1. Water System Infrastructure
Instructors mention that in this module, as part of distribution system infrastructure we will cover piping, valves, storage tanks, and hydrants
Presented by Dinah Foreman, CET
Communities Unlimited, Inc.
Workshop developed by RCAP/AWWA and funded by the USEPA
Developed by American Water Works Association with funds from the U.S. Environmental Protection Agency, Published 2015

2. Learning Objectives
Be able to describe key components of the water system
Determine how the key components can impact water quality
Be able to describe potential areas of water quality concern in your system
Consider ways to make improvements in the water system that may improve water quality

3. Components We Will Discuss
Distribution System Piping
Valves
Hydrants
Storage Tanks

4. Distribution System Piping
Different aspects of pipe networks can have impacts on water quality
Dead ends
Cross connections
Line breaks
Condition of the pipe

5. Dead Ends Effect on water quality Extended water age Other concerns
Increased DBPs
Decay of chlorine residual
Increased microorganisms
Other concerns
Positive RTCR samples
If there is a failure some customers will not have water service

6. Solutions to Dead Ends?
Loop dead end lines
Flushing

7. Dead End Solutions: Pipe Loops
Allows more than one way for water to get to different points of distribution system
Effect on water quality
Decrease water age
Potentially reduce DBP
Help maintain disinfectant residual
Potentially reduce microbiological concentrations

8. Dead End Solutions: Flushing
Flushing valves/systems
Flushing programs

9. Discussion Has anyone addressed a dead end in your system?
What water quality issue did you have?
What did you do?
Did it correct the problem?
What water quality parameters do you use to determine if a line has been flushed adequately?

10. Valves
Most commonly operated and widely dispersed components of distribution systems
Why do we install valves in the distribution system?
Isolate parts of the distribution system in case of leaks, maintenance, water quality issues and emergencies
Control flow and/or pressure
Release air that can accumulate in high points of the distribution system

11. Valves Most commonly types of valves
Flushing
Pressure regulating
Flow control
Isolation
Backflow prevention
Air release
Buried-under-the-pavement valves?
Are your valves accurately marked on the water system map?

12. Valves: Effect on Water Quality
Closed valves create dead ends in the distribution system
Stagnation
Increased water age
Biofilm development
Sediment built up
If opened or closed rapidly, water hammer can develop
Stirs up sediment
Line breaks

13. Valves: Solutions What can be done to limit water quality impacts?
- Survey valves to be sure they are open
- Exercise valves
- Open and close valves slowly

14. Why do we have hydrants in our Distribution System?
Fire protection
Flushing
To improve water quality
Caution – Opening and closing hydrants too quickly can cause water hammer

15. Hydrant Impacts on Water Quality
Flushing, scouring and cleaning (planned/unplanned)
Cross connection potential
Poor sampling points
Water can be trapped in the barrel of the hydrant when closed, resulting in unrepresentative samples

16. Storage Tanks Purpose? Improve system hydraulics Peak flow/fire flow
Balance treatment needs

17. Factors that Impact Water Quality in Storage
Increased water age
Stratification vs mixing
Inlet/outlet configuration
Formation of DBPs
Loss of chlorine residual
Microscopic critters in the water
External contamination
BIG critters in the water

18. What can be done to maintain or improve water quality in storage?
Reduce water age
Booster chlorination
Warning: Additional chlorination may increase DBPs
Inspection and maintenance of storage facility

19. AWWA recommends water age of less than 7 days
The residence time of water in the distribution system before reaching the customers
2 Days
Storage
Facility
4 Days
Water Supply
Customer
AWWA recommends water age of less than 7 days 19

20. Activity

21. Distribution System Components
Dead Ends
Storage Tanks
WTP

22. Where would you expect to find water with the greatest age?
Dead Ends
Storage Tanks
WTP

23. Where would you expect to find water with the greatest age?

24. EPANet Free Software from EPA
Software That Models the Hydraulic and Water Quality Behavior of Water Distribution Piping Systems
EPANET is software that models water distribution piping systems. EPANET is public domain software that may be freely copied and distributed. It is a Windows 95/98/NT/XP program. EPANET performs extended period simulation of the water movement and quality behavior within pressurized pipe networks.
If time permits, provide a demonstration of EPANet

25. Storage Facilities Inspections & Maintenance
Finished water storage not properly covered
Uncovered finished water storage prohibited
Cracks in the walls or storage cover
Storage facility not structurally sound
Accesses do not close properly
Vents & overflow pipes not protected with proper screen or other approved devices
Lack of normal maintenance
No inspection schedule for storage tanks

26. Loss of Integrity of Storage Facilities

27. Inside Storage Tank

28. At least 7 snakes At least 3 bloated mice
Courtesy Robert Clement, USEPA

29. Dead Frog
Dead Squirrel

30. Inspections & Maintenance
Inspection and maintenance
AWWA Manual M42 – Recommends every 3 years
MSDH requires that tanks be inspected every 5 years to receive credit for T2-3 on the annual water system inspection

31. Questions?