Characterization of Leachate and Its Impact on Surface and Groundwater Quality of a Closed Dumpsite – A Case Study at Dhapa, Kolkata, India

The possible enduring environmental impact of a closed landfill on groundwater and surface water quality depends on the leachate characteristics. Post closure management of closed landfill site is needed for averting the environmental hazards. The present investigation was aimed to characterize leachate and its impact on surrounding water resources of closed dumping site at Dhapa (Kolkata, West Bengal, India). Three sampling points were identified for collection of samples fromand near the closed dumping site. All the samples were examined for pH, TDS, Cl-, BOD5, COD, NH4+-N, Zn, Cu, Cr, Cd, Hg and Pbto study the seasonal variation of significant parameters. The laboratory analysis shows prevalence of high value of TDS (8994.16±6239.2mg/L), COD (4191.66±2282.19mg/L), NH4+-N (1165.93±658.4mg/L), Cl− (4356.65±1304.84mg/L) and two heavy metals viz. Pb (0.56±0.33mg/L) and Hg (0.42±0.44mg/L) in the leachate samples, which have exceeded their respective standards specified in “Municipal Solid Wastes (Management and Handling) Rules, 2000” for disposal of treated leachates. The maximum concentration of afore-said heavy metals viz. lead and mercury are found to be 0.15±0.18mg/L and 0.16±0.28mg/Land 0.23±0.21mg/L and 0.1±0.05mg/L respectively for surface and ground water resources, which have exceeded their respective permissible limits recommended by Bureau of Indian Standards (BIS). The extent of contamination of local water resources necessitates appropriate treatment of leachate before getting discharged and establishes the significance of post closure management of the closed dumpsite.