EXCAVATION HAZARDS- THEIR EFFECTS AND PREVENTION

Different types of hazards are associated with excavation of soil. These hazards should be identified and preventive measures should be taken to avoid any accident at construction sites. The following table highlights hazards associated with excavation of soil during construction, their types, effects and preventive measures.

TYPE OF EXCAVATION	TYPE OF HAZARD	EFFECT OF HAZARD	PREVENTIVE MEASURES
Pit excavation upto 3m	Falling into pit	Personal injury	Provide guard rails / barricade with warning signal Provide atleast two entries / exits Provide escape ladders
	Earth collapse	Suffocation /breathlessness Buried	Provide suitable size of shoring and strutting if required. Keep soil heaps away from the edge equivalent to 1.5m or depth of pit whichever is more. Don’t allow vehicles to operate too close to excavated areas. Maintain atleast 2m distance from the edge of cut. Maintain sufficient angle of repose. Provide slope not less than 1:1 and suitable depth of excavation in all soils except hard rock. Battering / benching the sides.
	Contact with buried electric cable Gas / Oil Pipelines	Electrocution Explosion	Obtain permission from competent authorities prior to excavation if required. Locate the position of buried utilities by referring to plant drawings. Start digging manually to locate the exact position of buried utilities and thereafter use mechanical means.
Pit excavation beyond 3m	Same as above plus flooding due to excessive rain / underground water	Can cause drowning situation	Prevent ingress of water Provide ring buoys Identify and provide suitable size dewatering pump or well point system
	Digging in the vicinity of existing building / structure	Building / structure may collapse Loss of health and wealth	Obtain prior approval of excavation method from local authorities. Use under-pinning method. Construct retaining wall side by side.
	Movement of vehicles / equipments close to the edge of cut.	May cause cave-in or slides. Person may get buried.	Barricade the excavated area with proper lighting arrangements. Maintain atleast 2m distance from edge of cut and use stop blocks to prevent over-run. Strengthen shoring and strutting.
Narrow deep excavations for pipelines etc.	Same as above plus frequent cave-in or slides	May cause severe injuries or prove fatal.	Battering / benching of sides. Provide escape ladders.
	Flooding due to hydro-static testing	May arise drowning situation	Same as above. Bail out accumulated water. Maintain adequate ventilation.
Rock excavation by blasting	Improper handling of explosives	May prove fatal	Ensure proper storage, handling and carrying of explosives by trained personnel. Comply with the applicable explosive acts and rules.
	Uncontrolled explosion	May cause severe injuries or prove fatal.	Allow only authorized persons to perform blasting operations. Smoking and open flames are to be strictly prohibited.
	Scattering of stone pieces to atmosphere	Can hurt people	Use PPEs like goggles, face mask, helmets etc.
	Entrapping of persons / animals	May cause severe injuries or prove fatal	Barricade the area with red flags and blow siren before blasting.
	Misfire	May explode suddenly	Do not return to site for atleast 20min or unless announced safe by designated person.
Piling work	Failure of pile-driving equipment	Can hurt people	Inspect piling rigs and pulley blocks before the beginning of each shift/
	Noise pollution	Can cause deafness and psychological imbalance.	Use personal protective equipments like ear plugs, muffs etc.
	Extruding rods/casing	Can hurt people	Barricade the area and install sign boards Provide first aid
	Working in the vicinity of live-electricity	Can cause electrocution / asphyxiation	Keep sufficient distance from live electricity as per relevant standard codes. Shut off the supply if possible. Provide artificial / rescue breathing to the injured.