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 Investigating Soil and Groundwater Pollution at the Gas Stations(the Fifth Project)- 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, 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.
Plan A performed by Sinotech was aimed to investigate soil and groundwater pollution at 21 gas stations in Central and Southern Taiwan. The findings generated will be used as references for the follow-up pollution control. The investigation was implemented in the following three stages:
1. Stage 1: The fuel vapor of soil gas monitoring well was detected and measured.
2. Stage 2: At the gas stations with high pollution potential, based on the results of Stage 1, the soil sampling analysis and groundwater sampling from simple wells analysis were conducted.
3. Stage 3: Focusing on the gas stations with groundwater pollutants beyond the control criteria, standard monitoring wells will be further installed and groundwater sampling analysis will be conducted.
For Stage 1, 21 gas stations were investigated, covering basic function tests of 336 soil gas monitoring wells, measurement of fuel vapor concentration by using Lower Explosive Limit(LEL), Photo Ionization Detector(PID), and Flame Ionization Detector (FID), and inspection of the soil vapor of 9 samples by using PID and FID. The results indicated that through the evaluation of the fuel gas concerntration detected by soil gas monitoring wells, there were 6 gas stations with the highest pollution potential (A Class) and 2 gas stations with the second high pollution potential (B Class), totaling 8 gas stations. According to the EPA’s instructions, except the aforesaid 21 gas stations, two more gas stations were investigated in the 2nd Stage, which made total 23 gas stations under investigation in Stage 2.
For Stage 2, 23 gas stations were investigated, covering the detection and analysis of 89 soil samples and 58 groundwater samples from simple wells. The findings showed that the soil pollutant concentration of 11 gas stations and groundwater pollutant concentration from the simple wells at 9 stations were under the control criteria. For Stage 3, five out of nine gas stations had the groundwater pollutant concentration under the control criteria.
It was concluded that there were 13 gas stations which had soil pollutant concentration above the control criteria in the implementation of Plan A. All of these stations should be remedied in accordance with the Soil and Groundwater Pollution Remediation Act. In addition, the correlation analyses of basic data of the gas stations investigated in the project, groundwater pollution control facilities, periodic declaration reports, and pollution potential at the gas stations were also conducted for the project. The outcomes will serve as references for the environmental protection agencies in the follow-up administrative control measures.