AS116: Insulation with gravel alone would have been possible in this area but would have required a work pad five to nine feet thick. By using insulation, however, the pipeline builders were able to reduce the overlay to an average 24 inches in total thickness., 1976-05, PCA0002-1b-58, Folder: PCA0002-1b. Alyeska Pipeline Service Company : Trans-Alaska Pipeline Construction Collection, 1976-1977, PCA 2. Alaska State Library - Historical Collections Finding Aids. https://alaska.libraryhost.com/repositories/2/archival_objects/17396 Accessed February 22, 2025.