Chester data evaluation report FINAL 6-27-19€¦ · FINAL REPORT Evaluation of Water Quality Data...

FINALREPORT

EvaluationofWaterQualityDataChesterWaterDepartment,ChesterMA

Preparedby:

RichardW.Gullick,PhDRCAPSolutions,Inc.

June27,2019TableofContents:

1. IntroductionandObjectives2. TreatmentSystem3. Methodology4. DrinkingWaterProduction5. Filtration6. PrimaryDisinfection7. SecondaryDisinfection(DistributionSystemChlorineResidual)8. pH9. DisinfectionByproducts10. Color11. LeadandCopper12. SummaryandConclusions13. Recommendations

1.IntroductionandObjectives:TheChesterWaterDepartmentoperatesacommunitywatersupplysystem(PWSID1059000)thatservesapproximately750peoplethroughapproximately252connectionsinthissmalltownlocatedinwesternMassachusetts.ThewatersystemrecentlyexceededtheallowableMaximumContaminantLevel(MCL)forthedisinfectionbyproduct(DBP)classknownastotaltrihalomethanes(TTHMs)forthreequartersinarow–thethirdandfourthquarterof2018andthefirstquarterof2019.TheMassachusettsDepartmentofEnvironmentalProtection(MassDEP)issuedaNoticeofNoncompliance(EnforcementNumber00005564)toChesteronDecember4,2018forthethirdquarter2018TTHMMCLexceedance,andaNoticeofNoncompliance(EnforcementNumber00006424)toChesteronMay3,2019forthefourth

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quarter2018andfirstquarter2019TTHMMCLexceedances.ChesterwasalsorequiredtocompleteandsubmitanOperationalEvaluationReportforexceedingtheOperationalEvaluationLevel(OEL)limitforTTHMinthesecondandthirdquartersof2018(perMassDEPletterdatedDecember4,2018).Inaddition,inaletterdatedAugust24,2018,MassDEPrequiredChesterto“prepareawrittenreporttoaddressthe2018color,turbidity,sourcewaterquality,anddisinfectionbyproductconcerns.”Thisreportpresentsthefindings,conclusions,andrecommendationsfromanevaluationofavailablewaterqualitydata,andisintendedtohelpsatisfytheaboveMassDEPrequirements.Thisevaluationincludesthewaterqualityparameterslistedabove,aswellasobservationsandrecommendationsrelatedtootheroperationaltopics.2.TreatmentSystem:Chester’swatertreatmentsystemiscomprisedmainlyofthefollowing,intheorderpresented:

1. PresentlythesourcewaterisfromHornPond,withtheAustinBrookReservoirservingasanalternatebackupsupply.

2. Slowsandfiltration–threeslowsandfiltersareavailable,andoneincludesalayerofgranularactivatedcarbonforremovingnaturalorganicmatter(NOM),whichisaprecursortoDBPformation.

3. Disinfectionwithfreechlorine–thisisaccomplishedinthethirdsegmentoftheclearwell(thewholeclearwellisavoidedtoreducechlorinecontacttimeandthusreduceDBPformation).

4. pHadjustmentusingsodiumhydroxide(NaOH),injectedjustaftertheclearwellandbeforethewaterleavesthetreatmentplant.

5. Disinfectionwithfreechlorine–thissecondstageofprimarydisinfectionisaccomplishedinthe~1,800-footpipelineleadingfromthetreatmentplantdownthehilltotheoldchlorinatorbuilding.ChorineisaddedatthetreatmentplantjustaftertheNaOHaddition,andtheresidualismeasuredattheoldchlorinatorbuilding.Enoughchlorineresidualistargetedtomaintainaresidualinthedistributionsystem(i.e.,secondarydisinfection).Forchlorinedisinfection,thepipelinehastheadvantageofahigherbafflingfactorthantheclearwell(1.0versus0.13,respectively),butthedisadvantageofahigherpH.

6. TheoldchlorinatorbuildingisconsideredtobethePointofEntry(POE)tothedistributionsystem.FinishedwaterturbidityandpHarealsomeasuredattheoldchlorinatorbuilding.

3.Methodology:Availablewaterproductionandwaterqualitydatawerereviewedforcalendaryear2018.MostofthedatawereobtainedfromtheMonthlyOperatingReports(MORs)thataresubmittedtotheMassDEP.TheMORswereobtainedfromtheChesterWaterDepartment.Flowandwaterqualitydatawereplottedtoidentifytrends,variousdatasetswerecomparedtoidentifypotentialcorrelations,andresultswerecomparedtothecorrespondingregulatoryrequirements(e.g.,MCLs)orotherwaterqualitytargets.Inaddition,adistributionsystemchlorineresidualmappingexercisewasconductedonMarch27,2019.

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4.DrinkingWaterProduction:Thequantityofpotablewaterproducedeachdayin2018ispresentedinFigure1.ThereportedpeakhourlyflowsforeachdayarepresentedinFigure2.

Figure1.Potablewaterproducedperday(1/1/18–12/31/18)

Figure2.PeakHourlyFlowforeachday(1/1/18–12/31/18)

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Thefollowingobservationsareevidentfromthewaterproductiondata:

• In2018,dailyflowsaveraged45,691gpd.Thehighestdailyflowwas109,328gpd,andthelowestdailyflowwas32,672gpd.

• Assumingapopulationsizeof750people,theaverageproductioncorrespondsto61gpdperperson,whichisveryclosetothenationalaverageof58.6gallonspercapitaperdayforresidentialcommunities(DeOreoetal.,2016).

• In2018,peakhourlyflowsaveraged49gpm.Thehighestpeakhourlyflowwas129gpm,andthelowestpeakhourlyflowwas32gpm.

• Theratioofaveragepeakhourlyflowtoannualaverageflowis1.5(49gpmvs.31.7gpm).• Thereweresomeperiodsofabnormallyhighflow,includinglateJanuary–earlyFebruary,and

againinOctoberandthenNovember(Figure1).Theselargeincreasesinwaterproductionappearattributabletoleakingpipesthatwerediscoveredandrepaired.Forexample,theJanuary/FebruaryissuewasapipebreakonEmeryStreetthatfilledabasement.

• Chesterusesthemeasuredvalueofpeakhourlyflowfordeterminingdisinfectionperformance,insteadofthealternatemethodofassumingavalueforpeakhourlyflowbasedontheaverageannualflowandapeakingfactor.Atypicalpeakingfactorusedis3.0,whileChester’smeasuredpeakingfactorisonly1.5.ItisrecommendedthatChestercontinuetousethemeasuredpeakhourlyflowinsteadofusingthealternatepeakingfactormethod,asinthiscasethatwouldtypicallyresultinlessdisinfectionbeingrequiredthanviathepeakingfactorapproach.Thiswouldbedisadvantageousonlyincircumstanceswherethereisanabnormalamountofflow,suchasduringamainbreak.

• Nounresolvedissueswereidentifiedregardingthewaterproductiondata.5.Filtration:TheChesterWaterDepartmentusesslowsandfiltrationaspartofthetreatmentsystem.Therearethreefilters,oneofwhich(Filter#3)hasagranularactivatedcarbon(GAC)layerbetweentwosandlayers(a“carbonsandwich”)forremovingnaturalorganicmatter(NOM),whichisaprecursortoDBPformation.Anywherefromonetothreefiltersmaybeoperatingatagiventime,dependingonflowrequirementsandimpactsfromfilterheadloss.DuringtheMarch27,2019sitevisit,Filter#2wastheonlyfilterinoperation.Turbidityhasbeenmonitoredforthefinishedwater,butnotforthecombinedfiltereffluent.TheturbiditymeteriscalibratedtwiceperyearbythesystemOperator(typicallyaroundJune1andduringtheDecemberholidays).

Forslowsandfiltration,theregulatoryrequirementsincludethefollowingtwoconditions(per310CMR22.20A(4)(b):

1. Atleast95%oftheCombinedFilterEffluent(CFE)turbidityreadingsinagivencalendarmonthmustbe≤1NTU(Nephelometricturbidityunit).Giventhatonlyonesignificantdigitisusedforthatlimit,thedatashouldalsoberoundedtoonesignificantdigit.Thismeansthatavalueof1.49NTUwouldberoundeddownto1NTU,andthatwouldmeetthelimit.Avalueof1.50NTUwouldberoundedupto2NTU,andthatwouldexceedtheallowablelimit.

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2. AtnotimecantheCombinedFilterEffluentturbiditybeabove5NTU(thusallowingupto5.49NTU,butnot5.50NTU).

Thefinishedwaterturbidityfor2018isplottedinFigure3(resultswerenotavailablefortheCombinedFilterEffluent).Thefollowingobservationsweremaderegardingthefiltrationoperations:

Figure3.FinishedWaterTurbidity

• Therequiredturbiditylimitsweremetthroughout2018.Theaveragedailyvaluefor2018was0.11NTU,andthehighestdailyvaluewas0.29NTU.Assuch,therewerenoresultsneareitherthe95%limitof≤1NTUnortheabsolutelimitof≤5NTU.

• Chesterhasbeencollectingthesamplesfortheturbidityanalysesfromthetreatmentplantfinishedwater(PointofEntry,orPOE).However,theproperlocationforsamplingturbidityforregulatorycomplianceisthecombinedfiltereffluentwater,beforeanyfurthertreatmentorchemicaladdition(referredtoas“filteredwater”in310CMR22.20A(4)(b)).Typically,filtereffluentturbiditiesarelowerthanfinishedwaterturbidities.RaisingthepHofthewatercancausedissolvedmetalstoprecipitateandthusincreasetheturbidity.Thefiltereffluentturbidityvaluesshouldbeusedforregulatorycompliancereporting,andforassessingtheoperationoftheslowsandfilters.

Chester’sOperatorreportedthattypicallythefiltereffluentturbiditiesarearound0.03to0.04NTU,asopposedtotheaveragedailyfinishedwaterturbidityof0.11NTU.WhencheckedonMarch27,2019,thefilteredwaterturbiditywas0.02NTUandthefinishedwaterturbiditywas0.09NTU.

• Chestershouldinstallsampletapsforallthreeindividualfiltereffluents(IFEs)andalsotheonecombinedfiltereffluent(CFE).ThereshouldbeanonlineturbiditymeterfortheCFEsample,andthatwouldbeusedfordeterminingthemaximumturbidityvalueforeachday.

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• TherewasanincreaseinfinishedwaterturbidityinAugust2018,andthenasecondspikeoccurredforalittleoveraweekinSept2018.However,themaximumturbiditywas0.29NTU,whichiswellbelowtheregulatorylimit=.Therefore,whiletheseturbidityincreasesarenotableforoperationalpurposes,thereisnoconcernrelatedtotheregulatoryrequirementsforturbidity.Thesystemoperatordoesnotbelievethatsourcewaterqualitywasacauseoftheincreasesinturbidity,andwonderedifafilterwasperhapsbroughtonlinepriortoitbeingcompletelyripened.

Theturbiditydatashowthefollowing(Figure3):• TurbiditystartedtoincreaseonJuly31,2018,reachedamaximumonAugust16-

17,2018,andthenstarteddecreasinguntilitreachednormallevelsaroundtheendofAugust2018.

• TurbiditystartedincreasingagainonSeptember6,2018,reachingamaximumonSeptember15,andwasthenbackdowntonormalbyaboutOctober1.

AnexcerptoftheOperator’slogbookforthattimeperiodisprovidedasFigure4.Itispossiblethatthefirstturbidityspikeiscorrelated,atleastinpart,toFilter#3beingtakenoffline.ThesecondspikestartsnotlongbeforeFilter#1wastakenofflinetodrainforcleaning,andpeakedonSeptember15,onlytwodaysbeforeFilter#1camebackonlineonSept.17.

Inthefuture,anyincreaseinturbidityshouldbeinvestigatedatthetimeitoccurs.ItisnotreadilyevidentfromtheOperator’sLogwhichfiltersareonlineatagiventime,thoughitappearsthatallthreewereonlinepriortothefirstturbidityspikethatstartedonJuly31,2018.Itmaybehelpfultotracksomewhatdifferentlywhichfiltersareonline.Figure5providesasampletemplateforatabletodothat,whichwouldmakeitsomewhateasierinthefuturetotryandcorrelatefilteroperationswithturbidityspikes.

Figure4.ExcerptfromOperator’sLogbook

Day Date Filter#1 Filter#2 Filter#3

?? ?? ONLINE ONLINE ONLINE

?? ?? takenOFFLINEat9:15am;drainingforcleaning

?? ?? PutbackONLINEat11:30am

?? ?? takenOFFLINEat9:15am;drainingforcleaning

?? ?? PutbackONLINEat9:30am

Figure5.SampleFilterOperationsLog

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6.PrimaryDisinfection:TheChesterWaterDepartmentusesfreechlorineforbothprimaryandsecondary(residual)disinfection.TheregulatoryrequirementsforprimarydisinfectionforthiswatersystemarebasedontheabilitytoinactivateGiardiacysts,andrequiresaminimumof1.0-logremoval(1.0log=90%removal,and2.0logs=99%removal).ThatremovalisafunctionofthepHandtemperatureofthewater,chlorineresidualconcentration,andchlorinecontacttime.Chester’streatmentplantusestwochlorinecontactchambersformeetingthedisinfectionrequirements.Thetargetchlorineresidualsareabout0.4to0.8mg/L.Therearetablesavailableinthetreatmentplantthatprovidesuggestedchlorineresidualsforavarietyofoperatingconditions(e.g.,differenttemperaturesandpH).NoattemptwasmadebyRCAPtoverifytheaccuracyofthatinformation.Thefinishedwaterchlorineresidualsfor2018areplottedinFigure6.

Figure6.FinishedWaterChlorineResidual

Thefollowingobservationsweremaderegardingthechemicaldisinfectionoperations:

• Therequireddisinfectionperformancewasmetatalltimesin2018.• Chlorineresidualsvarymorethanisdesiredformaintainingaconsistentwaterquality.Arange

of+/-0.2mg/Lor+/-0.3fromthetargetconcentrationwouldbeareasonablegoal.ItisrecommendedthatChesterinvestigatehowtomaintainamoreconsistentfinishedwaterchlorineresidual.

• Finishedwaterchlorineresidualwasconstantat0.3mg/LfromJuly11toAugust31,2018.ThesystemOperatorwasnotabletoprovideanexplanationforthisanomaly.

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• RCAP’scalculationoftheachieveddisinfectionperformancecalculationsconfirmedthatChesteriscalculatingdisinfectionperformanceaccurately(withinreasonablevariancesforroundingdifferences).However,thepartofthecalculationinvolvingthevolumeofthechlorinecontactorwasnotchecked.RCAPwasnotabletoobtainthespecificationsusedintheSCADAcalculationstodeterminethevolumeofthechlorinecontactors(partofdeterminingchlorinecontacttime),andthuscouldnotconfirmthisaccuracy.Itisrecommendedthatthisinformationbeobtainedandreviewedforaccuracy.

• Abafflingfactorof0.13isusedforthechlorinecontactchamber.ThesystemOperatornotesthatthiswasdeterminedviaatracerstudyconductedwithassistancefromtheMassachusettsRuralWaterAssociationandalsoMikeMcGrathofMassDEP.Nodocumentationofthistracerstudywasavailable.Thetracerstudyreportshouldbelocatedandfiled,andalsoperhapsbesubjecttoareview.RCAPSolutionsisavailabletoconductthatreviewifsodesiredbytheChesterWaterDepartment.

7.SecondaryDisinfection(DistributionSystemChlorineResidual):Secondary(residual)disinfectioninvolvesmaintainingadetectablechlorineresidualinthedistributionsystem.ThisismonitoredviathechlorineresidualanalysesconductedwhensamplingmonthlyforcoliformbacteriaaspartoftheRevisedTotalColiformRule(RTCR)monitoringprogram.Whiletheregulatoryrequirementisfora“detectable”chlorineresidual,ideallychlorineresidualsconcentrationsshouldbe≥0.2mg/Lthroughoutadistributionsystem.FortheChesterdistributionsystem,chlorineresidualiscurrentlymonitoredat381HuntingtonRoad,whichisneartheendofadead-endpipeinthesoutheasternpartofthedistributionsystem.The2018distributionsystemchlorineresidualsat381HuntingtonRoadareplottedinFigure7.

Figure7.DistributionSystemChlorineResidual

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Basedonthosedata,thefollowingobservationsweremade:

• ThechlorineresidualsmonitoredmonthlyattheWheelerOillocationhavebeenlowbutdetectable,averaging0.06mg/LfromJanuary2018throughApril2019,withaminimumof0.04mg/Landamaximumof0.11mg/L(Figure7).

• Therequiredminimumrequiredchlorineresidualofa“detectable”concentrationwasmetduringallRTCRsamplingeventsin2018.

• ItwouldbehelpfultomaintainahigherchlorineresidualattheendsofthedistributionsystemsuchastheWheelerOillocation.

• Biologicalgrowthindistributionsystemscanconsumechlorine.Onemeansforperiodicallyrestoringchlorineresidualsistoconductahigh-velocityflushingprogramonceortwiceayeartohelpcleanthepipes.ThatisrecommendedforChestertohelpmaintainthechlorineresiduals.

Tofurtherinvestigatedistributionsystemchlorineresiduals,RCAPSolutionsstaffconductedachlorinemappingexerciseofthedistributionsystemonMarch27,2019.Locationswereselectedbothnearthebeginningofthedistributionsystem,inthemiddle,andparticularlyneartheedges.ResultsarepresentedinFigure8andTable1.

Figure8.DistributionSystemChlorineMappingResults(3/27/19)

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Table1.DistributionSystemChlorineMappingResults(3/27/19)

~timefreechlorine

(mg/L)~flushrate

(gpm)~flushtime

(min)~flushed

volume(gal)Location

12:15 0.48 NM NM NMPOE-lowerbuldingatWTP(formerlowerchlorinatorbuilding)

12:35 0.37 NM NM NM WTPclearwelleffluent

14:02 0.39 2 3 6 191Rte.20(ChesterVillageMarket)

14:20 0.00 7.5 12 90 381Rte.20(WheelerOil)

14:40 0.01 4.3 16 69 309Rte.20(PostOffice)

15:20 0.15 NM 4 8 260Rte.20(Richie'sGeneralService)

15:50 0.25 NM 4 8 29MainSt.(ClassicPizza/BluenoteCafé)

16:45 0.25 NM 2 4 15MiddlefieldRoad(TownHall)

17:00 0.00 5 6 30 106MiddlefieldRoad(residence)

17:40 0.17 1.4 5 7 289Rte.20(DavidShepherdresidence)NM=notmeasured

Thefollowingobservationsweremadefromthechlorinemappingstudyresults:

• Chlorineresiduallevelsinandnearthecenteroftownweresatisfactory,rangingfromahighof0.39mg/LattheChesterVillageMarketlocationtoalowof0.15mg/LatRichie’sGeneralServiceat260Rte.20.

• NochlorineresidualwasdetectedneartheendsofthedistributionsystemonbothRte.20(0.01mg/LatthePostOffice,and0.00mg/LatWheelerOilCo.)andMiddlefieldRoad(0.00mg/Lat106MiddlefieldRd.).

• TherewasasuddenchangeinthechlorineresiduallevelinaveryshortdistanceonRte.20.Specifically,aresidenceat289Rte.20had0.17mg/Lchlorine,whilethePostOfficeafewbuildingsfurtheroutonRte.20hadonly0.01mg/L.ThereasonforthatisthePostOfficeisonadead-endpartofthepiping.Afterpassing289Rte.20,thepipingsplitswithadeadendgoingtothePostOffice,andthemainpipingleavingRte.20andfollowingBayStateDrivebacktoRte.20neartheWheelerOilCo.monitoringlocationat381Rte.20andthenashortwaystotheendofthedistributionsystem.

RCAPSolutionsalsousedthedistributionsystemmaptodevelopaninventoryofthepipinginthesystem.Determiningthetotalvolumeinthedistributionsystemcomparedtothechlorinecontacttimeinthetreatmentplantcanhelpdetermineifbleedingwateroutofthedistributionsystem(e.g.,viablow-offvalvesorableederassembly)cansignificantlyhelpreduceoverallwaterageandthusshortenchlorinecontacttime.Atpresent,thechlorinecontacttank(clearwell)volumeaverages~98,000gallons,andsecondprimarydisinfectionsegmentofthe8-inchpipe(betweenthetreatmentplantandtheoldchlorinatorbuilding)is~4,363gallons.Thecombinedtotalvolumeforchlorinecontacttimeduringprimarytreatmentis~102,000gallons.Thevolumeofwaterinthedistributionsystempipingwascalculatedtobeapproximately57,000gallons.Combiningthosetwovolumes

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resultsinatotalvolumeof~159,000gallons,ofwhich64%isprimarydisinfectionand34%isinthedistributionsystem.Withanaveragedemandof45,000gpd,thatcorrespondstowateragesof2.3daysforthetreatmentsystemand1.3daysforthedistributionsystem.Thismeansthatevenifthewholedistributionsystemwasflushedout,thewateragewouldstillbe~64%ofwhatithadbeen.Solargechangesinoverallwateragearenotexpectedtoresultfrombleedingwaterattheedgesofthesystem.Nonetheless,bleedingwateroutattheedgesofthedistributionsystemmaybeapossiblemeansofimprovingchlorineresidualatthoselocations.Thatoptionmaybeconsiderediftherecommendedunidirectionalflushingprogramisnotimplementedordoesnotprovidethenecessaryresults.Ifbleedingittobeconducted,itisusefultocalculatethevolumeofwaterthatisdesiredtobewasted.Onepossiblegoalwouldbetowaste(andthusmove)avolumeofwaterequivalenttothevolumeofwaterinthepipingbetweentheendofadead-endpipeandthelocationofthenearestacceptablechlorineconcentration.UsingthatapproachandthechlorineresidualdatafromtheMarch27,2019chlorinemappingstudy,thefollowingvolumeswouldneedtobewastedfromeachofthetwodeadends:

• Rte.20:~13,500gallonsfrom289Rte.20(0.17mg/Lchlorine)aroundBaystateDriveandtotheverysoutheastendofthesystemonRte.20pastWheelerOilCo.at381Rte.20

• MiddlefieldRoad:~8,700gallonsbetweentheTownHallat15MiddlefieldRoad(0.15mg/Lchlorine)outtotheendofthepipeatthenorthendofMiddlefieldRoad

Inthefield,flushingcouldcontinueuntilallcolorisgoneandanacceptablechlorineresidualisobtained(andassumingadequatepressureremainsthroughoutthedistributionsystem).8.pH:ThefinalcomponentofthetreatmentsystemispHadjustmentwithsodiumhydroxide.Unlessotherwisespecified,drinkingwatershouldhaveapHof6.5to8.5(pertheUSEPAsecondaryMCL).OptimalCorrosionControlTreatment(OCCT)ofteninvolvesanarrowertargetrangeforpH,andistypicallyabove7.0orhigher.ThefinishedwaterpHvaluesfor2018areshowninFigure9.ThefollowingobservationsweremaderegardingpH:

• ThepHdataarerelativelyscattered,coveringarangefrombelow7.0toabove8.5,withanarithmeticaverageof7.7.ItisbestfordistributionsystemwaterqualitytomaintainamoreconstantpH.ThesystemOperatorisawareofthisissue,andhastriedtomaintainasconstantapHaspractical.ChestercouldinvestigatehowtomaintainamoreconstantpH.

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Figure9.FinishedWaterpHin2018

• RCAPSolutionsdidnotfindaspecificMassDEPrequirementforthefinishedwaterpH.

However,thesystemOperatorexplainedthatDanLaPradeofMassDEPtoldhimtouseafinishedwaterpHrangeof7.3to7.5.ThatistoonarrowarangeofpHforpracticalimplementation,especiallyforalow-alkalinitywater,andshouldbewidened.AsisshowninFigure9,thatnarrowpHtargetwasnotmetveryfrequently.

• GiventhattheregulatorycomplianceissueiswithTHMsandnotleadandcopper,raisingthepHisnotrecommendedasthatcanresultinhigherTHMs(higherpHalsoresultsinaweakerchlorinedisinfectant).

• RCAPSolutionsrecommendsatargetfinishedwaterpHof7.5+/-0.3(i.e.,pHof7.2to7.8).Thiswouldwidentheallowablerangefromadifferenceof0.2uptoadifferenceof0.6pHunits.

9.DisinfectionByproducts:Twoclassesofdisinfectionbyproducts(DBPs)areregulatedbytheDisinfectant/DisinfectionByproductRule(D/DBPR):totaltrihalomethanes(TTHM,thetotalofthefourTHMs)andthetotaloffivehaloaceticacids(HAA5).ComplianceisdeterminedbymonitoringforTHMsandHAAsatselectdistributionsystemlocationsonceperquarter,andthencalculatingtheLocationalRunningAnnualAverage(LRAA)foreachsamplesite.TheTTHMandHAA5LRAAconcentrationsateachsamplesitemustnotbeabovetheMCLsof80µg/Land60µg/L,respectively.ThecurrentDBPmonitoringlocationsareat191HuntingtonRoad(ChesterVillageMarket),whichislocatednotfarfromthewatertreatmentplant,and381HuntingtonRoad(WheelerOilCo.),whichislocatedonadead-endlinenearthesoutheastendofthedistributionsystem.

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TheLocationalRunningAnnualAverageresultsforTTHMsarepresentedinFigure10,andforHAA5inFigure11.TheindividualTTHMresultsareplottedinFigure12forthesamplesiteatWheelerOilCo.,andfortheChesterVillageMarketinFigure13.IndividualHAA5resultsareshowninFigures14and15,respectively,forWheelerOilandChesterVillageMarket.ThesedatacoverthefullperiodthattheStage2D/DBPRhasbeenineffect,sincethebeginningof2013,andupthroughthe2ndquarterof2019.ThefollowingobservationsweremaderegardingTTHMandHAA5atthetwomonitoringlocations:

• TTHMshavebeenhighestattheWheelerOilCo.location,andHAA5havebeenhighestattheChesterVillageMarket.

• Intermsofregulatorycompliance,theMCLforTTHMswasexceededattheWheelerOilCompanylocation(381HuntingtonRoad)forthreequartersinarow(thethirdandfourthquartersof2018andthefirstquarterof2019).Themostrecentquarter’sresultsareincompliancewiththeDBPlimits,asthemaximumLRAAforTTHMis79µg/L.

• WhiletherehavebeennoexceedancesoftheMCLforHAA5,theLRAAhasattimescomeclosetotheMCL(Figure11andFigure15).ThehighestLRAAforHAA5was58µg/LattheChesterVillageMarketlocation(191HuntingtonRoad)on2/20/18,closetotheMCLof60µg/L.Assuch,HAA5arealsoofconcerninadditiontoTTHMs.

• ThereappearstobeasteadyincreaseinTTHMattheWheelerOilCo.location(381HuntingtonRoad)startingin4thquarterof2016.ThathasresultedinasteadyincreaseintheLRAAforTTHMsatthatsite,increasingfrom40µg/Lin3rdquarter2017upto92µg/Linthe4thquarterof2018.HAA5alsoincreasedduringasimilartimeperiod.Thecauseoftheseincreaseshasnotbeenidentified.Itisnotedthattheflushingprogramendedsometimearoundtwoyearsago.ItisalsopossiblethatthischangewasattributableatleastinparttoswitchingsourcewaterfromAustinBrookReservoirtoHornPond,butthetimingofthatswitchcouldnotbedeterminedandthusnocorrelationcouldbemade.

• ThetrendofincreasingTTHMconcentrationovertimeduringthepasttwoyearscontrastswiththetypicalTTHMseasonalpatternwherethehighestresultsarefoundinAugustduetothewarmertemperatures,andthelowestresultsinFebruaryduetocoldertemperatures.However,fortheChesterVillageMarketlocation,thehighestTTHMvaluesince2013was100µg/LinFebruary2018(HAA5alsowasatitshighestforthatlocationinFebruary2018),andthesecond-highestvalueof87µg/LwasinNovember2018.Incontrast,theAugust2018samplewasonly38µg/L.Noexplanationwasfoundforthisanomaly.

• TheLRAAdataforTTHMsshowninFigure10suggestthattherehavebeenperiodswheretheTTHMslevelswerenotmuchdifferentbetweenthetwosamplinglocations,including2013throughearly2015,and2017throughearly2018.Givenbothsamplesitesreceivewaterfromthesamesource,theonlyfactorthatwouldbeexpectedtoimpactdifferencesintheirTTHMlevelswouldbewatertraveltime(i.e.,chlorinecontacttime).Thereappearstobeaperiodfromlate2015through2016whenthewateragedifferencemayhavebeengreater,asthereisalargerdifferencebetweenthetwosamplesitesfortheTTHMLRAAs.

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Figure10.TTHMLocationalRunningAnnualAverages

Figure11.HAA5LocationalRunningAnnualAverages

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Figure12.TTHMat381HuntingtonRoad(WheelerOilCo.)

Figure13.TTHMat191HuntingtonRoad(ChesterVillageMarket)

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Figure14.HAA5at381HuntingtonRoad(WheelerOilCo.)

Figure15.HAA5at191HuntingtonRoad(ChesterVillageMarket)

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• InthecaseofHAAs,thereisacleardifferenceinHAA5levelsatthetwomonitoringsites,withlevelsattheWheelerOilCo.nearzero.ThisdifferenceinHAA5islikelyaresultofbiodegradationofHAA5withinthedistributionsystem,andgiventhelongerwaterageatWheelerOilCo.thereismoretimeforthebiodegradationtooccur.Whilethebiodegradationiscommoninthewarmermonths,itnormallyislessimpactfulduringthecoldermonths.Inthiscase,however,forthepastfouryearsbasicallyalloftheHAA5thathadbeenformedhaddegradedbythetimethewaterreachedtheWheelerOilCompanysite(Figure14).

• AnothernotabletrendisthatthreeofthefivehighestHAA5resultsoverthepastsixyearsfortheChesterVillageMarketwereinFebruary(Figure15).Typically,HAA5wouldbehigherinMayandNovemberthaninFebruary.ThismaysuggestsubstantialbiodegradationofHAA5leadingtotheChesterVillageMarketsite(despitethepresumedrelativelyshortwaterageatthatsite),astheFebruaryresultswereoftensubstantiallyhigherthanthedatafortheotherquarters,especiallythe3rdquartersamplinginAugust.

GiventherehavebeennoMCLexceedancesforHAA5,andthatthehighestTTHMexceedancewasbyonly15percentovertheMCL(asopposedtomuchhighervalues),averylargereductioninDBPsmaynotbenecessary.SimpleoperationalimprovementsmaybesufficienttoregainandmaintaincompliancewiththeDBPMCLs.Thoseimprovementsshouldbeimplementedandevaluatedpriortoconsideringanymajorcapitaladditiontothetreatmentsystem.ThreeapproachesarerecommendedatthistimeforimprovedcontrolofDBPs:

1. Implementaregularflushingprogram:Aswasdiscussedpreviously,semi-annualunidirectionalhigh-velocityflushingofthe

distributionsystemisrecommendedtohelpmaintainchlorineresidualsneartheendsofthesystem.FlushinghasalsobeenknowntobeabletoreduceDBPs,andthusisalsorecommendedforthatpurpose,especiallyforreductionofTHMs.Flushingcouldremovesomebiofilmfromtheinteriorofthepipes,whichcouldpotentiallyreducethebiodegradationofHAAs,andthusresultinhigherlevelsofHAAs.ThatpotentialeffectshouldbelookedforwhenreceivingthequarterlymonitoringresultsforDBPs.

2. Potentiallyswitchsourcewatertoreduceinfluentnaturalorganicmatter(NOM):Twosourcewatersareavailabletofeedthetreatmentplant.Itisrecommendedthat

Chesterregularlymonitorbothsourcewatersfortotalorganiccarbon(TOC).TOCservesasasurrogateforNOM.UV-254anddissolvedorganiccarbon(DOC)arealsoavailablesurrogatesforNOM.MonthlymonitoringofTOCisrecommendedforthefirstyear,butatminimumChestershouldsamplebothsourcewatersforTOConceperquarteronthesamedaysthatsamplingforDBPsisconducted.Turbidityshouldalsobemonitored,asthedecisionofwhichsourcetousemaybepredicatedontherelativelevelsofbothturbidityandTOC.TheTOCdatamaybeusedtodeterminewhichsourcewatertouse,especiallyduringthewarmermonthswhenTTHMformationismoreofaproblem.ItisexpectedthattheTOCinAustinBrookReservoirwillbelowerthanthatintheshallowerandslower-flowingHornPond.Therawwatertapinthetreatmentplantmaybeusedforsamplingthecurrentsourcewater,whileasampleoftheothersourcewatercanbecollectednearwherethewaterexitsthepond/reservoir.

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ThesourcewaterwasmonitoredforTOCfour(4)timesTOCin2018,withvaluesrangingfrom4.3to5.0mg/L.WhilethosesampleswerelabeledasbeingfromAustinBrookReservoir,theywerereportedlyfromHornPondasthatwasthesourcewaterbeingusedatthetime.Assuch,cautionshouldbeexercisedinusinganyrecentdatabecauseoftheissuewithsomeHornPondsamplesbeinglabelledasAustinBrookReservoir.

3. Optimizeuseofthegranularactivatedcarbon(GAC)sandwichfilterforremovalofNOMthroughimprovedmonitoringofTOC:

Filter#3hasthegranularactivatedcarbon(GAC)sandwich,withalayerofGACbetweentwolayersofsand.TheGACwasaddedtothisfilterforremovalofnaturalorganicmatter(NOM),whichisaprecursortoDBPformation.ThesorptivecapacityoftheGACforNOMandotherorganicchemicalsislimited.Theextentthesorptivecapacityhasbeenexhaustedcan,inpart,bemonitoredbyperiodicallyanalyzingtotalorganiccarbon(TOC)intheinfluentandeffluentfromthisfilter.WhentheeffluentTOCapproachestheleveloftheinfluentTOC,theactivatedcarbonisnearingexhaustionforadsorbingNOM.ConsiderationshouldbegiventoreplacingtheactivatedcarbonpriortoexhaustingitscapacitytoremoveNOM.

ATOCmonitoringprogramisrecommendedtohelpoptimizeuseoftheGACsandwichinFilter#3.MonthlymonitoringofTOCisrecommendedforthefirstyear,butatminimumChestershouldsamplefilterinfluentandfiltereffluentforTOConceperquarteronthesamedaysthatsamplingforDBPsisconducted.SampleandanalyzeforTOCinthefilterinfluent,theFilter#3effluent,andeithertheFilter#1orFilter#2effluentasacontrolsample.OnlyfilterscurrentlyonlineshouldbemonitoredforTOC.Sincethefilterinfluentsampleiseffectivelythesameasthesourcewatersampleforthecurrentsourcebeingused,itwouldbeprudenttodothissamplingonthesamedaysthattherawwaterTOCissampled,asrecommendedabove.

TOCwasmonitoredforboththerawwaterandfinishedwateron9/17/18and11/26/18,withTOCremovalbeing33%and13%,respectively(averagesof4.7mg/Linfluentand3.6mg/Leffluent).ItishopedthatamorestrategicandtargeteduseofthecarbonsandwichfilterwillresultinimprovedTOCremoval.

IfthoseapproachesdonotsatisfactorilyreduceDBPs,thenotherapproacheswouldneedtobeconsidered,includingpossiblybleedingwateroutoftheendsofthesystemtoreducewaterage,installingadditionaltreatmentcapabilitytoreduceNOM,orreducingpHtodecreaseTHMformation.10.Color:Nohistoricalcolordatawerefoundduringthisinvestigation.MassDEPmentionedcolorissuesintheirAugust24,2018lettertoChester,andalsomentionedinaninternalMassDEPe-maildatedAugust16,2018thatanearlierbrownwatercomplainthadbeenresolvedupondiscoveryandrepairofaleak.ThewatersystemOperatorhasreceivedafewcomplaintsaboutthewater’sappearance,includingayellowishcolor,andalightbrownishtea-likecolor.RCAPSolutionsstaffspokewithsometownresidentsabouttheirperceptionofthewaterqualityduringasitevisitonMarch27,2019,andsomeoftheresidentsnotedthatthewaterissometimescoloredeitherlightyelloworlightbrown.RCAPstaffconductedavisualexaminationofthewatercolorfromeachlocationthatchlorineresidualwasmeasuredduringthechlorinemappingstudyconductedonMarch27,2019.ThissimpletestinvolveslookingforcolorinawatersampleinsideawhiteStyrofoamcup.Distilledwaterwasusedfor

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comparisonasneeded.Ayellowtingetothewaterwasevidentatsomeofthelocations(butnotatalllocations),anditwasalighteryellowatsomelocationsthanatothers.AnexampleoftheyellowtintisshowninFigure16,whichcomparesadistributionsystemsamplewithdistilledwater.Nocolorwasdetectedinthetreatmentplant’sfinishedwater.

Figure16.Yellow-tingedWater(3/27/19)–

Distributionsystemsampleisontheleft,distilledwaterontherightOnecommoncauseofcolorationofdistributionsystemwateristhereleaseofiron,manganese,and/orothermetalsfromtheinteriorsurfaceofthepipe.Someofthepipesaremadeofiron,whilemanganesecandepositovertimeandbeasourceofcolorifitdissolvesintothewater.Manganesecancausewatertobeyellow,brown,orevenblack,dependingontheconcentration.Irontypicallyresultsinarust-coloredwater.Onemeansforreducingthesecolorissuesistomaintainasoundflushingprogramthathelpscleandepositsoffoftheinsideofthepipes.Chesterhashistoricallyconductedadistributionsystemflushingprogramtwiceperyear,butreportedlydidnotdothatthepasttwoyears.Resumingthesemi-annualflushingprogramisrecommendedtohelpreducethecolorobservedinthewater.Theflushingprogramshouldbeconductedunidirectionally,andwithsufficientvelocitytosufficientlycleantheinteriorofthepipes.Asnotedearlier,aproperlyconductedflushingprogramcanalsohelpmaintainchlorineresidualsandreducedisinfectionbyproducts.11.LeadandCopper:TheChesterWaterDepartmentprovidespHadjustmentasacorrosioncontrolmeasure.ThefinishedwaterpHisplottedinFigure9,andwasdiscussedpreviously.TheLeadandCopperRule(LCR)distributionsystemleadmonitoringdataarepresentedinFigure17andforcopperinFigure18.Basedontheavailabledata,leadandcoppercorrosiondoesnotappeartobeanissue,asneitherActionLevelhasbeenexceeded,andallindividualsampleresultswerebelowtheActionLevels.Thoughnotoptimal,thefluctuatingpHandchlorinelevelsdonotappeartohavecausedanyLCRcomplianceissues.

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Figure17.LCRLeadMonitoringResults(2013-2017)

Figure18.LCRCopperMonitoringResults(2013-2017)

12.SummaryandConclusions:Muchofthewaterqualityisgood,butimprovementcouldbemadeinreducingTHMs,HAAs,andcolor,andalsoforincreasingchlorineresidualsattheendsofthedistributionsystem.Implementationofasemi-annualhigh-velocityunidirectionalhigh-velocityflushingprogramisrecommended,andcouldhelpachieveallfourofthosegoals.ImplementationofamonitoringprogramforTOCisalsorecommendedtohelpselectwhichsourcewatertousetominimizeinfluentNOM,andtooptimizeuseoftheactivatedcarbonsandwichfilterforremovalofNOM.

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Basedontheavailabledata,leadandcoppercorrosiondoesnotappeartobeanissue,asneitherActionLevelhasbeenexceeded,andallindividualsampleresultswerebelowtheActionLevels.Thoughnotoptimal,thefluctuatingnatureofthepHandchlorinelevelsdonotappeartohavecausedanyLCRcomplianceissues.

13.Recommendations:ThefollowinglistsummarizestheprimaryrecommendationsdevelopedduringthisevaluationtohelptheChesterWaterDepartmentimproveoperationsandwaterquality:

DBPcontrol:

1. Implementasemi-annual,unidirectional,high-velocityflushingprogramtohelpcleanthedistributionsystempipes.ThiscanhelptoreduceDBPs,maintaindistributionsystemchlorineresiduals,andreduceincidentsofcoloredwater.Thosethreeissuesshouldbemonitoredcloselyafterflushinghasbeenconducted.Formaintainingchlorineresidual,focusonthenorthendofMiddlefieldRoadandthesoutheastendofRte.20.

2. ImplementaTOCmonitoringprogramforthetwosourcewaters(monitorturbidityalso).ConsiderusingthesourcewaterwiththelowerTOCduringthewarmerseasonstoreducetheamountofinfluentNOM,aslongasturbidityisnotanissue.DetailedsamplingrecommendationsareprovidedaboveinSection9.

3. ImplementaTOCmonitoringprogramforthefiltereffluenttohelpdeterminethesaturationstatusofthegranularactivatedcarboninFilter#3.UsethesedatatooptimizetimingoftheuseofFilter#3forremovalofNOM.DetailedsamplingrecommendationsareprovidedaboveinSection9.

Additionalprimaryrecommendationsincludethefollowing:

4. IftheunidirectionalflushingdoesnotsolvetheDBPandchlorineresidualissues,thenwateragecouldbecontrolledsomeattheedgesofthedistributionsystembywastingwaterthroughblow-offassemblies(i.e.,bleedingwateroutofthedistributionsystem).ThiscouldbedoneatthenorthendofMiddlefieldRoadandattheeastendofRte.20.

5. ProperlylabelthesourcewatersamplesasHornPondorAustinBrookReservoir(theyhavebeenmislabeledrecentlyasAustinBrookReservoirwhenitreallywasHornPondthatwassampled).

6. Installsampletapsforallthreeindividualfiltereffluents(IFEs)andalsofortheonecombinedfiltereffluent(CFE).ThereshouldbeanonlineturbiditymeterfortheCFEsampletouseforregulatorycompliancereporting.

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7. TurbidityresultsreportedtoMassDEPhavebeenforthefinishedwater(i.e.,treatmentplanteffluentatthePOE),butinsteadshouldbeforthecombinedfiltereffluent(CFE).Reportingcombinedfiltereffluentshouldlowertheresultsreportedfromanaverageof~0.11NTUtoapproximately~0.03NTU.

8. ImplementanewtargetfinishedwaterpHrangeof7.5+/-0.3(i.e.,7.2to7.8).

9. InvestigatehowtomaintainamoreconsistentfinishedwaterpH.

10. Investigatehowtomaintainamoreconsistentfinishedwaterchlorineresidual.

Otherrecommendationsincludethefollowing:

11. RCAPwasnotabletoobtainthespecificationsusedintheSCADAcalculationstodeterminethevolumeofthechlorinecontactors(partofdeterminingchlorinecontacttime),andthuscouldnotconfirmthisaccuracy.Also,thetracerstudythatresultedindeterminingabafflingfactorof0.13alsowasnotlocated.Thisinformationshouldbeobtainedandreviewedforaccuracy.Thatwouldhelpconfirmchlorineisnotbeingunderdosedoroverdosedasaresultofusinganinaccuratechlorinecontacttime,andconfirmthatbothdisinfectionsegmentsarenecessary.

12. TheSCADAsystemcouldbeimprovedtoincludetrendchartsofallwaterqualitydata.

13. TheTownofChestershouldbecomemoreinvolvedinthewatersystemoperations,especiallythetreatmentsystem,toreducerelianceonthecontractedcertifiedoperator,andtogainabetterunderstandingoftheissuesfacingthewatersystem,aswellasthetimeandresourcecommitmentsthatareneededtoensureefficientandsustainableoperationsandfuturecompliancewithallapplicableregulations.

14. Improvedatamanagement,includingtabulatingandplottingallhistoricaldata.SomeoneattheTownshouldfollowthedataandcomplianceissues,notjustthecertifiedoperator.

15. Developandmaintainacustomercommentlog.

16. Developandimplementapublicrelationscampaignaboutwaterquality.

17. Formonitoringsites,includetheaddressinthesitename(e.g.,“381Rte.20”or“WheelerOilCo./381Rte.20”).

18. UpdatethenameoftheWalkerBrookStoresamplesitetothecurrentnameofChesterVillageMarket(at191Rte.20/HuntingtonRd.).