1) The site investigation (SI) indicate that the slope is safe. In reality, the result of site investigation only reveal the soil properties in details, but not as a firm assurance for the safety of the slope. A geotechnical engineer must perform a complete analysis by using the site investigation's result to derive the factor of safety (F.O.S). A good judgement from an engineer also vital before finalizing the F.O.S. The slope composition and geology can be extremely varies even at a near distance. Geology information, soil classification and properties play a prime role in determine the slope stability. 2) Heavy downpour resulted to slope failure For a layman, it is logical for the slope to fail during heavy rainfall. As to engineer, continuous downpour will increase the water table and hence diminishing the F.O.S of the slopes. A minimum F.O.S is within 1.2 to 1.4, depending on the risk values to human and economy. In Malaysia, the minimum acceptable F.O.S is 1.5. 3) So
A typical Malaysian engineer with his side of story