Friday, 16 August 2019

Mapping of plumes at MSW disposal sites


Research paper review

Background and Goal of Study
Municipal solid waste disposal sites can be sources of groundwater contamination and the contamination problems are more likely to occur in humid areas, where the moisture available exceeds the ability of the waste pile absorb water.
This paper covers the Geo-electrical imaging of Subsurface to get know about the subsurface pollution quantitively and This paper discusses the results of the 2-D resistivity imaging which were conducted to identify and outline the extent of contaminated soil and leachate plumes, as well as to assess the capability of the 2-D resistivity imaging as a pre-characterization tool for tracing the properties of disposed waste and its severity underneath a capped landfill sites.
The surveys were conducted using ABEM SAS1000 resistivity meter and LUND Automatic imaging system and the measured resistivity profiles were interpreted using 2-D resistivity inversion program (RES2DINV)
Leachate Definition: liquid that is generated from water percolating through a solid waste disposal site, accumulating contaminants, and moving into subsurface areas. A second source of leachate arises from the high moisture content of certain disposed wastes. As these wastes are compacted or chemically react, bound water is released as “leachate.”

Methodology
The resistivity data acquisition used a two-dimensional resistivity imaging technique. Both the SAS1000 resistivity meter and ABEM LUND automatic electrode selector system was used in these studies. The meters were connected to a total of 61 steel electrodes, which were laid out on a straight line with a constant spacing via a multicore cable. The Wenner equal spacing electrode array was used for this survey. The Lund system automatically selects the four active electrodes used for each measurement.
Resulting 2D Geo-Electrical Image interpretation
Underground soil or water that has been contaminated by leachate usually has a significantly lower resistivity value, which is indicated by the colours in the above Fig.
The higher resistivity Value indicate that the soil is pure or Have Non degradable waste
 Resistivity of some common rocks and soil materials (Material Resistivity (ohm-m))
 Alluvium 10 – 100 (ohm-m), Sand 60 – 1000 (ohm-m), Clay 1 – 100 (ohm-m), Groundwater (fresh) 10 – 1000 (ohm-m), Granite 5000 – 1,000,000 (ohm-m).

Results Discussion of three sites which 2 D image has been generated
The Geo-electrical imaging method was used to map the contaminated subsurface soil and ground water at three selected municipal solid waste disposal sites in Malaysia. The sites include Ampar Tenang open-tipping site, Bukit Kemuning (BK) capped landfill, and Taiping landfill (TL), all located in Malaysia where a total of twenty-two 2-D resistivity lines were surveyed. The migration of leachate plume at Ampar Tenang site was traced in form of low resistivity zones (with resistivity less than 2.0 ohm-m) of decomposing waste bodies saturated with highly conductive leachate. At the Bukit Kemuning landfill site, two plumes of a reasonably high conductive leachate have been traced. The resistivity images indicate that the subsurface soil and groundwater within Taiping Landfill area has been contaminated by leachate, which appears to have migrated outside the landfill site.

Conclusion
The 2-D direct current resistivity imaging technique has been successfully used in this study to map the contamination plume and to characterize the landfill sites in terms of subsurface resistivity distribution of the waste material and soil underneath the vicinity of each landfill site. The interpreted resistivity section which correlates well with the actual profile of the excavated part of the site (Bukit Kemuning), suggests the potentiality of 2D resistivity imaging technique as pre-characterization tool for mapping subsurface contamination in the vicinity of waste disposal sites.

Recommendation
However, the complexity of subsurface conditions beneath contaminated lands requires a multidisciplinary approach combining the systematic and careful application of hydrogeological, chemical and environmental geophysical techniques.

Reference:


Mapping of contamination plumes at municipal solid waste disposal sites using geoelectric imaging technique: Case studies in Malaysia. Samsudin et al. / JOSH (2006) 13-22.

Review by,
Kamran ullah Khan 


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