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.
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
,Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
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, 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
, Tceq Wastewater Exam A Questions And Answers
2024/2025 All Answers 100% Correct Detailed Best Exam
Solution Graded A+ For Success
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
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
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