Non-completion of critical milestones spells disaster for NHPC's Subansiri Lower HEP

The recurring problems associated with the dam works and other critical activities at NHPC's 2000 MW Subansiri Lower hydro electric project (HEP), situated near North Lakhimpur, on the border of Assam and Arunachal Pradesh, has pushed back the commissioning date to August 2014.

Furthermore, the delay in signing of the Memorandum of Understanding (MoU) with the State government of Assam has added to the woes of NHPC, which is already struggling to complete the works associated with the critical milestones.

The hydro mechanical contractor has almost completed the heading excavation of the head-race-tunnel (HRT). On the other hand, more than half of benching excavation still needs to be finished. Power house concreting is progressing slowly, with only 2,690 cum out of 10,000 cum laid out during the month of August. Moreover, merely 9% of pressure shaft liner and 12% of intake gate 7 have been erected.

The Subansiri Lower HEP, with 8 units of 250 MW, each, is a run-of-river scheme, on the river Subansiri. Apart from a 116 m dam, the project involves construction of eight 1,168 m horseshoe-shaped head race tunnels (HRT) of 9.5 m diameter, eight pressure shafts, a surface power house to accommodate eight Francis turbines, along with a 206 m long tail race tunnel (TRT).