final beaver water district master plan study...black & veatch | chapter 1 – executive summary...

FINAL

BEAVER WATER DISTRICT MASTER PLAN STUDY Chapter 1 – Executive Summary

B&V PROJECT NO. 185669

PREPARED FOR

Beaver Water District 12 NOVEMBER 2015

®

®

Beaver Water District | MASTER PLAN STUDY FINAL

BLACK & VEATCH | Chapter 1 – Executive Summary ‐ Table of Contents Page i

Table of Contents Introduction.............................................................................................................................1PopulationandDemandProjections...............................................................................2ProcessOverview...................................................................................................................4RegulatoryReviewandWaterQualityAssessment....................................................5FacilityAssessment...............................................................................................................7CapacityEvaluation...............................................................................................................8SolidsHandlingFacility........................................................................................................8CapitalImprovementPlan..................................................................................................9


BLACK & VEATCH | Chapter 1 – Executive Summary Page 1

Introduction ThisreporthasbeenpreparedtoprovidetheBeaverWaterDistrict(BWD)withaguideforimprovementsoverthe25‐yearplanninghorizon.Therecommendedimprovementplanpresentedhereinwillserveasabasisforthedesign,construction,andfinancingoffacilitiestomeetpopulationgrowth,industrialneeds,andcommercialdevelopmentforthefourcustomercitiesincludingBentonville,Fayetteville,Rogers,andSpringdale.ThecurrentserviceareaboundariesforthefourcustomercitiesincludingtheirconsecutivecustomersareshowninFigure1‐1.

Figure 1‐1: BWD Service Area



Population and Demand Projections HistoricalandprojectedpopulationsforthefourcustomercitieswereobtainedfromtheNorthwestArkansasPlanningCommissionthroughYear2035.Inordertodevelopprojectionsthroughoutthe25‐yearplanninghorizon,regionalpopulationwereextrapolatedthrough2040andsummarizedgraphicallyinFigure1‐2.

Waterusecharacteristicsforresidential,commercial,industrial,andconsecutivesystemcustomersweregatheredforeachcustomercity.Percapitausage,whichincludesresidentialandcommercialusage,wascalculatedforthefourprimarycustomercitiesandisgenerallytrendingdownwardsince1985asaresultofconservationandefficiencyefforts.Duetorelativelysteadywaterconsumptioninrecentyears,a5‐yearaveragepercapitausewasusedasabasisforfutureprojections.Averagewaterdemandprojectionswerecompletedbaseduponpopulationgrowthandthe5yearaveragepercapitawateruseforeachprimarycustomercity.A95thpercentilemaximumdaypeakingfactorwasthenappliedtotheaveragedayprojectiontocalculatethefuturemaximumdaydemand.Inaddition,a3%processusefactorwasappliedtothetotalmaximumdayprojectedflowtoestablishtherequiredwaterproductionrate.Sincelimiteddataisavailabletoprovidereliablepredictionsforindustrialwateruse,projectionsarebaseduponindustrialwateruseincreasingatthesamepercentageasresidentialwaterusethroughoutthestudyperiod.Basedontheseplanningcriteria,theprojectedaveragedayandmaximumdaydemandsareasshowinTables1‐1and1‐2,respectively,andgraphicallyonFigure1‐3.

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1970 1980 1990 2000 2010 2020 2030 2040 2050

Popu

latio

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usan

ds)

Year

Figure 1‐2. Historical and Projected Population

Bentonville Regional Rogers RegionalSpringdale Regional Fayetteville Regional



TABLE 1‐1. AVERAGE DAY DEMAND PROJECTIONS

Year

Average Day (mgd)

Bentonville Rogers Springdale Fayetteville BWD Sales BWD Production

2015 8.93 9.32 16.06 14.79 49.10 50.57

2020 10.22 10.47 18.18 16.33 55.19 56.85

2025 11.51 11.61 20.31 17.87 61.29 63.13

2030 12.79 12.76 22.44 19.41 67.39 69.41

2035 14.08 13.90 24.56 20.94 73.49 75.69

2040 15.37 15.05 26.69 22.48 79.59 81.98

TABLE 1‐2. MAXIMUM DAY DEMAND PROJECTIONS

Year

Maximum Day (mgd)

Bentonville Rogers Springdale Fayetteville BWD Sales BWD Production

2015 16.98 19.09 29.92 30.02 96.01 98.89

2020 19.43 21.43 33.88 33.15 107.89 111.13

2025 21.88 23.78 37.84 36.28 119.78 123.37

2030 24.33 26.13 41.80 39.40 131.66 135.61

2035 26.77 28.47 45.76 42.53 143.54 147.85

2040 29.22 30.82 49.72 45.66 155.42 160.09

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gd)

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Figure 1‐3. BWD Maximum Day (MD) Demand Projections

Total Max 2005 BWD Master Plan Bentonville Max

Rogers Max Springdale Max Fayetteville Max

95% Confidence

50% Confidence



Process Overview Currently,BWDoperatesthethreeWTPswithatotalcapacityof140mgd.EachWTPhasthesameconventionaltreatmentprocessasillustratedbelowinFigure1‐4.Conventionaltreatmentincludesthefollowingmajorprocesses: Coagulation Flocculation Sedimentation Mixedgranularmediafiltration Disinfection

Figure 1‐4. BWD Treatment Process



Regulatory Review and Water Quality Assessment DrinkingwaterregulationsaretheprimarydriverforthetreatmentprocessesusedbyBWD.Currentandfutureregulationswereevaluatedtodetermineanypotentialimpactsonwatertreatmentoperations.Theresultsofthisevaluation,andtheDistrict’santicipatedabilitytocomply,aresummarizedinTable1‐3.

TABLE 1‐3. REGULATIONS COMPLIANCE

Regulation Compliance Status Future Compliance

Surface Water Treatment Rule (SWTR) Expected

Long Term 2 Enhanced Surface Water Treatment Rule (LT2)

Expected

Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage II DBPR)

Continued Monitoring

Arsenic Rule Expected

Lead and Copper Rule Continued Monitoring

Radionuclides Rule Expected

Phase I VOCs Expected

Phase II VOCs, SOCs, and IOCs Expected

Phase V VOCs, SOCs, and IOCs Expected

Revised Total Coliform Rule Expected

Filter Backwash Recycle Rule Not Currently Applicable

Could be influenced by EPA and NPDES requirements

Inadditiontoanoverallregulatorycompliancereview,adetailedanalysisofdisinfectionbyproducts(DBPs)wasconductedtoquantifytheimprovementsassociatedwithimplementationofthechlorinedioxidefacilityin2013.SinceClO2hasbeenusedasthepre‐oxidant(withthedoserangingbetweenapproximately0.6mg/Land1.5mg/L,asneeded),theaverageTTHMforalltestedsiteshasbeenreducedbyapproximately25%andtheaverageHAA5hasbeenreduced32%ascomparedtochlorineassummarizedforthetestinglocationsinTable1‐4.



TABLE 1‐4. AVERAGE DBP CONCENTRATION PER LOCATION

TTHM Avg Before ClO2

1 (ppb)

TTHM Avg After ClO2

2 (ppb)

Percent Decrease

HAA5 Avg Before ClO2

1 (ppb)

HAA5 Avg After ClO2

2 (ppb)

Percent Decrease

BWD 39.4 27.0 37% 29.5 22.2 25%Bentonville 59.8 42.7 28% 34.4 22.4 37%Rogers 59.4 42.9 28% 33.6 24.5 26%

Springdale 58.6 45.1 23% 36.8 24.8 32%Fayetteville 54.5 43.2 21% 36.4 23.7 34%1. Before ClO2 encompasses data prior to Jan 2013, as far back as 2001, as available.2. After ClO2 encompasses data from the first quarter of 2013 to the third quarter of 2015.

TasteandodorcausingcompoundsMIBandGeosminarecontaminantsthatBWDcontinuestomonitor.Ingeneral,theaverageandpeakconcentrationsofMIBhavedecreasedovertime,butaredetectableforalongerdurationasshownonFigure1‐5.Whilethistrendisencouraging,theabilitytopredictandcontrolfuturelevelsisuncertain.Accordingly,wehavereviewedandsummarizedpotentialtreatmenttechnologiesincludingozonation,powderedactivatedcarbon,andUV/hydrogenperoxideaspotentialsolutionsifrequiredtocontroltasteandodor.

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Jul‐98 Apr‐01 Jan‐04 Oct‐06 Jul‐09 Apr‐12 Dec‐14 Sep‐17

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tration (ppt)

Date

Figure 1‐5. MIB and Geosmin

MIB

Geosmin



Facility Assessment Afacilityassessmentwasperformedtoprovideanindependentreviewoftheconditionofexistingassets.ThisdatawillformtheframeworkfortrackingmajorequipmentperformanceandanticipatedreplacementdatesintheDistrict’sassetmanagementsystem.Assetsareidentifiedinthisreportasanitemessentialtoprocesscompletionand/orequipmentofvalue;approximately$10,000ormore.Equipmentinspectionswereconductedtoassignaconditionalratingandanagefactor.Theconditionalrating(CR)isbaseduponequipmentcondition,function,andmaintenancehistoryonascalefrom1to5,with1beingthemostfavorable.Theagefactor(AF)isbaseduponcurrentageascomparedtotheexpectedusefullife.Thecombinationofconditionalratingandagefactorresultsinanoveralladjustmentfactorfortheexpectedlife,asgovernedbythematrixinTable1‐5.

TABLE 1‐5. EXPECTED LIFE ADJUSTMENT FACTOR (ELAF)

Conditional Rating Percent of Expected Life Completed at Evaluation 1 2 3 4 5

Age Factor

0%‐25% A 5% 0% ‐25% ‐50% ‐75%

26%‐50% B 5% 0% ‐10% ‐25% ‐50%

51%‐75% C 10% 5% 0% ‐10% ‐25%

76%‐100% D 10% 5% 0% 0% 0%

Beyond Expected Life E 20% 10% 5% 0% 0%

Theexpectedlifeadjustmentfactor(ELAF)wasthenappliedtoeachassettodeterminethetheoreticaldateforfailureandreplacementoftheasset.Forexample,averticalturbinepumpinstalledin1990,withananticipatedlifeof40years,wouldbedueforreplacementorrehabilitation(R&R)intheYear2030.However,iftheassetwasgivenanELAFratingof4B,theexpectedlifewouldbereducedby25%whichinturnwouldmodifytheexpectedR&RdatetotheYear2020.Theseassessmentsresultedinthedevelopmentofanadjustedreplacementdate(ARD)foreachassetevaluated.Fromthisassessment,achronologicallistingofassetswhichhaveorwillsoonexceedtheirusefullifewasdeveloped.ThisdatawillbeimportedintotheDistrict’songoingassetmanagementprogramtoaidindeterminingwhenanassethasreachedtheendofitsusefullife.ThiswillthentriggerfurtherevaluationbytheDistricttodeterminethebestcourseofactionwhetheritberehabilitation,replacement,orruntofailure.MajorrepairsorreplacementoftheassetwouldbefundedthroughtheDistrict’sreplacementandrefurbishmentfund.



Capacity Evaluation CurrentwaterrightsforBeaverLakeprovidefor120MGDofannualaveragedaydemandwhichwillbeadequatethroughthestudyperiod.TheSouthIntakeiscurrentlylimitedbythepressurelimitsofthe48‐inchtransmissionpipeline.Therefore,increasingfuturecapacityoftherawwatersystemwillinvolveexpansionoftheNorthIntakebyaddingpumpsintheYear2031.Aparallel60‐inchtransmissionpipelinefromtheNorthIntaketotheplantsiteisrequiredbyYear2036andwillprovidesufficientcapacityfortheultimatebuildoutoftheplant.A40MGDplantexpansionisrequiredbyYear2031inordertomeetmaximumdaydemand.Ultimately(beyondthestudyperiod),another40MGDplantexpansionwillberequiredtomeetthefullbuild‐outofthetreatmentfacilities(220MGD).TheexistingclearwellscurrentlyhaveadequatecapacitytomeetCTrequirementsforinactivationofGiardiaunderextremeconditions(highflow,lowclearwelllevel,lowchlorineresidual,andlowtemperature).Aclearwellexpansionof8MGisrecommendedtobecompletedpriortotheplantexpansioninYear2031tomaintainoperationalflexibility.WESTERN CORRIDOR In2006,aRegionalGrowthStudy(RGS)forBWD’scustomercitiesidentifiedthatfuturepopulationgrowthwouldtakeplacewestofI‐540(nowI‐49).ItwasrecommendedthatanewtransmissionlineextendedtoapumpstationwestofI‐49beimplementedtomeetultimatedemand.Thejustificationandtimelineproposedinthe2011WesternCorridorPipelineandPumpStationStudywererevisitedaspartofthismasterplan.TheexistingpumpingfacilitiesareprojectedtoreachtheirbuildoutcapacitybyYear2032andthusnecessitatetheneedforadditionalpumpingcapacityattheWesterCorridorfacility.However,multipleotherfactorswillneedtobeevaluatedandcoordinatedwiththecustomercitiespriortoimplementation.

Solids Handling Facility Processwastestreamsincludefilterbackwash,filter‐to‐waste(FTW)andsedimentationbasinblowdowns.Thesewastestreamsareladenwithsolidsremovedfromtherawwaterduringthetreatmentprocessandasaresultofchemicalapplication.Thesolidsgeneratedareagelatinoussubstancethatisdifficulttosettle,conveyanddewater.Ahighlevelevaluationofthecurrenttreatmentsystemwasconductedthatincludedidentificationandanalysisofthecontributingflowstreamsandhowtheindividualunitprocessesperforminrelationtotheoriginaldesigncriteriaandindustrystandards.Ingeneral,BWDcomparesfavorablytotheperformanceofotherutilitieswithasimilartreatmentprocess.Variousconsiderationsforoperationalandprocessimprovementsareidentifiedarerecommendedtobeevaluatedfurther.Itisrecommendedthatanadditionalclarificationbasinandreplacementoftheequipmentinthetwogravitythickenersbebudgetedwithinthestudyperiod.



Capital Improvement Plan ThisCapitalImprovementPlan(CIP)summarizestherecommendedimprovementsidentifiedasneededtoincreasefacilitycapacityandtomeetwaterqualityrequirements.Table1‐6summarizesallrecommendedCIPprojectswithinthe2040studyperiodandtheassociatedprobableprojectcost(construction,generalrequirements,contingencyandengineering).Waterqualityrelatedprojectsarelistedseparatelyforreferencepurposesasimplementationisnotguaranteed.

TABLE 1‐6: CAPITAL IMPROVEMENT PLAN PROJECT SUMMARY

Project Type Year Probable Project Cost

North Intake Pumps Capacity 2031 $2.1M

Raw Water Transmission Main Capacity 2036 $15.9M

40 MGD Plant Expansion Capacity 2031 $43.9M

Clearwell Expansion Capacity 2031 $10.5M

High Service Pump Replacements Capacity 2022‐2038 $4.4M

Western Corridor Pump Station Capacity 2032 $19.4M

Western Corridor Transmission Main Capacity 2031 $54.6M

Basin Expansion/Modifications Solids Handling Unspecified $4.1M

SUBTOTAL $154.9M

Ammonia Facilities Water Quality Unspecified $1.3M

UV Facilities Water Quality Unspecified $15.0M

Ozone Facilities Water Quality Unspecified $39.0M

final beaver water district master plan study...black & veatch | chapter 1 – executive summary...

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