Solid Waste Sanitary Disposal Of Chengdu City And Its Surrounding Areas Groundwater Pollution Risk Assessment

During the first phase of a landfill in Chengdu, the design meet the requirement of the construction technology standards, only the vertical impermeable measures were took, but had no horizontal impermeable measures. After years of running, the leachate might spread to the groundwater system and caused regional groundwater pollution. This paper took the landfill as the object of study, Based on the quantitative evaluation of pollution source, pollution passage, pollution receptor, and by use of the spatial computing function of GIS software, divided the groundwater pollution risk zone of the landfill, provided Theoretical basis of pollution risk managements of the landfill.The main research results are as follows:(1) Evaluated the Inherent vulnerability of groundwater, the seven evaluation factors were divide according to their score by employing the DRASTIC model and the spatial computing function of GIS, and superposition by map algebra, at last the Inherent vulnerability of groundwater areas were got. As the result shows, the zones of high vulnerability spread upstream of groundwater flow, in this zone, The water bearing layer is mainly sandstone, The permeability is higher and the pollutant easily to migrate to groundwater.(2) The evaluation index system of the functional value of groundwater resources is established, include four index: population density, groundwater quality, groundwater overdraft and groundwater resources modulus. Using analytic hierarchy process to determine weight, ultimately the evaluation results were calculated and the regions were divided in GIS. As the result shows, the regions those grade of groundwater resource function value above medium were densely populated areas and had poor water quality in plain.(3) Through combining the simple judgment method and detailed classification method, pollution risk of groundwater pollutant source was classified and partitioned by GIS. As the result shows, medium risk and high risk areas are mainly distributed in the densely populated area, in these area, population is concentrated in those areas, agricultural and industrial activity is frequent, and the upstream pollution accumulated to the downstream direction of life, those may have great influence to groundwater.(4) Based on the algebra function of GIS, the groundwater inherent vulnerability, the groundwater resource function value and the pollution risk of groundwater pollutant source were counted, and got the pollution risk of groundwater pollutant source at last. As the result shows, the high risk and medium risk regions concentrated in the plain, where population was concentrated, and pollution sources were various, Groundwater resources function value was higher than others. The Exploitation of these regions should be paid attention to. Based on the results of groundwater pollution risk assessment, the risk management scheme of pollution risk management for classification management, pollution source classification and groundwater exploitation were proposed, from the aspects of technology, economy and policy, the behavior of groundwater pollution caused by groundwater is restricted.