Water distribution practice exam #2 (D1- D2) (2022/2023) graded A+

Water distribution practice exam #2 (D1- D2) (2022/2023) graded A+ Which process converts ammonia to nitrite and nitrate? ✔✔Nitrification What is the maximum advisable rate of chlorine gas removal from a 150- pound cy ...

Water distribution practice exam #2 (D1- D2) (2022/2023) graded A+ Which process converts ammonia to nitrite and nitrate? ✔✔Nitrification What is the maximum advisable rate of chlorine gas removal from a 150- pound cylinder? ✔✔40 pounds per day What is a type of positive displacement water meter? ✔✔Nutating- disk meter What is a power-operated mechanism for opening and closing a valve? ✔✔Actuator What is required if a routine sample test positive for total coliform bacteria? ✔✔Take repeat samples Why is a grid layout better than a tree layout for a water distribution system? ✔✔Less dead-end mains What is the purpose of a reduced pressure principle assembly? ✔✔Prevents back-pressure and back-siphonage In general, at what depths is shoring required for a trench, if you're excavating in soil? ✔✔5 feet or deeper What occurs after breakpoint chlorination is achieved? ✔✔Free available chlorine residual is directly proportional to the amount of chlorine added What is used to automatically shut-off the flow into a tank when the water level reaches a predetermined level? ✔✔Altitude valve What would be used to find a chlorine gas leak, which produces white smoke when it reacts with this substance? ✔✔Spray ammonia solution vapor near leak What causes staining of plumbing fixtures? ✔✔Iron & manganese How long should you flush water before you collect a bacteriological sample? ✔✔As long as necessary to flush stagnant water from the service pipe What is the purpose of a surge tank? ✔✔Protect pipelines from sudden high pressure What is recommended if a chlorine gas cylinder is leaking? ✔✔Rotate the cylinder and turn the leak upwards What is the purpose of primary MCL? ✔✔To protect human health What problem could be used by water with a pH of 5.3? ✔✔Corrosión What is a common way to connect a new pipe to an existing pipe, while the latter is pressurized and in-service? ✔✔Wet tap or hot tap What impact would organics have on chlorine demand? ✔✔Increase chlorine demand What is dichloramine? ✔✔Combined chlorine residual What impact does tuberculation have on the interior of a water main? ✔✔Causes rough interior of the water due to corrosion What is used to neutralize chlorine residuals when collecting a water sample for bacteriological analysis? ✔✔Sodium thiosulfate What are electrodes and ultrasonic signals used for in a tank? ✔✔Monitor water level Which part of the water main should a new service tap be installed? ✔✔45 degrees from the top of the water main What is the purpose of a vacuumed breaker? ✔✔Prevent back siphonage Which type of valve is commonly used to isolate water mains during repairs to minimize service outages? ✔✔Gate valve Pumping water level - static water level = ✔✔Drawdown What is purple pipe used for? ✔✔Reclaimed water Where is the correct location to install an air release valve ✔✔Top of pipe What must be performed prior to entering a confined space? ✔✔Test for oxygen deficiency/enrichment, combustible gases, and toxic gases What does the C- factor of a pipe represent? ✔✔Roughness of pipe interior Why should you never empty an underground storage tank when the groundwater level is high? ✔✔It may float the tank and cause damage to the facility What is used to determine the bacteriological quality of a water supply? ✔✔Presence-absence of coliform bacteria Which valve is available as a swing, double door, or slanting disc? ✔✔Check valve What is used to check the effectiveness of disinfection? ✔✔Test for coliform bacteria ( bacteriological result ) What are used to protect water mains and ranks from corrosion? ✔✔Anodes What is a common customer complaint during or immediately after fishing the water main? ✔✔Cloudiness and color in water What is total dynamic head? ✔✔Total static head plus head loss, when the pump is operating What is a connection between potable water system and an unapproved water supply? ✔✔Cross connection What is tested in the field during the collection of bacteriological sample? ✔✔Test for chlorine residual Which type of water meter diverts some of the flow through a bypass meter, which is calibrated to register the total flow through the main pipelines? ✔✔Proportional meter What must be true if trihalomethane is detected in the water? ✔✔Disinfection by products have formed What causes a pump to sound like it is pumping rocks? ✔✔Cavitation What are the three most commonly used forms of chlorine for disinfection in the water industry? ✔✔Chlorine gas, calcium hypochlorite, and sodium hypochlorite What will reduce flow rate in a pipe? ✔✔Encrustation What is the source of E.coli? ✔✔Intestinal tract of warm blooded animals What is the primary purpose of a listening device? ✔✔Locate leaks What does a positive result from a presence-absence test indicate? ✔✔Biological problem Which part of a chlorinator is fitted with a Venturi nozzle, and creates a vacuum that moves the chlorine gas? ✔✔Ejector What should be installed on the pipeline if the flow changes directions? ✔✔Thrust block restraint What has the least impact to the disinfection capabilities of chlorine? ✔✔Hardness What is commonly used to protect the exterior of ductile iron pipe from corrosion? ✔✔Polyethylene encasement What causes water to appear red? ✔✔Iron What could be used to indentify the corrosiveness of water? ✔✔pH What will happen to the maximum flow rate from a chlorine gas cylinder if the temperature of the cylinder decreases? ✔✔It decreases What is a white tablet with a 65% available chlorine? ✔✔Calcium hypochlorite Which type of water storage facility has a height that is greater than its diameter? ✔✔Standpipe What is required if you cannot perform a bacteriological test within one hour of sampling? ✔✔Refrigerate the sample What causes scaling in the pipe? ✔✔Hardness Which valve has a movable disc that rotates on a vertical shaft to stop the flow of water? ✔✔Butterfly valve What will happen if the pressure in the water main drops below zero? ✔✔Back -siphonage Which of the Following is a buried valve that connects a water main to a service lateral? ✔✔Corporation stop What is one if the drawbacks of a dead-end water main? ✔✔You have to flush more What is required before a new water main is placed in a service? ✔✔Test for coliform bacteria A solution with a pH of 6 is a? ✔✔Weak acid What is required before discharging chlorinated water to the environment? ✔✔Dechlorinate the water What is the purpose of painting or coating the interior of a steel tank? ✔✔Minimize corrosion What is an approved backflow prevention device for a service connection that does not pose a health hazard? ✔✔Double check valve What used to add head to water and convey it to higher elevations? ✔✔Booster pumps Which standards are commonly used to disinfect a new water main? ✔✔AWWA If the organic concentration in a new water main increases, what is the impact to chlorine demand? ✔✔Chlorine demand increases What are the essential for killing harmful bacteria in water? ✔✔Adequate chlorine contact time and chlorine residual concentration If a tank has disinfected due to possible contamination, which of the following is true? ✔✔It cannot be returned to service until bacteriological test results show that samples tested negative for coliform bacteria What is used to prevent backflow into a pump? ✔✔Check valve What is the primary problem with installing a PVC pipe ( C-900 ) near a gas station? ✔✔Gasoline can permeate into the pipe What is a source of water main contamination that is unique to rural areas? ✔✔Septic leach fields What is formed when chlorine reacts with natural organic matter? ✔✔Trihalomethane ( THM ) An environment with the presence of free oxygen is known as? ✔✔Aerobic What could happen if the water pressure on the customers side exceeds the pressure in the water main? ✔✔Back-pressure What is always required after costing the tank interior? ✔✔Disinfection What is a process by which water vapor passed into the atmosphere from living plants? ✔✔Evapotranspiration What is installed at the top of a well to prevent contamination of groundwater from the surface? ✔✔Sanitary seal Safe access and egress such as a ladder must be located? ✔✔25 feet of a trench that is 4 feet or deeper What is a type of positive displacement pump? ✔✔Reciprocating or piston pump What is an underground layer of porous water bearing material from which groundwater can be extracted using a well? ✔✔Aquifer