Excavations

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SAFETY TALK 

EXCAVATIONS

Lot of excavation is required in 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 stagnations 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/communicationcables 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 maintainedif 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.

Key points to remembered during excavation:-

1. Work permit for excavations must be obtained prior to starting work. It is very important to know the location of buried piping, electrical lines, etc.,. before excavating. Buried lines must be identified, marked and stated on excavation permits
2. The Client will issue and approve excavation permits.
3. If employees are to enter an excavation the following rules apply:
• Excavation spoil must be moved at least 1.5 meters away from the edge of the excavation.
• Shoring must be used, or the excavation must be sloped to prevent collapsing when the excavation depth is greater than 1.2 meters.
•  Ladders or stairs must be provided when excavations are more than 1.2 meters deep.
• Ladders, when required, shall not be more than 8 meters apart. 
4. Excavations in SOLID rock are the only types exempt from shoring or sloping.  
5. In some cases, excavations will need to be gas tested before employees may enter. This is required when crude oil, gasoline, or other hydrocarbon is in an excavation.  
6. Other precautions, such as respirators may be required, depending. on gas test results.  
7. The Safety Department will conduct inspection , gas tests and record results on a work permit.

Do not dig your own grave “dig” the rules

1. Before digging make sure the electric, water, gas and other services have been located and marked clearly and the organization work Permit to Dig has been obtained.
2. All excavations MUST be assessed for the need for support of being battered/benched to a safe angle.
3. Ladders must be used for access and egress from excavations, do not climb on the supports
4. Warning barriers must be placed around all shallow excavations and scaffold or adequate timber barriers must be provided around deep excavations i.e. 2 meters or deeper.
5. All reinforcement starter bars in excavations (any depth) must be protected to prevent the possibility of puncture injuries.
6. Keep spoil heaps, materials, tools, and vehicles away from edges of excavations
7.  All exposed services must be adequately protected from damage.
8.  When tipping into excavations, secured stop blocks are required to prevent vehicle running into the excavation.
9.  Do not jump across excavations; provide bridge access ways with guardrails.
10.  Do not alter or remove any support unless it is covered in your method statement and it is safe to do so.
11.  Ensure your excavation is examined at least daily and recorded in the site inspection register.
12.  Check that the excavation has been assessed to be classed as a confined space or not. If so get a Permit to Enter from organization .
13. Always follow the organization Excavation Procedure.

EXCAVATION WORK

1. Do not work in an excavation unless it is considered safe to do so by your Foreman.
2. Use gangways provided for crossing excavations.  Do not jump across.
3. Do not stand on struts.
4. Do not interfere with the positioning of barriers of supports in excavations or trenches unless authorized to do so.
5. Ensure that manholes or other openings are covered or an effective barrier is erected.  Barriers to excavations must be at least 1m high.
6. Be careful of slipping when using ladders in trenches, especially in wet and greasy conditions.  All ladders must be secured and extend at least 1.070 m (3’6”) above landing.
7. Keep walkways clear and free from rubbish at all times.
8. When vehicles are working near the edges of excavations, chocks should be positioned to prevent tipping vehicles over-riding or falling in.
9. Never work in an excavation over 1.210 m (4”) in depth unless it is timbered or battered to a safe angle or in solid rock.
10. Never work beyond the supported sides of an excavation.  If an excavating machine is being used, always face it.
11. Keep working areas above and alongside trenches or excavations, clear of objects or loose materials.
12. Ensure timber for supporting trenches is sound.  See that nails have been removed or hammered down.
13. Always use hard barriers when close to vehicles.