Geochemical and GMS – Modeling Approach in Characterization of Anticipated Environmental Threats of Leachate from an Open Dumpsite, Niger Delta, Nigeria

Dumping of solid waste in open dumpsites is widespread in developing countries. A major disadvantage of this waste management system is the generation of leachate; this has been a primary concern to the environment because it can percolate into the groundwater and consequently contaminate it. In this work, leachate and groundwater samples were collected from a dumpsite in Asaba and its adjoining area to ascertain the conceivable effect of leachate percolation on groundwater quality. The results of physicochemical and heavy metals analyses of leachate confirmed that its characteristics were highly variable, with severe contamination by organics, salts, and heavy metals. The BOD5/COD ratio in leachate varied from 0.08 – 0.12 mg/l, suggesting a dumpsite yet to attain final maturation but is in its late stage of the methanogenic phase. The low BOD5/COD ratio value (0.08 mg/l) observed for leachate shows some microbial activity in the decomposing leachate yet to stabilize. The plume model showed leachate infiltrating beneath the dumpsite up to depths greater than 20 m after one year. The low concentrations of significant cations, anions, heavy metals, and COD in groundwater likely indicate that leachate did not significantly affect groundwater quality. However, specific parameters such as Fe exceeded the WHO limits; the source of Fe may be related to the geology of the area. The good protective capacity around the dumpsite and groundwater mounds was a barrier against inflow from contaminated leachate.