The two 32-storey towers of Supertech Emerald Court (Apex and Ceyane) in Noida will be the tallest to be demolished in the country to date.
Experts say the country is relatively new to the concept of skyscrapers and has only just started building them. However, there is little expertise or experience in demolishing skyscrapers. Although there are different demolition techniques, the “implosion” technique is the most widely used and best suited for the demolition of such tall structures in a densely populated area. In this technique, small explosive devices are placed in several places in the building in such a way that the debris falls inside the premises.
After being reprimanded by the Supreme Court over the delays, the builder and Noida Authority finally awarded the demolition task to Edifice Engineering earlier this week. HT talks to Edifice Engineering partner Uttkarsh Mehta about how this piece of history unfolded.
So when do buildings collapse?
According to the action plan that we have submitted to the authority and the builder, once we have the work order and all the paperwork is completed, we will start our field investigation and all the preparation will take about three months. . We hope the day will be around mid-May. After the explosion, it will take us about three months to clear the debris and remove the steel.
What preparations and investigation do you need to do now?
There are two types of preparations – one prepares the building or structure itself and the other preparation is for neighboring buildings or surroundings. We also need No Objection Certificates (NOC) from all relevant authorities like DM, Police, Fire Department. We also need permission from the Petroleum and Explosives Security Organization (PESO) in Agra to transport and use the explosives. Also, we need to run a campaign to educate everyone in the neighborhood about the do’s and don’ts during the explosion. We will also have ongoing meetings with all government departments to prepare an evacuation plan for everyone living within a 50 meter radius and for stopping traffic within a 250 meter radius for the duration of the blast. . We will also discuss how emergency services will be allowed into the area for the duration of the explosion. All of this will be done in consultation with the Central Building Research Institute (CBRI).
What is the blasting process?
After the survey, our expert will prepare a “blasting design” for the structure to fall from all angles such as safety, vibration and other factors. The design will answer questions such as which columns should be sandblasted? Which walls need to be removed first? On which floors will the explosives be placed? What will be the diameter and depth of the hole (in which they are placed)? How much explosives are needed? The building should fall like a deck of cards with minimal flying debris. This is our biggest challenge.
Maybe after a month of starting the investigation, we can decide on a blasting date in agreement with all the authorities. A pre-structural analysis of all buildings within a radius of 50 meters will be carried out. We will investigate any existing damage to any of the structures and we will also check them afterwards to see if there was any impact from the blast.
There are apprehensions among people who live nearby, particularly at Emerald Court which is about nine meters from the Twin Towers. What are we going to do to ensure safety?
From our initial analysis of the location, we will need to build a passage between the Twin Towers and Emerald Court to avoid any flying debris. When we saw the site, there is an alley between the two buildings which is already weakened. It has exposed cracks and reinforcements. We may have to remove the driveway entirely for the debris to fall directly to the basement. The driveway will then have to be rebuilt later, which is already a request from local residents. Our other option is to reinforce it, but that’s not very doable. Additionally, we will be using empty containers anchored to the ground and stacked up to three stories high as an additional layer of security to protect Emerald Court buildings from any flying debris.
What other security measures will be followed?
We use at least four layers of geotextile fabric or fabric to cover the entire building that needs to be demolished so that there is no flying debris. Each part of the building to be blasted will be covered with wire mesh and then with geotextile fabric. Each floor and pillar that will be blasted will also be completely covered with geotextile fabric. A layer of fabric will also be placed to cover the entire building.
For ATS and other surrounding buildings, we will also cover them with geotextile fabric, primarily for dust control. Our assessment is that there will be virtually no flying debris leaving the Twin Tower compound itself.
During such implosions, there is also a large cloud of dust. Is there a way to control the dust?
Yes, there is a cloud of dust and this is the only negative point of this technology. While doing this inward blast there is a huge cloud of dust and it usually dissipates in 6-7 minutes. How long it will take to dissipate and how far it will go also depends on the wind speed and direction at the time of the explosion. However, there is no way to control or minimize it from our practical experience. Firefighters, fog guns and other solutions have been tried, but only about 10% successful in controlling the dust.
However, we will request Noida Authority to be ready with mechanical sweepers. When sending a notice to neighboring residents, we will mention that they should keep all doors and windows closed, turn off their air conditioners, and keep the outdoor unit of their air conditioners covered if possible so that dust is not sucked in .
(The Apex and Ceyane buildings were intended to be 40 floors, but were subject to litigation after the 32 floors were built. Both buildings have 915 apartments and 21 shops)