Ohio AWWA Southeast District Fall Meeting
Dealing with High Water Age in a
Water Distribution System
Thursday, November 21 , 2013
Dan Barr, PE
Introduction
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What is water age?
Why do we care about it?
What causes it?
What can we do about it?
What can we do about it’s
effects?
What is Water Age?
Defined as the time period that a
particular unit of water is traveling in
the distribution system before it leaves
that system.
What is Water Age?
• Normally measured in hours or days through
water quality computer modeling
• Cannot be directly measured
• Can be indirectly measured
Why Do We Care About It?
Surface Water
• High Disinfection Byproducts
• Low Chlorine Residuals
Ground Water
• Pipe Corrosion
• Color
• Low Chlorine Residuals
Why Do We Care About It?
What is too old?
11
10
9
12
1
2
3
8
4
7
6
5
Why Do Systems Have High Water Age?
Fire protection requirements increase water age
Pipe Volume (per mile)
Pipe Diameter
Gallons
2”
4”
862 3,466
6”
8”
10”
12”
18”
7,755
13,786
21,540
31,019
69,792
Larger pipes and storage for fires has a significant
effect on water age especially for smaller
systems or pressure zones
Why Do Systems Have High Water Age?
Customer Usage has dropped
• Conservation
• Population and businesses leaving
• Seasonal variations
Why Do Systems Have High Water Age?
Sizing for future growth or customers
What Can Be Done to Lower Water Age?
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Proper storage sizing
Increased tank turnover
Rerouting flows
Flushing
Increase demands and pressure zone bleeders
Reduce piping
Eliminate dead ends
What Can Be Done to Lower Water Age?
A storage and pumping analysis should include:
 Distribution system capabilities during critical
conditions
 Current and future storage/pumping requirements
 District by district requirements
 Incorporates minimum turnover requirements
What Can Be Done to Lower Water Age?
This analysis determines the
minimum required storage
volume for each of the
following components:
 Operational (balancing and
turnover)
 Fire Protection
 Outages
The
Three
Components
of Storage
What Can Be Done to Lower Water Age?
Rerouting Flows
Involves closing valves to force water through
high water age areas. Watch shifting water age
problems to other places.
Water models can help
predict result
What Can Be Done to Lower Water Age?
Increased Storage
Turnover
• Simple pumping control
changes
• Pumps fill tank longer
What Can Be Done to Lower Water Age?
Tank mixing
• Active versus passive
• Helps reduce water temperature
• Reduces dead zones in tank
• Mixing old water
• Chlorine residual monitors
What Can Be Done to Lower Water Age?
Flushing
• Increased flow reduces water age.
• How much water will need wasted?
• Many situations require too much water to
be wasted.
What Can Be Done to Lower Water Age?
Increase Demands
• Add customers
• Move pressure zone boundaries
• Add bleeders
What Can Be Done to Lower Water Age?
Abandon or reduce piping
• Valve off piping
• Replace mains with smaller ones
What Can Be Done to Lower Water Age?
Eliminate Dead Ends by Looping
• Adds capacity and fire protection
• Expensive and easements required
What Can Be Done to Lower Water Age?
Computer models help by:
• Checking results before changes made
• Locate high water age areas without as
much sampling.
• Locate fresh water to help indentify
solutions.
What Can Be Done about its Effects?
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Tank aeration or air stripping
Chlorine boosting
Flushing
Corrosion inhibitors and water stabilization
Water main rehabilitation or replacement
What Can Be Done about its Effects?
Tank aeration or air stripping
• Can work well for certain THMs
• Does not impact chlorine levels significantly
• Simple designs
• Watch venting
What Can Be Done about its Effects?
Chlorine Boosting
• Remote low level sodium hypochlorite feed
• NO-DES flushing
What Can Be Done about its Effects?
Chlorine Boosting and Flushing
• Remote low level sodium hypochlorite feed
• Chlorine tablets
• NO-DES flushing
• Flushing
What Can Be Done about its Effects?
Corrosion Control
• Add inhibitors or increase dosage
• Change treatment to stabilize water
What Can Be Done about its Effects?
Water Main Rehabilitation or Replacement
• Material choices
• Diameter reductions
• Internal coatings
Recent Current Events
Summary Of The Reduction Of Lead In Drinking Water Act
And Frequently Asked Questions by US EPA on October
22, 2013
5. Q. Are fire hydrants subject to the lead free requirements
in section 1417(a)?
A. Information available to EPA indicates that fire hydrants
can be, and are, used in emergency situations to provide
drinking water when there are disruptions to the normal
operations of the drinking water distribution system.
Therefore, as a class, hydrants would not qualify for the
exclusion for pipes, fittings and fixtures used exclusively
for nonpotable services
Recent Current Events
Jury Finds Pipe Maker Defrauded Governments
A federal jury in California found on Thursday that the nation’s largest
maker of plastic pipe defrauded states and municipalities over a
decade by knowingly selling them defective pipe for use in their
drinking water, firefighting, irrigation and other essential public
systems.
Recent Current Events
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The jury’s decision entitles the states and municipalities
to be compensated for their losses by the manufacturer,
JM Eagle, a private company based in Los Angeles that
has 20 plants in the United States and Mexico.
The amounts are to be determined in the next phase of
the proceedings, a second trial under the same judge
but with a different jury.
The case was brought under a law that calls for triple
damages, plus additional penalties for each false claim
submitted to a body of government.
Conclusion and Summary
Any Questions?
Dan Barr
Cell 614-633-5029
[email protected]
www.linkedin.com/in/danbarratburgessandniple/
Water Distribution System Professionals
LinkedIn Group
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Dealing With High Water Age in the Distribution System