Is Mullaperiyar Dam Safe?

The age of 116 years old Mullaperiyar Dam and the fact that it has outlived its design life of 50 year by more than 60 years itself are enough for common people to worry about the safety of dam and possible catastrophe the dam collapse can make! But it is not only the common man's perception, but experts and technical people also have evidence and reasoning to pronounce the dam is unsafe.

Here are some excerpts:

Retired Engineer M. Sasidharan:

"The scanning of upstream side of the Mullaperiyar dam using a remote operated vehicle by the Central Soil and Materials Research Station on directions from the Empowered Committee of the Supreme Court had found serious damage to the masonry structure between 95 to 106 feet from the base of the dam, retired engineer M. Sasidharan who was observer of Kerala during the scanning said in a report to the government." ‘Serious damage’ to masonry of Mullaperiyar dam detected The Hindu, December 7, 2011.

Himanshu Thakkar, Coordinator of the South Asia Network on Dams, Rivers & People:

"A dam that is now 116 year old developed leaks and cracks during the earthquake in 1979. Recently, at least four earthquake tremors since July 2011 (as accepted by Tamil Nadu in an application before the Supreme Court filed on December 1) are only the latest of the seismic activity in the dam area in this context. Several expert bodies including the Indian Institute of Technology, Centre for Earth Science Studies, etc. have concluded that the dam structure and foundation is too weak to take the shock of earthquake of magnitude 6.5 on Richter scale, which is very much likely at the dam site. The dam is not able to take the load it is supposed to take. Its unique construction material, geological and seismic location does not render it fit for any further technical solution." Why Mullaperiyar Dam needs to be decommissioned Urgently  , Rediff.com December 2, 2011 

James Wilson, Assistant Executive Engineer (Civil), Kerala State Electricity Board:

The Mullaperiyar Dam was built of lime surkhi concrete which is a very low strength concrete almost equivalent to M5 concrete compared to M30 concrete used for Idukki Arch Dam. The strength of this concrete has further reduced due to the continuous leaching of lime reported from its inception. Even though two attempts of grouting were attempted in 1930s and 1960s, it was not able to completely fill the cavities formed due to the leaching of lime. Seismic Threat to Mullaperiyar Dam, November 7, 2010

These excerpts only shows the structural weakness of the dam. Then there are study reports that shows the possibility of earthquake of 6.5 magnitude in the dam area and dam can not withstand an earthquake of such magnitude.

There are counter arguments from Tamil Nadu against these study reports. But should we play with lives of 3.5 millions of people? There are international conventions and principles on the aspect of precautionary measures. See what Justice. V. R, Krishna Iyer says, "Mullaperiyar is a classic instance where the precautionary principle of action cannot wait for a public calamity to happen"

"There are situations where engineers may disagree with one another. Some experts may consider the condition of a dam to be marginally safer than what others say it is. But nature has its own way, and experts’ expectations and calculations may go awry. Once there is doubt and the possibility of a risk, the state should not take any chances. This principle was laid down in the Rio de Janeiro Declaration on Environment and Development of the United Nations Conference on Environment and Development (1992)." A dam and some critical questions, The Hindu, July 21, 2009

Doesn't the Kerala's demand for decommissioning of the old Mullaperiyar Dam and constructing a new dam make sense?