In general, an excavation is a hole in the earth created by the removal of material. An excavation when the depth is greater than (larger than) the width is called a trench.
What dangers are present during excavation and trenching?
Both the employees inside the trenches and the workers on the surface confront risks when working in excavations and trenches. The risks consist of: collapses or cave-ins that could capture or crush workers falling objects or dug dirt injuring employees (e.g., equipment is operated or soil and debris is stored too close to the excavation). falling into an excavation or trench. flooding or water buildup exposure to a dangerous environment (e.g., gas, vapour, dust, biological contaminants, or lack of oxygen). contact with underground utility lines, including buried ones for telecommunications, water, sewage, electricity, and natural gas. contact with electrical cables above. slips, trips, and falls that occur as workers use the wrong access and egress procedures or while getting on and off of machinery. being struck by moving machinery, falling objects, or things in the air. handling of materials-related risks (e.g., lifting, struck by, crushed between, etc.).
What do soil kinds refer to?
In Canada, different jurisdictions have different definitions of soil types. Additionally, some governments don't designate soil types but do call for precautions to be taken when an excavation exceeds a specific depth or size. The goal of defining a soil type is to attempt to identify or anticipate the likelihood that the soil may move and potentially cause a collapse while the activity is being done. A scale of A to C, where A is hard and solid and C is soft, sandy, filled, or loose, is more commonly used to describe soil types. On this scale, 1 is firm and dense, and 4 is loose, soft, wet, or muddy soil. The soil's consistency, ease of removal, look, suitability for hand-versus-machine excavation, water seepage, previous excavation history, etc. all play a role in identifying the kind of soil.
What should happen before an excavation starts?
Before starting any work, the employer or supervisor is responsible for identifying any hazards and risks and must take the required precautions. These actions consist of: Determine which soil type(s) are appropriate for the trench or excavation you plan to dig. Within a single trench, soil characteristics frequently vary greatly (e.g., the soil type changes from top to bottom and along the length of a trench). Search for the applicable legal requirements in your area and the appropriate protective measures. Find all underground services. Ask the owners of any subterranean facilities or services that may be present there to identify and designate the location by getting in touch with them. Locate and identify any overhead electrical wires. As necessary, make sure to de-energize these services. In case of an emergency, be aware of all of these services' phone numbers. Look around the location for any potential dangers or sources that might affect the soil's stability. Be cautious since neighboring machinery and cars may cause the dirt to vibrate before collapsing. Ascertain whether the foundations of any surrounding structures or buildings may exert pressure on the soil and influence the trench's walls. Before entering, check for dangerous dust, vapors, and gases. Before entering the space and as needed throughout the work, check the oxygen levels. Plan for proper worksite organization and excellent housekeeping procedures, such as transferring waste and dug-up soil sufficiently away from the excavation site. Get rid of the water in the excavation. Avoid having workers fall into the excavation. Make sure that each employee is wearing the proper personal protective equipment, such as high visibility clothing for vehicular traffic. When a worker is working in a trench, have a worker above ground to alert people in the trench to danger and to provide emergency assistance. Ascertain whether the trench qualifies as a restricted space. If so, hold off on letting workers into the trench until all conditions of the organization's confined space program have been satisfied, such as entrance permits and training. Prepare the necessary work permits for limited space work. Provide a path out of the trench from the inside, often no more than 8 meters (25 feet) away from any worker in the trench. Create a plan for bad weather (e.g. hot or cold environments, storms, etc.). Create a rescue plan and emergency procedures. Keep first aid supplies on hand. Workers should be instructed on all current and potential risks, hazards, and safety measures.
What elements define the most suitable defensive system to employ?
In general, unless the excavation is fully in stable rock, trenches that are 1.2 meters (4 feet) deep or deeper require a protection system. The things to think about include: Type of soil Cutting depth Due to weather or climate, the soil's water content changes. Surcharge loads and other nearby operations (such as spoil and other items to be used in the trench) Always examine your jurisdiction's legal guidelines regarding the application of safety measures.
What different kinds of defense mechanisms are employed to prevent cave-ins?
There are two basic methods of protecting workers against cave-ins: Sloping Temporary protective structures (e.g., shoring, trench boxes, pre-fabricated systems, hydraulic systems, engineering systems, etc.) Sloping Sloping involves cutting back the trench wall at an angle that is inclined away from the work area of the excavation. The angle of slope required depends on the soil conditions. Benching is a similar method to sloping. Temporary protective structure WorkSafe Saskatchewan defines a temporary protective structure as “a structure or device in an excavation, trench, tunnel or excavated shaft that is designed to provide protection from cave-ins, collapse, sliding or rolling materials, and includes shoring, trench boxes, trench shields and similar structures.” Shoring is a system that supports the sides or walls. Shoring requires installing aluminum, steel, or wood panels that are supported by screws or hydraulic jacks. Some systems can be installed without the workers entering the trench. This option provides additional safety for those workers. Wherever possible, install the shoring equipment as the excavation proceeds. If there is any delay between digging and shoring, no one should enter the unprotected trench. Trench Boxes are commonly used in open areas that are away from utilities, roadways, and foundations. Trench boxes can be used to protect workers in cases of cave-ins, but not to shore up or support trench walls. They can support trench walls if the space between the box and the trench wall is backfilled with soil and compacted properly. Otherwise, a cave-in or collapse may cause the trench box to tilt or turn over. Workers should not be present in the box when it has to be moved. Other: In some cases, the trench or excavation walls are made of rock but are not entirely stable. Support the walls by using rock bolts, wire mesh, or a method that provides equivalent support.
What should NOT be done during an excavation?
Do not enter an unprotected trench deeper than 1.2 metres (4 feet), or as specified in the legislation. Do not start digging before locating and de-energizing the buried services. Do not enter a trench before testing the air for hazardous gasses and vapours, or the lack of oxygen. Do not place the sections of pipes, piles of spoil, unused tools, and timber, and other materials within 1 metre from the trench's edge. Do not rely on natural freezing to act as a method of soil stabilization. Do not work under suspended or raised loads and materials. Do not stand behind a backing vehicle.
What can be included in a trenching and excavation inspection checklist?
The following are some points to consider. Each circumstance will be different, so be sure to adapt the questions to suit your situation. Underground or Utility Services Know the contact numbers? Located, identified and informed respective parties? Grounded, isolated, de-energized, or protected from unplanned release? Housekeeping Excavated material, pipes etc. are placed 1 metre away from the edge of the excavation or trench wall? Are pumps available to remove water? Is the base and foot of the ladder secure, and free of garbage or water? Are materials placed on the site obstructing the worker's or vehicle's ability to move freely? Are established traffic controls used, where required, including adequate signage, personnel, and lighting? Has the excavation been marked to make the workers and others aware of the excavation (e.g., fence, flags, or other safeguards)? Are sanitary facilities available at the site, as appropriate? General Are proper barriers or guardrails in place to protect anyone or equipment falling into the excavation or trench? Has the air in the excavation been tested for low oxygen, and hazardous gasses and vapours? Is a safe means of entry and exit provided such as a sufficiently long and secured ladder placed at appropriate distances (within 25 feet of all workers)? Are cracks visible in the ground around the trench or excavation that may indicate soil movement? Are there any signs of water seeping into the trench or excavation? Are workers wearing appropriate PPE (e.g., hard hats, respirators, , safety boots, hearing protection)? Are high visibility vests or clothing provided and worn by all exposed to vehicular traffic? Is first aid equipment available at the site? Are operators qualified to operate the heavy machinery or equipment? Does a competent person regularly inspect the excavation (at the start of each shift before work begins or after any event likely to have affected the strength or stability of the excavation)? Is there a competent person stationed at the surface of the trench to warn workers in the trench of danger and to provide emergency help? Is the trench a confined space, and are the requirements of the confined space program met? Sloping Has the soil type been considered when determining the angle of the slope? Are they being sloped or benched back to a safe angle? Temporary protective equipment, such as: Timber Shoring Is the shoring equipment the right equipment as required for the depth of the trench or excavation and type of soil? Is the equipment damaged (e.g., cracked, crushed, split, or bowed)? Are there loose or missing cleats? Are the struts off level? Trench Boxes Are the boxes damaged or have defects? Are the plates deformed, bent, have holes, or show other damage? Are the welds cracked, bent, or distorted? Are there missing or missing struts? Are trench boxes shifting or settling to one side? Hydraulic Shoring Are there any visible leaks in hoses or cylinders? Are there bent bases? Is any equipment cracked, split, broken or cracked?"""