In the midst of intense rainfall and the expectation of more rain, Calcutta has not altered.

Piles of plastic waste had filled drainage pumping stations during the deluge of September 23, when the Met office recorded 252mm of rain in five hours.

The Kolkata Municipal Corporation (KMC) had to remove four truckloads of plastic from the drainage pumping station at Palmer Bazar. It was an identical picture in other drainage pumping stations, officials had said.

As the forecast of rain in Calcutta on Wednesday, caused by Cyclone Montha, became known, engineers and officials of KMC became worried about whether the drainage pumping stations would choke on plastic waste once again.

This time, the city was spared from heavy rain till Thursday evening.

“On a day of heavy rain, four trucks are required to remove the plastic that was accumulating at Ballygunge Drainage Pumping Station. The waste flows into the pumping station with the storm water. On a day without rain, we need at least one truck to remove the plastic waste that comes in with the dry weather flow,” said a KMC official.

“There is so much plastic waste going into the city’s underground sewer network,” said the official.

KMC officials said each drainage pumping station has a screen, a mesh of wires, that prevents plastic from reaching the pumps. “If the plastic reaches the pumps, it will damage the motors,” said an engineer.

Engineers said if a pump stops working, it will have to be lifted for repairs. This process can take hours.

Five truckloads of plastic waste were found floating on the storm water following the rain on September 23 at the Thanthania drainage pumping station.

“We have men in the drainage pumping stations who remove the plastic waste that gets stuck in the sieves,” an official said.

The sieves or screens had to be built because the civic body found heaps of plastic and other solid waste entering the stations along with rainwater.

The KMC deploys men to clean manholes and gully pits at intervals. They pick up and remove the plastic, yet waste is again found the next time the covers of manholes and gullypits are opened.

About 4,500 tonnes of waste is generated in the Calcutta municipal area alone every day, out of which roughly 280 tonnes is plastic waste, a KMC official said.

Not all of it reaches the Dhapa waste disposal ground or the processing units set up in Dhapa. A civic official said only 200 tonnes reach Dhapa.

“The rest eventually find their way into the underground drains or water bodies or vacant grounds,” said the official.