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This research was conducted to identify subsurface stratigraphy at Institut Teknologi Kalimantan (ITK) area. The information of subsurface stratigraphy becomes more important for minimizing the effects of changes in soil structure. We run the Geoelectrical resistivity method using Wenner-array along four measurement lines. Field data measured consists of electrical current and potential difference to calculated apparent resistivity values. Then, the apparent resistivity data were inverted to obtained true resistivity values. The results showed that subsurface stratigraphy was composed of three main layers. The first layer was characterized by higher resistivity values ranging from 39 to more than 86 ohm-meters interpreted as topsoil. The lower range of resistivity values at the second layer was identified as clay with resistivity values from 9.36 to 39 ohm-meters, while the higher resistivity values ranging from 39 to 86 ohm-meters and marked by Brown to red colour below the surface at the third layer was identified as clay sandstone.

TPA Manggar is a landfill in Balikpapan City. During the rainy season, the leachate discharge entering the processing plant is so large that the collection tub will not be able to withstand the leachate flow rate. To find out the direction of the distribution of leachate waste and the extent to which it has spread and to map the areas at high risk of being contaminated, measurements were taken using the Geophysical method, namely the Self Potential Method (SP). The SP method is based on measuring the self-potential of rocks in the earth’s crust without having to inject an electric current into the soil. Based on this, research will be carried out to determine the mapping of the distribution of leachate flow in the TPA Mangaar area. The results of measurement and processing of self-potential data can be showing beneath the surface in the form of leachate distribution in the study area based on isopotential contour. Based on the results of contour and isopotential map data processing. The highest potential value of this study was 60 mV, while the lowest potential value of this study was -40 mV.

The need for water resources continues to increase from year to year to meet various needs. The availability of water resources is increasingly limited due to seawater intrusion or water pollution. Pancuma Village is one of the coastal areas where it is necessary to study the potential of groundwater, especially during the dry season. One way to determine the presence of the groundwater aquifer layer is by using the resistivity method. This method is an effective geophysical method for shallow exploration so that it can be used to determine the structure beneath the earth’s surface. The configuration used in this study is the Schlumberger configuration. Research in Pancuma Village aims to determine the subsurface stratigraphy of the study area based on the resistivity value and to determine the distribution of groundwater aquifers in the study area. The results obtained from this study are that there are four types of subsurface layers in the study area, namely topsoil, claystone, iron sand, and alternating sandstone with conglomerates which are the aquifer layer in the study area. The resistivity value estimated at the aquifer layer ranges from 119 Ωm - 529 Ωm with a thickness of up to 45 meters.