The siphon system, installed on pilot basis at Varthur Kodi to suppress froth, was rendered defunct as gushing rainwater and sewage saw froth rise over onto neighbouring roads on Sunday morning.
However, it was not just Varthur and Bellandur (at Yemalur and Bellandur villages) that saw an increase in froth accumulation. At Huvinane and Subramanyapura lakes, the froth at the weirs increased much to the shock of residents.
With rains lashing the city over the past week, the inflow into lakes has increased drastically, leading to more volumes of froth being formed. At Varthur Kodi on Old Airport Road, accumulated foam had flowed onto neighbouring roads and were even blown by the wind into nearby commercial complexes.
“Anyone who travelled on the road was covered with froth, which had reached unimaginable heights. It was dangerous commuting there as motorists were swerving dangerously to avoid the flying foam,” said Raghu Muniswamy, a resident of the area.
Incidentally, it was here that the Bangalore Water Supply and Sewerage Board (BWSSB) had installed a system of siphons that was intended to transport flowing water smoothly over the weir, reduce the churning of the fluid and reduce froth. On Sunday, this system was clearly undone as water gushed over the pipes laid and frothed with greater magnitude. BWSSB officials said the system was on “trial” basis and was not expected to handle the heavy outflow of rains. Companies had been called to provide better, more sustainable designs for the system.
Other lakes froth
Similarly, two waste weirs of Bellandur saw foam increase in magnitude. However, unlike in Varthur, the erected 20-ft high mesh kept the froth off busy Yemalur Kodi.
On the outskirts of the city, Margondanahalli (Huvinane) lake — which receives much of the untreated sewage from the Hebbal valley — is seeing winds take froth into agricultural fields. “Our leafy vegetables shrivel the moment the froth falls upon them,” said Muniraju, whose farm is 100m from the frothy lake.
Rains have also seen the 6-acre Subramanyapura lake near Uttarahalli froth. “Frothing in our lakes is going from bad to worse. New lakes are joining the list,” said Sridhar Pabbisetty, CEO, Namma Bengaluru Foundation.
G. Vidyasagar, CEO of Karnataka Lake Conservation and Development Authority, said the civic body has been asked to demolish and remodel the inlet of the lake as the design caused the flowing sewage to churn. “In Varthur, however, the foam problem will continue until rejuvenation efforts, which will take at least nine months, bear fruit,” he said.
