Texas Wastewater Class A Exam Prep: Questions and Solutions for 2024/2025, Exams of Water and Wastewater Engineering

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Texas Wastewater Class A Exam Prep

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Seeding of BOD samples is necessary when samples (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? 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 = 4.9 cfs x 449 = 2,200 gpm 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 60 minutes If an existing centrifugal pump motor is replaced with a motor with 25 percent more speed, the motor horsepower required will increase by 1.25 x 1.25 x 1.25 = 1. 95 percent When must TCEQ be notified about expansions of a treatment facility? Before construction In an anaerobic digester, the percentage of methane and carbon dioxide gas content should be 70% methane, 30% carbon dioxide The temperature of an anaerobic digester should be maintained at a minimum of 95° F What type of wastewater treatment operates in the endogenous bacteria growth phase? Extended air Why is recirculation needed in a trickling filter? Keep the media wet Further reduce BOD All of the above (a, b, and c)

What type of fire extinguisher would be used on an electrical control panel that has been de- energized? Class A Class C (a and d) Disinfection with chlorine is the most effective at a pH of

The biomass on a normal functioning RBC has what appearance? Grey to brown and 0.05 to 0.1 inch thick The sludge from a primary clarifier should percent solids? 4% to 6% What is eutrophication in a pond system? Enrichment with nitrogen and phosphorous Causes algae blooms (b and c) How often should pH meters be calibrated? Daily In Texas, pH meters are required to be calibrated on how many buffers? 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 2941 The parameters of the BOD test are 5 days at 20° Centigrade Standard Dimension Ratio in pvc pipe is defined as Ratio of OD pipe diameter to wall thickness How should shoring be removed from a trench? 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 part of the collection system and the responsibility of the utility Effective communication depends on being a good listener When designing a wastewater collection system, the engineer considers the population for how many years in the future? 50 According to 30 TAC Chapter 317, all pipe and fittings used in wastewater pressure shall have a minimum psi pressure rating of 150 The minimum velocity of flow in a wastewater line should be 2.0 fps

At a construction job site, as the roadway speed increases, the spacing between cones and barricades should increase The major cause of wastewater line stoppages is roots and grease Carbon monoxide (CO) poisoning symptoms are 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 1 inch Dangerous gases in a confined space may not be detected with the physical senses because 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? 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? 10 How should trench shoring be installed? to above the top of the trench When setting work goals for an employee, the goals should be accompanied by an action plan According to Chapter 317, Design Criteria, a manhole can be installed within 9 feet of an existing waterline if 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 decrease Motivating workers to do a better job is best done by letting workers participate in setting goals One important element of a good communicator is being a good listener Monitoring and reporting records of a wastewater treatment plant shall be kept at the facility site for a period of 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.

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

13. What type of wastewater treatment operates in the endogenous bacteria growth phase? Extended air Why is recirculation needed in a trickling filter? a. Keep the media wet b. Further reduce BOD c. Flood the filter to control ponding and filter flies
14. What type of fire extinguisher would be used on an electrical control panel that has been de- energized? f. a class a and d class c Disinfection with chlorine is the most effective at a pH of
16. The biomass on a normal functioning RBC has what appearance? Grey to brown and 0.05 to 0.1 inch thick The sludge from a primary clarifier should contain what percent solids? b. 4% to 6% What is eutrophication in a pond system? Enrichment with nitrogen and phosphorous Causes algae blooms
17. 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 = 0.17 lbs BOD/ person 43,560 sq ft l acre d. 600 A"Racetrack" is what type of Activate Sludge treatment? Extended air Which form of activated sludge must have primary clarifiers? Conventional What is the relationship between F/M ratio and MCRT? Indirect; if one goes up, the other goes down Which activated sludge process does not achieve complete nitrification? Contact stabilization Which form of activated sludge does the better job of handling shock or toxic loads? Complete mix Which of activated sludge has two aeration basins per single treatment unit? Contact stabilization

27. 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 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 160 160 In the problem above, what the sludge quality? Bulking Which activated sludge process has 18 to 20 + hours detention time in the aeration basin? Extended air What is the minimum clearance from the sidewall of a pipe to the trench wall in an excavation? 4 inches What is the definition of pH? 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? 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, 3,644 27 3,

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, 3, What is the standard chlorine residual and contact time on Texas discharge permits? e. None of the above organization increases, As the complexity of an organization increases, what management function becomes most important? 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: 1750 1770 =F = 1.5 500 x 1.5 = 750 gpm 75 0 New head in feet: 75 x 1.5 x 1.5 = 168. 170 New horsepower required: 750 x 170 - 43 3960 x 0.75 a. 43 What compound or compounds are formed when Cl, combines with water? Both a and d When chlorinating treated wastewater, what chlorine residual do we test for? Chloramine and Total What is the standard pH range on Texas effluent discharge permits? 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? 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. What is the hydraulic loading on the clarifier in gal/sq ft/day? 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 10, In Texas, an oxidation ditch treatment plant is referred to as Racetrack In Texas, pH meters are required to be calibrated on how many buffers?

two An industrial complex has a BOD discharge to the POTW of 500 pounds per population equivalent of this industry is 500 lbs - 2,941 0.17 lbs BOD/ person 2941 What substance will interfere with a DPD chlorine test? Manganese The parameters of the BOD test are 5 days at 20° Centigrade An Imhoff tank is what type of treatment process? Primary Standard Dimension Ratio in pve pipe is defined as Ratio of OD pipe diameter to wall thickness MSDS sheets must be kept for how many years after you have stopped using the chemical? c. 30 A pneumatic ejector is a. a lift station pumping device How should shoring be removed from a trench? d. from the bottom up

57. The most common pump used in the collection system is d. centrifugal In low pressure sewer systems where each tap must have a grinder pump lift station, the lift station is considered to be Part of the collection system and the responsibility of the utility Effective communication depends on being a good listener A construction site safety evaluation checklist must include 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? 50 According to 30 TAC Chapter 317, all pipe and fittings used in wastewater pressure mains shall have a minimum psi pressure rating of 150 The minimum velocity of flow in a wastewater line should be 2.0 fps At a construction job site, as the roadway speed increases, the spacing barricades should

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 6,000 gallons? 5x5x0.0408x0.833x60 = 51 gpm 6,000 gal/51 gpm=117. round to 118 A bubbler level control system works off of what principal? differential pressure

67. The major cause of wastewater line stoppages is roots and grease What type of valve is usually used for isolation? gate Carbon monoxide (CO) poisoning symptoms are 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 dishwater gray in color The smallest pipe size for air recirculation of a self-priming centrifugal pump is b. 1 inch Dangerous gases in a confined space may not be detected with the physical senses because 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? a. CO2 b. CO c. H,S d. CH, e. all of the above When designing a wastewater rehab program, the first step is to d. define the objectives of the program The goal of a sanitary wastewater physical survey is to Identifying problems in the system need a rehab When should drop manholes be utilized? 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? mechanical cleaning equipment On a construction job site, equipment booms must maintain at least how many feet clearance from overhead electric lines? a. 10

How should trench shoring be installed? Two above the top of the trench If an existing centrifugal pump motor is replaced with a motor with 20 percent more speed, the motor horsepower required will increase by 1.2x1.2x1.2=1.728 73 percent When setting work goals for an employee, the goals should be accompanied by an action plan According to Chapter 317, Design Criteria, a manhole can be installed within 9 feet of an existing waterline if 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 decrease

84. One of the most important factors affecting the slope of a gravity wastewater line is pipe bedding a wastewater pipe has a slope of 4 feet in 200 feet, it is referred to as c. 0.02 feet per foot d. two percent When laying bell and spigot wastewater 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 letting workers participate in setting goals One important element of a good communicator is 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 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, a. the hydrant should be opened and closed slowly b. if flow needs to be controlled, use an external valve not the 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. 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 beginning construction When connecting a public water supply to any source of potential contamination, an air gap of what size must be provided? two times the inlet pipe diameter

The most important purpose for wastewater treatment is to remove harmful contaminants from the wastewater before it is discharged to the waters of the state Septic wastewater has what properties? 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 all employees The Federal Clean Water Act 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 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 attempt to modify the employee's behavior through training and other forms of assistance inform the employee of the consequences if the behavior is not modified When fighting an electrical fire, you should Use non-conductive extinguishing methods c. Use Class A or B extinguishers if electricity to the unit has been shut-off d. Either b or e A particular construction project has a total of 3,000 feet of 12-inch pipe, 15 manholes, 50 wastewater connections. Based upon the contract unit costs shown, if the contractor has completed 2,000 feet of pipe, 12 manholes, and 30 wastewater connections, what percentage of the total project has been completed? 12 inch pipe place $85.00 per linear foot Manholes in place $1,500.00 each Wastewater connections $250.00 each 3000 x 85 = 255, 15 x1500 = 22, 50x 250 = 12, 255,000 + 22,500+ 12,500 = $290, 2000 x 85 = 170, 12x1500 - 18,

30x250 =7, 170,000 + 18,000 + 7,500 = S195, 195 ,000/290000 =0.67 = 67% If the float that turns on the lead pump in a wastewater lift station is situated above a gravity influent line, the line will tend to have a grease problem If an operations company ceases its operation or is sold such that control of the company is transferred to another party, the company's operations certificate is revoked In 2.5 minutes, a lift station will fill up 18" with no pumps running. In 3.25 minutes, both pumps will drop the level in the lift station 18". In 7 minutes, the large pump will drop the level 18". What is the capacity of the small pump? The lift station is 10' x 10 x 10'. 10x10x1.5x7.48= 1122 gal/2.5=449 gpm inflow Both 1122/3.25=345 gpm + 449 gpm = 794 gpm both Large 1122/7=160 gpm + 449 gpm = 609 gpm large Small 794 gpm - 609 gpm = 185 gpm 185 gpm H,SO, is a(n). chemical compound What is the velocity of water flowing through a clarifier that is 16 feet deep x 45 feet wide 135 feet long if the flow is 5,837 gpm? Q- AxV 13=720x fps 0.02 fps A chemical element is a atom Chemical dechlorination can be accomplished with? a. sodium Bisulfite b. sulfur Dioxide A crucible and filter weigh 21.6870 grams. After filtering 50 ml of sample through the filter, and then drying, desiccating and weighing them, the crucible, filter, and sample weigh 21.7250 grams. How many mg/L of suspended solids are in the sample?

b. 760 Three hundred milliliters of 0.02 N H,SO, is needed for a lab test. The lab stocks a standard of 0. N. How many ml of the 0.5 N will be needed? 300 x0.02 = V x0.5 300x0.02 0. 12 How would an operator increase the degree nitrification in an activated sludge plant? increase D0 and increase sludge age What processes are used to check an upset activated sludge plant? BOD loadings, F/M ratio, SV 30, MCRT, DO When chlorine used, the effective disinfectant is HOCI Aerobic digestion is a(n) process. endogenous Distilled water used for the BOD analysis should not exceed mg/L oxygen depletion.

Chlorine disinfects the best at low pH The inside diameter of a manhole must be at least wide. 48 inches What does biomonitoring test for? effluent toxicity Why is recirculation needed in a trickling filter plant? a. to keep the zoogleal mass wet during low flow periods b. to assist in flooding the filters and to increase sloughing The sludge from a primary clarifier should contain what percent solids? 4% to 6% The Federal Clean Water Act: a, requires a permit for disposal of sludge b. requires a permit for ocean discharges of wastewater c. requires a permit for disposal of dredge material d. creates a national permit system for all wastewater The effectiveness of an activated sludge process depends on? amount of activated solids in the system type and health of organisms in the solids acration basin detention time influent characteristics A predominance of filaments in an activated sludge plant indicates what? low DO poor settling nutrient imbalance What is dissolved air floatation in a wastewater plant usually used for? grease removal What are the hazards of using powered activated carbon? a. fire/explosive b. inhalation c. uncomfortable working conditions

Why is lime added to sludge? to raise the pH and assist in pathogen reduction How often must a facility conduct a TCLP on its sludge if its sludge disposal is equal to or greater than 15,000 metric tons annually? monthly If effluent is land applied for irrigation what tests must be run? CBOD and TSS pH and dissolved solids total nitrogen total phosphorous A cyclone grit separator operates on what principle? centrifugal force Which temperature is more important to the operation of a trickling filter? influent temperature What is the MCL for coliform? per b. 1.0 per 100 mls Assume that a 12% solution of a substance weighs 10.6 lbs/gal.and a 0.8% solution of the same substance weighs 8.76 lbs/gal. If 10.0 gallons of the 12% solution are mixed with 50 gallons of the 0.8% solution, the percent strength of the mixed solution would be 3.0% Most gas detection instruments do not latch. This means that the instrument stops alarming when removed from the contaminated atmosphere An injured person is not breathing, but has a pulse. The correct first aid response is ventilate Proper employee motivation occurs when employees participate in developing goals A confined space is defined as a. a space so configured that an employee can enter and perform work space that is not designed for continuous human occupancy space that has limited entry and exit What can change a non-permit confined space entry into a permit required confined space entry? a, if an ignition source is identified b. non-sparking tools are required c. a possible source of engulfment is identified d. a hazardous atmosphere is identified e. all of the above What tasks does a manager perform when controlling a utility? being sure progress being made toward objectives What is the purpose of a capital improvement fund? replacement fund to keep the utility operating in the future The incubation procedure for fecal coliform in wastewater 44.5° Centigrade for 24 hours Cartridge respirators provide protection against: gases

Proper safety in the water lab includes: wearing protective eyewear wearing an apron or lab coat The management function of setting goals, policies, and procedures is called: planning The organizing management function involves: deciding who will do what work An operator must measure the current being used by a motor that is operating three phase power. The correct instrument for this measurement is: clamp-on ammeter Approved backflow devices in Texas include: air gap of two times the inlet pipe diameter testable assemblies usually an RPZ The discharge from a centrifugal pump will: increase with an decrease in head decreases with an increase head The Hazard Communication Act of 1985 is: Texas law Federal law To be a team player, a person must: put yourself in the place of other team members to understand their position PL 92-500 is known as the Clean Water Act Water Pollution Control Act In Texas no disinfection of treated effluent is required if detention time is 21 days + 15,000 gallons of sludge with 4% solids is run through a press to produce a 25% cake. How many dry metric tons of sludge will be disposed of? [Assume a conversion factor of 2200 Ibs per dry metric tons.]

Under the Texas Hazard Communication Act employers must annually report chemicals stored above what limits? 55 gals/500 Ibs Under EPA regulations utilities that store chlorine gas over what quantity are required to have a "Risk Management Plan"? 2500 Ibs 2500 Ibs The normal appearance of the biomass on an RBC is grey to brown and .05 to.1 inch thick shaggy and stringy appearance Wastewater What are the effects of organic pollution on the receiving stream? Decomposition of organics lowers DO levels adversely affecting aquatic life Nutrients encourage the growth of aquatic organism such as algae c. Lower water quality downstream is more difficult treat for potable use d. All of the above

A 30 ml wastewater sample, is incubated 5 days at 20 degrees C. The DO before was 6.0 mg/L and the DO after was 3.5 mg/L. What is the reportable BOD? (6-3.5) x 300 30 b. 25