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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)

                                                            PMF10840m3/sec(ForChecking)                    

            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 

                                                                                   (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  (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                                                74.69 MW                                         

b) Annual Energy                                           1696.29 GWh

c) Load factor (lean flow)                              16.82%

d) Design Energy                                          1674.27 GWh