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CONTENTS
Page Numbers:
PURPOSE OF THIS REPORT 1
INTRODUCTION 2
LEGISLATIVE BACKGROUND 3
SDWA Prior to the 1986 Amendments 3
SDWA Amendments of 1986 6
Summary of Key Changes 7
MCL Determination from the SDWA 9
ESTABLISHING AN MCL 1 1
Application of MCLs to Regulation 1 1
Setting MCLGs 1 1
Setting MCLs 1 7
Example: MCLG/MCL Determination for P-dcb 20
GLOSSARY OF ACRONYMS 2 3
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Disclaimer
This report was furnished to the U. S. Environmental Protection
Agency by the graduate student identified on the cover page, under
a National Network of Environmental Policy Studies fellowship.
The content* are essentially as received from the author. The
opinions, findings, and conclusions expressed are those of the author
and not necessarily those of the Environmental Protection Agency.
Mention, if any, of company, process, or product names is not to be
considered as an endorsement by the U. S. Environmental Protection
Agency.
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PURPOSE OF THIS REPORT
This work was conducted as part of the National Network for
Environmental Policy Studies (NNEPS) intern program. The
document has been reviewed by personnel in the Office of Drinking
Water and the Water Policy Office within the Office of Water at the
Environmental Protection Agency (EPA) for accuracy and
appropriateness. Viewpoints and opinions expressed do not
necessarily represent those of the EPA.
Amendments to the Safe Drinking Water Act (SDWA) in 1986
greatly expanded the list of contaminants for which the EPA must
establish safe levels in drinking water. These Maximum Contaminant
Levels (MCLs) are developed by the Office of Drinking Water (ODW)
at EPA through the application of a number of criteria and
procedures. In an effort to develop a clearer understanding of how
this process works, research was conducted by a summer intern in
the Water Policy Office at EPA .on the Safe Drinking Water Act and
protocols used in developing regulations for particular contaminants.
The information in this report has been compiled from that research.
This paper is intended to provide a descriptive report on the
methodology used by EPA to develop MCLs for contaminants in
drinking water. It should serve as a useful tool in understanding the
approach used to define MCLs and the factors applied in establishing
a given number (concentration) for a particular contaminant.
Background information on the development of the legislation is
provided to enhance the reader's perspective on how the concept of
MCLs has changed with recent modifications to the Safe Drinking
Water Act.
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INTRODUCTION
The Safe Drinking Water Act was passed in 1974 after several
years of work by Congress to develop a nationwide program to
protect the quality of the country's public water supply system.
Until that time, the Public Health Service had developed drinking
water standards for several contaminants, though these only applied
to interstate carriers of water. Passage of the 1974 legislation placed
responsibility for the establishment of national drinking water
standards upon the Environmental Protection Agency.
EPA took initial responsibility for enforcement of drinking
water regulations. Enforcement duties were then transferred to the
States as their drinking water programs were approved and they
were given primacy. Primacy requirements include the setting of
state standards at least as stringent as those set by EPA. Only a few
states have not yet received primacy.
EPA currently establishes Maximum Contaminant Level Goals
(MCLGs) for drinking water by setting standards for a level at which
"no known or anticipated adverse effects on the health of persons
occur and which allows an adequate margin of safety." These levels
are used to develop Maximum Contaminant Levels (MCLs) which are
set as close to the MCLGs as "feasible". Feasible is defined in the Safe
Drinking Water Act as "feasible with the use of the best technology,
treatment techniques and other means which the Administrator
finds, after examination for efficacy under field conditions and not
solely under laboratory conditions, are available (taking cost into
consideration)."
In order to understand how this language was developed and
the intention of Congress in the amendments to the SDWA in 1986,
excerpts from the legislative history are reviewed and analyzed to
provide background.
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LEGISLATIVE BACKGROUND
SDWA Prior to the 1986 Amendments
**'
Growing concern over the lack of knowledge about harmful
contamination of drinking water and the potential for substantial
negative impacts on the human population prompted Congress to
amend the Public Health Service Act in 1974. The House Report to
Congress on the initial SDWA of 1974 clearly illustrates the intent to
protect human health and develop more stringent regulations for
drinking water:
"The purpose of this legislation is to assure that water
supply systems serving the public meet minimum national
standards for protection of public health."
Primary drinking water standards were intended to protect the
public "to the maximum extent feasible" and the Administrator of
EPA was charged with identifying contaminants which "have an
adverse effect on the health of persons." This language is further
clarified by the Committee on Interstate and Foreign Commerce in
the following excerpt:
"...the Committee did not intend to require conclusive
proof that any contaminant will cause adverse effects as a
condition for regulation of a specific contaminant. Rather, all
that is required is that the Administrator make a reasoned and
plausible judgement that a contaminant may have such an
effect."
That judgement is to be based on "epidemiological, lexicological,
physiological, biochemical, or statistical research or studies or
extrapolations therefrom." This broad based discretion enables the
Administrator to use a number of criteria in developing the list of
contaminants and was intended to allow for regulation of groups of
chemicals as well as specific constituents.
Once the list of contaminants has been developed, it is
necessary to develop an actual number which serves as the national
standard for a particular contaminant. The House Report states:
"The only circumstance in which a maximum contaminant
level is not to be prescribed is if he (the Administrator) finds
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that it is not technologically or economically feasible for most
public water systems to monitor for that contaminant."
If such a finding is made, the Administrator is then required to list
all known treatment technologies which remove that contaminant
and require that at least one of those technologies be employed by
the public water system. This forms a two stage process whereby an
MCL for a contaminant is specified, or if such determination cannot
be made, a technology is then prescribed which is known to
effectively control for that contaminant (in lieu of an actual number).
The standard/technology approach remains the backbone of the
SDWA, with priority placed on the protection of public health.
The House Committee felt that inadequate information on
health effects of contaminants in drinking water was a deficiency
which called for more scientific study. The 1974 Act mandated that
the Administrator arrange with the National Academy of Sciences
(NAS) to conduct studies on the maximum contaminant levels which
should be allowed in drinking water. Congress further specified "the
NAS is directed to consider only what is required for protection of
public health, not what is technologically or economically feasible or
reasonable." The consideration of feasibility was left to the EPA:
"Economic and technological feasibility are to be
considered by EPA and then only for the purpose of
determining how soon it is possible to reach recommended
maximum contaminant levels and how much protection of the
public health is feasible until then."
Information from the study done by the NAS was then to be used by
EPA to establish Recommended Maximum Contaminant Levels
(RMCLs). The RMCLs were intended to be health goals which would
"prevent the occurrence of any known or anticipated health effects
with an adequate margin of safety." Language in the House Report
delineates the difference between "adequate margin of safety" and
"known or anticipated health effects". It directs the Administrator to
establish RMCLs by a three step process:
• "The known adverse health effects of contaminants
are to be compiled."
• "The Administrator must decide whether any adverse
effects can be reasonably anticipated, even though not
proved to exist. [It is at this point that the
Administrator must consider the possible impact of
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synergistic effects, long-term and multi-media
exposures, and the existence of more susceptible
groups in the population.]"
• "The recommended maximum contaminant level must
be* set to prevent the occurrence of any known or
anticipated adverse effect."
If unable to establish a safe threshold for a particular contaminant, it
was specified that the RMCL for that contaminant should be set at
zero. This is in accordance with the requirement to include an
adequate margin of safety in setting the RMCL.
It was required that revised national drinking water
regulations be proposed at the time of promulgation of RMCLs. These
revised regulations were to "specify the contaminant level (or
treatment methods if monitoring is infeasible) which provides
maximum feasible protection for human health, using generally
available methods of treatment or control."
In gauging how the Safe Drinking Water Act was implemented
and the initial progress made after its passage, it is worthwhile to
examine the testimony of Thomas C. Jorling during hearings on
reauthorization of SDWA in 1979. Jorling was then Assistant
Administrator for Water and Waste Management at EPA. At that
time, the States were doing well in revising their laws and meeting
federal guidelines to achieve primacy. In March of 1979, forty states
had received primary enforcement responsibility and five more were
expected to achieve that status before the end of the year. While
Jorling accentuated the progress that had been made, he pointed out
that "the legislatively mandated research and other studies have
clearly established that we are a long way from eliminating all
concerns about drinking water."
Another point which was highlighted was the recognition that
organic chemicals constituted one of the major threats to health from
drinking water:
"About one-half of our research has been invested in
monitoring techniques, health effects, control technology and
costs, and economic impacts related to the control of organic
contaminants in drinking water."
Mention was made of the use of Granular Activated Carbon (GAC) as
a control technology which would effectively remove organics. The
inability to determine specific standards for a number of organics
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focused attention on the requirement of control technology instead of
a maximum contaminant level.
Commenting on the work of the NAS in developing health
effects information, Jorling said "...we must rely primarily on the
generally accepted scientific interpretation of the results of animal
feeding studies." Information from animal studies remains an
important facet in the development of MCLs today.
The SDWA Amendments of 1986
The expanding list of contaminants in drinking water and
acknowledgement of their potential threat to public health created
an urgency to regulate them more comprehensively. This was the
basic theme underlying the changes which Congress made to the
SDWA in 1986. A review of the legislative history illustrates a
dissatisfaction on the part of several congressmen regarding the
speed with which EPA was promulgating regulations. Senator
Durenberger wrote in the Conference Report:
"It is now 12 years later (since passage of the 1974 Act)
and the Safe Drinking Water Act once again comes to the floor
of the Senate with most of the original promise unfulfilled.
...the Environmental Protection Agency has set standards for
only a handful of contaminants..."
In the Senate Committee's discussion of the SDWA Amendments of
1986, it is clear that the objective of changes in the law was to
expedite the process of establishing standards. Furthermore, a
review process was designed to "make them (regulations) more
protective of public health whenever possible." The Committee
added a clarification on the use of technology to insure adequate
protection of public health from drinking water:
"While cost and technology are factors to be considered
in establishing maximum contaminant levels under the Act, the
first priority of the Act is to protect human health by reducing
or preventing human exposure to potentially harmful
contaminants in drinking water."
The House Committee's version of the bill did not differ
substantially from that of the Senate. Under the "Basis for standard
setting" section, the House amendment included a requirement that
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the Agency use adsorption techniques such as granular activated
carbon (GAC) in defining best available technology which is feasible
for the control of synthetic organic chemicals (SOCs) for purposes of
establishing an MCL. The conference agreement incorporated this
language with that from the Senate and provided that any treatment
technology for the control of SOCs be at least as effective as GAC.
Summary of Kev Changes
The congressional intent underlying the SDWA amendments
has been discussed briefly. Substantive changes which have
relevance to the methodology of setting MCLs are listed below. A
summary of each of those changes is then included.
1. Mandatory deadlines set for the regulation of 83 i:ey
contaminants.
2. Substitutions are allowed for seven of the 83
contaminants on the list.
3. A change in the use of the term "Best Technology
Generally Available" to "Best Available Technology".
4. Elimination of study done by the NAS and addition of
review of regulations by the Science Advisory Board
(SAB).
5. Change in language from "Recommended Maximum
Contaminant Level" (RMCL) to "Maximum Contaminant
Level Goal" (MCLG).
6. Proposal of MCLG and MCL at the same time.
7. Establishment of a benchmark for treatment
technologies.
8. Periodic review of regulations.
1. Congress established deadlines for the promulgation of
regulations for 83 contaminants which wn.-e taken from a list which
EPA had been working on. The schedule .* setting MCLGs and
promulgation of national primary drinking water regulations is as
follows:
A) Not later than 12 months after the enactment of the
Safe Drinking Water Act Amendments of 1986 for not
less than 9 of those listed contaminants;
B) not later than 24 months after such enactment for not
less than 40 of those listed contaminants;
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C) not later than 36 months after such enactment for the
remainder of such listed contaminants.
2. Congress recognized that EPA might find contaminants not on
the list which posed a greater immediate threat to public health than
those for which "the deadlines applied. EPA was therefore allowed to
substitute as many as seven contaminants for any of those on the
list. If a contaminant i< substituted, the schedule for the one it
replaces applies to the substitution.
3. The original SDWA used the language "generally available" in
reference to the type of technology to be considered for removal of
contaminants. The amendments deleted this reference and directed
the Administrator to consider the "best technology, treatment
techniques and other means after examination for efficacy under
field conditions and not solely under laboratory conditions, are
available (taking cost into consideration)."
4. The role of the National Academy of Sciences was changed
from actually conducting scientific studies to providing guidance to
the Agency as EPA conducts risk assessments and establishes MCLGs.
The amended Act also requires that "The Administrator shall request
comments from the Science Advisory Board (established under the
Environmental Research, Development, and Demonstration Act of
1978) prior to proposal of a maximum contaminant level goal...".
These comments are to be considered by EPA but review by SAB
may not be used to delay final promulgation of a standard.
5. "Recommended Maximum Contaminant Levels" (RMCLs)
were changed to "Maximum Contaminant Level Goals" (MCLGs) to
reflect the health goal nature with which they are established. The
language change did not functionally change their meaning.
6. Under the 1974 SDWA, EPA issued RMCLs prior to
promulgating final MCLs. The 1986 Amendments require that
MCLGs and MCLs be proposed and finalized at the same time.
7. The Act is amended specifies that granular activated carbon
is available for the removal of synthetic organic compounds. This
establishes a benchmark for other technologies which must be at
least as effective as GAC.
8. Besides reviewing regulations every 3 years, EPA is directed
under the. new law to "include an analysis of innovations or changes
in technology, treatment techniques or other activities that have
occurred over the previous 3-year period and that may provide for
greater protection of the health of persons."
These changes have direct and indirect impact on the way in
which maximum contaminant levels are developed. Specific
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language from the Safe Drinking Water Act, 1986 (as amended) is
reprinted below to illustrate portions of the law which direct EPA on
the criteria to be used in establishing MCLs.
MCL Determination from the SDWA. 1986 (as amended")
Part A—Definitions
Section 1401
(1) The term "primary drinking water regulation" means
a regulation which-
(B) specifies contaminants which, in the judgement of
the Administrator, may have any adverse effect on the
health of persons;
(C) specifies for each contaminant either--
i) a maximum contaminant level, if, in the
judgement of the Administrator, it is economically
and technologically feasible to ascertain the level of
such contaminant in water in public water systems,
or
ii) if, in the judgement of the Administrator, it is
not economically or technologically feasible to
ascertain the level of such contaminant, each
treatment technique known to the Administrator
which leads to a reduction in the level of such
contaminant sufficient to satisfy the requirements
of section 1412.
(3) The term "maximum contaminant level" means the
maximum permissible level of a contaminant in water
which is delivered to any user of a public water system.
(6) The term "contaminant" means any physical, chemical,
biological or radiological substance or matter in water.
Part B--Public Water Systems
Section 1412-National Drinking Water Regulations
(b)(4) Each maximum contaminant level goal
established under this subsection shall be set at the
level at which no known or anticipated adverse effects
on the health of persons occur and which allows an
adequate margin of safety. Each national primary
drinking water regulation for a contaminant for which a
maximum contaminant level goal is established under
this subsection shall specify a maximum level for such
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language from the Safe Drinking Water Act, 1986 (as amended) is
reprinted below to illustrate portions of the law which direct EPA on
the criteria to be used in establishing MCLs.
MCL Determination from the SDWA. 1986 (as amended)
Part A—Definitions
Section 1401
(1) The term "primary drinking water regulation" means
a regulation which—
(B) specifies contaminants which, in the judgement of
the Administrator, may have any adverse effect on the
health of persons;
(C) specifies for each contaminant either-
i) a maximum contaminant level, if, in the
judgement of the Administrator, it is economically
and technologically feasible to ascertain the level of
such contaminant in water in public water systems,
or
ii) if, in the judgement of the Administrator, it is
not economically or technologically feasible to
ascertain the level of such contaminant, each
treatment technique known to the Administrator
which leads to a reduction in the level of such
contaminant sufficient to satisfy the requirements
of section 1412.
(3) The term "maximum contaminant level" means the
maximum permissible level of a contaminant in water
which is delivered to any user of a public water system.
(6) The term "contaminant" means any physical, chemical,
biological or radiological substance or matter in water.
Part B--Public Water Systems
Section 1412--National Drinking Water Regulations
(b)(4) Each maximum contaminant level goal
established under this subsection shall be set at the
level at which no known or anticipated adverse effects
on the health of persons occur and which allows an
adequate margin of safety. Each national primary
drinking water regulation for a contaminant for which a
maximum contaminant level goal is established under
this subsection shall specify a maximum level for such
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contaminant which is as close to the maximum
contaminant level goal as is feasible.
(5) For the purposes of this subsection, the term
"feasible" means feasible with the use of the best
technology, treatment techniques and other means which
the Administrator finds, after examination for efficacy
under field conditions and not solely under laboratory
conditions, are available (taking cost into consideration).
(7)(A) The Administrator is authorized to promulgate a
national primary drinking water regulation that requires
the use of a treatment technique in lieu of establishing a
maximum contaminant level, if the Administrator makes
a finding that it is not economically or technologically
feasible to ascertain the level of the contaminant.
These excerpts represent significant portions of the law which have
relevance to the setting of MCLs.
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ESTABLISHING AN MCL
Application of MCLs to Regulation
•*'
As previously cited, the Safe Drinking Water Act requires that
EPA establish Maximum Contaminant Level Goals (MCLGs) "at the
level at which no known or anticipated adverse effects on the health
of persons occur and which allow an adequate margin of safety."
These are health based goals and are non-enforceable. Maximum
Contaminant Levels (MCLs), on the other hand, are enforceable
standards developed from the MCLGs and set as close to them as
feasible. Whereas MCLGs consider only potential health effects, MCLs
are set by taking into account the; best technology available and the
cost of implementing that technology. To understand how MCLs are
developed, it is first necessary to understand the procedure for
establishing MCLGs.
Setting MCLGs
EPA bases MCLGs on available health effects information which
indicates whether or not a particular contaminant causes cancer.
Consideration of the potential health effects of a chemical includes
the suitability of available data for assessing toxicity and the
possibility of human health concern from exposure to the chemical in
drinking water. For substances considered to be "known" or
"probable" carcinogens, EPA sets the MCLGs at zero. For substances
which are considered "possible" carcinogens, EPA sets MCLGs based
on chronic toxicity data with an additional margin of safety or on
noncarcinogenic risk models.
EPA guidelines for risk assessment include a classification
system for chemicals based on evidence of carcinogenicity. This
system arranges categories of chemicals into five separate groups:
Group A: Human Carcinogen
This group denotes chemicals for which there is sufficient
evidence from epidemiological studies that a causal connection exists
between exposure to the chemical and cancer.
Group B: Probable Human Carcinogen
This group is further subdivided into groups Bl and B2.
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Bl: Used to designate agents for which there is
"limited" evidence of carcinogenicity from epidemiologic studies and
includes agents for which animal evidence is sufficient.
B2: Used to designate agents for which there is
sufficient evidence from animal studies but inadequate or no data
from epidemiologic studies.
Group C: Possible Human Carcinogen
This group is used for agents which show limited
evidence of carcinogenicity in animals in the absence of human data.
Specific evidence might include any of the following:
a) malignant tumor response in a well-conducted
experiment that does not meet conditions for sufficient evidence.
b) tumor responses of marginal statistical significance
in studies having inadequate design or reporting.
c) benign tumors with an agent showing no response
in a variety of short-term tests for mutagenicity.
d) responses of marginal statistical significance in a
tissue known to have a high or variable background rate.
Group D: Not Classified
This group is used for agents for which there is
inadequate human and animal evidence of carcinogenicity or for
which no data is available.
Group E: Evidence of Non-carcinogenicity for Humans
This group is used for agents which show no evidence of
carcinogenicity in at least two animal studies or in both adequate
epidemiologic and animal studies.
In setting MCLGs, EPA uses a three category approach which
incorporates the groups described above:
CATEGORY I-used for chemicals which show strong
evidence of carcinogenicity (Group A and Group B).
CATEGORY II--used to designate those chemicals for
which there is equivocal evidence of carcinogenicity
(Group C).
CATEGORY Ill-used to set MCLGs for chemicals for which
there is inadequate or no evidence of carcinogenicity
(Group D and Group E).
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CATEGORY I
EPA originally considered three options for setting MCLGs for
carcinogens. They were: 1) set the MCLGs at zero, 2) set the MCLGs
at the analytical detection limit and 3) set the MCLGs at a non-zero
level based upon calculated negligible contribution to lifetime risk.
Based upon EPA's analysis and public comments, the Agency chose to
set MCLGs for Category I contaminants at zero. Setting the MCLG at
zero is based on the fact that there is no demonstrated threshold for
carcinogenic health effects. EPA's rationale lies in the mandate of the
SDWA which requires that MCLGs be established "at the level at
which no known or anticipated adverse effects on the health of
persons occur and which allows an adequate margin of safety." Since
no threshold can be established for carcinogens, setting the MCLG at
zero is considered to fulfill the congressional mandate to provide an
"adequate margin of safety."
CATEGORY D
Category II includes contaminants for which there is some
limited evidence of carcinogenicity from animal studies. MCLGs are
set based upon non-carcinogenic toxicity data (the DWEL) divided by
an additional uncertainty factor to account for potential carcinogenic
risk.
CATEGORY IE
For contaminants where there is inadequate or no evidence of
carcinogenicity, MCLGs are set by using a "no-effect" level or
Reference Dose (RfD). The RfD is used to set MCLGs for both Category
II and III contaminants and is calculated for chronic periods of
exposure, including a margin of safety. The RfD is then used to
calculate a Drinking Water Equivalent Level (DWEL), which
represents a medium specific (drinking water) lifetime exposure at
which non-carcinogenic health effects are not anticipated to occur.
Definitions of terms are provided below and the procedure for
setting MCLGs for CATEGORY II and III contaminants follows:
RfD--formerly termed the Acceptable Daily Intake (ADI),
the RfD represents a no-effect level for chronic periods of exposure
to a contaminant from all sources. It is measured in units of
mg./kg./day.
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No-observed-adverse-effect-level (NOAEL)--this
term represents the level of contaminant, after a period of exposure,
at which there is no adverse effect observed in laboratory studies of
animals or occupational/experimental results from humans. It is
based on the principle that most biological effects of chemical
substances occur after some threshold dose has been reached.
Lowest-observed-ad verse-effect-level (LOAEL)--
similar to the NOAEL, it represents the lowest level of contaminant,
after a period of exposure, at which there is some observed adverse
effect.
Uncertainty factor-because the NOAEL and the LOAEL
are often based on scientific studies of animal populations which are
subject to variability, these values are usually divided by some
uncertainty factor to account for their indefinite nature. Uncertainty
factors are used to adjust for intra/interspecies variability, the small
number of animals tested compared to the size of the exposed
population, sensitive subpopulations, and possible synergistic effects
between chemicals. The magnitude of uncertainty factors varies
according to the nature of the data from which the NOAELs and
LOAELs are derived. A summary of the guidelines used to determine
uncertainty factors is taken from the November 13, 1985 proposal
for National Primary Drinking Water Standards for Synthetic Organic
Chemicals (50 FR 46946):
Uncertainty Factor Guideline
1 0 Used with valid experimental results on
appropriate durations of exposure in
humans.
100 Used when human data are not
available and extrapolating from valid
results of long-term studies in animals.
1000 Used when human data are not
available and extrapolating from studies
in animals of less than chronic
exposures.
1-10 Additional uncertainty factor applied
when using a LOAEL instead of a NOAEL.
DWEL--the drinking water equivalent level converts the
reference dose to a concentration level in water by factoring in the
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weight of an adult (70 kg.) at a consumption level of 2 liters of water
per day.
RSC--the relative source contribution is the proportion of
a contaminant contributed by a particular source (water) relative to
other sources (air and food).
Reference Dose (RfD) and Drinking Water Equivalent Level
(DWEL) Calculation:
RfD = (NOAEL or LOAEU = mg./kg. body wt./day
(Uncertainty Factor[s])
The RfD is then used to calculate a Drinking Water Equivalent
Level (DWEL) which assumes 100% exposure (to a contaminant) from
drinking water. The DWEL is calculated as follows:
DWEL = (RfD) (Body weight in kg.1 = mg./liter
(Drinking water volume
in liters/day)
Where:
Body weight = assumed to be a 70 kg. adult.
Drinking water volume = assumed to be 2 liters/day for
an adult.
MCLG Calculation:
Finally, an MCLG is calculated by subtracting from the DWEL
any contribution from other sources of exposure such as air or food.
If sufficient data on the Relative Source Contribution (RSC) of each of
these media is available, then the MCLG is calculated as follows:
MCLG = (DWEL) - % contribution - % contribution
from food • from air
If sufficient data are not available on RSCs, the MCLG is set by
using an estimate of the drinking water contribution:
MCLG = (DWEL) x % drinking water contribution
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The % drinking water contribution is an estimate based on
professional judgement. Good daca is generally available for
inorganic chemicals based on studies by the Food and Drug
Administration (FDA) and other surveys. Data for organic chemicals
is usually not available. EPA typically uses a value of 20% for the
RSC where adequate data is not available. This is considered to be
reasonably conservative and protective of public health. Where
available data suggest a higher relative source contribution for a
particular contaminant, the value of 20% is adjusted upwards to
reflect a greater contribution from drinking water.
Where drinking water is responsible for all of the exposure,
EPA assigns an RSC of 80%. The use of an 80% "ceiling" is considered
to allow for the contingency of exposure via air, food and other
sources that may not be reflected in the available data. EPA is
considering a 20% "floor" for relative source contributions when the
RSC is between 0 and 20%. The Agency feels that a more stringent
MCLG based on an RSC below 20% would not result in increased
health benefits, since most of the exposure to the contaminant is
from other sources.
Summary
Carcinogens
• MCLGs for carcinogens are set at zero.
Non-carcinogens
• MCLGs are set by utilizing a "no-effect" Reference Dose.
• The RfD is used to calculate a Drinking Water
Equivalent Level.
• The Relative Source Contribution for the contaminant
is applied to the DWEL and an MCLG is calculated.
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Setting MCLs
As noted earlier, EPA is required to set MCLs as close to MCLGs
as is feasible. In considering what the best available technology is to
set a particular MCL (what is feasible), EPA is allowed to select any
treatment technology which has been demonstrated to be effective
for removal of the contaminant beyond laboratory testing (under
field conditions). In establishing an MCL, EPA includes consideration
of a variety of factors. These include:
Treatment Technology and Cost
• availability and performance of BAT
• costs of specific technologies to large water
systems with relatively clean intake water
• the number of water systems which would be
required to install a particular technology
Monitoring
• availability of analytical methods and reliability of
analytical results
Health Effects
• health effects are examined as a check on feasibility to
assure that MCLs are set at safe levels
Treatment Technology and Cost
EPA examines treatment technologies available for removal of
contaminants and evaluates them for a number of criteria. These
include:
• removal efficiency based on relatively clean intake
water
• degree of compatibility with other water treatment
processes
• service life
• ability to achieve compliance for all the water in a
public water system
In the final rule for control of volatile synthetic organic
chemicals (VOCs), EPA recommended the use of granular activated
carbon (GAC) and packed tower aeration (PTA) as the best
technology for removal of VOCs from drinking water. These
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technologies met the above criteria and had been demonstrated to be
effective in the field.
Costs are taken into consideration by analyzing the financial
burden of implementing a technology on large public water
suppliers. The legislative history of the SDWA indicates that EPA is
to consider whether a particular technology is "reasonably
affordable" to large metropolitan water systems.
In the VOC rule, it was concluded that GAC and PTA were in
fact affordable by public water systems. For VOC contaminants
which belonged to carcinogenicity groups C, D and E, MCLGs had been
set at the non-zero level. Because the treatment technologies
available were capable of removing contaminants below the MCLG,
the MCL was set at the same level as the MCLG.
For contaminants which had MCLGs set at the zero level
(groups A and B), EPA explored the feasibility of setting various
MCLs based on "nationwide costs" and concluded that the costs
associated with additional removals (in this case from .005 mg./liter
to .001 mg./liter) did not warrant setting the MCL at a lower level.
Monitoring
EPA considers the analytical methods available for the
measurement of contaminants and factors this analysis into the
process of setting MCLs. They use a method detection limit (MDL) to
determine the minimum concentration of a substance which can be
measured and reported at the 99% confidence level. The MDL for a
particular contaminant is determined by an evaluation of the
detection level achievable by a few of ihe most experienced
laboratories under research conditions.
MDLs are used by EPA to determine another analytical
benchmark known as the practical quantitation level (PQL). The PQL
was defined in the November 1985 proposal (previously cited) as the
"lowest level that can be reliably achieved within specified limits of
precision and accuracy during routine laboratory operating
conditions." The basis for EPA determination of a PQL includes the
following:
• quantitation
• precision and accuracy
• normal operations of a laboratory
• the fundamental need to have a sufficient number of
laboratories available to conduct analyses
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The rationale behind the use of a PQL is that it provides a
uniform measurement concentration which is laboratory
independent and can be used to set standards. EPA has typically
estimated the PQL at five to ten times the MDL. The range of five to
ten times the MDL has been confirmed from laboratory data to be
one in which attainment of reliable data can be achieved. The PQLs
are based on multi-laboratory data which are considered to be
representative of performance by the best laboratories.
The MDLs for eight of the VOCs fell within the range of .0002 to
.0005 mg./liter. Multiplying these values by five to ten results in a
range of .001 to .005 mg./liter. The PQL of .005 mg./liter for these
VOCs was based on a laboratory performance criterion of ± 20
percent or 40 percent, depending on the concentration of the
contaminant.
Health Effects
Health risks posed by a contaminant are examined at various
levels of that contaminant in drinking water. These include health
risks for cancer causing agents as well as non-carcinogens. EPA
establishes the upper limit unit risk estimate from a linearized
multistaged nonthreshold extrapolation model, using data obtained
from human and animal studies. The upper 95% target reference
risk range for carcinogens is from 10'4 to 10'6. This means that a
70 kg. adult consuming two liters of water per day era lifetime of
70 years would have not more than a 1 in 10,000 and 1 in 1,000,000
chance of getting cancer.
EPA concedes in the proposed VOC rule that risk assessment is
an imprecise science:
"...quantitative risk extrapolation procedures can provide
only a rough estimate of carcinogenic hazard because of the
many unknown factors which enter into these estimates.
Models using different assumptions may produce estimates
ranging over several orders of magnitude."
EPA considers the procedures used to assess health risks
conservative. They feel that the estimates produced err on the side
of overprotection rather than on the side of inadequate protection of
public health.
.-J!«?.
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20
Example: MCLG/MCL Determination for Para-dichlorobenzene (p-dcb)
On November 13, 1985, EPA promulgated an MCLG (then an
RMCL) for p-dcb as a Group D substance. This was based on chronic
toxicity data from studies available at the time. Following this
proposal, EPA received new information from a study on p-dcb
conducted by the National Toxicology Program (NTP). The study
reported tumors in rats and mice after long term exposure to p-dcb.
The results were statistically significant. On April 17, 1987, EPA
reproposed the MCLG for p-dcb. Their calculation of the MCLG and
MCL were as follows:
MCLG:
New information resulted in a reclassification of p-dcb as Group
B2, probable human carcinogen (Category I). MCLGs for Category I
contaminants are set at zero, thus the proposed MCLG for p-dcb was
established at zero:
MCLG = 0
MCL:
The proposed MCL for p-dcb was determined by the following
analysis:
Treatment Technology and Cost
• PTA and GAC adsorption met the engineering criteria
for BAT and were considered "best".
• GAC: Costs for up to 99% removal of p-dcb (from 0.5
mg./liter to 0.005 mg./liter) ranged from 7 cents to 15 cents per
1,000 gallons for large to medium systems and were approximately
58 cents per 1,000 gallons for small systems.
PTA: Removal costs were from 5 cents to 8 cents per
1,000 gallons for large to medium systems and 57 cents per 1,000
gallons for small systems.
These costs were considered reasonable by EPA.
Monitoring
• Based on analytical methods for detecting p-dcb, EPA
determined that the range for the method detection limit (MDL) was
0.0002 to 0.0005 mg./liter.
• A PQL of 0.005 mg./liter was determined, which
confirmed the general rule of a PQL being set at five to ten times the
MDL.
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21
• The PQL was established based on a precision of ± 20
percent by most laboratories.
Health Effects
• Tlte draft theoretical upperbound lifetime risk using
the conservative linear nonthreshold model (upper 95% confidence
level) was between 10'5 and 10-6 at an MCL of 0.005 mg./liter.
Based on the above analysis, EPA proposed the MCL at 0.005
mg./liter:
MCL = 0.005 mg./liter
Final MCLG and MCL for p-dcb
The proposed MCLG and MCL considered p-dcb as a Group B2
substance. EPA acknowledged that there was controversy
surrounding this classification based on the nature of the study by
NTP and the applicability of results to humans. They presented a
Group C classification as an alternative. Public comments were
solicited as to which classification was appropriate. EPA made a
judgement based on the weight of the evidence available and
concluded that p-dcb should be classified as Group C, possible human
carcinogen. Based on this new classification, the MCLG and MCL were
calculated as follows:
A reference dose was calculated by using available information
from laboratory studies on rats and mice. The RfD was based on a
subchronic gavage study.
MCLG:
RfD = NOAEL =_ (150 mg./kg./day) (51
(Uncertainty factor) (1000) (7)
= 0.107 mg./kg./day
::.': ^ ; • ittie (S). an^ r
administered for 5 days out of 7 days per week]
[the uncertainty factor of 1000 was used because data
. was .from a study, with less than chronic exposure..levels]
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22
DWEL = (RfD) (Body weight) (0.107 mg./kg./dav)(70 kg.)
(daily consumption of water) 2 liters/day
= 3.75 mg./liter
•/'
MCLG = (DWEL) (RSO = (3.75 mg./liter) (.2 f20%1)
(Additional Uncertainty factor) (10)
[due to Group C classification]
= 0.075 mg./liter
MCL:
The MCL was then established by setting it as close to the
MCLG as feasible. Because t!:e recommended treatment technologies
(GAC or PTA) were capable of removing contaminants to a level
below the MCLG, it was feasible to set the MCL equal to the MCLG.
MCL = 0.075 mg./liter
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23
GLOSSARY OF ACRONYMS
ADI--Acceptable Daily Intake
BAT--Best Available Technology
DWEL—Drinking Water Equivalent Level
EPA—Environmental Protection Agency
GAC--Granular Activated Carbon
LOAEL--Lowest-observed-adverse-ef feet-level
MCL—Maximum Contaminant Level
MCLG—Maximum Contaminant Level Goal
MDL-Method Detection Limit
NAS—National Academy of Sciences
NO AEL--No-observed-ad verse-effect-level
NTP—National Toxicology Program
ODW--Office of Drinking Water
PQL—Practical Quantitation Level
PTA—Packed Tower Aeration
RfD--Reference Dose
RMCL—Recommended Maximum Contaminant Level
RSC--Relative Source Contribution
SDWA-Safe Drinking Water Act
SOC~Synthetic Organic Chemical
VOC--Volatile Synthetic Organic Chemical
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REPORT ON THE RESEARCH ACTIVITIES
OF THE OCEAN SURVEY VESSEL ANDERSON
IN RHODE ISLAND SOUND
AUGUST 15-18, 1988
WATER POLICY OFFICE
OFFICE OF WATER
U.S. ENVIRONMENTAL PROTECTION AGENCY
Peyton Robertson
Summer Intern, 1988
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BACKGROUND
The Peter W. Anderson is an Ocean Survey Vessel (OSV) used by
the Environmental Protection Agency for research in marine and
estuarine waters of the United States. Originally a Navy patrol gunboat
(USS Antelope PG-86). the vessel was converted for a new mission of
environmental research and monitoring in 1979. The Anderson is
used primarily for EPA surveys in the offshore waters of the eastern
United States. This work includes study of existing and proposed
dredge spoil disposal sites as well as monitoring of the 106 mile
sewage sludge disposal site (106 miles offshore of the coast of New
York and New Jersey). Individual EPA Regional offices are allotted
time aboard the Anderson to conduct research pertaining to specific
topics in their region.
On December 23. 1986. EPA Headquarters delegated
responsibility to the Regional offices for the designation of ocean
dumping sites for dredged material. It was intended that this
delegation of authority would improve local coordination between EPA,
the Army Corps of Engineers, states and local governments. To
further expedite the designation of ocean disposal sites, EPA began
negotiating a national Memorandum of Understanding (MOU) with the
Corps of Engineers in 1986.
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RESEARCH CRUISE IN RHODE ISLAND SOUND
As part of the preliminary stage of designating a site for dredge
spoil disposal, EPA Region I in cooperation with the Army Corps of
Engineers and State of Rhode Island conducted research In the waters
of Rhode Island Sound between August 15 and August 18. 1988.. The
purpose of this work was to establish baseline information on the
status of sediments and marine resources in areas which could
potentially be designated for dredge disposal. The initial data will be
used to narrow the list of potential sites. Further research will be
conducted on this smaller list of sites to more comprehensively
evaluate their suitability for disposal.
Richard Pastore of the Water Quality Branch, EPA Region I
served as chief scientist for the cruise and directed sampling and data
collection while the Anderson was underway. The first day of
sampling was to be conducted on Monday, August 15, 1988. The
Anderson proceeded from a dock In Davisville, Rhode Island through
the West Passage of Narragansett Bay to the coastal waters of Rhode
Island Sound (see attached map). After two hours of transit time from
Davisville, the Anderson was on station for the first sediment sample.
Windblown waves from the southwest had created seas of ten to
twelve feet on Rhode Island Sound. The box corer for sediment
sampling on the Anderson is deployed over the stern of the ship
through a hydraulic A-frame. Because the gear is heavy, rough seas
created a potentially dangerous situation and the captain and chief
scientist decided to return to Davisville.
The second day. the Anderson returned to the survey area and
seas had abated substantially. The box corer was lowered over the
stern and sediment samples were taken. The ship continued
sampling along a transect In waters between 180 and 200 feet deep.
Each box core was dumped Into a sediment tray and sub-sampled for
three cores. These cores were taken by pushing 2 x 6 inch . .
polycarbonate tubes into the sediment, capping the tubes at both ends,
and refrigerating the samples for future analysis. The analysis will
involve grain size and sediment chemistry. . .
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7
The third and fourth day, the Anderson returned to the
previously sampled transects to pull otter trawl tows for groundflsh
and benthlc fauna. Tows were conducted for twenty minutes using a
twenty foot otter trawl net. Tows were brought onboard and separated
by species. Individual species were counted and weighed. Typical
animals included fluke, summer and winter flounder, hake, skate and
lobster. Species composition, size and distribution will be used to
assess impacts of dredge disposal on marine life in the area.
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OBSERVATIONS
The cruise provided a unique opportunity to gain an
understanding of a typical research mission aboard the OSV Anderson.
The Anderson Is equipped with state-of-the-art research equipment
and Is capable of detailed oceanographlc analysis. Such sophistication
enabled this observer the opportunity to comprehensively understand
the area of study. The captain and crew were competent and
courteous. The ship was well maintained and though minor difficulties
were experienced in deploying some of the gear, the crew responded
effectively and minimized delays.
It was interesting to see EPA, Army Corps and State personnel
working cooperatively. Collection of information with representative
staff from different offices seems to facilitate a better understanding of
the site designation process. I was Impressed by the knowledge of
those aboard and their willingness to assist in any facet of the
operation.
Site designation for dredge spoil involves a number of steps.
This research cruise was only the first of those steps and further
analysis will be necessary. Given the recent press attention to ocean
dumping, final designation for the sites in Rhode Island Sound seems
unlikely. The proximity to Block Island and Newport, with potential
impacts on tourism and commercial fishing, raise the political specter
of the issue. The lack of economic resources to dredge harbors is also
likely to lessen the immediate need for a new disposal area. These
factors lead one to conclude that any new dredge disposal site in the
waters of Rhode Island Sound will remain on the drawing board.
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SURVEY AREAS FOR POTENTIAL
DREDGE DISPOSAL SITES
IN RHCOE ISLAM) SOUND
. .
CAUTION
IMS OOCUMINT IS NOT fOt I
Reproductd from
avallablt copy
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OBIe««flliilD«tnd
»-—.»—««
Offlo* of Water
MARINE DEBRIS
Who* is Marine Debris? high tides and wind.
Marine debris describes a wide vari- Ships and boats of all types dump
ety of floating material which may eventu- garbage over the side. Large commercial
ally end up on shorelines and beaches, and military vessels can generate tons of
The list Includes plastic, glass, rubber, waste In a single day. In 1975, the
styrofoam. metal, paper, wood, and cloth. National Academy of Sciences estimated
The most familiar of these items are also that people aboard ships dispose of over
the most visible since they destroy the 6.4 billion pounds of garbage worldwide
beauty of our waterways and coastlines each year. Commercial fishermen dis-
and harm marine life. Beverage contain- card old nets while recreational boaters
ers, wood debris, packaging material, six- throw away monofllament line.
pack yokes, tampon applicators, con-
doms, discarded fishing gear, garbage What happens to Marine Debris?
bags and plastic dlshware represent fa- Marine debris Is transported by
miliar items found washed up on the currents and wind. The size and weight
beach. Not as noticeable are polyethylene of the material determines where It even-
pellets and polystyrene spherules which tually ends up. Lighter objects such as
are the broken down components of styro- plastic cups and floating aluminum cans
foam. These particles can remain floating are strongly affected by wind. Heavier
on the surface for long periods of time and debris such as driftwood Is Influenced by
pose unique threats to bird life and water- surface currents. Storms concentrate
fowl. these materials in lines of debris which
wash up on beaches and shorelines.
Where does Marine Debris come from? Organic material such as food
Marine debris comes from many waste and wood are broken down by
sources which are often difficult to Iden- natural processes. Discarded food items
tify. Solid waste (garbage) landfills adja- decay faster than wood and paper, but
cent to the shoreline can contribute these Items will eventually decompose.
household debris from high winds and Synthetic materials such as plastic re-
rainfall. Barges which move garbage from main In the environment essentially
one place to another may lose material unchanged for long periods of time. Plas-
overboard when they encounter rough tics are made up of long chains of mole-
weather at sea or transfer their loads to cules which are very difficult to break
land-based facilities. apart. After prolonged exposure to sun-
Driftwood comes from trees, old light, some plastics become brittle and
piers, Jetties and boats which continue to break Into smaller fragments.
lose pieces of material as their structures
decay. Heavy rains In older cities create What problems are caused by Marine
sewer overloads which bypass the sewage Debris?
treatment process and carry litter directly The most offensive problems
to the water. Trash left on the beach can caused by marine debris are the potential
be carried back to the ocean by extremely harm to marine life and shore birds and
DRAFT
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the ugliness created by littered beaches
and waterways. Trash and garbage de-
stroy the natural beauty of shorelines and
can create health hazards as well. The
loss of aesthetic value can translate Into
loss of economic value as fewer people are
attracted to coastal resorts.
Marine life and shoreblrds have
been Injured and killed by several forms of
marine debris. Fragments of synthetic
fishing net have entangled fish and sea
turtles. Lost crab and lobster pots con-
tinue to capture animals for long periods
of time (this Is called "ghost fishing").
Discarded fishing line and six pack rings
entangle birds and impair their ability to
feed. Sea turtles have been known to
mistake plastic garbage bags for Jellyfish
(a food source) and have suffocated after
ingesting them.
Commercial and recreational inter-
ests are also negatively impacted by
marine debris. Fisheries may be harmed
by abandoned nets. Plastic sheets can
clog the cooling water intakes of boats and
polypropylene line may become wrapped
around propeller shafts. Floating pilings
are especially hazardous to smaller rec-
reational boats which can be severely
damaged by collision with these objects.
What ts being done about Marine Debris?
The Environmental Protection
Agency (EPA) has been working with other
federal agencies, states, local govern-
ments and private groups in a variety of
ways to control floatable debris. Efforts
are being undertaken to rehabilitate ag-
ing sewer lines and reduce combined
sewer overflows. Landfill operations are
being inspected and monitored more
closely. In some cases, a floating boom Is
being used to contain refuse which falls
off of barges during transfer operations.
Use of barge covers Is also being explored.
EPA has recently Implemented
stricter conditions for vessels which col-
lect driftwood and bum It at sea. These
vessels must be equipped with stan-
chions to contain their load and be followed
by another boat to retrieve wood lost over-
board. Studies are being conducted to
identify sources of marine debris and ways
to control them. Research is focusing on
the Impact of marine debris on fish and
wildlife populations.
Use of degradable plastics is being
evaluated as an alternative to currently
used materials which break down ex-
tremely slowly. A new law will .take effect In
December of 1988 which prohibits com-
mercial and military ships from disposing
of plastics at sea. The U.S. Coast Guard will
be responsible for enforcement and public
vessels will have to abide by the same
restriction by 1993.
What can you do to reduce Marine Debris?
Several coastal communities have
organized cleanup activities for their shore-
lines and beaches. COASTWEEKS '88 is a
nationwide cleanup scheduled for Septem-
ber 17 - October 10,1988. Volunteers will
collect trash and tally items on a scorecard.
The data from all of the cleanups will be
compiled by the Center for Environmental
Education to establish a National Beach
Cleanup Data Base.
DRAFT
YOU CAN HELP REDUCE MARINE
DEBRIS BY:
• not Uttering
• minimizing the use of disposable
materials ;V ••••".' '••••. •" ••••
• requesting paper bags when grocery
.,- ^shopping. •*;'%•• v .-. ,^>x;v. :
• using paper bags instead of plastic
, : JFor garbage '%* : «f - ^ '-' ••-•/'• ?-- • ••••
• recycllrig aluminum cans and news-
papers
'•"•• encouraging neighbors to recycle
• organizing a beach cleanup In your
'
^
• encouraging local governments' to'
- institute recycling programs and
f repair aging sewer systems
'
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/
KACT SHEET
SECTION 301 (h)
OF THE CLEAN WATER ACT
OMEP
Office of Marine and
Eatuarine Protection
Office of Water
What is Section 301(h}?
Section 301(h) refers to a section In
Title III of the Clean Water Act. Specifically.
301 (h) is the section which allows for waiv-
ers of secondary treatment by publicly
owned treatment works (POTWs) which
discharge into marine/estuarine waters.
301(h) lists the criteria which must be met
to be eligible for a waiver and describes the
environmental setting where such permits
are allowed.
Background qf301(h):
Until the passage of the Clean Water
Act in 1972. there was little progress made
in cleaning up the nation's waters. The Act
allowed the Environmental Protection
Agency (EPA) to establish technology based
treatment requirements for sewage treat-
ment plants. EPA established "secondary"
treatment as the "best practicable control
technology" and set deadlines for coming
into compliance with the secondary treat-
ment requirement.
Several west coast municipalities
proposed the enactment of section 301 (h) in
1977. Their proposal was based on the
"assimilation capacity" of ocean waters.
Because oceans have much greater mixing
zone and circulation, it was argued that
they could assimilate wastes more "tfec-
tively than streams or rivers. Coastal
municipalities felt that discharging sewage
into marine waters should be regulated
differently for this reason.
The waiver of secondary treatment
was a return to a water quality based ap-
proach to water pollution control. In con-
sidering the mixing capacity of the ocean.
receiving water quality was a criterion
rather than the technology available for
treatment. A great deal of controversy
surrounded this approach.
What are the criteria for a 301(h) waiver?
Amendments to the Clean Water Act
in 1987 revised and added to the list of
criteria which must be met to obtain a
30 l(h) waiver. These statutory criteria are
summarized below:
1) There is an applicable water quality
standard specific to the pollutant for
which the waiver is sought.
2) The discharge will not interfere with
attainment of water quality that sup-
ports a balanced indigenous
population of shellfish, fish, and
wildlife, and allows recreational ac-
tivities.
3) Establishment of a system to monitor
the liupact on aquatic biota to the
extent practicable.
4) There will be no increased treatment
requirements on other point or non-
point sources as a result of the
waiver.
5) Applicable pretreatment require-
ments will be enforced.
6) For treatment works serving a popu-
lation of 50,000 or more, with respect
to any toxic pollutant introduced by
an industrial discharger for which
there is no pretreatment require-
ment, the treatment works must
remove the same amount of such pol-
lutant as if required to use secondary
treatment.
7) Establishment of a schedule of activi-
-------
ties to eliminate Introduction of tox-
ics from nonindustrial sources, to the
extent practicable.
8) There will be no new or substantially
increased discharge above the vol-
ume specified in the permit.
9) At the time the waiver becomes effec-
tive, the treatment works will be
performing at least primary treat
ment or the equivalent of primary
treatment.
How are decisions made about granting
301 (h) waivers?
Decisions are made by a consensus
building process through task force recom-
mendations. An approval process takes
place within EPA whereby interagency of-
fices review the programs. Once concur-
rence is achieved, the program is delegated
to the EPA regional office. Another concur-
rence process takes place at the regional
level involving the affected section, branch.
division, and regional administrator. The
final decision on whether or not to grant a
301(h) waiver Involves public review and
comment.
301(h) program status as of August, 1988:
• 249 applications have been received
for 301 (h) waivers.
• Final decisions have been made on
185 applications.
• A totaJ of 47 waivers have been
granted.
• EPA has Issued 15 guidance docu-
ments for implementation of the
program.
Future outlook for the 301(h) program:
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