In order to prevent soil and groundwater pollution, ensure the sustainable use of soil and groundwater, and fulfill the regulations of Soil and Groundwater Pollution Remediation Act, the Environmental Protection Administration (the EPA) initiated the Project of Investigation of Soil and Groundwater Pollution for Gas Stations (5th Phase)- Plans A and B in 2009. Sinotech Engineering Consultants, Ltd. (Sinotech) was entrusted to carry out Plan A, covering Central and Northern Taiwan, while MWH Taiwan was assigned to carry out Plan B (this Project), covering Central and Southern Taiwan. Each consultant completed the investigation of soil and groundwater pollution at 21 gas stations, which made a total number of 42 stations investigated. This Project (Plan B) was to investigate soil and groundwater pollution for 21 gas stations in central and south Taiwan as reference in the follow up control activities. This project was implemented in three phases. The 1st phase was to measure the oil vapor density of soil vapor monitoring well. Based on the results of 1st phase, the 2nd phase foucus on high pollution potential area which screening of 1st phase to conduct the detection and analysis of soil samples. In addition, groundwater samples from temporary groundwater sampling wells were also detected and analyzed. Based on the results of 2nd phase, the 3rd phase selected the gas stations with the pollutants’ density in the groundwater higher than the control standards to install standard monitoring wells and detect and analyze groundwater samples. The 1st phases was to test the basic functions of 349 soil gas monitoring wells, measure the oil vapor densities by using LEF, PID, and FID and the soil vapor of 7 samples by using PID and FID in 21 gas stations. The results indicated that the oil vapor density detected by soil gas monitoring wells in 5 gas stations with the high pollution potential (B Class). According to the EPA’s requestion, two more gas stations also need for investigation in the 2nd phase. Therefore the total amount of investigated gas stations of 2nd phase are 22. The 2nd phase conducted the detection and analysis of 74 soil samples and 57 groundwater samples from simple wells in 22 gas stations. As a result, it was concluded that the pollutants’ densities in the soil of the 11 gas stations had reached the control standards; the pollutants’ densities in the groundwater from the simple wells of the 7 gas stations had reached the control standards. The 3rd phase was to investigate the 3 gas stations. The pollutants’ densities in the groundwater of the 11 of them had reached the control standards. As a result, it was concluded that the detected pollutants’ concentration in soil of the 11 gas stations were higher than the control standards, and the pollutants’ concentration in groundwater of the 3 gas stations out of the 11 gas stations were higher than the control standards. All of them should be controlled in accordance with the Soil and Groundwater Pollution Remediation Act. Besides, a correlation of the basic data of the gas stations surveyed in the project, groundwater pollution control facilities, and their periodic declaration reports, vis-à-vis the pollution potential of the gas station was conducted and the results provided as references for the EPA in the follow up activities of administrative control measures.

Gas Station Investigation, Soil, Groundwater