Creating a New Home for the Kraken

The current home of the Seattle Kraken NHL team is the Climate Pledge Arena in Seattle, Washington. The renovation of the existing 1962 World’s Fair Pavilion transformed the aging and outdated facility into a modern 900,000 square ft., 17,000 seat arena with all modern amenities. Although the existing arena already extended below grade, it included minimal event and amenities space, and did not meet the current needs for a sports and entertainment venue. In order to transform the arena, the site was further excavated to about 60 ft. (18.3 m.) below grade in order to provide additional space and access. The challenge: the existing roof was to remain in place with the majority of the expansion occurring below grade. The existing roof was underpinned on a series of 67 drilled shafts installed with low headroom equipment. In addition, support of the new arena structure required deep foundation support consisting of 117 drilled shafts of varying diameter and depth within the excavation. The primary support of excavation system or shoring system selected was permanent soldier piles and lagging with permanent tiebacks. This installation of the shoring system and excavation had to be completed with the iconic concrete roof, weighing in at 22,000 tons, suspended in place on temporary steel support framing and drilled shafts. The support of excavation system consisted of four elements: the primary perimeter excavation, snorkels, pylon shoring, and the south buttress shoring and support, each of which had their own unique design and construction challenges. In the end, the construction team installed approximately 178,000 square feet of permanent shoring, including 500 soldier piles and 130,000 linear ft. of tiebacks. The performance of the drilled shaft installation was monitored by CSL testing. The performance of the shoring system was monitored by geotechnical instrumentation and performed as predicted in our analysis.