On October 27-28, 1999, EPA held the sixth meeting of the Stage 2 Disinfection Byproducts and
Long-Term 2 Enhanced Surface Water Treatment Rules (MDBP) Federal Advisory Committee
(FACA). This meeting included presentations by the Technical Work Group (TWG) on twelve
months of ICR data, overviews of distribution system issues and non-ICR data collection, and
substantial time spent in caucusing and conversation among FACA Committee members. [See
Attachment I.a for a list of meeting participants.]
After introductions, mediator Abby Arnold, RESOLVE, reviewed the objectives of this meeting:
The Committee approved the agenda as proposed [See Attachment I.b.] The afternoon of
October 27 consisted of caucus time in which FACA members met among themselves. This
meeting report summarizes the presentations and plenary discussions, and proposed next steps
from this meeting.
Michael McGuire, MEC, and Michael Messner, EPA, presented the TWG's report to the FACA
committee. The TWG has completed initial analysis of 12 months of ICR data. McGuire and
Messner reminded FACA members that their presentations were developed by the TWG and that
in presenting this information they would be acting as reporters from the TWG to the FACA.
Information presented represents the consensus opinion of TWG members.
Messner began by presenting the analysis of microbial data from the ICR and Supplemental
Surveys, identification of indicator relationships and trends in the data, and next steps for the
Microbial Contaminants TWG Subgroup [Attachment II.a.] The Subgroup is focusing on the
following microbial contaminants: coliforms, viruses, and protozoa (Cryptosporidium and
Giardia). In response to a question, Messner explained that surveys for protozoa use a visual
microscopy technique to identify protozoa in samples. The low recovery rate of this technique is
attributed to lost oocysts or unseen oocysts. There is disagreement among subgroup members
regarding the accuracy of the method and how to best correct for recovery. Viruses are identified
using a cell culture technique that uses larger sample sizes than protozoa. Messner also
explained that the subgroup has focused on raw water data only.
Twelve months of ICR and six months of Supplemental Survey data are now available and data
analysis has begun. In response to a question, Messner explained that the Supplemental Survey
used only five or six labs, a tighter filter and other enhanced factors (as compared to the ICR
method) for detection of microbes. The Survey included 47 ICR, 40 medium sized and 40 small
sized systems. Protozoa data were not collected for small systems. Messner presented graphics
on the subgroup's analysis of these data and noted the following trends:
Messner presented the TWG list of 18 priority questions identified for the subgroup to address
(see Attachment II.a).
In response to a question, Messner noted that the large number of zeros, or non-detects, may be
the result of small volumes analyzed. The Subgroup will approach the meaning of zeros on two
simultaneous analysis paths. These approaches will be used to answer questions and then be
compared to see how answers differ and why:
A FACA member observed that it is curious that 40 to 50% of virus samples have a one detect.
The Subgroup has not yet looked in to explanations for this finding.
McGuire continued the TWG presentation by reviewing source water quality, enhanced
coagulation, specific disinfection byproducts (DBPs) and TWG next steps [Attachment II.b.]
McGuire began by noting that the primary Auxilliary data base (Aux 1) and Aux 3,4,5 & 6 are all
on-line. The query tools, Aux 2 and Aux 8, are still under development. Data presented is for 12
months (4 quarters). ICR data has a high number of samples; some are collected monthly and
some quarterly. ICR sampling is done on a plant basis and may include blends of more than one
source type. Compliance is calculated based on a system, rather than a plant, basis.
McGuire made the following clarification points regarding presentation slides and graphics on
ICR data analysis (See Attachment II.b.):
Delta TTHM for 12-months of Distribution Sampling: Delta is the calculated change in
TTHM levels between the entry point into distribution system and the maximum distance
to a customer (tap). Free Chlorine (Cl2) in distribution systems tend to increase the
creation of TTHMs. However, delta depends on primary treatment. If Cl2 is added as
primary treatment then TTHM creation occurs within the plant. Optimizing treatment
requires balancing different characteristics of control options. Chloramines are often used
as a secondary disinfectant because they produce fewer DBPs. Delta measures change, not
an absolute number, so a plant with a high delta may still have a low total concentration of
DBPs.
Next Steps for the TWG include:
- Prepare Stage 1 baseline for FACA by December/January meeting
- Present results from the other Auxiliary databases - sludge production and washwater
- Present compliance forecast analysis concepts at December FACA meeting - develop
vocabulary
- Present preliminary results of GAC and Membrane studies - December or January
III Status Update on Health Risk Assessment (DBPs/Micro)
Stig Regli, EPA, presented an overview of the Health Risk Assessment for DBPs and microbial
pathogens for development of the Stage 1 Rules and final Stage 1 Rules. Regli also covered
EPA's current understanding of risk and anticipated research in the near term [Attachment III.a.]
Regli began with overviews of maximum contaminant level goals (MCLGs) and maximum
residual disinfection level goals (MRDLGs) for DBPs, the 1994 regulatory impact analysis (RIA)
and microbial risks (Giarida, Cryptosporidium, and viruses). Regli also reviewed the M/DBP
Research Plan for DBPs and microbial pathogens and specific research completed between 1994
and 1998. Cryptosporidium has been a focus for microbial research because it may be an
indicator of overall microbial protection.
EPA will provide health risk characterizations for DBPs and pathogens to the FACA over the
next several months. The Agency will conduct more formal risk assessments to support the
proposed and final rules. EPA believes that existing health effects data suggests enough of a risk
from DBPs and microbial pathogens to require that the Agency evaluate how to reduce risk and
the cost implications of different risk reduction options. EPA does not expect the risk
assessment for DBPs to provide any more confidence regarding what existing studies indicate.
Two experts who have previously presented to the FACA, Rochelle Tyl, RTI, and John Reif,
Colorado State University, have been asked by EPA to provide the Agency with toxicological
and epidemiological evaluations of the reproductive and developmental health effects database.
[See Attachments III.b and III.c for Scopes of Work for Tyl and Reif.] These experts where
chosen, in part, because of their perceived neutrality.
The evaluations by Tyl and Reif are not the risk assessment, but preliminary technical appraisals
of the cumulative database. Though there is not much new data, this effort will be more detailed
than that required for the FACA presentations. EPA will share the findings of these experts with
FACA members as soon as they are available. Tyl and Reif may also be available to provide
FACA members additional information or instruction on their reviews of the database.
In addition to the presentation materials Regli made the following points:
- Dose response data based on the Iowa strain indicates that Cryptosporidium may be 70%
more infective than first thought. The more recent analysis of the Iowa strain data included
people infected with and without symptoms. Shedding of oocysts in stool is the most
common method of determining infection. However, some people may be infected without
shedding oocysts. A FACA member suggested that the problem may be with the detection
method and that more sophisticated detection methods would find cysts in these cases.
- Data shows that a significant percent of US population (25-35%) have antibodies
indicating that they have been exposed to Cryptosporidium oocysts.
- Rates of secondary spread vary greatly between age categories with low rates for adults
and high rates for children.
In response to a question, Regli noted that EPA now has better characterization of source water,
treatment (filtration efficiency), and dose response information (data for new strains).
Understanding of uncertainty levels has improved based on research. In response to a question
on the level of confidence in existing data, Regli explained that EPA is reevaluating existing data
as well as new research to evaluate the extent to which the characterization of risk from
Cryptosporidium may change from previous estimates (i.e., those conducted for IESWTR). EPA
intends to present the first parts of this characterization during the next two FACA meetings.
IV Regulatory Issues Involving Distribution System Management and
Finished Water Storage
Dan Schmelling, EPA, presented existing distribution systems regulations and an overview of
distribution system issues [Attachment IV.] The existing regulations covering water distribution
systems include:
- Total Coliform Rule (1989): Limits microbial contamination of potable water distribution
systems.
- Lead and Copper Rule (1991): Limits corrosion of lead and copper from plumbing and
solder into drinking water. A FACA member noted that MDBP rules, (e.g. adding
coagulant) may change the pH of water and effect compliance with this or other rules.
- Surface Water Treatment Rule (1989): Includes provisions for control of microbial
regrowth.
- Interim Enhanced Surface Water Treatment Rule (1998): Requires sanitary surveys, which
include distribution system information, and requires that all new finished water reservoirs
be covered.
V Distribution Systems and Water Quality
Gregory J. Kirmeyer, Economics and Engineering Services, Inc., presented an overview of
distribution and storage system maintenance issues [Attachment V.]
Kirmeyer was asked to answer five questions for the FACA:
Question 1: What are typical characteristics of potable water distribution systems and what
engineering issues underlay their design?
Kirmeyer began by reviewing key components and characteristics of a distribution systems [see
attachment.] Distribution systems, historically, have been designed primarily to meet flow,
pressure, and storage requirements for emergency and future development needs, not water
quality concerns. Maintaining water quality is now recognized as an important element. Each
system is unique and has individual needs and problems. A major component of distribution
systems is continual maintenance. In summary:
- Each "system" is unique in its design, operations and maintenance requirements.
- There are many places to check for design guidance - state standards, state design manuals,
AWWA and AWWARF guidance.
Question 2: What are the steps which utilities take to maintain water quality in the distribution
system?
Kirmeyer based answers to this question on three AWWARF reports [see Attachment]. Water
quality is affected by physical, chemical and microbiological parameters. To maintain water
quality Kirmeyer recommends that utilities set internal operational performance
guidelines/targets. These guidelines include: maintain positive pressure, minimize detention
time, maintain disinfection residual, keep distribution system clean, provide treatment, set goals
and monitor beyond regulations. Utilities should clearly design operation and maintenance of
distribution system with water quality in mind. These designs need to be fully integrated with
utilities' water quality programs. Kirmeyer also noted new data on micro-surges caused by
hydrant openings and closings that may result in low or possibly negative pressures. Water is
incompressible, therefore negative pressures can be formed. Air vacuum relief valves are one
place where vacuums in the system may siphon water.
Question 3: What roles do capital improvement and line replacement play in maintaining
distribution system water quality?
Roles of capital improvement and line replacement are unique for each utility and are system
specific. Priority capital improvements include:
1. Improving problem areas with low pressure - top priority.
2. Replacing/rehabilitating tuberculated (choked off or corroded) pipe. In response to a
question Kirmeyer explained that most utilities replace pipe based on repair history.
3. Addressing piping that leaks/breaks at excessive rates: emergency repairs are a source of
intrusion and leaks are potential pathways for backflow.
4. Addressing storage facilities: reduce potential for intrusion.
5. Addressing monitoring and control systems: real time data especially for remote
operations.
Question 4: What are the causes of microbial regrowth in distribution systems and how can it
be controlled?
Causes of microbial growth within the distribution system include:
- Passage through treatment plant and colonize in system
- Reactivation of injured organisms
- Contamination from new construction
- Contamination from main repair procedures
- Contamination during a depressurization event
- Backflow (cross-connection)
- Back siphonage (cross-connection)
- Uncovered storage facilities
- Penetration into storage facilities
Control measures include:
- Remove organisms from source
- Provide effective primary disinfection (i.e., no injured organisms to regrow)
- Maintain positive pressure
- Maintain secondary disinfectant residual
- Consider a switch to chloramines
- Optimize chloramine treatment
- Reduce detention time in storage and distribution systems
- Select water with lower temperatures
- Reduce pathogen intrusion potential
- New main procedures
- Sanitary repair procedures
- Flushing to keep system clean
- Provide corrosion control
Question 5: What are the risks, benefits, and other implications of systems switching to
chloramines as a residual disinfectant?
Chloramines are produced by adding ammonia to chlorine.
Drawbacks of Chloramination:
- The presence of ammonia may lead to the potential for nitrification. Many utilities
periodically switch to free chlorine to rid systems of chloramine resistant bacteria - this is
possible under current DBP rules because averaging.
- Residual Depletion
- Proliferation of Bacteria
- Adverse effects on fish rearing and kidney dialysis
Benefits of Chloramination:
- Low Potential--DBP/THMs/HAAs
- Minimal T & O
- Persistence--Remote areas
- Effectiveness--Biofilms
Summary:
- Chloramination has many benefits but requires very careful treatment, operation, and
maintenance of distribution system, plus public awareness of change.
FACA members made the following additional comments regarding distribution systems:
- Utilities recognize that distribution systems are equally or more complex than treatment
systems. Focus has been on treatment though distribution system conditions may have a
very large effect on water quality.
- Distribution systems have not had the same prevention, treatment or reliability standards as
treatment systems. This may be because of the enormous cost of maintenance and
replacement of distribution systems - approximately $1/2 million per mile.
- Centers for Disease Control reports indicated that 1/4 of waterborne disease is associated
with distribution system failure.
- Pathogens in distribution systems may be protected from disinfectant residuals because
they are resistant or they are protected by biofilms.
- EPA has added cross-connection control to a list of priority issues based on feedback
received during Enhance Surface Water Treatment Rule public comment.
- Emphasis should be on the importance of good management practices. The FACA should
look at opportunities to balance distribution system characteristics and procedures with
treatment requirements.
FACA members made the following additional comments regarding the use of Chloramines as
a secondary disinfectant:
- Fewer small systems are using chloramines.
- Research into the health effects (cancer and epidemiology) of Chloramines is included in
the Notice of Data Availability for the Stage 1 rule.
- Ammonia gas presents an additional risk in the use of Chloramines (Chloramines are
chlorine + ammonia). However, solid and liquid ammonia can be substituted for gas.
- Chloramines are less effective against viruses.
- Chloramines are very effective against bacterial regrowth in the distribution system.
- Free chlorine may be a better indicator of intrusion than chloramines.
VI Distribution Systems Presentation
Paul H. Schwartz, Foundation for Cross-Connection Control and Hydraulic Research at the
University of Southern California (USC FCCCHR), presented an overview of the hydraulics of
backflow, control measures, and incidents [Attachment VI.] The USC FCCCHR was established
in 1944 to investigate backflow occurrences and develop prevention measures. Schwartz
provided graphics illustrating backflow, cross-connections and prevention technologies:
- Backflow is the undesirable reversal of flow of water or other substances into the potable
water distribution supply.
- Cross-connection is an actual or potential connection between a potable water supply and
any non-potable substance or source.
There is little monitoring for contamination of water systems through backflow and cross-connection and events are rarely detected or documented. Schwartz reviewed the effects of four
individual incidents and their effects and occurrence data and drew the following summary
points:
- Backflow is a real problem - solids, liquids and gasses can all be drawn into a system.
- Transient in nature (occurs in large and small volumes) - incidents can be system-wide or
internal, effecting individual users.
- All water systems are susceptible
- Consequences may be severe
- A missing barrier in a multi-barrier approach to water quality may be distribution system
protection and effective cross-connection control and backflow prevention.
- In addition, Schwartz noted that some types of backflow prevention assemblies provide a
visual indication of operation . Technologies for controlling backflow are available and do
work. The increasing use of separate potable and recycled water systems (dual plumbed
systems) may present new problems in ensuring that systems remain separate. In response
to a question, Schwartz noted that codes and enforcement are not uniform and depend on
State, region, or city variances.
- Backflow events are often not detected, are hard or impossible to trace, and are influenced
outside of the distribution system by industrial sites or residents.
VII Cross Connection Control Programs
Ken Ashlock, City of Tempe, AZ, presented an overview of backflow prevention programs
[Attachment VII.] Ashlock began by reviewing the need for legal authority and personnel
training necessary for administering a cross connection control program. Cross connection
control programs typically include:
- Hazard surveys: to identify and inspect facilities that may pose a significant hazard from
cross connections (e.g. animal care facilities, car washes, hospitals and mortuaries,
semiconductor facilities.)
- Public education: to raise awareness of the problem of cross connections through
brochures, bill stuffers, informational meetings, and comic books.
- Installation and testing of assemblies: control assemblies should have been through a
performance evaluation, be installed correctly, and be maintained and tested regularly by
trained personnel.
- Record keeping: on types, operation and maintenance of equipment and type of hazard on
premises; and compliance, correspondence, and actions related to the site.
- Incident reporting: written procedures for recording backflow incidents.
Ashlock reviewed the elements of cross connection control programs around the country. Their
costs and program requirements differ between states. Some systems have cost recovery
programs, including specific user fees for cross connection control.
Key elements of a State program include: establish legal authority, training, public education,
record keeping, and enforcement. 96 percent of states have a minimum requirement for cross
connection control in their State code. Only 38 percent of States require reporting of backflow
incidents.
VIII TWG Non-ICR Subgroup: Overview of Approach to Characterizing Non-ICR Systems
At the request of FACA members, Stig Regli provided an overview of the TWG Non-ICR
subgroup's approach to characterizing Non-ICR systems [Attachment VIII.] Non-ICR systems
are divided into subgroups for analysis by source and size:
- Medium groundwater (GW) systems (serving 10,000-100,000 people)
- Small GW systems (serving <10,000)
- Medium surface water (SW) systems (serving 10,000-100,000)
- Small SW systems (serving <10,000)
Regli presented breakdowns of the percentage of US population served by ICR, and Non-ICR
systems (including the subgroups above), and the total number of systems in each category. Key
data sources of data for drinking water systems include:
- SDWIS
- ICR
- Supplemental Surveys
- Disinfection Surveys (evaluates operation of systems)
- Water Stats (treatment technology)
- Bromide Survey (GW systems, small number of sites)
- NRWA DBP Survey (Evaluates small system DBPs, data will be used to evaluate Water
Treatment Plan model and cold water verses warm weather data. Information will be used
in impact analysis of Stage 2 Rule Proposal.)
- Ground Water Supply Survey (EPA study of TOC in finished water, 500 systems)
- Community Water Supply Survey
- Needs Survey
- State Data
Regli reviewed the TWG subgroup's data analysis approach for each of the four non-ICR system
subgroups [See Attachment VII]:
- Medium SW systems: Analysis will be similar to large systems, based primarily on ICR.
- Small SW systems: Cannot be directly extrapolated from large system information,
partially due to differences in DBP precursors. EPA has developed a list of 12 model
plants that characterize small system universe and will use these to estimate Stage 1 and
pre-Stage 1 baselines.
- Medium and Small GW systems: Based on extrapolation from ICR groundwater system
data. Effect of THM data from Florida is large factor - 30% Florida small systems exceed
Stage 1 THM standard. Treatment for GW systems is expected to be similar for all system
sizes because treatment is specific for each well - larger systems have more wells.
The TWG Non-ICR subgroup schedule for developing and providing information to the FACA:
- December 1999 - Present results of pre-Stage 1 baseline conditions to FACA.
- January 2000 - Present results of Stage 1 impacts analysis to FACA (small SW systems
analysis in February)
- TBD - Present results of Stage 2 impact analysis to FACA
In response to a question, Regli explained that the subgroup expects that the Supplement Survey
will identify small system source water characteristics to adjust model. New data is available on
small systems that should allow for a "fairly good" impact analysis.
IX Report-outs from FACA Caucus Sessions
In the afternoon of October 27, FACA members split into three cross-caucus breakout sessions.
Participants in the breakouts were chosen so as many perspectives as possible were represented
in each breakout group. The purpose of breakout groups was to allow FACA members and
alternates to discuss openly any aspect of Stage 2 Rule development and the work of the FACA.
On October 28 each group informally presented an overview of their discussion. These
presentations are summarized below:
The group in the large conference room listed the following as points that the FACA could
consider in its discussion:
- Operator competency
- Best Management Practices for distribution systems
- Importance of affordability/costs - especially once alternatives are identified
- Recognition of public health concerns regarding byproducts and microbial pathogens.
- Need for cost characterization of treatment technologies, options for all system sizes.
- Maybe the TWG could provide estimates of costs per system size for a given technology.
This would give information on cost impact for each system size and technology.
Marginal cost is hard to characterize on a National basis.
- Explore multiple barriers including surface water protection for microbes.
The group in the middle conference room listed the following points:
Perspectives to consider - components of an effective regulatory system:
- Establish a floor to ensure protection based on sound science and health information -
bring outliers to the minimum standard.
- Optimize the operation or treatment and distribution systems (tweak zone) to meet or
exceed the floor.
- Provide incentives for technology to advance and be incorporated by utilities for
expansion, replacement, or updating of the system.
- Prevention verses treatment: understanding of unintended consequences and reducing
regulatory burden.
Issues to consider:
- Should there be different regulatory requirements for flowing streams, reservoirs or lakes?
- Is there enough health effects information to justify a change in treatment technology?
- How can we best address risk issues in the distribution system as part of a holistic view of
the water treatment and delivery system?
- Should we consider a maximum or cap for DBPs?
- What additional reduction of DBP levels can be achieved from Stage 1?
- What would a risk based requirement for the inactivation of Cryptosporidium look like?
- How do we improve reliability/assurance of performance of systems?
- What is the role of source water protection in a multiple barrier approach?
- Can microbial issues be addressed by dealing with operational anomalies?
- Should standards be based on surrogates or individual contaminants?
- Are there win/win approaches to reduce microbial and DBP risk simultaneously while
looking at water sources, technology, and distribution systems.
- What is the cost, in terms of health effects, of not acting now and how does this balance
costs of adjusting treatment technology?
The group in the conference room "behind the desk" listed the following discussion points and
comments:
- Desire to flesh out treatment options.
- A desire to keep in mind public health and operational goals.
- Develop several specific outlines or lists of key issues to be discussed or focused on.
- Need to seek integrated strategies that incorporate prevention, treatment and reliability.
- Analysis of the acute, subacute, and chronic health effects of disinfection, including
reproductive effects and malignancies.
- Cognizance of new knowledge about Cryptosporidium health effects and disinfection
possibilities.
- Desire to acknowledge clean water sources in the regulations.
- Cost and acceptance issues.
- Recognize the financial, managerial, technical and other difficulties faced by small,
especially rural, utilities.
- This regulatory process may only be a small step in a prolonged regulatory process that
stretches over years.
X Next Steps
FACA members discussed the following next steps:
- Some FACA members requested assistance understanding health effects data and
reviewing the critique of evaluations undertaken for EPA by Rochelle Tyl and John Reif
on reproductive and developmental effects. [See Attachments III.b and III.c for Scopes of
Work for Tyl and Reif.] Tyl and Reif may be available to provide FACA members with
additional information or instruction on their reviews of the existing database.
- Fred Hauchman has presented additional health effects research that is planned or currently
underway at previous FACA meetings. There will an opportunity for a Notice of Data
Availability (NODA) in August 2001. The FACA may agree to meet in late summer 2001 to
discuss new information. EPA, however, is under a time constraint for proposal development.
- December meeting will be one year anniversary of Stage 2 FACA.
XI Public Comment
Two speakers addressed the FACA during the public comment period on October 28:
Mike Doherty, Water Program Manager, U.S. Marine Corps, asked that the FACA look carefully
at issues surrounding DBP in the distribution system. Many distribution systems are currently in
a state of "crisis management." One recent positive step was EPA's guidelines for State water
utility operator certification, including distribution system operator certification. The FACA
should consider:
- Manganese contamination has been a problem at groundwater systems in California,
though it is not included in the DBP rules.
- States have a broad range of regulations regarding operation and management. To date this
has not been included in the scope of the MDBP FACA. FACA should look to equilibrate
at operation and maintenance requirements through States - especially for distribution
systems.
Caroline Cinquanto relayed the story of her child, who was born with a congenital heart defect.
Though there is no way to know the cause, Ms. Cinquanto asked the FACA to consider that if
drinking water was a contributing factor, the FACA should act to reduce these risks.
Adjourn
XII ATTACHMENTS
I.a Participants List
I.b Meeting Agenda
II.a Microbial Occurrence (Report from TWG Subgroup) - Michael Messner,
USEPA - OGWDW
II.b TWG Presentation to FACA Committee -- ICR Data Summary - Michael
J. McGuire, MEC
III.a Status Update on Health Risk Assessment (DBPs/Micro) - Stig Regli, EPA
III.b Scope of Work - Rochelle Tyl, RTI
III.c Scope of Work - John Reif, Colorado State University
IV. Regulatory Issues Involving Distribution System Management and
Finished Water Storage - Dan Schmelling, EPA
V. Distribution Systems and Water Quality - Gregory J. Kirmeyer, Economic
and Engineering Services, Inc.*
VI. Distribution Systems - Paul H. Schwatz, Foundation for Cross-Connection
Control and Hydraulic Research at the University of Southern California*
VII. Cross Connection Control Programs - Ken Ashlock, City of Tempe, AZ,*
VIII. TWG Non-ICR Subgroup: Overview of Approach to Characterizing Non-ICR Systems - Stig Regli, EPA
*note: due to the size of these presentations they have been printed with 6 slides per page. If you would like larger copies of the slides, or electronic versions of these presentations please contact Eddie Scher at [escher@resolv.org].
