16-11-2017 01:30 PM | Lathika Saju | My Indian Dream
The world’s largest overhead reservoir is undergoing renovation after a century
Did you know that the world’s largest overhead reservoir is in India? This Brobdingnagian tank is situated in Kolkata and is called the Tallah Tank. The sight of the gigantic tank which is said to be heavier than the Titanic is quite fascinating with its colossal structure made of iron, steel and timber.
This engineering marvel has developed only 14 leakages over 107 years of its existence and has withstood the World War II and the great earthquakes of 1934 in Bihar and Bengal. For over a century, this tank has diligently supplied potable water to the residents of Kolkata.
The Tallah Tank was designed by WB MacCabe, the then chief engineer of Calcutta Corporation. It was a major achievement in civil engineering and metallurgy accomplished by Indian firms. While the weight of the structure was about 8,500 tons, it could hold water to the extent of 40,000 tons.
Babu Khelat Ghosh had donated land for the reservoir and subsequently, an adjoining lane was named KhelatBabu Lane. The tank was built at the cost of Rs 11 lakh and materials including the anti-corrosion plates were brought from England.
The unique feature of the tank is that there is only one pipe for filling up and distribution of water. The tank is built in four compartments. When the underground tank at Tallah is spilled over with the incoming supply of water, the surplus water is stored in the overhead tank and again when the water level in the underground tank dwindles it compensates for the loss due to distribution. The tank was placed at a height in order to add pressure to the gravitational flow of the water in the overhead tank.
The tank stands at a height of 110 feet, it is 16 feet deep, spread over 321 feet square and divided into four compartments which are independent of each other and hence can be cleaned or repaired anytime without disrupting water supply.
Now, the century-old tank is being renovated for the first time. A tank built with a budget of Rs 11 lakh is undergoing a Rs 76-crore renovation. The job has been entrusted to Bridge and Roof Co. (India) Ltd which is a central government undertaking.
The two-year restoration project was designed by experts from IIT-Kharagpur and Jadavpur University. A French crane with a height of 130 feet and width of 140 feet has been secured to clean and restore the tank. The machine has the capacity to go 40 feet inside the tank and is also fitted with a sensor.
Once the silt is removed, the rusty rivets and plates will be replaced. The structure on which the tank rests will be reinforced, leaks plugged and all vegetation removed from the timber sleepers. Once the renovation is done, the magnificent Tallah Tank will continue to be the pride of India.
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