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TEHRI DAM & HPP(STAGE-I)
Features
SALIENT FEATURES


 

Nature of Scheme:

Storage scheme

Hydrology

Normal Annual Rainfall    

1016  to 2630 mm.

Maximum recorded flood discharge   

3800   Cumecs

Adopted maximum flood for diversion during monsoon period 

8120   Cumecs

Probable maximum flood   

15540  Cumecs

Routed Flood  

13248  Cumecs

Reservoir

Full Reservoir Level   (FRL)

EL  830 m.

Maximum Level during design flood (MFL) 

EL   835 m

Dead Storage Level 

EL   740 m.

Gross Storage 

3540 MCM

Dead Storage

925 MCM

Live Storage 

2615  MCM

Water Spread at full Supply Level EL.830 m.

42 Sq.km.

Water Spread at dead Storage Level EL.740 m.   

18 Sq.km.

TECHNICAL FEATURES

 

Diversion Tunnels

Type 

  Horse shoe

Left Bank

 2 Nos. 11.0m dia, 1774 &1778 m long

Right Bank

2 Nos. 11.0m dia, 1298 &1429 m long

Diversion Flood Discharge 

8120 Cumecs

Dam

Type 

Earth and Rock fill dam

Top Level   

 EL 839.5 m

Height 

260.5 m

Width at riverbed  

1125 m

Width at top 

25.5 m flared to 30.5 m at abutments 

 Length at Top

 592m

Slope 

Upstream 

1: 2.5  

Downstream 

1: 2  

Spillways

Chute Spillway:  

 

Crest Level 

EL 815.0 m

Waterway                                                                  

3 bays of 10.5 m width

Design Discharge   

5500 Cumecs

Type & No. of Gates

Radial Gates, 3 Nos

Right Bank Shaft Spillway:

 

Type                                                                          

Ungated  2 Nos

Crest Level 

 EL 830.2 m

Dia of Shaft  

12.0 m

Design Discharge

 3850 Cumecs

Left Bank Shaft Spillway:  

 

Type 

Gated 2 Nos

Crest Level  

EL 815.0 m

Dia of Shaft 

12.0 m

Design Discharge

3650 Cumecs

Type of Gates

Radial gates

Intermediate Level Outlet: 

 

No. and size 

One; 8.5 m dia

Discharge capacity ( at EL. 830.0 m) 

1100 Cumecs

Intake Works:

 

Location 

Left Bank of river Bhagirathi

No & Type of Structure

2 Nos. Submerged Structure

Crest Elevation

EL 720 m.

Head Race Tunnels:

 

Size and Number

8.5m. dia, 2 Nos, 

Total Length

1634 m

Penstocks:

 

Number and Size

4 Nos., 5.75 m. dia each

Total Length

1040 m

Power House

Machine Hall:

 

Type 

Underground

Location

Left Bank, under ground

Number & Units

4 Nos, 250 MW each

Size

197 m long, 22.0 m wide, 47.2m. high

Head 

Maximum 231.5 m ,
Minimum 127.50 m ,
Design     188.0 m.

Transformer Hall:

 

Type

Underground

Size

161m.long X 18.5m.wide X 29.0m high

Step-up Transformers:

 

Capacity

306 MVA

Number

 4

Voltage Ratio

15.7/400 KV

Switchyard:

 

Location and Type

Indoor SF-6 Switchgear

Tail Race Works:

 

Number and size of tail race tunnels

2 Nos. , 9.0 m. dia  each

Length of Tunnels

 862.5 m & 747.5 m

Invert Level of Outlet

EL. 598.0 m.

Installed Capacity :

1000 MW (4x250 MW)