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Experts say floods pose serious threat to Bengaluru’s buildings; more safety reforms needed

Recently, a group of homebuyers from Outer Ring Road in Bengaluru filed three complaints against the builder for failing to take necessary precautions to avoid apartment flooding.

On September 19, a group of homebuyers from Outer Ring Road (ORR) in Bengaluru filed a complaint at Marathahalli Police Station after they incurred a loss of at least Rs 4.3 crore due to waterlogging in their apartment complex.

Two weeks ago, incessant rainfall which battered the city, left several residential apartments and luxury villas waterlogged.

Homebuyers of the 'Sterling Ascentia’ luxury apartment on ORR were caught unawares before water gushed into the basement, damaging 29 vehicles and cutting off the Water Treatment Plant (WTP), Sewage Treatment Plant (STP) and two elevators. "Since September 5, none of these was repaired; only yesterday the WTP has started functioning," Prannay Srivastava, one of the complainants, said.

Later, the Resident Welfare Association (RWA) filed three complaints at the police station: one on the losses incurred due to water getting into their vehicles; a second for non-functional WTP, STP and elevator, and a third for excessive noise created due to two towers being constructed inside the complex.

More than encroachment

Experts say though encroachment is the primary culprit for the waterlogging, residents say the developer's non-compliance with necessary precautions added to the disaster. "Currently, we have two towers with 172 flats. However, two more towers are being constructed. Deep pits have been dug without any precautions like retention walls, etc. Additionally, one of the under-construction towers is just next to the current functional tower where people are staying ― less than 2 metres."

A representative from the developer, who did not wish to be named, said, "The level of the road behind the apartment complex is 4 metres below that of the road at the front. Due to heavy rainfall, water stagnated at the back at a height of 5 feet. And that led to the waterlogging."

The representative added, "Nobody could have anticipated the rainfall. Now, we have drained out the water and restarted the WTP, STP and elevators. For the compensation for damaged vehicles, we have told police officials and homebuyers that they have to claim their own insurance. We have taken cognizance of other matters."

Experts say Bengaluru buildings need to be made safer

Structural engineers and city planners in Bengaluru say most buildings in Bengaluru sit on lake beds or wetlands. These buildings encroach the Rajakaluves or stormwater drains, which can lead to infrastructural failure.

However, Iftikar, who goes by one name and an engineer, said, “The recent Bengaluru floods will pose a serious infrastructural threat to buildings. The foundation of these buildings could sink, leading to their collapse.”

Recently, he visited five gated apartments in the waterlogged areas of Bengaluru and found most of the affected buildings to be at risk of serious infrastructural damage. "The buildings here are 10-20 years old. Most builders have used filter sand, which was used before M-Sand came into the market ― filter sand is basically mud added with sea shells sold as river sand. Chances are high of columns built with this sand collapsing after being waterlogged for several days.”

Abhay Gupta, a structural consultant said basement flooding is a common scenario across India. "However, there are no rules on the number of levels of basement we can build, or how deep we can dig. Several buildings across the world have been built completely underground," he said.

According to experts, the population density which has increased multifold, has resulted in severe stress on the drainage system across cities. However, apartments need to take several precautions, apart from redesigning the infrastructure. "Rainwater is not an issue but the outflow creates a problem. Today, the level of most roads are higher than apartment levels. This should be considered while designing buildings," he said.

Earlier in an interaction with Moneycontrol, Premika Thirumur, a resident of a luxurious villament in Yemalur ― next to 'Billionaire's Street' ― had said, their apartment was flooded because the stormwater drain near their complex was at a higher level than the apartment.

Gupta said, "Waterways should be created in buildings to prevent water from gushing in. Measures like proper catch pit at the entrance of the complex and creating water recharge pits across the apartment can help prevent waterlogging inside complexes."

Experts say water should be allowed to flow, which can help prevent flooding of basements. Proper drainage will prevent waterlogging. There are many such success stories in Mumbai, they point out.

According to Iftikar, "Now that homeowners have started returning to their homes, they must get the foundations checked by a structural engineer and take necessary steps to strengthen the building infrastructure."
Souptik Datta Sub Editor at Moneycontrol
first published: Sep 25, 2022 01:44 pm