Hazards of Excavation :- Safety Blog

                 Hazards of Excavation

 Lot of excavation is required in our refineries for the maintenance of underground facilities, modifications or new construction. An excavation authorization is required for any removal of top layer of ground within the ‘Permit required area’. An excavation authorization is a document valid for one month (renewable for two more periods) and signed by eight authorized signatories.

Excavation can result in serious injury, fatality or property damage due to the following causes and it is imperative that safety measures shall be adopted to ensure safety of personnel and equipment.

                  ·         Collapse of earthwork due to lack of, inadequate, or weak shoring.

·         Persons falling into excavations due to lack of barriers or inadequate fencing, warning signs & illumination.  

·         Soil from excavations not being thrown clear of the sides, causing overloading and collapsing of walls.  

·         Water seepage causing drowning or collapsing of walls, failure to maintain shoring, particularly after rain storm. Persons working too close together causing hazards to each other.

·         Asphyxiation and intoxication from exhaust gases of running engines which, contain CO & CO2 that may have accumulated in the bottom of the excavation.

·         Asphyxiation by Carbon Dioxide that can be present in excavations caused by air stagnation through lack of ventilation, especially on low wind days. Symptoms are dizziness, pounding in the ears, and shortness of breath. ·

·         Toxic or flammable gases or liquids accumulation from leaking pipelines, buried hazardous materials/waste (ex. Leaded sludge).

·         Exposure of foundations affecting or collapsing the supported structure.

·         Workers not being provided with or not using proper tools for the job.

·         Workers in the excavation being struck by soil or materials falling into the excavation.  

·         Falls through unsafe means of access into or out of the excavation.

·         Vehicles or equipment too close to the edge, causing the edge to collapse.  

·         Vehicles being driven into the excavation due to driving errors, inadequate warning signs, or the absence of stop blocks. Vibrations due to machinery and heavy vehicles in close proximity.

·         Striking of services, e.g., electricity/communication cables and oil/gas pipes, utility pipes.

 

 EXCAVATION PRECAUTIONS :-

Ladder shall be positioned projecting a minimum of 1 meter above the edge of the excavation. There should be at least two means of exit for persons working inside large excavation within 7.5 meters of travel distance.

·       All walkways across any excavation shall be of scaffold construction with handrails. Jumping across excavations is not allowed. ·

·         Barricade the excavation to avoid the hazard of persons and vehicles falling in. Reflective warning notices, traffic cones and flashing lights should also be provided at the edge of excavation and at a safe distance ahead.

·         During night, adequate illumination inside and outside the excavation shall be maintained if the work continues.

·         All materials, equipment and excavated soil shall be kept at least half meter away to prevent “fall in” injuries and collapse of excavation.

·         Check the excavation safeguards, shoring, sloping and supporting system before starting the job and after every rainstorm or other hazard-increasing occurrence.

       Report any damage to underground services or any other incident immediately to the ECCC.

·         Prevention of drowning: Adequate fencing, warning notices, etc., are to be provided around an excavation deeper than 1.2 meters and contains water.

·         Shoring is required if the depth of the excavation exceeds one meter. Poling boards or sheet piles shall be placed not more than 750 mm (30”) apart faced with walling at one meter centers, across-strutted with suitable timber.

·         Inspect and strutting and shoring materials before their use.

·     Sheeting shall project at least 450cm (18”) above ground level to prevent falling objects