Module 9: Excavations

OSHA Online Outreach Course Materials

OSHA mandates that students spend a specific amount of time in each module of this course. In order to comply with OSHA’s requirement, additional resources related to this module’s content are provided below. You should also consider reviewing the Fact Sheet for this module, which is located at the end of this resource list.

When the minimum required time for this module has elapsed, you will be allowed to proceed to the next module.

CAUTION: When closing resource links, take care to not close your course browser window, as that will stop the module timer.

Module 9: Excavations Title URL Topic 1 Excavations-Trench Hazards Excavations: http://www.osha.gov/doc/outreachtraining/htmlfiles/excavate.html Construction Safety and Health Outreach Program Excavations OSHA http://www.osha.gov/Publications/osha2226.pdf 2226 Trenching and http://ehs.okstate.edu/MANUALS/Trench.htm Shoring Procedures Topic 2 Cave-in Prevention Methods Trenching and http://www.osha.gov/Publications/trench_excavation_fs.html Excavation Safety Fact Sheet Trenching and https://www.osha.gov/SLTC/trenchingexcavation/index.html Excavation American Pipeline http://www.americanpipeline.org/BestPractices/English/ExcavAndTrenching_O Contractors perators.pdf Association: Excavation & Trenching Best Practices Preventing Deaths http://www.cdc.gov/niosh/docs/85-110/ and Injuries from Excavation Cave-Ins Preventing Worker http://www.cdc.gov/niosh/docs/wp-solutions/2011-208/pdfs/2011-208.pdf Deaths from Trench Cave-ins

Topic 3 Hazard Elimination - Reduction OSHA Technical http://www.osha.gov/dts/osta/otm/otm_v/otm_v_2.html

OSHA Online Outreach Course Materials

Module 9: Excavations

Module 9: Excavations Title URL Manual: Section V: Chapter 2 Excavations Trenching and https://www.osha.gov/SLTC/trenchingexcavation/index.html#recognition Excavation: Hazards and Solutions Topic 4 Role of Competent Person Competent Person https://www.osha.gov/SLTC/competentperson/index.html Virginia Tech: http://www.ehss.vt.edu/uploaded_docs/200802201521540.Microsoft%20Word Excavation Safety %20-%20Excavation%20Safety%20Rev%20May%202007.pdf Trenching and http://www.osha.gov/OshDoc/data_Hurricane_Facts/trench_excavation_fs.pdf Excavation Safety: OSHA Fact Sheet Working Safety in http://www.osha.gov/Publications/trench/trench_safety_tips_card.pdf Trenches: OSHA Quick Card

FactSheet

Module 9: Excavations In this module, we cover information that will enable workers to recognize hazards and best practices associated with excavations and trenching.

Module Objectives o Falling loads – tools, equipment, or construction materials could fall into the Terminal Objective trench or excavation. Given current OSHA and industry information regarding Hazardous environment – excavations and construction worksite illnesses, injuries, and/or fatalities, o trenches could be considered a confined the student will be able to recognize hazards and best space which can pose potential risks of practices associated with excavations and trenching. oxygen deficiency, toxic fumes, and water Enabling Objectives accumulation. Mobile equipment – heavy equipment Specifically, the student will be able to: o operations pertaining to excavation or 1. Identify hazards associated with excavations and trenching activities or movement of other trenches, including the hazard that poses the greatest machinery or vehicles in the vicinity of the risk. site, not only contribute to cave-in 2. Identify the three main methods for protecting potential, but present struck-by, caught-in, employees from cave-ins. or caught-between hazards. 3. Identify three factors that pose a hazard to According to OSHA, two workers are killed every month in employees working in excavations, and at least one trench collapses. The crushing weight of soil can break way to eliminate or reduce each hazard. bones, impair circulation and breathing, and cause serious 4. Review the role of a competent person at an internal injuries. The following illustrations show a excavation or trenching site. multiple cave-in scenario.

What Are The Hazards Associated With Excavation and Trenching Activities? Excavations and trenching activities are some of the most dangerous construction operations. Most accidents tend to happen in trenches between 5-15 feet deep and there’s usually little or no warning before a cave-in occurs.

Hazards associated with excavations and trenches include:

• Cave-ins – the greatest risk; an open excavation or trench is an unnatural situation. The soil wants to flow back together and fill the void. • Other potential hazards Falls – a worker could get too close to the o edge and fall into the excavation or trench; or, a worker in the trench could lose footing and fall.

• Shield system – shielding systems may be permanent structures or they can be portable structures, such as trench boxes or trench shields, which are moved along the trench as work progresses. Trench boxes must extend 18 inches above grade or bank in all vertical-sided excavations of 20 feet or less depth to protect from ground collapsing into the box and onto the employee.

What Are The Main Methods Of Protecting Employees From Cave-ins? OSHA requires that all excavations or trenches five feet or deeper be protected against collapse. Employers must provide a properly designed protective system that is capable of withstanding all of the possible loads that could What Are Methods Of Protecting be imposed upon it. Workers should never enter an Employees From Other Hazards While unprotected trench! Working In Excavations? Although cave-ins pose the greatest risk when working in There are several types of protective systems with the excavations and trenches, other hazards pose a risk to most common types being: workers. Employers must use methods to protect workers • Support/shoring systems – hydraulic, mechanical, or from these hazards as well. wood structures, consisting of posts, beams, shores Other hazards associated with excavations or trenches and or planking, and hydraulic jacks, that make up a methods of eliminating or reducing these hazards include shoring system which provides support to the sides of the following: an excavation and prevent soil movement.

• Instability of adjacent structures – unstable structures next to a trench or excavation could collapse. These structures, including the side of a building, walls, edge of a road, utility poles, and sidewalks, are supported by the soil beneath them and may become unstable if the soil next to them is removed. A support system, such as shoring, bracing, • Sloping and benching – in a sloping system, the sides or underpinning, must be used to ensure the stability of the excavation are cut away at an angle to reduce of the structure. the chance of a cave-in. Benching is similar to sloping, • Underground structures – some underground but stair-steps the sides so that less of an angle is installations, such as pipe lines, water or wastewater required to satisfy the level of protection needed. lines, or other utility lines, may be in or near a trench or excavation. If struck by excavation equipment, these underground installations could release toxic fumes or present fire/explosion dangers. Before digging, contact the utility or owner and determine the exact location. The underground installations in open excavations must be supported, protected, or appropriately removed.

• Spoil pile – the soil removed from the trench poses area. A competent person should inspect excavations hazards if placed too close to the edge of an after rains. excavation by increasing the chances of cave-in. Spoil • Access/Egress – normal entry and exit of trenches or piles should be kept at least two feet from the edge excavations can present fall hazards if a safe means of of the excavation and placed so that rain water runs access/egress is not in place. If hazardous conditions away from it and not into it. in a trench develop, survival may depend on quick exit from the excavation/trench. OSHA recommends that stairways, ladders, ramps, or other safe means of egress be provided in all trenches that are four feet deep or more. Position means of egress within 25 lateral feet of workers. • Hard hats – when a danger of head injury from impact exists, employees working in those areas must be protected by protective helmets. Hard hats must be worn when workers are in trenches/excavations • Mobile equipment – equipment operated near an that are five feet or deeper or when the competent excavation or required to approach the edge of an person determines that there is a hazard at a lesser excavation is in danger of falling into the trench, depth. especially if the operator does not have a clear and direct view of the edge of the excavation. A warning What Is The Role Of The Competent system, such as barricades, hand or mechanical Person? signals, or stop logs must be used. If possible, the grade of the soil should be angled away from the The competent person is essential in excavation and excavation. trenching and must have specific training and knowledge in the following areas: • Falling loads -– this hazard involves items, such as tools, equipment, or construction materials, falling • Soil classification into the trench or excavation. Workers below could • Use of protective systems be struck by the falling item and be injured. Tools, • Requirements of OSHA’s standard on excavation and equipment, and construction materials should be trenching (29 CFR 1926 Subpart P) kept at least two feet from the edge or retaining devices should be used, or both. Provide employees The competent person must be capable of identifying with proper PPE to protect them from falling objects. existing and potential hazards and must have the authority Do not allow workers to stand or work below loads to immediately eliminate those hazards. being handled by lifting or digging equipment. • Hazardous atmospheres – oxygen deficiency and A competent person must make daily inspections of toxic fumes are hazardous environments that could excavations, areas around them, and protective system: potentially be encountered in the confined space of a trench or excavation. Test excavations that are more • Before work starts and as needed; than four feet deep before any employee entry is • After rainstorms, high winds, or other occurrences allowed. Employees shall not be permitted to work in which may increase hazards; and hazardous atmospheres unless proper respiratory • When it can be reasonably anticipated that an protection or ventilation is provided and regular employee will be exposed to hazards. testing of all controls used to reduce atmospheric contaminants to acceptable levels. If the competent person finds any evidence of a possible cave-in, failure of protective systems, hazardous • Water accumulation – hazards related to water atmospheres, or any other hazardous condition, he/she accumulation include a dangerous increase in cave-in must remove the exposed employees from the hazardous potential, a risk of drowning, and an increase in area and the employees may not return until all necessary difficulty of exiting the excavation or trench. Use precautions have been taken to protect them. water removal equipment to control or prevent water accumulation. Use diversion ditches, dikes or other means of diverting surface water from excavation or trench and providing adequate drainage of adjacent