Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
A primary clarifier should remove how much BOD and TSS? - CORRECT
ANSWERS 30% to 40% BOD
50% to 70 % TSS
What is a wastewater outfall line? - CORRECT ANSWERS Main line that
carries the wastewater to the treatment plant.
What are the minimum slopes for pipe sizes six, eight, ten, and 12 inches?
What are these slopes designed to achieve? - CORRECT ANSWERS 6 inch -
0.50 ft slope per 100 ft
8 inch - 0.33 ft slope per 100 ft
10 inch - 0.25 ft slope per 100 ft
12 inch - 0.20 ft slope per 100 ft
You have 3900 feet of 10-inch pipe on a grade of 0.25. What is the elevation
difference from one end to the other? - CORRECT ANSWERS 3900/100 =
39 sections of pipe 39 ( 39 x 0.25 = 9.75 ft = 9 ft 9 inc
Describe proper design of force main wastewater lines - CORRECT
ANSWERS Minimum 2 fps velocity with the smallest pump operating alone.
Minimum 4 inch diameter pipe
150 psi rating.
What is Standard Dimension Ratio? - CORRECT ANSWERS Ratio of outside
pipe diameter (OD) to wall thickness (PVC)
Describe proper design of gravity wastewater lines. - CORRECT ANSWERS
Designed to flow half full under normal conditions at a minimum of 2 fps
maximum of 10 fps.
,Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
A 12-inch line is on a 0.20 foot/100 foot grade. Point A is at an elevation of
127.6 feet. Point B is 600 feet downstream of point A and point C is 500 feet
downstream of point B. What is the elevation of points B and C? - CORRECT
ANSWERS A = 127.6
600
600 x (.2 ft / 100 ft) = 1.2 ft
B = 127.6 - 1.2 = 126.4 ft
500 x (.2ft/100ft) = 1 ft
C = 126.4-1= 125.4
List two methods of establishing grades when laying wastewater lines? -
CORRECT ANSWERS a. string and rod
b. batter boards
c. lasers
A 20-inch pipe is flowing at 4000 GPM. What is the velocity in the pipe? -
CORRECT ANSWERS CFS = (pipe area (sq^2)) x (Velocity (fps))
4000 gpm / 449 gpm/cfs = 8.91 cfs
R = (20/12)/2 = 0.833
sq ft = 3.14 (0.833)^2 = 2.18 ft^2
8.91 = 2.18 ft x V =
V = 8.91/2.18
V(FPS) = 4.09
Define infiltration and inflow. Give some examples of each. - CORRECT
ANSWERS Infiltration is water entering wastewater lines around joints, bad
taps, or other small holes in the pipe caused by roots, etc. Infiltration
usually occurs from ground water. Inflow is the direct flow of storm water
into the system from direct connections of roof drains, etc., bad manholes,
,Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
large openings in pipe such as old concrete pipe, or direct connections to
storm water lines.
What are some common methods for detecting leaks in a wastewater
collection system? - CORRECT ANSWERS a. infiltration/exfiltration testing
b. low pressure air
c. smoke testing
d. television
e. dye testing
Manholes should have a minimum opening of _________ and be at least
_________ wide. The invert depth should be at least ________ the diameter of
the pipe. - CORRECT ANSWERS 24 inches
4 ft
1/2
What is the normal DO range in the aeration basin of an activated sludge
plant? - CORRECT ANSWERS 2.0 to 4.0 mg/L absolute minimum of 1.0
mg/L
Which activated sludge process can operate the aeration basin below 2.0
mg/L D.O.? Explain why. - CORRECT ANSWERS Extended aeration or
racetracks. This process keeps the bugs starving and holds them for a
longer time. (Endogenous growth phase)
List several methods of wastewater flow measurements - CORRECT
ANSWERS a. V notch or rectangular weirs
b. Parshall flumes
c. Ultrasonic
d. Venturi
, Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
e. Magmeter
What size pipe is needed to carry 6.5 MGD at a velocity of 2.0 FPS flowing
half full? - CORRECT ANSWERS CFS = (pipe area (sq^2)) x (Velocity (fps))
CFS = pi * (r^2) * fps
6.5 mgd x 694.4 gpm/mgd = 4514 gpm
4514 gpm / 449 gpm/cfs = 10.5 cfs x 2 fps = 21 cfs
21 CFS = pi x r^2 x 2 FPS
r ^2 = 21 CFS / (pi x 2 FPS)
r^2 = 21/ ( 3.14 x 2) =21 / (6.28) = 3.34 sq ft
(r^2)^(1/2) = (3.34 ft ^2)^ 1/2 = 1.83 ft
r = 1.83 ft
convert to inches
1.83 ft x 12 in/ft = 21.96 in
diameter = r * 2
d = 21.96 * 2 = 43.92
44 inch pipe is needed
The Venturi meter works on what principle? - CORRECT ANSWERS The
Venturi meter works on Bertinelli's Principle. If you increase velocity there
will be a decrease in pressure.
Hydrogen sulfide results from what? - CORRECT ANSWERS Anaerobic
decomposition of sulfur compounds
What are Bacilli? - CORRECT ANSWERS Rod shaped bacteria
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
A primary clarifier should remove how much BOD and TSS? - CORRECT
ANSWERS 30% to 40% BOD
50% to 70 % TSS
What is a wastewater outfall line? - CORRECT ANSWERS Main line that
carries the wastewater to the treatment plant.
What are the minimum slopes for pipe sizes six, eight, ten, and 12 inches?
What are these slopes designed to achieve? - CORRECT ANSWERS 6 inch -
0.50 ft slope per 100 ft
8 inch - 0.33 ft slope per 100 ft
10 inch - 0.25 ft slope per 100 ft
12 inch - 0.20 ft slope per 100 ft
You have 3900 feet of 10-inch pipe on a grade of 0.25. What is the elevation
difference from one end to the other? - CORRECT ANSWERS 3900/100 =
39 sections of pipe 39 ( 39 x 0.25 = 9.75 ft = 9 ft 9 inc
Describe proper design of force main wastewater lines - CORRECT
ANSWERS Minimum 2 fps velocity with the smallest pump operating alone.
Minimum 4 inch diameter pipe
150 psi rating.
What is Standard Dimension Ratio? - CORRECT ANSWERS Ratio of outside
pipe diameter (OD) to wall thickness (PVC)
Describe proper design of gravity wastewater lines. - CORRECT ANSWERS
Designed to flow half full under normal conditions at a minimum of 2 fps
maximum of 10 fps.
,Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
A 12-inch line is on a 0.20 foot/100 foot grade. Point A is at an elevation of
127.6 feet. Point B is 600 feet downstream of point A and point C is 500 feet
downstream of point B. What is the elevation of points B and C? - CORRECT
ANSWERS A = 127.6
600
600 x (.2 ft / 100 ft) = 1.2 ft
B = 127.6 - 1.2 = 126.4 ft
500 x (.2ft/100ft) = 1 ft
C = 126.4-1= 125.4
List two methods of establishing grades when laying wastewater lines? -
CORRECT ANSWERS a. string and rod
b. batter boards
c. lasers
A 20-inch pipe is flowing at 4000 GPM. What is the velocity in the pipe? -
CORRECT ANSWERS CFS = (pipe area (sq^2)) x (Velocity (fps))
4000 gpm / 449 gpm/cfs = 8.91 cfs
R = (20/12)/2 = 0.833
sq ft = 3.14 (0.833)^2 = 2.18 ft^2
8.91 = 2.18 ft x V =
V = 8.91/2.18
V(FPS) = 4.09
Define infiltration and inflow. Give some examples of each. - CORRECT
ANSWERS Infiltration is water entering wastewater lines around joints, bad
taps, or other small holes in the pipe caused by roots, etc. Infiltration
usually occurs from ground water. Inflow is the direct flow of storm water
into the system from direct connections of roof drains, etc., bad manholes,
,Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
large openings in pipe such as old concrete pipe, or direct connections to
storm water lines.
What are some common methods for detecting leaks in a wastewater
collection system? - CORRECT ANSWERS a. infiltration/exfiltration testing
b. low pressure air
c. smoke testing
d. television
e. dye testing
Manholes should have a minimum opening of _________ and be at least
_________ wide. The invert depth should be at least ________ the diameter of
the pipe. - CORRECT ANSWERS 24 inches
4 ft
1/2
What is the normal DO range in the aeration basin of an activated sludge
plant? - CORRECT ANSWERS 2.0 to 4.0 mg/L absolute minimum of 1.0
mg/L
Which activated sludge process can operate the aeration basin below 2.0
mg/L D.O.? Explain why. - CORRECT ANSWERS Extended aeration or
racetracks. This process keeps the bugs starving and holds them for a
longer time. (Endogenous growth phase)
List several methods of wastewater flow measurements - CORRECT
ANSWERS a. V notch or rectangular weirs
b. Parshall flumes
c. Ultrasonic
d. Venturi
, Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
e. Magmeter
What size pipe is needed to carry 6.5 MGD at a velocity of 2.0 FPS flowing
half full? - CORRECT ANSWERS CFS = (pipe area (sq^2)) x (Velocity (fps))
CFS = pi * (r^2) * fps
6.5 mgd x 694.4 gpm/mgd = 4514 gpm
4514 gpm / 449 gpm/cfs = 10.5 cfs x 2 fps = 21 cfs
21 CFS = pi x r^2 x 2 FPS
r ^2 = 21 CFS / (pi x 2 FPS)
r^2 = 21/ ( 3.14 x 2) =21 / (6.28) = 3.34 sq ft
(r^2)^(1/2) = (3.34 ft ^2)^ 1/2 = 1.83 ft
r = 1.83 ft
convert to inches
1.83 ft x 12 in/ft = 21.96 in
diameter = r * 2
d = 21.96 * 2 = 43.92
44 inch pipe is needed
The Venturi meter works on what principle? - CORRECT ANSWERS The
Venturi meter works on Bertinelli's Principle. If you increase velocity there
will be a decrease in pressure.
Hydrogen sulfide results from what? - CORRECT ANSWERS Anaerobic
decomposition of sulfur compounds
What are Bacilli? - CORRECT ANSWERS Rod shaped bacteria
