On commission by the Swedish Armed Forces, FOI has performed environmental investigations of seven former naval bases (delimited to the basins and a priority on analyses of organic tin compounds); Berga, Rindö, Göteborg, Skredsvik, Härnösand, Karlskrona and Fårösund. This report presents the results from these studies and a final classification of assembled environmental risk of the sediment basins; according to the Swedish official method for investigation of polluted areas (MIFO). Complementary soil sampling has been carried out at a helicopter area and a building used for handling explosives at Skredsvik, and at an area for boat maintenance at Härnösand. The results of the risk classification are, in brief, shown in the table below. Object (harbour basin) Protective value Prominent contamination profile MIFO risk class Motivation Berga Moderate TBT1 (Hg2, Märsgarn basin) 2 Based on one point having very high TBT concentration and unknown areal extent Rindö Moderate TBT 3 Low to moderate TBT concentration Göteborg Moderate TBT PCB3, PAH4 3 Low to moderate concentration of PCB and PAH, occasional high TBT conc. Skredsvik Moderate TBT, PAH, PCB 3 Low to moderate concentrations of TBT, PAH, PCB Karlskrona Moderate TBT, Cu5, Pb6, Hg, PAH, hydrocarbons7 2 Occasional very high concentrations of TBT and metals Härnösand (boat maintenance area) Moderate TBT, Cu, Zn8 29 Very high concentrations at the grinding place Fårösund Moderate TBT, PCB, PAH, Cu, Zn, Pb 3 Occasional high concentrations of TBT but considered normal as to marinas 1Tributyltin; 2 Mercury; 3 Polychlorinated biphenyls; 4 Polycyclic aromatic hydrocarbon; 5 Cupper; 6 Lead; 7 Unpolar hydrocarbons/total extractable hydrocarbons; 8 Zinc; 9 Sand from grinding of boat hulls