San Francisco International Airport plans to construct a perimeter seawall to protect low-elevation runways, terminals and other facilities from rising sea levels. Ten miles in length, the steel sheetpile and concrete structure would complement existing earthen berms and smaller seawalls to provide an 8-ft-high barrier against flooding and 100-year storm waves from San Francisco Bay—forecast to rise by as much as 3 ft by 2085. The project is estimated to cost $587 million, with construction to start by 2025.