The Tala Project is located in the Chhukha Dzongkhag of Western Bhutan, just downstream of the Chhukha Project. Field investigation work related to the Tala Project was completed in March 1993. After finalizing of desk studies, a draft Detailed Project Report (DPR) was prepared by WAPCOS, on schedule, by August 1993. Various comments and suggestions on the draft DPR were received during a presentation of the draft DPR. A final DPR, incorporating these comments/suggestions, was prepared in October, 1993.

The Water & Power Consultancy Services India Ltd. (WAPCOS) a Govt. of India undertaking was appointed as the engineering design Consultants to the Project Authority. The expertise of premier organizations of the Government of India viz the Central Electricity Authority, Central Water Commission, Central Water & Power Research Station, Central Soil & Materials Research Station, Geological Survey of India and Survey of India were also made available to the Project through WAPCOS. The National Institute of Rock Mechanics(NIRM) still continues to provide consultancy in instrumentation in various appurtenants of the Project.

The implementation of the Project including creation of basic infrastructural facilities started in October 1997. The main works of the Project started in early 1999. Despite many adverse geological problems encountered in many components of the Project and the extensive damages caused by the unprecedented rains of 2000, the first unit of the Project was commissioned on 31 July 2006 and the last unit was added on the bar on 30 March 2007. The Project components stretch for approximately 100 Kms from Dam at Wangkha to TRT Outfall at Tabji.

The Detailed Project Report (DPR) provided for an estimated cost of Rs/Nu. 14180 million on June 1993 price level and a completion schedule of 8 years including 2 years of infrastructure development. The completion cost of the Project was sanctioned, in September 2005, on the basis of an estimate framed in September 2004, at a sum of Rs./Nu. 41,240 million, including restoration/compensation of damages due to Monsoon 2000 and Acceleration Measures for compressing the construction schedules. The final cost of completion of the Project is Nu. 41,258.545 million. The Government of India has fully financed the Project in the ratio of 60% grant and 40% loan repayable in 12 equated annual installments at a simple interest rate of 9% per annum.

The Project Headquarters at Gedu including all assets worth of Nu.933.413 million have been handed over to the Royal University of Bhutan for setting up of the Gaeddu College of Business Studies based on the decision taken by the RGoB in the 85th Session of the National Assembly. The new Plant Headquarter has been relocated to Rinchen Tse which lies along the approach road to the Power House and the entire construction is being funded from the Plant’s O&M revenue.The 2 Nos. 400kV Double Circuit Transmission lines of approximately 147 Kms upto the Bhutan –India border and the 200MVA, 400/220kV Interconnecting Substation at Malbase constructed at a cost of Nu. 2287.144 million have been handed over to the Bhutan Power Corporation with effect from 1 July 2007 along with the loan & IDC component.

in the world. The 23kms long Head Race Tunnel is perhaps one of the longest of its kind in this part of the world.The optimum full reservoir level has been kept as 1363m considering the tail race out-fall of the Chhukha Project and simultaneously the need to utilize fully the available head in the reach. The minimum draw-down level of 1352m provides a live storage of 3.2 million cubic metres; this is adequate to provide peaking capacity benefits during the lean season in winter for 4 hours, on a 90% dependable basis.

The tariff for export of power to India has been fixed at Nu.1.80 per kWh in line with the Power Purchase Agreement signed between PTC India Limited and the Royal Government of Bhutan. Besides the revenue from export of surplus power to India, the Tala Hydropower Plant has been mandated by the RGoB to meet the domestic energy requirements which was previously met by CHP.

Project Area

: 27o dergree  to 27.5 degree N, 89 degree to 91 degree E

River               

: Wangchu

District           

: Chhukha Dzongkhag, Western Bhutan

Dam Site       

: Near Wangkha village, 3km

  Downstream of Chhukha Project Tail-race

Power House

: Near Tala village

Full Reservoir level                 

: 1363m

Minimum draw-down level  

: 1352m

Reservoir volume                    

: 9.8 million cu.m

Peaking volume                         

: 3.2 million cu.m

Surface area at FRL                  

: 0.36 sq km

Catchment Area                                              :

: 4028 sq. km

Average flow at Dam site                            

: 99 cu.m/sec

Mean Annual Run-off                                   

: 3107 million cu.m

Minimum 10-daily flow 9in 90% year)  

: 19.5 cu.m/sec

Mean winter flow (in 90% year)                

: 23.4 cu.m/sec

Annual mean                                                     

: 77.6 cu.m/sec

Standard Project Flood                                

: 8575 cu.m/sec

Probable Maximum Flood                          

: 10,600 cu.m/sec

No.                                            

: 1

Size                                           

: 4m (W) x 3m(H)

Crest EI                                   

: 1360m

Gates                                        

   1 no., 4m x 3m, vertical lift fixed wheel

: service gate 1 no., 4m x 3.66m,

  vertical lift fixed wheel emergency gate

Energy Dissipater                

: Trajectory Bucket

Bucket lip                                

: 105m down stream (D/S) of Dam axis

Trajectory impingement  

 : About 205m D/S of Dam axis

Number

: 3

Type

: Straight intake with bell-mouth

Location

: Right Bank

Intake Tunnels

: 3 nos., 4.9m dia, modified horse-shoe

Maximum Discharge

 : 171 cu.m/sec

Intake C/L level

: 1343.5m

Gates

   3 nos., 4m x 4.9m vertical lift fixed wheel,

 : service gates 1 no., 4m x 4.9m vertical

    lift fixed wheel, emergency gate

No

 : 3

Size

: 250m (L) x 13.9m (W) x 18.5m (H)

Design Particle Size

 : 0.2mm and above (suspended sediment)

Construction Adit common

: 36m, 7m, D-shaped

Top branch

: 174m, 6m. D-shaped

Bottom branch

:189m, 6m. D-shaped

Gates  

: 3 nos., 4.2m (W) x 4.9m (H), vertical lift fixed wheel

 Adit to Gate Chamber

: 143m, 6m D-Shaped

 Gate shaft

: 7.1m x 2.9m (elliptical shaft) x 27m deep

Location

: Right Bank

Length

: 356m

Size

: 6.8m, D-Shaped

Design Discharge

: 350 cu.m/sec

Gate

: 4.2 x 4.9m, Vertical Lift fixed wheel

Type

: Concrete

Length

: 94m

Height

: 14m

Type

: Rock-fill

Length

: 45m

Height

: 3m

Type

: Concrete Gravity

Top of Dam

: 1366m

Average river bed elevation

: 1291m

Maximum height

: 92m

Length of non-overflow dam 

: 60.8m

Length of overflow dam

: 67.9m

Concreting

 : 3,52,000 cu.m

No 

: 5

Size

: 6.5m (W) x 13.15m (H)

Crest EI

: 1320m

Gates

    5 nos., 6.5m x 13.15m radial

 : 2 sets, 6.5m x 19.14m stop-logs

Size

: 3.5m dia D-shaped

Silt Flushing Discharge

: 20% (28.5 cu.m/sec)

 Gates

: 3 nos., 2.85m x 2.1m, Vertical lift slide gate

Gate Shaft

: 5.8m x 3.96m (oval shaft) x 43m deep

Length

: 23.00 km

Dia

: 6.8m modified horse-shoe

Design Discharge

: 142.5 cu.m/sec

Velocity at Design Discharge

: 3.75m/sec

Overloading Discharge

: 158.52 cu.m/sec

 Invert level at start

: 1338.074m

 Invert level at end

: 1257.20m

Bed Slope (average)

: 1 in 280

Size

: 7m, D-shaped

No

: 5 intermediate and 1 at inlet (11 faces) 

At inlet

: 73.5m

Thiyomachu

: 101m

Padechu

: 260m

Geduchu

: 963m

Mirchingchu

: 320m

Kalikhola

: 512m

At inlet

: 1 no.,2.5m x 2.5m, hinged type

At Mirchingchu

: 1 no., 1.2m x 1.5m, flap type

Type

: Restricted Orifice

Diameter

: 12m from bottom to EI. 1310m 15m from El. 1310m  to      El.1425,

Height

: 161 m (from orifice slab at El 1265 m to invert of upper  expansion chamber)

Orifice diameter

: 1.5 m

Computed Surge Levels (Discharge 158.52 cu m/sec) Load case 100-0-0(up)

 : 1423.07 m 

Load case 33-100-0 (up)

: 1425.754 m

 Load case 100-0-33 (down)

: 1279.122 m

Size

: 3 m (W) x 4 m (H)

Level

: 1300 m

Location

: 25 m from C/L of Surge Shaft

To Surge Shaft top

: 88 m x 6 m, D-shaped

To Surge Shaft bottom

 : 317 m x 7 m, D-shaped

 To Drainage Gallery

 : 376 m long, 3 m (W) x 4 m (H)

 Gates

 : 2 Nos. 3.66m x 5.2m vertical lift

Size

: 38 m (L) x 9 m (W) x 19 m (H)

No. of Valves

: 2 nos. 4.0 m dia

EOT Crane

: 1 no., 75/20 T

Crane beam support

 : RCC column-beam arrangement

 Adit Top

: 160 m x 6 m, D-Shaped

 Adit Bottom (branch)

: 12m x 7 m, D-shaped

Type

: Steel lined (ASTM A-537 Class II,

    thickness 30 mm to 38 mm;

    ASTM A-517 Grade F, thickness 38 mm to 40 mm)

Size

: 2 nos., 4.0m dia

Length

 PS I

 : 1069.40 m

PS II

 : 1021.00 m

C/C distance between Shafts

: 20 m

Inclination with horizontal

: 52 degree

Design velocity

: 5.6 m/sec

Maximum Design Pressure

: 9.24 Mpa, including water hammer

Manifold

: 4 m reduced to 3.2 m at bifurcation;

: 3.2 m bifurcated to 2.3 m and 2.3 m

No. of 2.3 m branches

: 6

Bifurcation type

: Escher Wyss internal sickle

Construction Adits size

: 6 x 7 m D-shaped

El. 1010 m

: 591 m

El. 765 m

: 820 m

El. 499 m (bottom)

: 349 m

Power House Cavern

: 206m (L) x 20.4 m (W) x 44.5m (H)

Installed Capacity

: 6 x 170 MW

Drainage/cable anchor gallery

: 3 m(W) x 4 m (H), 590 m long

Transformer Hall Cavern

: 191 m (L) x 16 m (W) x 26.5 m (H)

Rock pillar between PH/TH

: 39.3 m

Bus Duct 

: 3 nos., 39.3m x 10 m (W) x 8.5 (H)

Elevation of Service Bay

: 514.5 m

Size of Service Bay

: 42 m x 20.4 ,

EOT Crane in Power House

: 2 Nos, 200 T/40 T/20 T

Crane Span

: 19.05 m

Crane beam support

: Steel column-beam arrangement

EOT Crane Transformer Hall 1

 : no. 5 T

Crane Span

: 15 m

Crane beam support

: Steel bracket anchored to cavern wall

Main Access Tunnel (MAT)

: 377m. 7.5m (W) x 8.0m (H), D- shaped

Construction Adits (D-shaped)

  410m, 7m to top of Power House

 : 70m,7m to top of Transmission Hall

Unit Tail Race Gates

: 6 Nos. 4.0m x 4.5m vertical lift wheel type

Size

: 3.1.km, 7.75.m, horse-shoe

Type of flow

: Open Channel (Slope 1 in 1200)

Outfall Gate

: 1 no. 6.5.m (W) x 7.75.m (H)

Intermediate Adit

: 519.m, 7.m D-shaped

 Outfall Adit

: 130m, 7.m D-shaped

Type

: Vertical Pelton

No

 :6

Capacity

: 173.5 MW

No. of Jets

: 5

Nozzle level

: 501.5 m

Design Net Head

: 819 m

Rated Discharge

: 23.52m3/sec

Speed

: 375 rpm

Type

: Vertical shaft, Synchronous Machine

No

: 6

Capacity

: 190 MVA

Voltage

: 13.8 kV

Type

: Single Phase

No.

: 18 + 1 (spare)

Capacity

: 70 MVA

Rated Voltage

: 13.8. kV/400kV

Cable Tunnel

: 484 m, 5 m (W) x 5.5 m (H)

Pothead Yard

: 122 m x 31.5 m

400kv lines

: 2 nos. Double Circuit, 140 circuit km. up to border.

400 kV bays

: Five Nos.

220 kV bays

: Six Nos.

220kV lines

: 1 no. loop-in-loop-out connection each

with Chhukha and Birpara at Malbase

Rated Voltage

: 400/220kV

Type

: Single Phase

No

 : 3 + 1 (Spare) x 66.67MVA, 400kV/220kV

Firm Power

 90% Dependable Year

Average Year

MW Continuous

168 

199

Load Factor

16.48%

19.55%

Energy GWh

1472

1743

Total Annual Energy GWh

3962

4865

Average Annual Load Factor

44.34%

54.46%

First Unit (Unit VI) -

31 July, 2006

Second Unit (Unit V) -

7 October 2006

Third Unit (Unit IV) -

10 November 2006

Fourth Unit (Unit II) -

20 November, 2006

Fifth Unit (Unit I) -

12 February 2007

Sixth Unit (Unit III) -

30 March 2007

Sl No

Category

DGPC Grade

No. of employees

1

Executive

E1

0

2

Executive

E2

0

3

Executive

E3

5

4

Managerial

 M1

 7

5

Managerial

M2

 32

6

Managerial

M3

 35

7

 Supervisory

 S1

 26

8

  Supervisory

 S2

 24

9

  Supervisory

 S3

 15

10

 Operational

 O1

 66

11

 Operational

 O2

 116

12

 Operational

 O3

 31

13

  Operational

 O4

 54

14

  Operational

 O5

 143

15

  Operational

 O6

 40

16

  Operational

 O7

 82

17

 General Service Cadre

 GS1

 55

18

 General Service Cadre

 GS2

 74

TOTAL

805