The textbook entitled Foundation Analysis and Design states that there is no binding rules for the number or depth of soil borings.
However, PIP VECTA001 recommends for large tanks a minimum of 3 borings. The PIP STE03020 defines a large tank as 50 ft. diameter or greater.
Please advise...
The API 650 states in Appendix B that "when the ringwall width exceeds 460 mm (18 in), using a footing beneath the wall should be considered".
What is the technical basis for this recommendation?
