4>EPA
United States
Environmental Protection
Agoncy
Handbook -1998 Edition
Optimizing Water Treatment
Plant Performance Using the
Composite Correction Program
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EPA/625/6-91-027
Revised August 1998
Updated September 2004
Handbook-1998 Edition
Optimizing Water Treatment Plant
Performance Using the
Composite Correction Program
Office of Water
Technical Support Center
Standards and Risk Management Division
Office of Ground Water and Drinking Water
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
Office of Research and Development
Technology Transfer and Support Division
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Notice
This document has been reviewed in accordance with the U.S. Environmental Protection
Agency's peer and administrative review policies and approved for publication. Mention
of trade names or commercial products does not constitute endorsement or
recommendation for use.
This is an updated version of this handbook originally published in
August 1998. The updates included minor modifications to Table
4-2 and replacement of the original materials in Appendix A with
the instructions for using the Optimization Assessment
Spreadsheets included on the CD at the back of the Handbook.
This CD also includes the spreadsheets needed for the Major Unit
Process Evaluation discussed in Appendix C. All other materials
in the Handbook have not been changed.
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Acknowledgments
This handbook was prepared for the United States Environmental Protection Agency (U.S. EPA) by Process
Applications, Inc. Although many individuals contributed to the preparation and review of this document, the
assistance of the individuals listed below is especially acknowledged.
Major Authors:
Bob A. Hegg and Larry D. DeMers, Process Applications, Inc., Fort Collins, Colorado
Jon H. Bender, Eric M. Bissonette, and Richard J. Lieberman, U.S. EPA Office of Groundwater and
Drinking Water (OGWDW) Technical Support Center (TSC), Cincinnati, Ohio
Project Managers:
James E. Smith, Jr., U.S. EPA Office of Research and Development, Technology Transfer and
Support Division, National Risk Management Research Laboratory (NRMRL)
Jon H. Bender, U.S. EPA OGWDW, TSC, Cincinnati, Ohio
Reviewers:
Frank Evans, U.S. EPA, NRMRL, Cincinnati, Ohio
Julie Z. LeBlanc, U.S. Army Corps of Engineers, New Orleans, Louisiana
David Parker, U.S. EPA, Region IV, Atlanta, Georgia
Chuck Schwarz, Texas Natural Resource Conservation Commission, Tyler, Texas
Jeff Robichaud, U.S. EPA, OGWDW, Washington, D.C.
Editing and Production:
M. Lynn Kelly, Process Applications, Inc., Fort Collins, Colorado
in
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Contents
Chapter Page
Acknowledgments iii
List of Figures x
List of Tables xi
1 Introduction 1
1.1 Purpose 1
1.2 Background 1
1.2.1 Wastewater Treatment Compliance 1
1.2.2 Water Treatment Optimization 2
1.2.3 Broad-Scale Application of CCP Concepts 2
1.3 Scope 3
1.3.1 Update of the CCP Approach and Implementation 3
1.3.2 Support for Future Regulations 3
1.3.3 Technical Resource forthe Partnership for Safe Water 4
1.3.4 Considerations for Total System Optimization 4
1.4 Using the Manual 4
1.5 References 4
2 Protection Of Public Health From Microbial Pathogens 7
2.1 Background 7
2.2 Waterborne Disease History 7
2.3 Relationship Between Optimized Performance and Public Health Protection 8
2.3.1 Multiple Barrier Strategy 8
2.3.2 Basis for Optimization Goals 9
2.4 Optimization Performance Goals 10
2.4.1 Minimum Data Monitoring Requirements 10
2.4.2 Individual Sedimentation Basin Performance Goals 10
2.4.3 Individual Filter Performance Goals 10
2.4.4 Disinfection Performance Goal 11
2.5 Role of the Water Treatment Plant Staff in Public Health Protection 11
2.6 References 11
3 Assessing Composite Correction Program Application 13
3.1 Introduction 13
3.2 Optimization Program Experience 13
3.3 Area-Wide Optimization Model 14
3.3.1 Status Component 14
3.3.2 Evaluation Component 14
3.3.3 Follow-Up Component 14
3.3.4 Maintenance Component 14
3.4 Implementation of an Area-Wide Model 14
3.4.1 Establish Criteria to Prioritize Water Systems 16
3.4.2 Assess Water System Performance Relative to Optimization Goals 16
3.4.3 Prioritize Water Systems Based on Selected Criteria 17
3.4.4 Assess Response to Prioritized Water Systems 18
3.5 References 19
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Contents (continued)
Chapter Page
4 Comprehensive Performance Evaluation 21
4.1 Introduction 21
4.2 CPE Methodology 21
4.2.1 Assessment of Plant Performance 21
4.2.1.1 Review and Trend Charting of Plant Operating Records 21
4.2.1.2 Supplemental Data Collection 22
4.2.2 Evaluation of Major Unit Processes 25
4.2.2.1 Overview 25
4.2.2.2 Approach 27
4.2.2.3 Determining Peak Instantaneous Operating Flow 28
4.2.2.4 Rating Individual Unit Processes 29
Flocculation 30
Sedimentation 30
Filtration 31
Disinfection 32
Post-Disinfection 32
Pre-Disinfection 34
4.2.3 Identification and Prioritization of Performance Limiting Factors 35
4.2.3.1 Identification of Performance Limiting Factors 35
Identification of Administrative Factors 36
Policies 37
Budgeting 38
Staffing 38
Identification of Design Factors 38
Identification of Operational Factors 39
Plant Flow Rate and Number of Basins in Service 39
Chemical Dose Control 39
Filter Control 40
Process Control Activities 41
Other Controls 42
Identification of Maintenance Factors 42
4.2.3.2 Prioritization of Performance Limiting Factors 42
4.2.4 Assessment of the Applicability of a CTA 44
4.2.5 CPE Report 44
4.3 Conducting a CPE 44
4.3.1 Overview 49
4.3.2 Initial Activities 49
4.3.2.1 Key Personnel 50
4.3.2.2 CPE Resources 50
4.3.2.3 Scheduling 50
4.3.3 On-Site Activities 51
4.3.3.1 Kick-Off Meeting 51
4.3.3.2 Plant Tour 51
Pretreatment 52
Mixing/Flocculation/Sedimentation 52
Chemical Feed Facilities 53
Filtration 53
Disinfection 54
Backwash Water and Sludge Treatment and Disposal 54
Laboratory 54
Maintenance 54
VI
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Contents (continued)
Chapter Page
4.3.3.3 Data Collection Activities 54
4.3.3.4 Evaluation of Major Unit Processes 55
4.3.3.5 Performance Assessment 55
4.3.3.6 Field Evaluations 55
4.3.3.7 Interviews 57
4.3.3.8 Evaluation of Performance Limiting Factors 57
4.3.3.9 Exit Meeting 58
4.3.4 CPE Report 60
4.4 Case Study 60
4.4.1 Facility Information 60
4.4.2 Performance Assessment 61
4.4.3 Major Unit Process Evaluation 61
4.4.3.1 Flocculation Basin Evaluation 61
4.4.3.2 Sedimentation Basin Evaluation 62
4.4.3.3 Filter Evaluation 62
4.4.3.4 Disinfection Process Evaluation 62
4.4.4 Performance Limiting Factors 63
4.4.5 Assessing Applicability of a CTA 64
4.4.6 CPE Results 64
4.5 References 64
5 Comprehensive Technical Assistance 67
5.1 Objective 67
5.2 Conducting CTAs 68
5.2.1 Overview 68
5.2.2 Implementation 69
5.2.2.1 Approach 70
CTA Facilitator 70
On-Site CTA Champion 71
CTA Framework 71
5.2.2.2 Tools 73
Contingency Plans 73
Action Plans 73
Special Studies 73
Operational Guidelines 74
Data Collection and Interpretation 74
Priority Setting Tools 75
Topic Development Sheets 75
Internal Support 76
What If Scenarios 77
5.2.2.3 Correcting Performance Limiting Factors 77
Design Performance Limiting Factors 77
Maintenance Performance Limiting Factors 78
Administrative Performance Limiting Factors 78
Operational Performance Limiting Factors 79
Process Sampling and Testing 80
Chemical Pretreatment and Coagulant Control 80
Unit Process Controls 82
VII
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Contents (continued)
Chapter Page
5.3 Case Study 85
5.3.1 CPE Findings 85
5.3.2 CTA Activities 86
5.3.2.1 Initial Site Visit 86
5.3.2.2 Off-Site Activities 87
5.3.2.3 Follow-Up Site Visit 87
5.3.2.4 Other CTA Activities 88
5.3.2.5 CTA Results 88
5.4 References 91
6 Findings From Field Work 93
6.1 Introduction 93
6.2 Results of Comprehensive Performance Evaluations 93
6.2.1 Major Unit Process Capability 93
6.2.2 Factors Limiting Performance 94
6.2.3 Summary of CPE Findings 96
6.3 Results of Comprehensive Technical Assistance Projects 97
6.4 References 98
7 The Future: Changing Regulations and New Optimization Challenges 99
7.1 Introduction 99
7.2 Background on M-DBP Regulations 99
7.3 M-DBP Requirements Relative to Optimized Performance Goals 100
7.3.1 Treatment Technique Turbidity Requirements 100
7.3.2 Removal/lnactivation Requirements 101
7.3.3 DBP Maximum Contaminant Levels (MCLs) 102
7.3.4 Enhanced Coagulation Requirements 103
7.3.5 Microbial Backstop 103
7.4 Summary 104
7.5 References 105
8 Other CCP Considerations 107
8.1 Introduction 107
8.2 Developing CCP Skills 107
8.2.1 CPE Training Approach 107
8.2.2 CTA Training Approach 107
8.3 Quality Control 108
8.3.1 CPE Quality Control Guidance 108
8.3.2 CTA Quality Control Guidance 109
8.4 Total System Optimization 110
8.5 References 112
VIII
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Contents (continued)
Appendices
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
Appendix G
Appendix H
Appendix I
Appendix J
Appendix K
Appendix L
Appendix M
Appendix N
Page
Optimization Assessment Spreadsheets 115-1
Drinking Water Treatment Plant (DWTP) Advisor Software 123
Major Unit Process Capability Evaluation Performance Potential Graph
Spreadsheet Tool for the Partnership for Safe Water 125
CT Values for Inactivation of Giardia and Viruses by Free CI2 and Other
Disinfectants 135
Performance Limiting Factors Summary Materials and Definitions 145
Data Collection Forms 159
Example CPE Report 205
Example CPE Scheduling Letter 221
Example Special Study 225
Example Operational Guideline 227
Example Process Control Daily Report 231
Example Jar Test Guideline 233
Chemical Feed Guidelines 237
Conversion Chart 245
IX
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List of Figures
Chapter Page
Figure 2-1. Multiple barrier strategy for microbial contaminant protection 9
Figure 3-1. Area-wide optimization model 15
Figure 3-2. Area-wide treatment plant performance status 16
Figure 3-3. Example turbidity monitoring data for 12-month period 18
Figure 4-1. Example performance assessment trend charts 23
Figure 4-2. Example of individual filter monitoring 25
Figure 4-3. Major unit process evaluation approach 26
Figure 4-4. Example performance potential graph 27
Figure 4-5. Major unit process rating criteria 28
Figure 4-6. Example factors summary and supporting notes 45
Figure 4-7. CPE/CTA schematic of activities 47
Figure 4-8. Schematic of CPE activities 48
Figure 4-9. Flow schematic of Plant A 60
Figure 4-10. Performance potential graph for Plant A 61
Figure 5-1. CTA results showing finished water quality improvements 67
Figure 5-2. CTA priority setting model 68
Figure 5-3. Schematic of CTA framework 72
Figure 5-4. Example action plan 73
Figure 5-5. Special study format 74
Figure 5-6. Short term trend chart showing relationship of raw, settled and filtered
water turbidities 75
Figure 5-7. Example priority setting results from CTA site visit activity 76
Figure 5-8. Example topic development sheet 76
Figure 5-9. A basic process control sampling and testing schedule 81
Figure 5-10. Performance improvement during CTA project - filter effluent 89
Figure 5-11. Performance improvement during CTA project - sedimentation basin effluent 89
Figure 5-12. Performance improvement during CTA project - filter backwash spikes 90
Figure 5-13. Plant performance after CTA 90
Figure 7-1. Historic perspective of turbidity goal and regulations 101
Figure 7-2. Example of disinfection profile daily variations in log inactivation 104
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List of Tables
Number
Table 1-1.
Table 2-1.
Table 3-1.
Table 3-2.
Table 4-1.
Table 4-2.
Table 4-3.
Table 4-4.
Table 4-5.
Table 4-6.
Table 6-1.
Table 6-2.
Table 6-3.
Table 8-1.
Table 8-2.
Table 8-3.
Table 8-4.
Page
Information Pertinent to Specific User Groups 5
U.S. Outbreaks of Cryptosporidiosis in Surface Water Supplies 8
Example Prioritization Criteria for Surface Water Systems 17
Example Prioritization Database 18
Percentile Distribution Analysis of Water Quality Data 24
Major Unit Process Evaluation Criteria 29
Expected Removals of Giardia Cysts and Viruses by Filtration 33
Factors for Determining Effective Disinfection Contact Time Based on
Basin Characteristics 34
Classification System for Prioritizing Performance Limiting Factors 43
Evaluation Team Capabilities 49
Geographical Distribution of CPEs and CTAs 93
Summary of the Major Unit Process Ratings for 69 Plants 94
Most Frequently Occurring Factors Limiting Performance at 69 CPEs 95
Training Approach to Achieve Transfer of CPE Skills 108
Quality Control Checklist for Completed CPEs 109
Quality Control Checklist for Completed CTAs 110
Total System Optimization Considerations for Drinking Water Utilities 111
XI
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Chapter 1
Introduction
1.1 Purpose
Maintaining public health protection at water sup-
ply systems has become more challenging in
recent years with the resistance of some patho-
gens to disinfection using chlorination and an
increase in the immuno-compromised population
(e.g., people with HIV, organ transplant patients,
the elderly). Also, as evidenced by recent out-
breaks; compliance with the 1989 Surface Water
Treatment Rule (SWTR) does not always assure
maximum protection of the public from waterborne
disease (1). Based on this awareness, the U.S.
Environmental Protection Agency (USEPA) is
developing regulations to control contamination
from microbial pathogens in drinking water while
concurrently addressing other concerns such as
disinfection by-products (2,3). These new and
interrelated regulations are moving the water
supply industry toward meeting increasingly more
stringent water treatment requirements.
Research and field work results support optimizing
particle removal from water treatment facilities to
maximize public health protection from microbial
contamination (4,5,6). Since 1988 the Composite
Correction Program (CCP) has been developed
and demonstrated as a method of optimizing
surface water treatment plant performance with
respect to protection from microbial pathogens in
the United States and Canada (7,8). The
approach is based on establishing effective use of
the available water treatment process barriers
against passage of particles to the finished water.
Specific performance goals are used by the CCP
approach to define optimum performance for key
treatment process barriers such as sedimentation,
filtration, and disinfection. These include a
maximum individual sedimentation basin effluent
turbidity goal of less than 2 nephelometric turbidity
units (NTUs) to assure that the integrity of this
barrier is consistently maintained and to provide a
low particle loading to the filters. For the filtration
barrier, optimum performance has been described
as individual filter effluent turbidities of less than
0.1 NTU with a maximum post backwash "spike"
to 0.3 NTU and returning to less than 0.1 NTU in
less than 15 minutes. The disinfection goal has
been based on achieving the log inactivation
requirement for Giardia and/or viruses described in
the SWTR guidance (9).
This handbook is an updated version of the
USEPA Handbook: Optimizing Water Treatment
Plant Performance Using the Composite
Correction Program published in 1991 (7). It is
intended to serve as a resource document for
optimizing the performance of existing surface
water treatment facilities to provide protection from
microbial contamination.
1.2 Background
1.2.1 Wastewater Treatment Compliance
The CCP approach was initially developed to
address compliance problems at wastewater
treatment facilities that were constructed in the late
1960's and 1970's. A survey involving over one
hundred facilities was conducted to identify the
reasons for this noncompliance (10, 11, and 12).
The survey revealed that operations and
maintenance factors were frequently identified as
limiting plant performance, but also disclosed that
administrative and design factors were contributing
limitations. Most importantly, each plant evaluated
had a unique list of factors limiting performance.
Based on these findings, an approach was devel-
oped to identify and address performance
limitations at an individual facility and to obtain
improved performance. Significant success was
achieved in improving performance at many
wastewater treatment facilities without major
capital improvements (13). Ultimately, a handbook
was developed that formalized the evaluation and
correction procedures (14). The formalized
approach was defined as the Composite
Correction Program (CCP), and it consists of two
components—a Comprehensive Performance
Evaluation (CPE) and Comprehensive Technical
Assistance (CTA). As a point of clarification, the
technical assistance phase was initially referred to
as a Composite Correction Program; however, the
name of this phase was changed to
Comprehensive Technical Assistance to better
differentiate the two phases. A CPE is a thorough
review and analysis of a plant's performance-
based capabilities and associated administrative,
operation, and
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Maintenance practices. It is conducted to identify
factors that may be adversely impacting a plant's
ability to achieve permit compliance without major
capital improvements. A CTA is the performance
improvement phase that is implemented if the CPE
results indicate improved performance potential.
During the CTA phase, identified plant-specific fac-
tors are systematically addressed and eliminated.
The wastewater CCP handbook was updated in
1989 to include specific low cost modifications that
could be used to optimize an existing facility's
performance (15). An "expert system" (POTW
Expert) was also developed to supplement the
handbook (16).
1.2.2 Water Treatment Optimization
Based on the state of Montana's successful use of
the CCP approach for improving compliance of
their mechanical wastewater treatment facilities,
state personnel evaluated the feasibility of using
the CCP to optimize the performance of small sur-
face water treatment facilities. With financial
assistance from USEPA Region 8, nine CPEs and
three CTAs were completed from April 1988 until
September 1990. Through these efforts, each of
the existing facilities where CTAs were imple-
mented showed dramatic improvements in the
quality of finished water turbidity. Additionally,
improved performance was achieved at three
plants where only the evaluation phase (CPE) of
the program was completed (17). The encourag-
ing results from Montana's adoption of the CCP
approach to surface water treatment plants led to
the USEPA's Office of Ground Water and Drinking
Water involvement with the program in 1989.
USEPA decided to further develop and demon-
strate use of the CCP approach as it applied to
compliance with drinking water regulations to
ensure its applicability nation-wide. In pursuit of
this goal, a cooperative project was initiated
between USEPA's Office of Ground Water and
Drinking Water, Technical Support Center (TSC)
and Office of Research and Development, Tech-
nology Transfer and Support Division, National
Risk Management Research Laboratory (NRMRL).
This project provided resources to: conduct an
additional twelve CPEs in the states of Ohio,
Kentucky, West Virginia, Maryland, Montana,
Vermont, and Pennsylvania; prepare a summary
report (8); and develop water CCP Handbook (7).
Following these initial efforts, work continued,
through a cooperative agreement between TSC
and the University of Cincinnati, on further refine-
ment and development of the CCP approach. For-
mal efforts were implemented to incorporate the
CCP into state programs. It was anticipated that
application of the CCP by state regulatory person-
nel would achieve desired performance levels with
a minimum financial impact on the utilities in their
jurisdiction. Pilot programs were implemented in
eight states (West Virginia, Massachusetts,
Maryland, Rhode Island, Kentucky, Pennsylvania,
Texas, and Colorado) which focused on develop-
ing CPE capability for state staff. A progressive
training process was developed within each state.
The training process included the completion of a
seminar followed by three CPEs conducted by a
state core team that was facilitated by USEPA and
Process Applications, Inc. Similar pilot programs
were also completed in USEPA Regions 6 and 9.
Typically, state regulatory staff selected the CPE
candidate plants based on their perception of the
plant's inability to meet the SWTR turbidity require-
ments.
The progressive training approach proved to be
successful; however, other issues and challenges
related to implementation within the existing state
regulatory program structure became apparent. As
the state pilot programs progressed, these
challenges to implementation became known col-
lectively as institutional barriers. The impact of
institutional barriers on state-wide optimization
efforts is discussed further in Chapter 3.
1.2.3 Broad-Scale Application of CCP
Concepts
The optimization concepts included within the CCP
approach have been expanded to a variety of
water industry and regulatory activities. A partial
list of current optimization efforts that utilize com-
ponents of the CCP is described below.
• The states of Alabama, Georgia, Kentucky,
and South Carolina, in cooperation with EPA
Region 4, are currently pursuing a multi-state
effort that focuses on optimization of their sur-
face water treatment facilities through a pilot
program based on the application of the CCP
concepts and tools.
• The Partnership for Safe Water is a voluntary
program for enhancing water treatment to
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Provide higher quality drinking water. Organiza-
tions involved in the Partnership include the U.S.
Environmental Protection Agency, American Water
Works Association, Association of Metropolitan
Water Agencies, National Association of Water
Companies, Association of State Drinking Water
Administrators, and the American Water Works
Association Research Foundation. The Partner-
ship utilized the CCP as the basis of its Phase III
comprehensive water treatment self-assessment
(18). Use of the CCP is also being considered for
the Phase IV third party assessment of participat-
ing utilities. As of May 1998, 217 water utilities
serving nearly 90 million people are participating in
the Partnership for Safe Water.
• In 1996 the American Water Works Associa-
tion Research Foundation conducted an opti-
mization workshop with national water quality
and treatment experts from throughout the
industry. As a result of this workshop, a self-
assessment handbook was published by
AWWARF (19). This handbook, which follows
the CCP approach, is intended to be a
resource for water utilities that choose to
conduct a self-assessment to improve
performance.
1.3 Scope
Since publication of the predecessor of this hand-
book in 1991, several modifications have been
made to the CCP and its use for optimizing surface
water treatment plants. In addition, other com-
plementary drinking water optimization activities
(e.g., Partnership for Safe Water) have developed
and continue to have positive impacts in this area.
The purpose of this handbook update is to incor-
porate new information and to integrate the other
complementary programs.
1.3.1 Update of the CCP Approach and
Implementation
Experience gained from over 70 CPEs and 9 CTAs
provides the basis for updating the CCP approach
presented in this handbook. In addition, eight state
pilot programs have provided the basis for the
area-wide application of the CCP. Significant
additions and modifications to the CCP included in
this handbook are:
An expanded discussion of the relationship
between optimized performance and public
health protection.
An expanded definition of optimized perform-
ance goals for microbial contaminant protec-
tion.
Considerations for selection of CPE and CTA
candidates.
Clarification on CCP terminology.
Description and use of the Partnership for Safe
Water software for compiling and analyzing
turbidity data.
Updated process criteria for completing the
major unit process evaluation.
An updated database of completed CPEs and
CTAs and a summary of typical factors found
limiting performance.
Streamlined forms for collection of field data.
1.3.2 Support for Future Regulations
The initial CCP handbook focused on meeting the
requirements of the Surface Water Treatment Rule
(SWTR) (20). As the challenges of protecting the
public health from microbial contamination became
more paramount, the emphasis was shifted from
the SWTR requirements to achieving optimized
performance goals.
Pursuant to the requirements under the 1996
Amendments to the Safe Drinking Water Act
(SDWA), the USEPA is developing interrelated
regulations to control microbial pathogens and
disinfectants/disinfection byproducts in drinking
water, collectively known as the micro-
bial/disinfection byproducts (M/DBP) rules. The
1996 Amendment to the SDWA set a deadline for
promulgation of the Interim Enhanced Surface
Water Treatment Rule (IESWTR) of November
1998. USEPA's Notice of Data Availability (3)
indicates that this rule will include a revised fin-
ished water turbidity requirement of 0.3 NTU, new
individual filter monitoring requirements, and
requirements for states to have authority to
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Require the conduct of CCPs for water utilities that
experience difficulties in meeting the turbidity
requirements of the rule. This handbook is
intended to provide a technical resource to support
the implementation of the IESWTR.
1.3.3 Technical Resource for the
Partnership for Safe Water
This updated handbook is also intended to comple-
ment and enhance the existing Partnership for
Safe Water documentation and program activities.
In addition to supporting the ongoing Phase III self-
assessment activities, the handbook will also
support the anticipated Phase IV activities. A
possible Phase IV approach could involve an inde-
pendent third party review of a utility using the
CCP format. This final step in the Partnership
process ensures that some of the potential limita-
tions of self-assessment (e.g., difficulty in identi-
fying operational and administrative factors) are
not overlooked.
1.3.4 Considerations for Total System
Optimization
Although this handbook is intended to be a techni-
cal resource for surface water treatment facilities to
pursue optimized performance for protection
against microbial contamination, it is recognized
that as the regulations change and optimum per-
formance is pursued, the focus of optimization
activities will expand to other parameters. Antici-
pated future areas for optimization include source
water protection, disinfection by-products, corro-
sion control, groundwater disinfection, and distri-
bution system water quality. This expanded scope
is called total system optimization. Minor additions
are included in this handbook to address some of
these areas; however, future handbook
modifications or additional handbooks are envi-
sioned to more thoroughly address total system
optimization concepts and topics.
1.4 Using the Manual
The primary intended users of this handbook
include regulators (e.g., federal and state agency
personnel) and non-regulators (e.g., utility person-
nel and consultants). To facilitate the use of this
handbook, information has been separated into the
following chapters:
Chapter 1 - Introduction
Chapter 2 - Protection of Public Health
from Microbial Pathogens
Chapter 3 - Assessing Composite Correc-
tion Program Application
Chapter 4 - Comprehensive Performance
Evaluations
Chapter 5 - Comprehensive Technical
Assistance
Chapters - Findings From Field Work
Chapter 7 - Current and Future
Regulation Impacts on Optimization
Chapter 8 - Other CCP Considerations
Table 1-1 provides guidance on where specific
user groups can locate within this handbook
information that is considered pertinent to their
unique interest or intended use.
1.5 References
When an NTIS number is cited in a reference, that
reference is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
1. Kramer,
Disease:
88(3) :66.
M.H., et al. 1996. "Waterborne
1993 and 1994." Journal AWWA,
USEPA. 1997. National Primary Drinking
Water Regulations: Disinfectants and
Disinfection Byproducts; Notice of Data
Availability; Proposed Rule. Fed. Reg.,
62:212:59338 (Novembers, 1997).
USEPA. 1997. National Primary Drinking
Water Regulations: Interim Enhanced Surface
Water Treatment Rule Notice of Data
Availability; Proposed Rule. Fed. Reg.,
62:212:59486 (Novembers, 1997).
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Table 1-1. Information Pertinent to Specific User Groups
User
Purpose
Chapter
Source
USEPA/State
Regulatory
Personnel
Assess application of the CCP as part of an area-wide
optimization strategy
Identify priority plants for CCP application
Review/learn the CPE protocol
Review/learn the CTA protocol
Review CCP database for common factors limiting
performance
Review quality control criteria for assessment of third
party CCPs
Chapter 3
Chapter 3
Chapter 4
Chapter 5
Chapters
Chapter 8
Utility
Personnel
Utilize the CCP as a self-assessment resource
Assess capabilities of CCP providers
Chapters
4&5
Chapter 8
Consultants/
Peer Assessment
Team Members
Review/learn the CPE protocol
Review/learn the CTA protocol
Review CCP database for common factors limiting
performance
Chapter 4
Chapter 5
Chapters
4. Patania, N.L., et al. 1996. Optimization
of Filtration for Cyst Removal. AWWARF,
Denver, CO.
5. Nieminski, E.G., et al. 1995.
"Removing Giardia and Cryptosporidium by
Conventional Treatment and Direct Filtration."
Journal AWWA, 87(9):96.
6. Consonery, P.J., et al. 1996.
"Evaluating and Optimizing Surface Water
Treatment Plants: How Good is Good
Enough?" Paper presented at
AWWA Water Quality Technology Conference,
Boston, MA.
7. Renner, R.C., B.A. Hegg, J.H. Bender,
and E.M. Bissonette. 1991. Optimizing Water
Treatment Plant Performance Using the Com-
posite Correction Program.
91/027, USEPA Center for
Research Information, Cincinnati, OH.
EPA/625/6-
Environmental
8. Renner, R.C., B.A. Hegg, and J.H.
Bender. 1990. Summary Report: Optimizing
Water Treatment Plant Performance with the
Composite Correction Program. EPA 625/8-
90/017, USEPA Center for Environmental
Research Information, Cincinnati, OH.
9. Guidance Manual for Compliance with
the Filtration and Disinfection Requirements for
Public Water Systems Using Surface Water
Sources. 1989. NTIS No. PB-90148016,
USEPA, Cincinnati, OH.
10. Hegg, B.A., K.L. Rakness, and J.R.
Schultz. 1979. Evaluation of Operation and
Maintenance Factors Limiting Municipal
Wastewater Treatment Plant Performance.
EPA 600/2-79-034, NTIS No. PB-300331,
USEPA, Municipal Environmental Research
Laboratory, Cincinnati, OH.
-------
11.
12.
13.
14.
Gray, A.C., Jr., P.E.
Roberts. 1979.
Operation and Maintenance
Paul, and H.D.
Evaluation of
Factors
Limiting
Biological
Wastewater
Treatment
Plant
Performance.
EPA 600/2-79-087, NTIS No. PB-
297491, USEPA, Municipal Environ-
mental Research Laboratory,
Cincinnati, OH.
Hegg, B.A., K.L. Rakness, J.R. Schultz,
and L.D. DeMers. 1980. Evaluation of
Operation and Maintenance Factors
Limiting Municipal Wastewater
Treatment Plant Performance - Phase II.
EPA 600/2-80-129, NTIS No. PB-81-
112864, USEPA, Municipal
Environmental Research Laboratory,
Cincinnati, OH.
Hegg, B.A., K.L. Rakness, and J.R.
Schultz. 1979. A Demonstrated
Approach for Improving Performance
and Reliability of Biological Wastewater
Treatment Plants. EPA 600/2-79-035,
USEPA,
NTIS No.
Cincinnati, OH.
PB-300476,
15.
Hegg, B.A., J.R.
Rakness. 1984.
Improving POTW Performance
Schultz, and K.L.
EPA Handbook:
Using
the Composite Correction Program
Approach. EPA 625/6-84-008, NTIS
No. PB-88184007, USEPA Center for
Environmental Research Information,
Cincinnati, OH.
Hegg. B.A., L.D. DeMers, and J.B.
Barber. 1989. EPA Technology
Transfer Handbook: Retrofitting
POTWs. EPA 625/6-89-020, NTIS No.
PB-90182478, USEPA Center for Envi-
ronmental Research Information,
Cincinnati, OH.
16. Publicly Owned Treatment Works Expert
Users Guide and Software. 1990.
Eastern Research Group, Inc. and
Process Applications, Inc. for USEPA
Center for Environmental Research
Information, Cincinnati, OH.
17. Renner, R.C., B.A. Hegg, and D.L.
Fraser. 1989. "Demonstration of the
Comprehensive Performance
Evaluation Technigue to Assess
Montana Surface Water Treatment
Plants." Presented at the 4th Annual
ASDWA Conference, Tucson, AZ.
18. Bender, J.H., R.C. Renner, B.A. Hegg,
E.M. Bissonette, and R. Lieberman.
1995. "Partnership for Safe Water
Voluntary Water Treatment Plant
Performance Improvement Program
Self-Assessment Procedures." USEPA,
AWWA, AWWARF, Association of
Metropolitan Water Agencies,
Association of State Drinking Water
Administrators, and National
Association of Water Companies.
19. Renner, R.C., and B.A. Hegg. 1997.
Self-Assessment Guide for Surface
Water Treatment Plant Optimization.
AWWARF, Denver, CO.
20. USEPA. 1989. Surface Water
Treatment Rule. Fed. Reg.,
54:124:27486 (June 29, 1989).
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Chapter 2
Protection of Public Health From Microbial Pathogens
2.1 Background
One of the major objectives of water supply
systems is to provide consumers with drinking
water that is sufficiently free of microbial pathogens
to prevent waterborne disease. Water supply
systems can achieve this level of public health
protection by providing treatment to assure that
pathogens found in the raw water supply are
removed or inactivated. The relationship between
optimized water treatment plant performance and
protection of public health from microbial
pathogens is presented in this chapter.
2.2 Waterborne Disease History
Several well documented disease outbreaks that
were associated with the use of untreated surface
water, contaminated well water, treatment plant
deficiencies, and contaminated distribution sys-
tems have occurred over the past 20 years. Dur-
ing this period the most common suspected
causes of waterborne disease outbreaks were the
protozoan parasites Giardia lamblia and
Cryptosporidium parvum (1). These parasites exist
in the environment in an encysted form where the
infectious material is encapsulated such that they
are resistant to inactivation by commonly used
disinfectants. These parasites are transmitted to
their hosts by ingestion of cysts that have been
excreted in the feces of infected humans or ani-
mals. Infection can occur through ingestion of
fecally contaminated water or food or contact with
fecally contaminated surfaces. Recent studies
have indicated that these parasites are routinely
detected in surface water supplies throughout
North America (2, 3, and 4). They can enter
surface water supplies through natural runoff,
wastewater treatment discharges, and combined
sewer overflows.
A recent review of waterborne disease in the U.S.
during the period 1993 through 1994 identified 30
disease outbreaks associated with drinking water.
The outbreaks caused over 400,000 people to
become ill the majority from a 1993 outbreak in
Milwaukee. Twenty-two of the outbreaks were
known or suspected to be associated with
infectious agents and eight with chemical contami-
nants. Giardia or Cryptosporidium was identified as
the causative agent for 10 of the outbreaks, and
six of these systems were associated with a
surface water source. All six systems provided
chlorination, and four also provided filtration. In
the filtered systems, deficiencies in the distribution
system were identified for one outbreak,
inadequate filtration for one, and no apparent
deficiencies were identified in two cases (1).
Cryptosporidium presents a unique challenge to
the drinking water industry because of its
resistance to chlorination and its small size,
making it difficult to remove by filtration.
Cryptosporidiosis is the diarrheal illness in humans
caused by Cryptosporidium parvum.
Cryptosporidiosis outbreaks from surface water
supplies have been documented in the United
States, Canada and Great Britain (5, 6, and 7). A
summary of U.S. outbreaks associated with
surface water supplies is shown in Table 2-1. Five
of the outbreaks were associated with filtered
drinking waters. Three systems (Carroll, Jackson -
Talent, and Milwaukee) were experiencing
operational deficiencies and high finished water
turbidities at the time of the outbreaks. All three
plants utilized conventional treatment processes
that included rapid mix, flocculation, sedimentation,
and filtration. The Clark County outbreak was the
only outbreak associated with a filtered drinking
water for which no apparent treatment deficiencies
were noted. All five systems were in compliance
with the federal drinking water regulations in effect
at that time.
Recent research has shown that free chlorine and
monochloramine provide minimal disinfection of
Cryptosporidium oocysts at the dosage and
detention time conditions found at most treatment
facilities (8). Disinfection requirements based on
CT in the 1989 SWTR guidance were developed
solely on inactivation of Giardia lamblia cysts.
Research conducted by Finch (9) showed
approximately 0.2 log or less inactivation of
Cryptosporidium when free chlorine was used
alone (5 to 15 mg/L @ 60 to 240 min.). Monochlo-
ramine was slightly more effective than free chlo-
rine. Inactivation of Cryptosporidium through the
use of stronger disinfectants (e.g., ozone, chlorine
dioxide) and combined disinfectants is currently
being investigated by the water industry and
research institutions
-------
Table 2-1. U.S. Outbreaks of Cryptosporidiosis in Surface Water Supplies (5)
Location
Bernalillo County, New Mexico
Carroll County, Georgia
Jackson County, Oregon
Milwaukee County, Wisconsin
Cook County, Minnesota
Clark County, Nevada
Year
1986
1987
1992
1993
1993
1994
Type of System
Untreated surface water supply
Treated surface water supply
Medford - chlorinated spring
Talent - treated surface water
Treated surface water supply
Treated surface water supply
Treated surface water supply
Estimated
Number of
Cases
78
13,000
15,000
403,000
27
78
The recent incidence of waterborne disease
associated with protozoan parasites and the resist
trance of some pathogens to conventional
disinfection presents a challenge to the water
industry. Use of a single barrier, such as
disinfection alone, or operation of a conventional
treatment plant that had not been optimized has
contributed to several disease outbreaks. For
surface supplied filtration plants, minimizing con-
sumer's risk from microbial pathogens will require
a proactive approach to water treatment, including
plant optimization.
2.3 Relationship Between Optimized
Performance and Public Health
Protection
2.3.1 Multiple Barrier Strategy
Microbial pathogens, including protozoan para-
sites, bacteria, and viruses, can be physically
removed as particles in flocculation, sedimentation,
and filtration treatment processes or inactivated in
disinfection processes. Consequently, the level of
protection achieved in a water system can be
increased by optimizing the particle removal
processes in a system and by proper operation of
the disinfection processes. In a conventional plant,
the coagulation step is used to develop particles
that can be physically removed by sedimentation
and filtration processes. Effective use of these
processes as part of a multiple barrier strategy for
microbial protection represents an operational
approach for water systems that choose to
optimize performance. This strategy is also being
proposed as a method for addressing
Cryptosporidium in the Interim Enhanced Surface
Water Treatment Rule (10).
Particle removal through a water treatment process
can be monitored and assessed by various
methods including turbidity, particle counting, and
microscopic particulate analysis (MPA). An
increasing number of water systems treating a
surface water supply have turbidimeters installed
to monitor turbidity at various locations throughout
the process. Some systems are supplementing
turbidity monitoring with particle counting and
microscopic particulate analysis. However,
because turbidity monitoring is the most common
method of assessing particle removal in surface
water systems, performance goals based on this
parameter have been developed for the CCP to
define optimized system performance.
The role of multiple treatment barriers in optimizing
water treatment for protection from microbial
pathogens and the associated performance goals
are shown in Figure 2-1. Despite variability in
source water quality, surface water treatment
plants must produce consistently high quality fin-
ished water. To meet this objective, each treatment
process must consistently produce treated water of
a specific quality. To this end,
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Figure 2-1. Multiple barrier strategy for microbial contaminant protection.
Coagulant
Addition
Variable
Quality
Source
Water
Flocculat ion; Sediment at ion
Barrier
Finished
Water
Disinfection
Barrier
performance goals have been established for each
of the treatment barriers in a plant.
When plants include a sedimentation process, the
maximum sedimentation basin effluent turbidity
goal of less than 2 NTU is used to define optimum
process performance. A sedimentation perform-
ance goal ensures the integrity of this barrier and
provides a consistent particle loading to the filtra-
tion process. With respect to optimum particle
removal for the filtration process, the optimum
performance goal is defined as achieving individual
filter effluent turbidities of less than 0.1 NTU.
The performance of the disinfection barrier is
based on the log inactivation requirement for Giar-
dia and virus, as established by the Surface Water
Treatment Rule guidance manual (11). This
document provides tables of the required CT (i.e.,
disinfectant concentration (C) times the time (T)
that the disinfectant must be in contact with the
water) to achieve different levels of inactivation
based on the temperature and pH of the water.
The amount of log inactivation, and hence the CT
value that the plant must achieve, is based on
SWTR guidance.
Inactivation requirements for Cryptosporidium
based on CT have not been established but would
be significantly higher than those for Giardia and
virus. Since inactivation of Cryptosporidium is
difficult to achieve with chlorine disinfection,
maximizing particle removal could represent the
most cost effective and viable option for
maximizing public health protection from this
microorganism.
2.3.2 Basis for Optimization Goals
Strong evidence exists in support of maximizing
public health protection by optimizing particle
removal in a plant. Recent supportive evidence
from water treatment research and field evalua-
tions is summarized below:
• Pilot study work conducted by Patania (12)
showed that when treatment conditions were
optimized for turbidity and particle removal,
very effective removal of both Cryptosporidium
and Giardia was observed. Cryptosporidium
removal ranged from 2.7 to 5.9 logs, and
Giardia removal ranged from 3.4 to 5.1 logs
during stable filter operation. Under the condi-
tions tested, meeting a filter effluent turbidity
goal of 0.1 NTU was indicative of treatment
performance producing the most effective cyst
and oocyst removal. A small difference in filter
effluent turbidity (from 0.1 or less to between
0.1 and 0.3 NTU) produced a large difference
(up to 1.0 log) in cyst and oocyst removal.
• Pilot study and full-scale plant work performed
by Nieminski (13) demonstrated that consistent
removal rates of Giardia and Cryptosporidium
were achieved when the treatment plant was
producing water of consistently low turbidity
(0.1 - 0.2 NTU). As soon as the plant's
performance changed and water turbidity
fluctuated, a high variability in cyst
concentration was observed in collected
effluent samples. The pilot study work,
confirmed by full-scale plant studies, showed
that in a properly
-------
operated treatment plant producing finished
water of 0.1 to 0.2 NTU, either conventional
treatment or direct filtration can achieve 3-log
removal of Giardia cysts.
• An extensive amount of water filtration
research was conducted at Colorado State
University on low turbidity water (14,15).
Using field-scale pilot filters, researchers dem-
onstrated greater than 2-log Giardia removal
when proper chemical coagulation was prac-
ticed on low turbidity raw water (i.e., 0.5 to 1.5
NTU), resulting in filter effluent turbidity values
of less than 0.1 NTU.
• Filter plant performance evaluations conducted
by Consonery (16) at 284 Pennsylvania
filtration plants over the past eight years have
included a combination of turbidity, particle
counting, and microscopic particulate analysis
to assess the performance of plant processes.
The person completing the evaluation uses
this information to rate the plant as to whether
it provides an acceptable level of treatment for
microbial pathogens. Evaluation results have
shown that when filter effluent turbidity was
less than or equal to 0.2 NTU, 60 percent of
the plants were given an acceptable rating.
When filter effluent turbidity was greater than
or equal to 0.3 NTU, only 11 percent of the
plants were given an acceptable rating.
Although this work did not assess plant per-
formance at the 0.1 NTU level, the increased
acceptable rating that occurred when effluent
turbidity was less than 0.2 NTU versus
0.3 NTU indicates the benefit of lowering
finished water turbidity.
An extensive amount of research and field work
results support a filtered water turbidity goal of
0.1 NTU. These findings are also compatible with
a long standing AWWA Policy Statement support-
ing treatment to this level (17). It is important to
understand that achieving this level of filter per-
formance (i.e., 0.1 NTU) does not guarantee that
microbial pathogens will not pass through filters;
however, it represents the current best practice for
water treatment plants to achieve the greatest level
of public health protection.
Particle counting can be used to support and
enhance turbidity measurements, and can be
especially useful when source water turbidity is low
(< 5 NTU). At low source water turbidity levels, it is
difficult to assess the level of particle reduction
being achieved in the filtration process
with turbidity measurements alone. This is due to
the insensitivity of turbidimeters at extremely low
turbidity measurements (i.e., below about
0.05NTU) (18,19,20).
2.4 Optimization Performance Goals
For purposes of this handbook, optimized water
treatment performance for protection against
microbial pathogens is defined by specific meas-
urements and goals. This section presents the
performance goals for surface water treatment
systems. These goals are based on CCP field
work performed by the authors and experience
gained from the Partnership for Safe Water and
state optimization pilot programs. It is important to
note that these goals are the foundation for all
assessments in this handbook and that obtaining
this performance level exceeds present regulatory
requirements.
2.4.1 Minimum Data Monitoring
Requirements
• Daily raw water turbidity
• Settled water turbidity at 4-hour time incre-
ments from each sedimentation basin
• On-line (continuous) turbidity from each filter
• One filter backwash profile each month from
each filter
2.4.2 Individual Sedimentation Basin
Performance Goals
• Settled water turbidity less than 1 NTU
95 percent of the time when annual average
raw water turbidity is less than or equal to
10 NTU.
• Settled water turbidity less than 2 NTU
95 percent of the time when annual average
raw water turbidity is greater than 10 NTU.
2.4.3 Individual Filter Performance Goals
• Filtered water turbidity less than 0.1 NTU
95 percent of the time (excluding 15-minute
period following backwashes) based on the
10
-------
maximum values recorded during 4-hour time
increments.
• If particle counters are available, maximum
filtered water measurement of less than 10
particles (in the 3 to 18 urn range) per milliliter.
(Note: The current state-of-the-art regarding
calibration of particle counters and the inherent
problems in comparisons of readings between
different counters must be considered in using
particle count information to assess optimized
performance. Higher readings than the above
10 particles/mL goal from a counter that is
properly calibrated may be a function of
differences between instruments. Relative
changes in particle count data will be of
greater use in assessing optimized
performance than the absolute values from the
particle counter).
• Maximum filtered water measurement of
0.3 NTU.
• Initiate filter backwash immediately after
turbidity breakthrough has been observed and
before effluent turbidity exceeds 0.1 NTU.
• Maximum filtered water turbidity following
backwash of less than 0.3 NTU.
• Maximum backwash recovery period of
15 minutes (e.g., return to less than 0.1 NTU).
2.4.4 Disinfection Performance Goal
• CT values to achieve required log inactivation
of Giardia and virus.
2.5 Role of the Water Treatment Plant
Staff in Public Health Protection
The information presented in this chapter
demonstrates that the quality of water leaving a
water treatment plant has the potential to directly
impact the health of the consumers of its finished
water. All staff associated with the plant, from the
operator to the highest level administrator, have an
important role in protecting public health and a
responsibility to provide finished water that mini-
mizes the possibility of a disease outbreak. Expe-
rience gained from implementing CCP optimization
activities at plants has demonstrated that, in most
situations, once utility staff become aware of the
importance of achieving optimized performance
goals, they have enthusiastically pursued these
goals through a variety of activities. Later chapters
present comprehensive procedures for assessing
and achieving the level of performance described
in this chapter.
2.6 References
1.
2.
3.
4.
5.
Kramer, M.H., et al. 1996.
ease: 1993 and 1994."
88(3) :66.
"Waterborne Dis-
Journal AWWA,
Chauret, C., et al. 1995. "Correlating
Cryptosporidium and Giardia With Microbial
Indicators." Journal AWWA, 87(11):76.
LeChevallier, M.W., et al. 1995. "Giardia and
Cryptosporidium in Raw and Finished Water."
Journal AWWA, 87(9):54.
States, S., et al. 1997. "Protozoa in River
Water: Sources, Occurrence, and Treatment."
Journal AWWA, 89(9): 74.
Solo-Gabriele, H., et al. 1996. "U.S. Out-
breaks of Cryptosporidiosis." Journal AWWA,
88(9) :76.
Pett, B., et al. 1993. "Cryptosporidiosis Out-
break From an Operations Point of View:
Kitchener-Waterloo, Ontario." Paper
presented at AWWA Water Quality Technology
Conference, Miami, FL.
7. Richardson, A.J., et al. "An Outbreak of
Waterborne Cryptosporidiosis in Swindon and
Oxfordshire." Epidemiol. Infect, 107(3)485.
8. Korich, D.G., et al. 1990. "Effects of Ozone,
Chlorine Dioxide, Chlorine, and Monochlora-
mine on Cryptosporidium parvum Oocyst
Viability." Applied and Environmental Microbi-
ology, 56(5):1423.
9. Finch, G.R., etal. 1995. "Ozone and Chlorine
Inactivation of Cryptosporidium." In
Proceedings of Water Quality Technology
Conference, November 6-10, 1994, San
Francisco, CA. AWWA, Denver, CO.
10. USEPA. 1997. National Primary Drinking
Water Regulations: Interim Enhanced Surface
Water Treatment Rule; Notice of Data
11
-------
Availability; Proposed Rule. Fed. Reg.,
62:212:59486 (Novembers, 1997).
11. Guidance Manual for Compliance With the
Filtration and Disinfection Requirements for
Public Water Systems Using Surface Water
Sources. 1989. NTIS No. PB-90148016,
USEPA, Cincinnati, OH.
12. Patania, N.L., et al. 1996. Optimization of
Filtration for Cyst Removal. AWWARF,
Denver, CO.
13. Nieminski, E.G., et al. 1995. "Removing
Giardia and Cryptosporidium by Conventional
Treatment and Direct Filtration." Journal
AWWA, 87(9):96.
14. Mosher, R.R., et al. 1986. "Rapid Rate Filtra-
tion of Low Turbidity Water Using Field-Scale
Pilot Filters." Journal AWWA, 78(3):42.
15. AI-Ani, M.Y., et al. 1986. "Removing Giardia
Cysts From Low Turbidity Water by Rapid
Sand Filtration." Journal AWWA, 78(5):66.
16. Consonery, P.J., et al. 1996. "Evaluating and
Optimizing Surface Water Treatment Plants:
How Good is Good Enough?" Paper
presented at AWWA Water Quality Technology
Conference, November 1996, Boston, MA.
17. AWWA Statement of Policy. 1968. Quality
Goals for Potable Water, Journal AWWA,
60(12):1317.
18. Cleasby, J.L., et al. 1989. Design and Opera-
tion Guidelines for Optimization of the High
Rate Filtration Process: Plant Survey Results.
AWWARF, Denver, CO.
19. West, T., P. Demeduk, G. Williams, J.
Labonte, A. DeGraca, and S. Teefy. 1997.
"Using Particle Counting to Effectively Monitor
and Optimize Treatment." Paper presented at
AWWA Annual Conference, Atlanta, Georgia.
20. Veal, C., and B. Riebow. 1994. "Particle
Monitor Measures Filter Performance."
Op/tow, 20(5): 1.
12
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Chapter 3
Assessing Composite Correction Program Application
3.1 Introduction
The CCP is currently used as an optimization tool
by several EPA regional offices and state drinking
water programs, and its use could increase as the
result of possible new turbidity requirements when
the Interim Enhanced Surface Water Treatment
Rule (IESWTR) is promulgated (1). However, the
most effective application of the approach has
not always been achieved. Results from CCP
field experience and state pilot programs have
indicated that the CCP is most effective when it is
strategically integrated into a program that focuses
on area-wide optimization of water treatment
systems. This chapter describes a developing
program for regulatory agencies and others to
initiate effective CCPbased optimization activities
through the implementation of an area-wide
optimization model.
3.2 Optimization Program Experience
The experience gained from the transfer of CCP
capability to state drinking water programs is dis-
cussed in Chapter 1. These activities provided
valuable insights into the use of the CCP as an
optimization tool by primacy agencies. The objec-
tive of the early pilot programs was to demonstrate
the capability to effectively transfer CCP skills to
state personnel and to facilitate state-wide
implementation of these activities. Several chal-
lenges became apparent during the imple-
mentation phase. The CCP approach, while
considered extremely valuable, was also
considered to be resource intensive and, therefore,
in competition with other state program activities.
In some states with decentralized programs, field
and central office personnel had difficulty defining
their roles and responsibilities for implementing
optimization activities. Primacy agency policies
guiding the implementation of follow-up efforts
were sometimes challenged (e.g., enforcement
versus assistance responsibilities). As the state
pilot programs progressed, these challenges to
implementation became known collectively as
institutional barriers. In some cases these
institutional barriers were pervasive enough to
prevent state teams trained in CCP procedures
from using their new
technical skills at plants with potential public health
concerns.
Despite the identified institutional barriers, the
continued success of the CCP efforts at individual
facilities could not be ignored (2). In addition,
experience gained from the broad-scale
implementation of the CCP through state
optimization pilot programs and the Partnership for
Safe Water demonstrated that improvement in
water treatment performance could be achieved
through multiple activities that are based on CCP
concepts. Some specific examples include:
• Self-Assessment Based on CCP Can
Positively Impact Performance: Activities
that involve water utilities with the development
and interpretation of their turbidity data have
provided utility staff with a different perspective
on assessing their performance and have
resulted in utility-directed changes to their
operation and system that have improved
performance. Specifically, many water utilities
that have participated in the Partnership for
Safe Water have acknowledged that
associated turbidity data trending activities
have focused them on improving their plant
performance to achieve the Partnership goals
(3).
• Centralized Training Using CCP Principles
Can Impact Multiple Facilities: The applica-
tion of CCP-based principles through
centralized, facilitated training workshops
represents an effective and efficient approach
to assist a group of utilities with achieving
optimization goals. Specifically, a training
facilitator in Pennsylvania, working with a
group of water utilities, used CCP-based
process control procedures in a workshop
format to improve coagulant dosing
understanding and application (4).
• CCP Components Can be Used to Enhance
Existing State Program Activities: Aligning
existing programs (e.g., sanitary surveys,
facility outreach) with the CCP approach can
enhance achievement of performance goals.
For example, existing state sanitary survey
13
-------
programs in Texas and Pennsylvania were
modified to include performance-related CPE
activities (e.g., individual filter evaluations, filter
backwash special studies, process control
interviews) (5).
These findings supported a strategic change in the
CCP direction. The result was an organizational
framework for implementing optimization activities
on an area-wide basis.
3.3 Area-Wide Optimization Model
An area-wide optimization model was developed
that creates an environment to effectively apply
existing resources (e.g., state programs and per-
sonnel) with proven performance improvement
tools (e.g., CCP). Major components of the current
model include: Status, Evaluation, Follow-Up and
Maintenance. These components are des- cribed
in Figure 3-1. This model represents a pro- active
approach to public health protection, serving to
promote continuous improvement and addressing
performance-related issues when they first become
apparent. Pervasive throughout the area-wide
optimization program is an awareness building
process linking treatment plant performance with
public health protection. It is important to note that
an area-wide optimization program is an ongoing
activity with an overall objective to improve the
performance level of all water systems.
Future activities are planned to enhance the area-
wide optimization model. Potential activities
include expanded optimization efforts at surface
water treatment facilities (e.g., disinfection by-
products, source water protection, distribution
system water quality), and optimization activities
related to ground water systems.
3.3.1 Status Component
Status Component activities are designed to
determine the status of water systems relative to
optimized performance goals within a defined area
(e.g., state, region, district). Implementers of
optimization programs then use the results of these
activities in a prioritization process to continuously
focus available resources where they are most
needed, typically at high risk public health systems.
A key activity under the Status Component is
continuous performance monitoring, which can be
used to effectively measure the success of
the various optimization efforts associated with the
model.
3.3.2 Evaluation Component
Evaluation Component activities focus on the
determination of factors limiting performance for
those water systems where performance problems
were identified from Status Component activities.
Existing evaluation programs can be utilized by
incorporating performance-focused activities. The
most resource-intensive evaluation tools, such as
CPEs, are applied at water systems presenting the
greatest risk to public health.
3.3.3 Follow-Up Component
Follow-Up Component activities focus on identify-
ing and developing technical assistance method-
ologies, such as the CTA, to systematically
address performance limiting factors at these sys-
tems. Coordination and training of available tech-
nical resources (e.g., state drinking water program
trainers, non-profit organizations, water system
peers, consultants) are important activities to
assure consistency and effectiveness of this com-
ponent. The degree of involvement of regulatory
agency personnel in follow-up activities may be
impacted by the agency's policies on enforcement
versus technical assistance. In these situations,
policies should be clearly established and agreed
upon by agency staff prior to implementing follow-
up activities.
3.3.4 Maintenance Component
The Maintenance Component formalizes a feed-
back loop to integrate the "lessons learned" from
the various component activities back into the
model. In addition, these "lessons learned" can
provide opportunities to coordinate findings with
other related programs.
3.4 Implementation of an Area-Wide
Model
Figure 3-2 shows the status of filtration plant tur-
bidity performance during a two-year period when
a state was initiating an area-wide optimization
program (5). For those plants that achieved
improved performance levels, this progress was
accomplished through their participation in Status
14
-------
Component activities such as turbidity monitoring
and Follow-Up Component activities such as
chemical feed training. This figure demonstrates
some of the benefits of using the Status
Component to continuously monitor the water
system's level of performance relative to the
desired performance goal. For example, systems
representing the greatest public health risk are
apparent.
In addition, systems showing improved perform
acne can be assessed to ascertain the reasons for
such improvement. In some cases, an awareness
of the importance of optimized performance by the
water system has been identified as a major
contributing factor for the change.
Figure 3-1. Area-wide optimization model.
STATUS COMPONENT
> Establish optimized performance goals.
> Routinely prioritize water systems based on public health risk.
> Continuously monitor and assess performance data.
> Incorporate performance-based activities into existing surveillance
programs.
> Establish feedback mechanism to include monitoring and surveillance data
into ongoing prioritization process.
1
EVALUATION COMPONENT
> Focus existing programs on optimized performance goals.
> Use CCP-based evaluations to identify factors limiting performance.
> Implement CPEs at high risk systems.
> Identify and develop resources to provide CCP-based evaluations.
1
1
FOLLOW-UP COMPONENT
> Establish parties responsible for follow-up component activities.
> Utilize a follow-up protocol that systematically addresses factors limiting
performance.
> Identify and develop resources to provide CCP-based follow-up activities.
> Coordinate existing programs to complement performance improvement
efforts.
1
MAINTENANCE COMPONENT
> Integrate optimization efforts with other drinking water program activities,
such as design review, training, and funding.
> Identify and implement ongoing optimization program refinements.
Figure 3-2. Area-wide treatment plant performance status.
15
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100
D1996 B1997
=p 70
° 60
€ 50
3
1-
0>
H 40
o>
Si
£ 30
20
10
m
1 2 3 4
5 6 7 8 9 10
System
11 12 13 14 15
In the following sections, the Status Component is
further defined to provide a systematic procedure
for assessing applicability of the CCP. The four
steps of the procedure are: 1) establish perform-
ance focused goals to prioritize water systems,
2) assess performance relative to defined optimiza-
tion goals, 3) prioritize water systems based on
selected criteria, and 4) assess the response to the
prioritized water systems.
3.4.1 Establish Criteria to Prioritize Water
Systems
The initial step in the development of a prioritized
facility database is the selection of performance
focused criteria. Example prioritization criteria for
surface water treatment systems are shown in
Table 3-1. In this example, criteria were selected
based on specific performance goals (e.g., tur-
bidity) and operations and management practices
that support optimized performance (e.g., process
control, staffing level).
Points are applied to each criterion relative to their
potential to impact public health risk. For example,
the ability to meet the filtered water turbidity goal of
0.1 NTU is given a higher number of points
as the percentage of time meeting this goal
decreases. Additional data required to complete
the assessment outlined in Table 3-1 can usually
be obtained from existing resources (e.g., plant
performance charts, water system monthly reports,
sanitary surveys). It may be necessary to expand
the data collection requirements from water
systems to assure that sufficient performance
focused information is available for this activity.
3.4.2 Assess Water System Performance
Relative to Optimization Goals
Typically, each water system utilizing a surface
water source collects and records plant perform-
ance data on a daily basis. These data can be
entered into a computer by either water system
staff, regulators, or others on a monthly basis using
a spreadsheet program such as the Partnership for
Safe Water software included in Appendix A. Data
are then used to develop turbidity trend charts and
percentile tables. Specific types of turbidity data
included in the assessment are listed below.
Raw water turbidity (daily value; maximum
value recorded for the day preferred).
16
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• Sedimentation basin effluent turbidity (daily;
maximum value recorded for the day pre-
ferred).
• Filter effluent turbidity (daily for each filter;
maximum value preferred; combined filter or
finished water as alternative).
A minimum of 12 months of turbidity data is
desired to assess water system performance under
variable source water conditions. An example tur-
bidity monitoring chart for a surface water treat-
ment system is shown in Figure 3-3. Raw, settled,
and filtered water turbidity values are plotted for a
12-month period. In this example, overall filtered
water quality is excellent; however, occasional
turbidity spikes occur in the filtered water that
correspond to increases in the raw water turbidity.
3.4.3 Prioritize Water Systems Based on
Selected Criteria
When prioritization criteria data are available for
the water systems that are to be included in the
area-wide optimization program, each of the sys-
tems can be assigned points, as shown in Ta-
ble 3-2. The water systems are then ranked from
highest priority (i.e., most points) to lowest priority
(i.e., least points). Ideally, a prioritized water
Table 3-1. Example Prioritization Criteria for Surface Water Systems
Prioritization Criteria
Has the water system had an imminent health violation within the last two (2) years
(turbidity, CT, positive coliform)?
Does the water system achieve the optimization turbidity goal for filtered water of
0.1 NTU?
> 95 % time
50 - < 95 % time
< 50 % time
Does the water system experience post filter backwash turbidity of > 0.3 NTU for
greater than 15 minutes?
Does the water system achieve the optimization turbidity goal for settled water (e.g., <
2 NTU 95% time)?
Does the water system have operation and treatment problems (e.g., improper
chemical feed, improper jar testing, inadequate procedures)?
Does the water system experience sedimentation and filtered water turbidity variability
given changing raw water quality?
Does the water system lack administrative support (e.g., inadequate funding,
inadequate support of system operational needs)?
Does the water system have poor source water quality (e.g., high turbidity variability,
high presence of protozoan parasites)?
Does consistent, high-quality source water lead to complacency in the operation and
management of the water system?
Does the water system fail to monitor raw, settled and filtered water turbidity?
Points
(0 if No)
10-15
0
5
10
0-10
0-5
0-5
0-5
0-5
0-3
0-3
0-3
Figure 3-3. Example turbidity monitoring data for 12-month period.
17
-------
1000
95 % time settled turbidity <97 NTU
95 % time filtered turbidity < 0.1 NTU
1/1/95 2/1/95 3/4/95 4/4/95 5/5/95 6/5/95 7/6/95 8/6/95 9/6/95 10/7/95 11/7/95 12/8/95
Table 3-2. Example Prioritization Database
Water
System
2
1
5
3
7
6
10
9
8
4
Violations
12
15
10
10
0
0
0
0
0
0
Filter
Turbidity
Performance
5
10
5
5
2
2
2
0
2
0
Settled
Turbidity
Performance
5
3
3
3
3
2
4
3
3
2
O&M
Problems
5
5
3
5
2
3
3
3
1
0
Variability
5
3
3
3
3
3
3
2
3
0
Backwash
Spikes
5
5
4
3
4
2
3
0
0
0
Admin
Support
5
2
2
0
3
4
5
4
2
2
Poor
Source
Water
0
0
2
0
2
0
0
3
3
0
Complacency
& Reliability
3
0
0
0
4
4
0
4
0
0
Lack of
Monitoring
3
3
3
3
4
5
3
0
0
0
Total
Points
48
46
35
32
27
25
23
19
14
4
system database would include each system and
their total point score. This database should be
updated routinely (e.g., quarterly) to reflect new
information from system reports, field surveys, and
performance data.
3.4.4 Assess Response to Prioritized
Water Systems
Information gained from the prioritization database
provides the basis for determining the appropriate
response to achieving performance goals. For ex-
ample, some specific actions that could result from
an area-wide prioritization database include:
• High scoring utilities:
• Apply CCP
• Modifications/major construction
• Enforcement action
Moderate scoring utilities:
Performance-focused sanitary survey
18
-------
• Centralized training using CCP principles
(focus on high ranking performance limit-
ing factors)
• Low scoring utilities:
• Telephone contact
• Self-assessment
• Maintain or reduce frequency of sanitary
surveys
Use of a performance-based prioritization
database provides assurance that the identified
responses are commensurate with the level of
public health risk. Following this approach, the
CCP, a proven process that can result in optimized
performance, is applied at water systems that have
the highest public health risk.
3.5 References
1. USEPA. 1997. National Primary Drinking
Water Regulaions: Interim Enhanced Surface
Water Treatment Rule; Notice of Data Avail-
ability; Proposed Rule. Fed. Reg.,
62:212:59486 (Novembers, 1997).
2. Renner, R.C., B.A. Hegg, J.H. Bender, and
E.M. Bissonette. 1993. "Composite Correc-
tion Program Optimizes Performance at Water
Plants." JournalAWWA, 85(3):67.
3. Pizzi, N.G., B.A. Hegg, J.H. Bender, and
J. DeBoer. 1997. "Cleveland's Self-
Assessment and Contribution to the
Partnership for Safe Water Peer Review
Process." Proceedings - AWWA Annual
Conference, June 1997, Atlanta, GA.
4. Jesperson, K. 1997. "Pilot Program Ripples
Through PA DEP." E-Train, Published by the
National Environmental Training Center for
Small Communities.
5. Hoover, J.T., R.J. Lieberman, L.D. DeMers,
and J. Borland. 1997. "Public Water Supply
Area-Wide Optimization Strategy." Presenta-
tion at the Association of State Drinking Water
Administrators Annual Conference, October
1997, Savannah, GA.
19
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Chapter 4
Comprehensive Performance Evaluation
4.1 Introduction
This chapter provides information on the evaluation
phase of the CCP, which is a two-step process to
optimize the performance of existing surface water
treatment plants. For purposes of this handbook,
optimization is defined as achieving the
performance goals as outlined in Chapter 2. The
evaluation phase, called a Comprehensive
Performance Evaluation (CPE), is a thorough
review and analysis of a facility's design
capabilities and associated administrative,
operational, and maintenance practices as they
relate to achieving optimum performance from the
facility. A primary objective is to determine if
significant improvements in treatment performance
can be achieved without major capital
expenditures. This chapter covers three main
areas related to CPEs. First, a CPE methodology
section presents all of the major technical
components of a CPE and their theoretical basis.
The following section discusses how to implement
the CPE methodology when conducting a CPE.
This section also includes many practical
considerations based on the field experience
gained by conducting actual CPEs. The last sec-
tion of this chapter includes a case history of an
actual CPE.
4.2 CPE Methodology
Major components of the CPE process include:
1) assessment of plant performance, 2) evaluation
of major unit processes, 3) identification and priori-
tization of performance limiting factors,
4) assessment of applicability of the follow-up
phase, and 5) reporting results of the evaluation.
Although these are distinct components, some are
conducted concurrently with others during the
conduct of an actual CPE. A discussion of each of
these components follows.
4.2.1 Assessment of Plant Performance
The performance assessment uses historical data
from plant records supplemented by data collected
during the CPE to determine the status of a facility
relative to achieving the optimized performance
goals, and it starts to identify possible causes of
less-than-optimized performance. To achieve
optimized performance, a water treatment plant
must demonstrate that it can take a raw water
source of variable quality and produce a consistent
high quality finished water. Further, the perform-
ance of each unit process must demonstrate its
capability to act as a barrier to the passage of par-
ticles at all times. The performance assessment
determines if major unit treatment processes con-
sistently perform at optimum levels to provide
maximum multiple barrier protection. If perform-
ance is not optimized, it also provides valuable
insights into possible causes of the performance
problems and serves as the basis for other CPE
findings.
4.2.1.1 Review and Trend Charting of Plant
Operating Records
The performance assessment is based on turbidity
data located in plant operating records. These
records, along with a review of laboratory quality
control procedures (especially calibration of turbi-
dimeters) and sample locations, are first assessed
to ensure that proper sampling and analysis have
provided data that is representative of plant per-
formance. The next step is to prepare trend
graphs of the maximum daily turbidities for the raw
water, settled water, finished water, and individual
filter effluents, if available. Data for the most
recent one-year period is used in this evaluation
and can typically be obtained from the plant's
process control data sheets. Maximum values are
used in these trend charts since the goal is to
assess the integrity of each barrier at its most vul-
nerable time. A twelve-month period is utilized
because it includes the impacts of seasonal varia-
tions and provides a good indicator of long term
performance.
Data development can be accomplished by using a
commercial computer spreadsheet. However,
spreadsheets that work with several commercially
available spreadsheet programs were developed
for the Partnership for Safe Water (1) and have
proven valuable in making the desired
performance assessment trend charts. The
Partnership data development spreadsheets and a
description of how to use them are provided in
Appendix A.
21
-------
Figure 4-1 shows an example of performance
assessment trend charts prepared for a typical
plant. In addition to the trend charts, a percentile
analysis can also be made using the data to
determine the percent of time that raw, settled and
finished water quality is equal to or less than a
certain turbidity. This information can be used to
assess the variability of raw water turbidity and the
performance of sedimentation and filtration unit
processes. The percentile analysis of settled and
finished water quality are useful to project a plant's
capability to achieve optimized performance
objectives. An example of the percentile analysis
for the data shown in Figure 4-1 is presented in
Table 4-1. It is noted that the trend charts and the
percentile analysis are developed as a portion of
the Partnership data development spreadsheets
and are shown in Appendix A. The data provided
in Table 4-1 was taken from the yearly summary
on the percentile portion of the software output. It
is often useful to summarize the data in this
fashion since the spreadsheet provides a
significant amount of information.
Once the trend charts and percentile analysis have
been developed, interpretation of the data can be
accomplished. A good indication of the stability of
plant operation can be obtained from comparing a
plot of raw water, settled water and finished water
turbidity. When comparing these data, the
evaluator should look for consistent settled and
filtered water turbidities even though raw water
quality may vary significantly. In Figure 4-1 the raw
water turbidity shows variability and several
significant spikes. Variability is also evident in the
settled and finished water turbidities. In addition a
raw water "spike" on March 9th carried through the
plant resulting in a finished water turbidity close to
1 NTU. These "pass through variations and spikes"
indicate that the performance of this plant is not
optimized and that a threat of particle and possibly
pathogen passage exists. In plants that have
consistent low raw water turbidities, periodic spikes
in sedimentation and finished water that appear
related to changes in raw water quality may
indicate that the plant staff are complacent and
lack process control skills. The administrative
support for the plant may also play a role in this
complacency.
Optimized performance for the sedimentation basin
in the example is assessed based on achieving
settled water turbidities consistently less than 2
NTU in 95 percent of the samples, since the
average raw water turbidity exceeds 10 NTU (e.g.,
19 NTU). In the example shown, the settled
water turbidity was less than or equal to 5.3 NTU at
the 95th percentile. This indicates less-than-
optimum performance from this process barrier.
Optimized performance for the finished water is
assessed based on achieving 0.1 NTU or less in
95 percent of the samples. For the example
shown, the finished water was 0.48 NTU or less in
95 percent of the samples; consequently, optimum
performance was not being achieved by this
barrier. In summary, the interpretation of the data
shown in Figure 4-1 and Table 4-1 indicates that
optimum performance is not being achieved, and it
will be necessary to identify the causes for this
less-than-optimum performance during the conduct
of the CPE.
CPEs conducted to date have revealed that oper-
ating records often do not have adequate informa-
tion to complete the performance assessment.
Maximum daily turbidities are often not recorded
and settled water turbidity information often does
not exist. The fact that this type of information is
not available provides a preliminary indication
about the priority that the utility has on pursuing
achievement of optimum performance goals.
Particle data, when available, can also be used to
assess optimized performance. Typically, particle
data will provide a more sensitive assessment of
filter performance when the turbidity is less than
0.1 NTU. Particle counts will normally show more
subtle changes in filter performance than indicated
by the turbidimeters. This does not mean that
turbidimeter information should be ignored when
particle count data is available. It is important that
the evaluator have confidence in the filter's per-
formance relative to producing water that is less
than 0.1 NTU.
4.2.1.2 Supplemental Data Collection
Plant records used for the trend charting perform-
ance assessment activities are usually based on
clean/veil samples collected at four-hour intervals
as required by regulations. Complete assessment
of optimized performance, however, also requires
knowledge of the instantaneous performance of
individual treatment units; especially for individual
filters. Many plants currently do not have separate
turbidimeters on individual treatment units, and
most of these do not have equipment that will
provide continuous recording of the data. To sup-
plement the performance data available from the
22
-------
Figure 4-1. Example performance assessment trend charts.
Raw Water
Sep-94 Oct-94 Nov-94 Dec-94 Jan-95 Feb-95 Mar-95 Apr-95 May-95 Jun-95 Jul-95 Aug-95
Settled Water
25.00
0.00
Finished Water
Dec-94 Jan-95 Feb-95 Mar-95 Apr-95 May-95 Jun-95 Jul-95 Aug-95
23
-------
Table 4-1. Percentile Distribution Analysis of
Water Quality Data*
Percent of Time
Values
Less Than or
Equal To
Value Shown
50
75
90
95
Average
Raw
Water
Turbidity
NTU
17
22
29
34
19
Settled
Water
Turbidity
NTU
2.1
3.0
4.1
5.3
2.6
Finished
Water
Turbidity
NTU
0.30
0.38
0.44
0.48
0.31
*Percentile analysis is based on peak daily turbidities measured
for each sample source for the twelve-month evaluation period.
plant records, additional turbidity performance data
is usually collected during the CPE.
Optimum performance cannot be assessed without
an evaluation of individual filter performance.
Finished water samples are often obtained from
the clean/veil. The clean/veil "averages" the
performance of the individual filters and thus may
mask the impact of damaged underdrains, of
"blown media" on an individual filter, or of
malfunctioning filter rate control valves. A
malfunctioning individual filter could allow the
passage of sufficient microbial contamination to
threaten public health despite the plant as a whole
producing a low finished water turbidity. A second
reason for the need of supplemental data
collection is that most plants do not keep records
of their filter backwash recovery profiles. These
are needed to assess if the plant is meeting the
filter backwash recovery optimized performance
goals.
Since this instantaneous individual filter perform-
ance data is so critical, it is usually best if one or
two independently calibrated on-line continuous
recording turbidimeters are available during the
CPE. Along with providing the ability to assess the
performance of individual filters, these units also
allow a quality control check on the plant's
monitoring equipment. On-line units will provide
more information on the impacts of various
operational changes such as filter backwashes and
changes in flow rates. Grab sampling from
individual filters can provide useful insights about
the performance of individual filter units, but a
continuous recording turbidimeter provides more
accurate results. Grab sampling to assess
individual filter performance is also cumbersome
because many samples at short time increments
(e.g., 1 minute intervals) are needed to get an
accurate filter backwash recovery profile. It is
noted, however, that in a plant with multiple filters it
is advantageous to collect grab samples from
individual filters for turbidity analysis before
selecting the filter that is to be monitored by the
continuous recording turbidimeter. The filter
demonstrating the poorest performance should be
selected for analysis. If all filters demonstrate
similar performance, it is desirable to install the
online turbidimeter on a filter to be backwashed to
allow observation of the backwash recovery profile.
Continuous monitoring and recording of turbidity
from each filter allows identification of short term
turbidity excursions such as: impacts of malfunc-
tioning filter rate control valves, impacts of hy-
draulic changes such as adjustments to plant flow,
impacts of hydraulic loading changes during
backwash of other filters, impacts of plant start-up,
and impacts of backwashing on individual filters.
When the plant staff can properly apply process
control concepts they can eliminate these varia-
tions in turbidity either through proper control of the
hydraulic loadings to the treatment processes or
through chemical conditioning. These types of
turbidity fluctuations on the filter turbidimeters are
often indicators of inadequate process control that
must be verified during the CPE.
Figure 4-2 shows results of continuous recording of
turbidity from a filter that was backwashed. As
indicated, optimized performance of 0.1 NTU or
less was not being achieved prior to the backwash.
Also, the post backwash turbidity spike of 0.95
NTU exceeded the optimized performance goal of
0.3 NTU, and the filtered water turbidity did not
recover to 0.1 NTU or less within a 15-minute
period.
These same goals are also used to assess back-
wash spikes and optimized performance at plants
that use filter-to-waste. The 15-minute recovery
period starts when the filter begins filtering after
backwash even though the plant may filter-to-
waste for longer periods of time. The rationale for
24
-------
Figure 4-2. Example of individual filter monitoring.
i, °-50
.C1
jo
•B 0.40
Resume Filtration
Begin Backwash
\
*»««»»«««»<»»»«»•
Plant Flow Reduced - Limited Chlorine Available
4 6 8 10 12 14 16 18 20
Time From Start of Continuous Filter Monitoring - hrs
this approach is that the control of backwash
spikes is a key indicator of the adequacy of the
plant's process control program and chemical con-
ditioning of the filters. Waiting until the filter-to-
waste is completed to assess backwash spikes
could hide key information relative to the process
control capability of the plant staff.
As discussed above, many plants do not collect
and/or record data on sedimentation basin per-
formance. During a CPE, therefore, it may be
necessary to collect sedimentation basin perform-
ance data to assess if this process is meeting the
optimized performance goals. It may be necessary
to collect data on individual sedimentation units if
one appears to have worse performance than the
others. Usually, grab sampling of these units will
suffice.
4.2.2 Evaluation of Major Unit Processes
4.2.2.1 Overview
The major unit process evaluation is an assess-
ment of treatment potential, from the perspective of
capability of existing treatment processes to
achieve optimized performance levels. If the
evaluation indicates that the major unit processes
are of adequate size, then the opportunity to opti
maze the performance of existing facilities by
addressing operational, maintenance or
administrative limitations is available. If, on the
other hand, the evaluation shows that major unit
processes are too small, utility owners should
consider construction of new or additional
processes as the initial focus for pursuing
optimized performance.
It is important to understand that the major unit
process evaluation only considers if the existing
treatment processes are of adequate size to treat
current peak instantaneous operating flows and to
meet the optimized performance levels. The intent
is to assess if existing facilities in terms of concrete
and steel are adequate and does not include the
adequacy or condition of existing mechanical
equipment. The assumption here is that if the
concrete and steel are not of adequate size then
major construction may be warranted, and the
pursuit of purely operational approaches to
achieve optimized performance may not be
prudent. The condition of the mechanical
equipment around the treatment processes is an
important issue, but in this part of the CPE it is
assumed that the potential exists to repair and/or
replace this equipment without the disruption of the
plant inherent to a major construction project.
These types of issues are handled in the factors
limiting performance component of the CPE,
discussed later in this chapter. It is also projected
in the major unit
25
-------
process evaluation that the process control
requirements to meet optimized performance goals
are being met. By assuming that the equipment
limitations can be addressed and that operational
practices are optimized, the evaluator can project
the performance potential or capability of a unit
process to achieve optimized performance goals.
The evaluation approach uses a rating system that
allows the evaluator to project the adequacy of
each major treatment process and the overall plant
as either Type 1, 2 or 3, as graphically illustrated in
Figure 4-3. Type 1 plants are those where the
evaluation shows that existing unit process size
should not cause performance difficulties. In these
cases, existing performance problems are likely
related to plant operation, maintenance, or
administration. Plants categorized as Type 1 are
projected to most likely achieve optimized
performance through implementation of non-
construction-oriented follow-up assistance (e.g., a
CTA as described in Chapter 5).
believed to be required to achieve optimized per-
formance goals. Although other limiting factors
may exist, such as the operator's lack of process
control capability or the administration's unfamili-
arity with plant needs, consistent acceptable per-
formance cannot be expected to be achieved until
physical limitations of major unit processes are
corrected.
Owners with a Type 3 plant are probably looking at
significant expenditures to modify existing facilities
so they can meet optimized performance goals.
Depending on future water demands, they may
choose to conduct a more detailed engineering
study of treatment alternatives, rate structures, and
financing mechanisms. CPEs that identify Type 3
facilities are still of benefit to plant administrators in
that the need for construction is clearly defined.
Additionally, the CPE provides an understanding of
the capabilities and weaknesses of all existing unit
processes, operation and maintenance practices,
and administrative policies.
Figure 4-3. Major unit process evaluation
approach.
Plant Administrators or
Regulators Recognize Need to
Evaluate or Improve Plant
Performance
Evaluation of
Major Unit Processes
Type 1
Major Unit Processes
Are Adequate
Type 2
Major Unit Processes
Are Marginal
The Type 2 category is used to represent a situa-
tion where marginal capability of unit processes
could potentially limit a plant from achieving an
optimum performance level. Type 2 facilities have
marginal capability, but often these deficiencies
can be "operated around" and major construction is
not required. In these situations, improved process
control or elimination of other factors through
implementation of a CTA may allow the unit proc-
ess to meet performance goals.
Type 3 plants are those in which major unit proc-
esses are projected to be inadequate to provide
required capability for the existing plant flows. For
Type 3 facilities, major modifications are
As discussed in Chapter 2, water suppliers have a
key role to play in public health protection and a
responsibility to water quality that they must meet
on a continuous basis. If a facility is found to pose
a severe health risk because of its performance,
some action must be taken even if it is found to be
Type 3. In the short term, other weaknesses in the
plant that are identified in other components of the
CPE may need to be addressed to improve
performance as much as possible. If these actions
do not result in satisfactory performance, a boil
water order or water restriction may have to be
implemented until modifications are completed and
performance is improved. This may require
coordination with appropriate state regulatory
agencies. The water system must also make long
term plans to upgrade or replace deficient
treatment processes.
Another situation that must be considered in com-
pleting the major unit process evaluation is the age
and condition of the plant. Though the CCP
approach attempts to minimize construction of new
facilities, some plants are so old that they are not
structurally sound and/or contain antiquated
equipment (e.g., outdated filter rate-of-flow control
valves). It is possible that the major unit process
evaluation will show these plants as Type 1
because they were designed based on conserva-
tive loadings and/or the water demand of the area
has not increased. In these cases, the owner of
the plant will have to look at the plant needs, both
long term and short term. In addition, the plant
26
-------
may be able to optimize performance to meet short
term public health protection, but will also have to
consider construction of a new plant in order to
provide high quality water on a long term basis.
4.2.2.2 Approach
Major unit processes are evaluated based on their
capability to handle current peak instantaneous
flow requirements. The major unit processes
included in the evaluation are flocculation, sedi-
mentation, filtration and disinfection. These proc-
esses were selected for evaluation based on the
concept of determining if the basin sizes are ade-
quate. The performance potential of a major unit
process is not lowered if "minor modifications",
such as providing chemical feeders or installing
baffles, could be accomplished by the utility. This
approach is consistent with the CPE intent of
assessing adequacy of existing facilities to deter-
mine the potential of non-construction alternatives.
Other design-related components of the plant pro-
cesses, such as rapid mix facilities, are not
included in the major unit process evaluation but
rather are evaluated separately as factors that may
be limiting performance. For purposes of the major
unit process evaluation, these components are
projected to be addressed through "minor
modifications." It is important to note that the
major unit process evaluation should not be
viewed as a comparison to the original design
capability of a plant. The major unit process
evaluation is based on an assessment of existing
unit processes to meet optimized performance
goals. These goals are most likely not the goals
that the existing facility was designed to achieve.
A performance potential graph is used to evaluate
major unit processes. As an initial step in the
development of the performance potential graph,
the CPE evaluators are required to use their judg-
ment to select loading rates which will serve as the
basis to project peak treatment capability for each
of the major unit processes. It is important to note
that the projected capability ratings are based on
achieving optimum performance from flocculation,
sedimentation, filtration and disinfection such that
each process maintains its integrity as a "barrier" to
achieve microbial protection. This allows the total
plant to provide a "multiple barrier" to the passage
of pathogenic organisms into the distribution
system.
The projected unit process treatment capability is
then compared to the peak instantaneous operat-
ing flow rate experienced by the water treatment
plant during the most recent twelve months of
operation. If the most recent twelve months is not
indicative of typical plant flow rates, the evaluator
may choose to review a time period considered to
be more representative. The peak instantaneous
operating flow is utilized because unit process per-
formance is projected to be most challenged during
these peak loading events and it is necessary that
high quality finished water be produced on a
continuous basis.
An example performance potential graph is shown
in Figure 4-4. The major unit processes evaluated
are shown on the left of the graph and the various
flow rates assessed are shown across the top.
Horizontal bars on the graph depict projected
capability for each unit process, and the vertical
line represents the actual peak operating flow
experienced at the plant. Footnotes are used to
explain the loading criteria and conditions used to
rate the unit processes.
Figure 4-4. Example performance potential
graph.
Unit Process
Flocculation*
Sedimentationt
Filtration*
Disinfection
Flow (MGD)
10 20 30 40 50 60
i
Rate = 45 Iki
1
aneous
3W
GD
Rated at 20 min hydraulic detention time (HOT); assumes
variable speed drive would be added to existing Flocculator.
Rated at 0.6 gpm/sq ft surface overflow rate (SOR); 12.5 ft
depth.
Rated at 4 gpm/sq ft hydraulic loading rate (HLR); dual
media; assumes adequate media depth and backwashing
capability.
Rated at CT = 127 mg/L-min based on 2.4 mg/L CI2
residual, 53-min HOT, total 4 log Giardia reduction (1.5 log
by disinfection), pH = 8, temperature = 5 °C, 10% of usable
clean/veil volume, and depth in clean/veil maintained >9feet.
27
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The approach to determine whether a unit process
is Type 1, Type 2 or Type 3 is based on the rela-
tionship of the position of horizontal bars to the
position of the peak instantaneous operating flow
rate. It is noted that if a plant operates at peak
instantaneous operating flow with one unit out of
service, then the evaluation would be based on
these conditions. As presented in Figure 4-5, a
unit process would be rated Type 1 if its projected
capability exceeds the peak instantaneous operat-
ing flow rate, Type 2 if its projected capability was
80 to 100 percent of peak, or Type 3 if its projected
capability is less than 80 percent of peak.
Figure 4-5. Major unit process rating criteria.
Unit Process
Flocculation
Sedimentation
Filtration
Disinfection
Row
Typel
Type 2
Typsl
Type3
> 100% of peak flow
80 - 100% of peak flow
> 100% of peak flow
< 80% of peak flow
Peak Instantaneous Operating Flow Rate
&
4.2.2.3 Determining Peak Instantaneous
Operating Flow
A key aspect of the major unit process evaluation
is the determination of peak instantaneous oper-
ating flow rate. This is the flow rate against which
the capability of each of the major unit processes is
assessed. Based on this assessment, the unit
process type is projected, which determines if
major construction will be required at the plant.
An additional evaluation of both the peak instanta-
neous operating flow rate and plant operating time
allows the evaluator to determine if plant capability
can be enhanced by reducing the plant flow rate
and extending the plant operating time. Some
plants only operate for part of the day and shut
down at night. In these cases, the peak instanta-
neous operating flow rate of the plant could be
occurring only over a 12-hour period, and the plant
may be able to operate at half the flow rate for a
24-hour period. In this example, a unit process
that received a Type 3 rating may be able to
achieve Type 2 or Type 1 status. When a plant
decides to reduce flows, however, there probably
will be additional expenses for staff to operate the
plant for the extended time periods needed to meet
water demand. Basically the plant is trading off the
costs for staff with those required to construct
additional treatment capacity. In addition, it may
be possible for a community to take steps to
reduce demand by activities such as increasing
water rates, water rationing, or leak detection and
repair of their distribution system.
The peak instantaneous operating flow rate and
unit process loadings need to be carefully selected
and assessed by the evaluator since these
parameters in the unit process evaluation can
direct the utility either toward construction or
pursuing optimization with existing facilities. During
a CPE every effort should be made to direct the
plant toward optimization with existing facilities. In
completion of the major unit process evaluation,
this means that selection of parameter(s) such that
it directs a plant to pursue major construction
should be made after much consideration of the
impacts on optimized performance and public
health protection.
Peak instantaneous operating flow rate is identified
through review of operating records and observa-
tion of operation practices and flow control capa-
bility. A review of plant flow records can be mis-
leading in determining peak instantaneous flow.
For example, records may indicate a peak daily
water production value, and discussions with the
operating staff may indicate that the plant was not
operated for a full 24-hour period. If the recorded
production was not for the full 24-hour period but
had been determined by calculating an average
flow rate over the 24-hour period, a rate that was
less than the actual peak instantaneous operating
flow would be identified. Peak instantaneous
operating flow is that flow rate which the unit
processes actually receive. For example, a plant
may have two constant speed raw water pumps
each capable of pumping at 1,000 gpm. If only
one is operated at a time for 12 hours per day, the
peak instantaneous flow rate would be established
at 1,000 gpm. If, however, operating personnel
indicate that a control valve is used to throttle the
pump to 750 gpm on a continuous basis, the peak
instantaneous flow rate would be established at
750 gpm. In a third situation, the plant staff may
operate both pumps during times of the peak water
demand (e.g., summer) which ideally would make
the peak instantaneous flow rate 2,000gpm. It is
noted that the peak flow rate when both pumps are
operated is often lower than when using a single
pump. The maximum value for the two pumps
should be used even if the
28
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plant only operates this way for a few days at a
time.
4.2.2.4 Rating Individual Unit Processes
The next step in preparing a performance potential
graph is selecting appropriate loading rates for
each of the major unit processes. Once the load-
ing rates are selected, the performance potential of
a unit process to achieve optimized performance
goals can be projected. The criteria presented in
Table 4-2 can be used to assist in selecting load-
ing rates for individual unit processes. There is a
wide range in the criteria which can translate into
large differences in the projected unit process
capabilities. Criteria to help in "adjusting" loading
rates for site-specific conditions are provided.
However, using the performance potential graph
approach requires a great deal of judgment on
behalf of an experienced water treatment plant
evaluator to properly project capability of a major
unit process.
It is noted that other resources are available to
assist less experienced evaluators in completing a
major unit process evaluation. One of these
resources is the Water Advisor expert system (2)
which prepares a major unit process evaluation
based on pre-selected loading rates. This pro-
gram, developed to assess plants based on 1989
SWTR compliance, is several years old; and the
loading rates have not been recently updated.
When using this program, the evaluator has no
opportunity to change loading rates based on the
unique conditions of a particular plant. An inexpe-
rienced evaluator may find this a useful tool to
check the major unit process evaluation completed
using the procedures in this handbook. A further
description of this software is contained in Appen-
dix B.
An additional resource is the Partnership for Safe
Water software (1). A copy of this software, as
well as a description of its use, is located in Ap-
pendix C. The Partnership for Safe Water software
provides suggested loading rates based on
industry standards and operating experience, but
also allows the CPE evaluator to easily change
loading rates and plot different performance poten-
tial graphs.
The criteria presented in Table 4-2 are considered
to be the most current, relative to achieving
Table 4-2. Major Unit Process Evaluation Criteria2'
2,3,4,5,6,7)
Hydraulic
Flocculation Detention Time
Base
Single-Stage
Multiple Stages
Temp <=5°C
Temp >5°C
Temp <=5°C
Temp > 5°C
20 minutes
30 minutes
25 minutes
20 minutes
15 minutes
Filtration Air Binding Loading Rate
Sand Media
Dual/Mixed Media
Deep Bed
(Typically anthracite
>60 in. in depth)
None
Exists
None
Exists
None
Exists
2.0 gpm/ft2
1 .0-1 .5 gpm/ft2
4.0 gpm/ft2
2.0-3.0 gpm/ft2
6.0 gpm/ft2
3.0-4.5 gpm/ft2
Sedimentation (cold seasonal water <5°C)*
Conventional (circular and rectangular) and solids contact units
Operating Mode
Conventional Solids Contact Turbidity Removal
Depth Depth SOR
(ft) (ft) (gpm/ft2)
10 12-14 0.5
12-14 14-16 0.6
>14 >16 0.7
Softening
SOR
(gpm/ft2)
0.5
0.75
1.0
Color Removal
SOR
(gpm/ft2)
0.3
0.4
0.5
Conventional (circular and rectangular) and solids contact units -
with vertical (>45°) tube settlers
Operating Mode
Turbidity Removal
Depth SOR
(ft) (gpm/ft2)
10 1.0
12-14 1.5
>14 2.0
Softening
SOR
(gpm/ft2)
1.5
2.0
2.5
Color Removal
SOR
(gpm/ft2)
0.5
0.75
1.0
*lf long term (12 months) data monitoring indicates capability to meet performance goals at higher loading rates, then these rates can be used.
29
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optimized performance goals and are the criteria
that are used for development of the major unit proc-
ess evaluation for this handbook. However, the
performance of the unit process in meeting the
optimized performance goals should be a major
consideration in the selection of evaluation criteria.
The situation where a unit process continuously
performs at optimized levels should not be rated as
a Type 2 or Type 3 unit process merely based on
the criteria in Table 4-2. Specific guidance for
assessing each unit process is described in the
following sections.
Flocculation
Proper flocculation requires sufficient time to allow
aggregation of particles so that they are easily re-
moved in the sedimentation or filtration processes.
The capability of the flocculation process is pro-
jected based on the hydraulic detention time in
minutes required to allow floe to form at the lowest
water temperature. Judgment is used to adjust the
selected times based on the type of treatment plant,
number of stages, and ability to control mixing
intensity.
Selection of the required detention time for adequate
flocculation can vary widely depending on water
temperature. For example, at plants where water
temperatures of less than 5°C (41 °F) occur, floe
formation can be delayed because of the cold water.
In these instances, longer (e.g., 30-minute)
detention times may be required. If temperatures
are not as severe, detention times as low as 15
minutes or less could be considered adequate.
Other factors to consider include the number of
flocculation stages and the availability of variable
energy input to control flocculation. A minimum of
three stages of flocculation is desirable. However,
because the baffling and variable mixing energy can
often be added or modified through minor
modifications, these items are not considered as
significant in determining the basin capability rating.
Baffling a flocculation basin to better achieve plug
flow conditions can often significantly improve the
size and settleability of the floe. If adequate basin
volume is available (i.e., typically a Type 1 unit
process), a one-stage flocculation basin may result
in a Type 2 rating with the stipulation that baffling
could be provided to overcome the single-stage
limitation if it was shown to be limiting in follow-up
CTA activities.
The following guidelines are provided to aid in se-
lecting a hydraulic detention time to be used in
development of the flocculation unit process per-
formance potential:
• Desired hydraulic detention times for floe for-
mation are:
• Typical range: 15 to 30 minutes.
• Cold low turbidity waters (e.g., <0.5°C and
<5 NTU): 30 minutes or greater for a
conventional plant.
• With tapered mixing and at least three
stages, use lower end of ranges. Twenty
minutes is commonly used for multiple
stages in temperate climates.
• With single-stage, use upper end of ranges
shown in Table 4-2.
• Lower hydraulic detention times than those
shown in Table 4-2 can be used to project
capacity in cases where plant data demon-
strates that the flocculation basin contributes to
the plant achieving the desired performance
goals at higher loading rates.
Sedimentation
Except for consistent low turbidity waters, sedi-
mentation is one of the multiple barriers normally
provided to reduce the potential of cysts from
passing through the plant. The sedimentation pro-
cess is assessed based on achieving a settled water
turbidity of less than 1 NTU 95 percent of the time
when the average raw water turbidity is less than or
equal to 10 NTU and less than 2 NTU when the
average raw water turbidity exceeds 10 NTU.
Sedimentation performance potential is projected
primarily based on surface overflow rate (SOR) with
consideration given to the basin depth, enhanced
settling appurtenances (e.g., tube settlers), and
sludge removal mechanisms. Greater depths
generally result in more quiescent conditions and
allow higher SORs to be used (see Table 4-2).
Sludge removal mechanisms also must be
considered when establishing an SOR for projecting
sedimentation capability. If sludge is manually
removed from the sedimentation basin(s), additional
depth is required to allow volume for
30
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sludge storage. For these situations, the selected
SOR should be lowered.
Sedimentation capacity ratings can be restricted to
certain maximum values because of criteria
established by state regulatory agencies on
hydraulic detention time. In these cases, state
criteria may be used to project sedimentation
treatment capability. However, if data exists that
indicates the sedimentation basins can produce
desired performance at rates above the state rate, it
may be possible to obtain a variance from the state
criteria.
As shown in Table 4-2, the availability of or the
addition of tube or plate settlers in existing tankage
can be used to enhance the performance potential
of the sedimentation process (e.g., perform at higher
SORs). Upflow-solids-contact clarifiers represent a
unique sedimentation configuration since they
contain both a flocculation and sedimentation
process that have been designed as a single unit.
These units can be rated using the center volume to
assess the flocculation capability and the clarifier
surface area to rate the sedimentation capability.
The following guidelines are suggested to aid in
selecting a surface overflow rate to be used in the
development of the sedimentation unit process
capability.
• SORs to project performance potential for rec-
tangular, circular, and solids contact basins,
operating in a temperate climate with cold sea-
sonal water (< 5°C) are shown in Table 4-2.
• SORs to project performance potential for
basins with vertical (> 45°) tube settlers,
operating in a temperate climate with cold sea-
sonal water (< 5°C) are shown in Table 4-2.
• SORs for projecting performance potential of
proprietary settling units are:
• Lamella plates:
* 10 ft long plates with 2-inch spacing at
55° slope
* 4 gpm/ft2 (based on surface area
above plates)
• Contact adsorption clarifiers (CACs):
* 6-8 gpm/ft2
• Higher SORs than those shown in Table 4-2 can
be used to project capability in cases where
plant data demonstrates that a sedimentation
basin achieves the desired performance goals at
these higher loading rates.
Filtration
Filtration is typically the final unit treatment process
relative to the physical removal of microbial
pathogens and, therefore, high levels of perform-
ance are essential from each filter on a continuous
basis. Filters are assessed based on their capability
to achieve a treated water quality of less than or
equal to 0.1 NTU 95 percent of the time (excluding
the 15-minute period following backwash) based on
the maximum values recorded during 4-hour time
increments. Additional goals include a maximum
filtered water turbidity following backwash of less
than or equal to 0.3 NTU with a recovery to less than
0.1 NTU within 15 minutes.
The performance potential of the filtration process is
projected based on a filtration rate in gpm/ft2 which
varies based on the type of media as shown in
Table 4-2. For mono-media sand filters a maximum
filtration rate of 2 gpm/ft2 is used because of the
tendency of this filter to surface bind by removing
particles at the top of the filter. Dual or mixed-media
filters use a filtration rate of 4 gpm/ft2 because of
their ability to accomplish particle removal
throughout the depth of the anthracite layer. Using
the anthracite layer allows higher filtration rates to
be achieved while maintaining excellent filtered
water quality. Filtration rates can be, and often are,
restricted to certain maximum values because of
criteria established by state regulatory agencies. In
these cases, state criteria may be used to project
filter performance potential. However, if data exists
that indicates the filters can produce desired
performance at filtration rates above the state rate, it
may be possible to obtain a variance from the state
criteria.
Limitations caused by air binding can also impact
the selected loading rate for projecting a filter's
performance potential and could bias the selected
loading rate toward more conservative values (see
Table 4-2). Air binding is a condition that occurs in
filters when air comes out of solution as a result of
pressure decreases or water temperature increases
(i.e., the water warms as it passes through the filter.
The air clogs the voids between the media grains,
which causes the filter to behave
31
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as though it were clogged and in need of back-
washing. The result is shorter filter runs and limi-
tations in hydraulic capability.
Inadequate backwash or surface wash facilities, rate
control systems, and media and underdrain integrity
are areas that can be addressed through minor
modifications. As such, these items are assessed
during a CPE as factors limiting performance and
are typically not used to lower the filtration loading
rate.
Disinfection
Disinfection is the final barrier in the treatment plant,
and is responsible for inactivating any microbial
pathogens that pass through previous unit
processes. For purposes of this handbook,
assessment of disinfection capability will be based
on the SWTR (8). The rule requires a minimum of
99.9 percent (3 log) inactivation and/or removal of
Giardia lamblia cysts and at least 99.99 percent (4
log) inactivation and/or removal of viruses. Under
the rule, each state was required to develop its own
regulations to assure that these levels of disinfection
are achieved.
USEPA has published a guidance manual that pre-
sents an approach to assure that required levels of
disinfection are achieved (9). The approach uses
the concept of the disinfectant concentration (C)
multiplied by the actual time (T) that the finished
water is in contact with the disinfectant. In the
guidance manual, CT values are provided that can
be used to project the various log removals for
various disinfectants at specific operating conditions
(e.g., temperature, pH, disinfectant residual). The
guidance manual also indicates that, while the 3-log
and 4-log inactivation and/or removals are the
minimum required, the log inactivation and/or
removal may need to be increased if the raw water
source is subject to excessive contamination from
cysts and/or viruses. Cyst and virus removal credits
for the different types of treatment processes (e.g.,
conventional, direct filtration) are also provided in
the guidance manual.
The following procedures present an approach for
projecting the capability of a plant to meet the
disinfection requirements based on the CT values
presented in the SWTR guidance manual. Proce-
dures are presented for both pre- and post-disin-
fection, with pre-disinfection defined as adding the
disinfectant ahead of the filtration process and post-
disinfection defined as adding the disinfectant
following filtration. Whether or not a utility can use
pre-disinfection depends on how the utility's state
has developed its disinfection requirements. Some
states discourage pre-disinfection because of
concerns with disinfection by-products and the
possible ineffectiveness of disinfectants in untreated
water. Other states allow pre-disinfection because
of concerns with the limited capabilities of post-
disinfection systems (e.g., limited contact time).
Although the approach used in this Handbook is
based on the SWTR requirements, it is important to
note that the major unit process evaluation for
disinfection will have to be based on the disinfection
requirements adopted by the utility's state regulatory
agency.
Future regulations may affect the following approach
for assessing disinfection unit process capability.
CPE evaluators will need to carefully assess and
modify the following procedures as more details
concerning disinfection requirements are
established.
Post-Disinfection:
The following procedure is used to assess the
plant's disinfection capability when using only post-
disinfection.
• Project the total log Giardia reduction and
inactivation required by water treatment
processes based on the raw water quality or
watershed characteristics. Typically, Giardia
inactivation requirements are more difficult to
achieve than the virus requirements;
consequently, Giardia inactivation is the basis
for this assessment. State health departments
may have established these values for a specific
plant. If not, the standard requirement for a
watershed of reasonable quality is a 3.0 log
reduction/ inactivation of Giardia cysts. A 4.0 or
more log reduction/ inactivation may be required
for an unprotected watershed exposed to factors
such as wastewater treatment effluents.
• Project the log reduction capability of the ex-
isting treatment plant. Expected removals of
Giardia and viruses by various types of filtration
plants are presented in Table 4-3. As shown, a
2.5 log reduction may be allowed for a
conventional plant with adequate unit treatment
process capability (e.g., Type 1 units preceding
disinfection). If a Type 1 plant does not exist,
the evaluator may choose to lower the projection
of log removal capability for the
32
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facility. For purposes of the projection of
major unit process capability, it is assumed
that the plant will be operated to achieve
optimum performance from existing units.
Table 4-3. Expected Removals of Giardia Cysts
and Viruses by Filtration (9)
Filtration
Conventional
Direct
Slow Sand
Diatomaceous Earth
Expected Log Removals
Giardia
2.5
2.0
2.0
2.0
Viruses
2.0
1.0
2.0
1.0
Select a required CT value from the tables
in the SWTR guidance document (also
provided in Appendix D) based on the
required log reduction/inactivation, the log
reduction capability projected for the plant,
the maximum pH and minimum
temperature of the water being treated, and
the projected maximum disinfectant
residual. The maximum pH and the minimum
temperature of the water being treated are
selected to ensure capability under worst case
conditions. When chlorine is used as the
disinfectant, the maximum residual utilized in
the evaluation should not exceed 2.5 mg/L free
residual, based on research which indicates
that contact time is more important than
disinfectant concentration at free chlorine
residuals above 2.5 mg/L (10). Maximum
chlorine residual may also be impacted by
maximum residuals tolerated by the consumer.
Using these parameters, calculate a
required detention time (e.g., CT required
value divided by the projected operating
disinfectant residual) to meet the required
CT. The following equation is used to
complete this calculation.
T (min):
CTreq(mg/L-min)
Disinfectant Residual (mg/L)
Where:
I req
CTr,
•eq
= Required detention time in post disinfection
unit processes.
= CT requirements from tables in Appendix D
for post disinfection conditions.
Disinfectant Residual = Selected operating residual
maintained at the discharge point from the
disinfection unit processes.
Select an effective volume of the existing
clearwell and/or distribution pipelines to
the first user. Effective volume refers to the
volume of a basin or pipeline that is available
to provide adequate contact time for the
disinfectant. Effective volumes are calculated
based on worst case operating conditions
using the minimum operating depths, in the
case of basins. This is especially critical in
plants where high service pumps significantly
change the operating levels of the clearwell
and in plants that use backwash systems
supplied from the clearwell. Depending on the
information available, there are two ways to
determine the effective volume.
Some plants have conducted tracer studies to
determine the actual contact time of basins.
Adequate contact time is defined in the regula-
tions as T10, which is the time it takes 10 per-
cent of a tracer to be detected in the basin
effluent (9). For these plants the effective
volume is the peak instantaneous operating
flow rate (gpm) multiplied by the T10 value
(min) determined from the tracer studies. If a
tracer study has been conducted, the results
should be utilized in determining the effective
contact time. It is important to note that the
tracer study results must also consider peak
instantaneous operating flows as well as
minimum operating depths in order to project
an accurate CT.
For those plants where tracer studies have not
been conducted, the effective volume upon
which contact time will be determined can be
calculated by multiplying the nominal clearwell
or pipeline volumes by a factor. Nominal vol-
umes are based on worst case operating con-
ditions. For example, an unbaffled clearwell
may have an effective volume of only 10%
(factor = 0.1) of actual basin volume because
of the potential for short-circuiting; whereas, a
transmission line could be based on 100% of
the line volume to the first consumer because
of the plug flow characteristics. A summary of
factors to determine effective volume is
presented in Table 4-4. Typically, for unbaffled
clean/veils a factor of 0.1 has been used
because of the fill and draw operational prac-
tices (e.g., backwashing, demand changes)
and the lack of baffles. A factor of 0.5 has
been used when calculating the effective vol-
ume of flocculation and sedimentation basins
when rating prechlorination, and a factor
33
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1.0 has been used for pipeline flow. However,
each disinfection system must be assessed on
individual basin characteristics, as perceived by
the evaluator. Caution is urged when using a
factor from Table 4-4 of greater than 0.1 to project
additional disinfection capability for unbaffled
basins. Available tracer test information indicates
that actual T10/T ratios in typical full-scale
clean/veils are close to 10 percent of theoretical
time (10).
Table 4-4. Factors for Determining Effective
Disinfection Contact Time Based on Basin
Characteristics* (9)
Baffling Condition Factor
Description
Unbaffled
high
Poor
Average
with
Superior
Excellent
Perfect (plug flow)
0.1
0.3
0.5
0.7
0.9
1 .0
Baffling
None; agitated basin,
inlet and outlet flow
velocities, variable water
level
Single or multiple unbaf-
fled inlets and outlets,
no intra-basin baffles
Baffled inlet or outlet
some intra-basin baffling
Perforated inlet baffle,
serpentine or perforated
intra-basin baffles, outlet
weir or perforated weir
Serpentine baffling
throughout basin.
Pipeline flow.
'Based on hydraulic detention time at minimum operating
depth.
Calculate a flow rate where the plant will
achieve the required CT values for post-
disinfection. The following equation is used
to complete this calculation.
Treq (min)
Pre-Disinfection:
The following procedure is used to assess the
plant's disinfection capability when using pre-
disinfection along with post-disinfection. For pur-
poses of the calculations, the approach assumes
that the disinfection requirements can be met
independently by both pre- and post-disinfection;
and, therefore, these capabilities are additive when
projecting plant disinfection unit process capability.
The procedure is used to determine the additional
disinfection capability provided if pre-disinfection is
actually being practiced at the utility being
evaluated. If pre-disinfection is practiced and the
utility is concerned about disinfection by-products,
the performance potential graph should be
developed with two bars for disinfection: one
including pre- and post-disinfection and one
including only post-disinfection capability. This
allows the evaluators and the utility to assess
capability if pre-disinfection was excluded.
• Project the total log Giardia reduction and
inactivation required by water treatment
processes based on the raw water quality
or watershed characteristics as presented
in the post-disinfection procedure.
• Project the log reduction capability of the
existing treatment plant as presented in the
post-disinfection procedure.
• Select a required CT value for pre-
disinfection from the tables in the SWTR
guidance document. This value should be
based on the required log reduction, the log
reduction capability of the plant, the maximum
pH and minimum temperature of the water
being treated, and the projected maximum
disinfectant residual. The required pre-
disinfection CT value may be different than the
post-disinfection conditions if different
temperatures, pHs, and residuals exist for the
two conditions (e.g., addition of lime or soda
ash to increase the pH of finished water would
change the required post-disinfection CT
value relative to the pre-disinfection value).
CT values for inactivation of Giardia cysts and
viruses are presented in Appendix D.
Where:
Q = Flow rate where required CTreq can
be met.
Vpost = Effective volume for post-
disinfection units.
NOTE: If chlorine is used as the pre-disinfectant, a
1.5 mg/L free chlorine residual can be used as
a value in the calculations unless actual plant
records support selection of a different
residual.
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• Calculate Treq (e.g., CT required value
divided by the projected operating
disinfectant residual) as presented in the
post-disinfection procedure.
• Select an effective volume available to
provide adequate contact time for pre-
disinfection. Assess which basins and lines
will provide contact time. These are typically
the flocculation and sedimentation basins, but
could include raw water transmission lines if
facilities exist to inject disinfectant at the intake
structure. Filters typically have not been
included because of the short detention times
typically inherent in the filters and the reduction
in chlorine residual that often occurs through
filters. However, increasingly plants are
adding free chlorine ahead of the filters and
ammonia after the filters to improve particle
removal while minimizing DBP formation. Free
residuals of 2.0 mg/L in the filter effluent are
common. These residuals with a filter bed
contact time of 10 to 15 minutes may meet the
majority, if not all, of the CT requirement. The
actual basin volumes should be converted to
effective volumes by applying factors
described in Table 4-4 and discussed
previously in the post-disinfection procedure.
Add the individual effective volumes together
to obtain the total effective pre-disinfection
volume.
• Calculate a flow rate where the plant will
achieve the required CT values for both
pre- and post-disinfection using the
formula below. Use this flow rate to project
the pre- and post-disinfection system capability
on the performance potential graph.
Q(apm).
Treqpre (min) Treqpost (min)
Where:
Q = Flow rate where required CTreq can
be
met.
Vpre = Effective volume for pre-disinfection
units.
Vpost = Effective volume for post-disinfection
units.
4.2.3 Identification and Prioritization of
Performance Limiting Factors
4.2.3.1 Identification of Performance
Limiting Factors
A significant aspect of any CPE is the identification
of factors that limit the existing facility's per-
formance. This step is critical in defining the future
activities that the utility needs to focus on to
achieve optimized performance goals. To assist in
factor identification, a list of 50 different factors,
plus definitions, that could potentially limit water
treatment plant performance are provided in Ap-
pendix E. These factors are divided into the four
broad categories of administration, design, opera-
tion, and maintenance. This list and definitions are
based on the results of over 70 water treatment
plant CPEs. Definitions are provided for the
convenience of the user and also as a reference to
promote consistency in the use of factors from
plant to plant. If alternate names or definitions
provide a clearer understanding to those conduct-
ing the CPE, they can be used. However, if differ-
ent terms are used, each factor should be defined,
and these definitions should be made readily avail-
able to others conducting the CPE and interpreting
the results. Adopting and using a list of standard
factors and definitions as provided in this hand-
book allows the effective comparison of factors
identified from different plants which will enhance
the usefulness of the findings for improving water
system performance on an area-wide basis.
It is noted that several of the design factors refer to
capability of major unit processes. If the major unit
process evaluation resulted in a Type 2 or 3
classification for an individual unit process, these
results are also indicated in the CPE findings as an
identified factor limiting the existing facility's per-
formance. This also applies to those situations
where major unit processes are rated Type 1, but
have equipment-related problems that are limiting
performance. This would include key equipment
that needs to be repaired and/or replaced.
A CPE is a performance-based evaluation and,
therefore, factors should only be identified if they
impact performance. An observation that a utility
does not meet a particular "industry standard"
(e.g., utility does not have a documented preven-
tive maintenance program or does not practice
good housekeeping) does not necessarily indicate
that a performance limiting factor exists in these
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areas. An actual link between poor plant perform-
ance and the identified factor must exist.
Properly identifying a plant's unique list of factors is
difficult because the actual problems in a plant are
often masked. This concept is illustrated in the
following example:
A review of plant records revealed that a con-
ventional water treatment plant was periodically
producing finished water with a turbidity greater
than 0.5 NTU. The utility, assuming that the
plant was operating beyond its capability, was
beginning to make plans to expand both the
sedimentation and filtration unit processes.
Field evaluations conducted as part of a CPE
revealed that settled water and finished water
turbidities averaged about 5 NTU and 0.6 NTU,
respectively. Filtered water turbidities peaked
at 1.2 NTU for short periods following a filter
backwash. Conceivably, the plant's sedi-
mentation and filtration facilities were inade-
quately sized. However, further investigation
revealed that the poor performance was caused
by the operator adding coagulants at excessive
dosages, leading to formation of a pin floe that
was difficult to settle and filter. Additionally, the
plant was being operated at its peak capacity
for only 8 hours each day, further aggravating
the washout of solids from the sedimentation
basins. It was assessed that implementing
proper process control of the plant (e.g., jar
testing for coagulant control, calibration and
proper adjustment of chemical feed) and
operating the plant at a lower flow rate for a
longer time period would allow the plant to
continuously achieve optimized finished water
quality. When the operator and administration
were questioned about the reasons that the
plant was not operated for longer periods of
time, it was identified that it was an administra-
tive decision to limit the plant staffing to one
person. This limitation made additional daily
operating time as well as weekend coverage
difficult.
It was concluded that three major factors con-
tributed to the poor performance of the plant:
1. Application of Concepts and Testing to
Process Control: Inadequate operator
knowledge existed to determine proper
coagulant doses and to set chemical feed
pumps to apply the correct chemical dose.
2. Administrative Policies: A restrictive
administrative policy existed that prohibited
hiring an additional operator to allow
increased plant operating time at a reduced
plant flow rate.
3. Process Control Testing: The utility had
inadequate test equipment and an inade-
quate sampling program to provide process
control information.
In this example, pursuing the perceived limitation
regarding the need for additional sedimentation
and filtration capacity would have led to improper
corrective actions (i.e., plant expansion). The CPE
indicated that addressing the identified operational
and administrative factors would allow the plant to
produce a quality finished water on a continuous
basis without major expenditures for construction.
This example illustrates that a comprehensive
analysis of a performance problem is essential to
identify the actual performance limiting factors.
The CPE emphasis of assessing factors in the
broad categories of administration, design, opera-
tion, and maintenance helps to ensure the identifi-
cation of root causes of performance limitations.
The following sections provide useful observations
in identifying factors in these broad categories.
Identification of Administrative Factors
For purposes of a CPE administrative personnel
are those individuals who can exercise control over
water treatment but do not work "on-site" at the
plant on a day-to-day basis. This definition
includes personnel with job titles such as: off-site
superintendents, Directors of Public Works, council
personnel, mayors, etc.
The identification of administrative performance
limiting factors is a difficult and subjective effort.
Identification is primarily based on interpretation of
management and staff interview results. Typically,
the more interviews that can be conducted the
better the interpretation of results will be. In small
plants the entire staff, budgetary personnel, and
plant administrators, including a minimum of one or
two elected officials, can be interviewed. In larger
facilities all personnel cannot typically be
interviewed, requiring the CPE evaluator to select
key personnel.
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Interviews are more effective after the evaluator
has been on a plant tour and has completed
enough of the data development activities (includ-
ing the performance assessment and major unit
process evaluations) to become familiar with plant
capabilities and past performance. With this
information, the evaluator is better informed to ask
insightful questions about the existing plant.
Accurately identifying administrative factors
requires aggressive but non-threatening interview
skills. The evaluator must always be aware of this
delicate balance when pursuing the identification of
administrative factors.
Policies, budgeting, and staffing are key mecha-
nisms that plant owners/administrators generally
use to implement their objectives. Therefore,
evaluation of these aspects is an integral part of
efforts to identify the presence of administrative
performance limiting factors.
Policies:
In order for a utility to strive for optimized per-
formance, there needs to be a commitment to
excellence in the form of supplying a high quality
treated water. This commitment must be based on
an understanding of the importance of water
treatment to the protection of public health.
Administrators must understand that to minimize
the potential for exposure of consumers to patho-
genic organisms in their drinking water, all unit
processes must be performing at high levels on a
continuous basis. Accordingly, administrators
should develop goals for high quality water and
should emphasize to the operating staff the impor-
tance of achieving these goals. Relative to par-
ticulate removal, administrators should encourage
pursuit of optimized performance goals as
described in this handbook.
Typically, all administrators verbally support goals
of low cost, safe working conditions; good plant
performance; and high employee morale. An
important question that must be answered is, "Is
priority given to water quality?" Often administra-
tors are more concerned with water quantity than
water quality, and this question can be answered
by observing the items implemented or supported
by the administrators. If a multi-million dollar
storage reservoir project is being implemented
while the plant remains unattended and neglected,
priorities regarding water quality and quantity can
be easily discerned.
An ideal situation is one in which the administrators
function with the awareness that they want to
achieve high quality finished water as the end
product of their treatment efforts. At the other end
of the spectrum is an administrative attitude that
"We just raised rates last year, and we aren't
willing to pursue additional revenues. Besides my
family used to drink untreated water from the river
and no one ever got sick." Also, plant administra-
tors may emphasize cost savings as a priority to
plant staff. The staff may be told to keep chemical
cost down and to cut back if the finished water
turbidity falls below the regulated limit (i.e.,
0.5 NTU). For instance, one administrator indi-
cated to a plant superintendent that he would be
fired if he did not cut chemical costs. Administra-
tors who fall into this category usually are identified
as contributing to inadequate performance during
an administrative assessment.
Another area in which administrators can signifi-
cantly, though indirectly, affect plant performance
is through personnel motivation. A positive influ-
ence exists if administrators: encourage personal
and professional growth through support of train-
ing; encourage involvement in professional organi-
zations; and provide tangible rewards for pursuing
certification. If, however, administrators eliminate
or skimp on essential operator training, downgrade
operator or other positions through substandard
salaries, or otherwise provide a negative influence
on staff morale, administrators can have a signifi-
cant detrimental effect on plant performance.
When the CPE evaluator finds that the operations
staff exhibit complacency, the role of the utility's
management in this situation needs to be
assessed. Utility management must support de-
velopment of a work environment that generates a
commitment to excellence as the best defense
against complacency. This requires involvement of
the entire utility to create an empowered staff that
can effectively respond to changing conditions.
Utility administrators also need to be aware of the
impact that their policies have on treatment plant
performance. For example, at one small utility the
city manager forbid the plant operators to back-
wash filters more than once a week because
operating the backwash pump caused excessive
power demand and increased the utility's power
bill. This administrative policy's negative impact on
plant performance is obvious.
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When a plant is using key process equipment (e.g.,
filter rate controllers) that appear to be antiquated
and are impacting plant performance currently or
potentially long-term, concerns with plant reliability
must be assessed. In these cases the utility
administrator's role in influencing the plant to use
the antiquated equipment past its useful life should
be determined. For example, utility administrators
may have delayed replacement of the key equip-
ment way beyond its useful life because there was
no immediate problem and they wanted to keep
the utility's budget low. Identification of this
situation would be used to support an administra-
tor's policies factor limiting performance.
Budgeting:
Minor plant modifications to address performance
problems identified by the utility staff can often
serve as a basis for assessing administrative fac-
tors limiting performance. For example, the plant
staff may have correctly identified needed minor
modifications for the facility and presented these
needs to the utility manager, but had their requests
declined. The CPE evaluator must solicit the other
side of the story from the administrators to see if
the administration is indeed non-supportive in
correcting the problem. There have been
numerous instances in which operators or plant
superintendents have convinced administrators to
spend money to "correct" problems that resulted in
no improvement in plant performance.
Smaller utilities often have financial information
combined with other utilities, such as wastewater
treatment, street repairs, and parks and recreation.
Additionally, nearly every utility's financial infor-
mation is set up differently. Therefore, it is neces-
sary to review information with the assistance of
plant and/or budgetary personnel to rearrange the
line items into categories understood by the
evaluator. Forms for comprehensively collecting
plant information, including financial information,
have been developed and are included in Appen-
dix F.
When reviewing financial information, it is impor-
tant to determine the extent of bond indebtedness
of the community and whether the rate structure
creates sufficient revenue to adequately support
the plant. Water system revenues should provide
an adequate number of fairly paid staff and exceed
expenditures enough to allow establishment of a
reserve fund for future plant modifications. Criteria
for determining key financial ratios for a utility
and guidance on their use are included in
Appendix F.
Staffing:
Administrators can directly impact performance of
a plant by providing inadequate staffing levels such
that there is not an operator at the plant when it is
in operation. Inadequate plant coverage often
results in poor performance since no one is at the
plant to adjust chemical dosages relative to raw
water quality changes. Non-staffed plant operation
can sometimes be justified if remote monitoring
associated with performance parameters and
alarm and plant shutdown capability exists.
Identification of Design Factors
Data gathered during a plant tour, review of plant
drawings and specifications, completion of design
information forms in Appendix F, and the com-
pleted evaluation of major unit processes, includ-
ing the performance potential graph, provide
information needed to assess design-related per-
formance limiting factors. Typically, the identifica-
tion of design factors falls into two categories:
major unit process limitations, as indicated by the
performance potential graph, and other design fac-
tors indicated in the list in Appendix E.
When considering identifying major unit process
limitations, the evaluator needs to exercise a great
deal of judgment since identification of these fac-
tors directs the utility toward construction alter-
natives. If at all possible, the evaluator should
assess options for operational alternatives (e.g.,
lower plant loading during periods where the raw
water quality is poor or extended operational time
to bring loading more in-line with assessed capa-
bility). This emphasis is especially true for Type 2
unit processes.
When the CPE evaluator has concerns with plant
reliability because the plant is using antiquated
process equipment, the root cause of the reliability
must be assessed beyond just identifying this as a
design factor. Typically, a reliability issue from use
of antiquated equipment is an administrative factor.
In rare cases preventive maintenance programs
can lead to reliability problems.
Frequently, to identify design factors the evaluator
must make field evaluations of the various unit
38
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processes to assess design limitations. Identifica-
tion of these factors often offers great potential to
improve facility performance (e.g., baffling of
basins or improvement of flow splitting). Field
evaluations will be discussed later in this chapter.
It is important to note that any field evaluations
undertaken during a CPE should be completed in
cooperation with the plant staff. This approach is
essential since the evaluator may wish to make
changes that could improve plant performance but
could be detrimental to equipment at the plant.
Plant staff have worked and maintained the
equipment, are familiar with control systems, and
are in the best position to ascertain any adverse
impact of proposed changes.
Identification of Operational Factors
The approach and methods used in maintaining
process control can significantly affect perform-
ance of plants that have adequate physical facili-
ties (3,7). As such, identification of operationally-
based performance limiting factors offers the
greatest potential in improving the performance of
an existing utility. Information for identifying the
presence or absence of operational factors is
obtained throughout the CPE activities and
includes the plant tour, interviews, and the field
evaluation activities.
A plant tour provides an opportunity to initially
assess process control efforts. For example, the
process control capability of an operator can be
subjectively assessed during a tour by noting if the
operator discusses the importance of process
adjustments that are made to correlate with
changes in raw water quality. A solid foundation
for a viable process control program exists if the
operator presents this key information.
It is also important to assess issues of compla-
cency and reliability with respect to the staffs
process control capabilities. It is especially critical
to determine if all of the staff have the required
process control skills or if plant reliability is jeop-
ardized because only one person can make proc-
ess control decisions. Causes for this situation
could be administrative policies, staff technical
skills, or supervisory style.
After the tour, the focus of the identification of
operational factors is the assessment of the utiity's
process control testing, data interpretation, and
process adjustment techniques. Key process
controls available to a water treatment plant
operator are flow rate; number of basins in service;
chemical selection and dosage; and filter
backwash frequency, duration and rate. Other
controls include flocculation energy input and
sedimentation sludge removal. Process control
testing includes those activities necessary to gain
information to make decisions regarding available
plant controls. Information to assist in evaluating
process control testing, data interpretation, and
process adjustment efforts is presented below.
Plant Flow Rate and Number of Basins in
Service:
Plant flow rate dictates the hydraulic loading rate
on the various plant unit processes. In plants that
operate 24 hours each day, water demand dictates
water production requirements. However, many
small plants operate at maximum flow rates for
short (e.g., 8-hour) periods of time. Also, some
plants have multiple treatment trains, and flexibility
exists to vary the number in service. If the
operator is not aware that operating for longer
periods of time at a lower flow rate or increasing
the number of trains in service could improve plant
performance, an operations factor may be indi-
cated. Rapid increases in plant flow rate can also
have a significant effect on plant performance by
forcing particles through the filters.
Chemical Dose Control:
Chemical coagulants and flocculant and filter aids
are utilized to neutralize charges on colloidal parti-
cles and to increase the size and strength of parti-
cles to allow them to be removed in sedimentation
and filtration unit processes. Either overdosing or
underdosing these chemicals can result in a failure
to destabilize small particles, including pathogens,
and allow them to pass through the sedimentation
and filtration processes. If disinfection is inade-
quate to eliminate the pathogens that pass through
the plant, a significant public health risk exists.
Chemicals used for stabilization, disinfection, taste
and odor control, and fluoridation must also be
controlled.
The following are common indicators that proper
chemical application is not practiced:
• Calibration curves are not available for chemi-
cal feed pumps.
39
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• Operations staff cannot explain how chemi-
cals, such as polymers, are diluted prior to
application.
• Operations staff cannot calculate chemical
feed doses (e.g., cannot convert a mg/L
desired dose to Ib/day or ml/min to allow
proper setting of the chemical feeder).
• Operations staff cannot determine the chemi-
cal feeder setting for a selected dose role.
• Operations staff do not adjust chemical feed
rates for varying raw water quality conditions.
• Chemicals are utilized in combinations that
have detrimental effects on plant performance.
An example is the practice of feeding lime and
alum at the same point without consideration
of the optimum pH for alum coagulation.
• Chemicals are not fed at the optimum location
(e.g., non-ionic polymer fed before rapid mix
unit).
• Chemical feed rates are not changed when
plant flow rate is adjusted.
• Chemical coagulants are not utilized when raw
water quality is good (e.g., less than 0.5 to
1 NTU).
Filter Control:
The effectiveness of the filtration unit process is
primarily established by proper coagulant control;
however, other factors, such as hydraulic loading
rate and backwash frequency, rate, and duration,
also have a significant effect on filter performance.
Filters can perform at relatively high filtration rates
(e.g., 8 gpm/ft2) if the water applied is properly con-
ditioned (11, 12). However, because particles are
held in a filter by relatively delicate forces, rapid
flow rate changes can drive particles through a
filter, causing a significant degradation in per-
formance (7, 11, 12). Rapid rate changes can be
caused by increasing plant flow, by bringing a high
volume constant rate pump on-line, by a malfunc-
tioning filter rate control valve, or by removing a
filter from service for backwashing without reducing
overall plant flow.
Filters must be backwashed periodically to prevent
accumulated particles from washing through the
filter or to prevent the filter from reaching terminal
headless. Filters should be backwashed based on
effluent turbidity if breakthrough occurs before
terminal headless to prevent the production of poor
filtered water quality. Backwash based on
headless should be a secondary criteria. For
example, particles that are initially removed by the
filter are often "shed" when velocities and shear
forces increase within the filter as headless accu-
mulates as the filter becomes "dirty." This signifi-
cant breakthrough in particles can be prevented by
washing a filter based on turbidity or particle
counting. Also, inadequate washing, both in terms
of rate and duration, can result in an accumulation
of particles in the filter, resulting in poor filtered
water quality. When a filter is continually returned
to service with a significant amount of particles still
within the media, these particles can accumulate to
form mudballs. The accumulation of mudballs
displaces filter surface area and raises the filtration
rate through those areas of the filter where water
can still pass. The filter can also reach a point
where minimal additional particles can be removed
because available storage sites within the media
already have an accumulation of filtered particles.
The evaluator must determine whether inadequate
washing is caused by a design or an operational
limitation. Field evaluations, such as bed
expansion and rise rate, that can be conducted to
determine the capability of backwash facilities are
discussed later in this chapter.
Another key process control activity is returning a
filter to service following a backwash. Since start-
up of filters can often result in loss of particles and
high turbidities, process control practices should be
developed to minimize this impact on performance.
Operational practices that have provided improved
quality from filters during start-up have included:
ramping the backwash rate down in increments to
allow better media gradation, resting a filter after
backwash for several minutes or up to several
hours before putting the filter in service, adding a
polymer to the backwash water, and slowly
increasing the hydraulic loading on the filter as it is
brought back on line. These process control
practices should be implemented and observed at
each utility to develop the optimum combination of
activities that provides the best filter performance.
The following are common indicators that proper
filter control is not practiced:
• Filters are started dirty (i.e., without back-
washing).
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Rapid increases in overall plant flow rate are
made without consideration of filtered water
quality.
Filter to waste capability is not being utilized or
is not monitored if utilized.
Filters are removed from service without
reducing plant flow rate, resulting in the total
plant flow being directed to the remaining fil-
ters.
Operations staff backwash the filters without
regard for filter effluent turbidity.
Operations staff backwash at a low rate for a
longer period of time, or stop the backwash
when the filter is still dirty to "conserve" water.
Filters have significantly less media than speci-
fied, damage to underdrains or support grav-
els, or a significant accumulation of mudballs;
and these conditions are unknown to the oper-
ating staff because there is no routine exami-
nation of the filters.
Operations staff cannot describe the purpose
and function of the rate control device.
Process Control Activities:
It is necessary for the operations staff to develop
information from which proper process adjustments
can be made. As a minimum, a method of
coagulation control must be practiced, such as jar
testing. Samples of raw water, settled water, and
individual filter effluent should be monitored for
turbidity. Operations staff that properly understand
water treatment should be able to show the
evaluator a recorded history of raw, settled, and
filtered water quality and jar test results; and be
able to describe how chemical dosages are deter-
mined and calculated and how chemical feeders
are set to provide the desired chemical dose. They
should also be able to explain how chemical feed
rates are adjusted, depending on raw water
quality.
Two similar factors are described in Appendix E
which often are difficult to discern when identifying
operational factors: Water Treatment Under-
standing and Application of Concepts and Testing
to Process Control. Identification of the proper
factor is key since follow-up efforts to address
each factor are different. Water Treatment Under-
standing is identified when the technical skills of
the staff are not adequate to implement proper
process control procedures. This limitation would
require training in the fundamentals of water
treatment. Application of Concepts and Testing to
Process Control is identified if the staff have basic
technical skills but are not appropriately applying
their knowledge to the day-to-day process control
of the unit processes. This factor can often be best
addressed with site-specific hands-on training.
The following are common indicators that required
process control activities are not adequately
implemented at a plant:
• Specific performance objectives for each major
unit process (barrier) have not been estab-
lished.
• A formalized sampling and testing schedule
has not been established.
• Data recording forms are not available or not
used.
• Jar tests or other methods (e.g., streaming
current monitor, zeta potential, or pilot filter) of
coagulation control are not practiced.
• The operator does not understand how to
prepare a jar test stock solution or how to
administer various chemical doses to the jars.
• The staff collects one sample per day for raw
water turbidity despite a rapidly changing raw
water source.
• Settled water turbidities are not measured or
are not measured routinely (e.g., minimum of
once each shift).
• Individual filtered water quality is not moni-
tored.
• Recycle water quality is not monitored or its
impact on plant performance is not controlled
(e.g., intermittent high volume recycle pump-
ing).
• Raw water used in jar testing does not include
recycle streams.
41
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• There are no records available which
document performance of the individual
sedimentation or filtration unit processes.
• Performance following backwash is not moni-
tored or recorded.
• Recorded data are not developed or
interpreted (e.g., trend charts are not
developed for assessing unit process
performance).
• Calibration and other quality control proce-
dures are not practiced.
• An emergency response procedure has not
been developed for the loss of chemical feeds
or for unacceptable finished water quality
occurrences.
Other Controls:
Other controls available to the operations staff
include rapid mixing, flocculation energy input,
sedimentation sludge removal, and disinfection
control. The following are indicators that these
controls are not fully utilized to improve plant per-
formance:
• The rapid mixer is shut down (e.g., to conserve
power) and no other means exists to
effectively mix coagulant chemicals with raw
water (e.g., through a pump or prior to a
valve).
• Variable speed flocculation drives are not
adjusted (e.g., they remain at the setting
established when the plant was constructed).
• There is no routine removal of sludge from
sedimentation basins.
• There is no testing to control sludge quantities
in an upflow solids contact clarifier (e.g., rou-
tine sludge withdrawal is not practiced).
• Clean/veil or disinfection contact basin levels
are not monitored or maintained above a mini-
mum level to ensure that CT values can be
met.
Identification of Maintenance Factors
Maintenance performance limiting factors are typi-
cally associated with limitations in keeping critical
pieces of equipment running to ensure optimum
unit process performance or with reliability issues
related to a lack of ongoing preventive mainte-
nance activities.
Maintenance performance limiting factors are
evaluated throughout the CPE by data collection,
observations, and interviews concerning reliability
and service requirements of pieces of equipment
critical to plant performance. If units are out of
service routinely or for extended periods of time,
maintenance practices may be a significant con-
tributing cause to a performance problem. For
example, key equipment, such as chemical feed-
ers, require back-up parts and on-site skills for
repair to ensure their continued operation. Another
maintenance limitation could be a smaller raw
water pump that was out of service for an extended
period of time. In this example, the staff may be
forced to use a larger raw water pump that
overloads the existing unit processes during
periods of poor raw water quality.
Another key distinction to make when trying to
identify maintenance factors is to assess the qual-
ity of the preventive maintenance program relative
to the reliability of the equipment due to age.
Many utilities have excellent maintenance pro-
grams and personnel that have kept equipment
running long beyond its useful/reliable lifetime. In
these cases frequent breakdowns of the aging
equipment can lead to performance problems.
However, the root cause of the performance limi-
tation may be plant administrators that have made
a decision to forego the costs of replacement and
continue to force the plant to rely on the old
equipment. In this example, the CPE evaluator
must identify whether the lack of reliability is due to
poor maintenance or is an attitude related to the
administration staff.
4.2.3.2 Prioritization of Performance
Limiting Factors
After performance limiting factors are identified,
they are prioritized in order of their adverse impact
on plant performance. This prioritization estab-
lishes the sequence and/or emphasis of follow-up
activities necessary to optimize facility perform-
ance. For example, if the highest ranking factors
(i.e., those having the most negative impact on
performance) are related to physical limitations in
unit process capacity, initial corrective actions are
directed toward defining plant modifications and
obtaining administrative funding for their
42
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implementation. If the highest ranking factors are
process control-oriented, initial emphasis of follow-
up activities would be directed toward plant-
specific operator training.
Prioritization of factors is accomplished by a two-
step process. First, all factors that have been
identified are individually assessed with regard to
their adverse impact on plant performance and
assigned an "A", "B" or "C" rating (Table 4-5). The
summary of factors in Appendix E includes a
column to enter this rating. The second step of
prioritizing factors is to list those receiving "A"
rating in order of severity, followed by listing those
receiving "B" rating in order of severity. "C" factors
are not prioritized.
Table 4-5. Classification System for Prioritizing
Performance Limiting Factors
Ratin
g
A
B
C
Classification
Major effect on a long term repetitive
basis
Moderate effect on routine basis or major
effect on a periodic basis
Minor effect
"A" factors are the major causes of performance
deficiencies and are the central focus of any sub-
sequent improvement program. An example "A"
factor would be an operations staff that has not
developed or implemented process control adjust-
ments to compensate for changing raw water
quality.
Factors are assigned a "B" rating if they fall in one
of two categories:
1. Those that routinely contribute to poor plant
performance but are not the major problem.
An example would be insufficient plant process
control testing where the primary problem is
that the operations staff does not sample and
test to determine process efficiency for the
sedimentation basins.
2. Those that cause a major degradation of plant
performance, but only on a periodic basis.
Typical examples are sedimentation basins that
cause periodic performance problems due to
3.
excessive loading during spring run-off or a
short flocculation detention time that limits floe
formation during cold water periods.
Factors receive a "C" rating if they have a minor
effect on performance. For example, the lack of
laboratory space could be a "C" factor if samples
had to be taken off-site for analysis. The problem
could be addressed through the addition of bench
space and, thus, would not be a major focus during
follow-up activities.
A particular factor can receive an "A", "B", or "C"
rating at any facility, depending on the circum-
stances. For example, a sedimentation basin
could receive an "A" rating if its size was inade-
quate to produce optimized performance under all
current loading conditions. The basin could
receive a "B" rating if the basin was only
inadequate periodically, for example, during
infrequent periods of high raw water turbidity. The
basin would receive a "C" rating if the size and
volume were adequate, but minor baffling would
improve the consistency of its performance.
Typically, 5 to 10 unique factors are identified for a
particular CPE. The remaining factors that are not
identified as performance limiting represent a
significant finding. For example, in the illustration
that was previously presented in the Identification
of Performance Limiting Factors section of this
chapter, neither sedimentation nor filtration were
identified as performance limiting factors. Since
they were not identified, plant personnel need not
focus on sedimentation basin or filter modifications
and the associated capital to upgrade these
facilities. Factors that are not identified are also a
basis for providing recognition to plant personnel
for adequately addressing these potential sources
of problems.
Once each identified factor is assigned an "A", "B",
or "C" classification, those receiving "A" or "B"
ratings are listed on a one-page summary sheet
(see Appendix E) in order of assessed severity on
plant performance. Findings that support each
identified factor are summarized on an attached
notes page. An example of a Factors Summary
Sheet and the attached notes is shown in Figure 4-
6. The summary of prioritized factors provides a
valuable reference for the next step of the CPE,
assessing the ability to improve performance, and
serves as the foundation for implementing correc-
tion activities if they are deemed appropriate.
43
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All factors limiting facility performance may not be
identified during the CPE phase. It is often neces-
sary to later modify the original corrective steps as
new and additional information becomes available
during conduct of the performance improvement
phase (CTA).
4.2.4 Assessment of the Applicability of
a CTA
Proper interpretation of the CPE findings is neces-
sary to provide the basis for a recommendation to
pursue the performance improvement phase (e.g.,
Chapter 5). The initial step in assessment of CTA
applicability is to determine if improved perform-
ance is achievable by evaluating the capability of
major unit processes. A CTA is typically recom-
mended if unit processes receive a Type 1 or
Type 2 rating. However, if major unit processes
are deficient in capability (e.g., Type 3), acceptable
performance from each "barrier" may not be
achievable; and the focus of follow-up efforts may
have to include construction alternatives. Another
important consideration with Type 3 facilities is the
immediate need for public health protection
regardless of the condition of the plant. Even if a
facility has serious unit process deficiencies and
antiquated equipment, the plant still has a respon-
sibility to protect public health until new treatment
processes are designed and constructed. In these
situations every effort should be made, therefore,
to operate around marginal unit processes and un-
reliable equipment if it represents the best short-
term solution for providing safe drinking water. This
concept is shown schematically in Figure 4-7.
Although all performance limiting factors can theo-
retically be eliminated, the ultimate decision to
conduct a CTA may depend on the factors that are
identified during the CPE. An assessment of the
list of prioritized factors helps assure that all factors
can realistically be addressed given the unique set
of factors identified. There may be reasons why a
factor cannot be approached in a straightforward
manner. Examples of issues that may not be
feasible to address directly are: replacement of
key personnel, increases in rate structures, or
training of uninformed or uncooperative adminis-
trators to support plant needs. In the case of
recalcitrant administrators who refuse to recognize
the importance of water quality and minimizing
public health risk, regulatory pressure may be nec-
essary before a decision is made to implement a
CTA.
For plants where a decision is made to implement
a CTA, all performance limiting factors should be
considered as feasible to address. These are typi-
cally corrected with adequate "training" of the
appropriate personnel. The training is directed
toward the operations staff for improvements in
plant process control and maintenance, toward the
plant administrators for improvements in adminis-
trative policies and budget limitations, and toward
administrators and operations staff to achieve
minor facility modifications. Training, as used in
this context, describes activities whereby informa-
tion is provided to facilitate understanding and
implementation of corrective actions.
4.2.5 CPE Report
Results of a CPE are summarized in a brief written
report to provide guidance for utility staff and, in
some cases, state regulatory personnel. It is
important that the report be kept brief so that
maximum resources are used for the evaluation
rather than for preparation of an all-inclusive
report. The report should present sufficient infor-
mation to allow the utility decision-makers to initi-
ate efforts toward achieving desired performance
from their facility. It should not provide a list of
specific recommendations for correcting individual
performance limiting factors. Making specific rec-
ommendations often leads to a piecemeal
approach to corrective actions, and the goal of
improved performance is not achieved. For Type 1
and Type 2 plants, the necessity of comprehen-
sively addressing the combination of factors identi-
fied by the CPE through a CTA should be stressed.
For Type 3 plants, a recommendation for a more
detailed study of anticipated modifications may be
warranted. Appendix G demonstrates a sample
CPE report.
4.3 Conducting a CPE
A CPE involves numerous activities conducted
within a structured framework. A schematic of
CPE activities is shown graphically in Figure 4-8.
Initial activities are conducted prior to on-site
efforts and involve notifying appropriate utility
personnel to ensure that they, as well as neces-
sary resources, will be available during the CPE.
The kick-off meeting, conducted on-site, allows the
evaluators to describe forthcoming activities, to
coordinate schedules, and to assess availability of
the materials that will be required. Following
44
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Figure 4-6. Example factors summary and supporting notes.
CPE PERFORMANCE LIMITING FACTORS SUMMARY
Plant Name/Location: XYZ Water Treatment Plant
CPE Performed By: Process Applications, Inc.
CPE Date: June 15 -18, 1998
Plant Type: Conventional with mixed media filters
Source Water: Wolf Creek
Performance Summary:
Plant was not able to meet the Surface Water Treatment Rule turbidity requirement of 0.5 NTU 95
percent of the time during March - May 1998. Optimized performance to achieve maximum public
health protection from microbial contaminants by producing a filtered water turbidity of 0.1 or less 95
percent of the time has not been achieved.
Ranking Table
Rank
1
2
3
4
5
Rating
A
A
A
A
B
Performance Limiting Factor (Category)
Alarm Systems (Design)
Process Flexibility (Design)
Policies (Administration)
Application of Concepts and Testing to Process Control
(Operation)
Process Instrumentation/Automation (Design)
Rating Description
A — Major effect on long-term repetitive basis.
B — Moderate effect on a routine basis or major effect on a periodic basis.
C — Minor effect.
45
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Figure 4-6. Example factors summary and supporting notes (continued).
Performance Limiting Factors Notes
Factor
Alarm Systems
Process Flexibility
Policies
Applications of Concepts and
Testing to Process Control
Process Instrumentation/
Automation
Rating
A
A
A
A
B
Notes
• No alarm/plant shutdown capability on chlorine feed,
chlorine residual, raw water turbidity, and finished water
turbidity.
• Inability to select plant flow rate (e.g., set at 2,100 gpm).
• No ability to feed filter aid polymer to the filters.
• Inability to gradually increase and decrease backwash flow
rate.
• Lack of established optimization goals (e.g., 0.1 NTU
filtered water turbidity) to provide maximum public health
protection and associated support to achieve these
performance goals.
• No sampling of clarifier performance.
• Inadequate testing to optimize coagulant type and
dosages.
• No individual filter turbidity monitoring.
• Starting "dirty" filters without backwash.
• Incomplete jar testing to optimize coagulant dose.
• Non-optimized feed point for flocculant aid addition.
• No turbidimeters on individual filters.
• Start and stop of filters without backwash or filter-to-waste
(due to storage tank demand).
• Location of raw water turbidity monitor cell resulting in
inaccurate readings.
46
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Figure 4-7. CPE/CTA schematic of activities.
Plant Administrators or
Regulators Recognize Need
To Evaluate or Improve
Plant Performance
CPE Evaluation of
Major Unit Processes
Type 1
Major Unit Processes
Are Adequate
Type 2
Major Unit Processes
Are Marginal
Implement CTA to
Achieve Desired
Performance
From Existing Facilities
Implement CTA to
Optimize Existing Facilities
Before Initiating
Facility Modifications
Facility
Modifications
Optimized Performance
Achieved
Type 3
Major Unit Processes
Are Inadequate
Evaluate Options For
Facility Modifications
Address Public Health
Related Factors
Facility
Modifications
Plus CTA
Activities
Abandon
Existing
Facilities and
Design New
Ones Plus
CTA
Activities
the kick-off meeting, a plant tour is conducted by
the superintendent or process control supervisor.
During the tour, the evaluators ask questions
regarding the plant and observe areas that may
require additional attention during data collection
activities. For example, an evaluator might make a
mental note to investigate more thoroughly the flow
splitting arrangement prior to flocculation basins.
Following the plant tour, data collection activities
begin. Depending on team size, the evaluators
split into groups to facilitate simultaneous collection
of the administrative, design, operations,
maintenance and performance data. After data
are collected, the performance assessment and
the major unit process evaluation are conducted. It
is noted that often the utility can provide the per-
formance data prior to the site visit. In this case
the performance graphs can be initially completed
prior to the on-site activities. However, it is
important to verify the sources of the samples and
quality of the data during field efforts.
Field evaluations are also conducted to continue to
gather additional information regarding actual plant
performance and confirm potential factors. Once all
of this information is collected a series of inter-
views are completed with the plant staff and
administrators. Initiating these activities prior to
the interviews provides the evaluators with an
understanding of current plant performance and
plant unit process capability, which allows interview
questions to be more focused on potential factors.
47
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Figure 4-8. Schematic of CPE activities.
Initial Activities
Location
Off-Site
Kick-Off Meeting
Plant Tour
Data Collection Activities
Administration
Data
Design
Data
Operations
Data
Maintenance
Data
Performance
Data
On-Site
Off-Site
48
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After all information is collected, the evaluation
team meets at a location isolated from the utility
personnel to review findings. At this meeting, fac-
tors limiting performance of the plant are identified
and prioritized and an assessment of the applica-
bility of a follow-up CTA is made. The prioritized
list of factors, performance data, field evaluation
results, and major unit process evaluation data are
then compiled and copied for use as handouts
during the exit meeting. An exit meeting is held
with appropriate operations and administration
personnel where all evaluation findings are pre-
sented. Off-site activities include completing and
distributing the written report. A more detailed
discussion of each of these activities follows.
4.3.1 Overview
A CPE is typically conducted over a three to five-
day period by a team comprised of a minimum of
two personnel. A team approach is necessary to
allow a facility to be evaluated in a reasonable time
frame and for evaluation personnel to jointly
develop findings on topics requiring professional
judgment. Professional judgment is critical when
evaluating subjective information obtained during
the on-site CPE activities. For example, assessing
administrative versus operational performance lim-
iting factors often comes down to the evaluators'
interpretation of interview results. The synergistic
effect of two people making this determination is a
key part of the CPE process.
Because of the wide range of areas that are evalu-
ated during a CPE, the evaluation team needs to
have a broad range of available skills. This broad
skills range is another reason to use a team
approach in conducting CPEs. Specifically, per-
sons should have capability in the areas shown in
Table 4-6.
Regulatory agency personnel with experience in
evaluating water treatment facilities; consulting
engineers who routinely work with plant evaluation,
design and start-up; and utility personnel with
design and operations experience represent the
types of personnel with appropriate backgrounds
to conduct CPEs. Other combinations of
personnel can be used if they meet the minimum
experience requirements outlined above. Although
teams composed of utility management and opera-
tions personnel associated with the CPE facility
can be established, it is often difficult for an internal
team to objectively assess administrative and
operational factors. The strength of the CPE is
best represented by an objective third party review.
4.3.2 Initial Activities
The purpose of the initial activities is to establish
the availability of the required personnel and
documentation. To assure an efficient and com-
prehensive evaluation, key utility personnel and
Table 4-6. Evaluation Team Capabilities
Technical Skills
• Water treatment plant design
• Water treatment operations and
process control
• Regulatory requirements
• Maintenance
• Utility management (rates,
budgeting, planning)
Leadership Skills
• Communication (presenting, listening,
interviewing)
• Organization (scheduling, prioritizing)
• Motivation (involving people, recognizing staff
abilities)
• Decisiveness (completing CPE within time frame
allowed)
• Interpretation (assessing multiple inputs, making
judgments)
49
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specific information need to be available.
Required information includes basic data on the
plant design, staffing and performance. A letter
should be sent to the utility describing the schedule
of activities that will take place and outlining the
commitment required of plant and administrative
staff. An example letter is presented in Appen-
dix H. Topics that are discussed in the letter are
presented below.
4.3.2.1 Key Personnel
It is necessary to have key people available during
the conduct of the CPE. The plant superintendent,
manager or other person in charge of the water
treatment facility must be available. If different
persons are responsible for plant maintenance and
process control, their presence should also be
required. These individuals should be available
throughout the three to five-day on-site activities.
A person knowledgeable about details of the utility
budget must also be available. A one- to two-hour
meeting with this person will typically be required
during the on-site activities to assess the financial
information. In many small communities, this per-
son is most often the City Clerk; in small water
districts it may be the Chairman of the Board or a
part-time clerk. In larger communities, the Finance
Director, Utilities Director, or Plant Superintendent
can usually provide the required information.
Availability of key administrative personnel is also
required. In many small communities or water
districts, an operator or plant superintendent may
report directly to the mayor or board chairman or to
the elected administrative body (e.g., City Council
or District Board). In larger communities, the key
administrative person is often the Director of Public
Works/Utilities, City Manager, or other non-elected
administrator. In all cases the administrator(s) as
well as representative elected officials who have
the authority to effect a change in policy or budget
for the plant should be available to participate in
the evaluation. Typically these people are needed
for a one-half to three-quarter hour interview and to
attend the kick-off and exit meetings.
4.3.2.2 CPE Resources
Availability of specific utility and plant information is
required during a CPE. The following list of the
necessary items should be provided to the utility
contact for review at the kick-off meeting and
before initiating on-site activities:
• Engineering drawings and specifications which
include design information on the individual
unit processes, and plant equipment.
• A plant flow schematic.
• Daily plant performance summaries showing
the results of turbidity measurements on raw,
settled, and filtered water for the most recent
twelve-month period.
• Financial information showing budgeted and
actual revenues and expenditures (i.e., chemi-
cals, salaries, energy, training), long-term debt,
water rates and connection fees.
• An organizational chart of the utility.
• A list of utility staff members.
In addition to the information listed, meeting and
work rooms are required during the conduct of the
CPE. A meeting room large enough for the
evaluation team and utility personnel should be
available for the kick-off and exit meetings. During
the CPE, a somewhat private work room with a
table and electrical outlets is desirable. Two or
three small rooms or offices are necessary for the
individual interviews.
Some facilities do not have a sample tap available
on the effluent from each individual filter. If these
taps are not available they should be requested
prior to the on-site activities. During the CPE,
existing taps should be checked to see if they are
functional. All taps both new and existing must be
located at points that assure a continuous sample
stream that is representative of the filter effluent.
4.3.2.3 Scheduling
A typical schedule for on-site CPE activities for a
small to medium-sized water treatment facility is
presented below:
• First Day - a.m. (travel)
First Day- p.m.:
• Conduct kick-off meeting.
50
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Conduct plant tour.
Set-up and calibrate continuous recording
turbidimeter (if available).
Coordinate location of CPE resources.
• Second Day-a.m.:
Compile data on plant performance,
design, administration, operations and
maintenance.
• Second Day-p.m.:
• Continue data compilation.
• Develop performance assessment and
performance potential graph.
• Third Day-a.m.:
• Conduct interviews with plant staff and
utility officials.
• Conduct field evaluations.
• Third Day-p.m.:
• Shut down continuous recording turbi-
dimeter (if available).
• Meet to identify and prioritize performance
limiting factors.
• Prepare materials for exit meeting.
• Fourth Day-a.m.:
• Conduct exit meeting.
• Meet to debrief and make follow-up
assignments.
4.3.3 On-Site Activities
4.3.3.1 Kick-Off Meeting
A short (i.e., 30-minute) meeting between key plant
operations and administration staff and the
evaluators is held to initiate the field work. The
major purposes of this meeting are to present the
objectives of the CPE effort, to coordinate and
establish the schedule, and to initiate the adminis-
trative evaluation activities. Each of the specific
activities that will be conducted during the on-site
effort should be described. Meeting times for
interviews with administration and operations per-
sonnel should be scheduled. Some flexibility with
the interview schedules should be requested since
time for data development, which is essential prior
to conducting interviews, is variable from facility to
facility. A sign-up sheet (see Appendix F) may be
used to record attendance and as a mechanism for
recognizing names. Information items that were
requested in the letter should be reviewed to
ensure their availability during the CPE.
Observations that can contribute to the identifica-
tion of factors are initiated during the kick-off
meeting. More obvious indications of factors may
be lack of communication between the plant staff
and administration personnel or the lack of famili-
arity with the facilities by the administrators. More
subtle indications may be the priority placed on
water quality or policies on facility funding. These
initial perceptions often prove valuable when
formally evaluating administrative factors later in
the CPE effort.
4.3.3.2 Plant Tour
A plant tour follows the kick-off meeting. The
objectives of the tour include: 1) familiarize the
evaluation team with the physical plant; 2) make a
preliminary assessment of operational flexibility of
the existing processes and chemical feed systems;
and 3) provide a foundation for discussions on
performance, process control and maintenance
and continued observations that may indicate per-
formance limiting factors. A walk-through tour
following the flow through the plant (i.e., source to
clean/veil) is suggested. Additionally, the tour
should include backwash and sludge treatment
and disposal facilities, and the laboratory and
maintenance areas. The evaluator should note the
sampling points and chemical feed locations as the
tour progresses.
The CPE evaluation is often stressful, especially
initially, for plant personnel. Consequently, during
the conduct of a tour, as well as throughout the on-
site activities, the evaluation team should be
sensitive to this situation. Many of the questions
asked by the evaluation team on the plant tour are
asked again during formal data collection activities.
The plant staff should be informed that this repeti-
tiveness will occur. Questions that challenge cur-
rent operational practices or that put plant person-
nel on the defensive must be avoided. It is
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imperative that the CPE evaluators create an open,
non-threatening environment so that all of the plant
staff feel free to share their perspective as various
questions are asked. The evaluator should try to
maintain an information gathering posture at all
times. It is not appropriate to recommend changes
in facilities or operational practices during the plant
tour or the conduct of on-site activities. This is
often a challenge since the evaluation team will
frequently be asked for an opinion. Handle these
requests by stating that observations of the CPE
team will be presented at the conclusion of the on-
site activities after all information is collected and
analyzed.
The plant tour continues the opportunity for the
evaluator to observe intangible items that may
contribute to the identification of factors limiting
performance (i.e., operator knowledge of the plant
operation and facilities, relationship of process
control testing to process adjustments, the quality
of the relationships between various levels, etc.).
The tour also presents an opportunity to assess
the potential of using minor modifications to
enhance current facility capability. Suggestions to
help the evaluation team meet the objectives of the
plant tour are provided in the following sections.
Pretreatment
Pretreatment facilities consist of raw water intake
structures, raw water pumps, presedimentation
basins and flow measurement equipment. Intake
structures and associated screening equipment
can have a direct impact on plant performance.
For example, if the intake configuration is such that
screens become clogged with debris or the intake
becomes clogged with silt, maintaining a consistent
supply of water may be a problem. While at the
raw water source, questions should be asked
regarding variability of the raw water quality,
potential upstream pollutant sources, seasonal
problems with taste and odors, raw water quantity
limitations, and algae blooms.
Presedimentation facilities are usually only found
at water treatment plants where high variability in
raw water turbidities occurs. If plants are equipped
with presedimentation capability, basin inlet and
outlet configurations should be noted, and the
ability to feed coagulant chemicals should be
determined. Typically, most presedimentation
configurations lower turbidities to a consistent level
to allow conventional water treatment plants
to perform adequately. If presedimentation facili-
ties do not exist, the evaluator must assess the
capability of existing water treatment unit proc-
esses to remove variable and peak raw water tur-
bidities.
Raw water pumping should be evaluated regarding
the ability to provide a consistent water supply and
with respect to how many pumps are operated at a
time. Frequent changing of high volume constant
speed pumps can cause significant hydraulic
surges to downstream unit processes, degrading
plant performance. In addition, operational
practices as they relate to peak flow rates, peak
daily water production, and plant operating hours
should be discussed to assist in defining the peak
instantaneous operating flow rate.
Flow measurement facilities are important to accu-
rately establish chemical feed rates, wash water
rates, and unit process loadings. Questions
should also be asked concerning location, mainte-
nance, and calibration of flow measurement
devices. Discussions of changes in coagulant
dosages with changes in plant flow rate are also
appropriate at this stage of the tour.
Mixing/Flocculation/Sedimentation
Rapid mixing is utilized to provide a complete
instantaneous mix of coagulant chemicals to the
water. The coagulants neutralize the negative
charges on the colloidal particles allowing them to
agglomerate into larger particles during the gentle
mixing in the flocculation process. These heavier
particles are then removed by settling in the quies-
cent area of the sedimentation basin. These
facilities provide the initial barrier for particle
removal and, if properly designed and operated,
reduce the particulate load to the filters, allowing
them to "polish" the water. During the tour,
observations should be made to determine if the
mixing, flocculation, and sedimentation unit proc-
esses are designed and operated to achieve this
goal. The evaluators should also observe flow
splitting facilities and determine if parallel basins
are receiving equal flow distribution.
Rapid mix facilities should be observed to deter-
mine if adequate mixing of chemicals is occurring
throughout the operating flow range. The operator
should be asked what type of coagulants are being
added and what process control testing is
employed to determine their dosage. Observations
should be made as to the types of chemicals that
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are being added together in the mixing process.
For example, the addition of alum and lime at the
same location may be counter-productive if no
consideration is given to maintaining the optimum
pH for alum coagulation. If coagulant chemicals
are added without mixing, observations should be
made as to possible alternate feed locations, such
as prior to valves, orifice plates or hydraulic jumps,
where acceptable mixing might be achieved.
When touring flocculation facilities, the evaluator
should note inlet and outlet conditions, number of
stages, and the availability of variable energy
input. Flocculation facilities should be baffled to
provide even distribution of flow across the basin
and to prevent velocity currents from disrupting
settling conditions in adjacent sedimentation
basins. If multiple stages are not available, the
capability to baffle a basin to create additional
staging should be observed. The ability to feed
flocculation aids to the gentle mixing portion of the
basin should be noted. The operator should be
asked how often flocculation energy levels are
adjusted or if a special study was conducted to
determine the existing levels. In the case of
hydraulic flocculation, the number of stages, the
turbulence of the water, and the condition of the
floe should be noted to determine if the unit proc-
ess appears to be producing an acceptable floe.
For upflow solids contact units, questions con-
cerning control of the amount of solids in the unit
and sludge blanket control procedures should be
asked.
Sedimentation basin characteristics that should be
observed during the tour include visual observa-
tions of performance and observations of physical
characteristics such as configuration and depth.
Performance observations include clarity of settled
water, size and appearance of floe, and presence
of flow or density currents. The general configu-
ration, including shape, inlet conditions, outlet
conditions, and availability of a sludge removal
mechanism should be observed. Staff should be
asked about process control measures that are
utilized to optimize sedimentation, including sludge
removal.
Chemical Feed Facilities
A tour of the chemical feed facilities typically
requires a deviation from the water flow scheme in
order to observe this key equipment. Often all
chemical feed facilities are located in a central
location that supplies various chemicals to feed
points throughout the plant. Chemical feed facili-
ties should be toured to observe the feed pumps,
day tanks, bulk storage facilities, flow pacing
facilities, and chemical feeder calibration equip-
ment. Availability of backup equipment to ensure
continuous feeding of each chemical during plant
operation should also be observed.
Filtration
Filters represent the key unit process for the
removal of particles in water treatment. Careful
observation of operation and control practices
should occur during the tour. The number and
configuration of filters should be noted, including
the type of filter media. The filter rate control
equipment should be observed and discussed to
ensure that it regulates filter flow in an even, con-
sistent manner without rapid fluctuations. The flow
patterns onto each filter should be noted to see if
there is an indication of uneven flow to individual
filters. Backwash equipment, including pumps and
air compressors, should be noted. The availability
of back-up backwash pumping is desirable to avoid
interruptions in treatment if a breakdown occurs.
The operator should be asked how frequently fil-
ters are backwashed and what process control
procedures are used to determine when a filter
should be washed. Since turbidity represents an
indication of particles in the water, it should be the
parameter utilized to initiate a backwash unless the
plant has on-line particle counters. The operator's
response to this inquiry helps to demonstrate his
understanding and priorities concerning water
quality.
The tour guide should also be questioned con-
cerning the backwash procedure and asked if all
operators follow the same technique. The
evaluation team should determine if filter to waste
capability exists and, if so, how it is controlled.
Questions concerning individual filter monitoring
should also be asked. The availability of turbidity
profiles following backwash should be determined.
Some facilities utilize particle counting to assess
filter performance, and the availability of this
monitoring tool should be determined during the
plant tour.
The tour is an excellent time to discuss the selec-
tion of a filter and the location of the sampling point
for continuous turbidity monitoring to be
53
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conducted during the field evaluation activities.
Ideally, the filter that is most challenged to produce
high quality water should be monitored by the
evaluation team. Often, the operational staff will
be able to quickly identify a "problem filter."
Disinfection
The evaluation team should tour disinfection facili-
ties to become familiar with the equipment feed
points and type of contact facilities. Special atten-
tion should be given to the configuration and baf-
fling of clean/veils and finished water reservoirs that
provide contact time for final disinfection.
Observation of in-line contact time availability
should be made by noting the proximity of the "first
user" to the water treatment plant. Often,
distribution piping cannot be used in the assess-
ment of contact time since the plant staff repre-
sents the first user.
The availability of back-up disinfection equipment
should be determined to assess the capability of
providing an uninterrupted application of disinfec-
tant. The addition of a disinfectant prior to filtra-
tion, either as an oxidizing agent or disinfectant,
should also be noted. The capability to automati-
cally control the disinfection systems by flow
pacing should be determined.
Backwash Water and Sludge Treatment and
Disposal
The location of any recycle streams should be
identified during the tour. Recycle of water should
be assessed with respect to the potential for
returning a high concentration of cysts to the plant
raw water stream. Since this practice represents a
potential risk, the evaluator should determine the
method of treatment or other methods used to
handle the impact of recycle streams (e.g., storage
for equalization of flows with continuous return of
low volumes of recycle to the raw water). It is
also important to assess if plant piping allows col-
lection of a representative sample of recycle to be
used in jar tests to determine coagulant dose.
Typically, the main sources of recycle flows are the
settled filter backwash water and sedimentation
basin sludge decant. If these streams are dis-
charged to a storm sewer system or a waterway,
questions should be asked to determine if the dis-
charge is permitted and if permit requirements are
being complied with. If recycle treatment facilities
exist, questions should be asked to determine the
method of controlling the performance of these
facilities.
Laboratory
The laboratory facilities should be included as part
of the plant tour. Source water and performance
monitoring, process control testing, and quality
control procedures should be discussed with labo-
ratory personnel. It is especially important to
determine if turbidity measurements represent
actual plant performance. The use of laboratory
results should be discussed and a review of the
data reporting forms should also be made. The
laboratory tour also offers the opportunity to
assess the availability of additional plant data that
could be used to assess plant performance (e.g.,
special studies on different coagulants, individual
turbidity profiles). Available analytical capability
should also be noted. An assessment should also
be made if all of the analytical capability resides in
the laboratory and, if so, does the operations staff
have sufficient access to make process control
adjustments?
Maintenance
A tour of the maintenance facilities provides an
opportunity to assess the level of maintenance
support at the plant. Tools, spare parts availability,
storage, filing systems for equipment catalogues,
general plant appearance, and condition of
equipment should be observed. Questions on the
preventive maintenance program, including meth-
ods of initiating work (e.g., work orders), are
appropriate. Equipment out of service should also
be noted.
4.3.3.3 Data Collection Activities
Following the plant tour, data collection procedures
are initiated. Information is collected through
discussions with plant and administrative staff
utilizing a formalized data collection format as
shown in Appendix F. Categories covered by
these forms are listed below:
• Kick-Off Meeting
• Administration Data
• Design Data
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• Operations Data
• Maintenance Data
• Field Evaluation Data
• Interview Guidelines
Exit Meeting
When collecting information requested on the
forms, the evaluation team should solicit the par-
ticipation of the most knowledgeable person in
each of the evaluation areas. For example, those
persons actually implementing the maintenance
activities should be included in the maintenance
data collection efforts.
When collecting information, the evaluator should
be aware that the data are to be used to evaluate
the performance capability of the existing facilities.
The evaluator should continuously be asking "How
does this information affect plant performance?". If
the area of inquiry appears to be directly related to
plant performance, the evaluator should spend
sufficient time to fully develop the information.
Often this pursuit of information will go beyond the
constraints of the forms. In this way, some of the
most meaningful information obtained is "written on
the back of the forms."
4.3.3.4 Evaluation of Major Unit Processes
An evaluation of the plant's major unit processes is
conducted to determine the performance potential
of existing facilities at peak instantaneous
operating flow. This is accomplished by develop-
ing a performance potential graph and rating the
major unit processes as Type 1, 2, or 3, as previ-
ously discussed in 4.2.2 Evaluation of Major Unit
Processes.
It is important that the major unit process evalua-
tion be conducted early during the on-site activi-
ties, since this assessment provides the evaluator
with the knowledge of the plant's treatment capa-
bility. If the plant major unit processes are deter-
mined to be Type 1 or 2 and they are not per-
forming at optimum levels, then factors in the areas
of administration, operation or maintenance are
likely contributing to the performance problems.
The completed major unit process assessment
aids the evaluation personnel in focusing later
interviews and field evaluations to identify those
performance limiting factors.
4.3.3.5 Performance Assessment
An assessment of the plant's performance is made
by evaluating existing recorded data and by con-
ducting field evaluations to determine if unit proc-
ess and total plant performance have been opti-
mized. Typically, the most recent twelve months of
existing process control data is evaluated and
graphs are developed to assess performance of
the plant. Additional data (e.g., backwash turbidity
profiles, particle counting data, individual filter 24-
hour continuous turbidimeter performance) can be
developed if they aid in the determination of the
existing plant performance relative to optimized
goals. Evaluations are also conducted during the
performance assessment activities to determine if
existing plant records accurately reflect actual
plant-treated water quality. Calibration checks on
turbidimeters or a review of quality control proce-
dures in the laboratory are part of these evalua-
tions.
It is conceivable that a public health threat could
be indicated by the data during the development of
the data for the performance assessment compo-
nent. The CPE evaluation team will have to
handle these situations on a case-by-case basis.
An immediate discussion of the potential threat
should be conducted with the plant staff and
administration and they should be encouraged to
contact the appropriate regulatory agency.
Voluntary actions such as plant shut-down or a
voluntary boil water notice should also be
discussed. It is important that the CPE evaluation
team not assume responsibility for the process
adjustments at the plant.
Another key part of the performance assessment is
the use of a continuous recording turbidimeter
during the conduct of the on-site activities. This
effort will be further described in the next section of
this chapter. A detailed discussion of the methods
utilized in the performance assessment was
presented previously in the Assessment of Plant
Performance section of this chapter.
4.3.3.6 Field Evaluations
Field evaluations are an important aspect of the
on-site activities. Typically, field evaluations are
conducted to verify accuracy of monitoring and
flow records, chemical dosages, record drawings,
filter integrity, and backwash capability. Forms to
assist in the documentation of the data collected
55
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during field evaluations have been included in
Appendix F.
Performance monitoring records can be verified by
utilizing a continuous recording turbidimeter to
assess an individual filter's performance over a
twenty-four hour period. A backwash cycle is
conducted during this monitoring effort. It is
important that the evaluation team acquire or have
made available to them a properly calibrated tur-
bidimeter to support this field effort. If a recording
on-line turbidimeter is not available, an instrument
that allows individual analysis of grab samples can
be used. If the evaluation team does not have
access to a turbidimeter, the plant's turbidimeter,
which must be calibrated prior to the sampling and
testing activities, can be used.
Treated water quality obtained from the field
evaluation can be compared with recorded data to
make a determination if performance monitoring
records accurately represent treated water quality.
Differences in actual versus recorded finished
water quality can be caused by sampling location,
sampling time, sampling procedures, and testing
variations. The evaluation team's instrument can
also be used to assess the plant's turbidimeter and
calibration techniques.
The accuracy of flow records can be verified by
assessing the calibration of flow measurement
equipment. This is often difficult because of the
type of meters utilized (e.g., propeller, venturi,
magnetic). If these types of meters are utilized, it
may be necessary to require a basin to be filled or
drawn down over a timed period to accurately
check the metering equipment. If accuracy of
metering equipment is difficult to field-verify, the
frequency of calibration of the equipment by the
plant staff or outside instrumentation technicians
can be evaluated. If flow metering equipment is
being routinely (e.g., quarterly or semiannually)
calibrated, flow records typically can be assumed
to be accurate.
Dosages of primary coagulant chemicals should be
verified. Feed rates from dry feeders can be
checked by collecting a sample for a specified time
and weighing the accumulated chemical. Similarly,
liquid feeders can be checked by collecting a
sample in a graduated cylinder for a specified time.
In both cases the feed rate in Ib/min or mL/min of
chemical should be converted to mg/L and com-
pared with the reported dosage. During this
evaluation the operating staff should be asked how
they conduct chemical feed calculations, pre
pare polymer dilutions, and make chemical feeder
settings. Additionally, the plant staff should be
asked how they arrived at the reported dosage. If
jar testing is used, the evaluation team should dis-
cuss this procedure, including preparation of stock
solutions. Often, a discussion can be used to
assess the validity and understanding of this
coagulation control technique. Performing jar tests
is typically not part of the CPE process.
The integrity of the filter media, support gravels,
and underdrain system for a selected filter should
be evaluated. This requires that the filter be
drained and that the evaluation team inspect the
media. The filter should be investigated for surface
cracking, proper media depth, mudballs and
segregation of media in dual media filters. The
media can be excavated to determine the depth of
the different media layers in multi or dual media
filters. The media should be placed back in the
excavations in the same sequence that it was
removed. The filter should also be probed with a
steel rod to check for displacement of the support
gravels and to verify the media depth within the
filter. Variations in depth of support gravels of over
two inches would signify a potential problem.
Variations in media depth of over two inches would
also indicate a potential problem. If possible, the
clear well should be observed for the presence of
filter media. Often, plant staff can provide
feedback on media in the clean/veil if access is
limited. If support gravels or media loss are
apparent, a more detailed study of the filter would
then be indicated, which is beyond the scope of a
CPE.
Filter backwash capability often can be determined
from the flow measurement device on the back-
wash supply line. If this measurement is in ques-
tion or if the meter is not available, the backwash
rate should be field-verified by assessing either the
backwash rise rate or bed expansion. Rise rate is
determined by timing the rise of water for a specific
period. For example, a filter having a surface area
of 150 ft2 would have a backwash rate of
20 gpm/ft2 if the rise rate was 10.7 inches in
20 seconds. This technique is not suitable for
filters where the peak backwash rate is not
reached until the washwater is passing over the
troughs.
Bed expansion is determined by measuring the
distance from the top of the unexpanded media to
a reference point (e.g., top of filter wall) and from
the top of the expanded media to the same refer-
ence point. The difference between these two
56
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measurements is the bed expansion. A variety of
techniques can be used to determine the top of the
expanded bed. A light-colored can lid attached to
the end of a pole is effective. The bed expansion
measurement divided by the total depth of
expandable media (i.e., media depth less gravels)
multiplied times 100 gives the percent bed expan-
sion. A proper wash rate should expand the filter
media a minimum of 20 to 25 percent (4).
Record drawings may have to be field-verified by
measuring basin dimensions with a tape measure
if there is doubt as to their accuracy. If no
drawings are available, all basin dimensions will
have to be measured.
Additional field tests such as verification of equal
flow splitting and calibration of monitoring or labo-
ratory equipment can also be conducted. Field
verification to support identified factors limiting
performance should always be considered by the
evaluation team; however, time requirements for
these activities must be weighed against meeting
the overall objectives of the CPE.
4.3.3.7 Interviews
Prior to conducting personnel interviews, it is nec-
essary to complete the data collection forms, the
major unit process evaluation, and performance
assessment. This background information allows
the evaluator to focus interview questions on
anticipated factors limiting performance. It is also
advantageous for the CPE evaluators to be familiar
with the factors outlined in Appendix E prior to
conducting the interviews. This awareness also
helps to focus the interviews and to maintain the
performance emphasis of the interview process.
For example, an adamantly stated concern
regarding supervision or pay is only of significance
if it can be directly related to plant performance.
Unless the number of the utility staff is too large,
interviews should be conducted with all of the plant
staff and with key administrative personnel in order
to obtain feedback from both resources. Example
key administrators include the mayor, board
members from the Water Committee, and the
Utility Director.
Interviews should be conducted privately with each
individual. The persons being interviewed should
be informed that the responses are presented in
the findings as an overall perception, and
individual responses are not utilized in the exit
meeting or final report. Approximately 30 to 45
minutes should be allowed for each interview.
Interviews are conducted to clarify information
obtained from plant records and on-site activities
and to ascertain differences between real or per-
ceived problems. Intangible items such as com-
munication, administrative support, morale, and
work attitudes are also assessed during the inter-
view process. The interviews also offer an oppor-
tunity to ask questions about potential factors.
During the conduct of on-site activities, the CPE
evaluators begin to form preliminary judgments.
The interviews offer the opportunity to ask, in an
information gathering forum, what the utility per-
sonnel may think of the perceived limitation. An
adamant response may justify additional data col-
lection to strengthen the evaluation team's convic-
tions prior to the exit meeting. On the other hand,
sensitive findings such as operational and adminis-
trative limitations can be introduced in a one-on-
one setting and will allow the affected parties to be
aware that these issues may be discussed at the
exit meeting.
Interview skills are a key attribute for CPE evaluat-
ors. Avoidance of conflict, maintaining an infor-
mation gathering posture, utilizing initial on-site
activity results, creating an environment for open
communication, and pursuing difficult issues (e.g.,
supervisory traits) are a few of the skills required to
conduct successful interviews. An additional
challenge to the CPE evaluators is to avoid pro-
viding "answers" for the person being interviewed.
A major attribute is the ability to ask a question and
wait for a response even though a period of silence
may exist.
A key activity after conducting several interviews is
for the evaluation team members to discuss their
perceptions among themselves. Often, conflicting
information is indicated, and an awareness of
these differences can be utilized to gather addi-
tional information in remaining interviews. To
assist in conducting interviews, guidelines have
been provided in Appendix F - Interview Guide-
lines.
4.3.3.8 Evaluation of Performance Limiting
Factors
The summarizing effort of the on-site activities is
identification and prioritization of performance lim-
iting factors. This activity should be completed at a
location that allows open and objective
57
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discussions to occur (e.g., away from utility
personnel). Prior to the discussion, a debriefing
session that allows the evaluation team to discuss
pertinent findings from their respective efforts
should be held. This step is especially important
since each team member is typically not involved
in every aspect of the CPE. All data compiled
during the evaluations should be readily available
to support the factor identification efforts.
The checklist of performance limiting factors pre-
sented in Appendix E, as well as the factor defini-
tions, provides the structure for an organized
review of potential factors in the evaluated facility.
The intent is to identify, as clearly as possible, the
factors that most accurately describe the causes of
limited performance. Often, a great deal of dis-
cussion is generated in this phase of the CPE
effort. Sufficient time (i.e., 2 to 8 hours) should be
allocated to complete this step, and all opinions
and perceptions should be solicited. It is particu-
larly important to maintain the performance focus
during this activity. A natural bias is to identify all
factors that may have even a remote application at
the current facility. Persons new to this phase of a
CPE often want to make sure that they do not miss
anything in identifying deficiencies. An excellent
method to maintain focus is to remember that the
list of factors is the evaluation team's attempt to
prioritize the future efforts for the utility. If the total
number of factors is greater than 10, the evaluation
team should reassess the factors identified and
look for ways to clarify the message that will be
sent during the exit meeting. One option would be
to combine factors and use the examples given
when the factor was identified to provide greater
justification as to why the "combined factor" is
limiting performance. Another incentive to reduce
the number of factors is that extraneous factors
can confuse the utility's future activities and divert
focus from priority optimization efforts. Often, it is
the factors that are not identified that are important
since by not identifying factors, the team
discourages future emphasis in these areas.
One of the most difficult challenges facing a CPE
evaluator can be the identification of administrative
factors since the team may find itself criticizing
high level administrators and the culture that they
have created. This can be especially difficult in
situations where these same administrators have
contracted for the CPE and may be current and
future clients. Given these pressures, the CPE
team may find themselves avoiding identifying any
administrative factors when there is clear evidence
that the administrator in question is having a direct
impact on performance. If a CPE team finds
themselves in this situation they should review
their responsibility in protecting public health and
the long term good that will occur if the adminis-
trative factors are addressed. Those responsible
for the review of CPE reports should also question
a CPE report that fails to identify any administrative
factors.
Each factor identified as limiting performance
should be assigned an "A", "B", or "C" rating.
Further prioritization is accomplished by complet-
ing the Summary Sheet presented in Appendix E.
Only those factors receiving either an "A" or "B"
rating are prioritized on this sheet. A goal of the
prioritization activity is to provide a clear story and
an associated clear set of priorities for the utility to
use to pursue optimized performance at the con-
clusion of the CPE. Additional guidance for iden-
tifying and prioritizing performance limiting factors
was provided in the Identification and Prioritization
of Performance Limiting Factors section previously
discussed in this chapter.
4.3.3.9 Exit Meeting
Once the evaluation team has completed the on-
site activities, an exit meeting should be held with
the plant administrators and staff. A presentation
of CPE results should include descriptions of the
following:
• Overview of optimized treatment goals
• Plant performance assessment
• Evaluation of major unit processes
• Prioritized performance limiting factors
• Assessment of applicability of follow-up
The overview of optimized treatment goals is pre-
sented to establish the basis upon which the utility
was evaluated. It is important to identify that the
CPE evaluation was based on goals, likely more
stringent than the plant was designed for and more
stringent than regulated performance criteria. The
positive public health aspects of achieving this
level of performance should also be discussed.
Chapter 2 described the optimized performance
goals and the public health benefits of achieving
these goals. A synopsis of this information should
be presented at the beginning of the exit meeting.
A brief presentation on the function of each water
treatment unit process and the effort required to
58
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produce acceptable finished water quality can also
be made to enhance water treatment understand-
ing for the administrators.
Handouts, based on information developed during
the on-site activities, can be utilized to assist in
presenting the other exit meeting topics. Graphs
are effective for presenting the performance
assessment findings. Typically, the time versus
turbidity plots (one year of data) and percentile
plots for raw, settled and filtered and/or finished
water are presented. Additionally, results of field
evaluations such as turbidity profiles following a
filter backwash, 24-hour individual filter perform-
ance profiles, or particle counting data may be
presented. The objective of this portion of the exit
meeting is to clearly establish the utility's historical
and existing performance relative to optimized per-
formance goals. If optimized performance is not
being achieved, this presentation establishes the
foundation for the remaining exit meeting topics. If
the CPE reveals that the treatment plant perform-
ance represents a significant health risk, this
should be carefully explained to the utility staff.
Regulatory personnel conducting such a CPE
should determine if administrative or regulatory
action should be implemented and should
establish a time frame to protect public health (e.g.,
immediately).
The performance potential graph summarizes the
major unit process evaluation. If Type 1 unit pro-
cesses are indicated, the utility participants can be
told that physical facilities were not determined to
be limiting the plant's ability to achieve optimized
performance goals. Type 2 unit processes do not
necessarily indicate a construction need, and the
potential of "operating around" these deficiencies
can be presented. Type 3 unit processes demon-
strate the need for construction alternatives.
The summary of prioritized performance limiting
factors and a supplemental summary of key points
that were used to identify these factors are the
handouts utilized for this portion of the exit
meeting. Throughout the presentation, the evalua-
tor must remember that the purpose is to identify
and describe facts to be used to improve the cur-
rent situation, not to place blame for any past or
current problems. Depending on the factors iden-
tified, this portion of the exit meeting can be the
most difficult to present. Factors in the areas of
operation and administration offer the greatest
challenge. The evaluation team must "tell it like it
is" but in a constructive and motivational manner.
Little impact can be expected if this presentation is
softened to avoid conflict or adverse feedback from
the utility staff. At the same time, it is also
important that the factors not be presented so
harshly that it creates an overly hostile environ-
ment, where the plant staff are so angry that they
don't listen to CPE findings. Experience is valuable
in balancing the presentation of difficult findings
and achieving a motivational response. Often, it is
valuable to have one person initiate the presenta-
tion of the findings with the option available for
other team members to support the discussion.
Arguments should be avoided during presentation
of the factors.
It is emphasized that findings, and not recommen-
dations, be presented at the exit meeting. The
CPE, while comprehensive, is conducted over a
short time and is not a detailed engineering study.
Recommendations made without appropriate fol-
low-up could confuse operators and administrators,
lead to inappropriate or incorrect actions on the
part of the utility staff, and ultimately result in
improper technical guidance. For example, a rec-
ommendation to set coagulant dosages at a spe-
cific level could be followed literally to the extent
that operations staff set coagulant dosages at the
recommended level and never change them even
though time and highly variable raw water condi-
tions should have resulted in dosage adjustments.
An assessment of the value of follow-up activities
should be discussed at the exit meeting. The utility
may choose to pursue addressing performance
limiting factors on their own. The CPE evaluators
should emphasize the need to comprehensively
address the factors identified. A piecemeal
approach to address only the design limitations
likely would not result in improved performance if
adverse operation and administration factors
continue to exist. It should also be made clear at
the exit meeting that other factors are likely to
surface during the conduct of any follow-up activi-
ties. These factors will also have to be addressed
to achieve the desired performance. This under-
standing of the short term CPE evaluation capabili-
ties is often missed by local and regulatory offi-
cials, and efforts may be developed to address
only the items prioritized during the CPE. The
evaluator should stress that a commitment must be
made to achieve the desired optimized perform-
ance, not to address a "laundry list" of currently
identified problems.
It is important to present all findings at the exit
meeting with utility staff. This approach eliminates
surprises when the CPE report is received.
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An ideal conclusion for an exit meeting is that the
utility fully recognizes its responsibility to provide a
high quality finished water and that, provided with
the findings from the CPE, the utility staff are
enthusiastic to pursue achievement of this goal.
4.3.4 CPE Report
At the conclusion of the on-site activities, a CPE
report is prepared. The objective of a CPE report
is to summarize findings and conclusions. Ten to
fifteen typed pages are generally sufficient for the
text of the report. The CPE report should be
available within a month following the on-site
activities to reinforce the need to address factors
limiting optimized performance. An example report
is presented in Appendix G. Typical contents are:
• Introduction
• Facility Information
• Performance Assessment
• Major Unit Process Evaluation
• Performance Limiting Factors
• Assessment of Applicability of a CTA
4.4 Case Study
The following case study provides insights on the
conduct of a CPE at an actual water utility. The
state regulatory agency had identified in their
review of monthly monitoring reports that a con-
ventional water treatment plant was routinely vio-
lating the 0.5 NTU limit on finished water turbidity.
The state notified the community that they
intended to conduct a CPE to identify the reasons
for non-compliance with current regulatory
requirements.
4.4.1 Facility Information
Facility A serves a community of 10,000 people
and is located in an area with a temperate climate.
The facility was designed to treat 5.0 MGD. Nor-
mally during the year the plant is operated for
periods ranging from 5 to 12 hours each day.
During operation, the facility is always operated at
a flow rate of 5 MGD. A flow schematic of the
facility is shown in Figure 4-9.
The following data were compiled from the com-
pleted data collection forms, as presented in
Appendix F.
As a minimum, the CPE report should be distrib-
uted to plant administrators, and they should be
requested to distribute the report to key plant per-
sonnel. Further distribution of the report (e.g., to
regulatory personnel or to the design consultant)
depends on the circumstances of the CPE.
Design Flow: 5.0 MGD
Average Daily Flow: 1.2 MGD
Peak Daily Flow: 4.0 MGD
Peak Instantaneous Operating Flow:
5.0 MGD
Figure 4-9. Flow schematic of Plant A.
Sedimentation
Raw
Cleanwater Creek Water
Pumps
Flash
Mix
Flocculation
_.
-
riltf>
Clearwell/Contact. ,
High Service
Pumps
1
To
Distribution
Sludge to Ponds/
Drying Beds
Backwash to
Pond Supernatant
Returned to Rant
60
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Flocculation:
• Number Trains: 2
• Type: Mechanical turbines, 3 stages
• Dimensions:
* Length: 15.5ft
* Width: 15.5ft
* Depth: 10.0ft
Sedimentation:
• Number Trains: 2
• Type: Conventional rectangular
• Dimensions:
* Length: 90ft
* Width: 30ft
* Depth: 12ft
Filtration:
• Number: 3
• Type: Dual media (i.e., anthracite, sand),
gravity
• Dimensions:
* Length: 18ft
* Width: 18ft
Disinfection:
• Disinfectant: Free chlorine
• Application Point: Clean/veil
• Number: 1
• Clean/veil Dimensions:
* Length: 75ft
* Width: 75ft
* Maximum operating level: 20 ft
* Minimum operating level: 14ft
• Baffling factor: 0.1 based on unbaffled
basin
4.4.2 Performance Assessment
The performance assessment, using the most
recent 12 months of data, indicated that the fin-
ished water turbidity was not meeting the regulated
quality of <0.5 NTU in 95 percent of the samples
collected each month. In fact, the 95 percent
requirement was exceeded in 5 of 12 months. The
raw water turbidity averaged
approximately 15 NTU and the settled water tur-
bidity was measured at 4.3 NTU during the CPE.
Routine sampling of settled water was not being
practiced. Field evaluation of one of three filters
during the on-site activities indicated a turbidity
spike of 1.1 NTU following backwash with a
reduction to 0.6 NTU after one hour of operation.
The results of the performance assessment indi-
cated that optimized performance goals were not
being achieved.
4.4.3 Major Unit Process Evaluation
A performance potential graph (Figure 4-10) was
prepared to assess the capability of Plant A's ma-
jor unit processes. The calculations that were
conducted to complete the graph are shown in the
following four sections.
FIGURE 4-10. Performance potential graph for
Plant A.
Unit Process
Flocculation*1'
Sedimentation*2'
Filtration Rate*3'
Disinfection*4'
0123
Type 1
Type 2
80% of Peak ^
Typel
Type 2
4
I
I
5 6
.x
X I
H
Peak Instantaneous Operating
Flow = 5.0 MOD
(1) Ratedat20min(HDT)-7.8MGD
(2) Rated at 0.6 gpm/ft2 - 4.7 MGD
(3) Rated at 4.0 gpm/ft2 - 5.6 MGD
(4) Rated at 20 min HOT - 4.2 MGD
4.4.3.1 Flocculation Basin Evaluation
The flocculation basins were rated at a hydraulic
detention time of 20 minutes because the floccula-
tion system has desirable flexibility (i.e., three
stages with each stage equipped with variable
speed flocculators). The plant is also located in a
temperate climate, so the temperature criteria is
< = 0.5°C.
61
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1. Basin Volume
= 6 basins x 15.5 ft x
15.5 ft x 10 ft x 7.48 gal/ft3
= 107,824 gallons
2. Select 20-minute detention time to determine
peak rated capability.
3. Rated Capability = 107,824 gal/20 minutes
= 5,391 gpm x
1 MGD
694.4 gpm
= 7.8 MGD
The 20-minute detention time results in a rated
capability of 7.8 MGD. Therefore, the flocculation
system is rated Type 1 because the 7.8 MGD
exceeds the peak instantaneous plant flow of
5.0 MGD.
1. Filter Area
= 3 filters x 18 ft x 18 ft
= 972ft2
2. Select 4 gpm/ft to determine peak rated capa-
bility.
3. Rated Capability = 972 ft2 x 4 gpm/ft2
= 3,888 gpm x 1 MGD
694.4 gpm
= 5.6 MGD
The 4 gpm/ft rate results in a rated capability of
5.6 MGD. The filters were rated Type 1 because
5.6 MGD exceeds the peak instantaneous operat-
ing flow of 5.0 MGD.
4.4.3.4 Disinfection Process Evaluation
4.4.3.2 Sedimentation Basin Evaluation
The sedimentation basins were rated at 0.6 gpm/ft2
surface overflow rate. This mid-range criteria was
selected based on the basin depth of 12 ft and the
observed poor performance during the on-site
activities.
1. Basin Surface Area = 2 basins x 90 ft x 30 ft
= 5,400 ft2
2. Select 0.6 gpm/ft2 surface overflow rate to
determine peak rated capability.
3. Rated Capability = 5,400 ft2 x 0.6 gpm/ft2
= 3,240 gpm x 1 MGD
694.4 gpm
= 4.7 MGD
The 0.6 gpm/ft2 overflow rate results in a rated
capability of 4.7 MGD. The sedimentation basins
are rated Type 2 because the 4.7 MGD rating falls
within 80 percent of the 5 MGD peak instantane-
ous operating flow.
4.4.3.3 Filter Evaluation
The filters were rated at 4 gpm/ft2 filtration rate
based on dual-media with adequate backwashing
capability.
The disinfection system was evaluated based on
post-disinfection capability only since prechlorina-
tion was not practiced at Plant A.
1. Determine required Giardia log reduction/
inactivation based on raw water quality. Select
3.0 log, based on state regulatory agency
requirement.
2. Determine CT based on minimum water tem-
perature and maximum treated water pH.
From plant records select:
Temperature (minimum) = 0.5°C
pH (maximum) = 7.5
3. Determine log inactivation required by disinfec-
tion.
Allow 2.5 log reduction because plant is con-
ventional facility in reasonable condition with a
minimum Type 2 rating in previous unit proc-
ess evaluation.
Log inactivation required by disinfection =
3.0-2.5 = 0.5
4. Determine CT required for 0.5 log inactivation
of Giardia at pH = 7.5
T = 0.5°C, free chlorine residual = 2.5 mg/L.
From tables in Appendix D, CT = 50.5 mg/
L-min
62
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5. Determine required contact time based on
maximum free chlorine residual that can be
maintained.
Required contact time = 50.5 mg/L-min
2.5 mg/L
= 20 min
6. Determine effective clean/veil (contact basin)
volume required to calculate peak rated
capacity.
Effective volume*= 75 ft x 75 ft x
14ft x 0.1 x 7.48 gal/ft3
= 58,905 gallons
*Basin is unbaffled so use T10/T factor of 0.1 .
Use 14' minimum operating depth.
7. Determine rated capability:
58,905 gal
Rated Capability = 2Q
= 2.945gpmx 1MGD
694.4gpm
= 4.2 MGD
The 20 minute HOT results in a rated capa-
bility of 4.2 MGD. The disinfection system
was rated Type 2 because 4.2 MGD falls
within 80 percent of the peak instantaneous
plant flow of 5.0 MGD.
Based on the above calculations, a performance
potential graph was prepared. The performance
potential graph for Plant A is shown in Figure 4-10.
As shown, flocculation and filtration were rated
Type 1 because their rated capabilities exceeded
the peak instantaneous operating flow rate of
5.0 MGD. Sedimentation and post-disinfection unit
process were rated Type 2 because rated capacity
was within 80% of the peak instantaneous oper-
ating flow rate.
It is noted that the option to operate the facility for
a longer period of time to lower the peak instanta-
neous operating flow exists at Plant A. The aver-
age daily flow rate on an annual basis is 1.2 MGD.
If the plant were operated for 8 hours per day at
3.6 MGD, the average demand could be met at a
flow rate below the projected capability of all of the
major unit processes. For peak demand days,
exceeding 3.6 MGD, the plant would require
longer periods of operation. This option offers the
capability to avoid major construction and still pur-
sue optimized performance with the existing facili-
ties.
4.4.4 Performance Limiting Factors
The following performance limiting factors were
identified during the CPE and were given ratings of
"A" or "B." Further prioritization of these factors
was also conducted, as indicated by the number
assigned to each factor.
1. Application of Concepts and Testing to Proc-
ess Control - Operation (A)
• The plant operators had established no
process control program to make deci-
sions regarding plant flow rate, coagulant
dose and filter operation.
• Coagulant dosages had not been estab-
lished based on jar tests or other means
and were typically maintained at a con-
stant setting despite raw water quality
variations.
• Filters were started dirty on a routine
basis and the plant was operated at
maximum capacity when a much lower
rate was possible.
• Filter effluent turbidities exceeded regula-
tory requirements for extended periods
following backwash of a filter.
• The operator's lack of awareness of the
existence or impact of these spikes dem-
onstrated a limited understanding of water
treatment technology and the importance
of producing high quality treated water on
a continuous basis.
2. Process Control Testing - Operation (A)
• The only process control testing that was
conducted was turbidity on daily grab
samples of raw water and treated water
from the clean/veil and chlorine residual
on treated water after the high service
pumps.
• No process control testing was done to
establish coagulant dosages or optimized
sedimentation and filtration unit process
performance.
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3. Plant Coverage - Administration (A)
• Plant operators were only allowed enough
time to be at the plant to fill the reservoir,
approximately six hours each day.
• On occasion, the alum feed line would
plug and go unnoticed, resulting in peri-
ods of poor treated water quality.
• The operators were expected to conduct
other activities, such as monitoring the
city swimming pool, assisting wastewater
treatment plant operators, and assisting
street maintenance crews during summer
months.
4. Disinfection - Design (B)
• Operation of the plant at maximum flow
rate does not allow sufficient contact time
for disinfection. However, operation of
the plant at or below 4.2 MGD allows the
disinfection unit process to be in compli-
ance with existing regulations.
5. Sedimentation - Design (B)
• The sedimentation basin was not pro-
jected to be capable of achieving opti-
mized performance criteria at flows above
4.7 MGD. Reducing the flow would allow
the basin to perform adequately during
most periods of the year.
6. Sample Taps - Design (B)
• Sample taps do not exist to allow samples
to be obtained from the individual filters.
This prevents the plant staff from obtain-
ing needed information to optimize indi-
vidual filter performance.
4.4.5 Assessing Applicability of a CTA
The most serious of the performance limiting fac-
tors identified for Plant A were process control-
oriented. The evaluation of major unit processes
resulted in a Type 2 rating at the present peak
instantaneous operating flow. However, it was
determined that the rating could be upgraded to
Type 1 if the plant peak instantaneous operating
flow rate could be reduced by operating for longer
periods of time each day. This adjustment will
require addressing the plant coverage factor by
convincing administrators to allow operators to
spend additional time at the treatment facility. If
plant flow can be reduced and operator coverage
increased, it appears that the utility would be able
to achieve improved performance through imple-
mentation of a follow-up CTA. These conditions
would require approval by the City Council before a
CTA could be initiated. Documentation of
improvement in finished water turbidity, including
reduction of spikes after dirty filter start-up and
backwashing, should result from CTA efforts.
Additionally, maintaining settled water turbidity at <
2 NTU on a continuous basis would be the
expected result from a CTA. These improvements
to optimized performance will enhance the treat-
ment barriers that this facility provides and, thus,
enhance public health protection.
4.4.6 CPE Results
The success of conducting CPE activities can be
measured by plant administrators selecting a fol-
low-up approach and implementing activities to
achieve the required performance from their water
treatment facility. If definite follow-up activities are
not initiated within a reasonable time frame, the
objectives of conducting a CPE have not been
achieved. Ideally, follow-up activities must com-
prehensively address the combination of factors
identified (e.g., implement a CTA) and should not
be implemented in a piecemeal approach. In the
previous example, plant administrators decided to
hire a third party to implement a CTA. The CTA
addressed the identified factors and resulted in the
existing plant achieving optimized performance
goals without major capital improvements.
4.5 References
1. Bender, J.H., R.C. Renner, B.A. Hegg, E.M.
Bissonette, and R. Lieberman. 1995. "Part-
nership for Safe Water Voluntary Water
Treatment Plant Performance Improvement
Program Self-Assessment Procedures."
USEPA, AWWA, AWWARF, Association of
Metropolitan Water Agencies, Association of
State Drinking Water Administrators, and
National Association of Water Companies.
2. Eastern Research Group, Inc. 1992. Water
Advisor Utilizing the CCP Approach (Expert
System). USEPA Work Assignment No. 7391-
55. Eastern Research Group, Inc., Arlington,
MA.
64
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3. Renner, R.C., B.A. Hegg, J.H. Bender, and
E.M. Bissonette. February 1991. Handbook -
Optimizing Water Treatment Plant
Performance Using the Composite Correction
Program. EPA 625/9-91/027. USEPA,
Cincinnati, OH.
4. American Society of Civil Engineers and
American Water Works Association. 1990.
Water Treatment Plant Design. McGraw-Hill,
2nd ed.
5. James M. Montgomery Consulting Engineers,
Inc. 1985. Water Treatment Principles and
Design. John Wiley & Sons, Inc.
6. Sanks, R.L., ed.. 1978. Water Treatment
Plant Design for the Practicing Engineer. Ann
Arbor Science Publishers, Kent, England.
7. Renner, R.C., B.A. Hegg, and J.H. Bender.
March 1990. EPA Summary Report: Opti-
mizing Water Treatment Plant Performance
With the Composite Correction Program. EPA
625/8-90/017, USEPA Center for Environ-
mental Research Information, Cincinnati, OH.
8. "Surface Water Treatment Rule", from Federal
Register, Vol. 54, No. 124, U.S. Environmental
Protection Agency, 40 CFR, Parts 141 and
142, Rules and Regulations, Filtra-
tion/Disinfection (June 1989).
9. USEPA. 1989. Guidance Manual for Compli-
ance With the Filtration and Disinfection
Reguirements for Public Water Systems Using
Surface Water Sources. NTIS No. PB
90148016. USEPA, Washington, DC.
10. Regli, S. June 1990. "How's and Why's of
CTs." Presented at AWWA Annual Confer-
ence, Cincinnati, OH.
11. Cleasby, J.L., M.M. Williamson, and E.R.
Baumann. 1963. "Effect of Filtration Rate
Changes on Quality." Journal AWWA, 55:869-
878.
12. Cleasby, J.L., A.H. Dharmarajah, G.L. Sindt,
and E.R. Baumann. September 1989. Design
and Operation Guidelines for Optimization of
the High Rate Filtration Process: Plant Survey
Results. AWWA Research Foundation and
AWWA, Denver, CO.
65
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Chapter 5
Comprehensive Technical Assistance
5.1 Objective
The objective of conducting Comprehensive Tech-
nical Assistance (CTA) activities is to achieve and
sustain optimized performance goals, as was
described in Chapter 2. Given this objective, the
results of a successful CTA can be easily depicted
in graphical form. Results from an actual CTA are
presented in Figure 5-1. As shown, plant per-
formance was inconsistent as depicted by the
variations in finished water turbidity. However,
after CTA activities had been implemented (April
1997) the treated water quality gradually improved
to a level that has been consistently less than
0.1 NTU. It is noted that other parameters, such
as improved operator capability, cost savings, and
improved plant capacity are often associated with
the conduct of a CTA, but the true measure of
success is the ability to achieve optimized per-
formance goals and demonstrate the capability to
meet these goals long-term under changing raw
water quality conditions. It is recommended that
CTA results be presented graphically to indicate
that the primary objective has been achieved.
An additional objective of a CTA is to achieve opti-
mized performance from an existing water treat-
ment facility (i.e., avoid, if possible, major modifi-
cations). If the results of a Comprehensive Per-
formance Evaluation (CPE) indicate a Type 1 plant
(see Figure 4-3), then existing major unit proc-
esses have been assessed to be adequate to meet
optimized treatment requirements at current plant
loading rates. For these facilities, the CTA can
focus on systematically addressing identified per-
formance limiting factors to achieve optimized per-
formance goals.
For Type 2 plants, some or all of the major unit
processes have been determined to be marginal.
Improved performance is likely through the use of
a CTA; however, the plant may or may not meet
optimized performance goals without major facility
modifications. For these plants, the CTA focuses
on obtaining optimum capability of existing facili-
ties. If the CTA does not achieve the desired fin-
ished water quality, unit process deficiencies will
be clearly identified and plant administrators can
be confident in pursuing the indicated facility modi-
fications.
Figure 5-1. CTA results showing finished water quality improvements.
67
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For Type 3 plants, major unit processes have been
determined to be inadequate to meet performance
objectives. For these facilities, major construction
is indicated and a comprehensive engineering
study that focuses on alternatives to address the
indicated construction needs is warranted. The
study should also look at long term water needs,
raw water source or treatment alternatives, and
financing mechanisms.
If an existing Type 3 plant has performance prob-
lems with the potential to cause serious public
health risk, officials may want to try to address any
identified limitations, in addition to the design
factors, to improve plant performance. In these
cases, activities similar to a CTA could be imple-
mented to obtain the best performance possible
with the existing facilities, realizing that optimum
performance would not be achieved. Additionally,
administrative actions such as a boil order or water
restrictions may have to be initiated by regulators
until improvements and/or construction can be
completed for Type 3 facilities.
5.2 Conducting CTAs
5.2.1 Overview
The CTA was developed as a methodology to
address the unique combination of factors that limit
an individual facility's performance through use of
a consistent format that could be applied at
multiple utilities. This foundation for the CTA
necessarily required a flexible approach. Concepts
that define the general CTA approach are further
discussed.
Implementation of a CTA is guided by an unbiased
third party who is in a position to pursue correction
of factors in all areas such as addressing politically
sensitive administrative or operational limitations.
This person, called the CTA facilitator, initiates and
supports all of the CTA activities. The CTA
facilitator uses a priority setting model as a guide
to address the unique combination of factors that
have been identified in a CPE. Based on the
priorities indicated by this model, a systematic long
term approach is used to transfer priority setting
and problem solving skills to utility personnel. The
priority setting model is illustrated graphically in
Figure 5-2.
The first step in implementation of a CTA is estab-
lishing the optimized performance goals that will be
the objectives to achieve during the conduct of the
CTA. Since these goals exceed regulated
requirements, the plant administration has to
embrace achieving this level of performance from a
public health perspective. For example, adminis-
trators must be aware that even momentary
excursions in water quality must be avoided to
prevent Giardia and Cryptosporidium or other
pathogenic organisms from passing through the
treatment plant and into the distribution system.
To this end, all unit processes must be performing
at high levels on a continuous basis, thus providing
a "multiple barrier" to passage of pathogenic
organisms through the treatment plant. Ultimately,
administrators must adopt the concept of optimized
performance goals and be willing to emphasize the
importance of achieving these goals within the
framework of the CTA.
Figure 5-2. CTA priority setting model.
Optimized Performance Goals
Operation (Process Control)
Capable Rant
Administrative
Design
Maintenance
When the performance objectives are established,
the focus turns to operation (i.e., process control)
activities. Implementing process control is the key
to achieving optimized performance goals with a
capable facility. Administration, design and main-
tenance are necessary to support a capable plant.
Any limitations in these areas hinder the success
of the process control efforts. For example, if fil-
tered water turbidity cannot be consistently main-
tained at optimized levels because operating staff
is not at the plant to make chemical feed adjust-
ments in response to changing raw water quality,
then improved performance will require more staff
coverage. In this case, identified limitations in
making chemical feed adjustments established the
priority for improving staff coverage (i.e., an
administrative policy). Additional staff coverage
would alleviate the identified deficiency (i.e., sup-
port a capable plant) and allow process adjust-
ments to be made so that progress toward the
68
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optimized performance goals could be continued.
In this manner, factors can be prioritized and
addressed, ensuring efficient pursuit of the opti-
mized performance goals.
The results of the CPE (Chapter 4) provide the ini-
tial prioritized list of performance limiting factors
impacting an individual facility. The CTA facilitator
utilizes these factors, coupled with the priority
setting model, to establish the direction for the
CTA. It is important to note that a CTA is a
dynamic process, and the facilitator will have to
constantly readjust priorities as the events unfold.
The model can be used repetitively to assist in the
prioritization of CTA activities.
A systematic long term process is used to transfer
priority setting and problem solving skills to the
utility personnel during a CTA. Typically, 6 to 18
months are required to implement a CTA. This
long time period is necessary for several reasons:
• Time necessary to identify and develop a
local champion or champions. Since the
CTA facilitator is off-site, one or more
personnel that can implement the CTA
activities need to be identified. These persons
are called champions since they are the focal
point for CTA implementation. They are
designated as the person at the plant
responsible to understand the implementation
of the CTA and to assist the plant staff with
CTA activities on a day-to-day basis. This
person is also the key contact for communica-
tions with the CTA facilitator and the local
personnel. The champion is also the focal
point for the transfer of priority setting and
problem solving skills. The champion will
ultimately be responsible for transfer of these
skills to the other utility personnel. This transfer
is essential to ensure the continuity of water
quality improvements after the facilitator is
gone. Ideally, the champion would be the
superintendent or lead operator.
• Greater effectiveness of repetitive training
techniques. Operator and administrator train-
ing should be conducted under a variety of
actual operating conditions (e.g., seasonal
water quality or demand changes). This
approach allows development of observation,
interpretation, and implementation skills nec-
essary to maintain desired finished water
quality during periods of variable raw water
quality.
• Time required to make minor facility
modifications. For changes requiring finan-
cial expenditures, a multiple step approach is
typically required to gain administrative (e.g.,
City Council) approval. First, the need for
minor modifications to support a capable
facility must be demonstrated. Then, council/
administrators must be shown the need and
ultimately convinced to approve the funds
necessary for the modifications. This process
results in several months before the identified
modification is implemented and operational.
• Time required to make administrative
changes. Administrative factors can prolong
CTA efforts. For example, if the utility rate
structure is inadequate to support plant
performance, extensive time can be spent
facilitating the required changes in the rate
structure. Communication barriers between
"downtown" and the plant or among staff
members may have to be addressed before
progress can be made on improved
performance. If the staff is not capable,
changes in personnel may be required for the
CTA to be successful. The personnel policies
and union contracts under which the utility
must operate may dictate the length of time
these types of changes could take.
• Time required for identification and
elimination of any additional performance
limiting factors that may be found during
the CCP. It is important to note that additional
performance limiting factors, not identified
during the short duration of the CPE, often
become apparent during conduct of the CTA.
These additional limitations must also be
removed in order to achieve the desired level
of performance.
5.2.2 Implementation
Experience has shown that no single approach to
implementing a CTA can address the unique com-
bination of factors at every water treatment plant.
However, a systematic approach has been devel-
oped and specific tools have been used to
increase the effectiveness of CTA activities. The
approach requires involvement of key personnel
and establishes the framework within which the
CTA activities are conducted. Key personnel for
the implementation of the CTA are the CTA
facilitator and
69
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the utility champions. The framework for con-
ducting the activities includes site visits, commu-
nication events, and data and records review con-
ducted over a sufficient period of time (e.g., 6 to 18
months).
The tools utilized for conducting CTAs have been
developed to enhance the transfer of capability to
utility administrators and staff. Actual implemen-
tation of each CTA is site-specific, and the combi-
nation of tools used is at the discretion of the CTA
facilitator. Additional approaches to addressing
performance limiting factors exist, and a creative
facilitator may choose other options.
Implementation of a successful CTA requires that
the CTA facilitator constantly adjust the priorities
and implementation techniques to match the facility
and personnel capabilities at the unique site. The
bottom line is that optimized performance goals,
that can be graphically depicted, need to be
achieved as a result of the CTA efforts (see Figure
5-1). Components of CTA implementation are
further described.
5.2.2.1 Approach
CTA Facilitator
The CTA facilitator is a key person in the imple-
mentation of CTA activities and must possess a
variety of skills due to the dynamic nature of the
process. Desired skills include a comprehensive
understanding of water treatment unit processes
and operations and strong capabilities in leader-
ship, personnel motivation, priority setting, and
problem solving.
Comprehensive understanding of water treatment
unit processes and operations is necessary
because of the broad range of unit processes
equipment and chemicals utilized. For example,
numerous sedimentation devices exist such as
spiral flow, reactor type, lamella plate, tube set-
tlers, pulsators and solids contact units. Addition-
ally, multiple possibilities exist in terms of types,
combinations and dosages of coagulant, flocculant
and filter aid chemicals.
Operations capability is necessary to understand
the continually changing and sometimes conflicting
requirements associated with water treatment.
Optimization for particulate removal ultimately has
to be coordinated with control of other regulated
parameters such as disinfection by-products or
lead and copper. In addition, those responsible for
implementing a CTA must have sufficient process
control capability to establish an appropriate
approach that is compatible with the personnel
capabilities available at the utility.
A CTA facilitator must often address improved
operation, improved maintenance, and minor
design modifications with personnel already
responsible for these water treatment functions. A
"worst case situation" is one in which the plant staff
is trying to prove that "the facilitator can't make it
work either." The CTA facilitator must be able to
create an environment to maintain communications
and enthusiasm and to allow all parties involved to
focus on the common goal of achieving optimized
plant performance. Ultimately, the CTA facilitator
must transfer priority setting and problem solving
skills to the utility staff. The objective here is to
leave the utility with the necessary skills after the
facilitator leaves so that the performance goals can
be met long term. To accomplish this transfer, the
facilitator must create situations for local personnel
to "self discover" solutions to ongoing optimization
challenges so that they have the knowledge and
confidence to make all necessary changes. In
almost all cases the facilitator must avoid
assuming the role of troubleshooter or the person
with all of the answers. Each situation has to be
evaluated for its learning potential for the staff.
A CTA facilitator must be able to conduct training
in both formal and on-the-job situations. Training
capabilities must also be developed so they are
effective with both operating as well as adminis-
trative personnel. When addressing process con-
trol limitations, training must be geared to the
specific capabilities of the process control decision
makers. Some may be inexperienced; others may
have considerable experience and credentials.
"Administrative" training is often a matter of clearly
providing information to justify or support CTA
objectives or activities. Although many
administrators are competent, some may not know
what to expect from their facilities or what their
facilities require in terms of staffing, minor modifi-
cations, or specific funding needs.
CTA facilitators can be consultants, state and fed-
eral regulatory personnel, or utility employees. For
consultants, the emphasis of optimizing the
"existing facility" without major construction must
be maintained. A substantial construction cost can
be incurred if an inexperienced facilitator is not
able to bring a capable water treatment plant
70
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to the desired level of performance. For example,
a consultant, involved primarily with facility design,
may not have the operational experience to utilize
the capability of existing unit processes to their
fullest extent and may be biased toward designing
and constructing new processes.
If utility personnel try to fill the role as CTA facili-
tator, they should recognize that some inherent
problems may exist. The individuals implementing
the CTA, for example, often find it difficult to pro-
vide an unbiased assessment of the area in which
they normally work (i.e., operations personnel tend
to look at design and administration as problem
areas; administrators typically feel the operations
personnel should be able to do better with existing
resources). These biases should be recognized,
and they must be continually challenged by utility
personnel who assume the role of CTA facilitator.
Individuals who routinely work with water utilities to
improve water treatment plant performance will
likely be the best qualified CTA facilitators. These
people are typically engineers or operators who
have gained experience in correcting deficiencies
at plants of various types and sizes. CTA facilita-
tors that have experience in a variety of plants
have a definite advantage in their ability to recog-
nize and correct true causes of limited perform-
ance.
On-Site CTA Champion
In addition to the capabilities of the CTA facilitator,
it is necessary to have one or several utility per-
sonnel who "champion" the objectives and
implementation of the CTA process. The cham-
pion is the person who assumes the day-to-day
responsibilities of pursuing the implementation of
the established priorities. This person is also
responsible for the transfer of problem solving
skills learned from the CTA facilitator to the rest of
the staff.
Identification of the champion is a key step in the
success of the CTA. Ideally, the superintendent or
lead operator is the person that would fill the
champion role. However, many times these indi-
viduals may be part of the limitation to achieving
optimized performance because they tend to stick
to the old ways of conducting business. New
operators or laboratory personnel often offer the
greatest potential for the role as champion. To
resolve some of the issues with the selection of
these "junior" personnel, a champion team con-
sisting of the selected personnel and the personnel
that normally would assume the role (e.g., the
superintendent) can be selected.
Ideally the role of the champion is formally identi-
fied during the CTA activities. In other cases,
however, it may be necessary to use an informal
approach where the champion is only recognized
by the CTA facilitator. For example, in some cases
the champion may not be the typical person, based
on the "chain of command." In these cases the
use of a junior person to assist the supervisor or
superintendent in the actual implementation may
be the only option available to ensure progress on
CTA activities. This is a delicate situation for the
facilitator, and extra effort is required to maintain
open communications and acceptance for project
activities. In any event, the closer the
characteristics of the champion are to those out-
lined for the CTA facilitator, the easier the imple-
mentation of the CTA will be.
CTA Framework
A consistent framework has been developed to
support the implementation of a CTA. The
framework consists of on-site involvement (e.g.,
site visits) interspersed with off-site activities (e.g.,
communication events such as phone/fax/ e-mail
and data and guidelines review). A graphical
illustration of the CTA framework is shown in
Figure 5-3.
• Site visits are used by the facilitator to verify
or clarify plant status, establish optimization
performance goals, initiate major process con-
trol changes, test completed facility modifica-
tions, provide on-site plant or administrative
training, and report progress to administrators
and utility staff. Dates for site visits cannot be
established at specific intervals and must be
scheduled based on plant status (e.g., process
upsets), training requirements, communica-
tions challenges, etc. As shown in Figure 5-3,
site visits and communication events typically
taper off as the CTA progresses. This is in line
with the transfer of skills to the plant staff that
occurs throughout the CTA. The number of
site visits required by a CTA facilitator is
dependent on plant size and on the specific
performance limiting factors. For example,
some administrative (e.g., staffing and rate
changes) and minor design modifications could
significantly increase the number of site visits
required to complete a CTA. Typically, the
71
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Figure 5-3. Schematic of CTA framework.
12 3 4 5 678 9 10 11 12
Site Visits
Communication:
Data and
Correspondence
Review
Reporting
Activities
'
* *
o
* *
* *
]
* *
o
* *
* *
D
* *
o
* *
* *
* *
* *
• o
o
Months of Involvement
initial site visit is conducted over three to four
days and intermediate site visits are conducted
over two to three days. CTA accomplishments
and proposed future activities are presented to
plant and administrative personnel at an exit
meeting at the conclusion of each site visit.
• Communication events such as telephone
calls, faxes and e-mail are used to routinely
assess CTA progress. Communication activi-
ties are normally conducted with the on-site
CTA champion. Routine contact is used to
train and encourage plant personnel to pursue
data collection and interpretation, encourage
progress on prioritized activities, and provide
feedback on special studies and guideline
development. The CTA facilitator should
always summarize important points, describe
decisions that have been reached, and identify
actions to be taken. Further, both the CTA
facilitator and plant personnel should maintain
written phone logs. It is noted that communi-
cation events have limited ability to address all
identified factors. As such, the CTA facilitator
should always monitor the progress being
accomplished in the effectiveness of the com-
munication events to assess the need for a site
visit.
• Data and correspondence review are
activities where the CTA facilitator reviews the
information provided routinely by the utility. A
format for submittal of weekly performance
data is established during the initial site visit.
This information is provided in hard copy or
electronically by the utility. Results of special
studies or draft operational guidelines are also
submitted to the CTA facilitator for review.
Review and feedback by the CTA facilitator are
key to demonstrate the importance of efforts
by the utility personnel. Findings from data
and records review are related to the staff by
communications events. The routine feedback
enhances the data development and
interpretation skills of the utility staff.
Reporting activities are used to document
progress and to establish future direction.
Short letter reports are typically prepared at
the conclusion of each site visit. These reports
can be used to keep interested third parties
(e.g., regulatory personnel) informed and to
maintain a record of CTA progress and events.
They also provide the basis for the final CTA
report. Short reports or summaries can also
be developed to justify minor facility upgrades
or changes in plant coverage or staffing. A
final CTA report is typically prepared for
delivery at the last site visit. The report should
be brief (e.g., eight to twelve pages are
typically sufficient for the text of the report).
Graphs documenting the improvement in plant
performance should be presented. If other
benefits were achieved these should also be
documented. Typical contents are:
• Introduction:
* Reasons for conducting the CTA.
• CPE Results:
* Briefly summarize pertinent informa-
tion from the CPE report.
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CTA Significant Events:
* Chronological summary of activities
conducted.
* Include special study results.
• CTA Results:
* Graph of plant performance plus
other benefits.
• Conclusions:
* Efforts required to maintain improved
performance.
• Appendices:
* Compilation of site specific
guidelines developed by the plant
staff.
5.2.2.2 Tools
Contingency Plans
Contingency plans should be prepared for facilities
producing finished water quality that is not meeting
current regulated requirements and for possible
instances when finished water degrades during
implementation of changes during the CTA. The
contingency plan should include actions such as
reducing plant flow rate to improve performance,
shutting down the plant, initiating a voluntary public
notification, and initiating a voluntary boil order. If
plant finished water exceeds a regulated maximum
contaminant level (MCL), the State regulatory
agency should be immediately informed, and
public notification procedures mandated by the
Public Notification Regulation Rule (1) should be
followed. To minimize the chance of producing
unacceptable finished water while conducting a
CTA, all experimentation with chemical doses and
different coagulant products should be done on a
bench scale (e.g., jar test) before implementing
changes on a full scale basis. Full scale experi-
mentation can be done on an isolated treatment
train or during low demand conditions that would
allow "dumping" of improperly treated water.
Action Plans
Action plans can be utilized to ensure progressive
implementation of performance improvement
activities. The action plan summarizes items to be
completed, including the name of the person that
is assigned a particular task and the projected due
date. The plan is normally developed during the
CTA site visits and distributed by the CTA facilita-
tor. The plan should identify tasks that are clear to
the person responsible and within their area of
control. The person should have been involved in
the development of the action item and should
have agreed to the assignment and the due date.
The action plan is provided to administrators and
plant personnel after site visits or communication
events. Communication events are used to
encourage and monitor progress on the assigned
action items. An example format for an "Action"
plan is shown in Figure 5-4.
Figure 5-4. Example action plan.
Item
1
2
3
Action
Develop calibration curve for
polymer feed pump.
Draft special study procedure
to evaluate use of a
flocculant aid to improve
sedimentation basin
performance.
Process control:
a. Develop daily data
collection sheet.
b. Develop routine
sampling program.
c. Draft guideline for jar
testing.
Person
Responsibl
e
Jon
Bob
Larry
Eric
Rick
Date
Due
4/4
5/1
4/17
4/24
4/28
Special Studies
Special studies can be used to evaluate and opti-
mize unit processes, to modify plant process con-
trol activities, or to justify administrative or design
changes necessary to improve plant performance.
They are a structured, systematic approach for
assessing and documenting plant optimization
activities. The format for development of a special
study is shown in Figure 5-5. The major compo-
nents include the special study topic, hypothesis,
approach, duration of the study, expected results,
documentation/conclusions, and implementation
plan. The hypothesis should have a focused
scope and should clearly define the objective of
the special study. The approach should provide
detailed information on how the study is to be
conducted including: when and where samples
are to be collected, what analyses are to be con-
ducted, and which specific equipment or processes
will be used. The approach should be
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developed in conjunction with the plant staff to
obtain staff commitment and to address any chal-
lenges to implementation that may exist prior to
initiating the study. Expected results ensure that
measures of success or failure are discussed prior
to implementation. It is important that the study
conclusions be documented. Ideally, data should
be developed using graphs, figures and tables.
This helps to clarify the findings for presentation to
interested parties (e.g., plant staff, administrators,
regulators). Special study findings serve as a
basis for continuing or initiating a change in plant
operation, design, maintenance or administration.
An implementation plan in conjunction with con-
clusions identifies the procedural changes and
support required to utilize special study results. If
all of the steps are followed, the special study
approach ensures involvement by the plant staff,
serves as a basis for ongoing training, and
increases confidence in plant capabilities. An
example special study is presented in Appendix I.
Operational Guidelines
Operational guidelines can be used to formalize
activities that are essential to ensure consistent
plant performance. Examples of guidelines that
can be developed include: jar testing, polymer
dilution preparation, polymer and coagulant feed
calculations, filter backwashing, chemical feeder
calibration, sampling locations and data recording.
The CTA facilitator may provide examples, but
guidelines should be developed by the plant staff.
Through staff participation, operator training is
enhanced and operator familiarity with equipment
manuals is achieved. Additionally, communication
among operators and shifts is encouraged in the
preparation of guidelines. The guidelines should be
prepared using word processing software and
should be compiled in a three-ring binder so that
they can be easily modified as optimization
practices are enhanced. An example guideline is
presented in Appendix J.
Data Collection and Interpretation
Data collection and interpretation activities are
used to formalize the recording of results of proc-
ess control testing that is initiated. Typically, a
daily sheet is used to record operational data such
as lab test results, flow data, and chemical use.
These data are transferred to monthly sheets that
are used to report necessary information to the
regulatory agency and to serve as a historic record
for plant operation. Examples of daily and monthly
process control sheets are presented in Appendix
K. Graphs or trend charts can be used to enhance
the interpretation of process monitoring results.
The data developed can be plotted over long
periods to show seasonal trends and changes in
water demand or over shorter periods to show
instantaneous performance. Examples of data
development over a several month period are
shown in Figure 5-1. A short term trend chart
showing raw, settled and filtered water turbidities
over a one-day period is depicted in Figure 5-6.
During this period no change in coagulant dose
was initiated, despite the change in raw water tur-
bidity. As a result, settled water and finished water
quality deteriorated several hours after the raw
water turbidity increased. Without the use of a
trend chart this correlation would be difficult to
observe.
Figure 5-5. Special study format.
Special Study Topic: Identify name of the special study and
briefly describe why the study is being conducted (i.e., one to
two sentences).
Hypothesis:
Focused scope. Try to show definite cause/effect
relationship.
Approach:
Detailed information on conducting study. Involve plant
staff in development.
Duration of Study:
Important to define limits of the study since "extra work" is
typically required.
Expected Results:
Projection of results focuses attention on interim
measurements and defines success or limitations of
effort.
Conclusions:
Documented impact of study allows the effort to be
used as a training tool for all interested parties. Allows
credit to be given for trying an approach.
Implementation:
Identifies changes or justifies current operating
procedures. Formalizes demonstrated
mechanisms to optimize plant performance.
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Figure 5-6. Short term trend chart showing relationship of raw, settled and filtered water turbidities.
12 16
Time (hrs)
Priority Setting Tools
The CTA facilitator uses the priority setting model
(i.e., Figure 5-2) to aid in establishing priorities for
implementing a CTA. Awareness of this model can
be provided to utility personnel to aid them in
setting routine priorities for utility activities.
Another method that is useful for utility personnel
to aid in developing their priority setting skills is the
nominal group process. This mechanism uses a
facilitator (e.g., the CTA facilitator initially and the
utility champion or other staff as the CTA pro-
gresses) to solicit input from plant personnel during
a formal meeting by asking an open-ended
question concerning optimization activities. A
question such as "What concerns, activities, or
modifications, can we address to continue to pur-
sue optimization performance goals at our utility?"
can be asked to start the discussion. Participants
are given time to develop ideas and the facilitator
then solicits responses one at a time from each
person in a round-robin fashion. After all ideas are
documented (e.g., on a flip chart or chalk board)
the ideas are discussed for clarity and overlap.
The participants then priority vote on the issues
(e.g., vote for the top five issues, allowing five
points for the top issue, four for the second issue,
etc.). Topics are prioritized by the number of votes
that they get, and ties are differentiated by the
number of points. Based on the combined results
of all of the voting, the highest priority issues are
identified. These issues are discussed,
and action steps are identified and placed on an
action list. Example results from a priority setting
activity are shown in Figure 5-7.
The nominal group process encourages involve-
ment of all parties and provides significant training
during the open discussion of prioritized topics.
The CTA facilitator can interrupt the discussions if
technical inaccuracies exist; but, for the most part,
the facilitator should try to maintain a neutral role.
It is important to note, however, that the nominal
group process is only effective after the CTA is
underway and the initial key priorities have been
implemented. After the initial efforts, the utility
personnel are more aware of the purpose of the
CTA and better equipped to contribute meaningful
suggestions concerning optimization activities. It is
up to the CTA facilitator to ascertain when utility
personnel are able to effectively utilize this tool.
Topic Development Sheets
Topic development sheets (see Figure 5-8) can be
used to develop problem solving skills in utility
personnel. In utilizing the topic development
sheet, the issue should be clearly defined. An
ideal starting point would be a prioritized issue
developed from the nominal group process. The
CTA facilitator, initially, and utility champion, as the
CTA progresses, would lead the discussion on
using the topic development sheet format.
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Figure 5-7. Example priority setting results
from CTA site visit activity.
Question: What concerns, activities or modifications can
be addressed to continue to pursue optimization goals at
your utility?
List of Responses:
1 . Post backwash turbidity spikes
2. Retention of trained staff
3. End point for CTA project
4. Eliminate washwater return
5. Drought impact (color, taste and odor, rationing)
6. Flow indicators on chemical feeders
7. Reconsider particle counter capability
8. Recognition for utility staff by regulatory
9. Recent budget constraints
10. Public relations on optimization efforts
1 1 . Maintaining optimization approach
Prioritized Topics:
agency
Rank Item Votes
1 Flow indicators on chemical
feeders 6
2 Post backwash turbidity spikes
3 Retention of trained staff
4 End point for CTA project
5 Maintaining optimization
approach
6 Recognition for utility staff
6
5
4
3
3
Points
24
23
17
7
10
5
Figure 5-8, provides a section listing obstacles.
Typically, it is easier for participants to discuss the
reasons why an idea will not work. After the
obstacles are presented, the facilitator should
focus the group on possible solutions. The facilita-
tor should have the group pursue a solution for
each obstacle. While the discussion occurs, the
benefits for making the change can be listed in the
benefits section of the sheet. The solutions should
be converted to action steps and documented on
the sheet. The action steps should be
subsequently transferred to the optimization action
plan.
Use of the topic development sheet is effective in
enhancing the problem solving skills of utility per-
sonnel. The tool allows obstacles to be presented
but requires that solutions and action steps also be
developed. Use of the topic development sheet
and the associated activity also enhances commu-
nication skills among the staff.
Figure 5-8. Example topic development sheet.
TOPIC DEVELOPMENT SHEET
Topic/Issue:
Benefits:
Possible Obstacles:
Action Steps:*
Possible Solutions:
Transfer to an Action Plan.
Internal Support
The CTA facilitator must ensure that internal
communication to maintain support for the CTA
occurs at all levels of the organization. This is
typically done through routine meetings (e.g.,
during site visits) or with summary letters and
communication events. Internal support is key to
develop during the conduct of a CTA and can be
useful in accomplishing desired changes. Typi-
cally, a CTA introduces a "new way of doing busi-
ness" to the water utility. This new approach is not
always embraced by the existing personnel.
Support from the personnel department or the
administrative staff can be utilized in establishing
the "acceptable behavior" required of the utility
staff to support the CTA objectives. For example,
the CTA facilitator and utility champion may have
clearly defined a new sampling procedure to
support the optimization efforts. If a staff member
will not comply with the approach or continues to
resist the change, administrative pressure can be
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solicited if internal support for project activities has
been maintained.
What-lf Scenarios
Many facilities have very stable raw water sources
and as such are not challenged with variations that
test the capability of facilities and personnel to
respond and maintain optimized performance
goals. In some facilities this is true even if the
duration of the CTA is over a period of a year or
greater. In these facilities, factors relating to reli-
ability and complacency often need to be
addressed. The CTA facilitator can create "what-if
scenarios" for the utility personnel to address.
Development of these scenarios may be the only
opportunity during the conduct of the CTA to pre-
pare local personnel for challenging situations.
"What-if scenarios" should only be utilized after the
plant staff have gained experience and confidence
from CTA training activities.
5.2.2.3 Correcting Performance Limiting
Factors
A major emphasis of a CTA is addressing factors
identified as limiting performance in the CPE phase
as well as additional limiting factors that may be
identified during the CTA. Correcting these factors
provides a capable plant and allows the opera-
tional staff to utilize improved process control
(operation) to move the plant to achievement of
optimized performance goals. Approaches that
can be implemented to enhance efforts at
addressing factors in the areas of design, admini-
stration, maintenance and operation are discussed
in the following sections.
may support the need for major construction; and
once this has been established, utility staff should
pursue this direction similar to a Type 3 facility.
The performance of Type 1 and Type 2 plants can
often be improved by making minor modifications
to the plant. A minor modification is defined as a
modification that can be completed by the plant
staff without development of extensive contract
documents. Examples of minor modifications
include: adding a chemical feeder, developing
additional chemical feed points, or installing baffles
in a sedimentation basin.
A conceptual approach to improving design per-
formance limiting factors is based on the premise
that if each proposed design modification can be
related to an increased capability to achieve opti-
mized performance goals, then the modification will
be supported. For example, if a chemical feeder is
necessary to provide a feed rate in a lower range
than current equipment can provide, then the
design modifications are needed to provide a
capable plant so that desired process control
objectives can be met (see Figure 5-2). The need
for this minor modification can be easily
documented and justified to the administration.
Support for the modification would be expected.
The degree of documentation and justification for
minor modifications usually varies with the associ-
ated costs and specific plant circumstances. For
example, little justification may be required to add
a sampling tap to a filter effluent line. However,
justification for adding baffles to a flocculation
basin would require more supporting information.
Extensive justification may be required for a facility
where water rates are high and have recently been
raised, yet there is no money available for an iden-
tified modification.
Design Performance Limiting Factors
The performance of Type 3 plants is limited by
design factors that require major modifications to
correct. Major modifications require the develop-
ment of contract documents (i.e., drawings and
specifications) and hiring a construction company
to complete the improvements. Examples include
the addition of a sedimentation basin or expansion
of a clear well. Major modifications can sometimes
be avoided by operating the plant at a lower flow
rate for longer periods of time; thereby reducing
the unit process hydraulic loading rate to a range
that allows adequate performance to be achieved.
CTA experience with Type 2 facilities
The CTA facilitator should assist in developing the
plant staff skills to formally document the need for
minor modifications. This documentation is valu-
able in terms of presenting a request to supervi-
sory personnel and in providing a basis for the
plant staff to continue such requests after the CTA
has been completed. For many requests the spe-
cial study format can be used as the approach for
documenting the change (see Special Studies sec-
tion previously discussed in this chapter). For
modifications with a larger cost, the following items
may have to be added to the special study format.
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• Purpose and benefit of the proposed change
(i.e., how does the change relate to the devel-
opment of a capable plant so that process con-
trol can be used to achieve performance
goals?).
• Description of the proposed change and an
associated cost estimate.
Many state regulatory agencies require that modi-
fications, other than repair and maintenance items,
be submitted for their approval. Improvements
requiring state approval may consist of items such
as changing types of chemicals added to the water
(e.g., substituting iron salts for aluminum salts),
adding another chemical feeder (e.g., filter aid
polymer feeder), or modifying filter media. If there
is any doubt as to whether approval is needed, the
facilitator should recommend submitting the pro-
posed modification to the regulatory agency for
approval. Typically, the same documentation that
would be prepared to obtain administrative
approval can be used for the submittal to the
regulatory agency.
Once the proposed modification has been
approved by plant administrators and the state
regulatory agency, the CTA facilitator should serve
as a technical reference throughout the implemen-
tation of the modification. Following completion of
a modification, the CTA facilitator should ensure
that a formal presentation of the improved plant
capability is presented to the administration. This
feedback is necessary to build rapport with the
plant administrators and to ensure support for
future requests. The intent of the presentation
should be to identify the benefits in performance
obtained from the expended resources.
Maintenance Performance Limiting Factors
Maintenance can be improved in nearly all plants,
but it is a significant performance limiting factor in
only a small percentage of plants (2,3,4). The first
step in addressing maintenance factors is to
document any undesirable results of the current
maintenance effort. If plant performance is
degraded as a result of maintenance-related
equipment breakdowns, the problem is easily
documented. Likewise, if extensive emergency
maintenance events are experienced, a need for
improved preventive maintenance is easily recog-
nized. Ideally, maintenance factors should have
been previously identified and prioritized during a
CPE. However, most plants do not have such
obvious evidence directly correlating poor mainte-
nance practices with poor performance; therefore,
maintenance factors often do not become apparent
until the conduct of a CTA. For example, in many
cases CTA activities utilize equipment and proc-
esses more extensively than they have been used
in the past, such as running a facility for longer
periods of time. The expanded use emphasizes
any maintenance limitations that may exist.
Implementing a basic preventive maintenance pro-
gram will generally improve maintenance practices
to an acceptable level in many plants. A sug-
gested four-step procedure for developing a main-
tenance record keeping system is to: 1) list all
equipment, 2) gather manufacturers' literature on
all equipment, 3) complete equipment information
summary sheets for all equipment, and 4) develop
and implement time-based preventive maintenance
activities. Equipment lists can be developed by
touring the plant and by reviewing available
equipment manuals. As new equipment is pur-
chased it can be added to the list. Existing manu-
facturers' literature should be inventoried to identify
missing but needed materials. Maintenance
literature can be obtained from the manufacturer or
from local equipment representatives.
Equipment maintenance sheets that summarize
recommended maintenance activities and sched-
ules are then developed for each piece of equip-
ment. Once these sheets are completed, a com-
prehensive review of the information allows a time-
based schedule to be developed. This schedule
typically includes daily, weekly, monthly, quarterly,
semiannual, and annual activities. Forms to
remind the staff to complete the tasks at the
desired schedule (e.g., check-off lists) can be
developed.
The above system for developing a maintenance
record keeping system provides a reliable founda-
tion for implementing a preventive maintenance
program. However, there are many other good
maintenance systems, including computer-based
systems. The important concept to remember is
that adequate maintenance is essential to reliably
achieve optimized performance goals.
Administrative Performance Limiting Factors
Administrators who are unfamiliar with plant needs,
and thus implement policies that conflict with plant
performance, are a commonly identified factor. For
example, such items as implementing
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minor modifications, purchasing testing equipment,
or expanding operator coverage may be rec-
ognized by plant operating personnel as needed
performance improvement steps, but changes
cannot be pursued due to lack of support by non-
technical administrators. Administrative support
and understanding are essential to the successful
implementation of a CTA. The following tech-
niques have proven useful in addressing adminis-
trative factors limiting performance:
• Focus administrators on their responsibility to
provide a "product" that not only meets but
exceeds regulatory requirements on a continu-
ous basis to maximize public health protection.
Often, administrators are reluctant to pursue
actions aimed at improving plant performance
because of a lack of understanding of both the
health implications associated with operating a
water treatment plant and of their responsibili-
ties in producing a safe finished water. The
CTA facilitator must inform and train adminis-
trators about their public health responsibilities
and the associated objectives of achieving
optimized performance goals from their facili-
ties. As an endpoint, administrators should be
convinced to adopt the optimum performance
goals described in Chapter 2. Administrators
should also be encouraged to emphasize to
the operating staff the importance of achieving
these goals.
• Build a rapport with administrators such that
candid discussions concerning physical and
personnel resources can take place (e.g., see
Internal Support section previously discussed
in this chapter).
• Involve plant administrators from the start.
Site visits should include time with key
administrators to explain the CTA activities. If
possible, conduct a plant tour with the admin-
istrators to increase their understanding of
plant processes and problems. Share
performance results on a routine basis.
• Listen carefully to the concerns of administra-
tors so that they can be addressed. Some of
their concerns or ideas may be unrelated to
the technical issues at the plant, but are very
important in maintaining internal support for
ongoing CTA activities.
• Use technical data based on process needs to
convince administrators to take appropriate
actions.
• Solicit support for involvement of plant staff in
the budgeting process. Budget involvement
has been effective in encouraging more effec-
tive communication, in motivating plant staff,
and in improving administrative awareness and
understanding. This activity also helps to
ensure continued success after the CTA facili-
tator is gone.
• Encourage development of a "self-sustaining
utility" attitude. This requires financial planning
for modification and replacement of plant
equipment and structures, which encourages
communication between administrators and
plant staff concerning the need to accomplish
both short and long term planning. It also
requires development of a fair and equitable
rate structure that requires each water user
(i.e., domestic, commercial, and industrial) to
pay their fair share. The revenues generated
should be sufficient to support ongoing oper-
ating costs as well as short term modification
and long term replacement costs. The CTA
facilitator may choose to encourage the utility
to gain professional help in this area,
depending on the circumstances. Information
is also available from other sources (5,6,7).
Operational Performance Limiting Factors
Obtaining optimized performance goals is ulti-
mately accomplished by implementing formal
process control procedures, tailored for the par-
ticular personnel and plant. Additionally, the proc-
ess control skills must be transferred to the local
staff for the CTA to result in the plant having the
long term capability to maintain the desired per-
formance goals.
Initial efforts should be directed toward the training
of the key process control decision-makers (i.e.,
on-site CTA champion). In most plants with flows
less than 0.5 MGD, one person typically makes
and implements all major process control
decisions. In these cases, on-the-job training is
most effective in developing skills and transferring
capability. If possible, in plants of this size a "back-
up" person should also be trained. This person
may be an administrator or board member at a
very small utility. As the number of operators to be
trained increases with plant size, the need for
classroom training also increases. However, a
significant aspect of the CTA's effectiveness is the
"hands-on" training approach; therefore, any
classroom training must be supported by actual
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"hands-on" applicability and use. The only excep-
tion to this emphasis is in addressing complacency
issues with "what if scenarios" (see What If Sce-
narios section previously discussed in this chap-
ter).
A generic discussion of process control for water
treatment facilities is presented. The CTA facilita-
tor must identify deficiencies in any of the following
areas and implement activities to address these
limitations, recognizing existing facility and per-
sonnel capabilities.
Process Sampling and Testing:
Successful process control of a water treatment
plant involves producing a consistent, high quality
treated water despite the variability of the raw
water source. To accomplish this goal, it is nec-
essary that the performance of each unit process
be optimized. This is important because a break-
down in any one unit process places a greater
burden on the remaining processes and increases
the chance of viable pathogenic organisms reach-
ing the distribution system and consumers' taps.
By optimizing each unit process, the benefit of
providing multiple barriers prior to the consumer is
realized.
To optimize each unit process, information must be
routinely obtained and recorded on raw water
quality and on the performance of the various unit
processes in the plant so that appropriate controls
can be exercised to maintain consistent treated
water quality. The term "routinely" is stressed
because it is necessary to have the plant achieve
performance objectives at all times when it is in
operation. To allow information to be gathered and
for process control adjustments to be made
whenever water quality conditions dictate, staff
should be available during all periods of operation.
If staffing is not available, continuous water quality
monitoring with alarms and shutdown capability
should exist.
The gathering of information in an organized and
structured format involves development of a proc-
ess control sampling and testing schedule. A basic
process control sampling and testing schedule for
a conventional plant is shown in Figure 5-9.
Turbidity is the primary test because it provides a
quick and easily conducted measurement to
determine particulate levels and particle removal
effectiveness of individual plant unit processes.
Particle counting can be used in conjunction with
turbidity; however, most small facilities are not yet
using this technology. Raw water turbidity testing
should be conducted on a frequent basis (e.g.,
every four hours) to identify changes in quality.
During periods of rapid change, raw water turbidity
should be measured on a more frequent basis to
allow adjustment of coagulant aids. Settled water
turbidity from each basin should be measured a
minimum of every four hours to monitor the
effectiveness of the settling process and to
document that the integrity of this barrier is being
maintained. If the effectiveness of sedimentation
deteriorates (e.g., due to the unexpected failure of
an alum feeder), the monitoring allows immediate
corrective actions to be taken to minimize or lessen
the impact on downstream unit processes. Filtered
water turbidity should be measured and recorded
on a continuous basis from each filter to allow
constant monitoring of filtered water quality.
Continuous monitoring of filtered water tremen-
dously enhances the operators' capability to prop-
erly time backwashing of filters, to determine the
extent of post backwash turbidity breakthrough,
and to observe if filter control valve fluctuations are
impacting filtered water turbidity.
The process control data should be recorded on
daily sheets, and this data should be transferred to
monthly sheets to allow observation of water
quality trends. For turbidity measurement, maxi-
mum daily values are recorded since this repre-
sents the worst case potential for the passage of
particles. Appendix K includes examples of both
daily and monthly process control sheets. The
daily sheets should include space for recording
actual chemical feed rates and the conversion of
these values to a mg/L dosage so that dosage and
water quality can be correlated. This database can
then be used by the operator to better predict
chemical feed requirements during different raw
water quality events. Graphs and trend charts
greatly enhance these correlation efforts. The use
of computer spreadsheets is encouraged to sup-
port data development and the use of trend charts.
Chemical Pretreatment and Coagulant Control:
The selection and control of chemical coagulants,
flocculants and filter aids is the most important
aspect of improving water treatment plant per-
formance. Therefore, a method to evaluate differ-
ent coagulants and to control the selected coagu-
lant is a primary focus in implementing a process
control program. The special study format is
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especially effective for systematically optimizing
chemical pretreatment.
A coagulant control technique must exist or be
implemented during a CTA if optimized perform-
ance is to be achieved. Example coagulant control
techniques include: jar testing, streaming current
monitors, zeta potential, and pilot filters. Jar
testing is the most common technique and is dis-
cussed in more detail.
To successfully implement jar testing as a coagu-
lant control technique requires understanding of
stock solution preparation and conducting the test
so that it duplicates plant operating conditions as
closely as possible. A typical procedure for pre-
paring stock solutions, conducting jar tests, and
determining mixing energy settings is shown in
Appendix L. Stock solutions must be prepared for
all coagulant chemicals (e.g., metal salts and
polymers) that are going to be added to the jars.
The jar test can be set up to represent plant oper-
ating conditions by setting jar test mixing energy
inputs, mixing times, and settling detention times
similar to those found in the plant (Appendix L).
Plant mixing energy (i.e., G-values) can be deter-
mined by using worksheets presented in the
design section of Appendix F. The use of square
jars is recommended because square jars break
up the circular motion inherent in cylinders and
more accurately represent plant operating
conditions.
Chemicals should also be added to the jars to try
to duplicate plant operating conditions. For exam-
ple, if alum is added to the plant flash mix and
polymer is added to a pipeline approximately
30 seconds downstream from the flash mix, the
same sequence should be used in the jar test.
The use of syringes without needles to measure
and deliver the appropriate chemical dose to each
jar simplifies the chemical addition step (i.e., 1 cc =
1 ml). Syringes are available from pharmacies or
veterinary/farm supply stores. The jar test proce-
dure should be adjusted to more closely duplicate
the plant processes. In direct filtration plants, a
small volume (about 50 ml) of flocculated water
should be removed from the jars and passed
through filter paper. Typically, 40 micron filter
paper (e.g., Whatman #40, Schleicher and Schuell
#560) can be used to approximate filter perform-
ance. The filtered samples should be tested for
turbidity, and the sample with the lowest turbidity
represents the optimum chemical dose.
In conventional plants, the jar contents should be
allowed to settle for a period of time relative to the
surface overflow rate of the basins. The approach
for determining the sampling time for settled water
is shown in Appendix L. Allowing the water in the
jar to settle for 30 to 60 minutes and then taking a
sample for turbidity measurement has no relation-
ship to a full-scale plant and should not be done for
collecting useful jar test information. After the
correct sampling time is determined, samples
should be drawn from the sample tap located
10 cm from the top of the jar, and the turbidity of
the sample should be determined. The lowest tur-
bidity represents the best chemical dosage. If
sample taps are not available on the jars, pipettes
can be used to draw-off samples from the jars.
Excellent references are available to guide the
facilitator in implementing jar testing techniques to
obtain optimum coagulant doses (8,9,10,11).
Figure 5-9. A basic process control sampling and testing schedule.
Sample
Plant Influent
Sedimentation
Basin
Filter Effluent
Treated or Finished
Water
Sample Location
Tap by Raw Water
Turbidimeter
Top of Filter
Turbidimeter
Lab Tap
Tests
Turbidity
PH
Alkalinity
Flow Rate
Jar Test
Temperature
Turbidity
Turbidity
PH
CI2 Residual
Turbidity
Frequency
Continuous
Daily
Weekly
Continuous
As Needed
Daily
Every 2 Hours
Continuous
Daily
Continuous
Every 4 Hours
Sample By
Meter
Operator
Operator
Meter
Operator
Operator
Operator
Meter
Meter
Meter
Operator/Meter
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Once the correct chemical dose is determined, the
staff must be able to adjust the chemical feeders to
deliver the desired dosage. This requires the
ability to conduct chemical calculations and to
develop and utilize calibration curves for chemical
feeders. For example, a mg/L dose has to be con-
verted to a feed rate (e.g., Ib/day or mL/min) in
order to correctly adjust chemical feed equipment.
Calibration curves which indicate feed rate setting
versus feeder output must be developed for all
chemical feeders to assure the correct feeder set-
ting for a given desired chemical dosage. Some
chemicals, such as polymers, must often be pre-
pared in dilute solutions prior to introduction into
the plant flow stream. Therefore, the capability to
prepare chemical dilutions must be transferred to
the operators during the CTA. Example chemical
feed calculations are presented in Appendix M,
and a procedure to develop a chemical feeder cali-
bration curve is shown in Appendix J.
Chemical addition must not only be carefully con-
trolled, but the correct type of coagulants, floccu-
lants and filter aids must be applied.
• A positively charged product (e.g., metal salt,
cationic polymer, polyaluminum chloride)
should be added for coagulation. Coagulants
typically require good mixing so they should be
added to the rapid mix.
• If alum is being utilized with a raw water pH
exceeding 8.0 to 8.5, consideration should be
given to switching to iron salts, sodium
aluminates or polymerized products.
• The use of a flocculant polymer to enhance
floe formation and settling can also be investi-
gated.
• Investigation of filter aid polymers should be
conducted since these products are often
required if filtered water turbidities less than
0.1 NTU are to be achieved on a continuous
basis. Flocculant and filter aids typically have
an anionic or nonionic charge, and they should
be introduced into the plant flow stream at a
point of gentle mixing, since excessive turbu-
lence will shear the polymer chains and reduce
the product effectiveness.
• For low alkalinity waters (e.g., <20 mg/L),
consideration should be given to adding alka-
linity (e.g., soda ash, lime).
Some chemicals should not be added at the same
location. For example, the addition of lime and
alum at the same point is counter-productive if the
lime is raising the pH to the extent that the opti-
mum range for alum coagulation is exceeded. The
addition of powdered activated carbon at the same
location as chlorine is also detrimental since the
carbon will quickly adsorb the chlorine, inhibiting
the ability of both chemicals. The addition of chlo-
rine, potassium permanganate or other oxidant, in
combination with some polymers, will result in the
oxidation of the polymer, with a subsequent
reduction in its effectiveness.
Unit Process Controls:
Optimization of unit processes requires that those
parameters that can be controlled to adjust proc-
ess performance be identified and incorporated
into a plant specific process control program.
Ideally, existing process control procedures and
input from plant staff are used to develop this
program. This usually must be supplemented by
information from the CTA facilitator based on
experience at other facilities, equipment manuals,
or networking with peers. Multiple unit processes
and their unique control features exist in water
treatment facilities. An overview of the more con-
ventional unit processes and their associated con-
trols is presented in the following sections.
Mixing. Flocculation. and Sedimentation. The
main controls for mixing, flocculation and sedi-
mentation unit processes include the following:
• Plant process flow rate and flow splitting
between unit processes operating in parallel
• Type of chemical and chemical feed rate (see
Chemical Pretreatment and Coagulation Con-
trol section previously discussed in this
chapter)
• Flocculation energy input
• Sludge removal
• Floe break-up at the effluent of sedimentation
tanks
Plant flow rate is a primary control at many small
plants that are operated for less than 24 hours
each day. At these plants an excessive hydraulic
loading rate on the flocculation/sedimentation
processes can be avoided by operating at a lower
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flow rate for a longer period of time. This provides
an option to meet more rigorous performance
requirements with existing units without major
capital improvements. The capability to reduce
plant flow rate to improve performance is offset by
the need to staff the plant for longer periods of
time, which adds to operating costs. Therefore,
plant administrators and staff, in conjunction with
the CTA facilitator, must evaluate these options.
If multiple basins exist, flow splitting to ensure
equal loading to the units should be monitored and
controlled. Often, performance monitoring (e.g.,
turbidity) of individual sedimentation basins can be
used to indicate unequal flow splits.
Flocculation energy input is often fixed at small
plants, either by hydraulic flocculation systems or
by constant speed flocculation drives. However,
flocculation energy, if low enough to allow forma-
tion of settleable floe, is not considered an essen-
tial variable to achieve desired performance of a
small plant. More important are the plug flow
characteristics of the flocculation system. Plug
flow characteristics, similar to those found in most
hydraulic flocculation systems, result in the forma-
tion of floe particles of uniform size, which greatly
aids settleability. As such, greater priority may be
placed on installing baffling in flocculation systems
rather than trying to optimize mixing energies.
Adequate time for chemical reaction is typically
more important when the water temperature is less
than 5°C, and under these conditions performance
can be improved by reducing plant flow rate.
Sludge needs to be removed from conventional
sedimentation basins frequently enough to prevent
solids carryover to the filters. The frequency of
sludge removal can be determined by using a core
sampler to monitor build-up in the basin. The
duration of sludge removal can be determined by
collecting samples during draw-off (e.g., every
30 seconds) and determining when the sludge
begins to thin. A centrifuge, graduated cylinder, or
Imhoff cone can be used to observe the density
changes.
Sludge control is very important in the operation of
reactor type upflow sedimentation basins that
operate using a sludge blanket. The reactor sec-
tion of the basin must be monitored daily, and the
appropriate amount of sludge must be removed
from the basin to maintain the optimum reactor
concentration and sludge blanket depth. Inade
quate monitoring of the basin can lead to a loss of
the sludge blanket over the weirs, which signifi-
cantly degrades unit process performance and,
ultimately, filter performance. A 100 ml graduated
cylinder has been used to monitor sludge mass in
a reactor type basin. A volume of 18 - 25 ml of
sludge in a 100 ml cylinder, after five minutes of
settling, has provided satisfactory performance at
one location (12).
Another issue to consider is the possibility of floe
breakup after the settled water leaves the sedi-
mentation basins. Depending on the chemical
conditioning used in the plant, coagulated particles
may break apart because of turbulence when the
settled water is conveyed to the filtration process
(e.g., sedimentation effluents with large elevation
changes at the discharge of the basin). If floe
breakup is suspected, operational changes, such
as flooding the effluent weirs, can be tried to
assess if performance improves. Additionally, the
use of a filter aid can assist in overcoming the det-
rimental impacts office breakup.
Filtration. The controls for the filtration process
include the following:
• Coagulation control
• Filtration rate control
• Filter aid chemical and chemical feed rate
• Backwash frequency, duration and rate
• Filter to waste
Proper chemical pretreatment of the water prior to
filtration is the key to acceptable filter performance.
Improper coagulation (e.g., incorrect feed rate,
inappropriate coagulant) fails to produce particles
that can be removed within the filter or to produce
particles large enough that they can be removed
by sedimentation. Because of this impact, the
importance of a good plant specific coagulant
control technique cannot be overemphasized.
For waters that are properly chemically condi-
tioned, filter flow rate becomes less critical. The
most important aspect of flow rate relative to filter
performance is the magnitude and rate of change
of flow rate adjustments (4,13). Rapid, high mag-
nitude flow rate can cause a large number of
particles to be washed through the filter. This can
be observed by the associated increases in
turbidity measurements or particle counts. Since
the filters are the most effective barriers to cysts,
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even short term performance deviations can
potentially expose consumers to significant
concentrations of cysts.
Filtration rate changes most often occur during
backwashing events, raw water pumps cycling on
and off, start-up of filters, and periods when filter
rate controllers malfunction.
• When one filter is removed from service for
backwashing, many operators leave plant flow
rate the same and direct the entire plant flow to
the remaining filter or filters. At plants with a
limited number of filters this places an
instantaneous, high magnitude flow increase
on the remaining filters. This is frequently
inherent in automatic backwash control sys-
tems where the plant was not designed to
adjust flow during backwash. This can be
prevented by lowering the plant flow rate prior
to removing the filter from service, thereby
controlling the hydraulic loading to the
remaining on-line filters.
• Rapid changes in plant influent flow by starting
and stopping constant speed raw water pumps
also encourages the loss of particles from fil-
ters. This may be prevented by using a man-
ual or automatic control valve to slowly adjust
plant influent flow rate.
• Start-up of dirty filters can also result in the
washout of entrained particles. Backwashing
of filters prior to returning them to service is
essential to maintain the integrity of this unit
process.
• Malfunctioning filter rate control valves can
result in rapid changes in filtration rates. The
impact of filter rate control valve malfunctioning
is difficult to identify without continuous on-line
monitoring. An ongoing preventive
maintenance program can be effective to keep
the valves in good working order and to avoid
this source of poor filter performance.
The utilization of a low dose of filter aid polymer
can improve filtered water quality from dual or
mixed media filters. These products are very
effective but, if overdosed, can quickly blind a filter.
They, therefore, should be used at optimum doses
(i.e., typically less than 0.1 mg/L) to avoid exces-
sively short filter runs. Once activated, these
products are subject to shearing because of their
long polymer chains and should be fed at
points of low turbulence, such as flocculation
basins or sedimentation basin effluent lines.
During a filter run, backwashing must occur before
particle breakthrough occurs. Filtered water tur-
bidity should be monitored continuously, and the
filter should be backwashed at the first indication of
an increasing turbidity trend. Particle counters
have recently been used to monitor individual fil-
ters at some plants. Results have shown that par-
ticle breakthrough is indicated prior to deterioration
in filtered water turbidity (14,15). Excessive filter
runs (e.g., greater than 48 hours) can sometimes
make filters difficult to clean during backwash due
to media compaction and can cause an increase in
biological growth on the filter. However, filter run
times are site-specific and should be determined at
each treatment plant. One method to assess filter
run time is to conduct a special study involving
microscopic evaluations of filtered water
throughout the filter run (16,17). Particle
breakthrough, as measured by turbidity or particle
counting, should always remain a primary control
in establishing filter run times.
The filter backwash duration and intensity must be
sufficient to clean the filter, but not so great that
damage occurs with the support gravel and
underdrain system or media is washed out of the
filter. A filter bed expansion test can be used to
assess the adequacy of backwash rate (see the
Field Evaluations section discussed in Chapter 4).
The backwash duration should be long enough to
adequately clean the media, otherwise filter per-
formance will degrade and mudballs could form in
the media. The filter should be probed periodically
(e.g., semi-annually) to inspect for support gravel
problems and to check media depths. Proper
cleaning can be evaluated by inspecting the filter
media for mudballs and overall cleanliness. Filters
occasionally require the addition of media (i.e., top-
ping due to washout of media during backwash).
Operating guidelines should be developed to
describe consistent methods of backwashing fil-
ters. Guideline content should include measures
to: 1) prevent rapid flow rate increases to the
remaining on-line filter(s), 2) ensure that the filter is
properly cleaned, 3) prevent damage to the filter by
operating at excessive flow rates or opening valves
too quickly, and 4) return a filter to service. When
a filter is returned to service following washing, it
should be rested for a period of time to allow the
media to consolidate before it is restarted, or it
should be slow-started by gradually
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increasing the filtration rate over a period of
30 minutes (18). Conducting a special study to
define backwash procedures that result in the
achievement of optimized performance goals
should be completed and serve as the foundation
for the backwash guideline.
At some plants where operational adjustments do
not allow filters to return to optimized performance
goals within 15 minutes following backwash, more
aggressive steps may be required. These include
addition of coagulant to the water used to back-
wash the filter or modifications to provide filter to
waste capabilities. Some utilities have found that
addition of coagulants to the backwash water helps
in minimizing turbidity spikes by conditioning the
filter prior to returning it to service. Filter to waste
allows the initial filtered water to be directed to a
drain until the quality achieves the performance
criteria, at which time it can be redirected to the
clean/veil. These approaches should only be
implemented after other less costly approaches
described above have proven ineffective during a
series of special studies.
Disinfection. The controls for the disinfection
process include the following:
• Contact time
• Disinfectant concentration
• Disinfectant application point
To prove adequate disinfection, the plant unit
processes, including disinfection, must meet a
state-specified criteria for log reduction/inactivation
of Giardia and viruses. Presently, this criteria is
defined as achieving a CT value outlined in the
SWTR Guidance Manual (19). The CT value,
which is the concentration of disinfectant (mg/L)
multiplied by the effective contact time (minutes)
prior to the first user's tap, is affected both by plant
flow rate and the concentration of the disinfectant
applied. The maximum concentration of disinfec-
tant that can be added because of effectiveness
and aesthetic concerns (taste and odor) is normally
2.5 mg/L as free chlorine residual. Therefore,
adjustments to contact time offer the best process
control option for optimizing disinfection. Most
plants apply chlorine as a disinfectant to the
filtered water prior to a clean/veil. The clean/veil is
typically designed as a storage basin for backwash
water or a wet well for finished water pumps and
not as a disinfectant contactor. As a result, there
are no baffles or other means to make the basin
plug flow, and the clean/veil
basin's small size provides limited contact time.
Reducing the plant flow rate, operating at greater
clean/veil depth, or baffling the basin can often be
used to gain more effective contacting.
Adding a chlorine application point prior to the
plant rapid mix to provide contact time in raw water
transmission lines and flocculation and
sedimentation basins can also be evaluated. How-
ever, this practice, while allowing greater CT val-
ues to be obtained, may cause the formation of
excessive disinfection by-products. State regula-
tory personnel should be consulted prior to initiat-
ing this practice.
If operational changes cannot be made to achieve
the specified CT values, modifications to the plant
may be required to provide sufficient disinfectant
contact time. It is noted that actual levels of disin-
fection required for water treatment plants is pres-
ently established by the state where the plant is
located. Additionally, future regulations may
impact disinfection practices (20). Modifications to
a plant's disinfection system should include a
thorough review of proposed regulations and
coordination with the state regulators.
5.3 Case Study
A case study of a CTA is difficult to present
because many of the activities are conducted over
a long period of time and include numerous events
such as on-site training, transfer of technical and
interpersonal skills, weekly data review, phone
consultations and site visits, and multiple special
studies. Since these activities do not lend them-
selves readily to the case study format, an abbre-
viated overview of a CTA will be presented.
5.3.1 CPE Findings
A CPE was conducted at a conventional water
treatment plant that included facilities for chemical
addition, rapid mixing, flocculation, sedimentation,
filtration, and clean/veil storage. Raw water was
supplied to the plant from a reservoir fed by a river.
The facility was constructed in 1994 and had a
rated design capacity of 13 MGD. The plant is
operated 24 hours per day and serves approxi-
mately 23,000 people.
The performance assessment of the plant revealed
that this new facility had not consistently met the
0.5 NTU turbidity limit required by the 1989
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SWTR (21) during its first year of operation. In
fact, enforcement action was being considered by
the state regulatory personnel due to the frequent
violations. Turbidity values at the levels observed
indicated that the plant was definitely not achieving
optimized performance goals as described in
Chapter 2. Along with not meeting the filtered
water optimization goals, the plant had inconsistent
sedimentation basin performance with peaks as
high as 8 NTU. Turbidity spikes of 0.6 NTU after
backwash were also found.
The major unit process evaluation revealed that all
of the major unit processes had sufficient physical
capacity to support achievement of optimized per-
formance goals. The rated design capacity of the
facility was 13 MGD, and the peak instantaneous
flow rate was 7.5 MGD. All of the major unit
processes were rated above the 13 MGD capa-
bility.
Three major performance limiting factors were
identified in the CPE. The highest ranking factor
was related to the operations staffs capability to
apply proper process control concepts to improve
the performance of their facility. Performance
monitoring and process control testing were not
consistent, and data was not developed nor used
to make process adjustments. Limited efforts had
been completed to define optimum chemical feed
strategies. Backwashing practices were inconsis-
tent and not focused on limiting turbidity spikes or
shortening recovery time after filters were placed
back in service.
The second factor was related to administration.
Specific administrative policies were limiting per-
formance of the plant by failing to create an envi-
ronment necessary to support optimization. Start-
up training for the operators in connection with the
new facilities was deleted as a cost saving
measure. Optimization goals were not embraced
by administrative personnel, and personnel
changes at the plant had resulted in conflicting
directives to the plant staff and confusion over who
was in charge.
The third factor was related to design with several
issues related to process controllability. The loca-
tion of the recycle line from the sludge and back-
wash storage pond was after the point of chemical
addition to the raw water. This prevented the plant
staff from properly monitoring and controlling the
coagulation chemistry of the blended raw water.
Chemical feed facilities were also contributing to
the performance problems since several
chemical feed pumps were oversized for current
flows and sufficient flexibility had not been pro-
vided with respect to adding chemicals at various
locations in the plant.
A CTA was initiated at the plant to attempt to
achieve optimized performance goals. The dura-
tion of the CTA was about 18 months, and high-
lights from the project are summarized below.
5.3.2 CTA Activities
5.3.2.1 Initial Site Visit
During the initial site visit, the CTA facilitator used
the CPE results and the priority setting model to
prioritize activities. At the CTA facility, caution had
to be taken to consider the potential adverse
impact of any changes on plant performance and
public health since the facility was producing
unacceptable finished water quality. A contin-
gency plan was developed that included plant
shutdown, lowering plant flow rate, and initiating an
order to boil water. Fortunately, the staff had
improved process monitoring (e.g., began indi-
vidual filter monitoring and initiated sedimentation
basin monitoring) after the CPE exit meeting.
These steps had resulted in process control
changes that allowed improved performance and,
for the most part, compliance with the SWTR.
After the CPE, the plant staff had also dealt with
the oversized chemical feed pumps by interchang-
ing with others within the plant. They also made
provisions for some additional chemical feed
points.
A key step in the CTA was the identification of the
local CTA champion. The person selected was the
new superintendent for the utility. Although he was
new to the position, it was felt that he was the best
choice for utility champion and was the best person
to assist the CTA facilitator in making the
necessary changes to the "old ways of doing
business."
Jar testing procedures were developed, and rou-
tine testing was initiated. A sampling and jar test
set-up modification was implemented to allow jar
testing to be conducted on the blended raw water
and recycle water. Based on the jar test results,
the need for coagulant dosage adjustments was
indicated. The operations staff participated in all of
the testing and data development. Despite the
results, the staff was reluctant to make changes.
This stemmed from the fact that jar testing had
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never been a routine activity at the plant and, thus,
the operators lacked the confidence to take jar
tests results and use the information to make
chemical feed changes in the plant. However, a
staff consensus of "We don't think it will work, but
we can try it" was achieved. Preliminary results
during the site visit were very encouraging.
A formal meeting was set up between the CTA
facilitator and the plant staff to discuss additional
high priority items. The topics for discussion were
established by the CTA facilitator. During this
meeting, optimized unit process performance goals
were established. The guidelines in Chapter 2
were used to set the performance goals. Limited
staff acceptance for the goals was accomplished at
this meeting because they were more focused on
just being able to meet the SWTR requirements.
In addition, they did not have the confidence that
the optimized treatment goals could be met.
Sampling, monitoring and data recording
procedures were also discussed. The negative
impact of the location of the recycle line was also
discussed, and it was decided to pursue modifica-
tion of this line with the utility administration.
An action list was developed which included
assignments to the staff to develop operational
guidelines on jar testing and unit process perform-
ance sampling, monitoring, and data recording.
Arrangements were made with the on-site CTA
champion to provide plant monitoring and per-
formance data to the CTA facilitator on a weekly
basis.
Prior to the conclusion of the site visit, the CTA
facilitator and the on-site CTA champion met with
the City Manager and the Director of Public Works.
The basis for the meeting was to report on the
process control changes and the action list and to
initiate discussions on the desired recycle line
modification. The initial response on the need for
the recycle line was "Wasn't that the design
consultant's responsibility?". The CTA facilitator
identified that the optimized performance goals
that were being pursued required much closer con-
trol than would be required to just meet the SWTR
requirements. The utility was encouraged to pur-
sue modifications on their own, and the administra-
tors agreed to begin an evaluation of the possible
approaches for completion of the modification and
associated costs. A discussion was also held
concerning the less-than-enthusiastic response by
the staff to the new procedures and performance
goals. This information was provided to lay the
groundwork for administrative support if Condi
tions didn't change. Questions were received from
the administrators concerning the need and costs
of achieving water quality goals that exceeded
regulatory requirements. The public health
implications were explained by the CTA facilitator,
with only limited acceptance on behalf of the
administrative personnel. A report which
summarized the progress made and the action list
that was developed was prepared by the facilitator
at the conclusion of the site visit.
5.3.2.2 Off-Site Activities
The on-site CTA champion provided drafts of the
agreed upon guidelines as well as weekly summa-
ries of plant data. The CTA facilitator reviewed the
guidelines and provided written comments to the
utility. Data review was also completed by the
CTA facilitator, and trend charts were developed to
aid in data interpretation.
Phone calls were made on a weekly basis to dis-
cuss data trends and to follow up on action items.
Feedback from the CTA champion indicated that
even after his best efforts, the plant staff were still
balking at the increased sampling and laboratory
activities and that the administration had not pur-
sued the recycle line modification. A decision was
made to make a return site visit to address these
issues.
5.3.2.3 Follow-Up Site Visit
During the second site visit the nominal group
process was used to establish priorities for con-
tinued optimization activities (see Priority Setting
Tools section previously presented in this chapter).
The issue of increased work load and lack of rec-
ognition was rated high and received extensive
discussion. The CTA facilitator used the trend
charts developed from plant data to show the
improvements that had been accomplished in
achieving optimized performance goals. Several of
the operators took pride in these accomplishments
and voiced support for the increased process con-
trol activities. However, one operator remained
adamantly opposed to the changes. At the con-
clusion of the discussion it was decided to continue
the additional process control effort for at least
several more months.
The concept of special studies was introduced
during the staff meeting, and two special studies
were developed to evaluate the use of a filter aid
87
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polymer and to assess control of backwash spikes.
Additional guidelines for turbidimeter calibration
and sludge removal from the sedimentation basins
were also discussed. An action list was developed
to conduct the special studies, draft the additional
guidelines, and to pursue the modification to the
recycle line.
At the conclusion of the site visit, an administrative
exit meeting was held where the preliminary graph
of improved performance was presented. The
results of the plant meeting and discussions were
presented, and support for the recycle line
modification was again requested. These discus-
sions revealed that the administrators did not
completely understand the importance of the recy-
cle line modifications with respect to being able to
perform effective process control. Once they
understood the need for timely modifications to the
recycle line, these modifications were quickly
made.
A report was prepared by the facilitator at the
conclusion of the second site visit which summa-
rized the progress made and the updated action
list. The site visit was an effective mechanism to
demonstrate improved performance to the utility
staff, provide positive feedback on achieving
interim milestones, and reinforce the long term
project goals. This site visit also demonstrated the
importance of the facilitator in resolving issues that
the CTA champion finds difficult to resolve on
his/her own.
5.3.2.4 Other CTA Activities
Activities conducted by the CTA facilitator off-site
and on-site (an additional two site visits) continued,
using a similar format for another twelve months.
During that time, the modification to the recycle line
was accomplished, and process control skills were
transferred to all of the plant staff. A significant
part of transferring process control skills was
getting all of the operators to accurately record
individual filter effluent turbidities on the plant's
process control sheets. Procedures had to be
developed and implemented where readings
above a certain level (0.1 NTU) had to be verified
before being recorded. A total of 23 operational
guidelines were developed by the plant staff.
Acceptance of the optimization goals and the
process control procedures to achieve them were
not quickly accepted by all of the operators. One
recalcitrant operator was found to be undermining
the CTA champion's efforts to get consistent
process control procedures implemented. A sig-
nificant amount of the time during the CTA was
involved in obtaining the administrative support to
reassign this person to maintenance.
After the CPE, the plant staff made changes to the
existing piping so that polymers could be added
before and after the rapid mix basin. During the
CTA, a decision was made that a separate polymer
feed system would also be needed so that a filter
aid could be added to the sedimentation basin
effluent. This was deemed necessary to meet the
filter effluent and backwash spike turbidity goals.
Controlling the turbidity spikes after filter backwash
required a significant effort by the plant staff. Many
special studies were completed to evaluate a
variety of filter backwash procedures, including
gradual ramping of the backwash flow and resting
of the filter before returning it to service. Problems
were also found with the sample tap locations
when the special study results showed that the
spikes were eliminated on two of the filters but
remained on the other two.
5.3.2.5 CTA Results
Figure 5-10 graphically depicts the success of the
case history CTA. There was a dramatic change
from highly variable finished water prior to the CPE
to stable, high quality finished water after the CTA.
Along with the optimized performance from their
filters, Figure 5-11 shows how the plant also
achieved the settled water turbidity performance
goals. Additionally, after much effort, the plant has
essentially eliminated the turbidity spikes after
backwash, as shown in Figure 5-12. A significant
benefit achieved from the CTA was the develop-
ment of staff tenacity to address any deviations
from the optimized water quality goals. This
tenacity, coupled with the experience and confi-
dence that the staff gained during the CTA, sup-
ports the long term achievement of the optimization
goals. This is demonstrated in Figure 5-13 which
shows the performance of this plant for a year after
completion of the CTA without the assistance of
the facilitator.
88
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Figure 5-10. Performance improvement during CTA project - filter effluent.
Apr-94 Jul-94 Oct-94 Jan-95 Apr-95 Jul-95
Oct-95 Jan-96
Apr-96
Figure 5-11. Performance improvement during CTA project - sedimentation basin effluent.
c
w
3.00
2.50
C
O
I S 2.00
0) I—
E =,
0 .-e 1.50
E €
x
re
0.00
Apr-95 Jun-95 Aug-95 Oct-95 Dec-95 Feb-96
Date
89
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Figure 5-12. Performance improvement during CTA project -filter backwash spikes.
0.3
,£• 0.2
0.1
0.0
10 15 20
Time After Filter Start-Up
25
30
Figure 5-13. Plant performance after CTA.
0.25
0.00
Jan-97 Mar-97 May-97 Jul-97 Sep-97 Nov-97 Jan-98 Mar-98
Date
90
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Additionally, the administrators developed pride in
their utility's capability to maintain consistent, high
quality treated water that exceeds regulatory
requirements. Most importantly, the consumers of
the utility's water have benefited from the high level
of protection against water-borne disease
outbreaks.
A final CTA report was prepared and was used to
present the benefits of utilizing the CTA process to
plant administrators.
5.4 References
When an NTIS number is cited in a reference, that
reference is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
1. Public Notification Regulation Rule. October
1987. U.S. Environmental Protection Agency,
40 CFR, Part 141, Subpart D, Reporting, Pub-
lic Notification and Record Keeping.
2. Renner, R.C., B.A. Hegg, and J.H. Bender.
March 1990. EPA Summary Report: "Opti-
mizing Water Treatment Plant Performance
With the Composite Correction Program.
EPA 625/8-90/017, USEPA Center for Envi-
ronmental Research Information, Cincinnati,
OH.
3. Renner, R.C., B.A. Hegg, and D.L. Fraser.
February 1989. "Demonstration of the Com-
prehensive Performance Evaluation Technique
to Assess Montana Surface Water Treatment
Plants." Presented at the 4th Annual ASDWA
Conference, Tucson, AZ.
4. USEPA. February 1991. Handbook: Opti-
mizing Water Treatment Plant Performance
Using the Composite Correction Program.
EPA 625/6-91/027, USEPA Office of
Research and Development, Cincinnati, OH.
5. Water Rates and Related Charges (M25).
1986. AWWA Reference Manual, No. 30026,
Denver, CO.
6. Small System Guide to Rate Setting. Commu-
nity Resource Group, Inc., Springdale, AK.
7. USEPA. 1989. A Water and Wastewater
Manager's Guide for Staving Financially
Healthy. USEPA (#430-09-89-004), Cincinnati,
OH.
8. Hudson, H.E., Jr. 1980. Water Clarification
Processes: Practical Design and Evaluation,
Van Nostrand Reinhold Co.
9. Singley, H.E. June 1981. "Coagulation Con-
trol Using Jar Tests." Coagulation and Filtra-
tion: Back to Basics, Seminar Proceedings,
1981 Annual Conference, p.85. AWWA,
Denver, CO.
10. Hudson, H.E. and J.E. Singley. June 1974.
"Jar Testing and Utilization of Jar Test Data."
Upgrading Existing Water Treatment Plants,
AWWA Seminar Proceedings, VI-79. Denver,
CO.
11. AWWA. 1992. Operational Control of
Coagulation and Filtration Process. AWWA
Manual M37. AWWA, Denver, CO.
12. Process Applications, Inc. December 1990.
"Summary Report - Loma, Montana Water
Treatment Plant Composite Correction Pro-
gram." Unpublished report.
13. Cleasby, J.L., M.M. Williamson, and E.R.
Baumann. 1963. "Effect of Filtration Rate
Changes on Quality," Journal AWWA, 55:869-
878. Denver, CO.
14. West, T., P. Demeduk, G. Williams,
J. Labonte, A. DeGraca, and S. Teefy. June
1997. "Using Particle Counting to Effectively
Monitor and Optimize Treatment." Presented
at AWWA Annual Conference, Atlanta, GA.
15. Veal, C., and B. Riebow. May 1994. "Particle
Monitor Measures Filter Performance."
Op/tow, Vol. 20, No. 5. AWWA, Denver, CO.
16. Hibler, C.P. and C.M. Hancock. "Interpretation
- Water Filter Particulate Analysis." CH
Diagnostic & Consulting Service, Inc., Fort
Collins, CO.
17. Hibler, C.P. "Protocol - Sampling Water for
Detection of Waterborne Particulates, Giardia,
and Cryptosporidium." CH Diagnostic &
Consulting Service, Inc., Fort Collins, CO.
91
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18. Pizzi, N. 1996. "Optimizing Your Plant's Filter 21. "Surface Water Treatment Rule." June 1989.
Performance." Opflow, Vol.22, No.5. AWWA, From Federal Register, Vol. 54, No. 124, U.S.
Denver, CO. Environmental Protection Agency, 40 CFR,
Parts 141 and 142, Rules and Regulations, Fil-
19. USEPA. October 1989. Guidance Manual for tration/Disinfection.
Compliance With the Filtration and Disinfection
Requirements for Public Water Systems Using
Surface Water Sources. NTIS No. PB-90 148-
016, USEPA, Cincinnati, OH.
20. USEPA. 1997. Microbial/Disinfection By-
Products Federal Advisory Committee Agree-
ment in Principle. Dated June 9, 1997.
Signed July 15, 1997.
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Chapter 6
Findings From Field Work
6.1 Introduction
This chapter summarizes findings from the field
activities and draws conclusions concerning future
efforts and potential impacts of utilizing the CCP
approach in improving performance of surface
water treatment plants.
The field activities conducted to refine the CCP
approach have focused on three distinct areas:
• Development/application of the process to
water treatment plants.
• Demonstration and transfer of principles and
practices to state, third-party and utility per-
sonnel.
• Incorporation of the process into an area-wide
optimization program (see Chapter 3).
In addition, the CCP approach has evolved from a
focus of achieving compliance with the Surface
Water Treatment Rule (1) to one of minimizing the
passage of Cryptosporidium oocysts through the
treatment plant by achieving optimized perform-
ance goals (see Chapter 2).
The basis for the conclusions and results
described in this chapter is drawn from 69 CPEs
and 8 CTAs conducted in 17 states and Canada.
The geographical distribution of the CPEs and
CTAs is described in Table 6-1. The plants had a
wide range of peak instantaneous operating flow
rates and populations served. Thirty-five percent
of the plants served communities with populations
less than 3,300, with peak flow rates typically less
than 3.0 MGD, while 10 percent of the plants
provided service to populations in excess of
50,000 persons. The majority of the systems
served small to medium-sized communities.
Larger plants typically required more time to
conduct the plant tour and interviews; otherwise,
the CPE process was only minimally affected by
plant size.
All of the plants evaluated used surface water for
their raw water source. The majority of the plants
utilized conventional treatment consisting of rapid
mix, flocculation, sedimentation, filtration and
disinfection. Several of the plants that were
evaluated operated in a direct or in-line direct fil-
tration mode. Three lime softening plants were
evaluated. In addition, several types of unique
filtration processes were evaluated; they included
automatic valveless gravity filters, traveling bridge
backwashing filters, and several types of pressure
filters. The CCP approach was found to be appli-
cable regardless of plant size or type.
Table 6-1. Geographical Distribution of CPEs
and CTAs
CPEs CTAs
Montana
Maryland
West Virginia
Texas
Massachusetts
Pennsylvania
Canada
Colorado
Navajo Tribal
Lands in Utah,
New Mexico
11 3
10
8 1
7 1
4
4 1
4
3 1
2 1
CPEs
Louisiana
Rhode Island
Wisconsin
Kentucky
Ohio
California
Vermont
Washington
3
3
3
2
2
1
1
1
6.2 Results of Comprehensive
Performance Evaluations
6.2.1 Major Unit Process Capability
A summary of the major unit process capability for
the 69 plants is shown in Table 6-2. The unit
processes were assigned a rating of Type 1, 2 or 3
depending on their projected ability to consistently
meet optimized performance goals at the peak
instantaneous operating flow rates under ideal
conditions. Ideal conditions are those in which all
ancillary features of a unit process are operational
(e.g., paddles, drive motors and inter-basin baffles
are functional in a flocculation basin) and process
control activities have been optimized.
93
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As described in Chapter 4, a Type 1 or 2 rating
indicates that the unit processes are potentially
adequate to consistently meet optimized perform-
ance goals. A unit process rated as Type 3 would
not be expected to perform adequately.
Table 6-2. Summary of the Major Unit Process
Ratings for 69 Plants
Flocculation
Sedimentation
Filtration
Post-Disinfection
Only
Pre- & Post-
Disinfection
Typel
Percent
of Plants
88%
77%
86%
46%
86%
Type 2
Percent
of Plants
7%
17%
13%
3%
5%
Type3
Percent
of Plants
5%
6%
1%
51%
9%
The basis for rating the major unit processes has
been consistent for all 69 CPEs except for the
disinfection process. The disinfection process ini-
tially was evaluated on the ability of a plant to
provide two hours of theoretical detention time.
This was done for the initial nine plants evaluated
in Montana. The disinfection evaluation was later
modified based on the SWTR CT requirements.
The disinfection ratings for the initial nine Montana
CPE sites are not included in the summary in
Table 6-2.
As shown in Table 6-2, the flocculation, sedimen-
tation and filtration unit processes were typically
judged adequate to justify attempts to optimize
performance using existing facilities (e.g., major
unit processes rated either Type 1 or 2). Only 5
percent of the flocculation and 6 percent of the
sedimentation processes were judged to require
major capital improvements. Also, the filtration
processes were almost always rated as being
Typel. In some circumstances filters that had
been rated as Type 1 were found to require modi-
fications such as media replacement because of
damaged underdrains or support gravels; however,
media replacement was not judged to be a major
construction requirement. In some circumstances,
reducing the peak instantaneous flow rate and
operating the plant longer enabled a Type 3 unit
process to be reclassified as Type 2 or 1. Based
on these findings, it was projected that 92 percent
of the plants evaluated could meet optimized per-
formance goals without major capital construction.
Disinfection was evaluated at 60 of the facilities
with respect to their ability to meet the CT
requirements of the SWTR. Post-disinfection
alone was only found capable to meet the CT
requirements in 49 percent of the plants. The
primary deficiency was the limited contact time of
the clean/veils that were typically designed to pro-
vide backwash water storage or wet wells for high
service pumps. The majority of disinfection contact
basins were unbaffled and operated on a fill and
draw basis. This operation is less than ideal for
optimizing contact time.
For facilities where both pre- and post-disinfection
was practiced, 91 percent of the plants were pro-
jected to comply with the SWTR CT requirements.
Although use of both pre- and post-disinfection
may allow some plants to provide adequate disin-
fection capability with existing facilities, its appli-
cation may be limited due to requirements related
to the allowable levels of disinfection by-products
(DBPs). Proposed requirements of the Disinfec-
tants and Disinfection By-Products Rule (2) would
establish DBP requirements for all systems. The
final regulations regarding CT credit for
predisinfection will be established by individual
states. Because the regulations governing
disinfection are changing, it is likely that capability
projected from the historical CPE disinfection unit
process evaluations will change.
6.2.2 Factors Limiting Performance
Factors limiting performance were identified for
each of the 69 CPEs utilizing the list of factors
described in Appendix E. An average of eight fac-
tors was identified at each plant. Each factor was
given a rating of A, B, or C, depending on its
impact on performance (see Chapter 4). To
assess the degree
of impact from an overall basis, A factors (i.e.,
major impact on performance) were assigned 3
points, B factors (i.e., moderate impact on
performance on a continuous basis or a major
impact on performance on a periodic basis) were
assigned 2 points, and C factors (i.e., minor impact
on performance) were assigned 1 point. The
summary of factors that occurred most frequently
and the degree of impact of the factors identified
during the 69 CPEs are presented in Table 6-3
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Table 6-3. Most Frequently Occurring Factors Limiting Performance at 69 CPEs
Rank
1
2
3
4
5
6
7
8
9
10
11
12
Factor
Applications of Concepts
Disinfection
Process Control Testing
Sedimentation
Filtration
Administrative Policies
Process Flexibility
Process Controllability
Flocculation
Water Treatment Understanding
Plant Staff
Ultimate Sludge Disposal and/or
Backwash Water Treatment
Category
Operations
Design
Operations
Design
Design
Administrative
Design
Design
Design
Operations
Administrative
Design
Number
of
Points
113
112
88
79
72
69
58
47
45
41
40
39
Number
of
Plants
43
39
36
39
29
29
29
22
23
14
18
15
Three of the top twelve factors were related to
operations: Number 1- Application of Concepts,
Number 3 - Process Control Testing, and Number
10 - Water Treatment Understanding. The overall
high ranking of operational-related factors is of
major significance. Consistently achieving opti-
mized performance goals requires optimization of
each unit process in the treatment scheme. Addi-
tionally, achieving optimized performance goals
requires timely adjustments in response to chang-
ing raw water quality.
Essentially, inadequate or marginal process control
programs existed in over half of the plants where
CPEs were conducted. At 62 percent of the plants,
the operators had problems applying their
knowledge of water treatment to the control of the
treatment processes. These operators could dis-
cuss coagulation chemistry and filter operation but
had difficulty in demonstrating that they could
apply this knowledge to changing raw water quality
and subsequently to achieving optimized
performance goals. Water treatment understand-
ing was identified at 14 of the 69 plants. A lack of
understanding means that the operators did not
have the basic knowledge of water treatment,
which would make successful implementation of a
process control testing program impossible. Since
operator limitations in applications of concepts and
limitations in water treatment understanding are
mutually independent in identifying CPE factors,
these results can be combined, which indicates
that 85 percent of the plants had operational limi-
tations that adversely impacted performance.
Seven of the top 12 factors were related to design
aspects of the facility. While most flocculation,
sedimentation, and filtration processes were found
to be of adequate size during the major unit proc-
ess evaluation, limitations associated with these
unit processes contributed to their identification as
factors limiting performance. Sedimentation proc-
esses were projected to be marginal at 39 plants,
typically due to the inability to treat seasonal high
raw water turbidities, improper placement of efflu-
ent weirs that disrupted quiescent settling, and
effluent conditions that resulted in floe shear prior
to filtration. Problems such as backwash limita-
tions, improperly maintained rate-of-flow control-
lers, and disrupted support gravels and
underdrains contributed to filtration being identified
as a performance limiting factor. Flocculation
problems were typically related to marginal vol-
ume, lack of multiple stages, fixed speed mixer
drives that made tapered flocculation impossible,
and inoperative mechanical equipment.
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Disinfection was also identified as a top factor
limiting performance. As noted, the adoption of
final regulations by the states may affect the future
results in identifying the ranking of this factor.
Although plants may be able to improve contact
time by installing baffles, some plants may require
major capital improvements (e.g., new contact
basins, alternate disinfectant capabilities) to
accommodate the need for greater contact time
and/or reduced DBP levels.
Process flexibility, process controllability and ulti-
mate sludge disposal/backwash water treatment
were the other design factors that were consis-
tently identified. The identification of these factors
was usually attributed to plants that were not
equipped with the capability to add chemicals at
different points in the plant, were unable to operate
processes in different configurations (e.g., series or
parallel), were unable to measure or control flows
through processes, or lacked appropriate
backwash water treatment facilities that limited the
plant's ability to backwash filters based on
performance degradation.
It was projected that implementing minor modifica-
tions, reducing peak flows, and improving process
control could provide alternatives at individual
facilities to avoid major modifications. Ideally,
CTAs implemented at these facilities could be used
to implement these alternatives. If the CTA results
were unsuccessful, a construction alternative could
be more clearly pursued. It was concluded that,
despite the high ranking for design factors,
immediate construction of major plant
modifications was not indicated or warranted.
Two administrative factors, policies and inadequate
plant staff, were among the top factors identified.
Plant administrative policies were observed in 29
CPEs to be detrimental to performance. Typically,
these administrators were not aware of the
significance of finished water quality. For example,
most were unaware of the impact on public health
of even short-term excursions from high quality
treated water. Additional items contributing to the
identification of these factors included plant
administrators that: 1) were not aware of plant
resources or training requirements, 2) could not
relate the impact of their decisions on plant
performance and thus public health, 3) had
policies related to minimizing production cost at the
expense of performance, and 4) maintained plant
staffing at levels too low to support process control
requirements.
Eighteen of the 69 plants had a plant staff size
considered to be too small to properly operate and
monitor the treatment plant. This was considered
to be critical with respect to the projected need for
increased levels of process control and monitoring
required to achieve optimized performance goals.
Staffing limitations were felt to be especially critical
for plants that were being operated for periods
without staff on-site and without alarm and shut-
down capability triggered by performance parame-
ters.
It was interesting to note that insufficient resources
were not found to be a significant factor limiting
performance of the water plants evaluated despite
the fact that lack of resources is a widely publicized
reason for noncompliance of small systems.
Insufficient funding was identified in only 13 of 69
plants. Furthermore, in only 4 of the 13 plants
where insufficient funding was identified, it was
considered to be a major factor limiting per-
formance. Numerous utilities had sizable capital
reserve funds, and those that did not often had
water rates set at unreasonably low levels. It was
projected that resources could be made available
to address operations limitations and to implement
minor design modifications at these facilities. Time
would be required in follow-up CTAs at these
utilities to gain administrative support and under-
standing for reallocation or development of
resources, but the option to achieve this support
was projected to be viable.
The lack of identification of any significant mainte-
nance-related factors is also important to note.
Maintenance-related factors were assessed as
having a lessor or minor impact relative to the
operations and administrative factors. Only 2 of
the 69 CPEs had a maintenance factor identified
as having a major impact on performance. At both
facilities, total neglect was apparent. At these
facilities administrative policies that were contrary
to supporting the integrity of the infrastructure were
also identified as factors.
6.2.3 Summary of CPE Findings
• The flocculation, sedimentation and filtration
processes in 92 percent of the plants were
projected to have adequate capacity to handle
plant peak instantaneous operating flows.
• Construction would be required for 13 percent
of the plants if only post-disinfection were
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allowed, and baffling of existing clean/veils is
not sufficient. Disinfection capabilities are
dependent on the final interpretation and
implementation of the disinfection regulations
by individual states.
Operations factors limited performance in 60
percent of the CPEs performed. This finding,
coupled with the fact that 92 percent of the
existing facilities were assessed to have ade-
quate capacity to meet turbidity removal
requirements, indicates that addressing opera-
tions factors could significantly improve water
treatment plant performance.
Although design factors represent half of the
top factors identified, it was projected that
these deficiencies could be satisfactorily
addressed in many cases by utilizing minor
modifications, decreasing plant flows, and
improving process control/operations.
Administrative factors were identified as having
a significant impact on plant performance.
Training of plant administrators must be an
integral part of implementation of programs to
optimize performance.
Administrators must assure that adequate pro-
visions have been made to deal with compla-
cency and reliability issues. These issues are
prevalent for systems using stable high quality
source waters where administrators and staff
may be lulled into a false sense of security by
over-relying on the source water to protect
them from performance degradation. Adminis-
trators need to encourage operational staff to
maintain skills relative to proper process con-
trol for changing source water quality.
Impacts due to plant size only affected the
amount of time that it took to conduct the
actual CPE. Larger plants required more time
to conduct the interview process due to larger
operational and administrative staffs, yet the
approach was still applicable to large systems.
On-site performance assessments indicated
that reported finished water turbidities were
often not representative of true performance.
Continuous recording of turbidity from each fil-
ter is considered essential to provide operators
with enough information to minimize excur-
sions in treated water turbidities.
• Numerous plant-specific impacts on perform-
ance were identified during the conduct of the
CPEs:
• Lack of attention to filter rate control
devices resulted in deteriorated filter per-
formance.
• Lack of attention to the impact of flow rate
changes on operating filters resulted in
deteriorated filter performance.
• Starting dirty filters resulted in deterio-
rated filter performance.
• Filter performance immediately following
backwash was often unsatisfactory and
posed a significant health threat during
this critical operational period. Improved
operational practices, chemical condition-
ing of the backwash water, or use of
existing filter-to-waste provisions are
alternatives to address this negative
impact on filter performance.
• Adequate process control was only prac-
ticed in just over half of the plants where
CPEs were conducted.
• Decreased flows and increased operating
time offer a significant alternative to con-
struction of new facilities for many small
water treatment plants.
• Exit meetings with the administrators
were identified as one of the major advan-
tages of the CPE over other surveys and
inspections.
6.3 Results of Comprehensive
Technical Assistance Projects
CTAs have been conducted at eight facilities to
establish that plant performance could be
improved. Seven facilities achieved improved per-
formance without major capital expenditures.
Budget constraints limited completion of the
remaining CTA, and improved performance was
not documented at this facility. Of the seven
facilities where successful CTAs were imple-
mented, four were completed when the goal was to
meet the 0.5 NTU turbidity requirement of the
SWTR. The remaining three facilities were com-
pleted when the performance objective was the
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optimized performance criteria outlined in
Chapter 2. It is noted that performance results of
all seven of the facilities where CTAs were
completed would meet the proposed turbidity
performance objectives outlined in the IESWTR.
(3)
The potential in existing facilities to achieve current
and proposed regulatory requirements is a viable
alternative for many water treatment utilities. More
importantly, the CTA component has demonstrated
that optimized performance goals can be achieved
at small to medium-sized facilities without major
construction. This capability should be utilized,
especially at high risk facilities, as described in
Chapter 3, to obtain maximum benefit toward
public health protection from existing plants.
6.4 References
When an NTIS number is cited in a reference, that
reference is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
1. Surface Water Treatment Rule From Federal
Register, Vol. 54, No. 124. June 1989. U.S.
Environmental Protection Agency, 40 CFR,
Parts 141 and 142, Rules and Regulations, Fil-
tration/Disinfection.
2. USEPA. Novembers, 1997. National Primary
Drinking Water Regulations: Disinfectants and
Disinfection Byproducts; Notice of Data
Availability; Proposed Rule. Fed. Reg.,
62:212:59338.
3. USEPA. Novembers, 1997. National Primary
Drinking Water Regulations: Interim Enhanced
Surface Water Treatment Rule; Notice of Data
Availability; Proposed Rule. Fed. Reg.,
62:212:59486.
98
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Chapter 7
The Future: Changing Regulations and
New Optimization Challenges
7.1 Introduction
This handbook presents procedures for optimizing
filtration plant performance for particle removal. It
is the intent of this chapter to discuss how, even
when a water system has used these procedures
and attained the desired turbidity performance
goals, the challenges of plant optimization will
continue. Water systems face other regulatory
requirements, both current and future, that they will
need to consider as they maintain the optimized
turbidity performance achieved through use of the
CCP procedures. While water systems must
comply with a wide variety of drinking water
regulations, this chapter will focus on a series of
regulations known as the microbial-disinfectants/
disinfection by-product regulations (M-DBP) which,
from a regulatory perspective, represent one of the
biggest challenges facing water suppliers over the
next several years. It is not intended that this
chapter discuss the detailed requirements of these
regulations or serve as the definitive resource on
the technical issues around these regulations.
Most of these regulations have not been finalized;
and, when finalized, USEPA will provide detailed
guidance on the specific requirements and the
relevant technical information needed to comply.
7.2 Background on M-DBP Regulations
The M-DBP regulations were the result of a regula-
tory negotiation process (Reg-Neg) in 1993 (1,2,3)
between the USEPA and representatives of the
water supply industry over mutual concerns about
the possible health impacts of microbial pathogens
and DBPs. The following concerns were identified
during discussions to identify ways to minimize
health risks:
1. The adequacy of microbial control, especially
for Cryptosporidium, under the current Surface
Water Treatment Rule (SWTR).
2. The possibility that, if systems were to reduce
levels of disinfection to control DBPs, microbial
control could be compromised.
Control of microbial pathogens and DBPs were
linked together in these regulatory discussions
because of a fundamental concern that operational
changes to control DBPs could potentially lead to
changes in treatment. These changes could
adversely impact microbial pathogen control.
Regulations for microbials and DBPs, therefore,
needed to simultaneously consider the inherent
tradeoff of public health risks associated with
changing treatment practices for reducing levels of
DBPs along with the potential risks of lower
microbial pathogen control. In order to balance
these "risk-risk" tradeoffs, separate regulations for
microbial pathogens and DBPs are to be promul-
gated with effective dates set such that water sys-
tems will have to comply with both regulations at
the same time.
The original M-DBP Reg-Neg agreement included
the following:
• A "Stage 1" DBP regulation that would apply to
all systems. This regulation would initially
apply to systems with a population of >10,000.
Systems with a population of <10,000 would
have extended compliance dates.
• A "Stage 2" DBP regulation to evaluate the
need for further reductions in DBPs when more
health effects and occurrence information
becomes available.
• An "Interim" Enhanced SWTR (IESWTR) for
PWSs >10,000 to address improvements in
microbial control and risk-risk trade-off issues
related to the "Stage 1" DBP regulation which
would be implemented at the same time.
• A "Long Term" ESWTR (LTESWTR) that
would apply to PWSs <10,000 which would be
implemented when they are required to comply
with the "Stage 1" DBP regulation. This
regulation could also include enhancements
that would also apply to the large systems.
99
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During the Reg-Neg process there was also
agreement that additional data and research was
needed on occurrence, treatment capabilities, and
health effects of both microbials and DBFs to pro-
vide a sound technical basis for these regulations.
These issues were to be resolved by:
• An Information Collection Rule (ICR) to collect
occurrence and treatment information to
evaluate possible components of an IESWTR,
LTESWTR, and "Stage 2" DBP regulations.
• Additional research, including health effects
studies, to support regulatory development.
In July 1994, USEPA proposed a "Stage 1" DBP
regulation (4) and an IESWTR (5) which reflected
the 1992-93 negotiations. The ICR was promul-
gated in May 1996 (6) with data collection starting
in July 1997 and continuing for 18 months. Based
on this schedule, the ICR data will not be collected,
validated and available for regulation development
until January 2000.
In August 1996 congress passed amendments to
the Safe Drinking Water Act (SDWA) (7) that
included the following statutory deadlines for
USEPA to promulgate the M-DBP regulations:
• IESWTR and "Stage 1" DBPs - November
1998
• LTESWTR - November 2000
• "Stage 2" DBPs - May 2002
These deadlines were such that it would be
impossible to use the ICR data to develop the
IESWTR and LTESWTR as intended by Reg-Neg.
In early 1997, USEPA formed the M-DBP Advisory
Committee under the Federal Advisory Committee
Act (FACA) to help the Agency meet the new
SDWA deadlines. This resulted in an agreement in
principle that formed the basis for the Notice of
Data Availability (NODA) for the "Stage 1" DBP (8)
and the IESWTR (9) to supplement the 1994
proposal for these regulations. Based on com-
ments on the 1994 proposals and these NODAs,
the IESWTR will be promulgated in November
1998. USEPA plans to promulgate the LTESWTR
in 2000 in order to meet the SDWA mandate with a
compliance date that will correspond to the "Stage
1" DBP regulations for PWSs <10,000. Even
though the LTESWTR applies to PWSs <10,000, it
could include refinements for larger systems.
USEPA also plans to promulgate a "Long Term 2"
ESWTR (LT2ESWTR) at the same time that the
"Stage 2" DBP regulation is promulgated in order
to address risk-risk trade-offs.
7.3 M-DBP Requirements Relative to
Optimized Performance Goals
The discussions above indicate that by the year
2002 USEPA will have promulgated several differ-
ent SWTRs and DBP regulations, and water sys-
tems will be facing compliance. It is also apparent
that these regulations are interrelated such that
water systems will need to consider the impacts of
treatment process changes from the perspective of
both regulations. The remainder of this section will
discuss some of the major areas where special
consideration of optimization with respect to
M-DBP will need to be considered.
7.3.1 Treatment Technique Turbidity
Requirements
Figure 7-1 presents a historical perspective of tur-
bidity goals and regulations. The original SDWA
passed by congress in 1974 (10) required USEPA
for the first time to regulate turbidity. A require-
ment of 1 NTU was established, which was to be
measured at the combined plant effluent based on
one sample per day. There was also a maximum
turbidity level of 5 NTU. In 1989 the original SWTR
(11) was promulgated that lowered the combined
plant turbidity levels to 0.5 NTU based on samples
every four hours, but retained the maximum of 5
NTU.
The 1997 Microbial and Disinfectants/Disinfection
Byproducts (M-DBP) Federal Advisory Committee
meetings, resulted in the collection, development,
evaluation, and presentation of substantial data
and information related to turbidity control. The
FACA committee recommended that the turbidity
performance requirements be changed such that
the combined filter effluent limit be reduced to
0.3 NTU and that the maximum value be reduced
to 1 NTU. In addition, the Committee recom-
mended that systems conduct individual filter
monitoring and that exceptions reports be provided
to states under specific circumstances, namely:
100
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1. any individual filter with a turbidity level greater
than I.O NTU based on two consecutive
measurements fifteen minutes apart; and
2. any individual filter with a turbidity level greater
than 0.5 NTU at the end of the first four hours
of filter operation based on two consecutive
measurements fifteen minutes apart.
The Committee also recommended that if an indi-
vidual filter has turbidity levels greater than I.O NTU
based on two consecutive measurements fifteen
minutes apart at any time in each of three
consecutive months, the system should be
required to conduct a self-assessment of the filter,
utilizing as guidance relevant portions of guidance
issued by the Environmental Protection Agency for
Comprehensive Performance Evaluation (CPE).
Also, if an individual filter has turbidity levels
greater than 2.0 NTU based on two consecutive
measurements fifteen minutes apart at any time in
each of two consecutive months, the system
should be required to arrange for the conduct of a
CPE by the State or a third party approved by the
State.
The IESWTR is scheduled for promulgation in
November 1998, at which time the specific
turbidity requirements and provisions will be
available. EPA will issue detailed guidance at
that time on the relevant technical information
needed to comply with the rule. Both the
LTE1ESWTR and LT2ESWTR are in pre-
developmental stages.
Figure 7-1 also shows the turbidity goal of 0.1 NTU
that was discussed in previous chapters of this
handbook and how regulated turbidity levels are
approaching this long held turbidity goal. This is
not intended to predict that future regulations will
be set at the 0.1 NTU level, but to encourage
plants to pursue the 0.1 NTU performance goals
outlined in this handbook, as a way to assure
regulatory compliance on a combined plant basis.
7.3.2 Removal/In activation Requirements
The original SWTR required water systems to pro-
vide a minimum of 3-log removal/inactivation of
Giardia cysts. State regulatory agencies that
received primacy from USEPA were given broad
latitude in how plants would meet this requirement,
including the option to increase the
removal/inactivation requirements for water sys-
tems that may have higher levels of cysts in their
source water. Rule guidance stated that properly
operating filtration plants could be expected to
remove between 2.0 to 2.5-log of Giardia cysts,
and this removal could be credited against the
3-log requirement. The remaining log removal was
to be achieved with disinfection. Log removal
credits for various disinfectants and operating
conditions were provided in tables of disinfectant
concentration (C) multiplied by the contact time (T).
A major impetus for the IESWTR was that Crypto-
sporidium was not regulated under the original
Figure 7
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-
H 1-
5,
3?
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,E o.s-
0 "
a
u
a
T
'-1. Historic perspective
SDWA(1.0
>
*
Optimized
i
3 ^~ ^
> O> o>
/
of turbidity goal and regulations.
NTU)
SWTR (0.5 NTU)
IESWTR (o.s NTU;
/ "Stag
4//^ LT
Performance Goal (0.1 NTU) /
/^
r-.
I--
I I I I I I I I I V\
O CO CO O> CM U> OO T- ^
CO CO CO CO O> O> O O
T- T- ? T- ? ? T- ° «N
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ESWTR
"Stage 2" DBFs
101
-------
SWTR. This was of concern since chlorine is not
an effective disinfectant against Cryptosporidium,
and the impact of other disinfectants (e.g., ozone,
chlorine dioxide) has not been well established.
The 1997 M-DBP Federal Advisory Committee
recommended adoption of a 2-log Cryptosporidium
removal requirement for all surface water systems
that serve more than 10,000 people and are
required to filter. The committee also recom-
mended that systems which use rapid granular
filtration (direct filtration or conventional filtration
treatment - as currently defined in the SWTR) and
meet strengthened turbidity requirements would be
assumed to achieve at least a 2-log removal of
Cryptosporidium. Systems which use slow sand
filtration and diatomaceous earth filtration and
meet existing SWTR turbidity performance
requirements (less than 1 NTU for the 95th per-
centile or alternative criteria as approved by the
State) also would be assumed to achieve at least a
2-log removal of Cryptosporidium.
The IESWTR is scheduled for promulgation in
November 1998, at which time the specific
removal requirements and provisions will be
available. EPA will issue detailed guidance at
that time on the relevant technical information
needed to comply with the rule. Both the
LTE1ESWTR and LT2ESWTR are in pre-
developmental stages.
7.3.3 DBF Maximum Contaminant Levels
(MCLs)
DBFs were first regulated in 1979 (12) when an
MCL of 0.10 mg/L was established for the sum of
four trihalomethanes (THM), which applied to only
those water systems serving populations >10,000
persons. As discussed above, the purpose of the
M-DBP regulations is to reduce the health risk for
these compounds and other DBFs by promulgation
of disinfectant and disinfectant by-product (D/DBP)
regulations to be implemented in two stages. The
NODA for Stage 1 of the D/DBP rule has lowered
the MCL for THMs and a new MCL has been
added for the sum of five additional compounds
called haloacetic acids (HAA5). The NODA also
contains maximum residual disinfectant levels
(MRDLs) permitted in the distribution system.
Fundamental control procedures for THMs and
HAAs remain essentially the same and include:
• Removal of natural organic matter (NOM),
which are precursors, in the raw water.
• Altering the point of disinfectant addition.
• Reducing the amount of disinfectant used.
(NOTE: This may not be feasible because of
microbial backstop requirements.)
• Switching to alternate disinfectants.
In conventional treatment, NOM is removed by a
coagulation/adsorption mechanism accomplished
by changing the coagulation process to enhance
the removal of these organics. A potential conflict
exists from the standpoint of plant process control
procedures; chemical feed rates found to meet the
optimized turbidity performance goals described in
this handbook may not be compatible with those
needed to meet the DBP performance goals.
Some research has shown, however, that
enhanced coagulation conditions also achieved
excellent turbidity removal in jar tests. Few studies
have evaluated the impacts of enhanced
coagulation on filterability which may be more of a
problem.
Altering the plant's disinfection practices to meet
the DBP MCLs, either through changing the point
of disinfectant addition or lowering the disinfectant
dose, can potentially also lead to other types of
conflicts. When disinfectants are added ahead of
the treatment plant (e.g., pre-chlorination), they
can also provide additional important benefits (e.g.,
enhance the coagulation process for turbidity
removal, enhance iron and manganese control,
etc.) along with meeting the plant's CT
requirements. Lowering pre-disinfection doses to
reduce DBP formation, therefore, could result in
turbidity performance problems or higher levels of
iron and manganese in the finished water. The
major consideration in changing disinfection prac-
tices to control DBPs, however, is to assure that
the change will not result in compliance problems
with state SWTR disinfection and the IESWTR
microbial backstop requirements. The major unit
process evaluation described in Chapter 4
presents disinfection conditions (e.g., chlorine
residual, pH) that are necessary to achieve desired
inactivation levels.
If none of the above process control changes are
sufficient to control DBPs, then the utility may have
to consider alternate disinfection including
102
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ozone, chlorine dioxide, or chloramines. Ozone
and chlorine dioxide will result in major modifica-
tions to the treatment plant and will require the
design and installation of new treatment processes
and equipment. Chloramines, depending on the
plant, may be considered a modification that would
be addressed as part of a CTA.
7.3.4 Enhanced Coagulation Requirements
The Stage 1 DBP regulations proposed in the
NODA for the first time require surface water sys-
tems that use conventional treatment or softening
to remove a specified minimum percentage of the
total organic carbon (TOC) from their raw water
using a process called enhanced coagulation.
TOC removal is required because other DBFs
besides THMs and HAAs are formed when
disinfectants react with a NOM, measured as TOC.
The occurrence and health effects of these
unidentified DBFs are unknown at this time. The
intent of this part of the proposed regulation is to
control the formation of unknown, as well as
known, DBFs by requiring that a minimum
percentage of NOM in the raw water, measured as
TOC, is removed by the plant.
The percentage of TOC removal required is based
on the TOC and alkalinity levels of the plant's raw
water. These TOC removal requirements are
broken down into nine different percent TOC
removal categories. They are presented in a table
for three different alkalinities and raw water TOC
levels.
Plants that cannot meet the specified percent TOC
removals will follow a "Step 2" procedure to
determine what levels of TOC removal are "rea-
sonable and practical" to achieve. The plant uses
this information to request an alternative TOC
removal requirement from its primacy regulatory
agency.
The "Step 2" procedures consist of special jar tests
to determine the maximum percent TOC removal
that they can achieve by incremental increases in
coagulant dose. Coagulant dose is increased in
10 mg/L increments until a specified pH level
(depending on the raw water alkalinity) is achieved.
Residual TOC levels in each jar are then
measured, and an analysis is made of the "point of
diminishing return" (POOR). The POOR is defined
as when a 10 mg/L increase in coagulant does not
decrease the residual TOC by more than 0.3 mg/L.
This percentage TOC removal would then be con
sidered "reasonable and practical" and would be
used in discussions with the primacy agency rela-
tive to giving the plant an alternate enhanced
coagulation requirement.
When a water system meets one of a variety of
conditions it may be exempted from the enhanced
coagulation part of the regulation. It was
recognized that only the humid fraction of the raw
water TOC is amenable to removal by enhanced
coagulation. Plants, therefore, with high levels of
non-humid TOC may not be able to meet any of
the enhanced coagulation removal requirements
and could be exempt from this part of the
regulations. Plants can assess the amount of
humics in their raw water by measuring its specific
UV absorbance or SUVA. SUVA is defined as the
UV absorbance divided by the dissolved organic
carbon (DOC). SUVAs of <3 L/mg-cm represent
largely non-humic materials, and SUVAs in the
4-5 L/mg-cm range are mainly humic. SUVA val-
ues can also be used to request exemption from
the regulations and to determine POOR.
Plants may find that achieving desired TOC
removal will require some significant changes in
plant process control procedures. Enhanced
coagulation typically requires that additional
coagulant and/or acid is added to depress the pH
to a point where the TOC is removed in the
coagulation process. As with control of DBPs,
potential conflicts exist from the standpoint of plant
process control procedures. Chemical feed rates
needed to meet the turbidity performance goals in
this handbook may not be compatible with those
needed for enhanced coagulation.
7.3.5 Microbial Backstop
As discussed above, the Reg-Neg agreement
required that the M-DBP regulations would balance
the risk-risk tradeoffs between control of microbial
contaminants and DBPs. Control of DBPs was not
to result in any decrease in microbial protection.
Since alteration of disinfection practices is one way
of controlling DBPs, major concern was expressed
during the 1997 FACA process regarding reduced
disinfection capability. An approach was needed
to make sure that water systems did not change
disinfection practices to control DBPs and
decrease microbial protection.
The approach that resulted from these discussions
was the microbial backstop. As part of the micro-
bial backstop requirements, water systems will be
103
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required to prepare a disinfection profile when they
approach specified levels of THMs and HAAs. A
disinfection profile is a historical characterization of
the system's disinfection practices over a period of
time using new or "grandfathered" daily monitoring
data. A disinfection profile consists of a
compilation of daily Giardia log inactivation values
based on SWTR CT tables. These calculations will
be based on daily measurements of operational
data (disinfectant residual concentration(s); contact
time(s); temperature(s); and, where necessary,
pH(s)).
The second part of the microbial backstop
requirement is benchmarking, which quantifies the
lower bound of the system's current disinfection
practices. It is intended that water systems take
the results from the profiling and work with the
state regulatory agency to evaluate changes in
disinfection practices which could be used to con-
trol DBFs so that these changes result in no sig-
nificant decreases in microbial protection. Bench-
marking is only required if a PWS intends to make
a significant change to its disinfection practices
such as moving the point of disinfection, changing
disinfectants, changing the disinfection process, or
any changes the state considers significant.
Part of the concern that led to the microbial back-
stop was based on data that showed water plants
with widely varying disinfection levels. Figure 7-2
shows a profile where it is apparent that the plant
was not operating their disinfection systems at any
common baseline. Day-to-day variations above
the state disinfection requirement could be caused
by plants not determining their required CT based
on seasonal changes in water temperature and pH
and/or not having close operational control over
the actual CT provided by the plant. An example
would be not changing the applied disinfectant
dose to respond to changes in the required CT,
disinfectant demand, and/or operating flow. Plants
could also be adding disinfectant for other
treatment issues such as to control Fe, Mn, algae,
and/or taste and odor. The microbial backstop
would require water systems to understand in more
detail how much disinfectant they are applying on
a daily basis, and it would force them to make
rational decisions on why they are adding higher
levels of disinfectant above that required for the
state's disinfection requirements.
7.4 Summary
Water systems pursuing optimization for public
health protection must remain vigilant concerning
the ramifications of new and changing regulations.
Those plants that have met the optimized
performance goals defined in this handbook should
be well positioned to take those regulations in
stride and continue to meet the ever more stringent
challenges facing the water industry.
Figure 7-2. Example of disinfection profile daily variations in log inactivation.
Why the Difference?
•Improper Operational Practices
•Fe and Mn Control
•Taste and Odor
•Algae
State Disinfection Requirement
104
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7.5 References
1. Means, E.G. and S.W. Krasner. February
1993. "D-DBP Regulation: Issues and
Ramifications." Journal AWWA, 85:2:68.
Denver, CO.
2. Pontius, F.W. September 1993. "Reg-
Neg Process Draws to a Close." Journal
AWWA, 85:9:18. Denver, CO.
3. Roberson J.A., J.E. Cromwell, S.W.
Krasner, M.J. McGuire, D.M. Owen, S.
Regli, and R.S. Summers. October 1995.
"The D/DBP Rule: Where did the
Numbers Come From?" Journal AWWA,
87:10:48. Denver, CO.
4. USEPA. July 29, 1994. National Primary
Drinking Water Regulations: Enhanced
Surface Water Treatment Requirements;
Proposed Rule. Fed. Reg., 59:145:38832.
5. USEPA. July 29, 1994. National Primary
Drinking Water Regulations: Disinfectants
and Disinfection By-products; Proposed
Rule. Fed. Reg., 59:145:38668.
6. USEPA. May 14, 1996. National Primary
Drinking Water Regulations: Monitoring
Requirements for Public Drinking Water
Supplies. Fed. Reg., 61:94:24353
7. US Code. August 6, 1996. Title XIV of the
Public Health Service Act (The Safe
Drinking Water Act) as Amended by Public
Law 104-182.
8. USEPA. November 3, 1997. National
Primary Drinking Water Regulations:
Disinfectants and Disinfection By-products;
Notice of Data Availability; Proposed Rule.
Fed. Reg., 62:212:59338.
9. USEPA. November 3, 1997. National
Primary Drinking Water Regulations:
Interim Enhanced Surface Water
Treatment Rule; Notice of Data Availability;
Proposed Rule. Fed. Reg., 62:212:59486.
10. USEPA. December 4, 1975. National
Interim Primary Drinking Water
Regulations. EPA-570/9-76-003.
11. USEPA. June 29, 1989. Filtration and
Disinfection: Turbidity, Giardia lamblia,
Viruses, Legionella, and Heterotrophic
Bacteria; Final Rule. Fed. Reg.,
54:124:27486.
12. USEPA. November 29, 1979. National
Primary Drinking Water Regulations:
Control of Trihalomethanes in Drinking
Water; Final Rule. Fed. Reg.,
44:231:68624.
105
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Chapter 8
Other CCP Considerations
8.1 Introduction
The purposes of this chapter are to present training
requirements for persons wanting to conduct CCP
activities and to identify parameters that can be
used by CCP providers or recipients of CCP
services to assure quality control of the CCP
approach. In addition, a brief discussion is pre-
sented concerning the applicability of the CCP
approach to other optimization and compliance
activities that a utility may be required to achieve
now or in the future.
8.2 Developing CCP Skills
8.2.1 CPE Training Approach
In Chapters 4 and 5 the type of training and expe-
rience necessary to implement CPEs and CTAs
was discussed. In addition to these basic skill
requirements, it has been demonstrated that
hands-on training is very effective for developing
CCP skills in interested parties. For conducting
CPEs, a training approach has been formalized
and demonstrated with several state drinking water
program personnel. The training consists of train-
ees participating in a one-day seminar that pro-
vides instruction and workshop opportunities for
them to become familiar with the CPE terminology
and approach. This seminar is followed by three
actual CPEs where the trainees gain CPE skills
through progressive training that is facilitated by
experienced CPE providers. The roles of the CPE
provider and trainee are described in Table 8-1.
During the first CPE, the trainees are involved in
the data collection and special study activities but
are largely in an observation role during the kick-off
meeting, interview, and exit meeting activities.
Involvement in the remaining two CPEs is gradu-
ally increased such that by the time the third CPE
is conducted the trainees are responsible for all of
the activities. CPE provider observation and
involvement take place only when necessary.
This approach has proven to be very effective in
transferring CPE skills to trainees. Currently, the
training process is scheduled over a four to six-
month period. It is noted that in addition to the
training activities, a quality CPE must be provided
to the water utility. Because of this expectation,
the number of participants that can be trained
while still completing the CPE must be limited to
about four to six people.
8.2.2 CTA Training Approach
Participation in the CPE training, as described in
the previous section, is considered a prerequisite
to participation in CTA training. Training for per-
sonnel to implement CTAs has followed a format
similar to the one used for CPE training. CTA pro-
viders can be used to progressively transfer skills
to trainees through the conduct of actual CTA
activities. The difficulty with this approach is the
fact that the CTA typically occurs over a 6 to 18-
month period. Also, routine telephone contact with
the facility can only be effectively implemented by
one person. The current training approach
consists of CTA provider and trainee involvement
at site visits, with the provider supplying technical
assistance to a designated trainee who maintains
routine contact with the utility personnel. The CTA
provider utilizes telephone calls and exchange of
materials (e.g., telephone memos, operations
guidelines, plant data) to maintain trainee
involvement. Although the approach and time
commitment limit the number of trainees involved,
effective transfer of CTA skills has been achieved.
A key component of CTA training is the emphasis
on providing problem solving and priority setting
capability to the utility staff. Using this approach,
the trainees must learn not to "lead with their
troubleshooting skills" but rather to recognize how
to utilize situations to enhance utility priority setting
and problem solving skills. This does not mean that
CTA providers do not give technical or
administrative guidance when necessary; they only
use these activities when they are absolutely nec-
essary to accomplish the long term transfer of
capability to the utility staff and administration.
107
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Table 8-1. Training Approach to Achieve Transfer of CPE Skills
Training
Activity
CPE Provider Role
Trainee Role
CCP Seminar
(1 day)
• Present CPE seminar
Participate in seminar
First CPE
(3-4 days)
Conduct kick-off meeting
Facilitate data collection
Conduct special studies
Conduct interviews
Facilitate information exchange with team
Prepare exit meeting materials
Conduct exit meeting
Facilitate feedback session with team
Prepare final report
Observe kick-off meeting
Participate in data collection
Participate in special studies
Observe interviews
Review exit meeting materials
Observe exit meeting
Review final report
Second CPE
(3-4 days)
Conduct kick-off meeting
Facilitate data collection
Conduct special studies
Conduct interviews
Facilitate information exchange with team
Finalize exit meeting materials
Facilitate exit meeting
Facilitate feedback session with team
Review draft report
Participate in kick-off meeting
Participate in data collection
Participate in special studies
Participate in interviews
Prepare exit meeting materials
Participate in exit meeting
Prepare final report
Third CPE
(3-4 days)
Observe kick-off meeting
Participate in data collection
Observe special studies
Participate in interviews
Review exit meeting materials
Observe exit meeting
Facilitate feedback session with team
Review draft report
• Conduct kick-off meeting
• Facilitate data collection
• Conduct special studies
• Conduct interviews
• Facilitate information exchange with team
• Prepare exit meeting materials
• Conduct exit meeting
• Prepare final report
8.3 Quality Control
It is important for CCP providers and recipients of
CCPs to be aware of appropriate CCP
applications, expectations of the process, and
maintenance of program integrity. Maintaining the
integrity of the CCP approach can best be
accomplished by following the protocols described
in this handbook. However, to assure effective and
consistent CCP results, quality control
considerations have been developed and are
presented in this section.
8.3.1 CPE Quality Control Guidance
Table 8-2 presents a checklist for CPE providers
and recipients to assess the adequacy of a CPE
relative to the guidance provided in this handbook.
Some of the key areas are discussed in more
detail in this section.
A challenging area for the CPE provider is to main-
tain the focus of the evaluation on performance
(i.e., public health protection). Often, a provider
108
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will tend to identify limitations in a multitude of
areas which may not be related to optimized per-
formance criteria. Typical areas may include poor
plant housekeeping practices, lack of preventive
maintenance, or lack of an operation and mainte-
nance manual. Limitations in these areas are
easily observed and do not challenge the capability
of the operations staff. While they demonstrate a
thoroughness by the provider to identify all issues,
their identification may cause the utility to focus
resources on these areas and to ignore areas
more critical to achievement of optimized
performance goals. The evaluator should be
aware that a utility will have the tendency to take
the CPE results and only address those factors
that are considered relatively easy to correct
without consideration of priority or the inter-
relatedness of the factors.
Table 8-2. Quality Control Checklist for
Completed CPEs
Findings demonstrate emphasis on achievement of
optimized performance goals (i.e., performance
emphasis is evident in the discussion of why prioritized
factors were identified).
Lack of bias associated with the provider's background
in the factors identified (e.g., all design factors
identified by a provider with a design background or
lack of operations or administrative factors identified
by the utility personnel conducting a CPE).
Emphasis in the CPE results to maximize the use of
existing facility capability.
All components of the CPE completed and docu-
mented in a report (i.e., performance assessment,
major unit process evaluation, identification and pri-
oritization of factors, and assessment of CTA appli-
cation).
Less than 15 factors limiting performance identified
(i.e., excessive factors indicates lack of focus for the
utility).
Specific recommendations are not presented in the
CPE report, but rather, clear examples that support the
identification of the factors are summarized.
Identified limitations of operations staff or lack of site
specific guidelines instead of a need for a third party-
prepared operation and maintenance manual.
Findings address administrative, design, operation and
maintenance factors (i.e., results demonstrate
provider's willingness to identify/present all pertinent
factors).
When implementing a CPE, it is important to
understand that specific recommendations involv-
ing plant modifications or day-to-day operational
practices should not be made. For example, direc-
tion on changing coagulants or chemical dosages
is not appropriate during the conduct of a CPE.
There is a strong bias for providers to give specific
recommendations and for recipients to want spe-
cific checklists to implement. CPE providers
should focus their observations during the evalua-
tion on two key areas: 1) identification of factors
limiting the facility from achieving optimized per-
formance goals and 2) provision of specific exam-
ples to support these factors.
Another significant challenge in conducting an
effective CPE is the tendency for providers to iden-
tify limitations that are non-controversial rather
than real factors that may challenge utility person-
nel's roles and responsibilities. For example, it is
often easy to identify a design limitation, since the
utility could not be expected to achieve optimum
performance with inadequate facilities. It is much
more difficult to identify "lack of administrative
support for optimized performance goals" or an
operators' "inability to apply process control con-
cepts" as the causes of poor performance. Failing
to appropriately identify these difficult factors is a
disservice to all parties involved. A common result
of this situation is the utility will address a design
limitation without addressing existing administrative
or operational issues. Ultimately, these
administrative and operational issues remain and
impact the utility's ability to achieve optimized per-
formance. The challenge to properly identify the
true factors can best be achieved by the CPE pro-
vider focusing on the "greater good" (i.e., achieving
sustainable water quality goals). Understanding
this concept allows the CPE provider to present the
true factors, even though they may not be well
received at the exit meeting.
8.3.2 CTA Quality Control Guidance
Table 8-3 presents a checklist for CTA providers
and recipients to assess the quality of a CTA. A
review of the components of the checklist would be
a good way to ensure that the integrity of the CTA
approach has been maintained. Some of the key
components are discussed further in this section.
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Table 8-3. Quality Control Checklist for
Completed CTAs
Plant specific guidelines developed by utility staff.
Demonstrated problem solving skills of utility staff.
Demonstrated priority setting skills of utility admini-
stration and staff.
Tenacity of plant staff to pursue process changes
when optimized performance goals are exceeded (i.e.,
filtered water turbidity begins to increase and
approaches 0.1 NTU).
Utility policy established by administrators to achieve
optimized performance goals.
Demonstrated communication between utility man-
agement and staff.
Training plan that supports front line operators to be
capable of achieving performance goals under all raw
water conditions. For very stable raw water conditions
the training plan should include capability to address
"what if" situations (e.g., avoid complacency).
Adequate staffing or alarm and shut down capability to
ensure continuous compliance with optimized
performance goals.
Adequate funding to support maintaining optimized
performance goals.
Clear direction for utility personnel if optimized per-
formance goals are not achieved.
Trend charts showing unit processes meeting opti-
mized performance objectives over long time periods
despite changes in raw water quality.
Quality control for a CTA is more easily measured
than for a CPE, since the bottom line is achieve-
ment of unit process and plant optimized perform-
ance goals. Consequently, a graphical depiction of
performance results can be used to demonstrate
the CTA endpoint. In some cases the desired per-
formance graph cannot be achieved because of
physical limitations (e.g., a Type 2 unit process
was not able to perform as desired); however, the
utility officials can then proceed with confidence in
addressing the limiting factor.
Some attributes of a successful CTA are subtle
and difficult to measure. However, they ensure
that the integrity of the process is maintained after
the CTA provider is gone. Long term performance
can only be achieved by an administrative and
operations staff that have established water quality
goals and demonstrated a commitment to achieve
them. A successful CTA will result in a tenacious
staff that utilize problem solving and priority setting
skills in their daily routine. Plant staff recognition of
the role that they play in protecting the public
health of their customers can create a strong
professional image. These attributes can often be
difficult to assess, but they are obvious to the utility
personnel and the CTA provider if they have been
developed during the CTA.
One of the most difficult challenges for a CTA
provider and utility personnel is to address the
issue of complacency. Complacency can occur for
all parties if stable raw water quality exists or if
stable performance occurs due to the efforts of a
few key personnel. It is important that a CTA
provider and the utility personnel look beyond the
comfort of existing good performance and develop
skills to address the scenarios that could upset the
current stable situation.
8.4 Total System Optimization
As current and future regulations continue to be
implemented, the challenges facing the water
treatment industry will also expand. One of the
challenges will be the integration of optimizing par-
ticle removal with other, sometimes competing,
optimization goals (e.g., control of disinfection by-
products, corrosion control). The CCP approach
has been successfully applied to wastewater
treatment, water treatment (i.e., microbial protec-
tion), and ozone applications for water treatment
(1,2). Based on this success, it is anticipated that
the CCP approach can be adapted to new drinking
water regulations and associated requirements.
Future areas for optimization, such as watershed
management, balancing disinfection by-product
control with microbial protection, and controlling
water quality in distribution systems, are believed
to be suitable for development utilizing the CCP
approach. This overall approach is called total
system optimization, and the concept is intended to
be developed through additional publications that
will enhance this handbook. Table 8-4 presents a
summary of total system optimization con-
siderations for drinking water utilities.
The USEPA is funding the development of a Cen-
ter for Drinking Water Optimization that will focus
research on the impacts of new regulations on
water treatment plant process control. Results of
this research, coupled with field applications and
110
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Table 8-4. Total System Optimization Considerations for Drinking Water Utilities
Optimization
Area
Performance
Focus
Optimization Activities
Possible Treatment Conflicts
Watershed/
Source Water
Protection
Microbial
Protection
Monitor for sources of microbial
contamination
Develop watershed protection
program
Remove/address known sources
of contamination; develop pollution
prevention partnerships
Develop emergency response
plans
Disinfection By-
products
THMs
HAAs
Bromates
Reduce current level of
prechlorination
Relocate prechlorination to post
sedimentation
Increase TOC removal
Change disinfectant type; change
from chlorine to chloramines for
maintaining residual
Reduction in prechlorination
reduces preoxidation effects and
reduces particle removal
Increased TOC removal increases
sludge production/impacts facilities
Lowering disinfectant residual
causes regrowth
Lowering oxidant level increases
T&O
Lowering disinfectant residual
reduces disinfection capability
Lead and
Copper
Lead and
Copper
Corrosion control; feed corrosion
inhibitor, adjust pH to achieve
stable water
Increased pH levels could reduce
available CT for disinfection
Cryptosporidium
Control
Microbial
Protection
Achieve optimization criteria
defined in Chapter 2
Stop recycle practices
Plant Recycle
Microbial
Protection
Stop recycle to plant; discharge
wastewater to sewer or obtain
permit to discharge to receiving
water
Provide treatment of recycle for
particle removal
Discharge of water treatment
residuals to sewer impacts
wastewater treatment capacity
Distribution
System
Microbial
Protection
Develop monitoring program;
include routine, construction, and
emergency coverage
Maintain minimum disinfectant in
system; consider booster stations,
changing from chlorine to
chloramines; eliminate dead-end
zones
Develop unidirectional flushing
program
Cover treated water storage
reservoirs
Develop storage tank inspection
program, provide vent screens,
routine cleaning procedure
Maintain turnover rate in storage
tanks based on monitoring results
Optimizing storage tank turnover
impacts disinfection capability
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Table 8-4. Total System Optimization Considerations for Drinking Water Utilities (Continued)
Groundwater
Treatment
Microbial
Protection
Eliminate contaminants from
entering wells (i.e., well head
protection program)
Monitor for microbial
contamination
Provide disinfection (e.g.,
establish policy to achieve virus
inactivation, CT)
evaluations, will be used to integrate total system
optimization components with the CCP approach.
8.5 References
1. DeMers, L.D., K.L. Rakness, and B.D. Blank.
1996. Ozone System Energy Optimization
Handbook. AWWARF, Denver, CO and
Electric
Power Research Institute Community Environ-
mental Center, St. Louis, MO.
2. Hegg, B.A., L.D. DeMers, and J.B. Barber.
1989. Handbook: Retrofitting POTWs.
EPA/625/6-89/020, USEPA Center for Envi-
ronmental Research Information, Cincinnati,
OH.
112
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Appendices
NOTE
Appendix A has been completely revised. Original
pages 115 thru 122 have been deleted and replaced by
pages 115-1 thru 115-14.
Appendix B begins on page 123.
113
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Appendix A
Optimization Assessment Spreadsheet (OAS) Instructions
Overview:
The OAS was originally developed by Process Applications, Inc. to assess potential
improvements to water treatment plant performance using the CCP. Since that time the
spreadsheet has been adapted to assist plant staff in collecting and using turbidity data to
determine where they stand with respect to consistently meeting the optimization goals
shown in Table A-l.
These instructions mainly explain the features of the spreadsheet and the elements of the
reports. Some examples, however, on how to use the OAS for interpreting possible
performance limiting factors at specific plants are also provided.
The OAS consists of several different worksheets displayed as tabs at the bottom of the
OAS workbook. Each tab presents options for data entry and reports generated by the
spreadsheet after data entry.
Table A-l. Optimized Performance Goals
Individual Sedimentation Basin Performance Goals
Settled water turbidity less than 1.0 NTU 95 percent of the time when raw water turbidity is
less than or equal to 10 NTU
Settled water turbidity less than 2.0 NTU 95 percent of the time when raw water turbidity is
greater than 10 NTU
Individual Filter Performance Goals
! Filtered water turbidity less than 0.10 NTU 95 percent of the time based on the maximum
filter effluent turbidity for each day excluding the 15 minute period after bringing the filter
on line (for plants without filter-to-waste capability)
! Maximum filtered water measurement of 0.30 NTU
Combined Filter Performance Goal
Combined filter effluent turbidity of less than 0.10 NTU 95 percent of the time
115-1
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Data Required for OAS
The OAS uses the plant's turbidity performance data and works with a year's worth of data at
a time. The spreadsheet also includes provisions for multiple year assessments that are
discussed later. The OAS can be used to assess a year of data or the plant's progress towards
achieving optimized performance can be tracked by entering plant data daily throughout the
year. The recommended way to populate the spreadsheet requires entering maximum daily
values for the following parameters:
< Raw water turbidity.
< Settled water turbidity of each sedimentation basin, (up to 4 basins)
< Filtered water turbidity of each filter, (up to 12 filters)
< Combined filter effluent
A maximum value for the day for each of these parameters is entered into the spreadsheet.
For example, if the plant recorded a sedimentation basin effluent every 4 hours during the day,
they would take the maximum value from the 6 readings and enter that value into the
spreadsheet.
Table A-2. presents monitoring guidelines for these process streams.
Table A-2. Monitoring Guidelines
Process Stream
Raw Water
Individual Sedimentation Basins
Individual Filter Effluents
Combined Filter Effluents
Monitoring Guidelines
Daily raw water turbidity
Settled water turbidity at 4-hour intervals
From each sedimentation basin
On-line (continuous) turbidity from each filter
Combined filter effluent at
4-hour time increments
OAS Data Entry Requirements
The OAS can handle a maximum of 366 daily data points for raw water, four different
sedimentation basins, 12 filters, and the combined filter effluent. Those plants with more
treatment processes requires creation of another OAS file to track the performance of these
additional basins or the plant can choose to only include those basins with the worst
performance. Most plants chose to create a separate OAS for each year instead of trying to
keep a running year of data on one spreadsheet. Some plants, however prefer to keep a
running year data and transfer the last quarter of data from the previous year into a new OAS.
This will require some care in setting up the new OAS in this way. Data entry is handled in
two separate ways with two different worksheets provided, accessed through by tabs at the
115-2
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bottom of the workbook. NOTE: The proper worksheet must be used for the different
types of data entry.
Data Entry Paste Worksheet
The "DataEntryPaste" worksheet is only used to populate the spreadsheet with
electronic data. Figure A-l. shows the "DataEntryPaste" worksheet for a plant with
one sedimentation basin and five filters. This data has been electronically transferred to
the OAS. Once all the data is copied into the worksheet, clicking on the green
"TRANSFER" button activates a macro that converts the data to a standard format and
creates a data base. This database serves as the basis for the various reports in the OAS.
The red "CLEAR" button clears the data entry area prior to electronically transferring a
new data set into the worksheet.
Data Entry Values Worksheet
The "DataEntryValues" worksheet is only used for data entry when plant data is
entered by hand. This worksheet also displays the database created when data is
entered into the "DataEntryPaste" worksheet (Figure A-l.) and after activation of the
"TRANSFER" button. Figure A-2. shows the "DataEntryValues" worksheet generated
that becomes the basis for the other worksheets showing different plant performance
summary reports NOTE: When using the "TRANSFER" macro, all data in the
"Data Entry Values" worksheet is replaced.
At the top of the "DataEntryValues" worksheet, the plant's name and Public Water
System (PWS) identification number are entered along with information on the
performance goals against which the plant would like their data assessed including the
regulatory requirements. This plant chose 2.0 NTU for the sedimentation basins and
0.1 NTU for the filters and a regulatory requirement of 0.3 NTU. Use of the optimized
performance goals in Table A-l. is recommended, but the plant has the option to enter
other values for the performance goals.
After entering the value for the different performance goals, the OAS highlights, in
yellow, those values that exceed the selected goals. Figure 2. which shows that, for the
month of data shown, the sedimentation basin did not achieve the performance goal of
2.0 NTU on 1 /17/2002 and that filters 1,4 and 5 did not meet the 0.1 NTU filtered
water goal.
Once the performance goals are entered on the "DataEntryValues" worksheet, activating
the green "UPDATE" button creates a series of worksheets summarizing the data in
different ways. Activating the red "CLEAR" button removes all of the data from the
spreadsheet so that it can be used for another data set. NOTE: Every time new data is
entered in the OAS, the "UPDATE" button must be activated to generate updated
summary reports.
115-3
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OAS Summary Reports
After activating the "UPDATE" button, the macros in the spreadsheet create a series of
reports. A series of tabs across the bottom of the workbook identify the different
worksheets that contain the different reports. The following summarizes each of the
reports generated by the OAS.
Summary Worksheet
The "Summary" worksheet, shown in Figure A-3., presents the "Treatment Barrier
Performance Summary", which consists of four parts. The upper left section
contains the "Turbidity Profile" with trend plots of the log of the turbidity values for
raw, max sed, max filtered, and combined. The max sed and max filtered represent
the maximum value of all of the sedimentation basins and filters for that day. If on a
particular day filter 1 had the highest maximum, that would be the max filtered and
plotted on this graph. The log scale of the turbidity values allows presentation of all
the treatment process performance data on the same graph for determining if
variations in raw water turbidity pass through the different treatment processes.
The right side of the worksheet provides the next two parts where two trend graphs
are provided; "Maximum Daily Settled Water Turbidity" and "Maximum Daily
Filtered Water Turbidity." These show how the plant's max sed, max filtered, and
combined turbidities compare against the selected performance goals.
Finally at the lower left of the worksheet is a data summary table that provides some
statistics on the data. The table presents the maximum, minimum, and average for
all of the data along with the 95th percentile value. RSQ provides a correlation
between the raw, settled, filtered, and combined turbidities. The settled data is
correlated with the raw while the filtered and combined are correlated with the
settled. A high RSQ may indicate that the turbidity spikes are passing through the
treatment processes. Based on experience with this parameter, a coefficient above
about 0.25 indicates that turbidity pass-through may be occurring in a process (Note:
This correlation does not work between settled and filter water if the plant has
achieved very stable performance). The last two columns of the table present the
percent of time that the data met the selected performance goals. Note that the OAS
calculates the 95th percentile values using daily maximum values and not all the 4-
hour discrete readings required by the regulations. Because of this, the 95
th
th
percentile values in the OAS do not equate to the 95 percentiles reported to the state
for determination of regulatory compliance.
Optimization Trend Worksheet
Figure A-4. shows the "Optimization Trend" worksheet that contains the
"Optimization Trend Report" consisting of three sections. A table across the top of
the worksheet contains a summary of the unit treatment process performance data by
115-4
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month. This worksheet shows the 95 percentile values calculated for the individual
sedimentation and filtration processes and the percent of monthly values meeting
specific performance goals. Calculation of the percentile for sedimentation uses the
data for all the individual sedimentation basins while the calculation of the filtered
water percentile uses the combined filtered water data. Charts located on the lower
part of the report also plot these data.
For each month, the worksheet highlights in red the sedimentation basin and filter
with the highest turbidity value. Since the example plant has only one sedimentation
basin all of the monthly values are red. For the month of June, however, filter 4 at
this plant had the highest turbidity of all the filters (0.21 NTU). A closer inspection
of the data for all of the filters shows that the range of values for all five filters was
essentially the same. Looking at filter 4 one can see that it had the highest turbidity
for five of the 12 months with three months above 0.2 NTU. In addition, one can see
at the bottom of the table that Filter 4 met the goal of 0.10 NTU, only 83% of the
time, compared to 93.7%, 89.3%, 92.9%, and 87.7% for Filters 1, 2, 3, and 5,
respectively. Filter 4 also had the highest 95th percentile over the entire year (0.17
NTU) of all of the 5 filters. To optimize this plant the plant staff may try and
determine if there are reasons for this filter consistently having the highest turbidity.
The "Optimization Trend Report" contains two trend graphs across the bottom with
the "Settled Water Optimization Trend" on the left and the "Filtered Water
Optimization Trend" on the right. Each of these graphs trend the same two sets of
data; one related to the sedimentation basins and the other for the filters.
The most prevalent feature of these graphs is the various colored areas that are
layered on top of each other. For each month, all of the data for the respective
treatment process are sorted and placed into four categories; For the sedimentation
basins the categories are >3 NTU, <3 NTU, <2 NTU and <1 NTU. For the filters the
categories are >0.3 NTU, <0.3 NTU, <0.2 NTU and <0.1 NTU. The percent of time
the data for that month is in each of the four categories is then plotted using the
vertical axis on the left. Each category is plotted as a separate area on the chart so
that the 0.1 NTU data (and then 0.2 NTU data, etc.) is on top of the other categories.
Looking at the "settled water optimization trends" graph, in January 2002 the settled
water was <1 NTU 61% of time, <2 NTU 84% of time and <3 NTU 100% of the
time. Since none of the data was >3 NTU (the plant met < 3 NTUI100% of the time
in January), there is no white area showing in January. In April the plant met <3
NTU only 96.67% of the time; therefore, there is a small white area showing in
April.
Though these trend graphs appear confusing at first, their main purpose is to allow
the plant to quickly see how the plant performs throughout the year with respect to
the optimization goals. There is a tendency to try and read more into them than is
necessary. In looking at these graphs it is important to notice how much of the graph
is covered with the layer representing the highest level of performance. In the
"Settled Water Optimization Trends" graph the plant was almost completely
115-5
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optimized in November, but had less than optimum performance in August. It is also
important to look at the trend in the different layers. Between September and
November the performance of the sedimentation basins greatly improved. Between,
July and September, however, there were problems with the sedimentation basin
performance. The plant staff can use this information to assess changes in the plant
during these time periods to determine and what results in the best performance.
These graphs also have a solid line that plots the 95% value each month, shown on
the right vertical axis, for the sedimentation basins and filters. The intent of the
trend line is to allow the plant to observe if the performance is improving based on
the slope of the line. If the line is sloping downward, then performance is
improving. If it is sloping upward, then the changes in the plant are taking the
performance in the wrong direction.
Other Summary Worksheets
The OAS also contains several other worksheets that provide graphical presentation
of the performance data. Most of these are trend graphs of the performance of the
individual treatment units. Up to four individual processes are shown on a single
worksheet. Figures A-5 and A-6 show the "SedSum" and "FilterSum (1-4)"
worksheets.
The remaining worksheets present single versions of some of the graphs on the
"Summary" and "Optimization Trend" worksheets.
Long Term Trends Worksheet
The OAS only allows the analysis of one year of data at a time. Optimization of a
treatment plant, however, occurs over several years and looking at trends between
the different years can be beneficial. There is a separate long term trends spreadsheet
that will allow development of the settled and filtered water optimization trend
charts for a three year period. The last tab on the OAS is the "LT-Trend" worksheet
which generates a table of data (shown in Figure A-7.) that can be copied into the
long-term trends spreadsheet. Figure A-8. shows the output of the long term trends
spreadsheet.
115-6
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Figure A-l. Data Entry Paste Worksheet
?< Microsoft Excel - OAS Instructions Example 2. Turb-opt27
File Edit View Insert Format Tools Data Window Help
II D
Home3
Instruction to users: Paste plant turbiditg data sets into the data entrj area belov. The
data entrj area will hold 366 da§s of data. Following data input, transfer data to the
database b§ clicking on the data TRANSFER button. Go to the DataEntrjValues
worksheet to enter the plant name and performance goals.
Click of this button to TRANSFER the
data to the database
Click on this Button to CLEAR the data from
the data entry area below
Data Entry Area for Posting Data Sets
Raw jSedl |Sed2 |Sed3 I Sed 4 I Filter 1 I Filter £ I Filter 3 [Filter 4 I Filter 5 I Filter 6 I Filter 7 I Filter 8 I Filter 9 I Filter 10 | Filter 11 I Filter 12 I Combined
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72.00
273.00
650.00
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155.00
110.00
140.00
127.00
205.00
133.00
102.00
403.00
294.00
128.00
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0.61
0.61
O.S5
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0.63
0.65
0.30
0.97
0.73
0.30
0.72
0.83
0.69
1.10
2.10
0.44
0.82
2.30
0.83
0.73
1.10
1.60
2.40
2.00
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1.40
2.50
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1.10
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115-7
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Figure A-2. Data Entry Values Worksheet
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B H 1 J K L
XYZ Vater Treatment Plant "_
1
2.0 ^
0.10 ^
0.30 ^
Click on
Instruction to users: Input plant name and turbiditg goals above. Input start date
and turbiditg data below. The database will hold 366 dags of data. The turbiditg data
entrg cells will turn gellow if the value exceeds the process goal. Following data
input, develop the reports bg clicking the UPDATE button.
Area
Raw
:3 h:
7.4
7.5
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5.7
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0.07
0.03
0.03
0.07
0.03
0.06
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0.06
0.06
0.07
0.06
0.13
0.05
0.06
0.06
0.06
0.06
0.07
0.08
0.06
0.07
0.08
0.08
0.18
0.09
0.07
0.07
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0.12
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115-8
-------
Figure A-3. Treatment Barrier Performance Summary Worksheet
XYZ Water Treatment Plant
Treatment Barrier Performance Summary
Turbidity Profile
— Raw Max Seel Max Filter —Combined
^^
Jan-02 Frfj-02 Mar-O2 A|*-02 May-O2 Jun-02 Jul-02 Aug-02 Srf)2 Dec-02
Optimization A^iiesiiment Software - Version 27
115-9
-------
Figure A-4. Optimization Trend Worksheet
XYZ Water Treatment Plant
Optimization Trend Report
Settled Water Turbidity
95th I:-,. ..:,i,\.- V ,;,,,.-. (NTU) % Values Meeting Goal
Sed 2 Sed 3 Sed 4 » NTU 2 NTU I NTU
Filtered Water Turbidity
95th Percentile Values (NTU)
Filler* Fillers Filters Filter 7 Filter a Filter^ I Filter 10 Fitter 11 Flll«r12 Combined
% Values Meetin
O.S 0.2
Worst Filter
For Month
Highest Values
All Filters
Settled Water optimization Trends
Filtered Water Optimization Trends
NTU SB2NTU E2 1 NTU 96th Percerilile
Performance
Problems
95% Trend Line
Optimization Assessment Software - Version 27
115-10
-------
Figure A-5. Other Summary Worksheet - Sedimentation
Sedimentation Performance Summary
Sedimentation Basin 1
10.0
= 8.0
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2.0
0.0
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-------
Figure A-6. Other Summary Worksheet - Filtration
Filter 1
0.50
Filter 3
0.50
0.50
£- 0.40
o.so
0.00
Filter 2
Filter 4
999
CN CN CN CN Cn
CD O O O O
& £ S 8 i
CTl O 2 Q ^
115-12
-------
Figure A-7. Long Term Trend Worksheet Data Table
Month/Yr
Jan-02
Feb-02
Mar-02
Apr-02
May-02
Jun-02
Jul-02
Aug-02
Sep-02
Oct-02
Nov-02
Dec-02
Settled Water
95th %
Sed1
2.45
1.92
1.60
2.56
1.65
1.30
1.40
2.10
2.06
1.40
0.94
0.93
% Values Meeting Goal
3NTLJ
100.0
100.0
100.0
96.7
100.0
100.0
100.0
96.8
100.0
100.0
100.0
100.0
2NTU
1 NTU
83.9
92.9
100.0
80.0
96.8
100.0
100.0
93.5
93.3
100.0
100.0
100.0
61.3
57.1
61.3
36.7
45.2
63.3
71.0
51.6
26.7
54.8
100.0
96.8
Combined Filtered Water
95th %
0.13
0.08
0.13
0.12
0.17
0.12
0.15
0.15
0.09
0.13
0.11
0.09
% Values Meeting Goal
0.3 NTU
0.2 NTU
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
96.8
96.8
100.0
100.0
100.0
100.0
0.1 NTU
77.4
96.4
74.2
86.7
77.4
83.3
80.6
87.1
96.7
87.1
93.3
100.0
The area in blue can be copied to the long-term trend spreadsheet (LT_trend.xls) to develop up to three years of performance trends.
115-13
-------
Figure A-8. Long Term Trend Spreadsheet Output
Plant Name
PWS#
XYZ Water Treatment Plant
Settled Water Long Term Trends
I 3 NTU 2 NTU 1 NTU - 95th % (read on right axis)
10.3 NTU
Combined Filtered Water Long Term Trends
a 0.2 NTU : 0.1 NTU - 95th % (read on riaht axis)
115-14
-------
Appendix B
Drinking Water Treatment Plant (DWTP) Advisor Software
Development of the DWTP Advisor
The DWTP Advisor is a computer software appli-
cation designed as an "expert system" to provide
assistance in the evaluation of drinking water
treatment plants. The program was based on the
source document Interim Handbook: Optimizing
Water Treatment Plant Performance Using the
Composite Correction Program Approach (1). The
Interim Handbook is the predecessor document to
this handbook, of which this appendix is a part. The
software was developed to assist personnel
responsible for improving the performance of existing
water treatment plants in order to achieve compliance
with the 1989 SWTR.
The system consists of two major components:
Major Unit Process Evaluation and Performance
Limiting Factors. These two component parts were
designed to work together. The evaluator, therefore,
cannot choose to use only one of the program's
components. In addition, the evaluator cannot modify
the loading values, some of which are currently
outdated. The software leads the evaluator through a
series of questions and provides responses based on
the experience and judgment of a group of experts
that were used to delineate the logic for the program.
The complexity of the multiple interrelated factors
limiting performance and the uniqueness of individual
plants makes production of an expert system with
broad scale application difficult. This coupled with the
fact that the program has not been updated for sev-
eral years, should make persons considering use of
the software aware of these inherent limitations.
Even though an expert system like the DWTP Advisor
would theoretically have many uses, its current level
of development limits its usefulness in conducting
CPEs. Persons familiar with the fundamental CCP
concepts and who understand the limitations of the
software, however, may find it a useful tool.
Technical Information
Hardware Requirements
The DWTP Advisor requires an IBM AT or compatible
computer with the following components:
• A hard disk with at least 5.0 megabytes of free
space
• At least 640 Kbytes of RAM (560,000 bytes user-
available)
• A high density floppy disk drive (5.25" 1.2 MB or
3.5" 1.4 MB)
• DOS version 3.0 or higher
• A printer (EPSON compatible) configured as
system device PRN (optional)
If you installed the DWTP Advisor, but are unable to
run the program, you may need to check your
computer's memory configuration. Although your
computer may have the minimum memory required,
memory resident programs may use some of this
memory. "User-available" memory is the amount of
memory remaining after the operating system and
memory resident programs are loaded. If memory
resident programs are installed and adequate
memory is not available for the DWTP Advisor, an
error message will appear on the screen when you
attempt to run the program. If this occurs, memory
resident programs should be disabled (e.g., by editing
your computer's configuration files, config.sys and
autoexec.bat) and your computer rebooted before
running the system. To check the status of your
computer's disk and available memory, run the MS-
DOS CHKDSK program by typing CHKDSK and
pressing . For more information, see the MS-
DOS manual that came with your computer or consult
your PC support staff.
Software Specifications
The DWTP Advisor has been developed using sev-
eral commercially available software tools. The
system interface was developed using Turbo Pascal
6. The "reasoning" or evaluating portion of the
system uses the expert system shell 1ST Class. The
system also consists of data files in dBase.dbf format.
123
-------
Contents of the System
The DWTP Advisor package includes one double-
sided, high density disk and complete User Docu-
mentation.
A copy of the Water Advisor Software may be
obtained by contacting:
ORD Publications (G-72)
26 West Martin Luther King Drive
U. S. Environmental Protection Agency
Cincinnati, Ohio 45268-1072
Telephone: 513-569-7562
Fax:513-569-7566
Ask for: Drinking Water Treatment Plant
Advisor Software: 625/R-96/02
124
-------
Appendix C
Major Unit Process Capability Evaluation
Performance Potential Graph Spreadsheet Tool
for the Partnership for Safe Water
Section 1 Background on the Major Unit Process Capability Evaluation
Section 2 The Performance Potential Graph Spreadsheet Tool
Section 3 Selecting the Appropriate Spreadsheet for Your Application
Section 4 Loading the Spreadsheet
Section 5 Entering Plant Information/Data
Section 6 Printing Spreadsheet Output
Section 7 Important Rules to Remember When Using the Performance Potential Graph
Spreadsheet Tool
Figure C-1 Example performance potential graph output for LOTUS 123 files.
Figure C-2 Example performance potential graph output for EXCEL and QUATTRO
PRO files.
Figure C-3 Example performance potential graph data entry section for all files.
Figure C-4 Performance potential graph data entry guide.
Table C-1 Various Software Spreadsheets - The Designations for Performance Potential Graph
Table C-2 Major Unit Process Evaluation Criteria
125
-------
Section 1 - Background on the Major Unit
Process Capability Evaluation
Water treatment plants are designed to take a raw
water source of variable quality and produce a
consistent, high quality finished water using multiple
treatment processes in series to remove turbidity and
prevent microbial contaminants from entering the
finished water. Each treatment process represents a
barrier to prevent the passage of microbial
contaminants and particulates in the plant. By
providing multiple barriers, any microorganisms
passing one unit process can possibly be removed in
the next, minimizing the likelihood of microorganisms
passing through the entire treatment system and
surviving in water supplied to the public.
The performance potential graph (see Figures C-1
and C-2) is used to characterize capabilities of
individual treatment processes to continuously
function as a barrier for removing particulates and
harmful pathogens. Each of the major unit processes
is assessed with respect to its capability to
consistently contribute to an overall plant treated
water quality of less than 0.1 NTU turbidity during
peak flows. Specific considerations are given only to
process basin size and capability under optimum
conditions. Limitations in process capability due to
minor deficiencies or incorrect operation (e.g.,
degraded baffles which allow short-circuiting or
improper process control) do not contribute to
development of the performance potential graph.
These operational or minor modification limitations
are addressed during the evaluation of the other
aspects of the treatment plant conducted as part of
the Partnership for Safe Water self-assessment
procedures.
Specific performance goals for the flocculation,
sedimentation, filtration, and disinfection unit
processes are used when developing the perform-
ance potential graph. These include settled water tur-
bidities of less than 2 NTU and filtered effluent
turbidities of less than 0.1 NTU. Capabilities of the
disinfection process are assessed based on the CT
values outlined in a USEPA guidance manual for
meeting filtration and disinfection requirements.
Rated capacities are determined for each of the unit
processes based on industry standard loading rates
and detention times with demonstrated capability to
achieve specific unit process performance goals.
These evaluation criteria are defined in Table C-2 of
this appendix. The resulting unit process rated
capacities are compared to
the peak instantaneous operating flow for the
treatment plant. Any unit process rated capacities
which do not exceed the plant's peak instantaneous
operating flow are suspect in their ability to
consistently meet desired performance goals that will
maximize protection against the passage of microbial
contaminants through the treatment plant. Specific
interpretation of the results of the performance
potential graph are discussed in Section 3 of the
Partnership for Safe Water self-assessment
procedures. It is important that the
Figure C-1. Example performance potential graph
spreadsheet output for LOTUS 123 releases.
Major Unit Process Evaluation
Performance Potential Graph
Row (MGD)
2.5
7.5 10 12.5 15 17.5 20
Unit Processes:
Flocculation
Sedimentation
Filtration
Disinfection
Pre & Post
Post Only
1 1 1 I 1
9.60
14.04 |
18.82
16.82
8.98
1 1 1
^14.5 MGD
I
Figure C-2. Example performance potential graph
spreadsheet output for EXCEL and QUATTRO
PRO releases.
Major Unit Process Evaluation
Performance Potential Graph
22.5
20
17.5
15
12.5
10
7.5
5
2.5
0
Flocculation Sedimentation nitration Disinfection: Pre & Post Post Only
Unit Processes
126
-------
evaluator recognize that the guidance provided by this
computer software should not exceed the evaluators'
judgement in projecting unit process capability.
Options to change loading rate projections to values
different from those provided are available and should
be considered if data or the evaluators' experience
justifies the modification.
Section 2 - The Performance Potential
Graph Spreadsheet Tool
Spreadsheets have been generated to assist Utility
Partners in creating the performance potential graph
required for Section 3 for use in the Partnership for
Safe Water self-assessment procedures. Generating
the performance potential graph requires opening the
appropriate spreadsheet file and entering specific
physical plant information in the defined cells (see
Figure C-4). A performance potential graph will be
generated automatically. Rated capacities for each
unit process are generated from user-defined criteria
as well as from criteria defined in Table C-2 and dis-
cussed in Section 3 of the Partnership for Safe Water
self-assessment procedures. The user may print a
hard copy of the performance potential graph by
following steps defined in Section 6 of this appendix.
Users requiring expanded instructions for entering
appropriate information in the spreadsheet cells
should refer to Figure C-3. Should users require
additional assistance in preparing a performance
potential graph using the spreadsheet, please contact
Eric Bissonette of USEPA/OGWDW Technical
Support Division at (513) 569-7933.
Section 3 - Selecting the Appropriate
Spreadsheet for Your Application
Performance Potential Graph Spreadsheets have
been developed in LOTUS 123 Release 2.4 for DOS
and 5.0 for WINDOWS, EXCEL Release 4.0 and 5.0
for WINDOWS, and QUATTRO PRO Release 5.0 for
WINDOWS software systems. Select the files
corresponding to your application and data entry
needs from Table C-1 and proceed to Section 4.
Table C-1. File Designations for Various Software
Spreadsheets - Performance Potential Graph
Performance
Potential
Graphs
Working Files
External
Format Files
for DOS
LOTUS
1232.4
PPG.WK1
PPG.FMT
for WINDOWS
LOTUS 123
5.0
PPG.WK4
None
EXCEL 4.0 or
5.0
PPGXLC-XLS
None
QUATTRO
PRO 5.0
PPGQP.WB1
None
Section 4 - Loading the Spreadsheet
• Copy the required working file and external
format file from the Master Diskette to a directory
resident on the hard drive of your computer. Do
NOT work from the files contained on the Master
Diskette.
• Enter your spreadsheet software by selecting the
appropriate icon or menu option (e.g., click on the
LOTUS 123 Release 5.0 icon). (Note:
WYSIWYG needs to be invoked for the LOTUS
123 Release 2.4 spreadsheets.)
• Open the working file as specified in Section 3
and save the file under a new file name.
Section 5 - Entering Plant Information
Each spreadsheet contains a data entry section and a
chart which depicts the resulting individual unit
process rated capacities. The LOTUS 123
spreadsheets generate a performance potential graph
with the unit process rated capacities characterized
by horizontal bars (see Figure C-1). Contrarily, the
EXCEL and QUATTRO PRO performance potential
graphs characterize the unit process capacities by
vertical bars (see Figure C-2). The data entry
sections are identical for the LOTUS 123, EXCEL,
and QUATTRO PRO performance potential graph
files (see Figure C-3).
• Begin entering appropriate physical plant data in
cells B31..B71 and E32..E69. Figure C-4
contains in-depth description of the acceptable
entries for each of the cells in the spreadsheet.
• The entered physical plant data will appear in
blue. Cells containing black values are calculated
from data entered in other cells and cannot be
modified.
127
-------
Figure C-3. Performance potential graph data entry guide.
Peak Instantaneous Flow What is the peak flow in MGD at any instant through the treatment plant? This peak flow is based on historical records and pumping capacity.
(See Section 3 of the Self-Assessment for further discussion.)
Predisinfection
Presedi mentation
Presed. Basin Volume
Presed. Basin Baffling
Predisinfection Practiced
Temperature (°C)
pH
Predisinf. Residual (mg/L)
Predisinf. Application Point
Required CT
Predisinfection Volume
Effective Predisinf. Volume
Flocculation
Basin Volume
Temperature (°C)
Mixing Stages
Suggested
Assigned
Rated Capacity
Sedimentation
Basin Volume
Surface Area
Basin Depth
Operation Mode
Process Type
Tubes Present
Detention Time
Does the plant have and utilize a presedi mentation basin? Enter Yes or No.
What is the volume (in gallons) of the presedi mentation basin(s)?
What is the baffling condition of the presedi mentation basin(s)? Unbaffled Poor Average Superior impacts effective volume calculation regarding
predisinfection contact time based on estimated T10 to T ratios.
Does the plant apply a disinfectant prior to the clearwell? Enter Yes or No.
What is the coldest water temperature (in degrees Celsius) at the predisinfectant application point?
What is the maximum pH at the predisinfectant application point?
What is the maximum predisinfectant residual (in mg/L)?
Where is the predisinfectant applied? Prior to the presedi mentation or flocculation or sedimentation or filtration unit processes?
Using the predisinfection operating conditions (pH and Temp and required log removals), obtain the required CT value from Appendix C
of the Surface Water Treatment Rule Guidance Manual or Appendix A of the CCP Handbook.
Calculated from data entered in other areas. No entry is required here.
Calculated from data entered in other areas. Incorporates effective contact of the disinfectant based on baffling in each of the unit processes.
What is the total volume (in gallons) of the flocculation basin(s)?
What is the coldest water temperature (in Celsius) that the flocculation basin experiences?
Describe the stages contained within the flocculation basin(s). Single or Multiple? No baffling or interbasin compartments equals
single-staged. All other conditions equal multiple-staged.
Suggested detention time calculated using above information from existing conditions (see Attachment 2). No entry is required here.
Enter a detention time (in minutes). Use the suggested detention time or select one based on site-specific circumstances.
This is the rated capacity of the unit process (in MGD) calculated from the Assigned hydraulic detention time. No entry is required here.
This volume is calculated from other entered data. No entry is required here.
What is the total area (in square feet) of the sedimentation basin(s)?
What is the average depth (in feet) of the sedimentation basin(s)?
Enter Turbidity or Softening, depending on the process used. Is the process operated mainly to remove turbidity or to provide softening?
What settling process is utilized? Enter Rectangular/Circular/Contact/Lamella Plates/Adsorption Clarifier or SuperPulsator.
What type of settling tubes is present in the sedimentation basin(s)? Enter None or Vertical (>45°) or Horizontal (<45°).
128
-------
Figure C-3. Performance potential graph data entry guide (continued).
Process SOR
Suggested
Assigned
Rated Capacity
Filtration
Total Filter Surface Area
Total Number of Filters
Filters Typically in Service
Total Volume Above Filters
Media Type
Operation Mode
Raw Turbidity
Air Binding
Loading Rate
Suggested
Assigned
Rated Capacity
Disinfection
Clean/veil Volume
Effective Baffling
Temperature (°C)
pH
Disinfectant Residual (mg/L)
Required Log Inactivation
Reqd. Disinfection Log Inactivation
Pipe Distance to First User
Pipe Diameter
Suggested surface overflow rate calculated using above information from existing conditions (see Attachment 2). No entry is required here.
Enter a surface overflow rate (SOR) (in gpm/ft2). Use the suggested SOR or select one based on site-specific circumstances.
This is the rated capacity of the unit process (in MGD) calculated from the Assigned surface overflow rate. No entry is required.
What is the total surface area (in square feet) of the filter(s)?
What is the total number of filters in the treatment plant?
What number of filters are typically in service?
What is the total volume of water above the filter media (in gallons)?
What media configuration is present in the filters? Enter Sand, Dual, Mixed, Deep Bed.
How are the filters operated? Enter Conventional Direct, Inline Direct.
What is the yearly 95th percentile raw water turbidity value? Refer to the raw water turbidity spreadsheet output table.
What level of air binding is noticeable in the filter(s)? Enter None, Moderate, High.
Suggested filter loading rate calculated using above information from existing conditions (see Attachment 2). No entry is required here.
Enter a filter loading rate (in gpm/ft2). Use the suggested rate or select one based on site-specific circumstances.
This is the rated capacity of the unit process (in MGD) calculated from the Assigned filter loading rate. No entry is required here.
What is the total volume (in gallons) of the clearwell(s)?
What is the baffling condition of the clearwell(s)? Enter Unbaffled, Poor, Average, Superior. Impacts effective volume calculation
regarding disinfection contact time.
What is the temperature (in degrees Celsius) at the disinfectant application point?
What is the pH at the disinfectant application point?
What is the maximum disinfectant residual (in mg/L)?
Enter the total number of log removals required for the plant. Enter 3 or 4 or >4 (must be a numeric value).
Required disinfection log removals calculated from other data. No entry is required here.
What is the transmission distance (in feet) to the first user/customer?
What is the pipe diameter (in inches) of the transmission pipe?
129
-------
Required CT
Using the disinfection operating conditions (pH and Temp and required log removal), obtain the required CT value from Appendix C
of the Surface Water Treatment Rule Guidance Manual of Appendix A of the Composite Correction Program Handbook
Effective Contact Volume
Suggested
Assigned
Post Disinfection Rated Capacity
Pre & Post Disinf. Rated Capacity
Detention Time
Calculated from data entered in other areas. No entry is required here.
Suggested detention time calculated using above information from existing conditions (see attachment 2). No entry is required here.
Enter a detention time (in minutes). Use the suggested detention time or select one based on site specific circumstances.
This is the rated capacity of the unit process (MGD) calculated from the Assigned detention time and required CTs
No entry is required here.
This is the rated capacity of the unit process (MGD) calculated from the Assigned detention time and required CTs
No entry is required here.
130
-------
Figure C-4. Example performance potential graph data
Plant Name
Peak Instantaneous Flow
Predisinfection/Pre.
Basin Type
Basin Volume
Basin Baffling
Disinfectant Applied
Temperature (C)
pH
Disinfect residual (mg/L)
Required CT
Flocculation
Basin Volume
Temperature (C)
Mixing Stages
Disinfectant Applied
PH
Disinfect residual (mg/L)
Required CT
Suggested
Assgned
Rated Capacity
Sedimentation
Basin Volume
Surface Area
Basin Depth
Operation Mode
Process Type
Davenport, New Mexico |
9
sedimentati
Predis
50000
Poor
ozone
5
7
0.9
0.97
200000
0.5
Multiple
None
7
Detention Time
20
20
14.40
681135
6500
14
turbidity
rectangular
(MGD)
on Contact
None, Presed, Predis, both
(gallons)
Unbaffled Poor Average Superior
None, Chlorine, Chloramines, Chlorine
See Guidance Manual Appendix C
(gallons)
Single or Multiple
None, Chlorine, Chloramines, Chlorine
See Guidance Manual Appendix C
(min) HOT
(min) HOT
MGD
(gallons)
(ft2)
(ft)
Turbidity or Softening
None/Rectangular/Circular/Contact
Filtration
Total Filter Surface Area
Total Number of Filters
Filters Typically in Service
Total Volume Above Filters
Media Type
Dioxide, Ozone
Operation Mode
Raw Turbidity (NTU)
Air Binding
Disinfectant Applied
Disinfect residual (mg/L)
Required CT
Dioxide
Suggested
Assigned
Rated Capacity
Disinfection
Clean/veil Volume
Effective Baffling
Disinfectant Applied
Temperature (C)
pH
Disinfectant residual (mg/L)
Required Log Inactivation
Required Disinfection Log Removals
2500
10
9
20000
Dual
conventional
35
None
Chlorine
1.5
75
Loading Rate
4
4
12.96
2000000
Unbaffled
Chlorine
5
7.5
2.5
4
1.5
(ft2)
(gallons)
Sand Dual Mixed
DeepBed
Conventional Direct Inline
>0
None Moderate High
Chlorine, Chloramines
None, Chlorine Dioxide
See Guidance Manual
Appendix C
gpm/ft2
gpm/ft2
MGD
(gallons)
Unbaffled Poor
Average Superior
Chlorine, Chloramines
None, Chlorine Dioxide
3 or 4 or >4
LamellaPlates/AdsorpClarifier/SuperPulsator
Tubes Present
Percent Tube Area
Disinfectant Applied
PH
Disinfect residual (mg/L)
Required CT
Suggested
Assgned
Rated Capacity
Vertical
80
none
Process SOR
1.32
1.32
None or Vertical or Horizontal
% of basin containing tubes
None, Chlorine, Chloramines, Chlorine
See Guidance Manual Appendix C
gpm/ft2
gpm/ft2
Distribution Pipe Distance to First User
Pipe diameter
Required CT
Dioxide
Effective Contact Volume
Suggested
Assigned
Post Disinfection Rated Capacity
1000
12
82
(feet)
(inches)
see SWTR Guidance
Manual Appendix C
205879|(gallons)
Detention Time
33
33
8.98
(min) HOT
(min) HOT
MGD
12.36|MGD Pre & Post Disinfection Rated Capacity | 29.51|MGD
131
-------
Table C-2. Major Unit Process Evaluation Criteria*
Flocculation
Base
Single Stage
Multiple Stages
1 Filtration
Sand Media
Dual/Mixed Media
Deep Bed
Temp<=0.5°C
Temp >0.5°C
Temp<=0.5°C
Temp >0.5°C
Air Binding
None
Moderate
Hiah
None
Moderate
High
None
Moderate
High
Hydraulic
Detention Time
20 minutes
+10 minutes
+5 minutes
+0 minutes
-5 minutes
Loading Rate
2.0 gpm/ft2
1.5gpm/ft2
1.0 gpm/ft2
4.0 gpm/ft2
3.0 gpm/ft2
2.0 gpm/ft2
6.0 gpm/ft2
4.5 gpm/ft2
3.0 gpm/ft2
Sedimentation surface overflow
Rate
Rectangular/Circular/Contact
Turbidity Mode
Softening Mode
Vertical (>45°) Tube Settlers
Turbidity Mode
Softening Mode
Horizontal (<45°) Tube Settlers
Adsorption Clarifier
Lamella Plates
SuperPulsator
with tubes
Claricone Turbidity Mode
Claricone Softening Mode
Basin Depth
>14ft
12 -14 ft
10-12 ft
<10ft
>14ft
12 -14 ft
10-12ft
<10ft
>14ft
12 -14 ft
10-12ft
<10ft
>14ft
12 -14 ft
10-12ft
<10ft
0.7 gpm/ft2
0.6 gpm/ft2
0.5 -0.6 gpm/ft2
0.1 -0.5 gpm/ft2
1.0 gpm/ft2
0.75 gpm/ft2
0.5 - 0.75 gpm/ft2
0.1 -0.5 gpm/ft2
2.0 gpm/ft2
1.5 gpm/ft2
1.0 -1.5 gpm/ft2
0.2 -1.0 gpm/ft2
2.5 gpm/ft2
2.0 gpm/ft2
1.5 -2.0 gpm/ft2
0.7 -1.5 gpm/ft2
2.0 gpm/ft2
9.0 gpm/ft2
4.0 gpm/ft2
1.5 gpm/ft2
1.7 gpm/ft2
1.0 gpm/ft2
1.5 gpm/ft2
*lf long term (12-month) data monitoring indicates capability to meet performance goals at higher loading rates,
then these rates can be used.
Renner, R.C., B.A. Hegg, J.H. Bender, and E.M. Bissonette. 1991. Handbook- Optimizing Water Treatment Plant Performance Using the
Composite Correction Program. EPA 625/9-917027. Cincinnati, OH: USEPA.
AWWARF Workshop. 1995. Plant Optimization Workshop. Colorado Springs, CO: AWWARF.
Eastern Research Group, Inc. 1992. Water Advisor Utilizing the CCP Approach (Expert System). USEPA Work Assignment No. 7391 -55.
Eastern Research Group, Inc., Arlington, MA.
USEPA, AWWA, AWWARF, Association of Metropolitan Water Agencies, Association of State Drinking Water Administrators, and National
Association of Water Companies. 1995. Partnership for Safe Water Voluntary Water Treatment Plant Performance Improvement
Program.
132
-------
• Each major unit process section contains a sug-
gested and assigned evaluation criteria cell (e.g.,
the flocculation section contains a suggested and
an assigned hydraulic detention time cell). The
suggested loading rates, summarized in Table C-
2 of this appendix, for specified situations are
representative of conditions in which identified
unit processes have demonstrated effectiveness
in serving as a multiple barrier in the prevention
of cyst and microorganism passage through the
treatment plant.
• The actual rated capacities for each of the unit
processes are calculated from the loading rates
entered into the cells labeled "assigned loading
rates." Users must enter a value into the
assigned cell, either selecting the "suggested"
value or entering their own loading rate.
• The performance potential graph contained at the
top of each spreadsheet will instantaneously
update after each data entry. Complete the entire
data entry process prior to proceeding to printing
the spreadsheet output described in Section 6.
Section 6 - Printing Spreadsheet Output
To print the performance potential graph using:
• LOTUS 123 Release 2.4 for DOS, invoke the
WYSIWYG add-in and print the previously
defined range by pressing then selecting
and after the system has been
configured to the user's printer. If the WYSIWYG
add-in is unavailable, users should generate and
print the graph PIC file
PPG.PIC, using the
procedures.
LOTUS Printgraph
LOTUS 123 Release 5.0 for WINDOWS, or
QUATTRO PRO Release 5.0 for WINDOWS, or
EXCEL Release 4.0 or 5.0 for WINDOWS, follow
printing techniques specified for WINDOWS
applications by clicking on a printer icon
(which will print the previously defined range)
or select PRINT from the File submenu (and
select "previously defined range" when the
system requests a printing option). Users may
have to adjust margins to accommodate
individual applications in order to print output to a
single sheet of paper.
Section 7 - Important Rules to Remember
When Using the Performance Potential
Graph Spreadsheet Tool
• Cells containing "Black" values are calculated
from other pertinent data entries and cannot be
modified because the cells have been protected.
• The actual rated capacities for each of the unit
processes are calculated from the loading rate
entered into the cells labeled "assigned loading
rates." Users must enter a value into the
assigned cell, either selecting the "suggested"
value or entering their own loading rate.
• The external format file must be copied from the
Master Diskette to the same directory as the
working file or the Performance Potential Graph
will not be visible when using LOTUS 123
Release 2.4 for DOS.
133
-------
-------
Appendix D
CT Values for Inactivation of Giardia and Viruses
by Free CI2 and Other Disinfectants
All tables in this appendix are taken from Guidance Manual for Compliance With the Filtration and
Disinfection Requirements for Public Water Systems Using Surface Water Sources, Appendix E, Science and
Technology Branch, Criteria and Standards Division, Office of Drinking Water, USEPA, Washington, D.C.,
October 1989.
135
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Table D-1. CT Values for Inactivation of Giardia Cysts by Free Chlorine at 0.5 °C or Lower
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
pH <= 6.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
23 46 69 91 114 137
24 47 71 94 118 141
24 48 73 97 121 145
25 49 74 99 123 148
25 51 76 101 127 152
26 52 78 103 129 155
26 52 79 105 131 157
27 54 81 108 135 162
28 55 83 110 138 165
28 56 85 113 141 169
29 57 86 115 143 172
29 58 88 117 146 175
30 59 89 119 148 178
30 60 91 121 151 181
pH = 8.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
46 92 139 185 231 277
48 95 143 191 238 286
49 98 148 197 246 295
51 101 152 203 253 304
52 104 157 209 261 313
54 107 161 214 268 321
55 110 165 219 274 329
56 113 169 225 282 338
58 115 173 231 288 346
59 118 177 235 294 353
60 120 181 241 301 361
61 123 184 245 307 368
63 125 188 250 313 375
64 127 191 255 318 382
pH = 6.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
27 54 82 109 136 163
28 56 84 112 140 168
29 57 86 115 143 172
29 59 88 117 147 176
30 60 90 120 150 180
31 61 92 123 153 184
32 63 95 126 158 189
32 64 97 129 161 193
33 66 99 131 164 197
34 67 101 134 168 201
34 68 103 137 171 205
35 70 105 139 174 209
36 71 107 142 178 213
36 72 109 145 181 217
pH = 8.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
55 110 165 219 274 329
57 114 171 228 285 342
59 118 177 236 295 354
61 122 183 243 304 365
63 125 188 251 313 376
65 129 194 258 323 387
66 132 199 265 331 397
68 136 204 271 339 407
70 139 209 278 348 417
71 142 213 284 355 426
73 145 218 290 363 435
74 148 222 296 370 444
75 151 226 301 377 452
77 153 230 307 383 460
pH = 7.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
33 65 98 130 163 195
33 67 100 133 167 200
34 68 103 137 171 205
35 70 105 140 175 210
36 72 108 143 179 215
37 74 111 147 184 221
38 75 113 151 188 226
39 77 116 154 193 231
39 79 118 157 197 236
40 81 121 161 202 242
41 82 124 165 206 247
42 84 126 168 210 252
43 86 129 171 214 257
44 87 131 174 218 261
pH < =9.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
65 130 195 260 325 390
68 136 204 271 339 407
70 141 211 281 352 422
73 146 219 291 364 437
75 150 226 301 376 451
77 155 232 309 387 464
80 159 239 318 398 477
82 163 245 326 408 489
83 167 250 333 417 500
85 170 256 341 426 511
87 174 261 348 435 522
89 178 267 355 444 533
91 181 272 362 453 543
92 184 276 368 460 552
pH = 7.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
40 79 119 158 198 237
40 80 120 159 199 239
41 82 123 164 205 246
42 84 127 169 211 253
43 86 130 173 216 259
44 89 133 177 222 266
46 91 137 182 228 273
47 93 140 186 233 279
48 95 143 191 238 286
50 99 149 198 248 297
50 99 149 199 248 298
51 101 152 203 253 304
52 103 155 207 258 310
53 105 158 211 263 316
NOTE: CT 99.9 = CT for 3-log inactivation.
136
-------
Table D-2. CT Values for Inactivation of Giardia Cysts by Free Chlorine at 5 °C
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
Chlorine
Concentration
(mg/L)
<=O.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
pH<=6.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
16 32 49 65 81 97
17 33 50 67 83 100
17 34 52 69 86 103
18 35 53 70 88 105
18 36 54 71 89 107
18 36 55 73 91 109
19 37 56 74 93 111
19 38 57 76 95 114
19 39 58 77 97 116
20 39 59 79 98 118
20 40 60 80 100 120
20 41 61 81 102 122
21 41 62 83 103 124
21 42 63 84 105 126
pH=8.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
33 66 99 132 165 198
34 68 102 136 170 204
35 70 105 140 175 210
36 72 108 144 180 216
37 74 111 147 184 221
38 76 114 151 189 227
39 77 116 155 193 232
40 79 119 159 198 238
41 81 122 162 203 243
41 83 124 165 207 248
42 84 127 169 211 253
43 86 129 172 215 258
44 88 132 175 219 263
45 89 134 179 223 268
pH=6.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
20 39 59 78 98 117
20 40 60 80 100 120
20 41 61 81 102 122
21 42 63 83 104 125
21 42 64 85 106 127
22 43 65 87 108 130
22 44 66 88 110 132
23 45 68 90 113 135
23 46 69 92 115 138
23 47 70 93 117 140
24 48 72 95 119 143
24 49 73 97 122 146
25 49 74 99 123 148
25 50 76 101 126 151
pH=8.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
39 79 118 157 197 236
41 81 122 163 203 244
42 84 126 168 210 252
43 87 130 173 217 260
45 89 134 178 223 267
46 91 137 183 228 274
47 94 141 187 234 281
48 96 144 191 239 287
49 98 147 196 245 294
50 100 150 200 250 300
51 102 153 204 255 306
52 104 156 208 260 312
53 106 159 212 265 318
54 108 162 216 270 324
pH=7.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
23 46 70 93 116 139
24 48 72 95 119 143
24 49 73 97 122 146
25 50 75 99 124 149
25 51 76 101 127 152
26 52 78 103 129 155
26 53 79 105 132 158
27 54 81 108 135 162
28 55 83 110 138 165
28 56 85 113 141 169
29 57 86 115 143 172
29 58 88 117 146 175
30 59 89 119 148 178
30 61 91 121 152 182
pH<=9.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
47 93 140 186 233 279
49 97 146 194 243 291
50 100 151 201 251 301
52 104 156 208 260 312
53 107 160 213 267 320
55 110 165 219 274 329
56 112 169 225 281 337
58 115 173 230 288 345
59 118 177 235 294 353
60 120 181 241 301 361
61 123 184 245 307 368
63 125 188 250 313 375
64 127 191 255 318 382
65 130 195 259 324 389
pH=7.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
28 55 83 111 138 166
29 57 86 114 143 171
29 58 88 117 146 175
30 60 90 119 149 179
31 61 92 122 153 183
31 62 94 125 156 187
32 64 96 128 160 192
33 65 98 131 163 196
33 67 100 133 167 200
34 68 102 136 170 204
35 70 105 139 174 209
36 71 107 142 178 213
36 72 109 145 181 217
37 74 111 147 184 221
NOTE: CT 99.9 = CT for 3-log inactivation.
137
-------
Table D-3. CT Values for Inactivation of Giardia Cysts by Free Chlorine at 10 °C
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
Chlorine
Concentration
(mg/L)
<=O.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
pH<=6.0
Log Inactivation
0.5 1 1.5 2 2.5 3.0
12 24 37 49 61 73
13 25 38 50 63 75
13 26 39 52 65 78
13 26 40 53 66 79
13 27 40 53 67 80
14 27 41 55 68 82
14 28 42 55 69 83
14 29 43 57 72 86
15 29 44 58 73 87
15 30 45 59 74 89
15 30 45 60 75 90
15 31 46 61 77 92
16 31 47 62 78 93
16 32 48 63 79 95
pH = 8.0
Log Inactivation
0.5 1 1.5 2.0 2.5 3.0
25 50 75 99 124 149
26 51 77 102 128 153
26 53 79 105 132 158
27 54 81 108 135 162
28 55 83 111 138 166
28 57 85 113 142 170
29 58 87 116 145 174
30 60 90 119 149 179
30 61 91 121 152 182
31 62 93 124 155 186
32 63 95 127 158 190
32 65 97 129 162 194
33 66 99 131 164 197
34 67 101 134 168 201
pH=6.5
Log Inactivation
0.5 1 1.5 2 2.5 3.0
15 29 44 59 73 88
15 30 45 60 75 90
15 31 46 61 77 92
16 31 47 63 78 94
16 32 48 63 79 95
16 33 49 65 82 98
17 33 50 66 83 99
17 34 51 67 84 101
17 35 52 69 87 104
18 35 53 70 88 105
18 36 54 71 89 107
18 37 55 73 92 110
19 37 56 74 93 111
19 38 57 75 94 113
pH = 8.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
30 59 89 118 148 177
31 61 92 122 153 183
32 63 95 126 158 189
33 65 98 130 163 195
33 67 100 133 167 200
34 69 103 137 172 206
35 70 106 141 176 211
36 72 108 143 179 215
37 74 111 147 184 221
38 75 113 150 188 225
38 77 115 153 192 230
39 78 117 156 195 234
40 80 120 159 199 239
41 81 122 162 203 243
pH=7.0
Log Inactivation
0.5 1 1.5 2 2.5 3.0
17 35 52 69 87 104
18 36 54 71 89 107
18 37 55 73 92 110
19 37 56 75 93 112
19 38 57 76 95 114
19 39 58 77 97 116
20 40 60 79 99 119
20 41 61 81 102 122
21 41 62 83 103 124
21 42 64 85 106 127
22 43 65 86 108 129
22 44 66 87 109 131
22 45 67 89 112 134
23 46 69 91 114 137
pH <=9.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
35 70 105 139 174 209
36 73 109 145 182 218
38 75 113 151 188 226
39 78 117 156 195 234
40 80 120 160 200 240
41 82 124 165 206 247
42 84 127 169 211 243
43 86 130 173 216 259
44 88 133 177 221 265
45 90 136 181 226 271
46 92 138 184 230 276
47 94 141 187 234 281
48 96 144 191 239 287
49 97 146 195 243 292
pH=7.5
Log Inactivation
0.5 1 1.5 2 2.5 3.0
21 42 63 83 104 125
21 43 64 85 107 128
22 44 66 87 109 131
22 45 67 89 112 134
23 46 69 91 114 137
23 47 70 93 117 140
24 48 72 96 120 144
25 49 74 98 123 147
25 50 75 100 125 150
26 51 77 102 128 153
26 52 79 105 131 157
27 53 80 107 133 160
27 54 82 109 136 163
28 55 83 111 138 166
NOTE: CT 99.9 = CT for 3-log inactivation.
138
-------
Table D-4. CT Values for Inactivation of Giardia Cysts by Free Chlorine at 15 °C
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
pH<=6.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
16 25 33 41 49
8 17 25 33 42 50
9 17 26 35 43 52
9 18 27 35 44 53
9 18 27 36 45 54
9 18 28 37 46 55
9 19 28 37 47 56
10 19 29 38 48 57
10 19 29 39 48 58
10 20 30 39 49 59
10 20 30 40 50 60
10 20 31 41 51 61
10 21 31 41 52 62
11 21 32 42 53 63
pH=8.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
17 33 50 66 83 99
17 34 51 68 85 102
18 35 53 70 88 105
18 36 54 72 90 108
19 37 56 74 93 111
19 38 57 76 95 114
19 39 58 77 97 116
20 40 60 79 99 119
20 41 61 81 102 122
21 41 62 83 103 124
21 42 64 85 106 127
22 43 65 86 108 129
22 44 66 88 110 132
22 45 67 89 112 134
pH=6.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
1 20 30 39 49 59
1 20 30 40 50 60
1 20 31 41 51 61
11 21 32 42 53 63
11 21 32 43 53 64
11 22 33 43 54 65
11 22 33 44 55 66
11 23 34 45 57 68
12 23 35 46 58 69
12 23 35 47 58 70
12 24 36 48 60 72
12 24 37 49 61 73
12 25 37 49 62 74
13 25 38 51 63 76
pH=8.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
20 39 59 79 98 118
20 41 61 81 102 122
21 42 63 84 105 126
22 43 65 87 108 130
22 45 67 89 112 134
23 46 69 91 114 137
24 47 71 94 118 141
24 48 72 96 120 144
25 49 74 98 123 147
25 50 75 100 125 150
26 51 77 102 128 153
26 52 78 104 130 156
27 53 80 106 133 159
27 54 81 108 135 162
pH=7.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
12 23 35 47 58 70
12 24 36 48 60 72
12 24 37 49 61 73
13 25 38 50 63 75
13 25 38 51 63 76
13 26 39 52 65 78
13 26 40 53 66 79
14 27 41 54 68 81
14 28 42 55 69 83
14 28 43 57 71 85
14 29 43 57 72 86
15 29 44 59 73 88
15 30 45 59 74 89
15 30 46 61 76 91
pH<=9.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
23 47 70 93 117 140
24 49 73 97 122 146
25 50 76 101 126 151
26 52 78 104 130 156
27 53 80 107 133 160
28 55 83 110 138 165
28 56 85 113 141 169
29 58 87 115 144 173
30 59 89 118 148 177
30 60 91 121 151 181
31 61 92 123 153 184
31 63 94 125 157 188
32 64 96 127 159 191
33 65 98 130 163 195
pH=7.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
14 28 42 55 69 83
14 29 43 57 72 86
15 29 44 59 73 88
15 30 45 60 75 90
15 31 46 61 77 92
16 31 47 63 78 94
16 32 48 64 80 96
16 33 49 65 82 98
17 33 50 67 83 100
17 34 51 68 85 102
18 35 53 70 88 105
18 36 54 71 89 107
18 36 55 73 91 109
19 37 56 74 93 111
NOTE: CT 99.9 = CT for 3-log inactivation.
139
-------
Table D-5. CT Values for Inactivation of Giardia Cysts by Free Chlorine at 20 °C
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
pH<=6.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
6 12 18 24 30 36
6 13 19 25 32 38
7 13 20 26 33 39
7 13 20 26 33 39
7 13 20 27 33 40
7 14 21 27 34 41
7 14 21 28 35 42
7 14 22 29 36 43
7 15 22 29 37 44
7 15 22 29 37 44
8 15 23 30 38 45
8 15 23 31 38 46
8 16 24 31 39 47
8 16 24 31 39 47
pH=8.0
Lot Inactivation
0.5 1 1.5 2.0 2.5 3.0
12 25 37 49 62 74
13 26 39 51 64 77
13 26 40 53 66 79
14 27 41 54 68 81
14 28 42 55 69 83
14 28 43 57 71 85
15 29 44 58 73 87
15 30 45 59 74 89
15 30 46 61 76 91
16 31 47 62 78 93
16 32 48 63 79 95
16 32 49 65 81 97
17 33 50 66 83 99
17 34 51 67 84 101
pH=6.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
7 15 22 29 37 44
8 15 23 30 38 45
8 15 23 31 38 46
8 16 24 31 39 47
8 16 24 32 40 48
8 16 25 33 41 49
8 17 25 33 42 50
9 17 26 34 43 51
9 17 26 35 43 52
9 18 27 35 44 53
9 18 27 36 45 54
9 18 28 37 46 55
9 19 28 37 47 56
10 19 29 38 48 57
pH=8.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
15 30 45 59 74 89
15 31 46 61 77 92
16 32 48 63 79 95
16 33 49 65 82 98
17 33 50 67 83 100
17 34 52 69 86 103
18 35 53 70 88 105
18 36 54 72 90 108
18 37 55 73 92 110
19 38 57 75 94 113
19 38 58 77 96 115
20 39 59 78 98 117
20 40 60 79 99 119
20 41 61 81 102 122
pH=7.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
9 17 26 35 43 52
9 18 27 36 45 54
9 18 28 37 46 55
9 19 28 37 47 56
10 19 29 38 48 57
10 19 29 39 48 58
10 20 30 39 49 59
10 20 31 41 51 61
10 21 31 41 52 62
11 21 32 42 53 63
11 22 33 43 54 65
11 22 33 44 55 66
11 22 34 45 56 67
11 23 34 45 57 68
pH<=9.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
18 35 53 70 88 105
18 36 55 73 91 109
19 38 57 75 94 113
20 39 59 78 98 117
20 40 60 80 100 120
21 41 62 82 103 123
21 42 63 84 105 126
22 43 65 86 108 129
22 44 66 88 110 132
23 45 68 90 113 135
23 46 69 92 115 138
24 47 71 94 118 141
24 48 72 95 119 143
24 49 73 97 122 146
pH=7.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
10 21 31 41 52 62
11 21 32 43 53 64
11 22 33 44 55 66
11 22 34 45 56 67
12 23 35 46 58 69
12 23 35 47 58 70
12 24 36 48 60 72
12 25 37 49 62 74
13 25 38 50 63 75
13 26 39 51 64 77
13 26 39 52 65 78
13 27 40 53 67 80
14 27 41 54 68 81
14 28 42 55 69 83
NOTE: CT 99.9 = CT for 3-log inactivation.
140
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Table D-6. CT Values for Inactivation of Giardia Cysts by Free Chlorine at 25 °C
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
Chlorine
Concentration
(mg/L)
<=0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
pH<=6.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
4 8 12 16 20 24
4 8 13 17 21 25
4 9 13 17 22 26
4 9 13 17 22 26
5 9 14 18 23 27
5 9 14 18 23 27
5 9 14 19 23 28
5 10 15 19 24 29
5 10 15 19 24 29
5 10 15 20 25 30
5 10 15 20 25 30
5 10 16 21 26 31
5 10 16 21 26 31
5 11 16 21 27 32
pH=8.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
8 17 25 33 42 50
9 17 26 34 43 51
9 18 27 35 44 53
9 18 27 36 45 54
9 18 28 37 46 55
10 19 29 38 48 57
10 19 29 39 48 58
10 20 30 40 50 60
10 20 31 41 51 61
10 21 31 41 52 62
11 21 32 42 53 63
11 22 33 43 54 65
11 22 33 44 55 66
11 22 34 45 56 67
pH=6.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
5 10 15 19 24 29
5 10 15 20 25 30
5 10 16 21 26 31
5 10 16 21 26 31
5 11 16 21 27 32
6 11 17 22 28 33
6 11 17 22 28 33
6 11 17 23 28 34
6 12 18 23 29 35
6 12 18 23 29 35
6 12 18 24 30 36
6 12 19 25 31 37
6 12 19 25 31 37
6 13 19 25 32 38
pH=8.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
10 20 30 39 49 59
11 20 31 41 51 61
11 21 32 42 53 63
11 22 33 43 54 65
11 22 34 45 56 67
12 23 35 46 58 69
12 23 35 47 58 70
12 24 36 48 60 72
12 25 37 49 62 74
13 25 38 50 63 75
13 26 39 51 64 77
13 26 39 52 65 78
13 27 40 53 67 80
14 27 41 54 68 81
pH=7.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
6 12 18 23 29 35
6 12 18 24 30 36
6 12 19 25 31 37
6 12 19 25 31 37
6 13 19 25 32 38
7 13 20 26 33 39
7 13 20 27 33 40
7 14 21 27 34 41
7 14 21 27 34 41
7 14 21 28 35 42
7 14 22 29 36 43
7 15 22 29 37 44
8 15 23 30 38 45
8 15 23 31 38 46
pH<=9.0
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
12 23 35 47 58 70
12 24 37 49 61 73
13 25 38 50 63 75
13 26 39 52 65 78
13 27 40 53 67 80
14 27 41 55 68 82
14 28 42 56 70 84
14 29 43 57 72 86
15 29 44 59 73 88
15 30 45 60 75 90
15 31 46 61 77 92
16 31 47 63 78 94
16 32 48 64 80 96
16 32 49 65 81 97
PH=7.5
Log Inactivation
0.5 1.0 1.5 2.0 2.5 3.0
7 14 21 28 35 42
7 14 22 29 36 43
7 15 22 29 37 44
8 15 23 30 38 45
8 15 23 31 38 46
8 16 24 31 39 47
8 16 24 32 40 48
8 16 25 33 41 49
8 17 25 33 42 50
9 17 26 34 43 51
9 17 26 35 43 52
9 18 27 35 44 53
9 18 27 36 45 54
9 18 28 37 46 55
NOTE: CT 99.9 = CT for 3-log inactivation.
141
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Table D-7. CT Values for Inactivation of Viruses by Free Chlorine
Log Inactivation
2.0 3.0 4.0
PH
Temperature (C)
0.5
5
10
15
20
25
6-9 10
6 45
4 30
3 22
2 15
1 11
1 7
6-9 10
9 66
6 44
4 33
3 22
2 16
1 11
6-9 10
12 90
8 60
6 45
4 30
3 22
2 15
Table D-8. CT Values for Inactivation of Giardia Cysts by Chlorine Dioxide
Temperature (C)
2-log
3-log
4-log
<=1
8.4
25.6
50.1
5
5.6
17.1
33.4
10
4.2
12.8
25.1
15
2.8
8.6
16.7
20
2.1
6.4
12.5
25
1.4
4.3
8.4
Table D-9. CT Values for Inactivation of Viruses by Chlorine Dioxide pH 6-9
Temperature (C)
0.5-log
1-log
1.5-log
2-log
2.5-log
3-log
<=1
10
21
32
42
52
63
5
4.3
8.7
13
17
22
26
10
4
7.7
12
15
19
23
15
3.2
6.3
10
13
16
19
20
2.5
5
7.5
10
13
15
25
2
3.7
5.5
7.3
9
11
Table D-10. CT Values for Inactivation of Giardia Cysts by Ozone
Temperature (C)
0.5-log
1-log
1.5-log
2-log
2.5-log
3-log
<=1
0.48
0.97
1.5
1.9
2.4
2.9
5
0.32
0.63
0.95
1.3
1.6
1.9
10
0.23
0.48
0.72
0.95
1.2
1.43
15
0.16
0.32
0.48
0.63
0.79
0.95
20
0.1
0.2
0.36
0.48
0.6
0.72
25
0.08
0.16
0.24
0.32
0.4
0.48
142
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Table D-11. CT Values for Inactivation of Viruses by Ozone
Temperature (C)
2-log
3-log
4-log
<=1
0.9
1.4
1.8
5
0.6
0.9
1.2
10
0.5
0.8
1
15
0.3
0.5
0.6
20
0.25
0.4
0.5
25
0.15
0.25
0.3
Table D-12. CT Values for Inactivation of Giardia Cysts by Chloramine pH 6-9
Temperature (C)
0.5-log
1-log
1.5-log
2-log
2.5-log
3-log
<=1
635
1270
1900
2535
3170
3800
5
365
735
1100
1470
1830
2200
10
310
615
930
1230
1540
1850
15
250
500
750
1000
1250
1500
20
185
370
550
735
915
1100
25
125
250
375
500
625
750
Table D-13. CT Values for Inactivation of Viruses by Chloramine
Temperature (C)
2-log
3-log
4-log
<=1
1243
2063
2883
5
857
1423
1988
10
643
1067
1491
15
428
712
994
20
321
534
746
25
214
356
497
Table D-14. CT Values for Inactivation of Viruses by UV
Log Inactivation
2 3
21
36
143
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Appendix E
Performance Limiting Factors Summary Materials
and Definitions
145
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CPE Factor Summary Sheet Terms
Plant Type
Source Water
Performance Summary
Ranking Table
Rank
Rating
Performance Limiting
Factor (Category)
Notes
Brief but specific description of plant type (e.g., conventional with
flash mix, flocculation, sedimentation, filtration and chlorine
disinfection; or direct filtration with flash mix, flocculation and chlorine
disinfection).
Brief description of source water (e.g., surface water including name
of water body).
Brief description of plant performance based on performance
assessment component of the CPE (i.e., ability of plant to meet
optimized performance goals).
A listing of identified performance limiting factors that directly impact
plant performance and reliability.
Relative ranking of factor based on prioritization of all "A" and "B"
rated factors identified during the CPE.
Rating of factor based on impact on plant performance and reliability:
A — Major effect on a long-term repetitive basis
B — Moderate effect on a routine basis or major effect on a
periodic basis
C — Minor effect
Factor identified from Checklist of Performance Limiting Factors,
including factor category (e.g., administration, design, operation, and
maintenance).
Brief listing of reasons each factor was identified (e.g., lack of
process control testing, no defined performance goals).
146
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CPE Performance Limiting Factors Summary
Plant Name/Location:
CPE Performed By:
CPE Date:
Plant Type:
Source Water:
Performance Summary:
Ranking Table
Rank
Rating
Performance Limiting Factor (Category)
Rating Description
A — Major effect on long-term repetitive basis.
B — Moderate effect on a routine basis or major effect on a periodic basis.
C — Minor effect.
147
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Factor
Performance Limiting Factors Notes
Notes
148
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Checklist of Performance Limiting Factors
A. ADMINISTRATION
1. Plant Administrators
a. D Policies
b. D Familiarity With Plant Needs
c. D Supervision
d. D Planning
e. D Complacency
f. D Reliability
g. D Source Water Protection
2. Plant Staff
a. D Number
b. D Plant Coverage
c. D Personnel Turnover
d. D Compensation
e. D Work Environment
f. D Certification
3. Financial
a. D Operating Ratio
b. D Coverage Ratio
c. D Reserves
B. DESIGN
1. Source Water Quality
a. D Microbial Contamination
2. Unit Process Adeguacy
a. D Intake Structure
b. D Presedimentation Basin
c. D Raw Water Pumping
d. D Flow Measurement
e. D Chemical Storage and Feed
Facilities
f. D Flash Mix
g. D Flocculation
h. D Sedimentation
i. D Filtration
j. D Disinfection
k. D Sludge/Backwash Water
Treatment and Disposal
149
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3. Plant Operability
a. D Process Flexibility
b. D Process Controllability
c. D Process Instrumentation/
Automation
d. D Standby Units for Key
Equipment
e. D Flow Proportioning
f. D Alarm Systems
g. D Alternate Power Source
h. D Laboratory Space and Eguipment
i. D Sample Taps
C. OPERATION
1. Testing
a. D Process Control Testing
b. D Representative Sampling
2. Process Control
a. D Time on the Job
b. D Water Treatment Understanding
c. D Application of Concepts and
Testing to Process Control
3. Operational Resources
a. D Training Program
b. D Technical Guidance
c. D Operational Guidelines/Procedures
D. MAINTENANCE
1. Maintenance Program
a. D Preventive
b. D Corrective
c. D Housekeeping
2. Maintenance Resources
a. D Materials and Eguipment
b. D Skills or Contract Services
150
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Definitions for Assessing Performance Limiting Factors
NOTE: The following list of defined factors is provided to assist the evaluator with identifying performance limitations
associated with protection against microbial contaminants in water treatment systems. Performance limiting factors are
described below using the following format.
A. CATEGORY
1. Subcategory
a. Factor Name
» Factor description
> Example of factor applied to specific plant or utility
A. Administration
1. Plant Administrators
a. Policies
* Do existing policies or the lack of policies discourage staff members from making required operation,
maintenance, and management decisions to support plant performance and reliability?
> Utility administration has not communicated a clear policy to optimize plant performance for public
health protection.
> Multiple management levels within a utility contribute to unclear communication and lack of
responsibility for plant operation and performance.
> Cost savings is emphasized by management at the expense of plant performance.
> Utility managers do not support reasonable training and certification requests by plant staff.
> Administration continues to allow connections to the distribution system without consideration for
the capacity of the plant.
b. Familiarity With Plant Needs
* Do administrators lack first-hand knowledge of plant needs?
> The utility administrators do not make plant visits or otherwise communicate with plant staff.
> Utility administrators do not request input from plant staff during budget development.
c. Supervision
* Do management styles, organizational capabilities, budgeting skills, or communication practices at any
management level adversely impact the plant to the extent that performance is affected?
> A controlling supervision style does not allow the plant staff to contribute to operational decisions.
> A plant supervisor's inability to set priorities for staff results in insufficient time allocated for
process control.
d. Planning
* Does the lack of long range planning for facility replacement or alternative source water quantity or
quality adversely impact performance?
> A utility has approved the connection of new customers to the water system without considering
the water demand impacts on plant capacity.
> An inadequate capital replacement program results in utilization of outdated equipment that
cannot support optimization goals.
151
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e. Complacency
* Does the presence of consistent, high quality source water result in complacency within the water
utility?
> Due to the existence of consistent, high quality source water, plant staff are not prepared to
address unusual water quality conditions.
> A utility does not have an emergency response plan in place to respond to unusual water quality
conditions or events.
f. Reliability
* Do inadequate facilities or equipment, or the depth of staff capability, present a potential weak link
within the water utility to achieve and sustain optimized performance?
> Outdated filter control valves result in turbidity spikes in the filtered water entering the plant
clearwell.
> Plant staff capability to respond to unusual water quality conditions exists with only the laboratory
supervisor.
g. Source Water Protection
* Does the water utility lack an active source water protection program?
> The absence of a source water protection program has resulted in the failure to identify and
eliminate the discharge of failed septic tanks into the utility's source water lake.
> Utility management has not evaluated the impact of potential contamination sources on water
quality within their existing watershed.
2. Plant Staff
a. Number
* Does a limited number of people employed have a detrimental effect on plant operations or
maintenance?
> Plant staff are responsible for operation and maintenance of the plant as well as distribution
system and meter reading, limiting the time available for process control testing and process
adjustments.
b. Plant Coverage
* Does the lack of plant coverage result in inadequate time to complete necessary operational activities?
(Note: This factor could have significant impact if no alarm/shutdown capability exists - see design
factors).
> Staff are not present at the plant during evenings, weekends, or holidays to make appropriate
plant and process control adjustments.
> Staff are not available to respond to changing source water quality characteristics.
c. Personnel Turnover
* Does high personnel turnover cause operation and maintenance problems that affect process
performance or reliability?
> The lack of support for plant needs results in high operator turnover and, subsequently,
inconsistent operating procedures and low staff morale.
d. Compensation
* Does a low pay scale or benefit package discourage more highly qualified persons from applying for
operator positions or cause operators to leave after they are trained?
> The current pay scale does not attract personnel with sufficient qualifications to support plant
process control and testing needs.
e. Work Environment
* Does a poor work environment create a condition for "sloppy work habits" and lower operator morale?
> A small, noisy work space is not conducive for the recording and development of plant data.
152
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f. Certification
* Does the lack of certified personnel result in poor O & M decisions?
> The lack of certification hinders the staffs ability to make proper process control adjustments.
3. Financial
a. Operating Ratio
* Does the utility have inadequate revenues to cover operation, maintenance, and replacement of
necessary equipment (i.e., operating ratio less than 1.0)?
> The current utility rate structure does not provide adequate funding and limits expenditures
necessary to pursue optimized performance (e.g., equipment replacement, chemical purchases,
spare parts).
b. Coverage Ratio
* Does the utility have inadequate net operating profit to cover debt service requirements (i.e., coverage
ratio less than 1.25)?
> The magnitude of a utility's debt service has severely impacted expenditures on necessary plant
equipment and supplies.
c. Reserves
* Does the utility have inadequate reserves to cover unexpected expenses or future facility replacement?
> A utility has a 40-year-old water treatment plant requiring significant modifications; however, no
reserve account has been established to fund these needed capital expenditures.
B. Design
1. Source Water Quality
a. Microbial Contamination
* Does the presence of microbial contamination sources in close proximity to the water treatment plant
intake impact the plant's ability to provide an adequate treatment barrier?
> A water treatment plant intake is located downstream of a major wastewater treatment plant
discharge and is subject to a high percentage of this flow during drought periods.
2. Unit Process Adequacy
a. Intake Structure
* Does the design of the intake structure result in excessive clogging of screens, build-up of silt, or
passage of material that affects plant equipment?
> The location of an intake structure on the outside bank of the river causes excessive collection of
debris, resulting in plugging of the plant flow meter and static mixer.
> The design of a reservoir intake structure does not include flexibility to draw water at varying
levels to minimize algae concentration.
b. Presedimentation Basin
* Does the design of an existing presedimentation basin or the lack of a presedimentation basin
contribute to degraded plant performance?
> The lack of flexibility with a presedimentation basin (i.e., number of basins, size, bypass) causes
excessive algae growth, impacting plant performance.
> A conventional plant treating water directly from a "flashy" stream experiences performance
problems during high turbidity events.
153
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c. Raw Water Pumping
* Does the use of constant speed pumps cause undesirable hydraulic loading on downstream unit
processes?
> The on-off cycle associated with raw water pump operation at a plant results in turbidity spikes in
the sedimentation basin and filters.
d. Flow Measurement
* Does the lack of flow measurement devices or their accuracy limit plant control or impact process
control adjustments?
> The flow measurement device in a plant is not accurate, resulting in inconsistent flow
measurement records and the inability to pace chemical feed rates according to flow.
e. Chemical Storage and Feed Facilities
* Do inadeguate chemical storage and feed facilities limit process needs in a plant?
> Inadequate chemical storage facilities exist at a plant, resulting in excessive chemical handling
and deliveries.
> Capability does not exist to measure and adjust the coagulant and flocculant feed rates.
f. Flash Mix
* Does inadeguate mixing result in excessive chemical use or insufficient coagulation to the extent that it
impacts plant performance?
> A static mixer does not provide effective chemical mixing throughout the entire operating flow
range of the plant.
> Absence of a flash mixer results in less than optimal chemical addition and insufficient
coagulation.
g. Flocculation
* Does a lack of flocculation time, inadeguate eguipment, or lack of multiple flocculation stages result in
poor floe formation and degrade plant performance?
> A direct filtration plant, treating cold water and utilizing a flocculation basin with short detention
time and hydraulic mixing, does not create adequate floe for filtration.
h. Sedimentation
* Does the sedimentation basin configuration or eguipment cause inadeguate solids removal that
negatively impacts filter performance?
> The inlet and outlet configurations of the sedimentation basins cause short-circuiting, resulting in
poor settling and floe carryover to the filters.
> The outlet configuration causes floe break-up, resulting in poor filter performance
> The surface area of the available sedimentation basins is inadequate, resulting in solids loss and
inability to meet optimized performance criteria for the process.
Filtration
Do filter or filter media characteristics limit the filtration process performance?
> The filter loading rate in a plant is excessive, resulting in poor filter performance.
> Either the filter underdrain or support gravel have been damaged to the extent that filter
performance is impacted.
Do filter rate-of-flow control valves provide a consistent, controlled filtration rate?
> The rate-of-flow control valves produce erratic, inconsistent flow rates that result in turbidity and/or
particle spikes.
Do inadeguate surface wash or backwash facilities limit the ability to clean the filter beds?
> The backwash pumps for a filtration system do not have sufficient capacity to adequately clean
the filters during backwash.
154
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> The surface wash units are inadequate to properly clean the filter media.
> Backwash rate is not sufficient to provide proper bed expansion to properly clean the filters.
\. Disinfection
* Do the disinfection facilities have limitations, such as inadequate detention time, improper mixing, feed
rates, proportional feeds, or baffling, that contribute to poor disinfection?
> An unbaffled clearwell does not provide the necessary detention time to meet the Giardia
inactivation requirements of the SWTR.
k. Sludge/Backwash Water Treatment and Disposal
* Do inadequate sludge or backwash water treatment facilities negatively influence plant performance?
> The plant is recycling backwash decant water without adequate treatment.
> The plant is recycling backwash water intermittently with high volume pumps.
> The effluent discharged from a sludge/backwash water storage lagoon does not meet applicable
receiving stream permits.
> Inadequate long-term sludge disposal exists at a plant, resulting in reduced cleaning of settling
basins and recycle of solids back to the plant.
3. Plant Operability
a. Process Flexibility
* Does the lack of flexibility to feed chemicals at desired process locations or the lack of flexibility to
operate equipment or processes in an optimized mode limit the plant's ability to achieve desired
performance goals?
> A plant does not have the flexibility to feed either a flocculant aid to enhance floe development and
strength or a filter aid to improve filter performance.
> A plant includes two sedimentation basins that can only be operated in series.
b. Process Controllability
* Do existing process controls or lack of specific controls limit the adjustment and control of a process
over the desired operating range?
> Filter backwash control does not allow for the ramping up and down of the flow rate during a
backwash event.
> During a filter backwash, the lack of flow control through the plant causes hydraulic surging
through the operating filters.
> The level control system located in a filter influent channel causes the filter effluent control valves
to overcompensate during flow rate changes in a plant.
> Flows between parallel treatment units are not equal and cannot be controlled.
> The plant influent pumps cannot be easily controlled or adjusted, necessitating automatic start-
up/shutdown of raw water pumps.
> Plant flow rate measurement is not adequate to allow accurate control of chemical feed rates.
> Chemical feed rates are not easily changed or are not automatically changed to account for
changes in plant flow rate.
c. Process Instrumentation/Automation
* Does the lack of process instrumentation or automation cause excessive operator time for process
control and monitoring?
> A plant does not have continuous recording turbidimeters on each filter, resulting in extensive
operator time for sampling.
155
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> The indication of plant flow rate is only located in the pipe gallery, which causes difficulty in
coordinating plant operation and control.
> Automatic shutdown/start-up of the plant results in poor unit process performance.
d. Standby Units for Key Equipment
* Does the lack of standby units for key equipment cause degraded process performance during
breakdown or during necessary preventive maintenance activities?
> Only one backwash pump is available to pump water to a backwash supply tank, and the
combination of limited supply tank volume and an unreliable pump has caused staff to limit
backwashing of filters during peak production periods.
e. Flow Proportioning
* Does inadequate flow splitting to parallel process units cause individual unit overloads that degrade
process performance?
> Influent flow to a plant is hydraulically split to multiple treatment trains, and uneven flow
distribution causes overloading of one flocculation/sedimentation train over the others.
f. Alarm Systems
* Does the absence or inadequacy of an alarm system for critical equipment or processes cause
degraded process performance?
> A plant that is not staffed full-time does not have alarm and plant shut-down capability for critical
finished water quality parameters (i.e., turbidity, chlorine residual).
g. Alternate Power Source
* Does the absence of an alternate power source cause reliability problems leading to degraded plant
performance?
> A plant has frequent power outages, and resulting plant shutdowns and start-ups cause turbidity
spikes in the filtered water.
h. Laboratory Space and Equipment
* Does the absence of an adequately equipped laboratory limit plant performance?
> A plant does not have an adequate process control laboratory for operators to perform key tests
(i.e., turbidity, jar testing).
i. Sample Taps
* Does the lack of sample taps on process flow streams prevent needed information from being obtained
to optimize performance?
> Filter-to-waste piping following plant filters does not include sample taps to measure the turbidity
spike following backwash.
> Sludge sample taps are not available on sedimentation basins to allow process control of the
sludge draw-off from these units.
C. Operation
1. Testing
a. Process Control Testing
* Does the absence or wrong type of process control testing cause improper operational control
decisions to be made?
> Plant staff do not measure and record raw water pH, alkalinity, and turbidity on a routine basis;
consequently, the impact of raw water quality on plant performance cannot be assessed.
> Sedimentation basin effluent turbidity is not measured routinely in a plant.
156
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b. Representative Sampling
* Do monitoring results inaccurately represent plant performance or are samples collected improperly?
> Plant staff do not record the maximum turbidity spikes that occur during filter operation and
following filter backwash events.
> Turbidity sampling is not performed during periods when the reclaim backwash water pump is in
operation.
2. Process Control
a. Time on the Job
* Does staff's short time on the job and associated unfamiliarity with process control and plant needs
result in inadeguate or improper control adjustments?
> Utility staff, unfamiliar with surface water treatment, were given responsibility to start a new plant;
and lack of experience and training contributed to improper coagulation control and poor
performance.
b. Water Treatment Understanding
* Does the operator's lack of basic water treatment understanding contribute to improper operational
decisions and poor plant performance or reliability?
> Plant staff do not have sufficient understanding of water treatment processes to make proper
equipment or process adjustments.
> Plant staff have limited exposure to water treatment terminology, limiting their ability to interpret
information presented in training events or in published information.
c. Application of Concepts and Testing to Process Control
* Is the staff deficient in the application of their knowledge of water treatment and interpretation of
process control testing such that improper process control adjustments are made?
> Plant staff do not perform jar testing to determine appropriate coagulant dosages for different
water quality conditions.
> Plant filters are placed back in service following backwash without consideration for effluent
turbidity levels.
> Filter to waste valves are available but are not used following filter backwash.
> Plant staff do not calculate chemical dosages on a routine basis.
> Plant staff do not change chemical feed systems to respond to changes in raw water quality.
> Filters are backwashed based on time in service or headloss rather than on optimized
performance goal for turbidity or particle removal.
> Plant staff "bump" filters by increasing the hydraulic loading to see if backwashing is necessary.
> Sedimentation basin performance is controlled by visual observation rather than process control
testing.
3. Operational Resources
a. Training Program
* Does inadeguate training result in improper process control decisions by plant staff?
> A training program does not exist for new operators at a plant, resulting in inconsistent operator
capabilities.
157
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b. Technical Guidance
* Does inappropriate information received from a technical resource (e.g., design engineer, equipment
representative, regulator, peer) cause improper decisions or priorities to be implemented?
> A technical resource occasionally provides recommendations to the plant staff; however,
recommendations are not based on plant-specific studies.
c. Operational Guidelines/Procedures
* Does the lack of plant-specific operating guidelines and procedures result in inconsistent operational
decisions that impact performance?
> The lack of operational procedures has caused inconsistent sampling between operator shifts and
has led to improper data interpretation and process control adjustments.
D. Maintenance
1. Maintenance Program
a. Preventive
* Does the absence or lack of an effective preventive maintenance program cause unnecessary
equipment failures or excessive downtime that results in plant performance or reliability problems?
> Preventive maintenance is not performed on plant equipment as recommended by the
manufacturer, resulting in premature equipment failures and degraded plant performance.
> A work order system does not exist to identify and correct equipment that is functioning
improperly.
b. Corrective
* Does the lack of corrective maintenance procedures affect the completion of emergency equipment
maintenance?
> A priority system does not exist on completion of corrective maintenance activities, resulting in a
critical sedimentation basin being out of service for an extended period.
> Inadequate critical spare parts are available at the plant, resulting in equipment downtime.
c. Housekeeping
* Does a lack of good housekeeping procedures detract from the professional image of the water
treatment plant?
> An unkempt, cluttered working environment in a plant does not support the overall good
performance of the facility.
2. Maintenance Resources
a. Materials and Equipment
* Does the lack of necessary materials and tools delay the response time to correct plant equipment
problems?
> Inadequate tool resources at a plant results in increased delays in repairing equipment.
b. Skills or Contract Services
* Do plant maintenance staff have inadequate skills to correct equipment problems or do the
maintenance staff have limited access to contract maintenance services?
> Plant maintenance staff do not have instrumentation and control skills or access to contract
services for these skills, resulting in the inability to correct malfunctioning filter rate control valves.
158
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Appendix F
Data Collection Forms
159
-------
Contends
Section Page
Kick-Off Meeting 161-163
Administration Data 164-169
Design Data 170-180
Operations Data 181 -189
Maintenance Data 190 -191
Field Evaluation Data 192 -197
Interview Data 198 - 200
Exit Meeting 201 - 203
160
-------
KICK-OFF MEETING
A. Kick-Off Meeting Agenda
1. Purpose of the CPE
• Background on CCP process development and application
• Basis for conducting the CPE at the utility
• Assess ability of plant to meet optimized performance goals
Optimized performance criteria description
Multiple barrier concept for microbial protection
• Identify factors limiting plant performance
• Describe follow-up activities
2. Schedule CPE events
• Plant tour
Utility Staff Involved
Date/Time
• On-site data collection
Performance
Design
Operations
Maintenance
Administration
Special studies
Interviews
Exit meeting
161
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3. Information Resources
• Performance monitoring records
• Plant operating records
• As-built construction drawings
• Plant flow schematic
• As-built construction drawings
• O & M manuals
• Equipment manuals
• Previous and current year budgets
• Organizational structure
Water rate structure
162
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KICK-OFF MEETING
B. Attendance List
Utility Name
Date
Name
Title/Position
Telephone No.
163
-------
A. Name and Location
1. Name of Facility
2. Utility Name
3. Current Date
4. Contact Information:
Contact Name
Title
Mailing Address
Phone
Fax
Administration
Plant
B. Organization
1. Governing Body (name and scheduled meetings)
2. Utility structure (attach organizational chart if available)
164
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ADMINISTRATION DATA
3. Plant Organizational Structure (include operations, maintenance, laboratory personnel; attach chart if
available)
C. Communications
1. Utility Mission Statement
2. Water Quality Goals
165
-------
3. Communication Mechanisms:
Type
D
D
D
D
Staff Meetings
Administrator/Board
Visits to Plant
Reports (plant staff to
manager; manager to
governing board)
Public Relations/
Education
Description
D. Planning
1. Short-Term Needs
2. Long-Term Needs
166
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ADMINISTRATION DATA
E. Personnel
Title/Name
No.
Certification
Pay Scale
% Time
at Plant
Comments (e.g., vacant positions, adequacy of current staffing):
F. Plant Coverage
1. Shift Description (e.g., length, number per shift, weekend/holiday coverage)
2. Unstaffed Operation Safeguards (e.g., alarm/shutdown capability, dialer)
167
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G. Financial Information
1. Budget (basis for budget: total utility D plant only D)
Enter Year
1. Beginning Cash on Hand
2. Cash Receipts
a. Water Sales Revenue
b. Other Revenue (connection fees, interest)
c. Total Water Revenue (2a +2b)
d. Number of Customer Accounts
e. Average Charge per Account (2a •*• 2d)
3. Total Cash Available (1 + 2c)
4. Operating Expenses
a. Total O&M Expenses*
b. Replacement Expenses
c. Total O,M&R Expenses (4a + 4b)
d. Total Loan Payments (interest + principal)
e. Capital Purchases
f. Total Cash Paid Out (4c + 4d + 4e)
g. Ending Cash Position (3 - 4f)
5. Operating Ratio (2a •*• 4C)1
6. Coverage Ratio (2c - 4c) •*• (4d)T
7. Year End Reserves (debt, capital improvements)
8. End of Year Operating Cash (4g - 7)
Last Year Actual
m////////A
w/////////,
Current Year
Budget
W///////////.
Y///////////A
Source: USEPA Region 8 Financial Analysis Document (1997)
* Includes employee compensation, chemicals, utilities, supplies, training, transportation,
insurance, etc.
± Measure of whether operating revenues are sufficient to cover O,M&R expenses. An
operating ratio of 1.0 is considered minimum for a self-supporting utility.
t Measure of the sufficiency of net operating profit to cover debt service requirements of
the utility. Bonding requirements may require a minimum ratio (e.g., 1.25).
168
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ADMINISTRATION DATA
2. Supporting Financial Information:
Category
D
D
D
D
D
Rate Structure
• User fees
• Connection fees
• Planned rate changes
Debt Service
• Long-term debt
• Reserve account
Capital
Improvements
• Planning
• Reserve account
Budget Process
• Staff involvement
Spending Authorization
• Administrator
• Plant staff
Information
A.
1.
Plant Schematic and Capacity Information
Attach or draw plant flow schematic; include the following details:
• Source water type/location • Chemical injection locations
169
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• Major unit processes
• Flow measurement locations
• Piping flexibility
• On-line monitoring type/location
2. Flow Conditions:
Parameter
Design Capacity
Average Annual Flow
Peak Instantaneous Flow
Flow
170
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DESIGN DATA
B. Major Unit Process Information
1. Flocculation:
Topic
1. Description
2. Dimensions
3. Major Unit
Process
Evaluation
4. Other
Design
Information
(G values)
Description
Type (reel, turbine, hydraulic)
Number trains/stages per train
Control (constant/variable speed)
Information
Length per stage:
Width per stage:
Depth per stage:
Total volume:
Selected Process Parameter(s):
Detention time (min)
Assigned process capacity
Calculation of mixing energy as expressed by the mean velocity gradient (G) for mechanical mixing:
G =
G = Velocity gradient, sec"
u = viscosity, Ib-sec/ft2
v = volume, ft3
P = energy dissipated, ft-lb/sec
= hp x 550 ft-lb/sec/hp
Calculation of G for hydraulic mixing:
G =
tut
p = water density, 62.4 Ib/ft
l\ = head loss, ft
t = detention time, sec
Viscosity of Water Versus Temperature
Temp. (°F)
32
40
50
60
70
80
90
100
Temp. (°C)
0
4
10
16
21
27
32
38
Viscosity
x10'5
(Ib-sec/ft2)
3.746
3.229
2.735
2.359
2.050
1.799
1.595
1.424
171
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B. Major Unit Process Information (cont.)
2. Sedimentation:
Topic
1. Description
2. Dimensions
3. Major Unit
Process
Evaluation
4. Other
Design
Information
Description
Type (conventional, tube settlers)
Number trains
Weir location
Sludge collection
Information
Length or diameter:
Width:
Depth:
Total surface area:
Selected Process Parameter(s):
Surface loading rate
Assigned process capacity
172
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DESIGN DATA
B. Major Unit Process Information (cont.)
3. Filtration:
Topic
Description
Information
1. Description
Type (mono, dual, mixed)
Number of filters
Filter control (constant, declining)
Surface wash type (rotary, fixed)
2. Dimensions
Length or diameter:
Width:
Total surface area:
3. Media design conditions (depth, effective size, uniformity coefficient):
4. Backwash
Backwash initiation (headless, turbidity, time):
Sequence (surface wash, air scour, flow ramping up/down, filter-to-waste):
173
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B. Major Unit Process Information (cont.)
3. Filtration (cont.):
Topic
5. Major Unit
Process
Evaluation
6. Other
Design
Information
Description Information
Selected Process Parameter(s);
Surface loading rate
Assigned process capacity
174
-------
DESIGN DATA
B. Major Unit Process Information (cont.)
4. Disinfection:
Topic
1. Description
2. Dimensions
3. Major Unit
Process
Evaluation
5. Other
Design
Information
Description
Contact type (clean/veil, storage)
T10/T factor (see Table 4-4 or use
tracer study results)
Information
Length or diameter:
Width:
Minimum operating depth:
Total volume:
Volume adjusted for T10/T:
Selected Process Parameters:
Disinfectant (chlorine, chloramines)
Max. disinfectant residual (mg/L)
Maximum pH
Minimum temperature (°C)
Required Giardia inactivation
Required virus inactivation
Assigned process capacity
175
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C. Miscellaneous Equipment Information
1. Miscellaneous Equipment/Unit Processes:
Equipment/Process
1. Intake Structure
• Location
• Size of screen opening
• Design limitations
2. Presedimentation
• Detention time
• Flexibility to bypass
• Chemical feed capability
• Design limitations
3. Rapid Mix
• Type (mech., inline)
• Chemical feed options
• Mixing energy
• Design limitations
Description/Information
176
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DESIGN DATA
C. Miscellaneous Equipment Information (cont.)
1. Miscellaneous Equipment/Unit Processes (cont.):
Equipment/Process
4. Backwash/Sludge
Decant Treatment
• Description
• Recycle practices
• Design limitations
5. Sludge Handing
• Onsite storage volume
• Long-term disposal
• Design limitations
Description/Information
177
-------
C. Miscellaneous Equipment Information (cont.)
2. Chemical Feed Equipment:
Chemical Feed System
• Chemical name/characteristics
(e.g., product density, strength)
• Purpose (e.g., coagulant, filter
aid, T&O, disinfection)
• Number/type feed pumps
1.
2.
3.
4.
5.
6.
Capacity
(m Urn in)
• Design
• Operating
Range
Comments
• Dose control (e.g., flow paced)
• Manufacturer's information
• Calibration method
• Design issues
178
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DESIGN DATA
C. Miscellaneous Equipment Information (cont.)
3. Instrumentation:
On-Line Instrumentation
• Type (e.g., turbidimeter, flow
meter, particle counter, pH
monitor, chlorine monitor)
• Manufacturer
1.
2.
3.
4.
5.
6.
7.
Location
• Process
stream
Comments
• Calibration
• Alarm/shutdown capability
• Design issues
179
-------
C. Miscellaneous Equipment Information (cont.)
4. Pumping:
Flow Stream Pumped
• Location
• Number of pumps
• Rated capacity
1.
2.
3.
4.
5.
6.
7.
Pump Type
• Turbine
• Centrifugal
Comments
• Flow control method
• Design issues
• Source of rated capacity (name plate,
specifications, flow meter)
180
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DESIGN DATA
A. Process Control Strategies and Communication
Describe the process control strategy used by the staff and associated communication mechanisms.
Topic
1 . Process Control Strategy
• Does the staff set specific
performance targets? Are they
posted?
• Who sets process control
strategies and decisions?
• Are appropriate staff members
involved in process control
and optimization activities?
2. Communication Methods
• Does the staff have routine
plant/shift meetings?
• How is communication
conducted among operations,
maintenance, and lab?
• Does the staff develop and
follow operational procedures?
Description/Information
181
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B. Process Control Procedures
Describe specific process control procedures for the following available processes.
Process
1. Intake Structure
• Flexibility to draw water from
different locations & depths
• Operational problems
2. Pumping/Flow Control
• Flow measurement and control
• Proportioning to multiple units
• Operational problems
3. Presedimentation
• Chemicals used/dose control
• Monitoring (turbidity)
• Sludge removal
• Operational problems
4. Preoxidation
• Chemicals used/dose control
• Monitoring (residual)
• Operational problems
Description/Information
182
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DESIGN DATA
Describe specific process control procedures for the following available processes (cont.)
Process
5. Coagulation/Softening
• Chemicals used/feed location
• Dose control (adjustment for
flow changes; adjustment for
water quality - jar testing,
streaming current, pilot filter)
• Monitoring (turbidity, particle
counting)
• Operational problems
6. Flocculation
• Mixing energy adjustment
• Use of flocculant aid
• Monitoring
• Operational problems
7. Sedimentation
• Performance objective/
monitoring (turbidity)
• Sludge removal (control,
adjustment)
• Operational problems
Description/Information
183
-------
Describe specific process control procedures for the following available processes (cont.)
Process
8. Filtration
• Performance objective/
monitoring (turbidity, particles,
headless, run time)
• Rate control due to demand,
filter backwash
• Use of filter aid polymer
• Basis for backwash initiation
(turbidity, particles, headless,
time)
• Backwash procedures (wash
sequence, duration and rates,
basis for returning filter to
service)
• Filter/media inspections
(frequency and type)
• Operational problems
9. Disinfection
• Performance objective/
monitoring (residual, CT)
• CT factors (pH, minimum depth
of contactor, T10/T, maximum
residual)
• Operational problems
Description/Information
184
-------
DESIGN DATA
Describe specific process control procedures for the following available processes (cont.)
Process
10. Stabilization
• Chemical used/feed location
• Performance objective/
monitoring (pH, index)
• Operational problems
1 1 . Decant Recycle
• Duration, % of plant flow
• Type of treatment (settling,
chemical addition)
• Operational problems
12. Sludge Treatment
Description/Information
185
-------
C. Data Management
Describe data collection and management approaches and tools used by plant staff.
Topic
1 . Data Collection
• Type of forms used (water
quality testing, shift rounds,
plant log)
• Computer (SCADA, database)
2. Data Application
• Development of daily, monthly
reports
• Development of trend charts
Description/Information
D. Problem Solving and Optimization Activities
Describe specific approaches and tools used to solve problems or optimize plant processes.
Topic
1 . Problem Solving/Optimization
• Use of special studies
• Pilot plant
• List recent and ongoing
problem solving/optimization
activities
• Available resources (technical
assistance providers, training,
manuals of practice)
Description/Information
186
-------
DESIGN DATA
E. Complacency and Reliability
Describe specific approaches used to address complacency and reliability issues in the plant.
Topic
1. Complacency
• How does staff respond to
unusual water quality
conditions?
• Does staff have an emergency
response plan? How does staff
train for unusual conditions or
events?
2. Reliability
• Does staff capability to make
process control decisions
exist at more than one level?
Description/Information
187
-------
F. Laboratory Capability
1. Describe available analytical testing capability.
Analytical Capability
• Color
• Jar test
• Particle counting
• pH
• Solids (dissolved)
• Taste and odor
• Temperature
• Turbidity
• Aluminum
• Calcium
• Fluoride
• Hardness
• Iron
• Magnesium
• Manganese
• Sodium
• Alkalinity
• Ammonia Nitrogen
• Nitrite/nitrate
• Phosphate
• Sulfate
• Chlorine residual
• Bacteriological
• Disinfection byproducts
Capability S
Description/Comments
188
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DESIGN DATA
2. Describe laboratory space/equipment and procedures.
Process
Lab Space and Equipment
• Does adequate lab space exist?
• Do adequate equipment and
facilities exist?
Lab Procedures
• Is testing conducted following
standard procedures?
• Where is lab data recorded?
• Describe quality control
procedures.
Equipment Calibration
• Describe procedure for
calibrating turbidimeters.
• Describe procedures for
calibrating other equipment
(continuous chlorine and pH
monitors).
Description/Information
189
-------
A. Maintenance Program
Describe the plant maintenance program.
Topic
1 . Preventive Maintenance
• Describe equipment inventory
method (cards, computer).
• Describe maintenance scheduling
method (daily, weekly, monthly,
annual).
2. Corrective Maintenance
• Describe the work order system
(issuing orders/documentation).
• Describe priority setting
(relationship to process control
and plant performance needs).
• List major equipment out of
service within last 6 months.
3. Predictive Maintenance
• Describe methods used to
predict maintenance needs
(vibration, infrared analysis).
4. Housekeeping
• Does poor housekeeping detract
from plant performance/image?
Description/Information
190
-------
MAINTENANCE DATA
B. Maintenance Resources
Describe the available maintenance resources at the plant.
Topic
1 . Equipment Repair and Parts
• Are critical spare parts stored at
the plant?
• Can vendors provide quick
response to spare parts needs?
• What is the policy on parts
procurement by staff?
2. Maintenance Expertise
• Describe staff expertise
(mechanical, electrical,
instrumentation).
• Does the staff use any contract
maintenance services? How
responsive are they to needs?
• Does staff develop and use
maintenance procedures?
3. Work Space and Tools
• Does the plant have adequate
work space and tools to perform
maintenance tasks?
4. Performance Monitoring
• How is maintenance performance
measured (time to complete
task, work order backlog)?
Description/Information
191
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A. Historical Water Production Data
1. Use the following table to determine the peak instantaneous operating flow for the plant.
Month/Year
Maximum
Daily Flow
Operating
Time Per Day
Flow During
Operation (1)
Instantaneous Peak
Flow (2)
(1)
If a plant operates less than 24 hr/day, flow during operation can be determined from the
equation below:
Q 24 hr
QA = Average flow during operation
QT = Total flow in 24-hour period
T = Time of plant operation, hours
(2) Peak instantaneous flow through a plant is often different than the average flow due to changing
water demands that the plant must meet. The peak instantaneous flow during a day can
sometimes be obtained from plant logs (e.g., raw pump operation, rate change time and flow).
192
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FIELD EVALUATION DATA
B. Water Usage
1. Determine the water usage per capita based on water production records and population served. Water
usage statistics for the United States are shown in the table below.
n _Qi
Qc = Usage per capita per day
QT = Total flow in 24-hour period
P = Population served
Population
QcAvg.
Qc Peak
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Use (qpcpd)
191
134
191
154
175
188
120
124
146
160
180
163
154
115
131
144
128
147
81
165
119
136
105
127
131
164
State
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Puerto Rico
Virgin Islands
Use (qpcpd)
174
306
85
131
184
166
107
114
127
173
164
128
115
148
121
148
176
255
80
119
217
96
118
188
115
63
Source: Solley, W.B. Preliminary Estimates of Water Use in the United States, 1995, U.S.
Geological Survey (1997).
193
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2. Determine unaccounted for water based on monthly or annual water production and meter records.
Unaccounted for water typically varies from 10 to 12 percent for new systems and 15 to 30 percent for older
systems (Metcalf and Eddy, Inc. 1991).
Q =(QT-QM)XIOO
QT
Qo/0 = % unaccounted
QT = Total plant water production for month or year
QM = Total metered water for month or year
QT
QM
Q%
3. Determine backwash water percent based on volume of water filtered and volume of water used for
backwash. Typically, the amount of water used for backwash ranges for 2 to 6 percent for conventional
plants. Higher percentages can occur for direct filtration plants.
BW =
VF
BW% = % backwash water
VF = Volume of water filtered
VBW = Volume of water used for backwash
VF
VBW
BW%
194
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FIELD EVALUATION DATA
C. In-Plant Studies
Describe results of in-plant studies conducted during the CPE.
Topic
1 . Filter Media Evaluation
• Check media depth and type.
• Check media condition (presence
of chemicals/debris, mudballs,
worn media).
• Check support gravel level
(variation of less than 2 inches
acceptable).
2. Backwash Evaluation
• Check backwash rate (measure
rise rate in the filter versus time
and convert to backwash rate;
> 15 gpm/ft2 acceptable).
• Check bed expansion
> 20 percent acceptable).
Description/Information/Findings
195
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C. In-Plant Studies (cont.)
Describe results of in-plant studies conducted during the CPE.
Topic
2. Backwash Evaluation (cont.)
• Observe backwash procedure
(flow distribution, ramping of flow
rate, turbidity of water at end of
backwash).
3. Coagulant Dosage Evaluation
• Verify reported dose with actual;
measure liquid or dry feed rate
(Ib/min, mL/min) and convert to
dose (mg/L).
4. Turbidity Meter Evaluation
• Check meter calibration or
compare with calibrated meter.
Description/Information/Findings
196
-------
FIELD EVALUATION DATA
C. In-Plant Studies (cont.)
Describe results of in-plant studies conducted during the CPE.
Topic
Description/Information/Findings
197
-------
A. Interview Guidelines
The following interview guidelines are provided to assist CPE providers with the interview process.
1. Conduct interviews with one staff person at a time in a private location.
• It is important to create a comfortable environment for the interview process to take place. Con-
fidentiality of the interview should be explained.
2. Keep the interview team size small.
• The number of people included on each interview team should be kept to a minimum (e.g., 1 to 3) to
avoid overwhelming the person being interviewed. If more than one person is included on the team,
one person should be assigned as the lead interviewer.
3. Allow 30 to 45 minutes for each interview.
• Interview times will vary depending on the personality of the individual being interviewed and the
number and type of issues involved. It is the responsibility of the interviewer to maintain the focus on
performance-related issues. Interviews can easily be detracted by individuals who find an "open ear"
for presenting grievances.
4. Explain the purpose of the interview and use of the information.
• It is important for the people being interviewed to understand that any information obtained from this
process is only used to support identification of factors limiting performance (i.e., areas impacting
performance). The interview information is not used to place blame on specific individuals or
departments.
5. Conduct interviews after sufficient information has been gathered from CPE activities.
• Utilize results and observations gained from the plant tour, performance assessment, major unit
process evaluation, and data collection activities to identify areas of emphasis during the interviews.
6. Progress through the interview in a logical order.
• For example, if an administrator is being interviewed, focus questions on administrative support, then
on design issues, followed by operation and maintenance capabilities.
7. Ask relevant questions with respect to staff area of involvement.
• For example, when interviewing maintenance personnel, ask questions related to relevant topics such
as maintenance responsibilities, communication with supervisors, and administrative support for
equipment.
8. Ask open-ended questions.
• For example, a question such as "Are you aware of any design deficiencies with the current plant? "
would provide better information than a question like "Do you think that the flocculation basin provides
sufficient detention time for flocculation?".
198
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INTERVIEW DATA
9. Ask the questions: don't give the answers.
• The purpose of the interview is to gain the perspective of the person being interviewed. Ask the
question and wait for the response (i.e., don't answer your own question based on information you may
have received from previous activities). Rephrasing the question may sometimes be necessary to
provide clarity.
10. Repeat a response to a question for clarification or confirmation.
• For example, the interviewer can confirm a response by stating, "If I understand you correctly, you
believe that the reason for poor plant performance during April was due to excessive algae growth in
the source water."
11. Avoid accusatory statements.
• Accusatory statements will likely lead to defensiveness by the person being interviewed. Rather, if an
area of concern is suspected, ask questions that can confirm or clarify the situation.
12. Use the interview to clarify or confirm field information.
• For example, if performance problems occurred during one month of the past year, ask questions to
clarify the perceived reasons for these problems.
13. Note specific responses that support factor identification.
• During or following the interview, the interviewer may want to note or underline specific responses that
support the identification of possible factors limiting performance. This summary can then be used
during team debriefing and factor identification meetings.
199
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B. Personnel Interview Form
Name Title
Time at plant Years of experience
Education/training/certification
Interview notes (concerns, recommendations in administration, design, operation, and maintenance):
200
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EXIT MEETING
A. Attendance List
Utility Name
Date
Name
Title/Position
Telephone No.
201
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B. Mutiple Barrier Concept for Microbial Contaminant Protection
Coagulant
Addition
'Turbidity'
Goal
v< 0.1 NTU,
Variable
Quality
Source
Water
r, , • -
T
•T^:
Flocculation/ Sedimentation
Barrier
m •
• * 4
* m *
• « •
Disinfectant \
Addition
* .
Filtration
Barrier
•
•
•
0
'I-nal
\
a-
Fnished
Disinfection
Barrier
Given a variable quality source water, the treatment objective is to produce a consistent, high quality finished
water.
Protozoan parasites, such as Giardia and Cryptosporidium, are found in most source waters; however, it is
difficult to quantify their presence and assess their viability.
Microbial pathogens in the source water, such as protozoan parasites, bacteria, and viruses, can be
physically removed as particles in treatment processes and inactivated through disinfection.
Multiple barriers are provided in a treatment plant to remove or inactivate microbial pathogens.
Key treatment barriers include flocculation/sedimentation, filtration, and disinfection.
Since measurement of protozoan parasites is difficult, surrogate parameters, such as turbidity, particle
counting, and pathogen inactivation, are used to assess the performance of each barrier.
202
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EXIT MEETING
C. Optimization Performance Criteria
A summary of performance criteria for surface water treatment plants to provide protection against microbial
contaminants is presented below:
1. Minimum Data Monitoring Requirements
• Daily raw water turbidity
• Settled water turbidity at 4-hour time increments from each sedimentation basin
• On-line (continuous) turbidity from each filter
• One filter backwash profile each month from each filter
2. Individual Sedimentation Basin Performance Criteria
• Settled water turbidity less than 1 NTU 95 percent of the time when annual average raw water turbidity
is less than or equal to 10 NTU
• Settled water turbidity less than 2 NTU 95 percent of the time when annual average raw water turbidity
is greater than 10 NTU
3. Individual Filter Performance Criteria
• Filtered water turbidity less than 0.1 NTU 95 percent of the time (excluding 15-minute period following
backwashes) based on the maximum values recorded during 4-hour time increments
• Maximum filtered water measurement of 0.3 NTU
• Initiate filter backwash immediately after turbidity breakthrough has been observed and before effluent
turbidity exceeds 0.1 NTU.
• Maximum filtered water turbidity following backwash of 0.3 NTU
• Maximum backwash recovery period of 15 minutes (i.e., return to less than 0.1 NTU)
• Maximum filtered water measurement of less than 10 particles (in the 3 to 18 urn range) per milliliter (if
particle counters are available)
4. Disinfection Performance Criteria
• CT values to achieve required log inactivation of Giardia and virus
203
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-------
Appendix G
Example CPE Report
205
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Results of the
Comprehensive Performance Evaluation
of Water Treatment Plant No. 005
Prepared by:
Prepared for:
206
-------
Site Visit Information
Mailing Address:
Date of Site Visit:
Utility Personnel:
CPE Team:
207
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Table of Contents
Page No.
INTRODUCTION 210
FACILITY INFORMATION 211
PERFORMANCE ASSESSMENT 212
MAJOR UNIT PROCESS EVALUATION 216
PERFORMANCE LIMITING FACTORS 218
Alarms (Design) A 218
Process Flexibility (Design) A 218
Policies (Administration) A 218
Insufficient Time on the Job (Operation) A 218
Process Instrumentation/Automation (Design) B 218
Presedimentation (Design) B 219
EVALUATION FOLLOW-UP 219
REFERENCES 219
208
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List of Figures
FIGURE 1 Comprehensive Performance Evaluation methodology.
FIGURE 2 Water treatment flow schematic.
FIGURE 3 Daily maximum plant influent water turbidity.
FIGURE 4 Daily maximum finished water turbidity.
FIGURE 5 Filter effluent turbidity profile after backwash.
FIGURE 6 Major unit process evaluation.
FIGURE 7 Process evaluation for individual treatment unit.
Page No.
210
211
213
214
215
216
217
List of Tables
TABLE 1 Frequency Analysis of Raw Water Turbidity
TABLE 2 Frequency Analysis of Finished Water Turbidity
213
215
209
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Introduction
The Composite Correction Program (CCP) (1) is an
approach developed by the U. S. Environmental
Protection Agency and Process Applications, Inc. to
improve surface water treatment plant performance
and to achieve compliance with the Surface Water
Treatment Rule (SWTR). Its development was
initiated by Process Applications, Inc. and the State of
Montana (2), who identified the need for a program to
deal with performance problems at their surface-
supplied facilities. The approach consists of two
components, a Comprehensive Performance Evalua-
tion (CPE) and Comprehensive Technical Assistance
(CTA).
The methodology followed during a CPE is described
in Figure 1. A comprehensive assessment of the unit
process design, administration and maintenance
support is performed to establish whether a capable
plant exists. Additionally, an assessment is made on
the plant staffs ability to apply process control
principles to a capable plant to meet the overall
objective of providing safe and reliable finished water.
The results of this assessment approach establish
the plant capability and a prioritized set of factors
limiting performance. Utility staff can address all or
some of the identified factors, and improved
performance can occur as the result of these efforts.
A CTA is used to improve performance of an existing
plant when challenging or difficult-to-address factors
are identified during the CPE. Therefore, the CCP
approach can be utilized to evaluate the ability of a
water filtration plant to meet the turbidity and
disinfection requirement of the SWTR and then to
facilitate the achievement of cost effective compli-
ance.
In recent years, the CCP has gained prominence as a
mechanism that can be used to assist in optimizing
the performance of existing surface water treatment
plants to levels of performance that exceed the
requirements in the SWTR. The current standards
do not always adequately protect against some
pathogenic microorganisms, as evidenced by recent
waterborne disease outbreaks. Producing a finished
water with a turbidity of <0.1 NTU provides much
better protection against pathogens like
Cryptosporidium (3,4,5, 6,7,8,9,10,11), the
microorganism responsible for a large outbreak of
Cryptosporidiosis in Milwaukee in April 1993, where
403,000 people became ill and at least 79 people
died.
USEPA has chosen to use the CCP approach to
evaluate selected surface water treatment plants in
this region. Water Treatment Plant No. 005 was
selected as the first candidate for a CPE. This plant
has experienced difficulties with continuously meeting
the turbidity requirements of the SWTR, and the
water system manager and staff expressed interest in
receiving assistance with correcting this situation.
FIGURE 1. Comprehensive Performance Evaluation methodology.
Safe/Reliable Finished Water
Operation (Process Control)
Capable Rant
Design
210
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The following report documents the findings of the
CPE conducted at Water Treatment Plant No. 005.
The CPE identifies and prioritizes the reasons for
less-than-optimum performance. The CPE may be
followed by the second phase of the CCP, Com-
prehensive Technical Assistance (CTA), if appro-
priate.
Facility Information
A flow schematic of Water Treatment Plant No. 005 is
shown in Figure 2. The water source for the plant is
Clear Creek. Staff reported that turbidity in the creek
reaches a maximum level of 50 - 80 NTU. The Clear
Creek Basin can be characterized as mountainous
and forested. Sources of potential contamination
include wildlife and human sources (e.g., recreation
use, camping etc.).
The intake for the treatment plant is located in Clear
Creek upstream of a small diversion dam. The
turbidity in the raw water pipeline has not been
recorded regularly since the treatment plant began
operation. Limited raw water pipeline turbidity data
from before plant start-up was reviewed during the
CPE. The data indicate that turbidity in the raw water
pipeline was typically low (i.e., < 1.5 NTU) with some
peaks in the spring that were less than 5 NTU. About
100 cubic yards of sediment is dredged and removed
at two-year intervals in the vicinity of the intake,
upstream of the diversion dam. Settling of par-
ticulates at this location may partially account for the
low raw water turbidity values observed. The utility is
also constructing a dam upstream of the intake; and,
as a result, even less raw water turbidity variations
are expected in the future.
FIGURE 2. Water treatment flow schematic.
Intake
Diversion Dam
Filter to Waste
/
r\^ri
l/^^
Upflow
/ Clarifier (typ)
Equalization
Basin
To Sewer
_ Spent _
Backwash
static rn
Mixer
Clearwell
-i (under floor)
ftt
I
i
T
n
Filter
(typ)
/^ — Polymer '
r
X
8
Q-*
J Act. Carbon
m
Soda Ash
Dhlorine Gas
- Backwash
Pump (typ)
Raw Water PS
To Distribution
System
211
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About 6 cfs of water flows by gravity from the intake
through about four miles of 14-inch diameter ductile
iron pipe to a utility-owned hydroelectric power
generating station near the water treatment plant.
After the hydroelectric station, about 4 cfs flows back
into Clear Creek and the remaining 2 cfs flows
through two large presedimentation ponds. Detention
time through these ponds is estimated to be about 14
days. A raw water pump station located beside the
lower pond includes four constant speed raw water
pumps, each with a 700 gpm capacity.
The amount of water that can be run through the
presedimentation ponds and discharged to the creek
is limited by the capacity of the Parshall flume on the
overflow of the lower pond. Also, there are no
provisions to bypass an individual pond to reduce the
detention time. The ponds can be bypassed by
directing the raw water to the pump station intake;
however, this results in the bypassing of the
hydroelectric station. The utility is planning to install
another pipeline from the hydroelectric station to the
raw water pumping station before the spring runoff
occurs. This will allow the ponds to be bypassed
without interfering with the hydroelectric station
operation.
The water treatment plant began operation in August
1996. Prior to that, chlorination was provided after
the settling ponds before entering the distribution
system. The plant has a reported firm design
capacity of about 3 MGD. Major treatment
components include chemical feed equipment, four
package treatment trains consisting of an upflow
clarifier and filter basins, a 110,000 gallon clean/veil,
and a 600,000 gallon finished water storage tank.
Each of the upflow clarifier and filter units has a
reported capacity of 1 MGD. The plant is designed to
operate at 1 MGD incremental flow rates with one raw
water pump dedicated to each treatment train in
operation. Unique characteristics of the plant are
summarized as follows.
• Large presedimentation ponds prior to treatment.
• Static mixer for coagulant mixing.
• Chemical feed capability: alum, polymer, soda
ash, powdered activated carbon, chlorine.
• Upflow clarifiers with gravel media (1 to 5 mm
size).
• Mixed media filters.
• Filter-to-waste capability set by a common control
valve to 1 MGD. (NOTE: This flow rate is not
easily adjusted and limits the flexibility to change
the individual treatment train flow rate to a value
other than 1 MGD.)
• Two continuously monitoring particle counters on
filter effluent (one shared by two trains).
• Clean/veil with intra-basin baffles
Performance Assessment
During the CPE, the capability of the Water Treat-
ment Plant No. 005 was evaluated to assess whether
the facility, under existing conditions, could comply
with the turbidity and disinfection requirements that
are used to define optimized performance. Optimized
performance, for purposes of this CPE, represents
performance criteria that exceeds the SWTR
requirements. Optimized performance would require
that the facility take a source water of variable quality
and consistently produce a high quality finished water.
Multiple treatment processes (e.g., flocculation,
sedimentation, filtration, disinfection) are provided in
series to remove particles, including microbial
pathogens, and provide disinfection to inactivate any
remaining pathogens.
Water Treatment Plant No. 005 utilizes a package
water treatment process that includes combined
flocculation/sedimentation in an upflow clarifier and
filtration. Each of the available processes represents
a barrier to prevent the passage of microbial patho-
gens through the plant. By providing multiple barri-
ers, any microorganisms passing one process can be
removed in the next, minimizing the likelihood of
microorganisms passing through the entire treatment
system and surviving in water supplied to the public.
The role of the water treatment operator is to optimize
the treatment processes (i.e., barriers) under all
conditions because even temporary loss of a barrier
could result in the passage of microorganisms into
the distribution system and represents a potential
health risk to the community.
A major component of the CPE process is an
assessment of past and present performance of the
plant. This performance assessment is intended to
identify if specific unit treatment
212
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processes are providing multiple barrier protection
through optimum performance. The performance
assessment is based on data from plant records and
data collected during special studies performed
during the CPE.
Specific turbidity performance targets were used
during this assessment. These specific performance
targets include:
• Sedimentation - turbidity of less than 1 NTU 95
percent of the time, since average annual raw
water turbidity is less than 10 NTU.
• Filtration - individual filter turbidity less than 0.1
NTU 95 percent of the time (excluding 15-minute
period following backwash); also, maximum
filtered water turbidity following backwash of 0.3
NTU.
Table 1. As indicated, the raw water turbidity is less
than or equal to 4 NTU 95 percent of the time.
Maximum daily plant influent turbidity varied from less
than 1 NTU to 10 NTU, as shown in Figure 3.
TABLE 1. Frequency Analysis of Raw Water
Turbidity
Percentile
50
75
90
95
Average
Raw Water
NTU*
2.2
3.0
3.6
4.0
2.6
*Daily maximum value
• Disinfection - CT values to achieve required log
Giardia cyst and virus inactivation.
A plant influent turbidimeter and strip chart recorder
are provided, but the plant operators do not routinely
record daily influent water turbidity in their operating
log. The plant influent turbidity strip charts for the
past year were reviewed during the evaluation. A
frequency analysis of these data is summarized in
The turbidimeter is located a long distance from the
influent pipe. A significant number of brief (a few
minutes to less than 1 hour) turbidity spikes were
noted on the strip chart. A special study would be
required to determine the cause of these brief influent
turbidity spikes. Influent turbidity during the CPE was
less than 1 NTU.
FIGURE 3. Daily maximum plant influent water turbidity.
10.00
213
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The finished water turbidimeter is located at the outlet
of the 600,000 gallon finished water storage tank.
This meter has a strip chart recorder, and operators
routinely record this data for water quality reporting
purposes.
The plant operators do not routinely sample and
measure turbidity after the upflow clarifiers. During
the CPE, turbidities of 0.56 to 0.71 NTU were
measured between the upflow clarifier and the filter
over a two-hour period. During the same period the
plant influent turbidity ranged from 0.5 to 0.7 except
for a 15-minute spike from 3 to 10 NTU after a brief
filter shutdown. Because of the low influent water
turbidity conditions during the CPE and the lack of
historical turbidity data at the clarifier outlet, the ability
of the plant to meet the 1 NTU turbidity goal on a
long-term basis could not be determined.
The plant does not have on-line turbidimeters for
monitoring turbidity following individual filters, and
plant operators do not routinely collect grab samples
to measure turbidity at this location. Two on-line
particle counters are available for monitoring filter
performance; however, staff have experienced
operating problems with at least one of the units. To
assess historical plant performance, turbidity values
from after the treated water storage tank were used.
The daily maximum finished water turbidity for the
previous 12 months is shown in Figure 4. The results
of a frequency analysis of the finished water data are
shown in Table 2 and indicate that 95 percent of the
time the filtered water turbidity was less than
0.87 NTU.
During several months, plant performance did not
meet the turbidity requirement of the SWTR (i.e.,
<0.50 NTU 95 percent of the time on monthly basis).
From April through June, filtered water turbidity
consistently exceeded the regulated limit of 0.50
NTU. Plant staff reported that this period of poor
performance was due to a bad batch of alum and
poor water quality from the ponds. A large amount of
algae or other filamentous material from the ponds
caused clogging problems on the media support
screens of the upflow clarifiers for several weeks.
This material was cleaned manually with great
difficulty, and during the worst period cleaning was
required on a daily frequency. Hand-cleaned screens
have been installed on the raw water pump intakes in
the lower pond to assist with removing this material
before it reaches the treatment units. It is also
possible that post flocculation may have occurred in
the clean/veil and finished water storage tank during
this period.
FIGURE 4. Daily maximum finished water turbidity.
2.00
214
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TABLE 2. Frequency Analysis of Finished Water
Turbidity
Percentile
50
75
90
95
Average
Finished Water
NTU*
0.16
0.32
0.55
0.87
0.33
*Daily maximum value
Although significant improvement in performance has
recently occurred, the plant did not achieve the
optimized filtered water turbidity target of less than
0.1 NTU during the past year. This performance
allows an increased opportunity for pathogens, such
as Cryptosporidium oocysts, to pass into the public
water supply.
During the CPE a special study was conducted on the
filter media, backwash procedure, and performance
of a filter following a backwash. Prior to
backwashing, filter unit #2 was drained to allow
physical observation of the filter media. The total
depth of the mixed media was consistently about 31.5
inches. Of this mixed media depth, about 18 inches
was anthracite. Inspection of the media at and below
the surface showed that the media was very clean.
During the backwash, a filter bed expansion of 21.8
percent was calculated, which is within the acceptable
range of 20 to 25%.
Immediately after completion of the filter backwash,
the filtered water turbidity was measured periodically
for about 35 minutes. These data are shown in
Figure 5. The current procedure is to filter to waste
for ten minutes after the end of the backwash cycle.
As indicated by the performance graph, the filter did
not meet the backwash optimization criteria of a
maximum turbidity spike of 0.3 NTU and return to
less than 0.1 NTU within 15 minutes.
In summary, performance data for the last year show
that Water Treatment Plant No. 005 has not been in
compliance with the SWTR on a consistent basis. In
addition, the plant has not met the optimized
performance goal of 0.1 NTU for filtered water.
Consequently, this performance assessment
indicates that the water system is at risk of passing
microbial pathogens to consumers.
FIGURE 5. Filter effluent turbidity profile after backwash.
0.45
0.40 - -
0.00-t
15 20
Minutes After Backwash
25
30
35
215
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Major Unit Process Evaluation
Major unit processes were assessed with respect to
their capability to provide consistent performance and
an effective barrier to passage of microorganisms on
a continuous basis. The performance goal used in
this assessment for the filtration process was a
settled water turbidity of less than 2 NTU and a
filtered water turbidity of less than 0.1 NTU.
Capabilities of the disinfection system were based on
the USEPA guidance manual (12) requirements for
inactivation of Giardia and viruses.
Since the plant's treatment processes must provide
an effective barrier at all times, a peak instantaneous
operating flow is typically determined. The peak
instantaneous operating flow represents the
maximum flow rate that the unit processes are
subjected to, which represents the hydraulic con-
ditions where the treatment processes are the most
vulnerable to the passage of microorganisms. If the
treatment processes are adequate at the peak
instantaneous flow, then the major unit processes are
projected to be capable of providing the necessary
effective barriers at lower flow rates.
Water Treatment Plant No. 005 has a maximum raw
water pumping capacity of 4 MGD. The plant was
designed for a maximum treatment capacity of 3
MGD with one treatment unit out of service. A peak
instantaneous flow rate of 3 MGD is used for the
major unit process evaluation, based on the highest
instantaneous flow rate reported by the staff.
Major unit process capability was assessed by
projecting treatment capacity of each major unit
process against the peak instantaneous flow rate.
The major unit process evaluation for the entire
treatment plant is shown in Figure 6. The unit
processes evaluated are shown on the left side of the
graphs, and the flow rates against which the
processes were assessed are shown across the top.
Horizontal bars on the graph represent the projected
peak capability of each unit process to achieve the
desired optimized process performance. These
capabilities were projected based on the combination
of treatment processes at the plant, the CPE team's
experience with other similar processes, industry
guidelines, and regulatory standards. The shortest
bar represents the unit process which limits plant
capability the most relative to achieving the desired
plant performance.
FIGURE 6. Major unit process evaluation.
0.0 0.5
1.0
Water Flow Rate (MGD)
1.5 2.0 2.5
3.0
3.5
4.0
Floe/Sedimentation (1)
Filtration (2)
Disinfection (3)
Peak
Instantaneous
Flow
(1) Surface area = 280 ft2; rated at 8.0 gpm/ft2, upflow clarifier with rock gravel media
(2) Surface area = 560 ft2; rated at 4 gpm/ft2; mixed media
(3) Volume = 98,000 gal; total 3-log Giardia inactivation/removal required; assume 2.5-log
removal allowed through conventional plant credit and 0.5-log required by disinfection;
pH = 7.5; temp = 0.5°C; chlorine residual = 1.6 mg/L; T10/T = 0.7; 3 ft minimum
clean/veil depth
216
-------
The major unit processes evaluated were the upflow
clarifiers (flocculation and sedimentation), filtration,
and disinfection processes. Criteria used to assess
each major unit process are described in the notes
below the graph.
The upflow clarifiers were rated based on their
surface overflow rate. Typically, conventional
sedimentation basin capability is rated based on a
surface overflow rate of 0.5 to 0.7 gpm/ft2. A surface
overflow rate of 10 gpm/ft2 is used by the package
plant manufacturer for the design rating of their
upflow clarifier units. Because of the combined
flocculation and sedimentation function and the short
detention time of these units, they were rated based
on an overflow rate of 8 gpm/ft2. This produced a
combined flocculation/sedimentation capability rating
of 3.23 MGD when using all four treatment units.
The filtration process was rated based on a loading
rate of 4 gpm/ft2 and use of all four filters. These
criteria resulted in a combined filtration capability of
3.23 MGD.
The disinfection process was assessed based on
USEPA Surface Water Treatment Rule requirements
for inactivation of 3-log of Giardia cysts and 4 log of
viruses. The Giardia removal/inactivation is the most
stringent criteria; consequently, it was used as the
basis of the disinfection evaluation. A well-operated
conventional filtration plant is allowed a 2.5-log
removal credit for Giardia cysts, and the remaining
0.5-log removal is achieved by meeting specified CT
requirements associated with chemical disinfection.
CT is the disinfectant concentration (C) in mg/L multi-
plied by the time (T) in minutes that the water is in
contact with the disinfectant. The required CT value
was obtained from the USEPA guidance manual (3),
using typical plant values for free chlorine residual
(i.e., 1.0 mg/L) and pH (i.e., 7.5) and a worst case
water temperature of 0.5°C. The volume of the clear-
well was adjusted for the minimum operating depth of
3 feet. A T10/T ratio of 0.70 was used because of the
superior baffling conditions in the clean/veil. Under
this scenario, the disinfection process is capable of
treating 3.44 MGD, using a required free chlorine CT
value of 46 mg/L-min.
The results of the major unit process evaluation
indicate that the plant should be capable of treating
the peak instantaneous flow rate of about 3.2 MGD
with four treatment trains in service (i.e., 0.8 MGD per
train). However, the control of the plant is set up so
that each treatment train operates at a constant flow
rate of 1 MGD (see Figure 7), and flexibility does not
exist to easily operate each train at lower flow rates
without modifying the filter to waste piping from the
filters.
FIGURE 7. Process evaluation for individual treatment unit.
0.0
Water Flow Rate (MGD)
0.5 1.0
1.5
Floe/Sedimentation (1)
Filtration (2)
Peak
Instantaneous
Flow
(1) Surface area = 70 ft2; rated at 8.0 gpm/ft2; upflow clarifier with gravel media
(2) Surface area = 140 ft2; rated at 4 gpm/ft2; mixed media
217
-------
The major unit process evaluation indicates that the
current practice of operating individual treatment units
at a constant flow rate of 1 MGD, as required by the
design and control system, may be contributing to the
less-than-optimum performance of the
flocculation/sedimentation and filtration processes.
Performance Limiting Factors
The areas of design, operation, maintenance, and
administration were evaluated in order to identify
factors which limit performance. These evaluations
were based on information obtained from the plant
tour, interviews, performance and design
assessments, special studies, and the judgment of
the evaluation team. Each of the factors was
classified as A, B, or C according to the following
guidelines:
A— Major effect on a long term, repetitive basis
B— Minimal effect on a routine basis or major
effect on a periodic basis
C — Minor effect
The A and B factors were prioritized as to their
relative impact on performance and are summarized
below. In developing this list of factors limiting
performance, 50 potential factors were reviewed; and
their impact on the performance of Water Treatment
Plant No. 005 was assessed. The evaluation team
identified six factors that are limiting plant
performance. Numerous other factors were not felt to
be affecting plant performance. The factors and the
findings that support their selection are summarized
below in prioritized order.
Alarms (Design) A
• The plant does not have alarm and shutdown
capability on chlorine feed, chlorine residual,
influent turbidity and finished water turbidity.
Process Flexibility (Design) A
• Inability to automatically change the filter to waste
flow rate to values other than 1 MGD. (NOTE:
This lack of flexibility limits the flow rate of the
individual treatment trains, since the plant flow
rate must be 1 MGD to match
the filter to waste flow rate of 1 MGD; otherwise,
the water level in a filter changes.)
• No ability to feed filter aid polymer to the filters.
(NOTE: This flexibility can be used to enhance
filter performance, especially during times when
clarifier performance is less than optimum.)
• Inability to gradually increase and decrease
backwash flow rate. (NOTE: This flexibility
provides better cleaning of the filter media, less
opportunity for loss of media, and better re-
stratification of the media following backwash.)
Policies (Administration) A
• Lack of established performance goals for the
plant, such as 0.1 NTU filtered water turbidity,
that would provide maximum public health
protection and associated support to achieve
these performance goals.
Insufficient Time on the Job (Operation) A
• No sampling and evaluation of upflow clarifier
performance.
• Inadequate testing to optimize coagulant type and
dosages. (NOTE: Some jar testing was
completed by staff; however, standard testing
procedures were not followed to determine
optimum dosages.)
• No monitoring of individual filter turbidity.
• Excessive caution on use of the creek source to
achieve optimized performance.
• Starting "dirty" filters without backwashing or
using filter to waste.
• Non-optimized feed point for flocculant aid
addition. (NOTE: Flocculant aid products are
typically fed at a location with gentle mixing to
avoid breaking the long-chain organic molecules.)
Process Instrumentation/Automation (Design) B
• No turbidimeters are located on individual filters
and creek source (i.e., at turbine).
218
-------
• Plant is designed to automatically start and stop
operation based on storage tank level and upflow
clarifier backwash requirements. (NOTE:
Without initiating a filter backwash or the filter to
waste mode after each shutdown, the potential
exists to pass trapped particles (i.e., potential
pathogens) through the plant due to hydraulic
surging.)
• Location of influent turbidity sample line relative to
the monitor cell may cause inaccurate readings.
Presedimentation (Design) B
• Long detention time and subsequent low turnover
contributes to excessive algae growth and poor
water quality.
• Lack of flexibility to operate one, or portion of
one, presedimentation pond to reduce detention
time and increase turnover.
• Lack of flexibility to bypass ponds without
bypassing the turbine. (NOTE: A new bypass is
under construction which will provide this
flexibility.)
• Limited ability to maintain high turnover through
ponds when not in use because of restriction in
Parshall flume from pond 2 to creek.
Evaluation Follow-Up
The potential exists to achieve optimized perform-
ance goals and, therefore, enhance public health
protection with Water Treatment Plant No. 005.
Implementation of a Comprehensive Technical
Assistance (CTA) project by a qualified facilitator has
been demonstrated to be an effective approach to
achieve optimum performance goals (13). Through a
CTA project, the performance limiting factors
identified during the Comprehensive Performance
Evaluation would be addressed in a systematic
manner. A partial list of potential CTA activities that
could be implemented by a facilitator and plant staff is
presented below:
• Facilitate development of optimization per-
formance goals by the city administration to
provide adequate direction and support to
operation and maintenance staff.
• Establish a process control program based on
prioritized data collection, database development,
data and trend interpretation, and process
adjustments.
• Provide technical guidance on use of the creek
source versus the presedimentation ponds during
seasonal water quality changes.
• Facilitate special studies with plant staff to assist
them with optimizing plant performance and
establishing the need for minor plant modi-
fications.
• Provide training to assist operators with opti-
mizing coagulant type and dosages.
References
1. Renner, R.C., B.A. Hegg, J.H. Bender, and E.M.
Bissonette. February 1991. Handbook -
Optimizing Water Treatment Plant Performance
Using the Composite Correction Program. EPA
625/6-91/027. Cincinnati, OH: USEPA.
2. Renner, R.C., B.A. Hegg, and D.F. Fraser.
February 1989. "Demonstration of the Com-
prehensive Performance Evaluation Technique
to Assess Montana Surface Water Treatment
Plants." Association of State Drinking Water
Administrators Conference. Tucson, AZ.
3. AWWA Statement of Policy. 1968. "Quality
Goals for Potable Water." Jour.AWWA,
60(12):1317. Denver, CO.
4. AWWA White Paper. 1995. "What Water
Utilities Can Do to Minimize Public Exposure to
Cryptosporidium in Drinking Water." AWWA
Mainstream. Denver, CO.
5. Logsdon, G.S. and E.G. Lippy. December 1982.
"The Role of Filtration in Preventing Waterborne
Disease." Jour.AWWA:Q54. Denver, CO.
6. USEPA Water Engineering Research Labora-
tory. 1985. Project Summary - Filtration of
Giardia Cysts and Other Substances: Volume 3
- Rapid Rate Filtration. EPA/600/ S2-85/027.
Cincinnati, OH: USEPA.
219
-------
7. Logsdon, G.S., L. Mason, and J.B. Stanley, Jr.
1988. "Troubleshooting an Existing Treatment
Plant." In Proc. of AWWA Seminar- Filtration:
Meeting New Standards: 109-125. Denver, CO.
8. Consonery, P.J., et. al. November 1996.
"Evaluating and Optimizing Surface Water
Treatment Plants: How Good is Good Enough."
Paper presented at AWWA Water Quality
Technology Conference. Boston, MA.
9. Nieminski, E.G., et. al. 1995. "Removing Giardia
and Cryptosporidium by Conventional Treatment
and Direct Filtration." Journal AWWA, 87(9):96.
Denver, CO.
10. West, T., P. Daniel, P. Meyerhofer, A. DeGraca,
S. Leonard, and C. Gerba. 1994. "Evaluation of
Cryptosporidium Removal Through High Rate
Filtration." In Proceedings of 1994 AWWA
Annual Conference - New York, NY.
Denver, CO.
AWWA.
11. Patania, N.L., et. al. 1996. "Optimization of
Filtration for Cyst Removal." Denver, CO:
AWWARF.
12. Guidance Manual for Compliance With the
Filtration and Disinfection Requirements for
Public Water Systems Using Surface Water
Sources. 1989. USEPA Office of Drinking
Water. Washington, D.C.
13. Schwarz, C., J.H. Bender, and B.A. Hegg.
December 1997. "Final Report - Comprehensive
Technical Assistance Project - City of Greenville
Water Treatment Plant." Texas Natural
Resource Conservation Commission.
220
-------
Appendix H
Example CPE Scheduling Letter
221
-------
April 6, 1998
Chairman/Mayor/Public Works Director
Water Authority/City/Town
RE: Evaluation of the Water Authority/City/Town Water Treatment Plant
May 18-21, 1998
Dear Mr./Ms. :
You were recently contacted by of the (regulatory agency) regarding an evaluation of
your water treatment facility. This letter is intended to provide you with some information on the evaluation and
describe the activities in which the Water Authority/City/Town will be involved. The evaluation
procedure that will be used at your facility is part of an overall water treatment optimization approach called the
Composite Correction Program.
The Composite Correction Program (CCP) was developed by the U. S. Environmental Protection Agency and
Process Applications, Inc. to optimize surface water treatment plant performance for protection against microbial
contaminants such as Giardia and Cryptosporidium. The approach consists of two components, a
Comprehensive Performance Evaluation (CPE) and Comprehensive Technical Assistance (CTA). The first com-
ponent, the Comprehensive Performance Evaluation, will be conducted at your facility the week of
. During the CPE, all aspects of your water treatment administration, design, operation, and maintenance will be
reviewed and evaluated with respect to their impact on achieving optimized performance.
The evaluation will begin with a brief entrance meeting on Monday, May 18, 1998 at approximately 2:00 P.M.
The purpose of the entrance meeting is to discuss with the plant staff and administrators the purpose of the
evaluation and the types of activities occurring during the next three days. Any questions and concerns
regarding the evaluation can also be raised at this time. It is important that the plant administrators and those
persons responsible for plant budgeting and planning be present because this evaluation will include an
assessment of these aspects of the plant. Following the entrance meeting, which should last approximately 30
minutes, the plant staff will be requested to take the evaluation team on an extensive plant tour. After the plant
tour, the team will begin collecting performance and design data. Please make arrangements so that the
monitoring records for the previous 12 months, operating records, and any design information for the plant are
available for the team. Also, a continuous recording on-line turbidimeter will be installed on one or more of your
filters. Sample taps to accomodate this connection should be available.
On Tuesday, the evaluation team will be involved in several different activities. The major involvement of the
plant staff will be responding to the evaluation team's questions on plant performance and operation and
maintenance practices. Several special studies may also be completed by the team to investigate the
performance capabilities of the plant's different unit treatment processes. Requests to inspect filter media and
monitor filter backwashes will be coordinated with staff to minimize the impact on plant operation.
Also on Tuesday, a member of the evaluation team will meet with the administrators to review the administrative
policies and procedures and financial records associated with the plant. We would like to review your water
treatment budget for the previous and current fiscal years. We would expect that most of this information would
be available in your existing accounting system.
222
-------
April 6, 1998
Page 2
We request that the plant staff and administrators be available for interviews either Tuesday afternoon or
Wednesday morning. We will be flexible in scheduling these interviews around other required duties of you and
your staff. Each of the interviews will require about 30 to 45 minutes of time.
We are anticipating that an exit meeting will be held on Thursday morning at 8:30 A.M., and it will last about 1
hour. During the exit meeting, the results of the evaluation will be discussed with all of those who participated.
The performance capabilities of the treatment processes will be presented, and any factors found to limit the
performance of the plant will be discussed. The evaluation team will also answer any questions regarding the
results of the evaluation. The results presented in the exit meeting will form the basis of the final report, which
will be completed in about one month.
We look forward to conducting the CPE at your facility. If you have any questions prior to the evaluation, please
don't hesitate to contact us.
Very truly yours,
Evaluation Team Contact
223
-------
-------
Appendix I
Example Special Study
225
-------
Example Special Study
(as developed by CTA facilitator and plant staff prior to implementation)
I. Hypothesis
A. Increasing the ferric chloride dosage for low turbidity water (< 5.0 NTU) will improve the finished
water turbidity and increase plant stability.
B. Increasing the ferric dosage may decrease alkalinity below level to maintain finished water pH
target.
II. Approach
A. Conduct series of jar tests using established jar testing guidelines that vary ferric chloride
dosages (start with 0.5 mg/L increments and bracket down to 0.1 mg/L).
B. Add filter aid at the end of the flocculation time to simulate plant dosage (up to 0.1 mg/L).
C. Measure pH, alkalinity, temperature and turbidity of raw and finished water.
D. Document and interpret test results.
E. Test optimum dosage at full plant scale (pilot mode where filtered water is directed to waste).
F. Measure same parameters as above.
G. If results indicate alkalinity limitation is necessary (finished water alkalinity < 20 mg/L), conduct
jar tests with soda ash addition.
III. Duration of Study
A. Two weeks to complete jar and full-scale testing.
IV. Expected Results
A. Improved finished water turbidity and increased plant stability at higher ferric chloride dosages.
B. Deficiency in finished water alkalinity.
C. Loss of finished water pH.
D. Potential change in primary coagulant.
E. Potential need for alkalinity (soda ash) addition.
V. Conclusions
A. To be compiled in summary report after completion of study.
VI. Implementation
A. To be determined after completion of study.
226
-------
Appendix J
Example Operational Guideline
227
-------
Example Operational Guideline
Subject: Process Control Data Collection Number: 5
Objective: To establish a data collection method Date Adopted: 4/29/97
Date Revised:
Measure and record the following water quality, chemical usage, and flow data at the
frequency noted.
A. Raw water parameters (measure/record once per day):
1. Plant flow rate - MGD (8:00 a.m. to 8:00 a.m.)
2. Raw turbidity - 7 days per week
3. pH - units - 7 days per week
4. Alkalinity - mg/L - 5 days per week
5. Temperature - °C - 7 days per week
B. Chemical usage data (record once per day):
1. Coagulant use - gal/day
2. Coagulant batch density - Ib/gal
3. Filter aid use - gal/day
4. Filter aid batch density - Ib/gal
5. Chlorine use - Ib/day
6. Orthophosphate use - Ib/day
C. Finished water parameters (measure/record once per day, unless noted otherwise):
1. Alkalinity-mg/L-5 days per week
2. pH - 7 days per week
3. Free chlorine residual - mg/L - 7 days per week (minimum value for day from chart)
4. Turbidity - NTU - value at established 4-hour increments
Individual sedimentation basin turbidity.
A. Collect samples once each 4-hour period from the effluent of each basin and use lab
turbidimeterto measure turbidity.
Individual filter monitoring data collection methods.
A. Circular recording charts will be used for turbidity monitoring.
1. Individual turbidity charts are located on top of the individual turbidity monitors.
2. Twenty-four hour charts will be used.
3. When changing charts, record the "change chart time" for the 24-hour period.
B. Data to record from individual filter charts.
1. Start of all backwashes (note time and record on chart).
2. Return to service after all backwashes (note time and record on chart).
3. Backwash turbidity spike (highest turbidity value after filter is back on-line).
4. Recovery turbidity (turbidity 15 minutes after filter placed back in service).
5. Highest turbidity recorded every 4 hours for each individual filter, excluding backwash
spike and recovery turbidities.
228
-------
Process Control Data Collection (Continued)
IV. Utilize the process control data entry form below for data recording.
A. Complete the data entry form once per day, 7 days per week.
B. Enter daily data into computer database program and print out daily report.
C. At the end of each month, print monthly process control report from the database program and
distribute as follows:
1. Public Works Director
2. Monthly process control file in filing cabinet
3. Post copy on plant bulletin board
Water Treatment Plant Process Control Data Entry Form
Parameter
Date
Flow rate
Raw turbidity
Raw pH
Raw alkalinity
Raw temperature
Coagulant daily use
Coaq. batch density
Filter aid daily use
Turbidity Data
Max. Sedimentation 1
Max. Sedimentation 2
Max. filter 1 turbidity
Max. filter 2 turbidity
Max. filter 3 turbidity
Max. filter 4 turbidity
Finished turbidity
Post Backwash Data
BW turbidity spike
Turb. 15 min. on-line
Units
m/d/y
MGD
NTU
units
mq/L
C
q a I/day
Ib/qal
q a I/day
Time
NTU
NTU
NTU
NTU
NTU
NTU
NTU
Filter No.
NTU
NTU
Data
2400-0400
1
Parameter
Filter aid batch density
Other chemical use
Other chemical density
Finished alkalinity
Finished pH
Finished free chlorine
Giardia Inact. tarqet
Chlorine use
Orthophosphate use
0400-0800
2
0800-1200
3
Units
Ib/qal
q a I/day
Ib/day
mq/L
units
mq/L
loq
Ib/day
Ib/day
1200-1600
4
Data
1600-2000
2000-2400
229
-------
-------
Appendix K
Example Process Control Daily Report
231
-------
Water Treatment Plant Process Control Daily Report
28-Feb-98
Parameter
Date
Flow rate
Raw turbidity
Raw pH
Raw alkalinity
Raw temperature
Coagulant daily use
Coag. batch density
Filter aid daily use
Units
m/d/y
MGD
NTU
units
mg/L
gal/day
Ib/gal
gal/day
Data
2/28/98
1.00
5.00
7.5
34.0
5.0
13.0
3.36
2.00
Parameter
Filter aid batch density
Other chemical use
Other chemical density
Finished alkalinity
Finished pH
Finished free chlorine
Giardia Inact. target
Chlorine use
Orthophosphate use
Units
Ib/gal
gal/day
Ib/day
mg/L
units
mg/L
log
Ib/day
Ib/day
Data
0.3
0.000
0.0
30.0
7.2
1.0
1.0
12.0
16.0
Turbidity Data
Time
2400-0400
0400-0800
0800-1200
1200-1600
1600-2000
2000-2400
Max. Sedimentation 1
NTU
0.55
0.60
0.75
0.80
0.70
0.50
Max. Sedimentation 2
NTU
0.60
0.70
0.85
0.90
0.80
0.60
Max, filter 1 turbidity
NTU
0.05
0.04
0.04
0.06
0.06
0.05
Max, filter 2 turbidity
NTU
0.02
0.02
0.03
0.02
0.03
0.04
Max, filter 3 turbidity
NTU
0.08
0.07
0.09
0.10
0.11
0.07
Max, filter 4 turbidity
NTU
0.05
0.04
0.04
0.03
0.03
0.04
Finished turbidity
NTU
0.04
0.04
0.05
0.06
0.06
0.05
Post Backwash Data
Filter No.
BW turbidity spike
NTU
0.20
0.15
0.25
0.18
Turb. 15 min. on-line
NTU
0.07
0.06
0.11
0.07
Calculated Parameters
Coagulant dose
Filter aid dose
Other chemical dose
Chemical cost
mg/L
mg/L
mg/L
$/m gal
5.24
0.060
0.00
47.91
Required CT
Measured CT
CT ratio
mg/L-min
mg/L-min
57.2
103.7
1.8
3 0.06!
,2 0.04
0.02 (
O
O
CN
— •
1
8
o
—
— Filter 1
h
t
f
- -O -
1 —
=^«
- Filter 2
1 1
'
..
88 88 88
^-00 00 CN CN CO
o o o ^~ T- ^-
Time
. -C
l-==i
j j
§1
»S
O ^"
rCi - - .
-••.
^
MOO-
0400
i —
> —
ii==^
i
• •*
ii — —
"k
^\
_5
P 9"'
I
0400- 0800- 1200- 1600-
0800 1200 1600 2000
Time
-^r^
1
)
2000-
2400
0 90 i —
0 80
|0.60C
'o
"~ 0.20
0.10-
— • — Sed 1 - - O - -Sed 2
1— — -"
>•"" .
i^
.-' ji
^
— —
O-J,
,x
s
2400- 0400- 0800- 1 200- 1 600-
0400 0800 1200 1600 2000
)
2000-
2400
232
-------
Appendix L
Example Jar Test Guideline
233
-------
JAR TEST PROCEDURE (page 1)
TEST CONDITIONS
Facility
Date
Time
Turbidity
Temperature
PH
Alkalinity
Water Source
Coagulant
Coagulant Aid
PREPARING STOCK SOLUTIONS
Step 1
Select desired stock solution concentration (see Table 1).
Choose a stock solution concentration that will be practical for transferring chemicals to jars.
Table 1
Stock
Solution
(%)
0.01
0.05
0.1
0.2
0.5
1.0
1.5
2.0
Concentration
(mg/L)
100
500
1,000
2,000
5,000
10,000
15,000
20,000
Desired Stock Solution
(%)
mg/L dosage per ml
of stock solution
added to 2 liter jar
0.05
0.25
0.5
1.0
2.5
5.0
7.5
10.0
Coagulant Coag. Aid
Step 2
Determine chemical amount to add to 1 liter flask.
If using dry products, see Table 2. If using liquid products, go to step 3.
Table 2
Stock Solution
(%)
0.01
0.05
0.1
0.2
0.5
1.0
1.5
2.0
Cone.
(mg/L)
100
500
1,000
2,000
5,000
10,000
15,000
20,000
Desired Amount
in 1 liter flask (ml_)
mg of alum added
to 1 liter flask
100
500
1,000
2,000
5,000
10,000
15,000
20,000
Coagulant Coag. Aid
StepS
Determine liquid chemical amount to add to volumetric flask.
For liquid chemicals, use the equation below -
ml coagulant =
(stock solution %) x (flask volume, ml) x (8.34 Ib/gal)
100 x (chemical strength, Ib/gal)
Chemical Strength (Ib/gal)1
Stock Solution Volume (mL)
Desired Volume of Chemical
to add to Flask (mL)
Coagulant
Polymer
1 Note: Chemical Strength = chemical density x % strength
234
-------
JAR TEST
PROCEDURE (page 2)
JAR SETUP
Set up individual jar doses based on desired range of test.
Determine amount of stock solution by dividing dose by mg/L per ml (see Table 1).
Coagulant - Jar#
Dose (mg/L)
Stock Solution (ml)
Coagulant Aid - Jar#
Dose (mg/L)
Stock Solution (ml)
Dose (mg/L)
Stock Solution (mL)
1 2
1 2
1 2
TEST PROCEDURE
Step 1
3
3
3
456
456
456
Set rapid mix time equal to rapid mix detention time.
To determine rapid mix time, use the following equation -
Rapid mix time (min) = (rapid mix volume, gal) x
Step 2
(plant flow
Mix Volume (gal)
Plant Flow Rate (gal/day)
Mix Time (sec)
(1 ,440 min/day) x (60 sec/min)
rate, gal/d)
Set total flocculation time equal to total flocculation detention time in plant.
To determine total flocculation time, use the following equation -
Floe time (min) = (flocculator volume, gal) x (1 ,440 min/day)
(plant flow rate, gal/d)
StepS
Step 4
Floe Volume (gal)
Floe Time (min)
Use Figure 1 to determine the jar mixing energy values (rpm) that correspond to the approximate
flocculator mixing energy values (G). Flocculator mixing energy can be estimated from plant
design information (O&M manual) or can be calculated from the equation described in
Appendix F - B.1 . Flocculation.
Flocculator Stage
Flocculator Mixing (G)
Jar Mixing (rpm)
1st
2nd 3rd
Set sample time based on particle settling velocity. Use the equation below to determine
sample time when using 2 liter gator jars as described in Figure 1 .
Sample time (min) = (10 cm) x (surface area, ft2) x (1 ,440 min/day) x (7.48 gal/ft3)
(plant flow rate, gal/d) x (30.48 cm/ft)
Sedimentation Surface Area
(ft2)
Plant Flow Rate (gal/day)
Sample Time (min)
235
-------
JAR TEST PROCEDURE (page 3)
TEST RESULTS
Record test results in the table below.
Settled Turbidity (MTU)
Settled pH
Filtered Turbidity (NTU)
Comments:
aoa
600
you
a OQ
300
D - 7. Sen
z
5 G 7 6 9 to
Impeller Speed (rpm)
Figure 1. Laboratory G Curve for Flat Paddle in 2 Liter Gator Jar
236
-------
Appendix M
Chemical Feed Guidelines
237
-------
Chemical Feed Guidelines
The following guidelines provide information on the
use of water treatment chemicals for coagulation and
particle removal. Typical chemicals used for these
applications include coagulants, flocculants, and filter
aids. To use these chemicals properly, it is
necessary to understand how the specific chemicals
function and the type of calculations that are required
to assure accurate feeding. Although these
guidelines focus on coagulation and particle removal,
the discussion on determining feed rates and
preparing feed solutions applies to other water treat-
ment chemical applications such as corrosion and
taste and odor control.
Chemicals for Coagulation and Particle
Removal
Coagulation Chemicals
Alum
1.
2.
3.
Alum (aluminum sulfate) is one of the most widely
used coagulants in water treatment. When alum
is added to water, insoluble precipitates such as
aluminum hydroxide (AI(OH)3) are formed.
The optimum
about 5 to 8.
pH range for alum is generally
Alkalinity is required for the alum reaction to
proceed. If insufficient alkalinity is present in the
raw water, the pH will be lowered to the point
where soluble aluminum ion is formed instead of
aluminum hydroxide. Soluble aluminum can
cause post flocculation to occur in the plant
clean/veil and distribution system.
4. As a rule of thumb, about 1.0 mg/L of commercial
alum will consume about 0.5 mg/L of alkalinity.
At least 5 to 10 mg/L of alkalinity should remain
after the reaction to maintain optimum pH.
5. 1.0 mg/L of alkalinity expressed as CaCO3
equivalent to:
• 0.66 mg/L 85% quicklime (CaO)
is
• 0.78 mg/L 95% hydrated lime (Ca(OH)3)
• 0.80 mg/L caustic soda (NaOH)
1.08 mg/L soda ash (Na2CO3)
• 1.52 mg/L sodium bicarbonate (NaHCO3)
6. If supplemental alkalinity is used it should be
added before coagulant addition, and the
chemical should be completely dissolved by the
time the coagulant is added.
7. When mixing alum with water to make a feed
solution, maintain the pH below 3.5 to prevent
hydrolysis from occurring which will reduce the
effectiveness of the chemical. A 10 to 20 percent
alum solution by weight will maintain this pH
requirement in most applications.
8. Density and solution strength values for com-
mercial alum can be found in Table M-1. A solu-
tion strength of 5.4 Ib/gal can be used for
approximate chemical calculations.
Ferric Chloride
1. The optimum pH range for ferric chloride is 4 to
12.
2. When mixing ferric chloride with water to make a
feed solution, maintain the pH below 2.2.
3. Ferric chloride consumes alkalinity at a rate of
about 0.75 mg/L alkalinity for every 1 mg/L of
ferric chloride.
4. Ferric chloride dosage is typically about half of
the dosage required for alum.
5. Density and solution strength values for com-
mercial ferric chloride vary with the supplier. A
solution strength of 3.4 Ib FeCI3/gallon can be
used for approximate chemical calculations (i.e.,
product density of 11.3 Ib/gal and 30 percent
FeCI3 by weight).
238
-------
Table M-1. Densities and Weight Equivalents of Commercial Alum Solutions1
Specific
Gravity
1.0069
1.0140
1.0211
1.0284
1.0357
1.0432
1.0507
1.0584
1.0662
1.0741
1.0821
1.0902
1.0985
1.1069
1.1154
1.1240
1.1328
1.1417
1.1508
1.1600
1.1694
1.1789
1.1885
1.1983
1.2083
1.2185
1.2288
1.2393
1.2500
1.2609
1.2719
1.2832
1.2946
1.3063
1.3182
1.3303
1.3426
1.3551
1.3679
Density
Ib/gal
8.40
8.46
8.52
8.58
8.64
8.70
8.76
8.83
8.89
8.96
9.02
9.09
9.16
9.23
9.30
9.37
9.45
9.52
9.60
9.67
9.57
9.83
9.91
9.99
10.08
10.16
10.25
10.34
10.43
10.52
10.61
10.70
10.80
10.89
10.99
11.09
11.20
11.30
11.41
% AI203
0.19
0.39
0.59
0.80
1.01
1.22
1.43
1.64
1.85
2.07
2.28
2.50
2.72
2.93
3.15
3.38
3.60
3.82
4.04
4.27
4.50
4.73
4.96
5.19
5.43
5.67
5.91
6.16
6.42
6.67
6.91
7.16
7.40
7.66
7.92
8.19
8.46
8.74
9.01
Equivalent %
Dry Alum2
1.12
2.29
3.47
4.71
5.94
7.18
8.41
9.65
10.88
12.18
13.41
14.71
16.00
17.24
18.53
19.88
21.18
22.47
23.76
25.12
26.47
27.82
29.18
30.53
31.94
33.35
34.76
36.24
37.76
39.24
40.65
42.12
43.53
45.06
46.59
48.18
49.76
51.41
53.00
Strength
Ib alum/gallon
0.09
0.19
0.30
0.40
0.51
0.62
0.74
0.85
0.97
1.09
1.21
1.34
1.47
1.59
1.72
1.86
2.00
2.14
2.28
2.43
2.58
2.74
2.89
3.05
3.22
3.39
3.56
3.74
3.93
4.12
4.31
4.51
4.71
4.91
5.12
5.34
5.57
5.81
6.05
Strength
g alum/liter
1 1 .277
23.221
35.432
48.438
61.521
74.902
88.364
102.136
116.003
130.825
145.110
160.368
175.760
190.830
206.684
223.451
239.927
256.540
273.430
291.392
309.540
327.970
346.804
365.841
385.931
406.370
427.131
449.122
472.000
494.777
517.027
540.484
563.539
588.619
614.149
640.938
668.078
696.657
724.987
From Allied Chemical Company "Alum Handbook", modified by adding gm/L dry alum column.
217% Al2C>3 in Dry Alum + 0.03% Free
239
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Polyaluminum Chloride (1)
Flocculation Chemicals
1. Polyaluminum chloride (PACI) products are less
sensitive to pH and can generally be used over
the entire pH range generally found in drinking
water treatment (i.e., 4.5 to 9.5).
2. Alum and PACI products are not compatible; a
change from feeding alum to PACI requires a
complete cleaning of the chemical storage tanks
and feed equipment.
3. The basicity of the product determines its most
appropriate application:
• Low basicity PACIs (below 20 percent):
Applicable for waters high in color and total
organic carbon (TOC).
• Medium basicity PACIs (40 to 50 percent):
Applicable for cold water, low turbidity, and
slightly variable raw water quality.
• High basicity PACIs (above 70 percent):
Applicable for waters with highly variable
quality, as a water softening coagulant, for
direct filtration, and some waters with high
color and TOC.
4. Check specific manufacturer's product infor-
mation for density and strength values.
Polymers (Coagulation)
1. Polymer can be added as either the primary
coagulant or as a coagulant aid to partially
replace a primary coagulant (e.g., alum).
2. Polymers used for coagulation are typically low
molecular weight and positively charged (cati-
onic).
3. The dosage for polymers used for coagulation is
dependent on raw water quality.
4. Product density and solution strength information
can be obtained from the individual polymer
manufacturers.
1. Polymers used as flocculants generally have a
high molecular weight and have a charge that is
positive, negative (anionic), or neutral (nonionic).
2. The purpose of a flocculant is to bridge and
enmesh the neutralized particles into larger floe
particles, and they are generally fed at a dosage
of less than 1 mg/L.
3. Flocculants should be fed at a point of gentle
mixing (e.g., diffuser pipe across a flocculation
basin) to prevent breaking apart the long-chained
organic molecules.
4. Product density and solution strength information
can be obtained from the individual polymer
manufacturers.
Filter Aid Chemicals
1. Polymers used as filter aids are similar to floc-
culants in both structure and function.
2. Filter aid polymers are typically fed at dosages
less than 0.1 mg/L; otherwise, when fed in
excess concentrations they can contribute to filter
head loss and short filter run times.
3. Filter aid polymers are fed at a point of gentle
mixing (e.g., filter influent trough).
4. Product density and solution strength information
can be obtained from the individual polymer
manufacturers.
Feeding Chemicals in the Plant
Step 1. Determining the Required Chemical
Dosage
1. The appropriate chemical dosage for coagulants
is typically determined by lab or pilot scale testing
(e.g., jar testing, pilot plant), on-line monitoring
(e.g., streaming current meter, particle counter),
and historical experience. A guideline on
performing jar testing is include in Appendix L.
240
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2. Flocculants are typically fed at concentrations
less than 1 mg/L. Jar testing can be used to
estimate the optimum dosage.
3. The typical dosage for filter aid polymers is less
than 0.1 mg/L. Jar testing, including filtering the
samples, is typically not effective for determining
an optimum dose. The polymer manufacturers
can provide guidelines on use of their products as
filter aids.
Step 2. Determining the Chemical Feed Rate
1. Once the chemical dosage is determined, the
feed rate can be calculated by the equation
below:
4.
a plant. An approach similar to dry feeder
calibration is followed; however, a volumetric
cylinder is typically used to collect the sample.
For example, 50 ml of liquid chemical collected
over 2 minutes would equate to a feed rate of 25
mL/min. A graph similar to Figure M-1 can be
developed showing pump setting (e.g., % speed)
versus feed rate in mL/min.
For liquid chemicals, an additional step is nec-
essary to convert the required weight-based feed
rate to a volume-based pumping rate. The
following equation can be used to determined the
pumping rate:
Pump Rate (mL/min) =
(FR)lb gal
day 3,785 ml
day (Cs)lb 1,440min
gal
Feed Rate (Ib/day) = Flow Rate (MGD) x
Chemical Dose (mg/L) x 8.34 Ib/gal
Step 3. Determining the Chemical Feeder
Setting
1. Once the chemical feed rate is known, this value
must be translated into a chemical feeder setting.
The approach for determining the setting
depends on whether the chemical is in a dry or
liquid form.
2. For dry chemicals, a calibration curve should be
developed for all feeders that are used in the
plant. A typical calibration curve is shown in
Figure M-1. The points on the curve are
determined by operating the feeder at a full
operating range of settings and collecting a
sample of the chemical over a timed period for
each setting. Once the sample weight is
determined by a balance, the feed rate can be
determined for that set point. For example, the
feed rate for the 100 setting was determined by
collecting a feeder output sample over a 2-minute
period. The sample weight was 5.8 Ib. The
associated feed rate can then be converted into
an equivalent hourly feed rate as follows:
,_ . „ x 5.8lb 60min
Feed Rate = x-
2min
hr
174lb
hr
FR = Feed Rate (Ib/day)
Cs = Chemical Strength (Ib/gal)
Preparation of Feed Solutions
Liquid solutions of both dry and liquid chemicals are
frequently prepared in a plant to prepare the chemical
for feeding (e.g., activating polymer) and to allow the
feeding of the chemical in an efficient manner. Two
examples are presented below to describe
approaches for preparing chemical solutions from dry
and liquid chemicals.
Preparation of an Alum Feed Solution
1. Determine the desired percent solution for
feeding the alum. As described under the previ-
ous alum discussion, a percent solution of 10 to
20 percent is typically used. In this example,
assume a 15 percent solution.
2. Based on the volume of alum solution to be
prepared, determine the weight of alum to add to
the solution tank. For an alum solution volume of
500 gallons, determine the alum weight as
follows:
Alum Weight = 500 gal x8'34lbx 0.15 = 625 Ib
gal
3.
For liquid chemicals, a calibration curve should
also be developed for all liquid feeders used in
241
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Figure M-1. Example dry chemical feeder calibration chart.
Setting
0
100
200
300
400
500
Sample Wt.
(Ib)
0
5.8
5.1
7.3
4.8
5.7
Time
(minutes)
0
2.0
1.0
1.0
0.5
0.5
Feed Rate
(Ib/hr)
0
174
306
438
576
684
700
600
500
.c
§. 400
0)
cc
•$ 300
£
200
100
0 50 100 150 200 250 300 350 400 450 500
Feeder Setting
3. Determine the alum strength (As) for use in
calculating feed rates. The alum strength for the
example above is calculated as follows:
Alum Strength (As):
625 Ib 1.25lb
500 gal gal
2. Based on the volume of solution to be prepared,
determine the weight of polymer to add to the
solution tank. For a solution volume of 200
gallons, determine the polymer weight as follows:
Polymer Weight = 200 gal x 8'34lbx 0.01 = 16.7 Ib
gal
Preparation of a Polymer Feed Solution
1. Polymer manufacturers provide guidelines on
preparation of their products, including whether
the product is fed neat (i.e., undiluted) or in a
diluted form. Diluted polymers are typically mixed
at 2% by weight or less; otherwise, they become
difficult to mix effectively. For this example,
assume a 1% solution is to be prepared.
It is frequently easier to measure polymer
volumetrically rather than by weight, so the weight
of polymer can be converted to an equivalent
volume by obtaining the product density from the
manufacturer. For example, if the polymer
density is 9.5 Ib/gal, the volume is calculated as
follows:
Polymer Volume = 16.7 Ib x
gal
9.5 Ib
= 1.76 gal
242
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Determine the polymer strength (Ps) for use in
calculating feed rates. The polymer strength for
the example above is calculated as follows:
..._,. 16.7lb 0.0835 Ib
Polymer Strength (Pq) = =
s 200 gal gal
References
1. Lind, Chris. 1996. "Top 10 Questions about
Alum and PACI." Opflow, 22(8):7. AWWA,
Denver, CO.
243
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Appendix N
Conversion Chart
245
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Conversion Chart
English Unit
acre
acre-ft
cfs
cuft
cuft
°F
ft
ft/sec
gal
gpm
gpm
gpd/sq ft
gpm/sq ft
inch
Ib
Ib
MGD
psi
sqft
Multiplier
0.405
1,233.5
1.7
0.0283
28.32
5/9 x (°F-32)
0.3048
30.48
3.785
0.0631
8.021
0.0408
40.7
2.54
0.454
454
3,785
0.070
0.0929
SI Unit
ha
cu m
cu m/min
cu m
I
°C
m
cm/sec
I
liter/sec
cu ft/hr
cu m/day/sq m
l/min/sq m
cm
kg
g
cu m/day
kg/sq cm
sq m
246
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Handbook -1998 Edition
-------
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