Hydrology
Catchment Area : 26747 Km2
90% Dependable year flows : 203 m3/s
Annual average flow : 296 m3/s
Glacier lake outburst flood at dam site : 4000 m3/s
Maximum flood ( 1:10,000) : 5543 m3/s
Probable Maximum Flood (PMF) : 7900 m3/s
Pondage fetch along the river from dam site : 4Km ( Approx.)
Design discharge for generation : 342.23 m3/s
Max. Gross Head : 303.8 m
Max. Net Head at full load : 285.98 m
Installed Capacity : 900 MW
Annual Energy : 4033.52MU
Diversion tunnel
Location : Right Bank
Number and Types : Circular Shaped
Length : 466.0m
Diameter : 11.0m Dia
Design discharge for diversion : 1300 m3/s
Gates : 2 X (5.5X11m)vertical lift fixed wheel
Dam
Type : Concrete gravity dam
Height above deepest Foundation Level: 68 m (EL.781 )
Top of Dam : EL 849 m
Length of Dam : 165.00 m
FRL : EL 845 m
Spillways
Sluice Spillway No. : 6 ( 9.0 m W X 12.5 m H )
Crest Level : EL 808.0 M
Overflow Spillway No. : 1 ( 5.0m W X 5.0 m H)
Crest level : EL 840.0m
Intakes
Number & Type : 4 No’s straight intake with Bell mouth
No of Gates( Size ) : 04 nos., 6.0m dia. Cir &01 (4.8mX6.0m) Moving
Desilting Caverns Emergency Gate
Number & Type : 4 No’s underground
Particle size to be removed : 0.2mm & above (Suspended Sediment)
Cavern dimensions (W/H/L) : 19/24/420m
Flushing tunnel : 4.5m(w)/ 3.6m(h)
Headrace Tunnel
Number & Type : One conc. lined circular pressure tunnel
Length : 11.74 Km
Finished Dia : 9.5 m
Surge Tank- Underground
Number & Type : One, Restricted orifice type
Shaft diameter : 24.00m
Height : 110.00m
Max. Upsurge/Min down surge : EL 863.35/ 826.79
Butterfly Valve Chamber
Type : Underground
Cavern Size : 12/ 21/ 94m
Butterfly Valves : 2 nos, 5.5m dia.
Pressure shaft & U/s manifold
Number & Type : Two vertical pressure shafts dia 5.5m each Bifurcation dia 3.2m
Power House Cavern
Dimension ( W/H/L) : 21/43/217m
No. of generating units : Francis 4 x 225 MW
Centre line of Turbine : EL 525.00 m
Clearances /Events of the project
LAND
A Sum of NPR 45.14 Crores has been paid to GON initially against expenditure made on Arun 3 HPP after signing of MOU, which includes the compensation paid on account of acquisition of land at different locations.
Total land in possession of project=8120ROPopani(4129020sq.m) (5161.275 bighas)
Infra structure works (Dam/Power House)=14-6Ropani(7435 sq.m) (9.294 Bighas)
After complete survey and marking on cadastral maps, the deptt of Survey and Land revenue at Khadbari are in the process of transferring the lal purjas ( Tatima ) in the name of GON, before handing over this land to SJVNL on lease or till project remains in possession of SJVN. Almost 60% of the job completed as informed by local administration.