VISHNUGAD PIPALKOTI H.E. PROJECT

  • The Vishnugad Pipalkoti Hydro Electric Project (4 x 111 MW) is located on Alaknanda River, a major tributary of river Ganga, in district Chamoli in the state of Uttarakhand. The nearest railhead is Rishikesh (225 Km) and the nearest Airport is Jolly Grant,  Dehradun (240 Km). The project is approachable by an all weather road (National Highway No. 58).

    The project envisages a run of river scheme with construction of a diversion dam of 65 m height across Alaknanda River for power generation harnessing a gross head of 237 m. The reservoir will have a gross storage capacity of 3.63 Million cum, out of which 2.47 Million CuM shall be live storage. A diversion cum spill tunnel of 10 m dia. shall divert the discharge of 725 m3/Sec during the construction period. The water conductor system comprises of 03 nos. intake tunnels, 03 nos. Underground sedimentation chambers, a head race tunnel, a surge shaft, 02 nos. pressure shafts bifurcating into 4 No Penstocks. The powerhouse comprises of two separate underground caverns for installation of turbines and transformers.
  • SALIENT FEATURES

    A.   LOCATION:
    State                                                               Uttarakhand
    Distt.                                                               Chamoli
    River                                                               Alaknanda
    Dam site                                                        Near Village Helong
    (E – 7929’ 30”) (N - 300   30’ 50”)
    P H site (underground)                               Near Village Hat     
    (E – 79 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
     
  • PROJECT FUNDING

    Construction of the project is proposed to be funded with a Debt: Equity ratio of 70:30. The Equity portion; 50% is to be shared by THDCIL and remaining 50 % is to be shared by GOI and GOUP in the ratio of 75: 25 respectively.

    For the funding of the debt portion (70 %) of the project, loan agreement for US $ 648 million has been signed with World Bank on 10th Aug-11. The loan includes US $ 10 million for Capacity Building and Institutional Strengthening (CBIS).The loan has become effective from 7th Nov-11 with tenure of 29 years. 
  • PROJECT BENEFITS
    • Capacity addition of 444 MW in the Northern Region, reducing peaking power shortage in the region.
    • Annual Design Energy of 1674 MU (90% dependable year).
    • Integrated Development of Chamoli / Garhwal region in the areas of employment, communication, education, health, tourism, development of Flora & Fauna etc.
    • Out of 13% free power to the home state Uttarakhand, 1% shall be utilized for contribution towards local area development.




Updated on : 24/04/2018