&EPA
United States
Environmental Protection
Agency
OSWER Directive 9200.1-116-FS
December 2013
Office of Superfund Remediation and
Technology Innovation
Sediment Assessment and Monitoring Sheet (SAMS) #4
A Primer for Remedial Project Managers on Water
Quality Standards and the Regulation of Combined
Sewage Overflows under the Clean Water Act
December 2013
OSWER Directive 9200.1-116-FS
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Contents
1. Introduction 1
2. What are the Clean Water Act (CWA) Goals and Requirements? 2
2.1 Goals 2
2.2 Requirements 3
2.2.1 Water Quality Standards 3
2.2.2 Assessing Water Quality Standard Attainment 5
2.2.3 Technology-Based Standards 6
2.2.4 Ambient Water Quality Criteria 6
2.2.5 The National Pollutant Discharge Elimination System Program 7
3. What are CSOs? 8
3.1 Impacts of CSOs on Water Bodies 9
3.2 How are CSOs and CSSs Regulated? 10
3.3 How is a Long-Term Control Plan Developed? 11
3.4 Implementation Schedules for CSO Plans 14
3.5 Recent Developments in CSO Control Planning 14
4. CWA Implementation and Possible Implications for Sediment Remediation under Superfund 15
4.1 Programmatic Goals 16
4.2 Media, Contaminants, and Cleanup Objectives 16
4.3 Sources, Controls and Site Management 17
4.4 Cost Considerations 18
4.5 Contamination/Recontamination by CSOs and Storm Water Outfalls 18
4.6 Need for Improved Coordination and Integration of CWA Regulation of Waterbodies and
CERCLA Remediation at Sediment Sites 19
5. References 21
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A Primer for Remedial Project Managers on Water Quality Standards and the Regulation of Combined Sewage
Overflows under the Clean Water Act
1. Introduction
Efforts to restore impaired water bodies have relied on two distinct laws. The Clean Water Act (CWA)
regulates discharges of pollutants to surface water, while the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) provides a mechanism for the assessment and cleanup of
surface water and sediment contamination resulting from the release of hazardous substances that presents
unacceptable risks to human health or the environment. The CWA and CERCLA are inherently linked
when sediment sites are considered, because surface water discharges can be sources of contamination to
sediment, and contaminated sediment can be an ongoing source of contamination to surface water.
Surface water discharges with storm water components, especially combined sewer overflows (CSOs),
can be challenging to control and regulate under the CWA, and their potential impacts to sediment may
complicate Superfund cleanups under CERCLA, especially in urban waterways.
The purpose of this fact sheet is to provide Superfund Remedial Project Managers (RPMs) with brief
summary information on how CSOs and other discharges are regulated under the CWA, emphasizing the
objectives of the legislation and how it is often applied in practice, and some significant challenges in
employing those controls to meet the objectives of the CWA. Similarities and differences in objectives
between the CWA and CERCLA and how they may affect remediation of contaminated sediment are also
highlighted. There is a great deal of information about CWA regulations, guidances, and policies on the
website of the U.S. Environmental Protection Agency Office of Water1. This fact sheet only summarizes
some of the key components as they might apply to Superfund sites. RPMs with sediment sites in areas
with permitted discharges should familiarize themselves with the CWA guidances and policies and work
closely with regional staff in the Office of Water throughout the remedial investigation and feasibility
study (RI/FS) and remedy selection processes. Additional information on how RPMs should consider
sections of the CWA regulations at their sites can be found in the CERCLA Compliance with Other Laws
Manual, Volume I, EPA/540/G89-006, August 1988.
This document provides guidance to regions and others regarding how the Agency intends to interpret and
implement the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), which
provides the framework for CERCLA implementation. However, this document does not substitute for
those provisions or regulations, nor is it a regulation itself. Thus, it cannot impose legally binding
requirements on EPA, states, or the regulated community and may not apply to a particular situation
based on specific circumstances. Any decisions regarding a particular situation will be made based on the
statute and regulations, and EPA decision-maker retain the discretion to adopt approaches on a case-by-
case basis that differ from this guidance where appropriate.
This fact sheet was prepared by EPA's Office of Superfund Remediation and Technology Innovation.
Drafting and revisions were provided by LimnoTech under subcontract to TetraTech EM Inc., (Prime
Contract Number EP-W-07-078).
1 www.epa. gov/npdes. This and other web addresses cited in this document are current as of December 2013.
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A Primer for Remedial Project Managers on Water Quality Standards and the Regulation of Combined Sewage
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2. What are the Clean Water Act (CWA)
Goals and Requirements?
The Federal Water Pollution Control Act (FWPCA) was enacted in 1948 and amended in!956 and 1972
and is more commonly known as the CWA. The amendments established a framework for restoring
surface waters under the CWA. The CWA includes the national goals listed below, which have a direct
impact on establishing water quality standards (WQS). The WQS play a significant role in setting effluent
limits for discharges to surface waters of the United States. These discharges are regulated under the
CWA's National Pollutant Discharge Elimination System (NPDES) program. Currently, EPA delegates
authority for implementing the NPDES program to 46 states and one territory.
2.1 Goals
The overall objective and specified goals of the CWA are as follows:
"The objective of this Act is to restore and maintain the chemical, physical, and biological integrity of
the Nation's waters. In order to achieve this objective it is hereby declared that, consistent with the
provisions of this Act ~
(1) It is the national goal that the discharge of pollutants into the navigable waters be eliminated
by 1985.
(2) It is the national goal that wherever attainable, an interim goal of water quality which provides
for the protection and propagation offish, shellfish, and wildlife and provides for recreation in
and on the water be achieved by July 1, 1983.
(3) It is the national policy that the discharge of toxic pollutants in toxic amounts be prohibited.
(4) It is the national policy that Federal financial assistance be provided to construct publicly
owned waste treatment works.
(5) It is the national policy that area-wide waste treatment management planning processes be
developed and implemented to assure adequate control of sources of pollutants in each state.
(6) It is the national policy that a major research and demonstration effort be made to develop
technology necessary to eliminate the discharge of pollutants into the navigable waters, waters of
the contiguous zone, and the oceans.
(7) It is the national policy that programs for the control of nonpoint sources of pollution be
developed and implemented in an expeditious manner so as to enable the goals of this Act to be
met through the control of both point and nonpoint sources of pollution."
Congress recognized that the elimination of pollutant discharges would take time and set goal #2 above as
an interim goal of water quality. This interim water quality goal is still the object of vigorous regulatory
United States
Environmental Protection
Agency
Office of Superfund Remediation and
Technology Innovation
OSWER Directive 9200.1-116-FS
December 2013
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A Primer for Remedial Project Managers on Water Quality Standards and the Regulation of Combined Sewage
Overflows under the Clean Water Act
effort. The CWA goal of water quality, defined in terms of supporting specific activities and uses of water
bodies, complements yet differs in important ways from CERCLA's goal of reducing risks to human
health and the environment posed by exposure to hazardous substances. Many of the differences between
CWA and CERCLA regulation of water bodies are rooted in the differences in their goals.
2.2 Requirements
Several requirements of the Clean Water Act play an important role in the regulation of combined sewer
overflows, including water quality standards, assessing attainment of water quality standards and total
maximum daily loads; technology-based standards; ambient water quality criteria; and the National
Pollution Discharge Elimination System (NPDES) program. The following sections discuss these
requirements.
2.2.1 Water Quality Standards
Consistent with the above goals, the CWA provides for states to establish WQS. WQS are reviewed and
approved by EPA. Often cited as applicable or relevant and appropriate requirements (ARARs) at
Superfund sites, a water quality standard is not just a single criterion or metric describing a chemical
concentration. The standard has three distinct parts:
• A designated waterbody use;
• Criteria to protect the designated use (generally referred to as ambient water quality criteria and
often expressed as chemical-specific concentration values); and
• An antidegradation policy and implementation method.
It is important to recognize that each water quality criterion is specific to water bodies having the
associated designated use (such as bacteria limits for recreational uses), and that the full list of numeric
criteria for 126 priority pollutants and 44 non-priority pollutants may not always be applied uniformly to
all water bodies in a state.
The designated water body uses are established by the state based on data available and are expected to
be consistent with the goals (listed above) set by Congress. These designations must take into
consideration
• The use and value of water for public water supplies;
• Protection and propagation offish, shellfish and wildlife;
• Recreation in and on the water; and
• Agricultural, industrial, and other purposes including navigation.
In practice, each state establishes a set of designated uses for each water body in that state, consistent with
its character and setting, and the lists of designated uses vary across states. Designated uses typically
include protection of recreation and aquatic life. Some states include fish consumption as a designated
use. States may also designate the waters for industrial use in cooling or product make-up water. The
WQS regulations provide that, in setting designated uses, states must consider the WQS of downstream
waters and ensure their WQS provide for the attainment and maintenance of the downstream waters.
There is no single prescriptive methodology that states must follow to establish designated uses, but they
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A Primer for Remedial Project Managers on Water Quality Standards and the Regulation of Combined Sewage
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must specify the designated use. It is important that EPA RPMs know the designated uses and the water
quality criteria of the water body under investigation.
EPA's implementing regulations for the CWA distinguish between designated and existing uses.
Specifically, the regulations clarify that a designated use can be changed if data exist to support the
change, but if the designated use is also an existing use it cannot be removed. To remove a designated
use, the state must present data detailing why the designated use is not attainable. This process is referred
to as a "use attainability analysis." The process requires the state to demonstrate that it is infeasible to
attain the use based on one of several allowable factors, such as some natural or physical condition, or
modification to dams or other human-caused condition that cannot be changed. From a Superfund
perspective, there may be interest in encouraging the state to add a more protective designated use, such
as fish consumption for a site where protection is currently limited only to fish survival. The state can
make such a change with the approval of EPA, and with notice and opportunity for a public hearing.
Criteria protecting recreational uses rely primarily on fecal indicator bacteria levels to prevent an
unacceptable level of illnesses during recreation on or in the water. Criteria for aquatic life uses, such as
cold water fishery or areas designated as habitat for specific sensitive species can include temperature,
dissolved oxygen, and toxic pollutant limitations designed to ensure healthy populations of organisms that
are expected to be present in those areas. Criteria for aquatic life uses may also be based on biological
indices. States may also designate water bodies for agricultural water supply to ensure that water quality
is appropriate for irrigation of crops.
To assist the states in establishing appropriate criteria, Section 304 of the CWA requires the EPA to
develop water quality criteria in the form of guidance. EPA maintains a website that provides a list of
pollutants for which it has developed criteria under Section 304 of the CWA, along with documentation
and guidance.2
States may adopt these recommended criteria directly as part of the WQS, or they may adopt different
criteria based on other scientifically defensible methods, where supported by data, that are more
appropriate to the conditions of specific waterbodies. The criteria established by the EPA include three
components: magnitude (allowable level of pollutant or pollutant parameter usually expressed as a
concentration), duration (the averaging period), and frequency (how often the criteria may be exceeded
without causing an adverse impact on the use). In most cases, these criteria are applied in the water
column, rather than to sediment or biota. One exception is the criterion of 0.3 milligrams of methyl
mercury per kilogram of fish tissue that the EPA established in January 2001. The EPA's approach for
developing human health criteria that are based on methodologies to estimate bioaccumulation in fish are
available on an EPA website.3 The EPA has not developed water quality criteria for levels of pollutants in
sediment; i.e., there are no promulgated federal ARARs to use as sediment cleanup levels.
The purpose of the anti degradation policy is to protect existing uses and the level of water quality
necessary to support these uses, to protect high quality waters, and to provide a transparent analytic
2 water, epa. gov/scitech/swguidance/standards/criteria
3 water.epa.gov/scitech/swguidance/standards/criteria/aqlife/upload/2003 01 23 criteria alcg sab draft.pdf.
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process for states and tribes to use to determine whether limited degradation of high-quality waters is
appropriate and necessary.
2.2.2 Assessing Water Quality Standard Attainment
In addition to addressing state requirements to develop water quality standards, Section 303 of the CWA
requires states to periodically assess whether waters are attaining water quality standards and provide a
list to EPA detailing the locations of nonattainment and the suspected reasons for impairments. States
submit this list for EPA approval every two years, and it is referred to as the "impaired waters list" or
Section 303(d) list. States are also required to develop a total maximum daily load (TMDL) for waters
placed on the list. A TMDL calculates the maximum pollutant load that the water body can receive and
still attain water quality standards. The CWA requires that the "load shall be established at a level
necessary to implement the applicable water quality standards with seasonal variations and a margin of
safety which takes into account any lack of knowledge concerning the relationship between effluent
limitations and water quality." Superfund does not generally consider TMDLs as ARARs for Superfund
cleanups, although the water quality standards used as the basis for the TMDLs may be ARARs (EPA
2005).
The CWA categorizes pollutant sources as either point sources or nonpoint sources. A point source is
defined as any discernible, confined, and discrete conveyance, such as a pipe, ditch, channel, tunnel,
conduit, or container. Control of point sources is handled primarily through the NPDES permit program.
In the CWA, point sources are clearly the focal point to be controlled, as the legal prohibition against
pollutant discharge without an NPDES permit or other specific allowance applies only to point source
discharges.
A nonpoint source is not specifically defined in the CWA, but is any source that is not a point source.
Typical nonpoint sources include runoff from rural areas, including farming, animal grazing, and timber
harvesting. The CWA does not establish a control program for nonpoint sources, as it did for point
sources. Nonpoint sources are primarily addressed through voluntary programs that include grant funding
to States, territories, and tribes for assistance and training, as well as for demonstration and monitoring of
reductions in pollutant loads. Releases to the water column from contaminated sediments at a Superfund
site would be considered a nonpoint source. Significant differences between the two approaches to source
control can be problematic for states as they develop TMDLs for waterbodies with both point sources and
nonpoint sources.
The TMDL establishes a ceiling for the sum of individual waste load allocations (WLAs) for point
sources, load allocations (LAs) for nonpoint sources, natural background sources, seasonal variations, and
a margin of safety. The state is required to develop a TMDL for the pollutant of concern, designed to
attain water quality standards, for each water-quality-limited water body identified on the 303(d) list. EPA
has issued numerous guidance documents and policy memoranda to assist states (and stakeholders) in
developing TMDLs.4
4 water.epa.gov/scitech/swguidance/standards/upload/2005 05 06 criteria humanhealth method complete.pdf
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2.2.3 Technology-Based Standards
Section 301 of the CWA also establishes how pollutants from point sources are to be controlled. It
describes a framework of increasingly more stringent technology-based standards to be developed by the
EPA to limit the amount of pollutants from the various categories of point sources. In the case of
industrial point sources, these standards are often referred to as "effluent guidelines." In most cases, these
are effluent limitations expressed as a pollutant mass of concentration not to be exceeded at the end of the
pipe. The EPA usually tries to establish the limitations as mass limits linked to production (for example,
pollutant parameter X shall not exceed Y pounds for Z pounds of product produced).
Congress' expectation for requiring these standards was that, over time, technology would advance to the
point that there would be no discharge of pollutants, meeting one of the CWA goals discussed above. The
initial step required EPA to develop standards based on Best Practicable Control Technology Currently
Available (BPT) and these standards were to be achieved by 1977. BPT standards addressed toxic [such
as, polycyclic aromatic hydrocarbons (PAHs), metals, polychlorinated biphenyls (PCBs)], conventional
[such as biochemical oxygen demand (BOD), total suspended solids (TSS), fecal indicator bacteria (FIB),
and pH], and non-conventional pollutants (such as floatables, which consist of trash and other visible
floating debris). To establish the level of pollutant control under BPT, the CWA directed EPA to consider
the average of the best existing performance by well-operating plants within each industrial category or
sub-category.
In the next phase of CWA implementation, EPA was required to develop standards based on Best
Available Technology Economically Achievable (BAT) and Best Conventional Pollutant Control
Technology (BCT) with a compliance deadline of 1983, which was extended to July 1, 1984, and
extended again to March 31, 1989. BAT standards addressed toxic pollutants and non-conventional
pollutants, such as may be generated by industrial facilities, while BCT addressed conventional
pollutants, more typical of pollutants treated by publicly owned treatment works (POTWs). BAT
considers the performance associated with the best control and treatment measures that have been, or are
capable of being achieved, and the cost of attainability, but does not balance the cost of implementation
against the pollutant reduction benefit. For BCT, however, the Act directs EPA to consider the
relationship between costs and benefits, as well as characteristics of specific POTW facilities, including
age, process, energy requirements, and cost and difficulty of control as compared with industrial facilities.
These BPT, BAT, and BCT standards are applicable to existing discharges, and the deadlines for
compliance with these standards have all passed.
Congress also required EPA to establish New Source Performance Standards (NSPS). These standards are
applied to any discharge where construction began after the standard for the specific industry category
was promulgated. Generally, NSPS are more stringent than standards for existing sources. These
standards are based on the state-of-the-art technology available at the time of construction, and the
assumption is that the standard can be planned for and the necessary controls can be installed in the
facility.
2.2.4 Ambient Water Quality Criteria
The term "water quality standard" is often incorrectly used to refer to ambient water quality criteria.
Water quality criteria, however, comprise a key component of the three-part WQS for establishing
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effluent limitations. The CWA generally requires states to adopt numeric water quality criteria for a list of
65 classes of "toxic" pollutants, which the EPA has developed into a list of 126 specific "priority"
pollutants. States often adopt the EPA ambient water quality criteria values at which time they become a
state water quality standard. The CWA directs EPA to develop, publish, and, from time to time, revise
water quality criteria, accurately reflecting the latest scientific information for these priority pollutants.
EPA's numeric water quality criteria are designed to be protective of plants and animals when applied in
the water (not at end of pipe), and to address short-term (acute) and long-term (chronic) effects on
freshwater and saltwater species. For example, criteria for protection of fisheries typically include
minimum aqueous concentrations of dissolved oxygen. It is important to note that the criteria are not
expressed in the same terms as an effluent limitation. Effluent limitations include a magnitude and an
averaging period (usually daily, weekly, or monthly); therefore, a conversion step is necessary to be able
to back-calculate effluent limits consistent with water quality criteria.
2.2.5 The National Pollutant Discharge Elimination System Program
A major component of the 1972 amendments to the CWA was creation of the NPDES permit program.
The NPDES program regulates all types of point source discharges to water bodies of the United States.
Since its creation, it has significantly reduced the discharge of pollutants from point sources. Any
discharge of pollutants from a point source is prohibited unless authorized by a NPDES permit. This
includes permits for combined and separate sewer overflows and non-agricultural storm water outfalls.
For most situations, NPDES permit limits are developed following these steps:
• Apply technology-based limits based on secondary treatment standards for POTWs, and limits
based on effluent limitation guidelines for non-POTWs. If, however, effluent limitation
guidelines do not exist for the specific industry discharge, the limits are based on a best
professional judgment (BPJ) calculation. Assess whether the technology-based limitations are
stringent enough to protect WQS.
• If there is reasonable potential for a pollutant in the discharge to cause or contribute to a violation
of the applicable WQS, and the technology-based effluent limit is not stringent enough to protect
the WQS, then set a limit for the pollutant at a level to ensure the numerical standards contained
in the WQS are not exceeded.
• If the receiving water body is on the list of impaired waters and a TMDL has been issued, use the
WLA from the TMDL to develop the effluent limit.
• Include monitoring and reporting in the permit to demonstrate compliance with an effluent limit.
If there is no limit, data collection may be required to determine whether a limit is necessary
during the next permit cycle.
During the early years of the NPDES program, the focus was on the discharge from continuously
discharging POTWs and industrial wastewater treatment plants. More recently, additional attention has
been paid to wet weather sources, such as municipal storm water, industrial storm water, and combined
sewer overflows (CSOs). In 1994, EPA issued the CSO Control Policy that outlined how the NPDES
program would regulate CSOs. CSOs are discussed in more detail below. The issue common to all of
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A Primer for Remedial Project Managers on Water Quality Standards and the Regulation of Combined Sewage
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these wet-weather discharges is that they are highly unpredictable and highly variable in volume and
duration. In light of this high level of variability, numeric effluent limits would be difficult to calculate;
therefore, permit limits in the form of best management practices (BMPs) have a much larger role in CSO
and storm water permitting than they do for other point source discharges.
3. What are CSOs?
UNITED STATES COMBINED SEWER SYSTEMS
Figure 1 - Combined Sewer System Locations
In the early 1900s, many developing cities constructed
combined sewer systems (CSSs), instead of separate sanitary
and storm water sewer systems, to conserve resources. By the
mid-1900s, construction of combined sewers was prohibited
by state and local governments. Figure 1 shows that most of
the CSSs are located in the Northeast, Great Lakes region, and
Pacific Northwest (adapted from EPA 2004), in core areas of
older communities of all sizes.
As POTWs were built, CSSs were sized to convey all of the
combined sewage to the POTW for treatment during periods
of no rain (dry weather) or for smaller storms when the connecting sewers leading to the POTW
(interceptor sewers) were not full. In many CSSs, the city or utility owns the interceptor sewers but does
not own the private laterals that connect houses or businesses to the interceptor sewer, which can make
control of CSOs difficult. CSSs were designed to discharge directly to receiving water bodies from an
outfall pipe during large rainfall or snowmelt events exceeding the capacity of a POTW. These conditions
are illustrated in Figure 2 (EPA 2004). According to EPA's Office of Water, there are 772 communities
with CSSs that serve 40 million people in the United States.5 The sizes and magnitudes of CSSs and their
impacts on surface waters vary significantly. Small communities may have only one or two outfalls, or in
some cases many outfalls (for example, Defiance, Ohio, has 44 outfalls and serves 3,000 people). Larger
communities, such as New York City or Cleveland, Ohio, can have multiple POTWs, each with its own
CSS and number of overflow
locations.
As cities grew, new separate
sewer systems were built
often tied into the existing
CSS. In a separate sewer
system, the city constructs a
separate sanitary sewer
system (SSS) to convey
sanitary sewage to the CSS or
Figure 2 - Schematic of Combined Sewer Structure and Performance POTW and a separate Storm
5 http://crpub.epa.gov/npdes/cso/demo.cfm7program id=5
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sewer system to convey storm water runoff directly to the receiving water bodies. As both CSSs and SSSs
aged, and cities often failed to maintain infrastructure, infiltration of groundwater and inflow of runoff
that was not intended to reach the sewer system resulted in increased wet weather flow within both the
CSS and SSS. CSS capacity is therefore exceeded more frequently than originally designed. Some cities
experience CSO discharges nearly every time it rains. Infiltration can also lead to overflows of SSSs, even
though the purpose of separation is to avoid overflows.
3.1 Impacts of CSOs on Water Bodies
The impacts of CSOs on water quality are site-specific and highly variable and are a function of volume
discharged, discharge frequency, and pollutant concentrations. CSO volumes often correlate with the
intensity and duration of rain or snowmelt events. They also depend on antecedent moisture conditions,
groundwater levels, and land use. Antecedent moisture conditions and land use determine what portion of
the rainfall infiltrates into the ground and how much becomes runoff that would enter the CSS.
Groundwater levels also affect how much infiltration can enter the CSS through cracks or leaks in the
pipes.
Pollutants can enter the CSS from a variety of sources. These sources include sanitary waste from
residences and from public and commercial buildings; industries that discharge directly to sewers; storm
water runoff that picks up pollutants from soils and paved surfaces; and from contaminated groundwater
that infiltrates the sewers. The National Pretreatment Program regulations at 40 Code of Regulations
(CFR) Section 403 require POTWs to control the level of pollutants from industrial discharges to sanitary
sewers to ensure the wastewater treatment plant is not adversely affected and that pollutants from the
industry do not pass through the plant to the receiving water. CSO Control Policy requires review and
modification of pretreatment requirements to assure CSO impacts from industrial sources are minimized.
Storm water contaminant loads to combined sewers can be a legacy of industrial activity and materials
storage and handling. Pollutants can also build up in solids that accumulate and deposit in the sewers and
may be flushed out of the CSO with higher-intensity rain events. Because of their diverse sources and the
effects of flow, pollutant concentrations in CSOs are highly variable and difficult to predict.
The EPA has focused on limiting releases of conventional pollutants such as fecal indicator bacteria
(FIB), 5-day biochemical oxygen demand (BODS), and total suspended solids (TSS). The hazardous
substances often found at Superfund sites are typically not addressed unless it has been shown that the
CSO discharge causes or contributes to violations of the ambient water quality criteria or equivalent state
standard. With respect to toxics, however, EPA stated in its Report to Congress that "toxics in wastewater
can be a concern in industrialized areas or where monitoring data indicate potential toxicity" (Moffa
1997). Storm water contributions to CSOs in urbanized areas can also contain significant concentrations
of hydrocarbons and metals" (EPA 2004). Table 1 shows EPA's reported ranges of pollutant
concentrations in CSOs and demonstrates how widely effluent concentrations can vary (EPA 2004).
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Table 1. Range of Pollutant Concentrations in Combined Sewer Overflows (EPA 2004)
| Pollutant
Fecal coliform bacteria
BOD5
TSS
Cadmium
Copper
Lead
Zinc
Units
Colonies per 100 ml
mg/L
mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Range
3 - 40,000,000
3.9-696
1 - 4,420
0.16-30
10-1,827
5-1,013
10-3,740
Median
215,000
43
127
2
40
48
156
BOD5 - 5-day biochemical oxygen demand
TSS - total suspended solids
ml - milliliters
ug/L - microgram per liter
mg/L - milligram per litre
The contribution of the CSO discharges to water quality impairments can vary because other sources
(stormwater and nonpoint sources) upstream of the CSS often contribute the same pollutants as the CSOs,
particularly during rain events. Depending on the nature of the waterway, CSO impacts can be dispersed
quickly, whereas in slow-moving waters the pollutants from the CSOs can build up in the sediments. In
some instances, sludge deposits form mounds near the CSO outfalls. EPA has published three
comprehensive reports on the occurrence and impacts of CSOs, which were all prepared primarily from a
water column exposure perspective (EPA 2002a, 2004, 2007).
3.2 How are CSOs and CSSs Regulated?
CSOs are regulated as point sources under the CWA and the CSO Control Policy of 1994 (59 Federal
Register [Fed. Reg.] 18688-18698, April 19, 1994). The 1994 CSO Policy is also included in Section
402(q) of the CWA, as explained later in this section. The Policy was negotiated among representatives
from states, environmental groups, municipal organizations, and EPA. The impetus was that effective
implementation of CSO controls through NPDES permits was lagging because of a lack of a common and
consistent framework. The Policy included four key principles to ensure that CSO controls are cost-
effective and meet the objectives of the CWA. These principles are:
1. Clear levels of control presumed to meet appropriate health and environmental objectives;
2. Flexibility to consider the site-specific nature of CSOs and find the most cost-effective means to
reduce pollutants and meet CWA objectives and requirements;
3. Phased implementation of CSO controls, considering a community's financial capability; and
4. Review and revision of state water quality standards to reflect the site-specific wet weather
impacts of CSOs.
The Policy includes consideration of both technology-based controls and water quality-based controls.
The technology-based controls are called the Nine Minimum Controls (see text box below) and are
essentially BMPs that a community should be able to implement immediately and without significant
capital cost. The water quality-based controls consist of developing and implementing a Long Term CSO
Control Plan (LTCP) that should result in compliance with applicable water quality standards.
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EPA has developed memoranda and guidance documents to help states and CSO permittees implement
the Policy.6 In response to criticisms that little progress was being made in accomplishing the objectives
of the CSO Policy, EPA began to develop and implement a national enforcement strategy in the mid-
1990s. This strategy was formalized in an April 2000 memorandum (EPA 2000) from EPA's Office of
Enforcement and Compliance Assurance (OECA).
In December 2000, the Wet Weather Water Quality Act of 2000 was enacted. The purposes of the
legislation are:
• To prevent and reduce water quality impacts of CSOs and sanitary sewer overflows (SSOs), by
authorizing grants to municipalities and states for CSO/SSO control projects;
• To authorize grants for a wet weather pilot program; and
• To codify the EPA's CSO Control Policy of 1994 as part of the CWA, although it is still
commonly referred to as a "Policy" in CSO control planning.
The bill also directs the EPA Administrator to "issue guidance to facilitate the conduct of water quality
and designated use reviews for municipal combined sewer overflow receiving waters."
While current statistics have not been updated since the 2004 Report to Congress, many CSO
communities have entered into either federal or state enforcement agreements or are in the process of
negotiating an agreement. Often, the enforcement action addresses not only CSOs but also SSOs. For
CSOs, the agreements are either to develop and implement an LTCP or to implement an already agency-
approved LTCP that ensures that water quality standards are met during a "typical" or average year
(discussed below). Thus, it is important to recognize that a LTCP does not ensure controls meet WQS in
every year, but rather that they are met under "typical" year conditions.
For SSOs, the enforcement action typically requires the community to set forth a sewer overflow
reduction plan that effectively "eliminates" all SSOs.7 For perspective on the range of agreement costs, a
review of federal consent decrees from EPA's news releases and the Federal Register revealed that, for
2011, eight communities had agreed to implement long-term control plans for CSO or SSO control
ranging in cost from $4.2 million (Elkins, West Virginia) to $4.7 billion (St. Louis, Missouri).
3.3 How is a Long-Term Control Plan Developed?
Under the CSO Control Policy, communities are required to characterize the CSS and the impacts of
CSOs on the receiving waters. They are typically characterized by conducting monitoring and computer
6 For EPA policy memoranda and guidance documents on CSO control see
http://crpub.epa.gov/npdes/docs.cfm7document type id=l&view=Policv%20and%20Guidance%20Documents&pr
ogram id=5&sort=name
7 As noted in the 2004 Report to Congress (EPA 2004), SSOs that reach waters of the United States are point source
discharges, and, like other point source discharges from municipal SSSs, are prohibited unless authorized by an
NPDES permit. EPA has attempted draft policy for addressing SSOs, however so far to date EPA has not produced a
final policy.
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modeling of current conditions. The models are then used to evaluate the effectiveness of possible CSO
controls in meeting water quality standards assuming a typical year.
Under the Policy, communities are provided with significant flexibility in selecting the typical year. In
some instances, the community selects a typical period that might include representative wet and dry
weather precipitation or stream flow conditions. This period is different than what is considered for
developing TMDLs, which must address "critical," reasonable worst-case, conditions.
Recognizing there is no single control technology for achieving water quality standards, the community is
expected to identify alternative CSO control technologies that could be used to reduce or eliminate CSOs
under typical-year conditions. As stated in the Policy, "EPA expects the long-term CSO control plan to
consider a reasonable range of alternatives. The plan should, for example, evaluate controls that would be
necessary to achieve zero overflow events per year, and an average of one to three, four to seven, and
eight to twelve overflow events per year. Alternatively, the long-term plan could evaluate controls that
achieve 100% capture [of combined sewage], 90% capture, 85% capture, 80% capture, and 75% capture
for treatment." EPA also expects communities to evaluate
alternatives to maximize treatment of combined sewage at
the POTW by upgrading conveyance or wet-weather
treatment capacity. Furthermore, EPA states that "[t]he
analysis of alternatives should be sufficient to make a
reasonable assessment of cost and performance" known as
a "knee-of-the-curve" analysis using the typical year (EPA
1994).
$350
40% 50% 60% 70% 80% 90% 100%
Percent Capture of Combined Sewage
Figure 3 - Hypothetical Cost Curve for
Knee-of-the-Curve Analysis
A hypothetical knee-of-the-curve analysis is shown in
Figure 3, where the percent capture and treatment of
combined sewage and storm water through a combination
of technologies is compared with capital program cost.
The "knee" represents the point "where the increment of
pollution reduction achieved in the receiving water
Combined Sewer Overflows Nine Minimum Controls
1 . Proper operation and regular maintenance programs for the sewer system and the CSOs
2. Maximum use of the collection system for storage
3. Review and modification of pretreatment requirements to assure CSO impacts are minimized
4. Maximization of flow to the publicly owned treatment works for treatment
5 . Prohibition of CSOs during dry weather
6. Control of solid and floatable materials in CSOs
7. Pollution prevention
8. Public notification to ensure that the public receives adequate notification of CSO occurrences
9.
and CSO impacts
Monitoring to effectively characterize CSO impacts and the efficacy of CSO controls
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diminishes compared to the increased costs" (EPA 1994). EPA expects communities to use the knee-of-
the-curve analysis to help guide selection of controls.
Under the CSO Policy, communities can pursue either the "presumption" approach or the
"demonstration" approach to evaluate the level of CSO control that is needed to meet water quality
standards. These approaches focus on conventional sanitary pollutants (such as bacteria, BOD5, or TSS).
Toxics receive much less attention. The Policy lists the following criteria for a community to consider
when pursuing a presumption approach, all based on the typical year:
• No more than an average of four (possibly up to six) overflow events;
• Elimination or capture for treatment of at least 85 percent of combined sewage by volume; or
• Elimination or removal of no less than the mass of pollutants causing the impairment using the 85
percent volume criterion.
The CSOs meeting these criteria are expected to receive, at a minimum:
• Primary clarification,
• Solids and floatables disposal, and
• Disinfection (if necessary to meet water quality standards).
Under this presumption approach, controls are "presumed to provide an adequate level of control to meet
the water quality-based requirements of the CWA, provided the permitting authority determines that such
presumption is reasonable in light of the data and analysis conducted in the characterization, monitoring,
and modeling of the system and the consideration of sensitive areas" (EPA 1994).
The demonstration approach was included in the Policy in the event that the controls required under the
presumption approach went beyond what was needed to comply with water quality standards. Under this
approach, the community must demonstrate that each of the following are met:
• CSOs alone will not violate water quality standards;
• If other sources will cause violations after the control program is implemented, there is a TMDL
or other plan to allocate loads;
• The plan provides the maximum pollution reduction benefits reasonably attainable; and
• The plan can be cost-effectively retrofitted if additional controls are ultimately needed to meet
water quality standards or designated uses.
As discussed previously, it is important to keep in mind that water quality standards apply only to
designated uses, which often are linked only to conventional sewage pollutants, and not to toxic
contaminants addressed at Superfund sites.
Regardless of whether the community chooses a presumption or demonstration approach, it is required to
conduct post-construction compliance monitoring. The purpose of the monitoring is to ensure that the
CSO controls provide the planned level of control and to confirm that CSOs are not causing or
contributing to water quality standards violations. Details of EPA's expectations for CSO post-
construction compliance monitoring are identified in recent guidance (EPA 2012).
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With respect to CSOs causing or contributing to water quality standards violations, the CSO Control
Policy also directs that EPA and the states work with communities to "review and revise" water quality
standards as appropriate. They must be revised and reviewed because it is recognized that some standards
were established many years ago without a complete use attainability analysis, and it also recognizes that
achieving zero discharge (which might be needed to prevent violations of some existing water quality
standards) can be cost-prohibitive, as shown by the knee-of-the-curve analysis. EPA issued guidance to
facilitate these reviews and revisions, stating: "[gjiven local resource constraints, CSO communities need
clear guidance on how they should implement the CSO control and other wet weather water pollution
control programs to attain water quality standards. Water quality standards reviews are an important step
in integrating the development and implementation of affordable, well-designed and operated CSO
control programs with the requirements of the Clean Water Act (CWA)" (EPA 2001). In practice, reviews
and revisions of water quality standards have been few.
3.4 Implementation Schedules for CSO Plans
The CSO Control Policy requires that permits issued to CSO communities include construction and
financing schedules. EPA indicated that these schedules "may be phased based on the relative importance
of adverse impacts upon WQS and designated uses, priority projects identified in the long-term plan, and
on a permittee's financial capability." EPA issued guidance on developing schedules, which includes a
scoring system to determine whether a community would experience a low, medium, or high burden
implementing the CSO control program (EPA 1997).
The scoring system includes socioeconomic factors and debt and financial indicators and also establishes
2 percent of median household income (MHI) as an indicator of high burden. In the same guidance, the
EPA indicates that communities with a low burden are expected to implement controls within normal
engineering and construction guidelines; while those with medium burdens should receive up to a total of
10 years; and high burden communities should receive up to a total of 15 years with "[s]chedule up to 20
years based on negotiation with EPA and state NPDES authorities" (EPA 1997, p, 44). This guidance is
often cited as a basis for setting a maximum implementation schedule in consent decrees at 20 years.
3.5 Recent Developments in CSO Control Planning
In 2007, EPA published a memorandum concerning the use of green infrastructure in NPDES permits and
enforcement (EPA 2007). Green infrastructure, which includes green roofs, permeable pavement, and
grassy swales to capture runoff, reduces storm water peaks through storage and infiltration, improving
capture for the CSS as a whole. EPA stated that permitting authorities could "encourage permittees to
utilize green infrastructure approaches, where appropriate, in lieu of or in addition to more traditional
controls" and encouraged EPA and state personnel to consider using green infrastructure as a component
of consent agreements in enforcement activities. The permittees would still be required to meet the limits
necessary to achieve water quality standards, but would be allowed to use different approaches from the
more conventional gray infrastructure (such as build more off-line storage or expand POTW capacity).
Greater reliance on green infrastructure might require additional flexibility such as lengthening
compliance schedules. EPA recognized that green infrastructure could be used to "down-size" gray
infrastructure such as tunnels and would provide additional water quality and aesthetic benefits for
communities. EPA also recognized that communities would need time to construct, test, and assess the
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benefits of green infrastructure, which is a relatively new technology. Despite this recognition, the early
consent decrees that included green infrastructure provided limited flexibility to communities for adaptive
implementation of green infrastructure and re-assessment of controls or implementation schedules. This
approach is now being re-assessed with EPA's initiative to allow communities to use integrated planning
to achieve CWA compliance.
In June 2009, the U.S. Conference of Mayors (USCM) held a plenary session at its 77th annual meeting
contending that EPA was requiring unnecessarily costly solutions to limit wet weather overflows. Several
mayors wrote to the EPA Administrator and the Attorney General expressing their concern. In response,
EPA and DOJ began meeting with the USCM Water Council to explore these issues further. In November
2009, the USCM transmitted its paper, titled "Local Government Recommendations to Increase
CSO/SSO Flexibility in Achieving Clean Water Goals," which identified the key areas where it was
argued that EPA was not providing cities with sufficient flexibility, and proposed ways that EPA might
change implementation of the program without requiring any changes to regulations or the CWA. The
USCM and EPA continued meeting, and EPA also began discussions with other stakeholders, including
the state regulatory agencies, about these issues.
In June 2012, EPA issued an Integrated Municipal Storm water and Wastewater Planning Approach
Framework. Under this framework, a municipality may develop an integrated plan incorporating the
following elements:
• Description of the water quality, human health, and regulatory challenges to be addressed;
• Characterization of existing wastewater and storm water systems and performance;
• Provision for stakeholder involvement in planning;
• Process for evaluation of alternatives and selection of an alternative;
• Monitoring to measure performance; and
• Adaptive improvement to the plan over the course of its implementation.
The alternative evaluation element of the framework allows cities to consider cost and benefit as factors
in the phasing and sequencing of controls, to most effectively achieve the requirements of the CWA based
on factors local to the CSO community. These include costs of alternatives, potential disproportionate
financial burdens on portions of the community, projected pollution reductions, benefits to receiving
waters, and other environmental and public health benefits. A systematic approach to evaluating green
infrastructure is also a component of the framework.
4. CWA Implementation and Possible Implications for
Sediment Remediation under Superfund
Contaminated sediment sites are commonly located in urban water bodies where CSOs and separate storm
water discharges are regulated under the CWA. Because of the potential for continuing impacts of those
discharges on sediment contamination, it is important to appreciate and understand relevant CWA
regulatory drivers and processes, and how they may affect Superfund remedial action objectives and
processes. This section discusses the commonalities and differences between the two regulatory
approaches. Because of some of these differences, the effectiveness of Superfund remedies at urban sites
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may depend on successful coordination between the regional CWA and CERCLA programs, throughout
the entire RI/FS and remedy selection and implementation processes.
4.1 Programmatic Goals
Under the CWA, discharges to surface waters are regulated with the objective of protecting designated
uses (such as recreation, cold water fisheries, or drinking water supply) of water bodies. States are
responsible for establishing water quality standards, including designated uses for each water body and
setting numerical and narrative water quality criteria to protect those uses. Depending on the designated
uses, these state standards may or may not include toxic pollutants typically found at Superfund sites.
Point sources (wastewater treatment plant discharges, CSOs, and storm water discharges) are regulated
through NPDES permits with effluent limits established as necessary using these numerical and narrative
water quality criteria, with the goal of maintaining or restoring water quality standards. Allowance is
made for the state of wastewater treatment technology where discharges are subject to technology-based
limits.
Both the CWA and CERCLA aim to protect wildlife populations and people who are potentially exposed
through recreation, but their goals and resulting approaches differ in important ways. Where the CWA
seeks water quality conditions consistent with Act's definition of protection and restoration of fishing,
swimming, and other designated uses, CERCLA is explicitly risk-based, implementing remedies that
reduce exposures to people and biota to protective levels; e.g., cancer risk not to exceed 1 x 10~4. Because
of the difference in objectives, CWA metrics of success may not be sufficient to meet CERCLA cleanup
objectives, even when both are site-specific.
4.2 Media, Contaminants, and Cleanup Objectives
Metrics for developing a successful LTCP for CSOs include reducing the frequency that bacterial counts,
nutrients, or solids exceed threshold values to protect recreation, preventing depletion of dissolved
oxygen, and protecting fisheries. An LTCP for a specific CSS may presume that other sources of
pollutants in the watershed will also ultimately be addressed.
In contrast, contaminated sediment cleanups target existing contamination, typically including a major
component of legacy contamination previously released to the water body over a period of years.
Exposures via sediments and pathways originating in sediments are targeted by CERCLA, with the intent
of protecting human health and the environment. This intent focuses CERCLA remedies on a different set
of contaminants, often those having persistent and bioaccumulative toxicity to human health and the
environment, commonly including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls
(PCBs), heavy metals, pesticides, and dioxins and furans. In contrast to presumptive measures that may
be imposed under the CWA, CERCLA controls are demonstrative: a CERCLA remedy is not complete
until the achievement of remedial action objectives and contaminant-specific remediation goals is
demonstrated through long-term monitoring results.
While persistent bioaccumulative contaminants may also be regulated under the CWA, they are rarely the
primary drivers for regulatory compliance for CSOs, and may not even be monitored. In these situations,
CSOs and separate storm water could result in recontamination of Superfund sites. There is also a greater
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emphasis under CERCLA on the ecological risks to benthos living in or on the sediment, in contrast to the
direct water column exposure that is the key exposure pathway evaluated under the CWA.
4.3 Sources, Controls and Site Management
Under the CWA, the regulatory process to achieve WQS typically includes a sequence of shorter and
longer-term controls. In the case of CSOs, permittees are first required to demonstrate the use of best
management practices, in the form of addressing the nine minimum controls. Permittees are then required
to develop and implement LTCPs, which incorporate more substantial and time-consuming public works
investments, targeting ultimate attainment of specific water quality criteria or state-specific standard
consistent with the designated uses of the water body. For larger communities, these controls can cost
from hundreds of millions to billions of dollars, depending in part on the financial capability of the
community. CSO controls are implemented over a period of up to 20 years, so the timing of CSO controls
may not coincide with the timing of CERCLA remedies.
Furthermore, it is anticipated that there will continue to be some level of CSO discharges, even after the
LTCPs are fully implemented. It is therefore possible for a community to continue to discharge
contamination that constitutes a source from the perspective of sediment contamination. Under the CWA,
controls are typically established with the intent of meeting water quality standards over time, and not to
prevent recontamination of a sediment site or to help meet sediment cleanup levels at the time of the
Superfund remediation.
CSOs controls are designed to minimize wet-weather overflows, and not to eliminate them in a "typical
year." Water quality impairments may consist of transitory problems, such as dissolved oxygen depletion
or elevated bacterial levels, in the sense that impairments are removed when pollutant loads are
effectively controlled. In contrast, contamination of sediments by metals and persistent hydrophobic
chemicals is typically a long-term problem. This makes it imperative that sources be controlled to the
maximum extent practicable for effective sediment remediation.
CERCLA risk management actions consider 11 principles (EPA 2002b), the first of which is to "Control
sources early." As compared with CWA management actions, there is greater priority and urgency
assigned to the cessation of contaminant releases under CERCLA. CERCLA also takes more of a once-
and-for-all approach to remediation, as compared with the phasing of controls under the CWA. While the
CERCLA framework provides for removal and interim actions, the typical course of response culminates
in a final remedy, attaining and demonstrating a reduction in risk to acceptable levels. Because of these
differences in goals and timing of remedies, more attention is being paid to the potential for the
recontamination of sediment sites by CSOs and storm water discharges.
After controls have been implemented, the methods of demonstrating regulatory compliance also differ
between remedial actions for CERCLA sediment sites and LTCPs. The success of CSO controls is most
commonly evaluated in terms of achieving target reductions in the frequency of overflow events and in
overflow volume, and not in terms of reduction in risks. Success of a LTCP may be demonstrated based
on water quality modeling that shows CSOs no longer are predicted to be causing or contributing to
violations of WQS during the typical period being simulated. These demonstrations may also assume
other reductions in watershed contaminant loads. Although EPA has indicated that water quality sampling
should also be performed for CSO post-construction monitoring programs, the evaluation of WQS
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typically relies instead on modeling overflows and predicting their impacts on water quality. In contrast,
post-construction and long-term monitoring of sediment is typically required after contaminated
sediments have been remediated under CERCLA. These data are collected to confirm both remedy
effectiveness and risk reduction and whether any additional remedial action is needed as part of the
CERCLA five-year review process.
4.4 Cost Considerations
Remedies and controls to address contaminated sediments, CSOs, and other permitted discharges can be
costly: costs for large sediment site remedies and for CSO controls for major cities can both total
hundreds of millions and even billions of dollars. These costs are considered somewhat differently under
CWA regulation of CSOs and storm water than under CERCLA.
Cost and affordability are taken into account in negotiating LTCPs, especially with respect to timing. Cost
can also affect the extent of load reduction through the knee-of-the-curve analysis. Funding for CSO
activities comes from the public via payments for water and sewer services. Rate payers are assessed fees
over the life of the project to finance the development and implementation of required controls and to pay
for long-term debt obligations for the water and sewer infrastructure. The ability of a community to pay
for these controls is considered during the LTCP process and is an important reason why the time to
implement new source control actions can be up to 20 years.
In contrast, costs for Superfund sediment sites (with the exception of orphan sites) are borne by one or
more parties deemed to be responsible for the contamination. Cost is considered as a balancing criterion
under CERCLA in evaluating a remedial action, but only after the level of risk reduction to be attained by
an alternative adequately satisfies the threshold evaluation criterion of overall protection of human health
and the environment. Affordability by the responsible parties may affect the allocation of costs for each
party, but is not explicitly considered in remedy selection.
In practice, both CWA- and CERCLA-based actions consider that technologies may not be sufficiently
advanced to allow for achievement of desired endpoints (immediate attainment of water quality standards
under the CWA, or achievement of risk-based protective levels under CERCLA). Remedies can still
result in concentrations that achieve substantial risk reductions for sediment sites, where existing
technologies are unable to meet a risk-based target concentration. Likewise, where complete control of
discharges is infeasible under the CWA (such as in CSO control), long-term control plans are often
developed to minimize CSO discharges under a "typical year," allowing greater discharges to continue
during the largest storm events and more extreme years.
4.5 Contamination/Recontamination by CSOs and
Storm Water Outfalls
Because the CWA does not require complete control of CSO or storm water loadings to surface waters,
the potential for these loadings to contaminate sediments or to recontaminate them after a remedy is
implemented can be significant. The crucial elements to consider are what contaminants are present in
discharges, what mass loadings occur prior to expected CSO and storm water controls, and what are the
extent and timing of load reductions that are expected under planned controls.
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If there is a CSO LTCP in place, its documentation is likely to provide much of the information needed
by the Superfund site manager to understand the potential for sediment contamination and consider these
impacts in remedy selection. LTCPs usually include estimates of typical year flows and loads of target
contaminants, before and after implementation, although RPMs may need to request additional
information about Superfund contaminants. Target contaminants for the LCTP may differ from the set
that is targeted for Superfund remediation, in which case CSO loading data for the latter may not exist. If
so, to estimate wet weather loadings of those contaminants under current conditions, additional
monitoring of CSOs may be necessary as part of the RI performed under CERCLA. That information can
then be used, in combination with projected capture rates under the LTCP remedy, to estimate future CSO
loads of sediment contaminants. LTCPs also provide a time line of improvements, which can be used to
estimate timing of source control in relation to the timing for the Superfund remediation. In general, it is
more challenging to predict future contaminant loads for storm water outfalls than for CSOs for two
reasons: first, because storm water controls rely more heavily on BMPs than on modeling-based
engineering controls; and second, because storm water controls are more fragmented than CSO controls.
A solution would be to monitor representative outfalls for contaminants of concern under varying wet-
weather conditions as part of the RI, to establish baseline loads, and then model watershed reductions
through the application of BMPs, based on any available values from published literature.
4.6 Need for Improved Coordination and Integration of CWA
Regulation of Waterbodies and CERCLA Remediation
at Sediment Sites
This fact sheet highlights some commonalities and differences within both the CWA and CERCLA
frameworks as they relate to contaminated sediment sites. It is not intended to provide resolution or
specific recommendations where different objectives or approaches may make it challenging to achieve
success from either regulatory perspective. However, it is reasonable that where CERCLA and CWA
have similar objectives, agency staff carrying out their mandates seek greater consistency in approaches
between the two legislative frameworks, to the extent allowable by law and regulation.
Coordination between programs can be challenging, and to date CSO long-term control planning has
proceeded without substantial regard to CERCLA concerns. However, the CWA and CERCLA domains
are intersecting with increased frequency on contaminated sediment sites, offering the opportunity for
improved integration, including increasing collaboration between EPA and state CWA program
managers, CWA permittees, and responsible parties under CERCLA. Superfund site managers are
encouraged to work with their counterparts in the state and EPA water programs to consider the need for
conducting one of more of the following activities pertaining to the site waterbody:
• Change the designated use in the WQS to one that is more protective with respect to food chain
exposures; for example, risks from fish consumption. This change would require the state to
"review and revise" the WQS and develop additional decreases in discharges.
• Develop waterbody-specific water quality criteria as part of a revised WQS.
• Provide access to responsible party and EPA contractors to collect end-of-the-pipe monitoring
data from NPDES-permitted outfalls.
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In the event of success in changing the designated use and waterbody-specific water quality criteria to
reflect the mitigation of risks that drive the Superfund process, then it becomes possible for management
actions under the CWA to support attainment of CERCLA goals through activities like the following:
• Require NPDES permittees to monitor their discharge for the key contaminants of concern that
are driving the need for a Superfund cleanup.
• When TMDLs are developed or revised, give priority to those TMDLs for waterbodies containing
Superfund sediment sites.
• For outfalls found to be discharging a potentially significant load of one or more hazardous
substances, issue a new NPDES permit with stricter controls.
As stated previously, this document provides a brief synopsis of the key EPA guidances and policies
describing the implementation of CWA requirements that may affect the success of sediment cleanups
under Superfund. Agency-wide efforts are under way to increase the level of coordination and
collaboration between regulatory programs. Superfund site managers are encouraged to work closely with
their EPA and state counterparts in the water programs.
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5. References
Kosco, J., and others. 2003. Lessons Learned from In-Field Evaluations of Phase I Municipal Stormwater
Programs.
Moffa, P.E. (editor). 1997. Control and Treatment of Combined Sewer Overflows. 2nd Edition. New
York: Van Nostrand Reinhold.
National Research Council, 2008. Urban Stormwater Management in the United States.
U.S. Environmental Protection Agency (EPA). 1992. Draft CSO Control Policy. December 22.
EPA. 1994. Office of Water. Combined Sewer Overflow (CSO) Control Policy. EPA 830-94-001.
EPA. 2000. Office of Enforcement and Compliance Assurance (OECA). Memorandum from Steven A.
Herman to Water Management and Enforcement Division Directors and Regional Counsels.
"Compliance and Enforcement Strategy Addressing Combined Sewer Overflows and Sanitary Sewer
Overflows." April 27.
EPA. 2001. Guidance: Coordinating Combined Sewer Overflow (CSO) Long-Term Planning with Water
Quality Standards Reviews. EPA 833-R-01-002. www.epa.gov/npdes/pubs/wqs_guide_final.pdf
EPA. 2002a. Office of Water. Report to Congress on Implementation and Enforcement of the CSO
Control Policy. EPA 833-R-01-003. http://cfpub.epa.gov/npdes/cso/cpolicv report.cfm
EPA. 2002b. Principles for Managing Contaminated Sediment Risks at Hazardous Waste Sites. OSWER
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EPA. 2004. Office of Water. Report to Congress - Impacts and Control of CSOs and SSOs. EPA 833-R-
04-001. http://cfpub.epa. gov/npdes/cso/cpolicy_report2004 .cfrn
EPA, 2005. Office of Solid Waste and Emergency Response. Contaminated Sediment Remediation
Guidance for Hazardous Waste Sites. EPA 540-R-05-012. OSWER 9355.0-85. December 2005.
www.epa.gov/superfund/health/conmedia/sediment/pdfs/guidance.pdf
EPA. 2007. Office of Water. Report to Congress - Combined Sewer Overflows to the Lake Michigan
Basin. EPA 833-R-07-007. www.epa.gov/npdes/pubs/cso_reporttocongress_lakemichigan.pdf
EPA. 2012. CSO Post-Construction Compliance Monitoring Guidance. Office of Wastewater
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United States
Environmental Protection
Agency
Office of Superfund Remediation and
Technology Innovation
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OSWER Directive 9200.1-116-FS
December 2013
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