Basically, every single building would requires structural engineer to design the foundation.
Foundation design would mainly depends on the site investigation as to found out the ground condition. Therefore the structural engineer would design the depth and size of the foundation piles. Let say 10m in this case, so if the contractor intended to reduce the depth of the piles to 8m! That means the contractor can 貪污 the money that he saved on that reduced 2m. Because time is money in a construction site, that 2m would includs materials and labours. that is a lot of money.............