Alcatraz Island Cellblock Repair

Langan provided the geotechnical and geologic services for the structural evaluation and repair of Cellblock on Alcatraz Island. The island is one of the National Park Service’s most popular parks and features the first lighthouse and US built fort on the West Coast as well as the infamous prison. The Cellblock required a foundation investigation for seismic retrofit and to address instabilities of a 50 to 60-foot high rock slope, which involved reconnaissance of slope areas, mapping of exposed geology, and development of recommendations for stabilization. We observed footing excavations, installation of rock anchors, and load tests on rock anchors, and verified that the foundations complied with the plans and specifications.