KOLKATA: At least 10 houses developed cracks on Friday morning in the Bowbazar area of Kolkata, following water seepage during work in the East West Metro tunnel there, a senior official said.
Residents of these houses located at Madan Dutta Lane were being shifted to nearby hotels, Kolkata Metro Rail Corporation (KMRC) general manager, administration, AK Nandy said.
Ten houses have developed cracks owing to some water seepage during work in the tunnel, he said.
Madan Dutta Lane is situated near Durga Pituri Lane, where buildings had got damaged on two occasions earlier due to ground subsidence.
Kolkata Mayor Firhad Hakim said that the Metro authorities should demolish the houses in the area and after total precautionary work to prevent any future accident, new buildings should be constructed.
"It is not good to try to identify and repair in bits and pieces as the danger of future accidents may exist, it will be good to demolish the houses in the affected area and come up with a condominium after extensive precaution," he told reporters, reacting to the incident.
Buildings in the Bowbazar area in central Kolkata developed cracks twice earlier during tunnelling work, leading to delay in completion of the East-West Metro project.
"Cement grouting work of the underground tunnel has been going on since last Friday," Nandy told reporters after visiting the affected area.
He said that on the advice of two expert engineers from Sweden who are here, chemical grouting is also being done for reinforcement of the structure.
"Despite that it happened, now we have to assess the reasons for the incident," he said, adding that the KMRC engineers were working underground to arrest the seepage.
Nandy said that a letter was given to the local councillor of Kolkata Municipal Corporation regarding evacuation of residents of the 10 houses.
"Following assessment of all the houses at the affected site, it will be decided whether residents of more buildings have to be evacuated," he said.
Nandy said that efforts will be made to give monetary compensation to the owners of affected buildings and shops and other residents within 15 days.
"We will pay as we did earlier, having paid Rs 5 lakh to those who had to stay away from their homes for more than 30 days, Rs one lakh to shops less than 100 square feet area and Rs 5 lakh which have area more than that," he said.
On August 31, 2019, a tunnel boring machine (TBM) had hit an aquifer leading to severe ground subsidence and collapse of several buildings at Bowbazar and caused delay in completion of the project, which was earlier scheduled to be completed in December, 2021.
At least three houses were damaged again in May this year owing to ground subsidence caused by water seepage during work for joining the tunnels coming from the Sealdah side and the Esplanade side.
Tunnelling for both up and down lines using TBM between Howrah and Sealdah was completed earlier this year and work was going on for joining the two sides when the second incident of ground subsidence due to water seepage occurred, an official of KMRC, which is the executing agency for the East-West Metro project, said.
The East West metro corridor connecting Howrah Maidan and Sector V in Salt Lake is partially operational between Sector V station and Sealdah.
Out of the 16.6 km length of East West metro, underground corridor constitutes 10.8 km between Howrah and Phoolbagan with the tunnel passing below the Hooghly river, while the rest is elevated corridor, according to the KMRC official.