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:
Review by,
Kamran ullah Khan
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