Groundwater flow modelling to address hydrogeological response of a contaminated site to remediation measures at Hjortsberga, southern Sweden

Abstract: Pentachlorophenol (PCP) is a chlorinated aromatic compound that was commonly used for treatment of wood against microbial degradation before it got banned in the 1970s. Due to its solubility in water, PCP is a common groundwater contaminant around old sawmills, for example near Hjortsberga in southern Sweden where this study was performed.. The contaminated groundwater is spreading and leaking into a nearby lake. It is of high importance to remediate the site. The area has been thoroughly investigated, and a few in-situ remediation methods have been attempted, but the problem is still not solved because of complex geology and severe contamination. Chemical and microbiological degradation of PCP is not fast enough. One way to slow down the groundwater flow and enhance the chemical oxidation could be to install a permeable reactive barrier. This can be done theoretically by the creation of a groundwater model. In this work a groundwater model was created with the code MODFLOW 2005 developed by the United States Geological Survey. With the created model a "best placement" scenario was investigated. The results show that a barrier type called "funnel and gate barrier" most efficiently prolongs the groundwater path, extending the time it takes for groundwater to flow from the contaminated site to the lake.