According to the ASTM E1527-13 Standard, “migrate” or “migration” in the context of a Phase I Environmental Site Assessment refers to “the movement of hazardous substances or petroleum products in any form, including, for example, solid and liquid at the surface or subsurface, and vapor in the subsurface.” The term is often used to refer to a plume of contamination at a neighboring property migrating onto the subject property via groundwater or vapor movement.
