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Texas Wastewater Class A Exam Questions and Answers, Exams of Water and Wastewater Engineering

A comprehensive set of questions and answers related to the texas wastewater class a exam. It covers various topics including wastewater treatment processes, regulations, safety procedures, and equipment operation. Designed to help individuals prepare for the exam and gain a deeper understanding of wastewater treatment principles.

Typology: Exams

2024/2025

Available from 12/09/2024

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Questions And Answers 100% Pass

Seeding of BOD samples is necessary when samples - - - correct answer ✅(All of the above) have a chlorine residual, have a previously been chlorinated, have been subjected to high temperatures, contain high or low pH industrial wastes When is blue-green algae the most dominant on a pond treatment system? - - - correct answer ✅Summer A 30-inch diameter wastewater interceptor is observed to be flowing half-full at about two fps. The approximate volume of wastewater flowing through the pipe is 3.14x1.25 x 1.25 x 2 = 4. cfs x 449 = 2,200 gpm - - - correct answer ✅c. 2,200 gallons per minute A one-cylinder reciprocating sludge pump with a 10-inch bore and a 5-inch stroke pumps at a rate of 50 cycles per minute. How many minutes must the pump be operated to pump 5,000 gallons of sludge? 3.14x0.416 x 0.416 x0.416 x 50 x7.48 = 84.5 gpm 5000 gal = 59,2min 84.5 gpm b. 29 - - - correct answer ✅60 minutes If an existing centrifugal pump motor is replaced with a motor with 25 percent more speed, the motor horsepower required will

Questions And Answers 100% Pass

increase by 1.25 x 1.25 x 1.25 = 1.95 - - - correct answer ✅95 percent When must TCEQ be notified about expansions of a treatment facility? - - - correct answer ✅Before construction In an anaerobic digester, the percentage of methane and carbon dioxide gas content should be - - - correct answer ✅70% methane, 30% carbon dioxide The temperature of an anaerobic digester should be maintained at a minimum of - - - correct answer ✅ 95 ° F What type of wastewater treatment operates in the endogenous bacteria growth phase? - - - correct answer ✅Extended air Why is recirculation needed in a trickling filter? - - - correct answer ✅Keep the media wet Further reduce BOD All of the above (a, b, and c)

Questions And Answers 100% Pass

What type of fire extinguisher would be used on an electrical control panel that has been de-energized? - - - correct answer ✅Class A Class C (a and d) Disinfection with chlorine is the most effective at a pH of - - - correct answer ✅6. The biomass on a normal functioning RBC has what appearance? - -

correct answer ✅Grey to brown and 0.05 to 0.1 inch thick The sludge from a primary clarifier should percent solids? - - - correct answer ✅4% to 6% What is eutrophication in a pond system? - - - correct answer ✅Enrichment with nitrogen and phosphorous Causes algae blooms (b and c) How often should pH meters be calibrated? - - - correct answer ✅Daily

Questions And Answers 100% Pass

In Texas, pH meters are required to be calibrated on how many buffers? - - - correct answer ✅two An industrial complex has a BOD discharge to the POTW of 500 pounds per day. The population equivalent of this industry is 500 lbs = 2,941 0.17 lbs BOD person - - - correct answer ✅ 2941 The parameters of the BOD test are - - - correct answer ✅5 days at 20° Centigrade Standard Dimension Ratio in pvc pipe is defined as - - - correct answer ✅Ratio of OD pipe diameter to wall thickness How should shoring be removed from a trench? - - - correct answer ✅up from the bottom up In low pressure sewer systems where each tap must have a grinder pump lift station, station is considered to be - - - correct answer ✅part of the collection system and the responsibility of the utility

Questions And Answers 100% Pass

Effective communication depends on - - - correct answer ✅being a good listener When designing a wastewater collection system, the engineer considers the population for how many years in the future? - - - correct answer ✅ 50 According to 30 TAC Chapter 317, all pipe and fittings used in wastewater pressure shall have a minimum psi pressure rating of - -

correct answer ✅ 150 The minimum velocity of flow in a wastewater line should be - - - correct answer ✅2.0 fps At a construction job site, as the roadway speed increases, the spacing between cones and barricades should - - - correct answer ✅increase The major cause of wastewater line stoppages is - - - correct answer ✅roots and grease

Questions And Answers 100% Pass

Carbon monoxide (CO) poisoning symptoms are - - - correct answer ✅tightness in the chest nausea drowsiness and headache (all of the above) The smallest pipe size for air recirculation of a self-priming centrifugal pump is - - - correct answer ✅1 inch Dangerous gases in a confined space may not be detected with the physical senses because - - - correct answer ✅some gases have no odor some gases may deaden the sense of smell some gases may displace the oxygen (all of the above) What are the dangerous gases a collection system worker might come into contact with? - - - correct answer ✅CO2 CO НaS CH4 (all of the above) On a construction job site, equipment booms must maintain at least how many feet of clearance from overhead electric lines? - - - correct answer ✅ 10

Questions And Answers 100% Pass

How should trench shoring be installed? - - - correct answer ✅to above the top of the trench When setting work goals for an employee, the goals should be - - - correct answer ✅accompanied by an action plan According to Chapter 317, Design Criteria, a manhole can be installed within 9 feet of an existing waterline if - - - correct answer ✅the manhole is completely watertight and tested for no leakage As the population of a collection system increases, the ratio of peak flow to average daily flow will - - - correct answer ✅decrease Motivating workers to do a better job is best done by - - - correct answer ✅letting workers participate in setting goals One important element of a good communicator is - - - correct answer ✅being a good listener

Questions And Answers 100% Pass

Monitoring and reporting records of a wastewater treatment plant shall be kept at the facility site for a period of - - - correct answer ✅d. three years The TCEQ Design Criteria requires that deflection tests be performed on all new installed flexible or semi-rigid pipe after the final backfill has been in place for 30 days. This deflection test is usually performed using a rigid ball or mandrel that has a diameter equal to -percent of the inside diameter of the pipe. - - - correct answer ✅c. 95 Seeding of BOD samples is necessary when samples - - - correct answer ✅e. all of the above A one-cylinder reciprocating sludge pump with a 10-inch bore and a 5-inch stroke pumps at rate of 50 cycles per minute. How many minutes must the pump be operated to pump 5,000 gallons of sludge? - - - correct answer ✅3.14 x0.416 x0.416 x0.416 x 50x7.48 = 84.5 gpm 5000 gal = 59.2min 84.5 gpm d. 60 minutes e. When is blue-green algae the most dominant on a pond treatment system? - - - correct answer ✅Summer

Questions And Answers 100% Pass

What is the purpose of biomonitoring of a plant's effluent? - - - correct answer ✅d. Test for toxicity Technology The management function of selecting and training employees of an organization is called - - - correct answer ✅staffing e. controlling When must TCEQ be notified about expansions of a treatment facility? - - - correct answer ✅Before construction In an anaerobic digester, the percentage of methane and carbon dioxide gas content should be - - - correct answer ✅b. 70% methane, 30% carbon dioxide The temperature of an anaerobic digester should be maintained at a minimum of - - - correct answer ✅ 95 ° F

  1. What type of wastewater treatment operates in the endogenous bacteria growth phase? - - - correct answer ✅Extended air

Questions And Answers 100% Pass

Why is recirculation needed in a trickling filter? - - - correct answer ✅a. Keep the media wet b. Further reduce BOD c. Flood the filter to control ponding and filter flies

  1. What type of fire extinguisher would be used on an electrical control panel that has been de-energized? - - - correct answer ✅f. a class a and d class c Disinfection with chlorine is the most effective at a pH of - - - correct answer ✅6.
  2. The biomass on a normal functioning RBC has what appearance? - - - correct answer ✅Grey to brown and 0.05 to 0.1 inch thick The sludge from a primary clarifier should contain what percent solids? - - - correct answer ✅b. 4% to 6% What is eutrophication in a pond system? - - - correct answer ✅Enrichment with nitrogen and phosphorous Causes algae blooms

Questions And Answers 100% Pass

  1. A wastewater stabilization pond has 130,680 sq. ft. It has a three to one slope on the embankment and has an average depth of 5 ft. Approximately how many people will this pond provide wastewater treatment for? 130,680 sq ft = 3 acres x 35 lbs / BOD/ acre = 105 lbs BOD =618 0.17 lbs BOD/ person 43,560 sq ft l acre - -

correct answer ✅d. 600 A"Racetrack" is what type of Activate Sludge treatment? - - - correct answer ✅Extended air Which form of activated sludge must have primary clarifiers? - - - correct answer ✅Conventional What is the relationship between F/M ratio and MCRT? - - - correct answer ✅Indirect; if one goes up, the other goes down Which activated sludge process does not achieve complete nitrification? - - - correct answer ✅Contact stabilization

Questions And Answers 100% Pass

Which form of activated sludge does the better job of handling shock or toxic loads? - - - correct answer ✅Complete mix Which of activated sludge has two aeration basins per single treatment unit? - - - correct answer ✅Contact stabilization

  1. A complete mix activated sludge plant has a fast settling sludge and high amounts of pin floc leaving the clarifier. One method of correcting the problem is to - - - correct answer ✅Increase F/M ratio by wasting more problem is Testing of mixed liquor indicates the MLSS is 2500 mg/L and the settling test shows that a 1000 ml sample settles to 400 mls after 30 minutes. What is the SVI? 400 x 1000 2500 160 - - - correct answer ✅ 160 In the problem above, what the sludge quality? - - - correct answer ✅Bulking

Questions And Answers 100% Pass

Which activated sludge process has 18 to 20 + hours detention time in the aeration basin? - - - correct answer ✅Extended air What is the minimum clearance from the sidewall of a pipe to the trench wall in an excavation? - - - correct answer ✅4 inches What is the definition of pH? - - - correct answer ✅The logarithm of the reciprocal of the hydrogen ion concentration The negative logarithm of the hydrogen ion concentration How often should pH meters be calibrated? - - - correct answer ✅Daily trench is 4,100 feet long, four 4 wide and 6 feet deep. There is a 12- inch diameter pipe in the bottom of the trench. How many cubic yards of material were removed from the trench? 4x6x4,100 3, 27 - - - correct answer ✅3,

Questions And Answers 100% Pass

In the problem above, how many cubic yards of material will be required to fill the trench? 3.14x0.5 x0.5 x 4,100 =119cu yds 27 3,644 -119 = 3,525 - - - correct answer ✅3, What is the standard chlorine residual and contact time on Texas discharge permits? - - - correct answer ✅e. None of the above organization increases, As the complexity of an organization increases, what management function becomes most important? - - - correct answer ✅Planning The following scenario is to be used in answering questions 38, 39, and 40. A pump with a 15-inch impeller is running at 1170 RPM s, with pump efficiency of 75%, and is pumping 500 gpm with 75 feet of head. If the RPM of the pump is increased to 1750 RPMS calculate the following: New output in gpm: - - - correct answer ✅1750 1770 =F = 1.5 500 x 1.5 = 750 gpm 750 New head in feet: 75 x 1.5 x 1.5 = 168.75 - - - correct answer ✅ 170

Questions And Answers 100% Pass

New horsepower required: - - - correct answer ✅750 x 170 - 43 3960 x 0.75 a. 43 What compound or compounds are formed when Cl, combines with water? - - - correct answer ✅Both a and d When chlorinating treated wastewater, what chlorine residual do we test for? - - - correct answer ✅Chloramine and Total What is the standard pH range on Texas effluent discharge permits?


correct answer ✅b. 6.0 to 9. A wastewater treatment plant has a clarifier that is 80 feet in diameter and is 12 feet deep. The flow is 2.5 mgd. The single weir is two feet inside the outer wall and is 3 feet deep. What is the clarifier detention time in hours? - - - correct answer ✅What is the clarifier detention time in hours? 2,500,000 gpd - 104,167 gph 24 hrs/day 3.14 x 40 x 40 x 9 x 7.48 gal 3.14 x 36 x 36 x 3 x 7.48 = 91,318 338,216 + 91,318 429,534 gallons 429,534 gals = 4.1 hrs 104,167 gph 4.

Questions And Answers 100% Pass

What is the hydraulic loading on the clarifier in gal/sq ft/day? - - - correct answer ✅3.14 x 38 x 38 = 4,534 sq ft 2,500,000 gpd = 551 gal / sq ft I day 4,534 sq ft 551 What is the weir loading in gal/linear ft/day? 3.14 x 76 = 239 ft of weir 2,500,000 gpd = 10,460 gal / lin ft / day 239 ft weir - - - correct answer ✅10, In Texas, an oxidation ditch treatment plant is referred to as - - - correct answer ✅Racetrack In Texas, pH meters are required to be calibrated on how many buffers? - - - correct answer ✅two An industrial complex has a BOD discharge to the POTW of 500 pounds per population equivalent of this industry is - - - correct answer ✅500 lbs - 2,941 0.17 lbs BOD/ person 2941 What substance will interfere with a DPD chlorine test? - - - correct answer ✅Manganese

Questions And Answers 100% Pass

The parameters of the BOD test are - - - correct answer ✅5 days at 20° Centigrade An Imhoff tank is what type of treatment process? - - - correct answer ✅Primary Standard Dimension Ratio in pve pipe is defined as - - - correct answer ✅Ratio of OD pipe diameter to wall thickness MSDS sheets must be kept for how many years after you have stopped using the chemical? - - - correct answer ✅c. 30 A pneumatic ejector is - - - correct answer ✅a. a lift station pumping device How should shoring be removed from a trench? - - - correct answer ✅d. from the bottom up

  1. The most common pump used in the collection system is - - - correct answer ✅d. centrifugal

Questions And Answers 100% Pass

In low pressure sewer systems where each tap must have a grinder pump lift station, the lift station is considered to be - - - correct answer ✅Part of the collection system and the responsibility of the utility Effective communication depends on - - - correct answer ✅being a good listener A construction site safety evaluation checklist must include - - - correct answer ✅a. placement of equipment, vehicles, and spoil bank b. placement of flaggers, barricades, cones and other safety equipment c. use of warning signs When designing a wastewater collection system, the engineer considers the population for how many years in the future? - - - correct answer ✅ 50 According to 30 TAC Chapter 317, all pipe and fittings used in wastewater pressure mains shall have a minimum psi pressure rating of - - - correct answer ✅ 150

Questions And Answers 100% Pass

The minimum velocity of flow in a wastewater line should be - - - correct answer ✅2.0 fps At a construction job site, as the roadway speed increases, the spacing barricades should - - - correct answer ✅increase A piston pump with a 5-inch piston and a 10-inch stroke strokes 60 times a minute. How many minutes will operated to pump 6, gallons? - - - correct answer ✅5x5x0.0408x0.833x60 = 51 gpm 6,000 gal/51 gpm=117. round to 118 A bubbler level control system works off of what principal? - - - correct answer ✅differential pressure

  1. The major cause of wastewater line stoppages is - - - correct answer ✅roots and grease

Questions And Answers 100% Pass

What type of valve is usually used for isolation? - - - correct answer ✅gate Carbon monoxide (CO) poisoning symptoms are - - - correct answer ✅a. tightness in the chest b. nausea c. drowsiness and headache d. all of the above Fresh wastewater is desirable because it is much easier to treat. The physical characteristics of fresh wastewater are - - - correct answer ✅dishwater gray in color The smallest pipe size for air recirculation of a self-priming centrifugal pump is - - - correct answer ✅b. 1 inch Dangerous gases in a confined space may not be detected with the physical senses because - - - correct answer ✅a. some gases have no odor b. some gases may deaden the sense of smell c. some gases may displace the oxygen What are the dangerous gases a collection system worker might come into contact with? - - - correct answer ✅a. CO2 b. CO c. H,S d. CH, e. all of the above

Questions And Answers 100% Pass

When designing a wastewater rehab program, the first step is to - -

correct answer ✅d. define the objectives of the program The goal of a sanitary wastewater physical survey is to - - - correct answer ✅Identifying problems in the system need a rehab When should drop manholes be utilized? - - - correct answer ✅wastewater velocities greater than ten fps flows entering the manhole 24 inches or greater above the floor Sewer balls or pigs are what type of wastewater cleaning equipment? - - - correct answer ✅mechanical cleaning equipment On a construction job site, equipment booms must maintain at least how many feet clearance from overhead electric lines? - - - correct answer ✅a. 10 How should trench shoring be installed? - - - correct answer ✅Two above the top of the trench

Questions And Answers 100% Pass

If an existing centrifugal pump motor is replaced with a motor with 20 percent more speed, the motor horsepower required will increase by - - - correct answer ✅1.2x1.2x1.2=1.728 73 percent When setting work goals for an employee, the goals should be - - - correct answer ✅accompanied by an action plan According to Chapter 317, Design Criteria, a manhole can be installed within 9 feet of an existing waterline if - - - correct answer ✅if a. the manhole is completely watertight and tested for no leakage As the population of a collection system increases, the ratio of peak flow to average daily flow will - - - correct answer ✅decrease

  1. One of the most important factors affecting the slope of a gravity wastewater line is - - - correct answer ✅pipe bedding

Questions And Answers 100% Pass

a wastewater pipe has a slope of 4 feet in 200 feet, it is referred to as - - - correct answer ✅c. 0.02 feet per foot d. two percent When laying bell and spigot wastewater - - - correct answer ✅trench bedding should be scooped out at joints > support pipe on the barrel the bell end should be pointed upstream Motivating workers to do a better job is best done by - - - correct answer ✅letting workers participate in setting goals One important element of a good communicator is - - - correct answer ✅Good listener A 24-inch wastewater interceptor is observed to be flowing half-full at 3 fps. The approximate volume of wastewater flowing through the line is - - - correct answer ✅3.14 x1x1x3 = 9.42 = cfs 9.42 x 449 = 4229.58 gpm 4229.58 = 2114.79 2,115 gpm When using a fire hydrant to flush wastewater lines, - - - correct answer ✅a. the hydrant should be opened and closed slowly b. if flow needs to be controlled, use an external valve not the

Questions And Answers 100% Pass

hydrant internal c. an air gap or backflow prevention device must be utilized d. all of the above A collection system that averages 1.0 mgd or more must employ. - -

correct answer ✅a. at least one Class III Collection operator or a Class B Wastewater operator Before making major changes in the collection system or the treatment plant, detailed designed by a professional engineer must be submitted to TCEQ before - - - correct answer ✅beginning construction When connecting a public water supply to any source of potential contamination, an air gap of what size must be provided? - - - correct answer ✅two times the inlet pipe diameter The most important purpose for wastewater treatment is - - - correct answer ✅to remove harmful contaminants from the wastewater before it is discharged to the waters of the state

Questions And Answers 100% Pass

Septic wastewater has what properties? - - - correct answer ✅a. dark in color b. offensive odor e. Jacks dissolved oxygen d. is harder treat than fresh wastewater e. all of the above One of the requirements of the Texas Hazard Communication Act of 1985 is that the employer must hold annual training in which the utilities' written policies and the employee's rights are explained to


correct answer ✅all employees The Federal Clean Water Act - - - correct answer ✅requires a permit for disposal of sludge requires a permit for ocean discharges of sewer c. requires a permit for disposal or placement of dredge material creates a national permit system for all wastewater discharge Pretreatment of industrial waste will help minimize - - - correct answer ✅sludge contamination interference to the treatment process safety hazards to workers discharge of industrial pollutants in the effluent If an employee is guilty of misconduct as defined by the utilities personnel policies, the supervisor should - - - correct answer ✅attempt to modify the employee's behavior