The DeLong Pier Repair Project: The Unique Challenges of Designing Repairs to a 1950 Vintage Marine Structure in the Arctic

This paper discusses the inspection and design of repairs to a pier 1118 kilometers (695 miles) north of the Arctic Circle. The DeLong pier serves as the lifeline to resupplying and providing construction materials to the Thule Air Base in Thule, Greenland. The pier supports base operations and is the northernmost deep-water port in the world. The pier is constructed of four jack up barges originally conceived for service as oil exploration platforms in the Gulf of Mexico. The barges were towed to the site in 1951 as a temporary facility and have been in continual seasonal service to this date. Each barge is 76 m long by 15 m wide (250-feet long by 50-feet wide) and aligned end-to-end forming a 305 m (1000-foot) berth. Forty-eight (24 per side) 2 m (6-foot) diameter concrete filled steel caissons support the pier. The jack up barge type construction allowed the pier to be installed at the site within the limited weather window of the arctic environment. Early in the pier's life, many of the caissons began to exhibit cracks in their steel shells within the tide zone, presumably a result of ice expansion forces and steel that was unsuitable for extreme cold weather service. Numerous repairs have been carried out over the structure's life to address this problem. This paper provides an overview of the pier's history and arctic port operations and focuses on the recent rehabilitation project. These repair designs incorporated experience and knowledge gained from previous repairs and were detailed for a limited construction window of approximately two months.