BBMP’s flood control solution: Build cement walls around 88.53 km of drains

The BBMP has received approval from Chief Minister Basavaraj Bommai to construct concrete retaining walls around 88.53 kilometres of stormwater drains in the city.

The project, aimed at freeing 58 low-lying areas from flood vulnerability, is estimated to cost Rs 962 crore, or as much as Rs 10.86 crore per kilometre.

The civic body says it has already built concrete walls around 312 kilometres of SWDs by spending Rs 2,169 crore in the last five years. The city’s total network of primary and secondary drains (rajakaluve) stands at 842 km.

The BBMP proposed remodelling another 88.53 kilometres of SWDs after several parts of the city, especially those located around lakes and drains, were flooded in the recent rains. The BBMP says these drains lack strong walls that can prevent floodwater from inundating surrounding areas.

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The project will cover 58 out of the 96 flood-vulnerable areas in the city, as per the presentation made to the chief minister.

Of the Rs 962-crore estimated cost, the maximum allocation has been made for Bommanahalli (Rs 256 crore), Yelahanka (Rs 164 crore) and RR Nagar (Rs 153 crore), all of which are located on the outskirts and were hit hard during the recent rains.

On Wednesday, Bommai and some of his cabinet colleagues held a meeting at the BBMP head office. The chief minister has promised to release the funds to remodel the drains.

“I have instructed the officials to prepare a detailed project report (DPR). We want to make sure that remodelling works are completed before the next monsoon,” he told news reporters.

CM upset with SWD officials

Bommai was said to be unhappy with the civic body’s SWD division because officials turned up at the meeting without visiting the flood-affected areas. Officials could not answer some of the questions asked by the chief minister on the ongoing SWD remodelling work, DH has learnt.

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‘Most destructive project’

Leo Saldanha, the coordinator at the nonprofit Environment Support Group (ESG), called the concretisation of drains the “most destructive project” in Bengaluru.

“What the concrete does is it blocks the seepage of water and increase the velocity or speed of the water flow. The water thus becomes a weapon of destruction, affecting families and properties in low-lying areas. This is an unwise engineering model drafted to help contractors and politicians,” he said.

Saldanha instead suggested restoring the drains through natural ways.

“Going by the BBMP’s logic, even rivers should get concrete walls. The wise thing to do is stabilise both sides of the drains by planting trees. There are so many ways to stabilise the sand. This will also help slow down the water flow and purify the water,” he said.

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