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B test material - TCEQ Class B Surface Water with Questions & Answers.
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B test material - TCEQ Class B Surface Water withQuestions & Answers
What is the most important factor affecting the useful life of service lines? - (correct answer) -It is the
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ability of the material to resist internal and external corrosion
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When does Suction Head exist? - (correct answer) -Suction head exists when the source of supply is
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above the centerline of the pump.
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What is Net positive Suction Head (NPSH) - (correct answer) -NPSH is the pressure under which water
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enters the eye of the impeller in a centrifugal pump. Insufficient NPSH is the main cause of pump
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cavitation
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Explain and expand on Chlorine Dioxide (what it reacts with, oxidizes, etc) - (correct answer) -Chlorine
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Dioxide is a gas used in small quantities to disinfect water. It does not react with organics to form
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THMs and HAAs. It oxidizes phenols, manganese, iron, sulfurous and organic compounds which aids in
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the removal of tastes and odors. It is a very effective bactericide and a superior virocide. It dies not
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combine with ammonia. Chlorine Dioxide MRDL is .8 mg/L and monitoring procedures are the same as
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for chlorine. The Chlorite MCL is .q mg/L and must be monitored daily.
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What is texas drinking water pH requirements? - (correct answer) -The texas drinking water
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requirements require a pH > 7.0 for the water treatment plant finished water. EPA requires that pH
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analysis be preformed within 15 minutes of the sample being caught.
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How does pH affect Chlorine activity? - (correct answer) -When chlorine is added to water it forms
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hypochlorous acid (HOCL) and hydrochloric acid (OCL). The hypochlorous acid is the effective
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disinfectant. At a pH of 4.0 there is 100% hypochlorous acid. At a pH of 11 there is 100% hypochlorite
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ion. At a pH of 7, the hypochlorous acid is at about 80% and the hypochlorite ion makes up about 20%
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of the chlorine content. The lower the pH is more effective chlorine is because you have more
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hypochlorous acid.
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What is meant by water stability? - (correct answer) -Stable water is defined as water that will neither
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deposit or dissolve a calcium carbonate film or scale. Since no water is stable indefinitely, chemical
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treatment of water usually is intended to produce water that is slightly scale forming without being
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liable to cause stoppages in small lines and services. Bayliss curve is the simplest determination of
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stability. The Langelier saturation index is also used.
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What/how are above ground tanks and piping protected from corrosion? - (correct answer) -Corrosion
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protection for above ground tanks and piping is prevented by: cathodic protection, use if protective
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linings/coatings, eliminating different types of metals in the distribution system, and treating the water
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with chemicals to make it less corrosive
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How do you tests fir alkalinity? - (correct answer) -The two tritiation methods of analysis are a standard
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acid to titrate a sample. The end point of the titration is determined by the following: an indicator that
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changes color at a certain pH, or potentiometric titration to end - point pH. Using either of the
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methods, a measured amount of sample is titrated with a standard sulfuric acid to a predetermined
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pH. Nomograph are a graphical form of determining alkalinity. If the pH, total alkalinity, temperature
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and total dissolved solids are known, any or all of the alkalinity forms may be estimated.
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,What is Turbidity? - (correct answer) -Turbidity can be described as a measure of the relative clarity of
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water. Turbidity is an expression of the optical property that causes light to be scattered and absorbed
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rather than transmitted in straight lines through the sample.
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What causes Turbidity? - (correct answer) -Turbidity is caused by clay, slit, finely divided organic and
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inorganic material. Other suspended matter and microscopic organisms can also cause turbidity. There
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is one approved method for running turbidity - the Nephelometric Method (NTU)
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What is chlorine Demand? - (correct answer) -The amount of chlorine used up to completely react with
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the water and its suspended or dissolve material
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What is chlorine residual? - (correct answer) -When all the demand of the water is met any additional
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chlorine produces a chlorine residual
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What is chlorine dosage? - (correct answer) -Demand plus residual is the chlorine dosage. Chlorine
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Dosage = Demand + Residual
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What determines rate of disinfection? - (correct answer) -Chlorine concentration and contact time
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determines the rate and degree of disinfection. If concentration increases, the time can be reduced; if
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concentration is reduced the time must be increased.
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How does temperature effect chlorine effectiveness? - (correct answer) -Chlorine effectiveness is
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greater at higher temperatures, up to the point that chlorine volatizes. At low temperature, chlorine is
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more stable, but disinfection time increases.
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Is removing turbidity important for disinfection? - (correct answer) -Turbidity must be removed to low
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levels by sedimentation and filtration to allow chlorine to contact pathogens.
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What happens to dissolved solids on contact with chlorine? - (correct answer) -Dissolved solids are
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oxidized on contact further reinforcing the importance of contact time.
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No residual is formed until reducing agents are destroyed. What are examples of reducing agents? -
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(correct answer) -Manganese, iron, turbidity, organic matter, ammonia, or nitrates
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What the 4 stages of the Chlorine Demand Curve chart? - (correct answer) -Stage 1: No residual is
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formed because inorganic demand destroys the chlorine. (Flat Line)
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Stage 2: Monochloramines are formed as chlorine combines with organics containing ammonia (rising
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curve). The chlorine to ammonia weight ratio at this point is 5:1. Combined and total residual
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increases, chloro-organics are formed.
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Stage 3: Increasing chlorine dosage (failing curve) to a chlorine/ammonia weight ratio of 7.6:1 destroys
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chloramines and chloro-organics. Combined decreases and free chlorine increases.
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Stage 4: Enough chlorine is added to reduce all demand. The combined residual remains the same, but
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free residual increases with dosage. This stage is called "breakpoint" chlorination. The chlorine to
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ammonia ratio of 10:1 satisfies all demand and disinfects the distribution system. ( second rising
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curve)
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What is the difference between free chlorine and combined chlorine (chloramines/chlorine-ammonia)
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systems? - (correct answer) -Free chlorine is more powerful than combined chlorine, but combined
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chlorine lasts longer.
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- combined chlorine requires a 60-minute detention time while free chlorine requires 10 minutes.
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-If combined residual is replaced by a free residual, less taste and odor in the water usuals occurs.
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- if combined residual is used : ph and temperature must be monitored closely and the residual
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, yi adjusted accordingly. For example, as the temperature decreases the combines residual must be
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yi increased. Free residual does not require such monitoring in the 6.0 - 8.0 pH range. Free chlorine
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yi residual concentration is not affected by temperature changes.
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What is the minimum chlorine residual at the far reaches of the system for both free and combined? -
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(correct answer) -Free chlorine residual = .2mg/L
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Chloramine (combined) residual = .5 mg/L yi yi yi yi yi
- Surface water systems should not exceed a maximum free chlorine or chloramine residual of 4 mg/L
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as a running average. Limiting residuals reduces disinfection byproducts such as trihalomethanes and
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haloacetic acids. These byproducts, consumed over a long period of time, may cause cancer.
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What are the proper techniques for chlorine cylinder storage? - (correct answer) -- secure the ton
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cylinders in a horizontal position and move with a lifting bar and hoist. Never roll them
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- 150lbs cylinders shall be chained to rigid support and keep capped unless in use.
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- Check all chlorine systems for leaks before putting into service with a 10% ammonia solution.
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Household ammonia is not approved. When ammonia contacts chlorine gas white smoke results.
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What are the steps to do before entering a room with a chlorine leak? - (correct answer) -1: notify other
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operators and have standby help for possible notification of emergency personnel
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2: Be trained in emergency procedures and have knowledge of chlorinators, tools, and ammonia use.
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3: Put on a self-contained breathing apparatus (SCBA)
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4: wear a safety harness and lifeline
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What is the maximum withdrawal rate for 150lbs chlorine cylinders? - (correct answer) -The maximum
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sustained gas withdrawal rate for 150lbs cylinders (vacuum transmission) is 1lbs per day per degree F.
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The equivalent rate for ton cylinders (vacuum transmission) is 8 lb per day per degree F.
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Pressure transmission rates are 42 lbs per day for 140lb cylinders and 336 lb per day for ton
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containers, based on an air temp of 70 degrees F.
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What are chlorine cylinders equipped with to help/prevent gas leaks in extreme temperatures? -
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(correct answer) -Chlorine cylinders are equipped with a fusible plug designed to melt between 158
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and 165 f
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Is chlorine the most cost effective and best disinfectant product? - (correct answer) -Yes
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Chlorine is available is what three forms? - (correct answer) -Gas - 100%
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Solution - 5.25 to 15% chlorine (bleach) yi yi yi yi yi yi
Granular (solids) - 65 chlorine (calcium hypochlorite)
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Types of waterborne pathogens - (correct answer) -- typhoid
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- partyphoid
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- bacillary dysentery
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- cholera
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- campylobacterosis
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- legionnaires disease
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- infectious hepatitis
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- poliomyelitis
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- gastroenteritis
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