Status of Construction of Project

 

Component Completed
Diversion Tunnel
U/S and D/S Coffer Dam
Excavation at Right Abutment of Dam
Intake Excavation 
Adit to Desilting Chamber
Adit to downstream Gate Operation Chamber
Upstream 6.5 m heading of Desilting Chamber-2 
Excavation of Desilting Chamber-2 u/s Transition
Upstream 6.5 m heading of Desilting Chamber- 1 
All the HRT Adits 
Main Access Tunnel (MAT)
Cable and Ventilation Tunnel (CVT)
Adit to Tail Race Tunnel (TRT)
Adit to Bottom of Pressure Shaft (PS)
Adit to Butterfly Valve Chamber (BVC)
Power House Crown Excavation
U/S and D/S of Bottom Horizontal Pressure Tunnel (BHPT)
Transformer Crown Excavation
Unit Pressure Tunnels -1 & 2
TRT – u/s of Adit and Unit TRT -2

 

Work under -progress as of April 30, 2019

Component Total Quantity Status as on April 30, 2019
Headworks
Excavation at Left Abutment of Dam completed upto El. 2262 m as on April 30, 2019. From El. 2317 m to El. 2253 m Excavation from El. 2262.00 m to El. 2253 m ongoing
Plunge pool excavation of 8,196 cum (45 % of total volume) has been completed. 18,618 cum  8,196 cum
Silt Flushing Tunnel Excavation 341.44 m 187.80 m
Desilting Chamber -1 d/s 6.5 m heading 60 m 32.30 m
Desilting Chamber -2 d/s 6.5 m heading 60.00 m 31.50 m
Desilting Chamber -1 u/s Transition 17.50 m 8.50 m
U/S unit Feeder Tunnel-2 (3.5 m x 4.5 m) 65.09 m 14.20 m
HRT
Face 1 1093.21 m 371.60 m
Face 2 1356.28 m 476.40 m
Face 3 1122.80 m 648.40 m
Face 4 1162.13 m 456.20 m
Face 5 1332.76 m 966.60 m
Face 6 1438.43 m 610.00 m
Face 7 1357.67 m 321.00 m
Face 8 1309.11 m 356.90 m
Face 9 1496.46 m 149.30 m
Face 10 329.65 m 122.00 m
Total length  11,998.50 m 4,478.40 m
Power House Complex
Power House Cavern- Bench Excavation form El. 1777 m to El. 1746 m Benching at service bay in progress (El. 1763 to El. 1761.9 m)
Transformer Cavern- Bench  Excavation El 1781 m to El. 1762 m Benching up to El. 1778 m
Adit to Surge Shaft Top 397.00 m 277.50 m
Adit to Pressure Assembly Chamber (PAC) 108.00 m 65.20 m
Inclined Pressure Shaft Upper Limb Pilot Hole Excavation 307.00 m 219.00 m
Inclined Pressure Shaft Lower Limb Pilot Hole Excavation 307.00 m 44.00 m
TRT- d/s of Adit 404.00 m 194.20 m
Connecting Tunnel 40.00 m 36.30 m
Unit TRT -1 87.00 m 73.50 m
Top Horizontal Pressure Tunnel (THPT)  d/s of BVC to Inclined PS 27.00 m 20.00 m
THPT u/s of BVC to Surge Shaft  160.00 m 36.80 m
Escape Tunnel 40.00 m 7.30 m
Bus Duct-1 40.00 m 13.00 m
Bus Duct-2 40.00 m 10.00 m

 

The progress of various components of the project till April 30, 2019 are as provided below:

2. Main Contract Package, MP-1(Civil & Hydro-Mechanical Works)

A. Head Works

The excavation at Right bank stands completed. The excavation on the left bank has reached at El. 2262.00 m. The adverse geology encountered at Left Bank of Dam site led to relocation of Dam axis and marked increase in excavation volume. Excavation for Intake has been completed.

The plunge pool excavation of 8,196 m3 (45 % of total volume) has been completed. The excavation works of Silt Flushing Tunnel was also undertaken and as of April 30, 2019, a tunnel length of 187.80 m out of total 341.44 m stands completed.

Excavation of Desilting Chamber 1 & 2 has started. Desilting Chamber 2 heading of 111.50 m has been completed out of total length of 140 m. As of April 30, 2019, 112.30 m heading for Desilting Chamber 1 has been completed out of 140 m. Adit to downstream GOC stands completed as of February 2019 and the heading and benching of Gate Operation Chamber (GOC- 9.8 m x 7.4 m x 8.0 m) has been completed as of April 30, 2019.

B. Head Face Tunnel 

Excavation of all the 5 Adits were completed in 2018. As of April 30, 2019, excavation of 4,478.40 m of HRT has been completed out of total length of 11,998.50 m.

C. Power House Complex, Surge Shaft, Valve Chamber and Pressure Shaft

Excavation of Power House crown (El. 1783.80 m - El. 1766 m) of length 66.6 m and Transformer Cavern Crown (EL 1787.47 m- El. 1762.5 m) of length 61.20 m stands completed. Benching of Power House Cavern at Service Bay from El. 1763 m to El. 1761.9 m is under progress as on April 30, 2019.

As of April 30, 2019 physical progress of MP-1 Package (Civil and HM Works) stands 34% completed.

3. Main Contract Package, MP-2 (Electro-Mechnical Works)

As of March 2019, MP-2 Package (Electro-Mechanical Works) progress includes engineering, manufacturing/procurement and transportation of the E&M components and the overall progress of MP-2 Package of 69.50% stands completed.

The Manufacture, Factory Acceptance Test and Dispatch of major E&M equipment such as Turbine Housing, Distributor Pipes, Power House EOT Crane, Ground Mats, Generator Transformers, Gas Insulated Switchgear, Isolated Phase Bus Ducts, Generator Stator Bars, Pothead yard Equipment, PLCC System, Static Excitation System, Protection System, DG Sets, Cable Trays & Support System, Auxiliary Transformers, Valve House Crane, GIS EOT Crane, Butterfly Valve and Rotor Rim stands completed. The Earth Resistivity Test at various project sites of Nikachhu Hydropower Project stands completed.

The mobilization for MP-2 works are expected to start from mid of May 2019.

Transmission Works

For power evacuation, construction of 18.6 km, 132 kV double circuit line from Nikachhu Pothead to Mangdechhu pothead yard is being executed by CDCL (transmission erection works) & BPC (supply of materials). As of March, 2019, the overall work stands completed up to 80%.