Water Distribution Exam Questions and Answers 100% Correct, Exams of Water and Wastewater Engineering

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Water Distribution Exam Questions and

Answers 100% Correct

Which is not a type of water? - ANSWER-Apparent Which layer of a lake is considered nutrient poor? - ANSWER-Hypolimnion (Bottom Layer) Copper Sulfate (Blue Stone) is used in lake management to? - ANSWER-Control Algae Bloom The Surface Water Treatment Rule requires that - ANSWER-3-log removal 99.9% for virus,4-log removal 99.99% for virus TDS (Total Dissolved Solids) levels of 1000mg/L is considered? - ANSWER-Unfit for human consumption An "Appropriate Right" is defined as what type of " water use" right? - ANSWER- Beneficial Use Right What are the acceptable and practical forms of public notification for most water systems for acute violations? - ANSWER-Mail, Newspaper, Radio broadcast A "Transmission Main" is a water main that - ANSWER-Is normally large in size , has very little service connections What well measurement must be known to calculate the specific capacity for a well? - ANSWER-Draw down and discharge capacity A map containing the size, location, and ties of water mains; valves; hydrants; tanks; and reservoirs is called a? - ANSWER-Comprehensive map Under the " Safe Drinking Water " act , Lead Free means? - ANSWER-Provided the use of lead in the system meets certain percentage levels When employees are working in trenches requiring a means of escape (such as a ladder or steps) exits must be located no further than? - ANSWER-25' apart A water audit consists of the following techniques? - ANSWER-Using standard accounting principles to determine the cost of water loss Conducting field test with work crews to gather information on leaks Using listening devices and flow measurements

Testing meters for accuracy A device used to check flows in a distribution system is called a - ANSWER-Pressure gauge Generally, a hydrant log should be kept whenever a hydrant is taken out of service. At a minimum the log should include - ANSWER-Date and time when it was placed out of service, Name of party contacted, Date and time when returned to service The type of hydrant that has a wet-top, where-by, the threaded end of the main rod and opening nut are not sealed from water when the main valve is open is the - ANSWER- Dry-Barrel hydrant Standard "pumper-connection" fire hydrants should not be installed on water mains smaller than...... - ANSWER-6 inches in diameter The type of corrosion caused by the use of dissimilar metals in a water system is .........

• ANSWER-Galvanic Series In the distribution systems FLOWS should not exceed.... - ANSWER-3.5 feet per second The " Nutating Disc" meter is classified as a ....... - ANSWER-Positive- displacement meter A direct water connection to a boiler containing a highly corrosive scale prevention compound must be protected by a (an)..... - ANSWER-Reduced Pressure Principal A cross-connection is defined as a connection between - ANSWER-A potable and non- potable water system An "Air Gap" technique is used to ......... - ANSWER-Prevent back-flow of non-potable water into the drinking water supply An approved device to prevent back-flow and back-siphonage is a ....... - ANSWER- check-valve A tank containing industrial solvent is under constant pressure. An employee accidentally opens a valve that is connected to the potable water system. Pressure in the tank forces the solvent into the potable water system. This is called........ - ANSWER-Back pressure

What is the one major difference between a "Double check" DC and a "Reduced Pressure" RP device? - ANSWER-An RP is used for toxic substances and a DC is used for Non-toxic substances A cross connection prevention program is - ANSWER-the responsibility of the water utility SPADNS is a reagent used in the analysis of - ANSWER-Fluoride What is an example of an "Acute Violation" - ANSWER-Occurrence of fecal coli-form/E.Coli Violation of the MCL for Nitrate What is the primary role of a State that has accepted primacy which means accepting guidelines at a state level to a local level - ANSWER-Implementing the requirements of the state drinking water program Which is not a class of public water systems covered by the "Safe Water Drinking Act"?

• ANSWER-Transient ,community water systems How many service connections or persons must a water system have for at least 60 days or more annually to qualify as a public water system under the SDWA? - ANSWER-15 connections or 25 persons If a water system fails to conduct the required water quality analysis , i.e. bac-t's , what action will the state generally direct the system to take? - ANSWER-Provide public notification There are several factors that affect the accuracy of a meter. Even something as simple as location can have an effect due to - ANSWER-Turbulence The type of hydrant that has valves located at each individual outlet is called - ANSWER-wet-barrel A compound meter consists of both a large turbine meter and a small bypass meter. The bypass meter will usually be of the Positive Displacement Type - ANSWER- After a water main has been depressurized for repairs the operator should? - ANSWER- Flush the line , collect special bac-t samples,and return to service CAL-OSHA considers an open trench of ___ or deeper a possible hazardous atmosphere condition - ANSWER-4 feet CAL-OSHA requires tool-box, tail-gate meetings to be conducted a minimum of ______ days for field workers - ANSWER-10 days

The minimum height for delineation type poles for traffic control is..... - ANSWER- inches The pH scales range from - ANSWER-0 to 14 Which of the following are considered physical characteristics of water - ANSWER- Color, odor,taste,temperature and turbidity A __________is a instrument for measuring and comparing the turbidity of liquids by passing light through them and determining how much light is reflected by the particles in the liquid - ANSWER-Turbidi-meter A well that provides drinking water to a school in a rural area with less than 15 service connections is classified as a? - ANSWER-Non-transient non-community water system Which of the following is a AWWA C-651 water main disinfection method for disinfecting the interior walls of water mains - ANSWER-50 ppm/24 hrs Sewer lines should be separated from potable water mains by at least ___ vertical and ____ parallel - ANSWER-1 foot/ 10 feet Which of the following is not used as a line valve in water system? - ANSWER-Rising stem gate Which of the following microbiological organisms is a protozoa? - ANSWER-Giardia Lamblia Back siphonage and back pressure in water systems can cause reverse flow conditions, which assembly is not used both the above condition? - ANSWER-Atmospheric Vacuum Breaker Minimum recommended set-back for a hydrant to curb face is? - ANSWER-2 feet A class "D" type fire involves : - ANSWER-Metal A theoretical line measured from the center line of a water main is called a? - ANSWER-Spring Line The lower the C-Factor, the __________ the inside the pipe - ANSWER-rougher The tensile strength of pipe material is the ability to - ANSWER-Stretch or pull without breakage The flexural strength of pipe material is the ability to - ANSWER-twist or bend without breakage

The AWWA recommended water flushing velocity for bio-film removal is - ANSWER- fps> Which end of a water main is fitted with an O-ring or gasket to make water tight seal? - ANSWER-Bell-end What is not used to determine the size of a water main? - ANSWER-Area of property A theoretical line connecting two water surface elevation together is called the - ANSWER-Hydraulic grade line A small piece of metal cut from a metallic water main examined for corrosion is called a? - ANSWER-Corrosion Coupon Black stains on plumbing fixtures can be attributable to - ANSWER-Manganese Red water stains in a water system can be attributed to - ANSWER-Ferric Iron When certain organic precursors (humic and fulvic acids) and chlorine combine together in water during disinfection, by-products can be formed. These organic by-products are called? - ANSWER-Trihalomethanes An indicator organism commonly used to determine drinking water contamination is - ANSWER-Coliform Bacteria Hardness is drinking water is mainly caused by - ANSWER-Calcium and magnesium Which of the following is responsible for a rotten egg odor in water - ANSWER-H2S The process by which plants give off moisture into the atmosphere is called - ANSWER- Transpiration Fluoride is applied to drinking water to - ANSWER-Help prevent tooth decay When pH increases, which of following chemical compound can precipitate a thin layer of (scale) on the interior wall of water mains - ANSWER-Calcium Carbonate An eccentric reducer on horizontal split case pumps is located on the - ANSWER- Suction side of the pump What is the (MCL FOR NITRATES) as nitrogen in drinking water - ANSWER-10 ppm A trench must be shored if it is __________ feet deep or deeper - ANSWER-5 feet but also depends on the soil condition

A portable ladder must extend _____ feet above the upper surface of an excavated trench - ANSWER-3 Feet Copper and lead found in drinking water is mainly due to - ANSWER-Customers plumbing Hard water caused by calcium and magnesium can - ANSWER-Increase soap consumption Oxygen levels should always be monitored while working in permitted confined space area. The oxygen levels for safe entry are? - ANSWER-19.5% low and 23.5% high the main purpose for adding sodium thiosulfate to bacteriological samples bottles is : - ANSWER-To neutralize any chlorine present in the water collected Which method is most commonly used to measure chlorine residuals in a water distribution system - ANSWER-DPD, colorimeter method Which of the following gases is called the silent killer? - ANSWER-Carbon monoxide Which pump is a positive displacement pump - ANSWER-Diaphragm Which type of Chlorine gas problem could be most dangerous to deal with? - ANSWER-Chlorine room fire any chlorine residual measured or remaining after the chlorine is applied to water using the DPD field method is called the? - ANSWER-Chlorine residual Chlorine containers commonly used at water treatment plants are equipped with fusible metal plugs as safety relief devices. These fusible metal plugs are designed to melt plugs are designed to melt at what range of temperatures - ANSWER-158-165 F Calcium Hypochlorite - ANSWER-*Is usually supplied as a tablet , granular or powder form *Is a chlorine compound used in hypochlorination *Can be stored for long periods of time in a dark, dry tank How many pounds of chlorine gas per day can be withdrawn from a 150 lb chlorine cylinder safely operating at normal room temperature? - ANSWER-40 lbs Which two acids are produced when chlorine is applied in water? - ANSWER- Hydrochloric and hypochlorous acids Which of the following disinfection methods provides the longest lasting residual in a water system - ANSWER-Chloramination

The maximum safe gas withdrawal rate from a one-ton chlorine cylinder at ambient temperatures, without freezing, is about: - ANSWER-400 lbs per day Which is not method used to disinfect new water mains? - ANSWER-Ultra Violet light Repaired mains, requiring de-pressurization, should be: - ANSWER-*Flushed *Disifected *Bacteriological sample A water main with a "C" Factor value of 90 is considered? - ANSWER-Slightly roughed If the water is being chlorinated to accomplish degree of treatment desired and to maintain the residual chlorine after a specific contact time , sufficient chlorine dosage must be added to satisfy the : - ANSWER-Chlorine demand Disease causing bacteria are called? - ANSWER-Pathogenic Large chlorine leaks may be easily identified by the human nose, but in order to detect small leaks an operator must use a solution of: - ANSWER-Ammonia hydroxide vapor The recommended minimum chlorine dosage applied to a well that is going back into service after repair is? - ANSWER-50 ppm Which part of a centrifugal type pump spins inside the pump case and converts velocity head to pressure head? - ANSWER-Impeller The purpose of adding more stages (pump bowls) to a deep well turbine pump assembly is? - ANSWER-Increase discharge capacity Excessive slip and/ or internal circulation inside a pump case can cause loss of efficiency due to? - ANSWER-Excessive leakage through the wear rings Which is NOT a positive displacement pump? - ANSWER-Centrifugal Which type of valve can be used for a tank level control? - ANSWER-Altitude valve A transducer is a mechanical device that? - ANSWER-converts mechanical energy to electrical proportionally using 4-20 mA