Abstract：A foundation design method and considerations for two large-sized fuel tanks on soft marine clay deposit in Attawapiskat，located in the James Bay coastal area of Northern Ontario，Canada are describes. The tanks with diameter of 29 m and height of 12 m are required for fuel supply for a diamond mine，located approximately 100 km west of Attawapiskat. Each tank has a volume capacity of 7.5 million litres；and the maximum tank pressure of 140 kPa is exerted. The design involving a mat foundation is introduced. The design criteria require adequate safety margin against potential failure(bearing pressure and edge pressure) and relatively stringent settlement(differential) limits. Other design considerations include frost effects，limited availability of granular and rockfill materials，short construction period，and spill containment. Stability assessment indicates the edge failure to be more critical than the bearing capacity failure mode，and emphasizes the need for soil improvement. The uses of geosynthetic reinforcement along the perimeter of the tank and prefabricated vertical drains(PVDs) in the foundation soil in conjunction with site preloading are expected to reinforce the foundation，accelerate consolidation and reduce post-construction settlement. The design studies confirm the feasibility of constructing a mat foundation within short time，provided that the ground improvement measures mentioned above were incorporated.
