Write a toolbox talk on Excavation and trenching safety

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# Trenching and Excavation (cont.) ## What factors determine what is the appropriate protective system to use? (cont.) - Water content of soil - Changes due to weather or climate - Surcharge loads (e.g., spoil, other materials to be used in the trench) and - Other operations in the area Always check the legislative requirements in your jurisdiction related to the use of protective systems. ## What are the different types of protective systems used to protect against 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. Trenching and Excavation CCOHS

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# Trench and Excavation Safety Trench collapses, or cave-ins, are the leading hazard in excavation work. Safe trenching helps prevent falls, falling loads, hazardous atmospheres, and incidents involving mobile equipment. ## Trench Safety Measures Trenches 5 feet or deeper require a protective system unless dug in stable rock. For trenches less than 5 feet, a competent person must decide if protection is needed. Trenches 20 feet or deeper must have a protective system designed or approved by a registered professional engineer, as required by OSHA 1926.652(b) and (c). ## Competent Person Before workers enter a trench, a competent person must inspect it daily and after any condition changes to ensure safety. This person is trained to identify hazards, determine soil types, select protective systems, and has the authority to correct issues immediately. ## Access and Egress • Keep heavy equipment and spoils at least 2 feet from trench edges - Locate underground utilities before digging • Test for atmospheric hazards in trenches over 4 feet deep • Inspect trenches daily, at the start of each shift, after storms, and after conditions change • Never work under suspended loads - Wear high visibility clothing when near traffic # Protective Systems • Benching: a method of protecting workers from cave-ins by cutting the sides of an excavation into horizontal steps. Benching is not allowed in Type C soil. • Sloping: involves cutting back the trench wall at an angle inclined away from excavation. • Shoring: requires installing aluminum hydraulic or other types of supports to prevent soil movement and cave-ins. • Shielding: protects workers by using trench boxes or supports to prevent cave-ins. Designing these systems can be complex, as factors like soil type, trench depth, moisture, weather, nearby loads, and site activity must all be considered. OSHA standards require that employers provide workplaces free of recognized hazards. The employer must compl…

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# [redacted identifier] - Definitions ## Cave-in The separation of a mass of soil or rock material from the side of an excavation, or loss of soil from under a trench shield or support system, and its sudden movement into the excavation in quantity that it could entrap, bury, injure, or immobilize a person.

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# Toolbox Talks Preventing Excavation/Trench Cave-ins - Ask the following questions and give time for answers. ## What are the hazards? Bodily or equipment entrapment in soil. ## What are the results? Broken or crushed limbs and bones, entrapment, suffocation, head injury, internal damage, and death. ## What should we look for? Stable rock and soil type (A, B, C), depth of excavation, cave-ins, water in trench, weather conditions (rain, frost), water table, protective systems, competent person, operation of heavy equipment near excavation, barricades, and falling loads. ## How do we prevent these results? • A competent person must evaluate excavations daily. Excavations should be re-evaluated after events such as rain. • Use shoring equipment, shielding, and/or sloping or benching systems for excavations greater than 5 feet in depth or less when deemed necessary by the competent person. • Examine protective systems in accordance with manufacturers recommendations and remove damaged systems from service. • Excavated material/other objects must be kept at least 2 feet from edge. ## Understanding Soil Types • Type "A" - most stable (clay, hardpan) • Type "B" - next most stable (slit, loam, unstable dry rock) • Type "C" - least stable (gravel, loamy sand) ## Let's talk about this site now How can you prevent cave-ins? Shoring, shielding, sloping, and/or benching. At what depth is cave-in protection required? 5 feet or less depending on the assessment by a competent person. Name some conditions that can increase cave-ins. Rain, heavy equipment, vibration, spoil piles, etc. The unfortunate reality - From 2011 to 2021 there were at least 220 trenching fatalities across the United States. These fatality incidents were preventable with the use of a protective system, proper employee training, and implementation of a safety and health management system. ## AN UNPROTECTED TRENCH IS AN EARLY GRAVE DOLI VIRGINIA DEPARTMENT OF LABOR AND INDUSTRY in li…

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# Tennessee OSHA's Special Emphasis Program on Trenching & Excavation Because trenching and excavation collapse is deadly and often involves multiple victims, Tennessee OSHA has established a special emphasis program to focus attention and resources on these hazards. It is impossible to predict when an excavation or trench will collapse. The sudden collapse of the walls makes escape almost impossible. The only way to prevent collapse is to slope or shore the walls or install a trench shield and follow the TOSHA trenching and excavation standards contained in 29 CFR 1926 Subpart P. Under this special emphasis program, all TOSHA compliance and consultative services personnel will be on the lookout for trenching or excavation work sites. Personal observation, reports of imminent danger, fatality/catastrophe reports, safety and health agency referrals, employee complaints, and media reports are also used to locate trenching and excavation work. Each occurrence is handled with an appropriate intervention by TOSHA. ## Hazards on the Excavation Site Excavation workers are exposed to many hazards, but the chief hazard is cave-in. TOSHA requires that all employees exposed to potential cave-ins be protected by sloping or benching the sides of the excavation, shoring the sides of the excavation, or placing a shield between the sides and the work area. In addition to cave-in hazards, workers must also be protected from adjacent utility lines, exposure to vehicular traffic, falling loads, hazardous atmospheres, and fall hazards. Utility lines such as gas, electrical, sewer, and water must be located and supported prior to placing employees in an excavation. Employees working in, or near, roadways must wear high visibility vests. Workers are not to work beneath suspended loads, and walkways crossing excavations must be equipped with guardrails. Precautions, including atmospheric testing and emergency rescue procedures and equipment, must be taken when workers enter excavat…