Apropos the WAPDA rejoinder of February 23 to my article (The Nation November 11, 2008) about serious concerns regarding safety of the world's highest roller-compacted concrete (RCC- roll-crete) Diamer Bhasha dam. Roll-crete is a new material. It is relatively soft and vulnerable to leakage and cracks compared to the conventional vibrated concrete. The latter has been used for building thousands of dams, bridges, buildings and other structures. No roll-crete dam higher than 620 feet in operation has been built anywhere in the world. My concerns stem from the height of 925 feet roll-crete dam located in an active earthquake zone and in the upper Indus valley prone to extraordinary hazards of avalanches, massive rock slides, land slides, rock and snow dams and lake bursts. Its safety would be at high risk. Such concerns are also shared by many top engineers of the country including two former WAPDA chairmen. Some other pertinent issues were also highlighted. One questioned the engagement of a German firm as lead consultant that had been blacklisted by the World Bank for corruption and payoffs on a project in South Africa. WAPDA's rejoinder is basically a pack of evasive rhetoric and irrelevance. So I would ignore it and continue to voice my concerns through your paper against the 925 feet high monstrosity that has the potential, in a worst case scenario, to be a catastrophic risk to life and property all the way down to the Indus Valley unto the Arabian Sea coast. -B.A. MALIK, Lahore, via e-mail, May 18.