What do we do with Chennai’s legacy waste?

Waste Management in Landfills

chennai legacy waste
Legacy waste in dumpyards pose a huge hazard to residents and local ecosystem. Pic: Aruna Natarajan

Legacy waste in Chennai’s dumpyards has become a ticking time-bomb making headlines over the years. The latest in a long line of incidents at Chennai’s dumpyards was a fire that broke out in Perungudi in the last week of April. The blaze spread across 15 acres and took four days for the Greater Chennai Corporation (GCC), Fire and Rescue Services and the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) to put out. 

While much is talked about waste management and the source segregation of household waste, such incidents bring into sharp focus the scale of legacy waste at the dumpyards in the city and how little success there has been in tackling it. 

Status of Chennnai’s dumpyards

At present garbage generated in Chennai is dumped at two dumpyards – Kodungaiyur, spread over 269 acres, and Perungudi, spread over 200 acres. With both the landfills being in use for almost three to four decades, 2,400 to 2,800 metric tonnes of waste is being disposed of at each site daily.

In 1985, the civic body started dumping 20 tonnes of waste per day in Kodungaiyur and in 1989 the first sewage treatment plant (STP) was built on the fodder farm land. These combined factors started the destruction of the original pulpannai (turf) in the area. In a matter of years, the lush green pulpannai had turned into a brown hill of garbage.

Similarly, the dumping of waste in Perungudi has had a profound effect on the ecologically sensitive Palikkaranai Marshland found nearby. The marshland has shrunk in size to 300 heactares from the original 8000 hectares, in part due to the spread of encroachments including the dumping site.

The estimated volume of legacy waste at present in the Perungudi dumpyard is 30.60 lakh cubic metres, while the Kodungaiyur dumpyard has around 64 lakh cubic metres of legacy waste. 

chennai dumpyard
With improper source segregation, more waste gets added to the dumpyards daily. Pic: Aruna Natarajan

Legacy waste a source of pollution

According to a study from the Centre for Science and Environment titled ‘Clean it right – Dumpsite management in India’, waste in dumpsites gradually decomposes by a combination of biological, chemical and physical processes. During the process of decomposition, two major emissions of primary concern – leachate and landfill gas which affect the environment in the following ways

Leachate is polluted water that emerges at the base of dumpsite waste. It is formed in two ways. Rainwater landing on the waste flows over and through the waste and soluble substances are dissolved in the water. Also, some of the decomposition reactions in the waste produce liquid that is acidic. Some substances, such as toxic metals, tend to dissolve more easily in acids, making the final leachate more harmful. Leachate enters watercourses and may be consumed by humans in drinking water, for domestic purposes or irrigation, exposing users to these pollutants.

Dumpsites in general receive mixed waste. The process of decomposition creates anaerobic conditions due to the presence of plastic and other large-surface-area materials. These anaerobic conditions lead to the formation of landfill gas, comprising a mixture of carbon dioxide and methane, both of which are greenhouse gases that contribute to global climate change. Methane is known to be more potent as a heat-trapping gas. It is also flammable with slight exposure to flame or high temperatures. In extreme cases, the gas can build up in a landfill and explode, with risk of devastation.


Read more: Yet another fire at Kodungaiyur, but no lasting solution in sight


Biomining, the solution with pitfalls

An oft cited solution to the mammoth task of clearing legacy waste in cities is biomining. Biomining is the process of using microorganisms to extract materials of economic interest from legacy waste. The prime process, however, is to recover soil from decomposed mixed waste. 

In other words, biomining is a process by which previously dumped waste is dug up after loosening by harrowing and then processed to recover valuable recyclable scrap while also recovering landfill space. The end product, likely to be soil, is rid of toxic materials and hence becomes reusable.

Removal of legacy waste is a herculean task. “It is not only a mixture of waste that is dumped there. For every two layers of legacy waste, debris from construction and demolition waste has been used to compact because there was a need for something to hold the waste together so that the waste does not dissipate. It could not be dug open or unearthed that easily,” said Dr Jayshree Vencatesan, Managing Trustee of Care Earth.

Citing the surveys conducted by Care Earth since 2002 in Perungudi, she pointed out the medical wastes also continue to be dumped there. “Physical removal of such wastes is not going to help. Projects like biomining are being done under the assumption that the land is flat. In the case of Perungudi, we still do not know how much of the waste has sunk into the marshland,” she noted.

With biomining, the useful inorganic waste in the dumps will be sent to recycling centres, while the organic part of the soil will be used for agriculture or creating manure. 

Explaining how the plastic in legacy waste gets inseparably mixed, Satyarupa Shekhar, Asia Pacific Regional Coordinator for Break Free From Plastic, said “Plastic is scientifically established to degrade very quickly. It basically does not biodegrade but breaks into smaller particles and gets mixed with all the materials. The problem with biomining is the assumption that we are removing all the plastic from the waste. The organic part of the soil, which is assumed to be free of toxic plastic substances, is used for gardening and farming. End of the day, these plastic substances enter our food system and also the bloodstream.”

Akin to how the soil becomes unusable despite biomining, citing a 2019 study conducted by Citizen Consumer and Civic Action Group (CAG), she said that groundwater around Kodungaiyur dump site has been highly contaminated. “The problem with legacy waste is that it makes the soil and water completely unusable,” she said.

The inorganic waste which cannot be recycled, is either sent to cement plants or used in projects like ‘waste to energy conversion’ in which the waste is incinerated. The cement plants require good quality waste. A monitoring mechanism on how the toxic mixed wastes are handled at cement plants is the need of the hour.

The problem with incinerators in India is the substandard technology, said Dharmesh Shah, Advisor at Legal Initiative for Forest and Environment (LIFE). “In addition to the emission, the larger question is what would we do with the ash after burning them? The ash is also very toxic and we will need a place to dump it again. What happened in Delhi is that the Okhla dumpyard was cleared, the waste was incinerated and ash was again dumped at the same site. This only led to air pollution,” he said.

Commenting on ‘waste to energy’ projects, he said, “It is just another term for incineration and it is going to have the same impact as incineration.”

What after biomining?

In a bid to remove the legacy waste and reclaim the marsh land, biomining works are underway in Perungudi. Meanwhile, waste characterisation study, a hydrogeological study to compute the flooding potential at the site, a baseline environmental study to determine presence of heavy metals and toxic substances in the soil, water and air and a socio-economic survey are soon to be conducted in Kodungaiyur prior to biomining, said a corporation official. 

According to recent news reports, following the biomining works which are underway in Perungudi, an eco-park or a forest is likely to come up following the reclamation.

“My worst fear is that the local body would plant saplings and convert it into a park. The Pallikaranai marshland has two unique features – the unique hydrology which is partly saline and partly fresh waste and the second, as a result of such unique hydrology the marshland has a wide diversity of habitats. It serves as home to 114 flora and 223 fauna species. Plantation on this land will make it a single habitat area which will attract only a few sets of birds. This could also have other ecological consequences,” she said.

When asked if the marsh land could retain its original shape after the biomining process, she said that it is impossible and is gone forever. 

S Janakarajan, Professor of Economics (Retired) from the Madras Institute of Development Studies (MIDS, Adyar), commented that natural hydrology could be retained after reclamation but it will not happen overnight. “It is going to take a very, very long time,” he said.

Need for Circular Economy

While dealing with the legacy waste is by itself a huge task, thousands of tonnes of fresh waste which remain unsegregated despite the attempts to implement decentralised waste management systems, also pose a huge challenge and further complicate the process.

A sanitary worker, S Balakrishnanan from Zone 9, who has been working on contract basis for over a decade, said that though there are different bins used for collecting bio-degradable and non-biodegradable wastes and even when residents segregate the household wastes at source level, the wastes are later mixed together and taken to dumpyards without being processed.

“Similarly, the compactor vehicles, which are mostly used only at night times, carry the mixed garbage from the bins straight to the dumpyards at Kodungaiyur and Perungudi,” he added.

“‘Use and throw’ has become the habit of urban citizens. In particular the middle and upper middle-class population have been intoxicated in a way with increasing habits of consumerism. They are decently employed people. They earn money and they spend. Who handles all the waste they generate? The answer is obvious”, said Janakarajan, stressing that every individual should take ownership of their garbage and ‘see through their own waste’.

“I would consider all the garbage as a resource and put it in a circular economy where by-products like manure could be made. Unless a product is processed from purchase to end through a circular economy, it could not be called solid waste management,” he said.

While some people argue that manufacturers should not use plastic. They are selling only because there are consumers who buy the product. Though the onus is on both the ends, people should have some sort of mechanism to protest against such sales, he added. 


Read more: Pallikaranai is struggling to survive, and so is life around it


Decentralised infra must be in place

The Solid Waste Management Rules are very clear. It mandates source segregation and decentralised waste management systems. However, municipal corporations have not been able to implement it effectively. “Even when all the waste generated is segregated into separate streams, there are few categories like low quality plastics which could not be recycled. We need policy level decisions to eliminate such waste,” Dharmesh said.

Pointing out examples from Bangalore and Pune, he added that unless a decentralised infrastructure is in place, biomining will only be yet another fancy project where crores of money is dumped in.

“Not only in Chennai but also across the country and globe, solid waste management contracts are being given only for waste collection and disposal. When contracts are worded that way, it only means that the contractor should collect the waste from the houses and dump it in a specified location. The contracts should rather include scientific processing of all kinds of waste,” said Satyarupa

Jayshree suggested that multidisciplinary experts should be roped in to deal with legacy waste as even a margin of error could have irrecoverable impacts on the environment.

Vamsi Shankar Kapilavai, Senior Researcher who heads projects in Solid Waste Management with Citizen Consumer and civic Action Group (CAG) said that the companies should come up with ‘reuse and refill’ initiatives, while the residents should ensure source segregation. He also added that the reclaimed land in areas near the Pallikaranai marshland should not be used for anything. It should be left as marsh land which will help in retaining the effects of climate change naturally in the long run.

Responding to the critiques on source segregation, a corporation official said that the civic body is implementing the source segregation strictly now and is aimed at preventing at least 1,000 metric tonnes of organic wastes from reaching the dumpsites. 

Meanwhile, the GCC has also announced that a sum of Rs 100 per day would be levied as fine on each household that fails to segregate the wastes at source level. A sum of Rs 13.85 lakh fine has been collected in April from 573 persons for dumping the household and construction waste in public places. 

Speaking on the legacy waste management, the officials also assured that the biomining in Perungudi is done with caution following all the rules and the biomining in Kodungaiyur would be carried out after the aforementioned studies.

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About Shobana Radhakrishnan 36 Articles
Shobana Radhakrishnan is a Senior Reporter at Citizen Matters. Before moving to Chennai in 2022, she reported for the national daily, The New Indian Express (TNIE), from Madurai. During her stint at TNIE, she did detailed ground reports on the plight of migrant workers and the sorry-state of public libraries in addition to covering the renowned Jallikattu, Tamil Nadu Assembly Elections (2021) and Rural Local Body Polls (2019-2020). Shobana has a Masters degree in Mass Communication and Journalism from the Pondicherry Central University and a Bachelors in English Literature. She keenly follows the impact of development on vulnerable groups.