Contamination analysis of the landfill Rösaberg inerta massor : Risk assessment and investigation of the contaminant distribution

Abstract: The dispersion of contaminants deriving from landfills poses a risk to the surrounding environment and human health. Old landfills are treated with extra precaution, due to their poorer construction, less stringent operation and lack information regarding the waste content. Vetlanda municipality has identified 48 old landfills. One of them is Rösaberg inerta massor. It is one of the largest landfills in the region and is located close to numerous sensitive environmental receptors (such as the river Emån). During a phase 1 investigation (MIFO 1) in 2017, the landfill was designated the highest risk classification, class 1, and is considered a very high risk to environment and human health. No sampling was conducted during this time, but the level of contaminants was assumed to be very high.   The objective of this study was to investigate the prevalence of contaminants by determining the pollution levels in soil and groundwater in the landfill. Samples was obtained by completing a site investigation, involving trial pits examination and installing of monitoring wells. National as well as site-specific guideline values were used to determine the effects of the contaminant levels of the site. In the software Groundwater Modeling system (GMS) was used to study if the contaminant plumes reach the river Emån. A 50-year scenario was set up in GMS to investigate likely concentrations in the future. Finally, a new risk assessment of the site was done, based on the obtained results.   The results indicated that the landfill does not pose such a large environmental risk that initially was expected in the phase 1 investigation. The level of contaminants was higher in the groundwater than in the soil. High concentrations of PAH-Hs and 2,6-dichlorobenzamide were found in two of the groundwater samples. However, the risk assessment using the information obtained from the study indicated a lower risk than what was estimated in the MIFO 1 assessment 2017. In this study, the risk of the landfills current properties was evaluated to a risk 2. The 50-year scenario indicated that contaminants in the uppermost groundwater layer will have dispersed in a higher rate than the contaminants in the lower layer. The risk was estimated to a risk 3 in 50 years. It should be noted that no samples was conducted in river Emån which needs to be done before ruling out the necessity for remediating the groundwater. No remediation action for the soil was assessed to be necessary.