Expert group for discussing seismic issues on Subansiri dam

‘Detailed geological map of the site needed for a fruitful discussion'

Guwahati: The Expert Group that went into the downstream impact of the 2000 MW Subansiri Lower Hydro Electric Project being constructed by the NHPC at Gerukamukh on Assam-Arunachal Pradesh border has written to the Expert Appraisal Committee (EAC) on Hydropower and River Valley Projects that the proposed discussion on seismological issues relating to the river dam should be held at the project site to facilitate any necessary explanation or field verification of the reality at the site itself.

Members of the Expert Group told journalists here on Monday that the EAC meeting held in Delhi on December 11 decided that a meeting of smaller group of experts would be held on January 7 in Delhi to discuss the seismological aspects of the Subansiri Lower HEP project. Members of the Expert Group also attended and deliberated in the EAC meeting.

The Expert Group in a letter to Dr. R. Nath, Chairman, Expert Appraisal Committee (EAC) on Hydropower and River Valley Projects, on Sunday also insisted that the proposed discussion on seismic issues should include all members of the expert group to avoid any ambiguity regarding collectiveness of any decision that comes through.

The Expert Group also stated in their letter that before holding any more discussion the detailed geological map of the site and area of influence, micro-seismic data and results of two-dimensional seismic survey and paleo-seismic study were needed to be furnished by the NHPC as without these documents a meaningful and fruitful discussion is unlikely. The Expert Group claimed that while all technical arguments of the group were by and large supported by a range of documents, those arguments made by others including those by the NHPC were mostly not supported by documents.

The Expert Group reiterated its stand that various seismic parameters considered by the NHPC for designing the dam were not correct and they needed to be corrected and accordingly the dam structure be redesigned to ensure safety and stability.