Water Distribution Course Exam Quuestions and Complete Solutions

Water Distribution Course Exam Quuestions and Complete Solutions The minimum residual water pressure required by the Rules and Regulations for Public Water Systems (30 TAC Chapter 290 subchapter D) is _____. a. 40 psi at all times b. 20 psi under peak demand conditions c. 200 gallons per day 35 psi under peak demand conditions - Answer: b. 20 psi under peak demand conditions Dead end mains should be flushed every _____. a. day b. week c. month d. 4th of July - Answer: c. month Water hardness is caused by _____. a. suspended solids b. improper treatment c. too much chlorine d. calcium and magnesium salts - Answer: d. calcium and magnesium salts Transpiration is _____. a. the release of water vapor into the air by plants b. breathing c. dying d. moving water from one place to another - Answer: a. the release of water vapor into the air by plants The presence of nitrates in water can cause _____. a. typhoid b. cancer c. blue babies d. none listed - Answer: c. blue babies The federal agency that provides standards for the maximum allowable concentration of inorganic chemicals in potable water is _____. a. the Texas Department of Health b. the Environmental Protection Agency c. the Texas Commission on Environmental Quality d. the Texas Department of Water Resources - Answer: b. the Environmental Protection Agency The term "head" as applied to water pressure means _____. a. foam on top of the water in a tank b. the distance water must travel c. height in feet of the water column d. dynamic pressure - Answer: c. height in feet of the water column The four common classes of working pressure in water mains are _____. a. 100, 150, 200, and 250 psi b. 25, 50, 75,and 100 psi c. 50, 100, 150, and 200 psi d. 100, 200, 300, and 400 psi - Answer: a. 100, 150, 200, and 250 psi Surface load is _____. a. the weight of backfill on the pipe b. the protective finish on the pipe c. the weight of traffic on the pipe d. the weight of the pipe on the truck - Answer: c. the weight of traffic on the pipe Check valves on the discharge side of a pump _____. a. check on how much water is flowing through the pipe b. check on the water velocity c. stop the flow of water in case of flooding d. keep water from flowing back through the pump when it is shut off - Answer: d. keep water from flowing back through the pump when it is shut off How far do fire hydrants have to be, both vertically and horiontally, from any sanitary wastewater line? a. 3 ft b. 7 ft c. 8 ft d. 9 ft - Answer: d. 9 ft What is the capacity of elevated storage reservoirs required to maintain adequate water pressure according to the Rules and Regulations for Public Water Systems? a. 200 gallons per connection b. 100 gallons per connection c. 145 gallons per connection d. not listed - Answer: b. 100 gallons per connection Cathodic protection is _____. a. a method of purifying water by radiation b. a way of getting rid of rust inside the tanks c. an electrochemical means of preventing corrosion on tank surfaces below the water line d. using cathodes to disinfect the water supply in reservoirs - Answer: c. an electrochemical means of preventing corrosion on tank surfaces below the water line The most common type of pump used in a water distribution system is _____. a. centrifugal pump b. jet pump c. hydraulic ram d. positive displacement pump - Answer: a. centrifugal pump What is required to overcome the resistance to flow in the pipe and fittings? a. discharge head b. friction head c. velocity head d. horsepower - Answer: d. horsepower The meter most commonly used for residential customers is the _____. a. compound meter b. turbine meter c. positive displacement meter d. magnetic meter - Answer: c. positive displacement meter The meter that is accurate over wide range of flow is the _____. a. compound meter b. turbine meter c. proportional meter d. propeller meter - Answer: a. compound meter The spoil bank should be located _____. a. at least 2 feet from the edge of the trench b. at least 5 feet from the edge of the trench c. on the north side of the trench d. near the sidewalk - Answer: a. at least 2 feet from the edge of the trench Ninety percent of underground pipe failures are related to _____. a. faulty equipment b. defective materials c. inexperienced help d. improper backfill and lack of proper bedding - Answer: d. improper backfill and lack of proper bedding Unexplained water losses in a good system will not exceed _____. a. 10% b. 20% c. 30% d. 40% - Answer: a. 10% The process of placing a smaller diameter pipe inside a larger pipe instead of repairing the pipe is known as _____. a. stripping b. slip lining c. backfilling d. coupling - Answer: b. slip lining Responsibility for making water safe to drink and use rests with the _____. a. city manager b. TCEQ c. EPA d. operator - Answer: d. operator Heavy water use in summer can result in complaints about _____. a. stained laundry b. low water pressure c. damaged water heaters d. vandalism - Answer: b. low water pressure How many gallons per minute will flow in a 12 inch pipe with a velocity of 4 feet per second? a. 1057 b. 1200 c. 1410 d. 1585 - Answer: c. 1410 Using the formula 29.7 * d^2 * √Pr *CR = gpm calculate the flow from a hydrant with a nozzle opening 2.5 inches, 90% CR, and 81 psi. a. 1200 b. 1300 c. 1400 d. 1500 - Answer: d. 1500 How many gallons of water will a tank hold that is 30 feet long, and 20 feet wide, and 12 feet deep? a. 7200 b. 53856 c. 60048 d. 71440 - Answer: b. 53856 What is the efficiency of a pump if 2200 gpm are being pumped against 150 feet of head? a. 82% b. 83% c. 84% d. 85% - Answer: b. 83% What will detention time in hours for a tank that holds 450000 gallons and the flow is 850 gallons per minute> a. 529 hours b. 9 hours c. 445 hours d. 19 hours - Answer: b. 9 hours After a job completion, how many cubic yards of dirt will be hauled away from an excavation site with a trench that is 250 feet long, 42 inches wide 5 feet deep and has a 24 inch pipe installed inside it? a. 785 yards^3 b. 162 yards^3 c. 13 yards^3 d. 29 yards^3 - Answer: d. 29 yards^3 Neglecting friction, how many 6 inch water lines would be required to carry the same amount of water as one 12 inch line? a. 2 b. 4 c. 6 d. 8 - Answer: b. 4 Considering friction, how many 6 inch water lines would be required to carry the same amount of water as one 12 inch line? a.2 b. 4 c. 6 d. 8 - Answer: