Salient Features
ARUN-3 HEP ( 900 MW ) ,NEPAL SALIENT FEATURES |
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1. |
Location |
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River |
Arun,a tributary of Kosi River in Eastern Nepal |
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District |
Sankhuwasabha |
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Nearest Railway Head |
Jogbani, Bihar ( B. Gauge ) about 300 km from project site |
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Nearest Airport |
Tumlingtar, Nepal 70 km |
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2. |
Hydrology |
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Catchment Area at Diversion Site |
26747 sq.km |
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Design Flood |
PMF-8880 cumec GLOF-6830 cumec |
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3. |
Reservoir |
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Submergence area at FRL |
66.3 Ha |
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Reservoir Capacity/ Gross storage at FRL |
13.94 MCM |
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Full Reservoir Level (FRL) |
El 845 m |
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Max. Water Level (MWL) |
El 847.73 m |
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MDDL |
El 835 m |
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Inactive Storage (below MDDL) |
8.29 MCM |
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Active storage /Peaking volume |
5.65 MCM |
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4. |
Diversion Tunnel |
429 m long, 11 m diameter to divert 1300 cumec |
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5. |
Dam |
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Type of Dam |
Concrete Gravity Dam |
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Dam top Level |
El.849 m |
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River bed Level |
El. 790 m |
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Dam Height above River bed |
59 m |
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Deepest Foundation Level |
El.769 m |
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Height above deepest Foundation Level |
80 m |
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Length of Dam at Top |
233 m |
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Top Width of Dam |
7 m |
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6. |
Upstream Coffer Dam |
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Type |
Colcrete dam |
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Top level |
El 818.00 m |
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Height |
27 m |
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Length |
108 m |
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7. |
Downstream Coffer Dam |
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Type |
Rock fill dam |
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Top level |
El 794.25 m |
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Height |
5.25 m |
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Length |
70.64 m |
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8. |
Spillway |
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Design Flood |
PMF-8880 cumec GLOF -6830 cumec |
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Energy Dissipation System |
Trajectory Bucket type |
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i)Sluice spillway No. Size ii)Overflow spillway No. Size |
5 9.0 m (W)X 14.85 m (H)
1 4.0 m (W)X 3.0 m (H) |
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Crest Level |
El 795 m-Sluice Spillway El 842 m-Overflow Spillway |
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9. |
Power Intake |
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No. & Type |
2 Nos., Straight intake with bell mouth |
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Invert Level |
El.819m |
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Top Level |
El.849m |
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10. |
Intake Tunnels |
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No. & Type |
2 Nos., 7 m diameter, horse-shoe shaped |
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Length |
231 m each |
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C.L. of Intake Tunnel |
El 822 m |
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11. |
Head Race Tunnel |
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Shape & Size |
Horse-shoe, 9.5 m diameter |
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Length of Tunnel |
11837 m |
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Design Discharge |
344.68 cum / sec |
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No. of Adits& size |
4 Nos.,7 m X 7 m D - shaped |
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ADIT |
ADIT LENGTH |
RD OF HRT |
DISTANCE BETWEEN ADITS |
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1 |
504 m |
790 m |
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2 |
683 m |
5156 m |
4366 m |
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3 |
387 m |
8272 m |
3116 m |
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4 |
333 m |
11786 m |
3514 m |
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12. |
Surge Shaft |
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Size & shape |
Open to sky,Restricted Orifice 1No.,24.0m diameter, Circular |
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Height |
155.00 m |
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Top Level |
El 946.00 m |
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Gates,No.& Size |
2 Nos., 5.5m ( W )X 5.5m (H ) |
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13. |
Butterfly Valve Chamber- Underground |
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Size |
83.05m (L) X 12 m(W) X 21 m(H) |
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Butterfly Valve |
2 nos, 5.5 m diameter |
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14. |
Pressure Shaft |
Underground, 2 Nos. |
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Type & Size |
Circular,each 5.5 m dia bifurcating into two nos of 4.0 m diameter to feed four units |
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Length of pressure shafts 1 and 2
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Pressure shaft-I |
432 m |
Pressure shaft-2 |
404 m |
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Branch 1 |
70 m |
Branch 3 |
70 m |
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Branch 2 |
58 m |
Branch 4 |
58 m |
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15. |
Power House Complex |
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Type |
Underground on left bank |
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P/H Cavern |
179.50 m(L)X22.5 m (W)X49.5 m (H) |
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Design Head ( net ) |
286.21 m |
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Gross Head |
307.67 m |
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Turbine |
4 Nos., Vertical Francis turbine, 225 MW each |
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Rated speed of Turbine |
250 rpm |
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Generation voltage |
15.75 kV |
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Service Bay Floor Level |
El. 539.00m |
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Generator Floor Level |
El. 534.00 m |
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Turbine Floor Level |
El. 529.00 m |
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Distribution Centre Line Level |
El. 525.00 m |
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MIV Floor Level |
El.520.50 m |
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Maximum Tail Water Level |
El. 536.46 m |
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Transformer |
Single phase, 12+1 (Spare), 92 MVA 15.75 kV/420/Root3 kV |
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16. |
Transformer Hall |
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Size |
146.14 m (L)X 16 m (W)x 23 m ( H ) |
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Transformer Hall Floor Level |
El. 552 m |
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Design Discharge per unit |
86.17 Cumec |
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Design Energy in a 90 % dependable year |
3924.03 MU |
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Annual Load Factor |
50.98 % |
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Weighted average efficiency of TG Set |
93 % |
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17. |
Tail Race Tunnel |
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No., Type & Size |
1 No., Horse-shoe shaped, 10.00 m diameter, 151.97 m long |
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18. |
Switchyard |
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Elevation |
El 557 m |
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Size |
160 m (L)X 80 m (W) |
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