Tuesday, June 9, 2020

Excavation Safety Precautions and Permit to Work

What is Excavation or Excavation Work?

Excavation work basically means various work activities such as the removal of soil or rock from a worksite to make or create a hole, cavity or open face with the help of heavy tools, machinery or if it is in the rocky area, then using the explosives.

Excavation Safety Precautions and Permit to Work

The working with excavation activities is always full of critical hazards and risk of physical, biological, mechanical is always high. For the accomplishment of such work, some certain precautions should be taken to minimize the risk of human injuries. Mostly, prior the start of excavation proper documents procedures must be followed such as risk assessments, method of statement, toolbox talks, etc. The most essential document procedure is the permit to Work that allows you as health and safety engineer/manager or officer, employer and or contractor to consider and record all of the critical possible hazards related to the excavation work that they are going to conduct and the mandatory precautions/initiatives that must be taken. By observing and seeing these hazards, the possibility for serious accidents is reduced and therefore, the permit to work (PTW) will help to assure the occupational health & safety of workforce and contractors.

The Basic Hazards and Risks Related to Excavation Are Generally:

  1. Materials and or substances falling onto the workforce while carrying out their work in the in the excavation.
  2. Sides of the excavation collapse
  3. Falling of vehicles and employees/general public/visitors into the excavation.
  4. Collapse of adjacent structures into the excavation.
  5. Severe possibility of electrocution, explosion, gas leakage, flooding due to the damage to underground services during excavation work.
All type of excavation work activities should be planned properly and a clear work plan must be acknowledged to all the personals involved in the work including the power supply services companies, heavy machinery operators, contractors etc. Also ensure that all required tools, equipment, materials and first aid /medical emergency are in place to handle any severe incident or accident. Ensure that the work is monitored by the project engineer and being supervised by a competent supervisor and the excavation works are inspected routinely on daily bases by someone who have the deep and strong knowledge, ability and experience regarding the risks and precautions to be taken. As per requirement and standard procedures under national and international governing bodies and institutions, at least once a week the excavation should be completely inspected and the workforce and operators involving in the excavation works must be inducted if there is any hazard observed, and also after any event such in case of any severe and strong wind or rains, which may affect the temporary support. All such inspections should be documented.

The Safety Initiatives to Be Taken Are:

Battering the Side
  1. Most of common the buried accidents occurred due to the collapse of the trench. So, to minimize the risks of its collapse should be avoided by battering the sides to a safe angle or by supporting them with sheeting or retention/proprietary support systems. Such supporting system should be installed as soon as the work progresses. The most prominent initiative is to ensure the workforce are professional, competent and experienced as far as possible and that they have clear instructions and inducted properly.
  2. Secure the workforce from falling into excavations by steady and strong barriers around the edges. This type of barrier system must be carried out if the depth of the excavation is more than two meters but it is suggested for excavations of lesser depths.
  3. Soil that is excavated, tools, plant, equipment, materials or substances should not be stored close to the sides of excavations as loose material can fall in. Severe Possibility of collapse of the sides of excavations if extra load kept or stored. 
  4. Prevent heavy vehicles, or other tools from falling into excavations or surcharging and causing the collapse of the sides of the excavation by keeping them out of the area. To protect such type of collapse due to vehicles fall into the excavation, barriers can be installed and should be painted with florescent colors to be easily visible particularly while working at night shifts. Due to the usage of such initiatives, vehicles tip materials into excavations, then they should be secured and prevented from over-running into the excavation by using stop blocks system.
  5. A proper access and egress should be available for safe and secure movement of the workforce involved in the excavation work activity.
  6. Because most of the excavation work is carried out with the heavy equipment and machinery and that machinery is powered and energized by the diesel and or other lubricants and the Hazardous fumes should be generated in abundance. Such equipment/machinery should not be permitted/allowed into excavations without arranging for exhausts to be released away by using ventilation system.
  7. Water and power energizing services such as gas, electricity or water supply pipes and Cable plans should be utilized to locate underground services which should be marked on the ground and if possible digging work activity should take place as far as possible from them. If possible, always use the latest underground detecting/locator device technology during the excavation work. The most important care regarding the locators should be taken to ensure that mechanical means of digging are not used within 0.5 meters of underground services (UGS) and spades and shovels should be prioritized instead of picks and forks which are more likely to pierce cables. When all energized services are detected, located or exposed, then they should be supported. All new and existing power generation services should be lastingly marked by the use of proper tapes over the service and by installing permanent markers above ground indicating information such as the service type, depth, route etc.
  8. Safety initiatives should be taken against severe flooding due to heavy rain water or big water pipe damage by installing adequate means of pumping out the excavations ensuring that the outflow from the water pump does not cause flooding problems elsewhere.

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