Exam Review on Water Distribution PDF

Exam Review 2. Purpose of Water Distribution Operator and System A water distribution operator ensures that water is safely and efficiently transported from treatment facilities to end-users. They maintain system integrity, monitor water quality, control pressures, manage emergencies, and ensure r...

Exam Review 2. Purpose of Water Distribution Operator and System A water distribution operator ensures that water is safely and efficiently transported from treatment facilities to end-users. They maintain system integrity, monitor water quality, control pressures, manage emergencies, and ensure regulatory compliance. Definitions ​ Cathodic protection: A technique to prevent corrosion by making the pipe a cathode of an electrochemical cell. ​ Anode: The positively charged electrode by which the electrons leave a device. ​ Foot valve: A type of check valve installed at the bottom of a pump suction line, inside the wet well. ​ Turbidity: The cloudiness or haziness of a fluid caused by large numbers of individual particles. ​ Stand pipe: A vertical pipe which is part of the water distribution system, providing pressure and flow stabilization. ​ Clear well: A storage reservoir for treated water, providing contact time for disinfectants. ​ Surge/pressure tank: A tank designed to absorb excess water pressure to protect the system from damage. ​ Regulating station: A facility that controls and maintains water pressure within a distribution system. ​ C-factor: The roughness coefficient used in the Hazen-Williams equation to describe the friction loss. ​ Invert of a pipe: The lowest point on the inside of a sewer or drain pipe. ​ Spring line of a pipe: The horizontal line at the midpoint of the vertical axis of a pipe. ​ Service pipe: The pipe that conveys water from the distribution main to the building. ​ Tuberculation: The formation of small mounds of corrosion products (tubercules) on the inside of a pipe. ​ Priming of a pump: The process of removing air from the pump and suction line to allow water flow. 3. Difference Between Transmission Line and Distribution Line ​ Transmission Line: Transports water from the source or treatment plant to distribution centers. Larger diameter and higher pressure. ​ Distribution Line: Delivers water from distribution centers to end-users. Smaller diameter and lower pressure. 4. Water Storage Facilities ​ Purpose: Store water to meet demand fluctuations, provide fire protection, and maintain pressure.  ​ Types: Elevated tanks, ground storage tanks, reservoirs. ​ When to Fill: Usually at night when demand is lower. ​ How to Stop Filling: Use of altitude valves or float-controlled valves. ​ Types of Controllers: Altitude valves, float valves, pressure sensors. They work by detecting the water level or pressure and adjusting flow accordingly. 5. How to Start a Pump (Procedure) 1.​ Check all valves and connections. 2.​ Prime the pump (remove air). 3.​ Open the suction valve. 4.​ Open the discharge valve slightly. 5.​ Start the pump motor. 6.​ Slowly open the discharge valve fully. 6. Water Quality (Table 2.1) ​ Explanation: Water quality parameters include pH, turbidity, chlorine residual, hardness, etc. Each parameter has an acceptable range or standard. 7. How to Control Corrosion in a Water Storage Tank ​ Name: Cathodic protection and coatings (e.g., epoxy). 8. When Emptying a Water Storage Tank ​ Water Table: If the water table is high, tank buoyancy could cause it to float or shift. ​ Tank: Structural damage or instability could occur. 9. Storage Tank Maintenance ​ Paint Frequency: Generally every 5-10 years. ​ How to Paint: Clean the surface, apply primer, and finish with a topcoat. ​ Concerns: Weather conditions, surface preparation, environmental regulations. ​ Paint Issues: Ensure proper drying time, avoid contamination. 10. Cleaning a Water Storage Tank ​ Frequency: Annually or as needed. ​ Procedure: Drain tank, inspect for damage, clean interior surfaces, disinfect, refill and test water quality. 11. Corrosion Control for Water Storage Tank ​ Chemicals: Corrosion inhibitors like orthophosphates. ​ Cathodic Protection: Use of sacrificial anodes or impressed current systems. 12. Good Corrosion Control Program  ​ Features: Regular inspections, maintenance of coatings, use of corrosion inhibitors, cathodic protection, monitoring of water quality. 13. Confined Space Entry Procedure 1.​ Obtain entry permit. 2.​ Test atmosphere for hazardous gases. 3.​ Ensure proper ventilation. 4.​ Use safety harnesses and lifelines. 5.​ Have a standby person. 14. Chlorine Compounds ​ Calcium (65% Powder): Used for disinfection. ​ Sodium (5%-15% Liquid): Commonly used in water treatment. ​ Gases (100%): Used for large-scale disinfection. 15. Chemicals Used to Neutralize Chlorine ​ Sodium thiosulfate, sodium bisulfite. 16. When to Neutralize Chlorine ​ Before discharging treated water into the environment. 17. Problems with Cold Weather and Elevated Water Tanks ​ Issues: Freezing of water, pipe bursts, ice formation. 18. Records for Equipment ​ Importance: Track services, installation dates, and failures for maintenance planning. 19. Contamination of Water System ​ Causes: Cross-connections, backflow, breaks in pipes. ​ Consequences: Health hazards, need for boil-water advisories. 20. Security Around Storage Reservoirs ​ Measures: Fencing, surveillance cameras, alarms, regular inspections. 21. Types of Backup Power at Reservoirs ​ Options: Generators, battery backups, dual power sources. 22. Distribution Systems ​ Grid: High reliability, but more complex. ​ Looping: Reduces stagnation, improves water quality. ​ Dead Ends: Simplest, but prone to stagnation and water quality issues. 23. Types of Pipe ​ Materials: PVC, ductile iron, steel, concrete. ​ Sizes: Vary depending on the application. ​ Coatings: Bituminous, cement mortar, epoxy. ​ Joints: Mechanical, welded, push-on, flanged. 24. Best Backflow Prevention ​ Device: Reduced pressure zone (RPZ) valve, double check valve, air gap.