EPA-R 2-73-176
FEBRUARY 1973
Environmental Protection Technology Series
Application of Selected Industrial
Engineering Techniques to
Wastewater Treatment Plants
I
55
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Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
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EPA-R2-73-176
February 1973
APPLICATION OF SELECTED INDUSTRIAL ENGINEERING
TECHNIQUES TO WASTEWATER TREATMENT PLANTS
By
Charles W. Mallory
Dr. Robert Waller
Contract .No. 14*12-946
Project 17090 FYZ
Project Officer
Walter F. McMichael
Environmental Protection Agency
National Environmental Research Center
Cincinnati, Ohio 45268
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For salo by tho Superintendent of Documents, U.S. Government Printing Office, Washington, D.O. 20402
Price $2.60 domestic postpaid or $2.25 QPO Bookstore
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EPA Review Notice
This report has been reviewed by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents necessarily
reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or
commercial products constitute endorsement or recom-
mendation for use.
11
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ABSTRACT
A study was performed to evaluate the applicability of
various industrial engineering techniques to operation and main-
tenance of secondary waste treatment plants. Numerous tech-
niques used in military and industrial projects were evaluated
and applied in a case study at the Flint, Michigan waste treat-
ment plant using actual plant data, practices, and procedures.
Emphasis was placed on Work Study and Reliability and Main-
tainability analysis.
The evaluations indicated that a variety of techniques
were directly and beneficially applicable to the development of
rational management programs for design, operation, mainte-
nance, staffing, and quality control. An overall approach to
develop complete management programs was developed whereby
designers or managers could start from effluent goals and ration-
ally develop designs, O & M procedures, and staffing levels as
well as increase plant reliability. Quality control programs are
hampered by: poor parameters for measuring effluent quality
and process control; lack of knowledge on causes of variability
of plant effluent quality as well as the nonsteady state effects of
equipment failures; the prevailing practices for setting
quality goals, collecting and evaluating performance data; and
current practices for enforcement of performance requirements
by regulatory agencies.
A number of recommendations were offered to develop
programs for upgrading wastewater plant management.
This work was performed by Hittman Associates, Inc.,
9190 Red Branch Road, Columbia, Maryland 21043.
ill
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CONTENTS
Section Page
I General Conclusions 1
II General Recommendations 7
III Introduction 9
IV Case Study of a Secondary Treatment Plant 21
V Evaluation of Work Study Techniques on 33
Operational Activities
VI Evaluation of Work Study Techniques on 53
Maintenance Activities
VII Application of Work Study Techniques to 65
Staffing of Wastewater Treatment Plants
VIII Quality Control in Wastewater Treatment Plants 77
IX Application of Reliability and Maintainability 83
Evaluation Techniques
X Applicability of Industrial Engineering Techniques 115
to Advanced Waste Treatment
XI Summary Discussion 123
XII Acknowledgements 129
XIII References 131
XIV Appendices 133
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age
FIGURES
1 Interrelationships Between Industrial Engineering 3
Techniques
2 Example of Functional Staging Diagram 13
3 Program Flowsheet 19
4 Correlation Matrix 38
5 Adjacency Chart 39
6 Function-Capability-Equipment Matrix 40
7 Sample Standard Operating Procedure 45
8 Sample Maintenance Procedure Evaluation 57
Worksheet
9 Example of Preventive Maintenance Card 60
10 Multiple Activity Chart for Typical Eight-Hour 69
Shift
11 Example of Time for Electrical Maintenance 75
12 Reliability and Maintainability Evaluation Flow 85
Process Elements
-rv;-
13 Elements of the Reliability and Maintainability 86
Evaluation Techniques
14 Failures vs. Operating Hours 94
15 System Level Reliability Model Block Diagram 97
16 Reliability Model Subsystem Level Block Diagram 98
17 Recommended Reliability and Maintainability 105
Analysis Method
18 Identification of Low Reliability Items 108
19 Failure Modes and Effects Analysis 109
VI
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SECTION I
CONCLUSIONS
As a result of this study, it was concluded that industrial engineering
techniques should be more universally applied in the planning, design,
maintenance, operation, and management of wastewater treatment plants.
The management programs for wastewater treatment plants are generally
deficient in comparison to accepted practices in industry. Although the
"Federal Guidelines for Design, Operation, and Maintenance" (Ref. 8)
require that facilities have maximum reliability, be capable of operating
during certain failure modes, be designed for ease of routine maintenance
have defined operation, maintenance,and staffing requirements, have
operation and maintenance manuals, etc., little has been done to guide
designers in meeting these requirements.
The industrial engineering techniques used in industry and on military
systems are generally applicable to wastewater treatment plants and will
provide a rational basis for the planning, design, operation, maintenance,
and management of wastewater treatment plants. The objective of this
study was to determine the techniques that would be applicable to waste-
water treatment plants and to define by illustration how these techniques
could be applied. The techniques found to be applicable are summarized
in Table 1. The interrelationship of these techniques is graphically
illustrated on Figure 1. The principal conclusions from this study are
as follows:
Functional Staging Diagrams, System/Equipment Staging
Diagrams, Process Flow Schematics, and Function-Capability-
Equipment Matrices should be used in the initial planning and
design of wastewater treatment facilities to assure that all of
the required functions are provided without unnecessary redun-
dancy and to provide a basis for the selection of equipment
(Section V and Appendices A, B, and D).
The use of Correlation Matrices and Adjacency Charts will
provide a basis for the development of a plant layout with
proper consideration' of process flow, minimum pumping
and piping, and future operation and maintenance (Section V
and Figures 4 and 5).
Operational Sequence Diagrams define man-machine interfaces
and provide a basis for the development of operating procedures,
operational manuals, training aids, and engineered time stan-
dards (Section V and Appendix E).
The System/Equipment Staging Diagrams provide the basis
for the development of a Preventive Maintenance System,
a Work Order System, Maintenance Work Schedules, and a
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TABLE 1. SUMMARY OF INDUSTRIAL ENGINEERING
TECHNIQUES APPLICABLE TO WASTE TREATMENT ACTIVITIES
Activity
Design
Operation
Maintenance
Staffing
Quality Control
Applicable Techniques
Functional Staging Diagrams
System Equipment Staging Diagrams
Function-Capability-Equipment Matrices
Indexed Equipment List
Process Flow Sheet
Plant Layout
Correlation Matrix
Adjacency Chart
R&M Analysis
Functional Staging Diagrams
System Equipment Staging Diagrams
Operational/Maintenance Task Matrices
Operation Sequence Diagram
Plant Layout
System/Equipment Staging Diagram
Function-Capability-Equipment Matrices
Indexed Equipment List
Operational/Maintenance Task Matrices
Maintenance Procedure Cards
R&M Analysis
Operational/Maintenance Task Matrices
Operation Sequence Diagrams
Multiple Activity Chart
Maintenance- oriented Techniques
(see above)
Operations-oriented Techniques
(see above)
R&M Analysis
Application of Effective Management
Principles
Process Flow Sheet
Reliability and Maintainability Calculations
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uality
Control
Management
Criteria
Functional
Staging
Diagram
Equipment
Staging
Diagram
To
O&M
Task
Matrix
unction/Capability
Equipment
Matrix
Process
Flow
Chart
Correlation
Matrix
Adjacency
Chart
Operation/
Maintenance
Task
Matrix
Manufacturers
.". Data
Reliability
Block
Diagram
To
Operation
Sequence
Diagram
Maintenance
Procedure
Evaluation
Operational
Staging
Diagram
Reliability &
Maintainability
Calculations
Operating
Manual
Multiple
Activity
Chart
Reliability
Model
Failure Mode
& Effects
Correlation Matrix
Figure 1
Interrelationships Between Industrial Engineering Techniques
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Maintenance Reporting System.. The Maintenance Procedure
Evaluation Sheets, Standard-Time Tables, and Preventive
Maintenance Ratio can be used in the planning and evaluation
of maintenance functions (Section VI).
Operational/Maintenance Task Matrices and Multiple Activity
Charts can be developed from the Operational Sequence Dia-
grams to provide a basis for determing and defining optimal
staffing and skill levels for wastewater treatment plants
(Section VII).
The application of Process Control to wastewater treatment
plants is limited due to the lack of on-line instrumentation
to determine the character of the incoming wastes, the
limited technology on the factors that cause the variability
of wastewater treatment processes, and the time required
for the analysis of the quality of effluent samples (Section VIII).
Based on present technology and analytical equipment, process
control of the biological treatment process is generally limited
to the control of the food (BOD) to microorganisms ratio (re-
cycle sludge) based on flow measurements (Section VIII).
Reliability and Maintainability Evaluation Techniques provide
a quantitative basis for designing wastewater treatment sys-
tems, sizing and selecting equipment, and defining the require-
ments for redundant subsystems and components to assure
maximum on-line availability (Section IX).
Because of the limited knowledge of the biological treatment
process with respect to the effect of various failure modes, it
is not possible to quantitively define the relationship between
effluent quality and equipment reliability; however, Failure
Mode-Effects Analysis Techniques can be applied to define
qualitative relationships (Section IX).
Industrial engineering techniques should be particularly valuable
in the planning, design, operation, and maintenance of advanced
wastewater treatment process since no precedent exists for the
operation and staffing of these systems. Process Control and
Reliability and Maintainability Evaluation Techniques can be
applied to these systems better than biological treatment sys-
tems because the process parameters are more predictable
(Section X).
This study was based on the Sewage Treatment Plant located at the City
of Flint, Michigan. A summary of the typical specific benefits that
might be derived through the use of industrial engineering techniques
at this plant and other wastewater treatment plants are as follows:
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If Functional Staging had been applied in the design of the
original plant, certain of the equipment provided to permit
alternative operating modes could have been eliminated.
The use of a Correlation Matrix and Adjacency Chart
could have changed the plant layout to more effectively
group operating functions.
The System/Equipment Staging Diagrams prepared for
this study can now be used to develop a Preventive Main-
tenance System and cost accounting and maintenance con-
trol systems.
The Operational Sequencing Diagram prepared for this study
will provide a basis for the preparation of standard operating
procedures and for training new personnel.
The Preventive Maintenance Ratio for the Flint Plant indicates
that additional personnel on preventive maintenance., particularly
in the electrical equipment area, would reduce the need for
corrective maintenance and repair.
The Multiple Activity Charts for the Flint Plant indicate that
the operating personnel will be able to handle more preventive
maintenance tasks during their shifts.
The Operational/Maintenance Task Matrices prepared for the
Flint Plant will provide a basis for assigning lower level skill
jobs to personnel during in-service training.
The Flint Plant controls the recycle sludge based on incoming
flow to control the food-to-microorganism ratio and the process
control is undoubtedly a major f actor-ffi the high removal effi-
ciencies attained by this plant.
The reliability and maintainability analysis of the Flint plant
has indicated a number of areas where equipment reliability
can be improved.
The results of the reliability and maintainability analysis can
also be used to establish stock levels for repair parts and
frequency of preventive maintenance for the various equipment.
The greatest overall benefits that will be attained through the use of
industrial engineering techniques will be assurance of a higher proba-
bility of successful operation and more effective removal of pollutants.
In many cases, the application of these techniques may cost more in
terms of personnel, spare parts, and redundant systems. By the use
of industrial engineering techniques, it will be possible to assure maxi-
mum return on investment in terms of performance.
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SECTION II
RECOMMENDATIONS
This report covers a survey of industrial engineering techniques and
illustrates how certain techniques can be applied to wastewater treat-
ment plants. This report is not intended to be a standard to be explicitly
followed in the planning, design, and operation of wastewater treatment
plants. The purpose of this report is to introduce wastewater treatment
managers and designers to the industrial engineering techniques and to
provide guidance to industrial engineers on how selected techniques
might be applied to wastewater treatment plants. From this initial
effort, it is hoped that a closer interdisciplinary relationship can be
developed among sanitary, environmental, civil, and mechanical engi-
neers; wastewater treatment plant planners, managers, and operators;
and industrial engineers. A number of projects should be undertaken
by the Environmental Protection Agency to facilitate the application of
industrial engineering techniques into the planning, design, operation,
and maintenance of wastewater treatment plants. The recommended
projects are as follows:
A manual on the "Operational and Maintenance Aspects of Waste-
water Treatment Plant Planning and Design" should be prepared.
This would provide standard guidelines to be used to factor indus-
trial engineering techniques into wastewater treatment plants.
This would include procedures for developing and applying each
of the techniques previously listed in Table 1.
Either as a part of the manual or as a separate project, standard-
ized Functional Staging Diagrams, Equipment Staging Diagrams,
and Function-Capability-Equipment Matrices should be developed
for a variety of secondary wastewater treatment processes. These
could be made part of the construction grant application and would
serve as a checklist to assure completeness and as an index for
the later development of operation and maintenance packages.
As a part of the construction of a new wastewater treatment plant,
a special grant could be made to have industrial engineering tech-
niques applied starting in the planning stage and continued through
construction and operation. Special reports covering this aspect
would provide valuable guidance to others and would foster the
further application of these techniques in the wastewater treat-
ment field.
A program should be initiated as soon as possible for the system-
atic collection of failure, reliability, and maintenance data on
wastewater treatment plant components. These data will provide
a basis for implementing reliability and maintainability evaluations
as part of wastewater treatment plant design and will provide cri-
teria for better specifying components.
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An experimental program should be undertaken to develop a
better understanding of the effects of various types of failures
on biological treatment processes. This technology will be
needed to relate equipment reliability to effluent quality and
to set standards for more effective treatment processes.
An experimental program should be initiated to investigate
the causes of variability in effluent quality with biological
wastewater treatment processes and to define quantitative
relationships which describe nonsteady-state conditions and
effects. This technology is a prerequisite to further develop-
ment of process controls, automated control, and quality con-
trol of biological wastewater treatment processes.
A state-of-the-art study of on-line process control techniques
should be undertaken to define the requirements for control
and analytical equipment and the characteristics of presently
available equipment. Deficiencies will be identified which
would be the subject of development programs.
A review should be made of the requirements of various states
on the reporting of effluent water quality data and wastewater
treatment plant performance data. The objective of this project is
to determine the practicality and advisability of having uniform
reporting requirements by regulatory agencies and better
standards for quality control.
Specific recommendations for the Flint Plant and a further discussion of
some of the overall recommendations are contained in Section XI.
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SECTION III
INTRODUCTION
BACKGROUND
Over the past decade, several billion dollars have been spent at the local,
state, and federal levels on wastewater collection and treatment systems.
Indications are that additional expenditures over the next few decades will
be perhaps an order of magnitude greater. These massive expenditures
are being made for the avowed purpose of upgrading and protecting the
quality of the nation's waterways; however, the emphasis on funding
has been almost exclusively aimed at the construction of facilities. The
effectiveness of any facility, conventional or advanced, is largely deter-
mined by the operation and maintenance policies employed. Unfortunately,
wastewater treatment operating policies have largely evolved through
trial and error and are often unrelated to actual system capabilities and
independent of process selection.
Recent actions by EPA and its predecessor agencies have attempted to
establish a stronger link between plant design, equipment specifications,
and operating considerations by including specific requirements in the
"Federal Guidelines for the Design, Operation, and Maintenance of
Wastewater Treatment Facilities ' issued September 1970. The "Guide-
lines" call for an analysis of operational requirements, staffing require-
ments, consideration of reliability, ease of maintenance, adequate
operating records, an effective maintenance program, and an operation
and maintenance manual. However, little or no information exists in
the literature to guide a designer or manager in the satisfaction of these
requirements.
Considerable advancement has been made in the application of industrial
engineering techniques to integrate the technical, operational, and human
factors involved in the operation of complex systems. These techniques
have been refined and improved through long use in industrial, military,
and aerospace systems. The systematic application of industrial engi-
neering analysis can result in the development of more effective and
efficient operating policies, improved maintenance procedures, measure-
ment of and improvement in plant reliability, maintenance criteria for
the design and specification of process equipment, and staffing require-
ments by skill level for each unit process.
This project was concerned with the application of selected industrial
engineering techniques to the operation and maintenance of wastewater
treatment plants. Its aim was to evaluate and identify those techniques
which could be applied, either immediately or after further work, to
the development of sound operation and maintenance practices. To this
end, wastewater treatment plants have been considered as manufacturing
facilities with sewage as the basic raw material and treated effluent as
the finished product.
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The following subsections define and describe the industrial engineering
techniques considered in this program as well as present the general
procedures employed during the course of the study.
INDUSTRIAL ENGINEERING TECHNIQUES
Methods Engineering or Work Study
The terms "Methods Engineering" or "Work Study" are used to describe
a collection of analysis techniques used to improve the effectiveness of
men and machines. It enables the industrial engineer or manager to
subject each phase of an operation to systematic analysis. Methods
Engineering or Work Study engineering is a combination of industrial
engineering work measurement, method study, human factor, and
management techniques combined with system engineering function anal-
ysis, synthesis, evaluation, decision-making, and design techniques.
It was developed to simultaneously apply the advantages of industrial and
system engineering techniques to the efficient and effective design and
improvement of systems in which functions are performed by men and
equipment. Its basic approach is to collect meaningful data on complex
systems and to arrange the data in a form whereby evaluation, innovation,
and implementation are more easily performed.
Many of the techniques were first developed by Frederick W. Taylor at
the end of the 19th century. Frank and Lillian Gilbreth pioneered motion
study and applied the techniques, to the design of efficient work areas and
factory layouts. At the same'time, Charles E. Bedaux improved the
methods of measuring work elements, and in the 1930's the concept of
Work Study was set forth by Russell Currie of England; World War II
provided the necessary opportunities to perfect the industrial engineering
techniques of modern Work Study. In applying Work Study techniques, a
"problem" is a man-machine design which must be defined, an operation
and maintenance system which must be developed, an estimate of personnel
staffing reqiiired, etc.; it is a, situation requiring logical and systematic
analysis to determine specific resources necessary to accomplish the
required functions of a system. The eight steps of Work Study are:
Problem Definition (1) Select: Clearly define the objec-
tives, the scope, and the
depth of the study,
(2) Record: Gather and record accu-
rate and complete facts
(data) required.
(3) Examine: Carefully and critically
analyze the facts..
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Problem Solution (4) Innovate: Generate a variety of
alternatives which might
provide the best solution
to the problem.
(5) Evaluate: Analyze the alternatives
using pertinent criteria
and determine the best
alternative(s).
(6) Develop: Determine and describe
procedural steps neces-
sary to place the best
alternative(s) in operation.
Execute as Approved (7) Install: Provide assistance re-
by Management quired to initiate proce-
dural operations.
Feedback from System (8) Maintain: Monitor operations and
make appropriate adjust-
ments which may be
required.
The engineer, in conducting Work Study, should be objective and investi-
gate all alternatives in order to arrive at the most acceptable problem
solution. Critical examination requires answers to the questions: WHAT?,
WHEN?, WHO?, WHY?, and HOW?, and is essential to eliminating the
unnecessary. The final result is a logical, practical, well-documented
solution to the problem studied.
For an existing plant, on-site recording by the engineer is essential to
insure a factual basis for his subsequent analysis. Photographs are
taken of facilities and equipment pertinent to the study, and other infor-
mation and data are collected. Operational procedures are documented,
as required, so that the engineer will have a complete description and
understanding of how the system under study is operating and is supposed
to operate. Basic analytical descriptions, such as operational sequence
and flow diagrams and flow process and multiple activity charts, are
initiated during the recording phase to insure that all pertinent informa-
tion is obtained and to facilitate subsequent analysis. Quite often, such
description and analysis techniques must be specially adapted for the
system studied to pinpoint the unique features of its dynamic operations.
Examples and actual applications of these techniques are given in later
sections.
Functional Staging Diagram (FSD)
The Functional Staging Diagram is the backbone of the Work Study tech-
niques applied in this program. It is a block diagram structure which
is used to determine and display the interdependency of functions neces-
sary for a system ;to operate. It is developed vertically from its top
block, which identifies the goal function downward through lower hori-
zontal levels of blocks. Each array of blocks at a lower level contains
11
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descriptions of "how" the functions to which they are connected by lines
at the next higher level are accomplished. That is, the lower staged
functions are required to be performed in order that the related function
at the next higher stage may be satisfied. This approach breaks down
and organizes complex functions into smaller, more manageable ele-
ments. A simple example of an FSD is given in Figure 2.
Functional Staging Diagrams can be used to organize both operational
and maintenance functions into a suitable display for functional analysis.
The diagram starts in the top block with a description of the objective
to be attained by system operation and extends downward to lower levels.
Two-part phrases, a demonstrable verb and a measurable direct object,
are used to precisely describe each function to be satisfied including
those to be accomplished by equipment and personnel. Functions are
numerically coded so that associated data, information, and equipment
can be cross-referenced to them during the course of the study. This
numerical index is used in many of the succeeding techniques.
Function- Capability- Equipment Matrix
The Function-Capability-Equipment Matrix is used to establish prelimi-
nary design characteristics of a complex system. The matrix permits
the design engineer to methodically set forth the required or desired
capability for each function and subfunction that must be performed to
accomplish the system objectives. These functions can be derived from
the FSD described above; the use of the same numerical index system
aids in cross-referencing and information retrieval. Capabilities are
stated in quantitative or definitive terms. Once the capabilities for a
specific function have been defined, then the selection of the subsystem
or equipment is facilitated. That is, specific equipment is selected to
perform the function with the stated (required) capability. The. defining
of capabilities for a specific function logically leads to the establishment
of capabilities for the subfunctions at the lower levels. Function-Capa-
bility-Equipment Matrices, when fully developed, establish a basic
structure upon which the system designer can visually display total sys-
tem design capabilities and upon which he can develop an equipment list.
In addition, the matrices serve as design checklists to insure that all
required functions are met.
System/Equipment Staging Diagram (ESP)
The major purpose of this technique is to provide a visual display and
organization around which a system, such as a wastewater treatment
plant, can be structured. System configuration, that is, the cataloging
of equipment within a system or subsystem, is facilitated by the use of
the previously discussed Functional Staging Diagrams, but for this use,
the staging diagrams are system/equipment oriented rather than func-
tionally oriented. The system staging diagrams provide the framework
to which all the subsystems and equipment can be cataloged. An index
number, if possible the same numeric designation as used for indexing
the related functional staging element, is assigned to each equipment,
subsystem, and system to provide for identification, inventory, sort,
audit, and sequencing, either by manual or computer process.
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CO
Wet Face
110
Obtain Water
at Proper
Temperature. , ,
Apply Water to
Hands or Wash
Cloth
112
Contact Face
113
Shave Beard
100
Apply Lather
120
Obtain Lather
121
Apply Lather
to Hand
122
Contact Face
123
Apply Razor
130
Rinse Blade
131
Contact Face
with Razor
132
Rinse Blade
133
Clean Face
140
Apply Water to
Hands or Wash
Cloth
Contact Face
142
Dry Face
143
Figure 2
Example of Functional Staging Diagram
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Operational Sequence Diagram (OSD)
The operational sequence diagram displays the information-decision-action
relationships within a highly complex system. It is a technique of plotting,
relative to time (actual or sequential), the flow of information, data, or en-
ergy through an operationally defined system using standard symbols to re-
late to actions taken (inspections, data transmittal, data receipt, data
storage, or decisions) as that data, information,or energy is manipulated
internally in the system. A standard set of symbols, established in 1947
by the American Society of Mechanical Engineers (ASME), is used for dis-
playing how functions are performed and for determining:
Man-machine relationships
Equipment requirements
Personnel requirements
Communication requirements
Space-adjacency requirements
Most effective arrangements
Skill levels
Performance times
By plotting the sequence of various operations, the analyst can more read-
ily comprehend and evaluate the mechanics of the various activities.
Multiple Activity Chart (MAC)
A Multiple Activity Chart (MAC) visually displays a time comparison of
the activities of two or more men (with or without equipment). Activity
descriptions are recorded in a columnar format on a time scale. The
MAC is useful in analyzing scheduling problems, work load balance, and
manpower utilization. (Figure 10, Section VII, is an example of an MAC.)
Correlation Chart
This technique relates functions of men and equipment in a system by
plotting identical functions of men and equipment on both the abscissa
and ordinate of a matrix forming a square array. Since the array forms
two mirror-like triangles, the common practice is to list only the elements
on the ordinate. Relationships and dependencies are coded and recorded
within the array based on information, data, or energy flow, or other
related factors. This array allows for the grouping and arranging of re-
lated factors to facilitate the process flow within the system. Correlation
Charts are best used to summarize and display the flow relationships
shown in either functional or operational sequence diagrams from which
14
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the transition to functional groupings or equipment arrangements can
easily be made. (A Correlation Chart is shown as Figure 4, Section V.)
Adjacency Chart
With interrelationships summarized by the Correlation Chart, the next
step is the design layout of the system complex or the work space. The
Adjacency Chart is a technique to initially develop the design layout.
The man or the functional unit with the greatest number of relationships
is placed in a central location on the layout sheet. Working from this
man, function, or equipment, a relative layout plan can be systematically
developed by adding each element related to that man, function, or equip-
ment and to each other. In establishing the placement of the elements,
the degree of relationship or adjacency requirements between elements
is considered and the elements placed accordingly. (An Adjacency Chart
is shown as Figure 5, Section V.)
Critical Examination (CE) Analysis
A time-proven Work Study tool for resolving specific problem areas is
the Critical Examination Analysis Sheet. Critical Examination is used
to examine recorded data. Recording of the WHAT, WHEN, WHO, and
HOW of a work system without further inquiry presupposes that work
must be done: WHAT is" done; WHEN it is done; WHERE it is done;
WHO or WHAT does it; and HOW it is done. When the analyst has
answered these questions, he reorients his thinking toward a conceptual
line of inquiry that begins with the question, Why? The Critical Examina-
tion Analysis Sheet permits the analyst to systematically dissect a specific
problem to answer this question of WHY by determining the CAUSE and
NEED. Once the CAUSE and NEED are determined, the analyst can then
methodically investigate whether the element can be eliminated, modified,
or accomplished by other means or methods.
Reliability Techniques
Reliability evaluation is a technology for the analysis, prediction, and
counteraction of system failures and their frequency of occurrence.
It involves system analysis, function synthesis, equipment design, time
degradation of equipment, and system performance. Its primary objec-
tives are attainment of acceptable system performance for needed periods
of time and minimum costs for operation and maintenance.
Knowing the types of failures to which a system is prone and the intervals
at which they can be expected is invaluable in taking action to prevent
failures and thereby avoid an interruption in system operation. Further,
this information can provide a sound basis for determining material and
personnel resources necessary to support sustained, successful system
service.
The following basic definitions or descriptions are pertinent to the evalu-
ation techniques. (The first three are adaptations of those in Military
Standard MIL-STD-721, Ref. 1.)
15
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Reliability. Reliability is the probability that a unit (i. e., equip-
ment, subsystem,t plant, etc.) will perform its intended function
for a specified length of time under stated conditions. The value
frequently used to indicate unit reliability is MTBF (mean time
between failures).
Maintainability. Maintainability is the characteristic of the design
and installation of a system which is a measure of the ease and
rapidity with which a plant unit can be restored to an operational
condition following a failure. The characteristic MTTR (mean
time to repair) is frequently used to indicate unit maintainability.
Availability. Availability is the fraction of operating time a unit
is capable of operation. The expression of availability, A, is the
interrelationship of reliability and maintainability:
MTBF
MTBF + MTTR
Reliability Model. The initial technique normally used in reliability
evaluations is preparation of a model. A model includes a block
diagram displaying the dependency of system components whose
operations are necessary for minimum acceptable system perfor-
mance. The diagram also displays additional components which
are available or are needed to replace other components which
fail. A model includes numerical values which are calculated to
indicate the reliability of each component and the system. A
reliability model provides the basis for analyzing the reliability
of a system and its components during typical system operations.
The analysis may also include interrelationship of reliability,
maintainability, and availability.
Data Collection and Analysis. To provide numerical information
for reliability modelling, "cTaTa on component operational or test
performance must be collected and analyzed; typically, these
data are not readily available. Two types of data are required:
the number of equipment failures which have occurred during a
particular time period, and the amount of time the .equipment has
been operated during the same time period. Sources of these data
vary, but are usually found in maintenance records, equipment
operating logs, and manufacturers' customer service files. Data
must be carefully reviewed to assure applicability to the equip-
ment being analyzed.
Failure Modes and Effects Analysis. To determine action which
must be taken to correct a system reliability problem the potential
modes of a failure and their effect on system operation are care-
fully examined. The results of this examination are used to develop
and evaluate various alternatives for improving system reliability
by selecting more reliable equipment, providing a duplicate or
"standby" unit, modifying the equipment to improve its reliability,
16
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or compensating for its failure characteristics through maintenance.
The results of this analysis provide a rationale for modifications to
system design or an investment in material and personnel resources
to reduce failures and preserve the system process.
Maintainability Evaluation Techniques
Maintainability evaluation concerns the analysis of maintenance activity
and resources required to return an inoperative system component to
its specified operating capability. Its primary objectives are to reduce
repair time, facilitate maintenance work, insure conditions of safety
for maintenance personnel, and minimize maintenance costs. Although
many calculation procedures used in maintainability engineering are
directed toward reducing the time required for corrective maintenance.,
the technology can also be applied to preventive maintenance requirements.
Maintainability Assessment. A Maintainability Assessment is
normally performed using information from the reliability model
and averages of time typically required to return equipment to an
operable condition. Model information is used to determine how
often maintenance is required on equipment and the repair times
determine how long the equipment will be out of operation. The
objective of the assessment is to identify maintenance conditions
which are unacceptable in supporting the overall performance of
a system.
Data elements used for maintainability assessments are normally
in the form of equipment failure rates and mean times to repair
(MTTR). Repair times are usually derived from maintenance
records and estimates or measurement of times required to per-
form maintenance task increments.
Maintenance Engineering Analysis
The results from maintainability assessments are used to analyze
in detail the resources needed for properly supporting a system
when it is in operation. The following are the types of considera-
tions made during this analysis: the frequency and scope of pre-
ventive and corrective maintenance required; accessibility to
parts which typically require replacement; work space necessary
for maintenance actiyities; methods for reducing the time needed
to diagnose and repair failures; and required maintenance resources
such as replacement parts and facilities. Results of this analysis
are used in formulating a realistic plan for maintaining a system.
Other Techniques
In addition to techniques described above, a number of,other industrial
engineering techniques can also be applied to wastewater treatment
plants. These would include operational analysis, work sampling, time
standards, methods time measurement, maintenance standards, work
17
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simplification, statistical and regression analysis, incentives, plus cost
controls. Within the scope of this project, it was not possible to show
how every industrial engineering technique might be applied in the waste-
water treatment field. Accordingly, the majority of the effort was con-
centrated on those techniques which have been successfully used to directly
relate operational, maintenance, and management considerations to the
physical plant of relatively complex process systems. By using this
approach, it was hoped to develop a foundation to which more refined
techniques could be added later.
PROJECT APPROACH
As mentioned previously, the basic premise employed in the project
was the analogy between wastewater treatment and a "typical manufac-
turing facility. Obviously, certain aspects of the analogy are weak,
such as market considerations and profitability. However, wastewater
treatment plants apply men and machines to raw materials (sewage, air)
to produce a product (treated effluent) and a by-product (sludge). On
that basis, one can examine design, application, maintenance, and
quality control from an industrial engineering point of view.
The initial phase of the project involved the consideration of wastewater
treatment plants in terms of systems, subsystems, etc., /and the identi-
fication of the current approaches to the various functions which lead to
design construction and operation. At the same time, a wide variety of
Work Study and reliability and maintainability (R&M) techniques, as well
as other industrial engineering techniques, were evaluated as to basic
applicability to wastewater treatment plants. From this effort, suitable
techniques were selected for study. These techniques were applied to
an existing plant at Flint, Michigan, to evaluate their applicability in
depth and to determine in qualitative terms the degree of difficulty in
their application.
It could be agreed that the utility of the techniques could be better demon-
strated for a plant under design since the Flint plant had, through trial
and error, developed a comparatively good operation and maintenance
program. However, the time span between the commencement of design
and the starting of a new plant was judged excessive in relation to the
desired length of the study program.
Several man-weeks were spent at the Flint plant collecting data from
plans, specifications, and personnel. Selected Work Study and R&M
techniques were used to organize, synthesize, interrelate, and display
the data as well as to evaluate procedures and innovate and develop new
approaches. Most of this latter work was performed in the post-data-
collection phase. Figure 3 shows the general program flow sheet.
Section IV describes the approach in more detail as well as presents
data on the Flint plant. Sections V, VI, VII, and VIII present the results
of studies on the application of Work Study techniques on design, operations,
18
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RAW DATA
Plant plans,
Specifications,
Manuals, and
INDUSTRIAL
ENGINEERING
TECHNIQUES
Critical
Evaluation and
Examination
Techniques .
RESULTS
Operator/Maintainer ^x.
Experience and T\
Selected
Equipment ./^
Maintenance s'
Organize,
Synthesize,
Interrelate,
and
Display
Technology ^>^
Knowledge ^
Processed
Data
Evaluate,
Innovate,
and
Develop
^
f^
Improved
Operating
Policy
Improved
Maintenance
Procedures
Improved
Plant
Reliability
Improved
Staffing
Levels
Figure 3
Program Flowsheet
-------
maintenance, staffing, and quality control. Section IX deals with the
applications of R&M analyses including the Reliability Model. Section X
discusses the potential application to advanced wastewater treatment
systems. A summary discussion, conclusions, and recommendations
are presented in Section XI.
20
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SECTION IV
CASE STUDY OF A'SECONDARY TREATMENT PLANT
PRERECORDING PHASE
The objectives of the case study phase of the program were to obtain
and develop operational and maintenance data, using various Work Study
techniques at a selected conventional wastewater treatment plant; to
evaluate these data, also using Work Study techniques; and to identify
specific improvement areas. Inherent in this objective was the iden-
tification of those industrial engineering (Work Study) techniques which
could be applied to conventional wastewater treatment plants to achieve
improvement of plant performance. To meet these objectives, it was
necessary to perform certain preparatory tasks prior to visiting a
wastewater treatment plant, including:
Selection of the industrial management areas to be studied
Establishment of the criteria for each industrial management
area
Determination of the industrial engineering (Work Study)
techniques to be used and evaluated during the on-site data
collection phase
Selection of the conventional wastewater treatment plant at
which these Work Study techniques could be applied and
evaluated
Development of selected Work Study documents and data
recording forms which would facilitate the on-site recording
process
Selection of the Industrial Management Areas
The four industrial management areas which were deemed of greatest
importance to existing wastewater treatment plants were:
Operations
Maintenance
Staffing
Quality Control
Design considerations must be added to be above list for new plants.
Since the case study was performed on an existing plant, design functions
were indirectly considered.
21
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Establishment of Criteria
The criteria for evaluating each of the four management areas were
documented to establish the "yardstick" upon which the evaluation of
the case study wastewater treatment plant could be accomplished. They
are addressed in detail in Sections V, VI, VII , and VIII . The criteria,
which are based upon accepted industrial engineering practices, were
obtained from a number of technical publications, the most significant
being:
Handbook of Industrial Engineering and Management,
Edited by W. Grant Ireson and Eugene L. Grant
(Reference 2)
Industrial^ Engineering Handbook, Edited by
H. B. Maynard (Reference 3)
Production Handbook, Edited by Gordon B. Carson
(Reference 4)
Maintenance Engineering Handbook, Edited by
L. C. Morrow (Reference 5)
Design Manual, Civil Engineering, NAVFAC DM-5
Naval Facilities Engineering Command (Reference 6)
Operation of Wastewater Treatment Plants,
Manual No, 11, Water Pollution Control Federation
(Reference 7)
"Federal Guidelines for Design, Operation, and
Maintenance of Waste Water Treatment Facilities, "
Sept, , 1970 (Reference 8)
Quality Control Handbook, Edited by J. M, Juran
(Reference 9)
Determination of Industrial Engineering (Work Study) Techniques
Having established the "yardstick" factors for wastewater treatment
system analysis, the next task was to select from the multitude of
industrial engineering techniques those which offered the greatest
potential for developing improved operating and maintenance policies
or guidelines for all wastewater treatment plants. In selecting these
techniques, emphasis was placed on choosing those that would best
record data and facilitate analysis of the recorded data to evaluate
an existing wastewater treatment plant using the established criteria.
Consideration was also given to the fact that the selected techniques
might ultimately be used by architects and engineers in the design and
staffing of new plants. The selected techniques are discussed under
each Industrial Management area in Sections V, VI,, VII , and VIII. .
22
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Selection of the Conventional Wastewater Treatment Plant
In selecting the conventional wastewater treatment plant for the on-site
survey of operation and maintenance, the following factors were the
major considerations:
Should be representative of a large percentage of olants in
the United States. A capacity of between 10 and 100 MGD was
considered to be desirable.
Processes should include as a minimum primary treatment,
secondary treatment, sludge treatment, and disposal and
disinfection subsystems.
Age of plant should be 5-10 years in order to possess
stability of operation and still have processes of modern
design.
Operating under fairly stringent state or local standards
of effluent quality
Considered by state authorities to be a plant operating
at near-design capacity and having earned the reputation of
being well managed in both the operation and maintenance areas.
State and local government authorities and plant management
be agreeable to contractor personnel conducting the on-site
survey.
An extensive search was conducted to locate a wastewater treatment
plant which satisfied these factors. Several candidate plants were
found from which the Sewage Treatment Plant of the City of Flint,
Michigan, was selected as meeting all of the previously mentioned
factors. A brief description of the Flint plant is contained in sub-
sequent paragraphs.
Development of. Selected Work Study Documents and Data Recording Forms
During the prerecording phase, preliminary Functional Staging Diagrams
(FSD's) were developed wherein the various wastewater treatment pro-
cesses known to exist at the Flint plant were staged down to that level
at which equipment items normally perform the required functions.
These preliminary FSD's were subsequently validated and corrected
during the recording phase. The final version of these Functional
Staging Diagrams is included in this report as Appendix A. A
questionnaire concerning all phases of the operation of wastewater
treatment plant was developed as a guide for conducting interviews
of plant personnel. Specific examples of Work Study tools were pre-
pared and assembled into a package for use in briefing plant man-
agement personnel on the initial day of the on-site survey Several
23
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other standard recording forms such as equipment inventory, flow
process charts, Operational Sequencing Diagrams, reliability and
maintainability data, etc. , were prepared. Some of these forms1 were
used only to record data, the data subsequently being recompiled for
inclusion in this report.
DESCRIPTION OF THE FLINT, MICHIGAN, SEWAGE TREATMENT
PLANT
The Flint Sewage Treatment Plant is located in the center of a 134-acre
site, 2-1/2 miles west of the city limits, adjacent to the Flint River, into
which the final effluent flows. The plant, originally constructed in 1926,
was modernized and expanded during the period 1953-56 and again during
the period 1962-64 when a major expansion was accomplished. The plant
serves Flint, Michigan, an industrial city with a population of about
194,000, as well as several surrounding suburban areas. It is primarily
an automobile manufacturing city, with industries such as auto assembly
plants, auto body works, spark plug manufacturers, paint factories, and
foundries.
The plant incorporates a complete activated sludge system plus a com-
plete trickling filter system, both of which receive influent from a
common primary system with common waste solids treatment and dis-
posal by filtration and incineration. The trickling filter system was
installed as a part of the original plant in 1926 and the activated sludge
system was added during the 1962-64 modernization. A Process Flow
Schematic and a general Plant Layout diagram are contained in Appen-
dices B and C, respectively. A brief description of the plant facilities
follow.
Basic Design Data
Design population 270, 000
Design average flow
Activated sludge 20 million gallons per day
Trickling filter 14 million gallons per day
Anticipated BOD removal over 90%
Expected removal of organic
solids at design flow 60, 000 pounds per day
Capacity of incinerators 90, 000 pounds per day
24
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jVLajor Process Elements
Influent Box. A raw sewage influent structure establishes the
hydraulic head by receiving flow from the Third Avenue Pumping
Station and the Northwest Pumping Station. The liquid level is
maintained at an elevation sufficient to provide gravity flow from
this point through the primary tanks, aeration tanks, final clari-
fiers, and chlorine contact chamber to the receiving Flint River.
The Third Avenue Pumping Station is not an integral part of the
plant. Since the Northwest Pumping Station is located in close
proximity to the plant proper, it is included as a part of the
plant's operation.
Grit Chambers. The sewage passes from the influent structure
through, a venturi tube to two aerated grit chambers. The cham-
ber size provides a detention period of 2. 8 minutes at the average
design flow of 34 MGD. These tanks have hopper units from
which the grit can be pumped as a slurry to the ash and grit lagoon.
However, this latter feature is inoperative and grit is removed
manually.
Screening Chamber. The degritted sewage flows from the grit
chambers through one of four 36-inch comminutors for screening
and cutting of coarse sewage matter
Primary Settling Tanks. Sewage flows from the screening cham-
bers to six primary settling tanks. Each tank is 41. 5 feet wide,
142 feet long, with a liquid depth of eight feet. The combined
volume of 272, 000 ft3 (2, 034, 500 gallons) provides a detention time
of 1.43 hours and a surface settling rate of 1000 gallons/ft2/day
at the design flow rate of 34 MGD.
Each tank is equipped with straight-line longitudinal and cross
collecting sludge scraping mechanisms which scrape the settled
solids to sludge hoppers at the ends of the tanks and skim floating
material to revolving type scum troughs near the outlet end.
Sludge is withdrawn from the hopper and may be pumped: (a) to the
digesters, (b) directly to the vacuum filters and incinerator, or
(c) to the sludge thickener building. Effluent from each primary
tank flows over V-notched weirs through a Parshall flume for
flow measurement.
Distribution of Primary Effluent. The flow of primary effluent is
split so that the major portion (approximately 60 percent) goes in-
to the activated sludge process aeration tanks and the smaller flow
(approximately 40 percent) to the trickling filters. The latter por-
tion passes through a flow meter and enters the settled sewage wet
well. This wet well also receives a portion of the trickling filter
effluent that is recirculated; the mixture of settled raw sewage,
plus recirculated filter effluent, is pumped from the wet well to
the trickling filters.
25
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Trickling Filters. Each of the two fixed nozzle trickling filters,
with concrete dosing tanks, has a filter area of 3. 8 acres. These
are currently operated with a hydraulic loading of 3 million gal-
lons per acre per day and an organic loading of 240 pounds BOD
per acre-foot per day.
Final Settling Tanks (After Trickling Filters). Two final settling
tanks have a capacity of 22. 6 MGD. Humus sludge is normally
pumped to the sludge-thickening building. However, it also can
be pumped to the primary tanks or to the digesters.
Chlorine Contact Tanks - Trickling Filters. The final effluent
from the trickling filters passes to four chlorine contact tanks.
The total volume of these tanks is 68, 000 ft3 and provide over
one hour detention.
Activated Sludge Aeration Tanks. The piping and valve arrange-
ments, meters, and controls allow the use of:
Conventional activated sludge process (normal
mode of operation)
Step-aeration activated sludge
Krause-Nitrification modification of
activated sludge
Three aeration tank units, each consisting of four passes, are
equipped with swing type air diffusers using Saran-wrapped tubes.
To control froth formation, a series of spray nozzles (using final
effluent) are located at the walls opposite those at which diffused
air is supplied. The total 750, 000 ft3 volume provides a five-
hour detention time at a sewage flow of 22 MGD, plus 25 percent
return sludge rate.
Blower Building. This structure houses three centrifugal single-
stage, electric motor driven air blowers. These blowers are sized
to produce a variable air output ranging from 15, 000 cfm to
30, 000 cfm. Space is provided for a future additional blower
Normally, one blower is in operation.
Asbestos-coated bag air filters are provided ahead of the blowers
with sufficient capacity to handle maximum air load to the blowers.
Final Settling Tanks. Discharge from the aeration tanks flows in a
channel tOgthree final settling tanks providing a total volume of
354, 672 ft ' At design flow, the detention time is 1.78 hours,
with a surface settling rate of 1241 gal/ft2/day.
Settled sludge is withdrawn through a sludge collector and sent to
a sludge well from which it is possible to pump return sludge to
26
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both the aeration tanks and to waste. Waste sludge from the acti-
vated sludge system can be sent to the sludge thickening building
or returned to the primary tanks.
Final Effluent Aeration Facilities. In order to provide additional
oxygen in the treated flow before discharge to the Flint River
during the periods of critical dissolved qxygen content in the reach
below the treatment plant, a postaeration tank is provided to
oxygenate the plant effluent before chlorination. The location
of this tank is adjacent to the aeration tanks. Air is introduced in
a manner similar to that used in the aeration tanks; about 10
minutes detention time is provided.
Chlorination Facilities - Activated Sludge. A chlorination contact
tank, located next to the postaeration tank, provides 20 minutes
detention at design flow.
Two chlorine feed machines, each with a capacity of 2000 pounds
per day. are provided and equipped with evaporators, scales,and
alarm.
Chlorine solution may be applied through diffuser units located
at the following points:
Plant influent structure (raw sewage)
Settled sewage wet well prior to trickling filters
Aeration tanks - return sludge entrance
Final effluent chlorine contact tank
Sludge Concentration. In order to decrease the capacity required
in sludge digesters and avoid the difficulties encountered in
settling trickling filter humus and waste activated sludge, a
flotation-thickening process has been installed using pressurized
primary effluent mixed with the sludge being thickened.
Three tanks are housed in the sludge thickening building. Also
contained therein are pumps, piping, valves, meters, and
appurtenances. Provisions are made to thicken primary sludge
and skimmings when required.
This process has successfully thickened 400 gpm of waste acti-
vated sludge at 0. 9 percent solids to 4+ percent using 1200 gpm
of pressurized primary effluent to provide flotation bubbles. The
thickened sludge may be pumped to the digesters or sent directly
to the incinerators. The subnatant is discharged to the activated
sludge aerators for secondary treatment.
27
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Sludge Digestion Storage Tanks. Three 80-foot diameter floating
cover digesters with exterior heat exchangers, meters, and con-
trols originally designed to provide a 30-day detention time at
design loading of 43, 700 pounds of sludge solids per day are
currently utilized for storage of sludge. The digesters are not
operated in the conventional manner; i, e. , sludge digestion.
A gas storage sphere originally installed to collect sewage gas
for use in the digester sludge heat exchangers or the sludge
incinerators is not utilized.
Sludge Dewatering Facilities. Digester sludge, raw sludge,, or a
mixture of the two may be pumped to an aerated 18, 000-gallon
sludge well at the vacuum filter building. The sludge is pumped
from this well with variable speed pumps to a chemical conditioning
tank adjacent to each of three vacuum filters. These filters are
equipped with coil springs as filter media. Each filter, has
360 ft2 area, providing a capacity of 1440 pounds per hour-
dry solids when operating at 4 Ib/ft2/hr.
Equipment for the automatic unloading, storing, handling, slaking,
and feeding of lime to the sludge prior to vacuum filtration is pro-
vided. A rubber lined storage vat, capacity 6000 gallons, is
provided (inside) for ferric chloride solution brought in by truck.
Studies have been made to investigate the improvement filterability
by the use of polyelectrolytes.
Filtered sludge cake is conveyed on belts from the vacuum filters
to the incinerators. A bypass facility is provided to allow for the
conveying of sludge cake to trucks during emergencies.
Sludge Incineration. There are two 6-hearth furnaces, each having
a capacity of evaporating 6500 pounds of water per hour and burning
2200 pounds of dry solids per hour.
Exhaust gases pass through wet scrubbers, using plant final efflu-
ent. The water leaving the scrubbers drops into the ash hopper for
quenching the incinerator ash. The ash slurry is pumped to the
ash and grit lagoon continuously.
Administration Building. This building houses offices, a con-
ference room, laboratory, master meter-control room, employees
kitchen, lunchroom, and washrooms.
Service Building. The original administration building has been
remodeled into a machine and general repair shop, including garage,
spare parts storage, and maintenance supervisor's office.
Recently, the Michigan Water Resources Commission issued new effluent
criteria for the plant which limit the BODs discharged to 3300 pounds per
day, NH3-N to no more than 0. 5 mg/4, 80 percent P reduction and a
28
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maximum suspended solids content of 35 mg/ JL. In addition, the plant is
to be expanded to an average design flow of 50 MGD. Thus, the treatment
plant will be undergoing considerable change in the next few years.
RECORDING PHASE
A detailed on-site survey of the operation and maintenance of the Sewage
Treatment Plant at Flint, Michigan, was conducted in April 1971, with
two additional visits in May and July 1971. Almost 40 man-days were
spent conducting this survey. The following activities were performed:
Previously developed Functional Staging Diagrams and System/
Equipment Staging Diagrams were validated and appropriate
changes, additions, and deletions made to reflect special condi-
tions at Flint.
A preliminary Equipment Inventory List was prepared based upon
the System/Equipment Staging Diagram. This inventory was com-
pared to the fragmentary equipment lists available at Flint and
data collected from plant inspection. From this process, the
System/Equipment Staging Diagram and the Equipment Inventory
List were revalidated. The updated Functional Staging Diagram
and the System/Equipment Staging Diagram are given in Appen-
dices A and D, respectively.
Based upon review of plans, inspection, and interviews with
plant personnel, a process flow schematic (Appendix B) and
a sketch of the physical layout of the plant (Appendix C) were
prepared.
A personnel list, organization, and staffing data, including skill
level, were collected from relevant plant documents and plant
management.
Data on operator maintenance and maintenance staff functions
were recorded from interviews with plant personnel and inspec-
tion of plant records.
Operational Sequencing Diagrams (OSD's) were developed for
the four principal operating positions: foreman, primary
operator.- filter operator, and furnace operator (Appendix E).
These were prepared by observing and recording operator's
movements and activities followed by post-recording interviews
to note deviations. The OSD's included the recording of type
and frequency of inspections and samplings conducted by the
operators. Also included were several of the normal and
nonroutine activities that occur on an unscheduled basis but
are critical to successful operation. It was necessary in some
cases to obtain the OSD data by interviewing the operator because
the activity of interest did not occur during the data collection
phase (for example, a power failure).
29
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Copies of inspection, sampling, preventive maintenance action,
and other recording forms were obtained and were included in
the review. The completion of these forms establishes the activity
pattern of the staff to a large degree.
The operator equipment malfunction logs for the six-month period
October 1970 through March 1971 were reviewed to determine those
equipment failures or malfunctions which affected the plant's opera-
tion and consequently were data inputs for the reliability and main-
tainability calculations.
Key personnel, including the Plant Supervisor, Assistant Plant
Supervisor, and the Plant Maintenance Supervisor, were extensively
interviewed regarding the various aspects of the operation and
maintenance performance of the plant.
Monthly operating reports of the type submitted to the State of
Michigan were reviewed and used as part of the process control
and quality control evaluation.
POST-RECORDING PHASE
Each of the four management areas previously described was studied as
an entity. The data recorded at the Flint Plant were reviewed, evaluated,
and, in many instances, were reorganized to facilitate evaluation for the
specific industrial management area studied.
Additional Work Study techniques such as multiple activity charts, adja-
cency charts, correlation charts, etc., were prepared to assist in evalu-
ation. Each technique selected was carefully studied to ensure that its
application for the intended task was proper. It should be noted that the
major value of the Work Study techniques employed is that they organize
and display data in such a manner that evaluation is simplified. In almost
every case, no new data, such as a mathematical parameter, are developed.
The purpose is to organize and display so that evaluation and innovation
can be facilitated. Thus, the major portion of the post-recording phase
involved:
Evaluating the basic utility of the Work Study techniques applied
Repetitive refinement of the data as understanding of the complex
interrelationships in the plant process increased
Consideration of the data as displayed and organized by the Work
Study techniques in relation to specific criteria
Identification of potential areas where improvements could be
made
Evaluating the effects that these potential improvements could
have
Developing and evaluating various methods of enhancing the
utility of the Work Study techniques
30
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The evaluations, including "yardstick" criteria, the findings, and the recom-
mendations for each of the four industrial management areas are described in
detail in Sections V, VI, VII, and VIII. In addition, considerations of the
application of these techniques to the design of new plants are given in
Section V-
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SECTION V
EVALUATION OF WORK STUDY TECHNIQUES
ON OPERATIONAL ACTIVITIES
In the context of this section, the operational aspects of waste treatment
include the major factors which determine or influence the ability of the
treatment plant to satisfactorily perform its function. Strictly speaking,
this would include almost all activities that one normally associates with
waste treatment including maintenance, staffing level, etc. However,
this section is confined to consideration of process planning or preliminary
design, plant layout, operational procedures, and plant flexibility Later
sections will deal with maintenance, staffing, and quality control, all of
which certainly have an influence on operations.
The following discussion includes a consideration of the criteria for suc-
cess for each of the operational activities, both in the context of classi-
cal industrial engineering and as governed by waste treatment require-
ments, along with a brief discussion of current general waste treatment
practice. This is followed by a discussion of the industrial engineering
techniques that were applied in each area as well as an evaluation as to
their utility. Finally, conclusions and recommendations are presented
on the applicability of the techniques employed.
CRITERIA
Process Planning
In designing or planning a process system, the objectives, in terms of
product goals, are the baseline from which all process planning develops.
For any manufacturing installation, the product requirements must be
clearly stated and understood. Process planning, or preliminary design,
is the translation of product goals into an effective and efficient assemblage
of equipment arranged for optimal operation and maintenance. Normally,
it is an iterative process where the basic equipment elements are first
developed and the final design evolves from a series of trade-offs be-
tween capital and operating costs. Thus, the process planning procedure
should be closely tied to product goals and should provide means for
consideration of other aspects of plant activities such as operating
procedures, maintenance, etc.
Currently, the definition of product goals for waste treatment plants can,
at best, be characterized as variable. In almost every case, the State
regulatory agency, the "customer, " sets the required product character-
istics. However, a problem exists in that between states these require-
ments are neither consistent nor complete. This is not to suggest that
all waste treatment plants should have the same effluent quality. Some
states specify "secondary treatment" as a process requirement with
the implication that the effluent will be of that quality normally
33
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associated with secondary treatment, whatever that may be. Others set
effluent standards in terms of an allowable concentration of certain quality
parameters (BOD, suspended solids, etc. ). Still others state their prod-
uct goals in terms of a maximum amount of a constituent in terms of
pounds per day that can be discharged based upon knowledge of the re-
ceiving stream. This diversity results in a wide variety of design pro-
cedure practices. Another aspect of the setting of process goals is the
large variability inherent in the biological treatment process. Studies
(Refs. 10, 11) have shown that the coefficient of variation of quality para-
meters increases through the treatment plant. That is, there is more
variability in the BOD content around the mean of treated effluent than
in the upstream steps. One would have intuitively expected the opposite
to be true, given the dampening effect of tankage involved of about 10 hours
total detention in conventional activated sludge plants with primary and
secondary clarifiers. On the other hand, the dynamics of biological
treatment under the normal daily or hourly variations in critical process
parameters (inflow rates, BOD, suspended solids, etc. ) are poorly under-
stood. This, coupled with a lack of suitable monitoring instruments,
contributes to an inability to exert close control over the process.
Given these uncertainties, it is not surprising that in many instances the
biological treatment plants merely involve the satisfaction of equipment
design criteria, such as overflow rates for clarifiers, aeration tank deten-
tion time, etc. This approach would fulfill the "secondary treatment"
requirement. In other cases, pilot o~r bench scale plant tests are run to
determine the product quality achievable in terms of the amount or con-
centration of pollutant. In very few cases is the question of variability
addressed since it is almost never required by the regulatory agencies.
Layout
The spatial arrangement of the equipment in a manufacturing process is
important from the standpoint of product flow and ease of operation and
maintenance. In wastewater plants, a primary factor in determining lay-
out is the topography as it relates to hydraulic design, including flow
rates, location of pipes, safety, plant expansion, etc. This subject is
adequately covered in several standard environmental engineering texts
and consequently will not be dealt with in this report. However, once
the topographic considerations are satisfied, there are layout decisions
to be made which may be susceptible to industrial engineering analysis.
For example, one significant criterion is the minimization of the
length of piping and the number of bends to minimize plugging, particu-
larly in the sludge handling systems.
Procedures
If a plant is to produce an acceptable product, the equipment must be
operated in the proper manner. Operating procedures can be divided
into routine, normal nonroutine, and emergency. In many manufacturing
operations, routine operations are highly repetitive. Standard operating
procedures have been developed after careful study to maximize
productivity.
34
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Wastewater plants differ somewhat from most manufacturing facilities
due to the variability of the raw material (sewage). In order to be effec-
tive, the operators of a wastewater treatment plant, particularly the
supervisory personnel, should have a thorough knowledge of the functions
of each unit in the plant, how each unit accomplishes its function, how
to evaluate the operation of each unit,and how each unit fits into the over-
all plant process. The operators should be thoroughly familiar with the
general theory and practice of the operations of the plant and be familiar
with the characteristics of the wastewater to be treated including changes
in flow patterns, organic and solids loadings, industrial wastes, etc.
They should also be familiar with local, state, and federal requirements
which set the standards for the treatment process. This latter item
necessitates the keeping of process records to facilitate appropriate
reporting on a periodic basis to regulatory authorities.
In order to ensure consistent performance the plant should have standard
operating procedures for normal, nonroutine,,and emergency operations.
These operating procedures should include inspection and sample collecting
check-off lists to ensure standardization and uniformity of actions by the
various shift operators. Finally, it is essential that the plant have an
active training program for the operators which enhances not only more
efficient operations but offers advancement incentives for all grades of
personnel, from trainee up to supervisory positions.
In most cases, operating procedures have been developed by trial and
error with certain basic operating functions known at startup. Few plants
have standard operating procedures. Recently EPA, through the "Federal
Guidelines for Design, Operation and Maintenance of Wastewater Treatment
Facilities, " 1970 (Ref. 8) has required an operating manual to be prepared
for new federally-assisted plants. In the past, few plants were equipped
with a comprehensive ana detailed operating manual. Historically, most
manuals prepared were concerned with how each equipment group is op-
erated rather than how the operator functions.
Flexibility
The design of process piping, equipment arrangement, and unit structures
must allow for efficiency and convenience in operation and maintenance
and provide maximum flexibility of operation. Such flexibility should
permit the highest possible degree of treatment to be obtained under
varying circumstances. Since plant operation is a 2 4-hour-a-day,
seven-day-a-week, 52-week-a-year operation, redundancy of certain
key units or equipment is mandatory. In other cases, unit bypasses may
suffice. Provisions should be designed into the systems for removing
the duplicate units from service separately.
35
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APPLIED INDUSTRIAL ENGINEERING TECHNIQUES
During the course of the study, several industrial engineering (Work
Study) techniques were applied. Initially, these techniques were applied
as discrete units; i. e., independent of an overall analysis of a given
aspect of the plant's functions. Upon evaluation, however, it became
apparent that several techniques were applicable to the operational
aspects of wastewater treatment. These are briefly described below.
Functional Staging
Functional Staging Diagrams (FSD's),contained herein as Appendix A,
were developed to methodically document the functions and subfunctions
which a conventional wastewater treatment plant is required to perform
to satisfy the objectives established for primary, secondary, and sludge
treatment processes. They were originally prepared in the prerecording
phase for general application and then refined to meet conditions at Flint.
These FSD's were the basis for subsequent development of Equipment
Staging Diagrams, Function-Capability-Equipment Matrices, and the
Reliability Block Diagrams.
Process Flow Schematic
A Process Flow Schematic for the Flint Sewage Treatment Plant, shown
in Appendix B, was developed by recording the process systems. Ideally,
process flow planning is best accomplished during the conceptual planning
stage in conjunction with the selection of systems and equipment. Appar-
ently, the design engineer did use such a process diagram to develop the
detailed plans and specifications. However, such a diagram covering
the total plant was not available to the recording team.
Physical Plant Layout
An existing Plant Layout Diagram provided by the Flint Plant Supervisor
was agumented to include amplifying data. The diagram is included as
Appendix C. This diagram was used in conjunction with the Process
Flow Schematic to evaluate adjacency of equipment requirements.
System/Equipment Staging Diagrams
The Functional Staging Diagrams were used to develop System/Equip-
ment Staging Diagrams, contained herein as Appendix D. Systems and
subsystems required to perform the stated functions were documented
using the corresponding index number from the FSD to permit the user
to identify the functions associated with the particular system or sub-
system. The lower stages of the FSD's were used to determine the
type of equipment required to perform the functions of the various sub-
systems with the equipment grouped under each subsystem. The
System/Equipment Diagrams were used as a check-off list to establish
an Equipment Inventory List for the Flint Plant. This inventory list was
36
-------
used to evaluate the maintenance system and to develop the reliability
and maintainability calculations. Entries, in the list were made
according to the numerical index developed in the FSD. To illustrate
the complexity of a,sewage plant,. over 250 different equipment entries
were required, not counting multiple or redundant units and subassemblies
such as motors, drivers, etc.
Operational Sequence Diagrams (OSD's)
The Flint plant is organized such that routine operations are conducted,
under the direct supervision of the Plant Supervisor and the Assistant
Supervisor, by three equally manned shifts, each shift consisting of a
Foreman, a Primary Operator, a Filter Operator, and a Furnace Oper-
ator. The routine is such that, with minor exceptions, the inspections,
taking of samples, recording operational data, and normal operating
tasks are the same for each shift. Check-off and recording forms are
provided each operator to ensure that specific inspections, samplings,
and data recordings are made at prescribed times (hourly, every two
hours, twice a shift, once a shift, etc. ). Each operator and the foreman
were observed performing their duties and their actions recorded on at
least two occasions and Operational Sequence Diagrams (OSD's) were
prepared to visually display their actions. The OSD's, contained in
Appendix E, were used, together with additional information concerning
nonroutine and emergency procedures gained_by interviews! of key_jper-
sonnel, to evaluate the operational and maintenance requirements of the
various plant processes. The OSD's were also used to develop data for
analyzing personnel requirements.
Correlation Matrix and Adjacency Chart
A Correlation Matrix and Adjacency Chart were developed and are shown
in Figures 4 and 5, respectively, to demonstrate how a design engineer
might use the techniques during the preliminary design phase to deter-
mine arrangement of process units in a plant or to determine arrangement
of equipment within a space. As indicated in Figure 4, the various
process units are rated relative to their closeness requirements to other
units. The reason for the selected rating value is also shown by code.
The Adjacency Chart was used to evaluate the layout of the existing Flint
plant.
The equipment groupings in the Correlation Matrix are arranged according
to normal process flow. For any equipment grouping, the importance of
proximity to £he other groupings that follow in the process is found by
reading downward the most right-hand column for that equipment group.
Function-Capability-Equipment Matrix
To demonstrate another technique which a design engineer might use
during the preliminary design phase, a Function-Capability-Equipment
Matrix, shown in Figure 6 for the Flint plant, was developed for the
selected function, "Receive Sewage and Remove a Large Portion of
Settleable and Floating Solids (1100), " from the Functional Staging Dia-
gram. This matrix defines the capabilities required to perform the
37
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CLOSENESS VALUE
CO
CO
INFLUENT BOX
GRIT CHAMBER
COMMINUTOR
PRIMARY TANKS
AERATION TANKS
ACTIVATED SLUDGE CLARIF1ERS
CHLORINATION CONTACT TANK
SLUDGE .WELL
BLOWERS
DIGESTERS
THICKENERS
THICKENED SLUDGE WELL
CHEMICAL CONDITIONERS
VACUUM FILTERS
INCINERATORS
ASH LAGOON
RIVER
~}
A
182
0
384
1
384
D
3ft4
N
N
N
N
N
N
N
N
N
N
N
ftWM
1
A
182
1
384
D
3R4
N
N
N
N
N
N
N
N
N
N
0
1 S4
N
1
A
182
N
N
N
N
N
N
N
N
N
N
N
N
N
~i
A
1 82
N
N
A
1 82
N
N
N
N
N
N
N
N
N
1
A
1 82
N
A
1 82
A
384
N
ftj
N
N
N
N
N
N
1
A
82
A
1 82
N
N
N
N
N
N
N
N
N
'TT".T.T
__
/WVS
A
1
D
N
U
ABSOLUTELY NECESSARY
IMPORTANT
DESIRABLE
NOT IMPORTANT
UNDESIRABLE
REASON CODE
~\
N
N
N
N
N
N
N
N
N
A
\ 8*2
1
N
A
3 84
A
3 S4
D
3
N
N
N
N
N
1
N
N
N
N
N
N
N
N
"1
A
3 84
A
3 84
N
N
N
N
N
1
A
1 83
A
3 S4
N
N
N
N
1
2
3
4
~»
A
1 83
1
i a 3
N
N
N
SEQUENCE
GRAVITY FLOW
MINIMUM PIPING
LINEARITY
~l
A
i az
N
N
N
1
A
1 83
N
N
~*
A
1 83
N
~»
N
1
Figure 4
Correlation Matrix
-------
oo
CD
ACTIVATED
SLUDGE
CLARIFIER
THICKENED
SLUDGE
WELL
Figure 5
Adjacency Chart (Excludes Trickling Filter
-------
INDEX
NO.
FUNCTION
REQUIRED CAPABILITY
SYSTEM/EQUIPMENT
11000 Receive sewage and remove a
large portion of settleable and
floating solids
11400
Remove settleable and float-
able solids
Provide capability to receive and treat raw sewage
of the following characteristics:
Total daily flow rate
BOD loading
Suspended solids
34.0 MGD
59, 500 Ibs/day
59, 500 Ibs/day
Remove settleable and floating solids as follows:
BOD 30%
Suspended Solids 60%
Remove organic loadings as follows:
BOD
Suspended Solids
17, 850 Ibs/day
35, 700 Ibs/day
Primary Treatment Subsystem
Primary Clarifier Element
11410 Receive and Contain Wastes
for Settling
11420 CoUect settled solids
Provide:
Overflow Rate
1000 gal/ft /day
Provide capability to remove approx. 6000 Ibs of
sludge per day per tank
Settling Tanks
6 - Tanks, 41. 5' x 142' x 8'
6 - Weirs, 378 ft.
12 - Flight Mechanisms
6 - Sludge Wells (one each tank)
Figure t>
Function- Capability- Equipment Matrix
-------
specified function for the specific plant being designed. The general
concept of the technique is to define the required capabilities for each of
the functions and subfunctions in the functional staging document to facil-
itate the selection of the system or equipment required to perform
that function or subfunction. The matrix, technique is a methodical and
systematic approach to documenting the total capability requirements
of the system and thus creating a structure to establish system design
requirements and to establish a preliminary equipment list for that
system.
Reliability Model
The Reliability Model and associated reliability and maintainability anal-
ysis data documents are discussed in Section IX. Mention of the model
is made only to indicate that it is an industrial engineering technique
applicable to operational aspects of wastewater treatment systems.
FINDINGS
Process Planning
Because the case study was performed on an existing plant, it was not
possible to relate the results of the application of Work Study techniques
to the design process for the Flint Plant. However, several techniques
which were developed for use in studying existing plant activities appear
to be quite useful for the preliminary design of new plants. These include:
Functional Staging Diagrams, System/Equipment Staging, Process Flow
Schematics,and the Function-Capability-Equipment Matrices. The use
of these techniques provides a logical rationale for the development of
an equipment list in which the entries are cross-indexed to required
functions.
The FSD can be a very useful tool in that it identifies all functions that
must be satisfied before equipment selection. Thus it acts as a checklist
for the designer to ensure completeness of his design. This is particu-
larly useful where innovative processes are being developed. In addition,
the FSD could serve as a checklist for the regulatory agency to ensure
that the critical functions are being met.
By using the Function-Equipment-Capability matrix, the design decisions
regarding the satisfaction of required functions are clearly identified.
The design data are organized in a form that is easily extracted for
reports or specifications and facilitates review by regulatory agencies
for technical adequacy. Knowing the required function and capability
permits the designer to evaluate alternative equipment or designs by
comparing performance characteristics against the required capability.
By using the same index system as the FSD's, the equipment designated
in the above matrix is automatically keyed into functions and can be
readily grouped into subsystems. Alternatively, the designer can choose
a more convenient grouping and formulate a new index system. The
41
-------
important factor is that an index system is generated to facilitate
subsequent operation and maintenance management.
The process flow sheet and plant layout obviously assist the designer in
determining the relationships between elements in the overall system.
In most cases, these documents have been prepared to varying degrees
of detail.
One industrial engineering concept which has been poorly handled in the
waste treatment design is the setting of product quality goals. At the
present time, there are great discrepancies between requirements which
lead to a variety of design approaches. If the operational aspects of
biological waste treatment are to be elevated to a science, there must
be much more definitive and consistent effluent quality requirements,
requirements that are based not only on stream conditions, but also
upon knowledge of the inherent variability of biological treatment plant
performance. Until this latter information is developed, there is little
basis for attributing variations in effluent quality to design inadequacies,
operator or equipment failure, or inherent variability.
The degree of difficulty in applying the above techniques to process
planning was not directly measured since they were applied at an existing
plant. Except for the FSD, the techniques involve similar efforts in
collection of data and design decisions as currently practiced. The main
difference is in the organizational format. The preparation of the FSD's
represented a novel approach to consideration of treatment systems.
However, standard FSD's could be developed for use by designers.
Layout
In establishing the layout of the plant and the equipment within a space
in that plant during the detailed design phase, two industrial engineering
techniques can be applied:
Plant Layout Diagram
Correlation Matrix and Adjacency Chart
Although Plant Layout Diagrams are generally applied by design engineers,
the development of such layouts warrants discussion. The Correlation
Matrices together with the associated Adjacency Chart are effective tools
to determine the optimized layout or arrangement of units and equipment.
The technique can be applied to total systems such as demonstrated in
Figures 4 and 5 to subsystems, or to rooms where arrangement of equip-
ment and controls is critical. The technique permits the design engineer
to determine the relative location of units or equipment to each other.
It is extremely useful in translating the man-equipment relationship into
operational arrangements of equipment controls.
42
-------
Evaluation of the layout of the Sewage Treatment Plant at Flint by com-
paring the plant layout shown in Appendix B with the Adjacency Chart,
Figure 5, indicated that the Thickened Sludge Well,Chemical Conditioner,
Vacuum Filter, and Incinerator units would be more effectively located
closer to the Sludge Well, Digester, and Thickener units. This finding
is substantiated by the numerous malfunctions of the piping systems
between the thickener-digester building complex and the incinerator
building due to plugged lines. It is reasoned that if the units involved
were closer together, the shorter length of piping runs and the reduc-
tion of the number of bends would have reduced the number of malfunc-
tions significantly.
It should be possible to develop generalized system Adjacency Charts
for use in design guidelines. Current design manuals make little men-
tion of subsystem location. The charts could be very advantageouslv
used by designers to display dependencies of equipment groups within
buildings or areas.
Procedures
In the development of operational procedures and training of the opera-
tors of wastewater treatment systems, five industrial engineering tech-
niques can be applied. These are:
Operational Sequencing Diagrams
Functional Staging Diagrams
Equipment Staging Diagrams
Process Flow Schematics
Function- Capability-Equipment Matrix
The Operational Sequencing Diagrams (OSD's) proved to be an effective
tool to record the activities of the operators at the Flint plant. The OSD's,
contained in Appendix E reflect all of the normal operations of the plant
which primarily consist of inspections, recording data, and the taking of
samples. While several nonroutine activities are included, there remain
some emergency or other nonroutine actions which were not observed or
recorded due to the seasonal nature of the action or due to the time limit
of the on-site recording. It was found that the recording forms and in-
spection check-off lists that had been developed by the Flint plant were
quite comprehensive and effective in standardizing the normal activities
of the operators. However, in observing or recording by interview the
procedures for routine control and nonroutine operations, such as re-
storing the plant to normal operations after a momentary power failure,
it was found that each operator had his own ideas as to the procedures
to be followed. Thus, standard operating procedures for routine con-
trol and nonroutine operations, with a few exceptions, do not exist at
the Flint plant.
43
-------
This is not unexpected even through Flint is considered a well-operated
plant; most sewage plants do not have standard operating procedures
which are geared to the operator At best, some have operating manuals
that are directed at how the equipment is to be operated. A major problem
at Flint is operator turnover- particularly at the sub-foreman level. If
written standard operating procedures for routine and nonroutine situations
were available, training of new personnel would be greatly facilitated.
The preparation of such routines by plant management would force a
review of current practices and would provide an opportunity for evalu-
ation and improvement.
Similarly, the Operational Staging Diagrams, the System/Equipment
Staging Diagrams, the Function-Capability-Equipment Matrix, and the
Process Flow Schematic are excellent visual training aids. These four
industrial engineering techniques visually display the function of each
unit in the plant, the equipment which accomplishes the function, and
the standards or required capability expected of each unit, thus estab-
lishing a yardstick to evaluate the effectiveness of the unit and also how
each unit fits into the overall plant process. The Equipment Staging
Diagrams establish an indexing system upon which an effective operation
cost accounting system can be based. That is, operation costs codified
by the index number of the equipment staging document would facilitate
evaluation of the costs by specific operational units or categories.
Flexibility
In addition to the findings discussed under Process Planning, the use of
the Reliability Model as an industrial engineering technique to determine
redundancy of equipment or facility requirements can be most effective
during the concept design phase. As indicated previously ^ a discussion
of the Reliability Model and the findings relative to its use as an industrial
engineering technique to determine flexibility requirements are contained
in Section IX.
RECOMMENDATIONS
From the results of the case study findings at Flint as well as consider-
ation of current general practices, the following recommendations are
offered in regard to operational aspects of conventional secondary treat-
ment plants:
Flint Plant
Standard Operating Procedures (SOP's). To complement the
check-off and recording forms which are used to standardize
the inspection and sampling routine operations, it is recommended
that the Flint plant develop SOP's for all nonroutine, emergency,
and routine operations not covered by the check-off forms.
These SOP's should be prepared as shown in Figure 7 using the
OSD techniques as demonstrated in Appendix E.
44
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PROCEDURE - ADJUSTMENT OF RETURN SLUDGE TO AERATION TANKS
NORMAL RESPONSIBILITY - Foreman or Senior Operator
REQUIREMENT - Adjustments in the amount of return sludge to the aera-
tion tanks is necessary whenever the flow rate of the primary effluent to
the aeration tanks varies significantly.
STANDARD OPERATING PROCEDURE
Pumping station reports change in flow rate of raw sewage.
OR
Operator checks "Raw Sewage Flow Printer" ("A-l, " Sheet 3)
on Console "A" in Meter Room and observes change in flow
rate
Refer to "Foreman's log" to obtain current requirement for
"% Return" of activated sludge flow.
Refer to "Return Activated Sludge Flow Conversion Table"
(Sheet 5) Enter left side of table at top with "% Return"1 value
and left column with "Raw Sewage Flow Printer" reading;
obtain "Return Flow in MGD" number.
Example of Step 4:
For a "Raw Sewage Flow Printer" reading of 29 (obtained
from Step 2) and with a current requirement of "% Return"
of 35 (obtained from Step 3), a "Return Flow in MGD" num-
ber of 10. 2 would be obtained from the table.
Enter right side of table at top with "Return Flow in MGD"
number and obtain the "Meter Setting" number.
Example of Step 5:
For a "Return Flow in MGD" number of 10. 2 (obtained from
Step 4) a "Meter Setting" number of 3. 4 would be obtained
from the table.
Figure 7
Sample Standard Operating Procedure
Sheet 1 of 5
45
-------
Adjust the round knobs on "Return Sludge to Aeration & Nit.
Tank Ratio" controls (B-3, C-3, D-3, B-4, and D-4, Sheet 4)
on console "B" to obtain the "Meter Setting" number (obtained
from Step 5) on the "Return Sludge to Aeration & Nit. Tank"
meter (B-l, C-l, D-l, B-2, C-2, D-2, Sheet 4) for each tank
designated to receive return sludge.
Example of Step 6:
Tanks 1, 3, 5, and 9 are designated to receive return sludge.
Before adjustment, meters B-l, C-l, D-l, and B-2 each
read approximately 9. 5.
Turn the round knobs clockwise on controls B-3, C-3, D-3,
and B-4 until each meter reads 10. 2.
Figure 7
Sample Standard Operating Procedure
(Continued) Sheet 2 Qf
46
-------
METER & CONTROL CONSOLE "A"
A B C D E F G
H
Figure 7
Sample Standard Operating Procedure
Return Activated Sludge Flow Conversion Table
(Continued)
Sheet 3 of 5
-------
METER & CONTROL CONSOLE "B1
A B C D
E F G H
CO
ol 1
II11 l§
4 " * * 'o
d CDDDo
i I I II IB
Figure 7
Sample Standard Operating Procedure
Return Activated Sludge Flow Conversion Table
(Continued)
Sheet 4 of 5
-------
Flow
14
16
18
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
25
3.5
4.0
4.5
5.0
5.3
5.5
5.8
6.0
6.3
6.5
6.8
7.0
7.3
7.5
7 8
8.0
8.3
8.5
8.8
% RETURI
30
4.2 .
4.8
5.4
6.0
6.3
6. 6
6. 9
7. 2
7.5
7. 8
8. 1
8.4
8.7
9.0
9.3
9.6
9. 9
10. 2
10.5
35
4.9
5.6
6.3
7.0
7.4
7 7
8.1
8.4
8. 8
9. 1
8.5
9.8
10.2
10.5
10.9
11.2
12.6
11.9
12.3
^
40
5.6
6.4
7.2
8.0
8.4
8.8
9.2
9.6
10.0
10.4
10.8
11.2
11.6
12.0
12.4
12.8
13.2
13. 6
14.0
45
6.3
7.2
8.1
9.0
9.5
9.0
10.4
10. 8
11.3
11.7
12. 2
12. 6
13.1
13.5
14.0
14.4
14.9
15. 3
15. 8
Return
Flow
In
MGD
3.5
4.0
4/2
4.5
4. 8-4.9
5.0
5.3.5.5
5.6-5.8
6.0
6. 3-6.4
6.5-6.6
6. 8-7.0
7. 2-7.3
7.4-7.5
7.7-7.8
8.0-8.1
8. 3-8.5
8.7-8.8
9.0-9.1
Meter
Set-
ing
1.2
1.3
1.4
1.5
1. 6
1.7
1.8
1.9
2.0
2.1
2.2
2. 3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
Return
Flow
In
MGD
9.1-9.5
9.6-9. 8
b.9-10.0
10.2
10.4-10-5
10.8-10.9
11.2-11.3
11. 6-11.7
11.9-12.2
12.3-12.4
12.6
12.8
13.1-13.2
13.5-13.6
14.0
14.4
14.9
15.3
15:8
Meter
Set-
ing
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.9
4.0
4.1
4.2
4.3
4.4
4.5
4.7
4.8
5.0
5. 1
5.3
Figure 7
Sample Standard Operating Procedure
Return Activated Sludge Flow Conversion Table
(Continued)
Sheet 5 of 5
49
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Operation Cost Accounting System. To establish a management
system for evaluating operating costs, it is recommended that the
Flint plant codify operational and maintenance costs with the index
numbering system of the System /Equipment Staging Diagram
contained in Appendix D. This will provide ready identification
of cost factors leading to better cost control.
Training Aids. It is recommended that the Flint plant use the
Functional Staging Diagrams, Appendix B; the Plant Layout Dia-
gram, Appendix C; the Equipment Staging Diagrams, Appendix D;
the Operational Sequencing Diagrams, Appendix E; and the SOP's
developed in response to the above recommendation as visual aids
in the training of regular operators and operator-trainees. These
can be collected in a manual form as a reference source for the
trainee or can be incorporated in an in-service training program.
These documents not only fully describe the logic and procedures
which govern plant operations but also are the basis for ongoing
plant management.
GENERAL
Design Procedure
Because of the benefits derived from the rational organization of data,
it is recommended that the following techniques be considered for gen-
eral use in developing designs and specifications of waste treatment
plants:
Technique Use
Functional Staging Methodical analysis of objective of system;
checklist
System/Equipment Promote equipment checklist; index basis
Staging
Function-Capability- Promote rational design based on capability
Equipment Matrix requirements; checklist for design data
Correlation Matrix and Optimize physical layout and equipment
Adjacency Chart management
Reliability Model Identification of requirements for redundant
elements (See Section IX)
50
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Establish Standard Operating Procedures (SOP's)
In order to optimize efficiency of routine type operations, SOP's should
be required as part of the operating manuals for new or existing plants.
The OSD technique, as shown in Figure 7 and Appendix E, is recommended
as a basic technique for Standard Operating Procedure development.
Using the OSD's and the SOP's, recording forms and inspection check-
off lists can be developed to provide guidance to the operating and
maintenance personnel and assure that the SOP's are followed.
Operation Cost Accounting System
It is recommended that wastewater treatment plants develop System/Equip-
ment Staging Diagrams, similar to Appendix D, not only for design use as
discussed throughout this section, but for use in codifying operational and
maintenance costs. The codifying system should be based on the index
numbering system of the System/Equipment Staging Diagram.
Training Aids
In establishing training programs for new plants or revising existing
training programs, it is recommended that Functional Staging Diagrams
similar to Appendix A, Process Flow Schematics similar to Appendix B,
Plant Layout Diagrams similar to Appendix C, Equipment Staging Dia-
grams similar to Appendix D, Operational Sequencing Diagrams similar
to Appendix E, and Standard Operating Procedures prepared as shown
in Figure 7 be developed and used as training aids.
Development of a Function-Capability-Equipment Matrix for General
Application
It is recommended that the concept of the Function-Capability-Equipment
Matrix technique as shown in Figure 6 be extended to develop a matrix
wherein the design parameters or characteristic elements which define
the capabilities required to perform a specific function are set forth.
The matrix would cover all functions and subfunctions in the Functional
Staging Diagram for all commonly employed unit operations or subsystems.
Design parameters are characteristic elements which are fixed by standards
or by design criteria would be spt forth in quantitative or definitive terms.
Where the design parameters or characteristic elements which have
variable quantities or which cannot be specifically stated due to the re-
quirements of the individual design, they could be set forth so that the
design engineer would only have to fill in the data in an appropriate blank.
The development of such a matrix for all the commonly used unit opera-
tions or subsystems would give the design engineer a tool which would
facilitate his conceptual design task to ensure coverage of all required
capabilities of the total system. Types of equipment required to per-
form the function would be listed. However, the quantity and size of
51
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equipment would be left blank,thus permitting the design engineer to fill
in the information based on his evaluation of the determined capabilities
for the specific function. In addition, provisions would be made to in-
clude alternative equipment if desired. In essence, the matrix could be
a wastewater treatment system design check-off list.
52
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SECTION VI
EVALUATION OF WORK STUDY TECHNIQUES
ON MAINTENANCE ACTIVITIES
No manufacturing facility, no matter how well designed, will be capable
of acceptable performance over an extended period unless it is properly
maintained. This is particularly true of waste treatment plants because
of the characteristics of sewage. Most sewage treatment plants are un-
derfunded to meet general operating expenses. Operational and quality
assurance functions are normally given higher priority since the result
of their neglect is almost immediate: poor performance or insufficient
data for the regulatory agency. Expenditures for preventive maintenance,
however, are relatively long term investments similar in certain respects
to insurance policies; one pays to avoid an undesirable future event. The
amount one is willing to pay depends upon the payer's assessment of the
probability of the event's occurrence and the penalties associated with
the event. Success in this case is not dramatic - the plant performs
as desired. Given the current policies in regard to funding and priorities,
it is not surprising to find that most plants have poor maintenance
management programs.
The following subsections include a discussion of criteria for successful
maintenance programs both in the context of industrial engineering and as
they relate to waste treatment. This will be followed by a description of
the industrial engineering approaches applied in the case study along with
general results and conclusions.
CRITERIA
Maintenance Planning and Procedures
Above all else, proper or optional maintenance is dependent upon an
effective maintenance management program. Preventive maintenance, if
it is to be effective, must be planned and controlled and the procedures
involved must be clearly defined. The objectives of a maintenance manage-
ment program include the development of a system which will:
Define the minimum requirements of planned maintenance
Reduce the maintenance of equipment to simple procedures
easily identified and managed
Schedule and control the performance of work tasks,
inspections, and tests
Describe the methods, materials, tools, and personnel
required
53
-------
Provide for the prevention or detection of impending
malfunctions
Develop and evaluate maintenance cost information
In accomplishing these objectives the maintenance management system
should contain certain basic elements:
Equipment Records. Each piece of equipment must be des-
cribed in detail, listing all information required to locate and
identify the unit and its major components. The information
contained in the Equipment Record Files provides a central
source of information pertinent to the several major aspects
of equipment preventive maintenance. It provides a means
of rapidly reviewing the history of each piece of equipment,
including the past maintenance and repairs, reported main-
tenance cost requirements, and a summary of maintenance costs.
Preventive Maintenance System (PM). The objective of a
sound maintenance management program is to obtain maximum
economy and efficiency in the operation of equipment. An ad-
equate PM system will maintain equipment in a satisfactory con-
dition by providing for the systematic inspection, detection,
and correction of incipient failures, either before !they occur
or before they develop into major defects. The particular
check points on the equipment, the frequency of attention,
and the schedule of performing the PM and follow-up repair
work should all be determined in advance of actual performance
of the work. The work should be measured by time stan-
dards and control procedures should be built into the
system that will indicate the effectiveness of the PM pro-
gram and to make adjustments to improve its effectiveness.
Work Order System. In order to control maintenance work, it
is necessary to have some type of work order system. Such a
system when established should determine the size of the approved
work load, what type of work is necessary, and what that work
is costing. A well designed Work Order System is the core to
effective maintenance operation. It goes beyond being merely
a means to transmit information. It is the tool by which sound
work load planning and scheduling is accomplished.
Planning and Scheduling Maintenance Work. A system should
be established which provides for both short-range and long-
range planning and scheduling to the proper maintenance groups.
Long-range planning and scheduling consist of establishing the
preventive maintenance routines and planned overhauls. Short-
range scheduling includes the assigning of jobs to maintenance
workers on a day-to-day or week-to-week basis. The short-
range planning coordinates the scheduling so that there will be a
minimal conflict with the normal operation of the equipment.
54
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Preventive Maintenance Ratio. One criterion that has been ad-
vanced for utility systems is that manpower resources expended
in preventive maintenance should be at least 50 percent of the
combined total manpower resources spent for both repair
(corrective) and Preventive Maintenance, However experience
has shown that it is not practical to base one plant's amount of
PM on the amount at some other plant. The ratios published
periodically can only be a guide. Each plant must find its own
best level. Control reports should be established to permit
this to be done with simplicity and confidence.
<_
Maintenance Reporting. An effective maintenance management
program includes the provisions for reporting: (1) maintenance
action accomplished for equipment history recording purposes
as both a check for management and as a performance record
for the equipment; (2) material and spare parts expenditures
for restocking purposes and recording of costs; and (3) man-hour
expenditures for recording labor costs and for comparison of
actual times with time standards for the purpose of revising
existing maintenance schedules or establishing new schedules.
Costing,data is essential for establishing budgets. The reporting
system should be simple and easily accomplished by the main-
tenance technicians with limited assistance from clerical type
personnel.
Material Support -
The important elements for obtaining an effective maintenance stores
control system are:
SpareJParts Inventory . The number and type of spare parts
stocked should be based on historical records of consumption and
usage. Materials or spare parts which may be difficult to ob-
tain promptly from suppliers or used in equipment for which
prolonged downtime is considered costly or unsafe should be
considered as high priority on the inventory list. Materials
and replacement parts required for scheduled maintenance
should be anticipated and procured in sufficient time so as to
not delay work.
Inventory Control. Adequate records should be maintained to
control issuance of to'ols and materials and to control the re-
plenishment of these materials. Material should be maintained
in usable condition and easy to locate when needed. The latter
is best accomplished by a classification system which is based
on a code number keyed to the material type or in the case of
spare parts, to the specific item of equipment. Costing data
should also be documented to facilitate the reporting of main-
tenance costs to management.
55
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APPLIED INDUSTRIAL ENGINEERING TECHNIQUES
Several industrial engineering techniques that were applied in the re-
cording, development, and evaluation of data at the Flint plant were
related to maintenance activities; these are discussed below.
Functional Staging
Functional Staging Diagrams (FSD's), Appendix A, were developed to
visually display the functions and subfunctions which a utility plant
maintenance group is required to perform. Functions and subfunctions
down to the fourth level are shown in the FSD's. Subfunctions below
the fourth level for preventive maintenance only were developed as
part of the effort to determine staffing requirements and are included
in the Operational/Maintenance Task Matrices, Appendix F. These
matrices are discussed in Section VII.
System/Equipment Staging Diagrams
The System/Equipment Staging Diagrams, Appendix D, and the equip-
ment inventory for the Flint plant developed therefrom, which were
discussed in Section V, were developed and used as a check-off list
to determine which equipment was required to be included in the Pre-
ventive Maintenance Program.
Maintenance Procedure Evaluation (MPE) Worksheet
To demonstrate an industrial engineering technique for developing pre-
ventive maintenance requirements for specific equipment, a Maintenance
Procedure Evaluation (MPE) Worksheet Figure 8, was prepared. This
worksheet is basically a Critical Examination Analysis worksheet and,
as such, methodically records the WHAT, WHEN, WHO, and HOW of a
required maintenance action. It includes the evaluation of data gathered
from such documents as manufacturers' technical manuals, maintenance
handbooks, standard timetables, and related reliability data. The MPE
worksheet was used to develop the Maintenance Procedure Card (MPC)
which is shown in Figure 9 for a raw sewage pump.
Operational Sequence Diagram (OSD)
The flow process of a requisition for a spare part was documented by the
OSD technique from the inception of the requirement for the spare part
to the receipt of the part and the preparation of the payment document.
This document, shown in Appendix E, was prepared to indicate how
management functions could be effectively displayed for convenient eval-
uation.
56
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MAINTENANCE PROCEDURE EVALUATION WORKSHEET
(MAINTENANCE PROCEDURE CARD DEVELOPMENT)
M.P. _
ring clearances Annually
SUBSYSTEM
Primary
FUNCTION .Transfer raw
COMPONENT.
Raw Sewage Pump
pimping Statinn Upt Upll tn
Influent Box and Establish
Hydraulic Head.
RECORD
PRESENT METHOD
MANUFACTURER'S RECOMMEDATIONS
Notify plant operator of pump
to tie worked on
Drain pump casing
Remove upper access covers
O OP
D INSP
!
i
2
3
p
Mini
5
60
60
EXAMINE
ANALYZE:
a WHAT t.WHY
b. WHERE 2. OTHER
C.WHEN
d WHO
e. HOW
a - 1 1-a Keep plant
operator -informed on Mach.
status.
b Control Room
c Before starting Maint.
d - Maint. Mechanic 1-d
Qualified
e - Tell plant operator
a - Z l-a Al low tor
removal of access covers to
take readings.
b - Casing drain valve
c Rpfn^p rpmrwing arrpssp
d - Mai nt . Mpr ha n i r
e - Drain casing to below
lower (suction head)
ring.
a - 3 Expose wearina rinas
b - Upper casing head
c - Casing drained
d - Maint. Mechanic
e Remove 43" pipe
plugs provided in
upper head
CREATE ft DEVELOP EVALUATE
IMPROVE METHOD'
SIMPLIFY
CHANGE SEQUENCE
COMBINE
CLARIFY
PRELIMINARY
a. Inform operator pump # out
of service for maintenance.
b. Drain casing sufficiently to
obtain readings between
suction head ring and impeller
ring
a. Remove pipe plugs in upper
casing head (4)
f
10
1
2
3
I
P
[Min)
^
60
fin
TOOLS, MATERIAL
AND
TEST EQUIPMENT
Nnn^
None
18" pipe wrench
HAZARDS TO MAN
AND
EQUIPMENT
Safety prer -
Ensure pump &
suction valve de-
energized.
None
NO. OF
MEN
a
RATE
MM
MM
MM
C71
Figure 8
Sample Maintenance Procedure Evaluation Worksheet
Sheet 1 of 3
-------
MAINTENANCE PROCEDURE EVALUATION WORKSHEET
(MAINTENANCE PROCEDURE CARD DEVELOPMENT)
Measure wearinq
M
SUBSYSTEM
Primary
FUNCTION Transfer raw sewage from
Pumping Station Wet Well to Influent
Box and Establish hydraulic head"
COMPONENT Raw SpwanP Pump
RECORD
PRESENT METHOD
MANUFACTURER'S RECOMMEDATIONS
Measure Ring Clearances
Reinstall Pipe Plugs
Remove Lower Access Covers
O OP
D INSP
!
c/T
4
5
6
t
P
Win)
fin
fin
60
EXAMINE
ANALYZE:
aWHAT 1.WHY
b. WHERE 2. OTHER
c. WHEN
d WHO
e. HOW
a .- 4 1 -a Make known
ring clearance
b - Between casino & impel
ring. 1-b where wear
occurs.
c - Pipe plugs removed
d - Maint. Mechanic
e - With feeler gauge
2-3 Taper Gauqe - Not as
accurate as feeler. Give
Mfr's allowances.
a - 5 Reassemble unit
b - Casing - where removed
c - After readings taken
d - Maint. Mechanic
e - Screw into holes
a - 6 1-a Expose Lower
wearing rings
b Lower casing head
d - Maint. Mechanic
e - Remove screws and
nuts from covers (4)
CREATE 8 DEVELOP EVALUATE
IMPROVE METHOD'
SIMPLIFY
CHANGE SEQUENCE
COMBINE
CLARIFY
b. Measure wearing ring
clearance through pipe plug
Maximum n ^no"
c. Reinstall pipe pluas
d. Remove hand hole covers
in lower casing head (4)
-
o
.£)
1
4
fi
6
1
i-
Min)
n
;n
iO
TOOLS, MATERIAL
AND
TEST EQUIPMENT
Rag";
Feeler gauge
Flashlight
18" pipe wrpnr.h
10" adjustable
wrench
6" normal duty
<;rrpwHriv°r
HAZARDS TO MAN
AND
EQUIPMENT
d|nne
Nnnp
None
NO. OF
MEN
a
RATE
MM
MM
MM
co
Figure 8
Sample Maintenance Procedure Evaluation Worksheet
(Continued)
Sheet 2 of 3
-------
MAINTENANCE PROCEDURE EVALUATION WORKSHEET
(MAINTENANCE PROCEDURE CARD DEVELOPMENT)
M.P. PFscnipTinii Measure wearing
ring clearances - Annually
SUBSYSTEM
Primary
FUNCTION _Transfer raw sewage
COMPONENT.
Raw Sewage Pump
'from Pumping Station Wet Well to
Influent Box and Establish
Hydraulic Head.
RECORD
PRESENT METHOD
MANUFACTURER'S RECOMMEDATIONS
Measure wearinq rinq clearance
Reinstall covers
Notify Operator when finished
Note: When Max. Clearance of .300"
is reached, notify Maint.Supvr.
wear rate indicates that pump will
reach max. wear limit of .312" and
require replacement uf wearing ring
in approx. b to a montns nence.
O OP
a INSP
I
7
a
9
5
1
p
Min)
fin
60
5
EXAMINE
ANALYZE'
a. WHAT 1.WHY
b. WHERE 2. OTHER
C.WHEN
dWHO
«. HOW
a - 7 1-a Make known
clearance
b - Between casing and
impeller ring 1 -b where
wear occurs
c - Covers removed. Rinas
accessible thru openings
d, - Maint. Mechanic
e - Feeler gauge 1-c Get
accurate readings, tnve
Mfr. allowances
a - 8 1-a Reassemble unit
b - Lower casing head
c ~ Readings taken
d - Maint. Mechanic
e - Reinstall with screws
a, ni|t<;
a 9 1-a Keep plant
operator informed of
Mach. status.
b - Control Room
c - Maint. complete
d - Maint. Mechanic
e - Tell plant operator
CREATE a DEVELOP EVALUATE
IMPROVE METHOD:
SIMPLIFY
CHANGE SEQUENCE
COMBINE
CLARIFY
e Measure wearing rinq
clearance through hand hole openings
Minimum 0.030", maximum 0.300".
. f - Reinstall hand hole covers
g - Notify operator maintenance
complete. Remove warning tag.
Subtotal
10% Factor
Total
f
10
/
8
q
9
E
i-
(Min)
60
60
tj
430
43
473
TOOLS, MATERIAL
AND
TEST EQUIPMENT
Feeler gauge
Kags
Flashlight
10" adjustable
wrench
6" normal duty
screwdriver
= 8.0 m/h
HAZARDS TO MAN
AND
EQUIPMENT
None
None
NO. OF
MEN
a
RATE
MM
MM
MM
t-n
vo
Figure 8
Sample Maintenance Procedure Evaluation Worksheet
(Continued)
Sheet 3 of 3
-------
SUBSYSTEM
Primary
COMPONENT
Pump
'SYSTEM INDEX NO.
1 1 1 00/03 ::
FREQ.
-3
EQUIPMENT
Sewage Pump & Motor
MANUFACTURER
Chicago Pump
MAINTENANCE
PERSONNEL
Maint.Mech.
M/H
8.0
LOCATION
Northwest Pumping
Station - Pump Level
RELATED MAINTENANCE
None
SAFETY PRECAUTIONS
1. Observe standard safety precautions.
2. Ensure pump controller and suction valve have been
de-energized. Tag switch.
TOTAL M/H
8.0
ELAPSED TIME
8.0
MAINTENANCE REQUIREMENT DESCRIPTION
1. Measure wearing ring clearances.
TOOLS, PARTS, MATERIALS, TEST EQUIPMENT
1. Rags 4. 18" Pipe wrench
2. Flashlight 5. 10" Adjustable wrench
3. Feeler gauge 6. 6" Normal duty screwdriver
PROCEDURE
Preliminary
a. Inform operator pump # out of service for maintenance.
b. Drain pump sufficiently to obtain readings between suction
head ring and impeller ring.
Measure Wearing Ring Clearances.
a.
b.
c.
d.
e.
f.
g.
NOTE:
Minimum
Minimum
Remove pipe plugs in upper casing head (4).
Measure wearing ring clearance through pipe plug openings.
.030", maximum .300".
Reinstall pipe plugs.
Remove hand hole covers in lower casing head (4).
Measure wearing ring clearance through hand hole openings.
.030", maximum .300".
Reinstall hand hole covers.
Remove warning tag and notify operator maintenance complete.
When maximum clearance of 0.300" is reached, notify maintenance
supervisor. Wear rate indicates that pump will reach maximum wear
limit of 0.312" and require replacement of wearing rings in
approximately 6 to 8 months hence.
MAINTENANCE PROCEDURE CARD (MPCI
Figure 9
Example of Maintenance Procedure Card
60
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Standard-Time Tables
Tj.me standards for accomplishing various maintenance and service tasks
are contained in several industrial engineering handbooks. These standards
are based on data gained by time and motion studies. The data are based
on statistical sampling and are applicable to those maintenance functions
that are commonly practiced (lubrication, replacing wiring, etc. ). The
reference use of these standards as an industrial engineering tool to
develop maintenance procedures is generally highly advantageous.
FINDINGS
Maintenance Planning and Procedures
In developing a maintenance management program for a wastewater treat-
ment plant, three industrial engineering techniques or tools can be applied:
System/Equipment Staging
Maintenance Procedure Evaluation (MPE) Worksheet
Standard-Time Tables
The logical steps in planning maintenance actions and developing main-
tenance procedures for specific plant equipment are: (1) develop System/
Equipment Staging Diagram to establish an equipment inventory for the
plant; (2) Analyze the preventive maintenance requirements for each piece
of equipment using the Maintenance Procedure Evaluation (MPE) Worksheet,
Figure 8, with standard times applied to the work covered; (3) prepare
Maintenance Procedure Cards (MFC's), such as shown in Figure 9, for
each preventive maintenance action (daily, weekly, etc.) for each com-
ponent of the equipment requiring such maintenance action; and (4) develop
master schedules based on the frequencies of maintenance action set
forth in the individual MPC's. The MFC so developed sets forth the
procedures in simple instructions, defines minimum requirements, and
lists the time, materials, tools, and personnel skill requirements. The
collective MPC's for a plant are the basis of the maintenance management
program and also serve as an excellent training tool.
The Flint plant was found to have a simple but reasonably effective pre-
ventive maintenance program for the machinery group which consisted
of mimeographed check-off lists delineating general areas of maintenance
action for all equipment. The check-off lists were grouped by location
and by frequency of action (weekly and monthly). Detailed instructions
were not provided; therefore, the Maintenance Mechanic was required
to interpret the general instructions to determine his own methods or
procedures for accomplishing the task. The check-off lists are issued
by a work-order system which is effective in assigning the work to the
proper maintenance group and skill. The work-order system provides
for recording of maintenance action taken for machinery history purposes.
61
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purposes. However, the system does not provide for recording of
man-hours or material cost data. Due to the magnitude of repair or
corrective maintenance of instruments and electrical equipment and
shortage of an electrician, the plant performs very little or no preven-
tive maintenance on electrical equipment. The plant expends approx-
imately 10 percent of manpower resources on scheduled preventive
maintenance, 20 percent on nonscheduled preventive maintenance, and
70 percent on repair or corrective maintenance.
In summary the Flint plant has a partially successful maintenance pro-
gram What is lacking is an overall management program to document
and standardize actions and to evaluate the costs and effectiveness, of the
program.
Material Support
The index system of the System /Equipment Staging Diagram, Appendix D,
provides a classification system for grouping spare parts. Spare parts
would then be keyed to the specific item of equipment, thereby facilitating
the recording of cost data by systems or subsystems. If the maintenance
records are also keyed to the System /Equipment Staging index system, the
developing of usage data for spare parts would be facilitated.
The Flint plant has an informal inventory control system which does not
facilitate recording of spare parts usage or cost data.
RECOMMENDATIONS
From the results of the case study at the Flint plant as well as consider-
ation of current general practices, the following recommendations are
offered in regard to maintenance management programs for conventional
secondary plants.
Flint Plant
Maintenance Control Indexing System, It is recommended that
the Flint plant adopt an indexing system for all equipment based
on the System/Equipment Staging Diagram, Appendix D. This
will provide a standard framework for a system for data col-
lection, recording, and retrieval on equipment maintenance re-
quirements, actions, and costs,
Maintenance Procedure Cards. In order to ensure uniformity
in maintenance actions and to clearly identify maintenance re-
quirements, the preparation of maintenance procedure cards
is recommended. This will not only avoid variations in the
quality of maintenance but will also be a valuable training aid.
62
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Additional Maintenance Personnel. As stated earlier, a rule of
thumb for a maintenance program for utility systems that is under
control is to have at least 50 percent of the maintenance effort
put into preventive maintenance. Although this is only a guide,
it is a known fact that more PM than is needed at the beginning
is less costly in the end'. Less PM than is needed almost always
results in more emergency or corrective maintenance which
cannot be scheduled and is inefficient from a manpower application
point of view. At Flint, only about 30 percent of maintenance is
PM. It is recommended that an additional maintenance specialist,
an electrician, be hired to perform the electrical PM which is
now inadequately handled.
General
Maintenance Program Development. In establishing a preventive
maintenance program for new plants or revising procedures at
existing plants, it is recommended that a comprehensive maintenance
management program be developed using the following techniques:
Use the System/Equipment Staging Diagrams to establish
an equipment inventory list that is conveniently indexed
Identify maintenance requirements for each piece of
equipment using an extension of the function capability/
equipment list
Analyze PM requirements for each component using the
Maintenance Procedure Evaluation Worksheet
Prepare Maintenance Procedure cards
Develop Master Maintenance Schedule
Detailed descriptions of procedures for the development of main-
tenance management programs should be presented in a manual
for general use by wastewater plant managers.
63
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SECTION VII
APPLICATION OF WORK STUDY TECHNIQUES
TO STAFFING OF WASTEWATER TREATMENT PLANTS
DISCUSSION
Successful production of any product, including treated sewage, is de-
pendent upon the effective application of men and equipment suitable for
performing the required tasks. Staffing of a plant includes the number
of people required as well as their skill level. The application of the
staff has previously been discussed in terms of operations and maintenance
functions. This section will deal with techniques used to develop staffing
levels.
Currently, staffing at waste treatment plants is determined on an empirical
basis. Some of the larger consulting firms maintain data from past ex-
perience from which they base their recommendations. Currently, an
EPA sponsored project is attempting to collect staffing data from a large
number of plants of various designs and capabilities. The expected
results are a series of correlations between plant size and staffing. Using
this information, a designer could estimate required staff by use of a
series of charts derived from a large number of existing plants. The es-
timate must be modified by the particular conditions and design of the
plant under consideration. In most cases, however staff size determination
for new plants is based upon minimal analysis of requirements and can
be considered as an educated guess. This is modified for new or expanded
plants by the willingness of the governmental unit (city, county, etc. ) to
provide operating funds. In those cases where the regulatory agency has
not set stringent effluent quality requirements, there is little incentive
for the plant to be adequately staffed. Thus, treatment plant management
can be faced with the need to request additional operating funds for staff
from an already tight municipal budget without having strong backup jus-
tification in the form of accepted staffing standards or strong regulatory
pressure.
The usual procedure that would be used by industrial engineers for de-
termining the value of an individual job with other jobs in an organization
is job evaluation. The salient features of the procedure are that it:
Starts with job analysis
Obtains relative rather than absolute values
of jobs
Groups the jobs into classes for which minimum
and maximum wages are established
65
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Of the three characteristics above, job analysis is probably the most im
portant because it is the foundation for the whole job evaluation structure.
It is the procedure that would be used to develop personnel requirements
for a job. A job is defined as a combination of tasks. A job normally
consists of (1) preparation, (2) travel, (3) task performance, (4) cleanup,
and (5) allowances. (The latter covers such factors as personal needs,
fatigue, unavoidable delays, and the effect of the environment.) Job anal-
ysis involves a careful study of each job to find out just what the job in-
cludes, what the job-holder does, how he does it, under what conditions
the job is performed, how the job relates to other jobs, and what special
qualifications the job-holder must have. It is an intensive, direct method
of obtaining the pertinent facts about jobs. It includes the observation of
the job and the reporting of facts which are observed and which are ob-
tained in conversation with workers, supervisors, and others who have
information of value.
In analyzing an operation to determine effectiveness, three factors are
involved which management can use as a productivity index:
Utilization the degree to which resources are
productively occupied
the way in which resources are used
x
[ Performance [ the level of skill and effort expended
while productively occupied
Productivity Index
An estimate of potential benefits can be shown by an example. The
present level of productivity is established by estimating a percentage
value for each factor and multiplying them. Assume that in a given
maintenance group, the workers are utilized productively for 70 percent
of available hours, that the methods level used while working is 80
percent, and that the workers have an average performance level of
95 percent. The productivity index for the group is:
70% x 80% x 95% = approximately 53%
To continue the example, suppose there are ten men working in this de-
partment. With a productivity level of 54 percent, the same work could,
theoretically, be produced by six men (54 percent of 10 men). This could
only be done if each productivity factor were raised to 100 percent. This
is not unrealistic but would be quite difficult and costly to achieve. It is
realistic, however, to raise the utilization level from 70 percent to
85 percent and to improve the methods level from 85 percent to 95 percent.
With performance unchanged, the new productivity level is shown on the
following page.
66
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85% x 95% x 95% - approximately 77%
The difference in manning would be:
7?^o"o/53% = approximately 42%
or
42% x 10 men = 4 men
Productivity is, therefore, a result or the end product of management
effectiveness. Methods are dependent upon the degree of attention manage-
ment provides in determining how a work task is to be performed. In
addition, management can exert a great influence on productivity by im-
proving the utilization of the workers' time. To do this,it has only to
concentrate on the application of improved work load planning and manage-
ment controls.
Regular operations in a utility or service type plant are relatively minor
in comparison to maintenance. One of the most important maintenance
functions is that of inspections. In order to emphasize preventive maintenance
and thereby minimize repair or corrective maintenance, only the most
skilled and experienced men should be used for maintenance inspections
since these people are most qualified to identify potential problems.
A major factor which influences employee performance is morale. In
general there are four factors in which workers are interested: (1) se-
curity (including pay); (2) opportunity; (3) recognition; and (4) inclusion
(awareness of being part of an operation). In order to satisfy these
elements, particularly the second, plant management should have a
"career ladder" or incentive program where employees qualify for
higher positions within the plant organization or within a broader organi-
zation, such as a municipal public works department, on the basis of
general ability and skills acquired through intensive training courses.
Given basic intelligence and desire, "hard core unemployed" could be
employed at the lower levels and by participation in such training pro-
grams progress to the higher levels.
APPLIED INDUSTRIAL ENGINEERING TECHNIQUES
Because of the nature of the preceding features, industrial engineering
techniques, as such, are only applicable to certain aspects of staffing
determinations. In other cases, current conditions in the waste treat-
ment field are compared to practices in industry and are discussed in
a later section.
67
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Operational Sequence Diagrams (OSD's)
The OSD's, contained in Appendix E and'discussed in Section V, were
used to develop not only the operational requirements of the plant but also to
develop data for analyzing personnel requirements. The activities of
the four operator positions (Foreman, Primary Operator, Filter Operator,
and Furnace Operator) were recorded. The OSD's documented what the
job included, what the operator did, how he did it, where he did it, and
how long it took for him to do it.
Operational/Maintenance Task Matrices
The Operational/Maintenance Task Matrix Technique was formulated
and developed during the project to satisfy a need to display the opera-
tional and maintenance tasks or functions that were required in the various
subsystems of a wastewater treatment system and to identify the skill
of the operator performing the function. The Operational/Maintenance
Task Matrices for the subsystems - Primary, Activated Sludge, Trickling
Filter, Air Flotation, Anaerobic Digestion, Dewatering, Incineration
and Ash Disposal, and Chlorination - are contained in Appendix F. The
functions or tasks were developed from the OSD's and the preventive
maintanance actions documented during the on-site recording phase.
Tasks are grouped by the categories: Inspect & Record, Sampling, Nor-
mal Operations, Nonroutine Operations, and Preventive Maintenance.
Estimated times, based on the OSD recorded times and performance
times reported by the maintenance supervisor for the Flint plant, are
indicated for each type evolution (hourly, every two hours, etc. ). Skill
titles for operators are those listed and defined in the U. S. Department
of Labor Dictionary of Occupational Titles. Skill ratings for operational
tasks are indicated by relative ratings of high,, medium,-and low within
the indicated skill code.
Multiple Activity Chart (MAC)
A Multiple Activity Chart (MAC), Figure 10, was developed to visually
display the relationship of the activities of the four operators during a
normal eight-hour shift in order to evaluate the utilization of the operators.
The MAC displays how each of the operators spends his time during a
normal shift. The activities shown in Figure 1:0 were derived from the
OSD's and other on-site observations such as number and duration of
meal, relaxation, and assigned cleaning work periods. The dark areas
indicate available periods for normal operations which are performed on
an "as required" basis such as adjustments to process controls or
equipment required by normal changes in the flow rate or other opera-
tional factors. The MAC is representative only of what occurs in a nor-
mal eight-hour shift. The occurrence of an "as required" event or a
nonroutine event, such as pipe stoppage, would cause the indicated
events to vary from the norm. Included in the dark area is idle time,
time when "as required" tasks are not being performed, which could be
available for productive work. The tasks and associated times shown
in the MAC are true only for the Flint plant. The same tasks performed
at another plant, where the layout of buildings and equipment is different
would be displayed somewhat differently.
68
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SEWAGE TREATMENT PLANT- FLINT MICHIGAN
MULTIPLE ACTIVITY CHART
FOR
TYPICAL EIGHT HOUR SHIFT
^Donates time available for Non-
\ Routine operations and additional
Preventive Maintenanca,
TIME
HOURS
.
5
n
FOREMAN
FINAL EFFLUENT, ASSIGNS
WORK AND SUPERVISES
RECORDS HOURLY METER
ROOM READINGS, INSPECTS,
SAMPLES, ANALYZES MIXED
COFFEE BREAK
LIQUOR AND FINAL
EFFLUENT, ASSIGNS WORK
AND SUPERVISES
OPERATORS.
RECORDS HOURLY METER
MEAL TIME
SAMPLES, ANALYZES
MIXED LIQUOR AND FINAL
OPERATORS.
RECORDS HOURLY METER
ROOM READINGS, INSPECTS,
SAMPLES, ANALYZES MIXED
COFFEE BREAK
LIQUOR AND FINAL
EFFLUENT, ASSIGNS
WORK AND SUPERVISES
OPERATORS.
PRIMARY
OPERATOR
INSPECT,
RECORD
SAMPLE
NORMAL OPERATIONS
PREVENTIVE MAINTENANCE
INSPECT, RECORD
AND SAMPLE
NORMAL
OPERATIONS
* * ' ' >-'-
INSPECT,
RECORD
SAMPLE
NORMAL OPERATIONS
COFFEE BREAK
INSPECT, RECORD
AND SAMPLE
NORMAL OPERATIONS
« ','""' ', ' '!"
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RECORD
AND
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INSPECT, RECORD
AND SAMPLE
NORMAL
OPERATIONS
PREVENTIVE MAINTENANCE
INSPECT,
RECORD
AND
NORMAL OPERATIONS
COFFEE BREAK
INSPECT, RECORD
AND SAMPLE
CLEANING
ASSIGNMENT
FILTER
OPERATOR
INSPECT
AND
RECORD
NORMAL
OPERATIONS
INSPECT, RECORD
NORMAL OPERATIONS
PREVENTIVE MAINTENANCE
CLEANING
ASSIGNMENT
INSPECT
AND
RECORD
NORMAL OPERATIONS
" »V V£VV ' ;
COFFEE BREAK
INSPECT, RECORD
NORMAL OPERATIONS
PREVENTIVE MAINTENANCE
CLEANING
INSPECT
AND
MEAL TIME
INSPECT, RECORD
NORMAL OPERATIONS
PREVENTIVE MAINTENANCE
&& ''' "'
INSPECT
AND
RECORD
';', ?//,'',',,' ,
COFFEE BREAK
INSPECT
AND
RECORD
NORMAL OPERATIONS
PREPARES
REPORT
FURNACE
OPERATOR
INSPECT, RECORD
AND SAMPLE
NORMAL OPERATIONS
, /' ' /? ' ;'?'"^fo;
' ' ' '/'/f/l
J /$ /.''t
."&' -^y"
INSPECT, RECORD
AND SAMPLE
NORMAL OPERATIONS
' , ' ' #??'
, '- »,« _ Jji-
,^ '
INSPECT, RECORD
AND SAMPLE
; '- * , '
-. .:/£.
COFFEE BREAK
INSPECT, RECORD
AND SAMPLE
NORMAL OPERATIONS
^
-------
FINDINGS
In developing the operational and maintenance personnel requirements
for a wastewater treatment plant, four industrial engineering techniques
or tools can be applied:
Operational Sequence Diagrams (OSD's)
Operational/Maintenance Task Matrices
Multiple Activity Charts (MAC)
Standard-Time Tables
The above techniques provide an effective combination of methodologies
for job analysis to determine personnel requirements for either existing
wastewater treatment plants or new plants. In the latter case, the
Functional Staging Diagrams, the System/Equipment Staging Diagrams,
the Function-Capability-Equipment Matrix, and the Operational/Mainte-
nance Task Matrices would permit the job analyst to develop the OSD's by
synthesizing the tasks or functions that would have to be performed.
The four techniques, when used in combination, permit the job analyst
to methodically document the individual tasks or functions which comprise
the total job. Thus, he is able to eliminate, add, or modify single ele-
ments of a job to establish job requirements. He is also able to assess
the utilization of the worker and add, delete, or reassign individual tasks
or functions. As an illustration, the Operational/Maintenance Task Ma-
trices, Appendix F, indicate that several tasks in the same operational
area can be performed by low-skilled operators, while others require
medium-skilled operators. Thus, an option exists either for assignment
of the low-skilled tasks to an operator-trainee and the medium-skilled
tasks to a qualified operator or assignment of all the tasks to a medium-
skilled operator. The analyst is assisted in making a decision by selective
assignment or reassignment of tasks on a Multiple Activity Chart where
he can evaluate the utilization of the operators.
The job analysis of the Flint plant indicates that the operational group
consisting of a Foreman, Primary Operator, Filter Operator, and Fur-
nace Operator is an effective organizational component. However, as
indicated in the Multiple Activity Chart based on normal activities of a
shift, a small amount of time in the "as required" category is available
for assignment to other tasks such as additional preventive maintenance
functions. In effect, better utilization of operating personnel can be ob-
tained by assigning additional tasks which have no stringent time limita-
tions (example: lubrication of certain equipments each month) to the
operator to perform during the "as required" period when no "as re-
quired" tasks are in fact required.
70
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The Operational/Maintenance Task Matrices, as developed, proved to
be an excellent tool for collecting, organizing, and displaying O&M
requirements at an existing plant. The data given in Appendix F, while
not strictly applicable to other plants, could serve as a guide to the type
of O&M activities generally required.
In addition to the study of staffing levels, personnel effectiveness was
also considered. Through interviews with plant management, it was
determined that the major problem facing the plant was the high turnover
rate. This is not atypical of waste treatment plants although there are
notable exceptions. An understanding of this phenomenon can be derived
by considering the four factors generally considered important by workers:
security (pay); opportunity; recognition; and inclusion. Security, particu-
larly in regard to pay, is a major source of dissatisfaction in waste treat-
ment plants. For a variety of reasons, the wage scale for sewage plant
workers is low. Wages, of course, are set by the operating budget which
is an indication of the perceived importance of the sewage plant operation
by the local governmental unit. That perception is strongly influenced
either by society (i.e. the voters) or by the regulatory agency (which also
should respond to societal pressures). In most cases, neither has exerted
much pressure to hire quality operators. Until that happens, job satis-
faction through equitable pay will be elusive.
There are some who argue that certification of operators would increase
their professional status. The degree of interest in improving the "lot"
of the operator can be deduced by the slow progress of the certification
program. As of 1969, 16 states required certification, 30 had voluntary
programs,and 4 had none. In those states with voluntary programs, avail-
able data showed that less than 50 percent of the operators were certified.
In addition, the certification programs which do exist vary widely from
state to state; no national organization, such as a Federal agency or the
Water Pollution Control Federation (WPCF), has been able to assist the
operator by developing a program in which his qualifications are accepted
nationwide.
Opportunity for advancement is mainly a function of plant practice. Cer-
tainly it would be desirable to have a clearly defined path whereby an em-
ployee entering the lower level of the staff "ladder" could, by training,
diligence, and application, advance to higher positions. Generally, in-
service operator training is practiced in the larger plants. Small plants
rely on programs sponsored by the State or by the local section of the
WPCF This can be a hardship for many operators since the courses
are normally given at central locations, thus requiring travel expenses
and time away from home.
Recognition can be received from two vantage points; in-plant and at-large.
In-plant recognition is a function of plant management. However the
societal image of the sewage plant worker, even in this day of "environ-
mental enlightenment, " is quite low. Various schemes have been proposed
to alleviate this situation including name change (water pollution control
plant), uniforms, certification, etc. However- these attempts have been
71
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aimed at satisfying the operator. A true change in status will only come
when society changes its attitudes toward those who provide basic, nec-
essary, but "dirty, " services.
RECOMMENDATIONS
Flint Sewage Treatment Plant
Preventive Maintenance. It is recommended that the Flint plant
consider assigning additional preventive maintenance tasks to the
operators to be performed during the period allotted to "as-required"
operations when such operations are not so required. Such pre-
ventive maintenance tasks as weekly or monthly lubrications pre-
sently assigned to the maintenance mechanic could be easily
accomplished by the operator if it is stipulated that the task should
be performed sometime during a given period and not at any specific
time. Provisions should be made for reporting the accomplishment
of the task to the supervisor.
Operator Turnover. The pay scale at the Flint plant was considered
good in relation to those found at other installations. The reasons
for the high turnover rate most likely include higher pay available
at local industry; poor image associated with sewage plant operation;
better chance for advancement at other plants. Whatever the rea-
son, it is imperative that the Flint plant be able to effectively func-
tion under these conditions. It is therefore recommended that
efforts be expended to develop a rapid and comprehensive in-service
training program using techniques that were discussed in previous
sections. Of course, existing efforts to improve both the salary
and status of the operator should continue. However, without
large-scale external input, it is unlikely that a single plant will be
able to change conditions significantly.
General
Operational/Maintenance Task Matrices. This technique was de-
vised in the course of this program to identify, group, and display
required operation and maintenance functions. It was found that
it serves as an excellent link between the equipment list or equip-
ment staging diagram and the OSD. It can be developed using the
Function-Capability-Equipment matrix as a basis and thus serve
as a direct link to the function oriented design process. It could
also be developed from reference tables which would be developed
as part of a design manual or guideline.
The Operational/Maintenance Task Matrix, as developed based on
recorded data at the Flint plant, should serve as an excellent guide
for job analysts responsible for determining personnel requirements
for new wastewater treatment systems. However, some doubt exists
72
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as to the validity of basing such a document on the observation at
only one plant and the validity of basing personnel requirements for
different capacity plants on data obtained from a 34 MGD plant.
It is recommended that the Operational/Maintenance Task Ma-
trices, contained in Appendix F, be validated for adequacy and
applicability to wastewater treatment unit processes or subsystems
other than those at the Flint plant, upon which the matrices are
based. The effective use of the matrices as a reference docu-
ment for plant supervisors and others interested in developing
personnel requirements is based on the data contained therein
being applicable to their specific wastewater treatment system
where the configuration and the size of the plant are quite different
than the Flint plant. Factors which could affect the matrix data
and for which validation at other facilities is required are:
(1) design capacity of plant, (2) geographical features, (3) local
and state regulations and standards, (4) labor union requirements,
(5) system configuration, (6) equipment configuration, (7) equip-
ment manufacturer's requirements, and (8) plant organizational
features.
For full validation, it is suggested that at least six wastewater
treatment facilities be visited to obtain data. The facilities should
be in different regions of the United States and their design capa-
cities should range from 1 MGD to 250 MGD.
Job Analysis. The industrial engineering techniques applied in the
job analyses demonstrated that it is possible to evaluate personnel
requirements for both new and existing plants on a rational, non-
empirical basis. These techniques included the OSD's, MAC, and
the Operational/Maintenance Task Matrices supplemented by the
use of Standard-Time tables. A question remains as to the degree
of effort required to arrive at a complete staffing list as compared
to the present empirical approach. If OSD's and MAC'S are being
prepared for development of Standard Operating Procedures, the
approach does not require a large amount of additional effort. It
is recommended that an additional study be performed on a plant
under design to test the efficiency of this approach.
Maintenance Standards. Although not used during the study, a prac-
tical approach is available for establishing standard times on nearly
all corrective as well as preventive maintenance work. This
approach is called Universal Maintenance Standards (UMS) and stays
within the bounds of sound industrial practice. It is economical on
both installation and administrative time and cost.
UMS has been used to develop data on thousands of specific jobs.
While some of these apply to all industry, others need tailoring
only to fit conditions in any specific industry. From these data,
jobs have been placed into Standard Work Groupings - one grouping
including the jobs within each craft which require a similar range
of time for completion.
73
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Figure 11 shows a number of electrical time standards that are
presently being used for controlling maintenance work. It also
illustrates how the time standards were developed.
Work Sampling. This is a statistical technique employed to deter-
mine the proportion of delays or other classifications of activity
present in the total work cycle. In maintenance, work sampling
is used to determine the effectiveness of the maintenance groups.
Secondly, it is often used to rationalize allowances in line with
management's agreements or policies on plant activities.
The purpose of this type of study is usually to measure,within rea-
sonable tolerances, the percentage of worker's time that is spent
in performing normal work, planning, travelling, delays of various
types, idle time, personal time, and other activities. During the
course of the study, the performance of the workers can be rated
and the working observations can be "leveled" from the worker's
performance. When the study is completed, the performance
efficiency and labor utilization efficiency can be determined,
based upon the methods presently used. These figures will then
provide a base point for determining the increase in present op-
erating effectiveness after improved work load planning, operating
methods,and management controls are installed.
Multiple Regression Analysis. This is a technique that can be used
in conjunction with Work Sampling to establish standards for work
tasks and manning requirements.
74
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SPREAD SHEET
CODE: 0795
CRAFT: Electrical
Ol
Gene
Task Area: General Installation
Group D
( 0.5 )
0.7 (^0.9)
0790-6 -- Medium size junction box,
4 tapped holes, 26 wires 112, screw
clamp connection, mount and
connect
0790-7 -- Medium size junction box,
4 tapped holes, 17 wires #12, screw
clamp connections, mount and
connect
0790-10 -- Wire*. 14-#12, 15',
measure, cut off, identify, and
install in 15' of conduit
Group E
0.9 )
1.2 ( <1.5)
0790-16 -- Conduit, 15'-1 1/4"
2-30° bends, 2 condulets, 2
nipples between junction boxes,
pr e pa r e conduit and install;
2 men
0790-2 -- Medium size junction box,
4 holes, 37 wires #12 crimped con-
0790-5 -- Medium size junction oox,
4 holes, 28 wires #12 crimped
0790-9 -- Wires. 22-#12. measure,
cut, identify, install in I57'"conduit
Group
1. 5 )
( <2 . 5 )
0790-15 -- Conduit, 35'-2", 2-
30° bends, 2 condulets, 2 nipple.,
between junction boxes, prepare
conduit and install; 2 men
0790-17 -- Conduit, 15'-1 1/2",
2-30° bends, i condulets, 2 nipples
between junction boxes, prepare
conduit and install; 2. men
OV9i
cut,
8 -- Wires, 37-112, mea.ure.
. luntify, install in 35' conduit
Sk,n end at wirr
Group Q
( 2.5 )
(<3. 5
0790-3 -- Medium size junction box, ^
4 holes, 85 wires 012 crimped con- "
nections, mount and connect
0790-11 -- Wires, 54-#l2, measure
cut, identify, install_in 80', then
50' conduit
0790-19 -- Medium size junction box,
plice, #12.wire.m..ke 54
Figure 11
Example of Time Standards for Electrical Maintenance
-------
SECTION VIII
QUALITY CONTROL IN WASTEWATER TREATMENT PLANTS
ELEMENTS OF QUALITY CONTROL
Quality control is defined as those functions which must be carried out in
order to ensure that the desired quality objectives for the product are
being met. Within this definition, there are several factors which must
be considered including a definition of quality objectives, means of mea-
suring quality, ability to control the manufacturing process, and com-
munications for feedback and proper dissemination of data.
In most industries, quality goals are identified by management after con-
sideration of consumer preferences, sensitivity of demand to quality,
effect on product cost of various levels of quality, etc. Once the para-
meters of quality have been defined, the process required to produce a
product capable of meeting these standards is devised. Included in the
process development are provisions to control or vary the process so
that positive control over product quality is possible during production.
Measurement techniques must be devised to accurately determine whether
quality standards are being met. Effective communications must be set
up to report the results of quality measurements back to those who are
responsible for meeting quality goals and those capable of controlling
the process. Thus, the various required elements of a quality assurance
program can be described as follows:
Quality Goals
Process Control
Measurement
Communication
and Feedback
Clear identification of quality requirements; iden-
tification of significant measurable parameters and
acceptable range of values for these parameters;
knowledge of "cost" or "profit" penalties associ-
ated with failure to meet goals.
Design such that quality can be controlled, if re-
quired; definition and assignment of responsibility
for quality in production area; clear definition of
the meaning of quality specifications; proper incen-
tive in production group; rejected product salvage
if possible.
Ability to accurately measure quality parameters;
adequate frequency, duration, and technique of
sampling; independent sampling and measuring
group; independent interpretation of results; in-
centive for measurement personnel to be accurate
and independent.
Data relay to those responsible in both process and
management; rapid turnaround of information; ad-
equate means of organizing and displaying data for
short and long term performance.
77
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From the above, it can be seen that quality control must be practiced in
all phases of production activity: design, equipment specifications, pur-
chasing, operations, maintenance, etc. One aspect of quality control that
is important in regard to waste treatment systems is quality assurance,
which is concerned with presenting to management summarized facts on
quality performance. Management in this sense can be considered both
in regard to the plant and the regulatory agency.
Work Study can be applied in two basic modes: (1) study of operator
routines for sampling and operating report preparation; (2) critical
examination of overall quality control programs. Operator routines
were discussed in a previous section. This section will deal with the
examination of current waste treatment practice as it relates to quality
control elements.
DISCUSSION
Quality Goals
Industrial quality goals are established after consideration of the market,
costs, technical feasibility, etc. In the sewage treatment field, the qual-
ity goals are set by the regulatory agency which also acts as the purchasing
agent for society. That is, the regulatory agency decides, after input
from a variety of groups such as voters, citizen groups, other agencies,
etc. , what quality product it will require. A difficulty arises in that
there are a number of ways in which the quality goals can be expressed;
concentration of pollutants in effluent; absolute amount of pollutants in
effluent (Ib/day); effect on receiving stream; and provision of certain
equipment specifications of "secondary treatment" or equivalent. The
last two approaches offer interesting analogies in industry Specifying
quality by process equipment is analogous to an automobile manufacturer
stating that his quality requirements for steel are satisfied as long as he
knows that it comes from an open hearth furnace. Acceptance of quality
based upon the effect on receiving streams is theoretically sound, but
if it is the sole quality control requirement, it is unwieldy. This would
be analogous to buying tires strictly on the basis of the tread wear
achieved rather than on readily measuredparameters that are related to
tread wear. There is too long a time lag between the purchase and the
manifestation of acceptable or unsatisfactory quality.
Another problem with quality standards as they are usually defined for
sewage treatment is the failure to accurately reflect the normal variations
in treatment performance. The quality of effluent from biological treat-
ment plants is never constant. All significant parameters vary consi-
derably due to several reasons, some of which are stated on the following
page.
78
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Constantly varying raw BOD, suspended solids, etc.
Constantly varying hydraulic loads
Cyclical nature of biological reactions
Minor equipment and operator malfunctions
Varying ambient and waste contribution which
can inhibit or alter biological kinetics or loading
With all of these factors, it is not surprising that there is considerable
variation in effluent quality, even in well-run plants. Studies (Refs. 10,
11.) have shown that the coefficient of variation of BOD and suspended
solids through activated sludge plants actually increases. While the ex-
istence of these uncontrolled variations is known, the quality goals as
set by most regulatory agencies do not reflect this reality. Thus, a
designer or manager can be faced with a "not to exceed" standard which
means that he must operate the plant at an average efficiency much higher
than the limit. Quality goals which are stated in terms of average quality
do not reflect the variability in effluent; short term variations can exert
very significant effects on receiving waters. What would be desirable
is a clearer means of defining quality goals; an approach which perhaps
not only specifies the allowable average content of pollutant but also a
maximum and an indication of allowable variation stated in a statistical
framework; for example, a frequency distribution curve based upon a
given time span. The question remains whether the state-of-the-art of
biological waste treatment is advanced to the degree where plants can
be designed on this basis. However, if more stringent performance
specifications are promulgated, there may be equipment or process
changes that can be incorporated to satisfy them. For example, raw
waste equalization ponds or tanks have long been used in industrial
waste treatment to dampen flow rates and waste variability. Because
of a lack of incentive, they have not been widely accepted in the munici-
pal field. Raw waste bypass is another example; if it were unacceptable
to bypass raw sewage due to process overload or equipment malfunction,
means would be found (redundant elements, holding ponds, etc. ) to meet
this requirement. If it is not required, it will not be done.
Process Control
Conventional biological treatment plants are simple in terms of basic
processes: contact waste with a suitable concentration of viable bacteria
for an adequate time in the presence of dissolved oxygen and remove the
bacteria from the treated waste by settling before discharge. In terms
of operation there are relatively few means of changing or controlling
the process, the two major parameters being the food-to-microorganism
(F/M) ratio and the dissolved oxygen content. For conventional activated
sludge plants, the dissolved oxygen (D. O. ) content should be above a cer-
tain minimum, usually 1 mg/£. Benefits accrued from high D. O. levels
79
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are normally not worth the added power cost. An exception to this is
the "UNOX" system which utilizes pure oxygen to achieve very high
D. O. levels. Thus, the main operating control for removing organic
material from sewage is the food-to-microorganism ratio. This ratio
is a function of incoming BOD (variable), detention time (varies inversely
with inflow rate),and microbial population (mainly dependent upon the
recycle rate of settled sludge from secondary clarifiers as well as the
solids concentration of settled sludge). The primary controlling technique
for ensuring that the process is functioning as designed is the amount of
sludge recycled. Note that in order for the process to function according
to theory, the F/M ratio must be kept within a relatively narrow range
which is characteristic of that given plant. Thus, in the face of varying
inflow rates and BOD concentrations, control of the amount of recycled
sludge is the only tool to ensure the proper food-to-microorganism ratio.
Most plants control recycle rate on the basis of inflow volume (see
Figure 7 for Flint);others attempt to control the F/M ratio by measuring
the mixed liquor solids content and adjusting the recycle rate as needed.
There are difficulties with both methods: (1) the BOD (food) of the in-
coming waste is assumed constant, which is not true; (2) either mixed
liquor suspended solids or volatile suspended solids are used as an
approximation of reliable microorganisms, both of which can be very
misleading since the total or volatile suspended solids determination
does not differentiate between microbial and inert solids. Thus, the
only major method of controlling the waste treatment process, the F/M
ratio, is hampered by measurement difficulties. The BOD test takes
too long to be of on-line use; and the suspended solids analysis is in-
direct.
Measurement
Quality goals are only meaningful if the goals can be expressed by para-
meters that can be easily and accurately measured. Essentially all
effluent quality goals that are applied in the wastewater field are mainly
concerned with five-day BOD and suspended solids. It is well known that
the five-day BOD test suffers many weaknesses, including: poor repro-
ducibility; questionable accuracy; long analysis- time; subject to inter-
ferences; may not represent true conditions in either the treatment plant
or the receiving stream. Because it is the only bioassay type technique
that is relatively easy to perform and because of historical precedent, it
remains the primary parameter for quality measurement for treated
sewage. The effectiveness of the BOD test for on-line quality control
is essentially nil. Often, by the time a substandard BOD is discovered
(5-6 days), the problem has passed. If remedial actions are taken, it
would be another 5-6 days until the results of those actions were known.
Thus, the current quality measurement technique of greatest significance,
BOD, is of no value in a quality control program since it provides little
or no feedback data for timely process control. In a quality control minded
industry, this would be an intolerable situation.
80
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There are several reasons why. a more effective quality analysis has
not been developed. Perhaps the most important is the lack of incentive
for development, purchase, and use. As long as strict quality control
is not required, sewage treatment plants will be reluctant to purchase
additional analytical hardware or to hire skilled personnel. At the same
time, instrument manufacturers are reluctant to invest large amounts
of money to develop an instrument or technique for which there is no
market. For any product, .the quality control exerted by the manufacturer
will only be that required by the customer since quality control costs
money.
i
Communications and Feedback
In order for a quality control program to function properly, relevant
data must be rapidly relayed to those responsible for quality decisions
as well as those who are able to control the process. In the waste
treatment field, these parties correspond to the regulatory agency and
the plant management. Communication of operating data can be effective
depending upon the management practices. At Flint, several forms were
prepared and circulated daily containing the results of a large number of
analyses (On various parameters of interest including influent, effluent,
and mixed liquor sludge characteristics. While these data are very
helpful in relation to the economics and the operation of certain equip-
ment, such as the vacuum filter, it does not enable plant management
to exert direct and complete control over the quality of the effluent, due to
the reasons previously discussed.
Communication of data to the regulatory agency varies considerably from
state to state. One study in 1969 (Ref. 12) indicated that only 44 states
require submission of operating reports. Of these states almost 40 per-
cent of the plants did not submit reports during 1969. Data requirements
also vary widely. Michigan requires extensive operating data from Flint,
some of which are only indirectly related to the quality of the effluent such
as the pounds of chemicals applied to the vacuum sludge filters. ,A signif-
icant amount of time is spent by Flint plant management in fulfilling state
data requirements. There are large differences in the use of the data,
once reported. Michigan evidently reviews the data from Flint carefully
and questions results which are out of the norm. Some states merely
file the data for future use, if required. In few cases are the analyses
as reported checked by the regulatory agency or an independent laboratory
for accuracy. Normally, there is little assurance that the plant analytical
techniques are correct.
The reasons for the wide variation in approach by regulatory agencies
are subject to conjecture. Some may be: lack of funds for staffing; lack
of qualified manpower; political considerations; and differences in philos-
ophy on the efficacy of close regulation.
81
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CONCLUSIONS AND RECOMMENDATIONS
Based upon comparison with industrial practice, it is concluded that the
quality control programs associated with waste treatment plants are gen-
erally poor or nonexistent. The responsibility for this situation does not
lie with the plants alone but also with the state-of-the-art and the various
approaches used by regulatory agencies. If a consistently high quality
effluent is deemed desirable, then new knowledge, approaches, and tech-
niques must be developed including:
Normal Variations in Effluent Quality. Consideration should be
given to projects to identify the normal variation in effluent quality
that can be expected in biological treatment plants, exclusive of
equipment or operator failures.
Expression of Quality Goals. Consideration should be given to de-
velopment of quality goals that more adequately reflect the variabil-
ity inherent in biological treatment systems.
Process Modifications. Cost/benefit studies should be initiated on
the feasibility of incorporating additional process steps to minimize
variations in sewage flow and strength as well as means to prevent
release of substandard effluent.
Process Control. True quality control will not be possible until
techniques are developed to allow on-line process control and
accurate monitoring of effluent quality. In order for this to happen,
incentives for development are required at the federal level. It
is recommended that a state-of-the-art study of on-line control and
quality monitoring be supported. Included should be consideration
of alternate incentive generating actions such as more stringent op-
eration requirements, financial support of equipment development,
etc. Until this is accomplished, it is doubtful that biological waste
treatment systems will be able to produce consistently acceptable
effluent.
Analytical Procedures. Dissatisfaction with the BOD test is not new.
Unless strong pressure is exerted to replace it with a more mean-
ingful and acceptable analysis, changes will be very slow. A state-
of-the-art study of bioassay or equivalent analyses is recommended
to identify promising approaches and to investigate alternative means
of promoting the development and use of better techniques.
Reports and Enforcement. There is a wide variation in reporting
requirements between the state regulatory agencies. The advis-
ability and practicability of uniform reporting requirements for
both state and federal use should be investigated.
82
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SECTION IX
APPLICATION OF RELIABILITY AND MAINTAINABILITY
EVALUATION TECHNIQUES
INTRODUCTION
Reliability and maintainability .(JR&M) evaluation techniques (see
Section III for definitions) were originally formulated to solve serious
military problems caused by equipment failures during wartime
missions. In most cases, such missions were accomplished during
limited and predictable time periods. Therefore, the reliability
effort to solve equipment failure problems was directed towards
making complex equipment more reliable by increasing the probability
that it would not fail during a specified "mission time" period. Com-
plementary maintainability techniques were directed toward reducing
to a minimum the average time needed to repair an equipment item if
and when it did fail. The combination of the R&M characteristics
of an equipment item determined the fraction of operating time the
equipment was available, or what is referred to as equipment avail-
ability.
The "mission time" of a wastewater treatment plant is a continuum
because the plant is in operation 24 hours a day, 7 days a week,
365 days a year. The reliability effort for a wastewater treatment
plant should be directed toward preventing the occurrence of an equip-
ment failure or combination of equipment failures which would result
in a failure of the plant as a whole. To attain this objective, equip-
ment reliability and maintainability characteristics, standby equipment
requirements, and preventive and corrective maintenance practices
must be carefully integrated into a well-planned man-machine system.
A primary objective of this program was to attempt to establish a cor-
relation between equipment R&M characteristics and the capability
of a wastewater treatment plant to achieve its desired goals. Plant
goals are: (1) to continuously produce an effluent of acceptable quality;
and (2) to operate in an efficient and economic manner. The approach
used was to conduct a reliability and maintainability evaluation of a
"typical" conventional plant applying adaptations of techniques which
have been used successfully to analyze military systems. The Sewage
Treatment Plant in Flint, Michigan, was selected for this purpose. The
evaluation included development of a mathematical reliability model
using data obtained at that plant. This model was the basis for evalua-
ting the effects of equipment reliability, maintainability, and availability
on the plant's operation.
Reliability and maintainability techniques used during the analysis and
which can be applied in plant design and maintenance planning are
described in the succeeding paragraphs. The purpose and sequence in
83
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which each technique is applied in the evaluation process are
summarized in Figure 12.
The first part of the process is to establish a basis for the evaluation
by describing:
Functions which must be performed by the system. Functional
Staging Diagrams in Appendix A are used for this purpose.
Equipment which is needed to perform each function. System/
Equipment Staging Diagrams in Appendix D are used.
The frequency and time duration that each part of the system
performs its function without interruption must be deter-
mined. Observed or derived estimates of equipment
operating requirements in the system are used. Although
a wastewater treatment plant must perform its function
continuously, each equipment is not necessarily in con-
tinuous operation. Therefore, certain interruptions in
equipment operation do not interrupt the plant's treatment
function; certain interruptions in equipment operation, or
combinations thereof, will interrupt the plant's function
while others may not; and other interruptions in equip-
ment operation will not interrupt the plant's function
unless they continue too long.
The second part of the evaluation process is to compare system R&M
characteristics with system .R&M requirements and determine
courses of action necessary to reconcile their differences. This is
accomplished by analyzing:
The system's capability to function properly without
interruption. Reliability block diagrams, failure data,
and reliability and maintainability calculations are used
to determine the frequency and cumulative effect of equip-
ment failures on the plant's treatment function.
Reasons for equipment failures and alternative actions which
may be taken to increase the length of time between failures
or to compensate in some manner for them. Failure Modes
and Effects Analysis is performed.
Determine the most attractive alternative actions and the
effects of selected alternatives in improving the reliability
and maintainability of the system. Reliability block diagrams
and calculations are used.
Technique descriptions are organized under three topics: modelling,
evaluation, and application; the elements of each topic are shown in
Figure 13.
84
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SYSTEM DESCRIPTION
Define the
required functions
in the system
Functional
Staging
>
Identify
equipment
which performs
each required
function
Equipment
Staging
Determine
system relia-
bility or
availability
requirements
Plant
Operating
Requirements
SYSTEM ANALYSIS
co
en
Reliability
Block Diagrams
Failure and
Maintenance
Time Data
R&M Calculations
Assess system
reliability,
maintainability
(& availability)
characteristics
Examine & com-
pare reliability,
maintainability
(& availability)
requirements
& characteristics
^-
Describe alter-
natives for
correcting
differences in
requirements &
characteristics
Reliability
Block Diagrams
« R&M Calculations
Failure Modes
and Effects
Analysis
Evaluate,
develop and
describe best
alternatives;
test for results
Monitor
corrective
action
taken
Failure Modes
and Effects «
Analysis
Reliability
Block
Diagrams
R&M Calculations
Reliability
Block Diagrams
R&M Calculations
Figure 12
Reliability and Maintainability Evaluation
Flow Process Elements
-------
co
OJ
A. Modelling
Reliability Block Diagrams
Data Analysis
Reliability & Maintainability
Calculations
Reliability & Maintainability
Relationships
B. Evaluation
Reliability, Maintainability,
Availability Assessments
Failure Modes and Effects
Analysis
C. Application
Corrective Action
Design Optimization
Maintenance Planning
Figure 13
Elements' of the Reliability and Maintainability Evaluation Techniques
-------
MODELLING TECHNIQUES
Reliability models usually consist of two elements -- block diagrams
and calculations. Typically, they are used to describe the probability
that a system will perform its function for a specified time without
failing and thereby accomplish its objective. Models are an extension
of function and system/equipment analysis into the operating time
domain. They are used as the basis for determining equipment and
operational relationships and quantities of equipment needed to assure
sufficient system flexibility in predictable equipment failure situations.
Since calculations in modelling are made using records of equipment
failures and malfunctions during operations or tests, models can be
used for planning equipment maintenance to prevent and correct equip-
ment failures and malfunctions.
Reliability Block Diagrams
Reliability block diagrams have been developed for the Flint plant to
demonstrate this technique and show the dependency relationship of
equipment, elements, and subsystems in carrying out the wastewater
treatment process. Typically, these redundant or nonredundant re-
lationships are diagrammed as being in "series, " "parallel, " or
"series-parallel" combinations.
In a series combination, each equipment must successfully perform
its function for the entire combination to perform successfully. A
parallel combination contains "standby" equipment which takes over
performance of a function for the equipment which fails.
Example: Series Combination
Raw Sewage
Pump
Raw Sewage
Pump Motor
The raw sewage pump and its motor are dependent upon the
performance of one another in order for the combined functions
they perform to be a success.
Example: Parallel Combination
L
Air Blower
1
Air Blower
2
Air Blower
3
87
-------
Blowers 1, 2, and 3 are installed so that any one of the three
can perform the air delivery function. When blower 1 is _
operating, either blower 2 or 3 is available to supply air in
place of number 1 should it fail.
Example: Series-Parallel Combination
Plant Influent
Flow Meter
& Recorder
Instrument
Air Com-
pressor 1
Instrument
pressor 2
The air-actuated flow meter and recorder are in series with
two air compressors, one of which is needed to provide air to
the meter and recorder; the other is installed in parallel with
the first in case it fails. The flow meter and recorder and
either one or the other instrument air compressors are in
series because they are needed to indicate and record plant
influent flow information.
Reliability block diagrams for the Flint plant were developed using
these basic diagramming procedures and information contained in the
functional and equipment staging diagrams for the plant. Diagrams of
the plant's subsystems and elements are given in a later subsection on
R&M calculations. (Formulas for the R&M calculations are included
in Appendix H. )
Data Analysis
In order to perform reliability and maintainability calculations, certain
equipment performance data are required. The following paragraphs
describe how raw data are processed into a form which permits them to
be used in such calculations.
Raw data were available at the Flint plant in the form of descrip-
tions of "Equipment Malfunctions" which are reported chronologically
by operating personnel; a sample of the form used for these reports is
shown on sheet 1 in AppendixG. Data for a one-year period, July 22,
1970 to July 21, 1971, were selected for analysis. Since the operators
must make such reports for corrective maintenance to be performed,
there is a relatively high degree of confidence that all equipment mal-
functions discovered by the operators during their inspection and
operation of equipment were entered on the forms during the data
period.
88
-------
During,the data reporting period, 711 equipment "problems" were
reported. Each problem description was reviewed to determine
whether it represented an equipment "failure" or an equipment
"malfunction." The following definitions were used in making these
determinations:
Failure
An equipment problem which prohibits the equipment from
being kept in operation or prohibits the equipment from
performing its required function. When an equipment
failure occurs, the satisfactory accomplishment of the
equipment's function is lost to the plant process until
corrective maintenance is performed.
Malfunction
An equipment problem which does not prohibit the equip-
ment from being kept in operation and does not prohibit
the equipment from performing its design function
acceptably. However, a malfunction may result in in-
convenience or inefficient operation.
During the review of each problem described in the data, each
"failure" and "malfunction" was determined, and the specific equip-
ment involved was identified by its System /Equipment Staging code
number. After the review was completed the quantities of "failures"
and "malfunctions" were totalled for each equipment code number. A
sample Work Sheet is shown on sheet 2 in Appendix G. Summaries of
these data were recorded in columns (3) and (4) on data sheets,
samples of which are in Appendix H. The following determinations
were made from the problem descriptions for the one-year period:
Equipment failures - 302
Equipment malfunctions - 202
Problems not affecting - 207
the plant process (e.g.,
light bulbs burned out)
Total: TTT
Calculations were performed using the previously described data.
Techniques used in making the calculations are described below.
The Sample results of calculations performed are summarized on
sheets contained in Appendix H.
Equipment operating hour records are maintained on relatively few
items of equipment at the plant. To provide a basis for subsequent
89
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calculations of MTBF (mean time between failures), estimates of the
number of hours each equipment item is typically operated per day
were obtained from qualified plant operator personnel. Total opera-
ting hours per year for each equipment code number was calculated
using the following formula:
Total equipment operating hours (per year) =
Qty. of equipment operated each day (equipment items)
x estimated no. of operating hrs per day (hrs/day) x
365 (days/year) = hrs/year
Example: (Pumping and screening instrument air compressors)
Total equipment operating hours (per year) = 2 (equipment items)
x 12 (hr/day) x
365 (days/year) = 2 x 12 x 365 = 8760 hr/yr
Estimates of MTBF (mean time between failures) and MTBM (mean
time between malfunctions) were then calculated for each equipment
using the following formulas:
MTBF = Total equipment operating hours (per year)
No. of failures (per year)
Operating hours per failure
MTBM = Total equipment operating hours (per year)
No. of malfunctions (per year)
= Operating hours per malfunction
Example: (Pumping and screening instrument air compressors)
MTBF = Total equipment operating hours (per year )
No. of failures (per year)
= 8760hr ("between failures")
MTBM = Total equipment operating hours (per year)
No. of malfunctions (per year)
8760
* = 4380 hr ( between malfunctions")
Some equipment is only operated part of the time. To convert values
of MTBF and MTBM of "part-time" equipment to system operating hours,
the equipment's MTBF and MTBM are divided by the percentage of time
the equipment operated in the system. The percentage value in this
calculation is referred to as "duty cycle" In the evaluation, a typical
90
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equipment operating day was used as a basis for calculating duty
cycles. The formula used is:
Duty cycle = No* of hours equipment operates/day
No. of hours system operates/day
Example; Single Equipment
Note:
** ^<± nr ' »
1 hr 1 hr 1 hr 1 hi
t
',
/
j
'i
*,
Denotes equipment
operating period.
Bar Screen Rake
D t cle = No. of hr bar screen operates/day
^ ^ No. of hr system operates/day
4 hr
24 hr
MTBF (adjusted to system hours)
= 0. 17
MTBF for continuous equipment operation
Duty cycle
365 hr
0. 17
= 2147.1 hr
There were no malfunctions recorded for the bar screen rake during
the reporting period; however, calculations for converting MTBM from
"equipment time" to "system time" are performed in the manner as
above for MTBF.
Example : Multiple Equipment
Foam Spray Pump #1
Foam Spray Pump #2
Foam Spray Pump #3
8 hr
24 hr
8 hr
8 hr
No. of hr foam spray pumps operate /day
Duty cycle - of hr sstem oerates da
No> of
8 hrs(F.
system operates /day
. l&2)+8 hrs(F. S. P. 2&3)+8 hrs(F. S. P. 1&3)
24 hrs
24 hr
= 1.00
91
-------
MTBF (adjusted to system hours)
= 876C
MTBM (adjusted to system hours)
MTBM for continuous equipment operation
Duty cycle
Certain reliability and maintainability calculations are facilitated using
equipment failure rates in place of MTBF. Failure rate (X) is the rate
at which failures occur during an interval of operating time and is the
reciprocal of MTBF; it is normally expressed in failures per equip-
ment (or system) operating hour.
Example :
MTBF
X Foam spray system pumps =
_
= 0. 114 x 10 failures per system
operating hour
RELIABILITY AND MAINTAINABILITY CALCULATIONS
With equipment series and parallel relationships displayed in reliability
block diagrams and process data available, reliability and maintainability
calculations can be made. The results of these calculations provide
engineering and maintenance planning information and can be used to
demonstrate the degree to which a new plant design relates to the general
reliability requirements contained in the "Federal Guidelines. " The
same basic calculations can be used to make design and management
decisions on practically all matters affected by reliability and main-
tainability.
Reliability Calculations
The fundamental calculation involves what is referred to as the "product
law of reliabilities" which is that the reliability of a system (Rs) is
equal to the product of the reliabilities of its subsystems in series,
i.e.,
Rs = ni . R2 . R3 Rn
92
-------
(A method for converting parallel subsystems to an
equivalent series subsystem is given later. )
The result of the calculation is a numerical expression of the probability
that the system will perform its intended function for a specified length
of time without failing. Note that the product law implicitly states that
the success of the system is possible only when all subsystems are
functioning properly. Thus, if one subsystem fails, the entire system
fails.
A formula for calculating subsystem reliability (R1t R9, etc. ) is:
*- £
B:= e-Xt
where:
X = subsystem failure rate
t = system operating time
In using this formula, it is assumed that component failures occur at
random intervals and that the expected number of failures would be
the same for equally long periods of time during the useful life of the
component. In other words, the component's failure rate is assumed
to be constant over equally long periods of time. In lieu of evidence
that a component's failure rate is not constant, this formula is
generally used because of its relative simplicity. In the case of the
Flint plant, a graph of cumulative equipment failures vs. cumulative
plant operating hours plotted as almost a straight line with the slope
indicating the failure rate for the composite plant system to be a
constant (Refer to Figure 14).
Example: Subsystem Reliability Calculation
X = 0. 114 x 10 failures/system operating hour
t = 720 system operating hours (one calendar month)
R = e-(0. 114x10-3x720) = ^^
The results of this calculation could be expressed, "There is a 92
percent probability that the subsystem will perform its function for
720 operating hours without failing. "
Example: System Reliability Calculations for Subsystems in
Series:
Block Diagram
93
-------
280
CD
CD
SH
d
I - 1
I I
Oi
0)
a
&
rH
d
cr
H
cd
ii
PH
QJ
d
U
1000 5000 7000
Cumulative Plant Operating Hours
9000
Figure 14
Failures vs. Operating Hours
94
-------
Subsystem reliabilities are:
R, = 0.921
R2 = 0.683
R3 = 0.849
Calculations
System reliability, R = 0.921 x 0.683 x 0.849 = 0.534
s
For Subsystems in Parallel:
In making this calculation, parallel or redundant subsystems
can be reduced to an equivalent "composite subsystem" so
that the system equation for expressing the "product law of
reliabilities" can be used. The following is an example of
the manner in which this can be done:
Block Diagram
Subsystem reliabilities are:
R1A = 0.921
R
= 0.921
Calculations
In this case, the equation used for calculating the reliability
value of the equivalent "composite subsystem" is:
RS = R1A+R1B-R1AR1B
R0 = 0.921 + 0.921 - (0.921MO. 921)
Rg = 0.994
95
-------
It should be noted that, in this case, a single subsystem has a
reliability of 0. 921, whereas two in parallel have a higher
reliability of 0. 994.
Approximation formulas have been derived to facilitate calculating re-
liability values for parallel subsystems. These formulas are in Appen-
dix I. Reliability models at the system and subsystem levels for the
Flint plant are shown in Figures 15 and 16. Element level models are
not included. A one-month operating period (720 hours) was selected
for making reliability calculations and analyses of the distribution of
reliability values of the different items of equipment.
System reliability values derived and shown in Figure 15 indicate that
there is a very low probability that the plant could continuously
operate for one month without a failure of at least one of its com-
ponents. By far the highest probability of failure would be in the
sludge treatment and disposal subsystem. The order of decreasing
probability of success is: chlorination, primary treatment, secondary
treatment, and sludge treatment for this particular plant. The order
would probably hold true for any increment of operating time. The
following tabulation contains the reliability values for each subsystem for
several selected plant operating periods.
Reliability Values for Selected Plant Operating
Times
64 hr
720 hr 120 hr (5 pm Fri. to 24 hr 8 hr
Subsystem (30 days) (5 days) 9 am Mon. ) (1 day) (1 shift)
Primary 0.057 0.620 0.775 0.908 0.969
Treatment
°' °31 °- 56° °- 734 °- 89° °-962
Sludge
Treatment 0.002 0.354 0.575 0.813 0.933
& Disposal
Chlorination 0.940 0.990 0.995 0.998 0.999
Plant 0.00000331 0.122 0.326 0.656 0.860
This tabulation illustrates the higher values of reliability during the
shorter plant operating periods.
It is important to note that the reliability model assumes that overall
system failure will result if any subsystem fails and that subsystems
will fail if any element fails. This concept is useful in predicting the
probability of equipment failure but it does not accurately represent an
96
-------
R
r
12000
0. 031
CD
R
iiooo
R12100=°-156
R12200=°-241
R13000=-°°2
R14000=°-94°
Primary
Treatment
Subsystem
11000
I
1
1
1
Activated Sludge
Secondary Treat-
ment Subsystem
12100
Trickling Filter
Secondary Treat-
ment Subsystem
12200
1
1
1
i
Sludge Treatment
and Disposal
Subsystem
13000
Effluent Treat-
ment Subsystem
(Chlorination)
14000
CALCULATIONS:
CALCULATIONS
-X
The values of R were obtained using the formula R = e
of operation) and t = 720 hours (one calendar month).
where: X = failure rate (failures per 1000 hr
RS R11000
R
12000
R
13000
R
14000
= (0. 057)(0. 031)(0. 002)(0. 940)
= 3.31 x 10~6
Figure 15
System Level Reliability Model Block Diagram
-------
SUBSYSTEMS
R11300=0-"6
11000
Primary-
Treatment
12100
Activated
Sludge
Treatment
12200
Trickling
Filter
Treatment
13000
Sludge
Treatment
and Disposal
14000
Effluent
Treatment
B
I
P
B
Pumping &
Screening
11100
^12110=°-742
Primary
Effluent
Transfer
12110
112210=°-902
Primary
pfflnpnt
Transfer
12210
= 0 QQ7
13100 '
Waste
Sludge
Transfer
13100
,14100-0.966
Chlorine
Storage
14100
I
I
F
B
Influent
Collection
11200
112120=0.31E
Aeration &
Mixing
12120
112220=1-°°C
Trickling
Filter
Operation
12220
t13200=°-003
Sludge
Stabilization
13200
tl4200=0.973
Chlorine
Feed
14200
) I
R
B
R
Preliminary
Treatment
11300
112130 = 0. 661
Secondary
Settling
12130
12230=°-267
Secondary
Settling
12230
13300=0'653
Sludge
Disposal
13300
14300=1-°°°
Chlorine
Contact
14300
Primary
Clarifiers
11400
CALCULATIONS:
R
R
11000
12100
R
12200
R
R
13000
14000
R11100 '
(0.354)(0.
R12110 '
(0.742)(0,
R12210
(0.902)(1.
R13100 '
(0.997)(0
R14100
(0. 966)(0
R11200 ' R11300 '
. 849)(0.996)(0. 191)
R12120 ' R12130
,319)(0.661) 0.
R
R
11400
0. 057
156
12220 "12230
,000)(0.267) 0.241
R13200 ' R13300
.003)(0.653) 0.002
R14200 ' R14300
.934)(1.000) 0.940
Figure 16
Reliability Model Subsystem Level Block Diagram
98
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actual equipment /effluent relationship in a wastewater treatment plant.
In biological treatment plants, there are "hidden redundancies" which
cannot be easily identified or quantified. Many elements in the treat-
ment plant can fail and remain out of order for a short time without
adversely affecting effluent quality. For example, if the return sludge
flow meters were inoperative, the operators could probably operate
the plant for a few days on the basis of their experience and additional
laboratory tests. This would be effective during that time, but not
efficient. Another example would be failure of the primary scum re-
moval equipment; a "certain amount" of floating solids could be
accepted by the secondary system for a short time span. The amount
of solids and the time duration allowable before adverse effects on the
effluent are manifested are unknown. Thus, it can be concluded that the
reliability model, as developed and demonstrated in this program, is
only useful in predicting equipment failures. The state-of-the-art of
biological treatment is not yet sufficiently advanced as to provide in-
formation for use in the models on the magnitude of effects on effluent
quality and time dependency of an equipment failure. Because of the
inherent variability in effluent quality due to other sources, as pre-
viously discussed, it is impossible to isolate the effects on effluent
quality of most equipment failures except in extreme cases such as
complete chlorinator breakdown or blower failure.
Maintainability Calculations
Maintainability calculations for MTTR are usually based upon averages
of equipment maintenance repair times (Re) derived from maintenance
records, estimates by experienced personnel, timed observations,
data tabulated for typical subtasks, or a combination of these sources.
Perhaps the most practical derivation of Re for waste treatment plant
equipment is by the use of a combination of information from records
and qualified estimates.
In a plant where records are kept of equipment failures, malfunctions
and corrective maintenance man-hours, Re, can be calculated using
the following formula:
P _ Cumulative corrective maintenance man-hours during a given period
e no. of failures + average no. of men who normally
no. of malfunctions perform maintenance on the
equipment
Example; Vacuum Filter-Filtrate Piping
Failure /malfunction mode Piping blockage
8+5+10+7+4+6+9+11+12+8+17+12+5+4+7+3+9+4+8
e ~ 19 x 2
149
= 3. 92 hr
99
-------
Note that this number represents the mean time that is required
to repair the equipment using a normal crew of two workmen.
Another practical method for determining Rg is to utilize experienced
personnel to estimate the time required to perform basic repair sub-
tasks which are: localization, disassembly, correction, reassembly
and adjustment, and checkout. The following procedure would be used;
Referring to failure and malfunction records and considering
the most frequent failure mode, estimate the average
localization time needed to determine that a problem exists
and its location in the equipment.
Referring to appropriate drawings, estimate the average
disassembly time needed to gain access to the equipment
problem area.
Considering what must be done to eliminate the problem,
estimate the correction time needed (including time to
obtain tools, remove and transport an assembly to the
shop, etc. ).
Referring to the drawings, estimate the time required to
reassemble the equipment, including readjustments, as
required.
Referring to performance ratings for the equipment,
estimate checkout time to assure that the equipment problem
has been corrected.
This procedure enables the evaluation to include a breakdown of the
total maintenance operation into smaller, more easily estimated
segments.
To calculate the MTTR (mean time to repair) for the next highest
level in the plant system (i. e. element level), the following formula
can be used:
MTTR = XlRel^2Re2+ ' '^en
where: X^ = failure rate of equipment no. 1 in the element
Rel = repair time of equipment no. 1 in the element
Example: Pumping and Screening Element
(Refer to Sheet 1, Appendix H, columns 1, 14, and 16)
100
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MTTR = (-466xl°" )(5)+(.0004xlO"d)(13)+(.228xlO~3)(l)+(.228xlO"3)(2)
(.466x10-3) +(.0004x10-3) +(.228xlQ-3) +(. 228xlO~3)
+ (. 007xlO~3)(5. 5)+(. Il4xl0"3)(3)
+ (.007x10-3) +(.114x10-3)
= (10"3) (. 466x5)+(. 0004xl3)+(. 228xl)+(. 288x2)+(. 007x5. 5)+(. 114x3)
(10"3)(. 466+. 0004+. 228+. 228+. 007+. 114)
2. 33+. 005+. 228+. 456+. 038+. 342
1.043
3. 399
= 3.25hr
RELIABILITY AND MAINTAINABILITY RELATIONSHIPS
Availability
Probably the most commonly referred to reliability and maintainability
relationship is availability (A). As defined earlier, availability is the
ratio of reliability to reliability combined with maintainability. The
diagram below illustrates the calculation of this ratio.
MTBF
MTTR
MTBF + MTTR
TOTAL OPERATING
TIME
Example
Sewage pumps and motors availability is:
MTBF _ 8760
A =
MTBF + MTTR
8760 + 13
- 0.9986
This value is referred to as "inherent availability" because it is
based upon the characteristics of the equipment and excludes
"administrative" repair delays such as time awaiting delivery
of a repair part. Values of availability for selected plant
elements were obtained from Sheet 1 in Appendix H.
101
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Maintenance Manpower Predictions
Probably the most valuable application of the reliability and maintain-
ability relationship for wastewater treatment plants is the use of
failure rate (X), Re, and MTTR for predicting corrective maintenance
man-hour requirements. The calculations are very similar to that
previously described for estimating MTTR.
To estimate corrective maintenance man-hours for an equipment
item (M ), the following formula can be used:
Mc = <*e + Mae)
where:
X = failure rate of equipment item (Mn)
e c
M = the reciprocal of MTBM (Mean Time Between Malfunctions)
cLG
P = no. of repairmen normally involved in a corrective
maintenance task on the equipment
The calculated value MC is the average number of hours spent
in corrective maintenance per 1000 hours of system operation.
The formula for predicting the number of hours to be spent on
corrective maintenance during one 40-hour week (M )
would be:
Mcw = TWO x Mc
Example: Sewage Pumps and Motors
From the Data Summary Sheet (columns 7, 11, and 16) in
Appendix H:
MTBM = 2920
Mae = 29120 X IWf) = °'342 x 10~3
X = 0. 114 x 10"3
e
Mc - (0. 114 + 0. 342) (10~3) failures and malfunctions per
1000 system operating hours (13 avg. hr per repair)- (1 man)
= ~lOOQ = 5. 934 Corrective maintenance man-hours
per 1000 system operating hours
102
-------
40
= -. QQQ x 5.934 = 0.237 Corrective maintenance
man-hours per 40 hr work week
The amount of corrective maintenance which can be expected during, say,
a 40-hour work week would be added to an estimate of additional main-
tenance (i.e., preventive maintenance recommended by the equipment
manufacturer) to arrive at an estimate of total maintenance required
during the 40-hour week. No doubt the calculated estimate for
corrective maintenance would influence planning for additional pre-
ventive maintenance to prevent, to the greatest reasonable degree,
failures and malfunctions from occurring.
To estimate preventive maintenance man-hours for an equipment
item, the following formula can be used:
Mp = (fe)(Pe)
where: f = frequency of preventive maintenance recommended by
the equipment manufacturer minus maintenance which
is recognizable as duplicating corrective maintenance
previously considered.
P = average preventive maintenance man-hours determined
by an analysis of recommended tasks similar to that
performed in estimating corrective maintenance man-
hours, (i.e., localization time estimate, disassembly
time estimate, etc. )
Example: Sewage Pumps and Motors
Manufacturer's recommended preventive maintenance which is
in addition to identified corrective maintenance actions
2 actions
3 months
2 actions 1 month _ 2 actions _ Q lfifi actions
e ~ 3 months X 4 weeks T2~ week ' week
Assuming an average value (which would be obtained from an
analysis of the times required to perform the preventive
maintenance tasks) of 2. 5 hr for Pg:
M = (0.166) (2. 5) = 0.415 hr per week
P
The total estimated maintenance requirement for sewage
pumps and motors would then be the sum of the preventive
and corrective actions as shown on the next page.
103
-------
Mt = Mp + Mc
= 0.415 + 0.237 = 0.652 hr per week
Of this total, preventive maintenance would represent about
63.7 percent of the total effort. If, from this analysis, it
was found that the CM/PM split was reversed, additional PM
should be scheduled to reduce CM requirements.
PLANT EVALUATION
To exhibit the utilization of reliability and maintainability evaluation
techniques previously described in this section, a case problem has
been developed for determining subsystems, elements, and equipment
which degrade system performance. Failure Modes and Effects
Analysis (FMEA) is included in this approach used for determining
a solution to an equipment reliability problem.
Reliability, Maintainability, and Availability Assessments
Various methods can be used in selecting and evaluating a specific
equipment for detailed reliability, maintainability, and availability
characteristics analysis. A method which is considered to be logical
and effective is summarized in Figure 17 and illustrated in succeeding
paragraphs using examples from the Flint plant.
The most serious equipment failures are those which affect the success-
ful operation of the entire plant. These failures can be identified by
"inserting" failures into a reliability block diagram prepared for the
plant and assessing their effect on the plant.
Using this method, it was determined that during the one-year data
reporting period there were no equipment problems which resulted in
a total failure of the plant process. The reliability block diagrams
were then examined to determine if a failure or a combination of
failures could have occurred at the same period of time which would
have hypothetic ally resulted in a total plant failure.
Examination of the plant's "Equipment Malfunctions" reports show
that during the period November 11-12, 1970, five equipment failures
occurred. These failures, added to one which was still uncorrected
from November 10, totaled six equipment failures and represent the
largest number of concurrent failures experienced by the plant during
the reporting period.
104
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1. Select specific equipment for evaluation
(a) Identify the equipment items which are causing the most serious
problems in the plant.
(b) Review plant and equipment reliability and maintainability
information.
(c) List problem equipment in descending order of importance
to plant operation.
2. Examine equipment problem facts
(a) Organize factual information and make an assessment of the
effect of each problem on plant operation.
(b) Examine and interrelate reliability and maintainability
information to determine failure modes, frequencies, and
their impact on plant operation and maintenance.
3. Generate (innovate) and evaluate different ways to solve each problem
(a) Consider various alternatives so the best way to solve an
equipment problem will not be overlooked.
(b) Consider various actions which can be taken.
(c) Evaluate and select the best practical solution to each problem.
Examples:
(1) Perform preventive maintenance prior to the anticipated
time of failure.
(2) Add redundant equipment to take over operation while
the other unit is being repaired.
(3) Improve reliability of the function by replacing existing
equipment with a more reliable or stronger unit.
(4) Improve reliability of existing equipment by modifying
the design.
(5) Decrease repair time by equipment or procedure
modification.
4. Develop a course of action to be taken.
Describe the best actions which must be taken to bring a problem under
control.
Figure 17
Recommended Reliability and Maintainability Analysis Method
105
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Failure Condition Effect on Plant Process
1. No. 5 primary clarifier sludge Slight buildup of sludge in
control valve inoperative. tank until valve repaired
on 11/12/70
2. No. 3 primary clarifier sludge Slight buildup of sludge in
pump packing seal leaking tank until pump repaired
excessively. on 11/13/70
3. No. 1 blower overheating Standby (No. 2) blower
bearing. placed in operation until
No. 1 repaired on 11/12/70
4&5. No. 2 and No. 3 sludge pumps No. 1 sludge pump used
in incinerator building until repairs on Nos. 2 & 3
inoperative. completed on 11/12/70
6. No. 4 primary clarifier scraper Slight scum and sludge
and cross collector chain drive accumulation in tank until
inoperative. repair completed 11/13/70
The combination of these six failures did not result in a failure of the
plant process.
The second most serious equipment failures are those which most
degrade plant subsystems and thereby threaten the successful operation
of the entire plant. These failures are identified by examining the re-
liability models from the top (plant level) down (to the equipment level).
Referring to Figures 15 and 16 it can be seen that Sludge Treatment
and Disposal is the least reliable subsystem (0. 002) and that Sludge
Stabilization is the element (0. 003) causing the largest part of the
problem. The reliability value calculated for this element is due
primarily to the relatively large number of equipment items which
comprise the element. That is to say that the reliability, which is
the product of multiplied decimal fractions, is inversely proportional
to the quantity of the number being multiplied. The low reliability
of the Sludge Stabilization element of 0. 003 is caused primarily
by the low reliability of the Air Flotation Thickener at 0 101 and
the low reliability of the Chemical conditioning Equipment at 0 286
further evaluation showed that within these groups the Thickened
7nUcfo^Meter (0'478>' Grit Scraper Mechanism and Controls
whirh * ^T F!edi?.g Mechanism (0.730) were the equipment items
which were the least reliable. Improving the reliability of this equip-
ment would improve the overall reliability of the plant and reduce
tCo°theCovrr?iaii;terJanCe COStS' AlthouSh these items are fundamental
*L i ? Plant process, they perform a function which is not
absolutely essential to successful treatment. Further investigation of
these items might be deferred until equipment with low reliability
which is essential to the production of an acceptable effluent is
106
-------
evaluated and remedied. Essential equipment with low reliability is
regarded as critical to the plant process until effective remedial
action has been taken to raise its reliability to an acceptable level.
"Activated Sludge" Secondary Treatment is the essential subsystem
having the next lowest reliability to Sludge Treatment and Disposal
and therefore is relatively critical compared to the other subsystems
in the plant. In performing a similar analysis of the Activated Sludge
Subsystem, which has a lower reliability value than the Trickling
Filter Subsystem, it was determined that the Return Sludge Meters
(0. 373) and the Settled Sewage to Aeration Tank Meters (0. 440)
have the lowest reliability and greatest effect on subsystem re-
liability. The "tracing sequence" diagram, used for synthesizing in-
formation in the models and calculation sheets to arrive at these
equipment items, is illustrated in Figure 18. Although both of these
meters perform an essential control function relative to treatment of
what will become plant effluent, the function performed by the Return
Sludge Meter is duplicated by another meter and is located in the
plant's meter room. This is not the case with the Settled Sewage
to Aeration Tank Meters; therefore, without function preservation pro-
vided by a standby, they are considered the more critical.
The function performed by these meters is to indicate the instantaneous
flow rate of settled sewage (from the primary clarifiers) going to
each aeration tank. A failure of one of these meters deprives the
plant operator of knowing whether the actual return sludge flow rate
corresponds to the rate set by the operator. Although failure of this
meter would signal an immediate system failure, the operators could
probably "get by" for several hours by determining the approximate
flow from the valve setting.
Failure Modes and Effects Analysis
Failure Modes and Effects Analysis (FMEA) provides a systematic
procedure for continuing detailed evaluation by using a format for
identifying and assessing the likelihood, consequences, and corrective
action which should be taken for significant modes of a failure. An
example using this format for guiding the analysis is shown in Figure
19.
The type of information used to develop corrective action descriptions
contained in the FMEA format is illustrated in the simple table and
time plot below for the Aeration Tank Meters. They provide an addi-
tional insight into the nature of the failure problem, showing that the
meters failed approximately every three weeks or multiples thereof.
107
-------
R = 0.057
Sewage
Treatment
System
10000
o
c»
Primary
Treatment
Subsystem
11000
n u. JL ao.
Primary
o Clarifier .
11400
R = 0. 156
Activated
Sludge
Secondary
Treatment
Subsystem
12100
R = 0.319
Aeration &
Mixing
12120
R = 0.241
Trickling
Filter
Secondary
Treatment
Subsystem
12200
R = 0.267
Secondary
Settling
12230
R = 0.373
Return Sludge
Meter
12120/09
R = 0.440
Settled Sewage
to Aeration
Tank Meters
12120/16M
(located in the
Meter Room)
0- £j dj UU i
R = 0.940
Effluent
Treatment
(Chlorination)
Subsystem
14000
R = 0.966
Chlorine
Storage
Figure 18
Identification of Low Reliability Items
-------
Subsystem (1) 12100 Activated Sludge Secondary Treatment
Element (2) 12120 Aeration and Mixing
o
co
Equipment Identification
Equipment
(3)
12120/16M
Settled
Sewage to
Aeration
Tank
Meter
Function
(4)
Indicate
(in MGD)
settled
sewage
flow
rate to
each
aeration
tank
Equip.
Relative
Failure
Freq.
(5)
System
0.033
(10/302)
Sub-
system
0.182
(10/55)
Failure
Mode
(6)
A) Stuck at
one meter
reading
B) Indicating
needle oscil-
lates
C) Indicating
incorrect
value
Failure Modes
Effects
Equipment
(7)
Meter fails
to indicate
flow rate of
settled
sewage to
an aeration
tank
Same as
above
Same as
above
and Effects Assessment
on
Element
(8)
Inappropriate
amount of
sewage sent
to aeration
tank
Same as
above
Same as
above
Mode
Proba-
bility in
Equip.
(9)
0.40
(4/10)
0.40
(4/10)
0.20
(2/10)
Mode
Proba-
bility in
Elem.
(10)
0.095
(4/42)
0.095
(4/42)
0.0475
(2/42)
Safe- Cause of
ty Failure
(11) (12)
II Amplifier
failure
II Amplifier
failure
II Amplifier
failure
Solution
Correct
Action
Recommended
(13)
A) Perform PM
every 21 days.
B) Report
failures to
amplifier
manufacturer
A) Perform PM
every 21 days.
B) Report
failures to
amplifier
manufacturer
A) Perform PR
every 21 days.
B) Renort
failures to
amplif ie r
manufacturer
Figure 19
Failure Modes and Effects Analysis
Sheet 1 of 2
-------
Description of the Contents of a Failure Modes andEffects Analysis Worksheet
1. Subsystem identification code number and nomenclature
2. Element identification code number and nomenclature
3. Equipment identification code number and nomenclature
4. Description of the function performed by the equipment
5. Equipment relative failure frequency in the system and subsystem
Rel. fail. freq. (sys.) no. of equipment failures/no, of system failures
Rel. fail. freq. (sys.) no. of equipment failures/no. of subsystem failures
6. Description of failures obtained from malfunction log
7. Effect of failure on equipment
8. Effect of failure on element
9. Probablity of failure mode occurring in the equipment
, . , no. of failures (in mode)
Prob. of mode in equipment
no. of equipment failures
10. Probability of failure mode occurring in element
_ , , .r.A ,, , . . , no. of failures (in mode)
Probability of mode in equipment
no. of element failures
11. Safety hazard class using the following definitions:
Class I SAFE--Conditions such that personnel error, deficiency/
inadequacy of design, or component malfunction will not
result in major system degradation and will not produce
system functional damage or personnel injury.
Class II MARGINAL--Conditions such that personnel error, deficiency/
inadequacy of design, or component malfunction will degrade
system performance but which can be counteracted or con-
trolled without major damage or any injury to personnel.
Class III CRITICAL--Conditions such that personnel error, deficiency/
inadequacy of design, or component malfunction will degrade
system performance by personnel injury or substantial
damage or will result in a hazard requiring immediate cor-
rective action for personnel or system survival.
Class IV CATASTROPHIC--Conditions such that personnel error,
deficiency/inadequacy of design, or component malfunction
will severely degrade system performance and cause subsequent
system loss or death or multiple injuries to personnel.
12. Description of the cause or probable cause of failure
13. Corrective action alternative
Figure 19
Failure Modes and Effects Analysis
(Continued) Sheet 2 of 2
110
-------
Intervals between failures
Days elapsed between failures
1-2
2-3
3-4
4-5
5-6
6-7
7-8
8-9
9-10
24
23
46
82
24
8
21
28
34
(or, 2 x 23)
(approx. 4x21)
(or, 1/3 x 24)
0)
s
1
0 2
v/
\
J
VA
* /v/
0
\
y
n
3
>
\
/\ /
0 40
50 6
Days between successive failures
Based upon this analysis, if successful preventive maintenance on
meter amplifiers is performed every three weeks, meter failures
could be reduced as much as 80 percent. Reducing the number of
failures.in the meter by this amount would increase its reliability
93 percent from 0.440 to 0. 849 and decrease failures in the aeration
and mixing element by 16 percent.
In addition to increasing preventive maintenance on these meters, the
manufacturer should be advised of the performance of his product in
the plant. In many cases, this is not done and an equipment problem
can persist for years without the knowledge of the manufacturer.
This type of information is particularly vital to the manufacturer who
is trying to improve the reliability and maintainability of his product.
DISCUSSION
From the foregoing presentation on the application of R&M techniques
to the Flint Sewage Treatment Plant, certain conclusions and recommen-
dations can be drawn in respect to general use. These have been cate-
gorized into three major areas (equipment reliability, system relia-
bility, and manpower planning) and are discussed in the following
paragraphs.
Ill
-------
Equipment Reliability
Little data are available on the reliability characteristics of waste-
water treatment equipment. Except for very large installations, few
plants keep records which indicate the frequency and severity of equip-
ment failures. Reliability information, such as it is, normally is
distributed by word-of-mouth. Consequently, it is based more on
opinion than on hard data. Nevertheless, reliability reputations are
built and destroyed by this informal communications technique. As a
result, there is a natural tendency on the part of designers to be very
conservative in their choice of equipment; since little or no data are
available, designers will choose equipment that has some demonstrated
performance characteristics. Due to the informal communication pro-
cess, the development of confidence in the reliability of a given equip-
ment item can only take place over a long time period. Consequently,
there is a tendency to avoid new approaches in equipment design. This
has been a strong criticism of the wastewater treatment profession. The
techniques of R&M data collection discussed in this section and illus-
trated in Appendices G and H could be applied in other plants with
minimum additional effort. Equipment malfunctions, failures, etc.,
are easily recorded, as is the practice at Flint. The index system
developed by the System /Equipment Staging Diagrams is most helpful
in organizing the data for easy reference. From this beginning, only
simple mathematics are required to calculate MTBF or MTBM for
equipment. If warranted, these calculations could be programmed for
computer analysis along with suitable reporting forms for management
control.
The collection and organization of these data could form a basis for the
development of performance ratings for wastewater treatment equip-
ment. This would provide plant designers with equipment performance
data which are not currently available. At the same time, it would
motivate manufacturers to improve their products, particularly with
respect to the specific problems being experienced in the plants. It
would provide a state-of-the-art baseline of equipment performance.
The same information could also be used as minimum performance
goals for manufacturers of new equipment. If new equipment could be
rigorously demonstrated to have equal or superior performance and
reliability characteristics in comparison to existing equipment, the
reluctance of plant designers to specify new technology will be
diminished.
System Reliability
One goal of this program was to assess the applicability of reliability
models to: (1) describe the effect of equipment failures on overall
system performance in terms of effluent quality, and (2) depict the re-
liability relationships between equipment, elements, subsystems, etc.
It was found that the reliability model approach could not correlate
equipment failure with effluent quality deterioration. Primarily, this
is due to the current lack of knowledge of the dynamic relationships
112
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between wastewater characteristics and equipment capabilities and
performance. For example, one cannot qualitatively assess the effect
of failure of the grit removal system over certain time spans (five
minutes,, one hour, one day, one year). Thus, the state-of-the-art of
biological wastewater treatment is not sufficiently advanced to allow
the model to represent equipment-effluent quality relationships. This
problem is similar to that discussed in Section VIII on Quality Control.
Until a better understanding of the biological process is reached, it will
not be possible, in most cases, to determine whether the cause of varia-
tion in effluent quality is due to raw waste characteristics, design defi-
ciencies, operator error, or equipment failure. Thus, it is again
recommended that studies be performed to increase our knowledge of
the real performance of biological waste treatment plants.
In this program, a reliability model showing the reliability relationships
between equipment, subsystems, elements, etc., was prepared. This
model was demonstrated to be of value for analyzing the probability of
equipment failures and malfunctions throughout the plant. The tech-
nique is useful for evaluating the magnitude of an equipment problem in
relation to the total plant equipment and can also be used to determine
the degree of improvement which would result from corrective action.
Manpower Planning
In Section VII, staffing analysis techniques were presented for operating
and preventive maintenance functions based upon the development of
OSD's and Function-Capability-Equipment Matrices and Operational/Main-
tenance Task Matrices. In this section, techniques for developing
staffing estimates for unscheduled (or corrective) maintenance were
demonstrated. While a rigorous staffing procedure cannot be developed
because of the random nature of CM requirements, the maintainability
calculations, based upon MTBF and MTTR values provide an excellent
guide for the provision of CM services. A procedure was demonstrated
for estimating the CM man- hours per week for a given equipment
group, based upon past experience. If PM efforts and requirements
have been documented, plant management can then make rational deci-
sions as to the advisability of increasing PM or modifying equipment
in order to reduce downtime or CM requirements due to failures. Thus,
a tool is provided by which corrective maintenance can be controlled
to a much higher degree than is currently the case.
113
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SECTION X
APPLICABILITY OF INDUSTRIAL ENGINEERING
TECHNIQUES TO ADVANCED WASTE TREATMENT
BACKGROUND
Over the past decade, it has become apparent that in many instances ef-
fluent quality higher than that normally associated with secondary treat-
ment will be required to protect critical water resources. To meet this
challenge, a wide variety of unit operations have been and are being de-
veloped; these processes are normally described as "advance waste
treatment" (AWT). Secondary treatment is almost exclusively concerned
with the removal of BOD and suspended solids. While higher removal
levels of these constituents may be required, other considerations, such
as removal of phosphates, nitrogen, or dissolved materials, may be
significant in relation to a particular receiving stream. Thus, the term
"advanced waste treatment" may be applied to a large number of processes
which either improve on secondary treatment performance or remove
or alter other constituents. The most commonly discussed AWT processess
include:
Phosphate Precipitation Breakpoint Chlorination
(lime and/or alum addition)
Carbon Adsorption Biological Denitrification
Microstraining Ion Exchange
Pressure Sand Filtration Electrodialysis (ED)
Rapid Sand Filtration Reverse Osmosis (RO)
Ammonia Stripping Distillation
These processes are widely described in the literature; an overall dis-
cussion can be found in Reference 13. With the exception of biological
nitrification-denitrification,. all of the above processes rely on chemical
and/or physical processes. While these processes are relatively new
to the wastewater field, it should be noted that several have been used
for many decades in water supply treatment: line or alum clarification,
filtration, breakpoint chlorination, and stripping. Microstraining has
been extensively applied to water treatment; ED, RO, ion exchange, and
distillation have been applied to desalting brackish or sea water.
While some questions are arising regarding the ability to remove trace
refractory materials, the traditional water treatment processes have
enjoyed a much higher reputation of being able to consistently produce
an acceptable effluent in comparison to wastewater treatment plants.
There are, of course, several reasons for this difference in performance,
not the least of which is the difference in raw materials.
115
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A major difference in operating requirements between water and waste-
water treatment systems is in the variability of the influent character-
istics. Flow rates to water treatment plants are, as a rule, kept nearly
constant; clarifier and filter efficiencies are directly dependent upon
clarifier overflow and filter application rates. Also, raw water charac-
teristics do not vary as widely as sewage. There are basic differences
in the operating modes between the biological and physical/chemical
processes that also help explain the difference in performance. As dis-
cussed in previous sections, upsets in the biological process are both
difficult to determine on-line and to control. In filtration or adsorption
systems, an upstream malfunction resulting in, for example, increased
suspended solids or dissolved carbon content will usually only shorten
the operating cycle (backwash or carbon regeneration). Thus, upset
would result in increased operating inputs such as backwash .water,
operator time, etc. Another major difference is in waste solids han-
dling. A large portion of the maintenance problems in wastewater
treatment is related to sludge handling and disposal; it is only recently
that consideration is being given to treatment of water plant sludges.
The analogy of AWT processes to industrial activities is equally as valid
as that for secondary wastewater treatment. An evaluation of the appli-
cability of industrial engineering techniques to AWT was performed to
determine significant differences, if any, in comparison to that asso-
ciated with secondary treatment. This evaluation was based upon a re-
view of AWT process technology and a visit to the South Lake Tahoe
AWT Plant,which is the largest and most experienced AWT installation
in the United States.
The Lake Tahoe plant includes a conventional secondary biological treat-
ment plant followed in series by lime precipitation and settling, air
stripping, multimedia separation beds, carbon adsorption, and chlori-
nation. The treated effluent is pumped to Indian Creek Reservoir, a
man-made lake, which is used for swimming, boating, fishing, and as
a source of irrigation water. Detailed descriptions of the unit opera-
tions can be found in Reference 13.
DESIGN AND OPERATION
In Section V, techniques were demonstrated for developing preliminary
designs and operating procedures by identifying and systematically satis-
fying required functions. This approach involved the use of Functional
Staging Diagrams, System/Equipment Staging Diagrams, Function-
Capability-Equipment Matrices, Correlation Matrices, Adjacency
Charts, and Operation Sequence Diagrams. All of these techniques were
found applicable from the standpoint that they would provide a rational
means of organizing decision-making and developing operating plans.
While there are variations in secondary biological treatment, the basic
process elements are the same: contact wastes with microorganism and
separate microorganisms from treated wastes to remove BOD and sus-
pended solids. For AWT there are many more optional approaches, not
116
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only in the constituents to be removed (BOD, suspended solids, phos-
phorus, nitrogen, dissolved organics, and dissolved inorganics), but
also in how it is removed. For example, nitrogen can be removed by
biological nitrification-denitrification, air stripping, selective ion
exchange, or breakpoint chlorination, all of which are quite different
in their removal mechanisms. The FSD's developed must, therefore,
be more general than those associated with secondary treatment. Appen-
dix M contains a sample FSD sheet for removing dissolved inorganic
material. Other FSD's were prepared for: removing or altering nutri-
ent materials; removing suspended solids; and removing residual dis-
solved organic matter.
System Equipment Staging Diagrams and Function-Capability-Equipment
Matrices would be prepared in the same manner as discussed in Chapter V.
Their utility as checklists is heightened since "universal" design criteria
have not been developed for AWT. Thus, it would be very beneficial for
the designer and design reviewer to have the capabilities and matching
equipment selections displayed for ready reference.
Where AWT is being.considered, the quality of the effluent will be-re-
quired to be consistently high. Consequently, provisions must be made
for dealing with off-quality effluent or various failure modes. Layout
of the plant assumes greater importance than in convential plants since
recycle .of off-quality effluent could be handled in a number of ways. The
Lake Tahoe plant contains two ballast ponds which serve several functions:
(1) store ammonia stripping effluent for use in backwashing the separation
beds; (2) equalize peak flows so that the separation beds and the carbon
adsorption column can operate at a steady rate; (3) provide settling for
turbid decanted backwash water if required; and (4) storage for inade-
quately treated wastes before recycle to the separation beds. The ponds
can receive wastes which have passed the lime clarification and/or the
NHs stripping tower. Thus, the ballast ponds must be located in close
proximity to a number of unit operations. The Correlation Matrix and
the Adjacency Chart are quite useful in developing a facility layout for
these conditions.
Operational aspects of AWT may be significantly different than those as-
sociated with secondary treatment. At Lake Tahoe, for example, opera-
tors of the AWT Plant must make decisions as to separation bed backwash,
carbon regeneration, and lime feed rate, all of which have a direct effect
on effluent quality. Thus, it is very important that standard operating
procedures or guidelines be developed to ensure that operating decisions
and practices are correct and the operator's time is efficiently utilized.
In this regard, the OSD technique is quite useful for delineating the detailed
tasks that must be performed by individual operators.
The Lake Tahoe plant has an operations manual considered by many to
be a model for a complete reference document. Over 80 illustrations
are included, most, of which provide detailed data on process cqnfigura-
tions under'a variety of operating modes. For example, piping and
valving diagrams are given for operating the carbon columns in the follow-
ing configurations: (1) normal upflow operation; (2) upflow to waste;
(3) reverse flow; and (4) bypass. A complete outline of this manual is
117
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given in Reference 13. The manual does not, however, relate man and
machine. While certain procedures and operating criteria are given for
numerous contingencies, actions of the operator himself, under normal
and nonroutine conditions, are not outlined. As stated earlier, these
operator routines are usually developed in an informal fashion and are
passed on by "in-servicetraining" to new personnel. The development
of standard operating procedures would allow review of operator per-
formance and would provide an effective training aid.
MAINTENANCE
The development of an effective maintenance management plan, as dis-
cussed in Chapter VI, can be accomplished by developing an equipment
list from the Function-Capability-Equipment Matrices followed by main-
tenance procedure evaluation and the preparation of Maintenance Pro-
cedure Cards (MFC). Most AWT processes require conventional equip-
ment regularly used in chemical processing and in wastewater treatment
(pumps, tanks, filters, etc. ); therefore, the above approach could be
used to the same advantage for AWT processes as is realized in the
chemical industry.
The Lake Tahoe plant has developed a maintenance program which in-
cludes some of the above management elements. A preventive main-
tenance equipment list has been prepared which is indexed by area
(blower room, digester area, tertiary plant, etc. ). This list con-
tains almost 450 equipment entries related to the treatment processes.
Of this total, about half are associated with AWT processes. Preven-
tive maintenance management is based upon an Inspection and Service
Record Card System which is indexed according to the PM equipment
list. Each item of equipment requiring PM is listed on a separate card.
The card describes the work to be done and the frequency. Detailed
maintenance procedures are not provided on the card. A sample In-
spection and Service Record Card is given in Appendix J.
Maintenance at the Lake Tahoe plant is performed by four separate
groups. Almost all PM is performed by the operators. The shift
foreman removes the applicable cards from a master file according to
a required schedule (daily, weekly, etc. ), and assigns the PM work to
specific operators. The regular maintenance crew is authorized to con-
sist of a maintenance supervisor, two mechanics, one electrician, an
equipment repairman (who is also involved with maintenance of auto-
motive equipment), and two utility men. The crew spends about 90 per-
cent of their time on Corrective Maintenance. Their work generally
requires higher maintenance skills than the PM performed by the opera-
tors. The sewer cleaning crew occasionally performs light maintenance
functions, such as cleaning out clarifiers, the barminutor, etc. An out-
side contractor performs PM services on all pneumatic and electrical
equipment (meters, sensing units, thermocouples, panel boards, timers,
etc. ). They also furnish the required replacement parts.
118
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During the day, the operating crew usually consists of seven men, in-
cluding the chief operator. The two night shifts normally consist of
f
-------
The criteria for effective quality control programs, as practiced in in-
dustry, are the same for AWT as for secondary treatment. These are:
statement of product quality goals; ability to control processes; effective
quality measurement techniques; and effective feedback communications.
The clear statement of quality goals and an effective information feedback
system are dependent upon the policies of the regulatory agencies and the
plants involved.
The Lake Tahoe plant, offers an interesting example of the variation in
settling process goals. The South Tahoe Public Utility District was
ordered by the Governor to export treated wastes from the Lake Tahoe
watershed. The Public Utility District was able to negotiate an agree-
ment with the Lahontan Regional Water Quality Control Board, a state
board, for discharge to an area in Alpine County, provided the effluent
met certain quality characteristics. At that time, Alpine County passed
a series of ordinances which fixed the allowable point of discharge and
established separate effluent standards. The Alpine County regulations
are of the "not to exceed" type while the Lahontan RWQCB requirements
are based upon a frequency distribution. A monthly summary sheet
giving both requirements and performance is in Appendix J.
The ability to control the process depends upon the AWT process con-
sidered. If, for example, the effluent from carbon adsorption towers is
too high in dissolved organics, the operator has the option of regenerating
the carbon or decreasing the application rate providing he has standby
columns or storage facilities. Process controls for ammonia removal
by air stripping are less effective. As the ambient temperature drops,
removal efficiency declines. For a fixed air blower capacity, there is
essentially nothing the operator can do to remedy this situation. The
biological nitrogen removal systems suffer the same problems as con-
ventional secondary treatment: the kinetics of the processes are not
well enough understood to control the variations of the effluent quality.
Filtration processes can be "controlled" by backwashing or alteration
of application rate. Polyelectrolytes are sometimes added to overcome
deficiencies in upstream gross solids removal. In most cases, the
chemical oriented techniques are easily controlled by adjusting feed rate.
Thus, for most of the chemical/physical type AWT processes, control
can be exerted by increasing or decreasing an operating input such as:
backwash frequency; regeneration frequency; filter or carbon column
application rates; and chemical feed rates.
The ability to control processes is dependent upon the availability of
effective measurement techniques. The difficulties associated with the
BOD and suspended solids tests as indications of quality and as process
control parameters, as previously discussed, are primarily due to the
inability to measure the parameters of interest directly (MLSS) as well
as the duration of the BOD test. Most of the AWT processes are con-
cerned with measuring materials which are readily measured: PO4,
turbidity, total or organic carbon. For these constituents, the
120
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analyses are rapid, direct, and, in many cases, can be continuously
monitored. For process control purposes, the operator can then have a
cpntinuous record of process performance. If effluent quality is slowly
degrading, he can take operating measures, such as backwashing or re-
generation, before the degradation becomes critical. Recording on-line
instruments can also provide a history which can be used to evaluate not
only overall process performance, but also the effects of equipment or
operator failure and knowledge of process characteristics.
RELIABILITY AND MAINTAINABILITY
The R&M approach considered in Section IX was evaluated for two basic
purposes: (1) determine the probability of equipment failure and the
means for minimizing effects; (2) determine the probability that the
effluent would not meet stated product goals due to equipment failure.
It was .concluded that R&M calculations could be quite beneficial in
reaching the first objective but that the state-of-the-art of biological
treatment was not sufficiently advanced to use R&M analyses to reach
the second. The utility of R&M analysis toward control of AWT equip-
ment failure is equal to that for secondary treatment. The results and
conclusions generated in Section IX in regard to this approach hold for
AWT processes.
As technology develops, the effluent from the AWT plants will be routed
to higher uses. The Lake Tahoe effluent goes to a reservoir which is
used for fishing, boating, swimming, and irrigation. At Windhoek, South
Africa, the AWT effluent is blended into the raw drinking water supply.
As the quality requirements for AWT effluent become higher, the reli-
ability of the AWT treatment processes will become more critical. South
Tahoe, in addition to its ballast ponds, has a 60 MG storage reservoir
which can be used to hold substandard effluent for return to the treatment
plant. Obviously, facilities of this type are expensive. The development
of techniques to assess the probability of the frequency and duration of
plant failures would be valuable in evaluating the relative cost and bene-
fits derived from such facilities. Many of the physical and chemical
unit processes are more amenable to the modeling approach discussed in
in Section IX as applied to the prediction of failure to meet quality goals
than are secondary treatment processes. For example, if a secondary
clarifier sludge pump fails, a certain unknown time span will elapse
before the effluent quality begins to deteriorate; if the stripping tower
blower motor fails, ammonia removal will cease. Also, variations in
the influent quality to most AWT processes are met by increasing or
decreasing "operating inputs" (backwash, etc.). On the other hand,
little is known about the response of the activated sludge system to con-
stantly varying BOD and hydraulic loadings.
It should be possible to develop an R&M model for a specific train of
AWT processes, such as at Lake Tahoe, to correlate equipment failure
with product quality. Separate submodels could be developed for the
various constituents of interest. In each case, the relationship between
121
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equipment and quality would change since each unit operation is intended
to remove different constituents; however, some are capable of remov-
ing other constituents, if required. For example, the carbon columns
could act as a filter in the event of a failure in the separation bed which
resulted in a high suspended solids feed to the carbon columns.
DISCUSSION
There is no question that AWT processes will be increasingly employed
in the near future. Because of the high costs involved and the desire to
produce a consistently high quality effluent, the industrial engineering
techniques described and evaluated in earlier sections for secondary
biological treatment systems are not only applicable but also highly
desirable.
Design and operation practices for secondary plants have evolved empir-
ically over a period of several decades. Past experience is available to
designers and plant managers as a basis for building or operating plants,
regardless of the inefficiency or inadequacies of this approach. For
most AWT processes, this information is not yet available. A procedure
for organizing the development of design and operating practices would
be quite beneficial.
The recommendations given in Chapters V through IX that deal with
industrial engineering techniques are equally applicable to AWT pro-
cesses. In addition, however, it is recommended that a Reliability
Model be prepared for an AWT plant, such as Lake Tahoe, with the
goal of correlating equipment failure to effluent quality. The develop-
ment of this model would provide guidelines for application of R&M anal-
ysis for other AWT plants.
122
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SECTION XI
SUMMARY DISCUSSION
Over the past decade, billions of dollars have been spent in the construc-
tion and treatment facilities for the purpose of upgrading the quality of our
water resources. The success of these facilities in meeting desired goals,
however, is highly dependent upon the operation and maintenance policies
employed. Operating policies for conventional treatment facilities have
evolved through the years by trial-and-error and have been strongly in-
fluenced by the incentives and priorities set by society. With today's in-
creasing concern, not only for the protection of the environment but also
for protecting the growing investment in treatment facilities, interest is
turning to methods by which the performance of conventional plants can
be improved. Over the past few decades, techniques have been developed
to better control and manage the operation of complex systems. Among
these techniques, Work Study and Reliability and Maintainability Analysis
have enjoyed considerable success, particularly in military systems. The
purpose of this program was to evaluate the applicability of these techniques
as well as selected other industrial engineering techniques to the operation
and maintenance of wastewater treatment plants. This was done by applying
the techniques to an existing plant as a case study and by consideration of
current priorities in the waste treatment field. For evaluative purposes,
conventional secondary treatment was considered analagous to an industrial
manufacturing facility. Consideration was also given to the applicability
of the techniques studied to advanced waste treatment processes.
At the outset of the program, initial efforts were directed toward the ap-
plication of individual techniques to specific problems. As the program
progressed, however, it became apparent from consideration of industrial
practices, the overall management of waste treatment plants is generally
poor in comparison to industries with comparable capital investments.
Thus, attention was directed to identifying management deficiencies and
evaluating industrial engineering approaches that could be used to cause
improvement. The areas of consideration were broadened to include a
more comprehensive approach on the utility of industrial engineering
practices from design through quality control.
GENERAL CONCLUSIONS
In Sections V through VIII, the applicability of industrial engineering tech-
niques to the following activities were considered: design and operation,
maintenance, staffing, and quality control. In each section, specific rec-
ommendations were made concerning the applicability of certain indus-
trial engineering techniques to one of the above activities; these are sum-
marized in Table 1 and Figure 1 presented earlier. It is seen from this
table that several of the techniques are common to all activities.
Figure 1 shows the interrelationships between the various techniques and
o
the expected results.
123
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In the interest of clarity, some of the minor relationships between tech-
niques were not shown in Figure 1 . Of prime significance is the fact that
the use of all or most of the techniques enables a designer or manager to
rationally and logically develop a design, detailed operating and mainte-
nance management programs, and a staffing level starting from a defini-
tion of process goals. In effect, therefore, the total approach shown in
Figure 1 provides the procedural framework whereby good management
practices can be developed and instituted. This is particularly impor-
tant in the wastewater treatment field where very little information is
available to the plant manager from either technical literature, pro-
fessional societies, or regulatory agencies on how he should manage the
plant.
The "Federal Guidelines" (Ref. 8) require, among other things, the
following from new plants:
Facilities should be planned for maximum reliability
Facilities should be capable of operating during certain
failure modes
A thorough analysis should be made of operation and main-
tenance requirements, including staffing, operator qualifi-
cations, and operating budget
Plant bypasses should not be permitted
Designs should provide for efficiency and convenience
in O&M and maximum flexibility
Plants should be designed for ease in routine maintenance
Operation and maintenance manuals should be prepared
An effective equipment maintenance program is required
including a control system and a spare parts inventory
Larger plants should have a maintenance management
system for recording and evaluating data
As stated above, there is little information available on how to meet
these requirements. The approach outlined in Figure 1 provides an
overall approach which would satisfy all of the above needs.
It is recommended, therefore, that a management manual be prepared
to outline the steps required for developing better management practices
for both new and existing plants based upon the techniques applied in this
study. This manual should be organized in such a manner as to impress
the reader with the importance of good managerial control in the various
critical areas such as operation, maintenance, quality control, etc. This
is an aspect of waste treatment technology which has been sorely neglected
124
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in the past. With the exception of the mathematics involved in the R&M
model, the techniques evaluated in this program do not require special
knowledge or talents that are not commonly available from most mana-
gerial level personnel.
During the course of the study, management approaches used in industry
were compared to those generally found in the waste treatment field. In
some areas, particularly reliability modelling and quality control, there
were certain technical deficiencies which either limited the applicability
of the approach or prevented good management priorities from being
achieved. Among these are:
Quality goals are not normally stated by regulatory agencies
in a manner which reflects the natural variability of the bio-
logical treatment process.
The primary measurement of effluent quality, BOD, is not
effective as a quality control parameter.
The major process control parameter, food-to-microorganism
ratio, is not directly measured since no on-line analytical tech-
niques are available for measuring viable bacteria or BOD
content.
Little information is available on the variability of biological
treatment performance. It is, therefore, difficult to deter-
mine whether substandard performance is due to equipment
or operator failure, design deficiencies, inhibitory substances,
or the natural cyclical nature of biological processes.
Essentially no data are available on the short-term effects of
equipment failure on effluent quality in secondary systems.
This prevents the Reliability Model from being used to pre-
dict process failures, defined in terms of pollutant concen-
trations, as a function of equipment failures.
Some of the above conclusions have been stated by others on various oc-
casions; the reason for emphasizing them in this section is that they pre-
vent the development of highly effective management programs.
RECOMMENDATIONS
The following is a summary of the major recommendations generated
during this study.
Flint Sewage Treatment Plant
Develop standard operating procedures to complement the
current management practices and to aid in training.
125
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Develop operation cost accounting and maintenance control
systems based upon the indexing system developed in this
study.
Use several of the techniques and documents prepared for
the plant as part of the case study as training aids.
Prepare preventive maintenance procedure cards to ensure
proper performance of PM functions and to better assess
PM manpower requirements.
Add additional maintenance personnel (electrician) to
upgrade the PM program for electrical equipment.
Consider the assignment of additional preventive main-
tenance tasks to the operators as suggested by the results of
the multiple activity chart.
Develop a rapid and comprehensive in-service training program
to ease the problems caused by high turnover rate.
Immediate or Short-Term Application
Develop a management manual for designers or managers
which gives detailed instructions on the application of
techniques for developing sound operation and maintenance
management programs. This would provide procedures for
satisfying the requirements of the "Federal Guidelines"
(Ref. 8).
Develop Functional Staging Diagrams and partially completed
Equipment Staging Diagrams and Function-Capability-Equipment
Matrices for a variety of secondary treatment processes.
These standard documents could then be used, completed,
and submitted with the application for construction assistance
funds. This would provide a checklist for the regulatory
agencies and the designer and would also generate an equip-
ment list with entries indexed according to a standard code.
The collection of data on equipment failure and repair should
be required of treatment plants receiving federal construc-
tion assistance. These data should include: equipment index
number, date and time of failure, reason for failure, per-
ceived effect on process performance, time repaired, time
and manpower required for repair. This requirement will
promote better maintenance programs and will serve as a
data base for reliability and maintainability evaluation
programs.
126
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Future Programs
A state-of-the-art study on secondary treatment should be
performed to identify the caused of variability of effluent
quality and to develop the quantitative relationships
describing the nonsteady state effects of equipment failure
on effluent quality.
A state-of-the-art study of on-line process control is
recommended in order to promote the development of
techniques to enhance quality control in waste treatment
plants. Included should be consideration of alternate
analytical approaches to: (1) describe and analyze ef-
fluent quality; and (2) analyze critical process control
parameters such as the food-to-microorganism ratio.
Consideration should also be given to methods of gen-
erating incentives for advanced technique development
and plant utilization.
Cost/benefit studies should be initiated on the feasibility
of incorporating additional process steps to minimize
variations in sewage flow and strength as well as means
to prevent release of substandard effluent.
The practicality and advisability of uniform quality re-
porting formats should be investigated. This study should
also investigate data collection and handling systems for
documenting the performance of individual plants.
A demonstration project for the application of the indus-
trial engineering techniques evaluated in this program on a
plant under design is recommended. It is suggested that
this program be complete in that it start with process
goals and proceed through the development of staffing
levels, standard operating procedures, maintenance pro-
grams, and quality control programs. This work should
be done for both a conventional plant and an advanced waste
treatment installation.
Development of a computerized data collection and evaluation
system to be used by regulatory agencies for handling data on
equipment failures is recommended. This system would
receive maintenance data from a large number of plants and
keep an up-to-date tabulation of mean time to failure and
mean time to repair. This would form the basis of a data
bank for R&M analysis. At the same time, procedures
should be developed to enable manufacturers to demonstrate
the R&M characteristics of new equipment.
127
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Of all of the above recommendations, the ones dealing with the develop-
ment of a management manual and the studies for better understanding
of the secondary processes (control, effluent quality, and equipment
failure effects) are considered most important. Without adequate pro-
cess technology and effective management, consistently high performance
from biological waste treatment plants will be very difficult to attain.
128
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SECTION XII
ACKNOWLEDGEMENTS
A significant amount of time was spent at the Flint, Michigan Sewage
Treatment Plant in order to collect data for the Case Study. Sincere
thanks are extended to Mr. Robert Misekow, Plant Supervisor;
Mr. David Swenson, Assistant Supervisor; Mr. Don Cole, Maintenance
Supervisor; Mr. L. Stevens, Operator-Foreman; and all of the other
people at the Flint Plant, who have a difficult, sometimes thankless
job to do, yet found the time to be helpful, understanding, and patient
during our visits.
In addition, thanks are extended to Mr. R. Gulp, Plant Superintendent,
and Mr. E. Hardie, Chief Operator, of the South Tahoe Waste Treat-
ment Plant for their great assistance during a comparatively brief but
intensive visit. The support of the project by the Office of Research
and Monitoring of the Environmental Protection Agency and the guidance
provided by Mr. Walter F. McMichael, Project Officer, and Mr. Morton
S. Ettelstein, Division of Manpower and Training, is acknowledged with
sincere appreciation.
Significant contributions were made by the Stanwick Corporation of
Arlington, Virginia, as the principal subcontractor on this project.
Stanwick personnel participated jointly with Hittman Associates in
the plant visits, analysis, and the development of this report. The
assistance and review comments provided by Grover Barkdoll, H. B.
Maynard & Co. , Inc. , are gratefully acknowledged.
129
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SECTION XIII
REFERENCES
1. "Definitions of Effectiveness Terms for Reliability, Maintain-
ability, Human Factors and Safety," MIL-STD-721B, Depart-
ment of Defense, Washington, D.C., August 1966.
2. Iveson, W. G. , and E. L. Grant, Handbook of Industrial Engi-
neering and Management, Second Edition, Prentice-Hall,
Englewood Cliffs, New Jersey.
3. Maynard, H. B. , Industrial Engineering Handbook, Third Edition,
McGraw-Hill Book Company, New York, 1971.
4. Carson, G. B. , Production Handbook, Third Edition, Ronald
Press Company, New York.
5. Morrow, L. C. , Maintenance Engineering Handbook, Second
Edition, McGraw-Hill Book Company, New York, 1966.
6. Design Manual-Civil Engineering, NAVFAC DM-5, Naval
Facilities Engineering Command, Washington, D. C. ,
January 1969.
7. "Operation of Wastewater Treatment Plants, WPCF Manual
of Practice. No. 11, Water Pollution Control Federation,
Washington, D.C., 1970.
8. "Federal Guidelines Design, Operation and Maintenance of
Waste Water Treatment Facilities, " U.S. Department of the
Interior, FWQA, September 1970.
9. Juran, J.M., Quality Control Handbook, McGraw-Hill Book
Company, New York, 1962.
10. Thomann, R. V. , "Variability of Waste Treatment Plant Per-
formance, " Jour. San. Eng. Div. , Proceedings of the ASCE,
96, No. SA3, 819, June 1970.
11. Carr, D. F. , and J. Ganczarczyk, "A Performance Analysis
of an Activated Sludge Plant," Publication 71-600, University
of Toronto, Department of Civil Engineering, February 1971.
12. "FY 1970 State Program Plants, " U.S. Department of the
Interior, FWQA, Washington, D.C., 1970.
13. Gulp, R.L. , and G. L. Gulp, Advanced Wastewater Treatment,
Van Nostrand-Reinhold Company, New York, 1971.
131
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SECTION XIV
APPENDICES
Page
A. Functional Staging Diagrams 135
B. Process Flow, Sewage Treatment Plant, Flint, Michigan. . 141
C. Physical Layout, Sewage Treatment Plant,
Flint, Michigan 143
D. System/Equipment Staging Diagram 145
E. Operation Sequence Diagrams 159
F. Operational/Maintenance Task Matrices, Sewage
Treatment Plant, Flint, Michigan 175
G. Malfunction Log, Sewage Treatment, Flint Michigan .... 211
H. Reliability and Maintainability Data 215
I. Formulas and Approximation Formulas for Calculating
the Reliability of Redundant Relationships 219
J. AWT Functional Staging Diagrams 223
133
-------
APPENDIX A
FUNCTIONAL STAGING DIAGRAMS
135
-------
Perform Operational Processes
10000
GO
Receive Sewage and Remove a
Large Portion of Settleable
and Floating Solids
11000
Remove Oxygen Consuming
Materials in Settled Sewage
12000
Provide for the Stabilization
and Ultimate Disposal of
Putrescible Solids
13000
Achieve Disinfection of Effluent
Prior to Release & Prevent
Septic Conditions in the
Treatment Process
14000
FUNCTIONAL STAGING DIAGRAM (FSD)
(sheet 1 of 5)
-------
r
Receive Sewage From
Interceptors and Establish
Hydraulic Head
11100
Receive Sewage & Remove a Large
Portion of Settleable
& Floating Solids
11000
Receive Influent &
Divert Excess Flow
Remove Gross Solids
11300
Remove Settleable and
Floatable Solids
11400
Receive & Contain
Wastes for Settling
11410
Collect Settled
Solids
11420
Collect Floating Solids
11430
Convey Settled Solids
11440
Convey Floating Solids
11450
Collect & Convey
Clarified Wastes for
Further Treatment
11460
Sample & Analyze
Effluent
11470
Monitor & Control Flow
in Settling Tanks
11480
FUNCTIONAL STAGING DIAGRAM (FSD)
(Continued)
(sheet 2 of 5)
-------
Remove Oxygen Consuming
Materials in Settled Sewage
12000
1
Remove Oxygen Consuming Materials
in Settled Sewage by the Activated
Sludge Process
12100
_L
CO
CO
Remove Oxygen Consuming Materials
in Settled Sewage by the Trickling
Filter Process
12200
1 1
^mar?^ t£% ^$%£%F
J Suspended Microorganisms
12210 12220
-
1
Convey Influent
from Primary
Treatment
12211
Provide
Contact
Surfaces
12221
Distribute
Flow to Each
Filter
12212
Provide
for Air
Circulation
12223
Control Flow
to Each
Filter
12213
Control Dose
Rate to
Each Filter
12225
Monitor Flow
12214
Convey Re-
cycled Filter
or Settling
Tank Effluent
12227
Sample &
Analyze Re-
cycled Filter
Effluent
12229
Contain
Contact
Surfaces
12222
Remove Settleable and
Floating Solids
12230
1
Receive &
Distribute
Filter
Effluent
12231
Convey
Wastes to
Contact Sur-
face 12224
Contain
Wastes for
Settling
12233
Collect
_ Wastes After
Filtration
12226
Collect
Floating
Solids
12235
Monitor &
Control
Recycle Rate
12228
Convey
Floating Solids
to Sludge
Treatment
12237
Convey
Wastes to
L Settling
Tanks
12229-1000
Sample &
Analyze
Effluent
from Settling
12239
Control Flow
to Settling
Tanks
12232
Collect
_ Settled Solids
12234
Convey Settled
Solids to Sludge
~ Treatment
12236
Convey Clar-
ified Wastes
forFurther
Treatment
12238
Monitor
Waste Sludge
~ Flow Rate
12239-1000
Sample &
Analyze
- Waste Sludge
12239-2000
FUNCTIONAL STAGING DIAGRAM (FSD)
(Continued)
(sheet 3 of 5)
-------
Provide for the Stabilization
and Ulitmate Disposal of
Putrescible Solids
13000
GO
CD
Receive Waste Solids
from Primary &
Secondary Systems
13100
Convey bolids
for Further
Treatment
13212-2000
Monitor Flow
13130
Collect &
Remove
Dewatered
Solids
13212-3000
Provide
Chemical
Stor
13211-2100
Provide v
Means for
Dewatering
Solids
13212-4000
Feed
Chemicals
13211-2200
Control
Feed Rate
13211-2300
Monitor
and Record
Feed Rate
13211-2400
Stabilize Solids
13200
~r
Destroy +
Putrescible
Materials
(Initial)
13220
~L
Provide for Ultimate
Disposal of Treated
Solids
13300
Remove for
Ultimate
Disposal or
Subsequent
Treatment
13225
NOTES:
* Various approaches can be employed, including
vacuum filtration, air flotation, gravity settling
w/wo gentle stirring, centrifugal!on, and sand
nitration.
Subfunctions are same as 13210 except for number
changes
^ Subfunctions are same as 13220 except for number
changes
Depends upon particular process
being used, some of which are incineration
(heat), anaerobic digestion (heat, lime),
aerobic digestion (dissolved oxygen) and
wet air oxidation (high pressure, heat).
+ In most cases conditioning and dewatering
are practiced before putrescible solids are
destroyed. However, many plants condition
solids before and/or after the solids are
stabilized by digestion processes.
FUNCTIONAL STAGING DIAGRAM (FSD)
(sheet 4 of 5)
-------
Store Chlorine
14100
Provide for Chlorine
Container Storage
14110
Provide Mobility
of Containers
14120
Monitor Supply
on Hand
14130
Achieve Disinfection Prior to
Release and Prevent Septic
Conditions in the
Process
14000
Supply Chlorine
14210
Convey
Chlorine Solution
14220
Analyze Chlorinated
Wastes for Chlorine
Residual
14230
Analyze Chlorinated
Wastes for Bacterial
Content
14240
T These functions may not be required
for prechlorination
Feed Chlorine
14200
Provide Contact
14300
Control Feed
14250
Monitor & Record
Chlorine Feedrate
14260
Record Chlorine
Residual
14270
Receive Effluent
from Preceding Process
14310
Provide
Mixing
14320
Convey Treated Wastes
to Discharge or Next
Treatment Step
14330
Contain Treated Wastes
14340
Meter or Monitor Flow
14350
FUNCTIONAL STAGING DIAGRAM (FSD)
(Continued)
(sheet 5 of 5)
-------
APPENDIX B
PROCESS FLOW SCHEMATIC
SEWAGE TREATMENT PLANT
FLINT. MICHIGAN
141
-------
Scum Jljector
iButtertly i .- ,,
f* Valve i' , -J
I i Flow ,' ' I . x- -,
/ I Splitter pfhicP* -1 / \
Meter
I Indicator
R Recorder
T Totalizer
Control Valve(s]
C Constant Speed
V Variable Speed
C7 Pump
PROCESS FLOW SCHEMATIC
FLINT SEWAGE TREATMENT PLANT
(sheet I of 1)
-------
APPENDIX C
PHYSICAL LAYOUT
SEWAGE TREATMENT PLANT
FLINT, MICHIGAN
143
-------
Scum Ejector [1]
Raw Sludge Pumps (6) [7]
.rComminutors (4)[8]
~
Chlorine Contact
Tanks
Filter Cake Conveyor [19]
STATUS BOARD
INDICATING LIGHTS
Scum Ejector
Spray Water Pump
H. P. Final Effluent Pump
Primary Effluent Pump
Primary Effluent Screen
Collector Drive
Raw Sludge Pump
Comrninutors
Grit Collector
Grit Pump
Final Effluent Screen
Return Sludge Pump
Waste Sludge Pump
Settled Sewage Pump
Blower
Chlorinator
Digested Sludge Pump
Recirculation Pump
Filter Cake Conveyor
Vacuum Filters
24" Force Main
Incinerators
Vacuum Filters [20]
FLINT PLANT LAYOUT
FLINT PLANT LAYOUT
(sheet 1 of 1)
-------
APPENDIX D
SYSTEM/EQUIPMENT STAGING DIAGRAMS
145
-------
System
Sewage
Treatment
System
10000
Subsystem
Advanced
Treatment
15000
See Sheet #2
SYSTEM/EQUIPMENT STAGING DIAGRAM
Sheet 1 of 12
-------
Sub-
System
Primary
Treatment
HOOO
Element
Pumping and Screening
11100
Influent Collection
11200
Equip- 11100/01
ment 102
/03
/04
/05
/06
/07
Raw sewage mains
Pump station set well
Sewage pumps and
motors
Pump motor controls
Piping and check
values
Flow meter and
recorder
Sample jars, sampling
pole, and jar
carrying container
Laboratory equipment
Preliminary Treatment
11300
Primary Clarifier
11400
11200/01 Influent pipes
/02 Influent collection
chamber
/03 Overflow weirs
/04 Overflow channel
/05 Sluice gate or valve
/06 Valve operating device
/07 Influent pipe to grit
tanks
/08 By-pass chamber
/09 By-pass pipe
/10 Flow meter
11300/01 Bar screen (and rake)
/02 Grit tanks
/03 Grit removal mechanism
/04 Sewage flow control
/05 Grit pumps
/06 Influent and effluent
piping
/07 Weirs
/08 Air compressors
/09 Air piping and valves
/10 Air drops and diffusers
III Comminutor chamber
/12 Comminutors
/13 Control and by-pass
devices (stop plates,
valves etc.)
/14 Trash removal
/ 15 Influent and effluent
piping or channels
/16 Effluent piping or
channels
/17 Control valves or
plates
11400/01 Influent channel
/02 Distribution pipes for
all wastes to be
settled (raw sewage,
re-cycled waste
sludge from primary/
secondary)
/03 Settling tanks
/04 Air piping and controls
/05 Air diffusers
/06 Sewage control valves
and gates
/07 Meter (sewage flow to
each clarifier)
/08 Sludge scraper
mechanism
/09 Sludge pumps (primary)
/10 Control valves (sludge)
III Piping (sludge) in
settling tank
/12 Meter (sludge)
/13 Scum collection
mechanism
/14 Scum collection trough
/15 Scum removal pump
( ejector)
/16 Scum control valves
gates etc.
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 2 of 12
-------
11400/17 Scuin piping in
settling tanks
/18 Sludge piping to
sludge disposal
/19 Sludge valves
/20 Scum piping to
scum disposal
/21 Scum valves
/22 Primary treatment
effluent channel
/23 Effluent valves
and gates
/24 Weirs
/25 Laboratory (D. ),
suspended solids,
volatile suspended
solids, BOD, PH)
/26 Flow measuring
device (settled
sewage)
/27 Indicating meter
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued) Sheet 3 of 12
-------
Sub-
System
Secondary
Treatment
12000
Element
CO
Activated Sludge
Process
12100
Trickling Filter
Process
12200
Contact Stabilization
Process
12300
Aerated Lagoon
Process
12400
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 4 of 12
-------
Element
Sub-
Element
Equipment
Activated Sludge
Process
12100
Transfer
Unit Operation
12110
01
O
Aeration & Mixing
Unit Operation
12120
12110/01 Channel (Primary Effluent)
/02 Flow control valves &
piping (primary effluent)
/03 Meter (flow)
/04 Air compressor
/OS Piping (pneumatic instrument air)
/OS Filter (air compressor)
/07 Piping (primary effluent)
/08 Water screens
/09 Pump (primary effluent to
thickeners)
Settling
Unit Operation
12130
12120/01 Tank (aeration)
102 Blowers
/03 Filters (air)
/04 Meter (air cym)
/05 Flow control valves (air)
/06 Diffusers (air)
/07 Piping (air)
/08 Pump (cooling water)
/09 Meter (return sludge gpm)
/10 Flow control valves (return sludge)
111 Trough (mixed liquor)
/12 Foam spray system (pump, pipi,
nozzles, etc.)
/13 Protected water system
/14 Laboratory analysis system (dissolved
oxygen, mixed liquor suspended
solids, mixed liquor volatile
suspended solids, pH)
12130/01 Tanks (final clarifier)
/02 Control valves (mixed
liquor)
/03 Scum removal mechanism
/04 Scum removal pump/
ejector
/05 Piping (scum)
/06 Sludge scraper
mechanism
/07 Sludge well
/08 Pumps (return sludge)
/09 Piping (return sludge)
/10 Trough (secondary
effluent)
/ll Laboratory analysis
system (dissolved
oxygen, BOD,
suspended solids,
pH, NH3, TKN, NO3,
index, sludge %
solids)
/12 Piping (settled sludge)
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 5 of 12
-------
Element
Trickling Filter
Process
12200
Sub-
Element
Equipment
Transfer
Unit Operation
CJl
12210
Filter
Unit Operation
12210/01 Pumps (settled sewa
/02 Wet well (settled sewage)
/03 Piping (settled sewage)
/04 Meter (settled sewage flow)
/05 Pre-air tank
/06 Air compressor
/07 Filter (air)
/OS Piping (air)
/09 D iff user (air)
/10 Meter (air psi. & cfm)
12220
Settling
Unit Operation
12220/01 Tank (trickling filter)
/02 Tank false bottom
/03 Filter media
/04 Dosing mechanisms
/05 Dosing distribution piping
/06 Dosing nozzles
/07 Collecting manifold (filter
underdrain)
/08 Piping (filter effluent)
/09 Piping (recycled filter
effluent)
/10 Valves (recycled filter
effluent)
111 Meter (recycled filter
effluent flow)
/12 Laboratory analysis system
(BOD, dissolved oxygen,
suspended solids, pH)
12230
12230/01 Tank (final clarifiers)
/02 Scum removal mechanism
/03 Scum removal pump
/04 Piping (scum)
/05 Sludge scraper mechanism
/06 Sludge well
/07 Pump (waste sludge)
/08 Piping (waste sludge)
/09 Meter (waste sludge flow)
/10 Trough (trickling filter
effluent) '
111 Control valve (effluent)
/12 Laboratory analysis
system (BOD, dissolved
oxygen, suspended
solids, pH, NH3, NOg,
SDI, SVI, % solids)
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 6 of 1 2
-------
Sub-
System
Element
Equipment
Sludge
Treatment and
Disposal
13000
Transfer
Unit Operation
13100
Stabilization
Unit Operations
13200
Disposal
Unit Operation
13300
DO
13100/01 Pumps (waste sludge,
humus, primary sludge)
/02 Piping (waste sludge, humus,
primary sludge)
/03 Flow control valves (waste
sludge, humus, primary
sludge)
/04 Meter (waste sludge flow)
/05 Laboratory analysis system
(pH, suspended solids,
volatile solids)
13300/01 Ash hopper (slurry tank)
/02 Pump (ash hopper spray
water)
/03 Pump (ash hopper agitator)
/04 Pump (ash slurry)
/05 Strainers (ash slurry)
/OS Piping, valves and nozzles
(ash hopper spray water)
/07 Piping, valves and nozzles
(ash hopper agitator)
/08 Piping (ash slurry)
/09 Ash lagoon facilities
Flotation System
13210
Anaerobic Digester
13220
Dewatering System
13230
Incinerator
13240
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 7 of 12
-------
Flotation System
13210
Chemical Addition
13211
Air
Flotation Thickener
CO
13212
13212/01 Tank (flotation thickeners)
/02 Sludge skimmer mechanism & controls
/03 Sludge well
/04 Pumps (thickened sludge)
/05 Piping (thickened sludge)
/06 Valves (thickened sludge)
/07 Meter (thickened sludge flow)
/08 Subnatant well
/09 Pumps (thickener subnatant)
/10 Piping (thickener subnatant)
/ll Valves (thickener subnatant)
/12 Grit screw mechanism & controls
/13 Grit scraper mechanism
/14 Grit well
/15 Pump (grit)
/16 Piping (grit)
111 Valves (grit)
/18 Compressor (flotation air)
/19 Piping & valves (flotation air)
/20 Filter (air compressor)
/21 Pressure tank
/22 Compressor (instrument air)
/23 Piping & valves (instrument air)
/24 Filters & dryers (compressor-instrument air)
/25 Laboratory analysis system (pH, suspended
solids, volatile solids)
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 8 of 12
-------
Anaerobic Digester
13220
en
13220/01 Recorder (waster sludge flow,
digested sludge flow)
/02 Tanks (digester)
/03 Meters (temp, waste sludge flow,
digested sludge flow)
/04 Piping (waste sludge)
/05 Valves (waste sludge)
/06 Heat exchanger
/07 Pump (recirculating-heater)
/08 Pump (digested sludge transfer)
/09 Piping (digested sludge transfer)
/10 Valves (digested sludge transfer)
111 Pumps (digested sludge)
/12 Piping (digested sludge)
/13 Valves (digested sludge)
/14 Piping (digester supernatant)
/15 Valves (digester supernatant)
/16 Protected water system (heat exchanger)
111 Laboratory analysis system (pH, suspended
solids, volatile solids)
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 9 of 12
-------
Dewatering System
13230
Chemical Conditioning
13231
on
en
Vacuum Filter
13231/01 Tank (chemical conditioning)
/02 FeCl3 storage tank
/03 Lime storage tank
/04 Lime feeding mechanism
/05 Lime slaker
/06 Lime solution (slurry) tank
/07 Protected water system
/08 Pump (lime solution)
/09 Piping (lime solution)
/10 Pump (FeCl3 solution)
III FeClg solution tank
/12 Pump (FeClg solution)
/13 Piping (FeCls solution)
/14 Piping (conditioned sludge)
13232
13232/01 Vacuum filter unit
/02 Vacuum pump unit, separator and pipint
/03 Protected water system
/04 Pump (filtrate)
/05 Piping (filtrate)
/06 Sludge conveyor velt mechanism
/07 Portable belt conveyor
/08 Compressor (sludge well)
/09 Air filter (sludge well compressor)
/10 Sludge well
III Piping & valves (air)
/12 Diffuser (air)
/13 Pump (sludge)
/14 Piping (sludge)
/15 Pump (Calgon feeding)
/16 Piping (Calgon)
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 10 of 12
-------
Incinerator
Ul
O3
13240
13240/01 Incinerator
/02 Sludge conveyor belt mechanism
/03 Filter cake splitter unit
/04 Weight scales
/05 Recorder (filter cake weight)
/06 Gas (scrubbers)
/07 Pump (scrubber water)
/08 Piping (scrubber water)
/09 Final effluent well
/10 Blower (shaft cooling)
/ll Induced draft fans
/12 Air compressor (service air)
/13 Air filter (air compressor)
/14 Piping & valves (air)
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 11 of 12
-------
Sub-
System
Chlorinatlon
Process
14000
Elem ent
Equipment
Chlorine Storage
14100
Chlorine Feed
Unit Operation
14100/01 Storage racks for
chlorine cylinders
/02 Weighing scale
/03 Trolley hoist
/04 Cylinder valve connectors
cn
14200
Contact
Unit Operation
14300
14200/01 Chlorinator (including
meters)
/02 Flow control valves and
piping (chlorine)
/03 Flow control valves and
piping (water)
/04 Meters (vacuum, flow)
/05 Recorder (chlorine feed
rate)
/06 Chlorine residual analyzer
& recorder)
/07 Ambient chlorine detector
/OS Piping & valves (chlorine
solution)
/09 Protected water system
/10 Laboratory analysis system
(chlorine residual,
coliform bacteria)
14300/01 Contact tank
/02 Chlorine diffuser
/03 Baffles
/04 Piping (final effluent)
/05 Meter (final effluent flow)
SYSTEM/EQUIPMENT STAGING DIAGRAM
(Continued)
Sheet 12 of 12
-------
APPENDIX E
OPERATION SEQUENCE DIAGRAMS
Legend:
Symbols
<0
Transmission
Operation
Inspection, Examination
Decision
Combined Inspection and Operation
rFA
| _ / Written Form
Numbers Within Symbols
1 - Every hour, e.g. 1
2 - Every 2 hours
4 - Twice a Shift
8 - Once a Shift
12 - Twice daily
24 - Once daily
48 - Every two days
W Walk
FPF-3 - Flint Plant Form 3
159
-------
SYSTEM Flint Wastewater Treatment Plant
USE OF WORKSHEET Describe operations performed
by operator foreman daring two-hourly plant inspec'
PROJECT TITLE Application of
Industrial Engineering Techniques
STAGE NO.
PREPARED BY
G. Calnan
SHEET NO.
1 of 4
DATE
4/14/71
APPROXIMATE
ELAPSED
TIME!
(MINUTES)
0
2
3
3'
5
7
9
11
13
14
16
18
/ £ / o / & /?*/ f#/,.f$/ '£&/ / /$$/$£/$'&/ / / /
EXTERNAL / * / ^ / / / / if &/ / / /EXTERNAL
INPUT
rV
V
Sample
Require-
ment Sj
Inspection
InstrucLio
Record
Sheets
Yes
Make ad-
justments
with
////////
/2\ Pick up sample
( ) bottles & carrying
^"^ rack from lab
l
Jw^-
L^J
i
p
1
o
V
chlorinator 1^ _,
control
knobs
Ye
Shift to
next tank.
Exchange
tank from
outside
stowage
for empty
tank
Y
GO
X.
Nj/
s^~\
\)
T
^
To chlorine control room
Checklfor chlorine odors
Check evaporators Nos. 1
gasternperature & pressui
meters
Adjustment
No
Check and r
tank in use
requir
ed?
& 2
cord scale weight o1.
(FPF Ijfo. 7)
Chlorine tank chan
requi
To ae
red?
ration
)uildin
= e
chlori
(\ Pick up sample drawing pol
\ J and additional sample
1 bottles from lab. ,
to aeration tanks
T_J
r~
[ 2 )
[
rt
-@-
I
~~~L Draw sample irom a
IA} Set down bottle
x
^pL
x
( 4 )
S
*&
Y
/^
( )
y
-/w]
Renioi
Place
into c
conce
To ae
pipe
To next aeration tan
Draw £
Set do-
To mi:
effluer
Pick u
sarnpl
To aej
e samj
riLxed
sntrii'u
tratioi
" ati on
allery
ample
m bott
ed liq
. chan
A
( 2 /
r? l
w]
5 first
bottli
at ion 1
le botl
iquor
e for
test.
ank
from E
e. Se
or anc
els
Draw
Samp
moun
Draw
effliu
s
uildinj
es.
ample
ludge
IB
e
a ration
eratior
down
plant
mixed
e usm^
ed on
plant I
at sam
/////// OUTPUT
ank
;ank.
ole fc
nal
quor
pole
ail
nal
le
NOTE
Tank
See a
aera
!influe
1
TS^
^ J
j
/fm
Sam
ever
2 and
6 anc
0 anc
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ove nc
on tat
t to fi
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air te
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recor
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recori
0800.
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card
es ar
four
4
8
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e
larg<
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nd re
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ed ea
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ed dai
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r Bur
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ours.
a amp
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c she
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ally a:
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au
info!
bottl
1 F 'X
ank outside
er) To
F-A
e - fp-pK 'gO
y
To
Weather
Bureau
^r
owing order
s
_\ To
| ) Sheet 2
160
-------
Flint Wsstewater Treatment Plant
USE OF WORKSHEET Describe operations performed by
operator foreman during two-hourly plant inspections
PROJECT TITLE
Application of Industrial
Engineering Techniques
STAGE NO.
PRJEPAREP BY
^W
DAT|/14/71
APPROXIMATE
ELAPSED
TIME
(MIN 3TES)
Sh
21
22
23
24
25
27
28
31
32
33
43
45
50
EXTERNAL / V ,
INPUT / /
From*
V
Approxima
time requi
20 minutes
To admin.
bldg. mete
room.
te
' ^ / T? / * / V4V ^ /**?/ /"*" /H/0^/ / / /EXTERNAL
///////////// OUTPUT
1 j> 1
,/
\
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|
w>-
r
? Nj
.. ^
r
-5
r
i
r
I
|2 |
L
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LfJ
^
^
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and b
gland
To ba
first
Inspe
comp
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blowe
Inspe
tank j
Retur
Checl
S\
Y
^
Inspe
on cl
(1) I
(2) I
(3) I
(4) I
(5) I
(6) /
(7) £
(8) C
t oper
semen
leakag
5 em en
evel.
:t oper
essor
losite
: basei
:t oper
age an
i to ae
blowe
Perfor
dissol-
To bio
t blow
p boar
lower
xciter
rive ei
ighest
C. ar
ir tern
uth be
enter 1
rS
\j
.-L
LJ
JwL
l**^
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1 ,J
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ition o
; sump
ition o
. Ble
iide of
lent.
ition o
. city v
ation
air ir
|
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ite.
. Insp
valves
norm;
ation o
ps. Ha
vibra
ent pui
next t
on (in(
e). (FF
efflue
one en
lab. a
.oor.
-d the
e
e
ure 1
ature
retur
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y high
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prim
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. (to tr
water
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ct pip.
enrout
noise
high ]
nd touc
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tip disc
nortt
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F-8)
t filte
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= (eve
sludg
heat a
ispect
ifor a
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ry effl
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icklin
and pa
d
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s.
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ollow]
9) Nc
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12) O
13) V,
14) A
15) Ir
16) S.
17) L
ng for
rovide
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1 inlet
1 outk
ater p
C. an
:ernal
cond f
>vel oi
; pum
y 4 ho
pump
id vib
npes,
snorm
epth rr
uent p
ond le
printer
filter
iking
e fina
morm
eadin
st pur
r filte
g
and
No. 4
ach b
on cl
ring t
ure (f
empe
temp
essurf
j.
uide i
ss dii
settlei
s.
ITS).
3. Ha
ations
gasket
.1 nois
eter.
mps
el.
enrou
lly
on
3.
AR -
As re
ower c
^ boar
mpers
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ature
rat ure
ane se
solved
sewa£
i
s.
e.
uired
forrr
ure
ing
oxyge
well
F_\
[7FPF-8))
AR - As
Required
-Normally
once or twice
per week
F \
[7pW>
[FPF sy
A To
r~\ Sheet 3
161
-------
Flint Waste-water Treatment Plant
USE Of WORKSHEET Describe operations performed by
operator foreman during two-hourly plant inspections
PROJECT TITLE
Application of Industrial
Engineering Techniques
STAGE NO.
PREPARED BY
G. Calnan
SHEET AIO.
3 of 4
DATE
4/14/71
APPROXIMATE
ELAPSED
TIME)
(MINUTES)
Approxima
time requi;
10 minutes
Approximaj
time requi
2 minutes
(5 mirJ
Delr
to lal
Take
requ
Cons'
/unit)
hourl1
ed ad
readii
ustme;
fe delay
pies
ie FPF'2
lathroqm stopT
To digester
building
Check
contn
To ba
(nort
Bleed
water
Check
to gri]
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cylindji
requi:
Inspe
comp.
To gr
G.E.
[l pane!
iemen>
end)
instru;
ip,
light,
ment a
micro
protec
rerno
:t and f I
era 01
ed nor
:t and
essord
sludgi
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sludg|
id just.1
sludg^
ough.
or (nolr
ChecH thickdi
temp
Checl
tive w|
al pu
air p
Anally
witch
daily
Lnstrui
at 8 Ai*
to thr]
Inks.
condi
lent 01)
well.
Put sat
mallyj)
Checl
tank
n to g.
G. E.
Checti prot'
kralve.
klean;
leter
ater d:
(3)
it magjr
essur
ivery
:ion an]
time
Take
iple 11
everj
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exchd
gage
n pum]
'ctive 4
Chan;
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hours
skim:
;locks
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jar fo
2 hour
.ngers fl
contni
s, frai
ater p
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witch
ler bl
.s reqj
when
pick
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ol pani
.ps, antl Hand-
ides.
.ired.
sampld
Is,
limps dnd
daily at 8 A
.ate drbdnageJ
^
To
Sheet
4
162
-------
Flint Wastewater Treatment Plant
USE OF WORKSHEET Describe operations performed by
operator foreman during two-hourly plant inspections
PROJECT TITLE
Engineering Techniques
STAGE NO.
PREPARED BY
G. Calnan
SHEET NO.
4 of 4
DATE
4/14/71
94
96
o
rec
wor
fore
Tak<
req
r desc
lalfun
rding
orde
an, ;
ription
ioned
heet.
Con
requ
3 of fa
quipm
Iniiiat
act ma
red. S
readi
justme
Led
;nt on
repai
intena
e FPI
ngs. Make
nts.
To incinerator bi
Insp
cles
Che
Mak
assi
Che
Che
tern
opei
Che
ect
ning w
e new
jnmen
;k furr
leratm
ator r.
Pro-
as r
equi
ride op
equest
irnent.
,k weij ht met
ace op
e prin
;cordii
srator
id, to
.Id ing
:ompli;
rk ass
>n PPB
ileanii
s on 1
work
PF No,
(2) wi
nspect
g mete
ignmei ts.
No. 1
rSj a
shee
1
rder
furns
& ope i
163
-------
Filter Operator - Operations
USE OF WORKSHEET
PROJECT TITLE
Application of Industrial
Engineering Techniques
PREPARED BY
R. E. Muller
Flint Sewage Treatment Plant
filteii records (2),
es of FeCl3 level in day tank and records
avity teaker.
le of FeCl3 solution for specific gravity test
Obtained filtrate samples
164
-------
SYSTEM
Filter Operator
USE OF WORKSHEET
Flint
- Operations
Sewage Treatment Plant
PROJECT TITLE
Application of Industrial
Engineering Techniques
STAGE NO.
PREPARED BY
H. E. Muller
SHEET NO.
2 of 3
DA4TfH/71
of FeCls pumps. (Normally checked
TIME
ter
Che
B leve
of 1
1
' etorabe tanKj 1
\ Transfers lime frcjm
1 storage to siakersl
FPF
11,12, 13
!To
heet 3
165
-------
SYSTEM
Filter Operator - Operations
USE Of WORKSHEET
Treatment Plant
PROJECT TITLE
Application of Industrial
Engineering Techniques
STAGE NO.
WMer
SHEET NO.
3 of 3
DATE
4/14/71
TIME
EXTERNAL
INPUT
EXTERNAL
OUTPUT
From
Sheet
2
es lirr
fitting
of oil
oil in
Checl
.n oilei
illers
s pack
5 for
quired
ng glai
Tight =
filtr;
ns pa<
.e pum
king g.
is whei
ands o
requ.
Repl.
Chec
of si
Repl
of sli
iors (s.
mpres 3ors.
epts
ptic hi
in oile
udge and ser'
ace).
166
-------
Furnace Operator - Operations
Application of Industrial
Engineering Techniques
167
-------
PROJECT TITLE
Application of Industrial
Engineering Techniques
Furnace Operator - Operations
168
-------
SYSTEM
Wastewater Treatment Plant, Flint, Mich.
Incinerators and Associated Equipment
USE OF WORKSHEET Equipment Re-starting Procedures
Furnace Operator after Elec. Power Interruption
PROJECT TITLE Application of I. E.
Techniques to Conventional and
Advanced Wastewater Treatment
Systems
STAGE NO.
PREPARED BY
G. Calnan
SHEET NO.
1
DATE ,
5/12/71
APPROXIMATE
ELAPSED
TIME | '
(MINUTES)
169
-------
SYSTEM Wastewater Treatment Plant, Flint, Mich.
jPrimary Subsystem Clarifier Scum-Sludge Flights
USE OF WORKSHEET Procedures followed by foreman
primary operator when primary tank alarm, sounds
PROJECT TITLE Application of I. E.
Techniques to Conventional and
Advanced Wastewater Treatment
Systems
STAGE NO.
PREPARED BY
G, Calnan
SHEET NO.
1
DATE
4/12/71
TIM
170
-------
.SYSTEM Wastewater Treatment Plant, Flint, Mich.
I Vacuum Filters and Associated Equipment
USE OF WORKSHEET Equipment He-starting Proce-
dures Filter Operator after Elec. PC
Power Interruptio
PROJECT TITLE application at 1. t.
Techniques to Conventional and
Advanced Wastewater Treatment
i Systems
SHEET NO.
AIE12/71
APPROXIMATE
ELAPSED
TIME |
(MINUTES)
171
-------
SYSTEM Wastewater Treatment Plant, Flint, Mich.
Primary Equipment /Final Tank Collectors
USE OF WORKSHEET Equipment re-starting procedures
by primary operator after elec. Power interruption
/ J, ///* ,
APPROXIMATE /»/V~^° /&'/$ /
ELAPSED / £
-------
SYSTEM plint Waste-water Treatment Plant ;
USE OF WORKSHEET Describe operations performed by
primary operator during two-hourly inspections
PROJECT TITLE Application of I. B.
Techniques to Conventional and
Advanced Waste-water Treatment
Systems
STAGE NO. -
PREPARED BY
G. Cahian
SHEEIoN,°2-
DA?/um
APPROXIMATE
ELAPSED
TIME |
(MINUTES)
00
04
05
07
10
11
13
15
18
21
rA
1V
Sample re-
quirements
inspections
instruction
t
JL
0
CL)
[2"!
-jw^-
i
1
Draw
Inspe
Inspe
as" re
Turn
panel
Inspe
Tq G
(2~|
EH
[3
X
[ 2|
[2)
\
plant
:t grit
:t com
quired
on / off
on grc
:t G. E
it Bui]
Inspe c
Inspe*
Inspe c
Inspec
when
Inspe(
To Pi
nfluent
tanks 1
nut or
List*
primal
und flc
moto
ling -
t oper;
t open
sampl
svels a
)perati
n for a
y sludj
or of G
' contr
laseme
tion of
tion of
t Worthington
t F~P
sludge
t propt
se Gall
sludge
lump i;
r oper
*ry Eat
; from
nd all
ms an
Dnorm
e tank
rit Bu
3! pant
Qt
grit pi
tank g
Air C<
low m
runni
ition o
t.
j_
(2J
1
J
one of
Jiff use
cham
il nois
pumps
Lding.
Is and
imps g
-it rerr
impres
;ter an
ig-
prote
Pick i
carry
To Gr
the gr
s for
)ers.
;s. (ra
at pun
Recoi
Tri Ri(
tge (Ibf
oval rr
sor Op
i Ohm;
:tive w
i
p sam
ng rac
t Tank
t tanks
.ormal
lemov
ely r«=
p cont
d on F
:e wate
. pre;
echani
eratior
rt slue
iter pi
JwJ^
I
[2!
1
[T|
1
*&>
[2!
T
^^
]T
|
ile bot
-------
SYSTEM F1.nt Wastewater Treatment Plant
USE .OF WORKSHEET uescriDe operations penormea D^
Primary Operator during two-hourly inspections
PROJECT TITLE
Application of I.E. Techniques
to Conventional and Advanced
Wastewater Treatment Svstems
STAGF NO
PREPARED BY
G. Calnan
SH!EoTf^°-
DA#16/71
174
-------
APPENDIX F
OPERATIONAL/MAINTENANCE TASK MATRICES
SEWAGE TREATMENT PLANT.
FLINT, MICHIGAN
.175
-------
SUBSYSTEM-
. PRIMARY
FUNCTION
INSPECT AND RECORD
Inspect grit tank levels and check air diffusers for
normal operation
Check comminutor operation
Inspect Motor Control Panel
Check influent temperature recorder
Check operation of grit pumps and inspect pressure gage
Check operation of grit removal mechanism
Check operation of air compressor
Check operation of raw sewage pumps
Check operation of mechanical bar screen rake
Check raw sewage flow meter and recorder
Inspect sludge flow meter and sludge density meter
Check operation of protective water pump and inspect
reserve tank
Inspect piping and flanges for leaks
Check operation of sludge pumps
Check operation of scum ejector equipment (tank, valve, and
air compressor)
Check operation of primary effluent pumps and record
inlet and cL,Iet pressures
LOCATION
Grit Tank Area
Comminutor Channel Area
Grit Bldg. - Main Floor
Grit Bldg. - Main Floor
Grit Bldg. - Basement
Grit Bldg. - Basement
Grit Bldg. - Basement
Pumping Station
Grit Bldg. - Basement
Grit Bldg. - Basement
Primary - Pipe Gallery
Primary - Pipe Gallery
Primary - Pipe Gallery
Aeration - Pipe gallery
FREQUENCY
very 2 hours
j
ESTIMATED
TIME
^
34 Minute
SKILL
UTILITIES
OPERATOR
HIGH
MED
LOW
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sheet 1 of 6
-------
SUBSYSTEM.
PRIMARY
FUNCTION
INSPECT AND RECORD - (continued)
Check scum cross collectors
Check primary effluent flow meters
Check scum and other floating items on surface of tank
Inspect operation of flights
Inspect weirs
Observe primary effluent characteristics
Record depth of primary sludge
Record operation time of sludge pumps
Record operation time of grit pumps
SAMPLES
Influent (24 hour composite)
Primary effluent (24 hour composite)
NORMAL OPERATIONS
Start/stop sludge pumps
Bleed water from filter of air compressor
Adjust scum cross collectors
Clean basket screen filters in protected water system
LOCATION
Primary Tank Area
Motor Control Panel
Grit Tank Area
Primary Effluent Channel
Motor Control Panel
Grit Bldg. - Basement
Primary Tank Area
Grit Bldg. - Basement
FREQUENCY
Every 2 hours
Daily
As required
Every 2 hours
Every 2 hours
Every 8 hours
ESTIMATED
TIME
i
~)
6 Minutes
~\
1 NAT*
J
1
^ 3 Minutes
\ 4 Minutes
i
I
2 Minutes
*NAT - No Appreci
SKILL
UTILITIES
OPERATOR
HIGH
ble Ti
MEO
X
X
X
X
ne.
LOW
X
X
X
X
X
X
X
X
X
Sheet 2 of 6
-------
SUBSYSTEM.
PRIMARY
CO
FUNCTION
NORMAL OPERATIONS - (continued)
Start/stop raw sewage pumps
Start/stop mechanical bar screen rake
Remove container of debris from rake and clean-up area
Remove floating objects from comminutor channel
Adjust primary tank sluice gates
Operate scum collector paddle
Free weirs of debris
Start/stop grit screws
Start/stop grit pumps
NON-ROUTINE OPERATIONS
Power Interruption
Restart comminutors
Restart settled sewage- pumps
Restart raw sewage pumps
Restart mechanical Bar Screen Rake
Observe primary effluent characteristics
Observe effluent meters
Observe surface conditions of primary tank
Check operation of comminutors
Inspect all equipment and piping in Grit Bldg.,
Basement, and Primary Pipe Gallery
LOCATION
Pumping Station
Comminutor Channel
Primary Tank Area
Motor Control Panel
Blower Bldg.
Pumping Station
1
Primary Tank Area
Comminutor Channel Area
Grit Bldg. - Basement
FREQUENCY
As required
Average of 4 time
Der year
ESTIMATED
TIME
1
1 Approx.
20 Mins.
| Daily
J
1
I Approx.
[ 12 Mins.
J Daily
> Unknown
j
1
(
I Approx.
f 15 Mins.
J
SKILL
TILITIES
PERATOR
HIGH
MED
X
X
X
X
LOW
X
X
X
X
Sheet 3 of 6
-------
SUBSYSTEM.
PRIMARY
FUNCTION
NON-ROUTINE OPERATIONS - (continued)
Shear Pin on Flights Shears
Silence Shear Pin Alarm
Stop flight gear drive motor
Inspect flights to determine where shear pin
has sheared
Obtain spare shear pin
Start flight gear drive motor and align shear pin
holes in gear wheels
Stop flight gear drive motor
Insert new gear shear pin(s)
Start flight gear drive motors and check for
proper operation
PREVENTIVE MAINTENANCE
Replenish oil in oilers of sludge pumps
Replenish oil in oilers of air compressor
Tighten packing glands of raw sewage pumps
LOCATION
Admin. Bldg. - Meter Room
Primary Tank Area
Primary Tank Area
Grit Bldg. - Main Floor
Primary Tank Area
Grit Bldg. - Basement
Pumping Station
FREQUENCY
Average of 6
times per year
Every 2 hours
or as needed
Every 8 hours
or as needed
As required
ESTIMATED
TIME
-\
^
-
-
> Approx.
12 Mins.
3 Mins.
3 Mins.
2 Mins.
SKILL
UTILITIES
OPERATOR
HIGH
MED
X
X
LOW
X
X
Sheet 4 o 6
-J
CD
-------
SUBSYSTEM-
PRIMARY
CO
o
FUNCTION
PREVENTIVE MAINTENANCE - (continued)
Grease and check oil in comminutors
Check oil in gear case of flight gear drives
Check oil level in oiler of screen ejectors
Check oil, packing and clean strainers of sludge pumps
Check oil level and drain water from air compressors
Check oil, packing, and clean strainers of grit pumps
Grease and check grit screw mechanism
Check protected water system
Check venturi meter
Check swing fuser joints
Check shear pins on flight drive gears
Check effluent meters
Grease and check raw sewage pumps
Check oil level and check operation of bar screen rake
mechanism
Lubricate grit screw drive
Clean strainer and belt on grit pump
Clean and test air compressor
LOCATION
Comminutor Channel Area
Primary Tank Area
Primary Pipe Gallery
Grit Bldg. - Basement
Primary Tank Area
Pumping Station
Grit Bldg. - Basement
FREQUENCY
Weekly
Monthly
ESTIMATED
TIME
^
->
^
'
* 4 Hours
p
SKILL
1AINTENANCE
ECHANIC
HIGH
MED
LOW
Sheet 5 of 6
-------
SUBSYSTEM
FUNCTION
PREVENTIVE MAINTENANCE - (continued)
Clean strainers and belts of sludge pump<
Clean air filter and oil scum ejectors
Lubr.icate flight drive mechanisms
Check operation of comminutors
Clean motor control panels
Check, clean and adjust meters and recorders
Check, lubricate, clean and adjust motors:
Raw Sewage Pumps
Mechanical Bar Screen Rake
Sludge Pumps
Air Compressors
Fl ight Gear Drive
Comminutors
Grit Pump
Grit Screw
LOCATION
Grit Bldg. - Basement
Primary - Pipe Gallery
Comminutor Channel Area
Grit Bldg. - Main Floor
Grit Bldg. , Primary
Tank Area, Pumping
Station
FREQUENCY
Monthly
Monthly
ESTIMATED
TIME
*
f
X 5 Hours
j
-,
I
f
1
^ 4 Hours
,,-
SKILL
MAINTENANCE
MECHANIC
HIGH
MED
LOft
MAINTENANCE
ELECTRICIAN
oo
Sheet 6 of 6
-------
SUBSYSTEM ACTIVATED SLUDGE
00
CO
FUNCTION
INSPECT AND RECORD
Record following meter readings:
Total raw sewage rate (MGD)
Settled sewage to aeration tanks
Return sludge to aeration tanks
Record weather data
Check operation of return sludge pumps
Check operation of waste sludge pumps
Inspect equipment & piping in pipe gallery for abnormal
noise or leaks
Check operation of high pressure final effluent pumps and
record inlet and outlet pressures
Check level of primary effluent on depthmeter
Inspect protected water system
Check volume of blower air on recorder
Check operation of instrument air compressors
Check operation of travelling water screens
Check surface conditions and operation of final clarifier
Inspect blower operation and record following for each
operating blower:
Exciter bearing temp.
Drive and bearing temp.
LOCATION
Admin. Bldg. -Meter Room
Admin. Bldg. Area
Pipe Gallery
"
Pipe Gallery
Blower Bldg. - Basement
Aeration Tank Area
Final Clarifier Area
Blower Bldg.
FREQUENCY
Hourly
Every 2 hours
ESTIMATED
TIME
2 Mins.
' - \
" 51 Mins.
SKILL
ACTIVATED-SLUDGE
OPERATOR
HIGH
MED
X
X
X
X
X
X
X
X
X
X
X
:x
X
LOW
Sheet 1 of 6
-------
SUBSYSTEM.
ACTIVATED SLUDGE
FUNCTION
INSPECT AND RECORD - (continued)
Highest tbermo temp.
D. C. amps
Air temp and pressure
Bearing temps, (each end and center)
Oil pressure
Oil inlet and outlet temps.
AC amps.
Internal guide vane setting
Kilowatts
SAMPLES
Suspended solids -- mixed liquor
BOD -- mixed liquor
Suspended solids final effluent
BOD final effluent
Dissolved oxygen -- mixed liquor
Dissolved oxygen -- final effluent
Dissolved oxygen'-- river
BOD & suspended' solids -- return sludge
NORMAL OPERATIONS
Adjust controls on console to regulate return sludge to
aeration tanks
LOCATION
Aeration Tanks
Final Effluent Channel
Aeration Tanks
Final Effluent Channel
River
Aeration Bldg.
Admin. Bldg. - Meter Rm.
FREQUENCY
Every 2 hours
Every 4 hours
1
Hourly or as
required
ESTIMATED
TIME
I
1
\
;> 15 Mins.
i
1
J
~\
1
--
s 10 Mins.
3 Mins.
SKILL
ACTIVATED-SLUDGE
OPERATOR
HIGH
X
MED
LOW
X '
X
X
X
X
X
X
X
CO
oo
Sheet 2 of 6
-------
SUBSYSTEM ACTIVATED SLUDGE
00
FUNCTION
NORMAL OPERATIONS (continued)
Perform laboratory analysis for suspended solids
Bleed moisture from instrument air compressor and
H.P air compressor
Perform laboratory analysis for dissolved oxygen
Clean basket screen filters in protected water system
Start/stop pumps (waste sludge, return sludge,
protected water, effluent, mixed liquor, etc.)
Open/close valves
Open/close sluice gates
Clear final clarifiers of surface scum
Start/stop blowers
Adjust blower vane settings
NON-ROUTINE OPERATIONS
Power Interruption
Stop stand-by blower and restart in-service blower
Check blower motor gages for proper readings
Re-energize following units:
Primary effluent pumps
Travelling water screens
LOCATION
Aeration Bldg. - Lab
Blower Bldg. - Basement
Aeration Bldg. - Lab
Blower Bldg. - Basement
Pipe Gallery
Pipe Gallery
Mixed Liquor Channel
Final clarifier
Blower Bldg.
ii
Aeration Bldg. -Control
Panel
FREQUENCY
Every 2 hours
Every 4 hours
Every 8 hours
As required
Average of 4
times per
year
ESTIMATED
TIME
I 30 Mins.
5 Mins.
2 Mins.
~^
Comprises
an aver-
f- age of
I 15 mins.
every 8
hours
i
', 15 Mins.
*
SKILL
ACTIVATED - SLUDGE
OPERATOR
HIGH
X
X
X
X
X
MED
X
X.
LOW
X
X
X
X
Sheet 3 of 6
-------
SIIRSYSTFM flfTTVATFn SI IIHRF
FUNCTION
NON-ROUTINE OPERATIONS - Power interruption (continued)
H.P, final effluent pumps
Spray water pumps
Return sludge pumps
Waste sludge pumps
Protected water pumps
Instrument air compressor
Check air flow meter for proper reading
Visually check operation of above units
PREVENTIVE MAINTENANCE
Adjust packing glands on all pumps (spray water, return
sludge, waste sludge, and effluent)
Check and clean instrument air filters in control
consoles
Clean strainers and check oil level of blowers
Check oil level in blower motors
Clean and replenish oil in air dryer
Check oil level and drain moisture from instrument
air compressor and H.P. air compressor
Check packing glands on all pumps, adjust as
necessary (spray water, return sludge, waste
sludge and effluent)
Clean strainers in pressure reducing valves of return
sludge and waste sludge pumps
Check oil lev"! in oiler of scum ejector
LOCATION
Aeration Bldg. -Control Pane
n n n n
it
Blower Bldg. - Basement
M n n
Admin. Bldg. - Meter Room
Blower Bldg.
- Basement
Pipe Gallery
FREQUENCY
i
-
L
As required
Weekly
ESTIMATED
TIME
2 Mins.
1
V 6 Hours
\
SKILL
ACTIVATED - SLUDGE
OPERATOR
HIGH
MED
X
LOW
MAINTENANCE
MECHANIC
00
Cn
Sheet 4 of 6
-------
SUBSYSTEM ACTIVATED SLUDGE
oo
05
FUNCTION
PREVENTIVE MAINTENANCE (continued)
Lubricate and check oil level of gear mechanism of
final clarifiers
Blow down travelling water screen controllers
Swing diffuser joints, replace diffusers and clean
diffuser
Exchange moisture traps in consoles and clean
Clean screens and moisture traps in blowers
Clean, test safety valves and replace air cleaners
of instrument air compressor and H.P. air
compressor
Check operation of protected water system
Clean, check packing, lubricate and adjust belts of
pumps (effluent, waste sludge, return sludge,
spray water)
Clean scum ejectors
Lubricate, check oil level and adjust travelling
water screens
Lubricate and check operation of final clarifier
mechanism
LOCATION
Final Clarifiers
Aeration Tank Area
Admin. Bldg. -Meter Room
Blower Bldg.
Blower Bldg. - Basement
Pipe Gallery
Aeration Tank Area
Final Clarifier
FREQUENCY
Weekly
Monthly
ESTIMATED
TIME
I
j
J
^ 2 Hours
SKILL
MAINTENANCE
MECHANIC
HIGH
MED
LOW
Sheet 5 of 6
-------
SUBSYSTEM.
ACTIVATED SLUDGE
FUNCTION
PREVENTIVE MAINTENANCE - (continued)
- Clean motor control panels
- Check, lubricate, clean and adjust following motors:
Blowers
Instrument air compressors
H.P. air compressors
Effluent pumps
Spray water pumps
Return sludge pumps
Waste sludge pumps
Travelling water screen
- Check, clean, adjust meters and recorders of control
consoles. Replenish ink in recorder needles
LOCATION
Blower Bldg.
Admin. Bldg. -Meter Room
FREQUENCY
Monthly
Quarterly
ESTIMATED
TIME
\
/ 5 Hours
J'
1 1/2 Hrs
SKILL
MAINTENANCE
ELECTRICIAN
HIGH
MED
LOW
O3
Sheey 6 of 6
-------
SUBSYSTEM.
TRTfKI TNR FTI TFR
CO
CO
FUNCTION
INSPECT AND RECORD
Record settled sewage flow to T. F. (MGD)
Check operation of settled sewage pumps
Check operation of filter spray nozzles
Check surface conditions and operation of final clarifiers
Check operation of humus sludge pumps
SAMPLES
Suspended solids final effluent
BOD -- final effluent
Dissolved oxygen -- final effluent
NORMAL OPERATIONS
Perform laboratory analysis for dissolved oxygen
Start/stop humus sludge pumps
Open/close valves
Start/stop protected water pumps
Start/stop settled sewage pumps
Replace filter spray nozzles and clean nozzles
Clear final clarifiers of surface scum
LOCATION
Admin. Bldg. -Meter Room
Blower Bldg. - Basement
Filter Field
Final Clarifier
T. F. Bldg.
Final Effluent Channel
T. F. Bldg.
II 11
Blower Bldg.
Filter Field
Final clarifiers
FREQUENCY
Hourly
Every 2 hours
Every 4 hours
Every 4 hours
As required
ESTIMATED
TIME
NAT*
L 4 Mins.
_/
| 3 Mins.
2 Mins.
10 Mins.
"*! Comprises
I an aver-
[ age of
2 hours
daily
*NAT = No Appreci
SKILL
TILITIES
OPERATOR
HIGH
X
ble T
MED
X
X
X
X
X
le.
LOW
X
X
X
X
X
Sheet 1 of 2
-------
TRICKLING FILTER
FUNCTION
PREVENTIVE MAINTENANCE
Adjust packing glands on pumps
Inspect, replace and clean filter spray nozzles
Inspect filter bed
Check, lubricate, and adjust packing glands and belt
of humus sludge pump
Check operation of protected water system
Check, lubricate final settling tank mechanism
Clean motor control panels
Check, lubricate, clean and adjust motors:
Final Clarifiers
Humus Sludge Pumps
Protected Water Pumps
Settled Sewage Pumps
LOCATION
T. F. Bldg.
Blower Bldg. - Basement
Filter Field
T. F. Bldg.
Final Clarifiers
T. F. Bldg.
Blower Bldg.
FREQUENCY
As required
Weekly
Monthly
ESTIMATED
TIME
-
2 Mins.
~1 Approx.
} 20 Mins.
-i
1
(
J
" 1/2 Hr.
1 1/4 Hrs.
SKILL
UTILITIES
OPERATOR
HIGH
MED
X
LOW
MAINTENANCE
MECHANIC
MAINTENANCE
ELECTRICIAN
00
CD
Sheet 2 of 2
-------
SUBSYSTEM AIR FLOTATION
CD
O
FUNCTION
INSPECT AND RECORD
Check motor control panel for proper settings
Check operation of instrument air compressor
Check sludge flow meter
Check operation of flotation air compressor
Check operation of grit removal pumps
Check operation of sludge pumps
Check operation of protected water system
Check sludge characteristics at input end of
thickening tanks
Check characteristics of sludge on surface of
thickening tanks
Inspect operation of flights
Check characteristics of subnatant
Inspect magnetrol switches
SAMPLES
Thickened sludge (24 hour composite)
Thickener subnatant (24 hour composite)
LOCATION
Thickener Bldg.
Thickener Bldg. -Basement
Thickener Tanks
"
Thickener Bldg. -Basement
Thickener Tanks
FREQUENCY
Every 2 hours
Every 8 hours
Every 2 hours
ESTIMATED
TIME
->,
> 9 Mins.
NAT*
\ 3 Mins.
*NAT -.No. Appreci
SKILL
SLUDGE-CONTROL
OPERATOR
HIGH
jle Ti
MED
X
X
X
X
X
X
X
X
X
X
le.
LOW
X
X
Sheet 1 of 5
-------
SUBSYSTEM AIR FLOTATION
FUNCTION
NORMAL OPERATIONS
Bleed moisture from air compressors
Adjust automatic settings on time clocks for grit
flights, sludge skimmer, sludge screw, and
grit screw
Flush out magnetrol switch cylinders on air
pressure tanks
Clean basket screen filters in protected water system
Alternate protected water pumps
Alternate air compressors
Start/stop pumps (grit, thickened sludge)
Open/close valves
NON-ROUTINE OPERATIONS
Power Interruption
Restart air compressors (instrument and
flotation)
PREVENTIVE MAINTENANCE
Replenish oil in oilers of sludge pumps
Replenish oil in oilers of air compressors
Tighten packing glands of pumps (grit, sludge)
Replace shear pins on flights and skimmers
LOCATION
Thickener Bldg.
Thickener Bldg. -Basement
Motor Control Panel
Thickener Bldg. -Basement
"
Thickener Bldg.
Thickener Bldg. -Basement
Thickener Tanks
FREQUENCY
Every 2 hours
Every 8 hours
Daily
As required
Average 4 times
per year
As required
"
11
"
ESTIMATED
TIME
1
> 5 Mins.
f 12 Mins.
J
2 Mins.
1 Comprises 12
? Mins. Daily
2 Mins.
v
> 8 Mins.
SKILL
SLUDGE-CONTROL
OPERATOR
HIGH
MED
X
X
X
X
X
X
X
X
X-
LOW
CD
Sheet 2 of 5
-------
SUBSYSTEM-
FLOTATION
CD
1X3
1
FUNCTION
PREVENTIVE MAINTENANCE (continued)
Check, lubricate, adjust belt, clean filters, and
blow moisture of air compressor
Check, lubricate and tighten packing gland of grit
screw mechanisms
Check, lubricate and tighten packing y:o,nc; of grit
pumps
Check oil level, adjust packing gl.-'K1:. ?:nd
lubricate flight and skimmer ire,.hamsms
Check oil level, adjust packing nlar-ds and
lubricate sludge pumps
Clean and check operation of magnetrol switch units
Clean "lint; of venturi meter?
Check, lubricate, adjust belt, clean filters, and
blow moisture of instrument air compressor
Check oil level, adjust packing glands, and
lubricate protected water pumps
Check operation; replace shear pins, lubricate and
adjust tension of skimmers
Lubricate drivc chain and check oil level of grit
screw mechanism
Clean strainer of grit pump
LOCATION
Thickener Bldg. -Basement
t;
Thickener Bldg.
Thickener Tanks
Thickener Bldg. -Basement
FREQUENCY
Weekly
Monthly
ESTIMATED
TIME
"^
^
1
> 4 Hours
i
SKILL
MAINTENANCE
MECHANIC
HIGH
MED
LOW
Sheet 3 of 5
-------
SUBSYSTEM.
AIR FLOTATION
FUNCTION
PREVENTIVE MAINTENANCE (continued)
Clean and test safety valves of flotation air
compressor
Check and replace filters and clean air dryer
water trap of instrument air system
Clean strainers of sludge pumps
Lubricate and check oil level of flight mechanisms
(bottom collectors)
Clean and test safety valves of instrument
air compressors
Check oil level and lubricate drive units of skimmers
Check oil level of sludge screw drive
Lubricate screw drive chain
Check lubrication of skimmer hangers
Clean motor control panel
Check, clean, and adjust meters
Check, lubricate, clean, and adjust motors:
Skimmer
Flights (bottom collector)
Thickened sludge pump
LOCATION
Thickener Bldg. -Basement
Thickener Bldg.
Thickener Tanks
Thickener Bldg.
Thickener Bldg. -Basement
Thickener Tank Area
FREQUENCY
Monthly
t
ESTIMATED
TIME
1
'
-v
\
\
f 2 Hours
>- 4 hours
i
SKILL
MAINTENANCE
MECHANIC
HIGH
MED
LOW
MAINTENANCE
ELECTRICIAN
CD
GO
Sheet 4 of 5
-------
SUBSYSTEM.
AIR FLOTATION
CD
FUNCTION
PREVENTIVE MAINTENANCE (continued)
Grit screw
Grit pump
Instrument air compressor
Flotation air compressor
Protected water pumps
LOCATION
FREQUENCY
ESTIMATED
TIME
SKILL
AINTENANCE
LECTRICIAN
HIGH
MED
LOW
Sheet 5 of 5
-------
SUBSYSTEM-
DEWATERING SYSTEM
FUNCTION
INSPECT AND RECORD
Check sludge tank agitator air compressor and check
level of oil in oilers
Observes scrapers in vacuum filter to ensure filter cake
is being removed correctly
Inspect FECLj day tank and record depth level and flow
rate
Check sludge in filter sump
Check oil level in vacuum pumps
Inspect consistency of filter cake
Inspect filter coil spray water
Record total tonnage of filter cake and tons per hour
Record seal water pressure on filters
Record filter vacuum gage readings
Inspect lime feeder equipment and record register,
pounds/hour, pressure, torque, grit water flow rate
and spray water flow rate
Inspect Sludge Pumps
Check level of oil in oilers of sludge pumps
Records register reading on sludge pumps
Check packing glands of filtrate pumps
LOCATION
Sludge Pump Area
Vacuum Filter Area
FECL3 Day Tank Area
Vacuum Filter Area
Vacuum Pump Area
Vacuum Filter Area
Vacuum Filter Area
Conveyor Belt Area
Vacuum Filter Area
Vacuum Filter Area
Lime Slaker Area
Sludge Pump Area
Sludge Pump Area
Sludge Pump Area
Filtrate Pump Area
FREQUENCY
Hourly
Hourly
Hourly
Hourly
Hourly
tourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
ESTIMATED
TIME
-v
23 Minutes
SKILL
SLUDGE-FILTRATION
OPERATOR
HIGH
MED
X
X
X
X
X
LOW
X
X
X
X
X
X
X
X
X
X
CD
cn
Sheet 1 of 6
-------
SUBSYSTFM DEWATERING SYSTEM
CD
FUNCTION
INSPECT AND RECORD (continued)
Record motor setting of lime pumps
Check level of oil in oilers for filter chains
Check level of lime in lime storage tank
Record drum settings on filters
Record chemical conditioning tank settings
SAMPLES
Filtrate (24 hour composite)
Sludge (24 hour composite)
FECLo sample for specific gravity test
NORMAL OPERATIONS
Lubricate sludge pump plungers
Transfer lime from storage tank to slakers
Perform specific gravity test of FECLj
LOCATION
Lime Slaker Area
Vacuum Filter Area
Lime Storage Tank Area
Vacuum Filter Area
Chem. Cond. Tank Area,
Vacuum Pump Area
Sludge Pump Area
FECL3 Day Tank Area
Sludge Pump Area
Lime Storage Tank Area
Filter Laboratory
FREQUENCY
tourly
ivery 8 hours
Daily
When changed
dhen changed
ivery 2 hours
Every 4 hours
iach time tank is
filled and
jeginning of each
shift
ivery 2 hours
ivery 8 hours
ESTIMATED
TIME
J
NAT*
4 Minutes
I NAT*
3 Minutes
2 Minutes
4 Minutes
\ 8 Minutes
">
'NAT = No Apprecia
SKILL
SLUDGE-FILTRATION
OPERATOR
HIGH
le Ti
MED
X
LOW
X
X
X
X
X
X
X
X
X
X
Sheet 2 of 6
-------
SUBSYSTEM.
DEWATERING SYSTEM
FUNCTION
NORMAL OPERATIONS (continued)
Fill FECU Day Tank
0
Bleed water from filter of Sludge Tank
Agitator air compressor
Prepare Daily Filtration Pumpage and Chemical Feed Log
Energize and de-energize vacuum filter agitators
Adjust filter coil spray water
Adjust drum speed of vacuum filter
Start, stop and regulate sludge pumps
Start, stop and regulate FECL, pumps
Start, stop and regulate lime slurry pumps
NON-ROUTINE OPERATIONS
Power Interruption
Re-energize following equipment in sequence:
Lighting Panel
Lime Slurry Agitator
Lime Slurry Pump
FECL3 Feeder Pump
Sludge Tank Agitation Air Compressor
Filtrate Pump
Vacuum Filter Drum
Conditioning Tank
LOCATION
rECL3 Day Tank Area
Sludge Pump Area
Filter Laboratory
Vacuum Filter Area
Vacuum Filter Area
Vacuum Filter Area
Sludge Pump Area
FECL3 Tank Area
Lime Slurry Tank Area
Motor Control Panel
" " "
1
1
FREQUENCY
Every 8 hours
Every 8 hours
Daily (Midnight)
As requ i i ed
As requited
As required
As required
As required
As required
Average of 4 times
per year
ESTIMATED
TIME
A
1
> 33 Minutes
J
-/
30 Minutes
-*v
Comprises an
\ average of
16 minutes
every 4 hrs.
j
-,
> 30 Minutes
1 '
SKILL
SLUDGE-FILTRATION
OPERATOR
HI6H
MED
X
X
X
X
X
X
X
X
LOW
X
CD
Sheet 3 of G
-------
SUBSYSTEM-
DEWATERING SYSTEM
CD
CO
FUNCTION
NON-ROUTINE OPERATIONS (continued)
Power Interruption (continued)
Lime Slaker Grit Conveyor
Lime Slaker
Lime Feeder
Exhaust Fans
Check operation of above equipment and adjust according
Conveyor Pulley Stoppage
De-energize following equipment in sequence:
Filter drums
Conveyors
Conveyor alarm
Sludge pumps
FECL3 feeder pumps
Lime slurry pump
Lime conveyor
Lime feeder
Lime slaker paddle
Lime slaker grit conveyor
Conditioning tank
Filtrate pump
Assist Furnace Operator in corrective action and
then energize following equipment in sequence:
Conveyors
Filter drums
Remainder of equipment in reverse order as
shown above.
LOCATION
Motor Control Panel
ii ii ii
y-
Motor Control Panel
n ii M
11
1
r
FREQUENCY
Average of 8 times
i year
ESTIMATED
TIME
^
-'
»
i
Comprises an
average of
» 50 minutes
operator
time.
SKILL
SLUDGE-FILTRATION
OPERATOR
HIGH
MEO
X
X
LOW
STTeet 4 of 6
-------
SUBSYSTEM DEWATERING SYSTEM
FUNCTION
PREVENTIVE MAINTENANCE
Replenish oil in oilers of sludge pumps
Replenish oil in oilers of sludge tank agitator
air compressor
Grease vacuum filter zerk fittings
Grease lime slurry pump zerk fittings
Replenish oil in vacuum pump
Replenish oil in oilers for filter chains
Tighten packing glands of filtrate pumps
Check, lubricate and adjust lime conveying system
Check, lubricate and adjust lime slakers'
Check and lubricate lime slurry pumps
Check and lubricate FEC1-3 solution pumps
Lubricate FECI_3 Transfer Pump
Check, lubricate and align vacuum filters
Lubricate chemical conditioning drums
Check, lubricate and adjust vacuum pumps
Check, lubricate and adjust filtrate pumps
LOCATION
Sludge Pump Area
Sludge Pump Area
Vacuum Filter Area
Slurry Pump Area
Vacuum Pump Area
Vacuum Filter Area
Filtrate Pump Area
Lime Storage Tank Area
Lime Slaker Area
Lime Slurry Tank Area
FECL3 Day Tank Area
FECL3 Day Tank Area
Vacuum Filter Area
Vacuum Filter Area
Vacuum Filter Area
Vacuum Filter Area
FREQUENCY
Every 2 hours or
as needed
Every 8 hours or
as needed
Daily
Daily
As Required
As Required
As Required
Weekly
Weekly
Weekly
Weekly
Weekly
ESTIMATED
TIME
3 Minutes
3 Minutes
| 4 Minutes
^
I
>
\
> 5 Minutes
(Daily)
> 5 1/2 Mrs.
SKILL
SLUDGE-FILTRATION
OPERATOR
HIGH
MED
X
LOW
X
X
X
X
MAINTENANCE
MECHANIC
CD
CO
Sheet 5 of 6
-------
SUBSYSTEM.
DEWATERING SYSTEM
CO
o
o
FUNCTION
PREVENTIVE MAINTENANCE (continued)
Check, lubricate and align belt conveyors
Lubricate weightometer
Check, lubricate and adjust sludge well air
compressor
Check, lubricate and adjust sludge pumps
Clean coils of vacuum filters
Flush piping (sludge, filtrate, lime slurry)
Clean Motor Control Panels
Check, lubricate, clean and adjust following Motors:
Sludge Pump
Sludge Tank Agitator Air Compressor
Lime Feeder
Lime Slaker
Lime Slurry Pump
Lime Slurry Agitator
FECLj Pump
Chemical Conditioning Mixer
Vacuum Filter
Belt Conveyor
Spray Water Pump
Filtrate Pump
Vacuum Pump
LOCATION
Belt Conveyor Area
Sludge Pump Area
Vacuum Filter Area
Control Panel Area
Sludge Pump Area
n ii n
Lime Storage Area
Lime Slaker Area
Lime Slurry Tank Area
Lime Slurry Tank Area
FECL3 Tank Area
Vacuum Filter Area
Vacuum Filter Area
Belt Conveyor Area
Vacuum Pump Area
II 11 II
II
FREQUENCY
Weekly
As Required
As Required
lonthly
Monthly
ESTIMATED
TIME
4
!
*r
5 1/2 Mrs.
2 Weeks
(every 4
months)
1 Hour
(every
month)
N
6 Hours
SKILL
4AINTENANCE
ECHANIC
HIGH
MED
LOW
MAINTENANCE
ELECTRICIAN
Sheet 6 of 6
-------
SUBSYSTEM.
ANAEROBIC DIGESTER
FUNCTION
INSPECT AND RECORD
Check meters and position of controls of motor control
panel
Check level of sludge in digester tanks
Check temperature gage and control settings of heat
exchangers
Check operation of recirculation pumps of heat
exchanger
Check operation of protected water system
Check level of supernatant
Check operation of sludge pumps
Inspect valves and piping for leakage
SAMPLES
None
NORMAL OPERATIONS
Start/stop sludge pumps
Alternate protected water pumps
Open/close valves
Adjusts heat exchanger
Transfer sludge
LOCATION
Digester Bldg.
"'
Digester Bldg. - Basement
Motor Control Panel
Digester Bldg. - Basement
Digester Bldg.
FREQUENCY
Every 2 hours
Daily
As required
ii
ESTIMATED
TIME
-N
->
* 9 Mins.
> 3 Mins.
1 Approx.
> . 15 Mins.
Every 8
_J Hours
SKILL
SLUDGE-CONTROL
OPERATOR
HIGH
MED
LOW
Sheet 1 of 3
-------
SUBSYSTEM ANAEROBIC DIGESTER
to
O
(SO
FUNCTION
NON-ROUTINE
Power Interruption
Check operation of following equipment:
Recirculating Pumps
Protected Water Pumps
Heat Exchangers
Sludge Pumps
Restart above equipment if necessary
Plugged Piping
Open/close valves to isolate plugged line and
reroute sludge or liquid being transferred.
Start/stop pumps
Remove flanges or sections of piping as necessary
to gain access to plugged sections.
Flush or rod-out plugged line.
LOCATION
Digester Bldg.
Digester Bldg. -Basement
FREQUENCY
Average 4 times
per year
Average of 15
occurrences per
year
ESTIMATED
TIME
N
^4 Mins.
J
V
Average of
19 1/2 hrs.
each occur-
rence. In-
>- volves main-
1 tenance
personnel in
addition to
operator
SKILL
LUDGE-CONTROL
OPERATOR
HIGH
MED
X
X
X
X
X
LOW
Sheet 2 of 3
-------
SUBSYSTEM-
ANAEROBIC DIGESTER
O
CO
FUNCTION
PREVENTIVE MAINTENANCE
Replenish oil in oilers of sludge pumps
Tighten packing glands of pumps (sludge,
protected water, recirculating)
Check oil level, adjust packing glands, and
lubricate sludge pumps
Check oil level, adjust packing glands, and
lubricate protected water pumps
Check oil level, adjust packing glands, and
lubricate recirculating pumps
Clean strainer of sludge pump
Clean motor control panels
Check, lubricate, clean and adjust following motors:
Sludge pumps
Recirculating pumps
Protected water pumps
Check, clean and adjust meters
LOCATION
Digester Bldg. - Basement
Digester Bldg.
Digester Bldg. - Basement
Digester Bldg.
FREQUENCY
As required
As required
Weekly
Monthly
Quarterly
ESTIMATED
TIME
~s
^
v
> 6 Mins.
> 45 Mins.
5 Mins.
1 Hour
1 Hour
SKILL
SLUDGE-CONTROL
OPERATOR
HIGH
MED
X
X
LOW
MAINTENANCE
MECHANIC
MAINTENANCE
ELECTRICIAN
Sheet 3 of 3
-------
INCINERATION AND ASH DISPOSAL
to
o
FUNCTION
INSPECT AND RECORD
Record following data for all operating furnaces:
Temperature - Hearths 1 through 5
Temperature - Scrubbers, in and out
Temperature - Cooling air
Flow Rate - Furnace draft
Flow Rate - Gas
Record burner settings
Record filter cake accumulative reading and calculate
tons/hour, recording same.
Check furnace flame in operating furnaces
Check furnace shaft oilers
Record water pressure to scrubber precoolers
Check conveyor belt
Record water supply pressure to scrubbers
Check ash hearths
Record pressure of ash hopper agitators
Check service air compressor and check level of oil in
oilers.
LOCATION
Furnace Control Station
Furnace - Main Floor
Weightometer Area
Furnace - Main Floor
Furnace - Upper Level
Furnace - Upper Level
Furnace - Upper Level
Furnace - Main Floor
Furnace - Basement
Furnace - Basement
Furnace - Basement
FREQUENCY
Hourly
Hourly
ESTIMATED
TIME
-v
> 16 Minutes
1
SKILL
INCINERATOR
OPERATOR
HIGH
MED
LOW
X
X
X
X
X
X.
X
X
X
X
X
Sheet 1 of 5
-------
SIIRSVSTFM INCINERATION AND ASH DISPOSAL
to
O
cn-
FUNCTION
INSPECT AND RECORD (continued)
Check ash slurry pumps (belts & glands)
Check agitator pump
Check scrubber pump
Check spray water pump
Record induced draft limit switch temperature
Record amperage of induced blower fans
Check furnace drive shear pins
Check ash chute
Record spray wash pressure to induced draft blowers
Measures calgon solution level and records
Record reading on gas meter
SAMPLES
Filter Cake (8 hour composite)
NORMAL OPERATIONS
Bleed water from filter of service air compressor
Clean basket screen filters in protected water system
Clean basket strainers for scrubber pumps
LOCATION
Furnace - Basement
Furnace - Basement
Furnace - Basement
Furnace - Basement
Furnace - Upper Level
Motor Control Panel
Furnace - Basement
Furnace - Basement
Furnace - Basement
Furnace - Basement
Gas Meter Building
Conveyor Belt Area
Furnace - Basement
Furnace - Basement
Furnace - Basement
FREQUENCY
Hourly
Every 4 Hours
Every 4 Hours
Every 4 Hours
Every 4 Hours
Every 8 Hours
Every 8 hours
Daily
Hourly
Every 2 Hours
Every 8 Hours
Every 48 Hours
ESTIMATED
TIME
1
^
>
_ *"
"
1
^. 3 Minutes
1
> 3 Minutes
6 Minutes
2 Minutes
1 Minute
2 Minutes
2 Minutes
SKILL
INCINERATOR
OPERATOR
HIGH
MED
LOW
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sheet 2 of 5
-------
SIIRSYSTFM INCINERATION AND ASH DISPOSAL
to
O
FUNCTION
NORMAL OPERATIONS (continued)
Ignites additional burners or turns burners off
Adjust burners
NUN-ROUTINE OPERATIONS
Power Interruption
Re-energize following equipment in sequence:
Protected water system
Sludge conveyors
Scrubber water pumps
Filter agitator pump
Cool ing Fans
Turbo blowers
Furnace drives
Induced draft fans
Ash hopper pump
Spray water pump
Energize maxon safety shut-off valve and relight burners
Check operation of above equipment and adjust accordingly
LOCATION
Furnace - Main Floor
Furnace - Main Floor
Motor Control Panel
Furnace - Main Floor
FREQUENCY
As Required
As Required
Average of 4
times per year
ESTIMATED
TIME
}
Comprises
an av-
erage of
12 mins.
every 4
hrs.
> 8 Minutes
SKILL
INCINERATOR
OPERATOR
HIGH
MED
X
X
X
LOW
Sheet 3 of 5
-------
SUBSYSTEM
INCINERATION AND ASH DISPOSAL
FUNCTION
Conveyor Pulley Stoppage
Inspect conveyor for cause of stoppage
Perform corrective action
Shovel filter cake onto conveyor and clean up area
Check operation of conveyor after re-energized by
Filter Operator
PREVENTIVE MAINTENANCE
Fill oil reservoir of furnace shaft oilers
Grease exhaust fan bearings on scrubber
Check and lubricate scrubber damper
Check furnace shaft cooling air fans and grease
bearings and adjust drive belt if necessary
Inspect furnace drives, lubricate, and check drive
belts, adjust as necessary
Check oil level of furnace bottom bearing, replenish
if necessary
Inspect combustion air turbo blower
Check and lubricate ash hopper make-up water valve
LOCATION
Conveyor area
Furnace - Upper Level
Furnace - Upper Level
Furnace - Upper Level
Furnace - Basement
Furnace - Basement
Furnace - Basement
Furnace - Basement
Furnace - Basement
FREQUENCY
Average of 8
times a year
Every 4 Hours
or as Required
Daily
Weekly
Weekly
Weekly
Weekly
Weekly
Weekly
ESTIMATED
TIME
Comprises an
average of 50
Mins. Operator
Time
'
3 Minutes
2 Minutes
2 1/2 Hrs
SKILL
INCINERATOR
OPERATOR
HIGH
MED
X
LOW
X
X
MAINTENANCE
MECHANIC
bhee
t 4 6t b
to
o
-------
SUBSYSTEM INCINERATION AND ASH DISPOSAL
to
O
CO
FUNCTION
PREVENTIVE MAINTENANCE -(continued)
Check ash slurry pumps and replenish oil, adjust belt
and packing if required.
Check, lubricate and adjust service air compressor
Check protected water system
Check city water system
Inspect scrubber and agitator water pumps and
adjust seal if necessary
Clean Motor Control Panels
Check, lubricate, clean and adjust following motors:
Turbo blower Spray water pump
Conveyors Inducer blower fans
Service air compressor Furnace drive
Ash slurry pumps Protected water pumps
Agitator pump
Scrubber pump
Check, clean and adjust meters and recorders of
furnace control panel. Replenish ink in recorder
needles.
LOCATION
Furnace - Basement
Furnace - Basement
Furnace - Basement
Furnace - Basement
Furnace - Basement
Control Panel Area
Furnace Control Station
FREQUENCY
Weekly
Weekly
Weekly
Weekly
Weekly
Monthly
Monthly
Quarterly
ESTIMATED
TIME
I
J
"*"N
-<
* 5 1/2 Mrs.
- 30 Mins.
SKILL
MAINTENANCE
MECHANIC
HIGH
MED
LOW
MAINTENANCE
ELECTRICIAN
Sheet 5 of 5
-------
SUBSYSTEM CHLORINATION
to
o
CD
FUNCTION
INSPECT AND RECORD
Check chlorine room for chlorine odor
Check operation of evaporators and record:
Final effluent flow (MGD)
Chlorine flow rate (Ibs/day)
Residual chlorine (PPM)
Check and record scale weight of chlorine
tank in use
SAMPLES
Chlorine Residual :
Final effluent - activated sludge
Final effluent - Trickling Filter
NORMAL OPERATIONS
Determine chlorine residual - activated sludge
Determine chlorine residual - trickling filter
Adjust chlorine evaporators
Replace chlorine tank and connect tank to system
LOCATION
Chlorine Room
Admin. Bldg. -Meter Room
Chlorine Room
Chlorine garage
A.S. Contact Tank
T.F. Contact Tank
Aeration Bldg. - Lab
Trickling Filter Bldg.-
Lab
Chlorine Room
Chlorine Garage
FREQUENCY
Every 2 Hours
As required
ESTIMATED
TIME
-\
_
]
}
>. 3 Mins.
\
[ 2 Mins.
16 Mins.
12 Mins.
SKILL
UTILITIES
OPERATOR
HIGH
X
X
MED
X
LOW
X
X
X
X
X
Sheet 1 of 2
-------
SUBSYSTEM.
CHLORINATTflN
FUNCTION
NON-ROUTINE OPERATIONS
Power Interruption
Turn off chlorine flow at tank headers
Turn on chlorine flow when H.P. final effluent
pumps are operating
PREVENTIVE MAINTENANCE
Check meters and recorders of following units:
Chlorine residual
Chlorine evaporators
Chlorine gas detector
Chlorine flow
Lubricate chain hoist
LOCATION
Chlorine Garage
Chlorine Garage
" Room
ii
Chlorine Garage
FREQUENCY
Average of 4
times per year
Quarterly
ESTIMATED
TIME
I 1 Min.
1
^. 30 Mins.
3 Mins.
SKILL
UTILITIES
OPERATOR
HIGH
MED
MAINTENANCE
ELECTRICIAN
LOW
X
MAINTENANCE
MECHANIC
Sheet 2 of 2
-------
APPENDIX G
MALFUNCTION LOG
SEWAGE TREATMENT PLANT
FLINT, MICHIGAN
211
-------
CO
I1
CO
Item
No.
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
Date
6/24/71
6/24/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/26/71
6/27/71
6/27/71
6/27/71
6/28/71
6/29/71
6/29/71
6/29/71
6/29/71
6/29/71
6/29/71
6/30/71
6/30/71
6/30/71
6/30/71
7/1/71
Equipment Description
West Scum ejector
#1 Lime pump
#1 Filter
#3 Filtrate
sample line
Raw Sewage Dip Stick
M.L. Dip Stick
#2 Filtrate Seal HgO
gage
Thickened Sludge Meter
Scrubber Press Line
East Furnace inspecion
door
#3 Filtrate pump
#2 Filter
#1 Filter filtrate
#3 Filter
#2 Sludge pump
#3 Sludge pump
East scum ejector
Thickened sludge
Waste sludge meter
#1 Chlorinator
Truck
#4 Conveyor
Brady
Hot water heater
#2 Lime pump & #1
Basket strainer
Equipment
Location
Grit Bldg.
Inc.
Inc.
Inc
Grit
M.L. ChannE
Inc.
Meter Rm.
E Furnace
E Furnace
Inc.
Inc.
Inc.
Inc.
Inc.
Inc.
Grit
Meter
Meter
Cl, Bldg.
Inc. Bldg.
Inc. Bldg.
Inc.
Inc.
Inc.
Work
Order
Written
Yes
Yes
Yes
Yes
Yes
1 Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Problem
Will not shut off
Diaphragm ka-flooey
Filtrate not being taken away
(going up on roof)
Plugged
Needs repair
Needs repair
Not good
Not working
Broken wooden plug stuck in it
Inspection door hinge broken
Needs packing
Remote switch on W. Wall
Filtrate pump not pumping
Time bar needs readjusting
Parking needs adjustment
Parking needs adjustment
Not working properly
Still not working (meter)
Not working
High gas temperature and pressure
Broken left door handle
Holes in conveyor structure
Low level light sticking
Needs a new thermocouple
Diaphragm
Chamber valves not sealing
Work
Order
Received
6/24/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/28/71
6/28/71
6/28/71
6/28/71
6/28/71
6/28/71
6/28/71
6/30/71
6/30/71
6/30/71
6/30/71
6/30/71
6/30/71
7/1/71
7/1/71
7/1/71
7/1/71
7/2/71
Date
Started
6/24/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/28/71
7/1/71
6/28/71
6/28/71
6/28/71
7/1/71
6/29/71
6/30/71
6/30/71
6/30/71
6/30/71
6/30/71
7/6/71
7/2/71
7/1/71
7/1/71
7/1/71
7/2/71
Date
Completed
6/24/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/25/71
6/28/71
7/1/71
6/28/71
6/28/71
6/28/71
7/1/71
6/29/71
6/30/71
6/30/71
6/30/71
6/30/71
6/30/71
7/6/71
7/1/71
7/1/71
7/1/71
EQUIPMENT MALFUNCTIONS SEWAGE TREATMENT PLANT
Sheet Uof 2
-------
SUBSYSTEM: Primary Treatment
ELEMENT: Pumping and Screening
CO
i*
oo
Equipment Description
1100
/Ol Raw sewage mains
/02 Pump station wet
well
/03 Bar screen/rake
/04 Sewage pumps and
motors
14" pumps and
electric motors (2)
12" pump and
electric motor (1)
Quantity
Installed
2
1
1
3
i
/05 Pump motor controls 1
Switching controls
system
/OS Piping and check
valves (with 14"
pumps)
Piping and check
3
valve (with 12" pump)
/07 A. Flow meter and
recorde r
B. Instrument Air
compressors
/10 Plant Influent mains
1
2
1
Failures
0
0
799(F)
1042(F)(4)
1170(F)
119KF)
1246(F)
(2)
768(F)
785(F)
(2)
Best
Foremen's
Est.
1 in 6 years
716(F)
1380(F>
(2)
926(F)
(1)
Best Fore-
men's Est.
during 1 year
period. (1)
Malfunctions
0
0
0
744(M)
863(M)
932(M)
938(M)(b)
1221(M)
1389(M)
754(M)
829(M)m
879(M)( '
1386(M)
870(M)
(1)
(0)
933(M)
939(M)
(2)
0
Operating
Hours
17520
8760
1460
1752
8760
8760
8760
8760
8760
MTBF
-
365.0
8760
4380
52560
4380
8760
8760
MTBM
-
-
_
2920
2190
8760
_
4380
-
FAILURES AND MALFUNCTIONS SUMMARY WORK SHEET
Sheet 2 of 2
-------
APPENDIX H
RELIABILITY AND MAINTAINABILITY DATA
215
-------
(2)
(3)
(4)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13) (14)
(15)
(16)
(17)
////*/ / / // / f / Ai Desien Avera6e /^ ? / /
/ // / , i f, / £ / / i?& / v^ /
Equipment /$'£ / / / ff / * / £ / £* / C$ / $ £ / $ ^ / ^ / / ^ / 3 / * /^^ / ° /
/ Q? $* / ^ / ^ / /^ / / "^ / ^ / ^ ^ / V^ / ^ ^ / £?'$/ i? / ^ C. / Qf₯ / £^~ / ^ /
11100
/Ol
Raw Sewage Mains
/02
Pump Station Wet Well
/03
A - Bar Screen
B - Rake
/04
Sewage Pumps and Motors
/05
Wet well level sensor and
pump motor control system
/06
Piping and check valves
/07
A - Flow Meter and
Recorder
B - Instrument Air
Compressors
/10
Plant Influent Main
/ '
2
1
1
1
3
1
3
1
2
1
7
0
0
0
4
2
2
1/6
2
1
1
0
0
0
0
6
4
1
0
2
0
/ V
17520
8760
8760
1460
17520
8760
8760
8760
8760
8760
-
-
365.0
8760.0
4380.0
52560.0
4380. 0
8760. 0
8760. 0
/ // / / £ / rg g/ *
/ / / / / ^ / V ^
-
-
-
2920.0
2190.0
8760.0
4380.0
1.00
1.00
1.00
0. 17
1.00
1.00
1.00
1.00
1.00
1.00
-
-
-
2147. 1
8760.0
4380.0
52560.0
4380.0
8760.0
8760.0
-
-
-
2920.0
2190.0
8760. 0
-
4380.0
-
0.466
0.133
0.228
0.019
0.228
0. 114
0. 114
2
1
1
1
2
1
2
1
1
1
1.000
1. 000
1. 000
0.715
0.750
0. 849
Incl
0.849
0. 993
0.921
/C? ///^
-
-
-
0.466
0.0004
0. 228
aded with
0. 228
0.007
0. 114
-
-
-
2147. 1
2500.0
4380.0
/04
4380.0
143
8760. 0
///
-
-
-
5
13
1
-
2
5.5
3
/ ^
-
-
-
2.33
0.005
0.228
-
0.456
0.038
0.342
/
Sheet 1 of 2
WASTE WATER TREATMENT PLANT
RELIABILITY AND MAINTAINABILITY DATA
PUMPING AND SCREENING
11100
-------
CALCULATIONS
11100
.111r=Z)X/A1 , = (0.466+0.0004+0.228+0. 228+0. 007+0. 114)xlO"3(from column (14)
11100 /01-" /n
= 1.043xlO"3
MTBF
11100 1.043xlO-3
= 958 Hours
__ « _ _ ______ _ __________________ __ _ _______ _ ___-_--
"3
_ /UJ. ^-,ua. , Vi, ^,^ , iv 'e/10 _ (2. 33+. 005+0.228+0.456+0.038+0. 342)xlO
1V1 Ilrt111/-.ri - >
11100 X,..+X,._+X... 1.043x10-3
(from columns (17) and (14) on Sheet 1 of 2)
3.399xlO~3
1.043xlO"3
= 3.25 Hours
MTBF,
A _ 11100 _ 958 _ 958
11100 MTBF11100+MTTR11100 958+3.25 961.25
= 0<996
WASTE WATER TREATMENT PLANT
MTBF, MTTR, AND AVAILABILITY CALCULATIONS
PUMPING AND SCREENING
11100
(Continued)
Sheet 2 of 2
-------
APPENDIX I
FORMULAS AND APPROXIMATION FORMULAS
FOR CALCULATING THE,..RELIABILITY
OF REDUNDANT RELATIONSHIPS
219
-------
FORMULAS AND APPROXIMATION FORMULAS
FOR CALCULATING THE RELIABILITY
OF REDUNDANT RELATIONSHIPS
Operational Redundancy. Redundant units are operating when a failure to one
or more units occurs. Units remaining, e.g., 1 of 2, are needed to sustain
required system function.
Formula Approximation
Formula
1 of 2
2e - _e
1 of 3
1 of 4
4e
+ . -3U -4U -(At)'
1 of n
n
a=l
2 of 3
3e
-e
-3(\t)
3 of 4
4e
-6(\t)
n-1 of n
ne
-(2)
2 of 4
_2Xt
3 of 5
6e - -I5e
n-2ofn
a=0
(§)e
mof n
m
a=0
-nXt
r m
E
U=i
- (m-l)(Xt)n-m+1
m
/nl L -(n-m)(Xt)
a=m
Sheet 1 of 2
220
-------
Standby Redundancy. A unit is in operation to provide required system funcion.
Kedundant unit (or units) is "standing by" to be turned on should the operating
unit fail.
_(Xt)2
1 of 2 e"Xt+(Xt)e"Xt e 2
-\ + -\ + 1 O li 4- ~\A.t)
1 of 3 e ^+(U)e U+I(U) e U e ~T~
£t
(U)3
1 ofn e"Xt+(Xt)e-Xt+l(Xt)2e'Xt e n!
£i
n-l -\t
(1) Number of each unit which must be working to provide required system
function.
(2) Approximation formulas should only be used when Xt ^ 0. 200
/o\ /nv n! _ n- n-1- n-2- 1
a a! (n-a)! a- a-1- l(n-a- n-a-1- 1)
Sheet 2 of 2
221
-------
APPENDIX J
AWT FUNCTIONAL STAGING DIAGRAMS
223
-------
Remove Dissolved
Inorganic Material
Receive Wastes
From Previous
Steps
CO
DO
Remove Dissolved
Inorganic Material
From Wastes
15420
Convey Wastes
From Previous
Steps
15411
NOTES:
Several approaches could be selected, including:
reverse osmosis, electrodialysis, ion exchange,
distillation, and freezing
Could include: dispersion, lagoons, evaporation,
and deep well disposal
Dispose of
Concentrated
Inorganic Wastes
Sample &
Analyze
Effluent
15426
Collect Treated
Wastes &
Convey to Next
Treatment Step
15427
SAMPLE FUNCTIONAL STAGING DIAGRAM FOR
ADVANCED WASTE TREATMENT
(sheet 1 of 3)
-------
SAMPLE
SOUTH TAHOE PUDLIC UTILITY DISTRICT
WATER RENOVATION PLANT
MONTHLY SUMMARY
OF
FLOW AND LABORATORY DATA
FOR
FLOW DATA
Total Plant Flow for Month, MG
Average Daily Plant Flow for Month, MGD
Peak Flow Rate for Month, MGD
Total Flow for Month Into Indian Creek Res. MG
Total Flow for Month From Indian Creek Res . MG
Total Flow for Month From Pipeline Outlets, MG
WATER QUALITY DATA
Description
MBAS, mg/1, less than
BOD, mg/1, less than
COD, mg/1, less than
SUSD. S. mg/1, less than
Turbidity JU,
Phosphorus, mg/1 less than
pH, units
Coliform, MPN/100 ml
Requirements
Alpine Co.
0.5
5
30
2
5
No
6.5 to 8.5
Adequately
Disinfected
Lahontan R.W.Q.C.B.
per cent of time
50
Requiren
80
0.5
5
25
2
5
tents
100
1.0
10
50
4
10
6.5 to 9.0
Median less than 2
Max. No. Consecutive
Samples
23, 2
greater than
Plant
Performance
per cent of time
50
80
100
Median
No. of
Consecutive
Samples greater than
23,
(sheet 2 of 3)
225
-------
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M T W T
r s s J D » M
Q SA A I J F M
DAYS OF WEEK FREQUENCY
A MJ JASONDjl? 3
MONTH SHIFT
INSPECTION AND SERVICE RECORD
Equipment Settled oewage Channel File No. Ok!-uo^y
Item
1
2
Work
To Be Done
i/asJi Down Channel 9
Remove & Reset all Slide G-ates.
Ref.
Freq.
D
Q
Time
&3SWnN 31IJ
> t i i
0 I t t JS
0 L £ > I JS
0 1 £ f i JS
0 1 1 t I 41
:£
re
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SPECIAL
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-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
r't tfo,
w
APPLICATION OF SELECTED INDUSTRIAL
ENGINEERING TECHNIQUES TO WASTE WATER
TREATMENT PLANTS
Waller, R., Dr.
Mallory, C. W.
Hittman Associates, Inc.
9190 Red Branch Road
Columbia, Maryland
-12. ,
13., Type tjiZReptfrt"^,; ,S'-|^|
. '' Psifotl Covered' '-^ 'i^JIffl
" , :
Environmental Protection Agency report
number. EPA-R2-73-176. February
d
1. _
A study was performed to evaluate the applicability of various industrial
engineering techniques to operation and maintenance of secondary waste treatment
plants. Numerous techniques used in military and industrial projects were evaluated
and applied in a case study at the Flint, Michigan, waste treatment plant using actual
plant data, practices, and procedures. Emphasis was placed on Work Study and
Reliability and Maintainability analysis.
The evaluations indicated that a variety of techniques were directly and beneficially
applicable to the development of rational management programs for design, operation,
maintenance, staffing, and quality control. An overall approach to develop complete
management programs was developed whereby designers or managers could start from
effluent goals and rationally develop designs, O&M procedures, and staffing levels as
well as increase plant reliability. Quality control programs are hampered by: poor
parameters for measuring effluent quality and process control; lack of knowledge of
causes of variability of plant effluent quality as well as the nonsteady state effects of
equipment failures; the prevailing practices for setting quality goals, collecting and
evaluating performance data; and current practices for enforcement of performance
requirements by regulatory agencies.
A number of recommendations were offered to develop programs for upgrading waste-
water plant management.
17a. Descriptors
*Water Quality Control, Wastewater Treatment, Operation and Maintenance,
Reliability, Personnel Management
17b. Identifiers
*Flint, Michigan, Industrial Engineering, Work Study, Reliability and
Maintainability Evaluation, Reliability and Maintainability Prediction
05G
' iS. $t';-utiiy C^ss.
' (Jkepo'rt)'
20. Security Cfass- ''
, ;- (Pitge) . , ,.
'21. ::K-j,:of-
Pages
22. 'Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTFB
U.S. DEPARTMENT OF THE INTERIOR " ' "-"" <-tNTER
WASHINGTON, D. C. 2O24O
Charles W. Mallory
Hittman Associates, Inc.
------- |