Groundwater contamination by total petroleum hydrocarbons (TPH) represents a severe environmental and public health challenge, particularly in suburban areas of Java Island, Indonesia. This study assessed leakage from a fuel storage tank that resulted in widespread contamination of residential wells, with concentrations reaching up to 8024 mg/L. This result surpasses international regulatory limits. To address this issue, an in situ remediation approach was implemented by injecting the surfactant Tween 80 into five contaminated wells (GW1-GW5). Within 7 months of monitoring, this method achieved 85.5-100% TPH removal in contaminated wells, confirming its effectiveness for field-scale groundwater restoration. In addition, geophysical testing using the Automatic Audio-Frequency Magnetotelluric (ADMT) method confirmed persistent contamination at GW4, where low resistivity values revealed subsurface heterogeneity and basin effects that chemical monitoring alone could not explain. Moreover, the integration of ADMT with chemical monitoring demonstrated its effectiveness not only for aquifer exploration but also as a validation tool for contaminated soil remediation. These findings highlight the urgency of addressing petroleum hydrocarbon pollution and underscore the potential of surfactant injection, supported by geophysical monitoring, as a scalable and sustainable strategy for groundwater remediation in complex geological settings.