Colorado WW Operator D Exam Actual
Exam QUESTIONS AND ANSWERS 2026 |
Complete Solution Guide A+ Graded | Pass
Guaranteed - A+ Graded
Section 1: Basic Mathematics and Calculations
Questions 1-15
Question 1 Convert 500 gallons to cubic feet. (1 cubic foot = 7.48 gallons)
A. 3,740 ft³
B. 66.8 ft³ [CORRECT]
C. 500 ft³
D. 0.015 ft³
Correct Answer: B
Rationale: To convert gallons to cubic feet, divide by 7.48 gallons/ft³. Calculation: 500 gallons ÷
7.48 gallons/ft³ = 66.844 ft³ ≈ 66.8 ft³
Why other options are incorrect:
• A (3,740): Multiplied 500 × 7.48 instead of dividing
• C (500): Assumed 1:1 conversion
• D (0.015): Divided 7.48 by 500 (inverted calculation)
Question 2 A rectangular tank is 30 feet long, 15 feet wide, and has a water depth of 10 feet.
What is the volume of water in gallons?
A. 4,500 gallons
B. 33,660 gallons [CORRECT]
C. 112,200 gallons
D. 4,500,000 gallons
Correct Answer: B
,Rationale: Step 1: Calculate volume in cubic feet Volume = Length × Width × Depth = 30 ft ×
15 ft × 10 ft = 4,500 ft³
Step 2: Convert to gallons 4,500 ft³ × 7.48 gallons/ft³ = 33,660 gallons
Why other options are incorrect:
• A (4,500): This is cubic feet, not gallons (forgot conversion)
• C (112,200): Used 30 × 15 × 10 × 7.48 but calculation error or used wrong multiplier
• D (4,500,000): Multiplied by 1,000 instead of 7.48
Question 3 A pump delivers 800 gallons per minute (gpm). How many million gallons per day
(MGD) does this represent?
A. 0.08 MGD
B. 0.8 MGD
C. 1.15 MGD [CORRECT]
D. 19.2 MGD
Correct Answer: C
Rationale: Step 1: Convert gpm to gallons per day 800 gpm × 60 minutes/hour × 24 hours/day =
1,152,000 gallons/day
Step 2: Convert to MGD 1,152,000 gallons/day ÷ 1,000,000 = 1.152 MGD ≈ 1.15 MGD
Shortcut formula: gpm × 1.44 = MGD 800 × 1.44 = 1.152 MGD
Why other options are incorrect:
• A (0.08): Divided by 10,000 incorrectly
• B (0.8): Forgot to multiply by 24 hours
• D (19.2): Multiplied by 24 but didn't divide by 1,000,000
Question 4 A treatment plant treats 3.0 MGD. The chlorine dosage is 2.0 mg/L. How many
pounds of chlorine are used per day? (Formula: lbs/day = mg/L × MGD × 8.34)
A. 5.0 lbs
B. 25.0 lbs
C. 50.0 lbs [CORRECT]
D. 500.0 lbs
,Correct Answer: C
Rationale: Using the formula: lbs/day = mg/L × MGD × 8.34 lbs/day = 2.0 mg/L × 3.0 MGD ×
8.34 lbs/day = 6.0 × 8.34 = 50.04 lbs/day ≈ 50.0 lbs
Why other options are incorrect:
• A (5.0): Used 0.3 MGD instead of 3.0 MGD
• B (25.0): Used 1.0 MGD or forgot 8.34 factor (2 × 3 × 4.17)
• D (500.0): Multiplied by 10 (used 30 MGD or 20 mg/L)
Question 5 The detention time in a clarifier is 3 hours. If the flow rate is 2.0 MGD, what is the
volume of the clarifier in gallons?
A. 250,000 gallons [CORRECT]
B. 500,000 gallons
C. 750,000 gallons
D. 1,000,000 gallons
Correct Answer: A
Rationale: Formula: Detention Time = Volume ÷ Flow Rate Rearranged: Volume = Flow Rate ×
Detention Time
Step 1: Convert detention time to days 3 hours ÷ 24 hours/day = 0.125 days
Step 2: Calculate volume Volume = 2.0 MGD × 0.125 days = 0.25 million gallons = 250,000
gallons
Why other options are incorrect:
• B (500,000): Used 6 hours detention time
• C (750,000): Used 9 hours detention time
• D (1,000,000): Used 12 hours detention time or 4 MGD flow
Question 6 A circular tank has a diameter of 40 feet and a water depth of 12 feet. What is the
volume in gallons?
A. 15,040 gallons
B. 112,499 gallons [CORRECT]
C. 451,200 gallons
D. 1,128,000 gallons
, Correct Answer: B
Rationale: Step 1: Calculate area of circle Area = π × r² = 3.1416 × (20 ft)² = 3.1416 × 400 =
1,256.64 ft²
Step 2: Calculate volume in cubic feet Volume = Area × Depth = 1,256.64 ft² × 12 ft = 15,079.68
ft³
Step 3: Convert to gallons 15,079.68 ft³ × 7.48 gallons/ft³ = 112,796 gallons ≈ 112,499 gallons
(Using π = 3.14: 3.14 × 400 × 12 × 7.48 = 112,499 gallons)
Why other options are incorrect:
• A (15,040): This is cubic feet (forgot × 7.48)
• C (451,200): Used diameter instead of radius (40² instead of 20²)
• D (1,128,000): Used 40² × 12 × 7.48 × 10 (decimal error)
Question 7 A pipeline is 2,000 feet long and has a diameter of 12 inches. If the flow velocity is 3
feet per second, what is the flow rate in gpm?
A. 105 gpm
B. 211 gpm
C. 1,057 gpm [CORRECT]
D. 2,640 gpm
Correct Answer: C
Rationale: Step 1: Convert diameter to feet and find radius 12 inches = 1 foot, radius = 0.5 ft
Step 2: Calculate cross-sectional area Area = π × r² = 3.1416 × (0.5)² = 0.7854 ft²
Step 3: Calculate flow rate in cfs (cubic feet per second) Q = Area × Velocity = 0.7854 ft² × 3 ft/s
= 2.356 ft³/s
Step 4: Convert to gpm 2.356 ft³/s × 7.48 gallons/ft³ × 60 seconds/minute = 1,057 gpm
Why other options are incorrect:
• A (105): Divided by 10 (unit conversion error)
• B (211): Used 6-inch diameter (radius = 0.25 ft)
• D (2,640): Used 24-inch diameter or velocity of 7.5 ft/s
Exam QUESTIONS AND ANSWERS 2026 |
Complete Solution Guide A+ Graded | Pass
Guaranteed - A+ Graded
Section 1: Basic Mathematics and Calculations
Questions 1-15
Question 1 Convert 500 gallons to cubic feet. (1 cubic foot = 7.48 gallons)
A. 3,740 ft³
B. 66.8 ft³ [CORRECT]
C. 500 ft³
D. 0.015 ft³
Correct Answer: B
Rationale: To convert gallons to cubic feet, divide by 7.48 gallons/ft³. Calculation: 500 gallons ÷
7.48 gallons/ft³ = 66.844 ft³ ≈ 66.8 ft³
Why other options are incorrect:
• A (3,740): Multiplied 500 × 7.48 instead of dividing
• C (500): Assumed 1:1 conversion
• D (0.015): Divided 7.48 by 500 (inverted calculation)
Question 2 A rectangular tank is 30 feet long, 15 feet wide, and has a water depth of 10 feet.
What is the volume of water in gallons?
A. 4,500 gallons
B. 33,660 gallons [CORRECT]
C. 112,200 gallons
D. 4,500,000 gallons
Correct Answer: B
,Rationale: Step 1: Calculate volume in cubic feet Volume = Length × Width × Depth = 30 ft ×
15 ft × 10 ft = 4,500 ft³
Step 2: Convert to gallons 4,500 ft³ × 7.48 gallons/ft³ = 33,660 gallons
Why other options are incorrect:
• A (4,500): This is cubic feet, not gallons (forgot conversion)
• C (112,200): Used 30 × 15 × 10 × 7.48 but calculation error or used wrong multiplier
• D (4,500,000): Multiplied by 1,000 instead of 7.48
Question 3 A pump delivers 800 gallons per minute (gpm). How many million gallons per day
(MGD) does this represent?
A. 0.08 MGD
B. 0.8 MGD
C. 1.15 MGD [CORRECT]
D. 19.2 MGD
Correct Answer: C
Rationale: Step 1: Convert gpm to gallons per day 800 gpm × 60 minutes/hour × 24 hours/day =
1,152,000 gallons/day
Step 2: Convert to MGD 1,152,000 gallons/day ÷ 1,000,000 = 1.152 MGD ≈ 1.15 MGD
Shortcut formula: gpm × 1.44 = MGD 800 × 1.44 = 1.152 MGD
Why other options are incorrect:
• A (0.08): Divided by 10,000 incorrectly
• B (0.8): Forgot to multiply by 24 hours
• D (19.2): Multiplied by 24 but didn't divide by 1,000,000
Question 4 A treatment plant treats 3.0 MGD. The chlorine dosage is 2.0 mg/L. How many
pounds of chlorine are used per day? (Formula: lbs/day = mg/L × MGD × 8.34)
A. 5.0 lbs
B. 25.0 lbs
C. 50.0 lbs [CORRECT]
D. 500.0 lbs
,Correct Answer: C
Rationale: Using the formula: lbs/day = mg/L × MGD × 8.34 lbs/day = 2.0 mg/L × 3.0 MGD ×
8.34 lbs/day = 6.0 × 8.34 = 50.04 lbs/day ≈ 50.0 lbs
Why other options are incorrect:
• A (5.0): Used 0.3 MGD instead of 3.0 MGD
• B (25.0): Used 1.0 MGD or forgot 8.34 factor (2 × 3 × 4.17)
• D (500.0): Multiplied by 10 (used 30 MGD or 20 mg/L)
Question 5 The detention time in a clarifier is 3 hours. If the flow rate is 2.0 MGD, what is the
volume of the clarifier in gallons?
A. 250,000 gallons [CORRECT]
B. 500,000 gallons
C. 750,000 gallons
D. 1,000,000 gallons
Correct Answer: A
Rationale: Formula: Detention Time = Volume ÷ Flow Rate Rearranged: Volume = Flow Rate ×
Detention Time
Step 1: Convert detention time to days 3 hours ÷ 24 hours/day = 0.125 days
Step 2: Calculate volume Volume = 2.0 MGD × 0.125 days = 0.25 million gallons = 250,000
gallons
Why other options are incorrect:
• B (500,000): Used 6 hours detention time
• C (750,000): Used 9 hours detention time
• D (1,000,000): Used 12 hours detention time or 4 MGD flow
Question 6 A circular tank has a diameter of 40 feet and a water depth of 12 feet. What is the
volume in gallons?
A. 15,040 gallons
B. 112,499 gallons [CORRECT]
C. 451,200 gallons
D. 1,128,000 gallons
, Correct Answer: B
Rationale: Step 1: Calculate area of circle Area = π × r² = 3.1416 × (20 ft)² = 3.1416 × 400 =
1,256.64 ft²
Step 2: Calculate volume in cubic feet Volume = Area × Depth = 1,256.64 ft² × 12 ft = 15,079.68
ft³
Step 3: Convert to gallons 15,079.68 ft³ × 7.48 gallons/ft³ = 112,796 gallons ≈ 112,499 gallons
(Using π = 3.14: 3.14 × 400 × 12 × 7.48 = 112,499 gallons)
Why other options are incorrect:
• A (15,040): This is cubic feet (forgot × 7.48)
• C (451,200): Used diameter instead of radius (40² instead of 20²)
• D (1,128,000): Used 40² × 12 × 7.48 × 10 (decimal error)
Question 7 A pipeline is 2,000 feet long and has a diameter of 12 inches. If the flow velocity is 3
feet per second, what is the flow rate in gpm?
A. 105 gpm
B. 211 gpm
C. 1,057 gpm [CORRECT]
D. 2,640 gpm
Correct Answer: C
Rationale: Step 1: Convert diameter to feet and find radius 12 inches = 1 foot, radius = 0.5 ft
Step 2: Calculate cross-sectional area Area = π × r² = 3.1416 × (0.5)² = 0.7854 ft²
Step 3: Calculate flow rate in cfs (cubic feet per second) Q = Area × Velocity = 0.7854 ft² × 3 ft/s
= 2.356 ft³/s
Step 4: Convert to gpm 2.356 ft³/s × 7.48 gallons/ft³ × 60 seconds/minute = 1,057 gpm
Why other options are incorrect:
• A (105): Divided by 10 (unit conversion error)
• B (211): Used 6-inch diameter (radius = 0.25 ft)
• D (2,640): Used 24-inch diameter or velocity of 7.5 ft/s
