In order to prevent soil and groundwater pollution, ensure the sustainable use of soil and groundwater, and fulfill the regulations of Soil and Water Pollution Remediation Act, the Environmental Protection Agency (the EPA) planned the Project of Investigating Soil and Groundwater pollution at the Gas Stations in Taiwan(the Fourth Project)- the Plan A and B in 2007. The scope of the Plan A covered central and northern Taiwan and was carried out by MWH Taiwan. The scope of the Plan B (this Project) covered central and southern Taiwan and was carried out by Sinotech.LTD. Plan A and B carried out the investigation of soil and groundwater pollution for 400 gas stations (200 gas stations for each Plan). This Project (Plan B) was to investigate soil and groundwater pollution for 200 gas stations in central and southern 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 selected gas stations with high pollution potential to conduct the detection and analysis of soil samples. In addition, groundwater samples from simple wells were also detected and analyzed. Based on the results of 2nd phase, the 3rd phase selected the gas stations with the pollutants’ concentration 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 3,616 soil gas monitoring wells, measure the oil vapor densities by using LEL, PID, and FID and the soil vapor of 715 samples by using PID and FID in 200 gas stations. The results indicated that the oil vapor density detected by soil gas monitoring wells in 7 gas stations with the highest pollution potential (A Class) and 12 gas stations with secondary pollution potential (B Class), totaling 19 gas stations. According to the instructions from the EPA, except the aforesaid 19 gas stations, the 2nd phase investigated the 7 gas stations listed in the Project of Inspection and Appraisal of Groundwater Pollution Control Facilities and Monitoring Equipment in Gas Stations, and Consultation on Internet Declaration System for 2006 and 2007. Totaling 26 gas stations were investigated at 2nd phase. The 2nd phase conducted the detection and analysis of 100 soil samples and 78 groundwater samples from simple wells in 26 gas stations. As a result, it was concluded that the pollutants’ concentration in the soil of the 11 gas stations had reached the control standards; the pollutants’ concentration in the groundwater from the simple wells of the 9 gas stations had reached the control standards. The 3rd phase was to investigate the 9 gas stations. The pollutants’ concentration in the groundwater of the 5 of them had reached the control standards. As a result, it was concluded that the pollutants’ concentration in the soil of the 11 gas stations were higher than the control standards, and the pollutants’ concentration in the groundwater of the 5 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 analysis 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, Soil, Groundwater