The BMC five months ago claimed to have conducted a successful lake-tapping experiment at the Modak Sagar lake, which would have increased the water supply to the city by 40 million litres daily (MLD).
But, as it turns out now, the lake-tapping failed and Rs30 crore of taxpayers’ money, which was spent on the project, has gone down the drain. What’s worse: the BMC did not disclose that the experiment conducted on September 3, 2014, had failed.
Lake-tapping involves pulling out water from the lake through an inlet created below or on the side of the lake bed. The inlet is created by drilling a hole in a rock by means of a controlled blast.
Although the project at Modak Sagar did not succeed, the civic body has now decided to spend another Rs17 crore on it. Work on it is expected to be complete by July, said sources.
Currently, Mumbai gets 455 MLD water from Modak Sagar lake. Its lowest drawable limit is 146 metres from the base, which means water can be taken out through tunnels on its side as long as this level is not breached.
The BMC had planned to have another water inlet, or tunnel, at 136 metres, which would have allowed them to pull out an additional 40 MLD water from the lake.
Additional municipal commissioner Dr Sanjay Mukherjee admitted that the lake tapping experiment failed. “It failed and now we are going to undertake dredging work in the tunnel again. It is expected to complete in July,” he said. “After the blast, the rock did not come out [essential for the flow of water into the new inlet] so now we are forced to do it again.”
A source from the water special projects (WSP) department said: “The experiment failed owing to a weak blast. The contractor and technical team failed to do proper assessment and the rock between the tunnel and the inlet did not come out. Also, the work from the tunnel side was not up to the mark and now the BMC has decided to do dredging again.”
The experiment was carried out under the technical guidance of Dr Deepak Modak, chief engineer (civil), hydro projects; and Rajneesh Shukla, superintendent engineer and deputy secretary, hydro projetcs of the water resources department. They were part of the team which had successfully done lake-tapping at Koyna Dam.
When the project was unveiled, in the presence of several VIPs, the authorities released the water from the inlet at 146 metres instead of 136 metres, and no one noticed the difference, said an official.
“There were strict orders from the officers to not give out any information about the flop show and claim that experiment has succeeded,” said a source from the water department.