NORTH LAKHIMPUR, June 22 - Rising water of Subansiri has been flowing over the under-construction main dam of 2000 MW Lower Subansiri Hydro Electrical Power (LSHEP) plant at Gerukamukh since Sunday night. The river has been in surge due to incessant rains in that area covering the hills of neighbouring Arunachal Pradesh.
The incident sent panic waves among the people living in the downstream areas in Lakhimpur, Dhemaji and Majuli districts. The LSHEP site at Gerukamukh has been experiencing a series of natural disasters since May 27 with landslides and damages to claddings of the diversion tunnel. The overflowing Subansiri also inundated many installed machineries and other infrastructure in the LSHEP site. The developments prompted various organisations to hold a public meet at Gogamukh where leaders of AASU, AJYCP, TMPK and others calling for unified action against the construction of the mega dam.
On Monday, a delegation of various organisations visited the LSHEP site at Gerukamukh. The National Hydro Electrical Power Corporation (NHPC), which is constructing the dam, showed the visiting organizations the latest state of the site.
Speaking to The Assam Tribune, an official from NHPC at Gerukamukh said that latest natural phenomenon was quite normal to the design of the mega structure. He explained that as per planning, construction period of LSHEP was considered for seven months during non-monsoon period from October to April.
�Upstream coffer dam 31m high at 100m upstream of dam axis and downstream coffer dam 21m at 100m downstream are constructed to divert the river water through diversion tunnels to facilitate dam construction during non-monsoon period,� said the official.
The official further said that the diversion scheme was designed to cater for non-monsoon floods, while coffer dams were expected to get damaged during monsoon flood from May to September and as such, required rebuilding before undertaking work in subsequent working seasons.
The main dam was already constructed more than 30 m above bed level, the upstream coffer dam was no more required to divert the river through diversion tunnels. Downstream coffer dam is required to stop the backflow of the river coming out of the diversion tunnel to the spillway area during non-monsoon months.
�As such washing away of coffer dam during monsoon period is a usual event for the LSHEP,� said the officer.