Long-Term Design of the At-Grade Foundation System for an LNG Storage Tank in Fairbanks, Alaska

Fairbanks Natural Gas (FNG) has been evaluating the need for a new liquefied natural gas (LNG) storage tank since 2012. The new tank is required to support expanded service of natural gas in the greater Fairbanks and North Pole areas of Interior Alaska. Because of the seismic demand, an at-grade mat foundation was selected for this tank over the typical pile supported foundations. LNG is typically stored at temperatures around -160°C and then warmed before passing into service lines. Traditionally, LNG storage tanks constructed on thawed ground include heater systems between the foundation and underlying soil to avoid the generation of permafrost and basal frost heave. In regions with permafrost, LNG storage tanks are generally supported on pile foundations with elevated pile caps that allow for a thermal break between the tanks and soil. The FNG LNG storage tank is one of the first LNG storage tanks constructed on permafrost soils that has been designed as an at-grade foundation. Because the permafrost soils only extend approximately 40 m deep and the site is adjacent to the Tanana River, the aggradation of permafrost would not be acceptable over a 75 year design life. The delicate balance of maintaining warm permafrost was evaluated, modeled, and designed to allow for the construction of an at-grade foundation system. The system balances the cold from the LNG within the storage tank to maintain the permafrost, but not to significantly lower the temperature of the permafrost. The methods and design considerations will be presented.

Language

  • English

Media Info

  • Media Type: Web
  • Pagination: pp 483-491
  • Monograph Title: Cold Regions Engineering 2019

Subject/Index Terms

Filing Info

  • Accession Number: 01728529
  • Record Type: Publication
  • ISBN: 9780784482599
  • Files: TRIS, ASCE
  • Created Date: Aug 8 2019 3:03PM