A thick sequence (45+ m) of Cretaceous age Potomac Group sediments unconformably overlain by Quaternary Trenton Gravel and Alluvial silts and clays was investigated as part of the planning for and construction of a new 1525-m-long (5000-ft) runway (Runway 8–26) at the Philadelphia International Airport. This runway was constructed over a deleted but deed-restricted U.S. Environmental Protection Agency Superfund site, the Enterprise Avenue Landfill. This sedimentary sequence contains three discrete aquifer units, several of which are included within the recharge zone of the federally designated New Jersey Coastal Plain Sole Source Aquifer. This paper presents an overview of the geology of southwestern Philadelphia in the vicinity of Philadelphia International Airport and the former Enterprise Avenue Landfill area. The field trip through this area will include descriptions of the geology and history of the area, the Runway 8–26 project at the airport, the on-site groundwater mitigation system at the Enterprise Avenue Landfill area, and future enhancements to the airport infrastructure currently under consideration.