TEXAS WASTEWATER CLASS A NEWEST ACTUAL EXAM
QESTIONS AND CORRECT DETAILED ANSWERS
What is TCEQ doing to control "point source" pollution of the Texas waterways? -
ANSWER: *Permitting of domestic wastewater plants
*Permitting of industrial wastewater plants
Describe proper design of force main wastewater lines. - ANSWER: Minimum two fps
velocity with the smallest pump operating alone. Minimum four inch diameter pipe
with 150 psi rating.
What is Standard Dimension Ratio? - ANSWER: Ratio of outside pipe diameter (OD)
to wall thickness (PVC)
Describe proper design of gravity wastewater lines. - ANSWER: Designed to flow half
full ,under normal conditions, at a minimum of two fps and a maximum of ten fps.
Manholes should have a minimum opening of? - ANSWER: 24 inches and be at least
4 feet wide.
pH meters should be calibrated how often? What standards should be used for
calibration purposes? - ANSWER: Daily with at least two buffers.
What is the standard chlorine residual and minimum contact time on Texas
wastewater permits? - ANSWER: a. 1.0 mg/L for a minimum 20 minutes detention
time at peak flow b. No chlorine residual needed if detention time is greater than 21
days
As the complexity of an organization increases, what management function becomes
most important? - ANSWER: Planning
What is the effective chlorine disinfecting agent? - ANSWER: Hypochlorous Acid
(HOCl)
Does pH affect the chlorination process? Explain your answer. - ANSWER: When
using free chlorine the disinfectant is HOCl acid. As such it is much more effective at
pH's below 7.0. Above 7.0 pH the acid begins to be neutralized.
What is the effluent chlorine residual in Texas that is standard on permits and the
minimum detention time? What is the maximum residual allowed? - ANSWER: Texas
standard is 1.0 mg/L for a minimum 20 minutes detention time at peak flow.
Maximum residual allowed is 4.0 mg/L.
A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet deep. The
weir is 2 feet inside the outer clarifier wall. The flow is 1.0 MGD. The weir and
, outflow channel is 3 feet deep. a. What is the detention time in hours? - ANSWER:
Formula
What activated process cannot nitrify in a single stage? - ANSWER: Contact
Stabilization
What is the GPM output of a piston pump with an 8-inch diameter piston with a 10-
inch stroke operating at 50 strokes per minute? - ANSWER: Formula
Anaerobic digester gas should contain? - ANSWER: 65-75% methane, 25-35% carbon
dioxide and 1-5% nitrogen.
An activated sludge plant has an average daily flow of 3.5 MG. The aeration tank
capacity is 1.2 MG with a MLSS concentration of 3200 mg/L. The clarifier has a
capacity of 400,000 gallons with a MLSS concentration of 6,000 mg/L. The wasting
rate is 40,000 gallons per day with a MLSS concentration of 8, 000 mg/L. The effluent
TSS is 18 mg/L. Assuming volatile concentrations of 70%, what is the MCRT and what
type of activated sludge plant should this be? - ANSWER: Formulas MCRT
What are some of the causes of filaments in the aeration basin? - ANSWER: a. low
DO
b. low organic loading
c. septic wastes
d. nutrient deficiencies .
e. high sulfur content
Good sludge quality will have a predominance of what organisms in the MLSS? -
ANSWER: Ciliated protozoa
When an RBC is operating correctly, how will the slime appear on the media? -
ANSWER: Grey to brown 0.05 to 0.1 inches thick
According to design criteria, what are the minimum allowable diameters for a
manhole? - ANSWER: 24 inch opening and 48 inch inside diameter
What activated sludge process does not achieve complete nitrification? - ANSWER:
Contact Stabilization
In the selection of forced main wastewater piping, what is the minimum working
pressure? - ANSWER: 150 psi
The oxygen depletion of BOD dilution water should not exceed - ANSWER: 0.2 mg/L.
What is the minimum air gap when making water and wastewater connections? -
ANSWER: Minimum of one inch or twice the inlet pipe size whichever is greater.
QESTIONS AND CORRECT DETAILED ANSWERS
What is TCEQ doing to control "point source" pollution of the Texas waterways? -
ANSWER: *Permitting of domestic wastewater plants
*Permitting of industrial wastewater plants
Describe proper design of force main wastewater lines. - ANSWER: Minimum two fps
velocity with the smallest pump operating alone. Minimum four inch diameter pipe
with 150 psi rating.
What is Standard Dimension Ratio? - ANSWER: Ratio of outside pipe diameter (OD)
to wall thickness (PVC)
Describe proper design of gravity wastewater lines. - ANSWER: Designed to flow half
full ,under normal conditions, at a minimum of two fps and a maximum of ten fps.
Manholes should have a minimum opening of? - ANSWER: 24 inches and be at least
4 feet wide.
pH meters should be calibrated how often? What standards should be used for
calibration purposes? - ANSWER: Daily with at least two buffers.
What is the standard chlorine residual and minimum contact time on Texas
wastewater permits? - ANSWER: a. 1.0 mg/L for a minimum 20 minutes detention
time at peak flow b. No chlorine residual needed if detention time is greater than 21
days
As the complexity of an organization increases, what management function becomes
most important? - ANSWER: Planning
What is the effective chlorine disinfecting agent? - ANSWER: Hypochlorous Acid
(HOCl)
Does pH affect the chlorination process? Explain your answer. - ANSWER: When
using free chlorine the disinfectant is HOCl acid. As such it is much more effective at
pH's below 7.0. Above 7.0 pH the acid begins to be neutralized.
What is the effluent chlorine residual in Texas that is standard on permits and the
minimum detention time? What is the maximum residual allowed? - ANSWER: Texas
standard is 1.0 mg/L for a minimum 20 minutes detention time at peak flow.
Maximum residual allowed is 4.0 mg/L.
A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet deep. The
weir is 2 feet inside the outer clarifier wall. The flow is 1.0 MGD. The weir and
, outflow channel is 3 feet deep. a. What is the detention time in hours? - ANSWER:
Formula
What activated process cannot nitrify in a single stage? - ANSWER: Contact
Stabilization
What is the GPM output of a piston pump with an 8-inch diameter piston with a 10-
inch stroke operating at 50 strokes per minute? - ANSWER: Formula
Anaerobic digester gas should contain? - ANSWER: 65-75% methane, 25-35% carbon
dioxide and 1-5% nitrogen.
An activated sludge plant has an average daily flow of 3.5 MG. The aeration tank
capacity is 1.2 MG with a MLSS concentration of 3200 mg/L. The clarifier has a
capacity of 400,000 gallons with a MLSS concentration of 6,000 mg/L. The wasting
rate is 40,000 gallons per day with a MLSS concentration of 8, 000 mg/L. The effluent
TSS is 18 mg/L. Assuming volatile concentrations of 70%, what is the MCRT and what
type of activated sludge plant should this be? - ANSWER: Formulas MCRT
What are some of the causes of filaments in the aeration basin? - ANSWER: a. low
DO
b. low organic loading
c. septic wastes
d. nutrient deficiencies .
e. high sulfur content
Good sludge quality will have a predominance of what organisms in the MLSS? -
ANSWER: Ciliated protozoa
When an RBC is operating correctly, how will the slime appear on the media? -
ANSWER: Grey to brown 0.05 to 0.1 inches thick
According to design criteria, what are the minimum allowable diameters for a
manhole? - ANSWER: 24 inch opening and 48 inch inside diameter
What activated sludge process does not achieve complete nitrification? - ANSWER:
Contact Stabilization
In the selection of forced main wastewater piping, what is the minimum working
pressure? - ANSWER: 150 psi
The oxygen depletion of BOD dilution water should not exceed - ANSWER: 0.2 mg/L.
What is the minimum air gap when making water and wastewater connections? -
ANSWER: Minimum of one inch or twice the inlet pipe size whichever is greater.
