CO Water & Sewer Line Contractor
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant
Download Pdf.
1. Which type of pipe is commonly used for underground water-
service and distribution lines because of its corrosion resistance,
flexibility, and resistance to many soil conditions?
A. Unprotected carbon steel
B. Ductile iron
C. Uncoated structural steel
D. Cast aluminum
Rationale: Ductile iron pipe is widely used for water distribution because
it provides high strength, durability, and good resistance to external
loading while accommodating many underground service conditions.
2. What is the primary purpose of a water-main pressure test after
installation?
A. Determine the trench width
B. Measure pipe color uniformity
C. Verify the integrity of the installed piping and joints under
, specified pressure
D. Determine the excavation volume
Rationale: A pressure test is intended to identify leaks, defective joints,
damaged pipe, or other deficiencies before the water main is placed into
service.
3. Before excavating for a new sewer or water line in Colorado, what
should the contractor do first regarding existing underground
utilities?
A. Begin excavation at the property line
B. Assume utilities are installed at standard depths
C. Request utility locating and marking through the appropriate
notification system
D. Remove the pavement immediately
Rationale: Existing underground utilities must be located and marked
before excavation so that workers can plan the work safely and prevent
utility strikes.
4. Which organization administers the Colorado 811 utility-locating
notification system?
A. Colorado Department of Labor
B. Colorado Division of Fire Prevention and Control
C. Utility Notification Center of Colorado
D. Colorado Department of Revenue
,Rationale: Colorado's utility notification system coordinates requests for
locating and marking underground utility facilities before excavation
begins.
5. What is the principal purpose of a trench box or trench shield?
A. Increase pipe pressure
B. Prevent water from entering the pipe
C. Protect workers from cave-ins by providing a protected work
area
D. Improve sewer flow capacity
Rationale: A trench shield is designed to protect workers within an
excavation by limiting exposure to collapsing soil rather than preventing
the trench itself from collapsing.
6. Under OSHA excavation requirements, when employees are
exposed to cave-in hazards, the contractor generally must provide
an appropriate protective system unless a recognized exception
applies. Which is an example of such a system?
A. Paint coating
B. Pipe insulation
C. Sloping, benching, shoring, or shielding
D. Concrete curing
Rationale: OSHA permits several protective approaches, including
properly designed sloping, benching, shoring, and shielding systems,
depending on site conditions and excavation characteristics.
, 7. Why should excavated spoil piles generally be kept back from the
edge of a trench?
A. To increase pipe diameter
B. To reduce pipe pressure
C. To reduce the possibility of material falling into the excavation
and adding surcharge loads to the trench wall
D. To increase groundwater flow
Rationale: Spoil placed too close to a trench edge can fall onto workers
and increase the loading imposed on the excavation walls, potentially
contributing to a cave-in.
8. What is the primary function of a water-main valve?
A. Increase pipe wall thickness
B. Control or isolate sections of the distribution system
C. Remove all sediment automatically
D. Measure trench depth
Rationale: Valves allow operators to isolate portions of a water system
for maintenance, repairs, emergencies, or operational control without
shutting down the entire network.
9. What is the purpose of a corporation stop or service connection
fitting on a water main?
A. Connect a sewer manhole to a storm drain
B. Provide a controlled connection from the water main to a
service line
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant
Download Pdf.
1. Which type of pipe is commonly used for underground water-
service and distribution lines because of its corrosion resistance,
flexibility, and resistance to many soil conditions?
A. Unprotected carbon steel
B. Ductile iron
C. Uncoated structural steel
D. Cast aluminum
Rationale: Ductile iron pipe is widely used for water distribution because
it provides high strength, durability, and good resistance to external
loading while accommodating many underground service conditions.
2. What is the primary purpose of a water-main pressure test after
installation?
A. Determine the trench width
B. Measure pipe color uniformity
C. Verify the integrity of the installed piping and joints under
, specified pressure
D. Determine the excavation volume
Rationale: A pressure test is intended to identify leaks, defective joints,
damaged pipe, or other deficiencies before the water main is placed into
service.
3. Before excavating for a new sewer or water line in Colorado, what
should the contractor do first regarding existing underground
utilities?
A. Begin excavation at the property line
B. Assume utilities are installed at standard depths
C. Request utility locating and marking through the appropriate
notification system
D. Remove the pavement immediately
Rationale: Existing underground utilities must be located and marked
before excavation so that workers can plan the work safely and prevent
utility strikes.
4. Which organization administers the Colorado 811 utility-locating
notification system?
A. Colorado Department of Labor
B. Colorado Division of Fire Prevention and Control
C. Utility Notification Center of Colorado
D. Colorado Department of Revenue
,Rationale: Colorado's utility notification system coordinates requests for
locating and marking underground utility facilities before excavation
begins.
5. What is the principal purpose of a trench box or trench shield?
A. Increase pipe pressure
B. Prevent water from entering the pipe
C. Protect workers from cave-ins by providing a protected work
area
D. Improve sewer flow capacity
Rationale: A trench shield is designed to protect workers within an
excavation by limiting exposure to collapsing soil rather than preventing
the trench itself from collapsing.
6. Under OSHA excavation requirements, when employees are
exposed to cave-in hazards, the contractor generally must provide
an appropriate protective system unless a recognized exception
applies. Which is an example of such a system?
A. Paint coating
B. Pipe insulation
C. Sloping, benching, shoring, or shielding
D. Concrete curing
Rationale: OSHA permits several protective approaches, including
properly designed sloping, benching, shoring, and shielding systems,
depending on site conditions and excavation characteristics.
, 7. Why should excavated spoil piles generally be kept back from the
edge of a trench?
A. To increase pipe diameter
B. To reduce pipe pressure
C. To reduce the possibility of material falling into the excavation
and adding surcharge loads to the trench wall
D. To increase groundwater flow
Rationale: Spoil placed too close to a trench edge can fall onto workers
and increase the loading imposed on the excavation walls, potentially
contributing to a cave-in.
8. What is the primary function of a water-main valve?
A. Increase pipe wall thickness
B. Control or isolate sections of the distribution system
C. Remove all sediment automatically
D. Measure trench depth
Rationale: Valves allow operators to isolate portions of a water system
for maintenance, repairs, emergencies, or operational control without
shutting down the entire network.
9. What is the purpose of a corporation stop or service connection
fitting on a water main?
A. Connect a sewer manhole to a storm drain
B. Provide a controlled connection from the water main to a
service line
