The "Zielona ” industrial waste dump in the former "Zachem ” Chemical Plant in Bydgoszcz city is an active source of contamination of organic and inorganic substances directly related to the complex production profile of plants. A TOC concentration o f 1,600 mg/dm3 has been found in the waste dump area. Inorganic substances occur also at very high concentrations, mainly Cl- (up to 11,000 mg/dm3) and SO42-(over 7,800 mg/dm3). Specific groundwater contaminants include polycyclic aromatic hydrocarbons (PAHs), which have been found in all 13 piezometers around the waste dump. Concentrations of PAHs in the "Zielona ” waste dump range from <0.08 μg/dm3 to 19.10 μg/dm3, with a geometric mean of 1.08 μg/dm3. Approximately 85÷90% of total PAHs is naphthalene detected over the region at the highest concentration of 16.2 μg/dm3. Three-ring compounds, such as: acenaften (max 1.19 μg/dm3), anthracene (0.219 μg/dm3), phenanthrene (0.650 μg/dm3) and fluorescence (0.802 μg/dm3); as well as four-ring compounds, such as: pyrene (0.14 μg/dm3), chrysene (0.042 μg/dm3), benzo(a)anthracene (0.045 μg/dm3) and strongly carcinogenic fluoranthene at a very high level of 2.76 μg/dm3 have been identified in the research area. The rate of migration of PAHs in soil and water environment in the "Zielona ” industrial waste dump area is very small. Therefore, PAHs occur only near the source at a distance of about 100÷200 m from it. Furthermore, numerical hydrogeological modeling indicates that sorption takes place in a non-specific manner.