An illegal dumping site located in Ping-Tung County, Taiwan was selected as the case study site. For the site remediation and decision-making purposes, illegal waste dumps need to be identified before the application of remedial tasks. However, traditional investigation via soil gas/soil sampling is not able to detect buried wastes or containers in a cost-effective and time-efficient way. In this study, a ground-pentrating radar GPR system was utilized to locate the buried wastes under a central frequency operation of 300 MHz. This paper was aimed at ascertaining the feasibility of GPR application on this case study. Based on the results of GPR detection, several highly suspected regions of buried waste were delineated through congregating the sections of abrupt intensive GPR reflectance on each walkpath. Subsequently, the suspected regions were subjected to field sampling as well as laboratory analysis of volatile organic com- pounds, semivolatile organic compounds, and heavy metals. With the aid of GPR detection, several bags of fly-ash-like dust were unearthed in hot spot region. According to lab data of sample analysis, soil samples from hot spot area were abundant in zinc and lead, which were closely associated with the unearthed fly-ash-like dust. The results of an integrated approach of site investigation in an uncontrolled dumpsite were presented to offer suitable information for those who intend to utilize the GPR application on the masterpiece of hazardous waste management.