type of operating machinery hydraulic
Nominal diameter of excavated shaft for combined
emergency access and air vent, ft. 10
TUNNEL DOWNSTREAM OF GATE STRUCTURE
Length of tunnel, feet 1,452
Shape horseshoe
Lining none
Bottom width, ft. 22
Maximum height, ft. 22
Length of concrete splash apron, ft. 200
Invert elevation at downstream portal, ft. above msl 710
DOWNSTREAM CHANNEL
Length, ft. 640
Maximum bottom width, ft. 50
Side slopes:
Sound rock 4 on 1
Weathered rock 1 on 1
Overburden 1 on 2
Bottom elevation at downstream end of 700
POWER INTAKE
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GENERAL
Number of intake structures 2
HEADRACE
Length (approximate), ft. 1,600
Width (minimum section), ft. 200
Side slopes 4 on 1
Bottom elevation, ft. above msl 979.0
INTAKE STRUCTURES
Top elevation, ft. above msl 1,112.5
Width of each structure, ft. 94
Length of base, ft. (excluding transition) 51
Maximum height, ft. 138.5
Type of head gate tractor
Number of head gates, each structure 2
Height of gate, ft. 20.5
Width of gate, ft. 14
Type of operation fixed hoist
Elevation of operating deck, ft. above msl 1,112.5
PENSTOCKS
Number 4
Length of conventional unit penstocks, ft. 835
Length of pump-turbine unit penstocks, ft. 838
Nominal diameter of excavated tunnel, ft. 23
Inside diameter of steel-lined penstock, ft. 18
Minimum thickness of concrete liner, inches 30
POWER DATA
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GENERAL
Number of units 4
Capacity of each unit, kw 125,000
Total installation, kw 500,000
Dependable plant output during critical period, kw 500,000
Operating head at maximum power pool, ft. 396
Minimum head at full drawdown, ft. 324
Maximum head loss at 115% generator rating, ft. 4.8
Maximum discharge per unit at 115% generator
rating (conventional unit), cfs 5,400
Maximum discharge per unit at 115% generator
rating (pump-turbine unit), cfs 5,400
Discharge each pump-turbine unit at 385 feet
total head, cfs 3,765
Maximum discharge at minimum power pool, elev. 1022,
(estimated for 4 units), cfs 20,900
GENERATING UNITS 1 AND 2 ONLY
Speed-RPM 163.6
Spacing of units, center to center, ft. 63
Turbines
Type-Francis, clockwise rotation
Capacity, guaranteed
at 345.0 ft. net head, HP, each 172,000
at 393.0 ft. net head, HP, each 199,000
Spiral cases - plate steel
Draft tubes - concrete elbow,
three discharge passages
Generators
Type - Vertical shaft, with combined thrust
and guide bearing below rotor and with
air enclosure for self-ventilation.
Ratings
Continuous at 60 C. rise - 125,000 kW,
131,579 kVA
Continuous capability at 1.15 rating - 143,750 kW,
151,316 kVA
Power factor 0.95
Voltage, 60 hertz, 3-phase 13,800
Short circuit ratio, not less than 1.175
Fly wheel effect (wK2 LBS-FT ) 95,700,000
Ratio, Xq"/Xd", not more than 1.35
GENERATOR/MOTOR UNITS 3 AND 4 ONLY
Speed-RPM 150
Spacing of units, center to center, ft. 63
Pump/Turbines
Type-Francis, clockwise rotation as
turbine; counter-clockwise rotation
as pump
Capacity, guaranteed
at 345.0 ft. net
as a turbine 173,000
at 376.0 ft. net
as a turbine 209,000
at 347 ft. total eff 87.6%
at 383 ft. total eff 87.2%
Spiral cases - plate steel
Draft tubes - concrete elbow,
three discharge/intake passages
Generator/Motors
Type - Vertical shaft, with thrust-bearing
above rotor and guide-bearings above
and below rotor, and with air enclosure
for self-ventilation.
Ratings
As a generator:
Continuous at 60 C. rise - 125,000 kW, 131,579 kVA
Continuous capability at
1.15 rating 143,750 kW, 151,316 kVA
Power factor .95
Voltage, 60 hertz, 3-phase 13,800
Short circuit ratio not less than 1.175
Flywheel effect (Wk2), LBS-FT2 90,000,000
As a motor:
Output, rated, horsepower 185,000
Power factor .95
Voltage, 60 hertz, 3-phase 13,800
Speed, RPM 150
POWERHOUSE
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GENERAL
Location - right bank about 200 feet below the
downstream toe of the main dam and 700 feet
northward from the river channel
Size of building
Length, feet including unloading bay 361'-6"
Width, feet (including draft tube deck) 114'-3"
Entrance wing ("L" shaped)
ELEVATIONS, FEET (MSL)
Bottom of structure 603.20
Low point of draft tube (Units 1 & 2) 620.00
(Units 3 & 4) 615.67
Centerline of distributor (Units 1 & 2) 658.00
(Units 3 & 4) 649.00
Turbine room floor (Units 1 & 2) 676.00
Generator room floor (Units 1 & 2) 691.00
(Units 3 & 4) 676.00
Control room 691.00
Erection floor 708.00
Unloading floor 708.00
Draft tube deck 708.00
Crane runway rail 737.50
Roof, high point 758.08
Top of parapet 761.92
DRAFT TUBE GATES
Type Vertical lift, slide
Number 3
Size, feet (approx.) 13'-9«" x 20'-l«"
Method of handling Gantry crane
Type Vertical life, slide
Number 6
Size, feet (approx.) 13'-9«" x 21'-8«"
Method of handling Gantry crane
REREGULATION DAM
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GENERAL
Dam site, miles above mouth of Coosawattee River 25
Drainage area above dam site, square miles 530
Drainage area of reregulation dam only, square miles 154
RESERVOIR
Maximum storage poo1 elevation, ft. above msl 698.0
Maximum normal operating poo1 elevation, ft. above msl 696
Minimum poo1 elevation, ft. above msl 662.5
Minimum normal operating pool elevation, ft. above msl 677
Area at maximum storage pool, acres 870
Area at minimum pool, acres 50
Usable storage, acre-feet 17,210
Dead storage, acre-feet 290
Area acquired, acres 1,373
Maximum elevation of clearing, ft. above msl 700.0
Area cleared, acres 320
SPILLWAY
Total length, including end piers, ft. 208
Net length, ft. 168
Elevation of crest, ft. above msl 662.5
Number of piers, including end piers 5
Width of piers, ft. 8
Type of gates tainter
Number of gates 4
Length of gates, ft. 42
Height of gates, ft. 36.5
Elevation of top of gates in closed position, ft msl 699.0
Elevation of low steel of gates in fully open, ft msl 699.0
Elevation of trunnion, ft. above msl 675.0
Elevation of access bridge, ft. above msl 717.0
Elevation of stilling basin apron, ft. above msl 647.5
Length of stilling basin, ft. 40
Height of end sill, ft. 4
EARTH DIKES
Top elevation, ft. above msl 703.0
Length, ft. 2,855
Top width of right dike, ft 32
Top width of left dike, ft 12
Side slopes 1 on 3
Thickness of riprap, inches 24
Thickness of filter material, inches 9
Thickness of dumped rock, inches 60