GROUNDWATER DISINFECTION RULE
WORKSHOP ON PREDICTING
MICROBIAL CONTAMINATION
OF GROUNDWATER SYSTEMS
JULY 10-11,1996
PROCEEDINGS REPORT
September 1996
U.S. Environmental Protection Agency
Office of Groundwater and Drinking Water
401 M Street, SW
Washington, DC 20460
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TABLE OF CONTENTS
EXECUTIVE SUMMARY . • • ES-1
1. INTRODUCTION . . , • • • ...... 1-1
1.1 BACKGROUND . - 1-1
1.2 PURPOSE OF THE WORKSHOP -.-. 1-2
1.3 ORGANIZATION OF THIS PROCEEDINGS REPORT 1-5
2. NATURAL DISINFECTION TEAM . . . .-. .'•. 2-1
, 2.1 INTRODUCTION • • 2-1
2.2 METHODOLOGY/PROCESS . .. 2-2
2.3 NATURAL DISINFECTION TEAM PRODUCTS . 2-3
2.3.1 Conceptual Model . . 2-4
2.3.2 Decision Tree .. . . • • 2-4
2.3.3 Useability and Appropriateness of Mathematical Models ...... 2-10
2.3.4 Applicability of Wellhead Protection Programs 2-11
2.4 RECOMMENDATIONS AND RESEARCH NEEDS . . 2-12
2.4.1 Recommendations 2-12
2.4.2 Research Needs 2-13
3. SANITARY SURVEY TEAM . 3-1
3.1 INTRODUCTION . . .3-1
3.2 METHODOLOGY/PROCESS 3-4
3.3 SANITARY SURVEY TEAM PRODUCTS 3-6
3.3.1 Deficiencies Matrix 3-6
3.3.2 Decision Tree 3-9
3.3.3 Elements Necessary for Distribution System Protection 3-10
3.3.4 Construction Codes/Well Siting Requirements 3-10
3.4 RECOMMENDATIONS/ADDITIONAL RESEARCH 3-11
4. MICROBIAL MONITORING TEAM ., 4-1
4.1 INTRODUCTION .. ...I 4-1
4.2 METHODOLOGY/PROCESS .. . : ... 4-2
4.3 MICROBIAL MONITORING TEAM PRODUCTS 4-3
4.4 RECOMMENDATIONS/ADDITIONAL RESEARCH 4-8
4.4.1 Recommendations 4-8
4.4.2 Additional Research 4-9
Final
September 1996
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Table of Contents
TABLE OF CONTENTS (Continued)
5. SUMMARY/NEXT STEPS . . 5-1
5.1 SUMMARY 5-1
5.1.1 Natural Disinfection Team 5-1
5.1.2 Sanitary Survey Team 5-2
5.1.3 Microbial Monitoring Team 5-2
5.1.4 Overall • • • 5-2
5.2 NEXT STEPS . 5-4
LIST OF EXHIBITS
Exhibit 1-1. GWDR Workshop Schedule . . 1 1-3
Exhibit 2-1. Decision Tree 2-5
Exhibit 2-2. Characteristics of Adequate Well Construction 2-7
Exhibit 2-3. List of Contaminant Sources 2-7
Exhibit 2-4. Identification of Area of Contribution 2-8
Exhibit 2-5. Characteristics of Aquifers of Low Hydrogeologic Sensitivity 2-9
Exhibit 2-6. Characteristics of Aquifers of High Hydrogeologic Sensitivity .... 2-10
Exhibit 2-7. Characteristics of Confined and Deep Sedimentary Aquifers 2-10
Exhibit 2-8. Useability and Appropriateness of Mathematical Models 2-11
Exhibit 2-9. Applicability of Wellhead Protection and Source Control Programs 2-12
Exhibit 3-1. List of Deficiencies Identified in Sanitary Surveys of Groundwater
Systems 3-7
Exhibit 3-2. Draft Flow Chart/Decision Tree for Deciding Whether To Require
Disinfection 3-9
Exhibit 3-3. Ensure the Integrity of the Distribution System (Including Storage) in Lieu
of Requiring a Residual 3-10
Exhibit 3-4. Sanitary Survey Subcommittee Recommendations 3-11
Exhibit 4-1. Sensitivity and Specificity of Indicators 4-5
Exhibit 4-2. Parameters for Indicators , 4-9
Appendix A.
Appendix B.
LIST OF APPENDICES
EPA Workshop on Predicting Microbial Contamination of Groundwater
Systems—Attendees-List
EPA Workshop on Predicting Microbial Contamination of Groundwater
Systems—Briefing Packet
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LIST OF ACRONYMS
ASDWA Association of State Drinking Water Administrators
ASTM American Society for Testing and Materials
BMP best management practices
CFR Code of Federal Regulations
EPA U.S. Environmental Protection Agency
GWDR Ground Water Disinfection Rule
HFC Heterotrophic Plate Count
ml milliliter
MPA microscopic particulate analysis
MPN most probable number
PCR polymerase chain reaction
SAIC Science Applications International Corporation
SDWA Safe Drinking Water Act
SWTR Surface Water Treatment Rule
TCR Total Coliform Rule
USDA U.S. Department of Agriculture !
WHP wellhead protection
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EXECUTIVE SUMMARY
EPA is in the process of developing a National Primary Drinking Water
Regulation to protect the public from microbial pathogens in groundwater and prevent
waterborne disease. A "Workshop on Predicting Microbial Contamination of
Groundwater Systems" was held July 10-11,1996, at The National Academy of Sciences'
Beckman Center in Irvine, California. Experts and other interested participants discussed
and provided recommendations on three aspects, of the potential regulation:
(1) assessing vulnerability of groundwater to microbial contamination (Natural
Disinfection Team), (2) evaluating and ensuring water system integrity (Sanitary Survey
Team), and (3) monitoring for fecal contamination (Microbial Monitoring Team).
The goals of this workshop were to
Determine what groundwater protection and natural disinfection criteria are
feasible as protective regulatory elements
Develop a sanitary survey/defect correction regulatory element, and
Determine monitoring requirements.
The overall question for the workshop participants was
Can the GWDR be written to ensure public health protection from fecal
contamination of groundwater without requiring all systems to disinfect?
If so, how?
The Teams each had specific questions to address.
• Natural Disinfection Team—Predict source water microbial fate and transport
relating to source water protection and develop descriptions of criteria and
source water protection elements
• Sanitary Survey Team—Identify potential types of deficiencies generally found
during sanitary surveys that, if not corrected, could indicate the need for
disinfection
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Executive Summary
• Microbial Monitoring Team—Consider appropriate indicators of fecal
contamination as candidates for GWDR monitoring requirements.
The detailed products of the three teams are documented in this report. The teams
reached the following conclusions:
• Natural Disinfection Team—Natural disinfection processes can provide
adequate protection for some groundwater. spurces that are public water
supplies. A conceptual model, such as the decision tree developed by the
team, can be used to identify those groundwater sources potentially at risk of
fecal contamination.
The decision tree provides a series of assessment criteria at each decision point
to determine whether a particular well is at risk. The assessment criteria are
grouped into the following decision points:
- Examination of the adequacy of well construction
- Identification of the area of contribution
— Identification of potential sources of contamination
- Characterization of aquifers of relatively "low" and "high" hydrologic
susceptibility.
The decision tree will require refinements based on further research and on
integration with the results of the other two teams. The refinements of highest
priority include the following:
- Evaluation of whether the predictions of low aquifer vulnerability are
verified by microbial analysis of water supplies from those wells
- Integration of the decision tree with an approach to monitoring and with
the results of sanitary surveys
- Determination of the magnitude of microbial deactivation in transport
through the vadose zone.
• Sanitary Survey Team—The types of deficiencies in a groundwater public
water supply system that would trigger the need for a disinfection system can
be identified during a sanitary survey. Additionally, this team proposed the
use of a generalized decision tree to identify and correct deficiencies. To
ensure distribution system integrity and public heallh protection, a list of
elements was developed for integration into sanitary surveys. The list is
categorized into the following types of deficiencies and prioritized within each
type:
— Well/source
- Treatment
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Executive Summary
- Storage
- Distribution system
- Monitoring and reporting
—. Operations and maintenance.
Distribution system integrity assurance is recommended in lieu of a mandatory
requirement for a residual disinfectant within the distribution system. This
recommendation, however, is made with the caveat that State regulatory
agencies need to be provided with the authority to take enforcement actions
that will remediate the deficiencies identified in sanitary surveys.
• Microbial Monitoring Team—Based on sa\ evaluation of the risk of exposure
to pathogens from drinking contaminated groundwater, the Microbial
Monitoring Team recommended that four microbial analyses be used as routine
and nonroutine indicators of fecal contamination in groundwater. Microbial
indicator analyses were selected on the basis of high correlation between the
presence of the indicator and the incidence of disease, sensitivity of the test,
practicality and feasibility of the analytical method, and cost. The
recommended indicator microbial analytes include the following:
- E. coli
- Enterococti
- Clostridium perfringens
.- Coliphage (somatic and male-specific).
Initial and/or routine monitoring requirements using any. one of these cannot
be determined without further literature and field research.
The concepts, criteria, arid methodologies developed by each of the teams will be
refined and integrated into a multiple barrier approach for the GWDR. This approach
will consist of a series of protection criteria for the groundwater sources of public
drinking water that will assure protection from fecal contamination. The multiple
barriers probably will include source protection criteria, filtration, disinfection,
distribution system protection, and monitoring.
Final
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September 1996
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1. INTRODUCTION
• &
This workshop proceedings report was prepared by Science Applications
International Corporation (SAIC) for the U.S. Environmental Protection Agency (EPA)
Office of Ground Water and Drinking Water under contract No. C3-68-0365. The
workshop, entitled "Workshop on Predicting Microbial Contamination of Groundwater
Systems," was conducted in Irvine, California, on July 10 and 11, 1996, in support of
development of the Ground Water Disinfection Rule (GWDR) as required under the Safe.
Drinking Water Act (SDWA).
1.1 BACKGROUND
As mandated by the SDWA, EPA is required to promulgate disinfection
requirements for all public water supply systems. In June 1989, EPA promulgated
disinfection requirements for surface water supplies and for groundwater systems under
the direct influence of surface water (i.e., the Surface Water Treatment Rule [SWTR]).
The equivalent regulations for groundwater, the GWDR, is now in development. The
purpose of the GWDR is to protect the health of persons served by groundwater systems
from exposure to microbial (e.g., fecal) contamination in drinking water.
From January 1995 to date, the EPA GWDR Regulation Manager has been
conducting conference call working sessions to solicit technical assistance in developing
the proposed GWDR. The regulation development working sessions have been open to
all interested parties.
Among many issues discussed during these sessions is the following:
Can the GWDR be written to ensure public health protection front fecal
contamination of groundwater without requiring all systems to disinfect?
The GWDR Regulation Manager actively promoted the participation of State
regulators in the working sessions because many States have existing requirements and
guidance that adequately ensure protection of groundwater systems without the use of
disinfection. State groundwater protection programs include source water protection
components (e.g., hydrogeological evaluations, land use restrictions, wellhead protection
programs, well siting criteria) and sanitary survey components (e.g., well construction
and maintenance, distribution system maintenance, and monitoring).
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Introduction
The intention is to develop a rule that draws from State experience with existing
groundwater protection programs. Therefore, using information provided by
participants in source water protection programs and by those who conduct sanitary
surveys, the workgroup developed preliminary topic areas from which "criteria for
determining GWDR treatment requirements" could be developed in subsequent working
sessions. The purpose of these criteria is to assist States in determining whether a
groundwater system should be required to treat or disinfect its water supply under the
GWDR. These criteria could be applied to assess whether a system is vulnerable to or
protected from microbial contamination at the source or within the system. Source water
protection evaluation criteria are used to assess the adequacy of the control of
contaminant sources and to predict "natural disinfection" from source to well. Sanitary
survey evaluation criteria are used to assess the integrity of the water systems
themselves.
The criteria for determining system vulnerability to contamination and the need
for disinfection are quite complex. For example, very little is known about how some
microbial contaminants are transported in soils, what their attenuation rates are, and
how long they take to reach a groundwater source. Therefore, it was decided that a
workshop of experts should be held to discuss these types of issues in detail and to
expand and qualify the list of criteria that the workgroup feels may indicate that a
groundwater system is protected adequately and is safe without disinfection.
1.2 PURPOSE OF THE WORKSHOP
EPA sponsored the "Workshop on Predicting Microbial Contamination of
Groundwater Systems," held in Irvine, California, on July 10 and 11,1996. Invitees were
experts in the field of microbial contamination of groundwater systems; they included
hydrogeologists, microbiologists, environmental engineers, and environmental scientists.
A workshop schedule is provided in Exhibit 1-1, and an attendees list is provided in
Appendix A of this report. The GWDR Regulation Development Manager discussed the
current status of the GWDR and instructed the attendees on whait the workshop should
accomplish. His briefing packet is presented in Appendix B.
Several experts were invited to,make background presentations on such relevant
topics as public health concerns from microbial contamination of groundwater, the
occurrence of fecal contamination in groundwater, microbial fate and transport in
saturated and unsaturated media, vulnerability and sensitivity of groundwater based on
hydrogeology and water quality factors, source water protection concepts, groundwater
and wellhead protection programs, sanitary surveys, and microbial monitoring.
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Introduction
Exhibit 1-1. GWDR Workshop Schedule
July 10th
7:30 Workshop check-in and breakfast, Beckman Center
8:30 Welcome, introductions, logistics
GWDR regulatory status and needs
Goals for the workshop, approach, and agenda
Bruce Macler, GWDR Manager
9:15 Background presentations: -
Public health concerns from microbial contamination of groundwater, acceptable risk levels
Charles Gerba, University of Arizona
Occurrence of fecal contamination in groundwater
Morteza Abbaszadegan, AWWSC
Microbial fate and transport in saturated and unsaturated media
Marylynn Yates, University of California at Riverside
Hydrogeology and water quality factors; vulnerability and sensitivity
Mike Wireman, EPA
10:15 Break
10:30 More background presentations:
Source water protection concepts •
Henk Haitjema, University of Indiana
Groundwater and wellhead protection programs
. Chuck Job, EPA
Sanitary surveys
Dennis Nelson, Oregon DOH
Microbial. monitoring
Paul Berger, EPA .
Morteza Abbaszadegan, AWWSC
11:30 Questions and charges for the breakout groups
12:00 Lunch, Beckman Center
1:00 Facilitated breakout sessions
1) "Natural disinfection"
2) Sanitary surveys and defect correction
3) Microbial monitoring
3:00 Break . •
3:15 More discussion
4:00 Preparation of provisional reports
5:00 End first day
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Introduction
Exhibit 1-1. GWDR Workshop Schedule (Continued)
July llth
7:30 Breakfast, Beckman Center
8:30 Breakout session reports to entire group, answers to questions
9:30 Facilitated group discussion on major question—Can microbial protection of groundwater
be ensured without treatment? Development of new breakout session questions
1050 Break
10:45 Breakout sessions
12KX) Lunch, Beckman Center
1:00 Breakout sessions
Discussion on new questions
Recommendations
Research Jieeds and approaches
Ideas for future activities
Report preparation
2:45 Break
3:00 Breakout session reports to entire group
Discussion
4:30 Summary and closure
The primary purpose of this workshop was to expand on the conference call
working sessions about the concept that proper source protection and maintenance of
system integrity can be adequate for ensuring safe drinking water. In. this workshop,
attendees were asked to take the fundamental question
Can the GWDR be written to ensure public health protection front fecal
contamination of groundwater without requiring all systems to disinfect?
a bit further and develop products that more specifically answer
If so, HOW?
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Introduction
With this general issue as a backdrop, the group was divided into the following
three teams, each with an assigned mission:
• Natural Disinfection Team—Predict source water microbial fate and transport
issues relating to source water protection and .develop descriptions of criteria
and source water protection elements
• Sanitary Survey Team—Identify potential types of deficiencies generally found
during sanitary surveys that could indicate the need for disinfection if not
corrected
• Microbial Monitoring Team—Consider appropriate indicators of fecal
contamination as candidates for GWDR monitoring requirements.
1.3 ORGANIZATION OF THIS PROCEEDINGS REPORT
The detailed assignments, outcomes, recommendations, and additional research
outlined by each of the teams are presented in the following sections:
• Section 2—Natural Disinfection Team
• Section 3—Sanitary Survey Team
• Section 4—Microbial Monitoring Team ' ;
• Section 5—Recommended next steps and an overall summary of the workshop
proceedings. .
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2. NATURAL DISINFECTION TEAM
This section presents the activities and products of the breakout session on natural
disinfection processes, lists the assignments given to the Natural Disinfection Team,
describes the process used to develop the team's products, and gives recommendations
for future research.
2.1 INTRODUCTION
EPA assembled a team of national experts to integrate the best flunking about the
ability of natural hydrogeologic and biological processes to provide adequate disinfection
and protection of public health. The Natural Disinfection Team, composed of
approximately 40 hydrogeologic and microbial experts from State and Federal agencies,
universities, and research centers, was assigned to develop a set of hydrogeologic and
microbial criteria that could be applied to determine whether a groundwater system
would be required to provide disinfection. Criteria would need to be conservative to
provide adequate certainty that a source water would be adequately protected from fecal
contamination. To achieve this end, the team was requested specifically to address the
following three questions:
Can we now make meaningful predictions of fecal contamination or
protection based on hydrogeological and microbial fate and transport data?
Are there rigorous and feasible criteria that can be used to make decisions
some of the time, if not all the time?
Are wellhead and source water protection programs adequate to ensure
protection and accommodate regulatory verification?
In addition to providing answers to these questions, the team was tasked with providing
descriptions of criteria, protection elements, and research needed to determine the
certainty of the natural disinfection criteria developed.;
The premise of this assignment is that natural disinfection processes may provide
a mechanism to ensure adequate protection of the groundwater source. Implementation
of a decision-making tool that evaluates the source water may assist regulators in
determining the need for disinfection. This premise has a caveat-—protection of the
source water does not, in itself, preclude the need for disinfection. The requirement for
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Natural Disinfection Team
disinfection would necessitate an analysis not only of the source water but also of the
conditions at the surface as indicated by a sanitary survey.
Additional instruction provided to the team included direction to do the
following:
• Focus on developing criteria that would predict the effectiveness of natural
disinfection of the source water
• Disregard potential disinfection requirements imposed based on distribution
system or other conditions that may be developed by a sanitary survey
• Avoid focusing on monitoring requirements (although these requirements may
be integrally related to the criteria developed).
The GWDR Regulation Manager and members of the workgroup will integrate
the results of the Sanitary Survey, Microbial Monitoring, and Natural Disinfection Teams
following the workshop.
2.2 METHODOLOGY/PROCESS
The facilitator of the Natural Disinfection Team began the session by reviewing
the assigned questions and products. Initial team discussions provided a forum for
ideas but did not focus on the questions or products. After the initial discussion period,
a preliminary decision tree (flowchart) was presented showing a process for determining
water sources at. relatively low risk. The consensus of the team was that the decision
tree provided a focal point to begin discussion.
To optimize productivity, the team was divided into three smaller workgroups.
Each workgroup was tasked with developing criteria for one of the following portions
of the decision tree:
• Identification of contaminant sources in the area of contribution
• Definition of the area of contribution
• Identification of aquifers at lower risk of microbial contamination.
When the workgroups reconvened, their results were presented to the entire team for
discussion and consensus development.
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Natural Disinfection Team
The technique of working in smaller, focused workgroups was used to develop
various elements for team discussion and consensus. Workgroups addressed the
following topic areas:
• Adequate well construction criteria
• Additional criteria to define settings of low susceptibility
• Criteria that define protective time of travel
• Usefulness and appropriateness of mathematical models as predictive tools
• Incorporation of wellhead protection program elements or concepts into
programs to protect groundwater from microbial contamination
• Research needs related to natural disinfection processes.
Based on the concepts developed within each of these workgroups, the team
refined the decision tree, which provides initial criteria for use in determining whether
a groundwater source of drinking water has a low risk of fecal contamination. The
decision tree provides decisionmakers with a conceptual framework for assessing the
susceptibility and vulnerability of groundwater. Susceptibility, as used in this
discussion, is the relative risk or sensitivity of an aquifer to contamination based on its
hydrogeologic characteristics, such as the depth to the groundwater, the permeability of
the vadose zone, and the extent (if any) of a confining layer (susceptibility was also
referred to as sensitivity in many of the discussions).
Groundwater vulnerability is an integrated attribute that includes the presence of
sources of contamination superimposed on the susceptibility. Thus, if a source is highly
susceptible but has no sources of contamination, the aquifer would be considered to
have low vulnerability. On the other hand, if an aquifer is moderately susceptible and
has numerous potential sources of contamination,, the aquifer would be considered
vulnerable.
2.3 NATURAL DISINFECTION TEAM PRODUCTS
The following subsections present an integration and distillation of the discussions
and presentations of the Natural Disinfection Tesim. This presentation attempts to
capture and synthesize more than 8 hours of work by the team. The team discussions
resulted in the evolution and refinement of the decision tree. The results are presented
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Natural Disinfection Team
in an integrated fashion, rather than in the chronological order in which they were
developed.
.
2.3.1 Conceptual Model
A conceptual model that predicts the potential for contamination has multiple
components, each of which must provide a measure of predictability. These components
include the following:
• Well characteristics that provide protection to the groundwater source
• Sources of fecal contamination
• Identification of the area of contribution
• Vadose zone including the soil component
• Saturated zone.
i
Each of these components contributes either contamination or a quantifiable
measure of natural disinfection or protection of the source groundwater. Every
component must be addressed to provide a prediction of the potential for contamination
of a specific system. Within the timeframe of the workshop, the team was able to
synthesize a decision tree from a conceptual model that evaluated all of these
components except the vadose zone. The conceptual model embodied in the decision
tree identifies which aquifers are likely to be contaminated based on conservative
hydrogeologic and microbial assessments.
2.3.2 Decision Tree
The decision tree (Exhibit 2-1) is an assessment tool that, evaluates risk
characteristics and that must be viewed as a whole. The decision tree is limited by the
following assumptions and caveats:
• The underlying premise of the decision tree is the assumption that monitoring
results have provided no indication of fecal contamination.
• The decision tree represents a conservative format for decisionmakers to ensure
an adequate margin of safety. If a system cannot provide sufficient data to
demonstrate an affirmative (yes) response at a decision point, the answer is
assumed to be a negative (no) response until additional information can be
provided.
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Natural Disinfection Team
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Natural Disinfection Team
• The decision tree, as presented, does not provide a final determination of the
need for disinfection. Endpoints represent a conservative evaluation of the
condition of the source water only.
• The decision tree does not stand alone; its results are integrated with system
information gathered from monitoring or from a sanitary survey. Endpoints
that indicate that the source water is at a higher risk of contamination may
require integration of a mechanism for ensuring protection without
disinfection. For example, a source that has a moderate risk of contamination
but no indications of fecal contamination may be subject to more frequent
monitoring to preclude the need for disinfection.
• Several of the decision boxes may require multiple or iterative evaluations
based on the answers to other decision boxes.
The first decision tree question requires an assessment of the adequacy of the well
construction (Exhibit 2-2). Although this assessment could be performed as part of the
sanitary survey,- the team considered well construction critical to the protection of the
groundwater source; therefore, the group elected to address this issue separately. In
addition to a visual inspection, the well construction assessment should include a review
of the well log for the well under consideration and additional hydrogeologic data
available, in part, from well logs of adjacent wells. Exhibit 2-2 presents criteria that
States should address in developing well construction regulations or guidelines. The
well construction criteria should consider special hydrogeologic conditions of the site;
for example, an acceptable age of seal may depend, in part, on the type of aquifer
formation in which the well is completed. Construction, repair, and maintenance criteria
need to be enforceable by the State. Criteria for determining the adequacy of
construction of dug and driven wells remains to be developed. If a public water supply
system does not have a well log that provides construction information, the flowchart
assumes the answer to this question is "no."
The next question in the decision tree is whether there are contaminant sources
in the area of contribution. This assessment is two-fold: determination of the presence
or absence of potential contaminant sources, as depicted in Exhibit 2-3, and
determination of the size of the area of contribution. One participant indicated that
sources of fecal contamination are everywhere, and the list of potential contaminant
sources could be extensive; a list of the more significant human and animal sources is
presented in Exhibit 2-3. Although the initial ranking of sources, was not performed by
group consensus, it is provided here as a point of departure for future discussions.
Guidance developed to accompany the rule should provide a list of typical contaminant
sources and a discussion of whether and how sources can be managed to reduce the risk
of fecal contamination to the source waiter.
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Natural Disinfection Team
Exhibit 2-2. Characteristics of Adequate Well Construction
• Surface seal is absent of defects and drains away from the well
• Casing seal
- Emplacement to take advantage of natural protection
- Demonstrated lateral persistence
- Emplacement under positive pressure
- Cement use preferred over bentonite
- Age of the seal
• Criteria needed for other types of wells:
- Driven
- Gravel-pack
Well construction enforcement guidelines need to be developed.
Exhibit 2-3. List of Contaminant Sources
(Assumption: Well has been properly cased and sealed)
Sources of fecal contamination—ranked in order of severity
•. Priority 1: Sewage disposal systems, both subsurface (e.g., septic systems and drainfields, privies,
direct subsurface injection of sewage) and surface (e.g., unlined lagoons, infiltration
basins, land application of sludge or wastewater)
• Priority 2: Leaking sewer lines or leaking collection or conveyance lines •
• Priority 3: Animal confinement facilities (feed lots, dairies, zoos, dog kennels)
• All other sources:
- Reclaimed wastewater applied to the land surface
- Sanitary landfills
- Municipal solid waste transfer stations
- Animal waste or sludge composting facilities
- Land application sites for sewage sludge
- Storm water runoff
- Cemeteries
- Underground injection wells and storm water recharge projects
- Runoff from wetlands - .
- Improperly abandoned wells.
The team selected criteria to be met in determining the area of contribution of a
single well in unconfined conditions. The criteria included protection of a minimum
time of groundwater travel of 2 years; the calculated time of travel should be based on
the aquifer thickness and the pumping rate. Use of the screened interval as a
conservative estimate of the aquifer thickness was discussed; but resolution of this issue
was not achieved for all aquifer and screened conditions. A ratio of the screened
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Natural Disinfection Team
interval to aquifer thickness may provide a departure point for future consensus
building.
The 2-year time of travel provides for 107 (i.ev seven orders of magnitude) of
microbial deactivation. This conservative value is based on time of travel in the
saturated zone only. Discussion of microbial deactivation during travel through the
vadose zone was delayed until a future refinement of the decision tree.
Exhibit 2-4 suggests that small systems, with fewer technical and fiscal resources,
could estimate the time of travel based on a calculated fixed-radius model (similar to
models used in wellhead protection programs with some cautions). The calculated
fixed-radius model should not be used for aquifers with high ambient flow. The area
of contribution under high ambient flow conditions may extend a long distance,
approximating a pencil shape, and would not be protected by a circular radius. The
microbiologists suggested that a 100-foot radius or a 2-year time of travel (whichever is
more stringent) should be applied for systems of very low ambient flow. For large
public water supply systems, standard capture zone delineation models were
recommended to provide a more accurate assessment of the area of contribution.
Exhibit 2-4. Identification of Area of Contribution
(Uncorifined systems)
Assumption: No contamination—entire area of contribution for the well
• 52 years calculated time of travel (applies to saturated zone only, ignores filtration of unsaturated
zone)
• For SMALL SYSTEMS: Use calculated fixed-radius delineation or 100 feet, whichever is greater
(allow States flexibility to decide radius)
• Calculated fixed radius requires two pieces of information in addition to the location of the well:
aquifer thickness and pumping rate
- Use screened interval for aquifer thickness (as default value for aquifer thickness, or assume
another default for unscreened wells) based on State discretion. Well screen is more
conservative than aquifer thickness; therefore, may not want to apply screen interval universally;
may consider the ratio of screened interval to aquifer thickness
- Develop a table of ranges for aquifer thickness and pumping rates and effective porosity that
provides the calculated fixed radius.
- Calculated fixed radius is unsafe in some cases:
— Thick saturated zone and low pumping rates (predict too small radius)
— High ambient flow with no or low radial flow (have pencil shape capture zone, extending
in one direction)
• For LARGE SYSTEMS: Standard Capture Zone Delineation using models.
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The third decision point represents an assessment of the susceptibility or
sensitivity of the aquifer. Exhibit 2-5 provides five hydrogeologic settings that represent
potential categories of low risk aquifer types. These include:
• Confined aquifers
• Deep sedimentary aquifers
• Aquifers with "old" water as assessed by water quality parameters
• . Vadose conditions that prevent contamination from entering the saturated zone
• Combinations of conditions that ensure low susceptibility.
Exhibit 2-5. Characteristics of Aquifers of Low Hydrogeologic Sensitivity
NOTE: These five settings represent potential categories of low risk hydrogeological settings or
aquifer types
• Demonstrated adequate confining unit/aquitard—minimum criteria:
- Pressure heads
- Aquifer tests
- Geologic information—do not use only a single well log
• Depth of intake for some settings:
- Deep Sedimentary Basins (e.g., 1,500 to 2,000 feet)
- Deep Coastal Plain Sediments (e.g., 5,000 feet)
• Water quality: ;
- Age of water (difficult to measure, need to assess age, use of average vs. 99.99%, "old")
- Other (NO3, SOV Cl, others)
• Vadose zone characteristics:
- Thickness (distance between source and saturated zone) :
- Lithology (adequate sorptive capacity and minimum flow through micro-fractures)
• Low sensitivity (combination of low factors)
- Portions of aquifers that have low susceptibility
- Some States have these areas mapped.
Exhibit 2-6 lists characteristics of aquifers that have greater susceptibility than
those in Exhibit 2-5 and that provide a moderate or high risk of fecal contamination.
Although these source waters are "more" susceptible hydrogeologically, public water
supplies that have these as source waters should NOT, a priori, be required to provide
for disinfection. Further evaluation should be given to other protective mechanisms such
as higher frequencies of contaminant monitoring, and implementation of best
management practices for potential sources.
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Exhibit 2-6. Characteristics of Aquifers of High Hydrogeologic Sensitivity
• Course surficial soils
• Fractured or karst topography (although ihe presence of overburden may provide a measure of
protection)
• Extremely shallow depth to water and unconfined
• Young age of water
• Poor water quality
- NO3 > 5 mg/L in nonagricultural area
- pH>10 -
- Dissolved organic carbon (DOC) that is sewage-derived (caffeine levels)
• Groundwater located in or proximate to recharge zones in connection with a surface water body
(e.gv high seasonal water tables or seasonal ponding).
Criteria for ascertaining confining aquifers and deep sedimentary conditions are
further refined in Exhibit 2-7.
Exhibit 2-7. Characteristics of Confined and Deep Sedimentary Aquifers
Confined Aquifers as defined by one or more of the following criteria:
• Elevated pressure head above the water-bearing zone
• Competent confining layer as defined by:
- Thickness of the confining layer
- Lateral extent of me confining layer
- Hydraulic conductivity (a minimum K value)
- Low potential for artificial breaches m the confining layer (no breaches from injection or
agricultural retum-flow wells)
• Aquifer test data (continuous pump test with recovery data)
* Storativity indicative of confined conditions
• Documented regional determination of confined hydrologic settings.
Deep Unconsolidated Valley Fill Aquifers
• Thick deposit (regionally deep and extensive suite of sediments)
• Alternating layers of high- and low-hydraulic conductivity sediments
• Well that is screened in the bottom of the high-transmissivity water-bearing zone.
2.3.3 Useability and Appropriateness of Mathematical Models
The group began the work session with a lengthy discussion, including the
intricacies of mathematical models, the appropriateness of specific models, and the range
of specific parameters. Discussion was refocused on the utility of a conceptual model
that could provide regulatory decisionmakers with an assessment of whether the source
water for a system was protected adequately from fecal contamination so it did not
require disinfection. The mathematical modelers re-convened toward the end of the
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session to discuss the relevance of models as predictive tools. The team answered two
of its initial questions in the affirmative:
• We can make meaningful predictions of fecal contamination or protection
based on hydrogeological and microbial fate and transport data.
• There are rigorous and feasible criteria that can be used to make decisions
some of the time, if not all the time.
The synthesis of the discussion is shown in Exhibit 2-£. In summary, the
conceptual model of the decision tree created by the group is a conceptual model with
some quantitative components. This model may be applicable for many small systems.
These systems (or the regulators of the systems) will be required to determine whether
disinfection will be required or can be avoided because of natural disinfection processes
provided by a specific hydrogeologic scenario. More sophisticated mathematical models
will be useful for larger systems that have the technical and fiscal resources to select an
appropriate model, gather the necessary hydrogeologic data, and ascertain accurate and
reasonable input parameters. Mathematical models will be useful for systems that select
to implement a more refined, potentially less conservative, approach than the decision
tree developed. Modeling could also be used to refine the minimum 100-foot radius
default value to be integrated into the decision tree.
Exhibit 2-8. Useability and Appropriateness of Mathematical Models
• Information developed does not negate the usefulness of models
• If decision tree indicates inadequate protection, system can use a more sophisticated model
• Mathematical models require additional information about the system (e.gv dispersion, porosity,
velocity, uncertainty associated with each of these, and sorption, desorption, and deactivation of
microbes)
• Models can be useful to refine the 100-foot capture zone (minimum).
2.3.4 Applicability of Wellhead Protection Programs
The discussion of similarities and differences between the Wellhead Protection
(WHP) program and other source control programs indicated that the approach of these
programs can serve as a model for protecting the source waters. Exhibit 2-9 summarizes
the relevant similarities.
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Exhibit 2-9. Applicability of Wellhead Protection and Source Control Programs
• Approach of WHF program (seven-element program) is similar to wliat could be used for the
GWDR implementation when establishing source control, assessing likelihood of contamination,
and establishing zones of contribution
• Data available from the WHP program efforts
• "Adequate" WHP programs may assist in protection as a basis for not disinfecting
• Many WHP programs not currently concerned with fecal contamination and would need to
develop best management practices for human and animal waste
• "Acceptable" densities of fecal contaminant sources would need to be developed
• Sources of contamination need to be re-assessed through a WHP survey:
- Every 3 (preferred) to 5 years
- More frequently if conditions change.
Many pieces of data have been amassed for WHP programs and can be useful in
assessing natural disinfection processes. Many WHP programs focus on protection from
chemical contaminants rather than from biological contaminants; therefore, program
adequacy would need to be assessed individually. Some programs probably would
require adaptations to protect groundwater sources from fecatl contamination. This
approach is preferred over mandatory development of a new regulatory program.
2.4 RECOMMENDATIONS AND RESEARCIJ NEEDS
2.4.1 Recommendations
The following recommendations are a synthesis of the discussions of the Natural
Disinfection Team:
• Natural disinfection processes can provide adequate protection to groundwater
sources that are public water supplies; therefore, not all systems should be
required to provide disinfection—rather, the susceptibility and vulnerability of
groundwater sources should be assessed.
• A conceptual model such as the decision tree can be used to assess ground-
water sources at lower risk of fecal contamination. The decision tree reflects
all components of a hydrogeologic system, except protections provided by the
vadose zone. This conceptual model can be used to assess conditions at small
systems without the technical and fiscal resources required for greater
sophistication of mathematical models. Mathematical models can be useful for
delineating areas of contribution for larger systems with greater hydrological
and fiscal resources.
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Natural Disinfection Team
- A 2-year time of travel in the saturated zone was determined to provide
a conservative measure of protection from fecal contaminant sources
- Refinement of the decision tree is required to address the issues of vadose
zone transport of microbes
- The decision tree should also be integrated to include monitoring and
sanitary survey requirements into a single flowchart.
• More sophisticated mathematical models will be useful for larger systems that
have the technical and fiscal resources to select and implement an appropriate
model. Mathematical models will also be useful for systems that elect a less
conservative approach.
• WHP programs and other source control programs may serve as useful tools
to assess fixe protection of the source because WHP programs have amassed
vast quantities of data. Although all public water supply systems may not
have a. WHP program that is adequately protective, incorporation of microbial
protection components into existing programs is encouraged over a mandated
requirement to develop a new program.
2.4.2 Research Needs
One workgroup explored areas requiring additional research to provide validation
or verification of the components of the decision tree. Research needs are grouped
according to one of the following categories and ranked within each category as to the
importance of the need: validation of the decision tree, hydrogeological research, and
microbial research. A brief description of each need follows.
• Evaluation of Decision Tree as Predictive Tool
- Evaluate whether the predictions of low aquifer vulnerability are verified
by microbial analysis of water samples from those wells.
• Microbial Research
- The fate of pathogen indicators over various time and travel distances
needs to be investigated, particularly in the vadose zone. This may be just
a matter of technology transfer.
- Evaluate the effect of continuous versus slug loading of microbial
contaminants on their fate and transport.
- Evaluate the survival rate of animal viruses at temperatures at or below
8°C .,
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Natural Disinfection Team
- Discuss the role of natural predation within. soil/aquifer matrix on
reducing pathogens. How may the fact that protozoa consume bacteria
which consume viruses be used as predictors of pathogenic contaminant
reduction levels or as biological disinfection amendments to contaminated
systems?
Hydrogeological Research
- A method of geophysical logging needs to be ^developed to verify the
presence and integrity of well seals. This may be an issue of technology
transfer; however, at a minimum, a literature and technology search on this
topic needs to be performed.
- Develop a geophysical tool that can map aquifer heterogeneity regionally.
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3. SANITARY SURVEY TEAM
This section reports on the breakout session for the Sanitary Survey Team. It
describes the specific assignments given to this team, the process used to develop the
team's assigned products, the products developed., and additional recommendations.
3.1 INTRODUCTION
The Sanitary Survey Team consisted of personnel with expertise in conducting
sanitary surveys from several State environmental and health agencies, several
groundwater system operators/administrators, an EPA employee in the drinking water
program, a representative from the U.S. Department of Agriculture (USDA) Forest
Service, and a representative from the Association of State Drinking Water Adminis-
trators (ASDWA). This group of experts was well versed in drinking water treatment
technologies, construction issues, and the importance of conducting sanitary surveys to
ensure protection of public health.
A sanitary survey, as denned in 40 Code of Federal Regulations (CFR) 141.2
(Definitions) is an onsite review of the water source, facilities, equipment, operation and
maintenance, and monitoring compliance of a public water system for the purpose of
evaluating the adequacy of such source, facilities, equipment, and operation and
maintenance for producing and distributing safe drinking water.
A sanitary survey evaluates and documents the capabilities of a water system's
sources, treatment, storage, distribution network, operation and maintenance, and overall
management to continually provide safe drinking water and to identify any deficiencies
that might adversely impact a public water system's ability to provide a safe, reliable
water supply. (EPA/State Joint Guidance on Sanitary Surveys, December 1995)
The mission of this team, as dictated by the GWDR Regulation Development
Manager, was the following:
Mission
Develop a sanitary survey I correction of defects regulatory element of the GWDR.
The basic premise of this assignment was that sanitary surveys are a major
mechanism available to ensure that adequate protection of groundwater supplies is
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Sanitary Survey Team
provided. Furthermore, the existence and implementation of effective sanitary survey
programs and enforcement of remedial actions may preclude a system from a mandatory
disinfection requirement under the proposed GWDR. This team strongly posits that
sanitary surveys provide a first line of defense in ensuring that public water systems
provide safe water. Specific tasks initially assigned to this team were to:
Taskl
Develop a list of potential groundzvater system deficiencies typically identified
during a sanitary survey that should be corrected to ensure system integrity.
The product of this discussion will be a matrix that lists and prioritizes the
severity of these deficiencies.
Task 2
Develop a decision tree for groundwater systems to aid in the decision on
whether disinfection should be required.
Several additional questions were posed to this team during the workshop:
TaskS
How should the integrity of the distribution system (including storage) be
protected in lieu of requiring the use of a residual?
Task 4
How should construction codes and well siting be incorporated into the GWDR?
The process used by the group to address these assignments and the products of
the Sanitary Survey Team discussions are presented in Sections 3.2 and 3.3, respectively.
Further recommendations are presented in Section 3.4.
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3.2 METHODOLOGY/PROCESS
The facilitator of this group began the session by reiterating the assigned tasks
and expected products then asked how the group would like to proceed in formulating
the products. Before "putting pen to paper/' a lengthy discussion ensued regarding the
appropriateness of a mandatory disinfection requirement, especially for noncommunity
systems. A major concern voiced by several members of the group was that
noncommunities may be forced to use disinfection that could (1) mask a problem or
(2) create more problems if the chlorination system is not properly run .or maintained
(a distinct possibility with some noncommunity systems because of lack of resources and
operator training). The team stated that sanitary surveys should be viewed as the first
line of defense in the protection and maintenance of groundwater systems.
•\
The group was reminded that the main reason, they were asked to attend this
meeting was because of their expertise in conducting sanitary surveys. It was restated
that the GWDR Workgroup has agreed that the GWDR should not be written to require
mandatory disinfection of all groundwater supplies because it believes that public health
can be protected through other measures, such as a good sanitary survey program. This
team was established to develop information that could be used in guidance to help
regulators determine whether a system is adequately protected and maintained so that
disinfection is not required.
Once the group was comfortable with the fact that the GWDR Regulation
Manager intends to develop a GWDR mat will give more emphasis to the need for good
sanitary surveys, it emphasized that the rule should be written to give States the
authority to require sanitary surveys and enforce remedial actions (fix defects). The
team believes that sanitary surveys should be hiandatory as a first step instead of
allowing systems to make the decision to disinfect before assessing whether disinfection
is the most appropriate option and the most protective of public health.
Next, the team focused on the tasks at hand. Descriptions of the process used by
the team to complete its assigned tasks follow. The actual products developed by the
Sanitary Survey Team are presented and described in Section 3.3.
Task 1—Prioritized List of System Deficiencies Typically Identified During a Sanitary
Survey
To focus on accomplishing Task 1, the team reviewed the draft list developed in
May 1996 during the ASDWA/EPA GWDR Sanitary Survey Workgroup Meeting. The
ASDWA/EPA meeting was attended by representatives from Minnesota, Virginia, New
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Sanitary Survey Team
Hampshire, California, Illinois, Nebraska, EPA, ASDWA, AWWA, and ISTI, Inc. The
purpose of the meeting was to make as much progress as possible in developing the list
of deficiencies before this July meeting so that the Sanitary Survey Team could focus on
development of the assigned products. The list of deficiencies is divided into separate
categories—well source, treatment, storage, distribution system, monitoring and
reporting, and operations and maintenance.
The Sanitary Survey Team carefully revised the ASDWA/EPA list of deficiencies
and then went back through the list and arranged the deficiencies in order of their
potential severity. The severity of the deficiency is correlated with the potential need
for disinfection or the need for corrective measures if the system, is already disinfecting.
The rating system selected by the team is as follows:
• 1 = High Priority—This type of deficiency warrants immediate action
• 2 = Medium Priority—This type of deficiency is an imminent problem, not as
serious as #1 but potentially serious
• 3 = Low Priority—This type of deficiency would warrant a long-term
correction if the water quality remains acceptable. If the water quality becomes
unacceptable, the rating would go up.
To order the list of deficiencies, the team first listed high-priority items that are
serious problems requiring immediate action. Deficiencies considered to be low priority
were listed next; those issues that remained were considered to be medium priority.
The deficiencies matrix the team developed is presented in Section 3.3-Sanitary
Team Products.
Task 2—Develop a Decision Tree for Determination of the Need for Disinfection
Originally, the GWDR Regulation Development Manager had hoped for a detailed
decision tree listing all potential deficiencies; it would help a decisionmaker determine
a system's need for disinfection based on the results of a sanitary survey. The team
agreed that this was not possible; the decision-making process could not be generalized
because of the intricacies and differences among systems, the synergistic effects of types
of deficiencies, the myriad potential combinations of deficiencies, and other factors.
I i
The team therefore developed a very generalized schematic of the decision tree
for deciding whether to require disinfection. This chart is presented in Section 3.3.
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Task 3—How To Ensure the Integrity of the Distribution System Without Requiring
a Residual
Based on the Best Management Practices (BMP) proposed study provided by
ASDWA, the team developed a list of elements that should be in place to ensure that
adequate water quality is maintained throughout die distribution system. This list is
provided in the following section.
Task 4—How To Incorporate Construction Codes/Well Siting Criteria into the GWDR
The team developed proposed language and recommended that it be inserted into
the GWDR. This language is presented in the following section.
3.3 SANITARY SURVEY TEAM PRODUCTS
In this section the products discussed in Section 3.2 are presented and described.
The Sanitary Survey Team products consist of a matrix listing and prioritizing potential
deficiencies identified via sanitary surveys, a decision tree for determining whether
disinfection should be required, a list of elements; that should be in place to ensure
distribution system integrity, and proposed regulation language for incorporating
construction codes and well siting criteria into the GWDR.
3.3.1 Deficiencies Matrix
The matrix shown in Exhibit 3-1 presents the list of potential system deficiencies
identified by the Sanitary Survey Team. These are the types of things that are assessed
during a sanitary survey. Eventually, this list is be developed into guidance to aid in
the evaluation of whether a system is properly protected from ground water
contamination and whether the system is properly constructed, operated,, and
maintained. The guidance is to assist with the determination of whether disinfection
should be required. The Sanitary Survey Team emphasized that the deficiencies
identified during a sanitary survey should be corrected first, before installation of
disinfection. Although the list of deficiencies ultimately is to be used in deciding
whether to disinfect, the team also listed possible deficiencies in systems that already
disinfect, so that all sanitary survey issues are listed.
Also shown in Exhibit 3-1 are the priority ratings the team assigned to the list of
deficiencies. An important caveat to the priority ratings shown in this matrix is that all
systems have different characteristics (e.g., well depth, hydrogeological configurations,
and construction) and these ratings cannot be applied across the board. Furthermore,
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Sanitary Survey Team
Exhibit 3-1. List of Deficiencies Identified
in Sanitary Surveys of Groundwater Systems
1 » High Priority
2 « Medium Priority
3 35 Low Priority
Well/Source
Warrants immediate action
Imminent problem, not so serious but potential problem
Long-term correction warranted if water quality remains acceptable
1 Unsafe source (e.g., dead animals, wells of improper construction)
1 Wells of improper construction (improper as defined by State code)
1 Chronic coliform hits found in raw water samples
2 Improper draining of well site
2 Well in pit with improper drainage/construction
2 Improperly abandoned wells in proximity to operating wells
2 The presence of any physical means of contamination of the well (e.g., lack of screen vent,
presence of hole in well seal, pump-based drain, unprotected suction line, check valves below
grade)
3 Wells of unknown construction
3 Insufficient setback distance (e.g., to drywell, sewer lines, septic tanks) as defined by local or State
code
Treatment
1 Inappropriate or unapproved treatments that require disinfection (e.g., corrosion control)
1 Lack of proper cross connection control for treatment chemicals
1 Lack of redundant mechanical components where chlorination is required for disinfection
2 Inadequate CT
2 Improper use of bypass lines
2 Inadequate application of treatment chemicals
2 Inadequate recordkeeping of treatment history (e.g., daily logs)
2 Lack of overfeed/underfeed protection, where applicable
2 Inadequate monitoring and reporting to verify continuous disinfection where applicable
Storage
1 Improper venting of tank
1 Uncovered finished water reservoirs
1 Lack of proper screening of overflow pipe and drain
1 Inadequate roofing (e.g., holes in the storage tank, improper hatch construction)
1 Inadequate internal cleaning and maintenance (and recordkeeping) of storage tank
2 Insufficient circulation within tank
2 Improper drainage around ground-level storage tanks
2 Improper below-grade tank construction
3 Evidence of vandalism
3 Lack of protection against vandalism
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Sanitary Survey Team
Exhibit 3-1. List of Deficiencies Identified
in Sanitary Surveys of Groundwater Systems (Continued)
Distribution System
1 Unprotected cross-connection
1 Unacceptable system leakage that could result in entrance of contaminants
1 Inadequate monitoring of disinfection residual, when required
2 Inadequate flushing or inadequate means for flushing .; .
2 Subsurface air release/vacuum relief valves
2 Inadequate or fluctuating pressure levels ; .
2 Pump station or any appurtenances subject to flooding
2 Poor installation and repair procedures of mains and services
2 Lack of compliance with State cross-connection control program
3 Use of unapproved piping and appurtenances
Monitoring and Reporting
1 Lack of compliance with new indicator organisms
1 Lack of compliance with the Total Coliform Rule (TCR)
- Lack of sample siting plan
- Lack of coliform sampling after main repair
- Failure to conduct follow-up TCR monitoring
- Chronic TCR coliform detections with inadequate remediation
2 Failure to maintain cross-connection control program records
2 Failure of system operator to address customer compliance regarding water quality or quantity
issues
Operations and Maintenance
2 Failure to comply with State-specific O&M requirements
2 Lack of properly trained or licensed staff
2 Inadequate follow-up, including public notification, to deficiencies noted in previous inspection/
sanitary surveys ",
2 Lack of approved source water protection plan (including emergency response plan), if applicable
2 Inadequate maintenance of disinfectant residual
synergistic effects occur between types of low-priority deficiencies that could pose an
immediate danger and should be considered as high priority. For example, "improper
draining of a well site" is classified as a low-priority deficiency; however, if coupled
with a medium-priority deficiency, such as the presence of a hole in the well seal or
some other improper protection of the wellhead, this could be a serious problem,
especially if the well were downslope from a feedlot
Exhibit 3-1 reflects the few changes made to the original list based on comments
from workshop attendees when all of the teams reconvened to present the current status
of their assignments. .
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3.3.2 Decision Tree
The Task 1 exercise helped with Task 2; the goal was to develop a decision tree
or checklist as guidance to help decisionmakers determine whether a particular
groundwater system should be required to disinfect. The team agreed that this is not
a cut-and-dried process that can be developed into a detailed decision tree because each
system must be assessed on a case-by-case basis. The team,, however, did develop a
generalized decision tree, shown in Exhibit 3-2. . .
Exhibit 3-2. Draft Flow Chart/Decision Tree
for Deciding Whether To Require Disinfection
Conduct
Sanitary
Survey
Yes
Are
Major
Deficiencies
Identified?
Have Deficiencies
Been Corrected?
Yes
No
Is Water
Quality Acceptable?
No
Yes
Disinfection
May Be Required
Disinfection May
Not Be Required
852E-01
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The decision process basically consists of the conduct of a sanitary survey and
identification of whether major deficiencies exist. If the deficiencies have been corrected
and water quality problems still exist, then disinfection may need to be required. If
major deficiencies are not identified and the water quality is found to be unacceptable
then, again, disinfection may be warranted. Disinfection may not be warranted if no
major deficiencies are identified and if water quality remains acceptable.
3.3.3 Elements Necessary for Distribution System Protection
Exhibit 3-3 lists the elements the team agreed should be required to be in place
under the GWDR to ensure the integrity of a groundwater systems distribution system
in lieu of requiring the addition of a residual.
Exhibit 3-3. Ensure the Integrity of the Distribution System (Including Storage)
in Lieu of Requiring a Residual
Include as part of the rule the requirement that the State ensure that these elements are in place at the
groundwater systems for which they are applicable:
• Cross-connection control/backflow prevention program.
• System water mains installed in accordance with applicable State criteria/codes/regulations
• Disinfection of newly installed water mains and following repair of mains after breakage
• System maintains an acceptable distribution system pressure,at all times
• System implements water main flushing program ;
• Water distribution system storage tanks are designed, constructed, maintained, and disinfected
according to applicable State criteria/codes/regulations
• Distribution system storage tanks are inspected and cleaned routinely
• Distribution system storage tanks are disinfected after repair
• Water cycles through water distribution system storage tank on a frequent basis
• Distribution system maintenance plan
• Leak detection system
• Other
3.3.4 Construction Codes/Well Siting Requirements
The Sanitary Survey Team recommends that the following language be placed in
the GWDR so that construction codes and well siting requirements are incorporated into
the GWDR and receive the attention they warrant:
"Before primacy can be granted to a State, under the GWDR, a State must
have in place well siting and construction codes/criteria."
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3.4 RECOMMENDATIONS/ADDITIONAL RESEARCH
No additional research efforts were identified by the Sanitary Survey Team.
However, several recommendations were developed by the team and are shown in
Exhibit 3-4.
Exhibit 3-4. Sanitary Survey Subcommittee Recommendations
Recommendation 1
Make the following overall objective more explicit in the GWDR:
• The first public health priority should be correction of identified sanitary defects, not disinfection
of all groundwater supplies. Therefore, the rule should not be written in a manner that implies
that disinfection in all cases is an appropriate alternative to the correction of defects.
Recommendation 2
• State primacy agencies must have/be able to obtain authority to enforce compliance with the State's
siting/construction codes/criteria and the correction of identified sanitary defects.
Recommendation 3
• A source of funding shall be identified to correct defects in all public w ater supplies (private and
publicly owned) identified through the sanitary survey process developed for this rule.
Recommendation 4
• Suggested new names for the GWDR:
- Groundwater Protection Rule
- Groundwater Treatment Rule
- Source Water Protection Rule
- Groundwater Quality Optimization Rule.
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4. MICROBIAL MONITORING TEAM
This section describes the discussions and findings of the Microbial Monitoring
Team. The team discussed the utility and practicality of monitoring groundwater and
distribution system water for assessing the vulnerability of a well to pathogens or fecal
contamination.
4.1 INTRODUCTION
The Microbial Monitoring Team was composed of university teaching and
research professionals and personnel from State departments of health and the
environment, the U.S. Geological Survey, the AWWA Research Foundation, and the EPA
Office of Science and Technology and Office of Ground Water and Drinking Water.
After introductions, the chair summarized the discussions of five previous
teleconferences held in 1996 on the topics of interest He pointed out that several
important topics remained to be resolved. The most basic unresolved issue follows:
Can the public be protected from fecal contamination of groundwater without
requiring all systems to disinfect?
The team unanimously agreed that protection could be ensured without requiring all
systems to disinfect.
The team then turned to determining monitoring requirements, including the
following issues:
• To what extent do the approaches currently in use for monitoring and/or
research purposes actually tell us whether the water is contaminated with fecal
material?
• Which pathogens and/or indicators are appropriate for an assessment of
source water quality, and how many samples are needed?
• Should microbial monitoring involve a determination of microbial density, or
would the mere presence or absence of the target organism suffice?
• What is the association between pathogenic viruses and bacteriophage in soil
and subsurface water, and how does this correlation vary with methodology
and environmental factors? The same questions arise for pathogenic viruses
and enterococci, coliforms, chemicals, and other indicators.
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Microbial Monitoring Team
• Where should samples to assess vulnerability be taken—from the tap or source
or both?
• What are typical virus densities in sewage and what correlation exists in
sewage between viral pathogens and indicators?
• What critical microbiology date does EPA need to have before publishing the
GWDR? What technical assumptions in microbiology are proper for EPA to
make in developing the rule in the absence of sufficient data?
4.2 METHODOLOGY/PROCESS
' '
i
There are two questions to ask in determining monitoring requirements: Is there
sewage contamination in the well? If so, what is the risk to human health? The team
assumed that if an assessment indicates the presence of fecal contamination, a system
would be required to disinfect and to increase the amount of monitoring. A second
assumption also was made mat monitoring requirements would identify whether the
source of contamination is within the distribution system, at tne wellhead, or in the
source. To answer the first question, the team identified the following potential
indicators of fecal contamination:
• Escherichia coli (£. coli)
• Enterococri
• Clostridium perfringens
• CoHphage (somatic phage and male-specific phage)
• PCR (polymerase chain reaction) for pathogenic viruses
• Microscopic particulate analysis (MPA)
• Pathogenic protozoa (e.g., Giardia and cryptosporidium)
• Chemical indicators
• Total coliforms
• Enteric viruses.
The team agreed that no indicator of pathogenic or fecal contamination was
perfect, but that some indicators may be adequate. For example, drinking water that has
tested positive for total coliform bacteria usually has no pathogens present.
Of the 10 indicators listed above, 2 were eliminated from further consideration.
Microscopic particulate analysis (MPA), which involves the microscopic examination of
a water sample using a battery of tests (e.g., Giardia, insect parts, leaf material) was
judged too costly, and thus eliminated from further consideration.
Final
4-2
September 1996
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Microbial Monitoring Team
Testing for viruses (by culture methods) or protozoa was discarded because of the
high cost (about $400+/sample for protozoa and higher for viruses) and the large sample
volume needed (up to 1,000 liters). It was also mentioned that the detection of Giardia
and Cryptosporidium in the well water would strongly indicate the direct influence of
surface water and would therefore require the system to conform to EPA's Surface Water
Treatment Rule. . •
The team decided to develop a matrix of indicators to evaluate their suitability
for use in determining fecal contamination in groundwater based oh sensitivity and
specificity. Selected indicators were evaluated for occurrence, survival, laboratory
availability, sample size, and cost. Section 4.3 presents the discussion of each of the
potential indicators under consideration.
4.3 MICROBIAL MONITORING TEAM PRODUCTS
The team discussed the following indicators:
• Polymerase Chain Reaction (PCR) for enteric viruses—This method, which
involves the amplification of selected strainds of nucleic acid, can be used to
detect viral presence. There appears to be a link between virus culture-
positives and PCR-positives for the enteroviruses. However, the use of PCR
for virus detection is expensive because of the large sample volumes needed
(perhaps up to 1,000 L). Also, some training would be needed to collect this
. large sample volume. For these reasons, the team relegated PCR as a
secondary monitoring tool, i.e., to be used only when a less expensive test
revealed a possible presence of fecal contamination.
PCR is, recommended for use as a secondary test because it is a useful indicator
for fecal contamination. If there are positive results from E. colt and
enterococci, then PCR could be used to further refine the assessment. PCR is
a viable tool; it is not recommended as an initial indicator test because of the
large sample size required and the high cost of analysis.
• Heterotrophic bacteria—It appears that an adequate correlation between
viruses and heterotrophic bacteria in groundwater does not exist. Moreover,
an increase in heterotrophic bacteria does not necessarily suggest an increased
likelihood of fecal contamination. Therefore, the heterotrophic bacteria group
was not considered promising as an indicator.
• Enterococci—Testing for enterococci is easy and inexpensive and has a good
correlation between the group of organisms and the incidence of disease in
recreational waters. Sample size is a fa.ctor in determining sensitivity for
enterococci as an indicator. In conjunction with E. coli, enterococci could be
used as a good initial indicator for fecal contamination.
Final
4-3 September 1996
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Microbial Monitoring Team
Clostridium perfringens—C. perfringens is apparently only associated with fecal
material. However, its spore can survive for a long time in soil and water, far
longer than the pathogens. The team considered this organism useful,
especially in conjunction with other tests.
Coliphage—This easy and fairly inexpensive test may be suitable as a
monitoring tool. One to ten liter sample volumes may suffice, perhaps even
lower, probably keeping the total cost per sample well below $100. The utility
of the two groups of coliphages was discussed—the somatic coliphages and
male-specific coliphages.
i
Somatic coliphage infects E. coli through the cell waH. Although this group of
non-heterogenous viruses is not present in all human hosts, it is common in
sewage. Its presence apparently indicates fecal contamination. However, the
ecology of various strains of somatic phage in soil is; not known, and it is
possible that common soil organisms may serve as reservoirs for some of the
strains. The team suggested that further study was necessary on this point to
assess .its utility as an indicator.
Male-specific coliphage infects E. coli only through sex pili. These phage are only
found when fecal contamination is present; therefore, il: is important to devise
an analytical test that finds only the phages that are male-specific. If a small
(>100) human population is observed, there may not be male-specific
coliphages present; however, with raw sewage generated from more than 100
people, male-specific coliphages usually are present in concentrations of
approximately iOVmilliliter (ml). This phage is relatively persistent.
Total Coliforms—There was little support for the use of total coliforms as a
determinant of fecal contamination in the well. This group of organisms is
often present in soil and water in the absence of fecal contamination.
However, all systems, including the smallest, are currently monitoring total
coliforms in the distribution system on a routine basis. Thus, its use under the
GWDR cannot be dismissed totally.
E. colt—E. coli is a sensitive indicator for fresh fecal contamination. However,
it dies out more rapidly than many pathogens and other indicators (including
coliphage).
Chemicals (e.g., caffeine, sterols, optical brighteners, detergents)—The team
evaluated several possible chemical indicators of fecal contamination of
groundwater. Caffeine may be adequate as an indicator in surface water, but
may be too biodegradable as it moves through the soil and groundwater.
There is not enough information on sterols.
Southern California, which employs numerous water reclamation projects,
treats wastewater aggressivety. In these locations, extensive monitoring is
Final
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September 1996
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Microbial Monitoring Team
required to observe potential impacts on groundwater. Abiotic indicators, such
as caffeine and optical brighteners used in laundry detergents, have shown
promising characteristics in detecting the presence of wastewater. The
committee considered these indicators as part of a tiered approach in which the
abiotic indicators could be used to initially determine whether groundwater
had been contaminated by wastewater.
Chemicals are not considered good candidates for indicators because of a lack
of data on their behavior in groundwater systems.
In summary, each of the previously listed indicators was evaluated for sensitivity
and specificity for fecal contamination at the wellhead. The results are given in Exhibit
4-1.
Exhibit 4-1. Sensitivity and Specificity of Indicators
Indicator
£. coli
Enterococci
HPC
PCR
Total colif orm
Phage somatic
Phage male-specific
Chemicals
Clostridium perfringens
Sensitivity
Yes
No
No :
Yes
No
Yes
Yes (>100 population)
Maybe
Yes
Specificity
Yes
Maybe
Yes
Yes
Yes
No
Yes
Maybe
•Maybe
The team judged that monitoring to assess well vulnerability should be performed
at the well rather than in the distribution system, because of confounding factors in the
latter. ,: • "
Based on discussions and explanations presented previously, the team selected the
following potential indicators as useful in determining fecal contamination in
groundwater:
• E. coli
• Enterococci
• Clostridium perfringens • .
• Coliphage (somatic and male-specific).
Final
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September 1996
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Microbtal Monitoring Team
For these four indicators, the team discussed indicator occurrence, sample volume,
cost for sampling, and laboratory capabilities. They also discussed whether indicators
should be used for initial monitoring and, if so, what the monitoring frequency should
be.
•i
A major concern was that populations with very small systems usually do not
have the economic base to support a heavy monitoring schedule of tests. The team
members addressed other considerations for each promising monitoring tool, such as the
availability of. a standard analytical method, survival rates in the subsurface, sample
Volume, and initial densities in sewage or feces. The following information was
reported:
• E. coli occurrence is about 109/liter of raw sewage. Raw sewage is a major
source of intrusion into the subsurface system. The survival rate of E. coli
ranges from weeks to months, depending on the strain and the temperature of
the grbundwater.
E. coli and enterococci have survival times that are too short to be used as
indicators for viruses. A marker for the viruses needs to be found that has a
longer survival rate. Marylynn Yates has done much of the work on survival
rates; her work should be reviewed.
Finding E. coli and enterococci in groundwater indicates a definite problem
with the source water, which may be sufficient to require disinfection.
The sample size for E. coli should be one liter. Sample size and frequency have
to be reconciled with other information, including flow rates and historical
information about the health of the system. For intermittent contamination, the
volume of samples will not be of major importance. Low-level contamination,
however, is a matter of the density of the microbes in the water, and sample
size is critical. Research shows that better testing results are obtained by
taking five 100-ml samples rather than a single 500-ml sample. In any event,
the major concern will be the frequency of sampling rather than the sample
size.
Sampling must address intermittent and continuous contamination. A search
of the literature should be performed to determine the impact of sample size
in reaching the decision to increase sample size from 100 ml to one liter. This
issue is not considered a problem at this stage of regulation development.
The current cost for E. coli testing is about $15 per sample and laboratory
capabilities already exist.
Final
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September 1996
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Micrdbial Monitoring Team
Enterococci occurrence is visually 107/liter of raw sewage. Laboratory
capability exists with standardized methods. The sample volume needed is the
same as for E. coli (e.g., 100 ml to one liter). Survival rates are similar to E. coli,
but a literature search is needed to establish certainty; enterococci have a
longer half-life than E. coli in soils.
Clostridium perfringens survive months to years and the occurrence in raw
sewage is approximately 106/liter. A literature search is needed to confirm
these projections. C. perfringens are not always present in instances of fecal
contamination and there is an uncertainty about its survival and occurrence in
ground water. More research is needed on the survival and occurrence of C.
perfringens in groundwater. -
The American Society for Testing and Materials (ASTM) method for C.
perfringens has been cbllaboratively tested and approved by two different
groups and carries a cost of $25 to $27 per sample. The sample size should be
100 ml or more as dictated by statistical procedures. Laboratories that perform
fecal cpliform testing can perform this test easily with minor modifications to
existing laboratory procedures.
Somatic phages and male-specific phages occur at a concentration in raw
sewage of 106/liter. Somatic phage occurrence in humans is between 10 and
50% and the occurrence of male-specific phages is 1 to 3% in humans.
Because there have been only a few studies performed on the occurrence of
phages in septic tanks for household or small populations, more research needs
to be done in this area. Occurrence of phages in large cities is known to be
high. Phages may multiply in fresh raw sewage but probably only through
one cycle. The phages are not known to proliferate in groundwater. If the
coliform level is below 106/ml with temperatures below 25 degrees C, phages
will npt grow.
Part of the dilemma is that not much is known about the microbial ecology of
the somatic phages. There may be somatic coljphages that proliferate in wells,
biofilms, or even in the groundwater environment that are not only affecting
E. coli, but also other coliform organisms that might be present. This scenario
is undocumented but highly possible.
Survival of somatic phages is good in groundwater. Male-specific phages
survive well at low temperatures; at temperatures above 15 to 20 degrees C,
they do not survive appreciably longer than such bacteria as E. coli and
enterococci.
The methodology for somatic and male-specific phages is essentially the same.
Without sample concentration, the method should cost about $25. With
sample concentration, according to one member, perhaps $50. Using Bill
Yanko's (County Sanitation Districts of Los Angeles County) method, a one
Final
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September 1996
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Microbial Monitoring Team
gallon sample could be used without concentration at a cost of $25. Statistical
procedures may dictate that several small samples are preferable to one large
sample.
The State representatives to the team suggested that if any requirement for
delivering samples to laboratories within 8 to 24 hours is attached to the methodology
for any indicator, that method would probably not be used. The small systems do not
have the wherewithal to meet such stringent delivery requirements. There is a need to
establish an ASTM method for testing; this could be accomplished within 6 months.
Representatives from the States indicated that States already have some
developmental sampling for initial installation of wells that require monitoring for
chemical and bacteriological occurrence. This information is used to determine a
baseline for assessing the need for treatment. Traditionally, the State of Colorado looks
at total colif orms by most probable number (MPN) analyses. If results are positive, then
tests for fecal cbUform that do not include E. coli are performed A minimum of five
samples are taken over a 2- or 3-day period; if any are positive, then the second testing
of 20 samples taken over a 24-hour period is performed.
Other States require 36 consecutive safe samples over a period from 1 month to
3 years for a system to waive disinfection requirement. The number of samples among
States ranges from 1 to 36 for initial monitoring. According to one team member,
positive tests for E. coli should be assessed in the light of sanitary survey results and
other mitigating factors.
The team recommended that States be surveyed to find out what microbiological
requirements exist to waive a disinfection requirement. A similar .study has already
been done by Jon Merkle, EPA Region 9. This study was a comparison of well
construction codes for all 50 States.
4.4 RECOMMENDATIONS/ADDITIONAL RESEARCH
4.4.1 Recommendations
• ]
Exhibit 4-2 summarizes the occurrence, survival, lab availability, sample size, and
laboratory cost of the most promising indicators selected by the team. The group did
not feel there was enough information to make good recommendations about the
suitability of any of the indicators or combination of indicators for initial or routine
monitoring. These discussions were postponed until complete literature searches have
Final
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September 1996
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Micrdbial Monitoring Team
been performed and additional information regarding survival and transport rates can
be obtained.
Exhibit 4-2. Parameters for Indicators
Indicator
E. coli
Enterococci
C. perfringens
Somatic
phages
Male-specific
phages
Occurrence
lO'/liter of raw
sewage, found 100%
in human stool
107/liter of raw
sewage, found 100%
in human stool
lOVliter of raw
sewage, found 100%
in humans and
animals
lO'/liter of raw
sewage, found 50% in
humans
106 /\iter of raw
sewage, found 1 to
3% in humans
Survival
Week to months,
not very
biodegradable
Weeks, lasts
longer in soils
Months to years
Weeks
Weeks
Lab Availability
Good
Good
Good
Large number
can do testing
but currently
are not doing it
Large number
can do testing
but currently
are not doing it
Sample Size
100 ml with
multiple
samples
100 ml with
multiple
samples
100 ml with
multiple
samples
100 ml with
multiple
samples
100ml with
multiple
samples
Cost
$15 /sample
$15/sample
$25 /sample
$25 /sample
$25/sample
The team concluded the discussion on indicators to be used for fecal
contamination by recommending the steps to be taken next. These next steps are
presented in Section 5 of this report. There was consensus among the team that all of
the issues that could be addressed by this group were explored effectively for validity
and practicality. :
4.4.2 Additional Research
After extensive deliberation, the team determined that the following research on
the identified potential indicators for fecal contamination of groundwater at the wellhead
has already been done and should be reviewed. A comprehensive literature search is
needed for all indicators. :
• E. coli
- Survival data—Gordon McFeters, Montana State University; Gene Rice,
EPA National Risk Management Research Laboratory in Cincinnati;
Marylynn Yates, University of California at Riverside
- Sample size—Betty Olson, University of California at Irvine; Chuck Hass,
Drexel University
Final
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September 1996
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Microbial Monitoring Team
• Enterococci
- Survival data—Gordon McFeters, Montana State University
i' • I
• C perfringens
— Occurrence—A literature search is needed
• Somatic and male-specific phages
i . -. '
- Occurrence—Dan Deborde, University of Montana; R.E. Havelaar,
Netherlands; Vic Cabelli, Israel.
The team reached a consensus that certain research items were needed to support
promulgation of the GWDR. Recognizing the time constraints on long-term research,
the team rated the following research items for their criticality:
E. coli survival
Appropriate methods for enterococci
Presence of dostridium in groundwater
Transport of clostridium spores in subsurface
Occurrence of coliphage in septic tanks
Host range of somatic coliphage
Prevalence of male-specific coliphage in sewage
from small populations
Prevalence of human enteric viruses in sewage
from small populations
Not critical
Not critical
Critical
Not critical
Not critical
Critical
Critical
Critical
Final
4-10
September 1996
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5. SUMMARY/NEXT STEPS
This section summarizes the proceedings of the "Workshop on Predicting
Microbial Contamination of Groundwater Systems/' It also presents concluding remarks
made by the GWDR Regulation Development Manager and describes the "next steps"
agreed to by the participants in each of the workshop teams.
5.1 SUMMARY
The workshop was highly successful and the products of the teams were very
good, primarily because of the talents and expertise of the attendees. Each of the teams
made substantial progress.in development of their assigned products.
5.1.1 Natural Disinfection Team :
The Natural Disinfection Team discussed conditions under which groundwater
systems may be protected naturally from microbial contamination.
The team concluded that natural disinfection processes can provide adequate
protection to some groundwater sources that are public water supplies. Thus, not all
systems should be required to provide disinfection, but rather the susceptibility and
vulnerability of groundwater sources should be assessed.
A conceptual model, such as the decision tree, can be used to determine
groundwater sources at lower risk of fecal contamination. The decision tree can be
particularly useful for assessing small systems without the technical and fiscal resources
required for greater sophistication of mathematical models. Mathematical models can
be useful for delineating areas of contribution for larger systems with greater
hydrological and fiscal resources. However, the decision tree needs to be refined based
on the following:
• Evaluation of whether the predictions of low aquifer vulnerability are verified
by microbial analysis of water samples from those wells.
• The magnitude of deactivation of microbes in transport through the vadose
zone and soils.
• The decision tree must be integrated with an approach to monitoring and with
the results of sanitary surveys.
Final
5-1
September 1996
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Summary/Next Steps
5.1.2 Sanitary Survey Team
The Sanitary Survey Team discussed, at length, the types of groundwater system
deficiencies that can be identified during a sanitary survey; these deficiencies were
prioritized in order of severity that may trigger the need for disinfection. A very
generalized decision tree was developed for deciding whether a system should be
required to disinfect. The team also developed a list of elements that should be required
to ensure the integrity of a distribution system in lieu of a residual requirement.
The Sanitary Survey Team felt strongly about the need to emphasize in the
GWDR the importance of conducting sanitary surveys. The group believes that the
sanitary survey should be the first line of defense in ensuring safe drinking water and
should be conducted prior to requiring disinfection. Further, they feel that the GWDR
should give States the authority to enforce sanitary survey programs and to require that
identified system deficiencies be corrected.
5.1.3 Microbial Monitoring Team
The Microbial Monitoring Team assessed several candidcite monitoring tools for
their utility and practicality as an indicator of fecal contamination or pathogen presence.
The five indicators are E. coif, enterococci, Clostridium perfringens, somatic phages, and
male-specific phages. The team concurred that PCR is a useful indicator, but present
limitations would make it more suitable as a second line of testing.
The parameters discussed for each of the five indicators were occurrence, survival
rate, laboratory availability, sample size, and cost. Determinations of the frequency of
monitoring and on the usefulness of each indicator as an initial or routine testing tool
were deferred pending additional literature searches and field research. The strongly
expressed opinion of the team was ihat none of these tests should be use singularly, but
that greater benefit would be derived from using a combination of these test methods.
5.1.4 Overall
The major elements identified during the team breakout sessions will be refined
to become the major elements of the GWDR. Further refinements must integrate the
elements for incorporation into the GWDR. Currently, the GWDR Regulation Manager
envisions the following two options for incorporating these elements into the rule:
Final
5-2
September 1996
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', . Summary/Nesct Steps
• Initially, the GWDR Workgroup was leaning toward developing the GWDR
around the concept of requiring disinfection but incorporating "avoidance
criteria" that/if met, could preclude a system from disinfecting. A system
could avoid disinfection based on source water, system integrity, or monitoring
results. This approach is an option primairily because of how the language of
the law has been structured.
• The more likely, more desirable, option is that the GWDR will be based on the
concept of multiple barrier protection, which is exactly what is used in the
SWTR. The Enhanced SWTR probably will consist of multiple barriers, such
as source protection, filtration, disinfection, distribution system protection, and
monitoring. A multiple barrier approach for GWDR would consist of source
water protection, system integrity, and monitoring. Whether these barriers are
adequate and vigorous enough to ensure protection in each of those elements
is still to be determined.
The GWDR Regulation Manager stated that although more work is needed to
refine the elements of the multiple barrier concept, substantial progress was made
during this workshop. For example, criteria for source water protection were developed
by the Natural Disinfection Team. These criteria are designed to predict groundwater
vulnerability to microbial contamination. The GWDR Regulation Manager stated that
these criteria could be incorporated into the GWDR and written in a manner so that the
criteria would be enforceable. i
. j
Well construction and the other sanitary survey elements also can be developed
and incorporated into a barrier approach. The monitoring can be folded in and may
consist of wellhead monitoring, particularly for more vulnerable wells. Therefore, the
GWDR Regulation Manager is confident that these pieces can be fit together as a
multiple barrier approach for protecting groundwaier.
The criteria will need to be refined and eventually field tested to determine
whether the criteria are predictive of system vulnerability to microbial contamination.
Currently not a lot of data are available for making these assessments. The Regulation
Manager intends to take the following steps to validate these criteria:
• Develop and refine the criteria , . •
• Test the criteria with available data
• Continue to validate the criteria with supplemental data from ongoing studies
as they become available.
Final
5-3
September 1996
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Summary/Next Steps
5.2 NEXT STEPS
Specific next steps developed by each of the teams are listed below:
• Natural Disinfection Team—The Natural Disinfection Team spent the last few
minutes of the session brainstorming on additional areas requiring attention
before submittal of a final decision tree. Descriptions of these areas of further
refinement and evaluation follow:
- Descriptions of additional hydrogeological settings are not addressed in the
decision tree (e.g., the use of water quality parameters as indicators of
hydrologic conditions that have low sensitivity or susceptibility).
- The magnitude of deactivation of microbes in transport through the vadose
zone and soils should be viewed as the relative protection provided by the
vertical contaminant migration to the total time of travel.
- Definition of specific ambient aquifer conditions that make "fixed shape"
approach to delineating an area of protection inappropriate. Specified
fixed shapes may need to be prescribed or recommended for specific
conditions. For example:, the pencil shape may be used for highly
transmissive aquifers. An umbrella shape could be prescribed under other,
less transmissive, conditions.
- The decision tree does not discuss contingencies for responding to releases
within a zone of concern. Contingencies should be contained within any
guidance document that is developed; in addition, BMPs for waste sources
heed to be identified in a guidance document.
- The decision tree needs to be expanded to include monitoring. For
example, if monitoring results have indicated no microbial contamination
in the past, yet the aquifer is in a moderately susceptible or vulnerable
setting, additional monitoring may be recommended rather than
disinfection. These scenarios need to be developed integrating monitoring
into the decision tree.
- A discussion needs to be convened on an approach to rule-making that
would require monitoring for all systems before an assessment of
vulnerability.
- Encourage the incorporation of microbial protection into State and
community wellhead protection programs rather ihan a strict regulatory
approach of new program development.
i ! ,j
• Sanitary Survey Team—The Sanitary Survey Team agreed that the list of
system deficiencies must be expanded upon and sanitary survey guidance for
Final
5-4
September 1996
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Summary/Next Steps
groundwater systems should be developed. Additionally, field test criteria to
determine if the criteria are predictive of system vulnerability.
• Microbial Monitoring Team—The Microbial Monitoring Team decided that
additional literature searches and field research needed to be performed before
recommendations could be made on the appropriate indicators to be used for
initial and routine monitoring and on sample collection frequencies.
Additionally, the States should be surveyed to determine the monitoring
methods and frequencies that are already being employed.
The GWDR Regulation Manager will refine and integrate the criteria developed
by the three teams and incorporate them into the GWDR as a multiple barrier approach
to protecting groundwater supplies. This concept will be presented to the Assistant
Administrator of the Office of Water in mid-September. It is anticipated that the
proposed GWDR will be published in approximately 2 years.
Final
5-5
September 1996
-------
APPENDIX A
EPA WORKSHOP ON PREDICTING MICROBIAL
CONTAMINATION OF GROUNDWATER SYSTEMS
Attendees List
-------
APPENDIX A. EPA WORKSHOP ON PREDICTING MICROBIAL
CONTAMINATION OF GROUNDWATER SYSTEMS
Attendees List - Updated 7/16/96
Morteza Abbaszadegan
American Water Works Service Company
1115 S. Illinois Street
Bellsville, IL 62220
Phone: 618-235-3600 Fax: 618-235-9771
Martin Allen
Director, Technology Transfer
American Water Works Assocation, Research
Foundation
6666 W. Quincy Avenue
Denver, CO 80235
Phone: 303-347-6107 Fax: 303-730-0851
mallen@awwarf.com
Pamela Ansley
Clarkson Systems & Analyses, Inc.
1713 Gosnell Road
Vienna, VA 22182
Phone: 703-242-5137 Fax: 703-242-5649
Tom Atherholt
Research Scientist
New Jersey Department of Environmental
Protection
Division of Science & Research
401 E. State Street, CN 409
Trenton, NJ 08625-0409
Phone: 609-984-2212 Fax: 609-292-7340
tatherho@dep.state.nj.us
Paul Berger
U.S. Environmental Protection Agency
401 M Street, SW
Mail Code 4304
Washington, DC 20460
Phone: 202-260-3039 Fax: 202-260-3762
Jerry Biberstine
Colorado Dept. of Public Health and the
Environment
4300 Cherry Creek Drive, South
Denver, CO 80222-1530
Phone: 303-692-3546 Fax: 303-782-0390
jerry.biberstine@state.co.us
Robert Blodgett
Vulnerability Assessment Team Leader, Public
Drinking Water Program
Texas Natural Resource Conservation
Commission
Water Utilities Division/MC 155, Public
Drinking Water Section
TNRCC, P.O. Box 13087
Austin, TX 78711-3087
Phone: 512-239-6036 Fax: 512-239-6050
rblodget@smtpgate.tnrcc.state.tx.us
Judy Bloom
CA Wellhead Protection Project Officer
U.S. Environmental Protection Agency
75 Hawthorne Street, W-6-3
San Francisco, CA 94105-3901
Phone: 415^-744-1829 Fax: 415-744-1235
bloom.judy@epamail.epa.gov
Jackye Bonds
Ground Water Protection Branch
U.S. Environmental Protection Agency Region 4
345 Courtland Street, N.E.
Atlanta, GA 30365
Phone: 404-347-3866, ext. 6649
BONES.JACKYE@epamail.epa.gov
Susan Bradford
Principal Regulatory Investigator
Orange County Water District
10500 Ellis Avenue
P.O. Box 8300
Fountain Valley, CA 92728-8300
Phone: 714-378-3214 Fax: 714-378-3373
Koby Cohen
Sanitary Engineer
CDHS
Drinking Water Program
1449 Tample Street, Room 202
Los Angeles, CA 90025
Phone: 213-580-3127 Fax: 213-580-5711
kcohen@msn.com
Final
A-l
August 1996
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EPAWorkship on Predicting Microbial Contamination of Groundwater Systems
M. Yavuz Coraptioglu
Texas A&M University
Department of Civil Engineering
College Station, TX 77805
Phone: 409-845-9782 Fax: 409-862-1542
Ricardo De Leon
Principal Microbiologist
Metropolitan Water District of Southern
California
700 Moreno Avenue
LaVeme,CA 91750
Phone: 909-392-5185 Fax: 909-392-5246
Ricardo_deleon@mwd.dst.ca.us
Dan DeBorde
Assistant Professor
University of Montana, Missoula
Division of Biological Sciences
University of Montana
Missoula, MT 59812
Phone: 406-243-2389 Fax: 406-243-4184
deborde@selvvay.umt.edu
Karen Doherty
Environmental Analyst
Massachusetts Department of Environmental
Protection
Division of Water Supply
One Winter Street, 9th Floor
Boston, MA 02108
Phone: 617-292-5775 Fax: 617-292-5696
kdoherty@state.ma.us
Robert Dunlevy
Drinking Water/Ground Water Branch
U.S. Environmental Protection Agency Region 7
726 Minnesota Avenue
Kansas City, KS 66101
Phone: 913-551-7798 Fax: 913-551-7765
Dunlevy.Robert@EPAMAIL.EPA.GOV
Stephen Edberg
Yale University School of Medicine
Box 20835, Yale Medical School
333 Cedar Street
New Haven, CT 06520
Phone: 203-785-2437 Fax: 203-737-4170
Stephen.Edberg@quickmail.yale.edu
Cindy Forbes
Chief, Central California Section, Drinking Water
Field Operations Branch
California Department of Health Services
5545 E. Shields Avenue
Fresno, CA 93727
Phone: 209-297-3771 Fax: 209-297-3873
cforbes@hwl.cahwnet.gov
Charles Gerba
University of Arizona
Department of Soil, Water, and Environmental
Science
Tucson, AZ 85721
Phone: 520-621-6906 Fax: 520-621-6366
gerba@aruba.CCIT.Ariizona.edu
Henk Haitjema
Indiana University
School of Public Health and Environmental
Affairs
2323 Rock Creek Drive;
Bloomington, IN 47401
Phone: 812-336-2464 Fax: 812-336-2508
haitjema@indiana.edu
David Hansen
Environmental Specialist
Georgia Department of Natural Resources
Environmental Protection Division, Water
Resources Management Branch, Drinking
Water Program
GWUDI Evaluation Section
Floyd Towers East, Suite 1362
205 Butler Street, SE
Atlanta, GA 30334
Phone: 404-651-5160 Fax: 404-651-9590
david_hansen@mail.dnr.state.ga.us
Ron Harvey
U.S. Geological Survejr
Water Resources Division
3215 Marine Street
Boulder, CO 80303-1066
Phone: 303-541-3034 Fax: 303-447-2505
rwharvey@usgs.gov
Douglas Heath
NH GW Coordinator/USEPA Region I
U.S. Environmental Protection Agency, Region I
JFK Federal Building, CNH
Boston, MA 02203
Phone: 617-565-3594 Fax: 617-565-4940
Final
A-2
August 1996
-------
EPA Workship on Predicting Microbial Contamination of Groundzvater Systems
Dennis Helsel
Coordinator, Drinking Water Initiative
U.S. Geological Survey
413 National Center
Reston, VA 21092
Phone: 703-648-5713 Fax: 703-648-5297
dhelsel@usgs.gov
Torn Higham
Water Quality/Backflow Inspector
City of Arcadia
P.O. Box 60021
Arcadia, CA 91066-6021
Phone: 818-821r4321 Fax: 818-359-7028
THigham365@aol.com
Daniel Home
Engineering Field Director
Virginia Department of Health
Southeast Virginia Engineering Field Office,
Office of Water Programs
5700 Thurston Avenue, Suite 203
Virginia Beach, VA 23455-3302
Phone: 804-363-3876 Fax: 804-363-3955
Robert Hulquist
Chief, Drinking Water Technical Operations
Section
California Department of Health Services
601 N. 7th Street
P.O. Box 942732
Sacremento, CA 94234-7320
Phone: 916-445-5944 Fax: 916-323-1382
bhultqui@hwl.cahwnet.gov
James Hunt
Professor, University of California
631 Davis Hall, Department of Civil and
Environmental Engineering
University of California
Berkeley, CA 94720-1710-
Phone: 510-642-0948 Fax: 510-642-7483
hunt@ce.berkeley.edu
Subhash Jha
Program Manager
Nebraska Department of Health
Environmental Health Protection Section
301 Centennial Mall South, P.O. Box 95007
Lincoln, NE 68509-5007
Phone: 402-471-2541 Fax: 402-471-6436
Charles Job
Office of Ground Water/Drinking Water
Environmental Protection Agency, Headquarters
GWPD (4602)
401 M Street, SW
Washington, DC 20460
Phone: 202-260-7084
Tyrone Kelley
Water and Wastewater Program Manager
USDA Forest Service
20114th Street, SW . •
Washington, DC 20250
Phone: 202-205-0881 Fax: 202-205-0861
/s=T.KeUey/OUl-W01A@mhs-fswa.attmail.com
RobKittay
Senior Scientist
South Dakota Drinking Water Program
523 E. Capkol-DENR
Pierre, SD 57501
Phone: 605-773-4208 Fax: 605-773-5286
robk@denr.state.sd.us
Stephen Kraemer
Research Hydrologist
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
919 Kerr Research Drive, P.O. Box 1198
Ada, OK 74820
Phone: 405-436-8549 Fax: 405-436-8703
stephen@epamail.epa.gov
Denise Kruger
Quality Assurance Supervisor
Southern California Water Company
630. E. Foothill Boulevard
SanDimas, CA 91773
Phone: 909-394-3600, ext. 653 Fax: 909-394-0827
dkruger@ccmaiLuci.gsm.edu
Lynn Kurth
SAIC
2004-A Cody Court
Austin, TX 78704
Phone: 512-444-9312
Fax: 512-326-4433
Lawrence Y.C. Leong
Vice President
Kennedy/Jehks Consultants
2151 Michelson Drive, Suite 100
Irvine, CA 92715
Phone: 714-261-1577 Fax: 714-261-2134
lycl@aol.com
Final
A-3
August 1996
-------
EPA Workship on Predicting Miarobial Contamination of Ground-water Systems
Mary Ellen Ley
Water Supply Specialist
Maryland Department of Environment
Public Drinking Water Program
2500 Broening Highway
Baltimore, MD 21224
Phone: 410-631-3476 Fax: 410-631-4894
Sharon Lien
Environmental Specialist
City of Anaheim Public Utilities Department
201 S. Anaheim Boulevard, #1102
Anaheim, CA 92805
Phone: 714-254-4279 Fax: 714-254-4135
envservs@deifanet.com
Ronald Linsky
National Water Research Institute
10500 Ellis Avenue
Fountain Valley, CA 92718
Phone: 714-378-3278 Fax: 714-378-3375
Dale Long
Environmental Protection Agency Region 3
841 Chestnut
Philadelphia, PA 19107
Phone: 215-566-5779
Long.Dale@epamail.epa.gov
Gary Lynch
Director of Water Quality
Park Water Company
PO Box 7002
9750 Washburn Road
Downey, CA 90241-7002
Phone: 310-923-0711, ext 201 Fax: 310-861-5902
pwcwq@lax-ca38-16.ixjietcom.com
Bruce Macler
Ground Water Disinfection Rule Manager
U.S. Environmental Protection Agency Region 9
75 Hawthorne Street
San Francisco, CA 94105
Phone: 415-744-1884 Fax: 415-744-1235
David McCauley
Environmental Engineer for U.S. Forest Service
USDA Forest Service
2245 Morello Ave.
Pleasant Hill, CA 94523
Phone: 510-825-9800 Fax: 510-687-0125
/s=d .mccauley / oul=r05a@mhs-fswa.attmail.com
Dennis McChesney
Ground Water Management Section
U.S. Environmental Protection Agency Region 2
290 Broadway, Suite 2400
New York, NY 10007-1866
Phone: 212-637-3851
McChesney.Dennis@epamail.epa.gov
Gordon McFeters
Professor of Microbiology
Montana State University
Department of Microbiology
Boozeman, MT 59717
Phone: 406-994-5663 Fax: 406-994-4926
umbgm@msu.oscs.montana.edu
James McNabb
Consultant, Groundwater Microbiology
P.O. Box 1762
Ada, OK 74820
Phone: 405-332-3302 Fax: 405-332-6553
Wendy Melgin
Source Water Protection Section
Environmental Protection Agency Region 9,
W-6-3
75 Hawthorne Street
San Francisco, CA 94105
Phone: 415-744-1831
Jon Merkle
Environmental Scientist
U.S. Environmental Protection Agency Region 9
75 Hawthorne Street
San Francisco, CA 94105
Phone: 415-744-1844 Fax: 415-744-1235
Merklejon @ epamail.epa.gov
Larry Mitchell
Microbiological Monitoring Team, Team Leader
Public Drinking Water Program, Texas Natural
Resource Conservation Commission
Water Utilities Division/MC 155, Public
Drinking Water Section
TNRCC, P.O. Box 13087
Austin, TX 78711-3087
Phone: 512-239-6020 Fax: 512-239-6050
Dennis Nelson
Drinking Water Program
Oregon Health Division
800 NE Oregon Street
Portland, OR 97232
Phone: 503-731-4821 ext. 763 Fax: 503-731-4077
dennis.o.nelson@state.or.us
Final
A-4
August 1996
-------
EPA Workship on Predicting Microbial Contamination of Groundzvater Systems
Roy Ney
Iowa Department of Natural Resources
Wallace State Office Building
900 E. Grand Avenue
DesMoines/IA 50319-0034
Phone: 515-281-8945 Fax: 515-281-8895
runner551@aol.com
Betty Olson
K/J Consultant
University of California, Irvine
Department of Environmental Analysis
Irvine, CA 92679
Phone: 714-261-1577 Fax: 714-824-2056
Robin Oshiro
Graduate Student
University of California, Irvine
Department of Environmental Analysis
Irvine, CA 92679
Phone: 714-261-1577 Fax: 714-824-2056
Tom Outlaw
Project Coordinator
The Association of State Drinking Water
Administrators
1120 Connecticut Avenue, NW, Suite 1060
Washington, DC 20036
Phone: 202-293-7655 Fax: 202-293-7656
asdwa@interramp.com
Richard Overmyer
Chief, Noncommunity Program
Drinking Water & Radiological Protection
Division
3423 N. Martin L. King Jr. Boulevard
P.O. Box 30630
Lansing, MI 48909-8130
Phone: 517-335-8310 Fax: 517-335-9434
overmyerr@state.mi.us
Pierre Payment
Director of R&D
Institut Armand-Frappier
531 Boulevard des Prairies
Laval, Quebec H7N 4Z3
Canada
Phone: 514-687-5010, ext.4339 Fax: 514-686-5626
Pierre_Payment@iaf.uquebec.ca
Keith Peacock
Unit Supervisor
Minnesota Department of Health
Public Health Laboratory Division
717 S.E. Delaware Street, P.O. Box 9441
Minneapolis, MN 55440
Phone: 612^623-5305 Fax: 612-623-5514
keith.peacock@health.state.mn.us
Rodney Pingree
Water Systems Section Chief
Vermont Agency of Natural Resources
Water Supply Division, Old Pantry Building
103 S. Main Street
Waterbury, VT 05671-0403
Phone: 802-241-3418 Fax: 802-241-3284
rodney@getwet.anr.state.vt.us
CarlaPost
SAIC
1710 Goodridge Drive, M/S 1-1-3
McLean, VA 22102
Phone: 703-749-5185 Fax: 703-356-2714
Carla_Post@cpqm.saic.com
Ken Reich
Water 'Quality Manager
Central Basin MWD
17140 S. Avalon Boulevard
Carson, CA 90746
Phone: 310-660-6210 Fax: 310-217-2414
Martha Sabol
Ground Water Protection Unit
U.S. Environmental Protection Agency Region 10
1200 Sixth Avenue
MS-133
Seattle, WA 98101
Phone: 206-553-1593
Sabol.Martha@epamail.epa.gov
Tom Scifranek
Nebraska Department of Health
P.O. Box 95007
Lincoln, NE 68509
Phone: 402-471-0550 Fax: 402-471-0383
doh8107@vmhost.cdp.state.ne.us
Rick Saikaji
California Dept. of Health Services
2151 Berkeley Way, Room 449
Berkeley, CA 94704
Phone: 510-849-5050 Fax: 510-540-2181
Final
A-5
August 1996
-------
EPA Workship on Predicting Microbial Contamination of Groundwater Systems
Stephen Schaub
U.S. Environmental Protection Agency
401 M Street, SW
Mail Code 4304
Washington, DC 20460
Phone: 202-260-7591 Fax: 202-260-1036
Roger Selberg
Division Manager, Division of Public Water
Supplies
Illinois Environmental Protection Agency
2200 Churchill Road
P.O. Box 19276
Springfield, IL 62794-9276
Phone: 217-785-8653 Fax: 217-782-0075
Gerald Smith
Minnesota Department of Health
121 E. 7th Place
P.O. Box 64975
SL Paul, MN 55164-0975
Phone: 612-215-0765 Fax: 612-215-0979
Mark Sobsey
University of North Carolina, Chapel Hill
CB#7400
Rosenau Hall, Room 106
Chapel Hill, NC 27599
Phone: 919-966-7303 Fax: 919-966-4711
Mark_Sbosey@unc.edu
Ginny Stern
Hydrogeologist
Washington State Department of Health
Drinking Water Program
P.O. Box 47822
Olympia,WA 98504-7822
Phone: 360-586-7805 Fax: 360-586-5529
gas0303@hub.doh.wa.gov
Stephen Tighe
Arizona Department of Environmental Quality
Drinking Water Program, Program Development
and Outreach Unit
3033 N. Central Avenue
Phoenix, AZ 85012
Phone: 602-207-4638 Fax: 602-207-4634
Daniel Wilson
Manager, Well Program
Minnesota Department of health
121 E. Seventh Place
P.O. Box 64975
St. Paul Minesota 55164-0975
Phone: 612-215-0812 Fax: 612-215-0978
daniel.wilson@health.state.mn.us
Nancy Winters
SAIC
606 Columbia Street, NW, Suite 300
Olympia,WA 98506
Phone: 360-754-7077 Fax: 360-943-1331
Mike Wireman
Ecosystems Protection Branch
U.S. Environmental Protection Agency Region 8
SEPR-2405
Denver, CO 80202-2405
Phone: 303-312-6719
WkemanJMike@epamail.epa.gov
William Woessner
University of Montana
Department of Geology
Missoula,MT 59812
Phone: 406-243-5698 Fax: 406-243-4028
gl_www@selway.umt.edu
William Wong
Program Manager-Safe Drinking Water Program
Hawaii Department of Health
919 Ala Moana Boulevard, Room 308
Honolulu, HI 96814
Phone: 808-586-4258 Fax: 808-586-4370
Nira Yamachika
Director of Water Quality
Orange County Water District
10500 Ellis Avenue
P.O. Box 8300
Fountain Valley, CA 92728-8300
Phone: 714-378-3281 Fax: 714-378-3373
William Yanko
Laboratory Supervisor
County Sanitation Districts of Los Angeles
County
1965 Workman Mill Road
Whittier, CA 90601
Phone: 310-699-7411x3022 Fax: 310-695-7267
WAYanko@aol.com
Marylynn Yates
Associate Professor of Environmental Biology
University of California, Riverside
Department of Soil and Environmental Science
Riverside, CA 92521
Phone: 909-787-5488 Fax: 909-787-2954 or 3993
marylynn.yates@ucr.edu
Final
A-6
August 1996
-------
APPENDIX B
EPA WORKSHOP ON PREDICTING MICROBIAL
CONTAMINATION OF GROUNDWATER SYSTEMS
Briefing Packet
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