|
PROJECT LOCATION |
|
State |
Sikkim |
|
District |
West |
|
Stream |
Rathang Chu River |
|
Location of (nearest village) |
Yuksum |
|
Latitude |
270
13” N |
|
Longitude |
880 12” E |
|
|
HYDROLOGY |
|
Catchment area at Dam Site |
372 sq. km |
|
Average Annual precipitation in snow fed catchment |
1200 mm |
|
Average Annual precipitation in rain fed catchment |
2500 mm
|
|
Average Annual Inflow |
2578 mm
|
|
Flood Discharge for River Diversion (~Q25) Non-Monsoon |
125 Cumec |
|
Standard Project Flood Discharge (SPF) (~Q 500) |
1415 Cumec
|
|
Probable
Maximum Flood Discharge (PMF) |
1885 Cumec |
DAM AND
APPURTENANT STRUCTURES |
|
Type |
Concrete Gravity |
|
Length of dam at top |
98.5 m |
|
Spillway Width |
36 m |
|
Spillway Crest Level: |
1130.00 |
|
River Bed Level (Lowest) |
1125.00 m |
|
Minimum Draw Down Level |
1143.00 m |
|
Full Reservoir Level |
1165.00 m |
|
Top level of Dam |
1169.00 m |
|
Pondage above MDDL (Diurnal storage) |
0.46 MCM |
|
Submergence area at FRL (approx) |
4.02 ha |
|
Stretch of Reservoir |
0.46 km |
|
|
Spillway
Gates |
|
Type |
Radial
|
|
No. & Size |
3.0 nos. of 6.0m(w) x 6.5m (H)
|
|
|
|
|
Upstream
Cofferdam |
|
Crest Elevation |
EL 1142 m |
|
Length |
35.8 m |
Downstream Coffer dam |
|
Crest elevation |
El.
1125.00 m |
|
Length |
63.1 m |
Diversion Tunnel |
|
Shape & Size |
D-Shape, 3.6 m |
|
Length |
131.0 m |
|
Invert level at inlet |
EL 1137.0 m |
|
Invert level at outlet |
EL 1122.4 m |
|
|
Intake |
|
Location |
On Left bank, 5.9 m upstream of Dam axis |
|
Size of
opening for trash rack |
16 m x
6.02 m
|
|
Size of
Intake opening |
4.2 m(W)
x 4.4 m(H) |
|
Invert
level of Intake at Entry |
EL.1133.80 m |
|
Design
Discharge |
46.13
Cumec |
|
Velocity
of flow through Trash racks |
0.75
m/sec |
|
Feeder
Tunnel from Intake |
One no.
of 4.4 m Horse Shoe Shaped |
|
Invert
Level of Feeder Tunnel |
EL.1134.40 m |
|
No. Type
& Dimension of Gates |
One,
Vertical lift gate,4.2 mx4.4 m |
|
Trash
Rack Units |
8 panels
of 4.0 m x 3.01m |
|
|
|
HEADRACE TUNNEL-HRT |
|
Shape & Size |
Horse
Shoe, 4.4 m |
|
Length |
2141 m
|
|
Flow Velocity
at Design Discharge |
2.87
m/sec |
|
Design Discharge |
46.13
cumec |
|
Lining Thickness (PCC) |
200 mm to
300 mm |
|
|
|
Adit To
HRT |
|
Location |
Just U/s
of Surge shaft |
|
Slope &
Size |
D-shaped,
4.5 m |
|
Length |
122 m |
|
Level |
El. 1120 m |
|
|
|
SURGE SHAFT |
|
Vertical Shaft |
Restricted Orifice Type
|
|
Internal Diameter |
10 m |
|
Height of shaft |
63.9 m |
|
Concrete lining thickness |
Varying from 300 mm to 600 mm |
|
Lining Type |
RCC Lining |
|
Vertical Lift Gate size |
3.4 m (W)
x3.4 m (H) |
|
Top of Surge shaft |
El. 1188 m |
|
Bottom of Surge shaft |
El. 1124.1 m |
|
Max. Surge level |
El. 1185 m |
|
Min. Surge level |
El.
1127.80 m |
|
Orifice dia. |
2.25 m |
|
|
|
Adit to HRT & Surge Shaft Bottom |
Shape & Size
|
D-Shaped, 4.5m
|
|
Entry Sill Level |
EL1120.70
m |
|
Length |
77 m |
|
|
|
PRESSURE
SHAFT PENSTOCK |
|
Total Length upto Bifurcation |
760 m |
|
Number of
anchor blocks |
3 |
|
Diameter
after Bifurcation |
2.4 m |
|
Branch
penstock length |
23.1 m &
32.6 m |
|
Steel
liner thickness |
16 mm to
36 mm |
|
Grade of
Steel lining |
ASTM 537
Class-II |
|
|
POWERHOUSE |
|
Type |
Surface Powerhouse |
|
Size |
48 m (L)
x18 m (W)x44 m(H) |
|
Number of units |
Two (2) |
|
Rated Discharge per unit |
23.06
Cumec |
|
Turbine Speed |
500 rpm |
|
Min. Tail Water Level |
EL912.60
m |
|
Normal Tail Water Level |
EL 915.00
m |
|
Max. Tail
Water Level |
EL 924.00
m |
|
Gross Head (monsoon period) |
EL 250 m |
|
Net Rated Head |
233.98 m |
|
Installed Capacity |
2x 49.5
MW |
|
Annual
Plant Load Factor (90 % year) |
0.473 |
|
Inlet Valve Type |
Spherical Valve |
|
Number |
2 |
|
Inlet
Valve diameter |
1.8 m |
|
Turbine Axis Elevation |
EL 904.60
m |
|
Generator type
|
Suspended |
|
Nominal Speed |
500 rpm |
|
Voltage / Frequency |
11 kV /50
Hz |
|
Power Factor |
0.9 |
|
Draft
Tube Gates, No & Size |
Two,
4.71 m (W) x 3.764 (H) |
|
|
|
TRANSFORMER |
|
Type and
capacity |
Single phase,11KV/220KV, 21.0 MVA, OFWF |
|
Location |
Outdoor on left bank of the river |
|
Number
|
7 |
|
|
|
|
TRAILRACE TUNNEL |
|
Type |
Open Channel
|
|
Length
(Including tail pool) |
78.5 m |
|
Bed Slope (Tail
Pool) |
1:4 |
|
Nominal
Discharge |
50.76 Cumec |
|
River Bed
Elevation |
EL.686.00 m |
|
|
|
SWITCHYARD |
|
Type |
Twin box,
cut and cover tunnel |
|
Location
of Switchyard |
Downstream of PH on right bank at El. 940.00 m |
|
Bus bar
Voltage |
220
KV |
|
|
TRANSMISSION
LINE |
|
Type |
Switch
yard to pooling station |
|
Single
Circuit 220 KV |
|
|
|
|
|
ESTIMATED COST |
|
Civil Works (Including gates & hoists) |
Rs.
226.61 Crore |
|
E&M Works
(Including cost of Transmission line to pooling station) |
Rs.
167.83 Crore |
|
Total Basic
Cost |
Rs.
394.44 Crore |
|
Escalation
during construction |
Rs.
34.76 Crore |
|
Interest
during Construction |
Rs.
59.93 Crore |
|
Total
(Generation Works) |
Rs.
489.13 Crore |
|
Cost per MW
installed |
Rs.
4.91 Crore |
|
|
|
POWER BENEFITS |
|
Design
Energy Generation (90% Dependable Year with 95%
machine availability) |
410.24
GWh |
|
Annual
Energy Generation in (90% Dependable Year) |
424.09
GWh |
Annual
Energy Generation including additional energy utilizing
high inflow (90% Dependable Year)
|
444.63
GWh |
|
Design
Energy Generation (90% Dependable Year with 95% machine
availability) including additional energy utilizing high
inflow |
429.75
GWh |
|
Annual
Energy Generation including additional energy utilizing
high inflow (50% Dependable Year) |
478.77
GWh |
|
|
|
FINANCIAL ASPECTS |
|
Levelized
Tariff for Design Energy at
90%Dependable Year |
Rs 2.15
/kWh |
|
FIRR at
Rs 2.22 /kWh tariff (35 years |
8.96 % |
|
FIRR at
Rs 2.5 /kWh tariff (35 years) |
11.09 % |
|
CONSTRUCTION PERIOD |
|
Construction
Period in months (excluding pre-construction works) |
30 months |
|
|
|
|
| |
| |
