Safety Precautions

Secure fencing wherever required shall be  provided with proper caution signs during the day and red lights at nights to avoid accidents. 

Excavation shall not damage adjoining structures or dislocate the services  in any way. It would be useful to  have photographs of those structures and records of cracks if any. It may be useful in resolving disputes claims etc. at a later date. 

In sandy/alluvial soils, if ground water table is lowered, ground subsidence in the area surrounding the construction site may occur due to consolidation of underlying clay layers. In such a case it may be necessary to provide a water retaining barrier around the site if structures exist adjacent to the excavation. Pumping to dewater may produce 30 to 50 mm settlement within a short time affecting the structure. 

When pore water in the soil is just enough to moisture the sand but not saturate it, the surface tension makes it possible to provide shallow excavations with near vertical sides. With confirmed drainage and evaporation or vibration, the sides may collapse. 

Near vertical excavation in a cohesive soil may collapse due to rainfall softening the clay and creating excess pore water pressure. 

Excavation in sands below the water table may result in slumping of the sides and boiling of the bottom, unless a properly designed ground water lowering system is adopted.