Stage 2 D/DBP Rule Update Michael W. Deal Compliance Assurance Section Central Office
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Stage 2 D/DBP Rule
Update
Michael W. Deal Compliance Assurance Section Central Office
• Stage 2 rule update
• Key changes
• Implementation
• OELs, MCLs
• Paths to compliance
• Success story
Stage 2 D/DBP Rule Update • Following full implementation in 2013, continue to work with
many systems to reduce DBPs in distribution
• OEL report process is providing a “warning” of elevated DBP levels and begins collaboration
• Operators have responded by optimizing treatment and managing distribution system to lower DBPs
• Greater use of in-tank aeration coupled with active tank-mixing has significantly reduced DBP levels in systems that were ongoing MCL violators
Stage 2 D/DBP Rule
• Locations with highest levels of DBPs
• Sample monitoring plan
• Locational Running Annual Average (LRAA)
• Consecutive system MCL compliance
• Operational Evaluation Level (OEL)
Monitoring Location Changes
1. Site access issues
2. Distribution system changes
• Locations selected by PWS
• Alternate between high TTHM and high HAA5
• Resubmit Sample Monitoring Plan
• Templates and guidance available on web
Every 90 Day Monitoring
• Scheduled seven-day window
• ± five-day grace period (only in same month)
• Resampling permitted if problem with first sample
• Must be in same month
• Contact Ohio EPA for resampling waiver
Reduced Monitoring
• Eligible after four consecutive quarters of monitoring
• Must maintain an LRAA < 40 µg/L for TTHM and < 30 µg/L for HAA5
• Surface water systems must maintain an RAA < 4 mg/L for TOC in raw water
Operational Evaluation Level
• Calculation:
Quarter 1 + Quarter 2 + 2*(Quarter 3)
4
• Primary Goal: help prevent MCL exceedances
through advanced warning • Secondary Goal: encourage PWSs to address
locations with seasonal DBP issues
OEL Exceedance • Early warning, not a violation
• No public notice requirement
• OEL Report in 90 days
• Begins collaboration between PWS and Ohio EPA
• Calculated at each location
• Can be at one or more monitoring location(s)
• TTHM or HAA5
329 Exceedances
90% TTHM
OEL Exceedances (Aug. 2012 to Apr. 2016)
Statewide
Maximum Contaminant Level
• Based on LRAA
• Calculated at each location
• Can be at one or more monitoring location(s)
• TTHM or HAA5
• Tier 2 Public Notice
256 Exceedances
84% TTHM
MCL Exceedances (Dec. 2012 to Apr. 2016)
Statewide
MCL Exceedances
• Statewide, the number of DBP MCL exceedances has decreased
• Continue to have individual DBP “hotspot” issues in many systems, including purchased surface water systems - especially in warmer months.
0
5
10
15
20
25
30
35
Nu
mb
er
of
MC
L V
iola
tio
ns
Number of Quarterly MCL Violations Statewide
Paths to compliance: Investigation
• Where and when are my DBP issues?
• Special purpose samples – DBPs, Cl, TOC, etc.
• Point of purchase samples
• Water age calculations
• Isolated changes
• Consulting engineers
• On-site analyzers for quick results
Paths to compliance: Investigation
Parker Hannifin THM Analyzer
THM-100 Online THM Analyzer
• Bench-top unit • Purge and trap GC • 30-minute analysis • Uses helium gas
• Online and “grab” sampling • Purge and trap GC • Self-calibrating • Can be set to monitor every hour 24/7
Paths to compliance: Optimization
• Organic removal
• Flushing program
• Chlorine residual management
• Alternative disinfection
• Preventative tank maintenance – Increase turnover
– Increase mixing
Paths to compliance: Investigation
• Remove precursors – Enhanced coagulation/softening – Activated carbon absorption – Anion exchange – Membrane filtration
• Remove formed DBPs – Tank mixing and aeration with power
ventilation for TTHM removal – GAC filtration and biological
degradation for HAA5 removal
Stage 2 Success Story
• 3 MGD SW plant in NW Ohio
• Exceeded TTHM LRAA in 2012, 2013 and 2014
• Orders signed May 2012
• Plans approved March 2013
• Installation complete July 2014
Trihalomethane Removal System
• TRS
• Three Components
1. Active mixing
2. Spray aeration
3. Power ventilation
• Customized to each tank according to design, size, flow, etc.
TRS Validation Data
010203040506070
9/8
/20
14
9/1
0/2
01
4
9/1
2/2
01
4
9/1
4/2
01
4
9/1
6/2
01
4
9/1
8/2
01
4
9/2
0/2
01
4
9/2
2/2
01
4
9/2
4/2
01
4
9/2
6/2
01
4
9/2
8/2
01
4
9/3
0/2
01
4
10
/2/2
01
4
TTH
M (
µg/
L)
Clearwell
0
20
40
60
80
100
120
11
/3/2
01
4
11
/5/2
01
4
11
/7/2
01
4
11
/9/2
01
4
11
/11
/20
14
11
/13
/20
14
11
/15
/20
14
11
/17
/20
14
11
/19
/20
14
11
/21
/20
14
11
/23
/20
14
11
/25
/20
14
11
/27
/20
14
TTH
M (µ
g/L)
Tank 1 96% reduction
0
20
40
60
80
100
10
/6/2
01
4
10
/8/2
01
4
10
/10
/20
14
10
/12
/20
14
10
/14
/20
14
10
/16
/20
14
10
/18
/20
14
10
/20
/20
14
10
/22
/20
14
10
/24
/20
14
10
/26
/20
14
10
/28
/20
14
10
/30
/20
14
TTH
M (
µg/
L)
Tank 2 77% reduction • All samples taken in a.m.
• End of drain cycle
• Each TRS isolated for validation
40% reduction
Compliance Data
• Two compliance sites
• Noticeable difference between 3Q2013 and 3Q2014
• Remained in compliance with the MCL
0
20
40
60
80
100
120
140
160
1Q
20
13
2Q
20
13
3Q
20
13
4Q
20
13
1Q
20
14
2Q
20
14
3Q
20
14
4Q
20
14
1Q
20
15
2Q
20
15
3Q
20
15
4Q
20
15
1Q
20
16
TTH
M u
g/L
DS201
DS202
Take Home
• Stage 2 rule focus on “hotspots”
(LRAA) and early warning (OEL) • Most exceedances in Ohio are
TTHM in the Northern counties • System can avoid enforcement
by early action • Start investigation early when
high levels are first observed • Optimization and treatment
strategies are unique for each system
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