Over 30 lakh metric tonnes of drain silt removed before monsoon, but authorities struggle to find safe disposal methods.
As Delhi races to complete its annual desilting drive before the arrival of the monsoon, the city is facing an unexpected environmental problem. While authorities have removed record amounts of silt from drains to reduce flooding, they are now struggling to find space to safely dispose of the huge quantity of waste.
Officials say the dredged material is no longer ordinary mud. Much of it is mixed with municipal garbage, sewage and other contaminants making it difficult to reuse or dump through conventional methods. Environmental experts warn that improper disposal could create new pollution risks even as the city prepares for heavy rains.
According to the Delhi government, the Irrigation and Flood Control (I&FC) Department has removed 30.91 lakh metric tonnes silt from major and supplementary drains this year, a sharp increase from nearly 19 lakh metric tonnes removed last year. The large scale desilting exercise is aimed at improving drainage capacity and reducing the risk of waterlogging during the monsoon season.
The Public Works Department (PWD) has also made significant progress, completing desilting work along 1,900.15 kilometres of drains out of a total network of 2,125.87 kilometres achieving nearly 90 percent of its target. The city’s largest drain, the Najafgarh drain, alone accounted for 12.7 lakh metric tonnes of removed silt.
Traditional disposal methods no longer sufficient
The biggest challenge now is disposing of the extracted material safely. Officials say earlier methods such as strengthening embankments, filling low lying land, dumping silt at landfill sites or allowing contractors to reuse it have reached their limits. Most designated disposal sites are already saturated, leaving authorities with very few options.
The situation is even more complicated because around 25 mixed flow drains carry both stormwater and sewage. Every year, nearly 3.5 lakh metric tonnes of contaminated silt are removed from these drains. Since the material contains plastic waste, household garbage and other pollutants, it cannot be disposed of like normal soil and requires scientific treatment.
To address the growing problem, the I&FC Department has invited Expressions of Interest (EOIs) from agencies specialising in legacy waste management, bio-mining and bioremediation. These agencies will help develop methods for analysing, processing, treating and safely disposing of the contaminated silt while exploring possibilities for its reuse.
The proposed plan also includes studying the physical and chemical properties of the dredged material, developing treatment technologies preparing implementation strategies and ensuring compliance with environmental guidelines issued by the Central Pollution Control Board (CPCB), the Delhi Pollution Control Committee (DPCC) and the National Green Tribunal (NGT).
PWD Minister Parvesh Sahib Singh recently inspected monsoon preparedness work in Moti Nagar and said every drain, road and flood prone location is being reviewed. He stressed that any shortcomings would be corrected immediately to ensure the city is fully prepared for the rainy season.
Officials believe that removing over 30 lakh metric tonnes of silt will significantly improve the drainage system, help rainwater flow more efficiently and reduce the chances of flooding across Delhi. However, they also acknowledge that unless scientific and sustainable methods for handling contaminated drain silt are adopted, the city could face a growing environmental challenge even after the monsoon arrives.