what cave in protection is required in an open pit excavation 15 feet deep and 50 feet long and 50 feet wide.

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# EXCAVATIONS AND TRENCHES WAC [redacted identifier] defines an excavation as "Any person-made cut, cavity, trench, or depression in the earth's surface, formed by earth removal." A trench is "A narrow excavation in relation to its length made below the surface of the ground. In general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet. If forms or other structures are installed or constructed in an excavation so as to reduce the dimension measured from the forms or structure to the side of the excavation to 15 feet (4.6 m) or less (measured at the bottom of the excavation), the excavation is also considered to be a trench." One cubic yard of soil can weigh up to 3000 pounds - approximately the weight of a small car. The fatality rate for excavation work is 112% higher than the rate for general construction, according to data from the Occupational Safety and Health Administration (OSHA). The agency lists "employee injury from collapse" as the primary hazard of excavation work and includes "no protective system" among the leading causes of worker injuries. ## EXCAVATION AND TRENCHING HAZARDS Trenching and excavation work presents serious hazards to all workers involved. Cave-ins pose the most significant risk and are more likely than other excavation- related incidents to result in worker fatalities. One cubic yard of soil can weigh as much as a car. • Collapse of soils and materials (cave-in) due to lack of, inadequate, or weak protective systems • The striking or damaging of underground utility services • Persons falling into excavations due to a lack of barriers or inadequate fencing • Asphyxiation from toxic gases which have collected in the excavation/trench • Spoil (soil from excavation/trench) or materials/equipment being placed too close to the sides of the excavation/trench, which then become overloaded and collapse • Failure to check and maintain shoring, particularly after incle…

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OSHA DEPARTMENT OF LABOR AND INDUSTRY # Fact sheet # Trenching and excavation safety From 2014 through 2019, four Minnesota workers died in a trench, excavation or ground collapse. Cave-ins pose the greatest risk and are much more likely than other excavation-related accidents to result in worker fatalities. Minnesota law requires employers to provide a workplace free of recognized hazards that may cause serious injury or death. This includes the trenching and excavation requirements of 29 CFR 1926.651 and 1926.652. An excavation is any man-made cut, cavity, trench or depression in an earth surface, formed by earth removal. A trench - or a trench excavation - is a narrow excavation (in relation to its length) made below the surface of the ground; in general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet. ## Dangers of trenching and excavation In addition to cave-ins, other potential hazards include falls, falling loads, hazardous atmospheres and incidents involving mobile equipment. Two cubic yards of soil can weigh about 6,000 pounds or as much as a small car. An unprotected trench is an early grave. Do not enter an unprotected trench. ## Trench safety measures Trenches five feet deep or greater require a protective system unless the excavation is made entirely in stable rock. If the trench is fewer than five feet deep, a competent person may determine a protective system is not required. Trenches 20 feet deep or greater require that the protective system be designed by a registered professional engineer or be based on tabulated data prepared and/or approved by a registered professional engineer in accordance with 1926.652(b) and (c). ## Competent person OSHA standards require employers ensure trenches - before worker entry - are inspected by a competent person daily and as conditions change, to ensure elimination of excavation hazards. A competent person is an individual: who is capab…

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# Table of Contents (cont.) ## Inspection Guidance. (cont.) a. § 1926.652(a)(1). Consider a citation of § 1926.652(a)(1) if employees are working in an excavation that is not entirely in stable rock, and that is either at least 5 feet (1.52 meters) deep or is less than 5 feet deep and a competent person failed to assess that there was no indication of a potential cave-in. b. § 1926.652(a)(1) verses § 1926.652(b) or (c). Where a protective system is required, the employer is obligated to provide one designed in accordance with §§ 1926.652(b) or 1926.652(c). If a protective system has been provided but does not meet the criteria in §§ 1926.652(b) or (c), consider a citation specific to the appropriate/applicable provisions of (b) or (c), described below. A citation of § 1926.652(a)(1) should not be considered if a protective system is provided and in place, yet inadequate. c. § 1926.652(a)(1) verses § 1926.651(k)(2). As noted previously, citing both § 1926.652(a)(1) and § 1926.651(k)(2) is generally not appropriate. Consider a citation of § 1926.652(a)(1) where there is no protective system in place and employees are exposed to cave-in hazards. Citations under § 1926.651(k)(2) may be appropriate if an otherwise-compliant excavation has become compromised and the competent person failed to remove employees from the hazardous area. (See previous discussion on § 1926.651(k)(2)). § 1926.652(a)(2) requires the employer to implement a protective system with the capacity to resist all intended or reasonably expected loads to be applied or transmitted to the system. ## Inspection Guidance. In evaluating the chosen design of sloping and benching systems, refer to Appendix B to Subpart P – Sloping and Benching, which contains specifications for sloping and benching when used as methods of protecting employees working in excavations from cave-ins. Appendix B can be used to evaluate the slope or bench system chosen based on the soil conditions present. (See also the discus…

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# standard. (Note that requirements under 1926 Subpart G - Signs, Signals, and Barricades may also apply.) (cont.) ## Citation Policy (cont.) This section provides four alternatives for the design and construction of sloping and benching systems for protecting employees working in excavations. As defined in § 1926.650(b), "Benching” means “a method of protecting employees from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near-vertical surfaces between levels.” “Sloping” refers to “a method of protecting employees from cave-ins by excavating to form sides of an excavation that are inclined away from the excavation so as to prevent cave-ins." ## § 1926.652(b)(1). Option (1). Allowable configurations and slopes. Under this Option, the excavation sides must be sloped at an angle that is not steeper than one and one-half horizontal to one vertical (1.5H:1V, 34 degrees measured from the horizontal). Employers may cut the excavation to the slope specified by this option without the need for initial testing and classifying the soil at the excavation site. NOTE: Where the evidence shows that no support system was used and that the sides of the excavation are steeper than 1.5H:1V, the employer has the burden of proving compliance with one of the other protective system options under this section or § 1926.652(c). The CSHO, however, should document all relevant information concerning the excavation, including any protective systems in place or lack of protective systems, to support a potential citation. NOTE: If an excavation is 20 feet or less in depth and sloped in accordance with the requirements of § 1926.652(b)(1)(i) (i.e., the slope is not greater than 34 degrees measured from the horizontal), then soil classification tests are not required. If an employer assumes type C soil is present, and provides the protection (sloping, shoring or shielding) required for type C soil, a citati…

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# NOTE: § 1926.651(i) Stability of adjacent structures sets forth the employer's responsibility to support adjacent structures (e.g. buildings, walls, or other structures). See the discussion of citation policy for § 1926.651(i) below. (cont.) ## Citation Policy (cont.) This section provides four alternatives for the design and construction of sloping and benching systems for protecting employees working in excavations. As defined in § 1926.650(b), “Benching” means “a method of protecting employees from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near-vertical surfaces between levels." "Sloping" refers to "a method of protecting employees from cave-ins by excavating to form sides of an excavation that are inclined away from the excavation so as to prevent cave-ins." ## § 1926.652(b)(1). Option (1). Allowable configurations and slopes. Under this Option, the excavation sides must be sloped at an angle that is not steeper than one and one-half horizontal to one vertical (1.5H:1V, 34 degrees measured from the horizontal). Employers may cut the excavation to the slope specified by this option without the need for initial testing and classifying the soil at the excavation site. NOTE: Where the evidence shows that no support system was used and that the sides of the excavation are steeper than 1.5H:1V, the employer has the burden of proving compliance with one of the other protective system options under this section or § 1926.652(c). The CSHO, however, should document all relevant information concerning the excavation, including any protective systems in place or lack of protective systems, to support a potential citation. NOTE: If an excavation is 20 feet or less in depth and sloped in accordance with the requirements of § 1926.652(b)(1)(i) (i.e. the slope is not greater than 34 degrees measured from the horizontal), then soil classification tests are not required. If an employe…

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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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# 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…

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# Requirements for Protective Systems {Division 3/Subdivision P 29 CFR 1926.652} (cont.) ## Selection of Protective Systems (cont.) This material is for training use only # Protective Systems [29 CFR 1926.652(a)] Excavations and trenches less than five feet deep must still be sloped, benched, or otherwise supported when a Competent Person determines there is indication of cave-in. a Be careful not to get caught up on just the five foot depth requirement. Consider work practices in a shallow trench as well (i.e. working hunched over or on hands and knees). ## Selection of Protective Systems Protective systems are divided into two categories and include four choices in each: 1. Sloping and benching systems; and 2. ...everything else. The basic systems for protecting employees from cave-ins are sloping, benching, shoring, and shielding. The system that you should use depends on factors such as soil type and water content, excavation depth and width, the nature of the work, and nearby activities that could increase the risk of a cave-in. The competent person has the responsibility for considering these factors and for determining the appropriate protective system. A registered professional engineer must design protective systems for all excavations that are more than 20 feet deep. (from OR-OSHA's publication titled, “Excavations” Pub. #440-2174 (6/06)). OR-OSHA 302 Excavation Safety 24

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# Welcome Page (cont.) ## Cave-ins: (cont.) This material is for training use only # Scope, Application, Definitions {Division 3/Subdivision P 29 CFR 1926.650} ## Scope and Application This subpart applies to all excavations made in the earth's surface. Excavations are defined to include trenches. ## Some KEY Definitions: Competent Person means one who is capable of identifying existing and predictable hazards in the surroundings, or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them. Protective System means a method of protecting employees from cave-ins, from material that could fall or roll from an excavation face or into an excavation, or from the collapse of adjacent structures. Protective systems include support systems, sloping and benching systems, shield systems, and other systems that provide the necessary protection. Registered Professional Engineer means a person who is registered as a professional engineer in the state where the work is to be performed. However, a professional engineer, registered in any state is deemed to be a “registered professional engineer" within the meaning of this standard when approving designs for "manufactured protective systems" or "tabulated data” to be used in interstate commerce. Support System means a structure such as underpinning, bracing, or shoring, which provides support to an adjacent structure, underground installation, or the sides of an excavation. Tabulated Data means tables and charts approved by a registered professional engineer and used to design and construct a protective system. Trench (Trench excavation) means a narrow excavation (in relation to its length) made below the surface of the ground. In general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet. OR-OSHA 302 Excavation Safety 3

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# Trenching and excavation safety (cont.) ## General trenching and excavation rules (cont.) • Test for atmospheric hazards, such as low oxygen, hazardous fumes and toxic gases when greater than four feet deep. • Inspect trenches at the start of each shift and following a rainstorm or other water intrusion. • Do not work underneath suspended or raised loads and materials. • Inspect trenches after any occurrence that could have changed conditions in the trench. • Ensure personnel wear high-visibility or other suitable clothing when exposed to vehicular traffic or mobile earth-moving equipment. ## Protective systems There are different types of protective systems – sloping, shoring and shielding. <table><tr><th>Type of protective system</th><th></th><th>Illustration of system</th></tr><tr><td>Sloping involves cutting back the trench wall at an angle inclined away from the excavation.</td><td>20 MAX</td><td></td></tr><tr><td>Shoring requires installing aluminum hydraulic or other types of supports to prevent soil movement and cave-ins.</td><td></td><td></td></tr><tr><td>Shielding protects workers by using trench boxes or other types of supports to prevent soil cave-ins. Designing a protective system can be complex because many factors must be considered: soil classification; depth of cut; water content of soil; changes caused by weather or climate; surcharge loads (spoil, other materials to be used in the trench); and other operations in the vicinity.</td><td></td><td></td></tr></table> ## More information To learn more about excavation safety, view the standards at osha.gov. Revised March 2025

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Trenching Safety Preventing Cave-ins Trenching work is risky; cave-ins occur suddenly and bring lasting, tragic consequences. Safety preplanning, oversight, and training are key to ensuring work is set up and performed safely in trenches. ## Protective Systems Protective systems prevent cave-ins and protect workers from falling materials. There are three types: ■ Sloping and benching removes soil to eliminate the chance of cave-ins (benching isn't an option for sand, gravel, and other Type C soils). a ■Shoring uses supports to brace the walls of trench (e.g., aluminum hydraulic supports). ■ Shielding protects workers inside of the shielded area (e.g., trench boxes). Protective systems are required for all trenches four feet or deeper; and for those less than four feet deep if a potential for cave-in exists. Systems for trenches over 20 feet deep must be designed by a registered professional engineer (or designed according to tables, charts, and other tabulated data approved by them). ## Competent Person A competent person is someone who: ■ Conducts daily safety inspections of excavation areas, including protective systems, to identify existing and potential hazards. ■ Has the knowledge and authority to take immediate corrective measures to eliminate hazards and conditions; and has the authority to remove workers promptly if hazardous conditions are found. ## Getting In and Out Safely Workers must be able to easily and safely enter and exit trenches four feet or deeper. A way in or out must be available every 25 feet. The most common method for access is a straight ladder or an extension ladder. If a ladder is used, it must extend at least three feet above the landing. Other means could be a stairway or ramp designed by a registered professional engineer. ## General Safety Tips ■Don't let workers enter or work inside an unprotected trench four feet or more in depth. ■Never work inside a trench if the spoils pile is less than two feet away from the e…

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# What are the soil classification categories? (cont.) ## What types of protective systems can employers use to protect workers from cave-ins? (cont.) Figure 2. Trench Shields The Excavation standards do not require a protective system when an excavation is made entirely in stable rock or when an excavation is less than 5 feet (1.52 meters) deep and a competent person has examined the ground and found no indication of a potential cave-in. ## What other precautions do employers need to take to protect workers from cave-ins? The Excavation standards require employers to provide support systems, such as shoring, bracing, or underpinning, when necessary to ensure that adjacent structures (including adjoining buildings, walls, sidewalks and pavements) remain stable for the protection of workers. The standards also prohibit excavation below the base or footing of any foundation or retaining wall that could be reasonably expected to pose a hazard to workers unless: ■The employer provides a support system, such as underpinning; - The excavation is in stable rock; or Trenching and Excavation Safety 7

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# Scope, Application, Definitions {Division 3/Subdivision P 29 CFR 1926.650} (cont.) ## Some KEY Definitions: (cont.) This material is for training use only # Scope, Application, and Definitions Excavations are defined to include trenches. The definition of an excavation is a man-made cut, cavity, or depression in the earth's surface (including open- face excavations). More on trenches below. Competent Person - same "competent person" definition in OR-OSHA Div 3/Subs M, L, R, etc. Two part definition - must have authority to correct Open-face excavation hazards on site. Only the employer can deem someone a competent person because only their employer can grant them authority. OR- OSHA Div 3/Sub P does not require the competent person to be on the job 100% of the time; however, considering the number of specific responsibilities he/she has - it wouldn't be a bad idea. The following is a summary of the specific duties required in the standard: Structural ramp design, water removal monitoring, daily inspections, removing employees from serious hazards, equipment inspection to determine continued use/removal from service, soil classification, and reducing soil surcharges. Protective System basically means anything to protects from cave-in or collapse. Support System basically means everything that protects from cave-in or collapse besides sloping and benching systems. Tabulated Data is the documentation confirming a safe system - whatever the system is. OSHA includes tabulated data in Appendices B, C, and D. Of course, manufacturers of protective systems as well as other sources (vendors, engineers) provide tabulated data too. The following is from an OR-OSHA Letter of Interpretation dated 7/25/02: "You ask in your letter if tabulated data for components of shoring systems, used in excavations, is allowed to be identified by model number, or if serial numbers have to be used. There are no rules in 1926.652(c)(1), (2), or (3) that specifically address how to ma…

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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…