Saturday, April 9, 2011



               The Idukki Dam, (Kerala,India) is currently the 14th largest arch dam in Asia, at 555 feet in height. The dam stands between the two mountains - Kuravanmala(839 feet) and Kurathimala(925 feet). It was constructed and is owned by the Kerala State Electricity Board.

This prestigeous project of our nation is situated in Idukki District and its underground Power House is located at Moolamattom which is about 19 kms from Thodupuzha. Idukki Dam is 43 kms away from Moolamattom. This dam was constructed along with two other dams at Cheruthony and Kulamavu. Together, the three dams have created an artificial lake that is 60 km² wide. The Government of Canada aided in the building of the dam with long term loans and grants.


HISTORY 
             The possibility of Hydroelecric development at Idukki was first conceived in 1919. As per history Shri Kolumban, the head of 'Araya' race during 1922 showed the way, to the Malankara Estate Superintendent and his friend Thomas, who were on hunting spree in the forest, the spot of present Arch Dam. He told them of the legend of Kuravan and Kurathi Hills. The mind of Thomas was stirred by the sight of water flow between the mountains and his idea made the dream true of Idukki Arch Dam. Sri. W.J.John of Malankara Estate submitted a report to the Government of Travancore in 1932 on the possiability of constructing a dam at Idukki for Power Generation.          




Structure of Idukki Dam



Location                 :  Idukki , Kerala , India
Completed in         :   1976
Structural Type     :   Arch Dam
                                    Concrete double, curvature parabolic, thin arcConstructed by      :   Hindustan Construction Company , Mumbai , India

                                    (Idukki Dam is an Indo-Canadian Project) 
Technical Details

Diamensions:
      Height             : 167.68m
     Creast Length  : 365.85m
     Creast Width    : 7.62   m
     Base Width       : 19.81m    

Construction material used is concrete.
Concrete volume :                  478 000 m3  





Hydroelectric Project


Total drainage area 250.7 square. miles (649.3 square kilometres)
Full Reservoir Level (FRL) +2403 feet (732.62 m)
Maximum Water Level (MWL) +2408.5 feet (734.3 m)
Gross Storage of FRL 70500 million cubic feet (1996.3 million cubic metres)
Dead storage
below Minimum Draw Down Level (MDDL) of +2280 ft.
18957 million cubic feet (536.79 million cubic metres)
Live storage 51543 million cubic feet (1459.5 million cubic metres)
Water Spread area 23.1 sqare miles (59.83 sq. km)
Installed Capacity 780 Mega Watt (MW)
Firm Power Potential



 Other Details



Idukki 





Cheruthony Dam
Type Straight gravity concrete
Height above deepest foundation 453.4 feet (138.2 m)
Length at top 2135 feet (650.9 m)
Spillway length 240 feet (73.2 m)
No. of gates (radial) 5 nos. 40 feet x 34 feet (12.19 m x 10.36 m)


  Kulamavu Dam 

 Type Gravity masonry
 Intake sill level 2245 feet (684.45 m)

WATER CONDUCTOR SYSTEM

Type Masonry, straight gravity
Height above deepest foundation 328 feet (99.97 m)
Length at top 1263 feet (384.96 m)

POWER TUNNEL

Section 23 inch dia (7.01 m) finished horse shoe concrete lined (18 inches ie. 45.7 cm minimum 22 inches average i.e. 55.9 cm)
Length 6652 feet (2027.53 m)

SURGE SHAFT

Type Restricted orifice type with inclined shaft completely underground.
Size 28 feet 6 inches (8.69 m) dia. finished 250 feet (76.25 m) long and inclined at 53°.

PRESSURE SHAFT

No.of pressure shafts (under ground) 2 nos. (steel lined)
Length 3259 feet (993.34 m), 3136 feet (955.85 m)
Butterfly valves One in each pressure shaft located 300 feet away from surge shaft

UNDERGROUND POWER HOUSE

No. of machines 6
Capacity of each 130 MW, 144 MVA
Power Factor 0.9
Size of power house 463 feet (141.1 m) length.
65 feet (19.8 m) width
113.5 feet (34.6 m) height
Turbines 6 nos. Vertical Pelton wheel type
Normal Speed 375 rpm
Runaway Speed 625 rpm

 
TAIL RACE TUNNEL
Length of tunnel 4000 feet (1220 m)
Tunnel section 26 feet x 23 feet (7.29 m x 7m)
'D' shaped, finished with full section lining.
26 feet x 24 feet (7.92 m x 7.32 m) in weak zones
'D' shaped, finished with lining only for floor and sides.
Length of open channel 852 feet (259.7 m)

SWITCH YARD
Switch yard area 821 feet x 282 feet (250.24 m x 85.95 m)
Transmission lines One double circuit line to Kalamassery one single circuit line to Tamil Nadu One single circuit line to Pallom and three feeder bays forfuture.