Petrol Station Site Environmental Assessment And Contaminated Soil & Groundwater Remediation Research

Industrial development does not only bring convenience to people's life,but also brings a series of pollution,especially to soil and water.In the past40 years of reform and opening-up,the number of domestic petrol stations has been increasing,and now there are more than 100,000 petrol stations.However,soil and groundwater pollution in petrol stations is becoming increasingly serious.The Environmental Site Assessment?ESA?of petrol station started late in China with few relevant researches.Therefore,no matter it is a national strategy or a realistic demand,it is necessary to carry out ESA and remediation of petrol stations in order to find out the pollution situation and take corresponding measures to remediate and control the pollution risk.The Environmental Site Assessment of petrol station includes three phases.The Phase II ESA and Phase III ESA are carried out depends on the results of the previous ESA.According to the research of ESA,Contamincation Risk Assessment and Remediation for potential polluted petrol station in this paper,as well as the domestic and international relevant ESA,monitoring,remediation and acceptance guidances and technical methods research,and combine with the remediation cases research of the petrol station in China.Systematic analysis the standard of ESA process and remediation technical guidance,and develop suitable methods for petrol station ESA,Contamination Risk Assessment and soil and groundwater remediation from the experience of experimental analysis data of soil and groundwater samples,the main research conclusions are as follows:?1?Normally,the area of the petrol station is about thousands square meters which is smaller than other industrial sites.Its potential source of pollution is relatively clear,mainly gasoline and diesel from petrol stations.The main route of pollution is leakage of underground storage tank,underground pipeline or refueling area.The environmental drilling monitoring points of ESA is set up with a triangle of three drilling sampling points and install groundwater monitoring wells near the petrol station boundary.The refueling area,underground oil pipeline and oil tank area must be included in the triangle area.The depth of drilling is generally2.0³.0 meters below the initial water level.The environmental monitoring well is mainly made of PVC pipe,surrounded by filter screen,and filled with sand and stone between the PVC pipe and the borehole wall to achieve the effect of filtering solid impurities.The analysis samples were soils and water samples from groundwater monitoring wells after drilling and initial screening,and the analysis parameters were mainly benzene series?BTEX?,polycyclic aromatic hydrocarbons?PAH?,total petroleum hydrocarbons?TPH,C6^C36?,lead?Pb?and methyl tert-butyl ether?MTBE,only for groundwater samples?.According to the current national standards,the reference standards for the analysis of soil samples and groundwater samples of petrol stations are the screening value of type II land of"Soil Environment Quality Risk Control Standards for Contamination of Development Land"?GB 36600-2018?,and type IV standards of"Quality Standard for Ground Water"?GB/T 14848-2007?.Since there are no corresponding reference standards for MTBE and TPH indexes in groundwater analysis parameters in China,the Dutch Soil Remediation Circular of 2013 is commonly reffered in the industry.?2?According to the project experience,the contaminated site risk assessment of the petrol station is generally conducted at the same time as the Phase III ESA.Based on the study of national standard,human health risk was evaluated as non-sensitive land in petrol station.Through practical case studies in this paper,the affacted sensitive acceptor is mainly ground staff and customers in the petrol station,the main concerned pollutants is the parameters which exceed the limits in the ESA,the potential pollutants exposure pathways to field staff and customer including:indoor and outdoor air inhaled from the subsoil of gaseous pollutants and inhalation of gaseous pollutants in indoor air from groundwater.According to the calculation of carcinogenic effect and non-carcinogenic effect,the pollutants to be remedied are determined,and the target remediation value is deduced.Compared with the domestic soil and groundwater standards,the lowest value is determined as target remediation value related to site characteristics.?3?Polluted areas of petrol stations are usually the areas with high safety management risks,such as oil tank areas,underground oil pipelines and refueling areas.Based on the consideration of operation profit,the petrol station should try its best to consider the in-situ remediation without shutdown of the petrol station,and the remediation process should meet the requirements of the safety management and protection of the existing buildings and facilities in the petrol station.Through the screening study of the remediation methods,the fixed remediation target was that the concentration of groundwater petroleum hydrocarbon pollutants detected for 4 consecutive times did not exceed 5 times of the intervention value of the Dutch Intervention Value,the remediation methods of the petrol station are as follows:for the pollution of phase seperated hydrocarbon?PSH?in the groundwater monitoring well,the physical extraction for oil and water mixture is selected for the ectopic oil and water separation treatment;Then physical gas phase extraction of volatile pollutants was carried out in combination with soil vapor extraction?SVE?.After that,hydrogen peroxide?H₂O₂?and in-situ oxidation remediation were further injected.Finally,the natural degradation of pollutants is carried out by microorganisms in nature.Through a three-year follow-up study on the groundwater remediation cases of petrol stations,the selected remediation plan can basically achieve the pollution remediation target of the polluted petrol stations.This study combines the analysis and summary of technical regulations and project practice research,the ESA and risk assessment methods suitable for petrol station are presented,and the appropriate remediation plan for groundwater pollution of gas stations is proposed,which has certain reference value for pollution ESA,pollution risk assessment and remediation of existing petrol stations in China.