Idaho Excavation Contractor
Qualification Advanced 100-Question
Practice Exam 2026 | Questions &
Answers with Detailed Rationales |
Complete Exam Prep & Study Guide
1. Before beginning excavation work on a site in Idaho where underground
utilities may exist, what is the contractor's most important initial utility-
safety action?
A. Begin potholing with the excavator
B. Contact the applicable one-call utility locating service and allow required notice
time
C. Ask the equipment operator to identify utility markers
D. Obtain permission from the property owner only
Answer: Contact the applicable one-call utility locating service and allow
required notice time
Rationale: Underground utilities must be located before excavation begins.
Idaho project specifications commonly require advance one-call notification, and
contractors must also account for utilities that may not participate in the one-
call system.
, 2. Under OSHA excavation rules, who is responsible for identifying existing
and predictable hazards and having authority to take prompt corrective
measures?
A. Project owner
B. Equipment operator
C. Competent person
D. Surveyor
Answer: Competent person
Rationale: OSHA defines a competent person as someone capable of identifying
existing and predictable hazards and authorized to take prompt corrective
action.
3. Which condition generally triggers the need for a protective system for
employees working in an excavation?
A. Any excavation deeper than 2 feet
B. Any excavation deeper than 3 feet
C. An excavation 5 feet or deeper unless an applicable exception applies
D. Only excavations deeper than 10 feet
Answer: An excavation 5 feet or deeper unless an applicable exception applies
Rationale: OSHA generally requires employees in excavations to be protected
from cave-ins at depths of 5 feet or more, unless the excavation is entirely in
stable rock or another regulatory exception applies.
4. A trench is 8 feet deep and contains Type C soil. Which approach is
generally associated with the maximum allowable slope under OSHA's
simple sloping option?
A. ¼H:1V
B. ½H:1V
C. 1H:1V
D. 1½H:1V
,Answer: 1½H:1V
Rationale: Under OSHA's allowable configuration for Type C soil, the maximum
allowable slope is generally 1½ horizontal to 1 vertical, or approximately 34
degrees from horizontal.
5. What is the principal purpose of a trench shield?
A. Prevent groundwater infiltration
B. Support adjacent buildings permanently
C. Protect workers from cave-in hazards within the shielded area
D. Increase excavation production
Answer: Protect workers from cave-in hazards within the shielded area
Rationale: A trench shield, or trench box, is a protective system designed
primarily to protect employees from cave-ins rather than to provide structural
support to the surrounding soil.
6. Excavated spoil piles should generally be kept at least how far from the
edge of an excavation unless an equivalent protective method is used?
A. 6 inches
B. 1 foot
C. 2 feet
D. 5 feet
Answer: 2 feet
Rationale: OSHA generally requires excavated material and equipment to be
kept at least 2 feet from the edge or otherwise restrained from falling or rolling
into the excavation.
7. After heavy rainfall, what should occur before employees re-enter a
potentially affected excavation?
A. The operator should visually inspect it from the cab
B. The competent person should conduct an inspection
, C. The surveyor should establish a new benchmark
D. The owner should approve re-entry
Answer: The competent person should conduct an inspection
Rationale: Rain can increase soil instability, water accumulation, erosion, and
other hazards. OSHA requires inspection after rainstorms or other hazard-
increasing occurrences when employee exposure can reasonably be anticipated.
8. Which soil characteristic generally provides the strongest indication that
soil may be unstable?
A. Uniform color
B. Presence of fissures, layered materials, or seepage
C. High density alone
D. Low excavation production
Answer: Presence of fissures, layered materials, or seepage
Rationale: Fissures, seepage, previously disturbed soil, layering, and other
conditions can substantially reduce stability and must be considered during soil
classification and protective-system selection.
9. Which soil is generally considered the most stable under OSHA soil
classification?
A. Type C
B. Type B
C. Type A
D. Unclassified soil
Answer: Type A
Rationale: Type A soil has the highest allowable cohesive strength classification
among the three primary OSHA soil categories, although it can be downgraded
because of conditions such as fissuring or vibration.
Qualification Advanced 100-Question
Practice Exam 2026 | Questions &
Answers with Detailed Rationales |
Complete Exam Prep & Study Guide
1. Before beginning excavation work on a site in Idaho where underground
utilities may exist, what is the contractor's most important initial utility-
safety action?
A. Begin potholing with the excavator
B. Contact the applicable one-call utility locating service and allow required notice
time
C. Ask the equipment operator to identify utility markers
D. Obtain permission from the property owner only
Answer: Contact the applicable one-call utility locating service and allow
required notice time
Rationale: Underground utilities must be located before excavation begins.
Idaho project specifications commonly require advance one-call notification, and
contractors must also account for utilities that may not participate in the one-
call system.
, 2. Under OSHA excavation rules, who is responsible for identifying existing
and predictable hazards and having authority to take prompt corrective
measures?
A. Project owner
B. Equipment operator
C. Competent person
D. Surveyor
Answer: Competent person
Rationale: OSHA defines a competent person as someone capable of identifying
existing and predictable hazards and authorized to take prompt corrective
action.
3. Which condition generally triggers the need for a protective system for
employees working in an excavation?
A. Any excavation deeper than 2 feet
B. Any excavation deeper than 3 feet
C. An excavation 5 feet or deeper unless an applicable exception applies
D. Only excavations deeper than 10 feet
Answer: An excavation 5 feet or deeper unless an applicable exception applies
Rationale: OSHA generally requires employees in excavations to be protected
from cave-ins at depths of 5 feet or more, unless the excavation is entirely in
stable rock or another regulatory exception applies.
4. A trench is 8 feet deep and contains Type C soil. Which approach is
generally associated with the maximum allowable slope under OSHA's
simple sloping option?
A. ¼H:1V
B. ½H:1V
C. 1H:1V
D. 1½H:1V
,Answer: 1½H:1V
Rationale: Under OSHA's allowable configuration for Type C soil, the maximum
allowable slope is generally 1½ horizontal to 1 vertical, or approximately 34
degrees from horizontal.
5. What is the principal purpose of a trench shield?
A. Prevent groundwater infiltration
B. Support adjacent buildings permanently
C. Protect workers from cave-in hazards within the shielded area
D. Increase excavation production
Answer: Protect workers from cave-in hazards within the shielded area
Rationale: A trench shield, or trench box, is a protective system designed
primarily to protect employees from cave-ins rather than to provide structural
support to the surrounding soil.
6. Excavated spoil piles should generally be kept at least how far from the
edge of an excavation unless an equivalent protective method is used?
A. 6 inches
B. 1 foot
C. 2 feet
D. 5 feet
Answer: 2 feet
Rationale: OSHA generally requires excavated material and equipment to be
kept at least 2 feet from the edge or otherwise restrained from falling or rolling
into the excavation.
7. After heavy rainfall, what should occur before employees re-enter a
potentially affected excavation?
A. The operator should visually inspect it from the cab
B. The competent person should conduct an inspection
, C. The surveyor should establish a new benchmark
D. The owner should approve re-entry
Answer: The competent person should conduct an inspection
Rationale: Rain can increase soil instability, water accumulation, erosion, and
other hazards. OSHA requires inspection after rainstorms or other hazard-
increasing occurrences when employee exposure can reasonably be anticipated.
8. Which soil characteristic generally provides the strongest indication that
soil may be unstable?
A. Uniform color
B. Presence of fissures, layered materials, or seepage
C. High density alone
D. Low excavation production
Answer: Presence of fissures, layered materials, or seepage
Rationale: Fissures, seepage, previously disturbed soil, layering, and other
conditions can substantially reduce stability and must be considered during soil
classification and protective-system selection.
9. Which soil is generally considered the most stable under OSHA soil
classification?
A. Type C
B. Type B
C. Type A
D. Unclassified soil
Answer: Type A
Rationale: Type A soil has the highest allowable cohesive strength classification
among the three primary OSHA soil categories, although it can be downgraded
because of conditions such as fissuring or vibration.
