Denver Class D-5 Excavating, Caisson
Drilling and Drain Layer Contractor
Examination Practice Exam 2026 | 100
Questions & Answers with Detailed
Rationales | Complete Exam Prep Study
Guide | Denver Contractor License Test
Prep
1. Before beginning any excavation, what is the first priority?
A. Order concrete
B. Install reinforcement
C. Locate and identify underground utilities
D. Backfill the trench
Answer: C. Locate and identify underground utilities
Rationale: Identifying underground utilities prevents damage to utility
infrastructure, reduces injury risks, and complies with excavation safety
regulations.
, 2. OSHA generally requires a protective system for trenches at what depth?
A. 3 feet
B. 5 feet or greater unless entirely in stable rock
C. 10 feet
D. 15 feet
Answer: B. 5 feet or greater unless entirely in stable rock
Rationale: OSHA requires protective systems for trenches 5 feet or deeper unless
excavated entirely in stable rock or determined safe by a competent person.
3. Which soil type is considered the most stable?
A. Type C
B. Type B
C. Type A
D. Organic soil
Answer: C. Type A
Rationale: Type A soil has the greatest compressive strength and provides the
highest natural stability under OSHA soil classifications.
4. What is the primary purpose of trench shoring?
A. Increase drainage
B. Prevent trench wall collapse
C. Speed excavation
D. Improve compaction
Answer: B. Prevent trench wall collapse
Rationale: Shoring supports trench walls and protects workers from cave-ins.
, 5. Which equipment is commonly used for deep foundation caisson drilling?
A. Bulldozer
B. Rotary drilling rig
C. Asphalt paver
D. Roller compactor
Answer: B. Rotary drilling rig
Rationale: Rotary drilling rigs are specifically designed to drill deep shafts for
caisson foundations.
6. What is the minimum safe distance excavated material should generally be
kept from the edge of a trench?
A. 6 inches
B. 1 foot
C. 2 feet
D. 5 feet
Answer: C. 2 feet
Rationale: Keeping spoil piles at least 2 feet from the trench edge reduces
surcharge loading and minimizes cave-in hazards.
7. A competent person is responsible for:
A. Pouring concrete
B. Driving trucks
C. Inspecting excavations for hazards
D. Operating every machine
Answer: C. Inspecting excavations for hazards
, Rationale: OSHA requires a competent person to inspect excavations daily and
after hazard-increasing events.
8. Which machine is commonly used to compact soil in trenches?
A. Crane
B. Plate compactor
C. Backhoe loader
D. Drill rig
Answer: B. Plate compactor
Rationale: Plate compactors provide effective compaction for trench backfill and
confined areas.
9. The main purpose of drainage around foundations is to:
A. Increase soil expansion
B. Direct water away from structures
C. Raise groundwater levels
D. Reduce concrete strength
Answer: B. Direct water away from structures
Rationale: Proper drainage prevents water intrusion and protects foundation
integrity.
10.Which pipe material is commonly used for foundation drains?
A. Copper tubing
B. Perforated PVC pipe
C. Black steel pipe
D. Galvanized conduit
Drilling and Drain Layer Contractor
Examination Practice Exam 2026 | 100
Questions & Answers with Detailed
Rationales | Complete Exam Prep Study
Guide | Denver Contractor License Test
Prep
1. Before beginning any excavation, what is the first priority?
A. Order concrete
B. Install reinforcement
C. Locate and identify underground utilities
D. Backfill the trench
Answer: C. Locate and identify underground utilities
Rationale: Identifying underground utilities prevents damage to utility
infrastructure, reduces injury risks, and complies with excavation safety
regulations.
, 2. OSHA generally requires a protective system for trenches at what depth?
A. 3 feet
B. 5 feet or greater unless entirely in stable rock
C. 10 feet
D. 15 feet
Answer: B. 5 feet or greater unless entirely in stable rock
Rationale: OSHA requires protective systems for trenches 5 feet or deeper unless
excavated entirely in stable rock or determined safe by a competent person.
3. Which soil type is considered the most stable?
A. Type C
B. Type B
C. Type A
D. Organic soil
Answer: C. Type A
Rationale: Type A soil has the greatest compressive strength and provides the
highest natural stability under OSHA soil classifications.
4. What is the primary purpose of trench shoring?
A. Increase drainage
B. Prevent trench wall collapse
C. Speed excavation
D. Improve compaction
Answer: B. Prevent trench wall collapse
Rationale: Shoring supports trench walls and protects workers from cave-ins.
, 5. Which equipment is commonly used for deep foundation caisson drilling?
A. Bulldozer
B. Rotary drilling rig
C. Asphalt paver
D. Roller compactor
Answer: B. Rotary drilling rig
Rationale: Rotary drilling rigs are specifically designed to drill deep shafts for
caisson foundations.
6. What is the minimum safe distance excavated material should generally be
kept from the edge of a trench?
A. 6 inches
B. 1 foot
C. 2 feet
D. 5 feet
Answer: C. 2 feet
Rationale: Keeping spoil piles at least 2 feet from the trench edge reduces
surcharge loading and minimizes cave-in hazards.
7. A competent person is responsible for:
A. Pouring concrete
B. Driving trucks
C. Inspecting excavations for hazards
D. Operating every machine
Answer: C. Inspecting excavations for hazards
, Rationale: OSHA requires a competent person to inspect excavations daily and
after hazard-increasing events.
8. Which machine is commonly used to compact soil in trenches?
A. Crane
B. Plate compactor
C. Backhoe loader
D. Drill rig
Answer: B. Plate compactor
Rationale: Plate compactors provide effective compaction for trench backfill and
confined areas.
9. The main purpose of drainage around foundations is to:
A. Increase soil expansion
B. Direct water away from structures
C. Raise groundwater levels
D. Reduce concrete strength
Answer: B. Direct water away from structures
Rationale: Proper drainage prevents water intrusion and protects foundation
integrity.
10.Which pipe material is commonly used for foundation drains?
A. Copper tubing
B. Perforated PVC pipe
C. Black steel pipe
D. Galvanized conduit
