WATER DISTRIBUTION level 1 review questions and answers, Exams of Water Resources Planning and Management

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WATER DISTRIBUTION level 1 review

questions and answers

What the primary objective of water distribution operators - CORRECT ANSWER- deliver safe and pleasant drinking water to the consumers what should the distribution operator do if there is a complaint about the water? - CORRECT ANSWER-record the info and have the problem investigated and notify the person complained and what corrective was taken. Most accidents result from - CORRECT ANSWER-carelessness and negligence why are adequate and reliable records very important? - CORRECT ANSWER-to document the effectiveness of your operation an greater obligation rest with whom, and why? - CORRECT ANSWER-operators because of the great number who drink the water from the distribution system purpose of the a water storage facility? - CORRECT ANSWER-provide a sufficient amount of water to average or peak demand.,needs for fire protection, industrial uses and reserve storage where are storage tanks are found in the distribution - CORRECT ANSWER-closest to the users, where higher pressure are needed and where land is available. what signifies and standpipes? - CORRECT ANSWER-the height is greater than their diameter where are standing pipes are located? - CORRECT ANSWER-high ground and near well field or point in the distribution system why are stand pipes preferred over elevated storage? - CORRECT ANSWER-easy to maintain, more accessible safer and less objectionable from aesthetic viewpoint Hydropneumatic or pressure tank are used mostly in what type of plant? - CORRECT ANSWER-small system wells, they are pressure vessels caution with the pressures relief valve. hydropneumatic or pressure tank should have what amount of air to operate sufficient. - CORRECT ANSWER-2/3 or 1/3 air, otherwise cause the starting and stopping of the pumps causing damage. why should pressure tanks have a sight glass? - CORRECT ANSWER-to observe water to air ratio

what is an disadvantage of pressure tanks? - CORRECT ANSWER-not enough storage to meet demand in cause of power outage, and little time to do maintenance what are surge tanks? - CORRECT ANSWER-protect water line due too excessive surge pressure, also use to control water hammer and regulate the flow of water where should surge tanks be located? - CORRECT ANSWER-close as possible to activity that create water hammering. name procedure for storage operating a storage tank. - CORRECT ANSWER-fill all tanks during off peak hours, maintaining specified psi at critical points in distribution. Disadvantage of Variable speed pumps? - CORRECT ANSWER-Costly to operate. what normal operation procedure that can reduce cost? - CORRECT ANSWER-time-of day concept, pumps are only used during the off peak hours of electrical usage. 10pm- 6am what can eliminate taste and odor problems in a storage tank. - CORRECT ANSWER- periodally allow it to empty and be refilled. the purpose of altitude-control valve? - CORRECT ANSWER-prevent overflow from the storage tank, maintain a constant water level as long as water pressure in distribution is adequate. what is the simplest way to control level in storage? - CORRECT ANSWER-electrodes, but most problem arise when they are hard to reach and they get corroded. what is ultrasonic signals in storage tanks? - CORRECT ANSWER-transmitter sends a continues high-frequency to a receiver and when the water cover it the signal is broken. what are pressure switch in storage tanks? - CORRECT ANSWER-response to changes in pressure in the tank to control pumps what is the main problem with radio frequencies? - CORRECT ANSWER-bad weather and lighting cause voltage interferes or disrupts Name item needed to operate a centrifugal pump. - CORRECT ANSWER-impeller submerged in water, never operate until prime. what is JTU's - CORRECT ANSWER-Jackson turbidimeter is a Visual method 3 type of maintenance? - CORRECT ANSWER-preventive, predictive, and corrective

what's corrective maintenance? - CORRECT ANSWER-a problem already exist to be repaired how long should the outside or inside of painted pipes or tanks last? - CORRECT ANSWER-outside should last 5 yrs and 3-5 yrs. inside a tank. when is the best time to take out of service a storage tank in most cases? - CORRECT ANSWER-october - April two type of paints for refurnishing storage tanks. - CORRECT ANSWER-short life coating-protection for 6 yrs., long life-10yrs. before entering a tank what oxygen is safe? - CORRECT ANSWER-19.5-23.5 oxygen name some items that increase corrosion - CORRECT ANSWER-dissolve oxygen, carbon dioxide, dissolved minerals, salts. Electrical control of corrosion is - CORRECT ANSWER-Cathodic protection what is known as a corrosion inhibitor? - CORRECT ANSWER-any substance that promotes film formation on the surface to be protected, example: lime, soda ash, and caustic soda when pH is above equilibrium what coating is form? - CORRECT ANSWER-calcium carbonate to form on the surface protecting it from corrosion what chemical that is commonly used in corrosion control? - CORRECT ANSWER- Sodium Hexamethphosphate(polyphosphate) tie up a variety of ions what is the commonly used feed rate for polyphosphates? - CORRECT ANSWER-no more than 5 mg/L what is the key to a successful cathodic protection program? - CORRECT ANSWER- replacement of sacrificial anodes , inspected at least yearly(made of mg & zn) when spraying a tank how many people should be available? - CORRECT ANSWER- 1 in the tank and 2 backups people for assistance if emergency After chlorinating with 200 ppm of a tank, what is the procedure for filling it with water. - CORRECT ANSWER-let stand for least 30 minutes, fill with water with residual of 3. mg/L and let stand for 3-6 hours, then take BACT-T samples. what are other methods to disinfect a new tank? - CORRECT ANSWER-fill up tank with at least 10mg/L of water for 24hrs.

Name a stipulation concerning disinfecting a new tank? - CORRECT ANSWER-first time newly constructed tank, 50 ppm (instead of 3ppm) when placing a tank back in service for 24 hours. what disinfection method is used for different size storage tanks. - CORRECT ANSWER-tank over 100,000 gal. use gaseous chlorine, below 100,000 gal. us HTH when divers are used to inspect a tank what is the proper procedure? - CORRECT ANSWER-they need to be disinfected with 200 mg/L name procedures to prevent icing in storage tanks. - CORRECT ANSWER-flow rate into and out adjusted to allow circulation 50% variation within 24 hrs. or used air bubble to circulate water how often maintenance should be done on storage tanks? - CORRECT ANSWER- covered tanks every 3-5 yrs. and uncovered annually or twice a year. most booster pump are connected to service high elevation and controlled by? - CORRECT ANSWER-solenoid switch to altitude valve. what are regulator stations main function? - CORRECT ANSWER-reduce psi and maintain even acceptable psi down stream. what is excessive psi and what's normal psi in the system? - CORRECT ANSWER- 100 and 60- 90 how often should you operate and overhaul regulator station? - CORRECT ANSWER- once a month and inspected annually record of data, date of installation, start up data, failure, and service performed on equipment should be record on what? - CORRECT ANSWER-nameplate what type of ventilation is necessary storage facility - CORRECT ANSWER-force-draft Hydraulic transients are commonly called? - CORRECT ANSWER-surge, shock or water hammer the major hydraulic concerns of a water distribution system are - CORRECT ANSWER- whether water will flow, & in what direction water should be delivered with a working pressure of? - CORRECT ANSWER- 35 what would be the absolute psi in distribution system? - CORRECT ANSWER- 20 roughness inside a pipe is called? - CORRECT ANSWER-C-factor, high the factor the smoother the pipe

when do you will never used thrust block or kickers? - CORRECT ANSWER-when the pipe joints are fixed(welded) water hammer - CORRECT ANSWER-surges in the pipeline resulting from rapid increase or decrease in water flow. what are surge chambers? - CORRECT ANSWER-tank connect to the pipe to lessen the shock of water hammering in commercial districts what is the desired psi? - CORRECT ANSWER- 75 Minimum size pipe commonly used today? - CORRECT ANSWER-6 inches what is the absolute minimum size pipe installed? - CORRECT ANSWER-4 inches Dead end exceeding 1000 ft what should be the pipe size - CORRECT ANSWER-6" dead end exceeding 2000 ft. what should be the pipe size - CORRECT ANSWER-8" Valve in the distribution should be installed every - CORRECT ANSWER-1000 ft. hydrant in the distribution should be installed every - CORRECT ANSWER-500 ft. why type of material is commonly used in transmission lines - CORRECT ANSWER- concrete with steel cylinder where are distribution storage located? - CORRECT ANSWER-close as possible to the center of use. Ideally, the intake and outlet should be located where on storage tanks. - CORRECT ANSWER-opposite sides when a single reservoir is taken out of service the psi shouldn't be allowed to drop below? - CORRECT ANSWER- 20 what type of valve is install on the booster pump? - CORRECT ANSWER-check valve on the discharge side water distribution systems are laid out in - CORRECT ANSWER-grid, loop and tree(branching) most type of pipe layout? - CORRECT ANSWER-grid what is cathodic protection? - CORRECT ANSWER-electrical system for prevention of rust, and corrosion.

class of working pressure are commonly use? - CORRECT ANSWER-4, and 100,200,250 psi what causes shear breakage of water pipes? - CORRECT ANSWER-earthquakes what causes beam breakage? - CORRECT ANSWER-unevenly supported along it length min desirable pipe diameter is - CORRECT ANSWER-6 " pipes should certainly not be less than - CORRECT ANSWER-4" ductile iron pipe replace what type of pipe in water system? - CORRECT ANSWER- cast-iron pipe why used ductile iron pipe over cast-iron pipe? - CORRECT ANSWER-it will resist bending and twisting without breaking ductile iron is lined in the inside to prevent what? - CORRECT ANSWER-tuberculation- formation of small mounds of corrosion product. a lined pipe may have__________ the friction loss of an unlined pipe. - CORRECT ANSWER-1/ what can protect external pipe corrosion - CORRECT ANSWER-bituminous coatings, and polyethylene wrap when using concrete pipe what is the difference when it concern prestressed - CORRECT ANSWER-can withstand 250 psi and without stressed only 50 psi asbestos cement is immune to what? - CORRECT ANSWER-electrolysis can not tuberculate as do metal pipe. disadvantage of AC Pipe - CORRECT ANSWER-low flexural strength break when it is bent three types of plastic pipes general in usage? - CORRECT ANSWER-PVC, PE and PB, (pvc can reach up to 16") for pipes 24" or larger which pipe is recommended? - CORRECT ANSWER-reinforced concrete pipe what type of joints is most commonly used today? - CORRECT ANSWER-push-on(bell & spigot pipe)

steel metal pipe is susceptible to corrosion what is used to protect it? - CORRECT ANSWER-cement mortar,, cold applied mastic, or coal tar enamel. R/W stands for what? - CORRECT ANSWER-right of ways how to check for metal pipe damage? - CORRECT ANSWER-tap with hammer, if it doesn't ring or hum it is damage when installing pipe where should the pipe be laid down for proper installation? - CORRECT ANSWER-along the trench opposite of the excavated material when stacking up plastic pipe it shouldn't be exposed to sunlight for more than how many days? - CORRECT ANSWER- 30 water mains need at least ________ of cover over the top of the pipe - CORRECT ANSWER-30 inches trenches should be how wide for pipe installation? - CORRECT ANSWER-1 to 2 ft. wider than diameter of the pipe