The sink hole formed on C.V. Raman Avenue was the fourth in the past five months. This comes just four days after a large sink hole was reported on the road adjoining Ulsoor lake. The rise in the number of sink holes is raising questions about the cause.
BBMP officials attribute all sink holes to leaking water and sewerage lines below the road.
BWSSB officials concede that the pipelines in some parts of the city are old and they are in the process of replacing them, but argue that the unbridled urban sprawl has increased pressure on the pipelines by several fold. Adding to this is repeated digging by Bescom and telecom operators, which sometimes results in damage to their pipelines.
Experts say both agencies are at fault.
Prof. T.G. Seetharam, Civil Engineering Department, Indian Institute of Science said that while water seepage is one of the chief reasons for sink holes, the faulty design of drains and roads is also a cause. “Each sink hole has to be studied on a case-by-case basis. Mostly, when there is a water seepage either due to leaking pipelines or faulty design of drains, the soil beneath gets compacted creating a hollow space. The surrounding soil sinks into this space, leading to a sink hole on the surface,” he explained.
He attributed the two sink holes on roads above the Namma Metro underground section to disturbance of the soil pattern due to the drilling and laying of the tunnel.
