Identification and Assessment of Groundwater and Soil Contamination from an Informal Landfill Site

Landfills are a potential source of local environmental pollution of all kinds, and the gradual destruction of seepage-proof structures in informal landfills will lead to contamination of the surrounding soil and groundwater environment. In this study, an informal landfill site in eastern China is used as the research object. Using technologies such as unmanned vessels and monitoring well imaging to delineate the amount and distribution of polluting media, sampling of the surrounding soil, sediment, groundwater, and surface water for testing, analysis, and evaluation is carried out visually and finely for heavy metals, petroleum hydrocarbons, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and other indicators. The test results show that volatile phenols are the main contaminant species in the shallow groundwater, chlorinated hydrocarbons and benzene were prevalent in the deep groundwater, hexachlorobenzene and lead in the surface soil, and di(2-Ethylhexyl) phthalate in the deep soil (5.5 m), with a maximum exceedance of 1.24 times. Nearly 10 years have passed since the waste dumping incident at the landfill, but characteristic contaminants are still detected in the topsoil of the dumping area, which shows the long-term nature of the environmental impact of illegal dumping on the site. The study recommends that when developing a comprehensive remediation plan, the persistence of the environmental impact of the waste should be considered and appropriate remediation measures should be screened.