Title: Development of the Stage 2 Disinfectants and Disinfection Byproducts Rule Tom Grubbs, USEPA November
1Development of the Stage 2 Disinfectants and
Disinfection Byproducts Rule Tom Grubbs,
USEPA November 1, 2007
2Overview
- DBP regulatory history
- Stage 2 DBPR background information
- Stage 2 DBPR requirements
- Schedule
- IDSE
- MCLs and monitoring
- Compliance and treatment options
- Available resources
31979 TTHM Rule
- TTHM MCL of 0.10 mg/L
- Compliance based on running annual average
- Requirements applied to systems serving at least
10,000 people - Systems lt10,000 were not included due to concerns
about their ability to simultaneously control
TTHM and pathogens - There were no specified requirements for pathogen
treatment other than turbidity standards
41998 Stage 1 DBPR
- Lower MCL for TTHM, new MCLs for HAA5, bromate,
chlorite - MRDLs for chlorine, chloramine, chlorine dioxide
- Extended compliance requirements to systems
serving lt10,000 - Subpart H systems with conventional filtration
treatment had to meet TOC removal treatment
technique - Staggered compliance schedule
5Stage 2 DBPR Background
- EPA required by 1996 SDWAA to develop Stage 2
- Things learned through ICR data analysis,
implementation, etc. - DBP formation in the distribution system more
complex than previously thought - Consecutive systems not adequately protected
- Treatment plant-based monitoring inadequate
- EPA chartered a federal advisory committee (FAC)
to develop recommendations to regulate DBPs and
pathogens as needed - Beyond Stage 1 and IESWTR/LT1ESWTR
- Supported by a technical workgroup
6Stage 2 DBPR Background (cont.)
- FAC signed Agreement in Principle in September
2000 - Final rule consistent with FAC recommendations,
public comments - Builds on existing rules in M-DBP Suite
- Provides greater public health protection and
equity through risk targeting - Initial distribution system evaluations (IDSE) to
identify compliance monitoring locations with
high DBPs - Basing compliance on Locational Running Annual
Averages (LRAAs) and population-based monitoring - Specifying requirements for consecutive systems
7Stage 2 DBPR Definitions
40 CFR 141.2
- Combined distribution system (CDS)
Interconnected distribution system consisting of
the distribution system of wholesale systems and
consecutive systems that receive finished water. - Consecutive system PWS that receives some or
all of its finished water from one or more
wholesale systems. - Finished water Water introduced into the
distribution system of a PWS intended for
distribution and consumption without further
treatment, except as necessary to maintain water
quality in the distribution system. - Wholesale system PWS that treats source water
as necessary to produce finished water and then
delivers some or all of that finished water to
another PWS.
8MCLs for DBPs
40 CFR 141.64
- TTHM and HAA5 MCLs remain the same
- Calculating compliance changes
- Stage 1 RAA vs. Stage 2 LRAA
9RAA vs. LRAA
1st Quarter
2nd Quarter
3rd Quarter
4th Quarter
RAA of Quarterly Averages Must be Below MCL
(
)
4
(
)
4
EACH LRAA MUST BE BELOW MCL
)
(
4
)
(
4
10Population Based Monitoring
- Required for both IDSE and Compliance Monitoring
- Based on system population/source water type
- Targets DBP problem areas based on better
understanding of DBP occurrence and formation - Easier to implement for systems and states
- Greater equity of public health protection
- Addresses issues associated with part-time
treatment plants and sources, multiple wells,
consecutive systems, too few or too many samples
to characterize DBP occurrence
11Stage 2 DBPR Schedules
12Implementation Schedule
2006
2013
2012
2007
2010
2011
2009
2008
2014
2015
2016
Possible Extension
Treatment Installation
Crypto monitoring
1
IDSE
Review submission
Compliance
Treatment Installation
Crypto monitoring
Possible Extension
2
IDSE
Review submission
Compliance
Treatment Installation
Crypto monitoring
Possible Extension
3
IDSE
Review submission
Compliance
Compliance (if Crypto Monitoring)
Possible Extension
E. coli
Crypto monitoring
4
IDSE
Review submission
Treatment Installation
Compliance (if no Crypto Monitoring)
2006
2013
2012
2007
2009
2008
2014
2015
2016
2010
2011
Includes associated consecutive systems
13IDSE General Requirements
141.600
- Purpose
- Determine locations of high TTHM and HAA5
concentrations throughout distribution system - Results are used in conjunction with Stage 1 DBPR
compliance monitoring to identify and select
Stage 2 DBPR compliance monitoring locations - Applicability
- CWS (and NTNCWS serving 10,000) that uses or
delivers water that has been treated with a
primary or residual disinfectant other than UV
light
14Standard Monitoring
141.601
- Standard monitoring sampling locations
- Must be different from existing Stage 1
monitoring locations - Must be distributed throughout distribution
system - Distribution System Schematics are not CBI and
therefore are subject to the Freedom of
Information Act (FOIA). - System will continue to conduct compliance
monitoring at existing Stage 1 DBPR locations
15System Specific Study Existing Monitoring
141.602
- Existing Monitoring Results
- Based on samples collected and analyzed according
to analytical requirements - Minimum Requirements
- Collected no earlier than 5 years prior to study
plan submission date - Each location must be sampled once during month
of highest TTHM/HAA5 or highest water temperature
for each 12 months of data submitted - Must include all Stage 1 DBPR compliance
monitoring results plus additional results as
necessary to meet minimum number of sample
requirements
16System Specific Study Hydraulic
Modeling
141.602
- Extended period simulation hydraulic model
- Simulate 24 hour variation in demand show
consistently repeating 24 hour pattern of
residence time - Must represent key distribution system components
- Model must
- Be calibrated or have calibration plans for the
current configuration of the distribution system
during the period of high TTHM formation
potential - Evaluate all storage facilities
- Calibration completed NLT 12 months after SSS
plan submission - System must conduct one round of TTHM/HAA5
monitoring during that period
1740/30 Certification
141.603
- Eligibility
- All required Stage 1 DBPR (Subpart L) compliance
samples have been taken - No individual sample exceeded 0.040 mg/L for TTHM
- No individual sample exceeded 0.030 mg/L for HAA5
- No TTHM or HAA5 monitoring violations
- Based on recent two-year window
18VSS Waivers
141.604
- Eligibility
- Systems serving lt 500 persons
- Must have taken TTHM and HAA5 samples
- Stage 2 Compliance
- Monitor at Stage 1 DBPR compliance monitoring
locations for Stage 2 DBPR compliance monitoring
- Complete Standard Monitoring or System Specific
Study if - System has not taken TTHM and HAA5 samples or
- State requires it
19Stage 2 DBPR
Compliance Monitoring Location
141.605
- Surface water and GWUDI systems and systems that
purchase surface or GWUDI
20Stage 2 DBPR
Compliance Monitoring Location
141.605
- Ground water systems and systems that purchase
ground water
21Stage 2 DBPR
Monitoring Plan
141.622
- Monitoring Plan must include
- Monitoring locations dates
- Compliance calculation procedures
- Monitoring plans for any other systems in the CDS
if the state has modified monitoring requirements - Complete no later than date you must conduct
initial monitoring. - Revise as needed to reflect changes in treatment,
distribution system operations, layout, or other
factors that could affect TTHM or HAA5 formation
in consultation with State - Plan must be kept on file for State and public
review.
22Schedule
141.620
Schedule for systems in a combined distribution
system is based on that of the largest system in
the combined distribution system
23Other Stage 2 Provisions
- Modifies eligibility for reduced bromate
monitoring - Clarifies eligibility for reduced DBP monitoring
for subpart H systems without conventional
filtration - Requires disinfectant residual monitoring by
consecutive systems - Requires operational evaluations by systems with
high DBP levels prior to violation - Updates PN and CCR requirements
24Compliance Approaches
- System, in consultation with the State, chooses
the compliance approach - Take into account magnitude/nature of the
problem, existing treatment, source water
characteristics, costs, technical capabilities,
co-occurring contaminants - This is a site-specific decision
- THERE IS NO SILVER BULLET
- Optimize or modify current operations
- Move point of disinfection or change
predisinfectant - Improve precursor removal through EC/ES
- Modify distribution system operations to reduce
water age, add booster chlorination
25Compliance Approaches (cont.)
- Change primary or secondary disinfectant
- Primary switch to ozone, chlorine dioxide, UV
- Secondary switch to chloramine
- Improve precursor removal
- Membranes, GAC
- Miscellaneous
- Change source water, consolidate with other
systems - Keep simultaneous compliance issues in mind
check before you change
26Stage 2 Resources
- Guidance manuals
- Initial Distribution System Evaluation (IDSE)
Guidance Manual - IDSE Guide for Systems Serving lt 10,000
- Operational Evaluation Guidance Manual
- Stage 2 DBPR Implementation Guidance
- Stage 2/ LT2 Simultaneous Compliance Guidance
- Stage 2 DBPR Small System Compliance Document
- Consecutive System Guidance Manual
27Stage 2 Resources (cont.)
- Factsheets
- IDSE Standard Monitoring
- IDSE System Specific Study
- IDSE Very Small System Waiver 40/30
Certifications - IDSE Tool
- Designed to help systems determine their IDSE
requirements and prepare submit sampling plans
reports
28Stage 2 Resources (cont.)
- Stage 2 DBPR Website
- http//www.epa.gov/safewater/disinfection
- Final Rule Preamble
- Guidances, Manuals, Fact Sheets
- Link to the IDSE Tool, DCTS
- Contact List by State
- Searchable QA
- LT2ESWTR/Stage 2 DBPR Implementation Team
- Stage2mdbp_at_epa.gov