Technology and Cost
Document for the Final
Ground Water Rule
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Office of Water (4606-M) EPA 815-R-06-015 October 2006 www.epa.gov/safewater
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Contents
1. Introduction
1.1 Purpose of the Document
1.2 Statement of Statutory Requirements
1.3 Document Organization
1.4 Treatment Technologies
1.5 Best Management Practices
1.6 Use of the Information Presented in this Document
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2. Introduction to Treatment Technologies 2-1
2.2 Chlorine-Based Treatment Technologies 2-2
2.2.1 The Concept of Chlorine Residual 2-2
2.2.1.1 Chlorine Dose and Contact Time 2-3
2.2.2 Chlorine Gas 2-6
2.2.2.1 Background 2-6
2.2.2.2 Description 2-6
2.2.2.3 Operation and Maintenance 2-7
2.2.2.4 Microbial Inactivation Capabilities 2-8
2.2.2.5 Advantages and Disadvantages 2-8
2.2.3 Hypochlorite 2-9
2.2.3.1 Background 2-9
2.2.3.2 Description 2-9
2.2.3.3 Operation and Maintenance 2-10
2.2.3.4 Microbial Inactivation Capabilities 2-10
2.2.3.5 Advantages and Disadvantages 2-10
2.2.4 Temporary Hypochlorination 2-11
2.2.4.1 Background and Description 2-11
2.2.4.2 Implementation Issues 2-11
2.2.4.3 Advantages and Limitations 2-11
2.2.5 Chlorine Dioxide 2-11
2.2.5.1 Background 2-11
2.2.5.2 Description 2-12
2.2.5.3 Operation and Maintenance 2-13
2.2.5.4 Microbial Inactivation Capabilities 2-14
2.2.5.5 Advantages and Disadvantages 2-15
2.2.6 Anodic Oxidation 2-15
2.2.6.1 Background 2-15
2.2.6.2 Description 2-15
2.2.6.3 Operation and Maintenance 2-16
2.2.6.4 Microbial Inactivation Efficiencies 2-17
2.2.6.5 Advantages and Disadvantages 2-18
2.3 Chlorine-Free Treatment Technologies 2-18
2.3.1 Ozone 2-18
2.3.1.1 Background 2-18
2.3.1.2 Description 2-18
2.3.1.3 Operation and Maintenance 2-20
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2.3.1.4 Microbial Inactivation Capabilities 2-21
2.3.1.5 Advantages and Disadvantages 2-22
2.3.2 Nanofiltration 2-23
2.3.2.1 Background 2-23
2.3.2.2 Description 2-23
2.3.2.3 Operation and Maintenance 2-23
2.3.2.4 Microbial Removal Capabilities 2-24
2.3.2.5 Advantages and Disadvantages 2-24
2.4 Applicability Matrix 2-26
2.5 Risk/Risk Trade-Offs 2-26
2.5.1 Formation of Disinfection By-products 2-26
2.5.1.1 Sources of Data 2-26
2.5.2 Colored Water 2-28
2.5.2.1 Definition of Problem 2-29
2.5.2.2 Potential Sources of Ground Water Quality Problems 2-29
2.5.2.3 Potential Impacts On Water Quality 2-29
2.5.2.4 Mitigation of Ground Water Disinfection Impacts 2-30
3. Costs for Treatment Technologies 3-1
3.1 Introduction 3-1
3.2 Description and Application of the Cost Models 3-3
3.2.1 Water and Wastewater (WAV) Model 3-3
3.2.2 Water Model 3-6
3.2.3 Very Small Systems (VSS) Model 3-7
3.3 General Costing Methodology 3-8
3.3.1 Estimates Using Cost Models Approach 3-8
3.3.2 Estimates Using a Cost Build-Up Approach 3-10
3.3.3 Waste Disposal Costs 3-12
3.4 "Additional" Cost Items 3-12
3.4.1 Permitting 3-13
3.4.2 Piloting 3-13
3.4.3 Land 3-13
3.4.4 Housing, Operator Training, and Public Education 3-14
3.5 Example Calculations for Costing Methodologies 3-14
3.5.1 Example Calculations for the Cost Model Approach using WAV Model .... 3-15
3.5.2 Example Calculations for the Cost Model Approach using Water Model . . . 3-15
3.5.3 Example Calculations for the Cost Model Approach (VSS Model) 3-16
3.5.4 Example Calculations for the Cost Build-Up Approach 3-17
3.6 Costs for Storage tanks Including Finished Water Pumping 3-18
3.6.1 Introduction 3-18
3.6.2 Storage tanks 3-18
3.6.3 Finished Water Pumping 3-19
3.6.4 Cost Estimates 3-19
3.7 Costing for Applicable Technologies 3-21
3.7.1 Gas Chlorination Systems 3-22
3.7.1.1 Medium-to-Large Systems Costs: WAV Model 3-22
3.7.1.2 Small-to-Medium Systems Costs: Water Model 3-23
3.7.1.3 Very Small Systems Costs: VSS Model 3-24
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3.7.1.4 Gas Chlorination - Cost Summary and Equations 3-24
3.7.2 Hypochlorination Systems (with and without additional storage) 3-26
3.7.2.1 Medium-to-Large Systems Costs: WAV Model 3-26
3.7.2.2 Small-to-Medium Systems Costs: Water Model 3-26
3.7.2.3 Very Small Systems Costs: VSS Model 3-27
3.7.2.4 Hypochlorination - Cost Summary and Equations 3-28
3.7.2.5 Additional Cost Model Inputs for Gas Chlorination and
Hypochlorination 3-28
3.7.3 Temporary Hypochlorination 3-30
3.7.4 Chlorine Dioxide Systems (with and without additional storage) 3-33
3.7.4.1 Chlorine Dioxide Dose 3-33
3.7.4.2 Capital Cost Assumptions 3-33
3.7.4.3 O&M Cost Assumptions 3-34
3.7.4.4 Chlorine Dioxide - Cost Summary and Equations 3-35
3.7.5 Anodic Oxidation Systems 3-39
3.7.5.1 Medium-to-Large Systems Costs: WAV Model 3-39
3.7.5.2 Small-to-Medium Systems Costs: Water Model 3-40
3.7.5.3 Very Small Systems Costs: VSS Model 3-40
3.7.5.4 Anodic Oxidation - Cost Summary and Equations 3-40
3.7.5.5 Additional Cost Model Inputs for Chlorine-based Technologies ... 3-41
3.7.6 Ozonation Systems 3-43
3.7.6.1 Ozone Dose 3-43
3.7.6.2 Capital Cost Assumptions 3-44
3.7.6.3 O&M Cost Assumptions 3-48
3.7.6.4 Ozonation - Cost Summary and Equations 3-50
3.7.7 Nanofiltration (NF) 3-53
3.7.7.1 General Assumptions 3-53
3.7.7.2 Capital Cost Assumptions 3-53
3.7.7.3 O&M Cost Assumptions 3-56
3.7.7.4 Nanofiltration - Cost Summary and Equations 3-59
4. Introduction to Best Management Practices 4-1
4.1 Introduction to Best Management Practices 4-1
4.2 System Assessment BMPs 4-2
4.2.1 Sanitary Survey 4-2
4.2.1.1 Background and Description 4-2
4.2.1.2 Implementation Issues 4-2
4.2.1.3 Advantages and Limitations 4-6
4.2.2 Hydrogeologic Sensitivity Assessment (HSA) 4-7
4.2.2.1 Background and Description 4-7
4.2.2.2 Implementation Issues 4-7
4.2.2.3 Advantages and Limitations 4-7
4.3 Corrective Action BMPs 4-7
4.3.1 Significant Deficiency Correction Actions 4-8
4.3.1.1 Replacing a Well Seal 4-8
4.3.1.2 Rehabilitation of Existing Wells 4-8
4.3.2 Source Water Corrective Actions 4-9
4.3.2.1 Eliminating Known Sources of Contamination 4-9
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4.3.2.2 Rehabilitating a Well 4-10
4.3.2.3 Purchasing Water from Another Utility 4-10
4.3.2.4 Installation of New Wells 4-10
4.3.3 Additional Corrective Actions 4-12
4.3.3.1 Storage Tank Cover Replacement or Repair 4-12
4.3.3.2 Cross-Connection Control and Backflow Prevention Program 4-12
4.3.3.3 Installation of Security Measures 4-14
5. Costs for Best Management Practices 5-1
5.1 Introduction 5-2
5.2 System Assessment 5-4
5.2.1 Sanitary Survey 5-4
5.2.2 Hydrogeologic Sensitivity Assessment (HSA) 5-9
5.3 Corrective Actions 5-11
5.3.1 Significant Deficiency Corrective Actions 5-11
5.3.1.1 Replacing a Well Seal 5-11
5.3.1.2 Rehabilitation of Existing Wells 5-11
5.3.2 Source Water Corrective Actions 5-13
5.3.2.1 Eliminating Known Sources of Contamination 5-13
5.3.2.2 Rehabilitation of Existing Wells 5-14
5.3.2.3 Purchasing Water from Another Utility 5-14
5.3.2.4 Installation of New Wells 5-16
5.3.3 Additional Corrective Actions 5-17
5.3.3.1 Storage Tank Cover Replacement or Repair 5-17
5.3.3.2 Cross-Connection Control and Backflow Prevention Program 5-17
5.3.3.3 Installation of Security Measures 5-19
5.4 Summary 5-20
REFERENCES R-l
APPENDIX A: Linear Regression Coefficients for Unit Costs A-l
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List of Exhibits
Exhibit 1.1 Treatment Technologies 1-4
Exhibit 2.1 CT Values for Inactivation of Viruses by Free Chlorine (mg-min/L) 2-4
Exhibit 2.2 Inactivation of Poliovirus 1 (Mahoney) and Poliovirus 2 (MEFj) at pH 7, at 1 to
5°C and 25 to 28°C, with 0.20 to 0.30 ppm Free Residual Chlorine
(Pj = Poliovirus 1, P2 = Poliovirus 2) 2-5
Exhibit 2.3 Inactivation of Coxsackie B5 Virus at pH 6 to 10 at 25 to 28°C with
0.24 to 0.29 ppm Free Residual Chlorine 2-6
Exhibit 2.4 CT Values (mg-min/L) for Inactivation of Viruses1 by Chlorine Dioxide for
pH 6 to 9 2-14
Exhibit 2.5 Oxidant Production Efficiency of Four of MIOX's Models 2-16
Exhibit 2.6 CT Values (mg of O3-min/L) for Virus Inactivation by Ozone 2-22
Exhibit 2.7 Particle Sizes and Membrane Process Ranges 2-24
Exhibit 2.8 Applicability of Drinking Water Treatment Technologies for Virus Inactivation or
Removal 2-26
Exhibit 2.9 TOC Concentrations (mg/L) in Influent Water 2-28
Exhibit 2.10 Bromide Concentrations (mg/L) in Influent Water 2-28
Exhibit 2.11 THMs (mg/L) in Distribution System Water for Disinfecting
Ground Water Systems 2-28
Exhibit 3.1 Technologies Costed and Methodology Adopted 3-1
Exhibit 3.2 Flow Categories Used for Cost Estimates 3-2
Exhibit 3.3 Applicable Unit Costs and BLS Cost Indices (2003 dollars/indices) 3-5
Exhibit 3.4 ENR Cost Indices 3-6
Exhibit 3.5 Chemical Costs (2003 dollars 3-6
Exhibit 3.6 Labor Rates for PWS Operators 3-10
Exhibit 3.7 Additions to Preliminary Process Cost Estimates 3-11
Exhibit 3.8 Summary of Piloting Cost Assumptions 3-13
Exhibit 3.9 Summary of Land Cost Assumptions as a Percent of Total Capital Cost 3-14
Exhibit 3.10 Estimated Costs for At-Grade Tanks for Chlorine Contact (Residual of 2 mg/L) -
Costs in 2003$ 3-20
Exhibit 3.11 Estimated Costs for At-Grade Tanks for Chlorine Dioxide Contact
(Residual of 0.625 mg/L) - Costs in 2003$ 3-21
Exhibit 3.12 Estimated Costs for Gas Chlorination Systems 3-25
Exhibit 3.13 Estimated Costs for Hypochlorination Systems 3-29
Exhibit 3.14 Estimated Additional O&M Costs For Hypochlorite/ Gas Chlorination Systems
When Increasing Chlorine Dose From 2.5 mg/L to 4 mg/L 3-30
Exhibit 3.15 Temporary Hypochlorination Pumping Rates and Tank Volumes 3-31
Exhibit 3.16 Pump Costs (2003$) 3-31
Exhibit 3.17 Tank Costs (2003$) 3-32
Exhibit 3.18 Capital Costs for Temporary Hypochlorination 3-32
Exhibit 3.19 Operating and Maintenance Costs 3-33
Exhibit 3.20 WAV Cost Model Footprint Area, Electricity Usage and Required Labor 3-35
Exhibit 3.21 Estimated Costs for Chlorine Dioxide Systems 3-37
Exhibit 3.22 Estimated Costs for Anodic Oxidation Systems 3-42
Exhibit 3.23 Estimated Costs for Disinfection Monitoring 3-42
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Exhibit 3.24 Ozonation O&M Cost Assumptions 3-49
Exhibit 3.25 Estimated Costs for Ozonation Systems 3-51
Exhibit 3.26 Percent Distribution of NF Equipment Cost 3-54
Exhibit 3.27 Summary of NF Housing Cost Assumptions 3-55
Exhibit 3.28 NF Land Cost Assumptions 3-56
Exhibit 3.29 NF Operator Training Cost Assumptions 3-56
Exhibit 3.30 Summary of NF Technical Labor Assumptions 3-59
Exhibit 3.31 Estimated Costs for Nanofiltration Systems 3-60
Exhibit 5. la State Labor Rate Components of BMPs 5-2
Exhibit 5.1b PWS Operator Labor Rate Components of BMPs 5-3
Exhibit 5.2 Average Number of Wells per Community Water System 5-3
Exhibit 5.3a Estimated State Costs for a Sanitary Survey for Systems with Treatment (2003$) .... 5-5
Exhibit 5.3b Estimated State Costs for a Sanitary Survey for Systems without Treatment (2003$) . 5-6
Exhibit 5.4a Estimated System Costs for Performing a Sanitary Survey for Systems with
Treatment (2003$) 5-7
Exhibit 5.4b Estimated System Costs for Performing a Sanitary Survey for Systems without Treatment
(2003$) 5-8
Exhibit 5.5 Estimated State Costs of a Hydrogeologic Sensitivity Assessment (2003$) 5-10
Exhibit 5.6 Estimated Costs for Rehabilitating Community Water System Wells (2003$) 5-12
Exhibit 5.7 Estimated Costs for the Installation of a Booster Pump (2003$) 5-13
Exhibit 5.8 Estimated Costs for Elimination of Known Sources of Contamination -
Drainage of the Old Septic Tank and Installation of a New Septic Tank (2003$) . . . 5-14
Exhibit 5.9 General Costs Associated with a System Purchasing Water (2003$) 5-15
Exhibit 5.10 Estimated New Well Costs for Community Water Systems (2003$) 5-16
Exhibit 5.11 Estimated Costs for the Repair of Storage Tank Cover (2003$) 5-17
Exhibit 5.12 Estimated Costs for a Backflow Prevention Assembly (2003$) 5-18
Exhibit 5.13 Cost Components of Program Administration for a Cross-Connection Control and
Backflow Prevention Program 5-19
Exhibit 5.14 Estimated Costs for Installation of Security Measures (2003$) 5-20
Exhibit 5.15 Estimated Unit Costs of Non-Treatment Corrective Actions for Source Water
Contamination (2003$) 5-20
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List of Acronyms and Abbreviations
A° Angstrom
adj. adjustment
ANSI American National Standards Institute
ASCE American Society of Civil Engineers
AWWA American Water Works Association
BCI Building Cost Index
BLS Bureau of Labor Statistics
BMP Best Management Practice
BPJ Best Professional Judgment
BVP bovine parovirus
°C degrees centrigrade
C Residual Disinfectant Concentration (in mg/L)
CAP Total Capital Cost
CCCBFP Cross-Connection Control and Backflow Prevention
CIP Clean In-Place
cm centimeter
CPI Consumer Price Index
CSTR Continuous Stirred-tank Reactor
CSU California State University
CT product of the residual disinfectant concentration (C) & the disinfectant contact time (T)
CWC Culp/Wesner/Culp
CWS Community Water System
CY Cubic Yard
DBP Disinfection Byproduct
EA Economic Analysis
ECBO Enteric Cytopathogenic Bovine Orphan
ECI Employment Cost Index
E&I Electrical and Instrumentation
ENR Engineering News Record
ft foot or feet
ft2 square feet
gal gallons
gpd gallons per day
gpd/ft2 gallons per day per square feet
gpm gallons per minute
GWR Ground Water Rule
GWSS Ground Water Supply Survey
GWUDI Ground Water Under Direct Influence of Surface Water
HAA Haloacetic Acid
HAV Hepatitis A Virus
HCC hepatitus contagiosa
hp Horsepower
HPC Heterotrophic Plate Count
hr hour
HSA Hydrogeologic Sensitivity Assessment
HVAC Heating, Ventilation, and Air Conditioning
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I&C Instrumentation and Controls
ICP Inductively Coupled Plasma
ICR Information Collection Rule
IESWTR Interim Enhanced Surface Water Treatment Rule
in inch
IT Irradiance Multiplied by Time
kgal kilogallons
kg/mg kilograms per milligram
kgpd kilogallons per day
kW kilowatt
kWh kilowatt hours
kWh/ft2/yr kilowatt hour per square foot per year
kWh/lb kilowatt hour per pound
Ib pound
Ib/day pounds per day
Ib/kg pounds per kilogram
LF Linear Foot
L/gal liter per gallon
LOX Liquid Oxygen
LTIESWTR Long Term 1 Enhanced Surface Water Treatment Rule
jam micrometer
|amhos/cm micromhos per centimeter
MCL Maximum Contaminant Level
MF Microfiltration
mgd million gallons per day
mg/g milligrams per gram
mg/L milligrams per liter
mg-min/L milligrams minute per liter
mm millimeters
NCWS Noncommunity Water System
NDWAC National Drinking Water Advisory Council
NETA National Environmental Training Association
NF Nanofiltration
nm nanometers
NOM Natural Organic Matter
NPDES National Pollutant Discharge Elimination System
NPDWR National Primary Drinking Water Regulations
NRC National Research Council
NV Newcastle Disease Virus
NWQA National Water Quality Association
O.C. on center
OEM Original Equipment Manufacturer
O&M Operation and Maintenance
O&P Overhead and Profit
ORP Oxidation-Reduction Potential
PLC Programmable Logic Control
POE Point-of-Entry
POTW Publicly Owned Treatment Works
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POU Point-of-Use
PPI Producer Price Index
ppm parts per million
PSA Pressure Swing Absorption
psi pounds per square inch
P&V Pipes and Valves
PVC polyvinyl chloride
PWS Public Water System
Q10 factor by which disinfection rates increase for each 10°C rise in water temperature
rpm revolutions per minute
SDWA Safe Drinking Water Act
SDWIS Safe Drinking Water Information System
SWAP Source Water Assessment Program
SWTR Surface Water Treatment Rule
T Disinfectant Contact Time (in minutes)
TDH Total Dynamic Head
TOP Technology Design Panel
TDS Total Dissolved Solids
THM Trihalomethane
TTHMs Total Trihalomethanes
TOC Total Organic Carbon
UIC Underground Injection Control
UF Ultrafiltration
UFTREECO University of Florida Training, Research, and Education for Environmental Occupations
Center
U.S. United States
USGS United States Geological Survey
USEPA United States Environmental Protection Agency
VS Vesicular Somatitis
VSS Very Small Systems
WEF Water Environment Federation
WIDE Water Industry Database
WAV Water and Wastewater Model
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List of Chemical Formulae
CaCO3
Ca(OCl)2
Cl
ci-
C1O2
C1O2
C1O3
Fe2+
H+
H02
HO3
HO"
HC1O2
HC1O3
HCO3"
HCO3
H2O2
HC1
HOC1
H2S
H2SO4
Mn2+
Mn4+
NaCl
NaClO2
NaClO3
NaOCl
O2
02
O3
03
OC1
OH
calcium carbonate
calcium hypochlorite
chlorine
chloride ion
chlorine dioxide
chlorite
chlorate
iron (II)
hydrogen ion
hydrogen dioxide
hydrogen trioxide
hydroxyl free radical
chlorous acid
chloric acid
bicarbonate free radical
bicarbonate ion
hydrogen peroxide
hydrogen chloride or hydrochloric acid
hypochlorous acid
hydrogen sulfide
hydrogen sulfate
manganese (II)
manganese (IV)
sodium chloride
sodium chlorite
sodium chlorate
sodium hypochlorite
molecular oxygen
molecular oxygen unstable reactive intermediate
ozone
ozone unstable reactive intermediate
hypochlorite ion
hydroxylion
Technology and Cost Document for the
Final Ground Water Rule
October 2006
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1. Introduction
1.1 Purpose of the Document
This document is one of several technical documents prepared in support of the Ground Water
Rule (GWR) The document describes treatment technologies and best management practices (BMPs)
that ground water systems can consider as corrective actions or safeguards to reduce or eliminate
microbial risks. The document also presents the estimated costs associated with their installation,
implementation, and operation.
1.2 Statement of Statutory Requirements
The United States Environmental Protection Agency (EPA) has the responsibility to develop a
ground water rule which not only specifies the appropriate use of disinfection but, just as important, also
addresses other components of ground water systems to assure protection of public health. Section
1412(b)(l)(A) of the Safe Drinking Water Act (SDWA) requires EPA to establish National Primary
Drinking Water Regulations (NPDWRs) for contaminants that "may have an adverse effect on the health
of persons," are "known to occur or there is a substantial likelihood that the contaminant will occur in
public water systems with a frequency and at levels of public health concern," and for which, "in the sole
judgment of the Administrator, regulation of such contaminant presents a meaningful opportunity for
health risk reductions for persons served by public water systems." Section 1412(b)(8) requires the EPA
to develop regulations specifying the use of disinfectants for ground water systems as necessary.
1.3 Document Organization
This document is organized into five chapters as follows:
Chapter 1. Introduction discusses the purpose and organization of the document, presents
an overview of the treatment technologies and BMPs described in the document, and explains
how the information provided in this document support the development of the GWR. A
detailed description and derivation of costs for these technologies and practices are presented
in the following chapters of this document.
Chapter 2. Introduction to Water Treatment Technologies describes well-established
pathogen inactivation and removal technologies applicable to reduce microbial risks
fromground water sources, including evaluations of efficacy data and advantages and
disadvantages for each technology. A discussion of the potential impact of certain
technologies on the levels of disinfection byproducts (DBPs) in finished water is also
presented to enable evaluation of the risk/risk trade-offs associated with chemical
disinfection. Where applicable, the chapter considers waste disposal and operations and
maintenance (O&M) requirements for the treatment technologies discussed.
Chapter 3. Costs for Treatment Technologies presents design criteria, costing
methodologies, and unit cost elements for treatment technologies. The design criteria
presented address those elements used in the costing methodologies. Costs for each
technology include both capital and O&M costs.
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Chapter 4. Introduction to Best Management Practices describes ten different BMPs that
prevent, eliminate, or reduce contamination within ground water systems, and notes
advantages and disadvantages or limitations of each. A description and discussion of
implementation issues is also presented for each BMP.
Chapter 5. Costs for Best Management Practices presents costs for each of the BMPs
discussed in Chapter 4. This chapter outlines assumptions and describes oversight costs,
where relevant, for systems, States, or EPA.
Appendix A. Cost Equation Coefficients presents the linear coefficients used to calculate
costs for each of the treatment technologies for which costs were calculated.
1.4 Treatment Technologies
Treatment technologies are water treatment processes that provide public health protection by
achieving a specified level of contaminant removal or, in the case of microbial contamination,
inactivation or removal. The contaminants of concern for the GWR are viruses and bacteria. Modes of
treatment technologies include: centralized treatment facilities, prefabricated and designed package
treatment units or plants (decentralized or remotely operated), and point-of-entry (POE) devices. Some of
these technologies may be used on an interim basis to provide temporary disinfection until permanent
changes can be implemented.
An important consideration to the practical use of any treatment technique is the economic
feasibility of the selected treatment technique and financial capability of the public water system (PWS).
Some of the technologies identified for use to meet GWR requirements are more complex and expensive
than others, but because of site-specific conditions and system size, may be more applicable for
eliminating microbial contamination. Some water systems (e.g., the smallest) cannot use certain
technologies due to operational complexity, manpower or training requirements, economic
considerations, or other local conditions or requirements. In accordance with SDWA requirements, EPA
must evaluate and list affordable treatment techniques for small public water supplies serving populations
of: 25 to 500 people; 501 to 3,300 people; and 3,301 to 10,000 people.
Under the GWR, treatment techniques will not include point-of-use (POU) devices since section
1412(b)(4)(E)(42 U.S.C.300g-l(b)(4)(E)) of the SDWA directs EPA not to list any POU treatment
technology to achieve compliance with a maximum contaminant level or treatment technique requirement
for a microbial contaminant (or an indicator of a microbial contaminant). Given the importance of
disinfection, it is important to note that the National Research Council (NRC) cites that surface water
disinfection using point-of-entry (POE) and POU systems is generally regarded as inappropriate (NRC,
1997) because the use of POE devices weaken the systems assurance that public health is being protected
and customer access to some devices may make maintenance difficult. Other factors such as management
and monitoring frequency of POE and POU systems may make disinfection with POE and POU systems
less practical than centralized treatment at the community level (NRC, 1997).
Viruses are the target microbial pathogen for ground water sources because they are more mobile
in an underground setting, and are usually more resistant to inactivation and less amenable to filtration
processes than bacteria. EPA believes that protection against viruses will provide additional protection
against bacteria co-occurring in contaminated ground water. The 4-log inactivation or removal of viruses
is the standard of comparison for this document because it is consistent with the disinfection treatment
objectives for drinking water from surface water sources (USEPA, 1991a). Protozoa, such as
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Cryptosporidium, are more resistant to conventional disinfection methods than bacteria and viruses, but
are not the target microorganism for disinfection in ground water because the filtering action of the soil or
aquifer media immobilizes protozoa. Any ground water source that does contain protozoa is defined as
ground water under the direct influence of surface water (GWUDI). GWUDI sources are regulated the
same as surface water sources under EPA regulations such as the Surface Water Treatment Rule (SWTR),
the Interim Enhanced Surface Water Treatment Rule (IESWTR), Long Term 1 Enhanced Surface Water
Treatment Rule (LTIESWTR), and Long Term 2 Enhanced Surface Water Treatment Rule (LT2).
This document provides information on treatment techniques that PWSs could use for primary
pathogen inactivation and removal. Information on some technologies that may be utilized as secondary
disinfection technologies is also presented, although it is not required in the rule. Primary disinfection
technologies are capable of achieving a mandatory log inactivation, or removal of pathogenic or indicator
microorganisms prior to distribution. Secondary disinfection technologies are capable of providing a
residual disinfectant in the distribution system. In order to meet the GWR requirements, a treatment
technology must, at a minimum, satisfy the following criteria:
Field scale applications of the technology or projections from field or pilot studies are
available, and it is reasonable to assume that the technology will perform in a similar manner
under most field conditions
The technology is compatible with other treatment technologies (e.g., technologies for iron
and manganese removal)
• The technology can achieve effective contaminant inactivation or removal (i.e. 4-log virus
inactivation)
Exhibit 1.1 lists the treatment technologies described in this document and classifies them by
chemical (chlorine and non-chlorine based) and physical methods.
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Exhibit 1.1 Treatment Technologies
Chlorine Based
Treatment Technologies
Non-Chlorine Based
Chemical Treatment
Technologies
Physical or Irradiation Process
(Non-Chemical) Based
Treatment Technologies
Gas chlorination
Hypochlorination
Chlorine dioxide
Anodic oxidation
Ozonation
Nanofiltration (NF)
Although all of the technologies listed in Exhibit 1.1 are evaluated in this document, the selection
of any particular technology in response to GWR requirements is dependent on a variety of site specific
characteristics. Some technologies which were considered but not included are chloramines, reverse
osmosis, and UV. Chloramines were not considered because they cannot reasonably achieve 4-log virus
inactivation. Reverse Osmosis was not included because nanofiltration is a similar technology and can
achieve the treatment goals at a much lower cost. UV was not included because current validation
procedures do not allow for validation of reactors for 4-log virus inactivation. Although systems could
employ 2 reactors in series or UV in series with another technology, these options would be more
expensive than those described in this document.
1.5 Best Management Practices
There are numerous sanitation practices or BMPs that can be used to prevent, identify, and
correct situations that may cause microbial contamination of a ground water supply. Implementation of
BMPs may represent cost effective methods for achieving (or helping to achieve) the health protection
requirements of the GWR.
This document classifies BMPs into assessment and corrective action BMPs. Assessment BMPs,
such as sanitary surveys and hydrogeologic sensitivity assessments, are measures performed to identify
the components of PWSs that are vulnerable to the introduction of contamination. Systems implement
assessment BMPs to screen or prioritize defects or vulnerabilities in order to protect public health.
Assessment BMPs do not in and of themselves result in improved water quality. Corrective action BMPs,
which are divided into significant deficiency, source water, and additional corrective actions, are
measures performed to protect a system from a source of contamination. This document limits the
discussion on BMPs to those measures that a system may implement to address microbial contamination.
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1.6 Use of the Information Presented in this Document
Readers may use the information presented in this document to evaluate the effectiveness, costs,
and operational constraints of technologies available to PWSs for inactivation or removal of microbial
contaminants from drinking water drawn from ground water sources or to remedy a significant
deficiency. Similar evaluations may also be made for technologies used to correct significant deficiencies
that may lead to microbial contamination of drinking water drawn from ground water sources. In
addition, evaluations can be conducted of BMPs used to prevent, identify, and correct situations that may
cause microbial contamination of a ground water supply.
Information presented in this document also serves as a foundation for making comparisons
between regulatory alternatives developed by EPA, States, and other interested parties. The information
is meant to be used for evaluation and comparison purposes at the national level only and not as direct
input into system-specific design or budget preparation for non-EPA entities.
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2. Introduction to Treatment Technologies
2.1 Introduction
This chapter discusses chemical inactivation technologies and physical removal technologies that
may be used to address microbial contaminants in response to Ground Water Rule (GWR) requirements.
For each technology, a description and brief discussion illustrate the technology's efficiency in
eliminating microbial contaminants as well as the advantages and disadvantages of its use. An
assessment is also presented regarding how widely each technology is utilized. The treatment
technologies described are gas chlorination, hypochlorination, chlorine dioxide, on-site oxidant
generation (anodic oxidation), ozonation, and nanofiltration (NF).
General evaluations are made based on published research to determine the relative effectiveness
of each technology based upon the ability to achieve 4-log inactivation or removal of viruses from
ground water. In general, viruses are more resistant to disinfection than bacteria and protecting against
viruses should also ensure sufficient protection against the presence of bacteria in contaminated ground
water.
Research regarding the disinfection properties of specific chemical-based technologies often
correlate the product of the residual disinfectant concentration, C (in milligrams per liter [mg/L]), and the
residual disinfectant contact time, T (in minutes) (CT) values to the log inactivation of pathogens. The
SWTR formally established the concept of CT in chemical disinfection as the primary method for
determining inactivation levels (USEPA, 1989a). The time from the point of disinfectant application to
the point of residual disinfectant measurement, or between points of residual measurement, is the contact
time. The following EPA documents present a detailed description of the application of the CT concepts
to disinfection practices:
• The preamble to the SWTR. Federal Register; June 29, 1989; p. 274-86 (USEPA, 1989a).
• SWTR Guidance Manual (USEPA, 1991 a; AWWA, 199 Ib).
Although eliminating the source of contamination is a viable alternative for some ground water
supplies, the most widely used method of microbial control among public water supplies is chemical
disinfection (USEPA, 1997a; SDWIS, 1997). Systems use disinfection to inactivate, remove, or kill
disease-causing microorganisms. Chemical methods may inactivate microorganisms in several ways:
By causing damage to the cell wall which causes alterations in cell permeability and affects
nutrient and ion transport.
• By causing alteration of the cell protoplasm, denaturing the cell components, and
precipitating important cell proteins.
• By oxidizing functional groups in enzymes, oxidizing minerals essential for cell growth, and
disrupting electron transfer mechanisms within the cell genetic material (AWWA and ASCE,
1990).
For example, an increase in the oxidation-reduction potential (ORP) of the cellular environment
could disrupt protein synthesis within the cell and consequently inactivate it (Metcalf and Eddy, 1991).
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Adding oxidizing chemicals to water is the most common disinfection treatment method;
however, physical methods may provide similar results. Membrane treatment methods such as NF do not
inactivate microbes by impacting their metabolic processes, but rather remove microorganisms through
physical mechanisms such as straining and electrostatic repulsion.
2.2 Chlorine-Based Treatment Technologies
This section presents the general chemistry and CT information for the following chlorine-based
disinfection technologies:
Chlorine gas (Section 2.2.2)
Hypochlorite (Section 2.2.3)
Temporary Hypochlorination (2.2.4)
• Chlorine Dioxide (Section 2.2.5)
Anodic Oxidation (Section 2.2.6)
The chemistries of chlorine gas, hypochlorite and anodic oxidation are similar; they all react with
water to form the disinfecting agents - hypochlorous acid (HOC1) and hypochlorite ion (OC1~). Since they
require similar doses and contact time, they can achieve inactivation rates with similar CT values. The
other chlorine-based disinfectant, chlorine dioxide, differs in its disinfection mechanisms.
Chlorine dioxide (C1O2) is a more powerful oxidizing agent than chlorine, and does not react with
water. C1O2 is not as effective against viruses as other chlorine-based technologies. However, the effects
of pH and temperature on CT values are similar to those on chlorine.
2.2.1 The Concept of Chlorine Residual
During gas chlorination and hypochlorination, chlorine reacts with water to form HOC1 and OC1''
the free chlorine residuals that are the disinfecting agents. This process is known as hydrolysis and
occurs as follows:
ci2(g) + H2o •* HOCI + H+ + cr
Next, ionization occurs:
HOCI - H+ + ocr
These equations indicate the release of one or two protons. pH levels in drinking water typically
drop between 0.5 and 1.5 pH units as a result of chlorination during typical operations.
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In the hypochlorination process, sodium hypochlorite or calcium hypochlorite in solution ionize
directly to form hypochlorite ion as follows:
Na+ + OCl~
Ca(OCl)2 - Ca++ + 2OCl~
Reaction with water can produce HOC1 and hydroxide ion:
H2o + ocr - HOCI + OH-
2.2.1.1 Chlorine Dose and Contact Time
As discussed in section 2.1, CT values are the product of residual disinfectant concentration and
contact time. When chlorine is added to water, it reacts with inorganic ions and compounds such as iron
(Fe2+), manganese (Mn2+), and hydrogen sulfide (H2S) found in the water and in some system structural
materials. Therefore, the chlorine is not fully available for disinfection. The amount of chlorine needed
to react with these substances is known as chlorine demand. The chlorine dose (in mg/L) is the amount of
chlorine added to satisfy the chlorine demand and provide a free chlorine residual up to the end of the
contact period:
Chlorine dose = chlorine demand + free available residual chlorine
To illustrate the effects of chlorine demand, water with a chlorine demand of 0.5 mg/L and a
residual requirement of 0.5 mg/L needs a dosage of 1 mg/L of free chlorine. Typical chlorine dosages for
ground water systems range from 0.2 to 4 mg/L.
For daily plant operation, calculations of the amount of chlorine needed to satisfy the chlorine
demand are in pounds per day. For example, the following equation calculates the amount of chlorine
required to satisfy a 1.0 mg/L dosage:
^,, Ibs A i7i f j\ j \ MR 1 1 ke Ib 3.78 L
CL - = Average Flow (gpd) x dose — ^ x - * - x - x -
2 day ( L ) 1,000,000 mg 0.45 kg gal
Systems must allow sufficient contact time for attaining the necessary CT values to achieve
proper disinfection of bacteria and viruses. For a given water, the longer the chlorine remains in the
water, the greater the inactivation of microorganisms. Depending on the necessary contact time and
particular types of treatment in place, systems can apply disinfectants anywhere between the wellhead and
the first customer.
Attainment of contact times occurs in the distribution system or in contact basins designed
specifically for the task. Types of contact basins include clear wells and treated water reservoirs with
flow-through piping. A basin with at least four compartments and baffle walls that distribute flow across
the cross-section of the basin is ideal. Baffle walls minimize flow short-circuiting and maximize the
utilization of the basin volume. Baffle walls also reduce inlet and outlet flow velocities, distribute water
over the basin's cross section and simulate a plug -flow reactor (Montgomery, 1985; WEF and ASCE,
1992).
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Small water systems can have difficulty attaining sufficient contact time, especially for those
systems that employ package plants or have limited space for water storage (NRC, 1997). These systems
may meet CT values by using enlarged or existing discharge pipes and contact basins dedicated to the
disinfection process. Applying chlorine in combination with other functions such as fluoridation and
water storage also assists systems in meeting CT values. For example, for small systems serving a
population of about 10,000 people, storage tanks with capacities of up to 30,000 gallons may suffice and
a change in the system's pumping structure may not be required. The following calculation demonstrates
this point (assuming a per capita flow of 150 gallons per day (gpd) and a contact time of 28 minutes):
10,000 people x 150 gpd x 28 min •*• 1,440 (—) = 30,000 gal
day
Exhibit 2.1 presents the required CT values established by the SWTR that achieve 2-, 3- and 4-
log inactivation of viruses with chlorine.
Exhibit 2.1 CT Values for Inactivation of Viruses by Free Chlorine (mg-min/L)
Temperature °C
0.5
5
10
15
20
25
Log Inactivation1
2.0
DH6-9
6
4
3
2
1
1
DH10
45
30
22
15
11
7
3.0
DH6-9
9
6
4
3
2
1
DH10
66
44
33
22
16
11
4.0
DH6-9
12
8
6
4
3
2
DH10
90
60
45
30
22
15
1Presents data for inactivation of Hepatitis A virus (HAV) at pH = 6, 7, 8, 9 and 10 and temperature = 0.5, 5, 10, 15, 20
and 25 degrees centigrade (°C). CT values include a safety factor of 3. To adjust for other temperatures, simply double
the CT value for each 10°C drop in temperature.
Sources: USEPA, 1991 a; AWWA, 1991b.
Higher temperatures and lower pH values (less than 8) correspond to lower CT requirements to
achieve a given level of inactivation. CT values generally increase by a factor of at least two to three
times for each 10°C fall in temperature. In other words, disinfection efficiency (measured as a percent
loss in inactivation) decreases with the decrease in temperature (USEPA, 1991a; AWWA, 1991b). Water
treatment chemistry literature defines a Q10 value as the factor by which disinfection rates increase for
each 10°C rise in water temperature (the Q10 empirical common rule). For temperatures below 5°C,
disinfection efficiency might be much less than that which follows the Q10 empirical common rule.
However, studies have not conclusively quantified disinfection efficiencies in waters with temperatures
below 5°C (USEPA, 1986). Exhibit 2.2 presents the effects of temperature on disinfection efficiency of
polioviruses. Many other factors such as the degree of mixing and turbidity may also affect CT values for
chlorination.
The pH of the water is an important factor in determining virus and bacteria inactivation since the
OC1' 'and HOC1 proportions change dramatically over a pH level range between 6 to 10. The biocidal
effectiveness office chlorine decreases with an increase in pH. HOC1 is one and a half to three times
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more effective than OC1' 'as a disinfectant. At a pH of 6, HOC1 comprises 98 percent of the HOC1/OC1''
pair. As pH increases, OC1' 'is more prevalent, and at a pH level of 10, the HOC1/OC1' pair consists of
over 99 percent OC1'' Temperature slightly affects this equilibrium; lower temperatures slightly favor a
higher proportion of HOC1 (USEPA, 1986), which in turn increases disinfection efficiency. However,
lower temperatures may often cause microorganisms to clump together as the viscosity and surface
tension of water increases. This may result in them being shielded from the disinfectant. As a result, the
stronger germicidal effect of the higher HOC1/OC1" ratio may get eroded slightly. Exhibit 2.3
demonstrates the decreased disinfection efficiency of Coxsackie B5 virus by free chlorine at increased
pH.
Exhibit 2.2 Inactivation of Poliovirus 1 (Mahoney) and Poliovirus 2 (MEF.,)
at pH 7, at 1 to 5°C and 25 to 28°C, with 0.20 to 0.30 ppm Free Residual Chlorine
(P., = Poliovirus 1, P2 = Poliovirus 2)
IOO.O
P,
25-28*C.
O.OI -
O ! 2
16
MINUTES
Source: Kelly and Sanderson, 1958.
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Exhibit 2.3 Inactivation of Coxsackie B5 Virus at pH 6 to 10 at 25 to 28°C
with 0.24 to 0.29 ppm Free Residual Chlorine
IOO.O
0 0!
0 I 2
16
MINUTES
Source: Kelly and Sanderson, 1958.
In general, research shows disinfection by chlorination is most efficient with relatively high
values for the chlorine residual, contact time, water temperature, and degree of mixing combined with
relatively low values for pH, and an absence of interfering substances. But high residuals are limited by
DBF Rules. The CT product exhibits the possibility for effective disinfection with low chlorine residuals
when combining long contact times with other factors beneficial for disinfection, such as low pH (around
6) and high temperatures.
2.2.2 Chlorine Gas
2.2.2.1 Background
Systems conduct chlorine gas disinfection by injecting chlorine gas into the water stream. In
general, large systems are more likely to use chlorine gas, since safety, space, and operational
requirements necessary for chlorine gas disinfection may be beyond the operational capabilities of many
small systems.
2.2.2.2 Description
A gas chlorination facility consists of chlorine (liquified/pressurized) cylinders, a scale, an
evaporator (if the chlorine is drawn from 1-ton cylinders, or if the daily chlorine capacity exceeds 4,000
pounds (Ibs/day)), a chlorinator, a control and residual analyzer unit, a combined gas line and gas blow-
off valve, injectors, and diffusers. Systems must store chlorination equipment away from other treatment
facilities and chemicals because chlorine gas is hazardous and corrosive. Systems must also supply safety
equipment, such as a leak detector, scrubber, and ventilation system and have a reliable electricity supply.
Contact basins often help systems attain sufficient contact times (Montgomery, 1985; White, 1986).
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Evaporating liquid chlorine using pressure feed or vacuum feed methods generates chlorine gas
used for drinking water applications. In the pressure feed method, diffusers release chlorine to the water.
In the vacuum feed method, the system supersaturates a small flow of water with chlorine and
subsequently returns it to the main water flow. Generally, systems prefer the vacuum feed method over
the pressure feed method because the vacuum feed method uses negative pressure, which is less likely to
result in a chlorine gas leak.
Systems store chlorine as a liquified or pressurized gas in cylinders. For relatively small
cylinders tubing from the top of the chlorine cylinders to the chlorinator transfers the chlorine gas. The
cylinders are set on platform scales to measure dosage by the loss of weight. Chlorine cylinders have
specific withdrawal rates (about 40 Ibs/day for a 150-lb cylinder). The withdrawal rate is the maximum
amount of chlorine gas a user can withdraw from the tank given the ambient water temperature and the
liquid chlorine temperature without freezing the liquid. For one-ton cylinders, users draw liquid chlorine
from the bottom of the cylinders and transport the liquid to an evaporator for conversion into a gas
(AWWA and ASCE, 1990).
A chlorinator is a supply metering device for chlorine gas controlled by regulated pressure (i.e.,
pressure feed method) and/or variable orifices (i.e., vacuum feed method). A system may manually or
automatically regulate the chlorine feed rate. A manual control chlorinator is sufficient for a small plant
or well water supply. In the vacuum feed method, the rate-control-valve of the regulator controls the flow
rate. The control unit also includes a gas release valve for ventilation in the event of gas leaks (Viessman
and Hammer, 1993). Injectors in the vacuum feed method use the pressurized water supply to create a
vacuum that draws chlorine gas at a set dosage through the regulator to the throat of the injector to mix
with water (Montgomery, 1985). After injection, throttling valves, or flow indicators, send the solution to
the point(s) of chlorination. In the pressure feed method the metering pump sends a set amount of gas
directly into the main water line under a specific pressure.
Systems may inject chlorine directly into the main plant flow, with or without the aid of diffusers.
Diffusers disperse chlorine across the cross section of the flow. Small pipes (less than 500-mm diameter
or 20 in) generally do not need diffusers. Montgomery (1985) recommends diffusers and supplemental
mixing for waters with a chlorine demand greater than 1 mg/L.
2.2.2.3 Operation and Maintenance
The general elements of operation and maintenance (O&M) for a chlorination facility are labor,
energy, and materials. The time spent on operation activities varies by the size of the facility and the
degree of automation at the facility. O&M costs include daily operation, preventive maintenance, and
periodic personnel training and certification.
Operation of a gas chlorination facility includes checking and replacing the chlorine cylinders
when necessary, checking the valves and flow meters, and monitoring for a chlorine residual. For some
systems, residual analyzers monitor the chlorine levels in treated water. Many analyzer systems, often
automated, include alarm signals for chlorine residuals that are too low or too high. These analyzers
require a continuous sample stream generated by sample pumps.
Personnel require training in the operation of gas chlorination systems. The costs of operator
training and certification may be an important cost factor for very small systems. Besides treatment plant
operation training, operators also need training on safety procedures and hazardous materials handling.
Safety precautions for gas chlorination systems include: checking for leaks in the chlorine cylinders and
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the gas chlorination transport tubing, replacing gaskets, and the annual cleaning of interior parts (AWWA,
199 la). Chlorine gas leaks are very dangerous, and therefore, systems must routinely monitor the system
for leaks. Necessary safety equipment includes a ventilation system and scrubbers, a shower and eye
wash, and chlorine gas detectors. In case of emergency, systems must also supply gas masks or self-
contained breathing apparatuses and store them outside of the chlorine cylinder storage area.
The final element of O&M of the chlorination facility involves the materials required for routine
operation, including chlorine gas, cleaning chemicals, and replacement parts.
2.2.2.4 Microbial Inactivation Capabilities
Gas chlorination is a well-established disinfection technology for inactivating pathogenic viruses
and bacteria. Chlorine disinfection can achieve 4-log or greater inactivation of viruses and bacteria. In
addition, EPA lists chlorine disinfection as a compliance technology for all system sizes in the SWTR.
The SWTR and SWTR Guidance Manual cite a number of studies conducted to demonstrate these
capabilities (USEPA, 1991a;AWWA, 1991b).
2.2.2.5 Advantages and Disadvantages
Many systems use chlorine gas disinfection to inactivate viruses and bacteria while providing a
distribution system disinfectant residual. Chlorine controls biological growth in water treatment plants,
water storage basins, pipelines, reservoirs, provides taste and odor control, enhances color removal, and
oxidizes iron and manganese to facilitate their removal through subsequent unit processes such as green-
sand filtration. Gas chlorination systems are also flexible and, when properly maintained, reliable.
One disadvantage of chlorination is that chlorine gas is toxic. At low levels, chlorine gas causes
eye irritation and respiratory problems; at high doses, serious injury or even death can occur. Chlorine
gas systems require regular maintenance and special safety precautions, such as a separate storage space,
ventilation, and scrubbing facilities. Liquid chlorine pressure tanks could present an explosion hazard if
not handled carefully. Plant operators are required to have hazardous materials training and must wear
protective clothing when working with chlorine gas.
Provision of adequate contact facilities may in some cases be impractical and/or cost-prohibitive.
Some small systems may not be able to afford the construction of new basins or oversized pipes to meet
CT requirements.
Another disadvantage of chlorine gas, along with other chlorine compounds, is the formation of
disinfection byproducts (DBPs). The formation of DBFs depends upon the presence of disinfection
byproduct precursors in raw water, indicated by the presence of Total Organic Carbon (TOC) or bromide
ion. Harmful byproducts form under certain temperature and pH conditions, chlorine residual
concentrations, and contact times with raw water containing these precursors. Some known byproducts
include trihalomethanes (THMs), haloacetic acids (HAAs), chloral hydrate, chlorophenols,
haloacetonitriles, carboxylic acids, ketones, and chloropicrin. Other uncharacterized chlorinated and
oxidized intermediates and byproducts may also be formed. Depending on these same raw water
conditions, chlorine may also leave an unpleasant taste and odor in finished water.
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2.2.3 Hypochlorite
2.2.3.1 Background
In comparison to chlorine gas, the storage and handling of hypochlorite is safer, and for this
reason many small systems that chlorinate their water prefer to use hypochlorite. Systems achieve
hypochlorite disinfection by injecting sodium or calcium hypochlorite solution (obtained by dissolving
granules in water to produce a stock solution) into the water stream.
Sodium hypochlorite (NaOCl) is commercially available in solution form containing up to 10 to
16 percent available chlorine (i.e., the percentage by weight of chlorine available from the commercial
grade chemical such as sodium hypochlorite). Calcium hypochlorite (Ca(OCl)2) is a solid compound that
dissolves easily in water and comes in tablet, granular, or powder forms containing at least 65 percent
available chlorine (USEPA, 1991b). Calcium hypochlorite is also available as a solution. Water
treatment plants more commonly purchase hypochlorite stock supplies in the granular or tablet form than
the solution form. Produced from lime, sodium and calcium hypochlorite may contain impurities with
varying concentrations of iron, chromium, and lead (USEPA, 1986).
2.2.3.2 Description
A hypochlorite facility consists of a solution tank, a pressure feed or vacuum feed system
(hypochlorinator) with a flow meter and controls, and a contact basin. The pressure feed system also
includes a diaphragm pump, which is run with electric or hydraulic power. The vacuum feed system also
includes the use of a venturi tube.
At the beginning of the process, the user mixes calcium or sodium hypochlorite granules with
water in a solution tank. An inflow water supply line from the main water line feeds water into the
chlorine solution tank. In the pressure feed method, the metering pump sends a set amount of solution
into the main water line through a chlorine discharge line and back to the main water line. Chlorinator
controls such as in-line digital residual monitoring electrodes monitor the chlorine concentrations, while
the water supply pumping unit controls the rate of water injection (USEPA, 1991a; AWWA, 1991b; EPA,
1993a).
The vacuum feed method employs the same type of system as the pressure feed method; however,
the flow of water through the vacuum regulates the flow of chlorine. Water in the system draws in the
chlorine solution by creating a vacuum as it passes through a venturi tube. An increased flow through the
pipe adds chlorine solution to the system. For this reason, the vacuum feed system, once in place, is less
likely to cause overdosing or underdosing than the pressure feed system.
A contact basin can be used to increase contact time if the distribution system pipes or existing
basins do not provide for it adequately. Since small systems generally use hypochlorite, manufacturers
sell them package systems sized according to necessary chlorine flow requirements. White (1986)
suggests that systems requiring three Ibs/day or less of chlorine and treating 200,000 gpd with a 2 mg/L
dose-rate use hypochlorination since it is most economical for systems of this size.
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2.2.3.3 Operation and Maintenance
The general elements of O&M for a hypochlorination facility are labor, energy, and materials.
The time spent on operation activities varies by the size and the degree of automation of the facility.
O&M costs include daily operation, preventive maintenance, personnel training, and in some cases
operator certification.
Hypochlorination systems require daily monitoring of the flow meters and chlorine residual
analyzer, preparation and addition of hypochlorite solution to the solution tank, replacement of the
gaskets, valves and diaphragms, and regular cleaning and backwashing. The solution container also
requires periodic cleaning.
The cost of training and certification for the operator may be an important cost factor for very
small systems even though the handling of hypochlorite does not require hazardous materials training.
Nonetheless, hypochlorite does require careful handling. Contact with hypochlorite can burn the skin and
may cause damage to the eyes. Safety procedures for hypochlorite include wearing gloves and a nose
mask when handling calcium hypochlorite. Systems must store hypochlorite in airtight, corrosion-
resistant containers located in a cool place because hypochlorite solids and solution decompose rapidly in
heat and because calcium hypochlorite reacts with moisture.
Most of the O&M power costs can be attributed to the operation of pumps/motors. Control
panels and automated residual analyzers also require an energy source.
The final element of O&M for a hypochlorination facility includes the materials needed to ensure
adequate equipment function. These materials include cleaning chemicals and replacement parts for
periodic maintenance and repairs.
2.2.3.4 Microbial Inactivation Capabilities
Hypochlorination is an effective, well-established disinfection technology used in the inactivation
of viruses and bacteria.
2.2.3.5 Advantages and Disadvantages
Hypochlorite can be as effective as chlorine gas, and in some cases, sodium or calcium
hypochlorite may be more advantageous than gaseous chlorine for small systems because they are easier
to handle, need less equipment compared to chlorine gas, and because spills and leaks of hypochlorite can
be more easily managed and contained than chlorine gas leaks.
Hypochlorites tend to increase the pH level, rendering them potentially less effective than free
chlorine at the same dose. They are also more expensive to purchase than chlorine gas and have a shorter
shelf-life, which can affect the feed rate and dosage. High concentrations of hypochlorite solutions are
unstable and can produce chlorite ions or chlorate byproducts.
Calcium and sodium hypochlorite solutions are corrosive and require procedures for cautious
storage and handling. Using calcium hypochlorite in powder form requires dust control practices to guard
against breathing calcium hypochlorite dust and minimizing skin exposure. Skin exposure is particularly
dangerous during the hot season when operators are sweating, allowing absorption into pores. For the
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same reasons, systems must store calcium hypochlorite in corrosion-resistant containers to minimize the
possibility of inadvertent exposure. In addition, containers must be stored in a cool, dark place, since
hypochlorites degrade over time, particularly if exposed to heat and light.
2.2.4 Temporary Hypochlorination
2.2.4.1 Background and Description
If a system is found to have a serious deficiency or fecal contamination, it may take time for the
system to design and install a corrective action. In the mean time, the system cannot serve the
contaminated water to its customers. The Primacy agency may require the system to apply 4-log virus
disinfection until the contamination is eliminated or a corrective action is put in place. It is assumed that
in the case of this interim disinfection, hypochlorination will be used because it is easier to install and
operate than gaseous chlorination or other disinfection methods and the least costly of the treatment
methods.
2.2.4.2 Implementation Issues
Temporary hypochlorination will perform in the same manner as the permanent hypochlorination
described above. The main difference is that the facilities will need to be portable as they will most likely
be installed directly at a well site. Operators will need to travel to the well site to take chlorine residuals
and periodically refill the tank.
2.2.4.3 Advantages and Limitations
Temporary hypochlorination will enable a system to continue serving water while allowing the
system to come up with a permanent solution to a significant deficiency or contamination problem. It will
protect customers against microbial contaminants but may not remove other potential contaminants (e.g.
arsenic, iron). If the wells have high dissolved iron or manganese concentrations, precipitation in the
distribution system could occur leading to customer complaints. Systems may also get customer
objections to newly chlorinated systems.
2.2.5 Chlorine Dioxide
2.2.5.1 Background
Chlorine dioxide (C1O2) is unstable, both as a compressed gas and as a concentrated aqueous
solution, and therefore requires on-site generation for use as a drinking water disinfectant (Masschelein,
1992). Under atmospheric conditions, C1O2 is a yellow to red colored gas with an unpleasant odor.
Chlorine dioxide is a powerful oxidizing agent. One of the more widely used procedures for synthesizing
C1O2 is the chlorine-chlorite process of the acidification of NaClO2. The overall reaction is:
5NaClO2 + 4HCI - 4CIO2 + 5NaCl + 2H2O
Mechanistically, this process occurs by a series of coupled reactions, some of which may involve
the in-situ formation of chlorine, the catalysis by chloride, and the oxidation of chlorite by chlorine
(Noack and Doerr, 1979; Gordon, et al., 1972). The yield of the reaction and its rate are improved by low
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pH values, in which both gaseous chlorine and chlorous acid formation are favored. During the acid-
chlorite reaction, the following side reactions also occur:
5C70T + 5H+ - 3CIO; + C12 + 3/T + H2O
4CIO2 + 4/T - 2C/2 + 3 O, + 2H2O
4HC102 - 2C102 + HC103 + HCl + H2O
If reaction stoichiometry is met, then close to 100 percent of the conversion of chlorite may
occur, and a final pH below 0.5 will result. The overall chemistry of C1O2 in acidic waters can be
summarized as:
CIO2 + 5e~ + 4H+ * Cr + 2H2O
At pH values near neutral or basic, the following base catalyzed reaction occurs (e.g., C1O2
reduces to chlorite):
2CIO2 + 2OH~ - CIO2 + CIO3~ + H2O
2.2.5.2 Description
A C1O2 generation system consists of a closed-loop or vacuum generator with a metering pump
and gravity flow or diaphragm pump, storage tanks for sodium chlorite or sodium chlorate, equipment for
gaseous chlorine addition, and a control panel that includes an alarm and shutdown system. Systems
generate C1O2 for drinking water application either by reacting:
• Chlorine gas with sodium chlorite (NaClO2) solution
• Chlorine gas with solid sodium chlorite
• Sodium chlorite with hydrochloric acid (HCl)
• Sodium chlorate (NaClO3) with "other reactants" such as H2O2 and H2SO4
For drinking water applications, the most frequently used method of generating chlorine dioxide
in the United States is by reacting a solution of sodium chlorite with chlorine gas:
2NaClO2 + C12 (g) ^ 2CIO2 + INaCl
One mole of chlorine is required to react completely with 2 moles of sodium chlorite (i.e., 0.78
part of C12 per part of NaClO2 by weight). Chlorine is normally overdosed to ensure the near complete
conversion of sodium chlorite. The excess chlorine in solution is converted to hypochlorous acid which
lowers the pH and increases chlorine dioxide production efficiency. As stated above, to generate chlorine
dioxide, systems use sodium chlorite in a solid or liquid form. Solid sodium chlorite is only 80 percent
pure, while sodium chlorite solution is 25 to 32 percent sodium chlorite by weight. Systems prefer to use
liquid sodium chlorite, however, due to the hazardous nature of solid sodium chlorite. As long as the
production of chlorine dioxide generates a 95 percent yield, with no more than 5 percent excess chlorine
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in the effluent, THM production will not occur (AWWA and ASCE, 1990). A properly operated and
maintained system will consistently attain a 95 percent yield.
In gaseous chlorine/sodium chlorite solution generation, the liquid sodium chlorite vaporizes and
travels to a reaction chamber through a metering pump. The chlorine gas mixes with water and travels to
the generator's reaction chamber where the two components react under a vacuum at a pH of 7. The
chlorine dioxide forms in the reaction chamber and travels to a contact chamber to ensure ample contact
time for disinfection before pumping the water through the distribution system. The design of this system
may use an eductor to add chlorine gas and sodium chlorite solution to the water stream before it enters
the reaction chamber.
An "enrichment loop" or "closed loop" system is another type of C1O2 generation system. This
generator employs a circulating water loop that ensures the introduction of high levels of dissolved
chlorine at a low pH into the reaction chamber. A pump transfers the sodium chlorite from a solution
tank to the reactor.
A newer technology reacts solid sodium chlorite with gaseous chlorine to produce chlorine
dioxide gas with less than or equal to 1 percent free chlorine. This generator reacts dilute, humidified C12
with NaClO2 in a sealed reactor cartridge. The amount of chlorine dioxide produced is a function of the
feed rate of chlorine and may range from 0 to 100 percent. This process generates chlorine dioxide gas
free of the chlorite and chlorate ions often produced in other types of generation systems with poor
generation efficiency (Hoehn et al., 1996; Berringer et al., 1996).
Manufacturers also make small wall-mounted units for chlorine dioxide generation. These units
generate chlorine dioxide through both the chlorine-chlorite process and the acid-chlorite process. Wall-
mounted models for the chlorine-chlorite process include flow rate meters that regulate the flows from the
gaseous chlorine supply and the sodium chlorite supply to the reaction zone. The C1O2 contacts the water
in the eductor and receives more contact time in the absorption column before flowing out to the water
supply. Wall-mounted units using the acid chlorite generation process have a similar configuration (CSU,
1996).
2.2.5.3 Operation and Maintenance
The time spent on operation activities varies by the size and the degree of automation of the
facility. O&M cost categories are daily operation, preventive maintenance, personnel training, and
certification.
The operation of a chlorine dioxide system requires a trained staff and continuous plant
monitoring. Operators require training in system start-up and shutdown, operation, equipment cleaning,
and feed pump and rotameter calibration. Daily operation of the system requires adjustments of flow
meters and rotameters that control the flow of C12 gas and NaClO2 solution. The enrichment loop system
is more complex, requiring additional maintenance of the pumps and assembly associated with the
recirculating loop. Also, operators require training in the O&M of gas chlorinators.
C1O2 generator efficiency requires frequent tuning, and the generator requires recalibration if the
production rate needs to be varied. Inefficient generators cause excess free chlorine resulting in the
formation of chlorite and chlorate ions. Generator systems employing chlorine gas/solid sodium chlorite
reactions ensure the presence of excess solid sodium chlorite, thereby limiting the presence office
chlorine in the reactor cartridge (Berringer et al., 1996).
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The cost of operator training and certification may be an important cost factor for small systems.
Operators require training in the operation and safety procedures for a chlorine dioxide generation system,
including hazardous materials training for the handling of chlorine gas, HC1, and NaClO2. Chlorine
dioxide spontaneously combusts at concentrations exceeding 10 percent by volume in air. Operation of
the generation system also requires proper handling and storage of chlorine gas cylinders and sodium
chlorite. Sodium chlorite may explode upon contact with oxidizable or combustible materials and needs
separate storage tanks in enclosed fireproof buildings with a water source nearby for assistance in the
event of a spill. In addition, systems should have chlorine gas detectors, floor drains, and emergency gas
masks available on-site (Corbitt, 1990).
The materials necessary to ensure adequate equipment function comprise the final O&M
component of the C1O2 facility. These include:
• chemicals that depend on the method used to generate C1O2 (i.e., chlorine gas, NaClO2,
NaClO3, HC1, H2O2, and H2SO4),
cleaning chemicals, and
replacement parts.
2.2.5.4 Microbial Inactivation Capabilities
Chlorine dioxide is a powerful disinfectant and is effective against viruses, bacteria, and highly
resistant protozoa (e.g., Cryptosporidium parvurri). EPA lists chlorine dioxide as a compliance
technology for the SWTR. The SWTR Guidance Manual (USEPA, 1991a; AWWA, 1991b) provides CT
values for inactivation of viruses as shown in Exhibit 2.4.
Exhibit 2.4 CT Values (mg-min/L) for Inactivation of Viruses1 by Chlorine Dioxide
for pH 6 to 9
Inactivation
2 Log
3 Log
4 Log
Temperature
•1°C
8.4
25.6
50.1
5°C
5.6
17.1
33.4
10°C
4.2
12.8
25.1
15°C
2.8
8.6
16.7
20°C
2.1
6.4
12.5
25°C
1.4
4.3
8.4
1 Studies pertain to the Hepatitis A virus.
Source: USEPA, 1991 a; AWWA, 1991b.
As with many other disinfectants, pH and temperature affect the efficiency of C1O2. In general,
the disinfection efficiency of C1O2 decreases as temperature decreases (Troyan and Hansen, 1989).
Decreases in temperature cause microorganisms to clump together as surface tension and the viscosity of
water increase. Consequently, they get shielded from the disinfectant, resulting in lowered disinfection
efficiency. For some protozoan cysts, researchers have found C1O2 to increase in effectiveness with an
increase in pH levels (Troyan and Hansen, 1989). Experiments by LeChevallier et al. (1996) suggest
oocysts inactivate more rapidly at a pH level of 8 than at a pH level of 6. However, other research studies
show chlorine dioxide's oxidizing potential decreases linearly as pH increases, although its effectiveness
on viruses and bacteria does not decrease (Masschelein, 1992). This may make it very effective in
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inactivating viruses typically found in ground water sources at pH values high enough for final
distribution.
2.2.5.5 Advantages and Disadvantages
In addition to its use as a disinfectant, chlorine dioxide can also oxidize metals such as iron (Fe)
and manganese (Mn), and control taste, odor, and color (Corbitt, 1990). Chlorine dioxide is advantageous
over most other disinfectants since it effectively disinfects over a wide pH range and has a persistent
residual. Chlorine dioxide does not produce problematic disinfection byproducts such as THMs, unless
too much chlorine is added during generation. Previously considered too complex for most small
systems, the availability of wall mounted units simplifies chlorine dioxide generation (CSU, 1996)
making chlorine dioxide generators more feasible for smaller systems, as long as staff are well trained in
their use.
Chlorine dioxide does, however, have its disadvantages. Some major concerns with chlorine
dioxide are its instability, the production of chlorite (C1O2~) and chlorate (C1O3~) during the generation
process, and the incomplete generation of C1O2 resulting in the presence of unreacted chlorite and
chlorate in water (Sawyer et al, 1994). Researchers note human health problems associated with these
byproducts (LeChevallier et al., 1996; USEPA, 1992a). Chlorine dioxide requires longer contact times
for virus inactivation relative to Giardia. Hence, chlorine dioxide systems aimed specifically at virus
inactivation require higher capital investment than chlorine-based systems.
Finally, the maintenance of chlorine dioxide as a disinfection technology must address many
safety issues and is therefore more expensive to implement than chlorine (USEPA, 2003). Chlorine
dioxide requires a separate, explosion-proof storage area and a highly trained staff to prevent accidents.
Due to this, it is rarely used in systems serving populations less than 100 and is scarcely used by systems
serving populations less than 1,000 (USEPA, 2003).
2.2.6 Anodic Oxidation
2.2.6.1 Background
The anodic oxidation (on-site oxidant generation) disinfection process uses electrolysis of sodium
chloride in water by sending an electric current through the salt water. A reaction follows producing
various oxidants for disinfection or oxidation of pollutants in raw water (Bradford and Baker, 1994). A
cation exchange membrane separates the oxidants generated at the anode from the reactants at the
cathode. Oxidants presumed to be produced include hypochlorite ion (OCr), HOC1, ozone (O3), chlorine
dioxide (C1O2), and hydrogen peroxide (H2O2). Bradford and Baker (1994) studied the anodic oxidation
process and confirmed the presence of HOC1, OCr, C1O2 and O3 in the oxidant stream. However, they
were unable to verify the presence of H2O2. The verification of concentrations of oxidants produced at
the anode requires additional research. The presence of multiple oxidants enhances the oxidizing strength
of the solution such that it is a more effective disinfectant than a solution containing a single oxidant or
disinfecting agent.
2.2.6.2 Description
Anodic oxidation units are package units that generally consist of a storage tank, oxidant
generator (or cell) and storage tank, an injector, a control panel, and necessary pumps and piping.
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Additional system requirements include housing space for the equipment and an electric power supply or
solar panels. To ensure proper operation of the anodic oxidation system, the raw water source requires
removal of hardness prior to disinfection. Water with a conductivity of more than 150 • mhos/cm
requires a water softener (MIOX, 1997). Additionally, some substances that may occur in the source
water exert a chlorine demand. System designers must account for these substances, which include
organics, iron, manganese, and sulfides.
Energy required for the production of chlorine from salt varies among devices from different
manufacturers. Smith and Loveless, Inc. (1996) indicate that for their units, using 3.5 kilowatts (kW) of
electricity and 3.5 pounds of sodium chloride (NaCl) can produce 1 pound of chlorine. Units
manufactured by Chemical Services Company, Inc. (CSC, 1996) require 3.5 Ibs of salt, 2.5 kW of
electricity, and 15 gallons of water to produce 1 pound of chlorine. Units from MIOX, Inc., vary in their
efficiency; the higher the treated flow, the more efficient the treatment unit (MIOX, 1997). The system
uses food grade salt with granules less than 0.5 millimeters (mm), containing no additives or inhibitors.
Some generators work well using sea water as a raw material. Smith and Loveless, Inc. (1996)
indicate this disinfection technology is ideal for use at sea and at shorelines where sea water provides the
raw material for generating oxidants on-site. For most manufacturers, the sea water models and salt
models differ from one another. Salt intakes and production efficiencies vary by manufacturer. Exhibit
2.5 summarizes the oxidant production capabilities based on salt consumption for four of MIOX's
models, assuming a need for a dosage of 1 ppm chlorine equivalent to obtain a proper residual.
Exhibit 2.5 Oxidant Production Efficiency of Four of MIOX's Models
Gallons per day treated at 1 ppm dosage
Salt consumption
Daily free available chlorine production
MIOX Brine
Pump System
25,000
1 Ib/hr
0.5 Ibs/day
MIOX Model
SAL-20
250,000
3 Ibs/hr
1 .7 Ibs/day
MIOX Model
SAL-30
330,000
3 Ibs/hr
3.7 Ibs/day
MIOX Model
SAL-40
600,000
3.5 Ibs/hr
7 Ibs/day
Source: Vendor Estimates.
Several systems have successfully used anodic oxidations to maintain a residual throughout the
distribution system. Hamm (2002) summarized research from several systems using anodic oxidation and
found that systems achieved an average dose reduction of 30 percent while still maintaining adequate
residuals over lengths of pipe as long as 9 miles. Minimizing solution storage is critical to maintaining a
residual. Under most conditions, injection of the solution generated into the raw water stream is
immediate. Extended periods of storage in the pH range 4.5 to 8.8 allows the solution to breakdown.
When stored for up to 10 hours prior to disinfection, the solution requires an upward pH adjustment prior
to storage (Bradford, 1995). An increase in temperature also increases the rate of oxidant breakdown.
Therefore, systems should store the generated solution in a relatively cool location.
2.2.6.3 Operation and Maintenance
The general O&M elements of an anodic oxidation facility are labor, energy and materials. O&M
of an anodic oxidation facility includes daily operation, preventive maintenance, and personnel training
and certification. Systems purchase anodic oxidation units as a package, spending minimal operational
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time. Operation requires salt addition and routine control panel checks. Because some treatment and
regulatory requirements necessitate the presence of a residual disinfectant, operation also requires
analysis of treated water for a chlorine residual. The demand on the electrodes used in the process is
high. Efficient unit function requires electrode resistance to electric and chemical corrosion, and the
absence of heavy metals.
The manufacturer generally provides the O&M training on anodic oxidation package units
(MIOX, 1997; CSC, 1996). Generator and pump operations require a stable energy source and smaller
units can be solar powered. Efficiency increases with unit size, requiring less salt and less energy per
pound of chlorine generated.
The final O&M component for the facility are the materials required to ensure that the equipment
functions adequately. The consumable materials required include salt, cleaning chemicals, and small
replacement parts for periodic maintenance and repairs.
2.2.6.4 Microbial Inactivation Efficiencies
Early research by Mahnel (1978) determined the effectiveness of anodic oxidation on inactivating
viruses. Mahnel tested 11 viruses at concentrations up to 104 infectious units/mL in non-chlorinated tap
water. Anodic oxidation inactivated all 11 viruses. The degree of contamination did not affect the
results, although the virus inactivation occurred more easily in water with a higher conductivity and a
greater current density. The 11 viruses included poliovirus, enteric cytopathogenic bovine orphan
(ECBO), Sindbis, influenza-A, Vesicular Somatitis (VS), bovine parvovirus (BPV), reovirus, Newcastle
Disease Virus (NV), hepatitus contagiosa canis (HCC), pseudowut, and vacciniavirus.
Current research shows that anodic oxidation can be more effective than chlorine in the
disinfection of bacteria, viruses, and protozoa (MIOX, 1997; Venczel et al., 1997; USEPA, 1997b).
Research by Bradford and Baker (1994) suggests the anodic oxidation solution is capable of greater than
4-log inactivation of Vibrio cholerae and f-2 bacteriophage, as well as a 3- to 5-log inactivation of E. coll.
Venczel et al. (1997) also showed on-site oxidant generation was effective in inactivating viruses such as
MS-2 and bacteria such as E. coll and V. cholerae.
Anodic oxidation may provide more effective disinfection than chlorine gas, with lower contact
times. However, CT values for anodic oxidation are unknown. The efficiency of anodic oxidation on
pathogen inactivation requires further study and clarification (Venczel et al, 1997; USEPA, 1997b). The
ability of anodic oxidation to produce mixed oxidants also requires further study. Until more CT
information is available, EPA suggests using CT values for chlorine. Although these are conservative
values, they will ensure adequate time for disinfection. The MIOX manufacturers specify the units (by
Ibs) of chlorine produced for every unit of salt, electricity, and water consumed. This information could
be used to calculate the CT value and ensure the minimum level of disinfection needed.
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2.2.6.5 Advantages and Disadvantages
As stated in section 2.2.5.4, anodic oxidation disinfection is effective against bacteria and viruses.
Anodic oxidation disinfection is simple and reliable. The principles behind anodic oxidation disinfection
enable these systems to operate with potentially lower health or environmental impacts than traditional
chlorination methods. Specifically, there is no hazardous substance handling involved in this disinfection
process, thus reducing the risk of leaks and potential health impacts. When compared to other
disinfection technologies, anodic oxidation systems are cost-effective at design flows around one million
gallons per day (mgd) and slightly greater.
The compact, packaged anodic oxidation units provide additional benefits for systems with
limited space, especially small systems. EPA lists anodic oxidation as a small-system technology for
compliance with the SWTR(USEPA 1997b).
Case studies of water systems using anodic oxidation verify that anodic oxidation produces fewer
total trihalomethanes (TTHMs) than disinfection with chlorine gas (Daniel, 1995; MI OX, 1997).
Laboratory research suggests varying results regarding TTHM production. Research by Bradford and
Baker (1993) demonstrated that anodic oxidation reduces TTHM production by 50 percent in comparison
to free chlorine, while research at the University of North Carolina (Venczel et al., 1997) found that
anodic oxidation and free chlorine produced similar levels of TTHM.
The main disadvantage of anodic oxidation is higher O&M costs associated with high electrical
power requirements.
2.3 Chlorine-Free Treatment Technologies
This section discusses the following chlorine-free disinfection and pathogen removal
technologies: ozone and NF. Many systems use NF for the removal of contaminants other than microbial
contaminants and its applicability for the removal of pathogenic organisms is very promising.
2.3.1 Ozone
2.3.1.1 Background
According to survey data from the International Ozone Association (Dimitriou, 1997) more than
60 ground water treatment plants in the United States currently use ozonation. The majority of these
plants use ozone for oxidation of iron and manganese and control of taste and odor. More than a dozen
systems use ozone primarily for disinfection. Ozone disinfection is uncommon among very small
community and noncommunity water systems. One noncommunity water system uses a wall-mounted
ozone generator with an automatic shutdown mechanism that is used in case of an ozone leak.
2.3.1.2 Description
Ozone disinfection systems require some basic components including an oxygen source, air
blower, dust filter, air compressor, cooler and dryer, electric power supply, ozone generating equipment,
ozone contactor, filter system, off-gas collector/controller (also known as an ozone destruction unit),
control panel with an ozone gas detector and alarm, and a residual monitoring system. Because ozone is a
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hazardous compound, a separate building often houses the system (Viessman and Hammer, 1993;
Masschelein, 1992).
The components of an ozone disinfection system comprise four main process categories, which
are described below (DeMers and Renner, 1992).
Feed-Gas: A system requires an oxygen source to generate ozone. The oxygen source can be
natural clean dry air, oxygen-enriched air, or oxygen gas. Most systems prefer oxygen gas as an oxygen
source because it requires no preparation or treatment before use as a feed gas. The use of air requires
devices to dehumidify and clean the air of dust and other impurities. Using humid, dirty air will result in
the formation of undesirable byproducts along with the ozone. In addition, excess humidity can affect the
ozone production yield (Viessman and Hammer, 1993; Masschelein, 1992). The use of dry or water-ring
compressors dehumidifies the air. The compressors require high-quality stainless steel construction.
Chemical dehumidifiers such as CaCl2, silica gel, or activated alumina can eliminate the remaining
humidity. For small systems producing less than 100-lbs of ozone per day the preferred oxygen source is
air because of the safety issues and costs associated with handling liquid oxygen (USEPA, 1993a).
Ozone Generation: The second step in the disinfection process is ozone generation. Electric
voltage controls the rate of ozone production. There are many types of ozone generators including:
horizontal and vertical dielectric (non-conducting) glass tubes (Welsbach Tube and Megos and Wedeco
ozonators), and glass or ceramic plate dielectric generators (Otto Plate Ozonator). Horizontal dieletric
glass tube ozonators are widely used for water treatment. This ozonator is a glass tube, sealed at one end,
that forces gas to flow through the discharge gap. The dielectric glass is coated with aluminum on the
inside, which acts as the second electrode (Masschelein, 1992). In glass or ceramic plate generators, the
generation of ozone occurs between the plates. All ozonators produce heat, therefore cooling is
important. Cooling the tubes or plates increases the efficiency of ozone production (AWWA, 1990a).
Ozone Contacting/Absorption: The third and most important step in the ozone disinfection
process is ozone contacting and absorption. Currently, ozone systems require separate contactors. Ozone
transfer into water allows for disinfection in the contactor. The most commonly used contactor is a
bubble diffuser contactor which consists of a countercurrent tank with a porous diffuser. The primary
reasons for the common usage of bubble diffuser contactors include: no requirements for additional
energy (except initial gas compression), proven performance, high transfer rates, and process flexibility.
Moreover, bubble diffuser contactors have no moving parts.
To achieve 85 to 95 percent transfer efficiency, bubble diffuser contactors typically require 18- to
22-ft water depths. Since not all of the ozone transfers to the water, systems contain the off-gas by a
covered basin. Continuous stirred-tank reactors (CSTR) and baffled chambers are additional types of
contact basins. An axially submerged turbine in countercurrent flow can also act as a contactor. The
system includes a flow tube with baffles to provide for sufficient contact time. A pump forces the liquid
and gas in a co-current flow (i.e., in the same direction). Baffles create turbulence and increase the rate of
gas-liquid mass transfer (USEPA, 1991a; AWWA, 1991b). Because ozone reaction with materials in the
water produces suspended solids and colloidal particles, systems should filter to retain the colloidal
particles and suspended solids. Ozone in water is corrosive, therefore contact basins should consist of
concrete with at least American National Standards Institute (ANSI) 304 stainless steel reinforcing beams.
Systems should use ozone resistant pipe material and inert polymer gaskets (AWWA, 1990a).
Off-Gas Destruction: The final process in ozone disinfection is destruction of the unused ozone.
Excess ozone may pass through a valve to the off-gas controller, or ozone destruction unit. Off-gas
routing to a secondary disinfection contactor is also possible. Excess ozone from this unit then travels to
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an ozone destruction unit (CCC, 1991). This destruction unit converts the ozone to oxygen by passing the
ozone through a metallic oxide catalytic converter. Other off-gas destruction units destroy ozone by heat,
heat-catalyst, and/or activated carbon. Because ozone is a toxic gas, ozone existing in the decomposer
exit should be less than 0.1 percent by volume. For safety reasons, systems should regularly monitor flue
gases.
2.3.1.3 Operation and Maintenance
The general O&M needs for an ozonation facility are labor, energy, and materials. The three
O&M cost categories are: daily operation, preventive maintenance, and personnel training. The time
spent on operation activities varies by the size of the facility. Although ozone generators are complex,
they use complete automation, and require modest amounts of time for routine maintenance. Well-trained
technicians require preventive maintenance and repair training to operate the ozone generator. This
includes checking the generator and keeping system parts clean. Ozone is a strong oxidizer, therefore the
system parts require cleaning to prevent corrosion. Parts requiring occasional cleaning are the ozone
contacting unit and the ozone exhaust gas destruction unit. Other parts for the dehumidifying process also
require cleaning and maintenance. In addition, users must clean the air preparation or oxygen feed, and
dehumidify the saturated desiccant. Removing these areas from the ozonation process and heating them
accomplishes these tasks.
Ozone leaks in and around the ozone generation facility may create a health hazard to operators
of the treatment plant and may destroy or enhance the wear of other equipment materials. Therefore,
facilities must apply strict safety measures, install an ozone gas detector, and periodically check alarms.
The materials needed to ensure the equipment functions adequately comprise the final O&M
component of the ozonation facility. Materials include cleaning chemicals, replacement parts, and
additional necessary supplies for periodic maintenance, system cleaning, and unanticipated breakdowns.
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2.3.1.4 Microbial Inactivation Capabilities
Ozone is a powerful oxidant that reacts rapidly with organic and inorganic compounds in water,
although a slower reaction occurs with organic materials than with inorganic compounds. Ozone does not
react with water, but instead decomposes quickly in water to produce oxygen and hydroxyl free radicals,
which in most waters act as the main participants in oxidizing most organic and inorganic molecules in
the water. This decomposition does not leave a disinfection residual, but ozone has a high disinfection
capacity due to its high oxidation potential (Rice et al., 1981; Masschelein, 1992).
Ozone decomposition is enhanced by a variety of factors such as high pH, humic materials, and
transition metal ions. Decomposition of water yields hydroxyl ion (OH") (i.e., 2H2O • •H3O+ + OH")
which initiates the following sequence of reactions:
(1) OH- + O3 • ffO2 + O2
(2) HO2 • ff+ + O2
(3) 02- + 03 • 02 + 03
(4) O3- + H+ • ffO3
(5) HO3 • O2 + HO"
(6) HO'^O3 • ffO2 + O2
This is a chain reaction mechanism since the HO2 generated in step 6 can initiate a new chain
through steps 2-6. Since the hydroxyl radical (HO *fis a very powerful oxidizing species, when O3
decomposes, its oxidizing power is not necessarily lost if the hydroxyl radical can be efficiently utilized.
Bicarbonate increases the lifetime of O3 by stopping the chain mechanism by reacting with the
OH radical intermediate as follows:
HO'^r HCO3~ • OH- + HCO3"
The HCO3 'radical is a relatively unreactive radical that cannot propagate the chain. Thus, waters
high in bicarbonate alkalinity and low in other contaminants will retain an O3 residual for longer periods
than low alkalinity, high-TOC waters (Staehelin and Hoigne, 1985; Hoigne and Bader, 1983). Only
under high bicarbonate alkalinity does O3 assert itself as a somewhat dominant oxidizing species;
otherwise the disinfection power comes mainly from the HO 'free radical.
Typical ozone doses for ground water sources range from 1 to 3 ppm. For color removal in some
waters, doses may be as high as 8 ppm; however, this only occurs under extraordinary circumstances. In
terms of oxidation of organic matter, Masschelein (1992) suggests using 0.15 to 0.2 mg ozone per mg/L
of TOC. The SWTR lists ozonation as a disinfection technology able to achieve the required 4-log virus
and 3-log protozoa inactivation. Exhibit 2.6 provides CT values for virus inactivation by ozone.
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Exhibit 2.6 CT Values (mg of O3-min/L) for Virus Inactivation by Ozone
Inactivation
2-Log
3-Log
4-Log
Temperature
•1°C
0.9
1.4
1.8
5°C
0.6
0.9
1.2
10°C
0.5
0.8
1.0
15°C
0.3
0.5
0.6
20°C
0.25
0.4
0.5
25°C
0.15
0.25
0.3
Sources: USEPA, 1991 a; AWWA, 1991b.
Hall and Sobsey (1993) studied the inactivation of HAV and MS-2 by ozone and an ozone/
hydrogen peroxide combination at a pH range of 6 to 10. The researchers found that both HAV and MS-
2 became inactive after five seconds at an ozone concentration of 0.4 mg/L. Using these short contact
times an applied ozone dose between 0.3 and 2 mg/L will achieve 3.9- to 6-log virus inactivation. In
addition, when applying ozone for five minutes Finch et al. (1992) found 3-log inactivation ofGiardia
muris and enteric viruses using an ozone residual of 0.5 mg/L, and 4-log inactivation ofGiardia muris
and enteric viruses using an ozone residual of 0.6 mg/L.
2.3.1.5 Advantages and Disadvantages
Ozone has powerful disinfection capabilities. Its high diffusion characteristics make it one of the
most efficient chemical disinfectants with its contact time of only a few minutes. For this reason, the
SWTR lists ozone as a treatment technology for all public water systems (PWSs) (USEPA, 1997b).
Ozone inactivates microbes without forming THMs. Ozone also oxidizes iron and manganese, and
improves the taste, odor, and color of raw water. It enhances the biodegradability of natural and synthetic
organic compounds and destroys many organic compounds. Production of ozone from air requires no
storage space for chemicals. Due to its relatively short half-life and safety issues, ozone may require on-
site production. Due to the difficulty in determining an adequate dose, ozone is most beneficial to
systems with a constant demand or little demand fluctuation, such as ground water systems.
Disadvantages of ozone include its relatively high cost and complexity in its use (AWWA,
1990a). Ozone decomposes quickly in water and therefore does not provide an adequate residual to
protect against recontamination in distribution or water storage systems. Therefore, secondary
disinfection may be required. If the source water has a high bromide concentration, ozonation in
conjunction with chlorination could result in high concentrations of brominated DBFs in finished waters.
Ozonation also results in significant bromate ion production if the source water has high bromide levels.
Water containing large amounts of organic matter and bromide may increase ozone demand and
the potential for byproduct formation. However, high natural organic matter (NOM) content in raw
waters is generally not a concern for most ground water systems. Moreover, the placement of a carbon
filter before or after the ozonation process can reduce ozonation byproducts. The pre-ozonation carbon
filter removes the NOM that serves as a precursor to the formation of byproducts. Byproduct formation
depends on pH and the ratio of ozone to bromide and TOC to bromide, as well as ozone to TOC.
Depending on the amount of organic matter and bromide present, byproducts such as nitrates, oxalic
acids, carboxylic acids, sulfonic acids, nitrophenols, aldehydes and ketones may form. Ozone can cause
incomplete oxidation of some organic compounds and ozone may react with unsaturated aliphatic or
aromatic compounds to form acids, ketones, and alcohols. This material can serve as a carbon source for
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bacteria in the distribution system, increasing the amount of biofilm growth in the system. At a pH
greater than 9, ozone may form toxic phenolic structures in the presence of the redox salts, such as iron,
manganese, and copper aromatics (Eckenfelder, 1991).
2.3.2 Nanofiltration
2.3.2.1 Background
NF employs very high pressures and thin film membranes to filter particles of sizes on the order
of 10 nanometers (nm). Viruses range in size from 20 nm to 900 nm. NF membranes have pore sizes that
are much smaller than those of microfiltration (MF) or ultrafiltration (UF) and typically remove particles
between (5 to 10 nm) (USEPA, 1993a). NF membranes used for potable water applications typically use
molecular weight cut-offs of 200 to 400 daltons (i.e., approximately 2 to 4 nm).
2.3.2.2 Description
Manufacturers often use a variety of cellulose and non-cellulose materials, including cellulose
acetate, cellulose diacetate, cellulose triacetate, polyamide, other aromatic polyamides, polyetheramides,
polyetheramines, and polyetherurea in the construction of NF membranes. NF systems employ pressures
between 70 psi and 150 psi and flux rates ranging from 15 to 25 gallons per day per square feet (gpd/ft2).
However, this may not necessarily limit NF to small systems applications. Membranes vary in size and
can be configured to treat large volumes of water.
An NF membrane system train consists of chemical addition for pretreatment and pH adjustment,
a cartridge filter for removal of large particles that may foul the membrane system, medium to high
pressure booster pumps for the feedwater, membrane vessels, a disposal system for concentrate, a
degasifier, a clearwell for the addition of post-treatment disinfection and softening agents, and a transfer
pump to water storage or to the distribution system.
2.3.2.3 Operation and Maintenance
The general O&M elements for an NF facility are labor, energy, and materials. O&M cost
categories include daily operation, preventive maintenance, residual disposal, and periodic personnel
training.
Operation of an NF facility requires cleaning the pretreatment filters, disinfecting and cleaning
the membrane to prevent fouling, and checking the system to ensure proper operation. Systems must also
prevent membrane scaling through chemical cleaning. Depending on influent water quality, the
membrane may require cleaning every few days to every few months.
For an NF system, the quantity of residual concentrate directly relates to the recovery of the
membrane system. The periodic application of treatment residuals consisting of chemical cleaning
solutions and backwash water removes solids from the membrane surface. Systems discharge membrane
concentrates to surface waters such as lakes, rivers and oceans (requiring a National Pollutant Discharge
Elimination System (NPDES) permit), injection wells (under the Underground Injection Control (UIC)
program), sewers or Publicly Owned Treatment Works (POTWs) (possibly requiring State or local
permits), or evaporation ponds. Federal, State and local authorities, regulations, and permitting
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requirements regulate disposal methods. Disposal costs and geographic location are additional factors
affecting the membrane type selection and disposal options for a plant.
NF's high operating costs are primarily due to its high energy and materials requirements. NF
also requires the use of many materials and chemicals to prevent membrane fouling and to ensure
adequate system functions. Membranes are expected to have at least a 3 to 5-year lifespan; replacement
costs for the membranes are considerable (see Chapter 3 for costing details).
2.3.2.4 Microbial Removal Capabilities
In drinking water applications, NF is a common technology for water softening and NOM
reduction. Additionally, NF is very efficient in simultaneously controlling THM precursors, hardness,
and microbial contamination (USEPA, 1993a; Morin, 1994). Because of its very small pore size, NF can
remove both large (e.g., Giardia lamblia) and very small microorganisms (e.g., enteric viruses) (AWWA,
1990a).
2.3.2.5 Advantages and Disadvantages
NF membranes can achieve absolute pathogen removal. NF membranes can also remove some
colloidal material and organics, and are extremely effective in removing disinfection byproduct
precursors (Exhibit 2.7). Due to improvements in synthetic membrane materials, NF membranes can
remove DBF precursors in addition to organics and some total dissolved solids (TDS). Although capital
costs for membrane technologies are high, the ease of adding additional modular components allows for
future increases in treatment capacity with reduced capital costs (Hillis et al., 1996).
O&M costs for NF membranes are high because operation requires skilled and intensive labor to
perform activities such as chemical cleaning and pretreatment for turbidity and suspended solids. NF
membranes have up to a 90 percent recovery rate.
NF membranes do not provide any residual disinfection to control microbial growth in the
distribution system or inactivate contaminants introduced to the water supply after filtration. Systems that
require a disinfectant residual must use a secondary disinfection technology in conjunction with NF.
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Exhibit 2.7 Particle Sizes and Membrane Process Ranges
Macromolecules
Particle size: |
Viruses 5 - 500 nm
Animal Plant
Bacteria 50-1000 nm
1 1 1
A° 10° 101 102 103 104 105 106 107 A°
nm 10'1 10° 101 102 103 104 105 106 nm
•to. 104 10'3 ID'2 ID'1 10° 101 102 103 «m
mm 10'7 10'6 10'5 104 10'3 10'2 10'1 10° mm
ATOMIC RANGE COLLOIDAL RANGE MACROSCOPIC RANGE
1
H2O Molecule
1.45A0
Membrane Polk
processes: 27
Reverse Osmosis
Red Blood Cell
1.3'fti
Resolution of Light Microscope
Smallpox
200 nm
Resolution of Electron Microscope
3 virus
nm
50%
70%
Nanofiltration
60%
85%
Ultrafiltration
80%
90%
Microfiltration
94%
99%
Product Water Recovery Rates (%)
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2.4 Applicability Matrix
Exhibit 2.8 presents a matrix summarizing key attributes for the drinking water treatment
technologies discussed in the preceding sections of this chapter. For each technology, the matrix lists the
inactivation or removal efficiency for a specific virus and contact time necessary to achieve the described
inactivation or removal. The matrix also indicates whether the technology is capable of maintaining a
disinfectant residual and if the technology employs hazardous materials.
Exhibit 2.8 Applicability of Drinking Water Treatment Technologies
for Virus Inactivation or Removal
Technology
Gaseous Chlorine
Sodium Hypochlorite
Calcium Hypochlorite
Anodic Oxidation2
Chlorine Dioxide
Ozone
Nanofiltration
Virus
HAV
HAV
HAV
HAV
HAV
poliovirus
NA
Inactivation
or Removal
Efficiency
4- log
4- log
4- log
4-log
4-log
4-log
absolute
CT(min-
mg/L)1
4
4
4
4
16.7
0.6
NA
Ability to
Maintain a
Residual
Yes
Yes
Yes
Yes
Yes
No
No
Hazardous
Materials
Yes
No
No
No
Yes
Yes
No
1Contact times assuming a temperature of 15°C, a pH of 6-9 for use in the GWR preamble for comparison purposes
only.
2.5 Risk/Risk Trade-Offs
2.5.1 Formation of Disinfection By-products
Several disinfection processes can lead to the formation of DBFs. DBFs have been associated
with potential health risks, including adverse reproductive and developmental effects and cancer.
Systems treating water for microbial contaminants must consider the potential for DBF formation when
selecting a disinfection technology or other corrective action. DBFs are a result of reactions of the
organic matter in source water with free chlorine and bromide, if present. This reaction continues to
occur over time, and residence time in the distribution system becomes an important factor. The
remainder of section 2.5.1 presents the occurrence of DBF precursors (TOC and bromide) and DBFs
(THMs and F£AAs). Generally, DBF concentrations in disinfected ground water systems are low relative
to surface water systems because of lower precursor levels in ground water sources.
2.5.1.1 Sources of Data
Several data sources are available for analyses of precursor and DBF data. These data sources are
described below, followed by summaries of key data from each source.
Information Collection Rule: The Information Collection Rule (ICR) data collection focused on
large PWSs, which serve populations of at least 100,000 people. About 300 PWSs (both surface and
ground water systems) operating approximately 500 treatment plants participated in this extensive data
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collection. Out of these 500 plants, 129 are classified as ground water plants (i.e., using only ground
water). A more limited set of ICR requirements covered ground water systems serving 50,000 to 100,000
people. Over an 18-month period, PWSs monitored influent water quality parameters affecting DBF
formation and DBF levels in the treatment plant and the distribution system. PWSs also provided
operational data and descriptions of their treatment plant design. Systems began monitoring in July 1997
and completed monitoring in December 1998. Summaries of ICR precursor and DBF data are presented
in Exhibits 2.9 through 2.11.
Water Utility Database (WATER:\STATS): Published by the American Water Works
Association (AWWA), WATERV STATS is derived from the AWWA Water Industry Database (WIDE)
resulting from a 1996 survey of approximately 900 water utilities, mostly entities serving at least 10,000
people (approximately 30 systems in the database serve fewer than 10,000 people). The effort collected a
range of financial and operational information on these systems, including data on the occurrence of
DBFs in finished water (however, many systems did not respond to all questions). WATER:\STATS
does not contain individual sample results; rather it contains minimum, maximum, and average values
reported by each system. The WATER:\STATS data presented in this document are of TOC and TTHM
data from medium and large ground water systems. Summaries of WATER:\STATS precursor and DBF
data are presented in Exhibits 2.9 and 2.11.
The Ground Water Supply Survey (GWSS): This survey, conducted by EPA in 1981-82, was
designed to collect treatment, influent water quality, and finished water contaminant occurrence
information on 979 small, medium, and large ground water systems from across the United States.
Although THM data from this survey are available, they are probably not representative of current THM
levels for large and medium systems because they were collected more than 20 years ago. In addition, the
TTHM data were collected only at the entry point to the distribution system and THM concentrations
continue to increase through the distribution system. A summary of GWSS TOC data is presented in
Exhibit 2.9.
AWWA Survey (1998): In January 1997, McGuire Environmental Consultants conducted an
AWWA survey of 298 ICR systems (see description of the ICR above). Data were collected from ground
water systems serving more than 50,000 people in the United States. Two hundred seventy-five utilities
provided three months of TOC data collected in September, October, and November 1996. A summary
of AWWA Survey (1998) TOC data (based on 110 ground water plants) is presented in Exhibit 2.9.
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Exhibit 2.9 TOC Concentrations (mg/L) in Influent Water
Data Source
ICR
Water: \Stats - Large systems
Water: \Stats - Medium systems
GWSS1 - Large Systems
GWSS1 - Medium Systems
GWSS1 - Small Systems
AWWA(1998)
Mean
1.67
2.0
2.3
1.06
1.32
1.18
1.35
Median
0.23
1.0
0.8
0.5
0.7
0.6
0.76
90th Percentile
4.15
3.5
7.0
2.0
3.2
2.9
N/A
Range
0-15.9
0-14
0-25
0-11
0-14
0-18
0-12.9
1 GWSS TOC data taken from the finished water.
Exhibit 2.10 Bromide Concentrations (mg/L) in Influent Water
Data
Source
ICR
Mean
0.10
Median
0.06
90th Percentile
0.19
Range
0-1.32
Exhibit 2.11 THMs (mg/L) in Distribution System Water for Disinfecting
Ground Water Systems
Data Source
ICR1
WaterAStats -
Large systems
WaterAStats -
Medium systems
Mean
45.1
24
19
Median
40.1
12
10
90th Percentile
80.6
57
50
Range
0-236
0-91
0-121
1 ICR statistics are of Distribution System Average, which is the average of four locations
in a given plant's distribution system for a given sample period.
2.5.2 Colored Water
Another potential problem involved in installing disinfection treatment technologies is the
possibility of the disinfectant reacting with pipes and pipe scales to produce colored water.
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2.5.2.1 Definition of Problem
The chemistry involved in disinfecting previously undisinfected ground waters can, in some
cases, cause concerns such as increased nuisance complaints from customers and potential violations of
the SDWA color standards for PWSs. Oxidization of certain metals, such as iron and manganese, present
in source waters may be the source of color problems. It is also possible that oxidation of the existing
corrosion scales in a cast iron or ductile iron pipe may release metals that color the water. Color does not
itself pose a health risk. However, color requirements must be met in order to provide water for some
industries including beverage production, dairy and food processing, paper manufacturing, and textiles.
In domestic water, color is aesthetically undesirable and may dull clothes or stain fixtures. The scales
may also absorb or contain regulated contaminants.
The risk of colored water problems will cause many systems to be more careful when
implementing corrective actions such as changing the disinfectant and/or dose. Some research exists that
provides specific information on the number of systems potentially affected in certain areas. For
example, iron is a common ground water problem in at least 20 States (USGS, 1990-1996).
2.5.2.2 Potential Sources of Ground Water Quality Problems
There are several potential sources of water quality problems associated with implementing
disinfection of certain ground waters. The copper, iron, and manganese in ground water supplies result in
customer complaints, particularly in conjunction with chlorination. Manganese can be far more
problematic than iron and produces substantial manganese oxide deposits in distribution mains resulting
in occasional customer complaints regarding laundry staining. In the case of ferrous iron in corrosion
scales oxidized by chlorination, colored water can appear due to the more oxidized state of iron.
Corrosion scales exist at the surface of the pipe which consist of oxidized pipe metals and other minerals,
such as calcite, which form from constituents in the water. In some instances, more complex interactions
can occur. In one case, chlorination released high levels of copper particulates and sorbed mostly
insoluble arsenic onto the copper particulates causing arsenic levels to approach 5 mg/L (Reiber et al,
1997).
2.5.2.3 Potential Impacts On Water Quality
Disinfection of ground water can affect drinking water quality, resulting in an increase in
customer complaints due to nuisance color problems (as opposed to potential health risks). As mentioned
above, a major cause of colored water is the presence of precipitates (particulates) that form due to the
oxidation of metals by a disinfectant. This could occur through a reaction of the disinfectant with
dissolved metals in the water supply or though the disruption of corrosion scales in the distribution
system. Oxidizing these scales with chlorine can release large amounts of metals into the water until the
system reaches chemical stability (i.e., the system has re-equilibrated). This re-equilibration could take
anywhere between a few weeks to several months and could result in violations of SDWA regulations
(e.g. the Lead and Copper Rule). SDWA compliance issues such as chemical reactions that release
regulated contaminants at levels exceeding their MCLs need to be addressed as well. The impact of these
chemicals may not be known because systems do not typically monitor for such contaminants in the
distribution system with the exception of lead and copper. Another key issue related to SDWA
compliance is the impact of reduced disinfection and increased microbial risk due to oxidizing the metals
with chlorine, (i.e., high chlorine demand). Decreased levels of disinfection effectiveness result if metals
in the water or in corrosion scales exert a significant disinfectant demand. The result of decreased
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disinfection can cause a potential violation of the TCR due to bacterial growth and the consequent release
of viable coliforms from biofilms.
2.5.2.4 Mitigation of Ground Water Disinfection Impacts
Increased knowledge of a distribution system can help operators prevent and/or mitigate the
adverse impacts of ground water disinfection. A discussion of several of these knowledge areas is
presented below.
History of Ground Water Quality: An awareness of the ground water quality will assist
systems in understanding the possible range of issues they could face when initiating disinfection. Trace
metals present at concentrations well below an MCL can accumulate in scales and result in concentrations
exceeding the MCL if the scales are released into the distribution system. Therefore, a historical analysis
of the ground water quality can identify potential problems for the system before they arise. Waters high
in manganese concentrations, for example, will be strong candidates for colored water. This is because
manganese in ground water will form a colloidal precipitate when oxidized to the most stable (Mn4+)
oxidation state. Manganese coloration persists because the oxidation is relatively slow in water with a pH
below nine, which is typical in most ground water supplies (Sawyer and McCarty, 1967).
Characterization of Distribution System Materials: The type of distribution system materials
used determines the potential for colored water problems that may occur when implementing disinfection.
Water distribution systems consist of a variety of metal surfaces including steel, cast and ductile iron,
zinc, copper, lead, and a number of specialty alloys. Systems use many of these metals because of their
overall corrosion resistance. Nonetheless, all metal surfaces form a corrosion scale unique to the metal
type. Non-metallic distribution pipe materials include concrete and PVC piping.
The metals distribution in different scales are indicative of the respective pipe material. Cast iron
specimens, as expected, are high in iron. Typically galvanized iron pipe scale is high in iron and also
contains zinc. Corrosion scales consist largely of the oxidized metal, but will generally contain calcite
and other minerals. On some metal surfaces scales may be quite thin; in the case of copper, scales are
often less than 0.2 mm. On cast iron surfaces the scales are large, frequently exceeding a depth of 1
centimeter (cm). In even a relatively small distribution system, the existing corrosion scales will contain
several tons of metal oxides, while in large systems the corrosion scales can represent a massive reservoir
of metals measured in kilotons (Reiber, et. al., 1997).
Assessment of Impacts: Systems can directly monitor impacts of disinfection by measuring
corrosion scales and their stabilities. To measure corrosion scales, systems can obtain a variety of pipe
samples from different portions of the distribution system to analyze the suspect constituent and metals
contents. These include a sampling of copper tubing from galvanized iron service lines that provide water
to many of the homes and sections of galvanized iron pipe from the distribution system. Samples should
represent areas that have been in service over long periods in order to provide the appropriate data (i.e.,
corrosion scales that adequately represent the corrosion history of the system). Scales may be analyzed
by removing the scale down to the pipe wall, drying and powdering it, and then dissolving the powder in
nitric acid. This is followed by an inductively coupled plasma (ICP) analysis to determine the metal
constituents. The results are normalized by presenting the individual metals as the respective metal mass
per unit of total metal in the scale in milligrams per gram (mg/g).
Corrosion scale stability can be measured based on redox potential. Redox potential is the
measure of the relative oxidative conditions in a particular environment. A variety of factors affect the
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redox potential including dissolved minerals, gases, and the electrochemical state of the surfaces in
contact with the water. In a water distribution system temperature, pH, dissolved oxygen, microbial
activity, and the presence of disinfectants such as chlorine typically influence the redox potential the
most. This is important since many of the compounds in natural waters may exist in a variety of different
oxidation states. By convention, an oxidizing environment has a high redox potential, while a reducing
environment has a low redox potential. Clearly, a water distribution system with high dissolved oxygen
and substantial chlorine residual has a high redox potential. The more oxidized forms of minerals or
metal surfaces in contact with this water will tend to predominate in favor over reduced forms.
Prior to chlorination, most systems have relatively low redox potentials. Dissolved oxygen at the
wellheads is typically low and measured dissolved oxygen in the distribution system will generally be
very low (<1.0 mg/L). The historical absence of chlorine and low dissolved oxygen levels will probably
allow for reducing micro-environments to develop at the pipe walls and in the corrosion scales where
stagnation conditions predominate. This would suggest the existence of semi-reduced (i.e., not at their
highest oxidative state) forms. Chlorination will change the redox potential of the system, causing a
re-equilibration of the corrosion scales on residential copper plumbing surfaces. Disinfection converts the
more voluminous reduced-based scales to oxidized-based scales resulting in the loss of the bulk of metal
oxides stored in the scale. When conversion is complete, the resulting corrosion scale adheres and
protects the underlying metal. The length of time for conversion is generally unknown, but would likely
require up to months of continuous chlorine exposure (Reiber, et. al., 1997).
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3. Costs for Treatment Technologies
3.1 Introduction
To provide input to the Ground Water Rule (GWR) Economic Analysis (EA), the United States
Environmental Protection Agency (EPA) developed unit cost estimates for each of the ground water
disinfection technologies expected to be employed for meeting rule requirements. This chapter describes
the derivation of capital and operations and maintenance (O&M) unit costs for six treatment technologies.
Historically, the outputs of three EPA Cost Models [i.e., the Very Small Systems Model (VSS), the Water
Cost Model (Water), and the Water Wastewater Model (WAV)] have been used to estimate most unit
technology costs. In this document, however, a modified approach is used. The following approaches
were adopted to develop the cost estimates for GWR technologies:
• Cost Model Approach—modified outputs from the EPA Cost Models are used as stand-alone
estimates
Cost Build-Up Approach—manufacturer and/or vendor estimates along with engineered costs
are used in conjunction with cost model parameters for certain capital cost components
Exhibit 3.1 summarizes the technologies that were costed in this document and the specific
methodology adopted for each.
Exhibit 3.1 Technologies Costed and Methodology Adopted
Technology
Gas Chlorination
Hypochlorination
Temporary Hypochlorination
Chlorine Dioxide
Anodic Oxidation
Ozonation
Nanofiltration (NF)
Costing Methodology Used
Cost Model Approach
Cost Model Approach
Cost Build-Up Approach
Combination of Cost Build-Up and
Cost Model Approaches
Cost Model Approach
Cost Build-Up Approach
Cost Build-Up Approach
For each of the treatment technologies listed in Exhibit 3.1, EPA estimated costs based on 19
flow categories. These 19 flow categories correspond to different system sizes. Exhibit 3.2 presents
these flow categories.
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Exhibit 3.2 Flow Categories Used for Cost Estimates
Design Flow (mgd)
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1.0
1.2
2.0
3.5
7.0
17
22
76
210
430
520
Average Flow (mgd)
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.3
0.41
0.77
1.4
3.0
7.8
11
38
120
270
350
The remaining sections in this chapter provide more detail on the costing process.
• Section 3.2 provides descriptions of the three cost models.
• Section 3.3 provides detail on the two GWR unit technology cost estimation methodologies
(i.e., the Cost Model and Cost Build-Up approaches).
Section 3.4 describes the assumptions used for estimating certain indirect or "additional"
capital cost items.
• Section 3.5 presents example calculations for all three cost models that illustrate how the
"raw" model outputs were modified (based on methodologies discussed in section 3.3) to
produce the final capital cost estimates.
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Section 3.6 presents costs for storage tanks including finished water pumping.
Section 3.7 presents the derivation of capital and O&M costs for each of the six GWR
technologies.
3.2 Description and Application of the Cost Models
EPA developed the cost equations for the WAV and Water Models using data from
manufacturers, actual plant construction data, and other published data ((Culp/Wesner/ Gulp 1984);
Culp/Wesner/Culp 1979). The Very Small Systems Best Available Technology Cost Document (Malcolm
Pirnie Inc., 1993) provides the basis for the equations used in the VSS Model.
To develop technology costs, all three Cost Models require user-specified inputs such as design
and average flows, chemical dose, and cost indices. These three Cost Models, hereafter referred to as the
"models", were used to estimate technology costs for particular system sizes.
The WAV Model is used for design flows greater than 1.0 million gallons per day (mgd)
The Water Model is used for design flows from 0.1 mgd to 1.0 mgd1
The VSS Model is used for design flows less than 0.1 mgd
The following sections describe each of the three models in more detail.
3.2.1 Water and Wastewater (WAV) Model
EPA used the latest version (i.e., version 3.0 in the "Windows" operating system) of the W/W
Costs and Design Criteria Guidelines software (CWC, 2000) to develop costs for drinking water systems
serving more than 3,300 people (i.e., systems with design flows greater than 1 mgd). Information
contained in a four volume report provides the documentation for this software (CulpAVesner/Culp 1979).
EPA obtained unit cost estimates by selecting the appropriate unit processes within the model.
W/WModel Structure
The WAV Model generates capital and annual O&M costs based on treatment technology, design
and average daily flows, and chemical dose. The program calculates these costs based on capital and unit
cost factors assigned by the user.
Capital costs include the following:
Construction (e.g., equipment, labor, pipes/valves, electrical, housing)
• Sitework
1 Normally, the ideal applicability range for the Water Model is 0.27-1.0 mgd. Ideally, linear interpolation
would be appropriate for the "transition zone" between the Water and VSS Models (i.e., 0.1 to 0.27 mgd). However,
the Water Model has been found to be applicable for design flows as low as 0.1 mgd (USEPA, 1979). Thus, in this
document, the Water Model is used for the "transition zone" of 0.1 to 0.27 mgd.
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Subsurface
Standby power
General contractor overhead and profit
• Engineering
Land (assumed to be zero, unless noted)
Legal, fiscal and administrative services
Interest during construction
O&M costs include the following:
Energy (e.g, electricity, fuel and natural gas)
Maintenance material (e.g, periodic replacement throughout useful life)
Labor
Chemicals
W/WModel Inputs
The WAV Model is capable of estimating costs for the price level of any given year by entering
appropriate cost indices and adjustment factors. The WAV Model requires standard indices and unit costs
from the Bureau of Labor Statistics (BLS) and the Engineering News Record (ENR) to calculate and
update costs. Exhibits 3.3-3.5 present capital and unit cost factors, national average building cost
indices, and chemical costs used to generate capital and annual O&M costs. These represent year 2003
(average) numbers. The BLS indices listed in Exhibit 3.3 are based in 1967 dollars. The BLS
Commodity Indices in Exhibit 3.3 reflect specific producer price index (PPI) listings. Due to the 1986
review of the industrial price methodology, these indices were re-based in 1982 dollars. However, the
WAV Model requires BLS indices based on 1967 dollars and all BLS cost factors used in the model are
recalculated to represent the 1967 base level.
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Exhibit 3.3 Applicable Unit Costs and BLS Cost Indices (2003 dollars/indices)
Cost Index/Parameter
Engineering Percent
Sitework, Interface Piping Percent
Standby Power Percent35
Subsurface Sitework Percent1 34
Land Cost ($/Acre)6
Electricity ($/kWh)7
Labor ($/hr)7
Diesel Fuel ($/gal)7
Natural Gas ($/ft2)7
Building Energy (kWh/ft2/yr)9
Building/Housing ($/ft2)10
BLS Commodity Code No. 300027 (PPI for
Finished Goods)
BLS Commodity Code No. 1 1427
BLS Commodity Code No. 13227
BLS Commodity Code No. 101727
BLS Commodity Code No. 1 14927
BLS Commodity Code No. 11727
Index Value
Varies (see Exhibit 3.7)
Varies (see Exhibit 3.7)
5%
10%
0.0
0.076
27.01
1.78
0.0092
102.6
51.1
414.2
482.6
502.5
397.3
533.8
371.7
Sources:
1 Subsurface Sitework is a construction cost contingency factor developed for excavation work.
2 Commodity codes reflect specific PPI listings and a 1967 base year: No. 114: PPI for general
purpose machinery and equipment; No. 132: PPI for nonmetallic mineral products (e.g., concrete and
related products); No. 1017: PPI for metals and metal products; No. 1149: PPI for miscellaneous
general purpose machinery and equipment; No. 117: PPI for electrical machinery and equipment.
3 Percentage of construction costs.
4USEPA, 1993a.
5USEPA, 1992b.
6 Assumes available land on-site for certain technologies. For others, land costs have been added
separately (see section 3.4).
7 Bureau of Labor Statistics (BLS, 2001). This labor rate only used for model calculations. For labor
rate for other factors see Ex 3.6.
8USEPA, 1984.
9 USEPA, 2003.
10 R.S. Means (2000) cost updated to 2003 dollars using the ENR BCI (see Exhibit 3.4).
The ENR indices (2003 price level) listed in Exhibit 3.4 measure how much it costs to purchase
goods and services compared to costs in the base year. The WAV Model required the following ENR
indices as inputs: skilled labor, building costs, and materials. Exhibit 3.5 presents the cost of chemicals
used in the WAV Model.
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Exhibit 3.4 ENR Cost Indices
Cost Index/Parameter
ENR Skilled Labor Index
ENR Building Costs Index
ENR Materials Index
2003 Index
Value
5,947.72
3,693.00
2,120.23
Source: vwwv.enr.com
Exhibit 3.5 Chemical Costs (2003 dollars)
Chemical
Chlorine gas, 1-ton cylinder and bulk
Chlorine gas, 150-lb cylinder
Hexametaphosphate
Sodium Chlorite
Sodium Hypochlorite, 12 % chlorine
Sulfuric Acid
Cost
$296.8 per ton
$636 per ton
$1,378 per ton
$344.5 per ton
$1,192.5 per ton
$106 per ton
Source: Based on vendor estimates (USEPA, 2005).
The capital cost estimates based on the model outputs were then modified in a manner discussed
in Sections 3.3 and 3.4 to obtain the final capital costs.
3.2.2 Water Model
The Water Model estimates water treatment costs for small to medium-sized drinking water
systems serving between 1,000 and 3,300 people (i.e., systems with design flows between 0.1 mgd and 1
mgd). The model covers 45 different unit treatment processes. The document titled Estimation of Small
System Water Treatment Costs (Culp/Wesner/ Gulp 1984) contains a printout of the source code for the
Water Model in FORTRAN. A spreadsheet version of the model is also available and was used for
generating the cost numbers in this document.
Water Model Structure
The Water Model generates capital and annual O&M costs based on treatment technology, design
and average daily flows, and chemical dose. The spreadsheet version of the model has a cost generating
subroutine and a separate data file for each applicable technology that holds the user defined inputs. The
program calculates these costs based on capital and unit cost factors assigned by the user. EPA selected
unit processes for each technology based on processes used in prior technology and cost documents and
engineering judgement. When the model did not include a particular unit process as an individual model
process, EPA combined several model processes essential in achieving the treatment objective of the
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analyzed technology. The list of capital and O&M cost items included in the Water Model are the same
for those used in the WAV Model (see Section 3.2.1).
Water Model Inputs
The inputs and processes required by the Water Model to estimate costs for a given time (i.e.,
price level) are the same as those used for the WAV Model (see Section 3.2.1 and Exhibits 3.3 - 3.5).
Process-related input coefficients (such as minimum and maximum chemical dosages, detention times,
etc.) differ from those used in the WAV Model and were obtained by EPA from the data file titled
CRV_DAT.xls listed in Estimation of Small System Water Treatment Costs (CulpAVesner/ Gulp 1984).
The capital cost estimates based on the model outputs were then modified in a manner discussed
in Sections 3.3 and 3.4 to obtain the final capital costs.
3.2.3 Very Small Systems (VSS) Model
The VSS Model is most applicable for very small systems serving fewer than 1,000 people (i.e,
systems with design flows less than 0.1 mgd). The Very Small Systems Best Available Technology Cost
Document (Malcolm Pirnie Inc., 1993) provides the basis for the equations used to estimate costs. This
document compiles input from members of the National Water Quality Association (NWQA), academia,
EPA , information collected from original equipment manufacturers (OEMs), the Water Model (USEPA,
1984), and very small system installations to establish design parameters used to size process equipment
and to calculate annual O&M costs.
VSS Model Structure
In order to develop capital and annual O&M costs for very small systems the source information
discussed above is used to develop technology-specific cost equations that are a function of systems'
flows and labor costs. The VSS Model uses these cost equations to estimate technology-specific total
capital costs.
VSS Model Inputs
To develop total capital costs, the VSS Model applies a cost factor to specific equipment costs.
Since the VSS Model uses equipment costs as a basis for total capital costs, a cost factor is used to obtain
building costs (e.g., engineering, installation, contractor overhead and profit, legal, fiscal and
administrative, sitework, electricity, and standby power). This differs from the WAV and Water Models,
which estimate costs for each of these components separately. The VSS document (Malcolm Pirnie Inc.,
1993) provides these building cost estimates (presented as percentage of total capital cost).
O&M costs were also developed using OEM information and include costs for chemicals, power,
labor, and replacement parts. The chemical costs used were identical to those used in the WAV and Water
Models (see Exhibit 3.5). Labor costs for very small systems vary depending on the amount of time
allotted for system personnel to inspect, operate, and maintain the facility. Therefore, the number of labor
hours is a variable (along with average daily flow) in the VSS O&M cost equations.
The VSS Model also takes into account treatment plant site development (building, road, fencing,
and land acquisition), wellhead rehabilitation, and distribution system O&M costs. These costs are
estimated as a function of the size of process equipment and the need for the equipment to be installed in
a building (Malcolm Pirnie Inc., 1993).
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Adjustments to Model Outputs
EPA adjusted the capital and O&M cost outputs from the models to a year 2003 price level.
Based on the ENR Building Cost Index (BCI), a capital cost adjustment factor of was applied to the
capital costs. The BLS Consumer Price Index (CPI) was applied to the O&M costs. The BCI is more
applicable to projects involving construction; whereas, the CPI is more applicable to instances where
labor forms a substantial part of the total costs. Therefore, the BCI was used to adjust the capital costs,
and the CPI was used for adjusting the O&M costs.
The adjusted (to 2003 dollars) capital cost estimates were then modified in a manner discussed in
Sections 3.3 and Section 3.4 to obtain final capital cost estimates.
3.3 General Costing Methodology
Following the re-authorization of the SDWA in 1996 EPA critically evaluated its tools for
estimating the costs and benefits of drinking water regulations. As part of this evaluation EPA solicited
input from national drinking water experts at the Denver Technology Workshop (sponsored by EPA in
November, 1997) to improve the quality of its compliance cost estimating process for various drinking
water treatment technologies. The Technology Design Panel (TOP) formed at the workshop for this
purpose recommended several modifications to existing cost models to improve the accuracy of EPA's
compliance cost estimates (USEPA, 1998).
In 2001, the National Drinking Water Advisory Council (NDWAC) convened the Arsenic Cost
Working Group to review the cost methodologies, assumptions, and information underlying the system-
size specific cost estimates presented in the Arsenic Technologies and Costs Document (December,
2000), as well as the aggregated national cost estimates for the Arsenic in Drinking Water Rule. As part
of the review, the NDWAC made several recommendations (National Drinking Water Advisory Council,
2001) that have since been incorporated into the cost approach applied for the Arsenic Rule. This
document incorporates both the TOP and NDWAC recommendations in the capital unit cost estimates for
the GWR, as appropriate.2
3.3.1 Estimates Using Cost Models Approach
Capital Costs
The capital cost output from the cost models consists of three elements:
• Process costs which include manufactured equipment, concrete, steel, electrical and
instrumentation, and pipes and valves.
Construction costs which include installation, sitework and excavation, subsurface
considerations, standby power, contingencies, and interest during construction.
Engineering costs which include general contractor overhead and profit, engineering fees,
and legal, fiscal, and administrative fees.
This approach updates the costing approach used in the 1999 proposed Cost and Technology Document
for the Ground Water Rule.
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The TDP recommended that total capital cost estimates be based on process costs, which can then
be multiplied by a specific cost factor to estimate total capital costs (i.e., extract the process cost from the
model output and multiply it by a factor to arrive at the total cost). The TDP believed that the process
cost component of the model outputs was the most reliable component and hence recommended the
methodology described. The NDWAC recommendations were similar; however, the factors
recommended by the two groups varied to some degree. This document primarily utilizes cost factors
recommended by NDWAC, slightly modified as follows:
A cost factor of 2.5 is used for systems less than 1.0 mgd
A cost factor of 2.0 is applied for systems greater than 1.0 mgd
The cost factor for systems greater than 1.0 mgd is different from the 1.8 value recommended by
NDWAC in order to account for installation.
For Nanofiltration, the following multiplier was used:
• Nanofiltration: 1.67
The basis for the revised multipliers is that the 2.5 multiplier is applicable to relatively
inexpensive technologies that require proportionally greater engineering and design effort than pre-
assembled modular systems such as membrane units. Nanofiltration also requires relatively more
expensive equipment, but is usually easier to install.
Some costs are not included in the model outputs. Other "additional" indirect capital costs such
as land, permitting, piloting, operator training, housing, and public education are included (where
indicated) in the estimates presented in this chapter, but are added to the direct capital cost after
application of the NDWAC-recommended adjustment factors to the total process costs. Section 3.4
describes these "additional" indirect costs. Section 3.5 discusses this costing methodology in more detail
through example calculations.
Annual O&M costs
O&M costs are obtained directly from the model outputs. Unlike the capital costs, no cost factors
are applied to the O&M cost outputs from the models. Labor costs vary by size category and are shown
in Exhibit 3.6. Electricity costs are assumed to be $0.076/kWh for all flows.
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Exhibit 3.6 Labor Rates for PWS Operators
Size of PWS
25-100
101 -500
500 - 3,300
3,301 -10,000
10,001 -100,000
> 100,000
Labor Rate (2003 $)
$
$
$
$
$
$
21.44
23.09
24.74
25.34
26.05
31.26
Source: Labor Costs for National Drinking Water Rules (USEPA 2003)
Summary of Cost Model Approach
Total Capital Cost:
Total Capital Cost = Direct Cost + Indirect Cost
where,
Direct Cost = The "process" cost item from model output *
the appropriate NDWAC-recommended cost factor
multiplier.
Indirect Cost = Additional cost items such as land,
permitting, piloting, operator training, housing, and public
education (see Section 3.4 for details), to which the
NDWAC-recommended cost factor multiplier is NOT
applied.
Annual O&M Cost:
Obtained directly from model outputs.
No cost factors applied.
Labor rate: varies by system size
Electricity unit cost: $0.076/kWh
3.3.2 Estimates Using a Cost Build-Up Approach
Capital Costs
To estimate capital costs for those technologies where cost model estimates were found to be
inaccurate based on "best professional judgement" (BPJ), a cost build-up approach was used. Process
components were identified and sized using engineering design principles and were costed using
estimates from manufacturers, vendors, and field engineers. These process costs were then multiplied by
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the capital cost factors as discussed above. The capital cost factors account for the engineering and
construction costs. The breakouts showing the allocation of the factors are shown in Exhibit 3.7.
Exhibit 3.7 Additions to Preliminary Process Cost Estimates
Component
Site work
Contractor Overhead &
Profit (O&P)
Contingencies
Engineering and design
Mobilization and
bonding
Legal and administrative
Interest during
construction
Installation
For
Nanofiltration
Systems
10%
10%
15%
10%
5%
0%
7%
10%
For Design
Flows < 1
mgd
25%
20%
30%
25%
5%
15%
10%
20%
For Design Flows
> 1 mgd
15%
10%
20%
15%
3%
10%
7%
20%
Percentage refers to percentage of the "preliminary" process cost estimate.
Source: Best Professional Judgement.
Total capital costs are derived from the total process costs by applying the NDWAC-
recommended cost factors (the same as those discussed under Capital Costs in section 3.3.1). Indirect
capital costs such as land, permitting, piloting, operator training, housing, and public education are
included (where indicated) in the estimates presented in this chapter. However, they are added to the
direct capital cost after the application of the NDWAC-recommended cost factors to the total process
cost. Section 3.4 describes these "additional" indirect costs, and Section 3.5 discusses this costing
methodology in more detail through example calculations.
Annual O&M Costs
Annual O&M costs are mainly comprised of chemical, material, labor, and electricity/energy
costs. Chemical costs are computed using vendors' quotes after estimating the annual chemical
requirements based on the chemical doses applied and average flow rates. Material, labor, and electricity
costs are derived either from best professional judgement or directly from cost model input parameters.
Where Model parameters are used, no cost factors are applied to those outputs (unlike the capital costs),
except to update values to a 2003 price level. Labor costs are from Exhibit 3.6 and electricity costs are
assumed to be $0.076/kWh.
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Summary of Cost Build-Up Methodology
Total Capital Cost:
Total Capital Cost = Direct Cost + Indirect Cost
where,
Direct Cost = (Process cost estimated from engineering principles and
manufacturers' quotes + the cost of the other components listed in
Exhibit 3.6) and/or (Process costs from the cost models) * the
appropriate NDWAC-recommended cost factor multiplier.
Indirect Cost = "Additional" cost items such as land, permitting,
piloting, operator training, housing, and public education (see Section
3.4 for details), to which the NDWAC-recommended cost factor
multiplier is NOT applied.
Annual O&M Cost:
Chemical cost: vendor estimates for unit costs in conjunction with
annual chemical usage based on the chemical dose applied and
average flow.
Materials, labor, and electricity: directly from model parameters or
based on best professional judgement/vendor estimate. If cost models
are used, no cost factors are applied.
Labor rate: varies by system size.
Electricity unit cost: $0.076/kWh.
3.3.3 Waste Disposal Costs
The GWR technologies identified and costed in this chapter generate little or no waste, with the
exception of NF, which produces sufficient volumes of waste to warrant consideration. Therefore,
wastewater treatment and disposal costs are included for this technology.
The WAV, Water, and VSS Models do not account for expenses incurred for waste disposal
facilities; therefore, the NF waste disposal costs are based on engineering judgement and are added as a
line item in the cost build-up structure after the application of NDWAC-recommended cost factors.
3.4
'Additional" Cost Items
Based on the recommendations of the TOP and NDWAC cost working groups, capital cost
estimates presented in this chapter include additional costs associated with permitting, pilot testing, land,
housing, operator training, and public education. This section describes the approach used to incorporate
each of these items into unit cost estimates.
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3.4.1 Permitting
The cost to assemble a permit application can be highly variable and usually varies by
technology. Some permits can require extensive studies (e.g., Environmental Assessments or
Environmental Impact Statements). Technologies requiring extensive environmental impact studies or
permit applications for handling treatment residuals (e.g., National Pollutant Discharge Elimination
System (NPDES) permits) can also be expensive and require legal assistance that leads to increased costs.
Costs are also affected by whether a system has the expertise in-house to develop and submit the
necessary permit applications. Otherwise, additional consulting services may be required. The NDWAC
working group recommended that permitting costs for GWR technologies requiring a permit be calculated
as 3 percent of the total process cost, with a minimum of $2,500 and a maximum of $500,000. For
chlorination technologies (i.e. gas chlorination and hypochlorination), which require minor process
modifications, permitting costs are included as a part of the engineering fees (included in the capital cost
factor).
3.4.2 Piloting
The NDWAC working group recommended that the costs of pilot tests be included for all
technologies. Piloting costs can be widely variable depending on treatment options and the extent to
which pilot studies are necessary. For example, many pilot studies evaluate multiple technologies that
can lead to increased costs. For the purposes of this document, it was assumed piloting would not be
necessary for those technologies requiring relatively minor process modifications (i.e., gas chlorination,
and hypochlorination). All other technologies include the costs associated with bench- or pilot-scale
tests. For systems less than 1 mgd, bench-scale tests are assumed. Pilot-scale tests are assumed for all
systems larger than 1 mgd. Exhibit 3.8 summarizes the pilot testing cost assumptions used in this
document.
Exhibit 3.8 Summary of Piloting Cost Assumptions
Technology
All chlorination technologies
Chlorine Dioxide
Anodic Oxidation
Ozo nation
Nanofiltration
Design Flow (mgd)
<0.1
$0
$5,000
$5,000
$5,000
$1,000
0.1 to 1
$0
$10,000
$10,000
$10,000
$10,000
>1
$0
$50,000
$50,000
$65,000
$60,000
Source: NDWAC recommendation refined based on best professional judgement.
3.4.3 Land
The majority of the technologies discussed in this document will likely fit in existing plant
footprints and additional land purchases will not be required. However, several processes (i.e., ozonation,
and NF) are not likely to fit in existing footprints and may require systems to purchase additional land.
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The amount of land required for the installation or upgrade of a treatment process can vary significantly,
and land costs can also vary significantly from region to region depending upon availability.
The NDWAC working group recommended that land costs be included at 2 to 5 percent of total
capital costs. However, this recommendation is based on new treatment plant construction which would
require an entirely new parcel of land. Land cost were lowered from the NDWAC recommendations
because EPA believes, based on best professional judgment, that a majority of ground water systems will
have some land available for installation of new technologies. Most systems will have land to
accommodate other infrastructure associated with the system (e.g., pumping stations, designated wellhead
protection areas, etc.) that may also accommodate new treatment. As a result, land costs are included at
percentages ranging from 0.5 to 2 percent depending on the technology. The reason the percentage varies
from technology to technology is the relative capital cost of each technology. Percentages were also
adjusted based on the estimated building footprint of the technology. That is, if the land cost per acre was
considered unreasonable (i.e., significantly higher than $500,000 per acre3), the percentage was adjusted
accordingly. Exhibit 3.9 summarizes the land cost assumptions used in this document.
Exhibit 3.9 Summary of Land Cost Assumptions as a Percent of Total Capital
Cost
Technology
Ozonation
Nanofiltration
System Size (mgd)
<1
2%
2%
1 -10
2%
1%
>10
2%
0.5%
Source: NDWAC recommendations refined based on best professional judgement.
3.4.4 Housing, Operator Training, and Public Education
The assumptions behind costing these items (wherever appropriate) are technology-specific and
are discussed under the costing for individual technologies (see Section 3.7).
3.5 Example Calculations for Costing Methodologies
This section provides example calculations for the technologies using the approaches described
earlier in this chapter. Examples are provided for the Cost Model Approach using each of the three cost
models followed by an example using the Cost Build-Up Approach. These numbers and calculations are
presented for demonstration purposes only. Descriptions of the calculations used for each of the GWR
technologies are provided in Section 3.7.
3Based on best professional judgement, the upper end of land costs in the US is in the vicinity of $500,000
per acre. Anything beyond that value is considered high. This is consistent with the Technology and Cost document
for the Stage 2 DBPR/LT2ESWTR. (USEPA, 2003).
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3.5.1 Example Calculations for the Cost Model Approach using W/W Model
The following sample calculation describes how costs were derived using the WAV Model. Cost
estimates using the Cost Model Approach entail the application of NDWAC and TDP-recommended cost
factors. The steps outlined below incorporate those recommendations.
Example Technology - Chlorine Gas (applied chlorine dose of 4 mg/L using 150 Ib. Cylinders) for a
plant with a design flow capacity of 2 mgd
1. The total "raw" capital cost model output for installing a chlorine gas unit to a treatment process
with a design flow capacity of 2 mgd and a chlorine dose of 4 mg/L is $20,928
2. Total process cost (excluding housing) = cost of equipment (from above) + labor + pipes &
valves + electrical & instrumentation + concrete + steel
(all from the raw model output)
= $27,827
3. The modified capital cost can then be calculated using the total cost factor described in Section
3.3 (i.e., 2.0) = result from step 2 x total cost factor
= $27,827 x 2.0
= $55,654
4. Housing cost (from raw model output) = $10,546
5. Permitting costs = included in the cost factor for chlorine based processes (see Section 3.4.1)
6. Piloting costs = $0 for chlorine (see Section 3.4.2).
7. Land, operator training, and public education costs are assumed to be zero (see Section 3.4)
8. Total capital costs (modified) = (step 3) + (step 4) + (step 5) + (step 6) + (step 7)
= $55,654 + $10,546 + $0 + $0 + $0
= $66,200 (2003 dollars)
9. Annual O&M cost based on direct model output = $18,431 (2003 dollars)
3.5.2 Example Calculations for the Cost Model Approach using Water Model
Example Technology - Gas Chlorination (applied dose of 4 mg/L) for a plant with a design flow capacity
of 0.36 mgd
1. The total "raw" capital cost model output for installing a gas chlorination unit (including housing)
to a treatment process with a design flow capacity of 0.36 mgd and a dose of 1 mg/L is $30,154
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2. The model calculated the fraction of process cost to be 39.62 percent (from the "raw" output).
This number was derived from a sample model run for the applicable technology presented in the
Water Model documentation. The "raw" electronic model output does not provide a very detailed
breakout of the total capital cost. However, the breakout of process, construction, and
engineering costs are provided in the model documentation for a given sample run. The
assumption is that the breakout percentages for process, construction, and engineering costs are
independent of the process and operating parameters and can therefore be applied to any run for
that particular technology.
3. Total process cost = "raw" model output from step 1 * process cost factor derived in step 2.
= $30,154 x 39.62% = $11,947.
4. The modified capital cost can then be calculated using the total cost factor in Section 3.3 (i.e.,
2.5) = result from step 3 x total cost factor
= $11,947x2.5
= $29,868
5. Housing costs are not added separately as in the case of the WAV Model because the Water
Model assumes that additional housing for the facility being costed is not required.
6. Permitting costs for gas chlorination are assumed to be incorporated by the capital cost factor, and
are not added separately (see Section 3.4.1)
7. Land, piloting, operator training, and public education costs are assumed to be zero (see Section
3.4).
8. Hence, total capital costs (modified) = (step 4) + (step 5) + (step 6) + (step 7)
= $29,868 + $0 + $0 +$0
= $29,868 (2003 dollars)
9. Annual O&M cost based on direct model output = $6,554 (2003 dollars)
3.5.3 Example Calculations for the Cost Model Approach (VSS Model)
Example Technology - Hypochlorination (applied dose of 4 mg/L)for a plant with a design flow capacity
of 0.091 mgd
1. The capital cost equation for disinfection using hypochlorite is CAP = 4.7 (where CAP = capital
cost in 1,000s of dollars at a 1993 price level).
2. To escalate to 2003 dollars, multiply the equation generated capital cost by the ratio of the ENR
average Building Cost index for 2003 to the average 1993 index value. $ 4,700 x 1.23 (see
Section 3.2.3) = $5,793.
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3. Based on the model results, the fraction of process cost is 61.93 percent. This number was
derived from a sample model run for the applicable technology, presented in the VSS Model
documentation. The "raw" electronic model output does not provide a very detailed breakout of
the total capital cost. However, the breakout of process, construction, and engineering costs are
provided in the model documentation for a given "sample" run. The assumption here is that the
breakout percentages for process, construction, and engineering costs are independent of the
process and operating parameters and can therefore be applied to any run for that particular
technology. Total process cost is $5,793 x 61.93% = $3,588.
4. The modified capital cost can then be calculated using the total cost factor presented in section
3.3 (i.e., 2.5) = result from step 3 x total cost factor
= $3,588 x2.5
= $8,970
5. Permitting costs for chlorination technologies are assumed to be incorporated by the capital cost
factor and are thus not added separately.
6. Land, piloting, operator training, and public education costs are assumed to be zero (see Section
3.4). Housing costs are estimated within the VSS Model (see Section 3.2.3).
7. Hence, total modified capital costs = (step 4) + (step 5) + (step 6)
= $8,970 + $0 + $0
= $8,970 (2003 dollars)
8. Annual O&M costs are not based on the VSS Model. Instead, they were developed using BPJ.
Hence they are not discussed here.
3.5.4 Example Calculations for the Cost Build-Up Approach
Example Technology - ozonationfor a plant with a design flow capacity ofO. 091 mgd
1. Develop process cost using manufacturers' estimates. In this case:
Process costs = cost of ozone generator + cost of pipes and valves + cost of
instrumentation and controls + cost of pumping equipment + cost of
ozone contactor + cost of off-gas destruction + cost of ozone quench
= $122,149 (vendor estimate)
2. Compute Direct capital cost.
Direct capital cost = (Process cost from step 1) x (the appropriate capital cost factor).
= $122,149 x 2.5 (see Section 3.3.1)
= $305,371
3. Compute Indirect capital cost.
Indirect capital cost = "Additional" cost items such as land, permitting, piloting/treatability
testing, operator training, housing, public education, etc. (see Section 3.4 for details), to which
cost factors are NOT applied.
Indirect capital cost = operator training cost + piloting + housing + land + permitting
= $924 + $5,000 + $5,866 + $2,443 + $3,664
= $17,897
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4. Compute Total Capital cost.
Total Capital cost = Direct capital cost + Indirect capital cost
= $305,371+ $17897
= $323,268
5. Estimate Annual O&M costs.
Annual O&M costs = annual cost for chemicals + parts + monitoring + labor + electricity; where:
• Chemicals costs = annual chemical usage based on the applied dose for a given average flow
x unit cost of chemical based on vendor estimates = $36
Material costs are based on vendor estimates = $946
Labor costs = estimated labor hours based on discussions with vendors or best professional
judgement x unit labor cost of $24.74/hr
= $43,832
Electricity costs = estimated total kWh based on discussions with vendors or simple
computations based on equipment ratings x unit electricity cost of $0.076/kWh
= $306
•• Process monitoring = $10,400
Annual O&M Costs = $55,520
(i.e., 17 percent of total capital cost)
3.6 Costs for Storage tanks Including Finished Water Pumping
3.6.1 Introduction
In addition to the capital and O&M costs for installation of the disinfection technologies, ground
water systems may also require storage tanks to provide sufficient contact time for disinfection. Systems
which have disinfection but do not achieve the required inactivation may also be able to increase their
inactivation by adding additional storage. This section provides the capital costs and cost equations for
the storage tanks associated with chlorination (gas chlorination, hypochlorination, and anodic oxidation),
and chlorine dioxide systems. Costs are for storage tanks that provide the contact time needed for 4-log
inactivation of viruses at 15°C and a pH between 6 and 9. The document titled The Guidance Manual for
Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface
Water Sources (AWWA, 1991b) provided the appropriate CT values for the disinfectants.
3.6.2 Storage tanks
EPA considered "at-grade" baffled steel tanks for required capacities less than 100,000 gallons.
For capacities greater than or equal to 100,000 gallons, "at-grade" baffled prestressed concrete tanks were
assumed. The unit costs for these tanks were obtained from R.S. Means (2001). EPA assumed the use of
baffled storage tanks to provide an actual contact time of 1.5 times the theoretical detention time in
accordance with the Guidance Manual for Compliance with the Filtration and Disinfection Requirements
for Public Water Systems Using Surface Water Resources (AWWA, 1991b). Based on best professional
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judgement, an additional cost adjustment factor of 15 percent was applied to the R.S. Means costs to
account for engineering, piping, fittings and other appurtenances. O&M costs are assumed to be part of a
PWS's overall preventive maintenance plan and are expected to be negligible. These include yearly
inspection by the operator and the painting of both the interior and exterior once every 10 years (USEPA ,
1993b).
3.6.3 Finished Water Pumping
Ground water systems that require a storage tank for additional contact time for disinfection also
require a high lift pump after the tank. The system replaces the existing pumps with pumps that pump
water from the well to the distribution system and then restages the existing pumps with in-plant pumping
for a lower head.
The WAV Model estimates the costs of finished water pumping and assumes the design flow for
these costs. The model applies to design flow rates ranging from 1 to 200 mgd. It linearly extrapolates
the cost curve for design flows less than 1 mgd, all the way down to zero flow (where cost is zero).
The finished water requirements may be greater than the average daily flow depending on the layout of
the distribution system and the plant storage capacities. Pumps are vertical turbines driven by 1,800
revolutions per minute (rpm), constant speed, drip proof, high thrust vertical motors. EPA assumed a
total dynamic head (TDH) of 300 ft for these pumps. Costs also include a standby pump with a capacity
equal to the largest pump provided, all electrical equipment and instrumentation, and valving and
manifolding within the pumping station. The capital cost does not include wet well or housing. This
model assumes a 90 percent motor efficiency and an 85 percent pump efficiency.
3.6.4 Cost Estimates
Exhibits 3.9 and 3.10 present the estimated costs for modifying ground water systems to achieve
the required 4-log inactivation of viruses. These exhibits present two different disinfection technologies.
Exhibit 3.9 present costs for adding a storage tank for chlorine gas and hypochlorination, the most
commonly used disinfection technologies. They are also applicable to systems using anodic oxidation.
Exhibit 3.10 presents the costs for operating an "at-grade" storage tank for chlorine dioxide contact.
As indicated in Exhibit 3.9, estimates for storage tank costs for chlorinating systems are not
available for design flows greater than 76 mgd. Similarly, as indicated in Exhibit 3.10, estimates for
storage tank costs for chlorine dioxide are not available for design flows greater than 22 mgd. This is
because R.S. Means provides cost estimates for storage tanks up to a capacity of 500,000 gallons.
The capital costs for each system size are presented in Exhibits 3.10 and 3.11. Exhibits A. 1 and
A.2 of Appendix A present the linear regression cost coefficients A and B (described below) for all
pertinent flow ranges. Costs were assumed to vary linearly with flow between any two adjacent flow
points.
Cost ($) = A + [B x Flow (in kgpd)], where:
A = Y-axis intercept of the linear regression for that flow range
B = Slope of the linear regression for that flow range
The data shown in Exhibits A.I and A.2 of Appendix A serve as inputs to the GWR EA Cost
Model.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-19
-------
Exhibit 3.10 Estimated Costs for At-Grade Tanks for Chlorine Contact (Residual
of 2 mg/L) - Costs in 2003$
Design
Flow
(mgd)
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
210
430
520
CT (mg-
min/L)
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
C (mg/L)
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
T (min)
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Tank
Volume
(gal)
6.5
20.4
34.3
84.3
166.7
250.0
333.3
629.6
925.9
1,111.1
1,851.9
3,240.7
6,481.5
15,740.7
20,370.4
70,370.4
194,444.4
398,148
481 ,481
Clean/veil
and
Apurtenance
Cost
A
$372.42
$402.16
$431 .90
$538.97
$715.43
$893.87
$1,072.32
$1,706.78
$2,341.24
$2,737.78
$4,323.94
$7,297.99
$12,108.24
$20,350.74
$24,999.99
$75,211.94
$128,755.21
N/A
N/A
Finished Water
Pumping
Costs
B
$415.39
$1 ,305.05
$2,194.72
$5,396.91
$10,674.98
$16,012.99
$21,351.00
$40,329.54
$59,308.09
$90,947.62
$217,505.71
$326,957.60
$536,716.69
$1,039,131.05
$1,286,088.80
$3,488,387.75
$8,953,351 .98
Beyond Model
Range
Beyond Model
Range
At-grade
Clean/veil and
Pumping
Costs
C=A+ B
$787.81
$1,707.22
$2,626.63
$5,935.88
$11,390.41
$16,906.86
$22,423.31
$42,036.32
$61 ,649.33
$93,685.40
$221,829.65
$334,255.58
$548,824.93
$1,059,481.79
$1,311,088.79
$3,563,599.70
$9,082,107.19
N/A
N/A
Basis for Clean/veil Cost
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Pre-stressed concrete tank
(R.S. Means, 2001)
Pre-stressed concrete tank
(R.S. Means, 2001)
Pre-stressed concrete tank
(R.S. Means, 2001)
1. N/A = Not Applicable
2. O&M costs are assumed to be part of a PWS's overall preventive maintenance plan and are expected to be
negligible.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-20
-------
Exhibit 3.11 Estimated Costs for At-Grade Tanks for Chlorine Dioxide Contact
(Residual of 0.625 mg/L) - Costs in 2003$
Design
Flow
(mgd)
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
210
430
520
CT (mg-
min/L)
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
16.7
C (mg/L)
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
0.625
T (min)
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
26.72
Tank Volume
(gai)
86.6
272.1
457.7
1,125.7
2,226.7
3,340.0
4,453.3
8,411.9
12,370.4
14,844.4
24,740.7
43,296.3
86,592.6
210,296.3
272,148.1
940,148.1
2,597,777.8
N/A
N/A
Clearwell
and
Apurtenance
Cost
A
$543.97
$941.30
$1,338.63
$2,769.03
$5,126.54
$7,510.53
$9,894.53
$13,467.43
$16,966.08
$19,450.64
$29,388.89
$48,023.10
$91,502.93
$134,469.20
$156,764.42
$397,552.38
$995,065.11
N/A
N/A
Finished Water
Pumping
Costs
B
$415.39
$1,305.05
$2,194.72
$5,396.91
$10,674.98
$16,012.99
$21,351.00
$40,329.54
$59,308.09
$90,947.62
$217,505.71
$326,957.60
$536,716.69
$1,039,131.05
$1,286,088.80
$3,488,387.75
$8,953,351.98
Beyond Model
Ranae
Beyond Model
Range
At-grade
Clearwell and
Pumping
Costs
C = A+ B
$959.35
$2,246.35
$3,533.35
$8,165.94
$15,801.52
$23,523.52
$31,245.53
$53,796.98
$76,274.17
$110,398.26
$246,894.60
$374,980.70
$628,219.62
$1,173,600.25
$1,442,853.22
$3,885,940.13
$9,948,417.09
N/A
N/A
Basis for Clearwell Cost
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Steel tank (R.S. Means, 2001)
Pre-stressed concrete tank
(R.S. Means, 2001)
Pre-stressed concrete tank
(R.S. Means, 2001)
Pre-stressed concrete tank
(R.S. Means, 2001)
1. N/A = Not Applicable
2. O&M costs are assumed to be part of a PWS's overall preventive maintenance plan and are expected to be
negligible.
3.7 Costing for Applicable Technologies
This section discusses the methodology for developing cost estimates for the following ground
water treatment systems:
• Gas Chlorination
• Hypochlorination
• Temporary Hypochlorination
• Chlorine Dioxide
• Anodic Oxidation
• Ozonation
Nanofiltration (NF)
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-21
-------
3.7.1 Gas Chlorination Systems
3.7.1.1 Medium-to-Large Systems Costs: W/W Model
EPA used the WAV Model to estimate costs for systems with design flows equal to or greater
than 1 mgd for a chlorine dose of 4 mg/L. Based on the AWWA disinfection survey (AWWA 1998), the
average chlorine dose for community water system (CWS) plants expected to achieve a 4-log inactivation
of viruses was found to be 4 mg/L. Costs were also developed for systems that would require additional
storage capacity for contact time, besides chlorine addition. The details pertaining to additional storage
costs are presented in Section 3.6.
Capital Costs - The WAV Model assumes that systems use the following two kinds of storage
and feed systems to deliver chlorine:
For systems with feed rates between 10 and 100 Ibs/day, costs are developed assuming a
chlorine gas feed system using 150-lb gas cylinders.
• For systems with feed rates between 100 and 2,000 Ibs/day, costs are developed assuming a
feed system using 1-ton gas cylinders.
For systems with feed rates between 2,000 and 10,000 Ibs/day, costs are developed assuming
a feed system with on site-storage with bulk rail delivery.
However, for the range of flows and chlorine gas dose costed, the feed rates were always less than 2,000
Ibs/day. Therefore, the details of the on-site storage with bulk rail delivery option are not discussed here.
Construction costs for a 10 to 100 Ibs/day system include:
Chlorinator
Stand-by chlorinator
Booster pump
Injector
• Piping manifold system
Booster pump piping and valving
Housing for the chlorinator equipment
Cylinder scales
Construction costs for a 100 to 2,000 Ibs/day feed system include the following items in addition
to those discussed under 10 to 100 Ibs/day systems:
• Electrically operated monorail trolley hoist
• Cylinder scales
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-22
-------
Residual analyzer with flow proportioning controls (system > 1,000 Ibs/day)
Storage room for the gas cylinders with 30-day storage capacity
The model outputs were modified using the recommended methodology in Section 3.3.
Additional costs for housing, permitting, and piloting were added to arrive at the total capital costs (see
Section 3.5 for sample calculations). Because chlorination is fairly standardized and easy to operate, EPA
believes that minimal training will be required and the vendor will supply the necessary training at
minimal costs. To the degree that more rigorous training will be required, additional costs will be
incurred.
O&M Costs - System O&M costs include the following:
Process energy
Building energy
Equipment maintenance
Labor
Chemicals
EPA estimated the process energy cost using booster pump size and electrical hoists. The
building energy costs for both the chlorinator room and cylinder storage room include lighting, heating,
and ventilation. The model bases the building energy cost on 102.6 kilowatt-hour per square foot per
year (kWh/ft2/yr) including lighting, heating, and ventilation. Where appropriate, labor hours cover
loading and unloading cylinders from delivery trucks, periodic changeover of gas cylinders, and daily
checking of system operation and the chlorine residual. A cost of $296.80/ton for 1-ton cylinders and
$636/ton for 150-lb cylinders serves as the basis for the annual chemical cost.
3.7.1.2 Small-to-Medium Systems Costs: Water Model
EPA used the Water Model to estimate costs for systems with design flows less than 1 mgd.
Based on the AWWA disinfection survey (AWWA, 1998), the average chlorine dose for community
water system plants expected to achieve a 4-log inactivation of viruses was found to be 4 mg/L. Costs
were also developed for systems that would require additional storage capacity besides chlorine addition.
The details pertaining to the cost estimates for storage tanks are presented in Section 3.6. The model is
applicable for chlorine loading rates in the range 1-80 Ibs/day.
Capital Costs - The gas feed chlorination system used as a basis of design in the Water Model
consists of atypical side stream chemical feed system using 150-lb cylinders for chlorine gas delivery and
storage. The construction costs estimated by the Water Model include the following:
• Chlorine manifold piping
• Chlorinator
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-23
-------
Side stream booster pump
Venturi gas injector
The Water Model includes two feed systems, one using an applicable chlorine feed range of 1 to
40 Ibs/day and the second with a feed range of 40 to 80 Ibs/day. Systems with chlorine usage rates less
than 40 Ibs/day use a single two-cylinder scale. The scale measures the amount of chlorine remaining in
the cylinders. Systems with a chlorine usage rate between 40 and 80 Ibs/day use two parallel gas feed
systems, each with two 150 Ib cylinders and an automatic switch-over. The model includes the cost of
piping and valves between the booster pump and injector system and between the chlorinator and injector.
Construction costs include a 10 feet (ft) by 10 ft by 10 ft building with a 30 air changes/hour ventilation
system, louvers, automatic damper, chlorine leak detector, and protective respiratory apparatus.
The model outputs were modified using the recommended methodology in Section 3.3.
Additional costs for housing, permitting, and piloting were added to arrive at the total capital costs (see
Section 3.5 for sample calculations). Because chlorination is fairly standardized and easy to operate, EPA
believes that minimal training will be required and the vendor will supply the necessary training at
minimal costs. To the degree that more rigorous training will be required, additional costs will be
incurred.
O&M Costs - System O&M costs include the following:
• Process energy
• Building energy
• Equipment maintenance
• Labor
• Chemicals
The model estimates the process energy cost based on a booster pump sized to pump against a
pressure of 150 pounds per square inch (psi) with a capacity varying between 5.5 to 10.5 gallons per
minute (gpm). The model bases the building energy cost on 102.6 kilowatt-hour per square foot per year
(kWh/ft2/yr) including lighting, heating, and ventilation. The model estimated equipment maintenance at
approximately 5 percent of equipment capital cost per year. Labor averages one-half hour per day to
cover periodic changeover of gas cylinders and daily checking of system operation and the chlorine
residual. A cost of $636/ton for chlorine in 150-lb cylinders serves as the basis for the annual chemical
cost.
3.7.1.3 Very Small Systems Costs: VSS Model
The VSS document does not provide equations for chlorine gas feed technology.
3.7.1.4 Gas Chlorination - Cost Summary and Equations
Exhibit 3.12 presents the total capital and O&M costs for each system size (with and without
storage options). Exhibit A. 1 of Appendix A presents the linear regression cost coefficients A and B
(described below) for all pertinent flow ranges for estimated capital and O&M costs. Since cost floor
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-24
-------
estimates are not readily available, the lowest calculated costs are assumed to be the cost floor for this
technology. Costs were assumed to vary linearly with flow between any two adjacent flow points.
Cost ($) = A + [B x Flow (in kgpd)], where:
A = Y-axis intercept of the linear regression for that flow range
B = Slope of the linear regression for that flow range
The data shown in Exhibit A.3 of Appendix A serve as inputs to the Ground Water Rule
economic assessment cost model.
Exhibit 3.12 Estimated Costs for Gas Chlorination Systems (continued on next page)
Design
Flow
(mgd)
Average
Daily Flow
(mgd)
Total Capital
Cost
($)
Annual O&M
Cost
($)
Model Used
Chlorine gas (4.0 mg/L) with no storage
< 0.007
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
210
430
520
< 0.0015
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.35
0.41
0.77
1.4
3
7.8
11
38
120
270
350
$29,868
$29,868
$29,868
$29,868
$29,868
$29,868
$29,868
$29,868
$29,868
$56,898
$58,757
$66,200
$80,157
$112,725
$207,757
$259,231
$583,551
-
-
-
$6,182
$6,182
$6,198
$6,213
$6,267
$6,365
$6,466
$6,554
$6,961
$16,542
$16,812
$18,431
$21 ,287
$22,338
$34,104
$41,973
$117,190
-
-
-
Cost floor1
WM Process 23
WM Process 23
WM Process 23
WM Process 23
WM Process 23
WM Process 23
WM Process 23
WM Process 23
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
Flow beyond model range
Flow beyond model range
Flow beyond model range
Chlorine gas (4.0 mg/L) with storage2
< 0.007
0.007
0.022
0.037
0.091
0.18
0.27
< 0.0015
0.0015
0.0054
0.0095
0.025
0.054
0.084
$30,655
$30,655
$31,575
$32,494
$35,803
$41 ,258
$46,774
$6,182
$6,182
$6,198
$6,213
$6,267
$6,365
$6,466
Cost Floor1
WM Process 23
WM Process 23
WM Process 23
WM Process 23
WM Process 23
WM Process 23
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-25
-------
Design
Flow
(mgd)
0.36
0.68
1
1.2
2
3.5
7
17
22
76
210
430
520
Average
Daily Flow
(mgd)
0.11
0.23
0.35
0.41
0.77
1.4
3
7.8
11
38
120
270
350
Total Capital
Cost
($)
$52,291
$71,904
$118,547
$152,442
$288,030
$414,413
$661,550
$1,267,239
$1,570,320
$4,147,151
-
-
-
Annual O&M
Cost
($)
$6,554
$6,961
$16,542
$16,812
$18,431
$21 ,287
$22,338
$34,104
$41,973
$117,190
-
-
-
Model Used
WM Process 23
WM Process 23
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
W/W Process 50
Flow beyond model range
Flow beyond model range
Flow beyond model range
1 Since cost floor estimates are not readily available, the lowest calculated costs are assumed to be the minimum
costs for this technology. A cost floor refers to the minimum cost incurred by any system, howsoever small, in
implementing a technology. It is driven by the minimum size of the individual components that make a unit process or
the minimum lot size of equipments and fittings. For example, commercially available pumps can't be smaller than a
particular size.
2 See Exhibit 3.9 for storage costs.
3.7.2 Hypochlorination Systems (with and without additional storage)
Based on the AWWA disinfection survey (AWWA, 1998), the average chlorine dose for
community water system plants expected to achieve a 4-log inactivation of viruses was found to be 4
mg/L. This section discusses the assumptions made to develop cost estimates for hypochlorination
systems, using the cost models. Costs were also developed for systems that would require additional
storage capacity besides chlorine addition. Costs were also not included for training as it is assumed water
treatment operators are familiar with chlorination. The details pertaining to the cost estimates for
additional storage are presented in Section 3.7.
3.7.2.1 Medium-to-Large Systems Costs: W/W Model
The W/W Model was used to estimate hypochlorination costs for systems with design flows
greater than or equal to 1 mgd. The model can estimate costs up to a design flow of 200 mgd.
3.7.2.2 Small-to-Medium Systems Costs: Water Model
The hypochlorination systems used as a basis of design in the Water Model are capable of
feeding 0.1 to 100 Ibs/day of either sodium or calcium hypochlorite solution. Using the equipment listed,
systems may feed an equivalent of 0.01 to 1,000 Ibs/day of available chlorine, depending upon
hypochlorite solution strength and metering pump output.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-26
-------
Capital Costs - The construction costs estimated by the Water Model include the following:
• Solution preparation tank with mixer
• Strainer at the solution tank discharge
• Diaphragm metering pump
The system includes an electrical interlock to ensure that the system feeds hypochlorite solution
only when water is flowing. Operators manually set the metering pump discharge rate, therefore, the
system requires a constant water flow rate. EPA assumed the system uses PVC piping and valves.
Construction costs include alOftbylOftbylOft building with an emergency shower.
The model outputs were modified using the recommended methodology in Section 3.3.
Additional costs for housing, permitting, and piloting were added to arrive at the total capital costs (see
Section 3.5 for sample calculations). Because chlorination is fairly standardized and easy to operate, EPA
believes that minimal training will be required and the vendor would supply any needed training at
minimal costs. To the degree that more rigorous training will be required, additional costs will be
incurred.
O&M Costs - System O&M costs include the following:
Process energy
Building energy
Equipment maintenance materials
Labor
Chemicals
EPA estimated the process energy cost based on a diaphragm meter pump used continuously and
a periodically used mixer on the hypochlorite solution tank. The costs of equipment maintenance
materials include periodic maintenance of the metering pump. EPA assumed an average of one-half hour
per day spent on labor to cover the periodic preparation of the hypochlorite solution, and the daily
checking of system operation and chlorine residual. A cost of $1,192.50/ton for 12.5 percent sodium
hypochlorite solution (about 1 pound of chlorine per gallon) formed the basis for the annual chemical cost
estimates.
3.7.2.3 Very Small Systems Costs: VSS Model
Capital Costs - To estimate capital costs, EPA used the relevant VSS Model equations for design
flows between 0.030 mgd and 0.1 mgd for a hypochlorite feed system. The VSS Model estimated the
capital costs for these systems (excluding permitting costs) at $4,700. The model outputs were modified
using the recommended methodology in section 3.3. Additional costs for housing, permitting, and
piloting were added to arrive at the total capital costs (see section 3.5 for sample calculations). The total
capital costs (in 2003 dollars) are presented in Exhibit 3.12. Because chlorination is fairly standardized
and easy to operate, EPA assumed that the vendor would supply the needed training at minimal costs. To
the degree that more rigorous training will be required, additional costs will be incurred.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-27
-------
O&M Costs - The VSS O&M equation generated unrealistically high O&M costs relative to the
Water Model O&M outputs for the higher flow rates. Therefore, EPA developed O&M cost estimates
using engineering costing procedures for average flows less than and equal to 0.025 mgd. They were
based on the following assumptions based on best professional judgement:
Part replacement cost was estimated based on vendor quotes for parts anticipated to fail or be
consumed (tube or diaphragm for chemical metering pumps, reagents for on-line chlorine
analyzer).
Electricity costs were estimated based on metering pumps power requirements.
Labor costs reflect the labor hours required for routine maintenance. Maintenance labor
hours were assumed to be 4 hours per month.
• Labor and chemical costs used for developing these costs are listed in Exhibits 3.3 and 3.5,
respectively.
3.7.2.4 Hypochlorination - Cost Summary and Equations
Total capital and O&M costs (in 2003 dollars) for each system size are presented in Exhibit 3.13.
Exhibit A.4 of Appendix A presents the linear regression cost coefficients A and B (described below) for
all pertinent flow ranges. Since cost floor estimates are not readily available, the lowest calculated costs
are assumed to be the cost floor for this technology. Costs were assumed to vary linearly with flow
between any two adjacent flow points. Because there is a discontinuity in the costs where the cost models
changed, the highest cost for the Water Model was extended into the region of the WAV Model which
predicted lower costs than the Water Model. This gives a conservative estimate for the area where the
models disagree.
Cost ($) = A + [B x Flow (in kgpd)], where:
A = Y-axis intercept of the linear regression for that flow range
B = Slope of the linear regression for that flow range
The data shown in Exhibit A.4 of Appendix A serve as inputs to the GWR EA Cost Model.
3.7.2.5 Additional Cost Model Inputs for Gas Chlorination and Hypochlorination
The GWR EA Cost Model generates costs for systems that currently disinfect but do not achieve
4-log inactivation of viruses. Based on the AWWA disinfection survey data (AWWA, 1998) the average
chlorine dose of the CWS plants in this category was found to be 2.5 mg/L. Therefore costs are also
developed for gas chlorination and hypochlorination systems (specifically, hypochlorination for systems
serving populations less than 10,000 and gas chlorination for the rest) increasing the chlorine dose from
2.5 mg/L to 4 mg/L. This is consistent with the assumption that a dose of 4 mg/L will achieve 4-log
inactivation of viruses.
The increase in O&M costs (in 2003 dollars) for each system size are presented in Exhibit 3.13.
Exhibit A.5 of Appendix A presents the linear regression cost coefficients A and B (described below) for
all pertinent flow ranges. The use of different models causes a discontinuity in costs with a sharp spike
and then a dip. The costs for the 0.0095 mgd flow was extended over the next two flows to smooth out
the curves and remove the unrealistic spike.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-28
-------
Increase in Cost ($) = A + [B x Flow (in kgpd)], where:
A = Y-axis intercept of the linear regression for that flow range
B = Slope of the linear regression for that flow range
Exhibit 3.13 Estimated Costs for Hypochlorination Systems
Design
Flow
(mgd)
Average Daily
Flow (mgd)
Total Capital
Cost
($)
Annual O&M Cost
($)
Model Used
Hypochlorite (4 mg/L) without storage
< 0.007
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
210
430
520
< 0.0015
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.35
0.41
0.77
1.4
3
7.8
11
38
120
270
350
$8,970
$8,970
$8,970
$8,970
$8,970
$24,402
$24,402
$24,402
$24,402
$69,897
$72,604
$81,006
$88,812
$103,095
$137,972
$152,455
$297,421
-
-
-
$1,468
$1,468
$1,665
$1,871
$2,650
$6,414
$6,602
$6,765
$7,519
$4,660 3
$5,157
$7,975
$12,768
$24,652
$59,887
$83,394
$281,401
-
-
-
Floor for capital cost1, O&M cost2
Floor for capital cost1, O&M cost2
Floor for capital cost1, O&M cost2
VSS for capital cost, O&M cost2
VSS for capital cost, O&M cost2
WM Process 25
WM Process 25
WM Process 25
WM Process 25
W/W Process 49
W/W Process 49
W/W Process 49
W/W Process 49
W/W Process 49
W/W Process 49
W/W Process 49
W/W Process 49
Beyond model range4
Beyond model range4
Beyond model range4
Hypochlorite (4.0 mg/L) with storage5
< 0.007
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
< 0.0015
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.35
0.41
0.77
$9,757
$9,757
$10,677
$11,596
$14,906
$35,793
$41,309
$46,826
$66,439
$131,546
$166,289
$302,836
$1,468
$1,468
$1,665
$1,871
$2,650
$6,414
$6,602
$6,765
$7,519
$4,660 3
$5,157
$7,975
Floor for capital cost1, O&M cost2
Floor for capital cost1, O&M cost2
Floor for capital cost1, O&M cost2
VSS for capital cost, O&M cost2
VSS for capital cost, O&M cost2
WM Process 25
WM Process 25
WM Process 25
WM Process 25
W/W Process 49
W/W Process 49
W/W Process 49
1 Since cost floor estimates are not readily available, the lowest calculated costs are assumed to be the minimum
costs for this technology.
2 O&M costs are based on engineering costing procedures using assumptions based on best professional
judgement.
3 A drop in O&M costs is due to the use of a different cost model (i.e., the W/W Model)
4 Chlorine use rate outside range of costing models.
5 See Exhibit 3.10 for storage costs.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-29
-------
Exhibit 3.14 Estimated Additional O&M Costs For Hypochlorite/ Gas Chlorination
Systems When Increasing Chlorine Dose From 2.5 mg/L to 4 mg/L
Average Daily Flow (mgd)
< 0.0015
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.35
0.41
0.77
1.4
3
7.8
11
38
120
270
350
Annual O&M Cost Increase
$28
$28
$102
$179
$471
$127
$197
$259
$542
$1,100
$1 ,256
$2,252
$2,370
$5,107
$7,184
$10,137
$39,395
-
-
-
Comment
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Hypochlorite
Chlorine gas
Chlorine gas
Chlorine gas
Chlorine gas
Chlorine gas
Beyond model range
Beyond model range
Beyond model range
1. Hypochlorination costs for average flows • «0.025 mgd are based on best professional judgement.
2. Hypochlorination costs for 0.025 mgd < average flow < 0.35 mgd are based on the Water Model, Process 25.
3. Hypochlorination costs for 0.35 mgd • 'average flow • «0.77 mgd are based on the W/WModel, Process 49.
4. Gas chlorination costs for 0.77 mgd < average flow • «38 mgd are based on the W/W Model, Process 50.
3.7.3 Temporary Hypochlorination
Systems are assumed to install a portable hypochlorination system at the well site. A temporary
hypochlorination system is assumed to consist of a chemical storage tank, a chemical feed pump,
chemical feed tubing, and a housing. The main differences between this option and the permanent
hypochlorination discussed above are the temporary nature of the facilities. Housing costs here are for a
small temporary shelter only large enough to house the equipment rather than a lighted building. Doses
and duration of treatment also differ.
The system was designed assuming a 12.5 percent solution of hypochlorite. The pump was sized
using the system design flow. The tank was sized assuming that it could hold sufficient hypochlorite
solution to provide the average flow rate with a dose of 2 mg/L of hypochlorite for one week. Exhibit
3.15 displays the assumptions for required pumping rates and tank volumes.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-30
-------
Exhibit 3.15 Temporary Hypochlorination Pumping Rates and Tank Volumes
Design
Flow
(mgd)
A
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
210
Average
Flow
(mgd)
B
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.35
0.41
0.77
1.4
3
7.8
11
38
120
Dose (mg/L)
C
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Hypochlorite
Solution
Strength (%)
D
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
12.5%
Hypochlorite
needed
(gal/hr)
E =
A*C/28.752*D
0.0
0.0
0.0
0.1
0.1
0.2
0.2
0.4
0.6
0.7
1.1
1.9
3.9
9.5
12.2
42.3
116.9
Tank Size
(gai)
F =
5.843*B*C/D
0.1
0.5
0.9
2.3
5.0
7.9
10.3
21.5
32.7
38.3
72.0
130.9
280.5
729.2
1028.4
3552.6
11218.7
Costs were taken from the 2003 Cole Farmer catalog. The pumps used were single head
chemical-feed diaphragm pumps. A 115 VAC, 60 Hz pump with 3/8 inch tubing was assumed. For
flows greater than 10 gal/hr high volume pumps were assumed. A service kit including an extra
diaphragm, valve, spring, and O-rings were included in the price for each pump. Costs were also
included for 60 ft. of PTFE tubing. Exhibit 3.16 shows the costs for pumps with given design flow rates.
Exhibit 3.16 Pump Costs (2003$)
Pump Size (gal/hr)
Up to 10.5
> 10. 5 and < 16.5
> 16. 5 and < 32.5
Cost ($)
513.50
668.50
673.50
Source: 2003 Cole Farmer Catalog
If the required flow was greater than 32.5 gal/hr multiple pumps were assumed.
The tanks assumed were XLPE corrosion resistant horizontal leg tanks. Exhibit 3.17 Shows the
costs of the chemical storage tanks. Tanks are available in up to 300 gallon sizes. If more than 300
gallons of storage is required, multiple tanks were assumed.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-31
-------
Exhibit 3.17 Tank Costs (2003$)
Tank Size (gallons)
55
110
200
300
Cost ($)
328.00
408.00
585.00
660.00
Source: 2003 Cole Farmer Catalog
Housing costs were based on the size of the storage tank plus an additional foot clearance. Costs
were calculated using the 1999 RS means cost of $35.15 per square foot. The cost was converted to 2003
dollars by using the BCI index. Exhibit 3.18 Displays the total capital costs of the temporary
hypochlorination system. An extra 25 percent of the total capital costs of the equipment was added to
account for installation and an extra 20 percent was added to account for valving and instrumentation.
Exhibit 3.18 Capital Costs for Temporary Hypochlorination
Design
Flow
(mgd)
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
Average
Flow
(mgd)
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.35
0.41
0.77
1.4
3
7.8
11
38
Capital
Cost ($)
$1,874
$1,874
$1,874
$1,874
$1,874
$1,874
$1,874
$1,874
$1,874
$1,874
$1,990
$2,246
$2,355
$15,822
$19,483
$24,830
Chemical and pumping electricity costs were assumed to be the same as for a hypochlorination
system as listed in above. Labor costs were considered to be for 15 minutes a day for an operator to
check the pump, measure the residual, and refill the storage tank as necessary for systems with a flow of 1
mgd or less and 30 minutes a day for larger systems. A labor rate of $27.01 was used. Exhibits.19
shows the operating and maintenance costs for the system.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-32
-------
Exhibit 3.19 Operating and Maintenance Costs
Design
Flow
(mgd)
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
Average
Flow
(mgd)
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.35
0.41
0.77
1.4
3
7.8
11
38
Chemical &
Electricity
Costs ($)
$172
$172
$369
$575
$1,354
$1,485
$1,673
$1,836
$2,590
$228
$3,046
$7,839
$19,723
$54,958
$78,465
$276,472
Labor ($)
$2,465
$2,465
$2,465
$2,465
$2,465
$2,465
$2,465
$2,465
$2,465
$4,929
$4,929
$4,929
$4,929
$4,929
$4,929
$4,929
Total
O&M ($)
$2,636
$2,636
$2,833
$3,039
$3,818
$3,949
$4,137
$4,300
$5,054
$5,157
$7,975
$12,768
$24,652
$59,887
$83,394
$281,401
3.7.4 Chlorine Dioxide Systems (with and without additional storage)
Costs were estimated based on the cost models and vendor information and are presented for both
systems that would require additional storage capacity and those that will not require additional storage.
The details pertaining to the cost estimates for systems requiring additional storage for added contact time
are presented in Section 3.6.
3.7.4.1 Chlorine Dioxide Dose
Chlorine dioxide costs were evaluated at an applied dose of 1.25 mg/L. This is a conservative
maximum dose for compliance with the chlorite maximum contaminant level (MCL) of 1 mg/L, assuming
70 percent conversion of chlorine dioxide to chlorite and allowing for impurities in chlorine dioxide
generation. An average chlorine dioxide residual of 0.625 mg/L (i.e., half the applied dose) was assumed
for sizing the storage tanks.
3.7.4.2 Capital Cost Assumptions
Feed Equipment (for systems with design flows > 2 mgd)
Feed equipment costs for systems with design capacities greater than 2 mgd were estimated using
the WAV Costs Model. Assumptions for feed equipment in the model include a sodium chlorite mixing
and metering system, a chlorine dioxide generator (0.2 minute detention time), a polyethylene day tank
and mixer, and a dual head metering pump. For systems with design capacities less than or equal to 2
mgd, feed equipment was classified as an O&M cost item instead of a capital cost item. The rationale
behind this assumption and the corresponding costing assumptions are outlined in Section 3.7.4.3.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-33
-------
Instrumentation & Controls (I&C), and Pipe & Valves (P&V)
The WAV Cost Model was used to estimate these line item capital costs for all plant design
capacities. The calculation method for these capital cost line items is not explicitly stated in the WAV
Cost Model documentation. However, the costs developed in the model are based on quantity takeoffs
from actual designs, information from actual plant construction projects, and equipment supplier quotes.
Capital Cost Multipliers
The feed equipment, I&C, and P&V capital cost items were calculated as a subtotal representing
process costs. The process cost subtotal was then multiplied by a capital cost factor (2.5 for systems < 1
mgd or 2.0 for systems • •! mgd); the capital cost factors are intended to account for items not included in
the process costs.
Permitting
Significant process improvements or new treatment will likely require coordination with the
appropriate regulatory agency. As such, permitting costs are included at 3 percent of the process cost. As
discussed in the earlier sections, minimum and maximum permitting costs were assumed to be $2,500 and
$500,000, respectively (NDWAC and TOP recommendations).
Pilot/Bench Testing
The necessity for pilot or bench-scale testing was assumed to ensure that chlorine dioxide use
would be compatible with any existing treatment and/or the water quality conditions. The level of testing
required was estimated based on system size. Costs for testing were included as shown below (see
Exhibit 3.8):
• For systems less than 0.1 mgd: $5,000
• For systems from 0.1 to 1 mgd: $10,000
• For systems greater than 1.0 mgd: $50,000
Chlorine Dioxide System Housing
Housing costs are assumed to be $51.10 per sq. ft. This is based on the R.S. Means (2000)
estimate of the median cost of a factory type building, updated to year 2003 dollars using the BCI. The
footprint area for housing was calculated using the WAV Model. These are shown in Exhibit 3.20.
3.7.4.3 O&M Cost Assumptions
O&M costs for all systems were estimated using the WAV Cost Model. The sections below
address specifics of the line O&M costs.
Feed Equipment (for systems with design flows ' 2 mgd)
This is a capital cost item for systems with design flows greater than 2 mgd. However, based on
vendor information, it is believed that for design capacities less than or equal to 2 mgd, utilities can lease
the equipment more economically than constructing their own system. Thus vendor quotes of equipment
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-34
-------
leasing costs were applied for these systems (i.e., those with design flows • *2 mgd) and classified as an
O&M cost line item instead of a capital cost line item.
Chemical Usage
Chlorine dioxide costs were evaluated at an applied dose of 1.25 mg/L. The unit costs for sodium
chlorite and chlorine gas (i.e., the reactants for generating chlorine dioxide) are presented in Exhibit 3.5.
Footprint area, Electricity and Labor
The footprint area, electricity usage, and labor hours were calculated using the WAV Cost Model.
Exhibit 3.15 presents the values calculated by the model.
Exhibit 3.20 W/W Cost Model Footprint Area, Electricity Usage and Required
Labor
Design Capacity
(mgd)
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
210
430
520
Footprint Area for
Housing (ft2)
109
109
109
109
109
109
114
129
157
225
357
412
1,009
2,192
4,048
4,765
Electricity
Usage/Year (KWh)
3,437
3,437
3,437
3,437
3,437
3,437
3,443
3,457
3,504
3,638
3,917
4,163
7,241
15,165
24,749
29,766
O&M Labor/Year
(hours)
421
454
475
482
500
517
526
577
619
667
816
897
1,356
2,548
3,835
4,521
Source: Based on the W/W Model.
3.7.4.4 Chlorine Dioxide - Cost Summary and Equations
Total capital and O&M costs (in 2003 dollars) for each system size are presented in Exhibit 3.21.
Exhibit A.6 of Appendix A presents the linear regression cost coefficients A and B (described below) for
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-35
-------
all pertinent flow ranges. Cost estimates for design flows < 0.091 mgd are not presented since chlorine
dioxide is not a feasible technology for the very small systems (i.e., systems serving populations < 100).
Costs were assumed to vary linearly with flow between any two adjacent flow points.
Cost ($) = A + [B x Flow (in kgpd)], where:
A = Y-axis intercept of the linear regression for that flow range
B = Slope of the linear regression for that flow range
The data shown in Exhibit A.6 of Appendix A serve as inputs to the GWR EA Cost Model.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-36
-------
Exhibit 3.21 Estimated Costs for Chlorine Dioxide Systems (continued on next page)
Design Flow (MGD)
Average Flow (MGD)
0.007
0.0015
Capital Cost Summary
Total Capital Cost
Subtotal Indirect Capital Costs
Piloting
Permitting
Land
Operator Training
Housing
Housing SF
Other Indirect Costs
Capital Cost Multiplier
Subtotal Process Cost
Pipes and Valves
Instrumentation and controls
Pumping
Chlorine Dioxide Generator
Storage Tanks
Process Monitoring Equipment
Feed Equipment
Other Process Cost #2
0.022
0.0054
0.037
0.0095
0.091
0.025
0.18
0.054
0.27
0.084
0.36
0.11
0.68
0.23
1
0.35
DatrNofOsed
$32,661
$13,061
$5,000
$2,500
$5,561
109
$19,600
$7,840
$1,701
$6,139
$38,604
$18,061
$10,000
$2,500
$5,561
109
$20,543
$8,217
$1,900
$6,317
$39,406
$18,061
$10,000
$2,500
$5,561
109
$21,344
$8,538
$2,073
$6,465
$40,300
$18,061
$10,000
$2,500
$5,561
109
$22,239
$8,895
$2,265
$6,630
$43,239
$18,061
$10,000
$2,500
$5,561
109
$25,177
$10,071
$2,898
$7,173
$40,269
$18,061
$10,000
$2,500
$5,561
109
$22,208
$11,104
$ 3,454
$ 7,650
Annual O&M Cost Summary
Total Annual O&M Cost
Feed Equipment
Chemicals
Part Replacement
Performance monitoring
Materials
Electricity
Electricity Use (KWH)
Labor $
: DltarNotUsed
^-«-
$14,787
$2,373
$30
$1,708
$ 261
3,437
$10,416
$15,953
$2,373
$61
$2,026
$ 261
3,437
$11,232
$17,006
$2,373
$97
$2,239
$ 261
3,437
$12,037
$17,289
$2,373
$121
$2,320
$ 261
3,437
$12,214
$18,112
$2,373
$266
$2,542
$ 261
3,437
$12,670
$18,881
$2,373
$ 399
$ 2,748
$ 261
3,437
$ 13,101
1.2
0.41
$80,831
$58,344
$50,000
$2,500
$5,844
114
$22,487
$11,243
$ 3,462
$ 7,781
$19,673
$2,373
$ 471
$ 2,866
$ 262
3,443
$ 13,702
See Exhibit 3.11 for storage costs.
Technology and Cost Document for the
Final Ground Water Rule
3-37
October 2006
-------
Exhibit 3.21 Estimated Costs for Chlorine Dioxide Systems (continued)
Design Flow (MGD)
Average Flow (MGD)
2
0.77
3.5
1.4
7
3
17
7.8
22
11
76
38
210
120
430
270
520
350
Capital Cost Summary
Total Capital Cost
Subtotal Indirect Capital Costs
Piloting
Permitting
Land
Operator Training
Housing
Housing SF
Other Indirect Costs
Capital Cost Multiplier
Subtotal Process Cost
Pipes and Valves
Instrumentation and controls
Pumping
Chlorine Dioxide Generator
Storage Tanks
Process Monitoring Equipment
Feed Equipment
Other Process Cost #2
$82,332
$59,099
$50,000
$2,500
$6,599
129
$23,233
$11,617
$ 3,484
$ 8,132
$191,425
$60,514
$50,000
$2,500
$8,014
157
$130,911
$65,456
$ 3,526
$ 8,790
$53,140
$211,957
$64,004
$50,000
$2,500
$11,504
225
$147,954
$73,977
$ 3,627
$ 10,413
$59,937
$268,990
$71,191
$50,000
$2,967
$18,224
357
$197,799
$98,899
$ 4,968
$ 14,743
$79,189
$297,453
$74,389
$50,000
$3,346
$21,043
412
$223,065
$111,532
$ 5,824
$ 16,868
$88,841
$605,595
$109,008
$50,000
$7,449
$51,559
1,009
$496,587
$248,293
$ 15,084
$ 39,866
$193,343
$902,161
$172,932
$50,000
$10,938
$111,993
2,192
$729,229
$364,614
$ 22,541
$ 59,146
$282,928
$1,254,689
$271,584
$50,000
$14,747
$206,838
4,048
$983,105
$491,553
$ 30,324
$ 79,948
$ 381,281
$1,379,227
$309,533
$50,000
$16,045
$243,487
4,765
$1,069,694
$534,847
$ 32,976
$ 87,050
$ 414,820
Annual O&M Cost Summary
Total Annual O&M Cost
Feed Equipment
Chemicals
Part Replacement
Performance monitoring
Materials
Electricity
Electricity Use (KWH)
Labor$
$22,048
$2,373
$ 883
$ 3,499
$ 263
3,457
$15,031
$22,001
$ 1,658
$ 3,952
$ 266
3,504
$16,125
$28,867
$ 3,425
$ 4,315
$ 276
3,638
$20,850
$40,191
$ 8,941
$ 5,444
$ 298
3,917
$25,508
$47,010
$ 12,699
$ 5,954
$ 316
4,163
$ 28,040
$94,126
$ 43,724
$ 7,463
$ 550
7,241
$ 42,389
$230,088
$138,128
$ 11,157
$ 1,153
15,165
$ 79,650
$446,533
$ 310,813
$ 13,957
$ 1,881
24,749
$ 119,882
$561,934
$ 402,894
$ 15,451
$ 2,262
29,766
$ 141,326
Technology and Cost Document for the
Final Ground Water Rule
3-38
October 2006
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3.7.5 Anodic Oxidation Systems
In order to estimate costs for anodic oxidation systems, EPA estimated the costs for onsite
generation of hypochlorite, a process that is similar to the anodic oxidation process. This section
discusses the assumptions and the unit process used to estimate costs for anodic oxidation. Costs were
also presented for systems that would require additional storage capacity besides disinfectant addition.
The details pertaining to the cost estimates for storage tanks are presented in Section 3.6.
3.7.5.1 Medium-to-Large Systems Costs: W/W Model
EPA used the WAV Cost Model to estimate costs for all design flow categories. The WAV Cost
Model based the cost estimates on two types of generation equipment: open-cell and membrane systems.
EPA based the costs on the open-cell technology for systems with a chlorine-producing capacity up to
2,500 Ibs/day and membrane technology for systems producing more than 2,500 Ibs of chlorine per day.
Open-cell systems include an electrolysis cell with an anode and a cathode. Membrane systems
include an electrolysis cell with a membrane separating the anode and the cathode. EPA assumed that for
every 1 mg/L of sodium hypochlorite generated 2.2 mg/L of sodium chloride was required (i.e., for a 4
mg/L dose of sodium hypochlorite 8.8 mg/1 of sodium chloride was required).
Capital Costs - The construction costs include the following:
• Electrolysis cells
• Power rectifier
• Salt storage tank
• Brine dissolver
• Brine storage tank
• Water softener
• Brine transfer and metering pumps
• Oxidants solution transfer and metering pumps
• Oxidants solution storage tank
• Piping and valves
• Flowmeters
• Electrical control equipment
• Housing
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-39
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For systems producing more than 500 Ibs/day of chlorine, the storage tank and brine dissolver are located
outside. These estimates include a brine purification system for systems producing more than 2,000
Ibs/day of chlorine. The model outputs were modified using the recommended methodology in Section
3.3. Additional costs for housing, permitting, and piloting were added to arrive at the total capital costs
(see Section 3.5 for sample calculations).
O&M Costs - System O&M costs include the following:
• Process energy
• Equipment maintenance
• Materials
• Chemicals
The process energy requirements vary from 2.0 to 4.7 kilowatt hour per pound (kWh/lb) of
chlorine equivalent. The membrane cell consumes less energy than the open-cell system. Maintenance
requirements include the replacement of the electrode every two years, while material costs include the
salt consumption.
3.7.5.2 Small-to-Medium Systems Costs: Water Model
There are no cost curves or processes available for anodic oxidation systems in the Water Model.
3.7.5.3 Very Small Systems Costs: VSS Model
The VSS document does not provide equations for anodic oxidation systems.
3.7.5.4 Anodic Oxidation - Cost Summary and Equations
Total capital and O&M costs (in 2003 dollars) for each system size are presented in Exhibit 3.22.
Exhibit A.7 of Appendix A presents the linear cost coefficients A and B (described below) for all
pertinent flow ranges. Since cost floor estimates are not readily available, the lowest calculated costs are
assumed to be the cost floor for this technology. Costs were assumed to vary linearly with flow between
any two adjacent flow points.
Cost ($) = A + [B x Flow (in kgpd)], where:
A = Y-axis intercept of the linear regression for that flow range
B = Slope of the linear regression for that flow range
The data shown in Exhibit A.7 of Appendix A serve as inputs to the GWR EA Cost Model.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-40
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3.7.5.5 Additional Cost Model Inputs for Chlorine-based Technologies
The GWR EA Cost Model requires the following input pertaining to the chlorine-based
technologies (i.e., gas chlorination, hypochlorination, chlorine dioxide and anodic oxidation), in addition
to their unit costs (i.e., capital and O&M costs for the various flows):
Disinfection monitoring costs: This involves measuring the disinfectant residual to ascertain the
effectiveness of the disinfection unit process. The disinfection monitoring costs are presented in Exhibit
3.23. The costs are separated into two size categories: (1) for systems serving a population less than or
equal to 3,300, and (2) for systems serving a population greater than 3,300.
Systems serving < 3,300: For systems serving fewer than 3,300 people no capital costs are
incurred. Annual O&M cost components include the following
• Labor costs
Chlorine test kits, each lasting a 100 days. Each system thus incurs the cost of 3.65 kits per
annum.
Systems serving ' 3,300: For systems serving 3,300 people or more both capital and O&M costs
are incurred. Capital cost components include the following:
• Chlorine Analyzer (Hach CL 17)
Power cord
Chart Recorder (Honeywell 10" round)
Installation cost
O&M cost components include the following:
Labor costs
• Maintenance kit
Monthly reagents
• Charts
Recorder
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-41
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Exhibit 3.22 Estimated Costs for Anodic Oxidation Systems
Design
Flow
(mgd)
< 0.007
0.007
0.022
0.037
0.091
0.18
0.27
0.36
0.68
1
1.2
2
3.5
7
17
22
76
210
430
520
Average
Flow
(mgd)
< 0.0015
0.0015
0.0054
0.0095
0.025
0.054
0.084
0.11
0.23
0.35
0.41
0.77
1.4
3
7.8
11
38
120
270
350
Total
Capital
Cost (no
storage)
($)
$39,396
$39,396
$52,218
$60,313
$78,932
$100,475
$111,761
$123,015
$163,065
$219,436
$254,667
$374,031
$575,457
$904,296
$1,632,569
$1,836,363
$3,293,387
-
-
-
Total
Capital
Cost (with
storage1)
($)
$40,184
$40,184
$53,925
$62,940
$84,868
$111,865
$128,668
$145,438
$205,102
$281,085
$348,353
$595,861
$909,713
$1,453,121
$2,692,051
$3,147,452
$6,856,987
-
-
-
Annual O&M
Cost
($)
$2,908
$2,908
$2,914
$5,028
$6,715
$8,596
$9,929
$10,888
$13,533
$15,831
$16,952
$23,064
$29,552
$46,031
$89,120
$117,433
$354,875
-
-
-
Model Used
Cost floor
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
W/W Process 54
Flow beyond model range
Flow beyond model range
Flow beyond model range
1 See Exhibit 3.10 for storage costs.
Exhibit 3.23 Estimated Costs for Disinfection Monitoring (continued on next page)
SYSTEMS SERVING •
-------
Exhibit 3.23 Estimated Costs for Disinfection Monitoring (continued)
SYSTEMS SERVING > 3,300
Component
Frequency (Per
Year)/lnitial nos.
Hours/day
Unit cost
Total cost
Capital Costs
Chlorine analyzer1
Power cord1
Chart recorder1
Installation2 (3,301 -10,000)
Installation2 (10,001 -100,000)
Installation2 (>1 00, 000)
1
1
1
1
1
1
N/A
N/A
N/A
N/A
N/A
N/A
$2,251
$9
$630
$203
$208
$250
$2,251
$9
$630
$203
$208
$250
Total Capital Cost (3,301 - 10,000) = $3,094
Total Capital Cost (10,001 - 100,000) =$3,100
Total Capital Cost (>100,000) =$3,141
Annual O&M Costs
Labor (3,301 -10,000)
Labor (10,001 -100,000)
Labor (>1 00,000)
Maintenance kit1
Monthly reagents1
Charts1
Recorder pens1
80hr./yr.3
80hr./yr.3
80hr./yr.3
1
12
1
1
~
~
~
N/A
N/A
N/A
N/A
$25.34/hr
$26.05/hr
$31 .26
$147
$19
$16
$54
$2,027
$2,084
$2,501
$147
$226
$16
$54
Total O&M Cost (3,301 - 10,000) = $2,470
Total O&M Cost (10,001-100,000) = $2,527
Total O&M Cost (>1 00,000) = $2,944
1 Source: Products for Analysis, Hach Co. catalogue (1998).
2 Source: Labor Costs for National Drinking Water Rules (USEPA, 2003).
3 EPA estimate based on best professional judgement.
Detail may not add due to independent rounding.
3.7.6 Ozonation Systems
3.7.6.1 Ozone Dose
Capital costs were estimated based on an ozone dose of 4.5 mg/L (for details see USEPA, 2003).
The corresponding average ozone dose for day to day operations was assumed to be 2.43 mg/L, and was
used to determine O&M costs.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-43
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3.7.6.2 Capital Cost Assumptions
The capital cost for ozone can be broken down into two distinct categories: process costs and
indirect capital costs. Process costs include in-plant pumping, ozone generation system, ozone contactor,
off-gas destruction facilities, effluent ozone quench, chemical storage, stainless steel piping, valves,
ductwork, and electrical and instrumentation (E&I). Indirect costs applied for the ozone system include
housing, operator training, land, permitting, and piloting.
Process costs were estimated and added together resulting in a total process cost at each flow rate.
This value was then multiplied by the appropriate capital cost multiplier (either 2.0 or 2.5) resulting in a
value that represents constructed process facilities. To this result the indirect costs were added, resulting
in a total capital cost for all elements associated with implementing ozone treatment at an existing
treatment plant.
Process Costs
In-plant Pumping
In-plant pumping costs include costs for a concrete wet-well, vertical turbine pumps, piping, and
valving (P&V), manifolding, and all E&I associated with the in-plant pumping only. P&V and E&I were
included within the in-plant pumping line item costs because common construction practices will apply.
No corrosion resistant materials (e.g., stainless steel) were assumed to be required. Other details are
provided below:
A vertical turbine pump vendor provided the range of flow rates and TDH requirements.
They provided budgetary costs for a set of pumps (one duty, one standby) to meet the
requirements. The costs quoted included bowls, column, shaft, pump discharge head, and
motor.
• Wet-well tankage costs were estimated using the same unit cost curve (cost vs. volume of
wet-well) developed for the ozone contactors (without concrete baffles). Details of this cost
curve development are given in the section "Ozone Contactor Costs".
• P&V and E&I were estimated as a percentage of the manufactured equipment (pump cost)
based on the percentages provided in the WAV Cost Model for in-plant pumping.
Ozone Generation System
Ozone generation costs include costs for the ozone generators, feed gas delivery system, ozone
dissolution system, ambient air ozone monitors, and vendor-provided process monitoring equipment
necessary to verify generation rates and dosing. These costs were developed through contacting suppliers
of ozone generation equipment. Vendors were contacted and given the required oxygen generation rates
(Ibs/day). They responded with quotes for all the above components.
The costs also include the ozone dissolution system (a venturi-type injector). The ozone
dissolution system can consist of venturi-type injector devices or porous diffusers in the ozone contacting
tank. Vendors providing cost estimates universally preferred venturi-type injectors and therefore the
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-44
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costs are based on that type of ozone dissolution. Ozone generation systems are sized based on a transfer
efficiency of 90 percent. As an example for a design dose of 4.5 mg/L the actual ozone generation
requirement is estimated as:
Ozone generation requirement (Ibs/day) =
(4.5 mg/L) x (design flow) * (conversion factor) x (1.1)
The feed gas delivery system include the liquid oxygen (LOX) storage tank for systems where
LOX use is applicable (> 100 Ibs/day). For the smaller systems, the costs include all equipment necessary
to generate oxygen onsite using pressure swing absorption (PSA). PSA requires feed gas equipment such
as an air compressor, air chiller, and air dryer.
Ozone Contactor Costs
Ozone contactor costs include all costs related to installing reinforced concrete tankage. These
costs include excavation, formwork, rebar, concrete, backfill, tank coatings, and miscellaneous hardware
relating directly to the tank (i.e., railings, hatches, pipe supports, additions, etc.). The cost does not
include costs for connecting process lines or ductwork to the exterior of the tank or connecting
instrumentation cabling or required electrical cabling to the tank. With a given tank volume estimate unit
costs measured in terms of $/cubic yard of concrete were applied. The unit costs used for concrete
approved for drinking water use are the following:
$525/cubic yard for floors and slabs
$675/cubic yard for walls and baffles
$825/cubic yard for decks
These unit costs are based on best professional judgement where each of the above unit costs is
1.5 times a base cost for only the concrete work in many locations in the United States. That is, to
perform only the concrete work (no excavation, backfill, misc. fittings, coatings, etc.) values of $350,
$450, and $550 per cubic yard are commonly used as unit costs for installation of floors, walls, and decks,
respectively. The value of $525 used here for slabs results from (1.5) * ($350). The 1.5 multiplier
represents approximately 25 percent for excavation and backfill costs and 25 percent for miscellaneous
hardware related directly to the tank. The costs were then updated to 2003 dollars by using the BCI
index. Concrete costs are quite variable across the United States. The 2001 Means Heavy Construction
Cost Data reference gives a range between $56/cubic yard and $90/cubic yard for 5000 psi ready-mix
concrete for Cincinnati, OH and San Francisco, CA, respectively. The unit costs used capture
representative costs at many locations. Using these unit costs and the tankage design assumptions, cost
vs. contactor volume relations were developed for both concrete baffled (> 1 mgd) and non-concrete
baffled tanks. Specific "geometric" design criteria applicable for the ozone contact chamber costs are
summarized below:
• wall thickness = 18in, bottom slab and cover thickness = 12in
• length-to-width ratio = 2.5
• water depth inside the chamber ranges from 5 to 20 feet
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-45
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design volume = 1.2 x required volume (for freeboard and odor control)
• concrete baffle thickness = Sin (Note: stainless steel baffles for systems with design flows < 1
mgd and concrete baffles for systems with design flows • i mgd)
Off-Gas Destruction
Off-gas destruction cost includes the catalytic destruction unit and the blower to maintain
negative pressure over the contactors. Ductwork for conveying the off-gas from the contactors to the unit
is not included in this line item cost. E&I around the unit is not included in this line item. These items are
accounted for separately (see Stainless Steel Piping (Including Valves and Duct Work and Electrical and
Instrumentation)).
Effluent Ozone Quench
Ideally, the ozone dose provides the treatment necessary in the contactor and no ozone residual is
left as the treated stream leaves the contactor. However, this situation is not always achieved and some
ozone residual usually leaves the reactor. To eliminate downstream reactions outside of the contactor,
such as corrosion of equipment, the residual ozone must be quenched (destroyed) prior to the next unit
process. The ozone quenching is assumed to be conducted with hydrogen peroxide fed from a storage
facility into the effluent stream by chemical feed pumps. The quench system includes peroxide storage,
chemical feed pumps, and a liquid phase ozone analyzer. Design assumptions are outlined below.
Peroxide is stored and used as 35 percent solution (by weight).
• Peroxide quenches ozone 1:1 by weight.
10 percent of design transferred dose ends up as residual (requiring peroxide quench).
Peroxide storage facilities must allow for 30 days of storage without new deliveries.
Effluent ozone quench includes the cost of the hydrogen peroxide storage tank(s), peroxide feed
pumps, and an effluent residual ozone sensor (liquid stream unit) and associated analyzer. These costs
were based on calls to vendors; some package delivery systems were costed as well as the individual
components to build a complete system. Costs do not include P&V necessary to convey peroxide to the
injection location. They do not include E&I beyond the purchase of the ozone analyzer. These items are
accounted for separately (see Stainless Steel Piping (Including Valves and Duct Work and Electrical and
Instrumentation (E&I) on page 3-44). The following three quenching systems based on dosing
requirements were costed.
• Very small quenching systems (i.e., systems dosing less than 100 gallons per month). These
systems were assumed to store peroxide in 55 gallon drums and dose directly from the drums
with chemical feed pumps. The pump controls are skid or frame mounted near the drums and
pumps. No capital cost for tankage is incurred; the drums were assumed to be changed out
by a chemical supplier (O&M cost only). The system cost is the sum of the individual
components as quoted by vendors.
Small quenching systems (i.e., systems dosing between 100 and 1,000 gallons of peroxide per
month). These systems were assumed to maintain permanent stainless steel storage tanks on
site in addition to the chemical feed pumps and analyzer. The system cost is the sum of the
individual components as quoted by vendors.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-46
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Large quench systems (i.e., systems dosing in excess of 1,000 gallons of peroxide per
month). The costs were based on package systems from a peroxide supply vendor. The cost
includes a 9,600 gallon stainless steel storage tank, skid mounted dosing pumps, some
controls between the pumps and the tanks, and all suction piping between the tank and the
chemical feed pump.
Chemical Storage
A concrete pad was assumed as a capital cost for the LOX tank and the larger peroxide tanks at
the larger dose and quench requirements. The concrete was assumed to be 12"-thick reinforced concrete
with an "on-grade" slab cost of $350/cubic yard.
Stainless Steel Piping (Including Valves and Duct Work)
A cost addition of 25 percent of the sum of the costs for the ozone generation system, ozone
contactor, off-gas destruction facilities, and effluent quench system is included as a process cost line item.
This addition captures the material cost of all piping, valves, fittings, ductwork, and dampers to convey
the liquid and air streams to or from one unit process to the next. New piping and appurtenances for the
liquid stream can be expected before and after the in-plant pumping facilities, ozone generation system,
ozone contactors, and effluent ozone quench system.
Budgetary cost estimates for these components in water and wastewater treatment facilities range
widely with values from 10 to 35 percent of the process costs being commonly referenced. In the Water
Model documentation, pipes and valves range from 7 to 20 percent of the cost of the manufactured
equipment depending on the ozone feed rate (Ib/day). A recent cost estimate for a full scale ozone retrofit
in Southern California has piping (including valves and appurtenances) at 24 percent of total equipment
cost and 27 percent of the ozone equipment cost. Ozone is very corrosive; therefore, all process piping
that may come in contact with ozone must be made of a corrosion resistant metal such as stainless steel.
The value of 25 percent was selected to represent the premium paid for the corrosive resistant piping that
will be required in much of the process.
Electrical and Instrumentation (E&I)
A cost addition of 20 percent of the sum of the costs for the ozone generation system, ozone
contactors, off-gas destruction facilities, and effluent quench system was included as a separate process
cost line item. This line item captures the cost of electrical and instrumentation equipment (cabling,
motor control centers, Programmable Logic Controls (PLCs), additional ozone analyzers, flow meters
communications cable, software, standby power, etc.) beyond that provided with the ozone generation
system or the effluent quench system. This addition includes instrumentation to ensure that housing
around the ozone generator is monitored for ambient ozone levels. Alarm systems are typically part of a
monitoring program. Costs for these items also range widely depending on the process and the source.
The Water Model documentation suggests that E&I costs as a percentage of manufactured equipment
range from 41 to 56 percent. EPA used 20 percent of all the components of the process not solely the
generation equipment to represent the electrical and instrumentation costs.
Indirect Costs
Indirect costs assumed for the ozone system include housing, operator training, land, permitting,
and piloting.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-47
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Housing
These costs are based on the estimated footprint of the ozone generation equipment (minimum
100 ft2), multiplied by an average housing cost of $51. I/ft2 based on RS Means (2000) factory building
estimates updated to year 2003 dollars using the BCI.
Operator training
This is assumed to be a capital cost for systems with flows less than 1 mgd. Forty hours of
training is assumed at the technical labor rate. For systems greater than 1 mgd, training is assumed
to occur on the job.
Piloting and Permitting
Exhibit 3.7 shows the piloting assumptions for ozone. The pilot costs for the smaller systems
(<1.0 mgd) assume limited testing of the water in an off-site laboratory or possibly at the vendor's facility
(ozone generation system vendor). The cost for larger systems is based on a detailed cost estimate of an
existing pilot system. The piloting assumptions for the larger systems include equipment necessary to
perform the testing (using a small clear PVC contactor), enough labor to run the test four different times
for a week each time (to capture seasonal variability), and labor to write up the findings in the report. No
off-gas destruction or ozone quenching is provided as it is not likely to be necessary for a small test
application. The objective of such a pilot test is to develop design criteria for ozone dose and reactor
sizing. The costs above do not capture the effort required to understand how ozone treatment may impact
other plant unit processes or the stability of the treated water in the distribution system. For further
discussion of unintended consequences and related potential increases in health risks see Section 5.2.5.9
of the GWR EA. Permitting costs were added based on the assumptions outlined in section 3.3.
pH adjustment
To control bromate formation during ozonation, it may be necessary to lower the pH in certain
waters. Separate costs are estimated for pH adjustment so that this cost may be added to the costs of
ozonation where appropriate. The pH adjustment costs include addition of a feed system and chemical
costs to reduce the pH using sulfuric acid and raising the pH using caustic (after ozonation). Capital costs
for pH reduction are developed based on calls to vendors for significant components that make up an acid
feed system. Since the acid feed may or may not be used depending on the system, percentages for pipes
and valves, E&I, and capital cost multipliers are applied separately and it is included as a line item under
"indirect costs".
3.7.6.3 O&M Cost Assumptions
O&M costs include LOX, quenching agent, part replacement, performance monitoring,
electricity, and labor costs. Exhibit 3.24 details the O&M assumptions.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-48
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Exhibit 3.24 Ozonation O&M Cost Assumptions
Cost Item
LOX (where used)
Quench
Part Replacement
Electricity
BDOC Monitoring
pH reduction (when
used)
Basis
$80/ton for LOX
Chemical suppliers contacted for chemical costs.
Vendor provided estimates as a percentage of ozone equipment costs.
Pumps and ozone generation. $0.076/kWh, 1 1 .3 kWh/lb ozone for smaller
systems (<100 Ibs/day), includes generator, destruction unit, and PSA. 5.2
kWh/lb ozone for LOX systems, includes generator and destruction unit.
1 sample/week/reactor for biological dissolved organic carbon,
$100/sample.
Assuming 50th percentile alkalinity (78 mg/L as CaCO3) and pH (7.7) from
the ICR database, acid and caustic O&M costs were estimated. The unit
costs for chemicals were based on bulk shipments from chemical suppliers.
Source: Vendor estimates, best professional judgement, and the ICR database, as applicable.
The labor costs are a function of the cost category and the assumptions on the level of effort for
each system, presented below:
• 3 hr/day for monitoring, plus 4 hr/month maintenance (< 100 mgd design flow)
• 6 hr/day for monitoring, plus 8 hr/month maintenance (• "100 mgd design flow)
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-49
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3.7.6.4 Ozonation - Cost Summary and Equations
Total capital and O&M costs (in 2003 dollars) for each system size are presented in Exhibit 3.25.
Exhibit A. 8 of Appendix A presents the linear regression cost coefficients A and B (described below) for
all pertinent flow ranges. Cost estimates for design flows < 0.091 mgd are not presented since ozonation
is not a feasible technology for the very small systems (i.e., systems serving populations < 100). Costs
were assumed to vary linearly with flow between any two adjacent flow points.
Cost ($) = A + [B x Flow (in kgpd)], where,
A = Y-axis intercept of the linear regression for that flow range
B = Slope of the linear regression for that flow range
The data shown in Exhibit A. 8 of Appendix A serve as inputs to the GWR EA Cost Model.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-50
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Exhibit 3.25 Estimated Costs for Ozonation Systems (continued on next page)
Design Flow (mgd)
Average Flow (mgd)
0.091
0.025
0.18
0.054
0.27
0.084
0.36
0.11
0.68
0.23
1
0.35
1.2
0.41
Unit Capital Cost Summary
Total Unit Capital Cost (no pH adj.)
Indirect Capital Costs (no pH adj.)
Total Unit Capital Cost (with pH adj.)
Indirect Capital Costs (with pH adj.)
Piloting
Permitting
Land
Operator Training
Housing
pH adjustment (if used)
Capital Cost Multiplier
Subtotal Process Cost
Stainless pipes, valves, ductwork
Ozone process E&l
Off Gas Destruction
Effluent Ozone Quench
Ozone Contactor
Ozone Generation System
In plant pumping
Chemical Storage
$323,268
$17,897
$346,000
$40,628
$5,000
$3,664
$2,443
$924
$5,866
22,732
$305,371
$122,149
$15,954
$12,763
$6,528
$4,908
$8,164
$44,215
$29,617
$0
$383,356
$23,977
$426,480
$67,101
$10,000
$4,313
$2,875
$924
$5,866
43,124
$359,379
$143,752
$19,483
$15,586
$7,712
$4,955
$13,027
$52,238
$30,750
$0
$439,266
$25,138
$483,965
$69,837
$10,000
$4,970
$3,313
$990
$5,866
44,699
$414,128
$165,651
$23,061
$18,449
$8,910
$5,003
$17,982
$60,351
$31,895
$0
$493,875
$26,209
$540,149
$72,482
$10,000
$5,612
$3,741
$990
$5,866
46,274
$467,667
$187,067
$26,556
$21,245
$10,108
$5,051
$22,603
$68,463
$33,040
$0
$676,432
$29,788
$728,305
$81,661
$10,000
$7,760
$5,173
$990
$5,866
51,873
$646,644
$258,657
$38,593
$30,875
$14,366
$5,221
$37,476
$97,309
$34,817
$0
$805,095
$88,774
$862,567
$146,246
$65,000
$10,745
$7,163
$0
$5,866
57,472
$716,322
$358,161
$54,321
$43,457
$18,625
$5,391
$67,114
$126,155
$43,097
$0
$902,872
$91,158
$963,844
$152,130
$65,000
$12,176
$8,117
$0
$5,866
60,971
$811,714
$405,857
$61,756
$49,405
$21,287
$5,497
$76,058
$144,184
$47,671
$0
Annual O&M Summary
Total Annual O&M Cost (no pH adjust.)
Total Annual O&M Cost (with pH adjust)
Chemicals O2
Chemicals H2O2
Part Replacement
Performance monitoring
Electricity
Labor
pH adjustment (when used)
$55,520
$56,513
$0
$36
$946
$10,400
$306
$43,832
993
$55,884
$58,029
$0
$79
$1,118
$10,400
$456
$43,832
2,145
$59,391
$62,728
$0
$123
$1,292
$10,400
$611
$46,966
3,337
$59,737
$64,107
$0
$161
$1,465
$10,400
$746
$46,966
4,370
$61,152
$70,289
$0
$336
$2,082
$10,400
$1,368
$46,966
9,137
$62,566
$76,470
$0
$511
$2,700
$10,400
$1,990
$46,966
13,904
$63,350
$79,638
$0
$598
$3,086
$10,400
$2,301
$46,966
16,287
Technology is not feasible for systems with design flows less than 0.091 mgd.
adj. = adjustment.
Technology and Cost Document for the
Final Ground Water Rule
3-51
October 2006
-------
Exhibit 3.25 Estimated Costs for Ozonation Systems (continued)
Design Flow (mgd)
Average Flow (mgd)
2
0.77
3.5
1.4
7
3
17
7.8
22
11
76
38
210
120
430
270
520
350
Unit Capital Cost Summary
Total Unit Capital Cost (no pH adj.)
Indirect Capital Costs (no pH adj.)
Total Unit Capital Cost (with pH adj.)
Indirect Capital Costs (with pH adj.)
Piloting
Permitting
Land
Operator Training
Housing
pH adjustment (if used)
Capital Cost Multiplier
Subtotal Process Cost
Stainless pipes, valves, ductwork
Ozone process E&l
Off Gas Destruction
Effluent Ozone Quench
Ozone Contactor
Ozone Generation System
In plant pumping
Chemical Storage
$1,227,534
$105,167
$1,302,503
$180,136
$65,000
$16,836
$11,224
$0
$12,107
74,969
$1,122,367
$561,184
$85,853
$68,682
$29,525
$5,922
$107,982
$199,982
$63,238
$0
$1,597,111
$123,040
$1,698,325
$224,254
$65,000
$22,111
$14,741
$0
$21,188
101,215
$1,474,071
$737,035
$111,868
$89,494
$36,307
$6,719
$158,526
$245,920
$86,184
$2,018
$2,360,888
$162,340
$2,523,342
$324,794
$65,000
$32,978
$21,985
$0
$42,376
162,454
$2,198,548
$1,099,274
$167,219
$133,775
$52,132
$8,578
$255,057
$353,108
$126,461
$2,944
$3,957,086
$280,413
$4,294,510
$617,837
$65,000
$55,150
$36,767
$0
$123,496
337,424
$3,676,673
$1,838,337
$280,370
$224,296
$82,171
$13,889
$468,843
$556,575
$206,601
$5,592
$4,559,473
$330,542
$4,984,382
$755,451
$65,000
$63,434
$42,289
$0
$159,819
424,909
$4,228,931
$2,114,466
$322,289
$257,831
$91 ,729
$16,545
$559,567
$621,315
$238,274
$6,915
$12,674,233
$911,177
$14,043,980
$2,280,924
$65,000
$176,446
$117,631
$0
$552,101
1 ,369,747
$1 1 ,763,056
$5,881 ,528
$81 1 ,823
$649,458
$251 ,298
$72,638
$1 ,221 ,228
$1,702,128
$1,151,745
$21,211
$26,570,288
$2,199,804
$30,284,633
$5,914,149
$65,000
$365,557
$243,705
$0
$1,525,542
3,714,345
$24,370,484
$12,185,242
$1,542,432
$1,233,946
$425,249
$121,238
$2,742,878
$2,880,363
$3,182,452
$56,684
$45,364,301
$3,876,427
$52,927,986
$11,440,112
$65,000
$500,000
$414,879
$0
$2,896,548
7,563,685
$41 ,487,874
$20,743,937
$2,433,201
$1,946,560
$594,031
$201 ,029
$4,914,161
$4,023,582
$6,516,449
$114,924
$53,714,159
$4,423,346
$62,852,574
$13,561,761
$65,000
$500,000
$492,908
$0
$3,365,438
9,138,415
$49,290,813
$24,645,407
$2,866,603
$2,293,283
$686,415
$233,670
$5,896,994
$4,649,334
$7,880,357
$138,750
Annual O&M Summary
Total Annual O&M Cost (no pH adjust.)
Total Annual O&M Cost (with pH adjust)
Chemicals O2
Chemicals H2O2
Part Replacement
Performance monitoring
Electricity
Labor
pH adjustment (when used)
$67,621
$98,210
$0
$1,124
$4,280
$10,400
$4,166
$47,652
30,589
$77,719
$133,334
$4,557
$1,605
$5,263
$10,400
$7,431
$48,463
55,616
$95,346
$214,522
$9,764
$3,439
$7,557
$10,400
$15,722
$48,463
119,177
$145,700
$455,559
$25,387
$8,943
$11,911
$10,400
$40,596
$48,463
309,859
$177,752
$614,733
$35,802
$12,611
$13,296
$10,400
$57,179
$48,463
436,981
$464,832
$1,974,401
$123,681
$43,567
$36,426
$15,600
$197,096
$48,463
1 ,509,569
$1,377,320
$6,144,381
$390,570
$137,580
$61 ,640
$31 ,200
$622,028
$134,302
4,767,061
$2,871,997
$13,597,884
$878,783
$309,554
$86,105
$52,000
$1,399,343
$146,212
10,725,886
$3,662,456
$17,566,383
$1,139,163
$401 ,274
$99,496
$62,400
$1,813,911
$146,212
13,903,927
adj. = adjustment.
Technology and Cost Document for the
Final Ground Water Rule
3-52
October 2006
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3.7.7 Nanofiltration (NF)
3.7.7.1 General Assumptions
NF is an advanced treatment process that typically requires higher levels of pre- and post-
treatment than traditional water treatment processes. The costs provided assume that the NF system is
used on a system already generating water of desired quality for NF or that the ground water is of good
enough quality to not require pretreatment. These costs do not include any additional post-treatments that
may be necessary because of site-specific water quality. Costs are developed assuming a feed water
temperature of 10°C. It should be noted that the cost of a NF system can vary with the design
temperature, and that the assumption is conservative.
The cost estimates assume 100 percent of the flow is treated by the NF membranes (i.e., no
blending). Recovery is assumed to be 85 percent. In some regions, an additional cost for purchased
water may be incurred as a result of the 15 percent water loss as a result of this type of operation. The
costs associated with these losses are not included in the estimates provided because the costs of water
can be highly variable from region to region and may also include complex legal issues.
3.7.7.2 Capital Cost Assumptions
Capital costs are estimated based on vendor quotes, cost estimating guides (RS Means, 2001),
cost models, and best professional judgement. The spent brine is assumed to be directly discharged to a
sewer. The methodology used for estimating capital costs is discussed in this section.
Membrane System Costs
NF equipment costs were obtained from vendors. The NF equipment cost included costs for the
following items:
• Membrane skid with filter housings
• NF membrane elements (initial batch)
• Cartridge prefiltration
• System feed pumps
• Acid and anti-sealant feed systems
• Clean-in-place system
• Instrumentation and controls
• Pipes and valves
The typical percent distribution of the above components in the NF equipment cost is shown in
Exhibit 3.26. The NF skids are equipped with all necessary instrumentation and controls and pipes and
valves and therefore these costs are included as part of the NF equipment cost.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-53
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Exhibit 3.26 Percent Distribution of NF Equipment Cost
Capital Cost Item
Membrane skid with filter housings
NF membrane elements (initial batch)
Cartridge prefiltration
System feed pumps
Acid and anti-sealant feed systems
Clean-in-place system
Instrumentation and controls
Pipes and valves
Sub-Total NF Equipment Cost
NF Equipment Cost
(as %)
20%
20%
10%
12%
3%
5%
20%
10%
100%
Source: Best professional judgement (USEPA, 2005).
Online Process Monitoring Equipment
Costs for process monitoring included provision of online meters for each NF train/skid. The
meters can be used for integrity testing. The NF train/skid is assumed to have up to a 2 mgd capacity.
Process monitoring equipment include online conductivity/pH meter ($2,500 for meter and probe) and
turbidimeter ($2,500 for meter and probe). For systems less than 2 mgd capacity, one conductivity/pH
meter and one turbidimeter is assumed. For systems greater than 2 mgd, the number of meters is based on
the number trains/skids.
Brine Discharge Pipeline
It is assumed systems will build a brine discharge pipeline either to the ocean, an existing brine
interceptor pipeline, or to a sanitary sewer. Costs for brine discharge include laying a pipeline of 500 ft.
This pipeline is made of PVC or reinforced concrete and assumed to have diameters varying from 2 to 24
inches depending on the quantity of water to be discharged. Costs for the pipeline are obtained from
Small Water System Byproducts Treatment and Disposal Cost Document (DPRA, 1993a) and Water
System Byproducts Treatment and Disposal Cost Document (DPRA, 1993b).
Capital Cost Multipliers
The previously discussed capital costs (e.g., NF equipment, process monitoring equipment and
brine pipeline) are totaled to arrive at the subtotal process cost. The subtotal process cost is then
multiplied with an appropriate multiplier to obtain the capital costs. Capital cost multipliers of 1.67 and
2.0 are used for small (< 2 mgd) and large (• "2 mgd) systems, respectively. Unlike other treatment
processes, membrane systems are typically supplied by the equipment vendor as package, skid-mounted
units; therefore, smaller capital cost multipliers are used.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-54
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Permitting
Incorporating NF treatment will require coordination with the appropriate regulatory agencies.
To account for this, permitting costs are included at 3 percent of the process cost. A minimum permitting
fee of $2,500 and a maximum of $500,000 is assumed (NDWAC and TDP recommendation).
Pilot Testing
It is assumed that pilot- or bench-scale tests are necessary to ensure compatibility of membrane
materials with process chemicals (e.g., preoxidants), as well as determine critical design parameters, such
as design flux and cleaning frequency. Bench-scale flat sheet tests are assumed for systems less than 0.1
mgd at a cost of $1,000. Single-element tests at a one-time cost of $10,000 is assumed for systems
between 0.1 and 1 mgd. For systems greater than 1 mgd, a three month pilot test costing $60,000 is
assumed.
Membrane Housing
Membrane housing costs include the cost for a building to house the membrane skids and any
associated appurtenances (e.g., building electrical, HVAC and lighting). Housing costs will vary
depending on size of the system. Exhibit 3.27 summarizes the membrane housing cost assumptions used
for NF costs. Typical NF plant footprints between 900 to 1,100 ft2 per mgd of design flow is assumed.
For small systems, a minimum housing area of 100 ft2 is assumed. Housing costs are assumed to be
$51.10 per sq. ft. This is based on the R.S. Means (2000) estimate of the median cost of a factory type
building, updated to year 2003 dollars using the BCI.
Exhibit 3.27 Summary of NF Housing Cost Assumptions
System Size (mgd)
< 10 MGD
••10 MGD
Housing Area 1
1,1 00 ft2 per MGD
900 ft2 per MGD
Housing2 Cost ($/ft2)
$51.1
$51.1
1 A minimum housing area of 100 ft2 is also assumed for very small systems.
2 Source: R.S. Means (2000) median cost for a factory type building updated to 2003 dollars using the BCI.
Land
The NDWAC cost working group recommended a factor of 2 to 5 percent of capital cost for land.
Previous technology cost efforts adopted land costs at a factor of 5 percent for systems less than 1 mgd
and 2 percent for systems greater than 1 mgd. However, the previous cases assumed new plant
construction with no land currently available, as opposed to the case in this document where some land at
the well site is already owned by the system. Using a 2-5 percent factor for land resulted in unrealistic
per acreage costs for land acquisition ($/acre). Therefore, the land cost factors are adjusted as shown in
Exhibit 3.28.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-55
-------
Exhibit 3.28 NF Land Cost Assumptions
System Size (mgd)
< 1
1 -<10
••10
Land Cost (% of Capital
Cost)1
2%
1%
0.5%
1Capital Cost = Total Process Cost * Capital Cost Multiplier.
Source: USEPA, 2005.
Operator Training
The NDWAC cost working group also recommended inclusion of operator training. The operator
training costs are based on the number of hours required per system size to train an operator. Based upon
system size, this training could last a few hours or a few days. Exhibit 3.29 summarizes the operator
training cost assumptions used.
Exhibit 3.29 NF Operator Training Cost Assumptions
System Size (MGD)
<0.5
0.5-<1
1 -< 10
10-<100
••100
Training Cost ($)
included in membrane system price
$1,000
$3,000
$10,000
$25,000
Source: USEPA, 2005.
Indirect Capital Costs
Costs for permitting, piloting, membrane housing, land and operator training are calculated and
are referred to as indirect capital costs for the purposes of this document. Indirect capital costs are added
to the direct capital costs to obtain total capital costs.
3.7.7.3 O&M Cost Assumptions
NF O&M costs are estimated using current plant operational data, industry guidelines, and cost
models. This section discusses the assumptions regarding O&M estimates presented in this document.
Clean-in-Place (CIP) Chemicals
NF systems require periodic (typically quarterly or semi-annually) chemical cleaning to remove
biological/particulate foulants and sealants. Membrane cleaning is performed using manufacturer-
recommended cleaning agents. Because of the variability in cleaning practices, a standard rule-of-thumb
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-56
-------
of $0.01 per 1,000 gallons of water produced is assumed for all system sizes to account for cleaning
chemical costs. Thus, cleaning chemical costs can be estimated by the following equation.
Cleaning Chemicals ($/yr) = 0.01 x Average Flow produced (mgd) x 1000 x 365
A minimum cost of $50/year is assumed for cleaning chemicals, this accounts for the cost of
purchasing a 15-gallon pail of cleaning chemical.
Acid/'Anti-Sealant Chemicals
Acid and anti-sealant addition may be necessary to reduce the fouling and scaling of NF
membranes. The dosages of acid and anti-sealant needed is a function of the feed water quality. As a
rule-of-thumb, a cost of $0.04 per 1,000 gallons of water produced is assumed for average flows less than
0.35 mgd and $0.03 per 1,000 gallons is assumed for average flows greater than or equal to 0.35 mgd.
This cost difference represents economies achieved by bulk purchases. Therefore, acid and anti-sealant
chemical costs can be estimated by the following equations.
For average flows < 0.35 mgd
Acid and Anti-Sealant Chemicals ($/yr) = 0.04 x Average Flow produced (mgd) x 1000 x 365
For average flows • O.35 mgd
Acid and Anti-Sealant Chemicals ($/yr) = 0.03 x Average Flow produced (mgd) x 1000 x 365
A minimum cost of $50 is assumed for acid/anti-scalants to account for purchasing these
chemicals in small quantities of 5 gallons.
NF Membrane Replacement
NF membranes are assumed to have a life of 5 years. Therefore, the annual cost for NF
membrane replacement is assumed to be 20 percent of the NF membrane purchase cost.
NF Membrane Replacement ($/yr) = 0.20 x NF Membrane Element Process Cost
Cartridge Filter Replacement
Cartridge filters collect particulate matter and prevent them from depositing on to the NF
membranes. These cartridge filters have to be replaced more frequently for turbid waters and less
frequently for clean waters. Costs for cartridge filter replacement are assumed to be $0.002 per 1,000
gallons of water produced for systems with average flows less than 0.35 mgd and $0.02 per 1,000 gallons
produced for systems with flows greater than or equal to 0.35 mgd. Therefore, cartridge filter
replacement costs can be estimated by the following equations.
For average flows < 0.35 mgd
Cartridge Filter Replacement Cost ($/yr) = 0.002 x Average Flow produced (mgd) x 1000 x 365
For average flows • O.35 mgd
Cartridge Filter Replacement Cost ($/yr) = 0.02 x Average Flow produced (mgd) x 1000 x 365
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-57
-------
Repair, Maintenance and Replacement
NF systems require periodic maintenance and repair. The O&M cost for repair, maintenance, and
purchase of replacement parts is typically about $0.01 per 1,000 gallons produced (Bergman, 1996). A
minimum cost of $ 100 per year is assumed for repair and replacement for small systems. The cost
equation for repair, maintenance, and replacement is shown below.
Repair, Maintenance & Replacement Cost ($/yr) =
0.01 * Average Flow produced (mgd) x 1000 x 365
Performance Monitoring
In addition to online conductivity, pH and turbidity monitoring (included in capital cost
estimates), the costs for periodic heterotrophic plate count (HPC) bacterial monitoring are included in the
O&M estimates. HPC is monitored to detect biological activity on the finished water side of the
membrane. Field HPC tests cost approximately $1 per test, and require 1 hour of labor. The frequency of
HPC testing is assumed to be one test per membrane skid per week. The NF skid size of 2 mgd is
assumed for all system sizes.
Power
Power costs include power for NF feed pumps, instrumentation and controls and building
maintenance. The power requirements for process pumping and building maintenance are assumed to be
1.2 kWh/1,000 gallons and 0.6 kWh/1,000 gallons produced, respectively. Unit power cost of $0.076 per
kWh is used to estimate the power cost. The equation for power cost is given below.
Power Cost ($/yr) = 1.8 x 0.076 x Average Flow produced (mgd) x 1,000 x 365
Labor
Technical labor estimates include operation and maintenance of the membrane systems, including
labor associated with periodic data logging, repair of process equipment, sampling, and testing. No
additional managerial labor is assumed. A summary of labor hour assumptions is provided in Exhibit
3.30.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-58
-------
Exhibit 3.30 Summary of NF Technical Labor Assumptions
System Size (mgd)
<0.1
0.1 -< 1
1 -<5
5-<10
10-<100
••100
Technical Labor (hrs/week)
4
12
24
40
80
160
Source: USEPA, 2005.
POTW Surcharge
A fee of $0.00183 per 1000 gallons discharged to the sanitary sewer was assumed. This rate is
based upon data provided in the DPRA reports (1993a and 1993b). The discharge volume is based on an
average system recovery of 85 percent; therefore, the waste volume is 0.15 x average daily flow treated.
The surcharge for brine discharge can be calculated using the equation below.
Surcharge for Brine Discharge ($/yr) = 0.00183 x 0.15 x Average Flow produced (mgd) x 1000 x 365
Costs for concentrate handling include:
• Direct discharge of 15 percent of the feed flow to a sewer/storm/sanitary interceptor or ocean
outfall, located 500 feet or less from the NF plant (at 85 percent recovery, 15 percent would be
the brine stream).
• Assuming that the brine stream has adequate residual pressure, no additional pumping is
necessary.
3.7.7.4 Nanofiltration - Cost Summary and Equations
Total capital and O&M costs for each system size are presented in Exhibit 3.31. Exhibit A.9 of
Appendix A presents the linear regression cost coefficients A and B (described below) for all pertinent
flow ranges. Costs were assumed to vary linearly with flow between any two adjacent flow points.
Cost ($) = A + [B x Flow (in kgpd)], where:
A = Y-axis intercept of the linear regression for that flow range
B = Slope of the linear regression for that flow range
The data shown in Exhibit A.9 of Appendix A serve as inputs to the GWR EA Cost Model.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
3-59
-------
Exhibit 3.31 Estimated Costs for Nanofiltration Systems (continued)
Design Flow, mgd
Average Flow, mgd
0.007
0.0015
0.022
0.0054
0.037
0.0095
0.091
0.025
0.18
0.054
0.27
0.084
0.36
0.11
0.68
0.23
1
0.35
1.2
0.41
Unit Capital Cost Summary
Total Unit Capital Cost
Indirect Capital Costs
Piloting
Permitting
Land
Operator Training
Housing
Capital Cost After Multiplier
Subtotal Process Cost
Subtotal NF Equipment Cost
Pipes and Valves
Instrumentation and Controls
Cartridge Prefiltration
Acid and Anti-Scalent Feed Systems
System Feed Pumps
Nanofilter Membrane Elements
Membrane Skid with Filter Housing
Clean-ln-Place (CIP) System
Online Conductivity/pH and Turbidity Meters
Brine Discharge Pump (Not Included)
$52,107
$9,461
$1 ,000
$2,500
$853
$0
$5,108
$42,646
$25,537
$20,677
$2,068
$4,135
$1 ,654
$620
$2,585
$4,135
$4,135
$1 ,034
$5,169
$258
$69,454
$9,801
$1 ,000
$2,500
$1,193
$0
$5,108
$59,653
$35,720
$31,016
$3,102
$6,203
$2,481
$930
$3,877
$6,203
$6,203
$1,551
$5,169
$388
$86,801
$10,141
$1 ,000
$2,500
$1 ,533
$0
$5,108
$76,660
$45,904
$41 ,355
$4,135
$8,271
$3,308
$1,241
$5,169
$8,271
$8,271
$2,068
$5,169
$517
$156,293
$1 1 ,606
$1 ,000
$2,599
$2,894
$0
$5,113
$144,687
$86,639
$82,710
$8,271
$16,542
$6,617
$2,481
$10,339
$16,542
$16,542
$4,135
$5,169
$1,034
$223,250
$27,544
$10,000
$3,516
$3,914
$0
$10,114
$195,707
$117,190
$113,726
$11,373
$22,745
$9,098
$3,412
$14,216
$22,745
$22,745
$5,686
$5,169
$1,422
$316,569
$35,829
$10,000
$5,043
$5,615
$0
$15,171
$280,740
$168,108
$165,420
$16,542
$33,084
$13,234
$4,963
$20,677
$33,084
$33,084
$8,271
$5,169
$2,068
$357,931
$43,177
$10,000
$5,654
$6,295
$1,000
$20,228
$314,754
$188,475
$186,097
$18,610
$37,219
$14,888
$5,583
$23,262
$37,219
$37,219
$9,305
$5,169
$2,326
$664,969
$71,730
$10,000
$10,657
$11,865
$1 ,000
$38,208
$593,239
$355,233
$355,394
$35,539
$71 ,079
$28,432
$10,662
$44,424
$71 ,079
$71 ,079
$17,770
$5,169
$4,442
$914,766
$140,830
$60,000
$13,903
$7,739
$3,000
$56,188
$773,935
$463,434
$465,244
$46,524
$93,049
$37,219
$13,957
$58,155
$93,049
$93,049
$23,262
$5,169
$5,816
$1,083,344
$156,348
$60,000
$16,653
$9,270
$3,000
$67,426
$926,996
$555,087
$558,292
$55,829
$111,658
$44,663
$16,749
$69,787
$111,658
$111,658
$27,915
$5,169
$6,979
Annual O&M Summary
Total Annual O&M Cost
Acid, Anti-Sealant, Caustic Chemicals
Clean-in-Place Chemicals
NF Membrane Replacement
Cartridge Filter Replacement
Repair, Maintenance and Replacement
Process Monitoring (HPCs)
Power
Labor
Surcharge for Brine Discharge
(Sewer/Storm Drain/Brine Interceptor)
$6,909
$50
$50
$827
$30
$100
$1,167
$75
$4,460
$150
$7,937
$79
$50
$1,241
$30
$100
$1,167
$270
$4,460
$541
$9,025
$139
$50
$1 ,654
$30
$100
$1,167
$474
$4,460
$952
$13,703
$365
$91
$3,308
$30
$100
$1 ,253
$1 ,248
$4,803
$2,505
$29,539
$788
$197
$4,549
$39
$197
$1 ,253
$2,696
$14,408
$5,410
$37,904
$1,226
$307
$6,617
$61
$307
$1,338
$4,194
$15,438
$8,416
$43,223
$1 ,606
$401
$7,444
$80
$401
$1,338
$5,493
$15,438
$11,021
$70,725
$3,358
$839
$14,216
$168
$839
$1 ,338
$11,484
$15,438
$23,044
$112,309
$3,832
$1,277
$18,610
$2,555
$1,277
$1 ,338
$17,476
$30,876
$35,067
$126,572
$4,489
$1,496
$22,332
$2,993
$1,496
$1 ,338
$20,472
$30,876
$41 ,079
Land costs drop from a design flow of 0.68 mgd to 1 mgd due to a decrease in the land cost multiplier as we shift from one flow range to the
next (i.e., from 2% of capital cost for < 1 mgd to 1% of capital cost for 1 - < 10 mgd, see Exhibit 3.20).
Technology and Cost Document for the
Final Ground Water Rule
3-60
October 2006
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Exhibit 3.31 Estimated Costs for Nanofiltration Systems (continued on next page)
Design Flow, mgd
Average Flow, mgd
2
0.77
3.5
1.4
7
3
17
7.8
22
11
76
38
210
120
430
270
520
350
Unit Capital Cost Summary
Total Unit Capital Cost
Indirect Capital Costs
Piloting
Permitting
Land
Operator Training
Housing
Capital Cost After Multiplier
Subtotal Process Cost
Subtotal NF Equipment Cost
Pipes and Valves
Instrumentation and Controls
Cartridge Prefiltration
Acid and Anti-Scalent Feed Systems
System Feed Pumps
Nanofilter Membrane Elements
Membrane Skid with Filter Housing
Clean-ln-Place (CIP) System
Online Conductivity/pH and Turbidity Meters
Brine Discharge Pump (Not Included)
$2,023,265
$220,447
$60,000
$27,042
$18,028
$3,000
$112,376
$1,802,819
$901,409
$904,640
$90,464
$180,928
$72,371
$27,139
$113,080
$180,928
$180,928
$45,232
$10,339
$11,308
$3,412,330
$336,553
$60,000
$46,137
$30,758
$3,000
$196,658
$3,075,777
$1,537,888
$1,550,812
$155,081
$310,162
$124,065
$46,524
$193,851
$310,162
$310,162
$77,541
$10,339
$19,385
$6,761,659
$610,105
$60,000
$92,273
$61,516
$3,000
$393,317
$6,151,554
$3,075,777
$3,101,624
$310,162
$620,325
$248,130
$93,049
$387,703
$620,325
$620,325
$155,081
$20,677
$38,770
$15,488,708
$1,138,529
$60,000
$215,253
$71,751
$10,000
$781,525
$14,350,179
$7,175,090
$7,237,122
$723,712
$1,447,424
$578,970
$217,114
$904,640
$1,447,424
$1,447,424
$361,856
$46,524
$90,464
$19,905,140
$1,450,479
$60,000
$276,820
$92,273
$10,000
$1,011,385
$18,454,661
$9,227,331
$9,304,871
$930,487
$1,860,974
$744,390
$279,146
$1,163,109
$1,860,974
$1,860,974
$465,244
$62,032
$116,311
$57,703,935
$4,345,668
$60,000
$500,000
$266,791
$25,000
$3,493,876
$53,358,267
$26,679,134
$26,880,739
$2,688,074
$5,376,148
$2,150,459
$806,422
$3,360,092
$5,376,148
$5,376,148
$1,344,037
$201,606
$336,009
$130,061,681
$10,835,264
$60,000
$500,000
$596,132
$25,000
$9,654,132
$119,226,417
$59,613,208
$59,964,726
$5,996,473
$11,992,945
$4,797,178
$1,798,942
$7,495,591
$11,992,945
$11,992,945
$2,998,236
$547,954
$749,559
$266,180,394
$21,576,007
$60,000
$500,000
$1,223,022
$25,000
$19,767,985
$244,604,387
$122,302,193
$123,031,075
$12,303,108
$24,606,215
$9,842,486
$3,690,932
$15,378,884
$24,606,215
$24,606,215
$6,151,554
$1,116,585
$1,537,888
$319,911,447
$25,960,227
$60,000
$500,000
$1,469,756
$25,000
$23,905,470
$293,951,221
$146,975,610
$147,844,065
$14,784,406
$29,568,813
$11,827,525
$4,435,322
$18,480,508
$29,568,813
$29,568,813
$7,392,203
$1,349,206
$1,848,051
Annual O&M Summary
Total Annual O&M Cost
Acid, Anti-Sealant, Caustic Chemicals
Clean-in-Place Chemicals
NF Membrane Replacement
Cartridge Filter Replacement
Repair, Maintenance and Replacement
Process Monitoring (HPCs)
Power
Labor
Surcharge for Brine Discharge
(Sewer/Storm Drain/Brine Interceptor)
$205,817
$8,431
$2,810
$36,186
$5,621
$2,810
$2,739
$38,448
$31,624
$77,148
$343,298
$15,329
$5,110
$62,032
$10,219
$5,110
$2,813
$69,905
$32,510
$140,270
$710,894
$32,848
$10,949
$124,065
$21,899
$10,949
$5,626
$149,796
$54,184
$300,578
$1,780,761
$85,405
$28,468
$289,485
$56,936
$28,468
$12,659
$389,470
$108,368
$781,502
$2,429,844
$120,442
$40,147
$372,195
$80,295
$40,147
$16,879
$549,252
$108,368
$1,102,118
$7,914,024
$416,073
$138,691
$1,075,230
$277,382
$138,691
$54,857
$1,897,416
$108,368
$3,807,315
$23,845,168
$1,313,916
$437,972
$2,398,589
$875,944
$437,972
$149,100
$5,991,840
$216,736
$12,023,100
$52,975,344
$2,956,311
$985,437
$4,921,243
$1,970,874
$985,437
$362,344
$13,481,640
$260,083
$27,051,975
$68,097,181
$3,832,255
$1,277,418
$5,913,763
$2,554,836
$1,277,418
$437,833
$17,476,200
$260,083
$35,067,375
Technology and Cost Document for the
Final Ground Water Rule
3-61
October 2006
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3.8 Summary
Exhibit 3.32 shows a summary of all the costs derived in this chapter. The exhibit displays the
costs in terms of system size. The costs presented in this chapter are derived based on flow. The costs in
Exhibit 3.32 were derived using the coefficients displayed in Appendix A of this document and
multiplying those coefficients times the average flow for a given size category. The flows per size
category are listed in Exhibit 4.6 of the GWR EA.
Technology and Cost Document for the October 2006
Final Ground Water Rule 3-62
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Exhibit 3.32 Estimated Unit Costs of Treatment Corrective Actions for Source
Water Contamination
Corrective Action
System Size (Population Served)
<100
101-500
501-
1,000
1,001-
3,300
3,301-
10,000
10,001-
50,000
50,001-
100,000
100,001-
1 Million
>1 Million
Systems Adding Treatment
Chlorine gas feed
capital cost
Chlorine gas feed
annual O&M cost
Chlorine gas feed & storage
capital cost
Chlorine gas feed & storage
annual O&M cost
Hypochlorite feed
capital cost
Hypochlorite
annual O&M cost
Hypochlorite feed & storage
capital cost
Hypochlorite & storage
annual O&M cost
Chlorine Dioxide System
capital cost
Chlorine Dioxide
annual O&M cost
Chlorine Dioxide System
& storage capital cost
Chlorine Dioxide
& storage annual O&M cost
AnodicOxidant
capital cost
Anodic Oxidant
annual O&M cost
Anodic Oxidant & storage
capital cost
Anodic Oxidant & storage
annual O&M cost
Ozonation
capital cost
Ozonation
annual O&M cost
Nanofiltration
capital cost
Nanofiltration
annual O&M cost
$ 29,868
$ 6,192
$ 31,216
$ 6,192
$ 8,970
$ 1,585
$ 10,318
$ 1,585
N/A
N/A
N/A
N/A
$ 47,219
$ 2,911
$ 48,568
$ 2,911
N/A
N/A
$ 62,691
$ 7,520
$ 29,868
$ 6,227
$ 33,354
$ 6,227
$ 8,970
$ 2,076
$ 12,456
$ 2,076
N/A
N/A
N/A
N/A
$ 65,151
$ 5,471
$ 68,637
$ 5,471
N/A
N/A
$ 104,856
$ 10,253
$ 29,868
$ 6,307
$ 37,960
$ 6,307
$ 15,072
$ 4,180
$ 23,164
$ 4,180
$ 35,011
$ 15,261
$ 46,196
$ 16,251
$ 87,450
$ 7,480
$ 95,543
$ 7,480
$ 347,027
$ 55,668
$ 182,768
$ 20,140
$ 29,868
$ 6,456
$ 46,039
$ 6,456
$ 24,402
$ 6,582
$ 40,573
$ 6,582
$ 39,299
$ 16,897
$ 61,792
$ 17,720
$ 110,256
$ 9,791
$ 126,427
$ 9,791
$ 431,809
$ 59,028
$ 304,122
$ 37,037
$ 29,868
$ 6,857
$ 66,058
$ 6,857
$ 24,402
$ 7,326
$ 60,593
$ 7,326
$ 42,363
$ 17,901
$ 89,439
$ 18,733
$ 151,129
$ 12,855
$ 187,320
$ 12,855
$ 622,023
$ 60,789
$ 573,460
$ 63,670
$ 58,781
$ 16,951
$ 152,883
$ 16,951
$ 72,631
$ 7,558
$ 166,733
$ 7,558
$ 80,836
$ 19,878
$ 191,678
$ 20,392
$ 255,055
$ 17,479
$ 349,157
$ 17,479
$ 903,927
$ 63,718
$ 1,086,398
$ 133,397
$ 65,006
$ 18,197
$ 266,275
$ 18,197
$ 79,658
$ 7,909
$ 280,927
$ 7,909
$ 82,091
$ 21,705
$ 307,085
$ 22,257
$ 354,880
$ 22,181
$ 556,149
$ 22,181
$ 1,175,442
$ 67,004
$ 1,872,457
$ 194,361
$ 96,958
$ 21,854
$ 541,906
$ 21,854
$ 96,180
$ 19,177
$ 541,128
$ 19,177
$ 202,017
$ 25,983
$
$
$ 745,098
$ 38,439
$ 1,190,046
$ 38,439
$ 1,991,127
$ 87,225
$ 5,140,179
$ 541,543
$ 337,511
$ 61,772
$ 2,192,279
$ 61,772
$ 187,445
$ 135,513
$ 2,042,213
$ 135,513
$ 371,828
$ 59,412
$
$
$ 2,188,039
$ 179,932
$ 4,042,807
$ 179,932
$ 6,518,099
$ 253,317
$ 29,028,479
$ 3,873,384
Systems upgrading from less than 4-log to 4-log or greater
Add storage
capital cost
Increase dose - hypochlorination
annual O&M cost
Increase dose - chlorine gas
annual O&M cost
$ 1,349
$ 72
NA
$ 3,486
$ 179
NA
$ 8,093
$ 179
NA
$ 16,171
$ 195
NA
$ 36,191
$ 470
NA
$ 94,102
NA
$ 1,342
$ 201,269
NA
$ 2,108
$ 444,947
NA
$ 3,846
$ 1,854,768
NA
$ 17,838
Source: derived from Appendix A of this document and Exhibit 4.6 of the GWR EA
Technology and Cost Document for the
Final Ground Water Rule
3-63
October 2006
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4. Introduction to Best Management Practices
4.1 Introduction to Best Management Practices
This chapter provides information about ten different best management practices (BMPs) that
may prevent, eliminate, or reduce contamination to a water system. BMPs differ from treatment
technologies in that they don't inactivate or physically remove viruses in the water. Instead, the purpose
of a BMP is to protect the water source, well, or distribution system from contamination. Two categories
of BMPs are discussed in this chapter: system assessment and corrective actions.
System assessment BMPs help determine if systems require source water monitoring or
corrective action to address fecal contamination problems or significant deficiencies. This chapter
provides a background discussion and description often different BMPs, as well as a discussion of the
implementation issues and the advantages, disadvantages, and limitations associated with each BMP. The
BMPs discussed in this chapter are the following:
System Assessment
Sanitary survey (Section 4.2.1)
Hydrogeologic sensitivity assessment (Section 4.2.2)
Corrective Actions
Significant Deficiency Corrective Actions
• Replacing well seal (Section 4.3.1.1)
• Rehabilitation of an existing well (Section 4.3.1.2)
Source Water Corrective Actions
• Eliminating known sources of contamination (Section 4.3.2.1)
• Rehabilitation of an existing well (Section 4.3.2.2)
• Purchasing water from another utility (Section 4.3.2.3)
• Installation of new wells (Section 4.3.2.4)
Technology and Cost Document for the October 2006
Final Ground Water Rule 4-1
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Additional Corrective Actions1
Storage tank cover replacement or repair (Section 4.3.3.1)
• Cross-connection control/backflow prevention program (Section 4.3.3.2)
Installation of security measures (Section 4.3.3.3)
In addition, for systems that employ nontreatment corrective actions, the GWR EA Cost Model
assumes interim disinfection will be installed until the nontreatment corrective action begins. Information
on interim disinfection is provided in Section 2.2.4.
4.2 System Assessment BMPs
The system assessment BMPs are measures intended to identify conditions that might lead to
microbial contamination of drinking water and to identify the corrective actions that may prevent or
minimize this contamination. These system assessment BMPs include sanitary surveys and
hydrogeologic sensitivity assessments.
4.2.1 Sanitary Survey
4.2.1.1 Background and Description
A sanitary survey is an onsite review of the water source, facilities, equipment, operation and
maintenance of a public water system for the purpose of evaluating the adequacy of such source,
facilities, equipment, operation and maintenance for producing and distributing safe drinking water (40
CFR 141.2). Sanitary surveys allow a PWS to identify existing or potential sources of contamination.
Qualified persons from the Primacy agency or an independent third party perform sanitary surveys. They
should be trained and able to identify sanitary risks that may adversely affect the ability of a ground water
system to produce a safe, reliable, and adequate quality of potable water to the consumer (NETA, 2000).
4.2.1.2 Implementation Issues
The sanitary survey involves three phases: preparation, on-site inspection, and follow-up
activities.
Preparation
Before conducting or scheduling the on-site portion of a sanitary survey, the inspector must
review past sanitary survey reports, compliance records, water system plans, previous sampling results,
operating reports, and engineering studies. This pre-survey review provides an opportunity to examine
previous sampling and measurement results and allows the inspector to properly format the survey and
ensure that it addresses all issues. The inspector should also ensure that enough time is included to
evaluate whether the field equipment is in good repair. The water system operator must be contacted
beforehand to explain the purpose of the survey, schedule the survey, and discuss anything that needs to
occur before the inspector goes on-site.
1 Note, these additional corrective actions are included here for reference only. They are not used in the
GWR EA and are not included in the GWR compliance forecast.
Technology and Cost Document for the October 2006
Final Ground Water Rule 4-2
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On-site Inspection
There are eight essential elements involved in conducting an on-site sanitary survey. The on-site
sanitary survey includes visiting the water supply source and source facilities, pump stations, the
treatment plant, storage facilities, distribution system, and sampling locations. The eight essential
elements of a thorough sanitary survey include an evaluation of the following:
• Source (protection, physical components, and condition)
Treatment
• Distribution system
Finished water storage
Pumps/pump facilities and controls
Monitoring/reporting/data verification
Water system management/operations
Operator compliance with State requirements
Source (Protection, Physical Components, and Condition) - The source for a PWS is the first of
the multiple barriers to preventing waterborne disease. Objectives include evaluating the reliability and
quality of the source during the sanitary survey using available information and assessing the potential for
contamination from activities within the watershed, as well as from the physical components and
condition of the source facility.
To accomplish these objectives, the inspector needs to review available information such as
watershed control plans, source water assessment and protection plans, and/or wellhead protection plans
where they exist for a system. In the field, the inspector should discuss the water supply source with the
operator(s) and verify the information received from plans with field observations.
Treatment - In general, systems use different types of treatment units for different objectives.
The sanitary survey inspector will evaluate all water treatment processes at the water system, including
the design, operation, maintenance, and management of the water treatment plant to identify existing or
potential sanitary risks. The inspector should evaluate the treatment facilities and processes to determine
their ability to meet regulatory requirements and to provide an adequate supply of safe drinking water at
all times, including periods of high demand and poor source water quality. A sanitary survey of a
treatment facility should do the following:
Analyze all the distinct parts of the treatment process, including coagulation/flocculation,
sedimentation, filtration, disinfection, chemical feed systems, hydraulics, controls, safety
features and wastewater management, where applicable.
Review source water quality data that may impact the treatment process, such as turbidity,
pH, alkalinity, and water temperature.
Technology and Cost Document for the October 2006
Final Ground Water Rule 4-3
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Identify features that may pose a sanitary risk, such as cross-connections in the plant.
Review the criteria, procedures, and documentation used to comply with regulatory
requirements - adequate disinfection based on study of CT values (discussed in Chapter 2),
the turbidity of individual filters, the turbidity of the finished water, profiles of post-
backwash turbidity, etc. where applicable.
The inspector will need to review the design criteria, plant records, and compliance strategies in
addition to performing the actual inspection of the facility.
Distribution Systems - The water distribution system is the final link between the water source
and the consumer. The distribution system delivers drinking water produced at the water treatment
facility to the water system's customers. A typical water distribution system comprises miles of water
pipes constructed in a network which includes numerous valves, fire hydrants, pumps, storage tanks,
meters, and other appurtenances.
Water distribution systems consist of three elements: treated water storage facilities (e.g., ground
storage tanks, elevated storage tanks, standpipes, hydropneumatic tanks), pumping facilities (e.g., booster
pumps, piping, control, pump building), and the distribution lines (e.g., pipes, valves, fire hydrants,
meters). These components must be integrated in order to function as a comprehensive system that can
meet various schedules of demand. The water distribution system needs a thorough inspection to
determine whether the distribution system can provide a safe, reliable, and adequate supply of drinking
water to the customers. The objectives of surveying the water distribution system are to do the following:
Determine the potential for degradation of the water quality in the distribution system
Determine the reliability, quality, capacity, and vulnerability of the distribution system
• Ensure that the sampling and monitoring plan(s) for the system conform with the
requirements and adequately assess the quality of the water in the distribution system
To meet these objectives, the inspector will need to review the system configuration and
condition, design and construction criteria, system operation and maintenance records, and sampling and
monitoring plan(s) in addition to the actual inspection of the system.
Finished Water Storage - A survey of the storage facilities is critical to ensuring the availability
of safe water, and the adequacy of construction and maintenance of the facilities. Finished or treated
water storage facilities provide the following benefits to the operation of a public water system:
Allow treatment facilities to operate at or near uniform rates, even though the demands of the
system may greatly fluctuate
• Supply the peak and emergency needs of the system
• Maintain an adequate pressure in the system
• Provide extended contact or detention time for disinfection
• Serve as reservoirs for the blending and mixing of the water from different sources that may
have varying water qualities
Technology and Cost Document for the October 2006
Final Ground Water Rule 4-4
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The objectives of surveying the finished water storage facilities are to do the following:
Review the design and major components of storage to determine reliability, adequacy,
capacity, and vulnerability
• Evaluate the operation and maintenance and safety practices to determine that storage
facilities are reliable
Recognize any sanitary risks attributable to storage facilities (UFTREEO Center, 1998)
To accomplish these objectives, the inspector needs to review the information available from the
State's files for the system's finished water storage facilities. In the field, the inspector should perform an
inspection to verify the information and adequately assess facility conditions. The inspector may need to
climb storage tanks as part of the inspection (particularly if the water system uses elevated tanks and
standpipes). Since this can pose safety hazards, the inspector needs training in appropriate safety
procedures. In some cases, the results of a recent inspection by a qualified tank contractor may provide
the inspector with sufficient information without climbing the tank.
Pumps/Pump Facilities and Controls - Pumps and pump facilities are essential components of
all water systems. In addition to transporting water through the system, pump applications include
chemical feed systems, sludge removal, air compression, and sampling (UFTREEO Center, 1998).
Normally, there are several types of pumps used for an application. However, there are usually only one
or two types of pumps that will be the best fit for intended use. The objectives of surveying the
pumps/pump facilities and controls are to do the following:
• Review the design uses, and major components of water supply pumps
• Evaluate the operation and maintenance as well as safety practices to determine that water
supply pumping facilities are reliable
Recognize any sanitary risks attributable to water supply pumping facilities (UFTREEO
Center, 1998)
Monitoring/Reporting/Data Verification - For the water industry quality control consists of
monitoring the product (drinking water) from the source to the tap, with in-house as well as outside
laboratory testing for confirmation, as well as audits of existing data. A monitoring plan or program
provides the operator with data to assist in identifying potential problems and adjusting treatment
processes accordingly. It is important that all water systems create a water quality monitoring plan and
document monitoring results. Federal regulatory requirements, dictate the minimum scope of a water
quality monitoring plan. Primacy agencies may have more stringent requirements. The objectives of
surveying the water quality monitoring/reporting/data verification are to do the following:
Review the water quality monitoring plan of the PWS for conformance with regulatory
requirements
• Verify that the PWS is following the water quality monitoring plan by checking test results
• Verify that all in-house testing as well as equipment and reagents used conform to accepted
test procedures and quality
Technology and Cost Document for the October 2006
Final Ground Water Rule 4-5
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Verify the data submitted to the regulatory agency
Evaluate the procedures an operator follows to identify any problems with the process and
determine the changes needed to correct the problem
Water System Management/Operation - Management and staff need to work together to create
an environment allowing facilities to meet the goal of providing the best possible quality of drinking
water to the consumer. The objectives of surveying the water management/operation are to do the
following:
Review the water quality goals and evaluate any plan(s) (e.g. capital improvement plans) the
system has to accomplish the stated goals
• Identify and evaluate the basic information on the system, management, staffing, operations,
and maintenance
Review and evaluate the plan(s) for safety, emergency situations, maintenance, and security
to maintain system reliability
• Evaluate the system's revenue and budget and asset management for drinking water to
establish the long-term viability of meeting water quality goals (UFTREEO Center, 1998)
Operator Compliance with Primacy Agency Requirements - A system operator plays a critical
role in the reliable delivery of safe drinking water. Operator compliance with Primacy Agency
requirements includes Primacy agency-specific operation and maintenance requirements, training and
certification requirements, and overall competency with on-site observations of system performance.
Follow-up Activities - One of the most important components of the sanitary survey involves the
State writing the sanitary survey report after the on-site inspection is completed. The report should be
completed and presented in a timely manner and it should include the date of the survey, personnel
present during the survey, the findings of the survey, recommended or required improvements, and the
deadlines for completion. The report may assist in the planning of daily operations and long-term
projects.
PWSs with uncorrected significant deficiencies found during the sanitary survey must consult
with the primacy agency within 30 days or receiving written notice of the significant deficiency. Systems
must provide corrective actions, or be in compliance with State approved corrective action plan and
schedule (including State specified interim measures) within 120 days after the State notifies the system
of the significant deficiencies. Once the system receives State approval, the system must abide by the
State approved plan and schedule. The State agency should monitor progress towards correcting the
deficiencies to ensure that corrective actions are suitable and that the system corrects any sanitary
problems. Moreover, the State or Primacy Agency should determine whether the system needs to conduct
another sanitary survey before the next scheduled survey.
4.2.1.3 Advantages and Limitations
Some advantages of conducting sanitary surveys are as follows:
Identification of potential sources of contamination
Identification of potential problems with production, distribution, or treatment systems
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Evaluation of the system operations by an the Primacy agency or approved contractor reduces
bias in the evaluation
Provide information and assistance
Keep systems informed
The quantity and quality of the data available may limit the scope of the sanitary survey. The
survey in and of itself does not mitigate problems; rather, it identifies problems, and the utility must then
implement proper solutions to protect public health.
4.2.2 Hydrogeologic Sensitivity Assessment (HSA)
4.2.2.1 Background and Description
Hydrogeologic sensitivity to fecal contamination is not solely a function of the demonstrated
presence or absence of contaminant sources. Rather, the characteristics of the aquifer and overlying
geologic materials provide the basis of the sensitivity of a ground water source. Hydrogeologic
sensitivity also refers to the relative ease with which a contaminant applied on or near the surface can
migrate to the aquifer of interest. Hydrogeologic sensitivity depends on the hydrogeologic characteristics
of the area. For instance, karst, fractured rock, and gravel aquifers can be susceptible to microbial
contamination due to the large water-bearing openings found in these formations. A sensitivity
assessment is recommended in the Ground Water Rule. An assessment of a well's vulnerability may
include an evaluation of monitoring data as well as hydrogeology. HSAs also may include information
collected for a Source Water Assessment Program (SWAP).
4.2.2.2 Implementation Issues
HSAs are determined using hydrogeologic data from the surrounding area. The first step in an
HSA is to identify the aquifer from which the ground water system is drawing its water, where multiple
aquifers are present. This requires accurate well construction records that provide the depth of the well, a
record of the geologic strata encountered during the drilling, and an indication of the type and depth of
well casing, grouting, and well screen installed. The second step in assessing the sensitivity of a system is
to characterize the hydrogeology of the source aquifer (i.e., if the aquifer is in a karst, gravel, or fractured
bedrock). The next step is to determine if the aquifer has a hydrogeologic barrier that would prevent the
vertical movement of microbial contaminants from the surface into the aquifer. A confining layer, an
example of a hydrogeologic barrier, is a layer of impermeable material such as clay, that is sufficiently
thick and uniformly distributed to protect the underlying aquifer. The final step involves making a
determination of the sensitivity of the well based upon the available information and to document this
finding in an assessment report.
4.2.2.3 Advantages and Limitations
HSAs are beneficial because they can easily identify high-risk aquifers. However, as with
sanitary surveys, an HSA alone does not protect water quality. Additional monitoring, and in some cases,
implementation of corrective actions helps protect public water supplies in sensitive settings.
4.3 Corrective Action BMPs
The purpose of corrective action BMPs is to eliminate sources of microbial contamination that
may develop within drinking water supply wells, within storage tanks, within distribution systems, and
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with septic tank usage. The sanitary survey or source water monitoring will help identify the problem and
suggest the corrective action necessary. Corrective action BMPs costed for deficiencies identified during
a sanitary survey include: rehabilitating a well and replacing a well seal. Corrective action BMPs which
were costed for deficiencies identified during source water monitoring include eliminating known sources
of contamination, rehabilitating existing wells, purchasing water from another water system, and
installing new wells. Additional corrective actions which were not costed for the GWR EA but are
included for scoping the range of BMPs used include replacing or repairing a storage tank cover,
implementing a cross-connection control program, or installing security measures. The BMPs listed here
are not exhaustive but represent the range of BMPs available.
4.3.1 Significant Deficiency Correction Actions
4.3.1.1 Replacing a Well Seal
Background and Description
Contamination may enter a well through a leaking well seal. For example, runoff from nearby
agricultural fields can contaminate a well by entering through a leaking well seal. A well seal can leak
because of improper installation or deterioration due to age or corrosive conditions. Replacing the well
seal can correct a deficiency that could otherwise allow contamination from a nearby source to enter the
well.
Implementation Issues
If seal failure was caused by something other than age, care should be taken to ensure that the
conditions are improved so that failure does not occur again. Care should be taken in the installation of
the seal and materials should be chosen that are resistant to the conditions surrounding the well.
Advantages and Limitations
Replacing the well seal is a simple and relatively inexpensive way to reduce contamination, if the
source is a leaking seal. It does not eliminate the source of contamination, however, and contamination
can re-occur if the seal fails again.
4.3.1.2 Rehabilitation of Existing Wells
Background and Description
Old or poorly constructed wells can lead to contamination. Rehabilitating a well can often correct
the problems which lead to the contamination. Systems that rehabilitate existing wells do so to ensure the
integrity of the casing, screen, seal and pump and to prevent well contamination. The need for well
rehabilitation may result from poor design of the original well, the age of the existing well, or damage to
some well components. If a system must rehabilitate a well, it may need to repair or replace the well
screen, well casing, well seal, and/or the well pump.
The well casing should extend above ground, and the system should grade the ground surface at
the well site to drain surface water away from the well. If a system decides to replace the casing, it
should select the casing in accordance with applicable State or local criteria, codes, and regulations or
adopt other national criteria such as AWWA Standards (1997b) or the Ten States Standards (1997) if no
local regulations exist.
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Implementation Issues
The parties responsible for public water supply well installation can take an active role in
protecting the public from ground water contamination by constructing safe wells and by properly
abandoning old wells. Proper design and rehabilitation of well screens, casings, seals, and pumps may
require additional training of inspectors, engineers and contractors.
Advantages and Limitations
Proper rehabilitation of wells will greatly reduce the potential for well contamination by repairing
potential leaks in screens, casings, or seals. Rehabilitation of existing wells will also enhance yields and
water quality as well as contribute to extending the useful life of the well.
4.3.2 Source Water Corrective Actions
4.3.2.1 Eliminating Known Sources of Contamination
Background and Description
If the sanitary survey or source water monitoring is able to identify the sources of contamination
or significant deficiency, the PWS must provide corrective action. Potential sources of contamination
include the following:
• Septic tanks or cesspools
• Concentrated animal feeding operations
• Unlined or leaky sewage lagoons
• Secondary sewage treatment plant effluent used to recharge ground water or irrigate crop land
• Land application of raw or primary treated sewage or sewage sludge
• Ruptured, leaking sewage collection lines
• Improperly abandoned wells
Implementation Issues
It may be difficult to determine with certainty that a given source of contamination is responsible
for contaminating a well. The Primacy Agency may also require interim corrective actions to protect the
consumer from fecal contamination while the source of contaminant is being eliminated.
Once the system eliminates known sources of contamination, there will be a period of time over
which a well may continue to be contaminated. This will vary based upon the extent of contamination,
the time-of-travel to the well, and longevity of the contamination.
Advantages and Limitations
This corrective action is advantageous because it eliminates the known source of contamination
which may also act as a source for future contamination. This corrective action may be limited, however,
since it may require State or Federal intervention depending on the source(s) of contamination and
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negotiations with the responsible party(ies). That is, the contamination source may not be under the
direct, immediate control of the affected PWS. It may also be difficult to identify a specific source of
contamination.
4.3.2.2 Rehabilitating a Well
The need to rehabilitate a well may be identified by either sanitary survey or source water
monitoring. The issues brought up in either case are the same. See section 43.1.2 for a discussion of
well rehabilitation.
4.3.2.3 Purchasing Water from Another Utility
Background and Description
A water utility with fecally contaminated source water or a significant deficiency may decide to
purchase water from another utility if the costs of eliminating the contamination or treating the ground
water are prohibitively expensive. The system may purchase water in whole or for part of the system.
Implementation Issues
There are a number of issues that will impact a system's ability to purchase water, including the
proximity of a system to another system with the capacity available to sell water to the system. Systems
will need to construct a transmission main from the water seller to their distribution system and may need
to install booster pumps or pressure reducer valves to insure the system maintains a pressure plane. In
some cases, additional disinfection may be necessary.
Advantages and Limitations
A drinking water utility may achieve greater efficiency by combining with another utility. Small
systems, however, may find themselves limited by using another utility's water and no longer in control
of the quality of their product.
4.3.2.4 Installation of New Wells
Background and Description
When a PWS becomes fecally contaminated or certain significant deficiencies cannot be
corrected, and other corrective actions are not feasible nor effective, a new well may be necessary.
Systems site, design, and construct new wells in accordance with current applicable State and local
criteria, codes, or regulations. Systems choose well sites to ensure the avoidance of potential
contamination from known pollutant sources or contaminated aquifers, and systems construct wells so
that surface pollutants cannot reach the aquifer (Driscoll, 1986). Systems should ensure the new well is
not vulnerable to the source of contamination that affected the original well.
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Some of the parameters to consider when determining the site location, well construction methods, and
disinfection procedures, may include the following (Lehr et al, 1980):
Character of the local hydrogeology, such as: the slope of the ground surface, nature of the
soil and underlying material, thickness of the water-bearing formation, depth to the water
table, and slope of the water table
Location, boring logs, and construction details of all operating or abandoned local wells
Extent of recharge area likely to contribute water to the supply
Nature, distance, and direction to local sources of pollution
Possibility of surface drainage or flood water entering the supply
Methods used for protecting the supply against local sources of pollution
Well construction considerations (depth of the well, the casing diameter, wall thickness,
screen diameter and material, construction, the formation seal material, depth of placement,
annular thickness, and method of replacement)
• Surface protection of the well, including presence of sanitary well seal, height that casing
projects above ground, pumphouse floor, or flood level; protection of well from erosion and
animals, and pumphouse construction
• Pump capacity and pumping level
• Disinfection equipment, supervision, and test kits
In general, systems should locate a well on the highest ground whenever practical, and upgradient
from nearby or potential sources of pollution, such as sewage drainage fields, farm feed lots, or land
application of manure. The well casing should extend above ground, and the system should grade the
ground surface at the well site to drain surface water away from the well.
Construction of the well should utilize natural sanitary protection afforded by the geologic and
ground water conditions. Similarly, systems should design the well to avoid both natural and man-made
contamination and select casing and construct wells in accordance with applicable State or local
criteria/codes/regulations, or other criteria such as AWWA Standards (1997b) or the Ten States Standards
(1997) when no local regulations exist.
Implementation Issues
The parties responsible for public water supply well installation and siting can take an active role
in protecting the public from ground water contamination by properly constructing wells and making sure
that systems properly abandon old wells. Proper siting, design, and construction of wells will require
additional education of inspectors, engineers, well drillers, and contractors. System operators must know
the benefits of proper siting and construction in order to allocate sufficient resources to implement this
practice.
Advantages and Limitations
Use of a new well as opposed to correcting problems at an old well can be a more simple, less
costly option. New wells may, however, be subject to the same contamination sources as existing wells,
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so unless care is taken in siting construction of the new well, the original contamination problem could
appear in the new well. The time or costs to construct a new well may also serve as a limitation as well as
its proximity to other well(s) used by the PWS. Interim measures may need to be put in place until the
new well is installed.
4.3.3 Additional Corrective Actions
These corrective actions are examples of BMPs systems may use to address a significant
deficiency or fecal contamination. They may be identified by a sanitary survey or source water
monitoring. These corrective actions are included for comparison to the previous corrective actions
which were used in the GWR EA.
4.3.3.1 Storage Tank Cover Replacement or Repair
Background and Description
The sanitary survey may locate defects in the storage tank cover. Any damage to the storage tank
cover allows the potential for contamination of the finished water by birds, rodents, or other disease
vectors and can allow unauthorized human access.
Implementation Issues
Replacement or repair of a storage tank cover may require taking the tank out of service and
interruptions in water service. A system may need to clean and disinfect a repaired tank prior to returning
the tank to service. Interim measures may need to be undertaken until the storage tank cover is repaired
or replaced.
Advantages and Limitations
Replacing or repairing the storage tank cover will prevent any threats of future contamination as
it eliminates a pathway for contamination; however, this corrective action may not immediately address
existing contamination in the source water, unless the tank is drained and disinfected.
4.3.3.2 Cross-Connection Control and Backflow Prevention Program
Background and Description
Implementing a Cross-Connection Control and Backflow Prevention (CCCBFP) Program,
including the installation of backflow prevention assemblies and devices, can prevent the flow of non-
potable substances into the distribution system. When implementing the CCCBFP Program, the drinking
water system should adhere to applicable State and/or local criteria, codes, and/or regulations. Some
codes or regulations may include documenting installation procedures and the periodic testing of
backflow prevention assemblies.
CCCBFP can prevent the introduction of non-potable substances into the public water supply due
to backsiphonage or backpressure. Some common elements of a CCCBFP Program include:
• Installation of backflow prevention assemblies or devices at all high hazard service
connections.
• Elimination of cross-connections.
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Ensuring the inspection and testing of all backflow prevention assemblies or devices either by
the system or the hired contractor.
Providing administrative authority to implement the program.
Training and certification of personnel to maintain and administer the program and test
backflow prevention assemblies.
Implementation of proper record keeping and reporting procedures.
Education and notification of the public.
There are numerous potential cross-connection and backflow hazards. The degree of protection
from a cross-connection and backflow hazard should be commensurate with the degree of hazard. There
are five types of backflow prevention devices commonly used: air-gaps, double check valves, reduced-
pressure principle assemblies, atmospheric-vacuum breakers, and pressure-vacuum breakers (USEPA,
1989b).
To locate, eliminate, and prevent cross-connections and backflow, the program may identify who
has authority to enforce the codes and regulations covering hazard identification, and installation, testing,
and maintenance of backflow prevention assemblies or devices.
The legal basis for adoption of a CCCBFP Program ordinance varies by State. Water systems
should consult on this matter with the State Primacy Agency when developing a program (Salvato, 1982).
Implementation Issues
There are several issues involved in the process of developing and implementing a CCCBFP
Program. Both water suppliers and water users (utility customers) have a clearly implied responsibility to
protect the safety of water in the public distribution system and on their premises. The CCCBFP Program
should clearly define and establish responsibilities for each aspect of installation, maintenance, testing,
and inspection of control devices as well as enforcement of the plan (Salvato, 1982).
A building's piping system may require protection in accordance with the requirements of the
local drinking water, health, plumbing, or construction authority. The water distribution systems of some
premises served by PWSs, such as hotels, hospitals, and industrial plants, can be quite complex.
Contaminated backflow from these premises may result from backpressure or backsiphonage where
cross-connections are established between appliances and equipment containing non-potable substances
and the potable water supply. CCCBFP Programs usually require the installation of backflow prevention
devices or assemblies at water service connections where potentially hazardous conditions exist (AWWA,
1990b; EPA, 1989b). AWWA Manual M14 (1990b) lists potential CCCBFP Program elements, and
backflow prevention devices and assemblies to use in those cases where local authorities do not regulate
these controls.
Advantages and Limitations
CCCBFP reduce the potential for the introduction of pathogenic microbes and toxic chemicals in
the distribution system. Additional advantages of an effective CCCBFP Program include eliminating
transient contamination events resulting from pressure fluctuations that may otherwise go undetected and
minimizing the introduction of corrosive materials. Potential disadvantages may also exist, such as the
potential for jurisdictional problems where overlaps exist.
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4.3.3.3 Installation of Security Measures
Background and Description
Systems may need to install security measures in circumstances where the sanitary survey or on-
site inspection reveals vandalism or security breaches. Measures that a water system may take to correct
security breaches include installing a fence or locking buildings to restrict access to the system. In
addition, alarms and cameras may be used to detect security breaches.
Implementation Issues
Water systems should prioritize their security measures and concentrate on the most vulnerable
parts of the system, such as unstaffed facilities (e.g., finished water storage tanks). An important
implementation issue is the extent of the water system that needs to be secured. This would depend on
how widely spread the system/facility is, the number and complexity of the treatment trains, the extent of
the watershed, the distance of the treatment plant from the influent wells, accessibility of the distribution
system to the public, etc. Possible security measures include locked fence enclosures and employing a
full time, on-site security staff.
Advantages and Limitations
Installing security measures can increase the public's confidence in the protection of their
drinking water and indeed can afford substantial protection against vandalism that might result in
contamination of the water. However, security measures are not always foolproof or absolute in
combating vandalism or security breaches.
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5. Costs for Best Management Practices
This chapter describes the costs incurred for the best management practices (BMPs) identified
and discussed in Chapter 4. Because in some ways BMPs are a reasonable and sound way to minimize
the need for installing some more expensive corrective actions, public water systems (PWSs) practice one
form or another of BMPs regardless of rules and regulations. EPA does not expect systems with existing
disinfection treatment to abandon that practice in favor of fully implementing BMPs.
Costs of the BMPs provided in this chapter are intended to be used as estimates. Where
appropriate, the costs of these BMPs presented are per unit of number of wells in a system. This chapter
includes costs on the following BMPs:
System Assessment
• Sanitary survey (Section 5.2.1)
• Hydrogeologic sensitivity assessment (Section 5.2.2)
Corrective Actions
Significant Deficiency Corrective Actions (Section 5.3.1)
Replacing well seal (Section 5.3.1.1)
Rehabilitation of existing wells (Section 5.3.1.2)
Source Water Corrective Actions (Section 5.3.2)
• Eliminating known sources of contamination (Section 5.3.2.1)
• Rehabilitation of existing wells (Section 5.3.2.2)
• Purchasing water from another utility (Section 5.3.2.3)
• Installation of new wells (Section 5.3.2.4)
Additional Corrective Actions1 (Section 5.3.3)
• Storage tank cover replacement or repair (Section 5.3.3.1)
• Cross-connection control/backflow prevention program (Section 5.3.3.2)
• Installation of security measures (Section 5.3.3.3)
1 Note, these additional corrective actions are included here for reference only. They are not used in the
GWR EA and are not included in the GWR compliance forecast.
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In addition, for systems that employ nontreatment corrective actions, the GWR EA Cost Model
assumes interim disinfection will be installed until the nontreatment corrective action begins. Cost
information on interim disinfection is provided in Chapter 3, Section 3.7.3.
5.1 Introduction
The estimated costs for carrying out each of the various system assessment and corrective action
BMPs that were described in Chapter 4 are based upon specific components of each BMP. Those
components are identified and discussed in the sections that follow. Costs for all of the BMPs are highly
dependent upon labor and on the number of wells at a particular ground water system implementing a
BMP.
To remain consistent with the unit costs estimates presented in Chapter 3, the corrective actions
cost estimates have been updated to 2003 dollars by applying the appropriate Building Cost Index (BCI)
(i.e., [BCI Avg 2003 - BCI Avg. 1998] = 3693 - 3391 = 1.089) (www.enr.comV
Exhibit 5.1 presents a summary of the labor rates for various types of personnel who carry out
aspects of one or more of the BMP components. These rates include overhead as well as individual
wages. The R.S. Means (1998) labor costs were updated to 2003 dollars using the Employment Cost
Index (ECI) available from the website "http:\\www.bls.gov". Exhibit 5. Ib includes labor costs for
system operators.
Exhibit 5.2 provides a summary of the number of wells per system in the various population
categories.
Exhibit 5.1a State Labor Rate Components of BMPs
Cost Element
Staff Hydrogeologist
Field Engineer
Unit Cost
Hour
Hour
2003 Dollars
$ 27.10
$ 37.34
Source
R.S. Means1
R.S. Means1
1 R.S. Means 1998 costs updated to 2003 dollars using ECI.
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Exhibit 5.1 b PWS Operator Labor Rate Components of BMPs
Size of PWS
25- 100
101 -500
500 - 3,300
3,301 - 10,000
10,001 - 100,000
> 100,000
Unit Cost
Hour
Hour
Hour
Hour
Hour
Hour
2003 Dollars
$ 21.44
$ 23.09
$ 24.74
$ 25.34
$ 26.05
$ 31.26
Source
Labor Costs for National
Drinking Water Rules (USEPA
2003)
Labor Costs for National
Drinking Water Rules
(USEPA, 2003)
Labor Costs for National
Drinking Water Rules
(USEPA, 2003)
Labor Costs for National
Drinking Water Rules
(USEPA, 2003)
Labor Costs for National
Drinking Water Rules
(USEPA, 2003)
Labor Costs for National
Drinking Water Rules
(USEPA, 2003)
Source: GWR EA, Ex 6.1
Exhibit 5.2 Average Number of Wells per Community Water System
Population Served
1 00 or fewer
101-500
501-1,000
1,001-3,300
3,301-10,000
10,001-50,000
50,001-100,000
Greater than 100,000
Number of Wells
per System
1.5
2.0
2.3
3.1
4.6
9.8
16.1
49.9
Source: USEPA, 2001.
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5.2 System Assessment
5.2.1 Sanitary Survey
States or designated agents perform sanitary surveys, however, systems will incur costs to
accompany State inspectors during a review of the treatment plant and the distribution system, as well as
to prepare for the sanitary survey, and to review and discuss the sanitary survey report. The State labor
costs for a Sanitarian are assumed to be equivalent to that of a Field Engineer (at $37.34 per hour, in 2003
dollars). Exhibits 5.3a and 5.3b indicate the sanitary survey components and State labor costs for a
sanitary survey. The level of effort for systems that have treatment installed is greater than systems with
no treatment. Therefore separate costs are calculated for systems with and without treatment. Sanitary
surveys will increase either in scope or frequency under the GWR for some systems. Some systems will
incur the full cost for conducting additional sanitary surveys beyond their current requirements. Other
systems will only need to add additional elements to their existing sanitary surveys. It is assumed that the
additional effort will be half of the effort required to perform a full sanitary survey and that 10 percent of
systems will only be required to perform an incremental survey. This leads to a unit cost for incremental
surveys which is 0.05 times the cost for a full survey.
Hours are included for the engineer to review the plant and distribution system, to enter the data,
write, document and review the report. All burden estimates are based on consultations with EPA, State,
and Industry professionals with significant experience conducting sanitary surveys on ground water
systems.
The costs outlined in Exhibits 5.4a and 5.4b indicate the system costs for a sanitary survey. As
discussed in Section 4.2.1, the system should prepare and organize data for the survey. EPA assumes that
the system operator would accompany the engineer to the well and review the report. Costs are based on
the unit labor cost of a plant operator. As with the States costs, both unit costs for full surveys and
weighted unit costs for incremental survey are provided.
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Exhibit 5.3a Estimated State Costs for a Sanitary Survey for Systems with
Treatment (2003$)
System Size
(Population
Served)
Labor
Cost
(per hour)
A
Review/
Inspect
Wells
B
Review/
Inspect
Treatment
C
Review/
Inspect
Distribution
System
D
Report
Documenta
tion/
File Review
E
Report
Develop
ment
F
Data Entry
G
Report
Review and
Discussion
w/PWS
H
Travel
I
Total
Unit Burden
(hours)
J=sum(B-l)
Unit Cost
(Full Survey)
K=A*J
Community Water Systems (CWSs)
<100
101-500
501-1,000
1,001-3,300
3,301-1 OK
10,001 -50K
50,001 -100K
100.000-1M
> 1,000, 000
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
1.1
1.2
1.5
2.2
2.7
3.7
9.0
15.0
24.0
0.8
0.8
1.1
1.3
1.6
2.0
3.0
8.0
10.0
1.2
1.2
1.7
2.9
3.6
4.3
12.0
24.0
36.0
2.3
2.3
2.6
3.4
3.7
5.3
12.0
18.0
18.0
5.7
5.8
7.4
8.8
9.6
10.1
12.0
18.0
18.0
0.8
0.8
0.8
1.2
1.3
1.4
2.0
3.0
4.0
1.1
1.1
1.2
1.4
1.8
1.9
3.0
3.0
4.0
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
14.8
14.9
18.0
22.8
25.9
30.3
54.8
90.8
115.8
$ 551
$ 557
$ 671
$ 851
$ 967
$ 1,132
$ 2,044
$ 3,389
$ 3,389
Nontransient Noncommunity Water Systems (NTNCWSs)
<100
101-500
501-1,000
1,001-3,300
3,301-1 OK
1 0,001 -50K
50,001 -100K
100.000-1M
> 1,000, 000
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
NA
1.0
1.0
1.1
1.1
1.5
1.3
1.5
8.0
NA
0.8
0.8
0.9
1.1
1.5
0.8
0.8
1.0
NA
1.0
1.1
1.3
1.2
1.7
1.8
2.3
10.0
NA
1.9
2.0
2.1
2.1
2.2
2.5
2.5
8.0
NA
5.1
5.3
6.5
6.2
6.7
5.0
5.0
10.0
NA
1.0
1.0
0.8
0.8
0.8
0.8
0.8
1.0
NA
1.3
1.3
1.2
1.3
1.5
1.3
1.3
1.5
NA
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
13.8
14.2
15.6
15.6
17.6
15.0
15.8
41.3
NA
$ 515
$ 531
$ 583
$ 581
$ 657
$ 560
$ 588
$ 1,540
NA
Transient Noncommunity Water Systems (TNCWSs)
<100
101-500
501-1,000
1,001-3,300
3,301-1 OK
1 0,001 -50K
50,001 -100K
100.000-1M
> 1,000, 000
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
NA
0.7
0.7
1.0
0.9
1.2
0.8
1.3
8.0
NA
0.6
0.6
0.8
1.0
1.3
0.5
0.5
1.0
NA
0.6
0.6
1.0
0.9
1.2
1.3
1.3
10.0
NA
1.5
1.5
1.8
1.7
1.5
1.3
1.3
3.0
NA
5.1
5.3
5.8
4.7
5.2
3.8
3.8
8.0
NA
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.5
NA
0.9
0.9
0.9
1.1
1.2
0.8
0.8
1.0
NA
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
11.9
12.1
13.9
12.9
14.1
10.8
11.3
33.3
NA
$ 443
$ 452
$ 518
$ 480
$ 526
$ 401
$ 420
$ 1,242
NA
Weighted Unit Cost
(Incremental Survey)
L=0.05*K
$ 28
$ 28
$ 34
$ 43
$ 48
$ 57
$ 102
$ 169
$ 169
$ 26
$ 27
$ 29
$ 29
$ 33
$ 28
$ 29
$ 77
NA
$ 22
$ 23
$ 26
$ 24
$ 26
$ 20
$ 21
$ 62
NA
Notes: Weighted unit costs equal 5% of the unit costs.
text discussion).
This factor accounts for 50% effort for an incremental survey and 10% of systems that do not already comply with rule requirements (see
Technology and Cost Document for the
Final Ground Water Rule
October 2006
5-5
-------
Exhibit 5.3b Estimated State Costs for a Sanitary Survey for Systems without
Treatment (2003$)
System Size
(Population
Served)
Labor
Cost
(per hour)
A
Review/
Inspect
Wells
B
Review/
Inspect
Distribution
System
C
Report
Documenta
tion/
File Review
D
Report
Develop
ment
E
Data Entry
F
Report
Review and
Discussion
w/PWS
G
Travel
H
Total
Unit Burden
(hours)
l=sum(B-H)
Unit Cost
(Full Survey)
J=A*I
Community Water Systems (CWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
1 0,001 -50K
50.001-100K
1 00,000-1 M
>1, 000,000
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
1.1
1.2
1.5
2.2
2.7
3.7
9.0
15.0
24.0
1.2
1.2
1.7
2.9
3.6
4.3
12.0
24.0
36.0
2.3
2.3
2.6
3.4
3.7
5.3
12.0
18.0
18.0
5.7
5.8
7.4
8.8
9.6
10.1
12.0
18.0
18.0
0.8
0.8
0.8
1.2
1.3
1.4
2.0
3.0
4.0
1.1
1.1
1.2
1.4
1.8
1.9
3.0
3.0
4.0
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
13.9
14.1
16.9
21.5
24.3
28.3
51.8
82.8
105.8
$ 521
$ 526
$ 631
$ 803
$ 909
$ 1,058
$ 1,932
$ 3,090
$ 3,090
Nontransient Noncommunity Water Systems (NTNCWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
1 0,001 -50K
50.001-100K
1 00,000-1 M
>1, 000,000
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
NA
1.0
1.0
1.1
1.1
1.5
1.3
1.5
8.0
NA
1.0
1.1
1.3
1.2
1.7
1.8
2.3
10.0
NA
1.9
2.0
2.1
2.1
2.2
2.5
2.5
8.0
NA
5.1
5.3
6.5
6.2
6.7
5.0
5.0
10.0
NA
1.0
1.0
0.8
0.8
0.8
0.8
0.8
1.0
NA
1.3
1.3
1.2
1.3
1.5
1.3
1.3
1.5
NA
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
NA
13.0
13.5
14.8
14.5
16.1
14.3
15.0
40.3
NA
$ 487
$ 503
$ 551
$ 540
$ 601
$ 532
$ 560
$ 1,503
NA
Transient Noncommunity Water Systems (TNCWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
1 0,001 -50K
50.001-100K
1 00,000-1 M
>1, 000,000
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
$ 37.34
NA
0.7
0.7
1.0
0.9
1.2
0.8
1.3
8.0
NA
0.6
0.6
1.0
0.9
1.2
1.3
1.3
10.0
NA
1.5
1.5
1.8
1.7
1.5
1.3
1.3
3.0
NA
5.1
5.3
5.8
4.7
5.2
3.8
3.8
8.0
NA
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.5
NA
0.9
0.9
0.9
1.1
1.2
0.8
0.8
1.0
NA
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
NA
11.3
11.5
13.0
11.9
12.8
10.3
10.8
32.3
NA
$ 421
$ 431
$ 487
$ 443
$ 476
$ 383
$ 401
$ 1,204
NA
Weighted Unit Cost
(Incremental Survey)
K=0.05*J
$ 26
$ 26
$ 32
$ 40
$ 45
$ 53
$ 97
$ 155
$ 155
$ 24
$ 25
$ 28
$ 27
$ 30
$ 27
$ 28
$ 75
NA
$ 21
$ 22
$ 24
$ 22
$ 24
$ 19
$ 20
$ 60
NA
Notes: Weighted unit costs equal 5% of the unit costs. This factor accounts for 50% effort for an incremental survey and 10% of systems that do not already comply with rule
requirements (see text discussion).
Technology and Cost Document for the
Final Ground Water Rule
October 2006
5-6
-------
Exhibit 5.4a Estimated System Costs for Performing a Sanitary Survey for
Systems with Treatment (2003$)
System Size
(Population
Served)
Labor
Cost
(per hour)
A
Review/
Inspect
Wells
B
Review/
Inspect
Treatment
C
Review/
Inspect
Distribution
System
D
Report
Rev lew and
Discussion
w/ State
E
Total
Unit Burden
(hours)
F=sum(B-E)
Unit Cost
(Full Survey)
G=A*F
Community Water Systems (CWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
10.001-50K
50.001-100K
100, 000-1 M
>1, 000,000
$ 21.44
$ 23.09
$ 24.74
$ 24.74
$ 30.51
$ 31.08
$ 31.08
$ 35.25
$ 35.25
1.1
1.2
1.5
2.2
2.7
3.7
9.0
15.0
24.0
0.8
0.8
1.1
1.3
1.6
2.0
3.0
8.0
10.0
1.2
1.2
1.7
2.9
3.6
4.3
12.0
24.0
36.0
1.1
1.1
1.2
1.4
1.8
1.9
3.0
3.0
4.0
4.3
4.3
5.4
7.7
9.6
11.8
27.0
50.0
74.0
$ 92
$ 99
$ 135
$ 191
$ 291
$ 368
$ 839
$ 1,762
$ 1,762
Nontransient Noncommunity Water Systems (NTNCWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
10.001-50K
50.001-100K
100, 000-1 M
>1, 000,000
$ 21.44
$ 23.09
$ 24.74
$ 24.74
$ 30.51
$ 31.08
$ 31.08
$ 35.25
$ 35.25
1.0
1.0
1.1
1.1
1.5
1.3
1.5
8.0
NA
0.8
0.8
0.9
1.1
1.5
0.8
0.8
1.0
NA
1.0
1.1
1.3
1.2
1.7
1.8
2.3
10.0
NA
1.3
1.3
1.2
1.3
1.5
1.3
1.3
1.5
NA
4.0
4.2
4.5
4.7
6.2
5.0
5.8
20.5
NA
$ 87
$ 96
$ 110
$ 116
$ 188
$ 155
$ 179
$ 723
NA
Transient Noncommunity Water Systems (TNCWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
10.001-50K
50.001-100K
100, 000-1 M
>1, 000, 000
$ 21.44
$ 23.09
$ 24.74
$ 24.74
$ 30.51
$ 31.08
$ 31.08
$ 35.25
$ 35.25
0.7
0.7
1.0
0.9
1.2
0.8
1.3
8.0
NA
0.6
0.6
0.8
1.0
1.3
0.5
0.5
1.0
NA
0.6
0.6
1.0
0.9
1.2
1.3
1.3
10.0
NA
0.9
0.9
0.9
1.1
1.2
0.8
0.8
1.0
NA
2.7
2.7
3.7
3.9
4.8
3.3
3.8
20.0
NA
$ 59
$ 63
$ 92
$ 96
$ 147
$ 101
$ 117
$ 705
NA
Weighted
Unit Cost
(Incremental Survey)
H=0.05*G
$ 5
$ 5
$ 7
$ 10
$ 15
$ 18
$ 42
$ 88
$ 88
$ 4
$ 5
$ 6
$ 6
$ 9
$ 8
$ 9
$ 36
NA
$ 3
$ 3
$ 5
$ 5
$ 7
$ 5
$ 6
$ 35
NA
Notes:
Weighted unit costs equal 5% of the unit costs. This factor accounts for 50% effort for an incremental survey and
10% of systems that do not already comply with rule requirements (see text discussion).
Technology and Cost Document for the
Final Ground Water Rule
5-7
October 2006
-------
Exhibit 5.4b Estimated System Costs for Performing a Sanitary Survey for
Systems without Treatment (2003$)
System Size
(Population
Served)
Labor
Cost
(per hour)
A
Review/
Inspect
Wells
B
Review/
Inspect
Distribution
System
C
Report
Review and
Discussion
w/ State
D
Total
Unit Burden
(hours)
E=sum(B-D)
Unit Cost
(Full Survey)
F=A*E
Community Water Systems (CWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
1 0,001 -50K
50,001 -100K
1 00,000-1 M
>1, 000,000
$ 21.44
$ 23.09
$ 24.74
$ 24.74
$ 30.51
$ 31.08
$ 31.08
$ 35.25
$ 35.25
1.1
1.2
1.5
2.2
2.7
3.7
9.0
15.0
24.0
1.2
1.2
1.7
2.9
3.6
4.3
12.0
24.0
36.0
1.1
1.1
1.2
1.4
1.8
1.9
3.0
3.0
4.0
3.5
3.5
4.4
6.4
8.0
9.8
24.0
42.0
64.0
$ 75
$ 81
$ 108
$ 159
$ 243
$ 305
$ 746
$ 1,480
$ 1,480
Nontransient Noncommunity Water Systems (NTNCWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
1 0,001 -50K
50,001 -100K
1 00,000-1 M
>1, 000,000
$ 21.44
$ 23.09
$ 24.74
$ 24.74
$ 30.51
$ 31.08
$ 31.08
$ 35.25
$ 35.25
1.0
1.0
1.1
1.1
1.5
1.3
1.5
8.0
NA
1.0
1.1
1.3
1.2
1.7
1.8
2.3
10.0
NA
1.3
1.3
1.2
1.3
1.5
1.3
1.3
1.5
NA
3.3
3.4
3.6
3.6
4.7
4.3
5.0
19.5
NA
$ 70
$ 79
$ 89
$ 89
$ 142
$ 132
$ 155
$ 687
NA
Transient Noncommunity Water Systems (TNCWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
1 0,001 -50K
50,001 -100K
1 00,000-1 M
>1, 000,000
$ 21.44
$ 23.09
$ 24.74
$ 24.74
$ 30.51
$ 31.08
$ 31.08
$ 35.25
$ 35.25
0.7
0.7
1.0
0.9
1.2
0.8
1.3
8.0
NA
0.6
0.6
1.0
0.9
1.2
1.3
1.3
10.0
NA
0.9
0.9
0.9
1.1
1.2
0.8
0.8
1.0
NA
2.2
2.2
2.9
2.9
3.5
2.8
3.3
19.0
NA
$ 46
$ 50
$ 72
$ 72
$ 107
$ 85
$ 101
$ 670
NA
Weighted
Unit Cost
(Incremental Survey)
G=0.05*F
$ 4
$ 4
$ 5
$ 8
$ 12
$ 15
$ 37
$ 74
$ 74
$ 4
$ 4
$ 4
$ 4
$ 7
$ 7
$ 8
$ 34
NA
$ 2
$ 2
$ 4
$ 4
$ 5
$ 4
$ 5
$ 33
NA
Notes:
Weighted unit costs equal 5% of the unit costs. This factor accounts for 50% effort for an incremental survey and 10% of
systems that do not already comply with rule requirements (see text discussion).
Technology and Cost Document for the
Final Ground Water Rule
October 2006
5-6
-------
5.2.2 Hydrogeologic Sensitivity Assessment (HSA)
Similar to the sanitary survey, it is assumed that HSAs are conducted primarily by the Primacy
agency with assistance from the systems. The assistance provided by the systems is expected to be small
and negligible in terms of cost. The HSA is a voluntary approach recommended by EPA but not required
by the GWR. Costs calculated here are not used to calculate rule costs but shown for demonstrative
purposes. Exhibit 5.5 presents the cost components for a State inspector to perform a HSA. The costs
assume 2 hours of labor per well. The labor rate for the hydrogeologist is $27.10 per hour (in 2003
dollars). The cost per entry point is then determined by dividing by the number of entry points. In some
cases where an entry point is determined to be sensitive, States will also make barrier determinations.
The number of hours for a barrier determination are assumed to equal those to perform the HSA.
Technology and Cost Document for the October 2006
Final Ground Water Rule 5-9
-------
Exhibit 5.5 Estimated State Costs of a Hydrogeologic Sensitivity Assessment
(2003$)
System Size
(Population Served)
HSAs
Labor
Cost
(per
hour)
A
Conduct
HSA Wells HSA
Labor per (hours/
per Well System system)
B C D = B*C
Entry
Points
per
System
E
Conduct
HSA
(hours/
entry point)
F = DIE
Unit
Cost
G = A*F
Community Water Systems (CWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
10,001-SOK
50.001-100K
100,001-1 Million
> 1 Million
Total
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
2 1.5 3.0
2 2.0 4.0
2 2.3 4.6
2 3.1 6.2
2 4.6 9.2
2 9.8 19.6
2 16.1 32.2
2 49.9 99.8
2 49.9 99.8
1.3
1.6
2.0
2.4
3.2
5.6
11.3
12.4
11.4
2.3
2.5
2.3
2.6
2.9
3.5
2.8
8.0
8.8
$ 63
$ 68
$ 62
$ 70
$ 78
$ 95
$ 77
$ 218
$ 237
Nontransient Noncommunity Water Systems (NTNCWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
10,001-SOK
50.001-100K
100,001-1 Million
> 1 Million
Total
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
NA
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
NA
2.3
2.5
2.3
2.6
2.9
3.5
2.8
8.0
NA
$ 63
$ 68
$ 62
$ 70
$ 78
$ 95
$ 77
$ 218
NA
Transient Noncommunity Water Systems (TNCWSs)
<100
101-500
501-1,000
1,001-3,300
3.301-10K
10,001-SOK
50.001-100K
100,001-1 Million
> 1 Million
Total
All Total
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
$ 27.10
NA
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
NA
2.3
2.5
2.3
2.6
2.9
3.5
2.8
8.0
NA
$ 63
$ 68
$ 62
$ 70
$ 78
$ 95
$ 77
$ 218
NA
Notes: Detail may not add to totals due to independent rounding.
NA Not applicable (no NCWSs of this size category).
Sources: (A) Labor rates for staff hydrogeologist from Exhibit 5.1
(B) Labor for conducting assessment includes time for travel, records review, wellhead inspection, and
report preparation.
(C) Wells per system from US EPA Drinking Water Baseline Handbook (2001).
(E) Entry points per system derived from 1995 CWSS.
Labor hours per entry point for NTNCWSs and TNCWSs based on EPA estimate of hours per entry point
for CWSs.
Technology and Cost Document for the
Final Ground Water Rule
5-10
October 2006
-------
5.3 Corrective Actions
This section provides estimates of costs for the corrective action BMPs that systems may
undertake. A summary of the costs and assumptions used to determine costs accompanies each action.
The total cost estimates include capital costs (construction costs), and where applicable, operation and
maintenance (O&M) costs. Costs depend largely on site-specific conditions and may vary depending on
the individual components employed and the specific population category.
5.3.1 Significant Deficiency Corrective Actions
5.3.1.1 Replacing a Well Seal
The total cost for a replacing a well seal including parts and installation is $3,300 for a 6-inch
diameter well according to 1998 RS Means. Updating these costs to 2003 dollars gives $3,627.
5.3.1.2 Rehabilitation of Existing Wells
The cost components for rehabilitating an existing well include replacing the well screen, well
casing, well surface seal, testing the well pump, and well disinfection. Exhibit 5.6 presents the estimated
cost to rehabilitate a 6-inch diameter community water system (CWS) well. The estimated individual cost
components are material, labor, and equipment costs include replacing the well screen, steel well casing,
surface seal, testing the well pump, and well disinfection. The casing was assumed to be 100 feet in
length. The estimated total cost for rehabilitating a community well is $11,986 (in 2003 dollars). In
addition to the items costed out in Exhibit 5.6, the well pump may also require replacement as part of the
rehabilitation efforts. Exhibit 5.7 presents the cost for removing the old pump, and purchasing and
installing a new pump.
Technology and Cost Document for the October 2006
Final Ground Water Rule 5-11
-------
Exhibit 5.6 Estimated Costs for Rehabilitating Community Water
System Wells (2003$)
Cost Component
Well Screen2
Steel Well Casing3
Surface Seal4
Well Test Pump, Install & Remove5
Well Disinfection6
Permitting costs7
Total (1998$)8
Total (2003$)
Total, Including Overhead and
Profit1
$2,100
$1,200
$3,300
$3,400
$700
$300
$11,000
$11,986
1 Costs include rental of equipment as well as operating costs for equipment under normal use. The
operating costs include parts and laborfor routine servicing and repairs. Total cost includes overhead
and profit as reported by R.S. Means (1997a) rounded to the nearest $100.
2 The well screen is assumed to be stainless steel and 20-feet in length and 6-inch diameter.
3 Well casing applied to 100 feet of the well. Casing is assumed to be steel and weigh 8.75 pounds
per foot.
4 The surface seal is a one-time cost.
5 Well test pump, install, and remove is a one-time cost.
6 Well disinfection is a one-time cost.
7 Permitting costs based on 3 percent of capital.
8 Source: R.S. Means, 1998.
Technology and Cost Document for the
Final Ground Water Rule
October 2006
5-12
-------
Exhibit 5.7 Estimated Costs for the Installation of a Booster Pump (2003$)
Cost
Component
Centrifugal
Pump1
90 Degree
Elbows (steel
flanged)
Tees (Steel,
Flanged)
Gate valves
(Steel, flanged)
Subtotal
Design2
Permitting3
Total Cost45
(1998$)
Total Cost4
(2003$)
Number
1
2
2
2
Population Size Category
<100
$3,575
$360
$400
$680
$5,015
$802
$150
$6,000
$6,510
101-500
$4,675
$360
$532
$810
$6,377
$1,020
$191
$7,600
$8,266
501-
1,000
$5,700
$424
$660
$1,320
$8,104
$1,297
$243
$9,600
$10,436
1,001-
3,300
$5,875
$660
$1,150
$1,756
$9,441
$1,511
$283
$11,200
$12,193
3,301-
10,000
$7,625
$660
$1,150
$1,756
$11,191
$1,791
$336
$13,300
$14,156
10,001-
50,000
$9,500
$660
$1,150
$1,812
$13,122
$2,100
$394
$15,600
$16,636
50,001-
100,000
$12,800
$890
$1,290
$3,350
$18,330
$2,933
$550
$21,800
$23,766
>1 00,000
$14,200
$1,670
$2,500
$5,450
$23,820
$3,811
$715
$28,300
$30,792
Horizontal 1-stage split casing pump.
2 Design costs based on 16 percent of capital.
3 Permitting costs based on 3 percent of capital.
"Estimate rounds cost to nearest $100.
5 Source: R.S. Means, 1998.
5.3.2 Source Water Corrective Actions
5.3.2.1 Eliminating Known Sources of Contamination
There are many possible actions that a system could take to eliminate a source of contamination.
EPA has estimated the costs associated with eliminating a known source of contamination by assuming
that the system must remove and replace a septic system or cesspool. Exhibit 5.8 presents costs
associated with the remediation to relocate a 2,500 gallon septic tank and leach field to eliminate the
source of contamination. The capital costs itemized in Exhibit 5.8 include materials and labor. EPA
developed excavation costs by assuming the installation of a new septic tank 500 feet from the old tank
site. Total estimated costs for the drainage of the old septic tank and installation of a new tank are
$16,533 (in 2003 dollars).
Technology and Cost Document for the
Final Ground Water Rule
October 2006
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Exhibit 5.8 Estimated Costs for Elimination of Known Sources of Contamination
Drainage of the Old Septic Tank and Installation of a New Septic Tank (2003$)
Item
Survey and siting new septic tank (4 hrs)2
Excavate (170 C.Y.) 1/2 C.Y. backhoe (1 day)2
Installation 500' of 6" vitrified clay piping
Excavate for new septic tank (16 C.Y.) 3/4 C.Y.
backhoe2
Septic tank purchase and installation (2500 gal)
Fittings, 6" PVC Tees
Empty old tank and dispose of contents
Backfill old tank using existing stockpile and front-end
loader2
Compaction in 12" layers air tamp1
Leaching field excavation 30 C.Y. 1/4 C.Y. backhoe (1
day)2
Installation of 190' of 6" perforated PVC
Concrete leaching distribution box installation 4'x4'x4'
Gravel fill to 1' depth in 3 trenches (7 C.Y.)
Trench backfill common earth and compaction (14
C.Y.)2
Units
hourly
daily
L.F.
daily
each
each
tank
daily
daily
daily
L.F.
each
C.Y.
C.Y.
Number
4
1
500
1
1
5
1
1
1
1
190
1
7
14
Unit Cost,
Including O&P
$18.03
$1,000.40
$7.35
$1,111.75
$1,225.00
$102.00
$177.00
$800.90
$1,516.30
$911.10
$6.90
$258.00
$17.80
$3.99
Subtotal Capital Cost
Design cost3
Permitting cost4
Total (1998$)
Total (2003$)
Estimate1
$100
$1,000
$3,700
$1,100
$1,200
$500
$200
$800
$1,500
$900
$1,300
$300
$100
$100
$12,800
$2,000
$400
$15,200
$16,533
O&P - Overhead and Profit
LF - Linear foot
CY - Cubic yard
1 Estimate rounded to nearest $100.
2 Best professional judgement for the number and specification of the relevant items
3 Design cost based on 16 percent of capital.
4 Permitting costs based on 3 percent of capital.
Source: R.S. Means, 1998.
5.3.2.2 Rehabilitation of Existing Wells
The costs for rehabilitating a well discovered through source water monitoring is the same as
discussed in Section 5.3.1.2.
5.3.2.3 Purchasing Water from Another Utility
Exhibit 5.9 presents the cost components for purchasing water, which includes installing the
infrastructure for delivering water to the system, as well as piping, construction, permitting, and design.
EPA used a distance of 1.5 miles from the new connection to the system for estimating costs. Total
capital costs increase with increasing population size category and increasing pipe diameter. The overall
cost will vary, however, depending on the price of water and the quantity of water purchased to
supplement the system's demand.
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Final Ground Water Rule
October 2006
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Exhibit 5.9 General Costs Associated with a System Purchasing Water (2003$)
Population Size Category
<100
101-500
501-1,000
1,001-3,300
3,301-10,000
10,001-50,000
50,001-100,000
>100,000
Capital Costs
Pipe Diameter (inches)
Piping Unit Cost/LF
Construction1
Permitting2
Design2
Capital Costs (1998$)
Capital Costs (2003$)
4
$13.95
$132,600
$4,000
$21,200
$157,800
$173,180
4
$13.95
$132,600
$4,000
$21,200
$157,800
$173,180
6
$16
$152,100
$4,600
$24,300
$181,000
$198,599
6
$16
$152,100
$4,600
$24,300
$181,000
$198,599
8
$19.55
$185,800
$5,600
$29,700
$221,100
$242,618
8
$19.55
$185,800
$5,600
$29,700
$221,100
$242,618
10
$28.5
$270,900
$8,100
$43,300
$322,300
$353,697
12
$31.5
$299,400
$9,000
$47,900
$356,300
$390,999
Operation and Maintenance Costs
Unit cost of H2O per kga!3(1998$)
I Init rn<;t nf H_O npr knal3
Total Avg Annual Expense
Total Avg Annual Expense
Percent Operating Expense
Percent of Operating Avoided4
Expense Avoided4 (1998$)
Expense Avoided4 (2003$)
Avg. Daily Production (MGD)
Avoided cost per kgal (1998$)
Avoided cost per kgal (2003$)
Net cost per kgal (1998$)
Net cost per kgal (2003$)
$1.60
$1 7R
$6,350
$6,923
95%
31%
$1,883
$2,050
0.01
$0.57
$0.62
$1.03
$1.12
$1.60
$1 7R
$22,430
$24,386
93%
30%
$6,245
$6,797
0.03
$0.52
$0.57
$1.08
$1.18
$1.17
$1 2ft
$77,110
$83,904
88%
30%
$20,396
$22,200
0.10
$0.59
$0.64
$0.58
$0.63
$1.63
$1 7ft
$167,190
$181,963
87%
24%
$34,948
$38,039
0.31
$0.31
$0.34
$1.32
$1.44
$2.21
$2 43
$517,110
$562,836
88%
22%
$99,827
$108,667
0.94
$0.29
$0.32
$1.92
$2.09
$1.50
$1 R4
$1,925,940
$2,096,248
88%
21%
$350,660
$381,676
3.68
$0.26
$0.28
$1.24
$1.35
$1.57
$1 R4
$7,674,550
$8,084,200
85%
19%
$1,261,905
$1,373,520
11.78
$0.29
$0.32
$1.28
$1.39
$1.06
$1 17
$23,060,500
$24,291,400
84%
21%
$4,099,281
$4,461,862
50.19
$0.22
$0.24
$0.84
$0.91
1 Construction cost based on the installation of 1.5 miles of piping; ductile iron piping; plus 20 percent for fittings, excavation, and other expenses; rounded to the nearest $100.
2 Design cost based on 16 percent of capital; permitting cost based on 3 percent of capital.
3 Unit cost based on the mean wholesale per 1,000 gal sold.
4 Avoided cost is the estimated cost the system would incur if it continued to produce its own water. The estimate is based upon the mean expenses for energy, chemicals and
supplies in primarily ground water systems divided by their average annual production of water.
Sources: R.S. Means, 1998; USEPA, 1997a
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Final Ground Water Rule
October 2006
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5.3.2.4 Installation of New Wells
The cost to develop new ground water source wells for potable water supply depends on the
capacity and demand requirements of the new wells and the drilling environment. The key parameters
include well depth and diameter, the length of surface casing, water depth, and the size of the pump and
developing the wells, acquiring and placing new submersible pumps, conducting pump tests, well
disinfection, sealing the surface of the wells, testing the wells for water quantity and quality, well
permitting, added piping, and building well houses.
Community water systems requiring a larger capacity well will have higher installation and
development costs. Assuming that the new well is 250-feet deep and 6-inches in diameter, EPA estimates
the cost, rounded to the nearest $100, to be $30,200 (in 2003 dollars). This estimate includes costs for
materials, labor, equipment (including some O&M expenses), overhead, profit, and permitting.
Exhibit 5.10 identifies each cost component and the materials, labor, and equipment costs
associated with each component of the new well.
Exhibit 5.10 Estimated New Well Costs for Community Water Systems (2003$)
Cost Component
Well Drilling3
Well Screen4
Steel Well Casing5
Develop Well6
Pump Test7
Surface Seal8
Well Disinfection9
25-hp Pump10
Well House11
Permitting costs12
Total (1998$)
Total (2003$)
Total Including Overhead and Profit1'2
$7,100
$2,100
$1,200
$1,600
$400
$3,300
$700
$5,500
$5,000
$800
$27,700
$30,172
1 Equipment costs include not only rental, but also operating costs for equipment under
normal use. The operating costs include parts and labor for routine servicing and repairs.
2Total cost includes overhead and profit as reported by R.S. Means (1997a) rounded to
the nearest $100.
3The well is 250-feet deep and 6-inches in diameter.
4 The well screen assembly is stainless steel and 20-feet in length and 6 inches in
diameter.
5Well casing applied to 100-feet of the well. Casing assumed to be steel and weigh 8.75
pounds per foot.
6The cost for developing the well is a one-time cost estimated to take 3 hours to
complete.
7The cost for conducting a 1-hour pump test is a one-time cost.
8The surface seal is a one-time cost.
9Well disinfection is a one-time cost.
10The pump is a 25-hp submersible pump.
11 The well house price is equivalent to a prefab residential 2-car garage.
12 Permitting costs based on 3 percent of capital.
Source: R.S. Means, 1998
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Final Ground Water Rule
October 2006
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5.3.3 Additional Corrective Actions
5.3.3.1 Storage Tank Cover Replacement or Repair
Aging water storage tanks with damaged tank covers may be a source of contamination. Exhibit
5.11 presents estimated costs for repairing water storage tank covers according to population size
category. These cost estimates assume a 20 percent value of the total cost for installing a new tank. Total
repair estimates include capital, and overhead and profit (O&P) costs. Storage tank size increases with
population size category. EPA used a tank size 1,000,000 gallons for estimating costs for systems serving
populations greater than 10,000 persons.
Exhibit 5.11 Estimated Costs for the Repair of Storage Tank Cover (2003$)
Cost Component 1
Tank Size (gal) &
Style
New Tank
Construction Cost3'4
(1998$)
New Tank
Construction Cost
(2003$)3
Repair Estimate1'2'3
(1998$)
Repair Estimate1'2'3
(2003$)
Population Size Category
<100
10,000
surface
$13,500
$14,673
$2,700
$2,893
101-500
30,000
surface
$30,200
$32,859
$6,040
$6,613
501-
1,000
100,000
elevated
$225,000
$244,891
$45,000
$48,978
1,001-
3,300
250,000
elevated
$310,000
$337,371
$62,000
$67,474
3,301-
10,000
750,000
elevated
$690,000
$751,000
$138,000
$150,241
10,001-
50,000
1,000,000
elevated
$797,000
$867,452
$159,400
$173,490
50,001-
100,000
1,000,000
elevated
$797,000
$867,452
$159,400
$173,490
>1 00,000
1,000,000
elevated
$797,000
$867,452
$159,400
$173,490
1 Estimate is for tank cover repair only and does not require design or permitting costs.
2 Total tank cover repair estimate is calculated based on 20% cost of the total cost for constructing a new tank.
3 Estimate rounds cost to nearest $100.
"Source: R.S. Means, 1998.
5.3.3.2 Cross-Connection Control and Backflow Prevention Program
The cost components of a cross-connection control and backflow prevention program can be
broadly classified as:
• Cost of Backflow Prevention Assemblies and Devices
Cost of Program Administration: This can be further classified as: program organization,
system survey, record keeping costs, and enforcement.
The cost of program administration is usually more significant for small systems (i.e., typically
systems serving populations less than or equal to 10,000). However, for large systems, the costs of the
backflow devices and assemblies costs are usually more significant than the program administration costs.
This section provides the costs of installing a backflow prevention device and describes the items
included under program administration.
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Final Ground Water Rule
October 2006
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Back/low Prevention Assemblies and Devices
Exhibit 5.12 presents the costs of installing a backflow prevention assembly (i.e., a reduced
pressure flanged iron assembly). This is the usually the most expensive assembly and is used in situations
of highest hazard when backpressure and backsiphonage are both possible (www .use. edu/dept/fccchr).
Systems should install above-grade housing with drainage and heat to protect the equipment from
freezing where systems cannot install valves indoors. Installation costs do not include costs for this
housing, or costs for engineering/construction. Maintenance of these assemblies includes a minimum of
annual testing and inspection. In addition, the frequency for performance monitoring and internal
inspections (dismantling, cleaning, and repairs) should occur based on local water quality conditions, the
probability of contamination due to potential backflow, and manufacturers' recommendations for the
specific backflow prevention assembly.
Backflow prevention equipment installation and maintenance is generally the consumer's
responsibility. However, depending on how a system implements the cross-connection control and
backflow prevention program, the customer and the utility can share costs for the equipment and
equipment installation, inspection, testing, and maintenance. The utility, on the other hand, is primarily
responsible for the administration of cross-connection control and backflow prevention and the
inspection, review, and approval of all backflow prevention assemblies and devices.
Exhibit 5.12 Estimated Costs for a Backflow Prevention Assembly (2003$)
Cost Component 1|2'3
Reduced Pressure,
Flanged
Total -incl. O&P(1998$)
Total- incl. O&P
(2003$)
Population Size Category
<100
2.5 inch
$2,100
$2,273
101-500
2.5 inch
$2,100
$2,273
501-
1,000
2.5 inch
$2,100
$2,273
1,001-
3,300
3 inch
$2,200
$2,377
3,301-
10,000
3 inch
$2,200
$2,377
10,001-
50,000
4 inch
$3,000
$3,307
50,001-
100,000
6 inch
$4,700
$5,166
>1 00,000
6 inch
$4,700
$5,166
1 Estimates assume larger systems will on average have larger connections on which to install backflow prevention
assemblies.
2 Estimates assume assemblies are reduced pressure principle, flanged iron devices, and includes valves and
installation.
3 Does not include design or permit costs.
Source: R.S. Means, 1998 (includes O&P, rounded to nearest $100).
Program Administration
The administration of a CCCBPP is typically the responsibility of the utility. Costs for program
administration depend on the system size (population served and area covered), system demographics
(number of industrial, residential, and institutional customers), available staffing resources, maintenance
and record keeping, and specific code and regulatory requirements. Another factor in the administrative
costs in some cases is overcoming political resistance. The Cross-Connection Control Manual provides
additional guidance on program administration (USEPA, 1989c). Program administration will require
availability of technical and administrative staff. If sufficient staff is available, appropriate division of
program oversight duties may apply. Otherwise, these tasks may require additional staff or temporary
help. In some cases, program administration is contracted out. The Program Administration costs can be
classified under three headings:
Technology and Cost Document for the
Final Ground Water Rule
October 2006
5-18
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Program Organization: It involves establishing the legal foundation for the plan, establishing
responsibilities and chain of command, conducting employee and consumer education programs,
implementing required codes and regulations for enforcing the program, monitoring the progress of the
program, etc.
System Survey: It involves surveying the system for potential cross-connections and identifying
and prioritizing hazardous connections.
Record Keeping: It involves updating and maintaining records that are pertinent to the
implementation of the CCCBPP.
Exhibit 5.13 summarizes the activities included under each of the three components of Program
Administration.
Exhibit 5.13 Cost Components of Program Administration for a Cross-
Connection Control and Backflow Prevention Program
Cost Component
Specific Items Included
Program
Organization
Consulting with relevant local and State administrations
Establishing responsibilities and authorities for required program activities
(inspections, maintenance, reporting, etc.)
Notifying and educating employees and consumers of program and implications
Developing and implementing a local ordinance
Program Enforcement by the utility
System Survey
Recording number and sites of connections
Identifying potential hazardous connections
Prioritizing hazardous connections
Developing inspection schedules and records
Record keeping
Inspection records
Installation, repair, and maintenance of records
Customer correspondence records
Ordinance development records
Assembly test records
In addition to the other items presented in this section, a successful cross connection control
program will require development of testing and enforcement programs to ensure proper operation and
compliance. Such programs represent additional costs that are not included here.
5.3.3.3 Installation of Security Measures
Exhibit 5.14 presents the cost components for installing fencing, a gate with a lock, and flood
lights for 0.5 and 1-acre lots based on the need for a 0.5-acre of security fencing for systems serving
populations of 3,300 or fewer, and on the need for 1-acre of security fencing for systems serving
populations greater than 3,300. EPA estimates the cost for installing security measures on a 0.5-acre lot
to be $9,920, and for a 1-acre lotto be $13,640 (in 2003 dollars).
Technology and Cost Document for the
Final Ground Water Rule
October 2006
5-19
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Exhibit 5.14 Estimated Costs for Installation of Security Measures (2003$)
Item
Chainlinked fence with 3 strands barbed wire, 2" post @
10' O.C., set in concrete, 6' H (9 ga.wire, galv. steel)
Gate for 6' high fence, 1-5/8" frame, 3' wide, galv. steel
Flood lights-35 watt low pressure sodium wall mounted (2)
Lock
Total (1998$)
Total (2003$)
Population Served
<3,3001
$8,200
$250
$600
$10
$9,100
$9,920
>3,3002
$11,600
$250
$600
$10
$12,500
$13,640
Total cost includes overhead and profit, rounded to the nearest $100.
1 Security measures assumed for a 0.5-acre lot (600 L.F.).
2Security measures assumed for a 1-acre lot (850 L.F.).
Source: R.S. Means, 1998.
5.4 Summary
Exhibit 5.15 summarizes the costs derived in this chapter. The summary table includes those
BMPs which were used in the EA for the GWR.
Exhibit 5.15 Estimated Unit Costs of Non-Treatment Corrective Actions for
Source Water Contamination (2003$)
Corrective Action
Size Category (Population Served)
<100
101-500
501-
1,000
1,001-
3,300
3,301-
10,000
10,001-
50,000
50,001-
100,000
100,001-
1 Million
>1 Million
Nontreatment Corrective Actions
Rehabilitate an
Existing Well
Drill a New Well
Purchase Water
Capital
O&M ($ per kgal)
Eliminate Source of
Contamination
$1 1 ,986
$30,172
$1 1 ,986
$30,172
$1 1 ,986
$30,172
$1 1 ,986
$30,172
$1 1 ,986
$30,172
$1 1 ,986
$30,172
$1 1 ,986
$30,172
$1 1 ,986
$30,172
$1 1 ,986
$30,172
$173,180
$1.12
$16,533
$173,180
$1.18
$16,533
$198,599
$0.63
$16,533
$198,599
$1.44
$16,533
$242,618
$2.09
$16,533
$242,618
$1.35
$16,533
$353,697
$1.39
$16,533
$390,999
$0.91
$16,533
$390,999
$0.91
$16,533
Source: Sections 5.1 through 5.2
Technology and Cost Document for the
Final Ground Water Rule
5-20
October 2006
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Appendix A
Linear Regression Coefficients for Unit Costs
-------
-------
Exhibit A-1 Cost Equation Coefficient Inputs for At-grade Tanks for
Chlorine Contact
(Residual 2 mg/L)
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
Total Capital Costs
Regression Coeff.
A
787.81
358.75
358.75
359.18
358.77
357.51
357.51
358.67
358.67
-98,530.98
-98,530.98
71,928.42
119,686.24
191,365.13
204,017.97
393,399.16
B
0.00
61.29
61.29
61.28
61.29
61.29
61.29
61.29
61.29
160.18
160.18
74.95
61.31
51.07
50.32
41.71
Technology and Cost Document for the
Final Ground Water Rule
A-1
October 2006
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Exhibit A-2 Cost Equation Coefficient Inputs for At-grade Tanks for
Chlorine Dioxide Contact
(Residual 0.625 mg/L)
Design Flow range
(kgpd-kgpd)
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
Total Capital Costs
Regression Coeff.
A
358.77
357.51
357.51
5875.14
6032.93
-94346.26
-94346.26
76113.14
121741.77
246453.18
258140.16
B
85.79
85.80
85.80
70.47
70.24
170.62
170.62
85.39
72.35
54.54
53.85
Technology and Cost Document for the
Final Ground Water Rule
A-2
October 2006
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Exhibit A-3 Cost Equation Coefficient Inputs for Gas Chlorination (Dose 4 mg/L)
(No Storage)
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
Total Capital Costs
Regression Coeff.
A
29,867.54
29,867.54
29,867.54
29,867.54
29,867.54
29,867.54
29,867.54
29,867.54
-27,572.19
47,603.00
47,592.50
47,590.67
47,589.00
46,202.60
32,745.40
22000-<=76000 127,100.63
B
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
84.47
9.30
9.30
9.30
9.31
9.50
10.29
6.01
Average Flow range
(kgpd-kgpd)
<= 1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
O&M Costs
Regression Coeff.
A
6,182.00
6,175.85
6,178.24
6,179.90
6,182.52
6,183.20
6,181.69
6,180.92
-11,402.58
14,967.00
14,968.14
14,940.33
20,367.38
14,984.25
14,923.31
11,329.04
B
0.00
4.10
3.66
3.48
3.38
3.37
3.38
3.39
79.84
4.50
4.50
4.53
0.66
2.45
2.46
2.79
(With Storage)
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
Total Capital Costs
Regression Coeff.
A
30,655.35
30,226.29
30,226.29
30,226.72
30,226.31
30,225.05
30,225.05
30,226.21
-27,213.51
-50,927.98
-50,938.48
119,519.08
167,275.24
237,567.73
236,763.37
520,499.79
B
0.00
61.29
61.29
61.28
61.29
61.29
61.29
61.29
145.76
169.48
169.48
84.26
70.61
60.57
60.62
47.72
Average Flow range
(kgpd-kgpd)
<= 1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
O&M Costs
Regression Coeff.
A
6,182.00
6,175.85
6,178.24
6,179.90
6,182.52
6,183.20
6,181.69
6,180.92
-11,402.58
14,967.00
14,968.14
14,940.33
20,367.38
14,984.25
14,923.31
11,329.04
B
0.00
4.10
3.66
3.48
3.38
3.37
3.38
3.39
79.84
4.50
4.50
4.53
0.66
2.45
2.46
2.79
Technology and Cost Document for the
Final Ground Water Rule
A-3
October 2006
-------
Exhibit A-4 Cost Equation Coefficient Inputs for Hypochlorination (Dose 4 mg/L)
(No Storage)
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
Total Capital Costs
Regression Coeff.
A
8,969.67
8,969.67
8,969.67
8,969.67
-6,809.78
24,402.32
24,402.32
24,402.32
-72,273.88
56,362.00
60,001.00
70,598.00
74,529.00
78,681.10
88,729.80
93,394.78
B
0.00
0.00
0.00
0.00
173.40
0.00
0.00
0.00
142.17
13.54
10.50
5.20
4.08
3.49
2.90
2.68
Average Flow range
(kgpd-kgpd)
<= 1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
O&M Costs
Regression Coeff.
A
1,468.31
1,392.80
1,392.45
1,393.78
-593.79
6,075.16
6,074.27
6,073.54
7,519.86
7,519.00
6,999.67
2,116.89
2,369.50
2,630.13
2,588.69
2,724.48
B
0.00
50.34
50.40
50.26
129.77
6.27
6.28
6.29
0.00
0.00
1.27
7.61
7.43
7.34
7.35
7.33
(With Storage)
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
Total Capital Costs
Regression Coeff.
A
9,757.48
9,328.42
9,328.42
9,328.85
-6,451.02
24,759.83
24,759.83
24,760.99
-71,915.20
-42,168.98
-38,529.98
B
0.00
61.29
61.29
61.28
234.69
61.29
61.29
61.29
203.46
173.72
170.68
Average Flow range
(kgpd-kgpd)
<= 1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
O&M Costs
Regression Coeff.
A
1,468.31
1,392.80
1,392.45
1,393.78
-593.79
6,075.16
6,074.27
6,073.54
7,519.86
7,519.00
6,999.67
B
0.00
50.34
50.40
50.26
129.77
6.27
6.28
6.29
0.00
0.00
1.27
Technology and Cost Document for the
Final Ground Water Rule
A-4
October 2006
-------
Exhibit A-5 Cost Equation Coefficient Inputs for Difference in
Chlorine (gas/hypochlorination)
O&M Costs from a Dose of 2.5 mg/L to 4 mg/L
Average Flow range
(kgpd-kgpd)
<= 1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
O&M Cost difference
Regression Coeff.
A
27.90
-0.72
1.59
178.61
179.00
145.95
-2.94
-0.17
-526.10
190.00
121.67
2,107.78
-24.88
3,808.88
-13.94
-1,782.93
B
0.00
19.08
18.65
0.02
0.00
0.61
2.38
2.36
4.65
2.60
2.77
0.19
1.71
0.43
0.92
1.08
Technology and Cost Document for the
Final Ground Water Rule
A-5
October 2006
-------
Exhibit A-6 Cost Equation Coefficient Inputs for Chlorine Dioxide (Dose 1.25 mg/L)
(No Storage)
Design Flow range
(kgpd-kgpd)
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
76000-<=210000
210000-<=430000
430000-<=520000
Total Capital Costs
Regression Coeff.
A
26,584.02
37,001.90
36,722.75
36,993.82
43,238.21
-144,720.88
78,579.32
-63,125.11
170,892.66
172,034.60
172,213.83
171,914.01
437,393.28
565,655.87
659,676.23
B
66.78
8.90
9.94
9.18
0.00
187.96
1.88
72.73
5.87
5.70
5.69
5.71
2.21
1.60
1.38
Average Flow range
(kgpd-kgpd)
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
38000-<=1 20000
120000-<=270000
270000-<=350000
O&M Costs
Regression Coeff.
A
13,782.58
14,056.30
16,093.91
16,534.07
16,636.30
14,261.63
16,969.05
21,363.74
17,131.46
21,789.44
23,570.13
27,814.09
31,119.03
56,932.02
57,055.82
B
40.19
35.12
10.86
6.86
6.41
13.20
6.60
0.89
3.91
2.36
2.13
1.75
1.66
1.44
1.44
(With Storage)
Design Flow range
(kgpd-kgpd)
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
Total Capital Costs
Regression Coeff.
A
26,942.79
37,359.41
37,080.26
42,868.96
49,271.14
-239,067.14
-15,766.93
12,988.03
292,634.43
418,487.78
430,353.98
B
152.57
94.70
95.74
79.66
70.24
358.58
172.50
158.12
78.22
60.24
59.54
Average Flow range
(kgpd-kgpd)
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
O&M Costs
Regression Coeff.
A
14,677.60
15,518.24
16,853.91
17,316.11
17,421.56
17,220.51
17,422.93
22,607.49
19,606.03
19,356.21
20,947.43
B
42.78
27.21
11.31
7.11
6.65
7.23
6.73
0.00
2.14
2.23
2.02
Technology and Cost Document for the
Final Ground Water Rule
A-6
October 2006
-------
Exhibit A-7
(No storage)
Cost Equation Coefficient Inputs for Anodic Oxidation (Dose 4 mg/L)
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
Total Capital Costs
Regression Coeff.
A
39,396.48
33,413.28
40,343.67
47,556.05
56,906.20
77,901.22
78,000.42
77,958.05
43,278.31
43,279.60
75,620.74
105,464.05
246,617.80
394,504.98
939,670.31
1,242,761.05
B
0.00
854.74
539.72
344.80
242.05
125.41
125.04
125.16
176.16
176.16
149.21
134.28
93.95
72.83
40.76
26.98
Average Flow range
(kgpd-kgpd)
<=1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
O&M Costs
Regression Coeff.
A
2,907.70
2,905.31
129.44
3,993.82
5,094.19
6,196.68
6,830.96
8,463.04
9,128.48
9,291.23
9,991.43
15,134.34
15,133.14
19,100.99
20,105.94
20,697.38
B
0.00
1.59
515.64
108.86
64.85
44.43
36.88
22.04
19.15
18.69
16.98
10.30
10.30
8.98
8.85
8.79
(With Storage)
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
Total Capital Costs
Regression Coeff.
A
40,184.29
33,772.03
40,702.42
47,915.23
57,264.97
78,258.73
78,357.93
78,316.73
43,636.99
-55,251.38
-22,910.25
177,392.46
366,304.03
585,870.11
1,143,688.28
1,636,160.22
B
0.00
916.04
601.02
406.08
303.33
186.70
186.33
186.45
237.45
336.34
309.39
209.23
155.26
123.89
91.08
68.70
Average Flow range
(kgpd-kgpd)
<=1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
O&M Costs
Regression Coeff.
A
2,907.70
2,905.31
129.44
3,993.82
5,094.19
6,196.68
6,830.96
8,463.04
9,128.48
9,291.23
9,991.43
15,134.34
15,133.14
19,100.99
20,105.94
20,697.38
B
0.00
1.59
515.64
108.86
64.85
44.43
36.88
22.04
19.15
18.69
16.98
10.30
10.30
8.98
8.85
8.79
Technology and Cost Document for the
Final Ground Water Rule
A-7
October 2006
-------
Exhibit A-8 Cost Equation Coefficient Inputs for Ozonation
(No pH adjustment)
Design Flow range
(kgpd-kgpd)
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
76000-<=210000
210000-<=430000
430000-<=520000
Total Capital Costs
Regression Coeff.
A
261,830.35
271,534.78
275,438.44
288,498.99
403,021.23
316,210.63
415,879.99
734,764.83
833,333.71
1,243,548.46
1,908,971.15
1,253,459.60
4,792,888.54
8,630,547.65
5,470,535.57
B
675.14
621.23
606.77
570.49
402.07
488.88
405.83
246.38
218.22
159.62
120.48
150.27
103.70
85.43
92.78
Average Flow range
(kgpd-kgpd)
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
38000-<=1 20000
120000-<=270000
270000-<=350000
O&M Costs
Regression Coeff.
A
55,205.76
49,571.30
58,272.41
58,441.08
58,441.08
57,990.96
58,486.38
55,279.62
62,294.73
63,874.29
67,572.90
60,793.68
41,971.65
181,578.13
204,198.02
B
12.56
116.90
13.32
11.79
11.79
13.07
11.86
16.03
11.02
10.49
10.02
10.63
11.13
9.96
9.88
(With pH adjustment)
Design Flow range
(kgpd-kgpd)
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
76000-<=210000
210000-<=430000
430000-<=520000
Total Capital Costs
Regression Coeff.
A
263,710.67
311,509.78
315,413.44
328,473.99
442,996.23
356,185.63
455,854.99
774,739.83
873,308.71
1,283,523.46
1,948,946.15
1,293,434.60
4,832,863.54
8,670,522.65
5,510,510.57
B
904.27
638.72
624.27
587.99
419.57
506.38
423.32
263.88
235.72
177.12
137.97
167.77
121.20
102.92
110.27
Average Flow range
(kgpd-kgpd)
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
38000-<=1 20000
120000-<=270000
270000-<=350000
O&M Costs
Regression Coeff.
A
55,205.76
49,571.30
58,272.41
58,441.08
58,441.08
57,990.96
58,486.38
55,279.62
62,294.73
63,874.29
67,572.90
60,793.68
41,971.65
181,578.13
204,198.02
B
52.29
156.63
53.04
51.51
51.51
52.80
51.59
55.75
50.74
50.22
49.74
50.36
50.85
49.69
49.61
Technology and Cost Document for the
Final Ground Water Rule
October 2006
-------
Exhibit A-9 Cost Equation Coefficient Inputs for Nanofiltration
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
76000-<=210000
210000-<=430000
430000-<=520000
Total Capital Costs
Regression Coeff.
A
52,107.22
44,012.03
44,012.03
39,186.26
87,830.12
36,612.96
192,484.23
12,513.50
134,149.45
71,874.26
-326,538.15
171,179.90
63,000.00
652,725.04
472,838.89
4,505,630.65
16,665,213.20
130,182.12
9,465,362.32
B
0.00
1,156.46
1,156.46
1,286.88
752.34
1,036.87
459.57
959.49
780.62
842.89
1,174.90
926.04
956.95
872.70
883.29
699.98
539.98
618.72
597.01
Average Flow range
(kgpd-kgpd)
<=1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
38000-<=1 20000
120000-<=270000
270000-<=350000
O&M Costs
Regression Coeff.
A
6,908.69
6,513.35
6,502.37
6,158.52
51.91
14,480.22
20,720.87
18,012.58
-8,977.50
29,112.38
36,319.37
37,785.44
21,651.71
42,227.27
198,620.98
195,547.90
531,298.29
541,027.91
1,939,143.53
B
0.00
263.56
265.59
301.78
546.05
278.86
204.56
229.19
346.53
237.71
220.13
218.22
229.75
222.89
202.84
203.12
194.28
194.20
189.02
Technology and Cost Document for the
Final Ground Water Rule
A-9
October 2006
-------
Exhibit A-10 Cost Equation Coefficient Inputs for Temporary Hypochlorination (Dose 4 mg/L)
(No Storage)
Design Flow range
(kgpd-kgpd)
<=7
7-<=22
22-<=37
37-<=91
91-<=180
180-<=270
270-<=360
360-<=680
680-<=1000
1000-<=1200
1200-<=2000
2000-<=3500
3500-<=7000
7000-<=17000
17000-<=22000
22000-<=76000
Total Capital Costs
Regression Coeff.
A
1,873.73
1,873.73
1,873.73
1,873.73
1,873.73
1,873.73
1,873.73
1,873.73
1,873.73
1,873.73
1,699.73
1,647.53
2,137.63
-7,071.52
3,373.51
17,304.65
B
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.15
0.17
0.03
1.35
0.73
0.10
Average Flow range
(kgpd-kgpd)
<=1.5
1.5-<=5.4
5.4-<=9.5
9.5-<=25
25-<=54
54-<=84
84-<=110
110-<=230
230-<=350
350-<=410
410-<=770
770-<=1400
1400-<=3000
3000-<=7800
7800-<=11000
11000-<=38000
O&M Costs
Regression Coeff.
A
2,636.18
2,636.18
2,376.72
2,706.92
2,367.63
3,582.10
3,341.95
3,987.92
2,855.17
4,455.47
1,947.61
2,116.89
2,369.50
2,630.13
2,588.69
2,724.48
B
0.00
0.00
48.05
13.29
26.86
4.37
7.23
1.36
6.28
1.71
7.83
7.61
7.43
7.34
7.35
7.33
Technology and Cost Document for the
Final Ground Water Rule
A-10
October 2006
------- |