Kartering av markföroreningar inom Skutskärs Bruk samt utvärdering av spridningsrisker enligt Naturvårdsverkets MIFO fas 2
With the prospect of future construction on the Skutskär Pulp Mill property, Stora Enso Fine Paper has initiated an investigation of soil contaminants and a risk assessment of these contaminants. A soil and groundwater investigation has therefore been conducted on an open area of about 16 000 square meters, situated between the current wood room and digester house. To be able to integrate this study into an investigation for the whole industrial property, the study has been carried out as a phase 2 study according to the Swedish Environmental Protection Agency?s Methods of Inventories of Contaminated sites (MIFO).The site investigation has involved soil and groundwater sampling, together with the analysis of heavy metals and organic contaminants. The degree of hazard posed by the contaminants, the level of contamination, the potential for migration of the contaminants, as well as the degree to which protection of human health and the environment is required in the area, have been weighed together for an overall risk assessment of the area with regard to human health and the environment.The investigated area was built up by filling in the coastal waters. The fill material consists mainly of sand that becomes finer below the groundwater surface at the depth of about 2.3 m.Above the groundwater surface pyrite cinders was encountered. Underneath the cinders, lime sludge, bark and wood fiber were found at different depths. The deepest layer encountered consists of moraine.The results showed that most of the heavy metals in the soil originate from the pyrite cinders. The level of contamination was assessed as very high for Zn, Pb, Cu, Cd and Hg. In the groundwater, the level of contamination was assessed as high for Al and moderate for Pb and Cr. The level of organic contaminants was in general low. Heavy oils were encountered in shallow soil layers. Mercury was analysed due to risk of migration from an earlier factory that produced chlorine alkali. The metal was encountered in both the shallow and the deeper layers of soil. Only three of 56 soil samples exceeded the Swedish Environmental Protection Agency?s guideline value for less sensitive land use of 7 mg Hg/kg dry weight.The investigation indicates that the metals still are bound to the pyrite cinders and that most of the leachable parts were mobilized during the years when the ground was not covered with asphalt.Most of the contaminant migration is assumed to take place through groundwater advection. The groundwater flows in the direction of the dock and was calculated to about 3 m3 per day. The gradient in the area is about 0.5 %. The average linear groundwater velocity was computed to about 5 m per year. The transport of the pollutants might be slower due to adsorption and precipitation. Groundwater sampling indicates that the transport to the dock is up to 100 g Zn, 10 g Cr, 8 g Pb and 0.02 g Hg per year.The site was assigned to risk class 3, i.e. moderate risk regarding human health and environment and relatively low urgency concerning additional investigations.