Excavation safety


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a detailed note on excavation by experts on osho shemil baba lecture centre

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Excavation safety

  2. 2. Basic defenitions Deep Foundation means a foundation unit thatprovides support for a building or structure bytransferring loads either by end bearing to soil or rock atsubstantial depth below the building or structure, or byadhesion or friction or both, in the soil or rock in which itis placed, and includes a pile or caisson. Excavation means a dug out area of ground andincludes a deep foundation excavation, trench, tunneland shaft. Open excavation means an excavation in which thewidth is greater than the depth, measured at the bottom.
  3. 3. Basic defenitions Pile or Caisson means a slender, deep foundationunit made of materials or a combination ofmaterials, such as wood, steel or concrete, which iseither pre-manufactured and placed bydriving, jacking, jetting or screwing, or cast in place ina hole formed by driving, excavation or boring. Shaft means a vertical or inclined opening thatleads to an underground working and is excavatedbelow ground level.
  4. 4. Basic defenitions Shoring is an assembly of structural membersdesigned to prevent earth or material fromfalling, sliding or rolling into an excavation. Support structure means a temporary orpermanent structure or device designed to provideprotection to workers in an excavation, tunnel or shaftfrom cave-ins, collapse, sliding or rolling materialsand includes shoring, bracing, piles, planks and trenchcages.
  5. 5. Basic defenitions Trench means an excavation that is deeper thanits width measured at the bottom. Trench Cage means a steel support structuredesigned to resist the pressure from the walls of atrench and capable of being moved as a unit. Trench Jack means a screw or hydraulic jack usedas a brace for a temporary support structure. Tunnel means a generally horizontal excavationthat is more than a metre long and locatedunderground.
  6. 6. MAJOR HAZADRS OF EXCAVATION cave-ins or excavation collapses excavated material falling objects or objects near an excavation powered mobile equipment slips, trips, and falls hazardous atmospheres flooding/water hazards underground facilities
  7. 7. Why do serious worker injuries and fatalities continueto occur in the excavation industry? It is because both employers and workers often forgetthat when they remove earth from the ground itcreates an opening, and the remaining earthsurrounding the opening tends to relax. Thisincreases the pressure towards the walls of theopening and makes the ground collapse. Water in thesoil or ground also affects the stability of the walls byputting additional pressure on the walls andincreasing the possibility of a cave in. Unless ahorizontal distance equal to the vertical depth of theexcavation walls is maintained, engineering controlsmust be used (ex: shoring, trench cages) to provide asafe and healthy workplace within theexcavation area.
  8. 8. Falling Objects or Objects near anExcavation???Place tools and equipment used at theexcavation site so that they cannot fall into theexcavation or affect the structural stability ofthe walls of the excavation. Use barriers tohelp keep tools and equipment at a safedistance from the edge of the excavation. Useropes or other lowering devices to transportthe tools or equipment into the excavation.
  9. 9. Excavated Material? Injuries may also occur in excavation work whenexcavated material on the surface of the excavation istoo close to the edge and falls into the excavation, oraffects the structural stability of the walls of theexcavation. Pile all excavated material so that thematerial cannot roll back into the excavation. Thematerial must never be closer than one metre (threefeet) from the edge of the excavation, and should beplaced as far away as possible so it does not affect thestructural stability of the walls. Ideally, the excavatedmaterial should be placed as far away from the edge ofthe vertical excavation as the excavations height.
  10. 10. Powered Mobile Equipment Workers may be exposed to hazards whenpowered mobile equipment is used near anexcavation site. Powered mobile equipmentincludes backhoes, track hoes, concretetrucks, trucks removing excavated material andothers.
  11. 11. COMMON HAZARDS OF PME equipment placed close to the edge of anexcavation may cause the excavation walls tobecome unstable. Powered mobile equipment canbe placed near the edge of the excavation if asupport structure, designed to consider theoverload from the equipment, is installed in theexcavation. equipment vibration puts additional pressure onexcavation walls, affecting the structural stability.
  12. 12. COMMON HAZARDS OF PME equipment operating on rough terrain, or tooclose to the edge of an excavation, may roll overand fall into the excavation. Ensure all equipmentis equipped with roll over protective structures(ROPS). workers riding on equipment without approvedseats may be injured
  13. 13. COMMON HAZARDS OF PME workers getting on and off equipment are at riskbecause balance can be affected by the vibrationof the equipment. A worker may not be as surefooted getting off the equipment after operatingit for a period of time . workers may be injured by equipment. A safedistance must be maintained from movingequipment at all times. Operators must be awareof all workers near their work area.
  14. 14. Slips, Trips, and Falls Slip, trip and fall hazards are common aroundexcavations. Examples include: excavation entrancesand exits. A safe means of entering and exiting anexcavation is required. Specifically, where anexcavation is more than 1.5 metres (five feet) deep, astairway, ramp or ladder is required. Workers must useboth hands when climbing up or down ladders. Toolsor equipment should not be carried up or down theladder.
  15. 15. Slips, Trips, and Falls uneven ground surfaces around or inside anexcavation. It is important that a housekeepingprogram is in place and every effort is made toensure walkways and pedestrian traffic areas aremaintained. excavation edges are a risk to peopleworking near them. employees working near theedge of the excavation edge need to be protectedby a means of fall restraint or fall protection.
  16. 16. Slips, Trips, and Falls walkways constructed for use over an excavationmust be built and maintained for safe use byworkers. Guardrails must also be in place so that aworker cannot fall from the walkway into theexcavation. employees working around anexcavation site are at risk of falling into theexcavation. Adequate protection must beprovided for those workers as well as pedestriantraffic that may come near the edge of theexcavation.
  17. 17. Hazardous Atmospheres Hazardous atmospheres at excavation site maycome from soils that are moved or from pipes andconduits disturbed during excavation. Wherethere is a potential for a hazardous atmosphere, aplan must be developed to ensure the workers inor near the excavation are not at risk.
  18. 18. Hazardous Atmospheres Pre-Work Testing – The atmosphere must betested before anyone enters the excavation toensure they wont be exposed to hazards.Common atmospheric hazards include gasolinevapours , methane or other explosive gases and alack of oxygen.
  19. 19. Hazardous Atmospheres Controlling the Hazard – When an atmospherichazard is present, the first priorities must be toeliminate or control both the hazard and entry to theexcavation. Ventilation must be installed, operatedand maintained to ensure worker protection. Ifventilation is not practical, the worker must beprovided with personal protective equipment suitableto protect against the hazard. Forexample, when there is a lack of oxygen, the workermust be provided with an approved self-containedbreathing apparatus (SCBA) that provides adequateoxygen.
  20. 20. Flooding/Water Hazards Flooding – An excavation may flood if the work isbelow the water table, near a watercourse bank orexposed to adverse weather conditions. Whenthere is a risk of flooding, an emergencyevacuation plan must be developed. The plan willinclude a full body harness with a lifeline to beworn by workers in the excavation. Workers mustalso have direct communication with the personlocated at the surface of the excavation.
  21. 21. Flooding/Water Hazards Water Accumulation – This may be caused by anexcavation near a ground water source, in wetconditions or because of equipment that useswater for operation near the excavation site.Water accumulation must be kept to a minimumto reduce risks such as slipping or trippinghazards, electrical hazards, equipmentmalfunctions or others.
  22. 22. Underground FacilitiesCommon underground facilities include: electrical lines oil and gas lines telecommunication lines (phone, cable, computer) water and sewer lines traffic signal lines steam lines
  23. 23. Underground Facilities Special attention must be given to the hazardsassociated with underground facilities. Beforebeginning excavation work, proper planning mustidentify the location of underground facilitiesand any precautions needed to avoid contact withthese facilities.
  24. 24. Underground Facilities To ensure that all hazards are identified, owners ofunderground facilities must be notified prior tostarting excavation work. The owners of theunderground facilities must issue clearances orspecific instructions to the contractor. Theseclearances. and instructions must be available on sitefor further reference. If any pipe, conduit or cable thatis not supposed to be worked on is contacted duringexcavation work, the workers must be immediatelyevacuated from the excavation until all hazards orunsafe conditions are identified and corrected. Theowner of the facility must also be notified. Specialconsideration must also be given to prevent contactwith overhead electrical lines.
  25. 25. BEFORE YOU EXCAVATE registered as an excavation contractor with theWorkplace Safety and Health Division notified the Workplace Safety and HealthDivision of your excavation and obtained a serialnumber for your excavation obtained clearances from underground facilities obtained engineering approvals where required provided appropriate training for all workersinvolved in the excavation work
  26. 26. Requirement for EngineeringApprovals the open excavation exceeds three metres (10 feet)in depth, or the trench exceeds 4.5 metres (15 feet)in depth. a safety and health officer is of the opinion that atemporary support structure may create a risk tothe safety and health of a worker, or there is achange in the ground stability for which thesupport structure was originally installed.
  27. 27. Requirement for EngineeringApprovals the excavation may affect the structural integrity of anearby building, foundation, utility pole or otherstructure. an employer installs re-shoring. where a worker is required to enter any deepfoundation excavation, including caissons and piles, aprofessional engineer must provide approval on themethods of entry and exit as well as the equipmentand methods to be used for hoisting.
  28. 28. Training for WorkersEmployers must provide workers with informationand training on: workplace hazards that they may encounter safe work procedures developed to address thosehazards devices or personal protective equipment required andprovided for their use
  29. 29. Training needs to take place before workers perform work at the workplace before workers perform a different work activity thanthey were originally trained to perform before workers are moved to another area of theworkplace or a different workplace that has differentfacilities, procedures or hazards