Mumbai’s GMLR tunnel borers to be named after the city’s oldest lakes — Tulsi and Vihar

Tulsi and Vihar. The two Tunnel Boring Machines (TBMs), which will excavate the Goregaon Mulund Link Road (GMLR) project’s twin tunnels, are likely to be christened after Mumbai’s oldest man-made lakes, which cater to the city’s potable water supply.

According to Brihanmumbai Municipal Corporation (BMC) officials, the 6.65-km-long twin tunnels — which will run beneath the Sanjay Gandhi National Park — are slated to come up between Tulsi and Vihar lakes. “Considering the alignment of the tunnels between the two lakes and their rich history, we are keen to name the TBMs after Tulsi and Vihar,” a senior official privy to the developments, told The Indian Express.

The proposed GMLR tunnels are situated approximately a kilometre away from the Tulsi and Vihar lakes.

Speaking to The Indian Express, BMC officials said the first TBM boring the tunnel on the north-side, which will run parallel to the Tulsi lake, is set to be named Tulsi. “Meanwhile, the TBM on the southern-side is likely to be named after the Vihar lake,” an official added.

As an alternative east-west link in the city, the BMC is undertaking works of the 12.20-km GMLR project which will connect the Western Express Highway in Goregaon and Eastern Express Highway in Mulund. While the project comprises four phases ranging from flyovers to clover-leaf rotary, the 6.65 km-long twin tunnels form a crucial link of the project. The twin tunnels will be launched near Film City, borrow beneath the SGNP and pass a complex geography of hillocks, forests and the two potable water reservoirs — Tulsi and Vihar.

The story of Tulsi and Vihar

Commissioned in 1860, Vihar lake is the oldest man-made lake of the city whose origin coincides with the growth of erstwhile Bombay.

Dr Madhu Kelkar, who has extensively researched on the history of the water management system in colonial Bombay, said, “Before the lakes were established, Bombay would traditionally draw water from tanks and wells situated across the city. However, after 1845, Bombay witnessed phenomenal growth and a massive shortage of water was felt. Even from the engineering perspective, as growth happened, the corporation felt the need to bring water from outside the island city. Eventually, the Vihar lake was constructed between 1856 and 1860.”

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However, within years, the government in Bombay realised that Vihar was unable to quench the city’s growing demands. “Soon after Vihar lake, another shortage was felt because of the cotton boom, textile mills among other developments. People started complaining about inadequate water and at some point, Vihar was also not considered safe as the construction had come to doubt. Therefore, the corporation as an auxiliary planned the Tulsi lake in early 1870s until another source was conceived,” Dr Kelkar added.

After a seven year-long period of construction, water from Tulsi lake was formally let into Bombay by the erstwhile Governor, Sir Richard Temple Bart, on March 15, 1879.

According to The Bombay Gazette records, Vihar lake was constructed at a cost of Rs 65 lakh. “The total cost of Vehar water works was 65.5 lacs but the government gave up 20 lacs and charged the municipality 45 lacs as the original estimates had been considerably exceeded,” read a Bombay Gazette report from March 1879. Meanwhile, records show that a cost of Rs 40 lakh was sanctioned by the corporation, and the Government of Bombay, for the additional work on construction of Tulsi lake in 1875.

Over a century since their establishment, Tulsi and Vihar — situated within the forests of SGNP — continue to cater to Mumbai’s daily potable water demands. As per BMC data, presently, Vihar lake supplies 90 million litres of water daily (MLD) while the Tulsi lake supplies 18 MLD potable water in Mumbai.

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Developments on the TBM

About 1.1 km away from the Vihar and Tulsi reservoirs, the upcoming GMLR tunnels will be dug using the two TBM machines. A study report submitted by IIT Bombay’s Earth Science department maintained that the construction of the tunnels will have no impact on the reservoirs, following which the alignment was finalised.

While the official name for the new TBMs is yet to be formalised, the proposal of Tulsi and Vihar has obtained nods from the top civic brass including BMC commissioner Ashwini Bhide.

Currently, the civic body is assembling spare parts of the two TBM machines at the Film City launch shaft site in Goregaon, where the tunnels will be launched. Work on the assembly of the first TBM — on Tulsi lake side — is expected to be completed by second week of June after which the machine is slated to undergo comprehensive Site Acceptance Test (SAT) to test for the stability and performance.

While the first TBM was slated to be launched in June, it has been delayed owing to ongoing works and water lines.

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The naming of new TBMs marks a continuation of the administration’s legacy to name its major TBM machines. Previously, the BMC had named the TBM used to bore the twin tunnels of coastal road ‘Mavala’ after Chhatrapati Shivaji Maharaj’s mountain warfare experts hailing from the indigenous Koli and Kunbi communities. Earlier this year, the 13.34-mr TBMs — Arjun and Nayak — were launched by the MMRDA as a part of the Thane Borivali road project.