Underground Construction Safety
41 flashcards covering Underground Construction Safety for the OSHA OSHA 10/30 Construction section.
Underground construction safety focuses on protecting workers from hazards in excavations, tunnels, and shafts, such as cave-ins, flooding, and toxic atmospheres. This topic is defined by OSHA regulations under 29 CFR 1926 Subpart S, which sets standards for construction activities to prevent accidents and ensure safe work practices in the OSHA 10 and 30 outreach programs.
On OSHA 10/30 practice exams, this topic typically appears as multiple-choice questions testing hazard identification, emergency procedures, and protective measures, with common traps like overlooking the need for specific engineering controls or misinterpreting soil classification for shoring.
A practical tip workers often miss: Always verify that rescue equipment is on site and workers are trained in its use before starting any underground work.
Terms (41)
- 01
What is a competent person in the context of excavations?
A person 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 (29 CFR 1926.32(f)).
- 02
How often must excavations be inspected by a competent person?
At least once each day that work is being performed in the excavation, and as needed throughout the shift (29 CFR 1926.651(k)(1)).
- 03
Under 29 CFR 1926.652, what protective systems are required for excavations?
Excavations 5 feet or deeper into which employees enter must be protected from cave-ins by an adequate protective system designed in accordance with tabulated data or other methods (29 CFR 1926.652(a)(1)).
- 04
What must be done before workers enter an excavation?
A competent person must inspect the excavation and the protective systems daily, before work begins and as needed (29 CFR 1926.651(k)(1)).
- 05
In underground construction, what is required when a hazardous atmosphere is detected?
Testing and controls must be implemented to ensure oxygen content between 19.5 and 23.5 percent, and other atmospheric hazards are addressed before entry (29 CFR 1926.651(g)).
- 06
What is the definition of an excavation in OSHA standards?
Any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal (29 CFR 1926.650(b)).
- 07
How deep must an excavation be to require a protective system?
Five feet or greater, unless the excavation is made entirely in stable rock (29 CFR 1926.652(a)(1)).
- 08
What precautions must be taken for utilities in excavations?
The location of underground utilities must be determined and marked before excavation begins, and precautions taken to avoid damage (29 CFR 1926.651(b)).
- 09
When must a ladder be provided in an excavation?
In excavations more than 4 feet deep, a means of egress such as a ladder, ramp, or stairway must be provided within 25 feet of lateral travel for employees (29 CFR 1926.651(c)(2)).
- 10
A worker encounters water accumulation in an excavation. What should they do?
Immediately stop work and notify the competent person to evaluate and control the situation to prevent cave-in hazards (29 CFR 1926.651(i)).
- 11
Under 29 CFR 1926.651, what is required for soil classification?
A competent person must classify soil using at least one visual and one manual analysis to determine appropriate protective measures (29 CFR 1926.651(c)).
- 12
What is the maximum allowable slope for excavations in Type C soil?
/2 horizontal to 1 vertical (34 degrees) (29 CFR 1926.652(b)(2)).
- 13
Before starting excavation work, what must employers provide?
Surface encumbrances that are located so as to create a hazard to employees must be removed or supported (29 CFR 1926.651(a)).
- 14
In a scenario where heavy equipment is near an excavation, what safety measure is needed?
Employees must be protected from being struck or from materials or equipment falling into the excavation (29 CFR 1926.651(j)).
- 15
What training is required for workers in excavations?
Training must be provided by a competent person on the recognition of hazards associated with excavations (29 CFR 1926.21(b)(2)).
- 16
How must spoil piles be managed in excavations?
Spoil, materials, and equipment must be kept at least 2 feet from the edge of the excavation (29 CFR 1926.651(j)(2)).
- 17
What is required when an excavation is subject to vibration?
Additional precautions must be taken to prevent vibration-induced cave-ins (29 CFR 1926.651(a)(2)).
- 18
Under 29 CFR 1926.653, what defines a hazardous atmosphere in excavations?
An atmosphere that may expose employees to the risk of death, injury, acute illness, or impairment of ability to escape self-rescue (29 CFR 1926.651(g)).
- 19
What procedure must be followed for confined spaces in underground construction?
If the space is permit-required, follow the entry permit requirements including atmospheric testing and monitoring (29 CFR 1910.146, applicable via 29 CFR 1926).
- 20
A competent person identifies unstable soil in an excavation. What action is next?
Implement appropriate protective systems or methods to prevent cave-ins immediately (29 CFR 1926.652).
- 21
What is the role of a protective system in excavations?
A method of protecting employees from cave-ins, such as sloping, benching, shoring, or shielding (29 CFR 1926.650(b)).
- 22
How often must atmospheric testing be conducted in excavations?
Before employees enter and as necessary during occupancy to ensure safe conditions (29 CFR 1926.651(g)(2)).
- 23
What must be done if an excavation face shows signs of cracking?
The competent person must evaluate and take corrective action, such as installing supports (29 CFR 1926.651(k)(2)).
- 24
In underground construction, when is shoring required?
For excavations where sloping is not feasible, shoring must be used as a protective system (29 CFR 1926.652(c)).
- 25
What emergency rescue equipment is needed for excavations?
A safety harness and lifeline must be worn by employees entering bell-bottom pier holes or other similar deep and confined excavations (29 CFR 1926.651(g)(4)).
- 26
Under 29 CFR 1926.21, what training topics cover excavation safety?
Instruction on the recognition and avoidance of unsafe conditions, including cave-in hazards and proper use of protective systems (29 CFR 1926.21(b)(2)).
- 27
What is the minimum width of a means of egress in excavations?
Not specified exactly, but must be designed to allow safe exit; ladders must be secured and extend 3 feet above the excavation edge (29 CFR 1926.1052).
- 28
A worker reports feeling dizzy in an excavation. What is the response?
Evacuate the worker immediately and test for hazardous atmospheres before re-entry (29 CFR 1926.651(g)).
- 29
What documentation is required for excavation protective systems?
Tabulated data supporting the design of protective systems must be maintained at the jobsite (29 CFR 1926.652(b)(4)).
- 30
How must excavations be protected from vehicles?
Barricades, handrails, or other effective barriers must be provided at all remote excavations to prevent accidental entry by vehicles (29 CFR 1926.651(a)(3)).
- 31
What is required for overhead loads near excavations?
No soil, rock, or other materials should be stored near the edge if it could cause a cave-in, and loads must be placed away from the excavation edge (29 CFR 1926.651(j)(1)).
- 32
In excavations, what defines stable rock?
Natural solid mineral matter not subject to weathering or degradation that will not fail under its own weight (29 CFR 1926.650(b)).
- 33
What procedure is followed for daily excavation inspections?
The competent person must look for evidence of a situation that could result in possible cave-ins, failures of protective systems, hazardous atmospheres, or other hazards (29 CFR 1926.651(k)(1)).
- 34
Under 29 CFR 1926.650, what hazards must be assessed before excavation?
Potential for cave-ins, water accumulation, atmospheric hazards, and access/egress issues must be evaluated (29 CFR 1926.650).
- 35
A trench shows signs of water seepage. What action is required?
Control the inflow of water and stabilize the excavation to prevent cave-ins (29 CFR 1926.651(i)).
- 36
What is the purpose of benching in excavations?
To prevent cave-ins by creating stepped levels in the excavation walls (29 CFR 1926.652(b)).
- 37
How must employees be protected from falling loads in excavations?
By keeping materials and equipment away from the excavation edge and using toeboards or guards if necessary (29 CFR 1926.651(j)).
- 38
What training must a competent person have for excavations?
Knowledge of soil analysis, use of protective systems, and requirements of the standard (29 CFR 1926.651(a)).
- 39
In underground construction, when is a permit required for confined spaces?
For spaces that have hazards such as hazardous atmospheres or engulfment potential (29 CFR 1910.146, referenced in construction contexts).
- 40
What is the maximum distance employees can travel to a means of egress in excavations?
feet in excavations 4 feet or more in depth (29 CFR 1926.651(c)(2)).
- 41
Under 29 CFR 1926.652, what options exist for protective systems?
Sloping, benching, shoring, and shielding, selected based on soil type and excavation depth (29 CFR 1926.652).