CWEA COLLECTIONS SYSTEM MAINTENANCE
GRADE 3 Actual PRACTICE EXAM –
Comprehensive Review & Verified Guide
Category 1: Advanced System Inspection & Troubleshooting (12 Qs)
Q1: While reviewing CCTV footage of a 15-inch PVC main installed in 1985, you observe
a circumferential crack at the 2 o'clock position with visible soil infiltration during peak
flow periods. The pipe is located beneath a heavily trafficked arterial road with 8 feet of
cover. Based on PACP coding and rehabilitation priorities, what is the most appropriate
immediate action?
A) Code as BC (Broken/Cracked) severity 3 and schedule spot repair within 30 days
using open-cut excavation during off-peak traffic hours.
B) Code as BC severity 4, classify as an imminent structural failure, and recommend
immediate bypass pumping with emergency trenchless spot repair or sectional CIPP
within 48 hours.
C) Code as OJ (Offset Joint) severity 2 and continue routine inspection cycle as the PVC
pipe is resistant to structural deformation.
D) Code as BC severity 2 and defer repair until the next scheduled main rehabilitation as
infiltration is minimal and the road surface shows no distress.
Correct Answer: B
Rationale: Per NASSCO PACP standards, a circumferential crack with visible soil
infiltration represents an active soil loss condition (BC severity 4), indicating imminent
structural failure and potential sinkhole risk. Cal-OSHA and SWRCB guidelines prioritize
public safety threats over traffic inconvenience. Choice A underestimates the severity
(soil infiltration automatically elevates to severity 4). Choice C misidentifies the defect
(circumferential cracking differs from offset joints). Choice D ignores the soil infiltration
,component that signals active structural compromise beneath a high-traffic arterial
road.
Q2: Your CCTV operator reports chronic grease accumulation in a 12-inch vitrified clay
pipe segment serving a commercial district. The pipe exhibits 25% capacity loss with
hardened grease deposits at 2, 4, and 8 o'clock positions, but no structural defects.
Historical data shows three maintenance cleansings per year at this location. What is
the most cost-effective long-term solution?
A) Implement a targeted FOG source control program with grease interceptor
inspections and enforcement, combined with scheduled high-pressure jetting every 90
days.
B) Immediately line the pipe with CIPP to create a smooth surface that prevents grease
adhesion and reduces future maintenance.
C) Increase jetting frequency to monthly intervals and add biological additives to the
upstream manhole to digest existing deposits.
D) Recommend pipe replacement with HDPE to eliminate the rough clay surface that
promotes grease accumulation.
Correct Answer: A
Rationale: Grade 3 operators must address root causes rather than symptoms. Per
CWEA best practices and SSMP requirements, source control through FOG program
enforcement eliminates the problem at its origin. Choice B is technically
inappropriate—lining a pipe solely for grease management without structural need is
economically unjustified and may trap future grease against the liner. Choice C treats
symptoms without addressing upstream sources, creating perpetual reactive
maintenance. Choice D is excessively costly for a non-structural issue and does not
address the FOG generation source.
Q3: During a nighttime SSO response, you observe a 24-inch concrete trunk line
surcharging at a manhole with flow originating from an unmapped lateral connection.
The flow has a gray color, room-temperature thermal profile, and low BOD characteristic.
,Your preliminary assessment indicates clear water intrusion. What is the most likely
source?
A) Illegal industrial discharge from upstream manufacturing facility violating Waste
Discharge Requirements.
B) Groundwater infiltration through defective pipe joints exacerbated by recent seasonal
rainfall.
C) Tapped residential irrigation system or cross-connected potable water service line.
D) Upstream sanitary lift station pump failure causing backflow from the treatment
plant headworks.
Correct Answer: C
Rationale: The thermal profile (room temperature vs. groundwater's cooler
temperatures), gray coloration, and low BOD indicate treated or potable water, not raw
wastewater or groundwater. Cross-connections or illegal irrigation taps produce these
exact characteristics. Choice A would typically show elevated temperature, color
variation, and high BOD. Choice B would present cooler temperatures and clear water
but typically during/after rain events and without the "gray" tint of chlorinated water.
Choice D would involve raw wastewater with high BOD and characteristic sewage
odor/temperature.
Q4: A lift station's lead pump is running continuously but not lowering the wet well level
below the lead pump stop setpoint. The lag pump cycles on occasionally and
successfully draws down the level. Voltage readings show 460V at the starter, and the
pump amp draw is 15% below nameplate FLA (Full Load Amps). The most likely cause
is:
A) Worn pump impeller with reduced capacity due to rag accumulation or abrasive wear,
unable to meet system inflow at current demand.
B) Phase imbalance in the electrical supply causing the pump to run in reverse rotation.
C) Detached check valve allowing discharge to recirculate back into the wet well
through the inactive pump.
, D) Submergence depth insufficient for the specific pump model, causing vortexing and
air binding.
Correct Answer: A
Rationale: Normal voltage with below-FLA amperage indicates the pump is operating
but mechanically inefficient—classic symptoms of impeller wear, rag wrapping, or
clearance ring wear reducing hydraulic capacity. The lag pump's ability to draw down the
level confirms adequate system capacity and electrical infrastructure. Choice B would
typically show abnormal amp readings, not simply low, and would likely trip overloads.
Choice C would cause rapid cycling or continuous running without the lag pump's
success in drawing down levels. Choice D would present as splashing, noise, and erratic
flow, not steady continuous operation with reduced amps.
Q5: While assessing a 36-inch RCP interceptor for I/I reduction priority, you review five
years of flow monitoring data showing dry weather flow averaging 2.1 MGD and wet
weather peaks reaching 8.4 MGD during a 2-year storm event. Using the 3:1 peaking
factor rule for extraneous flow evaluation, what is your determination?
A) The system is within normal parameters as residential peaking factors typically
range 3:1 to 4:1 during storm events.
B) The system exhibits moderate I/I requiring further investigation through smoke
testing and dye flooding of suspected areas.
C) The system shows severe I/I with 4:1 peaking factor, indicating significant
rehabilitation priority for defective service laterals and mainline joints.
D) The data is inconclusive without simultaneous rainfall intensity measurements to
correlate flow peaks with specific precipitation events.
Correct Answer: C
Rationale: The calculated peaking factor is 4:1 (8.4 ÷ 2.1), which exceeds the industry
standard 3:1 threshold for excessive I/I in separate sanitary systems. Per EPA and State
Water Board guidelines, ratios above 3:1 indicate substantial extraneous flow requiring
capital rehabilitation. Choice A conflicts with standard I/I evaluation criteria. Choice B
GRADE 3 Actual PRACTICE EXAM –
Comprehensive Review & Verified Guide
Category 1: Advanced System Inspection & Troubleshooting (12 Qs)
Q1: While reviewing CCTV footage of a 15-inch PVC main installed in 1985, you observe
a circumferential crack at the 2 o'clock position with visible soil infiltration during peak
flow periods. The pipe is located beneath a heavily trafficked arterial road with 8 feet of
cover. Based on PACP coding and rehabilitation priorities, what is the most appropriate
immediate action?
A) Code as BC (Broken/Cracked) severity 3 and schedule spot repair within 30 days
using open-cut excavation during off-peak traffic hours.
B) Code as BC severity 4, classify as an imminent structural failure, and recommend
immediate bypass pumping with emergency trenchless spot repair or sectional CIPP
within 48 hours.
C) Code as OJ (Offset Joint) severity 2 and continue routine inspection cycle as the PVC
pipe is resistant to structural deformation.
D) Code as BC severity 2 and defer repair until the next scheduled main rehabilitation as
infiltration is minimal and the road surface shows no distress.
Correct Answer: B
Rationale: Per NASSCO PACP standards, a circumferential crack with visible soil
infiltration represents an active soil loss condition (BC severity 4), indicating imminent
structural failure and potential sinkhole risk. Cal-OSHA and SWRCB guidelines prioritize
public safety threats over traffic inconvenience. Choice A underestimates the severity
(soil infiltration automatically elevates to severity 4). Choice C misidentifies the defect
(circumferential cracking differs from offset joints). Choice D ignores the soil infiltration
,component that signals active structural compromise beneath a high-traffic arterial
road.
Q2: Your CCTV operator reports chronic grease accumulation in a 12-inch vitrified clay
pipe segment serving a commercial district. The pipe exhibits 25% capacity loss with
hardened grease deposits at 2, 4, and 8 o'clock positions, but no structural defects.
Historical data shows three maintenance cleansings per year at this location. What is
the most cost-effective long-term solution?
A) Implement a targeted FOG source control program with grease interceptor
inspections and enforcement, combined with scheduled high-pressure jetting every 90
days.
B) Immediately line the pipe with CIPP to create a smooth surface that prevents grease
adhesion and reduces future maintenance.
C) Increase jetting frequency to monthly intervals and add biological additives to the
upstream manhole to digest existing deposits.
D) Recommend pipe replacement with HDPE to eliminate the rough clay surface that
promotes grease accumulation.
Correct Answer: A
Rationale: Grade 3 operators must address root causes rather than symptoms. Per
CWEA best practices and SSMP requirements, source control through FOG program
enforcement eliminates the problem at its origin. Choice B is technically
inappropriate—lining a pipe solely for grease management without structural need is
economically unjustified and may trap future grease against the liner. Choice C treats
symptoms without addressing upstream sources, creating perpetual reactive
maintenance. Choice D is excessively costly for a non-structural issue and does not
address the FOG generation source.
Q3: During a nighttime SSO response, you observe a 24-inch concrete trunk line
surcharging at a manhole with flow originating from an unmapped lateral connection.
The flow has a gray color, room-temperature thermal profile, and low BOD characteristic.
,Your preliminary assessment indicates clear water intrusion. What is the most likely
source?
A) Illegal industrial discharge from upstream manufacturing facility violating Waste
Discharge Requirements.
B) Groundwater infiltration through defective pipe joints exacerbated by recent seasonal
rainfall.
C) Tapped residential irrigation system or cross-connected potable water service line.
D) Upstream sanitary lift station pump failure causing backflow from the treatment
plant headworks.
Correct Answer: C
Rationale: The thermal profile (room temperature vs. groundwater's cooler
temperatures), gray coloration, and low BOD indicate treated or potable water, not raw
wastewater or groundwater. Cross-connections or illegal irrigation taps produce these
exact characteristics. Choice A would typically show elevated temperature, color
variation, and high BOD. Choice B would present cooler temperatures and clear water
but typically during/after rain events and without the "gray" tint of chlorinated water.
Choice D would involve raw wastewater with high BOD and characteristic sewage
odor/temperature.
Q4: A lift station's lead pump is running continuously but not lowering the wet well level
below the lead pump stop setpoint. The lag pump cycles on occasionally and
successfully draws down the level. Voltage readings show 460V at the starter, and the
pump amp draw is 15% below nameplate FLA (Full Load Amps). The most likely cause
is:
A) Worn pump impeller with reduced capacity due to rag accumulation or abrasive wear,
unable to meet system inflow at current demand.
B) Phase imbalance in the electrical supply causing the pump to run in reverse rotation.
C) Detached check valve allowing discharge to recirculate back into the wet well
through the inactive pump.
, D) Submergence depth insufficient for the specific pump model, causing vortexing and
air binding.
Correct Answer: A
Rationale: Normal voltage with below-FLA amperage indicates the pump is operating
but mechanically inefficient—classic symptoms of impeller wear, rag wrapping, or
clearance ring wear reducing hydraulic capacity. The lag pump's ability to draw down the
level confirms adequate system capacity and electrical infrastructure. Choice B would
typically show abnormal amp readings, not simply low, and would likely trip overloads.
Choice C would cause rapid cycling or continuous running without the lag pump's
success in drawing down levels. Choice D would present as splashing, noise, and erratic
flow, not steady continuous operation with reduced amps.
Q5: While assessing a 36-inch RCP interceptor for I/I reduction priority, you review five
years of flow monitoring data showing dry weather flow averaging 2.1 MGD and wet
weather peaks reaching 8.4 MGD during a 2-year storm event. Using the 3:1 peaking
factor rule for extraneous flow evaluation, what is your determination?
A) The system is within normal parameters as residential peaking factors typically
range 3:1 to 4:1 during storm events.
B) The system exhibits moderate I/I requiring further investigation through smoke
testing and dye flooding of suspected areas.
C) The system shows severe I/I with 4:1 peaking factor, indicating significant
rehabilitation priority for defective service laterals and mainline joints.
D) The data is inconclusive without simultaneous rainfall intensity measurements to
correlate flow peaks with specific precipitation events.
Correct Answer: C
Rationale: The calculated peaking factor is 4:1 (8.4 ÷ 2.1), which exceeds the industry
standard 3:1 threshold for excessive I/I in separate sanitary systems. Per EPA and State
Water Board guidelines, ratios above 3:1 indicate substantial extraneous flow requiring
capital rehabilitation. Choice A conflicts with standard I/I evaluation criteria. Choice B
