Download Wastewater Collection Systems Exam Q&A: Maintenance and Safety and more Exams Water and Wastewater Engineering in PDF only on Docsity!
CWEA Collections Grade 2 Exam 202 5/2026 |
Questions and Verified Answers| 100%
Correct| Grade A
Q: What four conditions are necessary to create an explosion?
Answer: Combustible gas, adequate oxygen, sufficient heat, and proper mixing of gas and oxygen.
Q: What does "transition area" mean in traffic control?
Answer: Moves traffic out of its normal path
Q: The term "transition area" is one component of a:
Answer: Traffic Control Zone
Q: What elements should be considered to improve worker safety in High Speed Temporary
Traffic Control Zones? Answer: Rerouting traffic around the work site, positioning of law enforcement officers in the temporary traffic control zone, and work zone training.
Q: What key factors would you need to address when developing an S.O.P. for Lift Station
failure?
Answer: Traffic control plan, by-pass connections, and spill containment.
Q: "Spring Blades" are a type of tool used with:
Answer: Power Rodder
Q: Porcupine, Root Saw, and a Square Bar Cork Screw are all tools used for:
Answer: Sewer rodding
Q: What tool would you use to cut VCP pipe?
Answer: Chain pipe cutter
Q: Which conditions should a gas detection device test for?
Answer: Hydrogen Sulfide, explosive/flammable gases, oxygen.
Q: What does "LEL" mean on a gas detection meter?
Answer: Lower explosive limit
Q: Category 1 SSO's that discharge to a drainage channel and/or surface water must be reported
within: Answer: 2 hours
Q: To report in the Statewide SSO Data-base California Integrated Water Quality System
(CIWQS), regarding the location of a Category 2 SSO, you must know: Answer: the GPS coordinates
Q: Biological activity in long, sluggish-flow, flat grade sewer lines will likely cause odors, true
or false? Answer: True
Q: Flatter sewer line grades may cause added sewer maintenance expense and odor nuisance.
The problem is most likely caused by: Answer: A decrease in velocity allowing organic and inorganic solids to settle out
Q: Infiltration from a high water table can be one source of excessive clear water in a collection
system, true or false? Answer: True
Q: What is the first thing to consider when selecting a solution to clear a stoppage in a sewer?
Answer: Cause of stoppage
Q: The interior of 300 feet of 12 - inch pipe is uniformly coated with one inch of grease. How
many gallons will this pipe hold when filled with water? Answer: 12 inches (diameter of pipe) - 2 inches (grease on pipe) = 10 inches Convert inches to feet: 10 inches x (1 foot / 12 inches) = 0.833 feet Volume of a right regular cylinder: V = 0.785 x Diameter x Diameter x Length of Pipe V = 0.785 x 0.833 ft x 0.833 ft x 300 ft V = 163.41 cubic feet Convert to Gallons: 163.41 cu ft x (7.48 gal / 1 cu ft) = 1223.31 gal
Q: Infiltration can be caused by cracked pipes, true or false?
Answer: True
Q: The main reason for adding sodium hypochlorite to sewers is to control:
Answer: Odor
Q: Roots can enter collection systems through pipe cracks, true or false?
2 feet per second
Q: Vitrified Clay pipe is a Rigid type of pipe, true or false?
Answer: True
Q: Barrels, lids, cones, and backflow devices are all included in Manholes, true or false?
Answer: False. All are included except for backflow devices.
Q: Sewer testing methods include air, water, mandrill, and sewage, true or false?
Answer: False. Sewer testing methods do not include sewage.
Q: Using high velocity cleaners is one method included in hydraulic sewer cleaning, true or
false? Answer: True
Q: A flow of 650 gpm would be how many MGD?
Answer: 650 gpm x (1440 min / 1 day) = 936000 gpd 936000 x (1 MG / 1000000 gal) = 0.936 MGD
Q: One of the advantages of using CCTV is that the length and severity of defective pipe areas
can be recorded, true or false? Answer: True
Q: Offset joints are one hazard that may damage a TV camera going through a sewer, true or
false? Answer: True
Q: What is the total volume of 1000 feet of 8 inch line?
Answer: Convert inches to feet: 8 inches x (1 foot / 12 inches) = 0. Volume of a right regular cylinder: V = 0.785 x Diameter x Diameter x Length of Pipe V = 0.785 x 0.666 ft x 0.666 ft x 1000 ft V = 348.19 cu ft Convert to gallons: 348.19 cu ft x (7.48 gal / 1 cu ft) = 2604.47 gal
Q: If an 8 inch force main has a metered flow rate of 400000 gpd, what is the velocity?
Answer: Velocity = Flow / Area Area = 0.785 x Diameter x Diameter When finding Area, convert Diameter into feet 8 in x (1 ft / 12 in) = 0.667 ft Area = 0.785 x 0.667 ft x 0.667 ft = 0.349 sq ft Convert flow in gallons to cubic feet per second:
Answer: So you know where obstructions or difficulties are encountered
Q: Emergency stoppages in pipelines may be cleared safely by use of high velocity cleaners,
true or false? Answer: True
Q: Rodents and insects can be controlled by spraying manholes with an approved pesticide, true
or false? Answer: True
Q: How many types of common shoring are there?
Answer: 6
Q: If it takes 7 minutes and 30 seconds for dye to travel a distance of 860 feet through an 8 inch
sewer, what is the velocity in feet per second? Answer: Velocity = Distance / Time Convert minutes to seconds: 7 min (60 sec / 1 min) = 420 sec Velocity = 860 ft / (420 sec + 30 sec) Velocity = 860 ft / 450 sec Velocity = 1.91 fps
Q: An upright circular cylinder tank (flat bottom) has a diameter of 12 feet. When filled to a
depth of 8 feet, what is the volume? Answer: Volume = 0.785 x Diameter x Diameter x Height Volume = 0.785 x 12 ft x 12 ft x 8 ft Volume = 904.32 cu ft
Q: Once enrolled in CIWQS, the "Collection System Questionnaire" must be updated at least
every: Answer: 12 months
Q: You received a sewer spill call at 1100 hours, arrived on site at 1115, and your crew relieved
the stoppage at 1127. You estimate the spill was running at 6 gallons per minute. How much sewer went un-captured? Answer: Duration x Flow Rate = Spill Volume 27 min x 6 gpm = 162 gallons
Q: Lift station failure can include electrical circuit failures, true or false?
Answer: True
Q: A clogged impeller can cause a pump to deliver less than its expected rate of discharge, true
or false? Answer: True
Q: How long is an Inquiry Identification Number for an Underground Service Alert (USA)
viable for? Answer: 28 days
Q: A person who completes a training program in accordance with the requirements of Title 8,
Calif. Code of Regulations, Minimum Guidelines of the Common Ground Alliance is considered a Qualified Person, true or false? Answer: True
Q: Temporary traffic control lanes created as part of a Temporary Traffic Control Zone setup
on a street with a 35 MPH maximum speed limit shall be a minimum width of: Answer: 10 feet
Q: For a night time Short Term Stationary Temporary Traffic Control Zone setup on low
speed/low volume street, the minimum height of the traffic cones used shall be: Answer: 28 inches
Q: After completing a Temporary Traffic Control setup for your work zone it is a good practice
to: Answer: Observe how effective your TTC setup is working to control traffic and make the necessary changes to it if necessary
Q: When a citizen wants information regarding a maintenance operation you should give them
as much factual information as you can, and offer to help them further, true or false? Answer: True
Q: Before starting a maintenance operation in a basement located in the backyard of a residence
you should contact the resident and politely as permission to enter the backyard, true or false? Answer: True
Q: Maintenance programs are based on preventative and corrective maintenance principles, true
or false? Answer: True
Q: The goal of preventative maintenance is to avoid breakdowns, severe damage, or harmful
depreciation, true or false? Answer: True
Q: Why are gasoline and volatile solvents objectionable when present in a sewer?
Answer: They produce an explosion hazard
Answer: Hydrogen Sulfide (H2S)
Q: The lack of an unpleasant odor in a structure does not always mean that dangerous gases are
not present because: Answer: Some dangerous gases have no odor
