In a bid to ensure free flow of floodwater, the Water Resources Department (WRD) has accelerated work to clear floating waste and vegetation from various waterways and channels in city, ahead of the northeast monsoon.

The department has so far completed nearly 60% of the work in various surplus courses and waterways across the city and peripheral areas. While the department is keen on completing the work in a week, ecologists suggest that the vegetation cleared from waterways could be converted into manure instead of being sent to dump yards.

On an average, a minimum of 15-20 truckloads of garbage and vegetation were being removed daily from the waterways, the officials said.

Ecologist and soil biologist Sultan Ahmed Ismail said water hyacinth could be converted into manure. Such weeds could be spread in layers and simple techniques using diluted cowdung could turn them into manure.

Sludge for composting

Sludge from Chennai Metrowater’s sewage treatment plants too could be added to water hyacinth for composting. Research is being undertaken for developing other technologies too.

The vegetation should be analysed before composting as those removed from polluted waterways and with presence of heavy metals could only be used for wasteland development. Mere dumping of such vegetation would only generate green house gases, he said.

Officials said about 60 machinery had been deployed for the ₹7.8 crore worth works including in the river mouths of Araniar, Adyar and Cooum to drain floodwater into the sea.

Portions of Kosasthalaiyar river that were breached would also be closed along villages such as Karanodai and Vannipakkam.

Float-mounted machines are being used in portions of Buckingham canal where water depth is more. Silt remains a major challenge and projects are being chalked out to address the issues.

As funds are limited, only vulnerable portions of some of the surplus courses are being deweeded and cleaned.

An official said, “Vegetation removed are conveyed to Greater Chennai Corporation’s yards where measures are being taken to compost them. We plan to continue the cleaning exercise till the end of the northeast monsoon.”