Risk assessment of nitrate transport through subsurface layers and groundwater using experimental and modeling approach

Landfills are one of the main point sources of groundwater pollution. This research mainly aims to assess the risk of nitrate (NO -3) transport from the unlined landfill to subsurface layers and groundwater using experimental results and the SESOIL model. Samples from 12 groundwater wells downstream of the landfill were collected and analyzed in 2008, 21 years after the landfill construction. The average NO -3 concentration in the wells was 54 mg/L, slightly higher than the World Health Organization (NO -3 50 mg/L) standards. SESOIL model was used to predict the NO -3 concentration at the bottom of the unsaturated zone. Results indicated that the current mean NO -3 concentration at the bottom of the unsaturated zone is 75 mg/L. the model predicted that the level of NO3 will increased up to 325 mg/L within 30 years. Accordingly, the NO -3 concentration in groundwater wells near the landfill area is expected to gradually increase with time. Although the current risk associated with the NO -3 level might not be harm to adults, however, it might pose severe risks to both adults and infants in the near future due to NO -3 leaching. Urgent mitigation measures such as final cell cover (cap), lining system and vertical expansion should be considered at the landfill to protect the public health in the area.