Tehri Bandh Virodhi Sangharsh Samiti
C/o Riverview Hotel, Tehri, Uttranchal.
Delhi Contact- NAPM, 14, Supreme Enclave,
Mayur Vihar-1 Delhi-91
Phone: 91-11-2256394, 91-11-2250632

ACTION ALERT: REVIEW COMMITTEE, COMMENTS AND SOME SUGGESTED ACTION

The following is the text of a letter from the Ministry of Power, Government of India, dated 10th April, 2001.


Subject: Constitution of a Committee to go into the concerns raised regarding seismic safety of Tehri Dam in the light of Bhuj earthquake etc.

1. The Government had considered in depth the seismic safety of the Tehri Dam and the detailed seismology studies carried out by Geological Survey of India, Department of Earthquake Engineering of Roorkee University and Russian experts assisted by National Geophysical Research Institute, Wadia Institute of Himalayan Geology for determining safe height of Tehri Dam, before according approval in the implementation of Tehri Dam and Hydroelectric Project Stage I (1000 MW) in March, 1994. In view of the continuing concern relating to seismic safety of the Tehri Dam, a Group of Experts was constituted in June, 1996 to further examine the issue of seismic safety of Tehri Dam. This Group in its report concluded that the design of the dam was safe to withstand the Maximum Credible Earthquake.

2. However, in the wake of Bhuj earthquake of January, 2001 the need for review of seismic safety (of) Tehri Dam is felt necessary. Further, concern has also been expressed about the possible impace of Tehri Dam on the self-purification quality of Ganga Jal. It has accordingly been decided to constitute a Committee to go into the concerns regarding:
     (a) Seismic safety of Tehri Dam in the light of Bhuj earthquake of January, 2001; and
     (b) Impact of Tehri Dam on self purification quality of Ganga Jal, etc.

3. The Committee will comprise the following:

     (1) Dr. Murli Manohar Joshi, Minister of Human Resources Development and Science and Technology Chaiman
     (2) Dr.R.A.Mashelkar, Director General, CSIR & Secretary, Dept.of Scientific & Industrial Research & Member
     (3) Dr.C.D.Thatte, Former secretary, Ministry of Water Resources & Member
     (4) Chairman, Central Water Commission & Member
     (5) Director General, Geological survey of India & Member
     (6) Chairman, Central Pollution control Board & Member
     (7) Director, National Environmental Engineering Research Institute & Member
     (8) Prof. K.S.Valdia, Bhatnagar Research Professor, Jawahar Lal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore & Member
     (9) Prof.T.Shivaji Rao, Director, Centre for Environmental Studies, Geetam College of Engineering, Vishakhapatnam, A.P. & Member
     (10) Shri U.K.Chowdhury, B-36/21, C-6, Brahmanand Extension – I,Durga Kund, Varanasi Member
     (11) Shri Guru Das Agarwal, Vridda Sewa Sadan, Pramodvan, Chitrakoot (Satna), Madhya Pradesh & Member

4. Ministry of Power will service the Committee

5. The non-official members of the Committee will be entitled to TA/DA. Non-official members would also be entitled to an honorarium of Rs.1000/ per day. All expenditure in this regard shall be met by THDC

6. The Committee may submit its report within 4 weeks to the Government for its consideration.

(sd/-) Ajay Shankar
Jt.Secretary to the Government of India


Some comments on the above letter:

(1) The statement in the first paragraph that the "Government had considered in depth the seismic safety of the Tehri Dam and the detailed seismology studies carried out " etc. is misleading. Some of the institutions mentioned above - the study of the dam site by the Geological Survey of India in the 1960's, the report of the Director of the National Geophysical Research Institute in 1986 and the statement of the Russian Chief Engineer in 1987 - have given reports which have raised serious questions about the design of the dam and its capacity to withstand a major earthquake. The Environment Appraisal Committee of the Department of Environment (1990) had also concluded that the dam design did not provide for an earthquake of magnitude greater than 8.0 on the Richter scale which was certain to occur during the life of the dam. Therefore the EAC had recommended that the Tehri dam should not be given approval.

(2) In the first para, the statement that "… a Group of Experts was constituted in June, 1996 to further examine the issue of seismic safety of Tehri Dam. This Group in its report concluded that the design of the dam was safe to withstand the Maximum Credible Earthquake" is misleading. We reproduce below the page from the Report of the Group of Experts containing their recommendations, signed by 4 out of 5 members of the Group.

Recommendations

Based on a review of the reports made available to the Group and further studies conducted by DEQ-UR (Department of Earthquake Engineering – University of Roorkee) on the behaviour of the idealised two dimensional model of the dam to the ground acceleration corresponding to MCE (Maximum Credible Earthquake), the Group came to the conclusion that the present design of the dam is expected to be structurally safe to withstand the MCE during the economic performance life of the dam-reservoir system.

However, a number of crucial questions could not be settled, notably the slope stability on account of the difficulties reported in Annexure-13, and the response of the dam to MCE in the longitudinal direction. Keeping in view, therefore, of the sensitivity of non-linear behaviour to possible variations in the values of seismic parameters such as PGA, duration, frequency content and material properties, still larger displacements cannot be ruled out. In fact as per the Soviet Report (Tehri Dam Project on the Bhagirathi river, India, contract No. 53032/67652, 9, G.P. 73-74) to which attention was drawn by one member of the Group, the idealised section of a 200 m high dam fails for the earthquake impact with PGA equal to a(z) = 0.64g; a(h) = 1.28g. Whereas there are differences in the sections analysed in the above report and the current design of the Tehri Dam, attention is drawn to the fact that for some fortuitous combination of inputs combined with particular reservoir-dam conditions, the performance of the dam to hold water at a future date, may get affected.

It is therefore, further recommended that as a matter of abundant caution, the following work be carried out:
    (i) 3-D non-linear analysis of the dam to evaluate its performance against the MCE
    (ii) A simulated dam break analysis to ensure that in the unlikely event of an uncontrolled release of water, the consequences are minimum.

Comments

The Tehri Dam is located in one of the most hazardous sites in the world. Given the large population of several crores who live downstream of the Dam, the risk factor is also very high. According to the current norms of dam building in the world, a fully state –of-the-art dynamic design analysis of the Dam becomes mandatory. Four out of five members of the Expert Group have insisted that the dam can be considered safe only if the analyses recommended by them (3-D non-linear analysis and a dam break analysis) are carried out. These analyses are yet to be carried out.

What you can do

In view of the above facts it becomes absolutely essential for the Committee which has now been constituted, to take a careful look once again at all the reports on the seismicity and safety of the Tehri Dam. All these reports are already available with the Government of India. It is also necessary for the Committee to see to it that the analyses recommended by the Expert Group of 1996-98 are now carried out. The Dam design can be considered safe only if the results of these analyses are satisfactory. Obviously, the Committee has to first order the work on the Dam to be stopped before it can get on with its work. There is a prima-facie case for the work to be stopped straightaway.

As you can also see, the terms of the reference of the Committee are extremely limited and narrow in scope. The Hanumanatha Rao Committee on Environment and Rehabilitation, which had a detailed look at the Tehri Dam Project in 1997, found that the Project had violated several conditions which had to be fulfilled before the work on the dam could be continued. However, the work continued. Since the 30th of March, the work on the Dam has been stopped by the people of the villages in the submergence area.

KINDLY WRITE TO THE MINISTER FOR HUMAN RESOURCES DEVELOPMENT AND SCIENCE AND TECHNOLOGY, GOVERNMENT OF INDIA asking him to:
    (i) See that the work on the Tehri Dam be stopped immediately
    (ii)Make sure that the Committee takes a look at all the reports and documents available on the seismicity and safety of the Tehri Dam
    (iii) See that the terms of reference of the Committee are extended to include the issues of environment and rehabilitation. Address:

Contact info for the Murli Manohar Joshi:
Dr.Murli Manohar Joshi
Chairman, Review Committee on the Tehri Dam & Minister for Human Resources Development and Science and Technology
Government of India
301 C-wing , Sastri Bhavan, New Delhi 110001
Fax: 91-11-3382365 (office); 91-11-3711772 (Residence)

In Solidarity

T.M. Mukundan
Sameer
Raturi
Vimalbhai