Test blast takeaway: Demolition of Noida’s Supertech twin towers may be delayed

A test blast before actual demolition of the illegal Supertech twin towers in Noida was successfully carried out at 2.30pm, officials said on Sunday.

Experts now estimate that they might need more time to prepare the building for demolition, which could take place after the May 22 deadline mandated by the Supreme Court. The exercise might require more than the estimated quantity of explosives because the building is structurally strong, they said.

On February 7, 2022, a bench of justices Dhananjaya Y Chandrachud and Surya Kant directed that realtor Supertech Limited and demolition contractors Edifice Engineering and Jet Demolitions implement the Supreme Court’s August 31, 2021 order to demolish Apex and Cayene, two 32-storey buildings in Supertech Emerald Court society constructed in violation of building bylaws, without further hold-up. After much deliberation, authorities decided on May 22 as the date of demolition.

Officials from Edifice Engineering and Jet Demolitions had earlier said around 2,500-4,000kg of explosives may be required to demolish the twin towers.

“The trial was great and our initial estimate suggests that the building is strong. We may need to use more explosives than estimated earlier and will need enough time for preparation,” said Joseph Brinkmann, managing director of Jet Demolitions and the brain behind the demolition exercise.

Demolition experts will have to drill 8,810 holes in the two buildings, each of which will be about 2.2 metres long. Additionally, several supporting walls will be removed before the blast.

“The report from this trial will come in about 10-15 days, following which we will start the main preparation. Fixing the explosives in the building will take more than 15 days. It is a complex and risky procedure, and we can do the blast only when we are fully prepared,” said Uttkarsh Mehta, partner at Edifice Engineering.

“The trial was successful and up to our expectations. There is a lot that depends on this trial and the entire report will be prepared soon,” said N Gopalakrishnan, director at the Central Building Research Institute (CBRI).

The report from the trial will be sent to Petroleum and Explosives Safety Organization (PESO), CBRI and Noida authority.

On Sunday, six columns, five in the basement and one on the thirteenth floor, were chosen for the blast, officials said, adding that more of the basement columns were chosen as they were already covered with geo-textile fabric and steel sheets that required less preparation.

“We used various combinations of pillars and the kind of covering we would need with geo-textile fabric and steel sheets to see which combination would work best,” said Mehta.

For the trial, 20 gram and 80 gram shock tubes were inserted into the holes that were drilled into the pillars.

One van transported the explosives and another transported the ignition system from a magazine in Palwal around 6.30am on Sunday. The explosives reached the site around 8am. The team started charging the columns and fixed explosives till around 1.30pm. They sounded a siren around 2.15pm and evacuated the building.

The blast took place at 2.30pm with just five people on the premises, the man who set off the detonator, a police officer and three officials from Jet Demolitions, including Brinkmann and the security head Marthinus Botha.

The noise, dust and vibration levels were monitored during the test blast. While the noise and dust pollution was monitored by Uttar Pradesh Pollution Control Board (UPPCB), an Indian Institute of Technology (IIT) Madras team checked vibration levels by placing sensors at six locations, four around the GAIL pipeline, one in ATS Village and one in Emerald Court.

“We have taken the readings from the sensors and the report will come in a week. However, the readings seem normal and within limits,” said A Bhoominathan from IIT Madras.

During the exercise, residents of neighbouring societies were asked to stay indoors while traffic on the main road in front of the building was diverted for an hour. Several residents came out of their homes right after the blast.

“This test has allayed a lot of our fears. We are only a bit concerned about the green area in our society. However, we have been assured that it will also covered during the actual blast,” said UBS Teotia, president, Emerald Court Apartment Owners’ Association. “The sound was also not very high in intensity, and we have been told that it will be similar on the actual day too.”