Development of the Stage 2 Disinfectants and Disinfection Byproducts Rule Tom Grubbs, USEPA November - PowerPoint PPT Presentation

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Development of the Stage 2 Disinfectants and Disinfection Byproducts Rule Tom Grubbs, USEPA November

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Title: Development of the Stage 2 Disinfectants and Disinfection Byproducts Rule Tom Grubbs, USEPA November


1
Development of the Stage 2 Disinfectants and
Disinfection Byproducts Rule Tom Grubbs,
USEPA November 1, 2007
2
Overview
  • DBP regulatory history
  • Stage 2 DBPR background information
  • Stage 2 DBPR requirements
  • Schedule
  • IDSE
  • MCLs and monitoring
  • Compliance and treatment options
  • Available resources

3
1979 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

4
1998 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

5
Stage 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

6
Stage 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

7
Stage 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.

8
MCLs for DBPs
40 CFR 141.64
  • TTHM and HAA5 MCLs remain the same
  • Calculating compliance changes
  • Stage 1 RAA vs. Stage 2 LRAA

9
RAA 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
10
Population 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

11
Stage 2 DBPR Schedules
12
Implementation 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
13
IDSE 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

14
Standard 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

15
System 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

16
System 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

17
40/30 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

18
VSS 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

19
Stage 2 DBPR
Compliance Monitoring Location
141.605
  • Surface water and GWUDI systems and systems that
    purchase surface or GWUDI

20
Stage 2 DBPR
Compliance Monitoring Location
141.605
  • Ground water systems and systems that purchase
    ground water

21
Stage 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.

22
Schedule
141.620
Schedule for systems in a combined distribution
system is based on that of the largest system in
the combined distribution system
23
Other 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

24
Compliance 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

25
Compliance 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

26
Stage 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

27
Stage 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

28
Stage 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
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