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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
September 30, 1992
OFFICE OF THE ADMINISTRATOR
EPA^AB-RAC-LTR-92-018 «««««»«»
Honorable William K. Eeilly
Administrator
U.S. Environmental Protection Agency
401 M Street, S,W,
Washington, D, C. 20460
Re: Drinking Water Treatment Wastes Containing NOEM
Dear Mr, Reilly;
The Radiation Advisory Committee reviewed the Office of Drinking Water's
"Suggested Guidelines for the Disposal of Drinking Water Treatment Wastes
Containing Nata-ally-Occurring Radionuclides" dated July 1990, Staff from both
the Office of Drinking Water and the Office of Radiation Programs briefed the
Committee at its public meeting May 21-22, 1992; the American Water Works
Association provided public comment.
Guidelines for the disposal of drinking water treatment wastes containing
naturally occurring radiomielides are certainly needed because of the potential
radiation doses to treatment plant workers and to the public. In developing these
guidelines, the Office of Drinking Water has clearly recognized the potential
importance of this source of exposure. The Committee applauds this move.
However, the Guidelines document lacks information needed to fully assess the
magnitude of risk from exposure to radioactivity in drinking water treatment
wastes. (Such a risk assessment is also missing from the regulations proposed in
July 1991.) The need for such an assessment was cited by the SAB in its
Drinking Water Closure Commentary (EPA-SAB-EAC-COM-92-003). Another
important shortcoming is the failure to specify whether the radiation exposures to
drinking water treatment plant workers should be considered as occupational
exposures or be viewed against the dose limits for the general public. This
decision will have considerable bearing on any final guidelines. The Agency should
also reevaluate the numerical criteria for the disposal of wastes containing lead-
210.
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In the individual sections below, the Committee has spelled out its concerns
and provided recommendations in regard to each of these specific issues. Some
recommendations, which address policy, are based on the members* practical
experience in administration of control programs for radiation in the workplace
and in the environment. We would first like to emphasize two of our conclusions
and then present the responses to the charge,
The "Guidelines" are needed. The Committee commends the Office of
Drinking Water staff for recognizing that public water supply system operators
will need guidance both about the management and disposal of the drinking water
waste residues and about protecting treatment plant workers. Compliance with
the proposed drinking water regulations will result in concentration of naturally
occurring radionuclides in the waste that results from treatment to meet the
regulations. Few water supply personnel currently have expertise or experience
with ionizing radiation exposure, nor do they have much experience with the
disposal of low-level radioactive wastes. Thus unless the report is carefully written,
this inexperience may lead the states and water treatment system operators to
rigid compliance with the "Guidelines" suggestions in places where more
experienced persons could develop alternative acceptable options for handling and
disposal of radionuclide-contammated water treatment wastes,
Sometimes it is more important to ask the right questions than to get the
right answer on the first try. By July 1990, before the Science Advisory Board
released Reducing Risk (September 1990), before the Radiation Advisory
Committee commentaries on residual radioactivity and radionuclides in drinking
water (1992), and before prominent discussions of "risk-risk" analysis such as those
which took place at the July 1992 Executive Committee meeting, the Office of
Drinking Water staff had developed the "Suggested Guidelines for the Disposal of
Drinking Water Treatment Wastes Containing Naturally-Occurring Radionuclides",
It appears that the staff recognized a very important issue early, exercised
initiative in addressing it in the face of limited resources with which to do so, and
approached it in a procedurally appropriate way. That the Committee found
significant difficulties with the "Guidelines" document which render it inadequate
for the intended purpose is not surprising since it is a first effort on a complex
topic where a coherent federal regulatory structure does not exist.
The Committee is pleased that the ODW staff attempted to address this
problem. These recommendations essentially encourage the Agency to obtain
additional information, to explore the issues more fully, and to reach decisions on
certain key policy questions that will affect the strategies adopted by water supply
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operators. The Committee's critique of the document is intended to strengthen
the document, not to discourage others from attempting similar analyses.
The "Guidelines" Should Be Revised. The Committee recommends
that the Agency strengthen the "Guidelines" by obtaining additional data and by
clarifying both the scientific rationale and the policy decisions underlying many of
the recommendations. Improved "Guidelines" are very important because of
potential radiation doses to workers and the public and because of the costs that
states and water supply system operators will face dealing with these matters.
The 1990 "Guidelines" lack critical information about waste volumes and levels of
radioactivity which would allow informed decisions about water supply treatment
methods, worker protection, and waste disposal. As a result, the recommendations
presented in the "Guidelines" and the underlying rationales for them are not as
clear as they should be for a document of this importance,
*
Response to the Charge. The charge for this Committee-initiated review
was negotiated between the Committee and the Office of Drinking Water, The
Committee's response to the individual questions in the charge appear below,
1. In the Guidelines document, the ODW summarized well-
documented drinking water treatment technologies and disposal
practices, (The summary does not include a critical evaluation of
treatment technologies for Best Available Treatment (BAT)
identification and costing purposes which appears in a different
document.) Are the relevant available treatment technologies and
available disposal practices correctly characterized?
The 1990 "Guidelines" document includes all the relevant treatment
technologies but describes them only in general terms. Because the discussion of
both the treatment technologies and the waste disposal practices is highly
qualitative, the "Guidelines" document is not sufficient by itself for making
scientific, engineering or economic choices. (Such information may exist in the
separate evaluation of the treatment technologies for Best Available Treatment
(BAT) which the Committee did not review.) The Committee recommends that
such quantitative information be integrated into any final guidance package
assembled by the Agency to be provided to interested organizations and
individuals.
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Neither the "Guidelines11 document nor any document the Committee has
seen contains an analysis of the public and occupational aspects of this issue. The
revised document should examine the effect on radionuclide build-up at inlet
radionuclide concentrations typically encountered. Such information could define
the magnitude of the waste problem, allow estimates of personnel exposure, and
provide a better basis for assessing available treatment options.
2. The ODW compiled background and technical criteria from many
sources. Are the background materials and numerical criteria used in
creating the 1990 Guidelines document still scientifically supportable
and current, especially in terms of specific limits for solid waste
disposal?
Additional consideration is needed of the numerical criteria used in creating
the 1990 Guidelines document, especially with regard to the specific radioactivity
limit for solid waste disposal,
A discussion of the scope and magnitude of the worker exposure and waste
disposal problems would strengthen the revised "Guidelines". The discussion
should include an estimate of the number of locations that may be affected and
the number of workers and members of the public that may be exposed to various
radiation levels. Elevated concentrations of radiomielides in water are more apt to
be found in groundwater than in surface supplies and those concentrations depend
upon the local geology. Therefore, the Committee suspects that water supply
systems with elevated concentrations of radionuclides may be clustered and that
small systems may be disproportionally affected as they are more likely to rely on
wells.
The revised "Guidelines" should clarify the rationale for the specific
radionuclide limits for waste disposal. In particular, additional consideration and
discussion of the limits for lead-210 presented in the 1990 "Guidelines" document
are needed. Guidelines for lead-210 are important because they will be a major
factor in determining the feasibility of using granular activated carbon to remove
radon from drinking water. The "Guidelines" state that "suggested guidelines for
radium may also be applied to the radon progeny lead-210," which seems
inappropriate since the guidelines for radium rely primarily on risks associated
with radon gas with secondary consideration of direct external gamma exposure.
Lead-210 does not emit radon and the risk from direct external gamma exposure
per unit activity quoted in the "Guidelines" document is three orders of magnitude
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lower for Iead-210 than for radium-226- Although the lifetime ingestion risk
presented in the document for lead-210 in soil is higher than the ingestion risk
presented for radium-226, this ingestion risk for lead-210 is still 7 times lower
than the risk from external gamma exposure from radium presented in the
document. Thus, the basis for applying radium limits to lead-210 is not apparent.
The 1990 "Guidelines" document appears to assume that ingestion risks
result from an individuals^ total intake of vegetables, meat and milk coming from
land contaminated at the level specified for the disposal residue. This assumption
is conservative because it is unlikely that an individual's total food supply would
come from a single location and because radionuclides would have to leach from
the residues and migrate to the location of food production in order to expose
persons as assumed in the analysis. The revised "Guidelines" should present data
on the relationship between the radionuclide activity per gram of drinking water
treatment waste and the activity per gram in the soil that could result in exposure
to members of the public, either directly or through the food supply. The revised
document should: (1) analyze the desorption of lead-210 contained on granular
activated carbon used to remove radon from water, (2) address the migration of
lead-210 away from the waste disposal area, and (3) consider the radioactive decay
of lead-210 because lead-210 levels would decrease by a factor of approximately 30
over 100 years,
3. Are the rationale and guidance for selection of treatment
technologies and waste disposal practices clear?
The treatment technologies were discussed under the responses to questions
#1 and #2, The Committee found that the rationale and guidance for selection of
treatment technologies lacks critical information for assessing the available
treatment options.
The disposal of materials containing naturally-occuTrmg radionuclides is a
complex problem which has not been addressed in a systematic way by the federal
government. Although the 1990 "Guidelines" identifies and considers relevant
federal regulations, it is, understandably, somewhat unclear in its
recommendations. The "Guidelines" should be revised to make both the scientific
and policy rationales clear to the reader.
The 1990 "Guidelines" document describes liquid and solid waste streams
only in terms of their likely radionuclide contamination although it is clear that.
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in some cases, other hazardous contaminants as classified by RCEA may also be
present. When such contaminants are present in sufficient concentration, the
waste may be classified as a "mixed waste" and require special disposal. An
exhaustive review of non-radioactive co-contaminants is not warranted; however,
examples where this problem exists or might exist should be noted in order that
water supply system operators be alerted to the potential this has for limiting
available disposal options.
Some disposal options for liquid wastes are addressed under current
regulations, Discharge to storm sewers and surface waters requires an National
Pollutant Discharge Elimination System (NPDES) permit. Injection underground
may require a Underground Injection Control (UIC) permit, depending on the
radionuclide concentrations. The document's advice with respect to underground
injection of liquid wastes contaminated with radionuclides (but which are defined
as non-radioactive by the EPA's Underground Injection Control program) appears
reasonable, but it is not clear whether the 'extensive' permitting process currently
in place does indeed take the radionuclide contamination adequately into account.
In the case of discharge of liquid wastes to sanitary sewers, the "Guidelines"
document recommends adherence to existing Nuclear Regulatory Commission
(NEC) regulations which apply only to NRG licensees. (The NEC has revised
these regulations since the publication date of the "Guidelines".) The applicability
of these NEC recommendations to drinking water supply systems might be
different than their applicability to other facilities (such as nuclear power plants)
licensed by the NRC, Therefore, the Committee suggests that if the Agency
wishes to retain this recommendation on discharge to sanitary sewers, it should
provide a clear rationale for doing so.
Figure 1 in the "Guidelines" document, which summarizes the disposal
alternatives, could be improved by making a clear distinction between situations
where existing regulations apply and those situations where the "Guidelines"
propose to add new requirements.
Although the "Guidelines" note that provisions of Resource Conservation and
Recovery Act (ECEA) apply to solid wastes from water treatment, the document
describes disposal concerns, etc., as if the ECEA regulations do not apply, or do
not apply in all cases. Some clarification of this point should be made. Disposal
of solid wastes from water treatment must meet RCEA Subtitle D criteria for
sanitary landfills since they are solid wastes. Thus, even without the "Guidelines",
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these wastes will be disposed in facilities that control releases to the environment
for a significant period. Yet, the document lists a full range of concentration
levels for wastes which would already be addressed implicitly by RCRA Subtitle D
criteria. Identifying the radioactivity concentrations in treatment wastes above
which Subtitle D criteria are no longer sufficient would provide a simpler guide
and remove any conflict or redundancy with existing RCRA regulations.
The "Guidelines" also segregate the disposal procedures by activity
concentration for radium, uranium and lead-210; however, the document does not
discuss the sampling procedure^ or averaging periods used to determine these
quantities. The revised "Guidelines" should address the sampling procedures and
averaging periods because these are important for the implementation of the
guidance offered.
4, Is the recommended radiation exposure guidance for workers
complete, appropriate, and clear?
The basis for the guidance is not clear. No case is made whether the
radiation exposures to treatment plant workers should be considered occupational
exposures1 or whether the workers should be treated as members of the general
public. The basis for the eventual guide is largely determined by this distinction,
and the revised document should address this point. Subsequently, it is not clear
whether the suggested external gamma-radiation exposure guide is (1) based on a
policy of ALARA2 or whether it is (2) based oa an apportionment of the widely
accepted guidance of a maximal permissible dose of 100 mrem^r for the general
population,8
The "Guidelines" conclusion (p.33 paragraph 4) that an occupational
exposure level of 25 mrem/year for external and committed effective dose
equivalent is reasonably achievable at water treatment plants is unsupported; the
1 The "Radiation Protection Guidance to Federal Agential for Occupational Expoouin* limit* dose to worker* to an upper
bound of 5,000 mi«m par year an4 recommend* that down be a* low a* reasonably achievable (ALARA) Had that dow* not
approach the limit for rubetantial portion* of a working lifetime.
1 ALARA is defined by the International Commiasaon on Radiological Protection as meaning SB low m
reasonably achievable taking into account economic and soda! factors. The relevant economic ami social factors
are often considered to be those relating to health protection,
5 The "Guidelines" note that individual in the United State receive an average radiation dose of
approximately 360 mrems per year from all sources including radon. This provides context for the ICRP
recommendation that additional man-made exposure for members of the general public should be limited to 100
mrem per year, with no single source providing a large fraction of this limit.
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Agency has not shown that an occupational exposure level of 25 mrem/yr is
reasonably achievable at water treatment plants. Also, the phrase "external and
committed effective dose equivalent" indicates external plus internal exposure,
which is inconsistent with the separate treatment of radon in the "Guidelines"
document.
The "Guidelines" (page 34, paragraph 1) suggest that, "radiation
measurements be made within the plant and that areas which have external
radiation levels which could lead to worker exposures equal to or greater than the
limit of 25 mremVyr be identified and posted with signs reading, 'Caution
Radiation'," The Agency appears to believe that the radiation levels from
treatment systems would be elevated and readily measurable and that radiation
doses to workers would be the result of infrequent exposures. Thus, an
appropriate approach may be to recommend posting the hourly exposure rate and
to limit occupancy to stay within the exposure guideline, Thfl Agency should
evaluate the feasibility and practicality of measuring exposure rates that would
produce 25 millirems per year.
The "Guidelines" recommend that persons working in areas marked "Caution
Radiation" should have appropriate radiation protection training and their
radiation exposure should be monitored through area or personal monitoring, as
appropriate. Such a recommendation inevitably places a responsibility on water
treatment plant operators to conduct a radiation control program. The revised
"Guidelines" should address the feasibility of monitoring 25 mrem/yr above normal
background, and consider whether the benefits of such monitoring exceed the
costs.
The "Guidelines" recommend (page 36, paragraph "g") that "[rjadon levels in
air be monitored and action taken, where appropriate, to reduce radon levels in air
as much as possible." This guidance is inconsistent with the ICRP guidance to
keep doses as low as reasonably achievable. Keeping doses as low as reasonably
achievable can be accomplished by keeping radon levels in air sufficiently low or, if
that is not possible, by limiting occupancy times,
5. Are there other important issues that should be addressed in
the Guidelines document?
Since the individual States have the responsibility and authority for control
of naturally-occurring radioactive materials, it may be useful to suggest a process
8
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that would inform the appropriate State agencies so that they may provide
informed advice and supervision to the operators of those water supplies which
remove radionuclides. Such assistance with radiation matters would be
particularly valuable because few water treatment personnel are currently familiar
with ionizing radiation issues and protective practices.
While there are public and occupational radiation exposure issues associated
with water treatment plant operation and waste handling and disposal, the Agency
has not estimated the risks to either group nor compared them with the risk
reductions estimated to accrue from radionuclide removal from the water. The
Committee recognizes that this is not an entirely straightforward process and that
there are a number of possible scenarios regarding potential exposure levels;
nevertheless, an overall risk/benefit perspective would be useful, (This
recommendation also appears in the Committee's previous report EPA-SAB-KAC-
COM-S2-003, January 29, 1992.)
In summary, the Committee finds that the "Guidelines" document is very
important both for the task at hand (providing for the proper management and
disposal of drinking water treatment wastes containing naturally occurring
radionuclides) and because of the other science and policy issues inextricably
linked with it. The four most important recommendations of the Committee are:
1. The Agency should consider performing a risk assessment that
includes the occupational risks to reassure itself, and others, that the
risks of exposure to radionuclides in drinking water are indeed being
reduced and not just moved around as the result of their
concentration and disposal,
2. The Agency should consider collecting data on waste volumes, activity
levels, and costs which would allow more informed decisions
regarding treatment and disposal options by water suppliers.
3. In the interests of consistency and clarity, the Agency should select
and provide a rationale for an occupational protection approach from
among those available, that is whether treatment plant workers are
considered radiation workers or members of the public.
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4,
The Agency should reevaluate the numerical criteria for the disposal
of wastes containing lead-210 because of the apparent internal
inconsistencies and inaccuracies in the current analysis.
We appreciate the opportunity to review this document which demonstrates
highly commendable Agency initiative in a complex area and we look forward to a
response from the Agency on the revision of the Guidelines document which
considers the points raised. We stand ready to assist you if you have questions.
Sincerely,
/ju/mwi L £&&L'
/? ^
Dr. ^Raymond Grtioehr, Chair
Executive Committee
Science Advisory Board
Dr. Oddvar F Nygaard, Chair
Radiation Advisory Committee
Science Advisory Board
Enclosures: Committee Roster and Table I of the "Suggested Guidelines"
10
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U.S. ENVIRONMENTAL PROTECTION AGENCY
SCIENCE ADVISORY BOARD
RADIATION ADVISORY COMMITTEE
ROSTER
CHAIRMAN
Dr. Oddvar F. Nygaard, University Hospitals of Cleveland, Case Western
University, Cleveland, OH
MEMBERS
Dr. Stephen L. Brown, ENSR Consulting & Engineering,
Alameda, CA
Dr. Kelly H. Clifton, University of Wisconsin Clinical Cancer Center, Madison, WI
Dr. James E. Martin, University of Michigan, Ann Arbor, MI
Dr. Geuevieve M. MatanosM, The Johns Hopkins University,
Baltimore, MD
Dr. H. Robert Meyer, C.N.S.L, Harrisburg, PA
Dr. Richard G. Sextro, Lawrence Berkeley Laboratory, Berkeley, CA
Mr. Paul G. Voilleque, MJP Risk Assessment, Ine,, Idaho Palls, ID
Dr. James E. Watson, Jr., University of North Carolina at
Chapel Hill, NC
Science Advisory Board
Mrs. Kathleen W. Conway, Designated Federal Office, Science Advisory Board,
U.S. EPA, Washington, D.C.
Mrs. Dorothy M. Clark, Secretary, Science Advisory Board
U.S. EPA, Washington, D.C.
11
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TABLE 1 '
Summary of Treatment Technologies and Wastes Produced During
Removal of Naturally Occurring Radionuclides
Froa Drinking Water
TREATMENT
TECHNOLOGY
CONTAMINANT
REMOVED..
WASTE f 51 PRODUCED*
Cation
Exchange
Anion
Exchange
Lime
Softening
Coagulation/
Filtration
Reverse
Osmosis
Greensand
Filtration
Coprecipitation
with BaSQ4
Granular
Activated
Carbon
Selective
Sorbents
Aeration
Radium
Uranium
Radium
Uranium
Uranium
Rad ium
Uranium
Radium
Radium
Radon
Uranium
Radium
Radon
Rinse and backwash water,.
brine regenerant solution.
Rinse and backwash water,
brine regenerant solution.
Sludge from settling tanks,
filter backwash, supernatants.
Sludge from settling tanks,
filter backwash, supernatant
from settling or concentrating
sludge and filter backwash.
Reject water.
Solids and supernatant from
filter backwash.
Sludge from settling tanks,
filter backwash, supernatant
from settling or concentrating
sludge and filter backwash.
Granular activated carbon
media.
Selective sorbent media,
Radon released into air, or
radon decay products accumu-
lated on off-gas contactors
GAC1
_ _ 3^-*1 '••"• * \ It* T TII'
*NOTE: wastes containing radioactivity may also include filter
material, exchange resins, and other disposed materials.
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NOTICE
This report has been written as a part of the activities of the Science Advisory
Board, a public advisory group providing extramural scientific information and
advice to the Administrator and other officials of the Environmental Protection
Agency. The Board w structured to provide balanced, expert assessment of
scientific matters related to problems facing the Agency. This report has not been
reviewed for approval by the Agency and, hence, the contents of this report do not
necessarily represent the views and policies of the Environmental Protection
Agency, nor of other agencies in the Executive Branch of the Federal government,
nor does mention of trade names or commercial products, constitute a
recommendation for use.
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