Robots fail to tackle blocks of silt in underground drains

One of the robots brought from Italy for the job.

One of the robots brought from Italy for the job.  

Only 750 metres cleared; BMC may miss its monsoon target

The Brihanmumbai Municipal Corporation’s (BMC) plan to clean underground drains using robots has hit a block, quite literally. The robots are unable to tackle the large amounts of silt in these drains, and have managed to clean only 750 metres of the proposed 27 km. The BMC has issued a stop work notice to the contractor. Now, there is no way the civic body will be able to achieve its target before monsoon.

Of the 600-km underground storm water drain network in the city, about 70 km has not been cleaned for decades because of their hazardous nature. These are British-era, medium-sized underground drains that cannot be cleaned using heavy machinery, and are too risky to be cleaned manually. Over the years, silt, debris and trash deposited in them have hardened like cement, leaving little room for water to flow into the existing network and, out. This was found to be one of the reasons behind flooding in the island city.

Therefore, the BMC decided to clean these drains using robots. The civic body appointed a contractor to undertake the work in two years at a cost of around ₹60 crore. Two robots brought from Italy were used for the job. The storm water drain department had targeted to complete about 27-km network before monsoon. One of the areas to benefit from this clean-up was Hindmata junction.

However, the plan seems to have failed. “We had estimated that the drains would be filled about 40% with silt. In case of these drains, it is not possible to gauge the exact situation visually. When work started, we found out that the drains were almost completely choked. They were filled 80-95%,” an officer from the department said.

The robots are not equipped to clean such large quantities of silt, owing to which the contractor has been able to clean only 750 metres of the 27 km planned. “We will now have to come up with a solution. One would be to allow labourers to go inside the drains with hand-held/manually operated devices. But that would require safety measures, which would increase the cost. We don’t want to take risks, especially after the CSMT bridge collapse,” another officer said.

However, the manual operation will slow down the project, and work worth two years may even take six years. Another solution could be to dig up roads and clean underground drains, which is not possible in a city like Mumbai. The department will now be submitting a detailed report to the municipal commissioner, who will take a call on the issue. “It was an experiment that was not done anywhere before. We will need multiple attempts to get it right,” the officer said.

Additional municipal commissioner Vijay Singhal said, “The last time I took a review, work was going on slowly, but it was on. There is a large amount of silt hardened like a stone. I am not aware of this stop work notice. I will have to check.”

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Printable version | May 30, 2020 2:19:53 PM |

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