EPA, Small Drinking Water Systems, 2005

8/4/2019 EPA, Small Drinking Water Systems, 2005

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Small Drinking Water Systems:

State o the Industry andTreatment Technologies to Meetthe Sae Drinking Water ActRequirements


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EPA 600/X-05/021November 2005

Small Drinking Water Systems:State o the Industry and Treatment Technologiesto Meet the Sae Drinking Water Act Requirements

by

Chrstopher A. Impelltter, Crag L. Patterson, Roy C. Haught, and James A. Goodrch

Water Supply and Water Resources DvsonNatonal Rsk Management Research LaboratoryCncnnat, OH 45268

Ths report was compled n cooperaton wth Shaw Envronmental, Inc.Under EPA Contract EP-C-04-034 WA1-03 and WA 2-03

Work Assgnment Manager - Crag L. PattersonWater Supply and Water Resources Dvson

Natonal Rsk Management Research LaboratoryCncnnat, OH 45268

Natonal Rsk Management Research Laboratory

Oce o Research and DevelopmentU.S. Envronmental Protecton Agency

Cncnnat, OH 45268


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Notice

The EPA has not subjected ths report to nternal revew. Thereore, the research results presented

heren do not, necessarly, refect Agency polcy. Menton o trade names o commercal products does

not consttute endorsement or recommendaton or use.


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Abstract

Ths document summarzes the current natonal statstcs or small drnkng water systems (servng less

than ten thousand people). It descrbes the current status o regulatons, treatment technologes, source

water ssues, dstrbuton system characterstcs, waste resdual ssues, securty/emergency response,

and montorng as these ssues pertan to small systems. Ths objectve o ths document s to provde

researchers n the Water Supply and Water Resources Dvson n the Natonal Rsk Management Research

Laboratory wth a bass to desgn and mplement uture research projects that wll ocus on the most

pressng needs o small systems. The majorty o ths report ncludes data and normaton acqured

between June 1, 2004 and October 1, 2005, and most o the work was completed on November 1, 2005.

Secton 5.6, related to small systems treatment opton aordablty and denton o unreasonable rsk

to health, presents more recent updates (perormed n August 2006) based on revewer comments.


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Foreword

The U.S. Envronmental Protecton Agency (EPA) s charged by Congress wth protectng the Natons

land, ar, and water resources. Under a mandate o natonal envronmental laws, the Agency strves to

ormulate and mplement actons leadng to a compatble balance between human actvtes and the ablty

o natural systems to suppor t and nurture le. To meet ths mandate, EPAs research program s provdng

data and techncal support or solvng envronmental problems today and buldng a scence knowledge

base necessary to manage our ecologcal resources wsely, understand how pollutants aect our health,

and prevent or reduce envronmental rsks n the uture.

The Natonal Rsk Management Research Laboratory (NRMRL) s the Agencys center or nvestga-

ton o technologcal and management approaches or preventng and reducng rsks rom polluton

that threaten human health and the envronment. The ocus o the Laboratorys research program s

on methods and ther cost-eectveness or preventon and control o polluton to ar, land, water, and

subsurace resources; protecton o water qualty n publc water systems; remedaton o contamnated

stes, sedments and ground water; preventon and control o ndoor ar polluton; and restoraton o

ecosystems. NRMRL collaborates wth both publc and prvate sector partners to oster technologes

that reduce the cost o complance and to antcpate emergng problems. NRMRLs research provdessolutons to envronmental problems by: developng and promotng technologes that protect and

mprove the envronment; advancng scentc and engneerng normaton to support regulatory and

polcy decsons; and provdng the techncal support and normaton transer to ensure mplementaton

o envronmental regulatons and strateges at the natonal, state, and communty levels.

Ths publcaton has been produced as part o the Laboratorys strategc long-term research plan. It s

publshed and made avalable by EPAs Oce o Research and Development to assst the user com-

munty and to lnk researchers wth ther clents.

Sally Guterrez, Drector

Natonal Rsk Management Research Laboratory


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Table of Contents1.0 Introducton ..................................................................................................................................1-1

1.1 Goals and Objectves o ths Document .................................................................................1-11.2 Document Organzaton .........................................................................................................1-1

2.0 Current Status and Issues o Small Drnkng Water Systems ......................................................2-12.1 Introducton ............................................................................................................................2-1

2.2 Prole o Small Systems n the U.S. .......................................................................................2-12.3 Status o Drnkng Water Plant Volatons ...............................................................................2-42.4 Source Water Issues ..............................................................................................................2-52.5 Common Current Treatment Technologes .............................................................................2-52.6 Partculate/Turbdty Removal Technologes ...........................................................................2-8

2.6.1 Smple Fltraton .............................................................................................................2-82.6.2 Advanced Fltraton ........................................................................................................2-92.6.3 Reverse Osmoss (RO) .................................................................................................2-9

2.7 Chemcal Contamnant Removal............................................................................................2-92.7.1 Ion Exchange (IX) ..........................................................................................................2-92.7.2 Sorpton Technologes ....................................................................................................2-92.7.3 Other Technologes ......................................................................................................2-10

2.8 Bologcal Contamnant Removal .........................................................................................2-10

2.8.1 Chlornaton ..................................................................................................................2-102.8.2 Ultravolet Lght (UV) ....................................................................................................2-102.8.3 Ozone ..........................................................................................................................2-102.8.4 Other Dsnecton Technologes ...................................................................................2-10

2.9 Dstrbuton System Inrastructure ........................................................................................2-102.9.1 Storage Facltes..........................................................................................................2-142.9.2 Pumpng acltes .........................................................................................................2-162.9.3 Dstrbuton Lnes .........................................................................................................2-16

2.10 Remote Telemetry Supervsory Control and Data Acquston (SCADA) ..........................2-172.11 Key Questons ......................................................................................................................2-202.12 Reerences ...........................................................................................................................2-22

3.0 Regulatory Background ...............................................................................................................3-13.1 Sae Drnkng Water Act (SDWA) ...........................................................................................3-1

3.2 SDWA Provsons ...................................................................................................................3-13.2.1 Natonal Prmary Drnkng Water Regulatons (NPDWR) ...............................................3-13.2.2 Natonal Secondary Drnkng Water Regulatons (NSDWR) ..........................................3-23.2.3 Contamnant Canddate Lst (CCL) ................................................................................3-2

3.3 Current Regulatory Issues .....................................................................................................3-23.3.1 Perchlorate .....................................................................................................................3-23.3.2 Arsenc ...........................................................................................................................3-23.3.3 Complance wth Surace Water Treatment Rule ............................................................3-33.3.4 Stage 1 and 2 Dsnecton Byproducts (DBP) Rules .....................................................3-43.3.5 Proposed Ground Water Rule ........................................................................................3-53.3.6 Methyl Tertary Butyl Ether (MTBE) ................................................................................3-53.3.7 Radonucldes ................................................................................................................3-5

3.4 Source Water Assessments ...................................................................................................3-63.5 Wellhead Protecton ...............................................................................................................3-73.6 Vulnerablty Assessments (VA), Emergency Plannng and Securty .....................................3-73.7 Varances and Exemptons ....................................................................................................3-8

3.7.1 Small System Varances ................................................................................................3-83.7.2 Exemptons ....................................................................................................................3-8

3.8 DWSRF .................................................................................................................................3-93.9 Key Questons ........................................................................................................................3-93.10 Reerences .............................................................................................................................3-9

4.0 Source Water Issues....................................................................................................................4-14.1 Background ...........................................................................................................................4-14.2 Drnkng Water Research Program Mult-Year Plan ...............................................................4-1


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4.2.1 Long-Term Goals ...........................................................................................................4-14.2.2 Ongong and Future Research ......................................................................................4-1

4.3 Source Water Assessments ...................................................................................................4-24.3.1 Delneaton .....................................................................................................................4-24.3.2 Contamnaton Sources .................................................................................................4-24.3.3 Susceptblty Determnaton ..........................................................................................4-3

4.3.4 Publc Involvement .........................................................................................................4-34.3.5 Benets o Source Water Assessment Plans (SWAPs) .................................................4-34.3.6 Source Water Protecton ................................................................................................4-3

4.4 Other Source Water Assessment and Protecton Tools .........................................................4-34.4.1 Santary Survey .............................................................................................................4-34.4.2 Wellhead Protecton Program (WHPP) ..........................................................................4-3

4.5 Sustanablty o Communty Water Systems (CWSs) ............................................................4-44.6 EPA Source Water Assessment and Protecton Programs ....................................................4-44.7 Key Questons ........................................................................................................................4-44.8 Reerences .............................................................................................................................4-4

5.0 Treatment Processes ...................................................................................................................5-15.1 Introducton ...........................................................................................................................5-15.2 Packaged Fltraton ...............................................................................................................5-1

5.2.1 Fltraton .........................................................................................................................5-25.2.2 Bag Fltraton ..................................................................................................................5-35.2.3 Cartrdge Fltraton .........................................................................................................5-45.2.4 Membrane Fltraton .......................................................................................................5-45.2.5 Ultra Fltraton (UF) ........................................................................................................5-4

5.3 Dsnecton ............................................................................................................................5-45.3.1 Dsnecton by Chlornaton ...........................................................................................5-55.3.2 Dsnecton by Ozonaton ..............................................................................................5-65.3.3 Advanced Oxdaton Process or Dsnecton & Destructon ..........................................5-65.3.4 Dsnecton System Observatons .................................................................................5-7

5.4 Sorpton Technologes ............................................................................................................5-75.4.1 Ion exchange (IX) ...........................................................................................................5-85.4.2 Actvated Alumna (AA) and Iron-based Meda ..............................................................5-8

5.4.3 Powdered Actvated Carbon/Granular Actvated Carbon (PAC/GAC) ............................5-85.5 Lme Sotenng .......................................................................................................................5-95.6 Aordablty o Recommended Treatment Technologes and Protectveness o Publc Health

by Varance Technologes or Small Systems .........................................................................5-95.7 Pont-o-Use/Pont-o-Entry (POU/POE) Applcatons ..........................................................5-10

5.7.1 POU/POE Treatment Cost ...........................................................................................5-115.7.2 Use o POU/POE Treatment and Bottled Water n Small Systems ..............................5-11

5.8 Key Questons ......................................................................................................................5-135.9 Reerences ...........................................................................................................................5-13

6.0 Dstrbuton Systems ....................................................................................................................6-16.1 Dstrbuton System Overvew ................................................................................................6-16.2 Dstrbuton System Issues .....................................................................................................6-16.3 Inrastructure Issues ..............................................................................................................6-16.4 Operatonal Issues .................................................................................................................6-2

6.4.1 Bolm Growth................................................................................................................6-26.4.2 Ntrcaton .....................................................................................................................6-36.4.3 Fnshed Water Storage and Agng ................................................................................6-4

6.5 Contamnaton Events ............................................................................................................6-46.5.1 Cross-connecton Control ..............................................................................................6-46.5.2 Permeaton and Leachng ..............................................................................................6-56.5.3 Intruson and Inltratons ................................................................................................6-6

6.6 Dstrbuton System Summary................................................................................................6-66.7 Key Questons ........................................................................................................................6-76.8 Reerences .............................................................................................................................6-7


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7.0 Waste Resduals Generated by Small Systems ..........................................................................7-17.1 Introducton ............................................................................................................................7-17.2 Types o Waste Resduals and Dsposal ................................................................................7-17.3 Lqud Resduals Handlng & Dsposal ...................................................................................7-1

7.3.1 Drect Dscharge o Lquds ............................................................................................7-27.3.2 Indrect Dscharge o Lquds .........................................................................................7-3

7.3.3 Land Dsposal o Lquds ................................................................................................7-37.4 Sold Resduals ......................................................................................................................7-47.4.1 Land Dsposal o Solds .................................................................................................7-47.4.2 Land Applcaton o Solds .............................................................................................7-47.4.3 Incneraton o Solds and Lquds ..................................................................................7-4

7.5 Technologcally Enhanced Normally Occurrng Radoactve Materal (TENORM) Resduals 7-47.6 Conclusons and Future Research .........................................................................................7-57.7 Key Questons ........................................................................................................................7-57.8 Reerences .............................................................................................................................7-5

8.0 Homeland Securty/Emergency Response ..................................................................................8-18.1 Background and Drectves ....................................................................................................8-1

8.1.1 Boterrorsm Act .............................................................................................................8-18.1.2 Homeland Securty Presdental Drectve (HSPD)-7 - Crtcal Inrastructure Identcaton,

Prortzaton, and Protecton ..........................................................................................8-18.1.3 HSPD-8 - Natonal Preparedness ..................................................................................8-18.1.4 HSPD-9 - Deense o Unted States Agrculture and Food ...........................................8-18.1.5 HSPD-10 - BoDeense or the 21st Century ................................................................8-18.1.6 EPAs Strategc Plan or Homeland Securty ..................................................................8-2

8.2 EPAs Homeland Securty and Emergency Response Intatves and Resources ..................8-28.3 Threats and Rsks to the Water Supply ..................................................................................8-3

8.3.1 Chemcal and Radologcal Contamnants .....................................................................8-38.3.2 Bologcal Contamnants ................................................................................................8-38.3.3 Rsk Assessment and Mtgaton ....................................................................................8-3

8.4 Response Protocol Toolbox....................................................................................................8-38.5 Recommended Procedures or Securng Small Systems ......................................................8-48.6 Inrastructure and Bulk Water ................................................................................................8-4

8.7 Telemetry ...............................................................................................................................8-58.8 Early Warnng Systems or Drnkng Water Systems .............................................................8-58.9 Dsnecton n Dstrbuton Systems .......................................................................................8-68.10 Preparedness Assessment or Handlng Threats ...................................................................8-68.11 Local/State Emergency Plannng Commttees .......................................................................8-78.12 Alternatve Drnkng Water Supples n the Event o an Incdent ............................................8-78.13 Key Questons ........................................................................................................................8-88.14 Reerences .............................................................................................................................8-8

9.0 Remote Montorng and Control ...................................................................................................9-19.1 Introducton ............................................................................................................................9-19.2 Ratonale or Onlne Montorng .............................................................................................9-19.3 Selecton and Implementaton o Supervsory Control and Data Acquston (SCADA) Systems .. 9-19.4 Fundamentals o SCADA .......................................................................................................9-3

9.4.1 Montorng Equpment ....................................................................................................9-39.4.2 Control Equpment .........................................................................................................9-49.4.3 Data Collecton and Processng Unt(s) .........................................................................9-49.4.4 Communcaton Meda and Feld Wrng ........................................................................9-4

9.5 Remote Telemetry Applcatons or Small Systems ................................................................9-49.5.1 West Vrgna Remote Montorng Case Study ...............................................................9-49.5.2 Puerto Rco Remote Montorng Case Study .................................................................9-5

9.6 General Securty Issues wth Remote Montorng .................................................................9-79.7 Contamnaton Warnng Systems ...........................................................................................9-79.8 Key Questons ........................................................................................................................9-79.9 Reerences .............................................................................................................................9-7


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10.0 Summary ...................................................................................................................................10-110.1 Introducton ..........................................................................................................................10-110.2 Memorandum o Understandng (MOU) wth the Natonal Rural Water Assocaton (NRWA) ..... 10-110.3 Chapter-Specc Key Questons ..........................................................................................10-1


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List of Figures

Fgure 2.1 PWSs by system type ......................................................................................................2-2Fgure 2.2 Small systems by system type - FY2004 .........................................................................2-2Fgure 2.3 Number o people served by system type - All systems FY2004 ....................................2-2Fgure 2.4 Number o PWSs or each servce populaton group .......................................................2-3Fgure 2.5 Populaton served, servce connectons and number o systems - CWSs only FY2004 .2-3Fgure 2.6 Drnkng water system owners FY 2004-159,796 total systems ...................................2-4Fgure 2.7 Volatons reported FY2005 .............................................................................................2-4Fgure 2.8 Drnkng water system volatons or all system szes - FY2005 ......................................2-5Fgure 2.9 Volatons reported or systems servng populaton rom 25-10,000 - FY2005 ......................2-5Fgure 2.10 MCL volatons vs. populatons served FY2005 ...............................................................2-6Fgure 2.11 Source water comparson by sze category .....................................................................2-6Fgure 2.12 Percentage o ground water plants usng each treatment technque ...............................2-7Fgure 2.13 Percentage o surace water plants usng each treatment technque ..............................2-7Fgure 2.14 Percentage o mxed plants usng each treatment technque ..........................................2-8Fgure 2.15 Percentage o CWSs wthn each system servce populaton category that have a

clearwell type nshed water storage .............................................................................2-15

Fgure 2.16 Average number o mles o dstrbuton mans (publc vs. prvate systems) ..................2-16Fgure 2.17 Publc vs. prvate average annual ppe replaced (or CWSs) 5-year average ................2-17Fgure 2.18 System servce connectons ..........................................................................................2-18Fgure 2.19 Average number o mles o ppes n dstrbuton systems prvately owned .......................2-18Fgure 2.20 Average number o mles o ppes n dstrbuton systems publcly owned ........................2-19Fgure 2.21 Percentage o ppe n each age category or CWSs ......................................................2-19Fgure 2.22 Percentage o Ppe n Each Age Category by Source or CWSs...................................2-20Fgure 2.23 Percentage o ground water CWS plants (lackng 24/7 operator presence) that have

SCADA systems or process montorng or control........................................................2-21Fgure 2.24 Percentage o surace water CWS plants (lackng 24/7 operator presence) that have

SCADA systems or process montorng or control........................................................2-21Fgure 3.1 Structure o the DWSRF program ...................................................................................3-7

List of Tables

Table 2.1 Technologes or norganc contamnants ......................................................................2-11Table 2.2 Technologes or volatle organc contamnants .............................................................2-11Table 2.3 Technologes or synthetc organc contamnants ..........................................................2-12Table 2.4 Technologes or radonucldes ......................................................................................2-12

Table 2.5 Technologes or dsnecton ..........................................................................................2-13Table 2.6 Technologes or ltraton ...............................................................................................2-13Table 2.7 Complance technology or the Total Colorm Rule .......................................................2-14Table 2.8 Percentage o CWSs (wthn each system servce populaton category) that have treated-

water storage, beore dstrbuton system. .....................................................................2-15Table 2.9 Percentage o CWSs (wthn each system servce populaton category) that have treated-

water storage wthn the dstrbuton system. .................................................................2-15Table 2.10 System servce connectons by system owner ..............................................................2-20Table 3.1 Reduced montorng or radonucldes .............................................................................3-6Table 5.1 Surace Water Treatment Rule complance technologes or dsnecton ........................5-1Table 5.2 Surace Water Treatment Rule complance technologes or ltraton ..............................5-2Table 5.3 Summary o dsnectant characterstcs relatng to bocdal ecency ..................................... 5-5Table 5.4 Key Feature Summary o commonly used POU/POE technologes ..............................5-12

Table 9.1 Amenablty o treatment technologes to remote montorng used or small water ...................9-2Table 9.2 Cost estmates o SCADA system components ..............................................................9-5Table 9.3 Puerto Rco remote montorng system component costs ...............................................9-6


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Fgure 5.1 Partcle sze dstrbuton o common contamnants and assocated ltraton technology....5-3Fgure 5.2 Clogged Prelter ..............................................................................................................5-3Fgure 6.1 Dstrbuton System as a Reactor ..................................................................................6-3Fgure 6.2 Negatve Pressure Transent Assocated wth a Power Outage .......................................6-6Fgure 7.1 Federal regulatons governng the dsposal o resduals..................................................7-2Fgure 9.1 Possble layout o remote montorng system ..................................................................9-3

Fgure 9.2 Schematc layout o the small sytstem n San German, Puerto Rco ..............................9-6


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AA Actvated Alumna

ABPA Amercan Backfow PreventonAssocaton

ANSI Amercan Natonal StandardsInsttute

AOP Advanced Oxdaton Processes

APG Annual Perormance Goal

APM Annual Perormance Measure

ASCE Amercan Socety o Cvl Engneers

ASDWA Assocaton o State Drnkng WaterAdmnstrators

AWQC Ambent Water Qualty Crtera

AWWA Amercan Water Works Assocaton

BAT Best Avalable Technology

BMP Best Management Practces

CCL Contamnant Canddate Lst

CESQG Condtonally Exempt Small QuanttyGenerator

CFR Colorm Rule

CSO Combned Sewer Overfows

CT Contact Tme

CWA Clean Water Act

CWS Communty Water System

DBP Dsnecton By-Product

DBPR Dsnecton By-Product RuleDE Datomaceous Earth

DHS Department o Homeland Securty

DWSRF Drnkng Water State Revolvng Fund

EBCT Empty Bed Contact Tme

ED Electrodalyss

EPA Envronmental Protecton Agency

EPCRA Emergency Plannng and CommuntyRght-to-Know Act

EPTDS Entry Pont to the DstrbutonSystem

ERP Emergency Response Plan

ETV Envronmental TechnologyVercaton

FBRR Flter Backwash Recycle Rule

GAC Granular Actvated Carbon

GFH Granular Ferrc Hydroxde

GPM Gallons per Mnute

GWUDI Ground Water Under Drect Infuence

HAA5 Haloacetc Acds

Acronyms and Abbreviations

HFGP Horzontal Flow Gravel Prelter

HSPD Homeland Securty PresdentalDrectve

IT Inormaton TechnologyIUP Intended Use Plan

IX Ion Exchange

LEPC Local Emergency PlannngCommttee

LGR Local Government Rembursements

LLRW Low-level Radoactve Waste

LT1ESWTR Long Term 1 Enhanced SuraceWater Treatment Rule

LT2ESWTR Long Term 2 Enhanced SuraceWater Treatment Rule

M/R Montorng and Reportng

MCL Maxmum Contamnant Level

MCLG Maxmum Contamnant Level Goal

MF Mcroltraton

MGD Mllon Gallons per Day

MHI Medan Home Income

MOU Memorandum o Understandng

MRDLG Maxmum Resdual Dsnectant LevelGoal

MTBE Methyl Tertary Butyl Ether

MWCO Molecular Weght Cut-oNAS Natonal Academy o Scence

NDWAC Natonal Drnkng Water AdvsoryCouncl

NDWC Natonal Drnkng WaterClearnghouse

NRMRL Natonal Rsk ManagementResearch Laboratory

NF Nanoltraton

NHSRC Natonal Homeland SecurtyResearch Center

NIPDWR Natonal Interm Prmary DrnkngWater Regulatons

NOM Natural Organc Matter

NPDES Natonal Polluton DschargeElmnaton System

NPDWR Natonal Prmary Drnkng WaterRegulatons

NRC Natonal Research Councl (alsoused or Nuclear RegulatoryCommsson n Chapter )

NRWA Natonal Rural Water Assocaton


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NSDWR Natonal Secondary Drnkng WaterRegulaton

NSF Natonal Santaton Foundaton

NTNCWS Non-Transent Non-Cmmunty WaterSystem

NTU Nephelometrc Turbdty Unts

O3 Ozone

O&M Operaton and Mantenance

OCMS Onlne Contamnant MontorngSystem

OEM Oce o Emergency Management

ORD Oce o Research and Development

PAC Powdered Actvated Carbon

PDCO Pore Dameter Cut-o

PDD Presdental Decson Drectve

POE Pont-o-Entry

POTW Publcly Owned Treatment WorksPOU Pont-o-Use

ppb Parts per bllon

PTA Packed Tower Aeraton

PVC Polyvnyl Chlorde

PWS Publc Water System

RCRA Resource Conservaton andRecovery Act

RD Reerence Dose

RMCL Recommended MaxmumContamnant Level

RO Reverse Osmoss

RPTB Response Protocol Toolbox

SAB Scence Advsory Board

SBA Strong Base Anon

SCADA Supervsory Control and DataAcquston

SDWA Sae Drnkng Water Act

SDWIS State Drnkng Water InormatonSystem

SEMS Securty Emergency ManagementSystems

SEMS/ICS Standardzed EmergencyManagement System/IncdentCommand System

SSCT Small System ComplanceTechnology

SSF Slow Sand Flter

SWAP Source Water Assessment Plan

SWP Source Water Protecton

SWR Sold Waste Resduals

SWTR Surace Water Treatment Rule

TCLP Toxcty Characterstc LeachngProcedure

TCR Total Colorm Rule

T&E Test and Evaluaton

TENORM Technologcally Enhanced NaturallyOccurrng Radoactve Materal

THM Trhalomethane

TMDL Total Maxmum Daly Load

TNCWS Transent Communty Water System

TOC Total Organc Carbon

TT Treatment Technque

TTHM Total Trhalomethanes

UCMR Unregulated ContamnantsMontorng Rule

UF Ultraltraton

USACE Unted States Army Corps oEngneers

UV Ultravolet lght

VA Vulnerablty Assessment

VOC Volatle organc compound

WBA Weak Base Anon

WHP Well Head Protecton

WHPA Well Head Protecton Area

WHPP Well Head Protecton Plan

WSD Water Securty Dvson

WSWRD Water Supply and Water ResourcesDvson


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Ths report was submtted n partal ulllment o contract number EP-C-04-034 WA1-03 and 2-03 by

Shaw Envronmental, Inc. under the sponsorshp o the Unted States Envronmental Protecton Agency.

The authors extend ther thanks to EPA Regon 5 revewers: Ronald Kovach, Mguel Del Toral, Sahba

Rouhan, and Wllam Spauldng. The authors would also lke to thank Erc Bssonette, Jenny Belansk,

and Francne St. Dens n the EPAs Oce o Water or ther comments. Lastly, the authors extend ther

deepest apprecaton to the Natonal Rural Water Assocaton, speccally Jerry Bberstne and Dr. John

Regner or ther comments and suggestons. Collaboraton wth NRWA s made possble through a

Memorandum o Understandng between the EPA and NRWA.

Acknowledgements


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Chapter 1Introduction

1.1 Goals and Objectves o ths

DocumentThe objective o this document is to summarize the

existing status o drinking water supply in the United

States (U.S.) with particular emphasis on small sys-

tems (i.e., systems serving less that 10,000 people).

This document will then orm the backdrop to crat a

research plan that will serve as a roadmap or research-

ers in the U.S. Environmental Protection Agen-

cys (EPAs), Oce o Research and Development

(ORD), Water Supply and Water Resources Division

(WSWRD) by providing ocus and direction to the

WSWRDs research eorts. Specically, the Strategy

or Small Systems Research aims to:

Provide timely and appropriate research that willcontribute to small system management schemesor reducing Sae Drinking Water Act (SDWA)violations and public health risks.

Chart a research course that will drive newtechnologies and improve existing technologieswith emphasis on costs/benets (reduce costsand increase simplicity).

This strategy document ocuses on the current state o

the ollowing items as they pertain to small systems

and on the direction o uture research activities orthese items:

Source water issues

Monitoring/Reporting

Treatment processes

Distribution systems

Residuals Management

Homeland Security

Overall Utility Management

All research planning in the document should be in

the context o the six-year review o National Primary

Drinking Water Regulations (NPDWR) and the ve-

year update o the Contaminant Candidate List (CCL).

Note that the last NPDWR review was in August 2002

and the last CCL update was in February 2005.

1.2 Document OrganzatonThis document is organized into the ollowing sec-

tions:

Chapter 1 Introduction This section presents a

brie introduction to this report

Chapter 2 Current Status and Issues o Small

Drinking Water Systems

Chapter 3 Regulatory Background This section

presents a brie background o the

regulations impacting operators o small

drinking water systems

Chapter 4 Source Water Issues

Chapter 5 Treatment Processes

Chapter 6 Distribution Systems

Chapter 7 Waste Residuals

Chapter 8 Homeland Security/Emergency Response

Chapter 9 Remote Telemetry

Chapter 10 Summary


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Chapter 2Current Status andIssues o Small

Drinking WaterSystems

2.1 IntroductonThis Chapter provides an introduction to the current

status o small drinking water systems and the issues

acing small systems in maintaining compliance and

providing sae drinking water to the populace served

by these systems. The chapter begins with a detailed

snapshot prole (Section 2.2) o the distribution o

small systems based on the number o people served

and then provides brie overviews on the compliance

status (Section 2.3) o these small systems and source

water issues (Section 2.4). This chapter also provides

a brie introduction to the ollowing topics:

Common technologies currently used by smallsystems to treat source water to meet drinkingwater standards (Sections 2.5, 2.6, 2.7 and 2.8),

Distribution system inrastructure (including

storage acilities, pumping acilities and

distribution lines) currently employed by small

systems (Section 2.9),

Status o the use o remote telemetry to monitor

small systems operation (Section 2.10)

Key questions to be answered through ongoing

research (Section 2.11)

2.2 Prole o Small Systems n theU.S.

The EPAs Sae Drinking Water Inormation System

(SDWIS) estimates that there are 159,796 public

water systems (PWSs) in the U.S. (EPA, 2005a). The

SDWIS is a living database and portions o it are pe-

riodically updated. The prole data presented in thissection includes a conglomeration o data extracted

periodically rom the SDWIS during the preparation

o this report (between 2004 and 2005). Depend-

ing upon when the data was extracted and when the

underlying SDWIS was updated, the exact numbers

and percentages or individual categories described

in the gures may vary slightly. However, the over-

all trends and statistics are consistent throughout the

period during which the SDWIS was updated. Most

o the SDWIS updates were perormed between the

years 2000 and 2005; where inormation is available,

the specic year o the data presented is clearly identi-

ed. Unless otherwise stated, the graphs and statistics

relating to system types, population served, ownership,

violations, sizes, treatment scheme, piping distance

were all developed using the Pivot tables underlying

SDWIS (EPA, 2005b). Pivot tables are multidimen-sional spreadsheets/databases that provide analytical

processing capability. The Pivot tables allow or quick

summarization, cross-tabulation, and analysis o large

amounts o data.

A PWS is any water system which provides water to

at least 25 people or at least 60 days annually. These

PWSs provide water rom wells, rivers and other

sources to the majority (~85%) o the population in

the U.S. and territories (EPA, 2005b). The PWSs are

classied as ollows:

Community Water Systems (CWS) A watersystem which supplies drinking water to 25 ormore o the same people year-round in theirresidences.

Non-Transient Non-Community Water Systems(NTNCWS) A water system which supplieswater to 25 or more o the same people atleast six months per year in places other thantheir residences. Some examples are schools,actories, oce buildings, and hospitals thathave their own water systems.

Transient Non-Community Water Systems

(TNCWS) A water system which provideswater in a place such as a gas station orcampground where people do not remain orlong periods o time. These systems do not haveto test or treat their water or contaminants thatpose long-term health risks because ewer than25 people drink the water over a long period (6months/year). They still must test their wateror microbes and several chemicals.

There are diering standards or PWSs o dierent

sizes and types. Most (approximately 55%) o the

PWSs in the U.S. belong to the TNCWS variety (EPA,

2005b). Figure 2.1 illustrates the percentage break-down o the dierent system types. Most o these

systems represent the very small category (serving 25

500 people). Figure 2.2 shows the breakdown o

the number o small systems by system type. For the

purposes o this document, a small system is dened

as a CWS, NTNCWS, or TNCWS serving ewer than

10,000 persons (please note that a PWS serving 3001-

10,000 persons may be reerenced as medium in some

graphics).

While most o the PWSs are TNCWSs, the vast majority


20/1012-2

o people using PWSs actually obtain their water rom

CWSs. As illustrated in Figure 2.3, approximately

90% o all people using public drinking water systems

obtain their water rom CWSs. Figure 2.4 shows the

breakdown o system types by population category.

As indicated, approximately 84% o CWSs serve

populations o 3,300 or less. TNCWSs are mostlyrepresented in the very small category.

There are 159,796 CWSs, which includes both large

and small systems. There exists a great discrepancy

between the number o systems and the distribution o

the population served. Very small CWSs account or

57% o the total number o systems, although these

33%

12%

55%CWS

NTNCWS

TNCWS

Figure 2.1 PWSs by system type (EPA,2005b).

System Type

NumberofSystems

Very Small (25-500)

Small (501-3300)

Medium (3301-10,000)

30,

006

14,

212

4,707

16,545

2,720

96

84,

750

2,700

110

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

CWS NTNCWS TNCWS

Figure 2.2 Small systems by system type - FY2004 (EPA, 2005b).

272,

495,

677

5,

933,

320

18,

484,

66

0

0

50,000,000

100,000,000

150,000,000

200,000,000

250,000,000

300,000,000

Numbero

fSystems

CWS NTNCWS TNCWS

Figure 2.3 Number o people served by system type - All systems FY2004 (EPA, 2005b).


21/1012-3

systems serve less than 2 percent o the population

served by CWSs. In contrast, the large and very large

systems account or roughly 7 percent o the total

number o systems but serve over 80% o the popula-

tion. Figure 2.5 shows a breakdown o population

served, number o service connections, and number o

systems or CWSs by system size.

PWSs are owned by various governmental, tribal, pub-

lic, or private entities. There is a relationship between

system size and ownership, with the vast majority o

very small systems (25-500 persons served) being

privately owned and a majority o larger systems being

owned by local government. Figure 2.6 shows the

breakdown o ownership or all systems.

CWS

NTNCWS

TNCWS

30

,006

16

,545

84

,740

14

,212

2,

720

2,

700

4,

707

96

110

3,

541

14

29

372

0 4

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

NumberofSystem

s

Very Small

(25-500)

Small

(501-3,300)

Medium

(3,301-10,000)

Large

(10,001-100,000)

Very Large

(>100,000)

System Type

Figure 2.4 Number o PWSs or each service population group (EPA, 2005b).

0

20,000,000

40,000,000

60,000,000

80,000,000

100,000,000

120,000,000

140,000,000

System Size

Population/NumberofService

Connections

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

Number

ofSystems

2,594,626 7,333,945 9,473,250 32,152,151 32,984,472

4,957,131 20,137,604 27,346,264 99,808,668 120,246,010

30,006 14,212 4,707 3,541 372

Very Small Small Medium Large Very Large

Service Connections

Population

Systems

Figure 2.5 Population served, service connections and number o systems - CWSs onlyFY2004 (EPA, 2005b).


22/1012-4

2.3StatusofDrinkingWaterPlant

ViolationsThe SDWIS classifes drinking water system violations

into the ollowing our major categories:

Maximum contaminant level (MCL) violations;

Chapter 3 discusses MCLs in detail.

Treatment Technique (TT) violations; according

to EPA, a treatment technique is a required

process intended to reduce the level o a

contaminant in drinking water. A ew examples

o treatment techniques are disinection,

fltration, and aeration (urther discussed in

Chapter 3).

Monitoring or Reporting (M/R) Violations.

These violations are primarily record-keeping

issues.

Violations other than the three types mentioned

above.

Figure 2.7 shows the breakdown o system violations

or all PWSs. This fgure shows that most PWS viola-

tions are attributed to M/R.

Figure 2.8 shows system violations by population

served, number o systems, and violation type. Verysmall systems have the largest number o violations,

with the vast majority o these being M/R violations.

Figure 2.9 shows the breakdown o system violations

or small systems. Figure 2.9 looks very similar to

Figure 2.8 because the total violation statistics are

overwhelmingly dominated by small systems. Very

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

100,000

NumberofSystems

Very Small 25-500

Small 501-3,300

Medium 3,301-10,000

Large 10,001-100,000

Very Large >100,000

Federal Govt Local Govt Tribal Govt Private Public/Private State Govt Unknown

3,374 14,522 583 101,108 5,580 4,328 1,796

307 10,755 210 6,210 885 959 306

106 3,681 32 658 145 130 161

71 2,878 6 407 69 43 110

0 312 0 53 6 4 1

Figure 2.6 Drinking water system owners FY 2004-159,796 total systems (EPA, 2005b).

7.90%

0.0004%

1.67%

86.02%

4.40%

MCL

Maximum Residual DisinfectantLevel

Treatment Technique

Monitoring or Reporting

Other

Figure 2.7 Violations reported FY2005 (EPA, 2005b).


23/1012-5

small systems also experience the greatest number o

MCL and TT violations. In addition, PWSs experi-

enced a total o 145,962 MCL violations (2005 data),

with 135,495 (93%) o the violations attributed to

small systems (population served less than 3,300).

Figure 2.10 illustrates the relationship between the

number o MCL violations and population served.

Very small systems (those serving 25 to 500 people)

experience approximately one MCL violation orevery 80 persons served, which is the highest ratio o

all system service population categories. In compari-

son, very large systems (population served greater

than 100,000) experience approximately one MCL

violation or every 196,204 persons served.

2.4 Source Water IssuesPWSs obtain drinking water rom either surace or

ground water sources. Over 90% o the PWSs obtain

their water rom ground water sources, with a vast

majority (87%) o those using ground water being

represented by small systems (serving a populationless than 3,300). Figure 2.11 shows the distribution o

water sources, by each o the ve size categories.

Source waters rom streams, rivers, lakes, or aquiers

are used to supply private water systems and PWSs.

The source water moves within a watershed via

overland fow (i.e., surace water), shallow subsurace

storm fow or ground water fow. The surace water

is vulnerable to contamination rom both surace

runo and ground water inltration. Ground water

can become contaminated through inltration rom

the surace, incursion o contaminants rom under-

ground storage tanks, septic systems, injection wells,

or by naturally occurring substances in the soil or rock

through which it fows. These issues are discussed in

urther detail in Chapter 4.

2.5 Common Current TreatmentTechnologes

Most PWSs treat drinking water so that it will be sae

and palatable or the consumer. The application o a

specic TT depends on source water quality, system

size, and operator sophistication. Figures 2.12, 2.13

and 2.14 illustrate the variety and percent predomi-

nance o individual TTs used by the dierent size

classes o PWSs.

Very Small 25-500

Small 501-3,300

Medium 3,301-10,000

Large 10,001-100,000

Very Large >100,000

115861

19634

5136

5111

220

5 20 0 01

5732

8535

2733

3320

519

1307260

183057

43051

48078

7176

66847

10438

2366

1565

117

0

200000

400000

600000

800000

1000000

1200000

1400000

NumberofViolations

MCL MaximumResidual

Disinfectant Level

Treatment

Technique

Monitoring or

Reporting

Other

Figure 2.8 Drinking water system violations or all system sizes - FY2005 (EPA, 2005b).

7.90%

0.0004%

1.52%

86.11%

4.47%

MCL

Maximum Residual Disinfecta

Level

Treatment Technique

Monitoring or Reporting

Other

Figure 2.9 Violations reported or systems servingpopulation rom 25-10,000 - FY2005 (EPA, 2005b).


24/1012-6

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

NumberofViolations

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

PopulationinViolation

Violations

Population

Very Small

(25-500)

Small

(501-3,300)

Medium

(3,301-10,000)

Large

(10,001-100,000)

Very Large

(>100,000)

Figure 2.10 MCL violations vs. populations served FY2005 (EPA, 2005b).

125,5

87

5,704 1

5,514

4,

118

2,

826

2,

087

1,

493

2,

091

78

298

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

NumberofSystems

Very Small(25-500)

Small(501-3,300)

Medium(3,301-10,000)

Large(10,001-100,000)

Very Large(>100,000)

Ground Water

Surface Water

Figure 2.11 Source water comparison by size category (EPA, 2005b).


25/1012-7

Figure 2.12 Percentage o ground water plants using each treatment technique (EPA, 2002).

0

10

20

30

40

50

60

70

80

90

Percen

tage

100 orless

101-500

501-3,300

3,301-10,000

10,001-50,000

50,001-100,000

100,001-500,000

Over500,000

System Service Population

Disinfection with no

additional treatment

Other chemical addition

Ion exchange,

activated alumina,

aeration

Filtration other than

direct or conventional

Direct filtration

Conventional filtration

Membranes

Softening

Figure 2.13 Percentage o surace water plants using each treatment technique (EPA, 2002).

0

10

20

30

40

50

60

70

Percen

tage


100 orless

101-500

501-3,300

3,301-10,000

10,001-50,000

50,001-100,000

100,001-500,000

Over500,000




Ion exchange,

activated alumina,

aeration



Direct filtration


Membranes

Softening


26/1012-8

Figure 2.14 Percentage o mixed plants using each treatment technique (EPA, 2002).

0

10

20

30

40

50

60

70

80

90

100




Ion exchange,activated alumina,

aeration



Direct filtration


Membranes

Softening

Percentage


100 orless

101-500

501-3,300

3,301-10,000

10,001-50,000

50,001-100,000

100,001-500,000

Over500,000

The individual TTs are designed to be eective in

removing one or more types o contaminants includ-

ing particulate, chemical and biological contaminants.

Depending upon the type o contamination present in

the source water, one or more TTs may be applied by

the PWS to provide sae drinking water to consum-

ers. A general discussion o available TTs to remove

particulate (Section 2.6), chemical contaminants (Sec-

tion 2.7) and biological contaminants (Section 2.8)

is presented in this Chapter. A more comprehensive

discussion o TTs is presented in Chapter 5.

2.6 Partculate/Turbdty RemovalTechnologes

Particulate and turbidity removal is an almost univer-

sally used technology or the primary treatment o

drinking water. The primary means o particulate re-

moval is by means o simple ltration either by using

media ltration (e.g., sand lter) or by the use o bag

and/or cartridge lters. Advanced ltration techniques

include membrane ltration and other technologies.

This section provides a very brie overview o these

technologies.

2.6.1 Simple FiltrationFiltration is a process or removing particulate matter

rom water by passage through porous media. There

are numerous types o ltration processes. Some com-

mon ltration processes are summarized below (these

descriptions are available in many standard text books,

where applicable reerences have been provided or

specic usage and equipment descriptions):

Slow Sand Filtration is a process where untreatedwater percolates slowly down through a layero ne sand, then through a layer o gravel, andultimately collects in a system o underdrains.A biological layer or schmutzdecke orms onthe surace o the sand, trapping small particles.The schmutzdecke also helps to degrade organic

material in the water.Diatomaceous Earth (DE) also known as pre-

coat or diatomite ltration, can be used todirectly treat low turbidity raw water suppliesor chemically coagulated, more turbid watersources. DE lters consist o a pre-coat layer oDE, approximately 1/8-inch thick, supported bya septum or lter element (EPA, 1998).

Conventional Filtration is a method o treatingwater to remove particulates. The methodconsists o the addition o coagulant chemicals,fash mixing, coagulation-focculation,

sedimentation and ltration.

Direct Filtration also known as dead-endltration is similar to conventional ltrationwith the sedimentation process omitted.

Packaged Filtration consists o all o the ea-

tures o ltration chemical addition, focculation,

sedimentation, ltration mounted as a unit on a

rame or simple hookup o pipes and services. It

is most widely used to treat surace water supplies

or removal o turbidity, color, and coliorm organ-


27/1012-9

isms with ltration processes. Packaged ltration is

oten used to treat small community water supplies,

as well as supplies in recreational areas, state parks,

construction sites, ski areas, and military installations

(NDWC, 1996).

2.6.2 Advanced FiltrationMembrane Filtration Membrane ltration (as

dened under the Long Term 2 EnhancedSurace Water Treatment Rule-LT2ESWTR) isa pressure-driven separation process in whichparticulate matter larger than 1-micrometer isrejected by an engineered barrier, primarilythrough a size-exclusion mechanism and whichhas a measurable removal eciency or atarget organism that can be veried throughthe application o a direct integrity test (EPA,2003a). Some common types o membraneltration are:

Microltration is a pressure-driven membraneltration process that typically employshollow-ber membranes with a pore sizerange o approximately 0.1 0.2 micrometers(nominally 0.1 micrometers) (EPA, 2003a).

Ultraltration is a pressure-driven membraneltration process that typically employshollow-ber membranes with a pore size rangeo approximately 0.01 0.05 micrometer(nominally 0.01 micrometers) (EPA, 2003a).

Nanoltration is a pressure-driven membrane

separation process that employs the principleso reverse osmosis to remove dissolvedcontaminants rom water and is typicallyapplied or membrane sotening or the removalo dissolved organic contaminants (EPA,2003a).

2.6.3 Reverse Osmosis (RO)RO resembles membrane ltration processes in that

contamination rom water is removed by the use

o a membrane. However, unlike membrane ltra-

tion where water is orced through a media leaving

behind the contaminant, RO uses hydraulic pressure

to oppose the liquid osmotic pressure across a semi-permeable membrane, orcing the water rom the

concentrated solution side to the dilute solution side.

Thus, the RO membrane allows the passage o the

solvent (water) but not the dissolved solids (solutes).

Since the membrane is non-porous, the water does

not travel through pores, but rather dissolves into

the membrane, diuses across, and then dissolves

into the permeate (EPA, 1998b). RO can eectively

remove nearly all contaminants rom water includ-

ing arsenic (III), arsenic (V), barium, cadmium,

chromium (VI), radium, natural organic substances,

pesticides, and microbiological contaminants. The

liquid produced is demineralized water.

2.7 Chemcal ContamnantRemoval

Chemical contaminants are commonly removed using

ion exchange and sorption technologies. This sectionprovides a brie overview o these technologies along

with other TTs that are used to remove chemical con-

taminants in drinking water.

2.7.1 Ion Exchange (IX)Ion exchange involves the selective removal o charged

inorganic species rom water using an ion-specic

resin. The surace o the ion exchange resin contains

charged unctional groups that hold ionic species by

electrostatic attraction. As water containing undesired

ions passes through a column o resin beds, charged

ions on the resin surace are exchanged or the unde-

sired species in the water. The resin, when saturatedwith the undesired species, is regenerated with a solu-

tion o the exchangeable ion (EPA, 1998b).

Generally, resins can be categorized as anion exchange

or cation exchange resins. Anion exchange resins se-

lectively remove anionic species such as nitrate (NO3),

sulate (SO42), or fuoride (F) and exchange them

or hydroxyl (OH) or chloride (Cl) ions. Cation

exchange resins are used to remove undesired cations

such as cadmium (Cd2+) or Barium (Ba2+) rom water

and exchange them or protons (H+), sodium ions

(Na+) or potassium ions (K+) (EPA, 1998b). The pH

o the source water is important when employing IX

resins. For example, uranium exists in water at pH

levels o 6.0 and higher as a carbonate complex, which

is an anion, and thus has a strong anity or anion

resin in the chloride orm. The process is eective

on water with a pH o up to 8.2. A higher pH could

result in uranium precipitation; a lower pH changes

the nature o uranium to non-ionic and/or cationic spe-

cies, which would prevent the exchange reaction rom

operating eciently. It is advisable to control the inlet

water pH to above 6.0. Sudden pH changes to below

5.6 can dump any previously removed uranium o the

resin (DeSilva 1996).

2.7.2 Sorption TechnologiesAdsorption involves the removal o ions and molecules

rom solution and concentrating them on the surace

o adsorbents. Adsorption is driven by the interacial

orces o the ions and the adsorbent. Adsorption media

employed at drinking water plants include granular

activated carbon, activated alumina, and iron media.

Sorption technologies are used or the removal o

organics, taste and odor, and inorganic contaminants

(such as arsenic).


28/1012-10

2.7.3 Other Technologies

Aeration Technologies Aeration technologies aretypically used or removal o volatile organiccompounds and or removal o excess carbondioxide. In general, aeration is the contacting othe water with air wherein the target chemical

is transerred rom the water to the air stream.There are a number o methods used or themixing o air and water including packedaeration towers, shallow tray air strippers,mechanical aeration, and spray aeration.

Sotening Sotening is used to remove calciumand magnesium ions rom water. Types otechnologies used include ion exchange,chemical focculation, and precipitation.

Electrodialysis (ED) Another less commonlyused technology or chemical removal is ED,which is a process in which ions are transerred

through ion-selective membranes by means oan electromotive orce rom a less concentratedsolution to a more concentrated solution (EPA,2003a). ED is very eective in removingfuoride and nitrate, and can also remove barium,cadmium, and selenium (NDWC, 1997).

Reverse Osmosis Can remove many chemicalcontaminants eectively. See Section 2.6.3 orurther details.

2.8 Bologcal Contamnant

RemovalDisinection is a process or reducing the number opathogenic microbes in water and is required by the

Surace Water Treatment Rule (SWTR) or all PWSs

that obtain their water rom surace water or ground

water under the infuence o surace water. In addition,

PWSs must maintain a residual level o disinectant

in the distribution system per 40 CFR 141.72. It is

required that, at the point where the water enters the

distribution system, the residual disinection con-

centration not all below 0.2 mg/L. In addition, the

residual disinection concentration must be maintained

throughout the distribution system such that non-de-

tection results are measured in no more than 5% o thesamples collected each month.

2.8.1 ChlorinationChlorine is the most common method used or disin-

ection. There are a number o methods o delivery

and chemical reactions utilized or chlorination. These

include chlorine gas, chloramines, chlorine dioxide,

and sodium hypochlorite. The goal o all these meth-

ods is to release ree chlorine in the orm o hypochlo-

rite, or in the case o chloramines, combined available

chlorine (NH2Cl and NHCl2).

2.8.2 Ultraviolet Light (UV)Contaminated water is exposed to UV light, which

penetrates the cell walls o an organism. UV disrupts

the organisms genetic material which inactivates the

organism. A special lamp generates the radiation that

creates UV light by striking an electric arc through

low-pressure mercury vapor (low-pressure UV). Thislamp emits a broad spectrum o radiation with intense

peaks at UV wavelengths o 253.7 nanometers (nm)

and a lesser peak at 184.9 nm. Research has shown

that the optimum UV wavelength range to destroy bac-

teria is between 250 nm and 270 nm. At shorter wave-

lengths (e.g.185 nm), UV light is powerul enough to

produce ozone, hydroxyl, and other ree radicals that

destroy bacteria (NDWC, 2000).

2.8.3 OzoneOzone is a colorless, very unstable gas that is eective

as an oxidizing agent in removing bacteria with a rela-

tively short exposure time. Since the gas is unstableand has a very short lie, ozone generators are used to

produce ozone gas on site.

2.8.4 Other Disinection TechnologiesThere are a number o other disinection technologies

used in ultra pure water applications, but are not ap-

plicable nor typically used in water supply situations.

These include ammonium compounds, non-oxidizing

biocides (i.e. ormaldehyde), heat, and peracetic acid.

Tables 2.1, 2.2, 2.3, 2.4, 2.5 and 2.6 present candidate

technologies or treatment o inorganic contaminants,

volatile organic contaminants, synthetic organic con-taminants, radionuclides, disinection, and ltration

respectively. Table 2.7 identies compliance technol-

ogy or the Total Coliorm Rule.

2.9 Dstrbuton SystemInrastructure

Drinking water is delivered rom a water treatment

acility to its customers by means o a distribution

system. This inrastructure generally consists o a

combination o three key elements: treated water stor-

age acilities (e.g., ground storage tanks, elevated stor-

age tanks, standpipes, hydropneumatic tanks), pump-ing acilities (e.g., booster pumps, piping, control,

pump building), and the distribution lines (e.g., piping,

valves, re hydrants, meters). Most o the distribution

system inrastructure is located underground, making

it more dicult to detect problems such as leaks and

pipe deterioration. Various standards and procedures

or design, material selection, plumbing code, opera-

tion, and maintenance have been established that help

maintain the integrity o the system (EPA, 1999). The

distribution system issues acing small systems are


29/1012-11

Table 2.1 Technologies or inorganic contaminants (NDWC, undated).

Unit Technology Limitations*Operator Skill

Level Required Raw Water Quality Range

1. Actvated Alumna (a) AdvancedGround waters, competng anon concentratons wllaect run length.

2. Ion Exchange IntermedateGround waters wth low total dssolved solds, com-petng on concentratons wll aect run length.

3. Lme Sotenng (b) Advanced Hard ground and surace waters

4. Coagulaton/ Fltraton (c) Advanced Can treat wde range o water qualty.

5. Reverse Osmoss (RO) (d) Advanced Surace water usually requre preltraton.

6. Alkalne Chlornaton (e) Basc All ground waters.

7. Ozone Oxdaton Intermedate All ground waters.

8. Drect Fltraton Advanced Needs hgh raw water qualty.

9. Datomaceous Earth Fltraton Intermedate Needs very hgh raw water qualty.

10. Granular Actvated Carbon Basc Surace waters may requre preltraton.

11. Elecrodalyss Reversal Advanced Requres preltraton or surace water.

12. Pont o Use (POU)-IX () Basc Same as Technology #2.

13. POU-RO () Basc Same as Technology #5.

14. Calcum Carbonate Precptaton (g) Basc Water wth hgh levels o alkalnty and calcum.

15. pH and Alkalnty Adjustment(chemcal eed) (g) Basc All ranges.

16. pH and Alkalnty Adjustment(lmestone contactor) (h) Basc

Waters that are low n ron and turbdty. Raw watershould be sot and slghtly acdc.

17. Inhbtors Basc All ranges.

18. Aeraton () Basc Waters wth moderate to hgh carbon doxde content.

Limitation Footnotesa) Chemicals required during regeneration and pH adjustments may be dicult or small systems to handle.b) Sotening chemistry may be too complex or small systemsc) It may not be advisable to install coagulation/ltration solely or inorganics removal.d) I all o the infuent water is treated, post-treatment corrosion control will be necessary.e) pH must exceed pH 8.5 to ensure complete oxidation without build-up o cyanogen chloride.) When POU devices are used or compliance, programs or long-term operation, maintenance, and monitoring must be provided by water utility

to ensure proper perormance.g) Some chemical eeds require high degree o operator attention to avoid plugging.h) This technology is recommended primarily or the smallest size category.i) Any o the rst ve aeration technologies listed or volatile organic contaminants (Table 2.2) can be used.

Table 2.2 Technologies or volatile organic contaminants (NDWC, undated).

Unit TechnologyLimitations

(see ootnotes)Operator Skill Level

RequiredRaw Water

Quality Range

1. Packed Tower Aeraton (PTA) (a) Intermedate All ground waters.

2. Dused Aeraton (a,b) Basc All ground waters.

3. Mult-Stage Bubble Aerators (a,c) Basc All ground waters.

4. Tray Aeraton (a,d) Basc All ground waters.

5. Shallow Tray Aeraton (a,e) Basc All ground waters.

6. Spray Aeraton (a,) Basc All ground waters.

7. Mechancal Aeraton (a,g) Basc All ground waters.8. Granular Actvated Carbon (GAC) (h) Basc All ground waters.

Limitation Footnotesa) Pretreatment or the removal o microorganisms, iron, manganese, and excessive particulate matter may be needed. Post-treatment disinec-

tion may have to be used.b) May not be as ecient as other aeration methods because it does not provide or convective movement o the water thus limiting air-water

contact. It is generally used only to adapt existing plant equipment.c) These units are highly ecient; however, the eciency depends upon the air-to-water ratio.d) Costs may increase i a orced drat is used. Slime and algae growth can be a problem but can be controlled with chemcials such as copper

sulate or chlorine.e) These units require high air-to-water ratios (100-900 m3/m3).) For use only when low removal levels are needed to reach a MCL because these systems may not be as energy ecient as other aeration

methods because o the contacting system.g) For use only when low removal levels are needed to reach an MCL because these systems may not be as energy ecient as other aeration

methods. The units oten require large basins, long residence times, and high energy inputs, which may increase costs.h) See table 2.3 or limitations regarding these technologies.


30/1012-12

Table 2.3 Technologies or synthetic organic contaminants (NDWC, undated).



RequiredRaw Water Quality Range

and Considerations

1. Granular Actvated Carbon (GAC) (h) Basc Surace water may requre preltraton.

2. Pont o Use GAC (a, h) Basc Surace water may requre preltraton.

3. Powdered Actvated Carbon (b, h) Intermedate All waters

4. Chlornaton (c) Basc Better wth hgh qualty waters.

5. Ozonaton (c) Basc Better wth hgh qualty waters.

6. Packed Tower Aeraton (PTA) (d) Intermedate All ground waters.

7. Dused Aeraton (d,e) Basc All ground waters.

8. Mult-Stage Bubble Aerators (d,) Basc All ground waters.

9. Tray Aeraton (d,g) Basc All ground waters.

10. Shallow Tray Aeraton (d,) Basc All ground waters.

Limitation Footnotesa) When POU devices are used or compliance, programs or long-term operation, maintenance, and monitoring must be provided by water utility

to ensure proper perormance.b) Most applicable to small systems that already have a process train including basins, mixing, precipitation or sedimentation, and ltration. Site

specic design should be based on studies conducted on the systems particular water.c) See the Surace Water Treatment Rule compliance technology tables or limitations associated with this technology.d) Pretreatment or the removal o microorganisms, iron, manganese, and excessive particulate matter may be needed. Post-treatment disinec-

tion may have to be used.

e) May not be as ecient as other aeration methods because it does not provide or convective movement o the water thus limiting air-watercontact. It is generally used only to adapt existing plant equipment.

) These units are highly ecient; however, the eciency depends upon the air-to-water ratio.g) Forces may increase i a orced drat is used.h) Pretreatment or removal o suspended solids is an important design consideration. Spent carbon must be regenerated or disposed properly.

Table 2.4 Technologies or radionuclides (NDWC, undated).



RequiredRaw Water Quality Range

and Considerations

IX (a) Intermedate All ground waters.

Pont o Use (POU) IX (b) Basc All ground waters.

Reverse Osmoss (RO) (c) Advanced Surace waters, usually requre preltraton.

POU RO (b) Basc Surace waters, usually requre preltraton.

Lme Sotenng (d) Advanced All waters.

Green Sand Fltraton (e) Basc

Co-precptaton wth Barum Sulate ()Intermedate to

Advanced Ground waters wth sutable water qualty

Electrodalyss/Electrodalyss Reversal Advanced All ground waters.

Pre-ormed Hydrous ManganeseOxde Fltraton (g) Intermedate All ground waters.

Limitation Footnotesa) The regeneration solution contains high concentrations o the contaminant ions. Disposal options should be careully considered beore

choosing the technology.b) When POU devices are used or compliance, programs or long-term operation, maintenance, and monitoring must be provided by water utility

to ensure proper perormance.

c) Reject water disposal options should be careully considered beore choosing this technology. See other RO limitations described in the Sur-ace Water Treatment Rule Compliance Table.

d) The combination o variable source water quality and the complexity o the chemistry involved in lime sotening may make this technology toocomplex or small surace water systems.

e) Removal eciencies can vary depending on water quality.) This technology may be very limited in application to small systems. Since the process requires static mixing, detention basins, and ltration; it

is most applicable to systems with suciently high sulate levels that already have a suitable ltration treatment train in place.g) This technology is most applicable to small systems that already have ltration in place.


31/1012-13

Table 2.5 Technologies or disinection (NDWC, undated).


(see ootnotes)Operator Skill

Level RequiredRaw Water Quality Range

and Considerations

Free Chlorne (a,b) BascBetter wth hgh qualty. Hgh ron or manganese may requresequestraton or physcal removal.

Ozone (c,d, h) Intermedate

Better wth hgh qualty. Hgh ron or manganese may requre

sequestraton or physcal removal.

Chloramnes (e) IntermedateBetter wth hgh qualty. Ammona dose should be temperedby natural ammona levels n water.

Chlorne Doxde () Intermedate Better wth hgh qualty.

Onste Oxdant Generaton (g) Basc Better wth hgh qualty.

Ultravolet (UV) Radaton (h) BascRelatvely clean source water requred. Iron, natural organcmatter and turbdty aect UV dose.

Limitation Footnotesa) Providing adequate CT may be a problem or some water supplies.b) Chlorine gas requires special caution in handling and storage, and operator training.c) Ozone leaks represent hazard: air monitoring required.d) Ozone used as primary disinectant (i.e., no residual protection).e) Long CT. Requires care in monitoring o ratio o added chlorine to ammonia.) Chlorine dioxide requires special storage and handling precautions.g) Oxidants other than chlorine not detected in solution by signicant research eort. CT should be based on ree chlorine until new research

determines appropriate CT values or electrolyzed salt brine.

h) No disinectant residual protection or distributed water.

Table 2.6 Technologies or ltration (NDWC, undated).



Required Raw Water Quality Range and Considerations

Conventonal Fltraton(ncludes dual-stage anddssolved ar fotaton (a) Advanced

Wde range o water qualty. Dssolved ar fotaton s moreapplcable or removng partculate matter that doesntreadly settle: algae, hgh color, low turbdty--up to 30-50nephelometrc turbdty unts (NTU) and low-densty turbdty.

Drect Fltraton (ncludesn-lne ltraton (a) Advanced

Hgh qualty. Suggested lmts: average turbdty 10 NTU;maxmum turbdty 20 NTU; 40 color unts; algae on a case-by-case bass.

Slow Sand Fltraton (b) BascVery hgh qualty or pretreatment. Pretreatment requred raw water s hgh n turbdty, color, and/or algae.

Datomaceous EarthFltraton (c) Intermedate

Very hgh qualty or pretreatment. Pretreatment requred raw water s hgh n turbdty, color, and/or algae.

Reverse Osmoss (d,e,) Advanced

Requres preltratons or surace water-may nclude re-moval o turbdty, ron, and/or manganese. Hardness anddssolved solds may also aect perormance.

Nanoltraton (e) IntermedateVery hgh qualty o pretreatment. See reverse osmosspretreatment.

Ultraltraton (g) Basc Hgh qualty or pretreatment.

Mcroltraton (g) Basc Hgh qualty or pretreatment requred.

Bag Fltraton (g,h,) Basc

Very hgh qualty or pretreatment requred, due to lowpartculate loadng capacty. Pretreatment hgh turbdtyor algae.

Cartrdge Fltraton (g,h,) Basc

Very hgh qualty or pretreatment requred, due to lowpartculate loadng capacty. Pretreatment hgh turbdty

or algae.

Backwashable DepthFltraton (g,h,) Basc

Very hgh qualty or pretreatment requred, due to lowpartculate loadng capacty. Pretreatment hgh turbdtyor algae.

Limitations Footnotesa. Involves coagulation. Coagulation chemistry requires advanced operator skill and extensive monitoring. A system needs to have direct ull-time

access or ull-time remote access to a skilled operator to use this technology properly.b. Water service interruptions can occur during the per iodic lter-to-waste cycle, which can last rom six hours to two weeks.c. Filter cake should be discarded i ltration is interrupted. For this reason, intermittent use is not practical. Recycling the ltered water can remove

this potential problem.d. Blending (combining treated water with untreated raw water) cannot be practiced at risk o increasing microbial concentration in nished water.e. Post-disinection recommended as a saety measure and or residual maintenance.. Post-treatment corrosion control will be needed prior to distribution.g. Disinection required or viral inactivation.h. Site-specic pilot testing prior to installation likely to be needed to ensure adequate perormance.i. Technologies may be more applicable to system serving ewer than 3,300 people.


32/1012-14

urther discussed in Chapter 6. The ollowing is a

brie description o each o the key distribution system

inrastructure elements.

2.9.1 Storage FacilitiesStorage acilities may be closed tanks or reservoirs and

are designed to store treated water (ground storage)

or to maintain adequate service pressure (elevated,hydropneumatic, or ground storage that is built at a

location to act as elevated storage).

A clearwell tank is generally the rst treated water stor-

age tank and is located at the end o the treatment train

or at the end o a well system. Their primary purpose is

to provide or contact time when chemical treatment ad-

ditives (e.g., chlorine) are used. These storage structures

have limited use as storage reservoirs due to their loca-

tion. The added storage or reserve capability o clear-

wells are an advantage or small system operators that

need time or maintenance o equipment or structures,

or other storage needs such as re fows, but this is nottheir intended use. Utilities should not rely on clearwell

storage as their only means o reserve or the distribution

system. The clearwell tank also serves as a reservoir

or the storage o ltered water o sucient capacity to

prevent the need to vary the ltration rate with varia-

tions in demand. Clearwell tanks provide both a treated

water reserve or delivery to the distribution system and

additional detention time or more eective disinec-

tion (EPA, 1999). Figure 2.15 shows the percentage o

CWSs that use clearwell tanks or treated-water storage.

Table 2.7 Compliance technology or the Total Coliorm Rule (NDWC, undated).

40 CFR 141.63(d) - Best technologies or othermeans to comply

(Complexity level indicated) Comments/Water Quality Concerns

Protectng wells rom contamnaton, e.g., place-ment and constructon o well(s) (Basc).

Ten State Standards and other standards (AWWA, 1995) apply; nteracngwth other programs essental (e.g., source water protecton program).

Mantenance o a dsnecton resdual or dstrbu-ton system protecton (Intermedate).

Source water consttuents may aect dsnecton: ron, manganese, organ-cs, ammona, and other actors may aect dosage and water qualty. TotalColorm Rule (TCR) remans unspecc on type/amount o dsnectant, aseach type ders n concentraton, tme, temperature, pH, nteracton wthother consttuents, etc.

Proper mantenance o dstrbuton system: pperepar/replacement, man fushng programs,storage/reservor, and O&M programs (ncludngcross-connecton control/backfow preventon),and mantenance o postve pressure throughout(Intermedate).

O&M programs partcularly mportant or smaller systems needng to man-tan water purty. States may vary on dstrbuton protecton measures.See also EPAs Cross-Connecton Control Manual (EPA, 2003b)

Fltraton and/or dsnecton o surace water orother ground water under drect nfuence; or dsn-ecton o ground water (Basc thru Advanced).

Same ssues as cted above under mantanng dsnecton resdual;pretreatment requrements aect complexty o operaton. Reer to SuraceWater Treatment Rule Complance Technology Lst; and other regulatonsunder development.

Ground waters: Complance wth State WellheadProtecton Program (Intermedate). EPA/State Wellhead Protecton Program mple

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EPA, Small Drinking Water Systems, 2005

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