S-2.1, r. 4 - Safety Code for the construction industry
3.24.8. Preparation of the work area: Before the beginning of the steel structure erection work, the principal contractor must verify
(1) that the concrete foundations are backfilled and the work area, including the unloading area, is levelled, drained and of a sufficient dimension to store materials; and
(2) that the resistance of the soil under the work area allows support of hoisting apparatus, trucks and loads during the work.