1. The use of 2D Resistivity Imaging Technique to investigate subsurface contamination at Sungai Besar landfill site, Selangor ,Malaysia
Tan Chin Lee, Abdul Rahim Samsudin & Umar Hamzah
School of Environment & Natural Resources Science
Faculty of Science & Technology
National University of Malaysia
UKM Bangi

2. INTRODUCTION
Geophysical surveys using electrical imaging methods have been used in many application ever since the interpretation techniques have been developed by Loke and Barker (1996a).
A laboratory measurement was carried out for estimating the resistivity of clay and leachate.

3. 3. A waste disposal site at Sungai Besar, Sabak Bernam Selangor was selected for this study
4. Four resistivity lines were arranged in the NE-SW directions and three lines were in NW-SE directions. The length of each survey lines were between 200 to 400 metres.
5. Maximum depth of soil resistivity information are approximately about 30 to 60 metres.

8. EXPERIMENTAL STUDY Field measurement
-Geoelectrical imaging surveys are normally carried out with multielectrode resistivity system
-In this survey 61 electrodes are deployed in a straight line with constant spacing and connected to a multicore cable.

9. A computer-controlled system (Griffith, Turnbull and Olayinka 1990) is then used to select the active electrodes for each measurement.
The data gathered in this survey is interpreted using an inexpensive microcomputer to provide an inverse resistivity section.

11. Terrameter SAS 1000 system was used for the data collection
-Wenner array electrode confuguration was used to provide a good vertical resolution
- The data collected in the field is interpreted using the computer programme RES2DINV (Loke and Barker 1996b)

12. cable
battery
Terrameter SAS 1000
Lund system
electrode
Connection clip
Battery for Lund system

13. 2. Tank modeling
- Marine clay samples at the landfil site was taken to the laboratory for measurement of resistivity in a tank model of 100 X 100 X 75 cm in size.
- A small scale resistivity measurement were carried out in the tank
-This is followed by subsequent several measurements after one day, One week and one month introduction of leachate into the clay layer.

14. Tank modeling

15. Small scale electrode

16. RESULTS AND DISCUSSION
Field measurement
Solid waste
Clay layer
contaminated clay
leachate
Line 1

17. Line 2 Line 3 Solid waste leachate contaminated clay Clay layer

18. Line 4 Line 5 leachate Clay layer contaminated clay contaminated clay

19. contaminated clay
leachate
Line 6
contaminated clay
leachate
Line 7

20. Tank modeling Fresh clay without leachate A day after putting leachate
Clay layer
Fresh clay without leachate
Clay layer
leachate
A day after putting leachate

21. A week after putting leachate
Clay layer
A week after putting leachate
leachate
Clay layer
A month after putting leachate

22. migration in clay at the waste disposal sites.
CONCLUSION
- This study has been very succesful in determining the extend of leachate
migration in clay at the waste disposal sites.
- Major direction of leachate flow based
on plumes concentration was found to
be towards the sea.

23. ACKNOWLEDGEMENT
We would like to thank the Ministry of Science and Environment for the IRPA grant and to all staff for their help in the field data collection and processing.

24. Thank you