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CWEA CSM Grade 2 Practice Test – Comprehensive Collection Systems Maintenance Exam
Review
Study Guide Note: This practice test covers the essential knowledge, skills, and abilities
required for the CWEA Collection System Maintenance Grade II certification. The exam is
computer-based and tests comprehension, application, and analysis of collection system
operations, maintenance, safety, and regulatory compliance . Each question includes the
correct answer and a detailed rationale.
Section 1: Collection System Operations & Maintenance (Questions 1–20)
1. What is the primary purpose of a wastewater collection system?
A. To treat wastewater before discharge
B. To convey wastewater from its source to a treatment plant
C. To store wastewater during heavy rainfall
D. To filter solids from wastewater
Answer: B. The collection system (sewers, manholes, lift stations) conveys wastewater from
homes, businesses, and industries to a treatment plant. Treatment occurs at the plant, not in
the collection system .
2. Which of the following is the most common cause of sanitary sewer overflows (SSOs)?
A. Treatment plant power failure
B. Grease and debris blockages
C. Excessive rainfall only
D. Chemical spills
Answer: B. Grease buildup, roots, rags, and debris are the most common causes of
blockages leading to SSOs. While rainfall can cause infiltration and inflow issues, blockages
are the primary cause .
3. According to a typical preventive maintenance program, gravity sewer lines in high-FOG
commercial areas should be cleaned at a minimum frequency of:
A. Every 5 years
B. Annually
C. Every 6 months
D. Only when blockages occur
Answer: C. High-FOG commercial areas require cleaning every 6 months to prevent grease
accumulation and blockages. Residential areas are typically cleaned every 2–5 years
depending on system age and condition .
4. Sand and grit accumulation in a sewer line is BEST removed using which cleaning
method?
,2
A. High-velocity water jetting with a penetrating nozzle
B. Power rodding with a root cutter attachment
C. Bucket machine or power bucket
D. Chemical flushing with surfactants
Answer: C. Bucket machines are specifically designed for removing heavy debris such as
sand, grit, and stones from large-diameter sewers. Jetting moves sand but may not fully
remove dense deposits .
5. Which type of sewer cleaning method is most appropriate for removing heavy grease
and roots from a small-diameter line?
A. High-velocity jetting with a root cutter nozzle
B. Balling with a rubber expandable ball
C. Bucket machine cleaning
D. Manual rodding with a straight rod
Answer: A. Jetting with a root cutter nozzle uses high-pressure water and cutting capability
to remove both grease and roots, making it the most versatile method for small lines with
combined debris .
6. A collection system technician notices sewage backing up into a residential basement
during dry weather. Which condition most directly explains this occurrence?
A. Infiltration from groundwater entering through cracked pipes
B. Inflow from roof drains connected to the sanitary sewer
C. A blockage or restriction downstream in the sewer main
D. Excessive velocity causing pipe erosion
Answer: C. Dry-weather backups indicate a flow restriction rather than rain-dependent
inflow or infiltration. A downstream blockage causes sewage to surcharge and seek the
lowest available relief point .
7. What is the minimum recommended self-cleansing velocity in a gravity sewer line?
A. 1.0 foot per second
B. 2.0 feet per second
C. 3.5 feet per second
D. 5.0 feet per second
Answer: B. A minimum velocity of 2.0 feet per second (fps) is recommended to keep solids
suspended and prevent settling. Velocities below 2 fps allow solids to settle, leading to
blockages .
8. The lowest point on the inside of a pipeline is called the:
, 3
A. Crown
B. Invert
C. Springline
D. Bench
Answer: B. The invert is the lowest point on the inside of a pipeline. The crown is the highest
point .
9. What affects the flow capacity of a sewer line?
A. Pipe size only
B. Pipe material only
C. Pipe size, pipe material, and grade
D. Grade only
Answer: C. Flow capacity is affected by pipe size, pipe material (roughness coefficient), and
grade (slope) .
10. Drawings which are considered "As Built" would be:
A. Original design drawings
B. Corrected construction drawings showing changes made in the field installation
C. Preliminary sketches
D. Future expansion plans
Answer: B. "As Built" drawings are corrected construction drawings that document changes
made during field installation .
11. What is the primary purpose of a drop manhole in a steep sewer alignment?
A. To increase flow velocity at the connection point
B. To dissipate energy and prevent erosion at the outlet
C. To provide additional storage volume during peak flows
D. To allow flow direction changes without turbulence
Answer: B. Drop manholes reduce the velocity of flow entering the downstream sewer by
allowing sewage to fall vertically, preventing scour and damage to the pipe invert .
12. A CCTV inspection reveals a pipe segment with a sagging invert and visible standing
water. What is the most likely cause?
A. Root intrusion at a joint
B. Differential settlement of the pipe bedding
C. Chemical attack from hydrogen sulfide
D. Grease accumulation along the crown
Answer: B. A sagging invert with standing water indicates the pipe has lost proper grade due
to settling of the bedding or foundation, creating a low point that traps flow .
CWEA CSM Grade 2 Practice Test – Comprehensive Collection Systems Maintenance Exam
Review
Study Guide Note: This practice test covers the essential knowledge, skills, and abilities
required for the CWEA Collection System Maintenance Grade II certification. The exam is
computer-based and tests comprehension, application, and analysis of collection system
operations, maintenance, safety, and regulatory compliance . Each question includes the
correct answer and a detailed rationale.
Section 1: Collection System Operations & Maintenance (Questions 1–20)
1. What is the primary purpose of a wastewater collection system?
A. To treat wastewater before discharge
B. To convey wastewater from its source to a treatment plant
C. To store wastewater during heavy rainfall
D. To filter solids from wastewater
Answer: B. The collection system (sewers, manholes, lift stations) conveys wastewater from
homes, businesses, and industries to a treatment plant. Treatment occurs at the plant, not in
the collection system .
2. Which of the following is the most common cause of sanitary sewer overflows (SSOs)?
A. Treatment plant power failure
B. Grease and debris blockages
C. Excessive rainfall only
D. Chemical spills
Answer: B. Grease buildup, roots, rags, and debris are the most common causes of
blockages leading to SSOs. While rainfall can cause infiltration and inflow issues, blockages
are the primary cause .
3. According to a typical preventive maintenance program, gravity sewer lines in high-FOG
commercial areas should be cleaned at a minimum frequency of:
A. Every 5 years
B. Annually
C. Every 6 months
D. Only when blockages occur
Answer: C. High-FOG commercial areas require cleaning every 6 months to prevent grease
accumulation and blockages. Residential areas are typically cleaned every 2–5 years
depending on system age and condition .
4. Sand and grit accumulation in a sewer line is BEST removed using which cleaning
method?
,2
A. High-velocity water jetting with a penetrating nozzle
B. Power rodding with a root cutter attachment
C. Bucket machine or power bucket
D. Chemical flushing with surfactants
Answer: C. Bucket machines are specifically designed for removing heavy debris such as
sand, grit, and stones from large-diameter sewers. Jetting moves sand but may not fully
remove dense deposits .
5. Which type of sewer cleaning method is most appropriate for removing heavy grease
and roots from a small-diameter line?
A. High-velocity jetting with a root cutter nozzle
B. Balling with a rubber expandable ball
C. Bucket machine cleaning
D. Manual rodding with a straight rod
Answer: A. Jetting with a root cutter nozzle uses high-pressure water and cutting capability
to remove both grease and roots, making it the most versatile method for small lines with
combined debris .
6. A collection system technician notices sewage backing up into a residential basement
during dry weather. Which condition most directly explains this occurrence?
A. Infiltration from groundwater entering through cracked pipes
B. Inflow from roof drains connected to the sanitary sewer
C. A blockage or restriction downstream in the sewer main
D. Excessive velocity causing pipe erosion
Answer: C. Dry-weather backups indicate a flow restriction rather than rain-dependent
inflow or infiltration. A downstream blockage causes sewage to surcharge and seek the
lowest available relief point .
7. What is the minimum recommended self-cleansing velocity in a gravity sewer line?
A. 1.0 foot per second
B. 2.0 feet per second
C. 3.5 feet per second
D. 5.0 feet per second
Answer: B. A minimum velocity of 2.0 feet per second (fps) is recommended to keep solids
suspended and prevent settling. Velocities below 2 fps allow solids to settle, leading to
blockages .
8. The lowest point on the inside of a pipeline is called the:
, 3
A. Crown
B. Invert
C. Springline
D. Bench
Answer: B. The invert is the lowest point on the inside of a pipeline. The crown is the highest
point .
9. What affects the flow capacity of a sewer line?
A. Pipe size only
B. Pipe material only
C. Pipe size, pipe material, and grade
D. Grade only
Answer: C. Flow capacity is affected by pipe size, pipe material (roughness coefficient), and
grade (slope) .
10. Drawings which are considered "As Built" would be:
A. Original design drawings
B. Corrected construction drawings showing changes made in the field installation
C. Preliminary sketches
D. Future expansion plans
Answer: B. "As Built" drawings are corrected construction drawings that document changes
made during field installation .
11. What is the primary purpose of a drop manhole in a steep sewer alignment?
A. To increase flow velocity at the connection point
B. To dissipate energy and prevent erosion at the outlet
C. To provide additional storage volume during peak flows
D. To allow flow direction changes without turbulence
Answer: B. Drop manholes reduce the velocity of flow entering the downstream sewer by
allowing sewage to fall vertically, preventing scour and damage to the pipe invert .
12. A CCTV inspection reveals a pipe segment with a sagging invert and visible standing
water. What is the most likely cause?
A. Root intrusion at a joint
B. Differential settlement of the pipe bedding
C. Chemical attack from hydrogen sulfide
D. Grease accumulation along the crown
Answer: B. A sagging invert with standing water indicates the pipe has lost proper grade due
to settling of the bedding or foundation, creating a low point that traps flow .
