AWWA Technical Standards and Specifications 2 — Questions and Answers
Question 1: According to AWWA C651, what is the required chlorine residual for disinfection of a new water main after the holding period?
- At least 10 mg/L free chlorine (Correct answer)
- At least 25 mg/L free chlorine
- At least 5 mg/L free chlorine
- At least 50 mg/L free chlorine
Correct answer: At least 10 mg/L free chlorine
AWWA C651 requires a minimum free chlorine residual of 10 mg/L after the specified holding period to confirm adequate disinfection.
Question 2: AWWA Standard C900 covers which type of pipe material for water distribution systems?
- Ductile iron pipe
- PVC pressure pipe (Correct answer)
- Steel pipe
- HDPE pipe
Correct answer: PVC pressure pipe
AWWA C900 specifically covers PVC (polyvinyl chloride) pressure pipe for water distribution, typically in sizes 4 through 12 inches.
Question 3: What does the AWWA C110/A21.10 standard govern?
- Ductile-iron and gray-iron fittings for water service (Correct answer)
- Steel pipe flanges and fittings
- PVC fittings for potable water
- Copper tube fittings
Correct answer: Ductile-iron and gray-iron fittings for water service
AWWA C110/A21.10 establishes dimensions, pressure ratings, and material requirements for ductile-iron and gray-iron fittings used in water service.
Question 4: Under AWWA M11, what is the typical minimum cover depth for steel water transmission mains to protect against damage?
- 18 inches
- 24 inches
- 36 inches (Correct answer)
- 48 inches
Correct answer: 36 inches
AWWA M11 (Steel Pipe Manual) generally recommends a minimum cover of 36 inches for steel transmission mains to provide adequate protection.
Question 5: AWWA C207 provides specifications for which component commonly used in steel pipeline systems?
- Mechanical joint couplings
- Steel pipe flanges (Correct answer)
- Rubber gaskets
- Epoxy linings
Correct answer: Steel pipe flanges
AWWA C207 covers the dimensions, materials, and pressure ratings of steel pipe flanges used to connect sections of steel water pipelines.
Question 6: According to AWWA C104/A21.4, which lining is standard for ductile iron pipe in water service?
- Coal tar enamel
- Cement mortar (Correct answer)
- Fusion-bonded epoxy
- Polyethylene
Correct answer: Cement mortar
AWWA C104/A21.4 specifies cement-mortar lining as the standard internal protection for ductile iron pipe to prevent corrosion and tuberculation.
Question 7: What pressure rating class system does AWWA C900 use to classify PVC distribution pipe?
- Schedule numbers (40, 80, 120)
- Dimension Ratio (DR) designations (Correct answer)
- Wall thickness codes (WT1, WT2)
- Pressure classes (PC100, PC150, PC200)
Correct answer: Dimension Ratio (DR) designations
AWWA C900 uses Dimension Ratio (DR) designations, where the DR is the ratio of outside diameter to wall thickness, to classify PVC pipe pressure capacity.
AWWA Technical Standards and Specifications 2
According to AWWA C651, what is the required chlorine residual for disinfection of a new water main after the holding period?