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VISHNUGAD PIPALKOTI H.E. PROJECT
Features
SALIENT FEATURES

A.   LOCATION:

State                                                               Uttarakhand

Distt.                                                               Chamoli

River                                                               Alaknanda

Dam site                                                        Near Village Helong

(E – 790  29’ 30”) (N - 300   30’ 50”)

P H site (underground)                                 Near Village Hat     

(E – 790   24’ 56”) (N - 300   25’ 31”)

B.   HYDROLOGY:

Catchment Area at Dam Site                     4672 km2          

Annual mean flow                                         5682.6 Mcum           

Submergence area                                      24.5 ha

Design Flood                                                SPF 6700m3/sec (For Design)

                                                        PMF 10840m3/sec (For Checking)                    

            Diversion Flood

(1: 25 yr Non monsoon flood)                 725 m3/sec

 

Normal Water Level in Non Monsoon     1232 m.

season at Dam site             

HFL at Dam site                                           1238 m

Normal Water Level in Non Monsoon     1033  m

season at TRT Outlet site   .

HFL at TRT outlet site                                 1040 m

 

 

C.   RESERVOIR:

Full reservoir level                                   E L   1267 m

Maximum water level                                  E L   1269 m (PMF)

Minimum draw down level                          E L   1252.5 m

Gross storage at FRL                                 3.63 Mcum

Storage at MDDL                                        1.16 Mcum

Live storage                                                  2.47 Mcum

Surface Area at FRL                                   24.5 Ha.

 

D.   DIVERSION ARRANGEMENT:

Diversion Tunnel:

Location                                                  Left bank

Length                                                     425 m

Diameter                                                10m, Circular

Design Discharge                                 725m3/sec

Gates                                                      10mx10m, Vertical lift fixed wheel

Invert level at Entry                                 1228m

 

U/S Coffer Dam:

Type                                                         Colcrete

Length                                                      60 m

Height                                                      15 m

Top Elevation                                          EL 1242 m

                             

D/S Coffer Dam:

Type                                                         Rockfill

Length                                                      40 m          

Height                                                       6 m

Top EL.                                                    EL. 1229 m

 

E.   DIVERSION DAM:   

            Type of dam                                                Concrete, gravity dam

Height of dam above deepest                 65 m

Foundation level                                         

            Top of dam                                                         EL 1270 m

            River bed level                                               EL 1225 m

            Foundation level                                            EL 1205 m    

            Length                                                            89.55 M (NOF 28.65 m, OF 60.9 m)          

F.    SPILLING ARRANGEMENT:

Sluices:

Nos.                                                          4

Design Discharge                                8004 m3 /sec

                Size of sluice                                             7.2 m (W) x 15 m (H)

                                                                      

                  Type of gate                                            Radial

                                                                             Stoplog (1 no. 7.2 m x 22.5 m)

            Crest level of sluice                                1233 m

     

Diversion cum Spillway Tunnel:

Diameter                                                 10 m dia, Circular

Invert level at Entry                                  1249 m

Length                                                      100 m

Design Discharge                                   1074 m3/sec

Gate                                                          2+1 no., 4.1 m x 10 m

     (Vertical lift fixed wheel Gate)

 

Spill Tunnel (12m dia):                       

Size                                                          12m dia, Circular

Invert level at Entry                                1228m

Length                                                    205 m

Design Discharge                                  1618 m3/sec

Gate                                                          2+1 no., 4.8 m x 12 m

                                                                  (Vertical lift fixed wheel Gate)

Ogee spillway

No.                                                            1

Type of gate                                            vertical

Size                                                          7 m (H) x 6 m (W)

Design flow                                             310 m3 /sec

Crest EL                                                  EL 1260 m

 

 

 

G.   POWER INTAKE:

Location                                                         Right bank

Nos.                                                                3

Type                                                               Straight intake with bell mouth

Maximum discharge                                               274.63m3//sec

Intake invert level                                         EL 1242.5 m

Size                                                                6 m modified Horse shoe type

Gates                                                              3 + 3 nos. 5.20 m x 6 m

Vertical lift fixed wheel gate

           (Service   gate + emergency gate)

 

          Silt Flushing Tunnel 

(Below Intake)

           

Size of Intake                                                3 nos. of 3mx3m

            Size of SFT   ducts                                      3 nos. of 2mx5m

            Gate                                                                3+3 nos. of 3mx3m

            Design Discharge capacity                        380 cumec

 

H.   DESILTING CHAMBER:

Nos.                                                                3

Size                                                                390 m (L) x 20 m (W)x17.5m (H)

            Particle size to be removed                        0.2 mm & above

            Gates                                                              3 nos.  5.24 m x 6 m (H),

Vertical lift fixed wheel       

            Operation level                                             EL 1270 m

           

        Silt Flushing Tunnel:                                                

            Size                                                                3.6 m x 4.0 m (D shaped)

            Flushing discharge                                     45.8 m3/sec

            Gates                                                              3 nos. 2.5 m x 2.85 m,

(Vertical lift slide Gate)

            Operation level                                             EL 1237 m

 

 

 

 

I.      HEAD RACE TUNNEL:

            Length                                                           13.4 km

            Diameter                                                        8.8 m (1.4 Km Horse shoe by DBM &

                                                                                                12.0 Km Circular by TBM)

            Design discharge                                        228.86 m3/sec

            Velocity                                                          3.56 m/sec

            Bed slope (average)                                    1:121 (before Maina River)

1:321 (After Maina River)

            No. of adits                                                    2

 

 

J.    UPSTREAM SURGESHAFT:

            Type                                                               Restricted Orifice type

            Diameter                                                        15/22 m F 

                                                                                    (15 m F, EL.1165m to1240m)

                                                                                    (22 m F, EL.1240m to 1305 m)

           

Height            (from HRT invert)                            140 m

            Top EL                                                           1305 m

            Orifice level                                                   1165 m

            Orifice diameter                                            1.5 m , 3 nos.

            Tunnel inverts                                              EL 1155 m

 

K.   BUTTERFLY VALVE CHAMBER:

Size                                                                 50 m (L) x 9.8 m (W) x 19 m (H)

Butterfly Valve                                               2 nos., 5.2 m

 

L.    PENSTOCK ASSEMBLY CHAMBER:

Size                                                                 50 m (L)x 9.8 m (W) x 19 m (H)

 

M.   PRESSURE SHAFT:

Nos.                                                                 2 / 4

Type                                                                Circular

Diameter                                                         5.2 m / 3.65 m

Length of each PS                                       310 m / 35 m

Design velocity                                         5.39 m/sec

 

N.   POWER HOUSE:

Type                                                            Underground

Size of P/H cavern                                    146 m x 20.3 m x 50 m

Size of Transformer cavern                      142 m x 16 m x 24.5 m

Nos. of units                                                4

Rated unit capacity                                    111 MW

Installed capacity                                        4 x 111 MW = 444 MW

Gross Head                                                237.0 m

Rated Head                                                212.46 m

Centre line of unit                                       EL 1022.0 m

Service bay level                                        EL 1038 m

Maximum flow through each unit              57.22 m3/sec

Generator:                             

Synchronous speed of Generator            250 rpm

 

Power factor, Generator voltage              0.9, 13.8kV

 

Transformers- Type, Nos., No. of Phases, OFWF, 4, 3, single phase, 46MVA, 13.8/ 420/√3kV. 

Step-up voltage, Capacity                       400kV

Energy generation                                    1813.03 GWh

(On 90% dependability basis) 

O.   D/S SURGE TANK:

Type                                                             Underground

Size                                                             120 m (L) x16 m (W) x 35 m (H)

Maximum Surge level                                1040 m

Minimum Surge level                                 1026.5 m

 

P.   TAIL RACE TUNNEL:

a)  Size                                                         8.8 m f  (Horse shoe)

b) Length                                                      3.07 km

c) Max. TWL                                                1030.0 m 

(With all 4 M/C running)

d) Min. TWL                                                 1028.2 m 

e) TRT invert level                                        EL 1025.0

 

Q.   POTYARD:

a) Type                                                          GIS

b) No. of bays in the Potyard                      8 bays

c) Voltage level                                            420 kV

d) Size of potyard                                        40m x 67 m

 

R.   POWER GENERATION:

a) Firm power                                               51.47 MW                                         

b) Annual Energy                                         1696.31 GWh

c) Load factor (lean flow)                            11.72%

d) Design Energy                                        1674.29 GWh