The rejuvenation of storm-water drains (SWDs) is one of the major steps touted by the authorities after parts of the city were flooded in August last year when drains overflowed following heavy rain. However, civic experts say the ₹300 crore earmarked in the BBMP budget for construction and maintenance of such drains will only be sufficient for removing silt from a small portion of the drains.
The amount has been earmarked for construction and maintenance of SWDs in Hebbal, Koramangala, Challaghatta and Vrishabavathi valleys. Another ₹50 crore will be set aside for establishing sewage treatment plants to prevent sewage from entering lakes.
Naresh Narasimhan, a member of Citizens for Bengaluru, said the allocation was too little. “It will just cover 10% of the SWD network. Without separating sewage drains from SWDs, there is no point spending money on lake rejuvenation,” he said.
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He added that what was needed was a shared project with the Bangalore Water Supply and Sewerage Board to have all the sewage go into trunk sewers on either side of the drain. “The reason Bengaluru has faced floods is there is no place for sewage, which flows back into lakes,” he said.
This view was echoed by S. Raja Rao, former secretary to the Irrigation Department. “In Bengaluru, the trunk sewer line flows into river valleys and lakes. It is a perennial river of sewage. Until separate channels are made for sewage, it will cost substantially to put up two pipelines to separate sewage; the government could see funds for it under the Smart City plan or under Swacch Bharat,” Capt. Rao said.
He said that until separate channels are devised for sewage, the government should take measures such as building wet wells. “You put up a barrage across the storm-water drain, collect all the sewage, and allow all of it to drain into the wet well,” he said.
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“What do you expect people who live outside the 250 sq.km to do? The city administration should make it a priority to extend the drainage system to all the areas under it so that all the sewage collects at certain concentrated points, from where it can be treated,” he said.
Sidde Gowda, chief engineer (Storm Water Drains), BBMP, said the funds earmarked for 2017-18 would be used to construct 75 km of U-shaped RCC (reinforced cement concrete) drains, bridges and culverts, and for chain link fencing. Tenders are being called for construction of another 150 km, from the previous budget. He said there was no existing plan to work with the BWSSB to build parallel networks or to construct wet wells, but welcomed the suggestion. “Sewage is entering the storm-water drains because the BWSSB is letting untreated sewage into them” he said.