GOHANA TAL

  • Gohana Tal Hydroelectric Project is located on river Birahi Ganga, a tributary of Alaknanda River in Chamoli district of Uttarakhand. The site is approachable from Rishikesh by an all weather road about 211 km up to Gopeshwar and further 26 km up to barrage site by a proposed hill road. The nearest rail head is Rishikesh and nearest airport is Jolly Grant, Dehradun.
     
    The Project is a run-of-river scheme, harnessing a head of about 500.0 m. As per the Feasibility Report, the proposed project involves construction of 46.0m long Barrage. The water conductor system consists of 1 no. gated Power intake of size 3.0m x 3.5m each, 1 no. De-silting Chamber of size 120 m x 7 m x 8 m. The de-silting chambers converges, after a smooth transition to a 3m X 3.5m size, 9.69 km long, D shaped, head race tunnel. The head race tunnel ends in a 6m dia. and 65m high  surge shaft. Further, 1/4 nos. Pressure Shaft, 1.7m/0.85 dia. is entering into the machines in the surface power house of size 90.00 m x 21.5 m x 35.0 m. A Tail race channel of 2.0 m X 5.0 m rectangular shape and 80 m length, discharges the water back into the river.
     
    The project would afford an annual energy generation of 180.88 GWh in a 90% dependable year. The project is estimated to cost `488.52 crores including IDC at December, 2012 price level. The first year and levellised tariff from the project would be ` 6.50/ KWh and ` 5.65/ KWh respectively.
  • LOCATION
    State                                                               Uttarakhand
    District                                                            Chamoli
    River                                                               Birahi Ganga
    Nearest Airport                                             Dehradun
    Nearest Rail Head                                       Rishikesh
     
    Barrage                                                          1.5 km d/s of confluence of Pui Gadhera joining river Birahi Ganga from Right Bank
    Latitude                                                          3002340”N
    Longitude                                                      79030’43”E
     
    Power House                                                400 m u/s of barrage of Birahi HE Project
    Latitude                                                          3002340”N
    Longitude                                                      79024’38”E
     
    HYDROLOGY
     
    Catchment area at dam site                       218.95 sq km
    Design Flood                                                1005 m3/sec (SPF for Design)
    Diversion Flood                                            73 m3/sec
    (1:25 yr Non monsoon flood)
     
    RESERVOIR
     
    Full Reservoir Level (FRL)                         El 1619.0 m
    Maximum Water Level (MWL)                    El 1619.0 m
    Minimum Drawdown Level (MDDL)         El 1617.0 m
    Gross storage at FRL                                  0.98 M cum
    Live storage                                                  0.37 M cum
    Area under Submergence at FRL            20.95 ha
     
    DIVERSION STRUCTURE
     
    a)    Barrage
    Type                                                   Barrage with breast wall
    Length                                               46.0 m
    Top of Barrage                                  El 1622.0 m
    Total number of bays                      5
    No. of spillway bays                                    4 Nos. (6.0 m x 6 m each)
    No. of Under sluices bays              1 Nos. ( 6.0 m x 6 m each)
    Crest Level                                       
    (i)            Spillway bay                            El 1609.0 m
    (ii)          Under sluice bay                    El 1607.0 m
    Design Flood                                                1005 cumecs
     
    b)   Overflow section
    No. of bays                                        1
    Spillway size                                     4m x 2m
    Spillway crest level                          El 1617.0 m
     
    c)    Non Over flow section
    Type                                                   Earth and rockfill Embankment
    Length                                               154 m
    Top of structure                                El 1622.0 m
    U/S slope                                           2.5:1
    D/S slope                                           2.25:1
     
    INTAKE
    Number                                                          1
    Invert level                                                     El 1611.0 m
    Size of gate opening                                   3.0 m x 3.5 m
    Trash rack                                                     4.0 m x 5.3 m
    Design discharge                                        13.7 cumecs
     
    INTAKE TUNNEL
    Number                                                          1
    Type                                                               D Shape
    Size                                                                3.0 m x 3.5 m
    Length                                                           835 m
    Design discharge                                        13.7 cumecs
     
    DESILTING CHAMBER
    Number                                                          1
    Size                                                                120.0m x 7.0 m x 8.0 m
    Design discharge                                        13.7 cumecs
    Particle size to be removed                        0.2 mm & above
     
    SILT FLUSHING TUNNEL
    Number                                                          1
    Size                                                                2 m x 2.2 m
    Shape                                                            D Shape
    Length                                                           668 m
    Design discharge                                        2.28 Cumecs
    Size of the channel                                     0.9 m x 0.75 m
    HEAD RACE TUNNEL
     
    Number                                                          1
    Size                                                                3 m x 3.5 m
    Shape                                                            D Shape
    Length                                                           9.69 km
    Design discharge                                        11.4 cumecs
     
    SURGE SHAFT
     
    Number                                                          1
    Type                                                               Simple surge Tank
    Size                                                                6.0 m diameter
    Height                                                            65.0 m
    Top EL                                                           EL 1645 m
    Tunnel invert                                                EL 1580 m
    Maximum surge level                                  1638.0 m
    Minimum surge level                                   1597.0 m
     
    PRESSURE SHAFT
     
    Number                                                          1/4
    Size                                                                1.7 m / 0.85 m diameter
    Length                                                           915.0 m
     
    POWER HOUSE
     
    Type                                                               Surface
    Installed capacity                                         50 MW
    Number of units                                           4 of 12.5 MW
    Power house size                                        90.0 m x 21.5 m x 35.0 m
    Type of turbine                                             Vertical axis Pelton
    C.L. of turbine                                               El 1123.0 m
    Rated Head                                                   484.68 m
     
    TAIL RACE CHANNEL
     
    TYPE                                                              Rectangular
    Size                                                                2m x 5m
    Length                                                           80.0 m
    Design Discharge                                        11.4 cumecs
    River Bed Level                                            El 1119.0 m
    Minimum TWL                                              El 1119.3 m
    Maximum TWL                                             El 1121.6 m
    SWITCHYARD
     
    Type                                                               surface
    Size                                                                65 m x 110.0 m
     
    POWER GENERATION
     
    Installed capacity                                         50 MW (4x12.5 MW)
    Annual energy generation
    i)             90% dependable year                  180.88 GWh
    ii)            Energy in 90% year
    on 95% availability                    176.56 GWh
     
    COST ESTIMATES & FINANCIAL ASPECT (Rs. Crores)
     
    Civil Works                                                    296.26
    Electro Mechanical Works                         117.41
    Sub Total                                                       413.67
    Interest During Construction                     74.85
    Total                                                               488.52
     
    Tariff
     
    Tariff for first year                                         Rs. 6.50 / kwh
    Levellised Tariff                                            Rs. 5.65 / kwh
     
    CONSTRUCTION PERIOD                      4.5 YEARS
     
     
     




Updated on : 19/02/2018