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 PHILPOTT LAKE PROJECT | Martinsville & Henry County, VA   

 


Location of dam

On Smith River at latitude 36 46'50", longitude 80 01'40", about 44.3 river miles above the mouth, about 7 miles upstream from Bassett, Virginia, and 34 air miles south from Roanoke, Virginia.

Drainage areas, square miles

Smith River at Philpott Dam site . . . . . . . . . . . . 212
Smith River at Bassett, Virginia (gage). . . . . . . . . 253
Smith River at Martinsville, Virginia . . . . . . . . . 374
Smith River at mouth near Eden, N. C . . . . . . . . . . 550

Flows at damsite in period Sep 1929 - Dec 1981. c.f.s.

Average . . . . . . . . . . . . . . . . . . . . . . . . 285
Maximum (19 Oct 1937) . . . . . . . . . . . . . . . . 32,000
Minimum (weekly mean, Sept 1932) . . . . . . . . . . . . 40
Maximum monthly (Oct 1937) . . . . . . . . . . . . . . .1,205
Minimum monthly (Aug 1981) . . . . . . . . . . . . . . . 29

Elevations, feet, mean sea level

Top of dam . . . . . . . . . . . . . . . . . . . . . . .1,016
Flood plain (general elevation). . . . . . . . . . . . . 815
Base of dam (approx.). . . . . . . . . . . . . . . . . . 797
Crest of spillway. . . . . . . . . . . . . . . . . . . . 985
Maximum surcharge elevation (spillway design flood). . .1,014
Top of power intakes . . . . . . . . . . . . . . . . . . 902
Minimum elevation to which land has been purchased or
flowage easement acquired . . . . . . . . . . . . . . . 998
Reservoir clearing limits:
Upper. . . . . . . . . . . . . . . . . . . . . . . . 977
Lower. . . . . . . . . . . . . . . . . . . . . . . . 940
Max. (22June72) . . . . . . . . . . . . . . . . . . . 983.06
Min. (26Sep56). . . .. . . . . . . . . . . . . . . . . 927.59

Tailwater elevations. feet, mean sea level


Maximum level for spillway design flood outflow
(70,000 c.f.s.) . . . . . . . . . . . . . . . . . . . . 836
Maximum design level for protection of powerhouse
(20,000 c.f.s.) . . . . . . . . . . . . . . . . . . . . 822
Normal operating level . . . . . . . . . . . . . . . . . 811
Minimum level, regulated flow (20 c.f.s.). . . . . . . . 808

Reservoir


State affected . . . . . . . . . . . . . . . . . . . . . Virginia
Counties affected. . . . . . . . . . . . Franklin, Henry, Patrick
Length along Smith River at elev. 985. . . . . . . . . . 16 miles
Length of shoreline at elev. 985 . . . . . . . . . . . .110 miles
Maximum width at elev. 985 . . . . . . . . . . . . . . 0.75 miles
Storage: Acre-feet Inches
Total volume at elev. 1014. . . . . . . . . 318,300 28.2
Uncontrolled flood storage (elev. 1014
to elev. 985). . . . . . . . . . . . . . . 117,900 10.4
Controlled flood storage (elev. 985 to
elev. 974) . . . . . . . . . . . . . . . . 34,200 3.0
Power drawdown (elev. 974 to elev. 920) . . 111,200 9.8
Volume at design minimum power pool
(below elev. 920). . . . . . . . . . . . . 55,000 4.9
Surface area:
Total area at elev. 998 . . . . . . . . . . . . . . . 4,060 ac.
Maximum power pool (elev. 974). . . . . . . . . . . . 2,880 ac.
Design minimum power pool (elev. 920) . . . . . . . . 1,350 ac.
Original river area (below elev. 998) . . . . . . . . 310 ac.

Dam

Type. . . . . Concrete gravity with 120 ft. long ungated spillway
Foundation. . . . . . . . . . . . . . . . . . Quartz mica schist
Length. . . . . . . . . . . . . . . . . . . . . . . . . . 920 ft.
Maximum height of dam . . . . . . . . . . . . . . . . . . 220 ft.
Maximum width at base . . . . . . . . . . . . . . . . . . 166 ft.

Sluices

Number. . . . . . . . . . . . Three,5 ft. 8 in. by 10 ft. 0 in.
Sluice gates. . . . .Six (1 service and 1 emergency per outlet)
slide gates, hydraulically operated.
Total capacity at elev. 985 . . . . . . . . . . . 13,350 c.f.s.
Low flow outlets:
Number. . . . . . . . . . . . . . . .Two, circular, 12 in. I.D.
Gates . . . . . . . Four (1 service and 1 emergency per outlet)
iron body gate valves; 3 manually operated,
1 electrically operated.
Total capacity at elev. 985 . . . . . . . . . . . . . 80 c.f.s.
Spillway energy dissipator:
Type . . . . . . . . . . . . . . . . . . . . . Stilling basin
Length . . . . . . . . . . . . . . . . . . . . . . . . 189 ft.
Elevation of end sill . . . . . . . . . . . . . . .806 ft. msl.
Elevation of bottom . . . . . . . . . . . . . . . .790 ft. msl.

Power Plant

Rated generating capacity:
2 units at 6700 kw each . . . . . . . . . . . . . . . 13,400 kw
1 unit at 600 kw . . . . . . . . . . . . . . . . . . 600 kw
Total . . . . . . . . . . . . . . . . . . . . . . . . 14,000 kw
Principal dimensions:
Power house . . . . . . . . . . . . . . . . . . 86 ft. x 76 ft.
Generator room. . . . . . . . . . . . . . . . . 82 ft. x 32 ft.
Intakes:
Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Gates . . . . . . . . . . . . . Slide type, fixed cable hoists
Penstocks:
Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Type . . . . . . . . . . . . . . . . . . . . . . . .Welded steel
Dimensions:
For 6700 kw units. . . . . . . . . . . . . . . . . 9'-0" Dia.
For 600 kw unit. . . . . . . . . . . . . . . . . . 3'-0" Dia.
Hydraulic turbines:
Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Type . . . . . . . . . . . . . . . . . . Francis, vertical shaft
Rated capacity
2 units at 9400 hp each at 152 ft. net head. . . . .18,800 hp.
1 unit at 860 hp at 152 ft. net head . . . . . . . . 860 hp.
Total. . . . . . . . . . . . . . . . . . . . . . . .19,660 hp.
Discharge at rated turbine capacity (152 ft. net head):
9400 hp units - 605 c.f.s. x 2 units . . . . . . . 1210 c.f.s.
860 hp unit - 55 c.f.s. x 1 unit . . . . . . . . . 55 c.f.s.
Total discharge. . . . . . . . . . . . . . . . . . 1265 c.f.s.
Normal speed:
9400 hp units. . . . . . . . . . . . . . . . . . . . . 277 RPM
860 hp units . . . . . . . . . . . . . . . . . . . . . 720 RPM
Draft tubes:
Type:
Main units . . . . . . . . . . . . . . . . . .Concrete below
Secondary unit. . . . . . . . . . . . . .Conical plate steel
Approximate throat diameter:
Main units . . . . . . . . . . . . . . . . . . . . . . 5'-5"
Secondary unit . . . . . . . . . . . . . . . . . . . .1'-11"
Horizontal length (center line of main unit turbines
to downstream face) . . . . . . . . .24'-0"
Net area at outlet opening (9400 hp. units). . . . 142 sq. ft.
Transformer:
Type.3 phase, 60 cycle, oil immersed, inert gas filled, air cooled.
13.2 - 138 kv . . . . . . . . . . . . . (series connection)
13.2 - 69 kv . . . . . . . . . . . . . (multiple connection)
Rating: 14,000 kva, self cooled
17,500 kva force cooled
Switchyard:
Size . . . . . . . . . . . . . . . . . . . . . . . . 55' x 54'
Outgoing lines . . . . . . . . . . 1-132 kv, 3 phase, 60 cycle
Martinsville and Henry County, VA

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