N-/EPA
United States
Environmental Protection
Agency
Municipal Environmental Research1
Laboratory "
Cincinnati OH 45268
Research and Development
EPA-600/S2-82-050 August 1982
Project Summary
Evaluation and
Documentation of the Effects of
Operation and Maintenance
Practices on the Performance of
Selected Biological Treatment
Plants
Albert C. Gray, Jr., Paul E. Paul, and Hugh D. Roberts
Recognizing the significance of the
noncompliance problem and the inef-
fectiveness of the current federal
enforcement programs, the Office of
Research and Development, U.S. Envi-
ronmental Protection Agency (EPA),
undertook a comprehensive national
study of publicly owned municipal
treatment plants in 1975. This study
was to identify and quantify the
specific causes of inadequate perform-
ance and to formulate recommenda-
tions for improvement. Corollary
objectives of the study were to identify
future research needs and to demon-
strate methods of improved perform-
ance.
The full report deals with the second
phase of the two-part study; the
findings of the first phase were pub-
lished in EPA reports 600/2-79-078
and 600/2-79-034. Conclusions and
recommendations of the second phase
were based on comprehensive evalu-
ations conducted at 23 treatment
facilities. Of 70 potential problem
areas evaluated, the 10 highest ranked,
based on frequency of occurrence and
severity of impact, were operator
application of concepts and testing to
process control, sludge wasting and
return, process control testing, pro-
cess controllability, technical guidance
for process control adjustments, in-
dustrial loading, sewage treatment
understanding, adequacy of O&M
manual, training, and infiltration/
inflow.
In a critical evaluation of the data, it
was noted that at each treatment
facility a combination of factors limit-
ing performance was always observed
and that a single cause of poor per-
formance at any one facility was never
observed. Because there is an interrela-
tionship between performance limiting
factors and corrective programs, and
because most existing correction pro-
grams focus on single problems only,
a new approach that addresses all
problems at a single facility was devel-
oped as more effective in improving
existing plant performance. This ap-
proach is called a Composite Correc-
tion Program {CCP). The purpose of
the CCP is to eliminate all the per-
formance limiting factors at a plant
through the implementation of the
correction recommendations that are
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made as a part of the comprehensive
evaluation.
This Project Summary was devel-
oped by EPA's Municipal Environmen-
tal Research Laboratory, Cincinnati,
OH. to announce key findings of the
research project that is fully documented
in a separate report of the same title
(see*Project Report ordering informa-
tion at back).
Introduction
Significant potential exists for improv-
ing the performance of biological treat-
ment systems simply and inexpensively
by upgrading operation and mainte-
nance programs, improving attention to
management and administrative require-
ments, and by making low-cost correc-
tion of design deficiencies.
In this research effort to identify and
quantify specific cause and effect rela-
tionships in problems of performance,
operation, and maintenance of biologial
wastewater treatment plants, data from
selected operating plants were collected
and analyzed. The purpose was to
identify deficiencies that caused poor
plant performance; to weigh and rank,
in order of severity of impact, the
causative factors of poor performance at
each facility; and to demonstrate on a
limited basis the improvement in plant
performance that can be achieved with-
out major capital improvement when all
limiting factors are corrected.
Selection of Plants
The 69 plants selected for study met
the following selection screening cri-
teria:
1. Plants must incorporate a biologi-
cal treatment process as the basic
method of wastewater treatment.
2. Plants should have a history of
inadequate performance as meas-
ured by effluent quality.
3. Though not restrictive, hydraulic
capacities of plants should range
from 1 to 5 mgd.
4. Plants should not be hydraulically
or organically overloaded to any
great extent.
5. No enforcement action should be
underway against the municipality
or authority involved, nor should
the municipality be in the process
of designing or constructing phys-
ical modifications in the treatment
facility.
During site visits to each plant, various
preliminary data were compiled: process
schematics, wastewater characteristics,
staffing, laboratory capabilities, permit
requirements, and maintenance activ-
ities. Through interviews, information
was solicited from the plant staff relative
to specific problems interfering with
plant performance.
Site Visit Results
Observations resulting from the site
visits are based on a wide data base with
limited depth of detail.
1. Most plants were constructed or
upgraded since 1965. As such,
age of the facility or equipment
was rarely cited as a problem.
2. Preliminary treatment processes
were provided at 70 percent of the
plants. More than 75 percent of
the facilities were equipped with a
primary treatment stage. Only
about 15 percent of the plants,
however, included a form of ter-
tiary treatment.
3. One-third of the plants reported
major problems resulting from
infiltration/inflow, primarily those
associated with periodic hydraulic
overloads of plant units and "wash-
out" of suspended growth biolog-
ical systems. Dilution of waste-
water strength and resulting upset
of the biological process was also
a consequence of this problem.
4. Approximately 35 percent of the
plants were faced with moderate
to severe problems concerning
industrial wastewater discharges.
Specifically, intermittent or slug
organic loads from industry caused
process upsets.
5. Most plants were staffed 40 to 60
hours per week. The extent of shift
coverage appears to be proportion-
al to the size of the facility.
6. Staff training at a majority of the
plants was believed to be adequate
on the basis of discussions with
the plant operators.
7. Morethan85 percent of theplants
reported minimal or no downtime
as a result of inadequate main-
tenance. An adequate on-hand
supply of spare parts was reported
in only about one-third of the
plants, although parts were usual-
ly readily available from local
suppliers.
On the basis of the site visits, 23
plants were selected for more compre-
hensive study to examine, in detail, the
system and unit process performance
and to evaluate existing operation,
maintenance, and administrative prac-
tices. In all, 70 potential problem areas
were addressed at each facility including
plant and unit process performance,
design adequacy, operation and main-
tenance practices, and administrative
policies.
To quantify and report the deficiencies
and problems at plant sites, both indi-
vidually and collectively, a plant evalu-
ation summary was developed, consis-
ting of a weighing scale and a ranking
table. The scale was devised to rank the
70 different factors that could limit plant
performance. For each factor identified
at a facility, the extent to which it
adversely affected plant performance
was quantified according to the weigh-
ing scale points. The factors affecting
plant peformance were then ranked in
decreasing order of severity.
Causes of Poor Plant
Performance
The 10 most significant problems for
the 23 plants are listed in decreasing
order of severity:
1. Operator application of concepts
and testing to process control
2. Sludge wasting and return
3. Process control testing
4. Process controllability
5. Technical guidance for process
control adjustments
6. Industrial loading
7. Sewage treatment understanding
8. O&M manual adequacy
9. Training
10. Infiltration/inflow
The predominant factor adversely
impacting plant performance is the lack
of application of process control tech-
niques. A partial cause of this situation
appears to be the inability of the oper-
ators to relate generalized classroom
training to their specific facility. Another
reason is that the operators are not
always willing to accept the merits of
process control and, as a result, down-
play the need for process monitoring. In
many cases, the lack of a comprehensive
O&M manual was determined to be a
major deficiency contributing to the
process control problem and limiting thjA
operator's ability to respond to "troubleVI
situations, such as process upsets.
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Plant design problems, such as inade-
quate provision for process controllabil-
ity or flexibility and sludge handling
limitations, hamper the efforts of the
operators to practice effective process
control. External factors, including in-
dustrial loading and infiltration/inflow,
also adversely affect performance.
For the most part, maintenance prac-
tices at the 23 plants were satisfactory.
Supervisory operators seemed to give
first priority to keeping the plant equip-
ment operating and maintaining good
housekeeping practices; biological pro-
cess control and optimizing plant per-
formance as measured by effluent
quality received secondary consider-
ation.
With respect to administrative pol-
icies, two areas were examined in
detail—staffing and budgeting. Approx-
imately one-third of the preliminary
evaluation plants were staffed at a level
at least 25 percent less than that
recommended in EPA's staffing guide-
lines. Examination of the O&M budgets
indicates that a majority of the plants
were allocated funds in excess of the
average expeditures at a representative
sampling of similar plants in their
respective geographical areas. There-
fore, budgets were not believed to be a
major direct constraint on plant per-
formance.
Improving Plant Performance
Through a Composite
Correction Program
An evaluation of data indicates that a
combination of factors limited perform-
ance and that a single cause of poor
performance at any one facility was
never observed. Because there is an
interrelationship between performance-
limiting factors and corrective programs
and because most existing correction
programs focus on single problems
only, a new approach that addresses all
.problems at a single facility is proposed
"as a more effective approach in im-
proving existing plant performance. The
purpose of this approach (a CCP) is to
eliminate all the performance-limiting
factors, at a plant by implementing the
correction recommendations made in
the comprehensive evaluation report.
As a part of each evaluation, specific
recommendations were made for im-
proving plant performance chiefly
^through nonstructural modifications
"such as training, process monitoring
and control, O&M manual preparation.
staffing, and budgeting for plant opera-
tions. The actual, long-term impact of
implementing these recommendations
is not known. On the basis of engi-
neering judgment, however, attainable
effluent wastewater quality at each
plant was estimated. On the basis of
these estimates, compliance with
NPDES permit limitations by the plants
would improve from 55 to 86 percent for
BODs and from 64 to 95 percent for
suspended solids, solely as a result of
implementing the recommended opera-
tional improvements.
A final and important conclusion of
this study relates to the cost effective-
ness of implementing a CCP to improve
operation and maintenance and, there-
by, upgrade plant performance. Based
on estimates of costs associated with
implementing comprehensive evalua-
tion recommendations at three typical
facilities, initial-year costs could be
expected to range from approximately
$10,000 to $50,000 and annual recur-
ring costs would range from $2,000 to
$ 10,000. These cost estimates are given
only to illustrate the order of magnitude
of costs associated with a CCP. Each
case will be unique in its scope and
required expenditures.
Considering the benefits of improved
plant efficiency and better effluent
quality to be gained, the costs of a CCP
appear justifiable when compared with
the total investment already made in
construction and operation of these
treatment plants. A CCP is also a cost
effective way to attain quality effluent
by optimizing operations rather than
achieving permit compliance through
other means such as costly construction
or adding capital equipment. In fact,
court imposed fines for noncompliance
would most likely exceed the entire cost
of a CCP.
Conclusions and
Recommendations
The following conclusions and specific
recommendations are made as a result
of this study:
1. Because operator training pro-
grams and manuals appear to have
minimal impact on ensuring
proper plant operation, federal and
state training programs and liter-
ature should be redeveloped to
relate theoretical consideration to
practical operational situations
and to present solutions to specific
on-site problems as they arise.
Manuals must reflect the input of
the plant operations staff and
should be easy to follow so they
will be used on a day-to-day basis.
2. At the facility planning and design
stages, plant design, operability,
and flexibility should be subject to
a specific design and O&M review
as a grant-funding requirement.
Such a review would serve to:
a. emphasize the need for ade-
quate sludge handling in small
plants and design, operation,
and management of existing
facilities at large plants;
b. ensure proper design of second-
ary clarifiers to eliminate short
circuiting and ensure uniform
velocity gradients in the sludge
blanket;
c. implement more rational design
requirements for fixed-film
biological reactors;
d. allow and encourage separate
treatment of anaerobic digester
supernatant or require the size
of the wastewater treatment
process unit to be increased
to adequately receive and treat
this recycle flow;
e. encourage plant flexibility—this
would allow by-passing of
ponds following mechanical
plants and activated sludge
plants to operate in various
modes; and
f. emphasize good controllability
of return activated sludge flows.
3. To ensure that process control is
practiced at treatment facilities,
the following action should be
taken.
a. Improvetrainingforprivateand
governmental persons who pro-
vide technical operating assis-
tance. Training must include
on-site process control experi-
ence at various wastewater
treatment facilities so the in-
structor can properly apply
wastewater treatment concepts
to process control. Plant design
engineers should be trained in
plant operations and process
control.
b. Provide operators with compre-
hensive and understandable
process control information in
the plant operation and main-
tenance manual; this manual,
in turn, should reference other
manuals that would augment
and clarify theory, as necessary.
« U.S GOVERNMENT PRINTING OFFICE-1912 -559-017/0753
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c. Hold persons who provide tech-
nical guidance on operations
accountable for their recom-
mendations. As a minimum,
these people should use follow-
up phone calls or plant visits
to determine if the recommen-
dations given are satisfactory
and still apply.
4. Studies to determine the sources
of plant performance problems
should be comprehensive so that
subtle as well as obvious factors
that limit performance are identi-
fied. Plant administrators should
become familiar with the CCP
approach to improving plant per-
formance as an alternative to
making major plant modifications.
5. Federal and state regulatory efforts
should be directed toward enforce-
ment and accountability, specifi-
cally to:
a. Expand enforcement of Nation-
al Pollutant Discharge Elimina-
tion System permits to encour-
age optimum performance from
existing facilities.
b. Require that CCP's be imple-
mented before planning con-
struction of new or modified
facilities to ensure that existing
facilities' capabilities have been
examined and optimized.
6. Budgeting for operation and main-
tenance of wastewater treatment
facilities must be made needs-
sensitive. The municipal budget
must place a high priority on the
dollar needs of wastewater treat-
ment.
The full report was submitted under
Contract No. 68-03-2571 by Gannett
Fleming Corddry and Carpenter under
the sponsorship of the U.S. Environmen-
tal Protection Agency.
Albert C. Gray, Jr.. Paul E. Paul, and Hugh D. Roberts are with Gannett Fleming
Corddry and Carpenter, Inc., Harrisburg, PA 17105.
Francis L. Evans, III, is the EPA Project Officer (see below).
The complete report, entitled "Evaluation and Documentation of the Effects of
Operation and Maintenance Practices on the Performance of Selected Bio-
logical Treatment Plants," (Order No. PB 82-227 513; Cost: $10.50, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
cf'
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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