In the aftermath of the tragedy that unfolded in Bowbazar with building collapses and mass evacuation from the areas concerned, fear continues to loom large with buildings developing new cracks each day due to the continuing land subsidence. A total of around 20 buildings still remain affected and are developing new cracks. KMC sources said data that are being collected by control rooms, every day in the area, revealed that while some existing cracks continue to widen, new ones too are developing which is a cause of concern.
It may be noted that the KMC mayor, Firhad Hakim, has already said that while the buildings those stand in a precarious position need to be eventually razed, but at present, no risk can be taken since it could collapse on the workers during demolition. He clarified that first soil tests have to be done to ascertain whether land subsidence has ceased. Thereafter, the tunnel will be checked and finally post clearance, demolition can be discussed, said the mayor. It was further learnt that initial structural support is being given to the buildings which have developed a tilt.
Several residents of evacuated buildings in Syakra Para Lane had today gathered in the area to collect their belongings. They were allowed to go inside in a group of five. An official, requesting anonymity, said “The fear is that the developing cracks and the weak foundation of the buildings could collapse any moment, posing a threat to lives of the people who are still in the area. Arrest of land subsidence is crucial.”
Meanwhile, to combat the situation inside the tunnel, engineers of Kolkata Metro Rail Corporation Limited (KMRCL) along with the team of national and international experts, injected around 1000 litre of water to create a counter-force at various points from where the aquifer water was flowing into the tunnel.
Three “coffer” walls, according to the KMRCL engineers, are planned to be constructed at a distance of around 100 metres from the cutter head section of the tunnel boring machine, Chandi. The coffer walls and the coffer dam are being built to arrest the water that has flown inside the tunnel after passing through the cutter-head, main body, tail skin and concrete segments of the tunnel boring machine. Of the total 100 metres beyond which the three layers of coffer walls are being constructed, around 10 metres consist of the cutter-head, main body and tail skin while the remaining 90 metres is formed of the concrete segments in the shape of rings used in the wall of the tunnel.
“While the first coffer wall had been completed, the second one is being constructed and is expected to be done by today,” informed a senior KMRCL official. The coffer wall and the dam are expected to be ready in the next two days. The collection of aquifer water om the coffer dam will prevent the subsidence from spreading further, even though ground loss might continue to take place in the already affected area of Bowbazar, according to the KMRCL engineers,” he added.
KMRCL started a survey of the evacuees and affected families yesterday to get an initial idea before distribution of the compensation amount. KMRCL is also seeking help of the local councillors and Kolkata Police to get further information on the affected families and identify actual occupants. As informed by officials of KMRCL, the compensation amount of rupees five lakhs is expected to be distributed from tomorrow.