MUMBAI, June 4 -- As the Brihanmumbai Municipal Corporation (BMC) gears up for one of its most ambitious clean-up missions yet - clearing the vast Deonar dumping ground - a waste characterisation report has laid bare the staggering scale and complexity of the challenge. Spanning 127 hectares in the heart of Mumbai's eastern suburbs, the Deonar landfill holds nearly 18.5 million tonnes of legacy waste - accumulated over decades of unchecked dumping. Now, a 2024 survey commissioned by the BMC reveals that nearly 90% of this waste is practically unprocessable, leaving few sustainable disposal options. Conducted through 50 boreholes and 100 sampled layers, the Rs.1.13 crore survey - carried out by NM Consultants and Engineers Pvt Ltd in collaboration with SKW Soil and Surveys Pvt Ltd - found that "soiled material" accounts for the largest share of the waste at 48.43%. This category includes a fine mix of sand, silt, tiny plastic fragments, broken glass, and organic residues - all measuring less than 10mm in size. Their minute scale makes mechanical recycling and processing nearly impossible. Another 41.3% of the landfill is made up of inert materials, including stones, concrete debris and construction waste - heavy, bulky, and low in degradability. Together, these two waste types constitute nearly nine-tenths of the Deonar dump. With such limited scope for recycling or energy recovery, the vast majority of the Deonar waste is headed straight to low-lying areas for final disposal - a decision dictated by its low processing potential. The task is monumental. To meet the BMC's ambitious timeline of three years, contractors will have to excavate, segregate, and transport at least 25,000 metric tonnes of waste daily - an operation that will test the limits of the city's waste logistics. "The sheer volume and nature of this legacy waste means only around 10-12% can be converted into refuse-derived fuel (RDF)," said an official from BMC's Solid Waste Management (SWM) department. This RDF will likely be supplied to cement kilns, where it can be used as an alternative energy source. Just 9.56% of the total waste is classified as dry, potentially recyclable material - an alarmingly thin margin that offers little hope for large-scale material recovery. The landfill was divided into five zones for the survey, with Zones 1, 2 and 5 abutting a 4-km stretch of creek, Zone 4 near residential areas, and Zone 3 in the interior. The analysis found that Zones 3 and 4 have slightly higher calorific values, making them marginally better candidates for energy recovery - but the overall energy potential of the waste remains low. "Carbon content is critical to estimating energy potential through incineration or gasification," the report notes. "But Deonar's waste shows relatively poor carbon content across all zones." It's not just the solid waste that poses a threat. The leachate - a highly toxic liquid formed as water percolates through the garbage - will also have to be treated before safe disposal. The survey recorded Biochemical Oxygen Demand (BOD) at 390 mg/l, which must be brought down to 100 mg/l for land disposal and 30 mg/l for water bodies. The Chemical Oxygen Demand (COD), currently at 1002 mg/l, will need to be slashed to 250 mg/l. Worryingly, lead and cadmium levels were found to be above permissible limits, posing serious risks to soil and water ecosystems if not properly handled. Mercury, however, was within acceptable thresholds. On May 23, the BMC held a pre-bid meeting with prospective contractors. The civic body has now set a June 23 deadline for submission of bids. Whichever firm takes on the job will be tasked with not just transportation and disposal, but also dividing and mapping the waste zones, identifying suitable dumping areas, and ensuring compliance with environmental safeguards....