ing program has to be established for the injec-
(1) Upgrading of poorly operated facilities.
One of the most common reasons for poor plant
(b) Compatibility of the wastewater with
performance is poor operation. The operating
the water in the injection zone must be studied
techniques applied in a plant should always be
carefully. The reaction between wastewater con-
considered as the first step in upgrading a
system. In order to verify performance, optimiza-
tion of operations should be completed before any
tion of gases both of which could render the
other upgrading technique is applied. Specific
strata impermeable. Organic material in the
operating problems are listed and briefly dis-
cussed in the U.S. EPA survey quoted in para-
growth and rapid plugging of the aquifer pores.
graph 5-5a. These and other problems may be
categorized into the three basic problem areas
5-5. Upgrading of existing facilities
Improper application of process control
Upgrading existing wastewater treatment sys-
tems refers to a variety of design and operational
Inadequate training or guidance of plant
techniques intended to improve plant performance
or increase plant capacity. Upgrading of existing
Improper testing and data analyses.
plants may be desirable for one or several of the
(2) Upgrading poorly designed facilities.
Many plants have sizing or process design defi-
To improve performance of facilities with
ciencies relating to hydraulic or organic overload-
operational deficiencies, i.e., those facilities
ing problems. Many design problems also result
which have poor performance due to difficul-
in poor performance. These were listed in the U.S.
ties in operation of the systems.
EPA survey for five of the top 10 ranked plant
To improve performance of facilities with
problems. Major design deficiencies include:
design deficiencies, i.e., facilities displaying
--Insufficient flexibility in pumping rates,
poor performance due to inadequacy of de-
preventing proper control of plant pro-
cesses in times of high or low flow.
--To increase hydraulic capacity to alleviate
Inadequate by-passes for repair and
hydraulic overloads from infiltration and ex-
maintenance of equipment, resulting in
pansion of services.
entire processes being taken out of ser-
--To increase organic capacity compensating
for organic overload due to the number of
Lack of standby equipment, causing pos-
connections or high strength contributions.
sible loss of process operation while re-
To provide compliance with more stringent
placements are ordered.
--Poor hydraulic and solids distribution to
a. Plant performance. A national survey was
p a r a l l e l u n i t s resu l t i n g in over or
conducted by the U.S. EPA in 103 wastewater
underloading of different portions of the
treatment plants to identify and rank the major
causes of poor plant performance. The survey
Lack of flexibility in process instrumenta-
excluded plants with hydraulic or organic over-
tion and equipment resulting in poor low
loading problems. Table 5-4 lists the top 10
flow or low load operation.
ranked problem areas and provides a short expla-
--Poor accessibility of equipment for repair
nation of each. The survey results indicate that
and maintenance often resulting in repair
operation and design are often the two most
problems and negligent maintenance prac-
important areas to consider when upgrading an
tices. The remedies for most of these
problems are obvious. Correction of these
b. Upgrading techniques. Methods or tech-
deficiencies may result in sufficient im-
niques used in upgrading are entirely dependent
provement of plant performance to elimi-
upon the problems to be solved by the upgrading.
nate the need for further upgrading.
Often, several problems are involved; therefore,
several techniques must be employed in a manner
(3) Upgrading to provide increased hydraulic
to provide the level of performance required. For
capacity. Although units based on flow rates are
simplicity of discussion, the various approaches
operable when hydraulically overloaded, the re-
will be addressed separately with the understand-
moval efficiencies are greatly reduced. Some of
ing that combined use is encouraged where neces-
t h e units most adversely affected by hydraulic