Sinotech Engineering Consultants Ltd. completed the “Potential Contamination Sources Investigation Plan for 10-years-old Gas Station and Large Tank Sites, Sub-plan B”. In this plan, the background and pollution potential of underground environment in total 400 gas stations in southern Taiwan had been investigated.In Phase I Investigation, we inspected 400 gas stations and 5,018 soil vapor monitoring wells by using LEL(Lower Explosion Level) detector, PID(Photoionization Detector) and FID(Flame Ionization Detector) and checked the capabilities of those wells (including the cap could be opened or not, water accumulation and ventilation test, etc.). There were 616 soil vapor-monitoring wells failed. According to investigation results, 164 gas stations were screened to enter the next step (Phase II). In Phase II Investigation, we inspected 164 gas stations, sampled and analyzed 402 soil vapor samples from monitoring wells and 404 samples from direct push process. Base on the analyzing values of benzene, toluene, ethylbenzene, xylene and total petroleum hydrocarbons (TPH), 58 gas stations were sieved out to do soil and groundwater sampling investigation. (Phase III) According to the analyzing results of soil and groundwater samples, 35 gas stations have higher pollution potential among 58 gas stations. In order to confirm the pollution situation, Taiwan EPA assigned 35 gas stations to Sub-plan B、Sub-plan C and Sub-plan D to conduct the identification task. According to the identification results，19 gas stations were exceeding the “Soil Pollution Control Standards ” or the “Groundwater Pollution Control Standards”. Taiwan EPA have to do the follow-up control according to the “Soil and Groundwater pollution Remediation Rules”。 The “Criteria Examining of Groundwater Pollution Preventing Facilities and Monitoring Equipment of the UST System and Records Writing” has been reviewed and corrected in this plan. The initial steps of gas station leakage investigation, control plans and emergency process were also completed.

Gas Station, Soil, Groundwater, Soil Vapor Monitoring Well