1.1 million litres of water in an under-construction pit at AAC led to its collapse
MUMBAI: Monday's unprecedented downpour put to test the Aqua Line of Mumbai metro, where 1.1 million litres of water accumulated in its last station – the Acharya Atre Chowk (AAC) – which was only partially opened to public. There are six entry-exit gates to the station, of which two are open for public; four are under-construction. The heavy rain led to one of the under-construction gates flooding, leading to services to AAC being suspended.
The weight of the rainwater in the pit led to its collapse, flooding the station premises below. The temporary protective concrete retaining wall around it also failed to withstand the force of water. Officials from the Mumbai Metro Rail Corporation Limited (MMRCL) said the reason behind such an eventuality was because the area around Worli recorded 90 mm of rainfall in an hour (9.30-10.30 am); high tide alongside added to the problem. The AAC station is expected to reopen in a couple of days.
'The deepest point of this station is at 22 meters where water and slush has reached. High powered pumps are being used to flush it all out. Cleaning this portion is our first priority,' said Ashwini Bhide, managing director, MMRCL, on Tuesday. She also expressed optimism about reopening the AAC station in a couple of days.
People in the know told HT that the retaining wall was built only to withstand 'normal rain', and that a red alert is sounded if rainfall exceeds 25 mm in an hour. This under-construction entry-exit point is located along Dr Annie Besant Road, where an overflowing stormwater drain also compounded the problem.
'The work of fitting the base slab on this under construction portion was pending. So, we created a pit with the retaining wall. 1.1 million litres of rain water was too much for this temporary pit to contain, which collapsed and crashed onto the station concourse. No other station on the underground Line-3 suffered similar problem,' said an official from MMRCL.
An officer, who did not wish to be named, told HT that slush and water had entered the lifts and escalators, 'which are being cleaned and will be tested on Wednesday'.
Pumps have been deployed 24*7 to clean the tracks. The officer also said that a permanent protection wall is being built around the damaged part of the station, which will take a couple of months to be ready. This will help prevent any ingress of water in future. Other stations of this route – Worli to Aarey JVLR – are protected, the officer added.
While two entry-exit points are sufficient to service the station's existing passenger load, this incident has raised concerns about its safe operations, drainage systems and overall monsoon preparedness especially when MMRCL claimed earlier that the high profile ₹37,000-crore corridor was flood-proof.
'Passengers have no cause for worry on the underground metro corridor. Trains can be reversed on the southern end inside the tunnel, where water has not entered,' said the official.
On Monday, close to 40,000 passengers travelled on Aarey JVLR-Worli route while on Tuesday over 45,000 passengers travelled on this line.
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