As part of a team, C&S was the prime structural engineer for Orlando International Airport’s Airside 4 (AS4) expansion and renovation. This $114 million project included a 150,000-square-foot expansion of the FIS and customs area, addition of international gates, a new central energy plant, and overall renovation. The project was designed so passenger flow and overall operations were not impacted. C&S determined the extent of foundation and framing demolition required to create the new hub and wing expansion. Portions of the foundation and framing needed to be removed, so to minimize disruption to passengers and users, numerous phasing plans and construction sequences were developed. The existing building structure and foundation system also had to be analyzed to determine load capacity for the second-story addition. Another challenge was creating an underground utility tunnel to route all utilities to AS4. Because of the planned expansion of the airline gates, the existing tunnel was demolished and replaced with a new tunnel that incorporated the footings for the expansion. A separate but integral part of this project was a new 10,000-square-foot central energy plant to support AS4. Open space is at a premium at the airport, so the most ideal location for the structure was adjacent to and partially in a pond. This presented the challenge of a foundation system in an existing pond with very poor soils and low bearing capacity. The solution was a deep pile foundation to support the structure and a shallow foundation system for that portion of the plant on an improved surface.