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M/DBP Stage 2
Federal Advisory Committee (FACA2)
TWG Presentation and Discussion of Various Scenarios,
Viability of UV, and Narrowing of
Stage 2 Scenarios for Further Analysis
Meeting Summary - June 2000
Meeting #11
June 1-2, 2000
Washington, DC
Final
Table of Contents
I. Introduction
II. TWG Presentation to FACA Committee--Impacts of Stage 2 Regulatory Scenarios
III. Application of the Microbial Framework to LT2ESWTR FACA Options
IV. UV: Viability of UV for Treating Drinking Water
UV Disinfection: Technology Performance and Availability: An EPA Perspective
Application of UV Technology for Drinking Water Treatment - A Utility Perspective
Municipal Scale UV Disinfection of Drinking Water - UV Manufacturer's Perspective
FACA Discussion of UV
V. Public Comment
Detection, Treatment, and Management of Cryptosporidium At Philadelphia Water Department
Engineering Feasibility of UV Disinfection for NYC, Catskill and Delaware Systems
Countervailing Risk Considerations Important to Evaluation of Bromate Regulatory Options
Publication of the Oral (Drinking Water) Development Toxicity Study of Bromodichoromethane in Rabbits.
VI. Discussion of Regulatory Options
FACA discussion of microbial issues
FACA discussion of disinfection byproduct issues
VII. Next Steps
ATTACHMENTS
I.a Meeting Participants - M/DBP FACA, June 1-2, 2000
I.b Meeting Agenda - MDBP FACA, June 1-2, 2000
I.c FACA Meeting Materials Notebook: Table Of Contents, June 1-2, 2000
II. TWG Presentation --Impacts of Stage 2 Regulatory Scenarios, Michael McGuire, MEC
III. Application of the Microbial Framework to LT2ESWTR FACA Options, Stig Regli, EPA
IV.a UV Disinfection: Technology Performance and Availability: An EPA Perspective, Dan
Schmelling, EPA
IV.b Application of UV Technology for Drinking Water Treatment - A Utility Perspective, Roy Wolf,
Metropolitan Water District of Southern California
IV.c Municipal Scale UV Disinfection of Drinking Water - UV Manufacturer's Perspective, Jon
McClean, Hanovia Ltd.
V.a Detection, Treatment, and Management of Cryptosporidium At Philadelphia Water Department,
Howard Neukrug, Philadelphia Water, and Caroline Johnson, PA Dept. of Public Health
V.b Countervailing Risk Considerations Important to Evaluation of Bromate Regulatory Options,
Phillippe Daniel, Camp Dresser and McKee
V.c Summary and Conclusions: Oral (Drinking Water) Development Toxicity Study of
Bromodichoromethane in Rabbits, Keith Christman, Chlorine Chemistry Council
Introduction
On June 1-2, 2000, EPA held the twelfth meeting of the Stage 2 Disinfection Byproducts
and Long-Term 2 Enhanced Surface Water Treatment Rules (MDBP) Federal Advisory
Committee (FACA). Facilitator Abby Arnold, RESOLVE, began the meeting by
reviewing the proposed agenda and objectives of the meeting. The FACA approved the
agenda with a change to the schedule - the public comment period was moved earlier in
the day. The objectives of this meeting were to:
- present the results of TWG analysis of regulatory scenarios discussed by the FACA
at the April meeting;
- present scenarios for addressing microbial occurrence and DBPs;
- discuss various Stage 2 scenarios and FACA discussion;
- provide direction to TWG on Stage 2 scenarios; and
- review and discuss one-text outline.
See Attachment I.a for a list of meeting participants and Attachment I.b for the draft
meeting agenda.
In anticipation of this meeting the TWG, EPA staff, and consultants developed a package
of background materials for the FACA. This information was compiled into notebooks
which were distributed to FACA members before the meeting. The contents of the
notebook are listed in Attachment 1.c. Copies of these materials are available by
contacting RESOLVE.(1)
TWG Presentation to FACA Committee--Impacts of Stage 2
Regulatory Scenarios
Michael McGuire, MEC, presented the TWG's analysis of impacts of Stage 2 regulatory
scenarios requested by the FACA [Attachment II.a]. McGuire's presentation covered
primarily the disinfection byproduct data. (Stig Regli focused on the microbial data in
the following presentation.) McGuire reminded FACA members that he was presenting
on behalf of the TWG and data presented represents the consensus of the TWG. The
TWG is working with a very large amount of data; what is presented is one cut at
analyzing this data which the TWG hopes will be most useful to the FACA. This
presentation covers a review of the analysis of scenarios requested by the FACA in April,
a review of the DBP species requested by the FACA, action level and distribution system
options reviewed by the TWG, and anticipated next steps for the TWG. Household cost
data developed by the TWG and an EPA consultant were not ready for presentation
during McGuire's presentation. A revised cost data summary with the household cost
data was circulated to the FACA and meeting participants on June 2 [Attachment II].
McGuire presented the revised Stage 2 Scenario Matrix, as requested by the FACA at the
April meeting:
Stage 2 Regulatory Scenario Matrix - April 29
DBPs: |
80/60
RAA
Bromate
= 10 |
80/60
RAA
Bromate
= 5 |
80/60
AAM
Bromate = 10 |
80/60
AAM
Bromate = 5 |
80/60
LRAA
&
80/60
SH Action
Level
(5% SF)
Bromate = 5 |
80/60
LRAA
&
100/75
SH
Bromate =
5 |
80/60
SH
Bromate = 10 |
80/60
SH
Bromate =
5 |
Microbial: |
|
|
|
|
|
|
|
|
0 log Crypto
removal |
xx |
xx |
xx |
xx
|
xx |
xx |
xx |
xx |
0.5 log
Crypto
removal |
xx |
xx |
xx |
xx |
xx |
xx |
xx |
xx |
Sort only 20%
2.0 log
Cryptoremoval |
xx |
xx |
xx |
xx |
xx |
xx |
xx |
xx |
2.0 log
Crypto
removal |
xx |
xx |
xx |
xx |
xx |
xx |
xx |
xxxx |
each x represents one run of the SWAT |
McGuire presented an overview of the SWAT runs performed by the TWG for the new
Matrix:
Each option was run with UV On and UV Off;
Total national costs for some options and Large/Medium SW costs for all options
(not all were analyzed because of time constraints);
Determine impact of 1 Fg/L bromate in sodium hypochlorite on regulatory options;
Determine DBP species production;
Safety factor sensitivity analysis; and
System vs. plant compliance.
In addition to the SWAT runs on the scenarios in the Matrix, the FACA asked the TWG
to develop information on:
- Tools to respond to DBP action level exceedances;
- Qualitative description of RAA, LRAA, AAM and SH;
- Characterization microbial risks (covered by Stig Regli);
- Microbial Framework (toolbox) for source waters (covered by Stig Regli);
- UV characterization (UV was also covered as a separate agenda item - Section IV);
- Viability/applicability of GAC and chloramine for small systems; and
- Distribution System Water Quality Framework.
McGuire then reviewed the organization of TWG cost data into summary tables provided
as part of the FACA's notebook materials (Tab 1).
McGuire presented an overview of the analysis of scenarios requested by the FACA in
April for:
- Capital costs (in $billions) versus decrease in TTHMs - with UV on and off. Log
inactivation for Crypto = zero.
- Capital Costs versus decrease in TTHMs - UV on, log inactivation 0.5.
- Capital Costs versus decrease in TTHMs - UV on, 20 percent log inactivation 2.0.
- Capital Costs versus decrease in TTHMs - UV on, log inactivation 2.0.
- Capital Costs versus decrease in TTHMs - UV on and off, log inactivation 0.5.
- Capital Costs versus decrease in TTHMs - UV on and off, log inactivation 2.0.
- Capital Costs versus decrease in TTHMs - UV on, log inactivation 0.
In addition McGuire made the following points:
- UV does show up in the technology mix when UV is on and inactivation is zero
because the Long-Term 1 Enhanced Surface Water Treatment Rule requires
inactivation of Giardia and viruses, some plants will use UV to meet this
requirement.
- The figures shown in the cost summary are for the average and 90th percentile.
These points were chosen as one way to present data, they are important because
small changes in the average have a dramatic impact on the tails. The 90th
percentile is one measurement of the tail.
- UV on means that UV is an available technology, not that all plants will use it.
- The TWG has assumed a 5 percent safety factor on the 80/60 action level for all
MCLs and a 20 percent safety factor.
McGuire reviewed the distribution of TTHM species for the ICR baseline and regulatory
options requested by the FACA. The TWG did not have sufficient time to develop and
present data for HAA species. McGuire reviewed the TWG method and assumptions
behind the analysis of TTHM species. This analysis was performed only for surface
water ICR plants. McGuire presented the following analyses:
- Average level of TTHM and species concentrations;
- Average percent reduction in TTHM and species from ICR baseline;
- 90th percentile levels of TTHMs and species (focused on tails);
- Reduction in 90th percentile TTHM and species from ICR baseline;
- Reduction in Average TTHM Levels (ug/L) for Stage 1 Baseline and Stage 2
Options
The TWG analyzed the impact of action levels on surface water plants, and developed a
toolbox for dealing with action level exceedances in the distribution system. The TWG
analyzed impact on surface water ICR plants for the 80/60 LRAA scenario, with an 80/60
single highest action level (with a 5 percent safety factor):
- 3 to 6 % of plant months exceeded the action level while remaining in compliance
with the 80/60 LRAA.
- 20 to 35% of SW plants in the ICR exceeded an action level in at least one month
while in compliance with the 80/60 LRAA.
Distribution system toolbox for action level exceedences developed by the TWG:
Modified sampling strategies
Hydraulic monitoring / Modeling
Tank turnover
Modify tank design
Eliminate dead ends |
Improve reservoir mixing
Flushing
Change disinfection practice
pH control
Water Treatment Plant changes |
The TWG analyzed small systems costs to identify the estimated impacts of proposed
rule options on those surface and ground water systems serving fewer than 10,000 people.
The TWG analyses described:
- Impacts as a percentage of systems needing to change to an advanced technology;
and
- Cumulative distribution of household costs to affected households served by small
systems.
McGuire reviewed the TWG small system cost analysis, included in the materials
notebook (Tab 5: Small System Compliance Forecasts and Household Costs). He then
summarized the data:
- Generally, more stringent DBP regulatory options result in higher costs and lower
DBP levels;
- While Average DBP levels may only be reduced by a few ug/L, some regulatory
options significantly reduce the "tails";
- The reduction in TTHM levels results in a high percentage reduction in chloroform
and some BDCM (cromo dichloromethane) reduction;
- More stringent regulatory scenarios results in the production of some CHBr3;
- The greatest reduction in TTHM species is for chloroform as TTHMs are reduced
under more stringent regulatory scenarios; and
Highlights of the discussion that followed:
- The percent reduction in TTHM may not be the best measure of reduction of risk
due to species shifts. EPA responded that TTHMs have been identified as an good
indicator of chlorinated byproducts and brominated THMs. A FACA member
noted that as you bring down TTHMs or HAAs other DBPs and species of TTHMs
or HAAs are reduced.
- In response to a question regarding the prediction of speciation from the ICR
baseline McGuire noted that estimates of ICR baseline are compared with model
predictions and the fit of the data is very good, though not perfect. Overall, the
model is a good estimate of DBP speciation.
- Dose response relationship may be linear at low doses for cancer, however, there is
more likely to be a threshold for reproductive and developmental effects.
- The FACA should avoid taking action that lead to a shift in technologies without
understanding the consequences of those changes. Changes should not lead to
substituting hazards or risks.
- The predicted Stage 1 baseline includes a significant drop in TTHM and HAAs
from the ICR baseline.
- In response to a question, Michelle Frey, MEC, noted that small system water
quality is likely to be as good or better than the medium and large systems once
they come into Stage 1 compliance.
- The toolbox for distribution system remedies may contradict other existing
regulations, especially those regarding water storage.
- A FACA member asked for more data on small system costs and technology shifts
as a result of Stage 1 compliance. EPA responded that some of this data is
available in the cost summary charge (Tab 5 of the materials notebook).
Application of the Microbial Framework to LT2ESWTR FACA
Options
Stig Regli, EPA, presented on behalf of the TWG the microbial framework developed by
the TWG [Attachment III.]. Regli's presentation on the microbial framework included:
- Monitoring methodology for sorting plants into different mean Crypto source water
concentration ranges (bins) (E. coli indicator and/or Crypto monitoring)
- Toolbox of available control measures for shifting plants into lower bin
classifications (e.g., watershed control options, treatment options )
Regli reviewed the monitoring approach developed by the TWG microbial subgroup.
Sstems would be sorted into bins based on the monitoring results,. The TWG is
evaluating the potential for misclassification into bins. Additional issues that the TWG is
addressing and Regli reviewed are:
- National estimates of Crypto concentrations in source waters (how to reconcile
differences between Supplemental Survey and ICR data);
- Reliability of using E. coli for predicting mean Crypto concentrations in source
water (cost of monitoring for Crypto);
- Reliability of estimating mean Crypto concentrations using Method 1623;
- Evaluation of tool box options and how to assign credit per option; and
- Estimates of number of systems in different source water bins.
A FACA member expressed concern that the log credit (1 or 1/2) is difficult to
distinguish because the real change in finished water occurrence cannot be measured.
Regli presented an overview of the LT2ESWTR FACA options for microbial disinfection
(for filtered systems), developed by the TWG:
Option A (monitoring to assess if more treatment needed)
+1/2 log Crypto treatment if Crypto source conc. >0.1/L & <1/L
+1 log Crypto treatment if Crypto source conc. >1/L
Option B1 (monitoring to assess if more treatment needed)
+1/2 log Crypto treatment if Crypto source conc. >0.03/L & <0.1/L
+1.5 log Crypto treatment if Crypto source conc. >0.1/L &<1/L
+2.5 log Crypto treatment if Crypto source conc. >1/L
Option B2 (inactivation required but outs with monitoring)
same as B1 except must monitor and make demonstration to avoid default 1/2
log inactivation treatment requirement
Option C (inactivation or membranes)
1/2 log inactivation or membranes and for high Crypto conc. >1/2 log treatment
(required Crypto monitoring)
Regli presented estimated number of plants in each bin for each of the regulatory options
listed above, approximate impact and cost for each of the options and analysis of
misclassification rates. FACA members made the following points:
- These calculations do not include risk calculations for susceptible populations.
- 24 samples may be enough to determine/assign bins, but gives only a limited ability
to monitor at low occurrence ranges. EPA believes 0.03 oocysts per liter is the
lowest mean concentration that can be determined with reasonable confidence by
24 monthly 10 L samples. The 0.01 level corresponds to the 10-4 risk level for the
mix of Crypto strains.
- Surrogate monitoring is cheaper. However, some FACA members have concerns
that E. coli is not an adequate indicator of Crypto. One option, would be to allow 1
year of E. coli monitoring as a surrogate. Based on results some systems would go
to monitoring for Crypto, while others would be passed out of Crypto monitoring.
- In response to a question Regli explained that presence/absence testing, based on
split samples, has been debated by the TWG. However, there is not enough data to
support this approach. Advice from statistics experts is to assign zero as zero in the
data, even though there is some level of misclassification.
- ICR data indicates there is a relationship between E. coli and turbidity, although it
has not been quantified.
- During the Las Vegas Crypto outbreak there was no rise in E. coli, though there
was a change in total coliform in the month before the outbreak.
- A FACA member noted that spike events may not be captured by monthly
monitoring so risk is never overestimated.
- Regli noted that in determining the acceptable level of risk there is also a question
whether risk must be at a consistent level throughout the year, or if the majority of
the risk can be concentrated into a few days a year.
- The use of the 10-4 risk level is not an EPA policy for pathogens, it is a reference
point.
- Plant efficiency and removal may rise as particulate concentration increases.
Reliability and redundancy is designed into treatment plants specifically to achieve
this goal.
- A FACA member noted that there may be low risk systems which will fall into the
low risk bin that experiences occasional peaks with high probability of outbreaks or
systems with high probability of system failures that could lead to outbreaks.
EPA explained that to make the Framework approach to microbial protection work the
FACA will need to decide:
1. On a monitoring strategy to place systems into low, medium and high risk bins;
2. On appropriate bins and markers; and
3. On required actions for systems in each bin.
UV: Viability of UV for Treating Drinking Water
EPA, a large utility, and a UV manufacturer each provided a presentation on UV.
UV Disinfection: Technology Performance and Availability: An EPA
Perspective
Dan Schmelling, EPA, presented EPA's perspective on UV technology [Attachment
IV.a]. Schmelling reviewed the following concerns regarding use of UV that remain to
be addressed:
1. Efficacy of UV to inactivate pathogens and dose response relationship. UV
(expressed as mJ/cm2) equals irradiance (mW/cm2) times contact time. Typical UV
doses for water disinfection range from 30 - 140 mJ/cm2. Log inactivation of
bacterial pathogens is reported at doses of 3 - 34 mJ/cm2.
- Viruses are the most UV resistant pathogens: 4-log inactivation of many viral
pathogens reported at doses of 7 - 50 mJ/cm2 and 4-log inactivation of
Adenovirus is reported at doses of 120 to 140 mJ/cm2
- Cryptosporidium data includes 4 large independent data sets which suggests at least
3-log inactivation at 20 mJ/cm2. Studies by Sobsey and Linden indicate Crypto
does not reactivate following UV inactivation.
- Giardia data includes 6 independent data sets which suggest at least 3-log
inactivation of G. lamblia at 20 mJ/cm2. G. muris may be slightly more resistant
Schmelling concluded that UV can inactivate high levels of waterborne pathogens at
feasible doses and is effective against bacteria, viruses, Giardia, and Cryptosporidium.
UV is highly effective in multi-barrier approach.
4. Current use of UV in water treatment. Information was gathered from six UV
manufactures and 431 UV drinking water plants (> 0.1 MGD). Most of these plants
are in Europe (7 of 431 are in the United States) and approximately half use surface
water. Existing UV plant median design flow is 0.53 MGD and the maximum design
flow is 53.2 MGD. Over 90% of the UV plants were installed after 1990. The largest
individual UV reactors (Wedeco) is 15 MGD and UV use in drinking water plants is
increasing around the world.
5. Applicability of UV to different types of systems.
- Conventional plants: UV is currently used most often in smaller plants. For use in
larger plants, the size and number of UV reactor vessels is increased. For very
large plants customized designs may be required.
- Softening plants: Fouling studies indicate that hardness levels in filter effluent
from softening plants will not preclude use of UV. Mackey et al. reported
equivalent performance in softening and conventional plants in pilot study
3. Performance and reliability of critical UV system components (e.g., sensors) is
addressed through validation protocols. Germany has developed standards for UV
use and operation which include support documentation, standards for sensors, full
scale bioassay, and continuous monitoring. Eight manufacturers are currently
certified under the German certification program.
4. Feasibility: UV industry has the capacity to meet new demand. A conservative
estimate is that the UV industry currently has capacity to develop 300 - 500 systems
per year and the supply of components to UV reactors (e.g. lamps, sensors, reactor
vessels) is not constrained. Limiting factors for widespread implementation are the
limited design experience in US consulting firms, lack of state approval process, lack
of regulatory standards (IT tables) or validation protocols, and little operational
experience in US water treatment.
5. Risk associated with breakage of mercury vapor UV lamps is low. EPA has
identified no catastrophic on-line failure of low pressure lamps and three cases of
medium pressure lamps shattering on-line (EPA estimates that there are at least
50,000 medium pressure lamps in service). Risk is mitigated through standard
operating procedures and training, equipment design, thermal sensors and alarms, and
placement of unit within treatment train. Risk of mercury contamination is low and
manageable with standard operating procedures.
Application of UV Technology for Drinking Water Treatment - A Utility
Perspective
Roy Wolf, Metropolitan Water District of Southern California (MWDSC), presented
MWDSC's perspective on UV technology [Attachment VI.b]. In summary Wolf made
the following points: UV may offer benefit as multiple barrier for Crypto that must be
used with other disinfectants; UV implementation is site specific and large utilities face
unique challenges to implementing new technologies; and UV should be included in the
toolbox of options for utilities.
Wolf concluded that UV is not ready for use as Best Available Technology (BAT) for
Stage 2 schedule (see discussion below) and outlined criteria that he would proposed to
be used to determine UV's commercial readiness:
- Identification of required dose for UV disinfection of Crypto, Giardia, and viruses;
- Resolution of problems with measurement methods to determine UV dose applied
to water;
- UV monitoring issues (sensors);
- Use of other disinfectants/oxidants; and
- Resolve implementation concerns for medium and large-scale plants.
Following Wolf's presentation the FACA discussed what is meant by "Best Available
Technology" (BAT) in the context of the Stage 2 Rule:
- EPA uses BAT to determine if a requirement (e.g., log inactivation) is achievable
and what the costs would be to the industry.
- EPA noted that BAT is a technology that is feasible and will allow systems to meet
a specific Maximum Contaminant Level (MCL). There can be more than one BAT.
- Jim Malley, University of New Hampshire, explained that UV is ready for
widespread application. However, in Malley's opinion it should not be considered
the BAT. Before UV can be considered BAT the following issues must be
resolved:
Operational protocols must be developed;
Mercury issues must be resolved;
There is a lack of experience with large systems (100s million gallons per day
such as NYC or Chicago); and
Taste and odor control issues must be resolved.
Municipal Scale UV Disinfection of Drinking Water - UV Manufacturer's
Perspective
Jon McClean, Hanovia Ltd., presented an overall review of the use of UV technology to
disinfect water including wavelength, operational parameters, measurement and
monitoring technologies, and examples of applications and designs of UV apparatus
[Attachment IV.c]. McClean summarized that, regarding UV's drinking water track
record:
- There are currently over 20,000 potable installations world-wide;
- The largest potable flow, located in Finland, is 74 million gallons/day (mgd);
- Largest effluent flow, located in New Zealand, is 294 mgd;
- The largest UV drinking water installation in the US is in Fort Benton, Montana,
installed in 1987; and
- Municipal UV has been used in Europe since 1950.
Regarding UV's effectiveness McClean concluded:
- No species has demonstrated an ability to resist UV;
- Dose data is well documented by several research groups working independently;
and
- Crypto has been demonstrated to not reactivate.
McClean closed with the following points regarding engineering of UV systems:
- Sensors within UV mechanisms are calibrated and sealed;
- Wipers automatically remove any deposition;
- UV dose = intensity x residence time x transmittance of water;
- Design protocols are robust and fail safe; and
- The technology is mature, the consulting community well informed and the
equipment vendors have the capacity to meet additional needs.
In response to questions from FACA members McClean made the following points;
- UV systems are built with automatic, failsafe, shut downs so untreated water is not
sent into distribution system if the UV system fails.
- 0.4% of lamps fail, only 1 lamp has broken in Hanovia's experience.
- Retrofitting will be a major challenge to UV implementation in the US, however,
80% of Hanovia's experience is with designing UV systems for existing plants.
- EPA added that it does not endorse or otherwise have a relationship with Hanovia
or any other UV manufacturer.
- Water temperature (i.e., cold water) has no effect on effectiveness of UV
technology.
FACA Discussion of UV
FACA members made the following comments regarding UV:
- In drinking water applications UV will face different challenges than in wastewater
applications, such as calcium deposition. The majority of the issues that face
widespread UV implementation concern operations and maintenance, and
reliability.
- EPA's current thinking on UV is that it is an available technology, and it is readily
available to a sub-set of systems.
- There is no measurable residual from UV, therefore you cannot measure from the
water if UV has been applied. Sensors are used inside the UV housing to monitor
level of performance.
- Some organisms have been shown to be capable of repair of DNA after low dose
UV application. However, Crypto is a relatively complex organism and only very
simple organisms are capable of photo reactivation.
- In response to a question from a FACA member Wolf explained that the
wavelength of UV used is the same for all types of pathogens because it is based on
absorption by DNA.
Public Comment
Detection, Treatment, and Management of Cryptosporidium At Philadelphia
Water Department
Howard Neukrug, Director Watersheds - Philadelphia Water Department, and Dr.
Caroline Johnson, PA Dept. of Public Health, presented Philadelphia's experience with
watershed management, Crypto monitoring, filtration and ozone research, disease
surveillance, and citizen involvement and partnerships [Attachment V.a].
During his introduction Neukrug stated that:
- Source water Crypto levels are influenced by wet weather and vary seasonally;
- Existing treatment is highly successful - up to 5.5 log removal has been
demonstrated;
- Pilot studies show no added reduction using ozone; and
- Evidence does not suggest endemic Cryptosporidiosis in Philadelphia is related
to drinking water quality.
Johnson presented surveillance data on the incidence of Cryptosporidiosis from
Philadelphia:
- Documented incidence of Cryptosporidiosis is very low (1 case/100,000) in
Philadelphia, especially in comparison with other notifiable conditions;
- Majority of Cryptosporidiosis cases (>85%) have a known source of exposure or
risk for acquisition of infection; and
- Their interpretation of available evidence does not suggest that endemic
Cryptosporidiosis is related to drinking water quality.
Neukrug concluded that Crypto in drinking water is unlikely to be a major contributor
to any background or endemic level. EPA and FACA should work with utilities by (1)
giving us the opportunity to continue our treatment optimization programs, (2) helping
us strengthen our efforts towards source water protection; and (3) supporting our
efforts to address real environmental and health improvements.
Following the presentation by Philadelphia FACA members made the following
points:
- Regarding the observed similarity between Cryptosporidiosis and giardiasis
occurrence by age distribution, a FACA member noted that the similarity could
be a result of the surveillance system. Another FACA member noted that though
the curves are the same, this does not necessarily mean the same routes of
exposure.
- A FACA member noted that the general level of risk for non-morbid of
Cryptosporidiosis, those infected but not identified as having the disease, is not
known.
- A FACA member pointed out that public health surveillance systems are not
geared to pick up diseases such as Cryptosporidiosis and giardiasis. There are
two or three asymptomatic cases for each symptomatic case that is picked up by
the system.
Engineering Feasibility of UV Disinfection for NYC, Catskill and Delaware
Systems
Orren Schneider, Hazen and Sawyer, presented New York City's study of engineering
feasibility of UV Disinfection. This study was conducted at the request of the New York
City Department of Environmental Protection. The purpose of this study was not as a
conceptual design. Rather, the goal of this study was to determine if it is feasible to
engineer a UV disinfection system for the Catskill and Delaware portions of the NYC
water system. The study examined the available UV systems (lamps and reactor types)
and ancillary support systems (sensors and cleaning systems); the engineering feasibility
and hydraulic issues surrounding a specific NYCDEP site; and conceptual economics for
a recommended system. The study did not look at the scientific basis of UV disinfection
(required doses) or other water quality issues (disinfection by-products and regrowth).
The results of this study appear to indicate that a UV disinfection system could be
engineered to fit at a specific NYCDEP site. Also, preliminary projected costs were
presented.
- In response to a question from a FACA member Orrin explained that NYC has a
gravity system, therefore water will continue to pass through UV apparatus even
if there is a system failure. The amount of time to install the UV system in NY
is unknown.
Countervailing Risk Considerations Important to Evaluation of Bromate
Regulatory Options
Phillippe Daniel, Camp Dresser and McKee, discussed the risk tradeoffs associated with
lowering the bromate MCL [Attachment V.b]. The FACA should take a comprehensive,
systems based approach to considering the bromate MCL. Daniel discussed the
following "challenges" in balancing microbial and DBP risks:
- DBP regulations must consider the mixture composition resulting from source and
treatment factors;
- Assessing DBP health effects is difficult due to incomplete information on DBP
mixtures of interest;
- Technology choices influence far more than DBP mixtures and microbes; and
- The FACA must determine how to regulate individual contaminents while preserving
flexibilty to lower the overall drinking water risk.
Publication of the Oral (Drinking Water) Development Toxicity Study of
Bromodichoromethane in Rabbits.
Keith Christman, Chlorine Chemistry Council, announced the release of the Oral
(Drinking Water) Development Toxicity Study of Bromodichoromethane in Rabbits by
Argus Research Laboratories, Inc [Summary and Conclusions provided as Attachment
V.c].
Discussion of Regulatory Options
Day 2 of the FACA meeting consisted of a discussion among FACA members of
regulatory options. The day included plenary and caucus discussions among FACA
members. The plenary discussion was split into DBP and microbial issues and led to a
narrowing of the regulatory scenarios for discussion at the June 27-28 FACA meeting and
next steps (see below).
At the FACA's request, FACA member Chris Wiant introduced a "conceptual starting
place" for the FACA's discussion of regulatory options. Based on Wiant's discussion
with individual FACA members, he presented a package that he viewed as representing
"common ground." This does not represent an agreement among the FACA members and
was presented only as a starting place for discussion.
Conceptual Starting Place for FACA Stage 2 Discussion
Presented to FACA by Chris Wiant - June 2, 2000 |
Microbial Pathogens
Monitoring for Crypto:
- Use of a surrogate for Crypto?
- Difference between large, medium and small system monitoring requirements
- Analytical difficulties of monitoring Crypto
If system is in "High" Crypto bin:
- Source water protection credit (if possible)
- If not, chance to effect source water or watershed then toolbox (membranes,
ozone, UV, in bank filtration, others.)
- Reliability of systems - plant reliability credit?
- How to define/use BAT (UV)
- How to stratify utilities into bins and bin parameters (e.g., 0.03, 0.1, 1.0)
- Are there ways to do multiple barriers that are equivalent to inactivation
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Disinfection ByProducts (DBPs)
80 TTHMs/60 HAAs
- How can we be sure that we achieve temporal and spatial equity?
- Methods of averaging (RAA, LRAA, etc.)?
Action Level
- Based on single high (SH) trigger level
- Toolbox - required if action level is exceeded with some frequency
- Intended as an incentive for prevention
Monitoring
- Quarterly
- Monthly (if action level triggered)
- Phased (action level exceedences trigger more frequent monitoring)
Reliability
- Operations and Maintenance
- Distribution System
Bromate
- 5 MCL
- 10 MCL (current Stage 1 level)
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The FACA members discussed Chris Wiant's approach. Below is a summary of the
overall discussion, the summary also identifies the issues to be discussed by the FACA:
FACA discussion of microbial issues
The FACA did not reach consensus on the following, however, all that participated in the
discussion appeared comfortable at the time with concepts in the following bullets:
- The FACA is concerned if there are "high" levels of Crypto in the raw water.
- Many systems are currently addressing meeting protective goals; there is not a
need to require these systems to do more treatment (it is unclear whether
parties' desire continued monitoring for these systems).
- There are a subset of utilities at high risk for Crypto in raw water: these
systems need to address this through use of toolbox options - [inactivation,
treatment or membranes].
- Objective criteria are needed to minimize transactional costs in accepting tool
box options.
Microbial Scenario Under Discussion
- Monitor in order to characterize whether a system is at "high risk" for
presence of Crypto in the source water.
- If in a high Crypto bin, address through:
- Source water protection, if possible
- Application of multiple barriers (membranes, ozone, UV, inbank filtration,
or other items from the tool box)
- Differentiate monitoring requirements for large, medium, small systems.(2)
Microbial Issues That Need Further Discussion
- What to do about unfiltered systems?
- Bin boundaries (..03, 1,.)
- How many bins? (3,4?)
- What tool box options should pertain to each bin?
- Number of systems affected
- Costs
- Monitoring:
- Differentiate frequency and type of monitoring required and techniques
used between large, medium, small systems
- One suggestion: require large systems (>100K) to monitor for Crypto;
Allow small systems to use indicator; if indicator level is exceeded,
Crypto monitoring would be triggered.
- Question about monitoring for E.Coli, turbidity as surrogates to Crypto
- Possibly conduct research on using E.Coli or other index as a surrogate
within a certain time frame
- Allow small systems to use other indicator (turbidity, E.Coli, monitor
finished water - there is a question about technical feasibility of this)
- Can EPA develop criteria to characterize source waters? And if designated as
meeting water quality criteria, would the utility be dismissed from monitoring
under LT2ESWTR? (develop water quality criteria for microbial pathogens for a specific stream
reach, if the stream reach meets criteria)
- Questions about, who would develop assessment, what amount of monitoring is
needed to define drinking water use, how to define drinkable.
- What process would be developed to address the questions above?
- If characterized as in a "high bin"; or [if applicablea "moderate bin"], what
would utility be required to do?
- Ideas discussed:
- Use of multiple barriers defined as broadly as possible (Recognize
membranes/removal/inactivation)
- Source water protection
- Involvement in Partnership., get credit
- Removal
- Inactivation
- Tool box
- Few transaction costs as possible
- Use of toolbox as automatic/objective as possible
- For small systems
- Those in high risk waters monitor finished water, if test becomes
available.
- Need to provide help to states
- Resources
- Training
- Recognize changes in state role
- Require more highly trained professionals
- Distribution Systems
FACA discussion of disinfection byproduct issues
DBP Scenario under discussion
- 80/60 Standard. Recognize spatial and temporal equity issues. Address these
issues with a combination of an MCL standard and an enforceable action
level.
- Locational Running Annual Average MCL or Annual Average of the Max
MCL
- Action Level
When action will be triggered (e.g., frequency and level at which Action Level
is exceeded). To be determined. Response to action level is exceedences to be
determined.
Response to action level exceedence will be taken from a DBP toolbox of
activities, which will include incentives.
DBP Issues That Need Further Discussion
- Use of LRAA or AAM. The FACA did not reach a conclusion about
whether to use the LRAA or the AAM.
- Monitoring scheme
- What level of monitoring is needed to identify peaks?
- Quarterly samples?
- Quarterly samples during particular seasons?
- Monthly samples?
- Other scheme?
- If after monitoring, over a period of time (to be determined), there are
no exceedences, monitoring frequency could be reduced.
- Action Level exceedence
- When would an action level be triggered (80/60; 100/75..)
- What would happened if the action level was triggered multiple times
(two, three.)
- Would there be a phased approach where certain, as yet undefined
exceedences would trigger activities (actions undefined)
- Public notification stage
- When would this be required, what type of public notification would
be required, and how would this be required?
- Reliability of the distribution system
- What are the unintended consequences of this approach?, Will there be
a loss in microbial protection?
- To what extent could a benchmark approach as in Stage 1 or
LTESWTR prevent loss of microbial protection?
- Toolbox
- What is in the toolbox to address exceedences?
- Use of tools needs to result in verifiable measurable results
- Bromate 5, 10/ppb on the table
- We now have the ability to detect bromate at 5/ppb
- Issue is whether to lower standard, impact on utilities currently using
ozone, and the impact on utility technology choices.
- What are the other environmental costs for those systems that have to use
control measures to achieve a 5ppb bromate level?
Next Steps
- June 14 FACA Subgroup Meeting Scheduled
A FACA subgroup meeting was scheduled for Wednesday, June 14th in Denver
Colorado. The meeting will be held at the Denver offices of MEC, Inc. The
meeting will be attended by a subgroup of FACA members.
- June Follow up Activities
The schedule for developing the "one-text" for the possible FACA agreement will
be:
June 8: Abby will circulate a brief summary of the discussion from the meeting
on June 2nd.
June 14: a sub-group of FACA members will meet in Denver to continue to
discuss issues raised on June 2nd.
June 20: Abby will circulate to FACA members a revised "one-text" with
comments suggested by FACA members and the results of the Denver meeting.
June 27-28: FACA meeting in Washington
- July 28 FACA meeting date added
The FACA decided to expand the July 27 meeting to two days. The meeting is
now scheduled for July 27 and 28th.
- June 7-8 TWG meeting cancelled
The FACA decided to cancel the TWG meeting in June 7-8. The TWG may be
asked to provide further analysis after the June 14th meeting in Denver.
Adjourn
1.
* For copies of the notebook materials contact Eddie Scher at [escher@resolv.org] or 202-965-6203.
2.
1 Large = >100,000 population; Medium = 10,000-100,000; and Small = <10,000.
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