Drinking Water Distribution System

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Drinking Water Distribution System - Civil Engineering

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  • DRINKING WATER DISTRIBUTION SYSTEM

    Class Lecture Package -2

  • WATER DISTRIBUTION SYSTEM

    Drinking water distribution system is a combination of components used to supply safe water to individual households

    It collects treated water from treatment plant Household plumbing systems are also part of

    distribution system

  • WATER DISTRIBUTION SYSTEM

    WTPTransmission

    Distribution network

    Elevated storage tank

  • COMPONENTS OF DS

    Pumping station Structural Electrical Pumping Piping

    Distribution storage Tanks Pipe Valve

    Distribution piping Pipes Valves

  • HYDRAULICS, PRESSURIZED FLOW

    It is the flow (full) that is passed through the pipes

    It needs the concepts of fluid mechanics and hydraulics to analyze the flow

    Full flow

    Partial flow

  • DESIGN OF PIPELINES

    The construction of pipes involve large costs Needs modeling/predicting the behaviour

    Experimental systems (model prototype) Numerical models

    Cost Time Safety Ease of modification Aid to communication

  • TYPICAL HEADLOSS DIAGRAM

    H

    EGL

  • HYDRAULICS,PUMP

    Pumps are integral components of a distribution system

    It supplies the energy needed

    Conditions and performance assessment is critical

    Pump system carve is typically used for design

    DischargeH

    e

    a

    d

  • HYDRAULICS, DS

    It uses the concept of pressurized flow Air bubbles can arise in the water Pipe breaks, leaks can cause variations in the

    hydraulic calculations It considers steady state flows Hardy cross method is typically used hydraulic

    analysis of pipe network

  • PIPELINE FRICTION EQUATION

    Hazen-William equation

    US unit

    SI unit

    V = velocity

    C = roughness coefficient

    R = hydraulic radius

    S = friction headloss

  • TYPICAL VALUES OF CPipe material Value of CPVC 135-150Steel (mortar lining) 120-145Steel (unlined) 110-130Ductile iron (mortar lining) 100-140Ductile iron (unlined) 80-120Asbestos cement 120-130Concrete 130-140

  • TYPICAL DISTRIBUTION NETWORK

    1

    2 4

    53

  • HARDY CROSS METHOD

    It is a widely used method to calculate hydraulic behavior of a pipe network Head loss can also be computed

    It is a trial and error procedure Very useful for large scale computation in computer

  • APPLICATION OF MODELS

    Model selection Network representation Calibration Verification Problem definition Model application Display/analysis

  • HYDRAULICS, STORAGE

    Storage is provided to ensure Reliability of supply Maintain pressure Improve operational flexibility and efficiency

    Floating vs pumped storage Location of storage is important for efficient

    use/supply of water

  • HYDRAULICS, STORAGE

    Tank levels Settling overflow level Identifying service area Identifying pressure zone

    Tank volume Fire and emergency storage demand

  • CORROSION

    Corrosion is a big concern for water distribution systems

    Typical three types of corrosion observed in distribution system Internal corrosion Microbial influenced corrosion Leaching

  • TYPICAL CORROSION IN DS

    Metallic MIC Leaching

    Metal Major Unknown Minor

    Polymeric none Unknown Major

    Cement based

    major Unknown Major

  • METALLIC CORROSION

    Both Internal and external corrosion are very common in metallic pipes

    Three conditions required Metallic surface An oxidant Medium to transport the oxidant to the metal

  • MIC

    It is caused by microbiological activity Some researchers feel biofilms protect metallic surface

    from natural corrosion Presence and structure of biofilms

    Hydraulic condition Nutrient availability Residual disinfectant Roughness of pipe

  • LEACHING

    Leaching is typically defined as the release of material to water without involving conventional corrosion processes

    Typical examples are metal bearing corrosion scales, monomers or calcium from cement matrix

    g00036829Highlight

  • FACTORS AFFECTING CORROSION

    Flow velocity Temperature pH Alkalinity Dissolved oxygen Total dissolved solids Hardness Bacteria

  • INDICATORS OF CORROSION

    pH, alkalinity and calcium concentration indicate the potential of corrosion

    Pipe inspection, analysis of pipe scales help to understand the potential for corrosion

    Many indexes used Langelier Saturation Index Aggressive Index Ryznar Index Driving force index

  • CORROSION CONTROL

    Controlling corrosion is a big challenge in water distribution

    The presence of different material in the same DS can bring additional issues to reduce the corrosion Corrosion control mechanisms can cause harm to

    some materials

  • CORROSION CONTROL

    Typical corrosion control techniques Corrosion inhibitors

    Orthophosphate Changes in water quality to reduce Lining on pipe surface/change pipe material

    The chemicals used during water treatment process can affect the effectiveness

  • CONTROLLING MIC

    Controlling MIC is basically controlling the formation of biofilms

    Changes in water quality helps in controlling microbial growth in biofilm

    Chlorine is not effective in destruction of biofilms Shock chlorination work at some materials

  • PIPE MATERIALS

    Pipe materials can play an important part in the quality and quantity of water in DS

    Pipes provides External and internal integrity of DS Interact with water quality

    There are many different types of materials used in distribution system

  • CAST IRON

    Historically, it is the most widely used material Lined unlined

    The use of cast iron pipes for new construction is virtually non existent Pipe break problems Water quality problems

  • GRAY CAST IRON

    It is an iron alloy centrifugally cast in sand or metal molds Large amount of carbon present Low melting point

    Installation of these pipes have stopped in early 1970s

    It has flat flakes

  • GRAY CAST IRON

    The flakes reduces its strength Brittle in nature, not elastic

    It is very weak in tension Two ways manufactured

    Spun cast pipes Pit cast pipes

  • TYPES OF FAILURE IN GRAY CI PIPES

    Wedge Splitting Spiral Cracking Corrosion Pitting Longitudinal Cracking Circumferential Breaks Bell SplitsVisit http://irc.nrc-cnrc.gc.ca/ui/bu/grayfailuretype_e.htmlTo see the details

  • DUCTILE IRON

    Due to various limitations and problems associated with gray cast iron, ductile irons are being used since 1960s

    Ductile iron is more elastic than cast irons It is made by adding small amount of magnesium and

    controlling the manufacturing condition It is also very common as a material for distribution

    system

  • STEEL

    Steel pipes are typically used for large diameter pipes Transmission pipes

    High strength, elastic and shock resistant It is relatively expensive It is more corrosion resistant than other iron

    based pipes

  • CONCRETE

    Concrete is inert, safe, long-lived and dependable

    Different types of pipes used Steel cylinder Prestressed Noncylinder Pretensioned

  • ASBESTOS CEMENT CONCRETE

    Source of durable and inexpensive piping Maintenance requirement is relatively high Many municipalities are looking for ways reduce

    the maintenance costs Replacement of failed pipes

    Due to environmental concerns, no new construction of AC pipes

  • PVC

    Polyvinyl chloride is the most commonly used material for construction of new distribution systems

    It is resistant to corrosion High strength to weight ratio Low historical information regarding its service

  • LINING

    Lining is very important to reduce the pipe water interaction in various distribution systems

    Low cost Long life Sustained smoothness Cement mortar lining common for iron pipes

  • LINING

    Lining thickness plays an important role in determining effectiveness

    It can be slowly attacked at soft water Coatings provides resistant to corrosion Leaching of cement mortar can be a concern in

    some places

  • HW-2 Review an article by groups

    Article review guideline is posted on ilearn The guideline is quite comprehensive. All the items may

    not be applicable for your particular review. Do what applies to you

    Everyone needs to review the articles themselves. The writing portion can only be shared by group members

    Conduct the review within 2 pages Due: will be discussed in the class

  • Articles for Review Chlorine dioxide disinfection technology to avoid bromate

    formation in desalinated seawater in potable waterworksBelluati, M.; Danesi, E.; Petrucci, G.; Rosellini, M. Source:Desalination, v 203, n 1-3, p 312-318, Febrary 5, 2007

    Copper pipe failure by microbiologically influenced corrosionCantor, Abigail F. ; Bushman, James B.; Glodoski, Martin S.; Kiefer, Eric; Bersch, Randy; Wallenkamp, Hank Source: Materials Performance, v 45, n 6, p 38-41, June 2006

    Effect of pipe corrosion scales on chlorine dioxide consumption in drinking water distribution systemsZhang, Zhe; Stout, Janet E.; Yu, Victor L.; Vidic, RadisavSource: Water Research, v 42, n 1-2, p 129-136, January 2008

  • Articles for Review Effect of chlorine on corrosion in drinking water systems

    Cantor, Abigail F.; Park, Jae K.; Vaiyavatjamai, Prasit Source: Journal / American Water Works Association, v 95, n 5, p 112-122, May 2003

    Options for recarbonation, remineralisation and disinfection for desalination plantsWithers, Anthony Source: Desalination, v 179, n 1-3 SPEC. ISS., p 11-24, July 10, 2005

    Disinfecting the Coquitlam water supply: Ozone and UV disinfectionLandis, Heather; Neemann, Jeff; Hulsey, Bob; Fiorante, Reno; Neden, Doug; Singh, Inder Source: Ozone: Science and Engineering, v 29, n 4, p 287-290, July 2007

  • SELECTION OF PIPE MATERIAL

    Service conditions Pressure Soil loads Corrosion potential of

    soil Corrosive nature of

    water

    Availability Local availability Experienced

    installation Sizes and thickness Compatibility with

    available fittings

  • SELECTION

    Properties of pipe Strength Ductility Corrosion resistance Fluid friction

    resistance

    Economics Cost Required life Cost of maintenance

    and repairs

  • PERCENTAGE OF PIPE MATERIAL USED

    Country CI DI AC Steel Plastic/PVC

    Concrete Others

    Canada 42 12 24 4 15 4 2US 46 11 20 1 14 2 3UK 81 10 2 6 1Germany 55 9 5 30 1Spain 30 50 4 15 1Netherlands 16 40 3 40 1

  • PIPES IN REGINA DISTRIBUTION SYSTEM

    The distribution system is composed of different types of materials

    The dominant material is AC Other materials used are Cast iron, PVC and

    Steel Most of the distribution system are constructed in

    the last 30 years

  • LEAD

    Lead as household plumbing 20% of all service connections in US have lead Lead as a plumbing material is also widely used in

    Canada Due to health concerns, there are no new

    plumbing done with lead

  • LEAD

    Lead based alloys are also used in plumbing Most of the existing lead connections are old Leaching of lead is common from household plumbing Changes in water chemistry play an important role in

    the leachability of lead pipes Corrosion inhibitors are used to reduce the leachability

    of lead

  • COPPER

    Copper is also very common as household plumbing Since 1963, 5.3 million miles of copper tubing

    installed in US households Also common in Canada

    Copper based alloys are also used in joints and plumbing systems

  • COPPER

    Copper also has leachability issues in water The leached copper can often goes through

    typical wastewater treatment processes End up in wastewater sludge Concern for disposal of sludge

    Flushing is often required in the morning before drinking water

  • PVC

    PVC is very popular as household plumbing material for new construction

    It has less corrosion problem than other conventional plumbing material

    PVC is considered to be inert with the changes in water quality

  • WATER QUALITY ASPECTS

    Water travels hours, or even days from the time it leaves the treatment to reach individual household Uncertainty of maintaining similar water quality in the

    distribution system There are different types of reactions occurred

    inside this large reactors

  • WQ ASPECTS

    Pipe material can interact with the water to change the quality Iron oxidation/reduction encourage the presence of

    iron and sulphate reducing bacteria (MIC) Cross connections can challenge the quality of

    water in the distribution system

  • WQ ASPECTS

    Water Distribution Systems Handbook

  • WATER TREATMENT CHEMICALS

    Four major sources of chemicals in water treatment Coagulants Disinfectants Corrosion inhibitors Oxidants for chemical oxidation

  • WATER TREATMENT AND DS

    The effect of coagulant types on the distribution system integrity has been explored limitedly

    The effect of disinfectants on the distribution system has been investigated in detail Chlorine is more corrosive on the distribution system

    than other disinfectants

  • WATER TREATMENT AND DS

    Corrosion inhibitors are typically effective on specific materials It may deteriorate other types of materials in the distribution

    system Zinc orthophosphate also increases zinc concentrations in

    water The effects of other chemicals on the quality of water

    are not explored in detail

  • WQ CHALLENGE IN DIFFERENT MATERIALS

    Water Distribution Systems Handbook

  • DISINFECTION

    Disinfectants serve two purposes Restrict microbial regrowth Protect from microbial intrusion from cross connection

    Disinfectant concentration decreases over time due to protection from microbes Microbes however grows in biofilms Reaction with organic

  • DISINFECTION AND DBP

    Disinfectants react with organic matter to form byproducts DBPs formed during water treatment process remain

    in water (depending upon DBP formation kinetics) The reaction to form DBP continues in the

    distribution systems

  • CHALLENGING INTERACTIONS

    Corrosion control, microbial inactivation and DBPs all interact with each other

    Optimization needed to manage these challenges

    Corrosion Control

    Microbial Inactivation

    DBPs

  • WATER QUALITY MONITORING

    Mechanism for identifying variations in water quality over time and space

    The resulting database can also be used to model the distribution system behavior

    Specialized monitoring can also support specific research objectives

  • WQ MONITORING

    Monitoring can be conducted in three different ways Laboratory based Real time monitoring Online monitoring

    Online monitoring is gaining popularity due to ease of operation

  • WQ MONITORING

    Routing monitoring Regulatory requirements Sampling methods Sampling parameters

    Synoptic monitoring Specific requirements

  • US REGULATORY LIMITS FOR WQ

    Water Distribution Systems Handbook

  • WQ, STORAGE

    Water quality can be affected in the storage Three different types of problems typically

    observed Chemical Microbiological Physical

  • CHEMICAL PROBLEMS IN STORAGE

    Loss of disinfectant residual Formation of DBPs Development of taste and odor Increase in pH Corrosion Buildup of iron and manganese Occurrence of hydrogen sulfide Leachate from internal coatings

  • OTHER PROBLEMS

    Microbiological Bacterial regrowth Nitrification Worms and insects

    Physical Sediment buildup Entry of contaminants temperature

  • MONITORING WQ IN STORAGE

    Routine monitoring Typical parameters Nitrification Sediment Biofilm

    Specialized monitoring can also be done based on the specific requirements

  • WQ, CONSTRUCTION & OPERATION

    Numerous factors can have an impact on water quality in distribution system

    Appropriate construction and operation practices can reduce the chances of WQ failures

    Most standard operating procedures take care of these aspects

  • DISINFECTION OF NEW PIPES

    Water mains are expected to be sterile in the construction site

    Disinfection chemicals Liquid chlorine Sodium hy...

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