Introduction to Water Distribution

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Introduction to Water Distribution

• Water Solutions Inc
• 2006
• Class 5 79 Slides

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Hydrants Meters

• Types of hydrants parts
• Hydrant inspection installation
• Meter types, reading testing
• Meter maintenance repair
• Backflow and Cross connection terminology, types
  locations
• Types of Corrosion monitoring systems

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Fire Hydrants

• Who maintains them?
• Mostly the water utilities
• Few communities the fire dept does.
• Fire Hydrants are for public protection.
• Failure to maintain and ensure operation can lead
  to the utility becoming liable for damage due to
  fire in event hydrant does not work.

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Fire Hydrants

• Placement of Hydrants
• Other uses of Fire Hydrants
• Flushing of water mains
• Flushing sewers
• Supply for street washers other municipal
  functions
• Water source for construction jobs

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Fire Hydrants

• Other uses of Fire Hydrants
• Hydrants on dead ends
• Hydrants on busy streets
• Hydrants in locations with high groundwater
• Everyone who uses hydrants should be instructed
  in their proper operation

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Fire Hydrants

• Hydrant operation
• Hydrants should only be placed on mains 6 or
  larger
• Mains must have a minimum pressure of 20psi
  during fire flow demand
• Hydrant operation can disturb sediments and
  increase customer complaints
• Hydrants should always be closed slowly to reduce
  water hammer

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Fire Hydrants

• Types of Hydrants
• Dry-Barrel Hydrants
• Wet-Barrel Hydrants
• Warm climate hydrants
• Flush Hydrants

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Fire Hydrants

• Dry-Barrel Hydrant
• Wet-Top
• Dry-Top
• Main valve and drain in base
• Main valve opens and fills barrel with water.
  When main valve is closed the drain opens (at
  same time as main valve closes) and drains
  hydrant barrel.

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Fire Hydrants

• Dry-Barrel Hydrant (page 160)
• (Valve Classification)
• Standard Compression
• Valve closes against pressure
• Slide Gate Hydrant
• Main valve is a simple gate valve
• Toggle (Corey)
• Valve closes horizontally and barrel extends
  below branch line

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• Wet-Top
• Operating rod or main rod stays submerged when
  barrel is wet
• Dry-Top
• Packing isolates threaded end of main rod from
  water when barrel is wet

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Fire Hydrants

• Dry-Barrel Hydrant (page 162) fig 6-8
• (Breakaway)
• Barrel designed to break on impact limiting
  damage to upper part of barrel. Operating rod
  also designed to break
• Minimizes costs and time of repairs.

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Fire Hydrants

• Warm Climate Hydrants
• Two part barrel (lower) is filled with water at
  all times with main valve at ground level to
  separate upper barrel
• No drain mechanism

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Fire Hydrants

• Wet Barrel Hydrants
• Barrel is filled with water at all times
• NO main valve, instead each nozzle has a valve.
• Cannot be used in areas that are subject to
  freezing
• Large water waste if damaged in traffic

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Fire Hydrants

• Flush Hydrants
• Entirely below ground
• Usually Dry-Barrel type
• Airport aprons Taxiways
• Pedestrian malls
• Other areas where above ground obstructions are
  undesirable or cause a safety hazard

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Fire Hydrants

• Fire Hydrant Parts
• Upper Section
• Nozzle or head of hydrant
• 5-sided operating nut usually at top of hydrant
• Cap or bonnet over barrel of hydrant
• Outlet nozzles
• Threaded bronze NAS Threads (may differ)
• (2) 2 ½ and (1) 4 ½ nozzles
• Cast iron nozzle caps with nut to match operating
  nut

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Fire Hydrants

• Fire Hydrant Parts
• Lower Section
• Lower Barrel, Main Valve and Base
• Lower Barrel carries water between base and upper
  barrel (conduit)
• Buried so connection between upper barrel is 2
  above ground.
• Main Valve
• Operating stem, resilient valve gasket other
  parts
• Base
• Cast Iron and houses valve assembly
• Flanged to connect to main

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Fire Hydrants

• Fire Hydrant Parts
• Auxiliary Valves
• Isolation Valve
• Allows isolation of hydrant for repair or
  maintenance
• Attached to flanges of Base (hydrant) and Main
  (supply)

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Fire Hydrants

• Fire Hydrant Inspection
• Inspection checklist to include
• Direction to open hydrant
• Counterclockwise and marked on hydrant open to
  stops
• Size shape of operating nut
• Depth of bury
• Distance to main below surface
• Size and type of inlet connection
• Did you get what you ordered
• Main valve size
• Outlet nozzle sizes configuration
• Nozzle thread dimensions

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Fire Hydrants

• Fire Hydrant Installation
• Installation considerations
• Location
• Set back 2 from curbing
• Pumper nozzle always faces the street
• Footing and Blocking
• Set on footing that will not rot or settle
• Must be plumb (perfectly vertical)
• Must be blocked to protect from movement thrust
  excavation to retain undisturbed earth for
  block
• Common to use two shackles to connect base to
  main
• Drainage
• Color

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Fire Hydrants

• Fire Hydrant Installation
• Testing
• Hydrants should be pressure tested separate from
  the main
• Open hydrant fully fill with water
• Vent air from hydrant
• Apply pressure, up to maximum of 150psi
• Check for leaks
• Repair or replace components that leak

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Fire Hydrants

• Fire Hydrant Operation
• Operated by (1) person with a 15 wrench
• Dry-barrel hydrant should always have main valve
  opened or closed 100
• Failure to do so will leave drain valve partially
  open and loss of flow/water will occur
• Main valves are not designed to throttle flow and
  should not be used to do so

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Fire Hydrants

• Fire Hydrant Maintenance
• Visual Inspection
• Listen for seat leakage
• Check mechanical components
• Actuate valve to test components
• Drain
• Operating Nut
• Preventative Maintenance
• Lubricate applicable components

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Fire Hydrants

• Hydrant Flow Testing
• As mains age and systems expand flow testing
  should be performed to
• Determine the need for additional feeder or
  arterial mains
• Determine the condition of the pipe schedule
  cleaning if necessary.
• Records should be kept of all hydrants

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Fire Hydrants

• Hydrant Safety
• Hydrants can cause injury or problems if
• The full force of the water comes in contact with
  persons
• Freezing temperatures and streams from hydrants
  can cause slick surfaces
• Pedestrians as well as traffic
• Potential cross connections to sewers
• Connected hoses must be secured or they may flail
  about and strike someone

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Water Meters
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Types of Water Meters

• Positive-displacement meters
• Compound meters
• Current meters
• Detector-check meters
• Proportional meters
• Venturi meters
• Orifice meters
• Pitometers
• Magnetic meters
• Sonic meters

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Water Meters

• Large-Customer Meters (Compound Meters)
• Large Customers Municipal / Industrial /
  Commercial
• Compound Meters
• Current Meters
• Detector Check Meters

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Water Meters

• Meter Sizing
• Expected maximum demand for year
• Pressure at point of connection
• Friction losses in service line, meter and
  plumbing
• Range of flow rates expected on service
• Meter typically installed one size smaller than
  the service
• Residential Meters
• Most are 5/8 or ¾ inch
• Commercial Meters
• Most are 1-2
• Flushometer toilets may require larger meter
• Meter guidelines

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Water Meter Installation

• General Considerations
• Not Installed in area where flooding w/
  non-potable water is a problem
• Up and downstream shut off for repair
• Horizontal installation
• Accessible
• Easy to read either visually or remotely
• Not a hazard to public
• Seals attached to register to prevent tampering
• Supported if larger installations
• By-pass or multiple meters on larger services to
  prevent discontinuation of service if repair is
  needed.
• BENEFITS OF A MANIFOLD

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Water Meters

• Manifold Installation
• Benefits of a manifold
• In a manifold installation all but one of the
  meters should have a backpressure valve on the
  outlet. This will allow subsequent meters to
  register only as flow increases.

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Water Meters

• Meter Connections
• Screwed (Up to 1)
• Flanged
• Meter Installation (indoor outdoor)
• Maximum and minimum heights
• Types of meters
• Access to meters
• Large Meter installation
• Supported
• Adequate work space 20 from vertical walls and
  24 of head space from highest point on meter
• Thrust Blocking if necessary

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Water Meters

• Meter Reading
• Gallons or Cubic Feet
• May have multiplier 10X or 1,000X
• Circular or straight
• Direct Readout (Problematic ?)
• Remote Reading
• Signal is pulsed to a remote totalizer
• Plug in readers
• Electronic meter reading (Scanning)
• Automatic meter reading

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Water Meters

• Meter Testing
• Testing Frequency
• Meters wear and may not register at low flows.
• Meter Test Procedure
• Run a variety of flow rates through meter to
  determine meter efficiency
• Pass known quantities of water through meter at
  various flow rates
• Meet accuracy limits on different rates

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Water Meters

• Meter Repair
• Dismantling the meter
• Cleaning the parts
• Inspection of parts for wear
• Replacing or repairing parts as necessary
• Reassembly
• Retest the meter
• Replacement vs. Repair
• Meter Records
• Installation / Repair History documented

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Water Meters

• Mainline Meters
• Current
• Proportional
• Venturi
• Orifice
• Magnetic
• Ultrasonic

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Cross Connection
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Cross-Connection Control

• Definitions
• Backflow
• Flow of any liquid, gas, or other substances back
  into a potable water system
• Backpressure
• Backsiphonage
• Cross-Connections
• Any physical connection or structural arrangement
  that would allow backflow or backsiphonage
  between a potable water system and any other
  water source or system to occur.

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Cross-Connection Control

• Public Health Impact
• Health impacts can result due to cross
  connections as a result of
• Improper design and construction of system
• Modifications to existing system and structures
• Cost cutting on plumbing and backflow devices
• Failure to test and repair backflow prevention
  devices

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Cross-Connection Control

• Public Health Impact
• Diseases attributed to cross-connections
• Dysentery
• Gastroenteritis
• Hepatitis
• Salmonellas
• Chemical contamination attributed to
  cross-connections
• Fertilizers
• Pesticides
• Boiler-chemical contamination

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Backflow Control Methods Devices

• If a cross connection is found it must be removed
  or proper backflow prevention devices be
  installed.
• Backflow Prevention Measures
• Air Gaps
• Reduced Pressure Zone Backflow Preventers (RPB)
• Double Check Valve Assemblies
• Vacuum Breakers (atmospheric and pressure)
• Barometric loop

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Backflow Control Methods Devices

• Air Gap
• Most effective and is accepted in all cross
  connection situations and for all degrees of
  risk.
• The gap between the supply outlet and the
  overflow of the downstream receptacle must
  measure (2) times the diameter of the outlets tip
  but no less than 1

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Backflow Control Methods Devices

• Reduced-Pressure-Zone backflow preventer (RPBP)
• Consists of (2) spring loaded check valves with a
  pressure regulated relief valve located between
  them.
• RPBP Devices should be maintained regularly

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Backflow Control Methods Devices

• Double Check Valve Assemblies
• Consists of (2) spring loaded check valves
• Not recommended where health hazard may result
  from failure.
• Double check devices should be maintained
  regularly

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Backflow Control Methods Devices

• Vacuum Breakers
• Intended to protect against backsiphonage but not
  back pressure.
• Check valve and vent open to atmosphere.
• Backpressure
• Barometric Loop
• Loop that is taller than 33.9ft feet (35 above
  the highest liquid level) and open to atmosphere
  will prevent backsiphonage.
• No longer installed because ineffective vs.
  backpressure.

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Backflow Control Methods Devices

• Other Methods
• Complete separation
• Often voided due to flexible temporary
  connections, swing connections and spool pieces.
• Responsibility for Cross-Connection Control
  programs may reside upon the water supplier.

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Cross-Connection Control Program

• State and local laws will delineate
  responsibility for program and its development.
• If the water utility does assume control of the
  CCC then it has authority to
• Take actions to protect the water supply
• Authority to locate, remove or protect all cross
  connections in the system
• Establish procedures for obtaining the
  cooperation of the public in its mission to
  protect from cross connections.

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Cross-Connection Control

• Cross-Connection Control Program
• Records and Reports
• Records and reports are utilities insurance
  against litigation in event of a cross connection
• Water Customers have the right to know about
  cross connections or hazardous conditions that
  they may be exposed to. Information about cross
  connections should be made available to the
  public
• Inspections should be performed according to a
  schedule and the records and reports should
  reflect this schedule.
• Only qualified and authorized individuals should
  make periodic test and inspections on backflow
  devices and report on their findings.

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Distribution System O M
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Distribution System O M

• System Inspection
• System Inspections should be part of regular
  operation and maintenance schedule (All determine
  health of system)
• Fire Flow
• Loss of Head
• Check by isolating section and placing pressure
  gage at entrance and exit of line. Pressure drop
  is monitored
• Pressure
• Between 35 100 psi (20 psi minimum under fire
  flow)
• Checked at hydrant
• Leakage
• Isolation of sections of main and pressure drop
  indicates leakage
• Chemical bacteriological Tests
• Corrosion problems
• Quality degradation
• Taste and Odor
• Safe!

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Distribution System O M

• Lining Water Mains
• Cement Mortar Lining
• Sliplining
• Pulling or pushing a high density polyethylene
  pipe through main.
• Valves, tees, and services must be re-cut

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Distribution System O M

• Leak Detection
• Difference between all metered amount and amount
  pumped into system is known as unaccounted for
  water.
• Large Leaks
• Easy to find
• Small Leaks
• Difficult to find

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Distribution System O M

• Leak Detection
• Listening Surveys
• Acoustic devices (sound waves generated by
  escaping water)
• Mechanical Aquaphone and Geophone
• Electronic amplifiers
• Steps to perform a leak survey

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Distribution System O M

• Leak Detection
• Water Audit is a combination of flow measurement
  and listening surveys. (only good if meters are
  accurate)
• Step 1 24hr measurement of water entering
  system
• Step 2 Break system down into smaller areas and
  again measure 24hrs
• Step 3 Identify probable areas for leakage
  based upon surveys.
• Use ration of Minimum night rates (1000pm to
  600pm) to total consumption
• Residential ratios should be between .35 to .40
• Greater than .40 indicates probable leakage
• Step 4 Flows should be measured between 1000pm
  and 600am. Unusually large flow rates should be
  sounded
• Step 5 Repair Leak
• Step 6 Check flow into area again to determine
  additional leaks or if problem is resolved.

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Distribution System O M

• Flushing
• Cleaning
• Emergency Repairs
• What to do in the event a major leak is reported

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Distribution System O M

• Emergency Repairs
• Excavate
• Needed Equipment cont.
• Pipe cutters/saws
• Repair clamps, couplings and sleeves
• Air compressor (for asphalt demolition
• Generator lights
• Safety Ropes PPE
• Leak Repair
• Section pipe
• Clamp or coupling
• Restoration
• Site restored to original condition
• Record Keeping
• Maintained for future reference

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Corrosion
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Types of Corrosion

• Internal Corrosion
• Pipe Coating, internal and external
• phosphate treatment
• pH adjustment
• External Corrosion
• Soil analysis
• Coating or wrapping of pipe in trench
• Alternative materials (PVC or PE)
• Cathodic Protection on Pipe
• Galvanic Corrosion
• Dielectric Couplings
• Replacement
• Stray Current corrosion

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Corrosion Prevention

• Cathodic Protection
• Sacrificial Anodes
• Galvanic anodes- magnesium or zinc castings that
  are connected to the pipe through insulated lead
  wires.
• Impressed Current
• External DC power source to make the pipe
  cathodic with respect to a bank of graphite or
  cast iron rods connected as anodes.

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System Corrosion Monitoring

• 1. Langlier Index
• Calcium carbonate saturation indices do not have
  any significant predictive value for the
  corrosion and leaching of lead, zinc, and copper
  from services.
• The langlier index is a common index used for
  corrosion protection of pipe by a thin film of
  CaCo3 on the interior of pipes

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System Corrosion Monitoring

• 2. Coupon Stations
• Representative locations in your system
• 3gpm flow
• 3 metal types (representative of system)
• Semi- or annual inspection of coupons

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Coupon Station
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