PROJECT KEY SALIENT FEATURES

A. Main Dam and Reservoir

(A) Dam, Reservoir, Hydrology, Sedimentology, Spillways, Diversion and Outlet Structures

Type of Dam	Concrete Face Rockfill Dam (CFRD)
Dam Height (on foundation)	220 m
Dam Body Volume	26.7 Mm³
Dam Crest Elevation	648.0 masl
Parapet Wall Top Elevation	649.5 masl
Dam Crest Length	630.0 m
Maximum Normal Water Level (Max. NWL)	640.0 masl
Minimum Normal Water Level (Min. NWL)	530.0 masl
Total Storage Capacity	1,581 Mm³
Live Storage	1,342 Mm³
Dead Storage	239 Mm³

B. Hydrology

Catchment Area (at dam site)	3,857 km²
Dudhkoshi River Average Flow	209 m³/s
Construction Flood (50-year return period)	3,892 m³/s
Design Flood (10,000-year return period)	9,027 m³/s
Probable Maximum Flood (PMF)	12,638 m³/s

C. Sedimentology

Total Sediment Annual Yield	8.82 Mm³/year (15 Mt/year)
Total Sediment Volume after 50 years	441 Mm³
Dead Storage Loss after 50 years	239 Mm³ (100%)
Active Storage Loss after 50 years	202 Mm³ (15%)
Average Annual Energy with Sedimentation (50 years)	3,331 GWh
Average Dry Season Energy with Sedimentation (50 years)	1,204 GWh
Average Wet Season Energy with Sedimentation (50 years)	2,127 GWh

D. Main Spillway

(i) Gated Spillway

Type	Concrete gated
Design Discharge (10,000 year return period)	9,027 m³/s
Sill Elevation	624.0 masl
Crest Length	60.0 m
Radial Gates	4 nos, 15.0 m x 20.6 m (width x height)

(ii) Labyrinth Weir

Type	Labyrinth Overflow
Design Discharge	2,250 m³/s
Crest Elevation	640.5 masl
Length	56.55 m

(e) Auxiliary/Emergency Spillway

(i) Labyrinth Weir
Type	Labyrinth Overflow
Design Discharge	3,700 m³/s
Crest Elevation	644.0 masl
Length	154.5 m
(ii) Embankment Dam
Type	Embankment Fuse Dam
Design Discharge	7,800 m³/s
Crest Elevation	647.3 masl
Bottom Elevation	637.0 masl
Length	154.5 m

F. Diversion Tunnels (DT)

Type and Number	Horseshoe-shaped, 2 nos
Diameter (Excavation)	13.9 m (Finished Dia. 12 m)
Lengths	DT1 = 1,115.2 m DT2 = 1,289.6 m
Total Design Flow	3,892 m³/s (50-year return period)

G. Bottom Outlet (BO)
Type and Number	Horseshoe-shaped, 1 no (one of the Diversion Tunnels will serve as BO during operation)
Diameter (Excavation)	13.9 m
Maximum Discharge	2,400 m³/s (120 m gross head)
H. Low Level Outlet (LLO)
Type and Number	Horseshoe-shaped, 1 no
Diameter (Excavation)	9.6 m
Length	929.3 m
Maximum Discharge	1,000 m³/s (120 m gross head)
I. Middle Level Outlet (MLO)
Type and Number	Horseshoe-shaped, 1 no
Diameter (Excavation)	10.5 m and 13.2 m
Length	695.0 m
Maximum Discharge	1,000 m³/s (90 m gross head)

(B) Main Powerhouse

(a) Headrace Tunnel
Type	Circular shaped Concrete Lined
Diameter (Excavation)	9.32 m (with TBM), Finished Dia. 8.3 m
Length	13.2 km
Design Discharge at Rated Head	224.4 m³/s
(b) Surge Shaft
Type and Number	Circular, 1 no
Diameter (Excavation)	20 m
Height	221 m
(c) Steel Penstock
Type and Number	Circular, 1 no
Diameter (Internal)	6.7 m (3.2 m Dia. in bifurcation)
Length	528.0 m
(d) Vertical Penstock Shaft
Type and Number	Circular, 1 no
Diameter (Excavation)	8.5 m
Length	180.0 m
(e) Powerhouse
Type	Underground Powerhouse
Capacity	600 MW (4 x 150 MW)
Turbine	Francis (Vertical Axis)
Turbine Rated Head	294 m

(C) Dam Toe Powerhouse

(a) Headrace Tunnel
Type	D-Shaped, Concrete Lined
Diameter (Excavation)	8.0 m x 8.0 m
Length	880 m
Design Discharge at Rated Head	40 m³/s
(b) Surge Shaft
Number	Circular, 1 no
Diameter	7.0 m
Height	140.15 m
(c) Steel Penstock
Type and Number	Circular, 1 no
Diameter (Internal)	2.8 m
Length	186.5 m
(d) Vertical Penstock Shaft
Type and Number	Circular, 1 no
Diameter (Excavation)	3.6 m
Length	82.5 m
(e) Powerhouse
Type	Underground
Capacity	70 MW (2 x 35 MW)
Turbine	Francis (Vertical Axis)
Turbine Rated Head	182 m

C. Dam Toe Powerhouse

(a) Headrace Tunnel
Type	D-Shaped, Concrete Lined
Diameter (Excavation)	8.0 m x 8.0 m
Length	880 m
Design Discharge at Rated Head	40 m³/s
(b) Surge Shaft
Number	Circular, 1 no
Diameter	7.0 m
Height	140.15 m
(c) Steel Penstock
Type and Number	Circular, 1 no
Diameter (Internal)	2.8 m
Length	186.5 m
(d) Vertical Penstock Shaft
Type and Number	Circular, 1 no
Diameter (Excavation)	3.6 m
Length	82.5 m
(e) Powerhouse
Type	Underground
Capacity	70 MW (2 x 35 MW)
Turbine	Francis (Vertical Axis)
Turbine Rated Head	182 m

(D) Transmission Line and Sub-Stations

(a) Transmission Lines
Type and Voltage	Double Circuit, 400 kV
Conductor	ACSR Moose (Quad bundle per phase)
Length from Main Powerhouse substation (Dhitung Substation) to Dhalkebar substation	82 km
Length from Dam Toe substation to Bhadaure substation – LILO	1.6 km
(b) Substation / Switchyard
Number	3 nos
Location	One next to Main Powerhouse and the other two are located next to Dam Toe Powerhouse

(E) Energy and Implementation Plan

(a) Energy Production
Average Annual Energy Production	3,377 GWh
Average Dry Season Energy Production	1,252 GWh
Average Wet Season Energy Production	2,125 GWh
(b) Project Implementation
Construction Period	7 years