Write safety measures for excavation?

SAFETY MEASURES FOR EXCAVATION 

- prior to excavation work  a complete  knowledge of underground structures  such as sewers, water pipes ,gas main etc,  is essential so as to proper precaution  to prevent accidents.

-the works must be provided with all protective  devices 

-when the depth of excavation exceeds2 m  the trenches should be securely shored and timbered 

-sheathing should be placed  against the side of the trench 

-excavated materials should be kept away from the edge of trench 

-heavy equipment such as excavation machine trucks etc ,shout  be kept away at suitable distance from the excavation sides.

-a fence or barricade should be erected and at night the area must be properly lighted  

- Consider the excavation walls angle with respect to its height and soil classification/type. to prevent any collapse.

- To provide shielding/ supporting system if required.

- Provide hard barrier around the excavation area that suits the excavation location.

- Determining all underground utilities in excavation area ( Pipe lines, High voltage cables...etc)

- Provide a watch man all the time to give instructions for the machines operators.

- Watch the weather forecast and determine the possible effects to your excavation.

 

•Specific training (soil analysis, protective systems, requirements of the Identify hazards (underground utilities, surface and ground water, nearby structures, etc.)

•Conduct inspections:

•Determine soil type (A, B, C)•Determine best protective system

•Take corrective actions, including stopping work, removing exposed employees, etc.

 

To understand the safety measures for Excavation, one has to realize the hazards related to it. The critical hazards are as follows:

1) Underground utilities like HT/ LT cables, sewage line, gas pipe-line, fibre-optic lines, etc. 

2) Overhead power lines both HT/ LT in the area of excavation

3) Hazardous gases like methane leading to asphyxiation

4) Confined space

5) Snakes, leaches, scorpion, etc may bite while manual excavation

6) Cave in due to improper excavation, also due to storing of soil very near to the edge of the pit or movement of heavy vehicles near the edge of the pit. 

7) Collapse of nearby structure due to inadequate shoring

8) Water accumulation in the excavated pit due to high water table in that region. Drowning of person in the accumulated water 

9) Fall of person in the excavated pit

10) Absence of access or egress arrangement 

The above hazards should be identified during HIRAC process and then control measures needs to be implemented. 

The control measures shall follow the heirarchy of controls:

Elimination

Substitution

Engineering

Administrative

Personal Protective Equipment

Elimination & Substitution is not possible. But we can control the hazards by implementing Engineering controls like Mechanical excavation, shoring, blowers, utility checking equipment, ladders, O2 level checking meters, height restriction barriers.

Administrative controls like Work permit, Training to equipment operators, contract workers, adequate supervision, edge protection, unauthorized entry restriction, road safety and danger signage, emergency protocol, rescue kit.

PPE- Safety shoes, helmet/ hard hat, gum boots with steel toe, insulated hand gloves, safety goggles.

What are the general hazards in a workplace and control measure to be taken to avoid them

Structural stability during excavations What you need to do The law says you must prevent danger to workers in or near excavations. To maintain the required precautions, a competent person must inspect excavation supports or battering at the start of the working shift and at other specified times. No work should take place until the excavation is safe.Commercial clients must provide certain information to contractors before work begins. This should include relevant information on:Ground conditionsunderground structures or water courses; andthe location of existing services.This information should be used to during the planning and preparation for excavation work.Key issues are:Collapse of excavationsFalling or dislodging materialFalling into excavationsInspectionWhat you need to knowEvery year people are killed or seriously injured by collapses and falling materials while working in excavations. They are at risk from:Excavations collapsing and burying or injuring people working in them;material falling from the sides into any excavation; andpeople or plant falling into excavations.Remember:No ground can be relied upon to stand unsupported in all circumstances.Depending on conditions, a cubic metre of soil can weigh in excess of1.5 tonnnes.Trenchless techniques should always be considered at the design stage as they replace the need for major excavations.Underground and overhead services may also present a fire, explosion, electrical or other hazard and will need to be assessed and managed.Collapse of excavationsTemporary support – Before digging any trench pit, tunnel, or other excavations, decide what temporary support will be required and plan the precautions to be taken.Make sure the equipment and precautions needed (trench sheets, props, baulks etc) are available on site before work starts.Battering the excavation sides – Battering the excavation sides to a safe angle of repose may also make the excavation safer.In granular soils, the angle of slope should be less than the natural angle of repose of the material being excavated. In wet ground a considerably flatter slope will be required.Falling or dislodging materialLoose materials – may fall from spoil heaps into the excavation. Edge protection should include toeboards or other means, such as projecting trench sheets or box sides to protect against falling materials. Head protection should be worn.Undermining other structures – Check that excavations do not undermine scaffold footings, buried services or the foundations of nearby buildings or walls. Decide if extra support for the structure is needed before you start. Surveys of the foundations and the advice of a structural engineer may be required.Effect of plant and vehicles – Do not park plant and vehicles close to the sides of excavations. The extra loadings can make the sides of excavations more likely to collapse.Falling into excavationsPrevent people from falling – Edges of excavations should be protected with substantial barriers where people are liable to fall into them.To achieve this, use:Guard rails and toe boards inserted into the ground immediately next to the supported excavation side; orfabricated guard rail assemblies that connect to the sides of the trench boxthe support system itself, eg using trench box extensions or trench sheets longer than the trench depth.InspectionA competent person who fully understands the dangers and necessary precautions should inspect the excavation at the start of each shift.Excavations should also be inspected after any event that may have affected their strength or stability, or after a fall of rock or earth.A record of the inspections will be required and any faults that are found should be corrected immediately

As far as the excavation safety is concerned,several factors are involved.One must have complete knowledge of soil type ,its behaviour,type of excavation whether deep or shalllow and location of excavation. After this he would be able to decide which techinque should be adopted to ensure the safety during excavation.There are different techniques,noted below:

• Nailing
• Pile Anchoring System
• Shoring
• Excavation at some Slope

Above mentioned methods will avoid the failure of banks during working in that area.Apart from that,one must have knowledge of undeground utilities. Necessary barricades,warning signs, warning tapes and reflectors must be utilized to restrict the deep excavated area for commuters.

Inspection by competent person, Striking buried services, People falling in, Objects falling in, Flooding, Hazardous substances, Battering, Shoring, Spoil heaps away from excavation, Preventing people from falling, Barriers and signs and Protective clothing.