Test blasts of Supertech’s twin towers were carried out at the site on Sunday to ascertain the amount of explosives that would be needed for razing the nearly 100-metre tall structures, officials said.
The Supreme Court had on August 31 last year ordered demolition of the twin towers which had come up inside the Supertech Emerald Court housing society’s premises in Sector 93A in violation of building laws and in an area earmarked for green cover.
The demolition of the Apex and Ceyane towers is scheduled for May 22 but after the Sunday test blasts, experts engaged in the job said the structures are “very solid” and they may have to use “more explosives” than what was estimated earlier to bring the buildings down.
Earlier, it was estimated that 2,500 to 4,000 kg of explosives would be needed to demolish the twin towers but the “quantity is likely to go up” and they would “need more time” to plan out the final working, an expert told.
The test blasts were held in the presence of representatives of Central Building Research Institute (CBRI) at Roorkee in Uttarakhand, Noida Authority, Supertech, Edifice Engineering and Jet Demolitions.
A siren lasting a few seconds went off at 2.15 PM followed by two to three sirens at 2.30 PM, moments preceding the blasts (a series of six blasts separated by micro-seconds) which lasted less than two seconds.
A last short siren went off at 2.45 PM in an indication by representatives of Edifice Engineering and Jet Demolitions that everything was okay, officials said.
Mumbai-based Edifice Engineering and South Africa-based Jet Demolitions are private agencies entrusted with the demolition job.
The test blasts were carried out with less than four kg of explosives in the Apex tower. The explosives were placed on five columns in the basement of the building and one on the 13th floor, officials said.
“The objective of the test blasts was to determine the total amount of explosive required for the complete demolition and the procedure to be followed to control the flying dust as a result of the demolition,” the Noida Authority said in a statement.
Joe Brinkmann, Managing Director of Jet Demolitions, told reporters that different quantities of explosives were used at different places and different levels of protection were used.
“The whole purpose was to get precise and specific information so that we can fine-tune our blasting design. Everything went off nicely. We got very good results. We are very happy with what we see,” he said.
“Now we will be studying the results over the next few days after that we will work on our designs so we can then finalise our designs in next 10-15 days,” Brinkmann said.
He said it was a difficult and challenging task but they have the right crew, right work plan and will meet the challenge.
Noida Authority’s General Manager (Planning) Ishtiaq Ahmed said, “We have taken the environmental management plan from Edifice Engineering and all protection measures suggested in the plan will be taken. We are taking the PM 2.5 and PM 10 measurements regularly and we will take care of environment management.”
Ahmed said the readings of vibrations and pollution caused during the test blasts have been taken and it would be analysed over 10-15 days and the other details would be available after the detailed analysis only.
Utkarsh Mehta, Partner at Edifice Engineering, said a team from IIT Chennai was also present during the test blasts to monitor and analyse the vibrations caused by them. A team of geo-structural experts from Cochin has also been hired by Edifice Engineering along with IIT Chennai group for the monitoring, he said.
“The vibration monitoring was done at six points – four near the GAIL gas pipelines and one each at Emerald Court society and ATS Green Village society. Their results do not come immediately and take some time,” Mehta told reporters.
Meanwhile, residents of Supertech Emerald Court society expressed satisfaction after the test blast.
“I was downstairs but my family, including wife, parents and two minor children were inside the home when the test blasts were conducted. The test was successful and the May 22 result would also be good hopefully. I am more confident now after seeing the test blasts,” Gaurav Raghav, who lives in one of Emerald Court buildings which is very close to the Apex Tower, said.
The residents said they had followed all precautionary measures as advised by demolition agencies like switching-off air conditioners and not hanging in the balconies at the test blast time.
UBS Teotia (80), who had moved court for the demolition of the twin towers, “I am very satisfied with the test blast today.”
Additional Deputy Commissioner of Police (Central Noida) Elamaran G said adequate police force, ambulance, fire tenders were arranged at the time of test blast.
“A platoon of the Provincial Armed Constabulary (PAC) was kept ready for the test blasts while over 50 police personnel of Gautam Buddh Nagar were also on duty at the time,” the officer said.
The road stretch in front of the twin towers and Emerald Court was kept closed by the police for a brief period ahead and after the test blast as precautionary measure.