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I UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
? WASHINGTON, D.C. 20460
OFFICE OF THE ADMINISTRATOR
SCIENCE ADVISORY BOARD
June 30, 2000
EPA-SAB-DWC-LTR-00-005
Honorable Carol M. Browner
Administrator
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Subject: Science Advisory Board Letter Report on EPA's Draft Proposal for the
Groundwater Rule
Dear Ms. Browner:
The Drinking Water Committee (DWC) of EPA's Science Advisory Board (SAB) met on
March 13-14, 2000 to review the Agency's draft proposal for its Ground Water Rule. This rule
addresses the use of disinfection in ground water and other components of ground water systems to
assure public health protection.
The Committee conducted this review in fulfillment of its responsibilities under Section 1412(e)
of the Safe Drinking Water Act (SDWA as amended in August 1996) which state:
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 and national primary drinking water
regulation. The Board shall respond, as it deems appropriate, within the time period
applicable for promulgation of the national primary drinking water standard concerned.
This subsection shall, under no circumstances, be used to delay final promulgation of any
national primary drinking water standard.
This review was conducted in a public meeting in Washington, DC. EPA's draft proposal was
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reviewed by the Committee while it was still under review by the Office of Management and Budget
(OMB) and prior to being released for publication in the Federal Register as a proposed rule. As such,
the DWC members recognized that specific elements were subject to change during the OMB review.
The Committee reached closure on its conclusions during the March meeting. It was the view
of the Committee that: 1) both bacterial and viral indicators should be employed in ground water source
monitoring plans; 2) either E. coli or enterococci will serve as the bacterial indicator and coliphage
should be used as the viral indicator; 3) to save on costs of monitoring, the Agency should develop and
validate the use of a common host to simultaneously detect both male-specific and somatic coliphage;
4) the Agency should depend upon monitoring and wellhead protection programs to insure ground
water sources are not subject to microbial contamination; and 5) source monitoring should include all
ground water systems and some less frequent repeat monitoring that goes beyond the intensive
monitoring proposed for the first year. These points are discussed in detail later in this letter.
A general issue raised by members during the discussion concerned the need for detailed
technical information on the science that supports the rules which EPA requests SAB comments upon
pursuant to SDWA 1412(e). Not having specific technical information available on the issues
discussed in the rule can impede the effective evaluation of important issues by the Board. In this
review, the Committee discussed the adequacy of a number of monitoring technologies that were
referred to in the proposed rule. However, the technical descriptions of the methods were not
provided to the Committee by EPA. In this case, several of the members were familiar with the
methods thus the Committee was able to carry its discussion through to completion. However, the
discussion would have been more efficient and effective if all members had been provided technical
information on the methods prior to the meeting. Committee members noted that for future reviews, it
will be important to identify, and obtain for all members, the relevant technical support documents that
underpin critical elements in the Agency's proposed drinking water rules.
1. BACKGROUND
1.1 Statutory Context
The Safe Drinking Water Act (SDWA, 1996a) requires that EPA "publish a maximum
contaminant level goal [MCLG] for contaminants: 1) that may have an adverse effect on the health of
persons; 2) that are known to occur or there is a substantial likelihood that will occur in public water
systems with a frequency and at levels of public health concern; and 3) for which a regulation presents a
meaningful opportunity for health risk reduction for persons served by public water systems." MCLGs
are to 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"(SDWA, 1996b). Further, EPA must also
publish a National Primary Drinking Water Regulation (NPDWR) that specifies a maximum
contaminant level (MCL) for such contaminants "which is as close to the [MCLG] as is feasible"
(SDWA, 1996c) or specify "the use of a treatment technique in lieu of establishing an [MCL]," if EPA
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finds "that it is not economically or technologically feasible to ascertain the level of the contaminant"
(SDWA, 1996d) in water. "The term 'feasible' means feasible with the use of the best technology,
treatment techniques, and other means [found by examination under] field conditions...are available
(taking cost into consideration)" (SDWA, 1996e)
In addition, SDWA requires that when EPA "proposes a [NPDWR]...the Administrator shall:
1) "publish a determination as to whether the benefits of the [MCL] justify, or do not justify, the costs
based on..." (SDWA, 1996f) a "Health Risk Reduction and Cost Analysis" [HRRCA]; 2) "use - i) the
best available, peer-reviewed science and supporting studies conducted in accordance with sound and
objective scientific practices; and ii) data collected by accepted methods or best available methods (if
the reliability of the method and the nature of the decision justifies use of the data)" (SDWA, 1996g);
and 3) "ensure that the presentation of information on public health effects is comprehensive,
informative, and understandable." This information is to be contained in a publicly available document
that specifies, "to the extent practicable - i) each population addressed by any estimate of public health
effects; ii) the expected risk or central estimate of risk for the specific populations; iii) each appropriate
upper-bound or lower-bound estimate of risk; iv) each significant uncertainty identified in the process of
the assessment of public health effects and studies that would assist in resolving the uncertainty; and v)
peer-reviewed studies known to the Administrator that support, are directly relevant to, or fail to
support any estimate of public health effects and the methodology used to reconcile inconsistencies in
the scientific data" (SDWA, 1996h).
SDWA requires EPA to develop regulations specifying the use of disinfectants for ground
water systems as necessary. Under the provision, EPA must develop a ground water rule which
specifies the appropriate use of disinfection, and, in addition, addresses other components of ground
water systems to assure public health protection (SDWA, 1996i). Other rules applying to ground
water systems include: the Total Coliform Rule (EPA, 1989a), the Surface Water Treatment Rule
(EPA, 1989b), Interim Enhanced Surface Water Treatment Rule (EPA, 1998a), the Information
Collection Rule (EPA, 1996), and the Stage 1 Disinfectants/Disinfection Byproducts Rule (EPA,
1998b). In addition programs for Underground Injection Control, Wellhead Protection, and the
Source Water Assessment and Protection are also intended to address issues that are protective of
ground water.
1.2 Provisions of the Proposal Reviewed by the Drinking Water Committee
The draft proposed rule requires states to conduct sanitary surveys on all ground water systems
and surface water systems adding ground water directly to the distribution system without treatment
(every 3 years for community systems and 5 years for non-community systems) (EPA, 2000a, EPA,
2000b). Significant deficiencies are to be identified. All ground water systems not achieving the
equivalent of a 4-log reduction in concentration of viruses found in source water (commonly referred to
as 4-log virus inactivation or removal, i.e., a 99.99% decrease in the viruses found in the source water)
must do a one-time hydrogeologic sensitivity assessment to determine if the system is in a sensitive
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aquifer (within 6 to 8 years of the final rule). Monthly source water monitoring will be required for
those systems determined to be hydrogeologically sensitive. Triggered (one-time) source water
sampling will be required if a positive total coliform positive sample is found in the distribution system.
Finally, if sampling shows significant deficiencies or positive microbial samples that indicate fecal
contamination, the problem must be corrected by the system. Finally, systems notified of "...significant
deficiencies by the state, or notified of a [positive] source water sample,...must... correct the
contamination problem (by eliminating the contamination source), correct the significant deficiencies,
provide an alternative source water or install a treatment process which reliably achieves 4-log removal
or inactivation of viruses" (EPA, 2000a)."
2. CHARGE
The Charge provided to the Drinking Water Committee by EPA requested that the Committee
evaluate the premise that "...more than one fecal indicator may increase the likelihood of detecting fecal
contamination than a single indicator" (EPA, 2000c) in two areas:
a) Given the available data upon incidence, fate, and transport of virus and bacteria
through the soil/aquifer matrix, is it appropriate to monitor for both bacterial and viral
indicators to determine the presence of fecal contamination?
b) Based upon the available data, can each of the four candidate indicators (E. coli,
enterococci, somatic coliphage, male-specific coliphage) be justified as a monitoring
tool for determining the presence of fecal contamination in ground water?
3. SPECIFIC COMMENTS
Key points raised by the Committee are summarized below, to indicate the nature of their
concerns. Section 3.1 responds to specific charge questions from the Agency. Sections 3.2 and 3.3
address issues which were raised as questions within the draft proposal reviewed by the Committee.
3.1 Fecal Indicators
3.1.1 Given the available data upon incidence, fate and transport of virus and
bacteria through the soil/aquifer matrix, is it appropriate to monitor for both
bacterial and viral indicators to determine the presence of fecal
contamination ?
The Committee recommends that the Agency propose monitoring for both bacterial and viral
indicators for both routine and triggered monitoring. Specifically, the Committee recommends that the
Agency propose the use of E. coli or enterococci and coliphages.
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The Committee noted that occurrence studies that measure groundwater quality using several
microbial indicator organisms show that no single indicator adequately reflects the presence of fecal
contamination under all conditions. The draft proposed rule presents data from 13 studies (EPA,
2000b, pages 61-80). Different results were obtained for various bacterial and viral indicators in a wide
variety of groundwater sources. It is difficult to compare these studies side-by-side because different
methods and sample volumes were used. However, it is evident that no single indicator organism was
consistently detected in all the contaminated groundwater sources that were examined. The use of both
bacteria and coliphage indicators will provide better ability to detect fecal contamination and protect
human health.
For water samples collected close to the source of contamination, it is more likely that several
microbial indicators will be detected. For water samples collected distant from the source of
contamination, it is critical to use indicators that model the transport and survival characteristics of viral
pathogens because viruses are known to have prolonged survival in the environment and can be
transported long distances. The scientific literature documents significant differences between
transport and survival characteristics of enteric bacteria and enteric viruses. Field studies that
have spiked septic tanks with known quantities of virus have shown that viruses and bacteria have
different survival and transport characteristics in soil (Curry, 1999, Cogger et al, 1988, Vaughn et al.,
1983, Yates et al., 1986). Tracer studies where primary sewage effluent was applied to a rapid
infiltration site indicated that enteric viruses penetrated deeper into the ground than bacteria (Keswick,
1984). Gerba and Bitton (1984) present a thorough review of the survival and transport of
microorganisms in groundwater.
There is considerable evidence in the literature to support the use of coliphage as
surrogates for enteric animal viruses. Havelaar et al. (1993) examined virus and coliphage survival
in a wide variety of fresh water environments and concluded that, overall, coliphage were better
indicators of culturable enteroviruses than were bacterial indicators. Field Studies and soil column
studies have shown that coliphage are good predictors of the movement of enteric viruses in soils
(Nasser et al., 1989; Sobsey et al., 1995, DeBorde et al., 1999). Several occurrence studies have
shown a strong correlation between coliphage detection and viral and/or fecal contamination of
groundwater (Lieberman et al., 1999). Phase n of the EPA/AWWA study conducted monthly testing
of seven wells known to have viral contamination. Somatic coliphages were detected more frequently
in these wells (71% of specimens were positive) compared to E. coll (50% of specimens were
positive) or enterococci (55% of specimens were positive) (Lieberman et al., 1999). Twenty of 21
transient non-community groundwater systems in migrant worker camps in Wisconsin were found to be
positive for male-specific coliphage over a six month period, but E. coli was never detected in any of
these wells EPA 1998c). A study of fecal contamination in groundwater wells 500 feet down gradient
of a water recharge infiltration basin in California detected coliphage in all 23 wells at least once and
repeatedly in 20 of the 23 wells. E. coli were not detected in any of the 23 wells (Yanko et al., 1999).
Preliminary results of another study in California also indicate that coliphage are detected more
frequently than fecal streptococci in groundwater with viral contamination (Yates, 1999). Taken
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together, the data in the body of literature strongly suggest that it is necessary to include coliphage as
indicators of viral contamination.
Data from waterborne disease outbreaks indicate that there is significant risk of illness
associated with groundwater - both "treated" and untreated groundwater systems. In the draft
proposed rule, the Agency cites CDC data that between 1971 and 1996 there were 371 outbreaks of
waterborne disease associated with groundwater sources. This represents 58% of all the reported
waterborne disease outbreaks during this period (EPA 2000b, page 55). It is likely that much more
epidemic and endemic waterborne disease is associated with groundwater sources. Because of the
many small groundwater systems, it is probable that the majority of waterborne disease outbreaks
associated with these small systems are never recognized and reported. Of the 371 outbreaks in
groundwater systems from 1971 - 1996, 34 (9%) of the outbreaks were attributed to viral pathogens.
For the majority of these waterborne disease outbreaks (63%) the etiology was never determined.
However, it is likely that most of these outbreaks were due to viral agents because of the characteristics
of the outbreaks (symptoms, incubation period, duration) and the fact that viral agents are less likely to
be detected in infected persons because of inadequate diagnostic techniques.
The major target of the Groundwater Rule is viral disease. The treatment recommendation is
expressed in terms of 4-logs of virus inactivation or removal. Therefore, it is logical that the target of
groundwater monitoring should be viral indicators such as coliphage. Further, the use of both a
bacterial indicator and coliphage was also recommended by a panel of experts at the February 1999
"Workshop on Fecal Indicators for Ground Water Sampling Under the Groundwater Rule" (IS SI,
1999).
3.1.2 Charge. Based upon the available data, can each of the four candidate
indicators (E. coli, enterococci, somatic coliphage, male-specific coliphage) be
justified as a monitoring tool for determining the presence of fecal
contamination in ground water?
The Committee noted that both E. coli and enterococci are effective bacterial indicators and
that the States or water systems could chose either indicator. E. coli methods may be more familiar to
many laboratories which may make this indicator a more likely choice and provide data which will be
comparable to already existing data. However, the enterococci may be somewhat hardier in terms of
environmental persistence. The media for enterococci is more selective and less subject to non-target
bacterial growth. Laboratories that are already testing for enterococci should not be required to change
to E. coli if they are comfortable with the enterococci methods. The Committee recommends that the
Agency define the term "enterococci" because different media and methods may detect different sets or
sub-sets of organisms, and there is some confusion about this term in the international scientific literature
(LeClerc et al., 1996).
It is difficult to chose between somatic and male-specific coliphage. Occurrence studies show
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that the somatic coliphage are more prevalent in septic tanks, but both somatic and male specific
coliphages are detected with similar frequency in wastewater. Male-specific coliphages occur in higher
densities so they may provide additional sensitivity. The Committee recommends that the Agency
propose the use of both somatic and male-specific coliphage because this will detect a larger population
of coliphage. For most monitoring purposes, it is not necessary to be able to distinguish between
somatic and male-specific phage. Laboratory methods are available to detect both at the same time,
using a single host such as E. coli C3000 (ATCC 15597), so that it would not be necessary to collect
additional sample volume. The Agency is encouraged to initially propose testing for somatic and male-
specific coliphage on separate hosts and conduct round-robin testing of coliphage detection using E.
coli C3000 as the single host. Because the laboratory methods are the same whether using one or
more bacterial host strains, the round-robin testing of coliphage detection on a single host should be
relatively straightforward.
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3.2. Hydrogeological Assessment
Hydrogeological assessment is being considered by the Agency as a basis for distinguishing
between groundwater sources that are more vulnerable from those that are less vulnerable to fecal
contamination. The Committee is concerned about the ability to accurately assess the sensitivity of
specific groundwater sources.
The Committee questions whether hydrogeological assessment can be adequately conducted
based solely on maps. The Committee recognizes that some aquifers are well characterized with an
abundance of good hydrogeological information and well logging data, but other aquifers may have very
little information and it may be more economical to monitor these aquifers than to conduct an extensive
hydrogeological assessment. Furthermore, the Committee cited an example of a 2000 foot deep
aquifer with a confining layer that would give the appearance of being a well-protected source, but in
reality this source was contaminated due to infiltration through corroded casing of an existing well. This
illustrates the necessity of source monitoring for all groundwater sources rather than relying on
hydrogeological information to determine whether a source is likely to be contaminated.
The Committee is concerned that aquifers in sandy soils are not included in the list of sensitive
sources (karst, fractured rock, gravel). Field studies of virus transport from septic tanks show that
viruses rapidly move into groundwater in sandy soils (Cogger et al., 1988, Vaughn et al, 1983).
The Committee recommends that all groundwater sources be required to monitor for bacterial
indicators and coliphage for at least one year - regardless of sensitivity determination.
3.3 Source Monitoring
The Committee is concerned about the possibility that many untreated groundwater systems will
not be monitored at the source. CDC data on waterborne disease outbreaks indicate that 86% of the
outbreaks in groundwater systems between 1971 and 1996 were due to contaminated source water
(EPA, 2000b, page 55). As currently proposed, only groundwater systems in sensitive soils (karst,
fractured rock or gravel) will be monitored monthly for 12 months. After this time, it is possible for the
states to require less frequent or no source monitoring if all the source samples in the 12-month period
are negative. The Committee is concerned that one year of monthly monitoring may not provide
representative data (e.g., may not capture periods of heavy rainfall) or that new sources of fecal
contamination (septic tanks, animal feeding operations) may occur after the monitoring period. The
results of the occurrence studies indicate that 4-31% of groundwater sources had some evidence of
viral contamination. This high prevalence of groundwater contamination makes it critical to promote
regular source monitoring for untreated systems. It is possible that information from a hydrogeological
assessment and a strong wellhead protection program could provide a legitimate basis for decisions on
the frequency of source monitoring. The Committee recommends that all groundwater sources should
be monitored for a year and that all untreated sources should continue to be monitored at some
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frequency that should be based on the size of the population served, hydrogeological assessment, well
logging information, and well head protection programs. Source sampling of at least once per year
should be required for all systems. Due to insufficient data and scientific knowledge of all factors that
may make a well susceptible to fecal contamination, the Committee recommends a conservative
approach of monitoring all wells at the source as part of the evaluation process.
If laboratory capacity for source monitoring is a concern, it would be possible for the
monitoring requirement to be staged over a period of several years. Untreated systems serving the
largest populations should be first priority for source monitoring because more people have the potential
of being affected.
The Drinking Water Committee was pleased to conduct this review of the proposed rule. The
Committee looks forward to the response from the Assistant Administrator for the Office of Water to
the advice in this letter.
Sincerely,
/signed/
Dr. Mort Lippmann,
Interim Chair
Science Advisory Board
/signed/
Dr. Richard J. Bull, Chair
Drinking Water Committee
Science Advisory Board
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ROSTER
U.S. Environmental Protection Agency
Science Advisory Board, Drinking Water Committee (DWC)
March 13-14, 2000 Meeting
CHAIR
DR. RICHARD BULL, Batelle Pacific Northwest Laboratories, Molecular Biosciences, Richland, WA
MEMBERS
Dr. DAVID B. BAKER, Heidelberg College, Water Quality Laboratory, Tiffin, OH
DR. MARY DAVIS, Department of Pharmacology & Toxicology, West Virginia University,
Morgantown, WV
DR. RICARDO DE LEON, Metropolitan Water District of Southern California, Water Quality
Laboratory, La Verne, CA
DR. YVONNE DRAGAN, Ohio State University, Columbus, OH
DR. JOHN EVANS, Program in Environmental Health and Public Policy, Harvard Center for Risk
Analysis, Boston, MA
DR. BARBARA L. HARPER, Yakama Indian Nation, Richland, WA
DR. CHRISTINE MOE, Department of Epidemiology. University of North Carolina, Chapel Hill, NC
DR. LEE D. (L.D.) MCMULLEN, Des Moines Water Works, Des Moines, IA
DR. CHARLES O'MELIA, Department of Geography and Environmental Engineering, The Johns
Hopkins University, Baltimore, MD
DR. GARY A. TORANZOS, Department of Biology, University of Puerto Rico, San Juan, PR
DR. RHODES TRUSSELL, Montgomery Watson, Pasadena, CA
SCIENCE ADVISORY BOARD STAFF
MR. TOM MILLER, Designated Federal Official, US EPA/Science Advisory Board, 1200
Pennsylvania Avenue, NW (1400A), Washington, DC
MS. DOROTHY M. CLARK, Management Assistant, US EPA/Science Advisory Board, 1200
Pennsylvania Avenue, NW (1400A), Washington, DC
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NOTICE
This report has been written as 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 is 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.
Distribution and Availability: This Science Advisory Board report is provided to the EPA
Administrator, senior Agency management, appropriate program staff, interested members of the
public, and is posted on the SAB website (www.epa.gov/sab). Information on its availability is also
provided in the SAB's monthly newsletter (Happenings at the Science Advisory Board). Additional
copies and further information are available from the SAB Staff.
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REFERENCES
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Curry, DS. (1999) Final Report for the Septic Siting Project. New York City Department of
Environmental Protection. December 31, 1999.
DeBorde, D.C, W. W. Woessner, Q. T. Kiley and P. Ball (1999) Rapid transport of viruses in a flood
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EPA (2000a) Ground Water Rule - Fact Sheet. Prepared by US EPA Office of Water for the SAB
Briefing. February 14, 2000.
EPA (2000b) Ground Water Rule. Draft Proposal prepared by US EPA Office of Water. December
21, 1999.
EPA (2000c) Charge to Science Advisory Board. Indicators of Fecal Contamination in Ground Water
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EPA(1998a) National Primary Drinking Water Regulations. Interim Enhanced Surface Water
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EPA (1998b) National Primary Drinking Water Regulations: Disinfectants and Disinfection
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EPA (1998c). Unpublished report. Study and results are described on pages 71-72 of the draft
proposed groundwater rule (cited herein as EPA, 2000b).
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IS SI, Inc. (1999) Workshop on Fecal Indicators for Ground Water Sampling Under the Groundwater
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Office of Water, Health and Ecological Criteria Division, Office of Science and Technology.
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Lieberman, RJ et al. (1999) Unpublished report. Study and results are described on pages 68, 78 and
174 of draft proposed rule.
Nasser, A.M., R.M. Hall, C. Dunham and M.D. Sobsey. (1989) Comparative reduction of hepatitis A
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(1996a): Section 1412(b)(l)(A) General Authority.
(1996b): Section 1412(b)(4)(A)MCLGs
(1996c): Section 1412(b)(4)(B)MCLs
(1996d): Section 1412(b)(7)(A) Treatment Technology
(1996e): Section 1412(b)(4)(D) Feasible
(1996f): Section 1412(b)(4)(C) B-C Justification
(1996g): Section 1412(b)(3)(A) Best Science
(1996h): Section 1412(b)(3)(B) Public Information
(1996i): Section 1412(b)(8) Disinfection
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Vaughn, JM, EF Landry and MZ Thomas. (1983) Entrainment of viruses from septic tank leach fields
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