Results of the summary study indicate that despite different materials and processes, most coal tars have general similarities in composition, physical properties, and transport. Chemically, coal tars are dominated by polycyclic aromatic hydrocarbons, primarily naphthalene, methylnapthalenes and phenanthrene. The density of most coal tars is generally less than 1.1 g/cc. However, denser coal tars ranging from 1.2 to 1.5 g/cc occur, and these tars are generally composed of heavier polycyclic aromatic compounds. The viscosity of coal tars is variable generally range from about 30 cP to 100 cP. The surface and interfacial tensions of most coal tars ranges from 25 to 35 dynes/cm and 20 to 30 dynes/cm, respectively. As a result of these physical properties, the migration of coal tars from a source area is generally limited. In particular, with a density near water and an elevated viscosity the vertical and lateral migration of coal tars is generally limited. As such, the physical properties of coal tar produce uniquely different impacts when compared to other DNAPLs such as chlorinated solvents.