The findings of a recent study conducted by EPA indicate that discharge of CERCLA wastewater to a POTW can
be a feasible and effective part of a Superfund response action, and that currently, the option of discharging to a
POTW is under-utilized. This guide provides quick reference to the statutory, policy, administrative, and technical
factors involved in discharging aqueous wastes generated during Superfund response actions to a POTW. Additional
guidance on evaluating the use of POTWs can be found in three documents "CERCLA Site Discharges to POTWs--
Guidance Manual" (EPA/540/G-90/005, August 1990), "Treatability Manual" (EPA/540/2-90/007, August 1990), and
"CERCLA Sue Sampling Program Detailed Data Report" (EPA/540/2-90/008, August 1990)

United States Office of

A9ency Emergency Response March 1991
SEPA
Guide to Discharging CERCLA
Aqueous Wastes to Publicly
Owned Treatment Works (POTWs)
Office of Emergency and Remedial Response
Hazardous Site Control Division 0S-220W Quick Reference Fact Sheet
The discharge of aqueous wastes to a publicly-owned
treatment works (POTW) as part of a Superfund
response action generally is considered to be an off-site
activity, even if a CERCLA waste is first pretreated in
a wastewater facility located on site. Consequently, all
discharges to a POTW still have to be in compliance
with the off-site policy, ie., any facility accepting the
waste must have no relevant violations, uncontrolled
releases, or other environmental conditions that pose
a significant threat to human health, welfare, or the
environment, or otherwise affect the satisfactory
operation of the facility. In addition, site managers
must comply with both substantive and administrative
requirements (e.g, permits) of Federal, State, and local
laws and regulations.
EVALUATING THE POTW OPTION
Determining the feasibility of utilizing a POTW as a
discharge option should begin as early in the remedial
process as possible, i.e., once it is known that
wastewater streams generated during site
characterization, treatability studies, and/or response
actions will require treatment. Wastewater streams at
CERCLA sites that may be suitable for treatment in a
POTW include ground water, leachate, surface runoff,
or process streams generated by remedial activities
(eg., wastewaters from treatment processes) The
necessary steps involved in evaluating the POTW
option are outlined below.
1. Identify and Characterize CERCLA Wastewater
Discharge
In order for a POTW to accept a CERCLA
discharge, it will require data on the nature of the
discharge, including the constituents within the
wastestream. Therefore, data necessary to characterize
wastestreams and determine whether a POTW can
receive the discharge should be identified and
collected as early in the remedial process as possible
(e.g., during the sampling phase(s) of the Remedial
Investigation/Feasibility Study)
A POTW generally will require sampling information
on all Target Compound List (TCL) constituents
before it can accept a waste. [The TCL is a list of 152
volatile and semi-volatile organic compounds,
pesticides, polychlorinated biphenyls (PCBs), and
inorganics used in the contract laboratory program
(CLP) under CERCLA.] In addition, POTWs usually
require information about conventional pollutants in
the wastestream, such as the five-day suspended solids,
nitrite-nitrate, total Kjeldahl nitrogen, total
phosphorus, oil and grease, total dissolved solids, color,
total sulfides, and pH. The wastestream to be
discharged also should be characterized in terms of
quantity, i.e., as a function of time or expressed in
terms of daily average and daily maximum flows and
size and frequency of batch discharges.

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Lastly, because of the potential applicability of
RCR.A requirements to a POTW and the waste
management requirements that may be trjggered dunng
transportation and storage of the wasies, site mihagers
should determine whether a CERCLA astewater is a,
RCRA hazardous waste.
If the CERCLA wastestream is considered a RCRA
hazardous waste, site matiagers .need tO determine
whether the Domestic Sewage Exclusion (D,SE) applies
to the discharge of that waste to a POTW The, .CRA
DSE exempts domestic sewage, ari i mixture of
domestic sewage, and other wastes, that pass through
a sewer system to a POTW for treatment from
classification as a solid waste and, therefore as a
RCRA hazardous waste. [ The Domestic Sewage
Exclusion applies only to the actual point discharge; it
does not exclude industrial wastewaters while they are
being collected, stored, or treated before discharge;
sludges that are generated by industrial wastewater
treatment; or wastes received within the POTW’s
property boundary by truck, rail, or dedicated pipe.)
2. Identify Local POTWs
Once CERCLA wastestreams have been
characterized, site managers should identify existmg
POTWs within a delineated geographic area in which
it is technically feasible to transport the CERCLA
wastestream Factors for evaluating the feasibility of
transport to a POTW include
• The distance to the POTW or its existing sewer
lines;
• The volume of the wastewater;
• The viscosity or percent solids of the wastewater,
• Topography of the area;
• The need to obtain right-of-way permits; and
• Cost of transportation.
3. Evaluate Regulatory Status
If the determination is made that the discharge of
CERCLA aqueous wastes to a POTW is technically
feasible, site managers should begin evaluating the
regulatory status of the POTW potentially receiving the
wastes. One important source of information about
the regulatory status and facility-specific acceptance
requirements are the municipal authonties responsible
for technical and administrative oversight of each
POTW. The National Pollutant Discharge Elimination
System (NPDES) authority (State or Regional Office
of Water) can provide additional information
concerning the level of treatment, capacity, operating
history, and collection system that will be helpful for
screening POTWs.
If the CERCLA waste stream is considered a RCRA
hazardous waste and the DSE does not apply, site
managers should determine whether the POTW meets
RCRA Permit-by-Rule requirements POTWs
operating under an NPDES permit issued before
November 8,1984 currently must be operating under a
valid permit and be in compliance with the permit,
including RCRA manifesting and reporting
requirements. (In addition, the waste must meet all
Federal, State, and local pretreatment requirements
that would apply to the waste if it were discharaed
through a sewer, pipe, or similar conveyance The
necessary “POTW-spectfic” analyses of pretreatment
requirements are discussed later under step 5) If the
POTW is operating under a permit issued or renewed
after November 8, 1984, it also must comply with
RCRA corre tive action requirements under 40 CFR
264.101.
Site managers should identify the operations and
responsibilities of the POTW and the regulations that
apply to these activities to ensure compliance with
RCRA pernut-by-rule requirements. It is important to
involve P01W personnel to ensure that accurate and
complete information is received and evaluated As an
additional check, site managers can review EPA’s
Quarterly Noncompliance Report that includes a listing
of all POTW facilities that are in significant non-
compliance.
4. Evaluate Technical/Administrative Feasibility
If a POTW is determined to be in compliance with
its NPDES permit and is technically capable of
accepting the waste (see Highlight 1), it should be
determined whether acceptance of the CERCLA waste
is administratively feasible. Negotiations between EPA
and the POTW authority concerning administrative
feasibility should consider the permitting process and
effects of existing local ordinances.
If pollutants exist in the CERCLA wastewater that
the POTW did not previously handle, the NPDES
permit may require modifications, the pretreatment
program may require revisions to regulate the new
pollutant or increased discharges. In such cases, the
P01W may be unwilling to have the changes made, or
the required changes may not be feasible in a timely
manner. Similarly, local ordinances may include
prohibitions that make it illegal for the POTW to

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accept the CERCLA wastes, (e.g., restrictions on
accepting only domestic discharges). Consequently, it
i necessaiy to ensure compliance with these laws and
regulations or to see if the possibility of obtaining
variances exists.
There also may be liability issues associated with a
POTW’s accepting Superfund wastes. Section 107 of
CERCLA states that whenever there is a release or a
threatened release of a hazardous substance, the
responsible parties can be held liable for the costs of
cleanup of that release. Potentially responsible parties
(PRPs) include current owners and operators of the
facility, those who owned and operated the facility at
the time of the release, persons who transported the
substances and selected the disposal facility, the
generators of the waste, and the persons who arranged
for disposal or treatment of the hazardous substances.
Under CERCLA Section 107(j), federally permitted
releases as defined in Section 101 (10) are not subject
to such liabilities. These releases include discharges
covered by an NPDES permit, permit application, or
permit administrative record. These releases also
include the introduction of any pollutant into a POTW
when such pollutant is specified in (and in compliance
with) pretreatment standards, and a pretreatment
program has been submitted to EPA for approval
Therefore, local limits should be established for all of
the pollutants that exist in the CERCLA wastewater to
eliminate the possibility of the POTW’s being held
liable for the release of hazardous wastes.
Section 119 of CERCLA does not authorize
indemnification from liability to facilities regulated
under RCR.A. including RCRA Permit-By-Rule
POTWs. At this time, EPA believes that an extension
of indemnification to POTWs, even those not subject
to RCRA regulations, would be inconsistent with
Congressional intent.
5. Evaluate POTW Pretreatment Requirements
Once the best candidate(s) for receiving the
discharge has been determined using the four steps
outlined above, a POTW-specific analysis 01
pretreatment requirements designed to prevent pass
through, inhibition, and sludge contamination at a
POTW should be conducted to ensure that CERCLA
discharges are in compliance. Section 307(b) of the
CWA established the National Pretreatment Program,
which specifies three types of pretreatment standards.
general prohibitions, national categorical standards,
and local limits (see Highlight 2).
General prohibitions are intended to address site-
specific problems at POTWs and to apply a broad
baseline level of control to all industrial users
discharging to any POTW. National categorical
standards are technologically-based effluent limits that
must be achieved prior to introduction into a POTW
of wastes generated by particular categories of industry,
such as leather tanning and metal finishing. [ EPA
however, has not promulgated specific national
categorical pretreatment standards that govern the
discharge of CERCLA wastes to a POTW. As a result,
CERCLA wastes are treated as non-domestic
wastestreams, and are subject to the general
pretreatment regulations.] Local limits are specific
requirements developed and enforced by individual
POTWs to implement the national general prohibitions
and categorical standards.
Highlight 1
TECHNICAL FACTORS AFFECTING
THE FEASIBILITY OF DISCHARGING
TO A POTW
• The POTW’s hydraulic and organic load
capacity;
• The suitability of the POTW’s unit
operations for treatment of contaminants;
• If the CERCLA wastestream will be
discharged to a sewage collection system,
whether that system is separate from or
combined with the storm drain system, and
the capacity of that system to provide
proper containment of the wastestream;
• Whether there are combined sewer
overflows between the site and the POTW,
• The adequacy of the capacity and age of
the sewer piping system for the CERCLA
discharge flow rate;
• The sludge disposal processes currently
employed by the POTW; and
• The likelihood that the POTW could treat
the CERCLA wastestreani for the
duration required

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POTWs also may have a State-approved
pretreatment program and be required to have
mechanisms in place to ensure that dischargers comply
with applicable pretreatment standards and
requirements. Most POTWs likely will require some
type of self-monitonng program and submission of
monhtonng results to the POTW on a periodic basis.
An approved pretreatment program for a POTW
may not address all of the constituents of the
CERCLA discharge, in which case the site manager
must proceed as though an approved pretreatment
program did not exist, i.e., site managers must
determine whether sufficient mechanisms exist to
enable the POTW to ensure compliance with
appropriate pretreatment requirements.
Whether an approved pretreatment program exists
or not, compliance with applicable regulations must be
achieved. If an approved program exists, the
evaluation of a POTW’s pretreatment requirements
consists of obtaining the local limits enforced by the
POTW to prevent pass through, inhibition, and sludge
contamination If an approved program does not exist
or if the pretreatment program does not address all of
the components of the CERCLA waste, local limits
must be estimated by calculating the mass balances of
the wastestream to be disposed.
Estimating Local Limits to Meet Standards
Ideally, the POTW will have existing local limitations
for all of the contaminants present in the CERCLA
discharge. However, in many cases, the POTW will not
have local limitations for all of the contaminants in the
CERCLA discharge or existing limits may need to be
changed as a result of the discharge. In this case, the
limits must be developed by the POTW or estimated by
the site managers so that pretreatment alternatives may
be evaluated. Promulgated national categorical
pretreatment standards can he used in calculating local
limits for the CERCLA wastewater constituents where
limits do not already exist.
When the estimation of local limitations is
necessary, the following measures may be taken:
• Obtain Pertinent Regulatory Criteria to Ensure
Compliance of Estimated Limits With the Criteria
In estimating local limits it is necessary to comply
with limits that have been established on the Federal
and State levels. Furthermore, consulting these
limits can give necessary guidance for establishing
limits on the local level.
• Calculate a mass balance for each Compound
detected in the CERCLA waste using treatabilitv
The purpose of the mass balance is to
calculate the general treatment efficiency of the
POTW and identify which POTW removal
mechanisms will be impacted by the removal of each
constituent from the CERCLA wastestrearn. There
are several options for calculating the mass balance
of a particular contaminant, including the use of
POTW-specific or published treatability data and the
use of computer models.
• Evaluate the impact of each contaminant on air
emissions, treatment plant operations, sludge
disposal. and effluent air quality : Data exists (for
most contaminants) that makes it possible to
calculate the concentration of those contaminants in
air emissions, sludge, and also the amount that will
be biodegraded by certain operations.
Highlight 2
PRETREATMENT STANDARDS SPECIFIED
tSNDER THE OVA
General Prohibitions - Nationat prohibitions that
are applicable to nondomestic uses that control the
introduction of contaminants into POTWs to
(a) prevent interference (i e, a discharge that inhibits
or disrupts a FOTW causing a violation of its
t4PDES permit or other requirements) with the
operations of a P0Th’, and
(b) prevent pass through (i e, any discharge to a
POTW in concentrations thai cause a violation of
any requirement of the POTW’s NPDES permit)
of contaminants through the POTW
• National Categoilcal Standards National
prohibitions that apply to all non-domestic users
and protect against
(a) fire or explosion hazard in the sewers or POTWs
(b) corrosive structural damage to the POTW,
(c) obstruction of flow in ihe sewer system,
(d) interference due to the pollutants’ high
concentration or flow rate, or
(e) an increase in temperature ot wasiewater entering
the POTW that inhibits biological activity
resulting in interference
• Local Limits. Specific requirements that are
developed and enforced by individual POTWs to
implement the national general and specific
prohibitions States and localities also may impose
more su-ingent requirements than the national
limits on disdiargers to their regulated facilities
• Estimate local limits and the expected level of

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pretreatment
necessary to ensure continu i
compliance with NPDES permit limits and applicable
air emission standards, avoiding any exceedance of
State water quality standards and maintaining
acceptable levels of sludge quality . Using the local
limits and the composition of the CERCLA
wastewater, determine if and when additional
pretreatment is necessaiy to ensure compliance with
the POTW’s pretreatment requirements.
(Eventually, the estimated limits must be transferred by
the P01W mw enforceable limits. Because this
process may take tune and cause a delay in the
evaluation process, site managers should begin this
evaluation as early as possible).
Determining Pretreatment Options
Generally, site managers will have several
pretreatment options to achieve the identified limits
in effect at a POTW: -
Treatment technologies--(e.g., aerobic biological
treatment, precipitation, and oxidation),
• Separation technologies--(e.g., clarification,
filtration, and oil and grease separation);
• Polishing technologies--(e.g., carbon adsorption
and ion exchange).
[ Note: in many cases, these technologies may have
already been evaluated as pan of other alternatives
not involving discharge to a POTW.]
Once possible treatment technologies are
identified based on the nature of the CERCLA
wastes and the pretreatment requirements of the
P01W, it is necessary to develop a pretreatment
program that will result in CERCLA wastewater that
complies with the POTW’s pretreatment
requirements.
The key steps in the process for evaluating the
feasibility of discharging CERCLA wastes to a POTW
are summarized in Highlight 3.
Highlight 3
PROCESS FOR EVALUATING CERCLA DISCHARGES TO POTWs
L-
.
1
W i....lu .
• ldenti?y the slt. .wecrlc cERct.A
Wret er dIsctra, es
• Determine data requirements arid coOed
data to fulfill these requirements
• Evaluate all ava1Ia 4 data to
th eda.want
• Determine if the CERCLA t er
a RCPA ha2ar j3
2. Id.l Iy Local PO1Ws
• Determine geoQraphlc area to bo
• Consider methods ransporting the
eal.am to the P01W
• identify potentIal PO1Ws arid g Ier

Ev*iat,
‘J. R.guiatory Stabs.
• tv oalIgate the compliance ataru, ot
the P01W
• if cERc*.A waaiettream Is a hazardous
waate determine If Domestic Sewage
Earfuslon Is applicable If not. determine
Permit - by - Rule requirements
Evabset. Tsctelcd
4
• Contoct the P01W to determine if they are
willing to occagt a CEACLA eeneim
• Evaluate the P01Ws ability to handle and
ppert treat the CEACLA wast Tsarn
• Address and discuss me PO1W8 potential
liability a onTed with occepllng a
CER A wesreaneam
• Evaluate the current permits ot the P01W
and determine changes required and rer
permte needed
Evabiet. Prebeabew*
5
• Oblain or estimate the local limItS eryfo, ..U by
tha P01W to present p thmugli Innlbflicn
and sludge comamthabon
• Compare CERCLA dIscharge ctiarscterlstlcs
to local Ittst odeterminewiiicf i
contaminants muirepretreatmeru
• identify pocaible pretreatment technologies
• Develop a pretreatment pm a train to properly
pretreat th. CERCLA w esseam

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