The Contract Package (MC-3) involves the construction of various civil works components, including the part of Head Race Tunnel (from Surge Shaft end), underground Surge Shaft, Butterfly Valve Chamber, Ferrule Erection Chamber, Pressure Shafts, Machine hall cavern, Transformer/GIS hall cavern, Downstream Surge Chamber, Tail Race Tunnel, and associated Hydro-Mechanical works. M/s Hindustan Construction Company Limited (HCC) was awarded the Contract on March 27, 2009.
The works under those components included in MC-3 package are as follows:
- Head Race Tunnel: A 10.0 m diameter and 1.55 km long tunnel starting from the Surge Shaft end and connecting the balance HRT in the upstream.
- Surge Shaft: An underground Surge Shaft with a diameter of 24.5 m and a height of 128.5 m along with 370.0m long 7.0m (W) x 7.0m (H) Access Tunnel.
- Butterfly Valve Chamber: Chamber measuring 80.0 m (L) x 12.7 m (W) x 21.8 m (H) to house two Butterfly Valves along with 477.90m long 8.0m (W) x 8.0m (H) Access Tunnel.
- Ferrule Erection Chamber: A chamber with 99.3 m (L) x 12.1 m (W) x 14.2 m (H) to facilitate erection of PS steel ferrules.
- Pressure Shafts: Two Steel Lined Pressure Shafts with a diameter of 6.0 m and a height of 936.4 m each with access tunnel at its bottom bifurcated from the MAT.
- Main Access Tunnel: A D-shaped tunnel with a length of 720.0 m and dimension of 8.0 m (W) x 9.0 m (H).
- Machine Hall Cavern: A cavern measuring 236.9 m (L) x 22.9 m (W) x 53.0 m (H).
- Transformer Hall Cavern: A cavern measuring 215.7 m (L) x 14.3 m (W) x 26.3 m (H).
- Bus Duct Tunnels: Three D-shaped tunnels connecting machine hall & transformer hall, each with 52.5 m (L) x 10.0 m (W) x 8.0 m (H).
- Draft Tube Tunnels: Six tunnels measuring 107.2 m (L) x 5.5 m dia.
- Downstream Surge Gallery: A gallery measuring 150.0 m (L) x 11.5 m (W) x 45.4 m (H) along with access tunnel.
- Drainage Gallery: A D-shaped tunnel of 879.0m (L) x 5.0 m (W) x 5.5m (H).
- Tail Race Tunnel: A tunnel with 10.0 m finished dia. and 1.26 km length.
- Cable Tunnel: A D-shaped tunnel with 668.0 m (L) x 5.0 m (W) x 6.1 m (H).
- Pothead Yard: An area measuring 197.0 m (L) x 39.0 m (W).
- Hydromechanical Gates: Two Surge Shaft Gates, six Draft Tube Gates with independent hoisting mechanisms, and two TRT Outfall Gates
The construction of the major components in Contract Package MC-3 remains completed, with only minor activities and finishing works remaining.