Monday 31 October 2016

EXCAVATION HAZARDS- THEIR EFFECTS AND PREVENTION

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.

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