title: Leachate plume delineation and lithologic profiling using surface resistivity in an open municipal solid waste dumpsite, Sri Lanka.
abstract: This study presents the use of direct current resistivity techniques (DCRT) for investigation and characterization of leachate-contaminated subsurface environment of an open solid waste dumpsite at Kandy, Sri Lanka. The particular dumpsite has no liner and hence the leachate flows directly to the nearby river via subsurface and surface channels. For the identification of possible subsurface flow paths and the direction of the leachate, DCRT (two-dimensional, three-dimensional and vertical electrical sounding) have been applied. In addition, the physico-chemical parameters such as pH, electrical conductivity (EC), alkalinity, hardness, chloride, chemical oxygen demand (COD) and total organic carbon (TOC) of leachate collected from different points of the solid waste dumping area and leachate drainage channel were analysed. Resistivity data confirmed that the leachate flow is confined to the near surface and no separate plume is observed in the downstream area, which may be due to the contamination distribution in the shallow overburden thickness. The stratigraphy with leachate pockets and leachate plume movements was well demarcated inside the dumpsite via low resistivity zones (1-3 Ωm). The recorded EC, alkalinity, hardness and chloride contents in leachate were averaged as 14.13 mS cm⁻¹, 3236, 2241 and 320 mg L⁻¹, respectively, which confirmed the possible causes for low resistivity values. This study confirms that DCRT can be effectively utilized to assess the subsurface characteristics of the open dumpsites to decide on corridor placement and depth of permeable reactive barriers to reduce the groundwater contamination.
authors.affiliation: a Chemical and Environmental Systems Modeling Research Group, Institute of Fundamental Studies , Kandy , Sri Lanka.
authors.forename: Hasintha Rangana
authors.initials: HR
authors.lastname: Wijesekara
authors.affiliation: b Geological Survey and Mines Bureau , Pitakotte , Sri Lanka.
authors.forename: Sunethra Nalin
authors.initials: SN
authors.lastname: De Silva
authors.affiliation: b Geological Survey and Mines Bureau , Pitakotte , Sri Lanka.
authors.forename: Dharani Thanuja De Silva
authors.initials: DT
authors.lastname: Wijesundara
authors.affiliation: c Department of Agricultural Engineering, Faculty of Agriculture , University of Peradeniya , Peradeniya , Sri Lanka.
authors.forename: Bendict Francis Antony
authors.initials: BF
authors.lastname: Basnayake
authors.affiliation: a Chemical and Environmental Systems Modeling Research Group, Institute of Fundamental Studies , Kandy , Sri Lanka.
authors.forename: Meththika Suharshini
authors.initials: MS
authors.lastname: Vithanage
mesh_terms: D057919:Biological Oxygen Demand Analysis; D002712:Chlorides / Q000032:analysis; D004553:Electric Conductivity; D004784:Environmental Monitoring / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D012037:Refuse Disposal; D062611:Solid Waste; D013188:Sri Lanka; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002712:Chlorides; D062611:Solid Waste; D014874:Water Pollutants, Chemical
keywords: Sri Lanka; electrical conductivity; leachate plume delineation; municipal solid waste dumpsites; resistivity techniques