In a first, the Brihanmumbai Municipal Corporation (BMC) successfully carried out lake-tapping at the Modak Sagar lake in Thane on Wednesday afternoon. Through this method, the civic body aimed to increase the water intake level and also increase the water pressure for a better supply to the city in the coming months.
As per the civic body, this project will enable conveyance of additional 455 million litres per day (MLD) water from Middle Vaitarna dam and 440 MLD from the proposed Gargai Project, making it a total of 895 additional MLD of drinking water for the city.
The process of lake-tapping involves excavating the tunnel till the lowest level, and then blasting the final protective rock to allow the water to flow from the lake into the well in a force. For this process, the civic body had created three separate layers. While the initial two were tapped with a different method, a dynamite explosion was undertaken for the last layer.
The BMC had excavated around 131 meters of the inlet tunnel. “The work could not be undertaken manually as it was difficult to see through the tunnel. We had to bring in specialised contractors to undertake the explosion on Wednesday. Increasing the intake level was imperative for better force of water supply in the city,” said Ashok Tawadia, deputy hydraulic engineer (planning and control) of the civic body.
The approximate cost of the project is Rs 222 crore. As a Jawaharlal Nehru National Urban Renewal Mission (JNNURM) sanctioned project, the central government has funded 35 per cent of the project and the state government has funded about 15 per cent.
BMC had also taken technical assistance from a geological expert and two state government engineers who had earlier undertaken a similar method at the Koyna dam in Satara in the year 2012.