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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460
51985
CF
WATER
MEMORANDUM
SUBJECTS Local Limits Requirements for POTW
'Pnetreatment Programs
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addition, or alternatively, the POTW may develop specific
limi-fes" for each individual facility and incorporate these
limits in the facility's municipally-issued permit or
contract. By translating the regulations' general
prohibitions into specific limits for Industrial Users,
the POTW will ensure that the users are 'given a clear
standard to which they are to conform. "
The categorical pretreatment standards, applicable to broad
classes of industries, are technology-based minimum requirements
which do not necessarily address all industrial discharge problems
which might occur at a given POTW. To prevent these site-specific
problems, each POTW must assess all of its industrial discharges
and employ sound technical procedures to develop defensible Local
limits which will assure that the POTW, its personnel, and the
environment are adequately protected. This memorandum clarifies
EPA's minimum requirements for the development of local limits
to control the discharges of industrial users and discusses the
application of those requirements to POTWs in different stages of
local pretreatment program development and implementation.
II. Minimum Requirements for Local Limits
The General Pretreatment Regulations require every POTW
developing a pretreatment program to conduct an industrial waste
survey to locate and identify all industrial users which might be
subject to the POTW pretreatment program. This procedure is a
prerequisite to pretreatment program approval. In addition, the
POTW must determine the character and volume of pollutants contri-
buted to the POTW by these industrial users. Based on the infor-
mation obtained from the industrial waste survey and other sources,
including influent, effluent and sludge sampling, the POTW must
determine which of these pollutants (if any) have a reasonable
potential for pass-through, interference or sludge contamination.
For each of these pollutants of concern, the POTW roust determine,
using the best information available, the maximum loading which
can be accepted by the treatment facility without the occurrence
of pass-through, interference or sludge contamination. A proce-
dure for performing this analysis is provided in the Guidance
Manual for POTW Pretreatment Program Development. As a minimum,
each POTW must conduct this technical evaluation to determine
the maximum allowable treatment plant headworks (influent)
loading for. the following pollutants:
cadmium . lead
chromium nickel
copper zinc
These six toxic metals are listed because of their widespread
occurrence in POTW influents and effluents in concentrations that
warrant concern. Also, since they are usually associated with
the suspended solids in the waste stream, their presence often
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prohibits the beneficial reuse of municipal sewage sludge and
reduces POTtf options for safe sludge disposal. In addition,
based on site-specific information, the POTW and/or the Approval
Authority must identify other pollutants of concern which might
reasonably be expected to be discharged to the POTW in quantities
which could pass through or interfere with the POTW, contaminate
the sludge, or jeopardize POTW worker health or safety. Once
maximum allowable headworks loadings are determined for each of
the pollutants of concern, the POTW must implement a system of
local limits to assure that these loadings will not be exceeded.
The POTW may choose to implement its local limits in any of a
number of ways, such as uniform maximum allowable concentrations
applied to all significant industrial dischargers, or maximum
mass discharge limits on certain major dischargers. The method
of control is the option of the POTW, so long as the method
selected accomplishes the required objectives. There is no
single method of setting local limits which is best in all
situations. The Guidance Manual for POTW Pretreatment Program
Development discusses several alternative methods which a POTW
might use to allocate the acceptable pollutant load to industrial
users. The manual also provides an example of the calculations
a typical POTW would use to determine the maximum allowable
headworks loadings for a pollutant and to allocate that load to
significant industrial users. POTWs are strongly encouraged to
apply a safety factor to the calculated maximum allowable loadings
and to reserve some capacity for industrial expansion when setting
local limits.
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•*** Some POTWs may find that loading levels of at least some of
the pollutants of concern are far below the calculated maximum
allowable headworks loadings. In these cases, the POTW should
continue to monitor all industrial users discharging significant
quantities of these pollutants. It may also be appropriate for
the POTW to limit, each significant industrial user to a maximum
loading which cannot be exceeded without POTW approval. This
process of limiting increases in discharges of pollutants of
concern provides POTWs with a control mechanism without imposing
unnecessarily stringent limits on industries which expand or
change production processes. Industries approaching their limits
could petition the POTW for an increased allowance. Upon receipt
of such request, the POTW would update its headworks loading
analysis to determine the effect of the proposed increase. The
analysis would enable the POTW to make a sound technical decision
on the request.
Because they are based on the specific requirements of the
POTW, sound local limits can significantly enhance the enforce-
ability of a POTW's local pretreatment program. A POTW that
proposes to rely solely upon the application of the specific
prohibitions listed in §403.5(b) and categorical pretreatment
standards in lieu of numerical local limits should demonstrate
in its program submission that (1) it has determined the
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capability of the treatment facility to accept the industrial
pollutants "of concern, (2) it has adequate resources and proce-
dures for monitoring and enforcing compliance with these require
ments, and (3) full compliance with the applicable categorical
standards will meet the objectives of the pretreatment program.
III. Application of the Minimum Local Limits Requirement
A. Unapproved Programs
POTWs required to develop pretreatment programs must
comply with the regulatory local limits requirements described
above. However, EPA recognizes that there has been a need for
clarification of these requirements and that some Approval
Authorities have not applied this requirement in accordance
with the principles in this memorandum when approving local
pretreatment programs in the past. Some POTWs with local
programs now under development or review were given direction
by their Approval Authority that may have failed to reflect all
of the requirements for local limits that are discussed herein.
Withholding approval for these POTWs until they have adopted
all necessary local limits would delay availability of the
considerable local POTW resources needed to enforce categorical
pretreatment standards and other pretreatment requirements.
Therefore, where POTWs have not previously been advised of the
need to complete the analysis described herein and to adopt
,-5. local limits "prior to program approval, and where imposing
such a requirement would make approval by September 30, 1985
"^ infeasible, POTW pretreatment program submissions meeting all
other regulatory requirements may be approved. However, in any
such case, the POTW permit must be modified to require that the
POTW expeditiously determine the maximum allowable headworks
loading for all pollutants of concern as described above. and
adopt those local limits required to prevent pass-through,
interference, and sludge contamination. To ensure that this
condition is enforceable, the Approval Authority must assure
that this requirement is promptly incorporated into the POTW's
NPDES permit and require that the appropriate local limits be
adopted as soon as possible, but in no case later than one
year after approval. Noncompliance with this permit require-
ment on the part of the POTW will be considered grounds for
bringing an enforcement action for failure to implement a
required pretreatment program.
B. Approved Programs
If any POTW program has already been approved without the
analysis of the impact of the pollutants of concern and adoption
of local limits, the Approval Authority should immediately require
the POTW to initiate an analysis as described above and adopt
appropriate local limits. This requirement should be incorporated
in the POTW's NPDES permit as soon as feasible. Where a POTW has
previously adopted local limits but has not demonstrated that
those limits are based on sound technical analysis, the Approval
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Authority should require the POTW to demonstrate that the local
limits are sufficiently stringent to protect against pass-through,
interference and sludge contamination. POTWs which cannot
demonstrate that their limits provide adequate protection should
be required to revise those limits within a specific time set
forth in a^perrait modification.
IV. LocaJ^ Limits to Control Additional Toxic Pollutants
To date, where POTWs have evaluated their industrial
discharges and adopted local limits as needed based on that
evaluation, the pollutants most often controlled are toxic metals,
cyanide and phenol. Few POTWs now control the discharge of
toxic organic compounds through local limits. Recent studies,
including the Agency's Complex Effluent Toxicity Testing Program,
indicate that these substances are often responsible for toxicity
problems in receiving streams. Furthermore, many of the volatile
organic compounds in POTW influents may be released to the atmos-
phere during conveyance or treatment, potentially causing health
or safety hazards or aggravating air quality problems. Compounds
causing these problems are not necessarily among those in the
statutory list of 126 priority toxic pollutants and may not be
addressed by existing or proposed categorical standards. If
monitoring efforts are not sufficiently comprehensive, these
adverse impacts may go undiscovered, or their root causes may
not be identified.
After a POTW's pretreatment program has been approved,
Approval Authorities should continue to evaluate each POTW to
determine the need for additional measures to control toxic
discharges from industrial users. This is in keeping with the
Agency's policy on water quality-based permit limits for toxic
pollutants (49 FR 9016, March 9, 1984). Utilizing the authority .
provided by Section 308 of the Clean Water Act (or comparable
State authority), the Approval Authority should consider requiring
both chemical-specific and biological testing of POTW influent,
effluent and sludge to evaluate the need for additional local
limits. Where test results indicate a need for greater industrial
user control, POTWs should be required to determine the sources
of the toxic discharges through additional testing and to adopt
appropriate local limits which will prevent interference and
pass-through.
Not every POTW required to have a local pretreatment program
will need to perform this additional testing, but since toxic
chemicals are utilized by many non-categorical industries, this
requirement should not be limited to those POTWs with large
contributions from categorical industries. For example, there
is at least one documented instance of an FDA-approved food addi-
tive, discharged by a food processor to a POTW, causing receiving
stream toxicity problems. OWEP has been working closely with
EPA researchers and will provide whatever assistance we can to
Approval Authorities faced with complex toxicity problems
associated with POTW discharges.
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V. Local Limits Requirements for POTWs covered by §403.10(e);
State-run Pretreatment Programs
In accordance with §403.10(e) of the General Pratreatment
Regulations, some States have assumed responsibility for imple-
menting State-wide pretreatment programs in lieu of requiring
POTWs to develop individual local programs. In these States,
the NPDES permits of POTWs which otherwise would have been
required to develop local pretreatment programs may need to be
modified to require the local limits development procedures
described above. Alternativelyf the State can perform the
required analyses and implement the appropriate local limits
necessary to assure that the goals of the program are achieved.
These limits would then be enforced in the same manner as other
pretreatment requirements, in accordance with procedures included
in the approved State-run program. Where States assume POTW
responsibility for carrying out pretreatment program requirements,
Regional Offices must monitor all aspects of the State-run
pretreatment program, including local limits, to assure that the
national program requirements are met.
VI. Control of Conventional Pollutants
Although the National Pretreatment Program is usually
associated with the control of toxic industrial wastes, the
discharge of excessive conventional pollutants has been the most
commonly documented industry-related cause of POTW effluent limit
violations. Generally, POTWs are required to construct, operate
and maintain their own treatment facilities at efficiencies ade-
quate to prevent pass-through and interference from conventional
pollutants. However, where a POTW chooses instead to limit its
influent or where limits on the influent concentrations are
necessary to assure that unexpectedly high influent concentrations
do not occur, the POTW pretreatment program submission should
demonstrate that local limits adequately address conventional
pollutant loadings from industry. Most POTWs have already deter-
mined the capacity of their treatment facilities to accommodate
conventional pollutants. Where local limits for these pollutants
are needed, the limit-setting process is rather straightforward.
At a minimum, Approval Authorities should encourage all POTWs
to consider setting appropriate local limits on conventional
pollutants in order to prevent pass-through and interference
where problems have occurred in the past or can be anticipated
in the future due to local growth or increases in industry
discharges.
VII. .Deadline for Industrial User Compliance with Local Limits
POTWs adopting local limits should require industrial users
to comply with those limits as soon as is reasonable, but in no
case more than three years from the date of adoption. Where an
industrial user is allowed more than one year to comply, the POTW
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should evaluate the industrial user's operation and set interim
limits to minimize discharge of the pollutants of concern prior
to full compliance with the local limit. The POTW should also
establish enforceable increments of progress for industrial users
with compliance schedules longer than one year and require the
users to submit incremental progress reports at least annually
to assure proper tracking of actions needed to accomplish
compliance.
Where an industrial discharge has been identified as a
contributing factor in a POTW's violation of an NPDES permit
limit, water quality standard, or other environmental require-
ment, the POTW must take immediate enforcement action, employing
all means necessary to assure that the Industrial User is brought
into compliance in the shortest possible time.
VIII. Conclusion
This memorandum has summarized the Agency's minimum
requirements for the establishment of local limits by POTWs
implementing pretreatment programs. Because local limits
address site-specific needs, Approval Authorities should apply
these requirements with sensitivity to local conditions, recog-
nizing that the diversity among POTWs requires a case-by-case
consideration of local limits. Tn many cases, there will be a
clear need to aggressively attack toxicity or interference
problems with extensive analysis and local regulation. In
others, only a few local limits will be needed, if only to
insure that present loadings do not increase. This flexibility,
however, does not mean that local limits are optional under the
National Pretreatment Program. All POTWs implementing pretreat-
ment programs must evaluate the need for local limits. Where
the evaluation so indicates, the POTW must promptly adopt and
enforce local limits which will protect against interference,
pass-through and sludge contamination.
As EPA and State permit writers establish more comprehensive
water quality-based municipal permit limits (including toxics),
POTWs will have more definitive information available as a basis
for establishing the need for and the stringency of local limits
to prevent pass-through. Similarly, the forthcoming sludge
disposal and reuse regulations should enable States to establish
more comprehensive sludge quality requirements, which will in turn
provide a solid technical basis for local limits to prevent
sludge contamination. The Office of Water Enforcement and Permits
is also working with the Agency's Office of Research and Develop-
ment to obtain better information on the impact of toxic substances
on municipal treatment processes. These efforts are proceeding
as fast as available resources permit and should produce results,
in the form of guidance documents, in FY 86.
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Although these activities will help POTWs refine local
limits in the future, adequate information is available today
to proceed* with the specific local limits requirements set
forth in this memorandum. The Agency has recently developed a
computer program, PRELIM, which is intended to greatly reduce
the time required to calculate the maximum allowable headworks
loading. The program also calculates industrial user limits
using a number of optional allocation methods, using data
provided by the POTW. The program is designed for use by POTW
personnel but can also be used by Approval Authorities to verify
the adequacy of POTW local limits. OWE? is now scheduling PRELIM
training workshops for Approval Authority personnel, who can, in
turn, train POTW personnel in its use. Additional information
on PRELIM will be distributed in the near future.
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