Malad tunnel under repair,three months after rupture

Eighty-seven days after the Malad tunnel was punctured,repair work finally picked up on Sunday as five specialised divers of the Hindustan Construction Company went 250 feet underground.

Eighty-seven days after the Malad tunnel was punctured,repair work finally picked up on Sunday as five specialised divers of the Hindustan Construction Company went 250 feet underground. The tunnel,punctured February 12 due to the digging of an illegal borewell,has been leaking almost five million litres everyday.

On Sunday,the BMC and the HCC that built the tunnel in 2004,cut supply off a 2.5-km stretch of the 12-km tunnel and let the divers inside to assess the damage to the 3000-mm RCC structure. They realised that the punctures were along the side,not on the upper surface as earlier presumed.

“With the help of CCTV footage on Friday,and then when the divers went inside on Sunday,we realised the punctures have not been formed in a proper round hole on the top of the tunnel,but on its side,and it has been punctured at two spots. This has made the repair much more technically challenging,” said an executive engineer of the BMC’s hydraulic engineering department.

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The divers entered from Liberty Garden,cutting open the upper dome. They were sent on an initial inspection with oxygen cylinders and torches.

For actual repairs,the HCC is erecting a ventilation system and a lighting system inside the tunnel. This has been completed on the 250-foot vertical shaft,and then horizontally 200 metres,with another 500 metres to go till the spot of the rupture. “It is difficult to carry heavy oxygen cylinders and torches,so we had to erect the system. It will be completed by Monday evening,with bulbs every 2 metres,” said the official.

Using the German engineering method of “grouting”,the punctured spot will be sealed by injecting and spraying chemicals inside and outside,with steel patching inside. To prevent subsoil water from entering the tunnel,the borewell will be packed with binding chemicals. German engineers,too,are on the site.

The tunnel,from Bhandup Complex to Liberty Garden,supplies water to Malad,Goregaon,Kandivli and Jogeshwari that are currently facing water cuts. Repair is expected to be complete in 15 days.

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