Construction of Diversion Tunnel, Dam, Intakes, and Desilting Chamber including Hydro-Mechanical works.

The construction work of the Diversion Tunnel, Dam, Intakes, and Desilting chamber including associated Hydro-Mechanical works was awarded to M/s Larsen & Toubro Limited, India.

The MC-1 package consists of the following components:

• 2 Nos. of Diversion Tunnel of 11 m dia. each & lengths 1,427 m & 1,296 m.
• 4 Desilting Chamber each of 330 m x 18 m x 24 m.
• U/s & D/s Coffer Dam.
• 4 Nos. of Intake tunnel each of 6 m dia. & a total length of  1,477 m.
• Concrete Dam of 136 m height and 239 m length, 70 m deep below river bed level.

 Special Measure Features / Uniqueness of the Package adopted

• 2 m wide, 137 m long, 92.0 m deep (varies from 40 m to 92.5 m) plastic concrete cut-off wall has been constructed  below upstream Coffer Dam first time in the Subcontinent
• conventional vibrated concrete (Quantity 1.6 million Cum.approx.)
• 791 Nos. of 325 mm dia. Micro piles, with a total drilling depth of 66,735 m have been carried out for, the first time in Bhutan
• Consolidation Grouting drilling depth – 37,103 m.
• 50 m to 92 m deep, 491 Nos. Cable anchors, having a total drilling depth of 29,778m carried out first time in Bhutan
• 229 Nos. of 2 m dia. RCC piles, 50 to 65 m deep in rocks are being carried out as slope stabilization measures and part Dam foundation first time.