City utility networks exposed to danger

Damaged utility networks of Dhaka would be the main cause for casualties in the event of a major earthquake and the capital might need to be abandoned even, experts said.

Gas, electricity, water, and sewerage lines would be damaged immensely during the earthquake and the number of casualties would be high due to fires, which rescuers would most likely be unable to reach and put out.

The earthquake experts said rescue operations could collapse completely.

Painting the grim picture, they said immediate steps to improve the total system of the utility networks were needed to get rid of this vulnerability of Dhaka.

Dhaka has 1,834km of gas transmission pipes and there would be leaks in 56 places and cracks would develop in 191 places, said Prof ASM Maksud Kamal, chairman of department of disaster science and management of Dhaka University, quoting a 2010 survey done by the Comprehensive Disaster Management Programme.

There were 1,118km of underground water pipes in the city and if the Madhupur fault had an earthquake of 7.5 magnitude, pipes would leak in 79 points and pipes would break in 272 places, he said.

In the 630km of sewerage network, there would be leaks in 107 places and cracks in 360 points, the professor said.

Overhead electricity poles and snapping of cables would be a major problem too. At least 16,000 electricity poles out of 56,000 would topple during the tremor, he said.

Maksud suggested using gas cylinders instead of underground pipelines for providing gas to homes and installing earthquake-resistant gas pipes in phases. An automatic gas transmission control system was required, he added.

Prof Mehedi Ahmed Ansary of the department of civil engineering of Buet said 35 percent area of Dhaka city corporations and 60 percent area of Rajdhani Unnayan Kartripakkha were vulnerable to the risks of utility network-related hazards in the event of an earthquake.

He suggested that the quality of soil be improved to reduce the possible damage to utility networks and buildings.

“Soil can be improved by injecting cement water mixture under very high pressure, which is commercially called 'jet grouting'. This method of soil improvement is suitable for loose sand and clay,” said Ansary.

To assess the vulnerability, a physical survey of gas pipelines and water pipelines would be done by Rajuk and GIS maps would also be prepared under a project funded by the World Bank, he said.

Director (operations) of Titas Gas Transmission and Distribution Company Ltd HM Ali Ashraf said they were working on a study to find the solutions to this earthquake-vulnerability problem and would take effective measures following the survey.

He said it was necessary to set up seismic shut-off valves and they would try to do that after the study.

Deputy Managing Director SDM Quamrul Alam Chowdhury of Wasa said they had set up their large transmission lines considering the risk of earthquakes.

He said water treatments plants were also set up considering earthquakes.

Chittagong too had this vulnerability.

Prof Maksud said if an earthquake of 8.5 magnitude on the Richter Scale happened at the Rakhaine fault, there would be gas leaks in 104 places and cracks in 125 places in Chittagong city's gas transmission network of 217km.

He said the 542km water supply network would have leaks in 320 places and there would be cracks in 407 points. The sewerage network would leak in 131 points and crack in 59 places.