Revealing subsurface structure at the former municipal solid waste disposal site Leuwi Gajah of Cimahi Town by using geophysical data: a preliminary result

Abstract

Municipal solid waste disposal site Leuwi Gajah, situated in Cimahi, is near Bandung City. It was a vast open dumping site closed in 2006 due to a harmful geological hazard in 2005, causing hundreds of victims’ deaths. After 16 years of the tragedy, Bandung local government planned for the former municipal solid waste to become a food field with high technology that benefits the community around the area. We applied the Electromagnetic Induction (EMI) technique to image the study area’s subsurface structure as a non-invasive geophysical method. We collected apparent electrical conductivity (ECa) and apparent susceptibility data from the study site in a gridded pattern to map their distribution using EM-38 MK-2 technology. We chose three sites to map those parameter values: site 1, site 2, and site 3. Site 1 is cassava cultivation land by the community. Site 2 is the boundary between former waste and non-waste land, and site 3 is the same land as site 1 but has a steeper slope (20°). The selection of sites 1 and 3 compares land at higher and lower elevations affected by the former landfill landslide. Site 2 shows the difference in characteristics between waste and non-waste land.Our research in the study area delivers good results. First, we can identify the boundaries of waste and non-waste material, as shown in the low susceptibility value at site 2. This identification is probably related to the thermo-remanent magnetization that results from burning waste. On the other hand, water content influences the distribution of ECa values. Moreover, topography has effects that cause water accumulation in certain areas at sites 1 and 3. These findings recommend using other geophysical methods to detect the boundary between the waste deposit body and underlying bedrock and to characterize the waste body.