The design and calculations are based on the coulomb method and conform the britisch standard BS8002 which state that the security factor against overturning (FO) has to be 2 and the security factor against sliding (FS) has to be 1.5.
The calculations are done based on the information receive from the customer. In ideal conditions this should be communicated using a soil report which informs us about the soil density , internal friction angle , bearing pressures , soil type , cohesion , … of the construction site.
This is a rather expensive step for smaller projects. If these data aren’t provided we can make an accurate estimate of these parameters based on our experience. the assumptions made will be clearly mentioned in our studies to allow checking by the responsable site engineer or project leader.