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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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