Download B test material - TCEQ Class B Surface Water| Questions and Answers| Already Passed| 2025 and more Exams Water and Wastewater Engineering in PDF only on Docsity!
B test material - TCEQ Class B Surface
Water| Questions and Answers| Already
Passed| 2025
What is the most important factor affecting the useful life of service lines? It is the ability of the material to resist internal and external corrosion When does Suction Head exist? Suction head exists when the source of supply is above the centerline of the pump. What is Net positive Suction Head (NPSH) NPSH is the pressure under which water enters the eye of the impeller in a centrifugal pump. Insufficient NPSH is the main cause of pump cavitation Explain and expand on Chlorine Dioxide (what it reacts with, oxidizes, etc) Chlorine Dioxide is a gas used in small quantities to disinfect water. It does not react with organics to form THMs and HAAs. It oxidizes phenols, manganese, iron, sulfurous and organic compounds which aids in the removal of tastes and odors. It is a very effective bactericide and a superior virocide. It dies not combine with ammonia. Chlorine Dioxide MRDL is .8 mg/L and monitoring procedures are the same as for chlorine. The Chlorite MCL is .q mg/L and must be monitored daily. What is texas drinking water pH requirements?
The texas drinking water requirements require a pH > 7.0 for the water treatment plant finished water. EPA requires that pH analysis be preformed within 15 minutes of the sample being caught. How does pH affect Chlorine activity? When chlorine is added to water it forms hypochlorous acid (HOCL) and hydrochloric acid (OCL). The hypochlorous acid is the effective disinfectant. At a pH of 4.0 there is 100% hypochlorous acid. At a pH of 11 there is 100% hypochlorite ion. At a pH of 7, the hypochlorous acid is at about 80% and the hypochlorite ion makes up about 20% of the chlorine content. The lower the pH is more effective chlorine is because you have more hypochlorous acid. What is meant by water stability? Stable water is defined as water that will neither deposit or dissolve a calcium carbonate film or scale. Since no water is stable indefinitely, chemical treatment of water usually is intended to produce water that is slightly scale forming without being liable to cause stoppages in small lines and services. Bayliss curve is the simplest determination of stability. The Langelier saturation index is also used. What/how are above ground tanks and piping protected from corrosion? Corrosion protection for above ground tanks and piping is prevented by: cathodic protection, use if protective linings/coatings, eliminating different types of metals
The amount of chlorine used up to completely react with the water and its suspended or dissolve material What is chlorine residual? When all the demand of the water is met any additional chlorine produces a chlorine residual What is chlorine dosage? Demand plus residual is the chlorine dosage. Chlorine Dosage = Demand + Residual What determines rate of disinfection? Chlorine concentration and contact time determines the rate and degree of disinfection. If concentration increases, the time can be reduced; if concentration is reduced the time must be increased. How does temperature effect chlorine effectiveness? Chlorine effectiveness is greater at higher temperatures, up to the point that chlorine volatizes. At low temperature, chlorine is more stable, but disinfection time increases. Is removing turbidity important for disinfection? Turbidity must be removed to low levels by sedimentation and filtration to allow chlorine to contact pathogens. What happens to dissolved solids on contact with chlorine?
Dissolved solids are oxidized on contact further reinforcing the importance of contact time. No residual is formed until reducing agents are destroyed. What are examples of reducing agents? Manganese, iron, turbidity, organic matter, ammonia, or nitrates What the 4 stages of the Chlorine Demand Curve chart? Stage 1: No residual is formed because inorganic demand destroys the chlorine. (Flat Line) Stage 2: Monochloramines are formed as chlorine combines with organics containing ammonia (rising curve). The chlorine to ammonia weight ratio at this point is 5:1. Combined and total residual increases, chloro-organics are formed. Stage 3: Increasing chlorine dosage (failing curve) to a chlorine/ammonia weight ratio of 7.6:1 destroys chloramines and chloro-organics. Combined decreases and free chlorine increases. Stage 4: Enough chlorine is added to reduce all demand. The combined residual remains the same, but free residual increases with dosage. This stage is called
Chloramine (combined) residual = .5 mg/L
- Surface water systems should not exceed a maximum free chlorine or chloramine residual of 4 mg/L as a running average. Limiting residuals reduces disinfection byproducts such as trihalomethanes and haloacetic acids. These byproducts, consumed over a long period of time, may cause cancer. What are the proper techniques for chlorine cylinder storage?
- secure the ton cylinders in a horizontal position and move with a lifting bar and hoist. Never roll them
- 150lbs cylinders shall be chained to rigid support and keep capped unless in use.
- Check all chlorine systems for leaks before putting into service with a 10% ammonia solution. Household ammonia is not approved. When ammonia contacts chlorine gas white smoke results. What are the steps to do before entering a room with a chlorine leak? 1: notify other operators and have standby help for possible notification of emergency personnel 2: Be trained in emergency procedures and have knowledge of chlorinators, tools, and ammonia use.
3: Put on a self-contained breathing apparatus (SCBA) 4: wear a safety harness and lifeline What is the maximum withdrawal rate for 150lbs chlorine cylinders? The maximum sustained gas withdrawal rate for 150lbs cylinders (vacuum transmission) is 1lbs per day per degree F. The equivalent rate for ton cylinders (vacuum transmission) is 8 lb per day per degree F. Pressure transmission rates are 42 lbs per day for 140lb cylinders and 336 lb per day for ton containers, based on an air temp of 70 degrees F. What are chlorine cylinders equipped with to help/prevent gas leaks in extreme temperatures? Chlorine cylinders are equipped with a fusible plug designed to melt between 158 and 165 f Is chlorine the most cost effective and best disinfectant product? Yes Chlorine is available is what three forms?
- Chlorine is injected prior to the filters to prevent algae growth on the surface and fungi growth in the lower extremities
- Injection of chlorine into finished water going to storage to allow contact time for complete-to near-complete bacteria kill Chlorine Gas Characteristics
- Greenish Yellow gas
- Pungent Odor - irritating to the nose, throat, and lungs
- x2.5 heavier than air
- can be liquified
- corrosive to most metals when wet
- strong oxidizing agent What is the uses of Chlorine?
- Disinfection
- Taste and Odor control
- Turbidity Removal
- Oxidation of hydrogen sulfide
- oxidation of iron and manganese
- color removal
- control of biological growths
- disinfection of system repairs What is necessary for disinfection equipment? Disinfection equipment shall have a capacity of atleast 50% greater than the highest expected dosage to be applied at any time, and shall be capable of satisfactory operation under every prevailing hydraulic condition. All disinfecting equipment on surface water treatment plants shall include at least 1 standby unit to promptly adjust necessary dosages. What are the building safety standards for Chlorine storage? Do not store other equipment or supplies in the building A full faced SCBA or supplied air respirator that meet OSHA standards and a small bottle of fresh ammonia solution for testing for chlorine leakage shall be readily available to the operator in event of emergency Screened and louvered floor level and high level vents A fan which is located at and draws air through the top vent and discharges through the floor vent
What is Tuberculation, an example, how does it affect the C factor? Tuberculation is the process of forming a tubercle or deposit/formation. An example of this is a deposit of calcium carbonate on piping. It affects the C factor by decreasing it causing more friction and reducing its carrying capacity. How much should you be able to expand the filer bed of a mixed media filters without an air scour? The filter bed should be able to expand by at least 25% during a backwash. What three purposes do under-drains serve?
- They support the filter media
- The collect filtrate and transport it to the manifold
- They deliver uniform backwash and promote even filtering What are the most important design factors for filters? The most important factors are sand particle and filter bed depth What are the protective measures for handling dry aluminum?
- Use of protective equipment (clothing, gloves, footware, glasses, goggles, face shield)
- Handle in open or well ventilated areas
- Where dusts, mists, or aerosols may occur, use a NIOSHA approved half-face piece cartridge air purifying respirator
- Eye wash and shower stations available
When starting a safety program what is the first step? Start with a written safety policy so that everyone understands what is required of them and what controls are in regard to their position and work. People then know what expectations to meet and begin to build a good safety attitude. What is the retention time by Texas law of records for microbiological analyses and chemical analysis? Microbiological analysis is 5 years Chemical analysis is 10 years What does the Texas Hazard Communication Act require an employer to provide to the employees? The Texas Hazards Communication act requires employers to provide information and training to employees on the hazards of chemicals that they use or work with. An employee will not follow safety rules and feels like they do not have to followed. What should an employer do? Document employee's actions and counsel employee. If he does not respond discharge him. What is one method of ensuring safety in a trench or excavation? One method of ensuring safety and health of workers in a trench or excavation is to slope the sides of the cut to the "angle of repose", or the angle closet to the
area, flushing of water mains, build up in pipes or meter, a partially closed valve, heavy water use during summer and fire rescue. What is the quality of raw water affected by? The quality of raw water in any geographic locality is determined primarily by natural factors such as geology, topography, and climate in each locality. What can affect chemical activity/reactivity in water? Chemical activity in the water is governed by temperature, with greater activity accruing at higher temperatures and lower activity at lower. What is a public water system? A public water system is any water system that provides the public with piped water for human consumption with at least 15 connection or regularly serves at least 25 individuals daily at-least 60 days out of the year. A public water system is either a community water system or a non-community water system. What happens during thermal stratification in a body of water? Thermal stratification causes the bottom layer of water to lose oxygen resulting in anaerobic decomposition of organic material. In this process, hydrogen sulfide is produced there by lowering the pH that causes iron and manganese from the soil to become soluble. This also causes a noticeable increase in carbon dioxide. This causes water quality deterioration.
If the stratification layers mix (the lake turns over). Lake/Reservoir turn over occurs when cold heavy dense water develops above warm water, light (less dense) water and layers stabilize by exchanging places. What is a standard solution? A standard solution is a solution of known strength or concentration. What is concentration? Concentration is the relationship between the amount of solute in a solution. At what frequency should you test your water system for radiation? Every 4 years What do the absorbive properties of powder activated carbon include? The absorptive properties of activated carbon include taste and odor-causing substances and impurities such as trihilomethanes. What levels of fluoride do and some examples Flouride levels above 2mg/l cause mottling of the enamel producing a brown stain on teeth. Moderate levels (.7 to 1.0 mg/l) will reduce cavities snd dental care costs. Some examples are sodium fluoride, sodium silicoflouride and flourosilic acid are fluoride compounds that are added to water supplies. What is used as backflow prevention for drinking water?
Fire and explosion What is the precent of confined space deaths? Approximately 60% Why are there fans at the top of the cl2 building? Because wire will be damage/corroded by a cl2 leak A systems filtered water must comply with what turbidity standards? .3 NTUs or less in 95% of monthly samples, with none of them exceeding 1. NTU When do you apply a boil water notification?
- When the system pressure is below 20 psi
- Cl2 levels are low
- Water outages
- Repeated unacceptable microbiological samples If any of these occur you myst make a notification within 24 hrs to all connected systems What are the types of violations? Acute = 72 hrs Non-Acute = 14 days What are the requirements for a backwash?
6 to 10 ft loss of head Turbidities hit 1. 100+ hrs What should the backwash expansion of the media be? 30 - 50% CL2 residuals in the far reaches of the system should be? .2 free or .5 combined What is the best for oxidizing, taste, odor, color, iron, manganese or organics in water? Ozone If you are over feeding CL2 what is noticed? Taste, odor, Di and Tri CL2, nitrification What are the advantages and disadvantages of a Free Chlorine disinfection system? Advantages: More powerful not affected by temperature Requires 10 minute contact time Disadvantages: May form Trihelomethanes
