Shock & awe: Noida's twin towers to be demolished in four phases

NOIDA: The mammoth exercise of bringing down the twin towers at Supertech’s Emerald Court compound, while ensuring the safety of all other buildings in a populated neighbourhood, will take place in four phases that will include a structural survey of all buildings in the impact radius and a “pre-weakening” of the towers so that they implode within the perimeter once the charges are set off.
Sources at Edifice Engineering, the company tasked with the demolition, said it’s also planning to take a third-party insurance cover of Rs 75 crore-100 crore to indemnify owners of houses and any other structure within a 50-metre radius of the twin towers at Sector 93A in case there is any structural damage due to the demolition of the towers.

Residents in the vicinity, especially those at the adjacent ATS Greens Village, have been airing their concern about the demolition and its impact on the structural integrity of their homes. Its RWA head Bharat Bhusan had on Monday told TOI he had sought details of the demolition plan from the Noida Authority but hadn’t received any.
Apex and Ceyane, the two uninhabited towers, are being razed on the orders of the Supreme Court, which had on August 31 last year upheld an Allahabad high court order to bring them down, holding that the towers were built in violation of law. The Emerald Court RWA had initiated the legal battle against the twin towers back in 2012.
Sources said the type of explosives that will be used for the demolition will be determined once engineers and technical experts of Edifice visit the Petroleum and Explosives Safety Organisation (PESO) office in Agra within a week. Apart from seeking the organisation’s approval to carry out the blast, PESO, the nodal agency for matters where the Explosive Act and the Petroleum Act are applicable, will also provide the list of explosive storage magazines in the region.
Edifice Engineering will pick which explosives it will use only after checking the available inventory in the magazines. Away from locations where they are manufactured, magazines are buildings or structures specifically designed to permanently store explosives.
Ammonium nitrate, nitroglycerin (dynamite) and trinitrotoluene (TNT) are some options on the table. “The quantity will be decided only after we find out which type of explosives will be used for the implosion. Our meeting with PESO will give some clarity. Till then, nothing can be said. We will visit the magazines in Agra and other parts of NCR to check the options,” said Uttkarsh Mehta, partner at Edifice.
Before the demolitions happen, likely in May, extensive preparations are needed. In the first phase of the preparations, engineers will survey the demolition site and the two towers exhaustively. Experts will also check for defects, cracks and degree of deterioration in nearby buildings. “Basically, we are going to conduct a structural audit within the impact area and see if reinforcement of existing structures is required,” said Mehta.
Pre-weakening Apex and Ceyane to ensure the towers collapse inwards will be the next step. For this, engineers will identify columns, pillars and beams to be removed. Cantilever beams that support two walls will be the first ones to be brought down.
Shear walls will present a challenge. A preliminary survey has revealed that the shear walls built around each floor of the 100-metre-tall (33 storeys) Apex and 97-metre-tall (32 storeys) Ceyane are 12 metres long and 3 metres wide. Designed to bear lateral load and increase seismic resistance, the shear walls will have to be cut strategically on each storey to ensure the remaining structure collapses in the ‘waterfall implosion’ methodology that is being employed, in which the towers collapse inward and the debris collects in a heap at the bottom within the regulated perimeter. The shear walls will also yield the maximum amount of salvageable steel.
It is estimated that around 7,000 holes will have to be drilled at a gap of 1 metre to 3 metres in the two buildings to hold the charges for the implosion.
The other steps of the preparation will include checking for hazardous material like asbestos, which can cause health hazards and will have to be taken out before the implosion. Engineers will also set up an insulating perimeter to absorb the shock and minimise noise and dust pollution and vibration caused due to the implosion of the towers.