Kartläggning av föroreningars förekomst och spridning i Gräsötippen enligt MIFO

Sammanfattning: It is estimated that 22 000 contaminated areas exist in Sweden today. In order to classify the risk of contaminant migration from these areas and to prioritize which of these contaminated areas should first be treated, the Swedish Environmental Protection Agency (EPA) has designed a method, for the investigation of contaminated areas (MIFO). One of these contaminated areas is the landfill Gräsötippen outside Köping. The landfill has been used by both Yara AB and the Köping municipality between the years 1945 and 1975, and both industrial and household waste have been deposited there. The aim of this report is to survey which contaminants that can be found in the soil and water in the landfill Gräsötippen and to evaluate the migration of these contaminants. With help of this information, the landfill will then be risk classified according to MIFO. The goal is that this report will provide a basis for future studies and remedial measures at the landfill. To get a picture of what has been deposited at the landfill Gräsötippen, employees and former employees at Yara and others with connection to the landfill have been interviewed. Piezometers have been installed in and around the landfill so as to provide information on groundwater levels and movement, and for the collection of groundwater samples. Soils samples were collected as well. The water and soil samples were analyzed with regard to metals, organic compounds and nutrients. Furthermore, groundwater flow has been modeled using VS2DI, in order to get a picture of the groundwater’s flow direction and velocity under the landfill. In the water samples, only lead was detected with levels over the Maximum Contaminant Level (MCL) from the EPA. Relatively high levels of nutrients were also detected. In the soil, carcinogenic PAH, PCB, aliphatic hydrocarbons, aromatic hydrocarbons, arsenic, lead, cadmium, mercury and zinc were detected over the EPA MCL. The landfill Gräsötippen has a good location in an area with deep clay, which prevents rapid spreading of contaminants. No high levels of contaminants are leaching out today. The spreading of the contaminants is minor; most of the contaminants are fixed in the soil and do not spread to the surroundings. The water flow’s primary direction from the landfill is south but there are also flows to the west and east. Today, there are a number of proposals with regard to decreasing the risk for future contaminant dispersal from the landfill and to keep control of the water that is used in the area. A few of these proposals are to finally cover the landfill, to analyze the grass and plants in the enclosed pasture on the landfill, and to continuously analyze the water in the installed piezometers and drinking water wells on and around the landfill. The landfill Gräsötippen is classified to risk class 3, moderate risk, according to MIFO.