Identification of Groundwater Contamination by Hydrocarbon from Gas Station at Caturtunggal Area using Geoelectrical Methods

Abstract

Groundwater exploration is a method to produce the needs of clean water. Most of the Indonesian people use groundwater for daily consumption. Groundwater contamination can occur because of various human activities that produce pollutants. One of the activities that can affect the quality of subsurface water is the existence of a Gas Station. Caturtunggal is one of the areas in the Sleman Regency which has a dense population. Caturtunggal has varied activities such as hotels, restaurants, shopping centers, and education. If there is pollution due to hydrocarbons, the impact that occurs can pollute the densely populated area. Geophysics methods are one of the techniques to explore the groundwater, specially geoelectrical resistivity. The objective of this research is to identify the existence of hydrocarbon in the groundwater around gas stations using the geoelectrical resistivity method. This research was conducted with the methods, i.e., observation, mapping, and geophysical method, geoelectrical resistivity. The result from geoelectrical resistivity analysis shows that contamination of hydrocarbon does not occur in the groundwater. In general, the lithology of the composting area of the study area consists of loose sediments with coarse to very coarse grain sizes, which are represented by large resistivity values. At the measuring point 1 to 4, there is no indication of the presence of groundwater pollution, which is represented by the resistivity value of the aquifer zone in the Cilician area, which is still in the resistivity order of 10 1 -ohm meters. The existence of aquifers in the research area is at a depth of 12 meters to 15 meters. It was getting deeper towards the south. However, collaboration data is required to analyze more details about the contamination.