Large storage tanks are important oil and gas production infrastructure. However, due to widespread occurrence of weak and compressible soils, and the inevitable consequences of foundation failure, extreme care is exercised in the design of its foundation. More so in the Niger delta, characterized by a variety of soils including tropical lateritic soils that are known to exhibit lateral and vertical variations in strength and compressibility, as well as effects of seasonal changes in its moisture levels. The necessity for ground improvement is determined by soil peculiarity and the sensitivity of the structure to be placed on the ground. The tropical lateritic soil with seasonally dependent strength (50kN/mē - 110kN/mē) was considered inadequate for the foundation of a large storage tank with diameter ø 76m and 22m high transmitting about 10⁶kN when fully loaded, because of anticipated high total settlement which is unacceptable for the rigid skid systems. This paper describes the geotechnical and environmental considerations in the design of foundations. The choice of sand replacement for the foundation of the large storage tanks and details of the procedures, particularly the quality control steps adopted to ensure a satisfactory foundation performance are also described.
ISSN: 1792-9040 (Print)