Tracer Studies in Distribution Systems by ssy92676

VIEWS: 19 PAGES: 16

									            Tracer Studies in
           Distribution Systems




Nick Pizzi
Vice-President
www.eetinc.com
        EE&T
ENVIRONMENTAL ENGINEERING & TECHNOLOGY, INC.




 Tracer studies

 • Allow us to characterize system dynamics
      – Can show thoroughness of mixing chambers
      – Can determine path and time of travel in
        conduits
      – Can help calibrate models
 • Require adding a substance to the water
     that is traceable
      – Could be a dye
      – Could be a chemical that is quantifiable




                                                   1
Plug vs. Mixed Flow

    3                           • Plug flow happens
    2                               when the chemical
                            C
    1                               does not disperse in
    0                               the chamber
                                •   Mixed flow happens
    3                               when the chemical
    2
                            C
                                    disperses quickly and
    1                               finds its way to all
    0                               parts of chamber




Chemical Tracers
• Added in a known quantity or dosage at a
    known time and duration
    – Time of first detection is important
• Should be captured in totality at the conclusion
    of study
•   Must not be reactive or consumable in system
    – Fluorides, Sodium, Lithium, conductivity
• Should be easily measured and provide
    adequate quantifiable differences in values




                                                            2
 Chemical Tracers - Fluoride

 • Fluoride is a regulated contaminant
   – MCL – 4 mg/L, SMCL – 2 mg/L
 • Fluoride is required in Ohio
   – Supposed to keep the fluoride at 0.8 to 1.3
     mg/L
   – Take care to request permission from Ohio
     EPA before you stop feeding it
   – Notify local health department of your actions




Tools for IDSE (SMP) Site Selection
 • Geographic information system (GIS)
 • Hydraulic models
 • Tracer studies
 • DBP data
 • Disinfectant residual data
 • Maps
 • Other tools
   – Simulated distribution system (SDS) laboratory
     test
   – System operating data (e.g., tank level)




                                                      3
                              TTHM vs. Time

             80

             70

             60

             50
TTHM, ug/L




             40

             30

             20

             10

             0
                  0   2   4           6       8   10   12
                                     Days




                                                            4
Case Study: Lake County, OH -
West System
• 20 MGD WTP – serves
    about 85,000 people
    – 10 MGD demand
• Three pressure
    districts
•   Surface Water – free                    Aquarius Treatment Plant

    chlorine
•   Conventional
    Treatment




Lake County System Case Study
• Problem                      • Solution
    – New IDSE sample             – Fluoride tracer study
      points needed –             – Shut off F- feed at
      justification needed          Aquarius Plant
    – Multiple pressure           – Sample strategically
      districts                   – Control the variables
    – Distribution system
      model available but         – Take additional DBPs
      water age needs             – Draw conclusions from
      verification                  data
    – No historical database      – Present evidence to
      available beyond the          USEPA
      compliance points




                                                                       5
Stage 2 DBPR
?   Results in further reduction and scrutiny of DBPs
    in distribution systems (peak locations)
?   Initial Distribution System Evaluation (IDSE)
    • Establish locations with greatest potential for DBP
      formation in DS
                    one-
    • Can perform one-year of monitoring (SMP) or can use
      calibrated WQ model (SSS) – most will use SMP
?   Compliance
    • Identify (using IDSE and Stage 1) and select new
      locations with highest potential for TTHM and HAA5
    • Achieve 80/60 LRAA for TTHM and HAA5 at these new
      locations (i.e., highest site establishes compliance)
                    evaluation”
    • “operational evaluation ”




                                             Low Service




                                        First High Service




                                         Second High Service




                                                               6
Water Age According to
        Model




               Note:
   sites in different pressure
   districts with similar ages.




Water age and HPC




                                  7
Sites for tracer study

• 29 sites chosen for
    study
    – Each pressure district
      represented
    – Sites chosen with
      water age and HPC in
      mind




Lake County Plant Tap Fluoride

• Fluoride feed                                    Plant Tap Fluoride Values


    stopped on 9/11 at                      1.10



    1000                                    1.00




•
                                            0.90

    Fluoride fed prior to                   0.80

    filtration                              0.70


•
                            mg/L Fluoride




    Filter washes                           0.60


    recycled fluoride for                   0.50


    awhile                                  0.40



•   Stable background
                                            0.30

                                            0.20

    levels met on third                     0.10

    day                                     0.00




                                                                               8
Fluoride at Low Service and High
Service Sites
• Low service area (close to                                         F at Selected Low Service Sites


    plant) loses fluoride
                                                             E340 Close to Stevens                    Will City Hall
                                                             Speedway 38700 Mentor                    Peach St Willoughby
                                                             Chagrin River Park                       Timberlake 11 Eastshore

    quickly                                           1.20


•   Dome and High Service
                                                      1.00




                                     mg/L Fluoride
                                                      0.80


    areas and tanks take
                                                      0.60
                                                      0.40


    longer
                                                      0.20
                                                      0.00
                                                                 1            2       3       4           5            6       7

    – Concentration factor of 3 is
      shown in 1st and 2nd high                                      F at Dome and High Service Sites


    – At 7th sampling event (5
                                                             Dome 91/84                               4399 River
                                                             Rogers Road                              2705 River

      days) Dome F is still > ½                              Winchester/Bishop Apts                   White Road Tank


      of start level                                  1.20
                                                      1.00


• F levels appear to support
                                      mg/L Fluoride




                                                      0.80
                                                      0.60


    model predictions at                              0.40
                                                      0.20

    shorter times                                     0.00
                                                                1         2       3       4       5           6            7   8




Lake County Conclusions
• Tracer Study data supports model calibration
     – Longer times may be in question
• Water age is correlated to HPC and DBP data
• Some sites in differing pressure districts have
    same age
     – 1st and 2nd high service 3X F than that of low service
     – Operators report 33% turnover, but long residence
       time in Dome is seen
     – 1st and 2nd high about the same
• Lake County will make improvements to Dome




                                                                                                                                   9
Case Study: CWD System
• Problem                       • Solution
   – Low Cl2 residuals in         – Fluoride tracer study
     portion of transmission      – Shut off F- feed at
     mains                          Crown and Morgan,
   – Low flow demands               increase at Baldwin
   – Water Age unknown            – Sample strategically
   – Suspected biofilm            – Control the variables
     issues                       – Draw conclusions from
   – Distribution system            data
     model not suitable for
     this arrangement




Cleveland System layout
        15 miles


                   Morgan WTP
Crown WTP
                                              Nottingham WTP




                                               Baldwin WTP




                                              Study area
Parma Res




                                                               10
Cleveland, OH - Indy/Brecksville System
• System supposed to move
   water from Indy to Brecksville
    – Not known
• Oversized Components
• 24 inch and 12 inch mains – 4
   miles
    – 620,000 gallons in the mains
• Indy is 3 MG – Brecksville is
  .75 MG
• Pumps at Indy – 3 @ 3 MGD, 1
  @ 4.5 MGD
• Mostly residential use along
  the way
    – 1.3 MGD demand
    – Low velocity
        • Supports expectation of low
           Cl2 residuals and biofilm




                                             Indy Pump
                                            and chlorinator




                              Brecksville
                                Tower




                                                              11
                Indy Pump and chlorinator




                    Brecksville Tower




Indy / Hypo added


                    24 inch Main




                    Interconnects




                    12 inch Main




                                            12
Tracer Protocol
• Winter Test Period              • Summer Test Period
   – Brecksville Tank O.O.S. –       – Brecksville Tank in service
     bleeders open                     – bleeders open
   – Indy Pumps operating as         – Indy Pumps operating as
     normal – Hypo added               normal – Hypo added
   – Shut off fluoride at Crown      – Shut off fluoride at Crown
     – Morgan                          – Morgan
   – Increase Fluoride at            – Increase fluoride at
     Baldwin                           Baldwin
   – Sample each day at Tanks        – Sample each day at tanks
     and selected sites                and sites
   – Observe data                    – Shut bleeders after
                                       equilibrium
                                     – Continue sampling
                                     – Observe data




Blowoff at Metroparks




                                                                     13
                                                   Winter Period System Fluoride
                    Parma Eff1            Parma Eff2        Engle           P.V.             North Roy.           Blossom

1.40



1.20



1.00

                                                                            Indy Pump Fluoride Levels
0.80



0.60



0.40



0.20



0.00
 mg/L Fluoride




                                               Winter Period Sample Point Fluorides

                    Indy Pump    Sunoco        Citgo   Marathon     BP Station     Brecksville City Hall   Hose at Metroparks

                  1.60


                  1.40


                  1.20


                  1.00
  mg/L Fluoride




                  0.80


                  0.60


                  0.40


                  0.20


                  0.00
                                                                     Date




                                                                                                                                14
                                            Summer Period Sample Point Fluorides

                      Sunoco                1st Hyd Chestnut               2nd Hyd Chestnut   PV Hydrant
                      Citgo                 Wallings Hyd                   Marathon           Hose Drip at Eddie's
                      BP Station            Brecksville City Hall          Central School     Hose at Metroparks

                1.6


                1.4


                1.2


                 1
mg/L Fluoride




                0.8


                0.6


                0.4


                0.2


                 0
                                                                    Date




                  CWD Conclusions
                  • Will Indy Pump Station put water into Brecksville
                        system?
                          – Yes - If bleeders from 3rd high are off
                          – No – If bleeders are left on
                             • With bleeders on, 3rd high can push water back towards Indy
                             • Indy then must pump towards Parma
                             • Chlorine Residuals will not increase in Brecksville system as
                                 long as bleeders are open as they were in the study
                               • Chlorine residual in 3rd high service near Brecksville is low
                  • Is there a biofilm?
                          – Quite likely since there has been low chlorine in
                            system for some time
                  • On or Off, bleeders likely to cause WQ issues
                  • CWD will expend capital dollars to address




                                                                                                                     15
Conclusions

• Tracer studies assist utilities in choosing
  IDSE sample points
  – Tracer data verifies or calibrates model (water
    age)
• Tracer studies assist utilities in
  determining water quality issues related to
  hydraulics
  – Tracer data verifies flow path and time




                                                      16

								
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